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Disappearance
Kinds of Disappearance Terms modified by Disappearance Selected AbstractsDISAPPEARANCE OF MALE MITOCHONDRIAL DNA AFTER THE FOUR-CELL STAGE IN SPOROPHYTES OF THE ISOGAMOUS BROWN ALGA SCYTOSIPHON LOMENTARIA (SCYTOSIPHONACEAE, PHAEOPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 1 2010Kei Kimura Mitochondrial DNA (mtDNA) of the isogamous brown alga Scytosiphon lomentaria (Lyngb.) Link is inherited maternally. We used molecular biological and morphological analyses to investigate the fate of male mitochondria. Ultrastructural observations showed that the number of 25 mitochondria in a zygote coincided with the number of mitochondria derived from male and female gametes. This number remained almost constant during the first cell division. Strain-specific PCR in single germlings suggested that mtDNA derived from the female gamete remained in the germling during development, while the male mtDNA gradually and selectively disappeared after the four-cell stage. One week after fertilization, male mtDNA had disappeared in sporophytic cells. Using bisulfite DNA modification and methylation mapping assays, we found that the degree of methylation on three analyzed sites of mtDNA was not different between male and female gametes, suggesting that maternal inheritance of mtDNA is not defined by its methylation. This study indicates that the mechanism of selective elimination of male mtDNA is present in each cell of a four-celled sporophyte and that it does not depend on different degrees of DNA methylation between male and female mtDNA. [source] Disappearance of gender-related difference in the toxicity of benzotriazole ultraviolet absorber in juvenile ratsCONGENITAL ANOMALIES, Issue 4 2009Mutsuko Hirata-Koizumi ABSTRACT 2-(2,-hydroxy-3,,5,-di- tert -butylphenyl)benzotriazole (HDBB) is an ultraviolet absorber used in plastic resin products, such as building materials and automobile components. In oral repeated dose toxicity studies using 5- or 6-week-old rats, this chemical induced hepatic histopathological changes, such as hypertrophy accompanied with eosinophilic granular changes and focal necrosis of hepatocytes, and male rats showed nearly 25 times higher susceptibility to the toxic effects than females. Castration at approximately 4 weeks of age markedly reduced the sex-related variation in HDBB toxicity, but some difference, less than five times, remained between male and female castrated rats. Following oral HDBB administration to male and female juvenile rats from postnatal days 4,21, such gender-related difference in toxic susceptibility was not detected; therefore, it is speculated that the determinants of susceptibility to HDBB toxicity are differentiated between sexes after weaning. In young rats given HDBB, there was no gender-related difference in plasma HDBB concentration, and no metabolites were detected in the plasma of either sex. HDBB induced lauric acid 12-hydroxylase activity in the liver and this change was more pronounced in males than in females. These findings indicate that HDBB could show hepatic peroxisome proliferation activity, and the difference in the susceptibility of male and female rats to this effect might lead to marked gender-related differences in toxicity. [source] Epidemiologic Analysis of Factors Associated with Local Disappearances of Native Ranid Frogs in ArizonaCONSERVATION BIOLOGY, Issue 2 2008CARMEL L. WITTE análisis de factores de riesgo; declinación de anfibios; declinación de ranas; epidemiología de vida silvestre; métodos de control de casos Abstract:,We examined factors that may independently or synergistically contribute to amphibian population declines. We used epidemiologic case,control methodology to sample and analyze a large database developed and maintained by the Arizona Game and Fish Department that describes historical and currently known ranid frog localities in Arizona, U.S.A. Sites with historical documentation of target ranid species (n= 324) were evaluated to identify locations where frogs had disappeared during the study period (case sites) and locations where frog populations persisted (control sites). Between 1986 and 2003, 117 (36%) of the 324 sites became case sites, of which 105 were used in the analyses. An equal number of control sites were sampled to control for the effects of time. Risk factors, or predictor variables, were defined from environmental data summarized during site surveys and geographic information system data layers. We evaluated risk factors with univariate and multifactorial logistic-regression analyses to derive odds ratios (OR). Odds for local population