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Rosettes
Terms modified by Rosettes Selected AbstractsProtein fraction isolated from epididymal fluid re-associates sperm in vitro: Possible role of serpins in rat rosettes assemblyMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 5 2010María A. Monclus Abstract In many mammalian species, sperm associate as a consequence of the epididymal transit. From the classic Rouleaux in guinea pig to the most recent work in mouse and echidna, authors have focused mainly on a detailed morphological description of this phenomenon. Some of these articles have also begun to describe the nature of the material present between sperm heads. Here, we try to better understand the factor/s involved in rat sperm association (Rosette). Based on previous work describing the appearance of Rosettes in the distal segments of the rat epididymis, we consider that sperm during their transit must be in contact with factor/s present in the caudal lumen in order to associate with each other. By an in vitro sperm re-associating assay, we try to determine the in vivo phenomenon observed in the lumen. The assay consists of co-incubating non-associated sperm with several protein fractions obtained from epididymal caudal fluid. After establishing the most active fraction, the proteins were characterized by MALDI-TOF mass spectrometry. Among the proteins we found two members of the serine protease inhibitors family; an ,-1 antitrypsin and a new protein with an ,-1 antitrypsin like domain which includes a sequence compatible with the serpins' reactive center loop. These serpins may play a role in the assembly/disassembly process of Rosettes by modulating lumenal protease activity. Finally, a biochemical-morphological model which explains the sperm,proteases interaction was proposed. Mol. Reprod. Dev. 77: 410,419, 2010. © 2010 Wiley-Liss, Inc. [source] Genetic analysis identifies quantitative trait loci controlling rosette mineral concentrations in Arabidopsis thaliana under droughtNEW PHYTOLOGIST, Issue 1 2009Artak Ghandilyan Summary ,,Rosettes of 25 Arabidopsis thaliana accessions and an Antwerp-1 (An-1) × Landsberg erecta (Ler) population of recombinant inbred lines (RILs) grown in optimal watering conditions (OWC) and water deficit conditions (WDC) were analysed for mineral concentrations to identify genetic loci involved in adaptation of mineral homeostasis to drought stress. ,,Correlations between mineral concentrations were determined for accessions and a quantitative trait locus (QTL) analysis was performed for the RIL population. ,,Plant growth and rosette mineral contents strongly decreased in WDC compared with OWC. Mineral concentrations also generally decreased, except for phosphorus (P), which remained constant, and potassium (K), which increased. Large variations in mineral concentrations were observed among accessions, mostly correlated with total rosette leaf area. Mineral concentration QTLs were identified in the RIL population, but only a few were common for both conditions. Clusters of mineral concentration QTLs often cosegregated with dry weight QTLs. ,,Water deficit has a strong effect on rosette mineral status. This is genetically determined and seems largely a pleiotropic effect of the reduction in growth. The low number of common mineral concentration QTLs, shared among different RIL populations, tissues and conditions in Arabidopsis, suggests that breeding for robust, mineral biofortified crops will be complex. [source] Flowering Frequency and Plant Performance and their Relation to Age in the Perennial Orchid Spiranthes spiralis (L.) Chevall.PLANT BIOLOGY, Issue 3 2000J. H. Willems Abstract: Long-term demographic data have been analyzed to establish possible costs of flowering in the terrestrial orchid Spiranthes spiralis (L.) Chevall. in The Netherlands. Costs of flowering can be expressed as individual plant performance and flowering frequency in relation to the generative or vegetative status in the following year. Flowering in individuals of S. spiralis in a given year (t) is followed by a non-flowering phase in the next growing season (t + 1) in more than 80 % of the plants. The decline in flowering frequency is not a result of the age structure of the population involved because individual plants do not show signs of senescence after 10 - 15 years of aerial presence as an autotrophic plant. Rosettes have a smaller leaf area in the year of flowering (t), compared to the previous (t - 1) and following year (t + 1), due to the allocation of the limited underground resources to both flowering stalk and rosette at the beginning of its growing season. Generative reproduction in S. spiralis has a significant negative impact on both flowering frequency in subsequent years and on rosette size in the year of flowering. The flowering frequency and rosette size in relation to the life history, characterized by the yearly replacement of the underground tuber, is discussed. Better understanding of the life-history strategy, including costs of reproduction, may contribute to the creation of sustainable environmental conditions for growth of S. spiralis, e.g., optimal conditions for photosynthesis during the aboveground stage of the tiny wintergreen rosettes. [source] Surface morphology of eggs of Euproctis chrysorrhoea (Linnaeus, 1758)ACTA ZOOLOGICA, Issue 2 2008Selami Candan Abstract Candan, S., Suludere, Z. and Bayrakdar, F. 2007. Surface morphology of eggs of Euproctis chrysorrhoea (Linnaeus, 1758). ,Acta Zoologica (Stockholm) 88: 000,000. Filaments covering the egg batches and chorion structure were studied both by light and scanning electron microscopy in the brown-tailed moth Euproctis chrysorrhoea (Linnaeus, 1758). Females lay eggs in masses on the underside of apple leaves. The egg batches are covered with brown hairs derived from the bodies of the female. Each female lays about 200,400 eggs. The spherical eggs are about 0.84 mm long and 0.47 mm wide. Newly deposited eggs are golden-yellow and darken after the onset of embryonic development. The micropylar area appears somewhat depressed and has a circular outline. The region is surrounded by a rosette of 10,12 petal-shaped primary cells, which are completely surrounded by a series of secondary and tertiary cells. The remainder of the egg is largely smooth, but shows aeropyles. These are located in the corners of ill-defined polygons. [source] Notes on South American Valerianaceae I,FEDDES REPERTORIUM, Issue 7-8 2003F. Weberling Professor Dr. A new species of Belonanthus, Belonanthus theodorici sp. nova, is described. It is characterized by spathulate foliage leaves, the ovate blades of which are rather distinctly contracted into a long and narrow sheathing petiole and bear a dense covering with long hairs, giving the surface of the rosette a silvery sheen. In the monothyrsoid