Home About us Contact
|
Home About us Contact | ||
|
|
||
DBH
Kinds of DBH Selected AbstractsPostfledging habitat selection of juvenile middle spotted woodpeckers: a multi-scale approachECOGRAPHY, Issue 4 2009Carlos Ciudad Despite its relevance for the persistence of populations, the ecological mechanisms underlying habitat use decisions of juvenile birds are poorly understood. We examined postfledging habitat selection of radio-tracked juvenile middle spotted woodpeckers Dendrocopos medius at multiple hierarchically-nested spatial scales in NW Spain. At the landscape and home range scales, old oak forest was the most used and selected habitat, young oak forests and pine plantations were avoided, and riverside forests were used as available. At a lower scale, birds selected larger diameter trees for foraging. Home ranges had higher densities of large deciduous trees (mainly oaks Quercus spp., but also poplars Populus spp. and willows Salix spp. >22,cm and >33,cm DBH) selected for foraging by juveniles than non-used areas. These results suggest that foraging conditions may drive, at least partly, habitat use decisions by juvenile birds. We also discuss the potential influence of intraspecific competition, the search for a future breeding territory in the early postfledging period and predation avoidance on habitat use decisions by juvenile birds. Contrary to previous studies on migrant forest birds, postfledging juvenile woodpeckers selected the same habitat as for the breeding adults (i.e. old oak forest), indicating that migrant and resident specialist avian species may require different conservation actions. Conservation strategies of woodpecker populations should consider the protection of old oak forests with high densities of large trees to provide suitable habitat to breeding adults and postfledging juveniles. The habitat improvement for this indicator and umbrella species would also favour other organisms that depend on characteristics of old-growth oak forests. [source] Substance induced plasticity in noradrenergic innervation of the paraventricular hypothalamic nucleusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2003Arthur S. P. Jansen Abstract Single administration of the cytokine interleukin-1, (IL-1), or the psychostimulant amphetamine, enhanced adrenocorticotropin hormone and corticosterone responses to a stress challenge weeks later. This long-lasting hypothalamic-pituitary-adrenal (HPA)-sensitization is paralleled by an increase in electrically evoked release of noradrenaline in the paraventricular hypothalamic nucleus (PVN). We hypothesized that these functional changes may be associated with morphological plasticity of noradrenergic projections to the PVN, a parameter that shows high reproducibility. Specific alterations in relative (nor)adrenergic innervation density were studied by using dopamine-,-hydroxylase (DBH) as a marker. An image analysis system was used to detect changes in the relative DBH innervation density of the PVN. Groups of adult male rats were given IL-1 (10 µg/kg i.p.), amphetamine (5 mg/kg i.p.), or saline. Three weeks later, IL-1 and amphetamine primed rats showed enhanced adrenocorticotropin hormone and corticosterone responses to an amphetamine challenge. In another set of experiments, the relative DBH innervation density was measured in different PVN subnuclei at four rostro-caudal levels. Single administration of either IL-1 or amphetamine causes three weeks later a selective decrease in relative DBH innervation density in those subnuclei of the PVN that contain high numbers of corticotrophin-releasing hormone (CRH) producing neurons: the dorsal parvocellular and medial parvocellular PVN. We conclude that (1) long-lasting sensitization induced by single exposure to IL-1 and amphetamine induces specific pattern of neuroplastic changes in (nor)adrenergic innervation in the PVN and (2) reduction of relative DBH innervation density in CRH-rich areas is associated with paradoxical increase of electrically evoked release of (nor)adrenaline. [source] Anisogramma virgultorum on saplings of Betula pendula and Betula pubescens in a district of northern SwedenFOREST PATHOLOGY, Issue 4-5 2002J. WITZELL Summary During the autumn of 1999, the occurrence of the ascomycete Anisogramma virgultorum on saplings of Betula pubescens and Betula pendula was studied in two stands of B. pubescens, two stands of B. pendula and two mixed (B. pubescens and Pinus sylvestris) stands (age approximately 10 years, mean height 2,4 m, d.b.h. 10,20 mm) in a district in the vicinity of Umeå, northern Sweden. Stem and branch cankers associated with A. virgultorum were found on 54.8% of the investigated saplings, without significant difference between B. pendula and B. pubescens. Cankers were observed on 16.0% of stems and on branches of 54.2% of the saplings. Stem cankers appeared on the current year's shoot, as well as at the base of the trees. The mean diameter of the damaged saplings was significantly greater than the mean diameter of undamaged saplings. All samples of cankers with stromata examined in the laboratory showed perithecia with asci. Résumé Anisogramma virgultorum sur jeunes plants de Betula pendula et Betula pubescens dans un district du nord de la Suède Pendant l'été 1999, le développement de l'ascomycète Anisogramma virgultorum a étéétudié sur de jeunes plants de Betula pendula et Betula pubescens dans deux peuplements de B. pubescens, deux peuplements de B. pendula et deux peuplements mélangés (B. pubescens et Pinus sylvestris) (âge: environ 10 ans, hauteur moyenne: 2 à 4 m, dbh: 10 à 20 mm), dans un district près d'Umeå au nord de la Suède. Des chancres de tige et de branches associés àA. virgultorum ont été trouvés sur 54,8% des plants, sans différences significative entre B. pendula et B. pubescens. Les chancres de tige étaient présents sur 16% des plants, et les chancres de branches sur 54,2%. Les chancres de tige étaient situés sur les pousses de l'année en cours aussi bien qu'à la base des arbres. La diamètre moyen des plants attaqués était significativement plus grand que celui des arbres sains. Tous les chancres avec stromas examinés au laboratoire présentaient des périthèces avec des asques. Zusammenfassung Anisogramma virgultorum an Sämlingen von Betula pendula und Betula pubescens in einem Distrikt in Nordschweden Im Herbst 1999 wurde das Vorkommen des Ascomyceten Anisogramma virgultorum an Betula pubescens und Betula pendula in jeweils zwei Reinbeständen dieser Baumarten sowie in zwei Mischbeständen (B. pubescens und Pinus sylvestris) in einem Distrikt in der Nähe von Umeå, Nordschweden, untersucht (Alter ca. 10 Jahre, mittlere Baumhöhe 2,4 m, DBH 10,20 mm). Bei 54,8 % der untersuchten Bäumchen wurden an Stamm und Zweigen Krebse gefunden, die für A.virgultorum typisch sind. Zwischen B. pendula und B. pubescens gab es keine signifikanten Unterschiede. Bei 16 % der Pflanzen wurden Krebse an den Stämmen, bei 54,2 % an den Zweigen beobachtet. Die Stammkrebse traten sowohl am diesjährigen Gipfeltrieb auf als auch an der Stammbasis. Der mittlere Durchmesser geschädigter Pflanzen war signifikant grösser als derjenige von ungeschädigten Pflanzen. Alle Proben von Krebsen mit Stromata, die im Labor untersucht wurden, enthielten Perithecien mit Asci. [source] Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seekingGENES, BRAIN AND BEHAVIOR, Issue 4 2009A. Heck Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic (SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2) and dopaminergic genes (SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH), which have been previously reported to be implicated with personality traits. One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire. From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking. The effect of rs927544 could be replicated for the novelty seeking subscale extravagance, and the same SNP was also associated with extravagance inthe combined samples. Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype. [source] Mutations in human monoamine-related neurotransmitter pathway genes,HUMAN MUTATION, Issue 7 2008Jan Haavik Abstract Biosynthesis and metabolism of serotonin and catecholamines involve at least eight individual enzymes that are mainly expressed in tissues derived from the neuroectoderm, e.g., the central nervous system (CNS), pineal gland, adrenal medulla, enterochromaffin tissue, sympathetic nerves, and ganglia. Some of the enzymes appear to have additional biological functions and are also expressed in the heart and various other internal organs. The biosynthetic enzymes are tyrosine hydroxylase (TH), tryptophan hydroxylases type 1 and 2 (TPH1, TPH2), aromatic amino acid decarboxylase (AADC), dopamine beta-hydroxylase (D,H), and phenylethanolamine N -methyltransferase (PNMT), and the specific catabolic enzymes are monoamine oxidase A (MAO-A) and catechol O -methyltransferase (COMT). For the TH, DDC, DBH, and MAOA genes, many single nucleotide polymorphisms (SNPs) with unknown function, and small but increasing numbers of cases with autosomal recessive mutations have been recognized. For the remaining genes (TPH1, TPH2, PNMT, and COMT) several different genetic markers have been suggested to be associated with regulation of mood, pain perception, and aggression, as well as psychiatric disturbances such as schizophrenia, depression, suicidality, and attention deficit/hyperactivity disorder. The genetic markers may either have a functional role of their own, or be closely linked to other unknown functional variants. In the future, molecular testing may become important for the diagnosis of such conditions. Here we present an overview on mutations and polymorphisms in the group of genes encoding monoamine neurotransmitter metabolizing enzymes. At the same time we propose a unified nomenclature for the nucleic acid aberrations in these genes. New variations or details on mutations will be updated in the Pediatric Neurotransmitter Disorder Data Base (PNDDB) database (www.bioPKU.org). Hum Mutat 29(7), 891,902, 2008. © 2008 Wiley-Liss, Inc. [source] Diversity and composition of trees and shrubs in Kasagala forest: a semiarid savannah woodland in central UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Samson Gwali Abstract The diversity and composition of trees and shrubs of ,5 cm diameter at breast height (DBH) were investigated in Kasagala woodland in central Uganda using 1 ha permanent sample plots. A total of 2745 trees and shrubs with a mean stem density of 686 ha,1 were recorded. These included 69 tree species belonging to 28 families and 47 genera. There was a larger number of small stems compared with that of larger stems. There was significant variation in stem size class distribution between the plots (F = 3.14, P = 0.027). The variation in stem densities (counts) across different size classes was significant (F = 8.31, P < 0.001). Species diversity was higher in the low lands compared with that in the elevated sites in the woodland. The species encountered were unevenly distributed across the plots. Species abundance was not significantly different across the sample plots (F = 2.63, P = 0.053). We suggest that the structure of the forest is typical of any regenerating forest, but other human influences may have played a part in the dominance of size classes <10 cm DBH. The causes of the present status and composition of the woodland require further investigation. Résumé La diversité et la composition des arbres et arbustes de plus de 5 cm dbh ont étéétudiées dans la forêt de Kasagala, au centre de l'Ouganda, en utilisant des parcelles échantillons permanentes d'un hectare. On a relevé la présence de 2745 arbres et arbustes, avec une densité moyenne de 686 troncs ha,1. Ceux-ci comprenaient 69 espèces d'arbres appartenant à 28 familles et à 47 genres. Il y avait un plus grand nombre de petits troncs que de gros. Il y avait une variation significative de la distribution des classes de taille entre les parcelles (F = 3.14, P = 0.027). La variation de la densité des troncs (comptages) entre les différentes classes de taille était significative (F = 8.31, P < 0.001). La diversité des espèces était plus grande dans les terres basses que dans les sites plus élevés dans la forêt. Les espèces rencontrées étaient distribuées de façon inégale entre les parcelles. L'abondance des espèces n'était pas significativement différente selon les parcelles échantillons (F = 2.63, P = 0.053). Nous suggérons que la structure de la forêt est typique de toute forêt en voie de régénération, mais que d'autres influences humaines peuvent avoir joué un rôle dans la dominance des classes de taille <10 cm dbh. Les raisons du statut et de la composition actuels de la forêt requièrent de nouvelles investigations. [source] Natural regeneration and population dynamics of the tree Afzelia quanzensis in woodlands in Southern AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009Karin Gerhardt Abstract The logging of tree species of high commercial value is increasing throughout the African continent, yet the ecology of these species is generally poorly known. We studied the regeneration pattern and size class distribution of Afzelia quanzensis populations in northern South Africa over a 5-year period. Recruitment was low as the annual seedling mortality was >65%. Seedlings were located under the canopy and were affected by drought and browsing. The adults were scattered or were in a clump-dispersed pattern, which would result in higher recruitment of offspring near parents. Individuals of 0,10 cm diameter at breast height (DBH) were few, while there were 32 trees ha,1 at >10 cm DBH with an annual mortality of 0.8%. Annual diameter increments varied between 0.06 and 0.28 cm. It appears that the transition from the sapling into the juvenile stage could be a bottleneck in the regeneration of the species. A longer study, including more rainfall cycles, may reveal other patterns as dry and wet years have different impacts on dynamics. Résumé La coupe d'espèces d'arbres de grande valeur commerciale augmente dans tout le continent africain, pourtant l'écologie de ces espèces est généralement mal connue. Nous avons étudié le schéma de régénération et la distribution des classes d'âge des populations d'Afzelia quanzensis dans le nord de l'Afrique du Sud pendant cinq ans. Le recrutement était faible car la mortalité annuelle des jeunes plants était de plus de 65%. Les jeunes plans se trouvaient sous la canopée et étaient affectés par la sécheresse et par le broutage des animaux. Les adultes étaient dispersés ou se trouvaient en un schéma en bosquet, qui résulte en un plus fort recrutement de la progéniture près des parents. Les individus de 0,10 cm DBH étaient rares, alors qu'il y avait32 arbres ha,1à >10 cm DBH, avec une mortalité annuelle de 0,8%. L'incrément annuel du diamètre variait entre 0,06 et 0,28 cm. Il semble que la transition entre le stade de jeune arbre et celui de juvénile pourrait bien constituer un étranglement dans la régénération de l'espèce. Une étude plus longue, comprenant plus de cycles de pluies, pourrait révéler un autre schéma étant donné que les années sèches et humides ont des impacts différents sur cette dynamique. [source] Tree mortality due to an El Niño flood along the lower Tana River, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2009Julie Wieczkowski Abstract This study investigated forest tree mortality as a result of the extremely strong 1997,1998 El Niño flood in Tana River, Kenya, directly tested how mortality varied in relation to tree species and diameter at breast height (DBH), and indirectly tested how mortality varied in relation to floodwater depth. The study forest was under 2 m of water