disappearance were significantly related to 4 factors in the multifactorial model. Disappearance of frog populations increased with increasing elevation (OR = 2.7 for every 500 m, p < 0.01). Sites where disappearances occurred were 4.3 times more likely to have other nearby sites that also experienced disappearances (OR = 4.3, p < 0.01), whereas the odds of disappearance were 6.7 times less (OR = 0.15, p < 0.01) when there was a source population nearby. Sites with disappearances were 2.6 times more likely to have introduced crayfish than were control sites (OR = 2.6, p= 0.04). The identification of factors associated with frog disappearances increases understanding of declines occurring in natural populations and aids in conservation efforts to reestablish and protect native ranids by identifying and prioritizing implicated threats. Resumen:,Examinamos los factores que pueden contribuir independiente o sinérgicamente a la declinación de poblaciones de anfibios. Utilizamos una metodología epidemiológica de control de casos para muestrear y analizar una base de datos desarrollada y mantenida por el Departamento de Caza y Pesca de Arizona que describe las localidades históricas y actuales de ranas en Arizona, E. U. A. Los sitios con documentación histórica de las especies de ránidos (n= 324) fueron evaluados para identificar localidades donde las ranas desaparecieron durante el período de estudio (sitios caso) y localidades donde las poblaciones de ranas persistieron (sitios control). Entre 1986 y 2003, 36% (117) de los 324 sitios se volvieron sitios caso, de los cuales 105 fueron utilizados en los análisis. El mismo número de sitios control fueron muestreados para controlar los efectos del tiempo. Los factores de riesgo, o variables predictivas, fueron definidos a partir de datos ambientales obtenidos de los muestreos en los sitios y de capas de datos de un sistema información geográfica. Evaluamos los factores de riesgo con análisis de regresión logística univariada y multivariada para derivar proporciones de probabilidades (PP). Las probabilidad para la desaparición de una población local estuvo relacionada significativamente con 4 factores en el modelo multifactorial. La desaparición de poblaciones de ranas incrementó con la elevación (PP = 2.7 por cada 500 m, p < 0.01). Los sitios donde ocurrieron las desapariciones fueron 4.3 veces más propensos a estar cerca de otros sitios donde ocurrieron desapariciones (PP = 4.3, p < 0.01), mientras que la probabilidad de desaparición fue 6.7 veces menos (PP = 0.15, p < 0.01) cuando había una población fuente cercana. Los sitios con desapariciones fueron 2.6 veces más propensos a tener langostinos introducidos que los sitios control (PP = 2.6, p= 0.04). La identificación de factores asociados con la desaparición de ranas incrementa el conocimiento de las declinaciones de poblaciones naturales y ayuda a los esfuerzos de conservación para el reestablecimiento y la protección de ránidos nativos mediante la identificación y priorización de las amenazas implicadas. [source] Gravitational unloading inhibits the regenerative potential of atrophied soleus muscle in miceACTA PHYSIOLOGICA, Issue 3 2009Y. Matsuba Abstract Aim:, The present study was performed to investigate the influence of unloading on the regeneration of atrophied and injured skeletal muscle. Methods:, Male mice (C57BL/6J), aged 8 weeks, were used. Cardiotoxin (CTX) was injected into soleus muscles bilaterally. Gravitational unloading on soleus muscle was performed by hind limb suspension for 2 weeks before and additionally 6 weeks after CTX injection in one group. Soleus muscles in the remaining groups were loaded keeping the mice in the cages and were dissected 14, 28 and 42 days after the injection. Results:, Recovery of the wet weight and protein content of soleus in the CTX-injected group was inhibited by unloading. Increase in satellite cell number, induced by CTX injection and loading, was also inhibited by unloading. Disappearance of infiltration of mononucleated cells into the necrotic area was also delayed. This phenomenon suggests that regeneration, which is indicated by the appearance of fibres with central nuclei, was inhibited by unloading. Conclusion:, Results suggested that loading plays an important role in the activation of the regenerating potential of injured skeletal muscle. [source] ,, ,-Unsaturated sulfophenylcarboxylates as degradation intermediates of linear alkylbenzenesulfonates: Evidence for ,-oxygenation followed by ,-oxidations by liquid chromatography-mass spectrometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2002Peter Eichhorn Abstract Liquid chromatography with an electrospray