inflorescence the peduncles (hypopodia) of the lower partial inflorescences are considerably elongated. , Valeriana micropterinaWedd., V. poterioidesGraebn., V. thalictroidesGraebn. and V.aspleniifoliaKillip are included into Valeriana microptera. , For Valeriana fonkiiPhil. and V. radicalisClos reliable distinctive characters are named. , For Valeriana decussataRuiz & Pav. virescent calices with green sepals are described and illustrated. Anmerkungen zu südamerikanischen Valerianaceae I Es wird eine neue Belonanthus -Art aus Peru, Belonanthus theodorici sp. nova beschrieben. Diese ist gekennzeichnet durch ihre silberhaarigen Laubblätter und den Bau ihrer Infloreszenzen, deren cymöse Partialinfloreszenzen teilweise mit langgestreckten Hypopodien ausgestattet sind. Valeriana micropterinaWedd., V. poterioidesGraebn., V. thalictro-idesGraebn. und V. aspleniifoliaKillip sind unter dem Namen der erstgenannten vereinigt. Für Valeriana fonkiiPhil. und V. radicalisClos werden verlässliche Unterscheidungsmerkmale genannt. Vergrünte, mit sepaloiden Kelchblättern ausgestattete Kelche werden für Valeriana decussataRuiz & Pav. beschrieben und abgebildet. [source] Population structure and establishment of the threatened long-lived perennial Scorzonera humilis in relation to environmentJOURNAL OF APPLIED ECOLOGY, Issue 2 2002Guy Colling Summary 1The intensification of agriculture has resulted in the decline of many plant species of nutrient-poor wet grasslands. At some sites local populations of long-lived characteristic species have persisted and might benefit from recent extensification schemes. However, little is known about the population biology of these plants, and the prospects for the populations are uncertain. 2We studied the population structure and establishment of the long-lived Scorzonera humilis in 23 populations in Luxembourg and neighbouring Belgium. Two types of populations could be distinguished according to their population structure: regenerating populations, with a high proportion of plants with only one or a few rosettes, and aged populations, with a low proportion of small, young plants but a high proportion of individuals with many rosettes. The total density of Scorzonera individuals was higher in regenerating than in aged populations. 3Within sites, S. humilis was restricted to more open and nutrient-poor patches. The composition of the vegetation in plots where S. humilis was present was significantly different from that of plots without the species, indicating that S. humilis is restricted to particular microhabitats. 4In multiple regression analyses, environmental variables explained a large part of the variation in the total density of genets, the density of genets of different size and the density of rosettes. The main variables of influence were site productivity and soil moisture. With increasing productivity and decreasing soil moisture the proportion of small genets decreased and that of large genets increased. Increased productivity had contrasting effects at the genet and ramet (rosette) levels. While genet density decreased, ramet density increased, indicating that if a site is fertilized, recruitment of new genets and survival of genets is reduced, but growth of surviving genets is increased. 5The results of a sowing experiment indicated that an aged population structure was due to a lack of recruitment. The number of seeds that germinated and the proportion of seedlings that survived until the next summer were positively correlated with soil moisture and negatively with productivity. Germination rate and establishment success were significantly higher in Molinion grassland than in the Calthion grasslands. 6The results suggest that for long-lived species the size and number of populations may not be good indicators of the status of a species. In S. humilis large populations (> 1000 genets) still exist, but all are of the aged type. In order to preserve existing populations of S. humilis, management should aim to reduce productivity and increase soil moisture. [source] Characterization of Phytoplasmas Associated With Almond Diseases in IranJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2009L. Zirak Abstract In recent years, almond witches'-broom disease has been prevalent in almond growing areas in the centre and south of Iran. Furthermore, almond trees showing different symptoms of phytoplasma diseases such as little leaf, leaf rolling, dieback of branches, rosette and yellowing were observed in the central regions of Iran. DNA isolated from symptomatic almond trees was used to amplify 16S rDNA and 16S-23S rDNA intergenic spacer (IS) fragments by nested polymerase chain reaction (PCR) using phytoplasma universal primer pairs (P1/P7, R16F2/R2, PA2F/R and NPA2F/R). Phytoplasmas were detected in symptomatic almonds in two major almond-growing regions, Isfahan and ChaharMahal-O-Bakhtiari. Restriction fragment length polymorphism analyses of nested PCR products using endonuclease enzymes HpaII and TaqI revealed that phytoplasmas associated with infected almonds are genetically different. Sequence analyses of amplified fragments of 16S rDNA and IS region indicated that the almond phytoplasmas in Iran are closely related to ,Candidatus (Ca.) Phytoplasma aurantifolia', ,Ca. Phytoplasma phoenicium', ,Ca. Phytoplasma solani' and ,Ca. Phytoplasma trifolii'. The phytoplasmas related to ,Ca. Phytoplasma aurantifolia' were more prevalent than other phytoplasmas in the central regions of Iran. [source] KILLER WHALE PREDATION ON SPERM WHALES: OBSERVATIONS AND IMPLICATIONSMARINE MAMMAL SCIENCE, Issue 3 2001Robert L. Pitman Abstract In October 1997 we observed a herd of approximately 35 killer whales (Orcinus orca) attack a pod of nine sperm whales (Physeter macrocephalus) 130 km off the coast of central California. During the four hours we watched, adult female killer whales, including some with calves, attacked in waves of four to five animals in what was apparently a "wound and withdraw" strategy. Adult male killer whales stood by until the very end when one charged in and quickly killed a seriously wounded sperm whale that had been separated from the group. The sperm whales appeared largely helpless: their main defensive behavior was the formation of a rosette ("marguerite"-heads together, tails out). When the killer whales were successful in pulling an individual out of the rosette, one or two sperm whales exposed themselves to increased attack by leaving the rosette, flanking the isolated individual, and leading it back into the formation. Despite these efforts, one sperm whale was killed and eaten and the rest were seriously, perhaps mortally, wounded. We also present details of two other encounters between sperm whales and killer whales that we observed. Although sperm whales, because of various behavioral and morphological adaptations, were previously