for approximately 71 days, from December 1997 until February 1998. Twenty-five liana, subcanopy tree, and canopy tree species were selected based on their importance in the diet of the Tana River mangabey (Cercocebus galeritus Peters), a critically endangered primate endemic to the Tana River. Reproductive-sized individuals of these species were enumerated in 16.25 ha. I also enumerated trees killed by the El Niño flood, recorded their location in the forest, and measured their DBH. Ninety-two trees in fifteen species were killed by the flood. There were significant differences in mortality by species and by 0.25 ha quadrat. There were negative correlations between number of dead and DBH, number of dead and distance from the river, and per cent of quadrat killed and distance from the river. There appear to have been few long-term consequences of the El Niño flood in the forest or for the mangabeys. Résumé Cette étude s'est intéressée à la mortalité des arbres en forêt due à la très grave inondation causée en 1997,1998 par El Niño dans la rivière Tana, au Kenya. J'ai testé directement de quelle manière la mortalité variait selon l'espèce des arbres et leur diamètre à hauteur de poitrine (DBH), et indirectement comment elle variait avec la profondeur de l'eau. La forêt étudiée est restée sous deux mètres d'eau pendant environ 71 jours, de décembre 1997 à février 1998. Vingt-cinq espèces de lianes, d'arbres de sous-canopée et de la canopée ont été sélectionnées en fonction de leur importance dans le régime alimentaire du mangabey de la rivière Tana (Cercocebus galeritus Peters), une espèce de primate en danger critique d'extinction qui est endémique de cet endroit. Les individus de ces espèces ayant la taille requise pour se reproduire furent dénombrés sur 16,25 ha. J'ai aussi dénombré les arbres tués par l'inondation d'El Niño, noté leur emplacement dans la forêt et mesuré leur DBH. Quatre-vingt-douze arbres appartenant à 15 espèces ont été tués par cette inondation. Il y avait des différences significatives de mortalité selon les espèces et par quadrat de 0,25 ha. Il y avait des corrélations négatives entre le nombre d'arbres morts et leur DBH, entre le nombre d'arbres morts et la distance par rapport au lit du fleuve, et entre le nombre d'arbres morts par quadrat et cette distance. Il semble qu'il y ait peu de conséquences à long terme de cette inondation dans la forêt ou pour les mangabeys. [source] Potentiation of PGE2 -mediated cAMP production during neuronal differentiation of human neuroblastoma SK-N-BE(2)C cellsJOURNAL OF NEUROCHEMISTRY, Issue 2 2001Se-Young Choi The prostaglandin-evoked cAMP production was studied in human neuroblastoma SK-N-BE(2)C cells during neuronal differentiation induced by all- trans retinoic acid. The incubation with 5 µm all- trans retinoic acid for 4,6 days promoted neurite outgrowth of cells. After differentiation, prostaglandin E2 (PGE2)-induced cAMP production was dramatically increased, whereas forskolin- and AlF -induced cAMP productions were not changed. The increase reached maximum after 4-days of incubation with all- trans retinoic acid. The differentiation caused an increase in the maximal response and a decrease in the half-maximal effective concentration of the PGE2 -induced cAMP production. In addition, the binding of [3H]PGE2 to membrane receptors was enhanced in differentiated cells. However, the order of potency of the various prostaglandins (PGE1 = PGE2 > PGD2 = PGF2, = PGI2) in cAMP production did not change during the differentiation, suggesting that mainly E-prostanoid (EP) receptors were involved. Butaprost, an EP2 receptor specific agonist, increased the cAMP level in a concentration dependent manner and had a similar potentiating effect on cAMP production as PGE2 upon differentiation. Northern blot analysis using the human cDNA probes shows that the EP2 mRNA level was about seven times higher in differentiated cells, while the dopamine ,-hydroxylase (DBH) mRNA completely disappeared. Our results, thus, suggest that elevated gene expression of the prostanoid EP2 receptor results in an increase in the PGE2 -evoked cAMP production in SK-N-BE(2)C cells during neuronal differentiation. [source] Serotonergic and Catecholaminergic Interactions with Co-Localised Dopamine-Melatonin Neurones in the Hypothalamus of the Female TurkeyJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2009S. W. Kang Serotonin and catecholamines (dopamine, norepinephrine, epinephrine) have important roles as neurotransmitters in avian reproduction, but their anatomical relationship to the neuroendocrine circuitry that regulates reproduction is poorly understood. Our previous studies have shown that co-localised dopamine-melatonin (DA-MEL) neurones in the avian premammillary nucleus (PMM) are active during periods of photoresponsiveness and, therefore, are potentially photosensitive neurones. Because serotonergic and catecholaminergic neurotransmitters are important regulators of reproductive function in the female turkey, we hypothesised that the serotonergic/catecholaminergic neurones within the brainstem might interact with PMM DA-MEL neurones and constitute an important circuit for reproductive function. To examine this possible interaction, the retrograde fluorescent tract tracer, 1,1,dioctadecyl-3,3,3,3,-tetramethyleindocarbocyanine perchlorate (DiI) was injected into the PMM, and combined with serotonin, tyrosine hydroxylase (TH), dopamine ,-hydroxylase (DBH) and phenyl N -methyltransferse (PNMT) immunocytochemistry to reveal neuroanatomical connections. Changes in the activities of serotonergic, dopaminergic, adrenergic and noradrenergic neuronal systems projecting to the PMM were measured at different reproductive states with in situ hybridisation (ISH) techniques, using tryptophan hydroxylase 2 (TPH2) and TH mRNA expression, respectively. Cells labelled with DiI were found in anatomically discrete areas in or near the hypothalamus and the brainstem. Double immunocytochemistry confirmed that there were serotonin, DBH and PNMT fibres in close apposition to DA-MEL neurones. TPH2 mRNA expression in serotonin neurones was found in several nuclei, and its most abundant mRNA expression was seen in the nucleus Locus ceruleus of laying and incubating hens. TH mRNA expression levels in the six catecholaminegic areas labelled with DiI was measured across the different reproductive states. In the nucleus tractus solitarius (adrenergic), the highest level of TH mRNA expression was found in photorefractory hens and the lowest level in incubating hens. These observed patterns of serotonin/catecholamine neuronal distribution and their variable interactions with PMM DA-MEL neurones during different reproductive states may offer a significant neuroanatomical basis for understanding the control of avian reproductive seasonality. [source] Noradrenergic Regulation of Hypothalamic Cells that Produce Growth Hormone-Releasing Hormone and Somatostatin and the Effect of Altered Adiposity in SheepJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2005J. Iqbal Abstract The growth hormone (GH) axis is sensitive to alteration in body weight and there is evidence that central noradrenergic systems regulate neurones that produce growth hormone-releasing hormone (GHRH) and somatostatin (SRIF). This study reports semiquantitative estimates of the noradrenergic input to neuroendocrine GHRH and SRIF neurones in the sheep of different body weights. We also studied the effects of altered body weight on expression of dopamine ,-hydroxylase (DBH), the enzyme that produces noradrenalin from dopamine. Ovariectomised ewes were made Lean (39.6 ± 2.6 kg; Mean ± SEM) by dietary restriction, whereas Normally Fed animals (61.2 ± 0.8 kg) were maintained on a regular diet. Brains were perfused for immunohistochemistry and in situ hybridisation. The Mean ± SEM number of