interface to a mass spectrometer (LC-ES-MS) and LC-ES coupled to a tandem MS (LC-ES-MS/MS) were used to detect and identify intermediates excreted transiently during the aerobic degradation of linear alkylbenzenesulfonates (LAS) in fixed-bed bioreactors (FBBR). The inoculum for the FBBR was the microflora of the River Rhine, Germany. Two major phenomena were observed on the addition of 100 mg/L LAS to the system, sorption and then biodegradation. Disappearance due to sorption was followed in an inhibited FBBR. Biodegradation of LAS started on day 7 and was accompanied by the transient excretion of intermediates, which were later largely degraded. We detected not only the sulfophenylcarboxylates (SPCs) observed previously but also the ,, ,-unsaturated SPCs (SPC-2H), which have not been reported before. Experiments with the (4-sulfophenyl)dodecanes (C12-LAS), which had minor contaminants of C11-LAS, showed C12-, C10-, C8-, C6-, and C4-SPCs when LAS was degraded as well as traces of C9-, C7-, and C5-SPCs. Signals from the SPC-2H species were usually some 10% of those from the corresponding SPCs. Samples from these experiments were also examined by gas chromatography-mass spectrometry (GC-MS), but no desulfonated intermediates were detected. We interpret the data to mean that the only attack on LAS was by ,-oxygenation; there was no visible initial desulfonation. The products of ,-oxygenation were oxidized to the corresponding SPC and subject to ,-oxidation, as evidenced not only by the pattern of C-2 units in the excreted SPCs but also in the corresponding series of SPC-2H, representing the intermediates in ,-oxidation. [source] Esophageal ulcer of Crohn's disease: Disappearance in 1 week with infliximabINFLAMMATORY BOWEL DISEASES, Issue 8 2009Mitsuro Chiba MD No abstract is available for this article. [source] Natural course of hepatic focal nodular hyperplasia: A long-term follow-up study with sonographyJOURNAL OF CLINICAL ULTRASOUND, Issue 3 2009Yuan-Hung Kuo MD Abstract Purpose. We aimed to investigate the natural course of hepatic focal nodular hyperplasia (FNH) in a long-term follow-up study with sonography. Method. This study comprised 30 patients (24 women and 6 men) with 34 FNHs. Diagnosis of FNH was made using color Doppler sonography, contrast-enhanced CT, or MRI in combination with needle biopsy. Patients were followed every 3 to 6 months with sonography. Regression or progression of tumor was defined as a change of over 30% in maximal diameter. Disappearance was defined as no vizualization of the tumor on at least 3 follow-up sonographic examinations. Results. Thirty-four FNHs were followed over a mean period of 42 months (range, 7,95 months). Twenty-four lesions (70.6%) were stable in size, 1 (2.9%) progressed, and 9 (26.5%) regressed. Of those that regressed, 6 (17.6%) disappeared over a mean period of 59 ± 30 months (range, 20,95 months). Older age (OR 1.26, 95% CI 1.02,1.56; p < 0.05) and longer follow-up time (OR 1.11, 95% CI 1.01,1.21; p < 0.05) were the independent factors associated with complete regression of FNH. Conclusion. Most FNHs were stable or regressed/disappeared after a long follow-up period. Based on the benign course, conservative treatment for asymptomatic FNH should be advocated. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound 2009. [source] Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)JOURNAL OF FOOD SCIENCE, Issue 8 2009Thammarat Kaewmanee ABSTRACT:, Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp (Litopenaeus vannamei) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss (P,< 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate (P,> 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) (P,< 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties. [source] Infliximab for refractory ulcerative proctitisALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 11 2010G. BOUGUEN Aliment Pharmacol Ther,31, 1178,1185 Summary Background, Efficacy of infliximab in treating ulcerative proctitis remains unknown. Aim, To evaluate the clinical, biological and endoscopic efficacy of infliximab therapy in refractory proctitis. Methods, The charts of 420 patients treated with infliximab for ulcerative colitis were reviewed. Thirteen patients were treated with infliximab for refractory ulcerative proctitis in six referral centres between 2005 and 2009. Results, Following infliximab therapy induction, 9/13 patients (69%) had a complete response (defined as absence of diarrhoea and blood), 2/13 (15%) had a partial response and 2/13 (15%) were primary nonresponders. The median follow-up was 17 months (range, 3,48). Among the 11 patients with clinical response after