thought to be immune to predation, our observations clearly establish their vulnerability to killer whales. We suggest that killer whale predation has potentially been an important, and underrated, selective factor in the evolution of sperm whale ecology, influencing perhaps the development of their complex social behavior and at-sea distribution patterns. [source] The recently established diatom Coscinodiscus wailesii (Coscinodiscales, Bacillariophyta) in Brazilian waters.PHYCOLOGICAL RESEARCH, Issue 2 2001I: Remarks on morphology, distribution SUMMARY Coscinodiscus wailesii Gran et Angst is a large centric diatom (280,500 ,m diameter) from marine phytoplankton, characterized by a cylindrical frustule with flat valvar surface, two marginal rings of rimoportulae on the mantle, and two macrorimoportulae. Cells from cultured and natural populations collected in Paranaguá Bay, Paraná, southern Brazil were observed under light and scanning electron microscopes to verify the populations' correct identity and morphology. In both populations, a typical central rosette or a hyaline area was found in the valvar center. The species' distribution in Brazilian waters was revised, and a discussion on possible vectors of transport was made. Blooms of the species occur sporadically in the coast of Paraná, seeming to affect the local trophic chain. [source] Development of an HPLC-PAD-MS assay for the identification and quantification of major phenolic edelweiss (Leontopodium alpium Cass.) constituentsPHYTOCHEMICAL ANALYSIS, Issue 5 2006Stefan Schwaiger Abstract The analytical assessment of edelweiss (Leontopodium alpinum) herb extracts, used in traditional alpine medicine, has resulted in the development of a HPLC-PAD-MS method that allows baseline separation of almost all constituents. Peak assignment of 14 analytes was achieved by comparison of retention times, UV and mass spectra with those of reference compounds either commercially available (luteolin, apigenin and chlorogenic acid) or isolated from edelweiss plants by column chromatography. Ten of the isolated analytes were identified as the known natural products: quercetin-3- O - , - d -glucoside, luteolin-7- O - , - d -glucoside, luteolin-3,- O - , - d -glucoside, luteolin-4,- O - , - d -glucoside, apigenin-7- O - , - d -glucoside, 6-hydroxy-luteolin-7- O - , - d -glucoside, luteolin-7,4,-di- O - , - d -glucoside, chrysoeriol-7- O - , - d -glucoside, leontopodic acid and 3,5-dicaffeolyquinic acid. One analyte, 3,4,5-tri-(E)-caffeoly-d-glucaric acid proved to be a new natural product and was named leontopodic acid B. Structure elucidation was carried out by means of MS and NMR spectroscopy in all cases. The aerial plant parts of L. alpinum (capitula, inflorescence leaves, stems, stem leaves and leaves of the basal rosette) showed variable amounts of the above-mentioned constituents, although qualitative differences were not observable. Copyright © 2006 John Wiley & Sons, Ltd. [source] Herbivory and Abiotic Factors Affect Population Dynamics of Arabidopsis thaliana in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2005A. Mosleh Arany Abstract: Population dynamics of the annual plant Arabidopsis thaliana (L.) Heynh. were studied in a natural habitat of this species on the coastal dunes of the Netherlands. The main objective was to elucidate factors controlling population dynamics and the relative importance of factors affecting final population density. Permanent plots were established and plants were mapped to obtain data on survival and reproductive performance of each individual, with special attention to herbivore damage. In experimental plots we studied how watering, addition of nutrients, artificial disturbance, and natural herbivores affected survival and growth. Mortality was low during autumn and early winter and high at the time of stem elongation, between February and April. A key factor analysis showed a high correlation between mortality from February to April and total mortality. The specialist weevils Ceutorhyncus atomus and C. contractus (Curculionidae) were identified as the major insect herbivores on A. thaliana, reducing seed production by more than 40 %. These herbivores acted in a plant size-dependent manner, attacking a greater fraction of the fruits on large plants. While mortality rates were not affected by density, fecundity decreased with density, although the effect was small. Adding water reduced mortality in rosette and flowering plant stages. Soil disturbance did not increase seed germination, but did have a significant positive effect on survival of rosette and flowering plants. Seed production of A. thaliana populations varied greatly between years, leading to population fluctuations, with a small role for density-dependent fecundity and plant size-dependent herbivory. [source] Flowering Frequency and Plant Performance and their Relation to Age in the Perennial Orchid Spiranthes spiralis (L.) Chevall.PLANT BIOLOGY, Issue 3 2000J. H. Willems Abstract: Long-term demographic data have been analyzed to establish possible costs of flowering in the terrestrial orchid Spiranthes spiralis (L.) Chevall. in The Netherlands. Costs of flowering can be expressed as individual plant performance and flowering frequency in relation to the generative or vegetative status in the following year. Flowering in individuals of S. spiralis in a given year (t) is followed by a non-flowering phase in the next growing season (t + 1) in more than 80 % of the plants. The decline in flowering frequency is not a result of the age structure of the population involved because individual plants do not show signs of senescence after 10 - 15 years of aerial presence as an autotrophic plant. Rosettes have a smaller leaf area in the year of flowering (t), compared to the previous (t - 1) and following year (t + 1), due to the allocation of the limited underground resources to both flowering stalk and rosette at the beginning of its growing season. Generative reproduction in S. spiralis has a significant negative impact on both flowering frequency in subsequent years and on rosette size in the year of flowering. The flowering frequency and rosette size in relation to the life history, characterized by the yearly replacement of the underground tuber, is discussed. Better understanding of the life-history strategy, including costs of reproduction, may contribute to the creation of sustainable environmental conditions for growth of S. spiralis, e.g., optimal conditions for photosynthesis during the aboveground stage of the tiny wintergreen rosettes. [source] An overview of the microphysical structure of cirrus clouds observed during EMERALD-1THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 607 2005M. W. Gallagher Abstract High-resolution ice microphysical, turbulence, heat and water vapour flux data in cirrus clouds were collected