GHRH-immunoreactive (-IR) cells was lower in Normally Fed (65 ± 7) than in Lean (115 ± 14) animals, whereas the number of SRIF-IR cells was similar in the two groups (Normally Fed, 196 ± 17; Lean 230 ± 21). Confocal microscopic analysis revealed that the percentage of GHRH-IR cells (Normally Fed 36 ± 1.5% versus Lean 32 ± 4.6%) and percentage of SRIF-IR cells (Normally Fed 30 ± 40.4% versus Lean 32 ± 2.3%) contacted by noradrenergic fibres did not change with body weight. FluoroGold retrograde tracer injections confirmed that noradrenergic projections to the arcuate nucleus are from ventrolateral medulla and noradrenergic projections to periventricular nucleus arise from the ventrolateral medulla, nucleus of solitary tract, locus coeruleus (LC) and the parabrachial nucleus (PBN). DBH expressing cells were identified using immunohistochemistry and in situ hybridisation and the level of expression (silver grains/cell) quantified by image analysis. The number of DBH cells was similar in Normally Fed and Lean animals, but the level of expression/cell was lower (P < 0.02) in the PBN and LC of Lean animals. These results provide an anatomical basis for the noradrenergic regulation of GHRH and SRIF cells and GH secretion. Altered activity or noradrenergic neurones in the PBN and LC that occur with reduced body weight may be relevant to the control of GH axis. [source] Generation of dopamine neurons from embryonic stem cells in the presence of the neuralizing activity of bone marrow stromal cells derived from adult miceJOURNAL OF NEUROSCIENCE RESEARCH, Issue 13 2008Aki Shintani Abstract Stromal cell lines such as PA6 and MS5 have been employed for generating dopamine (DA) neurons from embryonic stem (ES) cells. The present study was designed to test whether bone marrow stromal cells (BMSC) derived from adult mice might be available as a feeder layer to produce DA cells efficiently from ES cells. When ES cells were grown on BMSC in the presence of fibroblast growth factor 8 (FGF8) and sonic hedgehog (SHH), about 40% of TuJ1-positive neurons expressed tyrosine hydroxylase (TH). Because these cells labeled with TH were negative for dopamine-,-hydroxylasae (DBH), the marker for noradrenergic and adrenergic neurons, the TH-positive cells were most likely DA neurons. They indeed expressed midbrain DA neuron markers such as Nurr 1, Ptx-3, and c-ret and were capable of synthesizing and releasing DA in vitro. Furthermore, DA neurons differentiated from ES cells in this differentiation protocol survived transplantation in rats with 6-hydroxydopamine lesions and reversed the lesion-induced circling behavior. The data indicate that BMSC can facilitate an efficient induction of DA neurons from ES cells and that the generated DA neurons are biologically functional both in vitro and in vivo. Insofar as BMSC have recently been employed in autologous cell therapy for ischemic heart and arteriosclerotic limb diseases, the present study raises the possibility that autologous BMSC can be applied in future cell transplantation therapy in Parkinson's disease. © 2008 Wiley-Liss, Inc. [source] Tree spacing and area of competitive influence do not scale with tree size in an African rain forestJOURNAL OF VEGETATION SCIENCE, Issue 5 2008Michael J. Lawes Abstract Questions: Is the area of influence of individual trees determined by tree size? Does competition, inferred from spatial pattern between neighbouring trees, affect adult tree spacing patterns in an tropical forest? At what size-class or stage is competition between neighbours most likely to affect adult tree spacing patterns? Location: Kibale National Park, western Uganda. Methods: Relationships between focal tree size and nearest neighbour distance, size, density, and species in a 4-ha permanent plot, using point pattern analyses. Results: We found non-random patterns of distribution of nearest tree neighbours (stems > 10 cm DBH). Independent of identity, tree density was highest and neighbours were regularly spaced within 3,5m of an individual. Tree densities were lower and relatively constant at distances >5m and neighbours were typically randomly spaced. In general, conspecific patterns conformed to the latter trends. Thus, individual area of influence was small (within a radius of 3,5 m). Rarer species were more clumped than common species. Weak competitive thinning occurred among more densely packed small trees (<20 cm DBH), and rapidly disappeared with increasing tree size and distance from an individual. The clumping and density of individuals was not significantly affected by tree size. Conclusions: Negative effects of competition among trees are weak, occur within the crown radius of most individuals, and are independent of adult tree size and identity. The density of neighbouring trees (aggregation) did not decline with increasing focal tree size at either the conspecific or the community level and tree diameter (tree size) was not a good estimator of the implied competitive influence of a tree. Mechanisms operating at the recruitment stage may be important determinants of adult tree community diversity and spacing patterns. [source] Relationships between soil hydrology and forest structure and composition in the southern Brazilian AmazonJOURNAL OF VEGETATION SCIENCE, Issue 2 2007Stefan Jirka Abstract Question: Is soil hydrology an important niche-based driver of biodiversity in tropical forests? More specifically, we asked whether seasonal dynamics in soil water regime contributed to vegetation partitioning into distinct forest types. Location: Tropical rain forest in northwestern Mato Grosso, Brazil. Methods: We investigated the distribution of trees and lianas , 1 cm DBH in ten transects that crossed distinct hydrological transitions. Soil water content and depth to water table were measured regularly over a 13-month period. Results: A detrended correspondence analysis (DCA) of 20 dominant species and structural attributes in 10 × 10 m subplots segregated three major forest types: (1) high-statured upland forest with intermediate stem density, (2) medium-statured forest dominated by palms, and (3) low-statured campinarana forest with high stem density. During the rainy season and transition into the dry season, distinct characteristics of the soil water regime (i.e. hydro-indicators) were closely associated with each vegetation community. Stand structural attributes and hydro-indicators were statistically different among forest types. Conclusions: Some upland species appeared intolerant of anaerobic conditions as they were not present in palm and campinarana sites, which experienced prolonged periods of saturation at the soil surface. A shallow impermeable layer restricted rooting depth in the campinarana community, which could heighten drought stress during the dry season. The only vegetation able to persist in campinarana sites were short-statured trees that appear to be well-adapted to the dual extremes of inundation and drought. [source] Johansson revisited: the spatial structure of epiphyte assemblagesJOURNAL OF VEGETATION SCIENCE, Issue 1 2007Gerhard Zotz Abstract Question: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community? Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama. Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species. Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest. Conclusions: Applying pre-established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees. [source] Variation in tree growth, mortality and recruitment among topographic positions in a warm temperate forestJOURNAL OF VEGETATION SCIENCE, Issue 3 2006Riyou Tsujino Abstract: Questions: Do the population dynamics of trees differ among topographic positions and, if so, how does topographic position affect the population dynamics of species that are distributed in a topography-specific manner? Which is the most important life stage in determining vegetation patterns? Location: Primary and secondary warm temperate evergreen broad-leaved forest (40 - 280 m a.s.l.) on the western part of Yakushima Island, Japan. Methods: Mortality, recruitment, DBH growth and distribution of stems (= 5 cm DBH) in a 2.62-ha plot were surveyed in 1992 and 2002 to determine the relationships between population parameters and (1) topography and (2) distribution patterns of 17 common tree species. Results: Common species (n = 17) were classified into three distribution pattern groups: group A, distributed mainly on convex slopes; group B, on concave slopes, and group C, not aggregated with respect to topographic position. Stem mortality, recruitment and DBH growth were greater in group A than in group B within each topographic class. The hierarchy of stem mortality among topographic classes for groups A and B was convex > planar > concave. Stem recruitment density was relatively high on the convex and concave slopes, respectively, for groups A and B. Conclusions The topographical positions of adult trees were not always most suited for adult survival and growth. For group A, the distribution pattern of adults was determined in the juvenile stage, while this was not the case for group B. Studies of juvenile stages are important for understanding the demographic basis of vegetation distribution patterns. [source] A long-term study of neighbour-regulated demography during a decline in forest species diversityJOURNAL OF VEGETATION SCIENCE, Issue 1 2006Lin Yi-ching Abstract Question: Did disturbance, no density-dependence of the dominant species, and negative neighbourhood interactions on rare species affect tree demography during a decline in species diversity associated with the increase of Acer saccharum from 1939,2001? Hypotheses: 1. The rise in dominance of A. saccharum was because of its advantage in disturbances and lack of density-dependence of its demography. 2. Rare species were not favoured by disturbances, including those from Dutch elm disease, and demonstrated negative neighbourhood interactions with A. saccharum. Location: Brownfield Woods in Illinois, USA. Methods: Historical maps of trees (, 7.6 cm DBH) from 1939, 1951, 1988, and 2001 in 16 quadrats (48 m × 68 m) were used to compare demography of eight tree species. Effects of disturbances, density-dependence, and neighbourhood interactions on mortality and recruitment of tree species within a 6-m radius of individual target trees were studied. Results: A. saccharum demonstrated a demographic advantage over rare species. It had lower mortality and higher recruitment rates. Disturbances facilitated recruitment of A. saccharum, but did not enhance rare species. Density-dependence of both mortality and recruitment of A. saccharum occurred, but population projection models indicated that ecological conditions became more favourable for A. saccharum in the past 62 years. Furthermore, negative neighbourhood interactions were detected between rare species and A. saccharum. The increase in neighbouring A. saccharum significantly increased mortality and reduced recruitment of the rare species. Conclusions: The general disturbance regime, enhanced by Dutch elm disease, in Brownfield Woods facilitated the rise of dominance of A. saccharum. Meanwhile, rare species declined as a result of their disadvantage in disturbance and negative neighbourhood interactions with A. saccharum. [source] Effects of selective logging on tree diversity, composition and plant functional type patterns in a Bornean rain forestJOURNAL OF VEGETATION SCIENCE, Issue 1 2003René Verburg Sidiyasa et al. (1999); Anon. (1955,1994) Abstract. The effects of selective logging on tree diversity, changes in tree species composition and plant functional types were studied with the use of seven permanent plots in virgin and in logged forest. All plots were located in a lowland dipterocarp rain forest in East Kalimantan on the island of Borneo. Just after logging and during the following 20 yr tree diversity measured as Fishers', was not significantly affected in logged forest plots. Temporal shifts in tree species composition were analysed with Principal Component Analysis (PCA). Logged forest plots had much larger changes over time than virgin forest plots. In the smallest diameter class, some logged forest plots showed a distinct trajectory in PCA space compared to virgin forest plots, while in larger diameter classes movement of logged plots in PCA space was random. This suggests that there is no predetermined community to which logged forest plots tend to shift when recovering from logging. We found a significant negative correlation between diameter increments and the species-specific wood densities of tree species. Species-specific wood density and potential tree height were used to assign species to five PFTs. As expected, logging increased the fraction of softwood stems in small diameter classes. In the largest diameter classes (, 50 cm DBH) a strong decrease of softwood emergent stems was found in logged forest plots. After more than 20 yr no recruitment was found of softwood emergent stems in selectively logged forest. [source] Tree mortality and effects of release from competition in an old-growth Fagus-Abies-Picea standJOURNAL OF VEGETATION SCIENCE, Issue 5 2001Jerzy Szwagrzyk Abstract. In a montane mixed Fagus-Abies-Picea forest in Babia Gora National Park (southern Poland), the dynamics of an old-growth stand were studied by combining an 8-yr annual census of trees in a 1-ha permanent sample plot with radial increments of Abies and Picea growing in the central part of the plot. The mortality among the canopy trees was relatively high (10% in 8 yr), but the basal area increment of surviving trees slightly exceeded the losses caused by tree death. DBH increment was positively correlated with initial diameter in Abies and Picea, but not in Fagus. For individual trees smaller than the median height, basal area increment was positively related to the basal area of old snags and the basal area of recently deceased trees in their neighbourhood, but negatively related to the basal area of live trees. Dendrochronological analysis of the past growth patterns revealed numerous periods of release and suppression, which were usually not synchronized among the trees within a 0.3 ha plot. The almost normal distribution of canopy tree DBH and the small number of young individuals in the plot indicated that stand dynamics were synchronized over a relatively large area and, hence, were consistent with the developmental phase concept. On the other hand, the lack of synchronization among periods of growth acceleration in individual mature Abies and Picea trees conforms more closely to the gap-dynamics paradigm. [source] Long-term post-fire changes in the northeastern boreal forest of QuebecJOURNAL OF VEGETATION SCIENCE, Issue 6 2000Louis De Grandpré Abstract. Natural dynamics in the boreal forest is influenced by disturbances. Fire recurrence affects community development and landscape diversity. Forest development was studied in the northeastern boreal forest of Quebec. The objective was to describe succession following fire and to assess the factors related to the changes in forest composition and structure. The study area is located in northeastern Quebec, 50 km north of Baie-Comeau. We used the forest inventory data gathered by the Ministère des Ressources naturelles du Québec (MRNQ). In circular plots of 400 m2, the diameter at breast height (DBH) of all stems of tree species greater than 10 cm was recorded and in 40 m2 subplots, stems smaller than 10 cm were measured. A total of 380 plots were sampled in an area of 6000 km2. The fire history reconstruction was done based on historical maps, old aerial photographs and field sampling. A time-since-fire class, a deposit type, slope, slope