infliximab induction therapy, 9 (82%) patients maintained response at last follow-up. Disappearance of rectal disorders was observed in all nine patients who maintained clinical response at last follow-up. Following infliximab induction therapy, the mean CRP level fell from 12.8 mg/L to 4.7 mg/L. Endoscopic evaluation was performed before and after infliximab in seven patients, showing an improvement in mucosal lesions in four patients, persistent mild endoscopic activity in two patients and no improvement in one patient. One patient underwent proctocolectomy. Conclusion, Infliximab therapy seems to be effective in inducing and maintaining a clinical response in refractory ulcerative proctitis. [source] Comparison of sheep and red deer rumen fluids for assessing nutritive value of ruminant feedstuffsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2005Gonzalo Hervás Abstract Four forages (alfalfa hay, barley straw, maize silage and beet pulp), four cereal grains (barley, maize, sorghum and wheat) and four shrubs (Calluna vulgaris, Erica australis, Cytisus cantabricus and Genista occidentalis) were incubated using rumen fluids from sheep and red deer, to examine differences in in vitro fermentation rates and ruminal parameters. For the forages and cereal grains, results suggest few differences between species in parameters related to gas production, rates of fermentation, organic matter disappearance and extent of degradation. Deer showed slightly better results for shrubs than sheep did. Disappearance of neutral detergent fibre was generally greater when the rumen fluid was derived from red deer (P < 0.05). On the other hand, ammonia-N concentration and total volatile fatty acids (VFAs) were higher in sheep (P < 0.05). Molar proportions of the major VFAs showed significant differences (P < 0.05) associated with the species of the inoculum donor and suggest that fermentation pathways might have been more efficient in red deer. The estimated amount of methane was higher in sheep, regardless of the substrate incubated (P < 0.001). The results indicate that although the sheep could be valid as a model to assess the nutritive value of good quality feedstuffs for red deer, it would fail to offer reliable information on non-conventional, low-quality feeds such as shrubs. Copyright © 2005 Society of Chemical Industry [source] Palaeontologic and biogeochemical characterization of the Cyrtograptus lundgreni event in the black shales of eastern Mid-Sardinia, ItalyLETHAIA, Issue 2 2006Paola Pittau A succession of biotic and geochemical changes that occurred during the Cyrtograptus lundgreni Event (Late Wenlock) have been recorded from the ,pelagic' black-shales in the Goni section, eastern mid-Sardinia, Italy. The studied interval encompasses the Cyrtograptus rigidus to Pristiograptus dubius-Gothograptus nassa zones. The fossil association includes graptolites, chitinozoans and microplankton i.e. probable linings of agglutinated foraminifera and radiolaria capsular membranes. Analysis of the chitinozoan distribution revealed a succession of several chitinozoan associations with low species diversity and dominated by opportunistic species. Three chitinozoan faunal turnovers and three extinction events have been recorded. Two of them coincide with graptolite extinctions whereas one probably is of local significance. Disappearance of the chitinozoan and microplankton associations occurred during four consecutive graptolite zones. Geochemical data (trace elements analysis) showed significantly higher (up to c. 100%) values for Co and Cd in the sedimentary organic matter (SOM) than in the whole rock samples. Possible relationships between peaks of metal enrichment, the major faunal changes among chitinozoans, extinction events among chitinozoans and graptolites and, to a certain extent, oceanic events may be inferred. The first extinction datum is older that those occurring in Gotland, Sweden and Thüringen, Germany and is so far considered to be of local significance. The second extinction datum of Sardinia can be matched with Datum 1 of Gotland and Thüringen. A close correlation between the third extinction datum of Sardinia and Datum 2 of Thüringen and Gotland reinforces the importance of these events at global scale. [source] The latest Ordovician Hirnantia Fauna (Brachiopoda) in time and spaceLETHAIA, Issue 3 2002RONG JIA-YU The diachronous temporal and spatial distribution of the Hirnantia brachiopod fauna and the complicated pattern of terminal Ordovician events are documented through biostratigraphical analysis of the Ordovician-Silurian boundary strata in S China, Sibumasu, Xizang and elsewhere. The duration of