by the Airborne Research Australia's (ARA) Egret Grob 520T research aircraft during the first Egret Microphysics with Extended Radiation and Lidar experiment (EMERALD-1). The in situ cirrus measurements were guided by simultaneous airborne lidar measurements collected by the ARA Super King Air research aircraft which flew below the cirrus and whose horizontal position was synchronized with the Egret. This allowed the microphysics and turbulence measurements to be interpreted and evaluated within the context of large-scale cirrus structure and its evolution. A significant feature of the clouds observed was the presence on occasion of active convective columns. Large variations in the cirrus dynamics were observed, with significant variations in the ice crystal habit from cloud top to cloud base and within the evaporating fall-streaks of precipitation. However, on average the picture presented is consistent with that shown by Heymsfield and Miloshevich, and by Kajikawa and Heymsfield, with the upper supersaturated region of the cloud acting as an active particle-generation zone where homogeneous nucleation proceeds apace; ice crystals there are initially dominated by small irregular or spheroidally shaped particles, some of which can be identified as proto or ,germ' rosettes. These are then observed to grow into more open bullet rosette and columnar types as they fall into the less supersaturated middle and lower layers of the cloud. The mean recognisable ice particle size fell within a very narrow size band, 70,90 µm, but the actual size distribution is thought to increase in a continuous manner to smaller sizes. However, there are currently instrument limitations that make it difficult to confirm this unambiguously. Unlike most previous studies, however, the cirrus clouds observed here were mostly devoid of pristine plate-like crystals, as nucleation and growth within the planar growth regime was rarely encountered. During some cases bullet rosettes, once formed, did undergo transition to the plate growth regime with complex crystal shapes resulting. The mean size of pristine bullet rosettes was again confined to a relatively narrow range. The likely nucleation processes dominating in cirrus clouds are discussed in the light of the observations. Very high concentrations of small ice crystals were sometimes detected, concentrations reaching a maximum of 10 000 L,1. There is strong evidence supporting these high concentrations which are probably produced by the homogeneous freezing of aerosol. Copyright © 2005 Royal Meteorological Society [source] Using biological traits to assess how urbanization filters plant species of small woodlandsAPPLIED VEGETATION SCIENCE, Issue 4 2010Jeanne Vallet Abstract Question: Which biological traits (persistence, regeneration, dispersion traits and resource requirements) may explain the distribution of woodland flora along an urban,rural gradient? Location: The study was carried out in three medium-sized conurbations of north-western France: Angers, Nantes and Rennes. Methods: We sampled the vegetation of 36 small woodlands of about 1.5 ha composed of non-planted vegetation along an urban,rural gradient. We characterized the position of woodlands along the urban,rural gradient by examining adjacent land cover. By using an ordination analysis (RLQ), we analysed which traits out of ,23 tested were related to the contrasted distribution of species along the urban,rural gradient. Results: Species that are more likely to be found in urban woodlands than rural woodlands have different persistence traits (higher specific leaf area, more often rosette or semi-rosette form, less underground vegetative multiplication), resource requirements (affinity for base-rich and fertile soils) and regeneration traits (short life-span). Dispersion traits were not related to the distribution of species along the urban,rural gradient. Conclusions: Our approach identifies traits that can help to determine the vulnerability of forest species as a result of the environmental changes that follow urbanization. Limiting the influence of the urban environment on habitat quality (particularly disturbance and soil enrichment) is likely to be of major importance in maintaining the plant biodiversity in woodlands. [source] An experimentally calibrated finite element study of maxillary traumaDENTAL TRAUMATOLOGY, Issue 5 2007Michael J Casas Abstract,,, A baseball injury to an instrumented human cadaver maxillae was simulated with a regulation (142 g) baseball traveling at 14 m s,1. Measurements of strain were obtained with three-axis strain gauge rosettes located at the medial palate and both canine fossae. A three-dimensional finite element (FE) model of a dentate human maxilla was constructed from computed tomography scans of the skull of an adolescent. This three-dimensional mathematical model of the maxilla was deemed geometrically accurate by convergence testing when the model's degrees of freedom approximated 74 000. The simulated load case involved a transient dynamic impact to the medial maxilla with boundary conditions imposed at skeletal buttresses of the model. The model was calibrated through direct comparison with the displacements and principal strains gathered from experimental and epidemiological data. The comparison of experimental and calculated principal strains as a result of the simulated impacts revealed a 1.7,11.4% difference. [source] Integration and differentiation of human embryonic stem cells transplanted to the chick embryoDEVELOPMENTAL DYNAMICS, Issue 1 2002Ronald S. Goldstein Abstract Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein,expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by ,-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells. © 2002 Wiley-Liss, Inc. [source] PNET-like features of synovial sarcoma of the lung: A pitfall in the cytologic diagnosis of soft-tissue tumorsDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2001Pascale Hummel M.D. Abstract Fine-needle aspiration (FNA) cytology of soft-tissue tumors is evolving. As more experience is gained, we are becoming aware of potential pitfalls. We describe 2 cases of synovial sarcoma of the lung, primary and metastatic, in patients who had FNA biopsy performed on a lung mass. The cytologic smears showed extremely cellular groups of malignant small round cells, intersected by small blood vessels, with numerous loose single cells, in a background of macrophages and mature lymphocytes. The tumors displayed monomorphic cells forming rosettes and displaying occasional mitoses. A diagnosis of neuroendocrine tumor/primitive neuroepithelial tumor (PNET) was suspected. Furthermore, this suspicion was supported by immunohistochemical stains, which showed positivity for a neuroendocrine marker, Leu 7 (case 1), and for a neural marker, CD 99 (O 13 or HBA 71) (both cases); and