aspect and altitude were attributed to each plot. Each plot was also described according to species richness and size structure characteristics. Traces of recent disturbance were also recorded in each plot. Changes in forest composition were described using ordination analyses (NMDS and CCA) and correlated with the explanatory variables. Two successional pathways were observed in the area and characterized by the early dominance of intolerant hardwood species or Picea mariana. With time elapsed since the last fire, composition converged towards either Picea mariana, Abies balsamea or a mixture of both species and the size structure of the coniferous dominated stands got more irregular. The environmental conditions varied between stands and explained part of the variability in composition. Their effect tended to decrease with increasing time elapsed since fire, as canopy composition was getting more similar. Gaps may be important to control forest dynamics in old successional communities. [source] Selection of sleeping trees in pileated gibbons (Hylobates pileatus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2010Rungnapa Phoonjampa Abstract Selection and use patterns of sleeping sites in nonhuman primates are suggested to have multiple functions, such as predation avoidance, but they might be further affected by range defense as well as foraging constraints or other factors. Here, we investigate sleeping tree selection by the male and female members of one group of pileated gibbons (Hylobates pileatus) at Khao Ang Rue Nai Wildlife Sanctuary, Thailand. Data were collected on 113 nights, between September 2006 and January 2009, yielding data on 201 sleeping tree choices (107 by the female and 94 by the male) and on the characteristics of 71 individual sleeping trees. Each sleeping tree and all trees ,40,cm diameter at breast height (DBH) in the home range were assessed (height, DBH, canopy structure, liana load) and mapped using a GPS. The gibbons preferentially selected tall (mean=38.5,m), emergent trees without lianas. The majority of the sleeping trees (53.5%) were used only once and consecutive reuse was rare (9.5%). Sleeping trees were closer to the last feeding tree of the evening than to the first feeding tree in the morning, and sleeping trees were located in the overlap areas with neighbors less often than expected based on time spent in these areas. These results suggest avoidance of predators as the main factor influencing sleeping tree selection in pileated gibbons. However, other non-mutually exclusive factors may be involved as well. Am. J. Primatol. 72:617,625, 2010. © 2010 Wiley-Liss, Inc. [source] Differential expression of catecholamine biosynthetic enzymes in the rat ventrolateral medullaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2001Jacqueline K. Phillips Abstract Adrenergic (C1) neurons located in the rostral ventrolateral medulla are considered a key component in the control of arterial blood pressure. Classically, C1 cells have been identified by their immunoreactivity for the catecholamine biosynthetic enzymes tyrosine hydroxylase (TH) and/or phenylethanolamine N-methyltransferase (PNMT). However, no studies have simultaneously demonstrated the expression of aromatic L-amino acid decarboxylase (AADC) and dopamine ,-hydroxylase (DBH) in these neurons. We examined the expression and colocalization of all four enzymes in the rat ventrolateral medulla using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Retrograde tracer injected into thoracic spinal segments T2,T4 was used to identify bulbospinal neurons. Using fluorescence and confocal microscopy, most cells of the C1 group were shown to be double or triple labeled with TH, DBH, and PNMT, whereas only 65,78% were immunoreactive for AADC. Cells that lacked detectable immunoreactivity for AADC were located in the rostral C1 region, and approximately 50% were spinally projecting. Some cells in this area lacked DBH immunoreactivity (6.5,8.3%) but were positive for TH and/or PNMT. Small numbers of cells were immunoreactive for only one of the four enzymes. Numerous fibres that were immunoreactive for DBH but not for TH or PNMT were noted in the rostral C1 region. Single-cell RT-PCR analysis conducted on spinally projecting C1 neurons indicated that only 76.5% of cells that contained mRNA for TH, DBH, and PNMT contained detectable message for AADC. These experiments suggest that a proportion of C1 cells may not express all of the enzymes necessary for adrenaline synthesis. J. Comp. Neurol. 432:20,34, 2001. © 2001 Wiley-Liss, Inc. [source] Foraging ecology of howler monkeys in a cacao (Theobroma cacao) plantation in Comalcalco, MexicoAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2006David Muñoz Abstract Recent evidence indicates that primate populations may persist in neotropical fragmented landscapes by using arboreal agroecosystems, which may provide temporary habitats, increased areas of vegetation, and connectivity, among other benefits. However, limited data are available on how primates are able to sustain themselves in such manmade habitats. We report the results of a 9-month-long investigation of the feeding ecology of a troop of howler monkeys (n=24) that have lived for the past 25 years in a 12-ha cacao plantation in the lowlands of Tabasco, Mexico. A vegetation census indicated the presence of 630 trees (,20 cm diameter at breast height (DBH)) of 32 shade species in the plantation. The howlers used 16 plant species (13 of which were trees) as sources of leaves, fruits, and flowers. Five shade tree species (Ficus cotinifolia, Pithecellobium saman, Gliricidia sepium, F. obtusifolia, and Ficus sp.) accounted for slightly over 80% of the total feeding time and 78% of the total number trees (n=139) used by the howlers, and were consistently used by the howlers from month to month. The howlers spent an average of 51% of their monthly feeding time exploiting young leaves, 29% exploiting mature fruit, and 20% exploiting flowers and other plant items. Monthly consumption of young leaves varied from 23% to 67%, and monthly consumption of ripe fruit varied from 12% to 64%. Differences in the protein-to-fiber ratio of young vs. mature leaves influenced diet selection by the monkeys. The howlers used 8.3 ha of the plantation area, and on average traveled 388 m per day in each month. The howlers preferred tree species whose contribution to the total tree biomass and density was above average for the shade-tree population in the plantation. Given the right conditions of management and protection, shaded arboreal plantations in fragmented landscapes can sustain segments of howler monkey populations for many decades. Am. J. Primatol. 68:127,142, 2006. © 2006 Wiley-Liss, Inc. [source] Ecological correlates of abundance in the Tana mangabey (Cercocebus galeritus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2004Julie Wieczkowski Abstract I investigated the ecological correlates of abundance in the Tana mangabey (Cercocebus galeritus), one of the world's most endangered primates, with the goal of recommending management strategies. I systematically selected 31 forest fragments throughout the mangabey's 60-km distribution along the lower Tana River in southeastern Kenya. Within the 31 fragments, I measured vegetation structure, food abundance, and human forest product use in 107 belt transects, and conducted 370 mangabey surveys. I used a weighted multiple regression analysis to determine whether there was a dependence between the selected forest attributes and the mean number of mangabey groups per fragment. Fragment area and density of trees ,10 cm diameter at breast height (DBH) were the only variables that significantly correlated with the variation in mangabey abundance. No additional variables were significant when the analysis was limited to forest fragments inside the Tana River Primate National Reserve (TRPNR) or to fragments outside the TRPNR. When I estimated the resources available before recent human forest product use by adding nonharvested and harvested variables, the total basal area of the top 15 food species became significant. This was only within the TRPNR, however. Management, therefore, should focus on increasing forest area, density of trees ,10 cm DBH, and coverage of food trees throughout the mangabey's distribution. Solutions must be found for the problem of forest clearing, and forest product use must be better managed to protect the habitat of this critically endangered primate. The significance of food abundance only within the TRPNR suggests a need to collect dietary data from mangabey groups in fragments toward the southern limit of the mangabey's distribution, where plant species composition differs from that in fragments in which dietary data have been previously collected. Am. J. Primatol. 