negativity for cytokeratins (case 1). The resection specimen of case 1 had mostly tightly packed small round cells, with occasional rosettes, similar to the FNA biopsy, and focal areas composed of spindle cells, organized in a focal fibrosarcoma-like and hemangiopericytoma-like pattern. A balanced translocation between chromosomes X and 18, demonstrated by both karyotyping and fluorescent in situ hybridization (FISH), enabled us to make a diagnosis of synovial sarcoma, which was histologically classified as poorly differentiated. Case 2 was a metastatic biphasic synovial sarcoma of the arm, with a prominent epithelial component. Synovial sarcoma, when composed mainly of small round cells on cytologic smears, is a great mimicker of neuroendocrine/PNET tumors, with light microscopic and immunohistochemical overlap. Awareness of this potential pitfall may aid in preventing a misdiagnosis. Its recognition is of major concern, especially for the poorly differentiated variant, because it is associated with a worse prognosis. Diagn. Cytopathol. 24:283,288, 2001. © 2001 Wiley-Liss, Inc. [source] Genetic Allee effects on performance, plasticity and developmental stability in a clonal plantECOLOGY LETTERS, Issue 6 2000M. Fischer Negative effects of small population size on fitness, so-called Allee effects, may threaten population persistence even in intact habitat remnants. We studied genotypes of 14 isolated populations of the clonal plant Ranunculus reptans, for which molecular genetic (RAPD-) variability is higher for large than for small populations. In a competition-free greenhouse environment vegetative offspring of genotypes from large populations produced more rosettes and flowers, indicating higher fitness. Within-genotype coefficients of variation in performance traits, indicating developmental instability, were lower for genotypes from populations with higher RAPD-variability. In competition with a taller grass, we found relative reduction in leaf length less pronounced for plants from large populations, suggesting higher adaptive plasticity. Our experimental study of a plant with predominantly vegetative reproduction suggests, that negative genetic effects of recent habitat fragmentation, which so far rather were expected in plants with frequent sexual reproduction, are more severe and more common than previously acknowledged. [source] Distribution of mossy fibre rosettes in the cerebellum of cat and mice: evidence for a parasagittal organization at the single fibre levelEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2001Fahad SultanArticle first published online: 20 DEC 200 Abstract Mossy fibres are the main afferent input to the granular layer of the cerebellar cortex. In this study, the spatial distribution of the mossy fibres' presynaptic enlargements , the so-called rosettes , were analysed on the single fibre level. Data obtained from the cerebella of cat and mice were compared to look for species differences, and the cerebella of the adult and young mice were also compared to look for developmental changes. The results show that there is a spatial anisotropy in all mossy fibres studied, with neighbouring rosettes being about three times further away from each other along the parasagittal axis and closer to each other in the mediolateral direction. Furthermore, these results suggest that this anisotropy is established at an early developmental stage. The anisotropic orientation of mossy fibres at the single fibre level supports the hypothesis of a timing mechanism in cerebellar function. [source] Clonal diversity and subpopulation structure in central European relict populations of Saxifraga paniculataMill. (Saxifragaceae)FEDDES REPERTORIUM, Issue 3-4 2004C. Reisch Saxifraga paniculata is a rare and endangered glacial relict in central Europe. It shows high clonal reproduction. In this study, we analysed the clonal diversity and the subpopulation structure of three populations from the species main distribution area in Germany outside of the Alps (Swabian Alb, Black Forest, Nahe Mountains). We used RAPD analysis to detect the genetic variation in S. paniculata and found high levels of clonal diversity. The percentage of distinguishable genotypes (PD) within populations of S. paniculata was 1.0 and even spatially well defined mats of rosettes consisted of several genotypes. In a cluster analysis, the investigated populations were clearly separated from each other. However, we detected no genetic differentiation among subpopulations. We ascribe the high level of genotypic variability to the species' mixed mating system, which creates and maintains high levels of genetic diversity within the populations of S. paniculata. Clonal reproduction seems, meanwhile, to be of secondary importance for the propagation of the species. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Klonale Diversität und Subpopulationsstruktur in mitteleuropäischen Reliktpopulationen von Saxifraga paniculataMill. (Saxifragaceae) Saxifraga paniculata ist in Mitteleuropa ein seltenes und gefährdetes Glazialrelikt, das sich durch die Fähigkeit zu starker klonaler Reproduktion auszeichnet. Die vorliegende Arbeit befasst sich mit der klonalen Diversität und der Subpopulationsstruktur von drei Populationen aus dem Hauptverbreitungsgebiet der Art außerhalb der Alpen (Schwäbische Alb, Schwarzwald, Nahe-Bergland). Die genetische Variabilität wurde mittels RAPD-Analyse untersucht. Dabei konnte ein hohes Maß an klonaler Diversität festgestellt werden. Der Prozentsatz unterscheidbarer Genotypen innerhalb einer Population (PD) betrug 1.0 und selbst größere Matten, deren Entstehung nach rein morphologischer Einschätzung auf klonalem Wachstum beruhen müsste, bestanden aus mehreren Genotypen. In einer Clusteranalyse unterschieden sich die analysierten Populationen klar voneinander. Unterschiede zwischen Subpopulationen konnten jedoch nicht nachgewiesen werden. Das hohe Ausmaß an genetischer Diversität kann dem "mixed mating system" der Art zugeschrieben werden, das genetische Variabilität schafft und erhält. Klonales Wachstum scheint währenddessen eher von zweitrangiger Bedeutung für die Vermehrung der Art zu sein. [source] Allelopathic effect of the aquatic macrophyte, Stratiotes aloides, on natural phytoplanktonFRESHWATER BIOLOGY, Issue 3 2006GABI MULDERIJ Summary 1. A survey of different Dutch Stratiotes stands showed that the density of phytoplankton (except cyanobacteria) was always higher outside S. aloides than between the rosettes of S. aloides. Analyses of water samples revealed that nutrient limitation was unlikely to have caused the lower phytoplankton biomass in the vicinity of S. aloides. 2. An in situ incubation experiment in the Danube Delta, Romania, indicated allelopathic activity against phytoplankton in S. aloides stands. The growth rate of natural phytoplankton populations exposed to water from S. aloides stands was significantly lower than that of populations that had not been in contact with S. aloides exudates. 3. A laboratory microcosm experiment showed a significantly lower phytoplankton biomass in treatments with S. aloides exudates. Nutrient concentrations and the light intensity were high enough that the lower phytoplankton biomass could not be explained by nutrient or light limitation. [source] The effects of plant structure on the spatial and microspatial distribution of a bromeliad-living jumping spider (Salticidae)JOURNAL OF ANIMAL ECOLOGY, Issue 1 2005GUSTAVO Q. ROMERO Summary 1In several regions of South America, the neotropical jumping spider Psecas chapoda inhabits and reproduces strictly on the bromeliad Bromelia balansae. Previous studies reported that this spider is more frequent on bromeliads in grasslands than on those growing in forests, and on larger plants, but only when the bromeliads are without inflorescence. Upon blooming, B. balansae fold their leaves back, thereby changing the plant architecture from a tri-dimensional to a bi-dimensional flattened shape, and our hypothesis is that this alteration affects the spider's habitat-selection decisions. 2In the present study, we examined experimentally the effects of inflorescence, plant size and blockade of the axil of the leaves (spider shelters) of forest bromeliads on the colonization of a bromeliad by P. chapoda. By using sticky traps, we also compared prey availability in grassland and forest. 3Plants with simulated inflorescence were colonized at a lower frequency than those without inflorescence simulation. Grassland bromeliads in which the rosettes were blocked with dry leaves were colonized less frequently than open bromeliads, whereas forest bromeliads from which dry leaves had been removed were not colonized. Spiders generally abandoned bromeliads in which three-quarters of the length of the leaves had been removed, although females with eggsacs remained on these plants. Prey availability (biomass and number) was up to 18 fold higher in the grassland than in the forest. These results suggest that microhabitat structure and prey availability shape the spatial distribution of P. chapoda populations. 4Our findings suggest that Psecas chapoda can evaluate, in fine detail, the physical state of its microhabitat, and this unusual spider,plant association is readily destabilized by changes in the microhabitat (i.e., it is strictly dependent on the size and morphology of the host plant). This study is one of the few to report a strict association between a spider species and its host plant, and also one of the few to examine the effects of habitat and microhabitat structure on the spatial distribution of active hunters on plants. [source] Population structure and establishment of the threatened long-lived perennial Scorzonera humilis in relation to environmentJOURNAL OF APPLIED ECOLOGY, Issue 2 2002Guy Colling Summary 1The intensification of agriculture has resulted in the decline of many plant species of nutrient-poor wet grasslands. At some sites local populations of long-lived characteristic species have persisted and might benefit from recent extensification schemes. However, little is known about the population biology of these plants, and the prospects for the populations are uncertain. 2We studied the population structure and establishment of the long-lived Scorzonera humilis in 23 populations in Luxembourg and neighbouring Belgium. Two types of populations could be distinguished according to their population structure: regenerating populations, with a high proportion of plants with only one or a few rosettes, and aged populations, with a low proportion of small, young plants but a high proportion of individuals with many rosettes. The total density of Scorzonera individuals was higher in regenerating than in aged populations. 3Within sites, S. humilis was restricted to more open and nutrient-poor patches. The composition of the vegetation in plots where S. humilis was present was significantly different from that of plots without the species, indicating that S. humilis is restricted to particular microhabitats. 4In multiple regression analyses, environmental variables explained a large part of the variation in the total density of genets, the density of genets of different size and the density of rosettes. The main variables of influence were site productivity and soil moisture. With increasing productivity and decreasing soil moisture the proportion of small genets decreased and that of large genets increased. Increased productivity had contrasting effects at the genet and ramet (rosette) levels. While genet density decreased, ramet density increased, indicating that if a site is fertilized, recruitment of new genets and survival of genets is reduced, but growth of surviving genets is increased. 5The results of a sowing experiment indicated that an aged population structure was due to a lack of recruitment. The number of seeds that germinated and the proportion of seedlings that survived until the next summer were positively correlated with soil moisture and negatively with productivity. Germination rate and establishment success were significantly higher in Molinion grassland than in the Calthion grasslands. 6The results suggest that for long-lived species the size and number of populations may not be good indicators of the status of a species. In S. humilis large populations (> 1000 genets) still exist, but all are of the aged type. In order to preserve existing populations of S. humilis, management should aim to reduce productivity and increase soil moisture. [source] Evidence for a combination of pre-adapted traits and rapid adaptive change in the invasive plant Centaurea stoebeJOURNAL OF ECOLOGY, Issue 4 2010Martin L. Henery Summary 1. Introduced plants have the potential to rapidly evolve traits of ecological importance that may add to their innate potential to become invasive. During invasions, selection may favour genotypes that are already pre-adapted to conditions in the new habitat and, over time, alter the characteristics of subsequent generations. 2. Spotted knapweed (Centaurea stoebe) occurs in two predominantly spatially separated cytotypes in its native range (Europe,Western Asia), but currently only the tetraploid form has been confirmed in the introduced range (North America), where it is invasive. We used several common garden experiments to examine, across multiple populations, whether tetraploids and diploids from the native range differ in life cycle, leaf traits and reproductive capacity and if such differences would explain the predominance of tetraploids and their advance into new habitats in the introduced range. We also compared the same traits in tetraploids from the native and introduced range to determine whether any rapid adaptive changes had occurred since introduction that may have enhanced invasive potential of the species in North America. 