63:125,138, 2004. © 2004 Wiley-Liss, Inc. [source] Cholinergic switch associated with morphological differentiation in neuroblastoma,THE JOURNAL OF PATHOLOGY, Issue 4 2009Franck Bourdeaut Abstract The morphology of malignant cells distinguishes between undifferentiated, poorly differentiated and differentiating neuroblastomas and constitutes a strong prognostic factor. Spontaneous or treatment-induced maturation characterizes a subset of neuroblastomas. It constitutes the basis of retinoic acid treatment to improve survival in aggressive neuroblastomas. However, the molecular events that drive differentiation are poorly understood. In the present study we have investigated the relationships between gene expression profiles and differentiation criteria in stroma-poor neuroblastomas. This study included three undifferentiated (UN), 20 poorly differentiated (PDN) and 11 differentiating (DN) neuroblastomas. These groups could be clearly separated using unsupervised clustering methods, which further enabled a major classification impact of genes involved in neural development, differentiation and function to be identified. UNs are characterized by high ASCL1, high PHOX2B, low GATA2, low TH and low DBH expressions. Most PDNs harbour a clear adrenergic phenotype, even in the presence of missense PHOX2B mutations. Finally, all DN tumours demonstrate cholinergic features. Depending upon their association with adrenergic characteristics, this enables dual ,cholinergic/adrenergic' and ,fully cholinergic' neuroblastomas to be defined. This suggests that the cholinergic switch, a final specification process that occurs physiologically in a minority of sympathetic neurons, is a critical step of differentiation in some neuroblastic tumours. This switch is associated with a down regulation of DBH that is apparently not strictly dependent upon PHOX2B. Conversely, GATA2 and TFAP2B may play critical roles in maintaining adrenergic features in poorly differentiated tumours. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Impact of landscape spatial pattern on liana communities in tropical rainforests at Los Tuxtlas, MexicoAPPLIED VEGETATION SCIENCE, Issue 3 2009Víctor Arroyo-Rodríguez Abstract Questions: What are the species composition and species and stem densities of liana communities in tropical landscapes of different deforestation levels? Which spatial attributes (forest cover, patch area, shape and isolation) have the strongest influence on liana communities in these landscapes? Location: Forty-five rainforest patches in Los Tuxtlas Biosphere Reserve, Mexico. Methods: In three landscapes with different deforestation levels (HDL=4%; IDL=11%; and LDL=24% of remaining forest cover) liana communities (DBH ,2.5 cm) were characterized in 15 randomly selected patches per landscape (10 50 m × 2 m transects per patch=0.1 ha), and evaluated the effects of patch area, shape and isolation on liana species and stem density (number of species and stems per 0.1 ha). Results: A total of 64 taxa and 24 families were sampled. Species composition differed highly among landscapes, with HDL being the most dissimilar landscape. The response of lianas to landscape spatial pattern differed significantly among landscapes. Proximity to villages had a strong positive effect on species and stem densities in LDL and IDL. There was a sharp decrease in liana stem density in HDL, with four patches (27%) found to be unoccupied by lianas. Conclusions: Fragmentation may have a positive effect on lianas, partly because of edge effects. This positive effect seems to be limited by the proportion of remaining forest cover in the landscape, as the liana communities had collapsed in the most deforested landscape. [source] Evaluation of mangrove structure and condition in two trans-boundary areas in the Western Indian OceanAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009S. O. Bandeira Abstract 1.The structure, forest condition and regeneration status of nine mangrove forests in two trans-boundary areas of Mozambique bordering Tanzania and South Africa were studied. The main objective was to estimate the cutting intensity in the selected sites , Saco and Sangala in southern Mozambique; Mecúfi, Pemba, Ibo, Luchete, Ulo in northern Mozambique, and Mngoji 1 and Mngoji 2 in Tanzania. 2.A total of 135, 10,m×10,m quadrats were set in the outer, middle and lower parts of the mangrove forests at all sampling sites. Measurements included stem diameter at breast height (DBH) and height of adult trees (i.e. all trees with stem diameter more than 2.5,cm). Young trees (with stem diameter of less than 2.5,cm) were classified as juveniles. To assess forest condition, trees within the quadrat were classified into intact, partially cut, coppiced, die back and stump. Pole quality was appraised through the classification of the lead stem into three categories,straight, semi-straight and crooked poles. 3.The results indicate different levels of exploitation with Mngoji 1 and Mngoji 2, the most degraded sites, having stump densities of 959,stumps,ha,1 and 592,stumps,ha,1, respectively. Most sites had mostly poles of inferior quality (crooked poles), but high densities of straight and semi-straight poles were found in Mngoji 1 (742,stems,ha,1) and Saco (636,stems,ha,1). 4.Natural regeneration was observed in most sites but not for all species, with adequate regeneration in Saco (14,766 saplings ha,1) and Mecúfi (14,706 saplings ha,1), while low regeneration was recorded in Mngoji 1 and 2 (2212 saplings ha,1 and 4799saplingsha,1, respectively). 5.These results indicate the need for improved mangrove management and replanting especially in mangrove depleted conservation areas of southern Tanzania. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effects of repeated maprotiline and fluoxetine treatment on gene expression of catecholamine synthesizing enzymes in adrenal medulla of unstressed and stressed ratsAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 4 2010N. Spasojevic Summary 1,Repeated maprotiline (a noradrenaline reuptake inhibitor) and fluoxetine (a serotonin reuptake inhibitor) treatment on gene expression of catecholamine biosynthetic enzymes were examined in adrenal medulla of unstressed control and chronic unpredictable mild stressed rats. 2,Maprotiline did not change gene expression of catecholamine biosynthetic enzymes in control and stressed rats. 3,Fluoxetine increased gene expression of tyrosine hydroxylase (TH) and dopamine-,-hydroxylase (DBH), but did not phenylethanolamine N -methyltransferase in both unstressed and chronic unpredictable mild stressed animals. 