3. We found tetraploids had lower specific leaf area, less lamina dissection and fewer, narrower leaves than diploids. Diploids exhibited a monocarpic life cycle and produced few if any accessory rosettes. Diploids produced significantly more seeds per capitulum and had more capitula per plant than tetraploids. In contrast, the vast majority of European tetraploids continued to flower in both seasons by regenerating from multiple secondary rosettes, demonstrating a predominantly polycarpic life cycle. 4. During early growth tetraploids from North America achieved greater biomass than both tetraploids and diploids from the native range but this did not manifest as larger above-ground biomass at maturity. In North American tetraploids there was also evidence of a shift towards a more strictly polycarpic life cycle, less leaf dissection, greater carbon investment per leaf, and greater seed production per capitulum. 5.,Synthesis. Our results suggest that the characteristics of tetraploid C. stoebe pre-adapted them (compared to diploid conspecifics) for spread and persistence of the species into habitats in North America characterized by a more continental climate. After the species' introduction, small but potentially important shifts in tetraploid biology have occurred that may have contributed significantly to successful invasion. [source] Habitat fragmentation and adaptation: a reciprocal replant,transplant experiment among 15 populations of Lychnis flos-cuculiJOURNAL OF ECOLOGY, Issue 5 2008Gillianne Bowman Summary 1Habitat fragmentation and variation in habitat quality can both affect plant performance, but their effects have rarely been studied in combination. We thus examined plant performance in response to differences in habitat quality for a species subject to habitat fragmentation, the common but declining perennial herb Lychnis flos-cuculi. 2We reciprocally transplanted plants between 15 fen grasslands in north-east Switzerland and recorded plant performance for 4 years. 3Variation between the 15 target sites was the most important factor and affected all measures of plant performance in all years. This demonstrates the importance of plastic responses to habitat quality for plant performance. 4Plants from smaller populations produced fewer rosettes than plants from larger populations in the first year of the replant,transplant experiment. 5Plant performance decreased with increasing ecological difference between grassland of origin and target grassland, indicating adaptation to ecological conditions. In contrast, plant performance was not influenced by microsatellite distance and hardly by geographic distance between grassland of origin and target grassland. 6Plants originating from larger populations were better able to cope with larger ecological differences between transplantation site and site of origin. 7Synthesis: In addition to the direct effects of target grasslands, both habitat fragmentation, through reduced population size, and adaptation to habitats of different quality, contributed to the performance of L. flos-cuculi. This underlines that habitat fragmentation also affects species that are still common. Moreover, it suggests that restoration projects involving L. flos-cuculi should use plant material from large populations living in habitats similar to the restoration site. Finally, our results bring into question whether plants in small habitat remnants will be able to cope with future environmental change. [source] Demography and population dynamics of Drosera anglica and D. rotundifoliaJOURNAL OF ECOLOGY, Issue 1 2004J.-F. Nordbakken Summary 1We studied demography and population dynamics of the sympatric perennial herbs Drosera anglica and D. rotundifolia on a boreal bog in SE Norway. Dry mass of 2872 D. anglica plants and 2467 D. rotundifolia plants (estimated from field morphological measurements) was used to classify plants into five species-specific size classes. Demographic changes within these two populations were followed from 1995 to 1999, and within segments (quartiles) along the water table gradient and the peat productivity gradient. 2Mortality was strongly size dependent, and varied between years, for both species; it was high for seedlings, low for the smallest mature rosettes and increased again for the largest mature rosettes. The proportion of fertile rosettes increased with increasing rosette size. Fecundity varied considerably between years, but little relative to gradient position. 3Growth rate (,) was > 1, except in the second year, when it fell to 0.572 for D. anglica and 0.627 for D. rotundifolia . For D. anglica small, but significant, differences were found between the two extremities of the water table gradient, and for D. rotundifolia between the second and the uppermost quartile. There was a tendency for D. anglica populations to have a lower growth rate in the most productive sites, whereas D. rotundifolia grew less on both low and high peat productivity. Elasticity analysis showed that stasis and size increase (primarily within mature stages) made major contributions to , for D. anglica in all years. 4The variance in population growth rate (var ,) was high between years, and higher for D. anglica than for D. rotundifolia , while the variance between quartiles along the two main gradients was low. Life-table response experiment (LTRE) analyses revealed that for both species, differences in probabilities of transitions within mature stages, and in growth to larger stages, contributed most to var ,. 5The effects of global warming are uncertain: drier growing seasons would affect Drosera populations negatively, while initially positive responses to a wetter climate may be balanced by competition from increased Sphagnum growth. [source] Vernalization requirement of wild beet Beta vulgaris ssp. maritima: among population variation and its adaptive significanceJOURNAL OF ECOLOGY, Issue 4 2002Pierre Boudry Summary 1Seven populations of Beta vulgaris ssp. maritima (wild beet) situated along a latitudinal cline were studied for their vernalization requirement and its consequences for fitness. 2Various cold regimes were applied in glasshouses and experimental gardens with plants of different ages. Three additional experimental sites (on the French Mediterranean, Atlantic and North Sea coasts) situated near three of the sampled populations, and thus including a reciprocal transplant design, were used to evaluate the influence of latitude under natural conditions. Survival and plant size were measured over 3 years. 3The vernalization requirement was greater in plants from more northern origins. The level of cold required to allow flowering overcompensated for the colder springs, so that northern plants in northern sites flowered less than southern plants in southern sites. 4Young seedlings were more difficult to vernalize than plants that had already developed vegetative rosettes. 5Differences in vernalization requirement seem to be an adaptive response to spring temperatures and season length in a particular latitude. A whole winter vernalization almost always led to flowering in the subsequent year whatever the latitude or geographical origin. 6Plants from the Atlantic and Channel coasts showed the highest lifetime reproductive success at all sites. Southern populations were better adapted to disturbed habitats as shown by their higher first-year reproductive success. The North Sea population had a lower reproductive success than the Atlantic populations, even in its native environment. [source] Demographic variation and population viability in Gentianella campestris: effects of grassland management and environmental stochasticityJOURNAL OF ECOLOGY, Issue 3 2001Tommy Lennartsson Summary 1,Transition matrix models were used to evaluate the effects of environmental stochasticity and four different methods of grassland management on dynamics and viability of a population of the biennial Gentianella campestris (Gentianaceae) in species-rich grassland. Data were collected between 1990 and 1995. 2,Continuous summer grazing, the prevailing management strategy in Scandinavian grasslands, resulted in high recruitment of new plants, mainly because litter accumulation was prevented and gaps were created by trampling. Trampling and repeated grazing, however, caused damage which reduced seed production. Lambda for the average matrix was c. 0.77, and a stochastic matrix model yielded an extinction probability for the total population of c. 0.08 within 50 years. 3,Mowing in mid-July (used as a conservation tool) increased seed production, but litter accumulation following re-growth of the vegetation prevented establishment. Lambda and extinction risk were similar to continuous grazing. 4,Mowing in October (another conservation tool) promoted recruitment because of low litter accumulation, but the seed output decreased because plant growth was impaired by tall vegetation. Lambda was 0.64, while the extinction probability was very high (c. 0.98 within 50 years). 5,Mid-July mowing followed by autumn grazing (the historical management regime) yielded high values for both seed production and establishment of rosettes. Lambda was 0.94 and the probability of extinction within 50 years was below detection level. 6,Log-linear analysis showed that the matrices differed significantly both between treatments and between years. The latter indicates environmental stochasticity, here caused by summer drought that increased the extinction risk. Lambda may be slightly underestimated because drought occurred in one out of five summers during the study period, which is high compared with the natural frequency. 7,We conclude that traditional grassland management is more favourable for G. campestris than the methods that prevail in Scandinavia today. This indicates a serious conservation problem, because grazing has replaced traditional management in many of the remaining semi-natural grasslands throughout Europe. [source] Reduced fecundity and offspring performance in small populations of the declining grassland plants Primula veris and Gentiana luteaJOURNAL OF ECOLOGY, Issue 1 2000Marc Kéry Summary 1,We studied reproduction and offspring performance in relation to population size in the declining self-incompatible perennials Primula veris and Gentiana lutea. In both species, reproduction was strongly reduced in small populations, where plants produced fewer seeds per fruit and per plant. Total seed mass per plant was higher in large populations, but individual seeds were smaller, indicating a trade-off between seed number and size. Reproduction was depressed most strongly in populations consisting of less than c. 200 (P. veris) and c. 500 plants (G. lutea), respectively. 2,The inclusion of plant size (an integrated measure of habitat quality) in the statistical models did not change the relationships between fecundity and population size. Pollen limitation or inbreeding depression in small populations are therefore more likely explanations for these patterns than is habitat quality. 3,Germination rate and survival of seedlings in a common environment was not related to population size in either species, although P. veris developed into larger rosettes when seeds were derived from large populations. This suggests that inbreeding depression occurs in small populations of P. veris. 4,In a factorial fertilizer-by-competition experiment with P. veris, offspring from larger populations grew significantly larger and responded more strongly to fertilizer. For this declining species genetic deterioration as a result of habitat fragmentation may therefore aggravate the effects of environmental changes such as habitat eutrophication. 5,Our results suggest that small populations may face an increased short-term risk of extinction because of reduced reproduction, and an increased long-term risk because they are less able to respond to environmental changes. [source] Detection of disseminated tumour cells in bone marrow of patients with isolated liver metastases from colorectal cancerJOURNAL OF SURGICAL ONCOLOGY, Issue 4 2003Kristin Bjørnland MD Abstract Background and Objectives In colorectal cancer (CRC) patients, tumour recurrence is common following potentially curative surgery for liver metastases. This may be caused by occult tumour cells present at the time of surgery. Dissemination of micrometastatic cells may occur early in patients with solid cancer, and micrometastases may signify a poor prognosis. The aim of the present study was to evaluate the frequency of micrometastatic cells in the bone marrow of patients with potentially resectable liver metastases. Methods Twenty millilitres of bone marrow was aspirated from both anterior iliac crests from 48 patients. Mononuclear cells were isolated and incubated with superparamagnetic Dynabeads® coated with an anti-epithelial monoclonal antibody (MOC31). Magnetically selected cells were identified by light microscopy as cells with bead rosettes (>5 beads/cell). Results Micrometastatic tumour cells were identified in four of 48 (8%) patients who all had their liver metastases surgically removed. Two of the four died after 17 and 18 months, respectively, whereas two are alive after 10 and 12 months. None of the 19 inoperable patients had micrometastases. Conclusions The frequency of bone marrow micrometastases in patients with clinically isolated liver metastases from CRC was low. This is biologically interesting, but bone marrow status should not affect current treatment protocols. J. Surg. Oncol. 2003;82:224,227. © 2003 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||