4,In conclusion, we have demonstrated that repeated administration of fluoxetine enhanced gene transcription of TH and DBH and subsequently stimulates noradrenaline synthesis in adrenal medulla of control and stressed rats. [source] Responses to Fire in Selected Tropical Dry Forest Trees,BIOTROPICA, Issue 5 2006Sarah M. Otterstrom ABSTRACT Fire is a frequent disturbance in the tropical dry forests of Central America, yet very little is known about how native species respond to such events. We conducted an experimental burn in a tropical dry forest of western Nicaragua to evaluate plant responses to fire with respect to survivorship and recruitment. Measurements of woody vegetation of all size classes were carried out prior to the prescribed burn and three successive years post fire. We selected the 15 most abundant species <10 cm DBH to assess percent survivorship and sprouting responses post fire. Changes in seedling densities for these 15 most abundant species and the 15 least abundant species were analyzed using a repeated measure ANOVA. We also assessed changes in seedling densities for three species of international conservation concern. We found three major fire-coping strategies among common dry forests plants: resisters (low fire-induced mortality), resprouters (vigorous sprouting), and recruiters (increased seeding post-fire). While survivorship was generally high relative to tropical moist forest species, those species with lower survivorship used either seeding or sprouting as an alternative strategy for persisting in the forest community. Seed dispersal mechanisms, particularly wind dispersal, appear to be an important factor in recruitment success post-fire. Burn treatment led to a significant increase in the density of seedlings for two species of conservation concern: Guaiacum sanctum and Swietenia humilis. Results of this study suggest that common dry forest species in western Nicaragua are fire tolerant. Further study of individual species and their fire responses is merited. RESUMEN El incendio forestal causa perturbación frecuente en los bosques secos tropicales de Centroamérica, sin embargo se conoce poco del comportamiento de las especies nativas a ésta perturbación. Nosotros llevamos a acabo una quema experimental en un bosque seco tropical de Nicaragua occidental para evaluar el comportamiento de la flora con respecto a la sobrevivencia y reclutamiento de las especies después de la quema. Se midió todas las clases diamétricas de la vegetación leñosa antes de la quema controlada y durante 3 años consecutivos después de la quema. Seleccionamos las 15 especies más abundantes en la clase diametrica <10 dap para evaluar el porcentaje de sobrevivencia y la actividad de rebrote después de la quema. Cambios en la densidad de plántulas para las 15 especies más abundantes y para las 15 especies menos abundantes fueron analizadas utilizando el análisis de varianza de medición repetido (ANOVA). También, evaluamos cambios en la densidad de plántulas para tres especies de interés a nivel internacional con respecto a su conservación. En la flora común del bosque seco se encontró tres estrategias principales utilizadas por las especies para contender con los incendios forestales, estas fueron: resistores (baja mortalidad por el incendio), rebrotadores (rebrotamiento vigoroso), y reclutores (reclutamiento elevado pos-incendio). Mientras la sobrevivencia de especies en el bosque seco en general fue relativamente alta a la de especies de bosque húmedo tropical, las especies con menor sobrevivencia utilizaron el reclutamiento ó rebrotamiento como estrategia para persistir en la comunidad boscosa. El mecanismo de dispersión de semilla, particularmente la dispersión eólica, parece ser un factor importante en el éxito de reclutamiento después de la quema. Las quemas controladas produjeron un aumento significativo en la densidad de plántulas para dos de las especies de interés para la conservación: Guaiacum sanctum L. (Zygophyllaceae) y Swietenia humilis Zucc. (Meliaceae). Resultados de esta investigación sugieren que las especies comunes del bosque seco de Nicaragua son tolerantes al fuego. Por lo tanto, es merecido hacer más estudios de estas especies y su comportamiento ante la perturbación del fuego. [source] Structure and Biomass of Four Lowland Neotropical ForestsBIOTROPICA, Issue 1 2004Saara J. DeWalt ABSTRACT We contrasted the structure and biomass of four lowland Neotropical forests (La Selva, Costa Rica; Barro Colorado Island, Panama; Cocha Cashu, Peru; and KM41, Brazil) to determine if commonalities exist within and among forests differing in latitude, rainfall, seasonality, and soil fertility. We examined the effect of soil fertility specifically by measuring the density and basal area of trees, lianas, and palms on two soil types differing in fertility at each site. We used allometric relationships to estimate the contribution of the various life-forms to total aboveground biomass (AGB) and compared two relationships for trees 30 cm diameter or greater. Estimated liana density and AGB were similar among sites, but the density and AGB of trees and palms, estimated using diameter alone, differed significantly. Basal area and AGB of trees 10 cm diameter at breast height (DBH) or greater differed among forests and averaged 30.2 m2/ha and 250 Mg/ha, respectively. Cocha Cashu and KM41 had higher tree basal area and AGB than La Selva or Barro Colorado Island. Across forests, lianas and small trees (1,10 cm DBH) each contributed between 4 and 5 percent of the total AGB and small palms contributed ca 1 percent. Many forest inventories ignore lianas, as well as trees and palms less than 10 cm DBH, and therefore underestimate AGB by ca 10 percent. Soil type had little influence on the forest structure within sites, except at Cocha Cashu where total AGB was much higher and liana density much lower on the more fertile old floodplain Entisols than the serra firme Oxisols. Although total stem density, basal area, and some biomass components differed significantly among forests, they seemed less variable than other quantitative measures (e.g., species richness). RESUMEN Contrastamos la estructura y la biomasa de cuatro bosques de bajura Neotropicales (La Selva, Costa Rica; Isla Barro Colorado, Panamá; Cocha Cashu, Perú; y KM41, Brasil) para determinar si existen patrones comunes entre bosques que difieren en la latitud, en la lluvia total, en la estacionalidad, y en la fertilidad de suelo. Examinamos el efecto de la fertilidad de suelo en cada sitio específicamente midiendo el área basal y densidad de árboles, lianas, y palmas en dos tipos de suelo que difieren en fertilidad. Usamos ecuaciones alométricas para estimar la contributión relativa de las varias formas de vida a la biomasa aérea (AGB) y comparamos dos ecuaciones para estimar biomasa con base en árboles , 30 cm diámetro. La densidad y AGB estimada de lianas fueron similares entre sitios, pero la densidad y AGB de árboles y palmas estimada en base solamente a diámetros fueron significativamente distintas. El área basal y la AGB de árboles , 10 cm diámetro a la altura de pecho (DAP) difirieron entre bosques y promediaron 30.2 m2/ ha y 250 Mg/ha. En Cocha Cashu y KM41 observamos mayor área basal y AGB para árboles que en La Selva o la Isla Barro Colorado. En general lianas y árboles pequeños (1,10 cm DAP) contribuyeron entre 4,5 porciento del AGB total cada uno y palmas pequeñas contribuyeron alrededor de 1 porciento. Muchos inventarios del bosque ignoran tanto las lianas como los árboles y palmas <10 cm DAP y por lo tanto subestiman AGB en alrededor de un 10 porciento. El tipo del suelo mostró una influencia pequena en la estructura del bosque dentro de sitios, menos en Cocha Cashu donde AGB total fue mucho más alto y densidad de lianas y palmas fue más bajo en los Entisols de mayor fertilidad que los Ultisols de menor fertilidad. Aunque la densidad de tallos, área basal, y algunos componentes de la biomasa difirieron significativamente entre bosques, estos parecieron menos variables que otras medidas cuanti-tativas (por ejemplo, riqueza de especies). [source] | |||||||||||||||||||||||||||||||