these events (longer than the half Myr derived from isotopic excursions) indicates that they were not abrupt and instantaneous. The presence of some core taxa of the Hirnantia fauna in the upper P. pacificus Biozone (known from their earliest occurrence in China) signals the start of increased water ventilation due to the invasion of cool water across the Yangtze Basin. Low- and higher-diversity Hirnantia faunas related to onshore, shallow-water and to offshore, deeper-water environments, respectively, developed first in the basal and upper N. extraordinarius-N. ojsuensis Biozone. Disappearance of most of the fauna in the early N. persculptus Biozone suggests that the glacial maximum started to decline. The presence of the Hirnantia fauna in the upper N. persculptus to the lower P. acuminatus biozones indicates the continuation of cool water environments in some places. The diachronous disappearance of deteriorating environments (earlier in later Hirnantian and finally in the early Rhuddanian) is associated with geographical heterogeneity. Occurrences of atrypids, pentamerids and spiriferids along with key elements of the Hirnantia fauna in N Guizhou provide a link between the Late Ordovician radiation and Early Silurian recovery of these major brachiopod groups. [source] Fluctuaciones Temporales en la Composición Floristica del Bosque Tropical Atlántico,BIOTROPICA, Issue 1 2001Samir Gonçalves Rolim ABSTRACT Temporal and spatial changes in floristic composition over a 15-year period in an Atlantic tropical forest in Brazil were analyzed. The data were recorded in five 0.5-ha (50 × 100 m) plots within a 22,000-ha forest reserve. In each plot, all stems ± 10 cm diameter at breast height (DBH) were repeatedly inventoried. The overall number of species among all plots was steady over time but changed within a given plot. In all plots, the proportion for the disappearance of species was 7 percent and that for immigration of new species into the plots was 9.5 percent. Approximately 65 percent of the disappearance occurred between 1986 and 1989, and 74 percent of the immigration happened after 1986. The observed changes in composition evidently were due to natural disturbance and climatic events, such as an unusual four-month drought. Disappearance of species from the plots did not denote regional extinction of those species, because they persisted elsewhere in the forest reserve. The changes in species composition within the plots and persistence outside them, however, indicated that large areas are required for in situ conservation of tropical tree species. These areas must be large enough for population changes to occur without negative effects on genetic and demographic structures of tree species. RESUMES Foram analisadas as variações temporais e espaciais na composição florística de uma floresta tropical num período de 15 anos entre os anos de 1980 e 1995. Em 5 parcelas de 0.5 ha (50 × 100 m) amostraram-se todas as árvores com diàmetro a altura do peito (DAP) , 10 cm. Para a escala e período que este estudo abrangeu pode-se concluir que há uma estabilidade no número de espécies da comunidade ao longo do tempo e esta estabilidade foi significativamente afetada por um distúrbio natural (um período seco de 4 meses) ocorrido em 1987. Foi constatado que em 15 anos desapareceram 7 por ciento das espécies nas parcelas monitoradas, contra um total de 9.5 por ciento de novas espécies recrutadas. Aproximadamente 65 por ciento do desaparecimento de espécies ocorreu entre 1986 e 1989 e 74 por ciento das novas espécies foram recrutadas apos 1986. O desaparecimento não significa necessariatmente um fenômeno de extinção e foi demonstrado que as espécies continuam ocorrendo na comunidade. O desaparecimento de espécies dentro das parcelas e sua pcrsisténcia fora delas indica que são necessárias grandes áreas para conservação in situ de espécies arbóreas. Estas áreas devem ser capazes de absorver as flutuaçz,oes populacionais sem afetar a estrutura genética e demográfica das espécies. [source] From la guerra sucia to ,A Gentleman's Fight': War, Disappearance and Nation in the 1976,1983 Argentine DictatorshipBULLETIN OF LATIN AMERICAN RESEARCH, Issue 1 2008JAMES SCORER Analysing the last Argentine dictatorship in the light of contemporary re-examinations of war, this article argues that the 1976,1983 dictatorship can be understood as a shift in war(s), from la guerra sucia to the Falklands/Malvinas conflict, from a limitless and unsustainable internal war to a bracketed external war. That external war is shown to be an attempt to re-found a nation imploding through disappearance. Drawing on the history of disappearance in Argentina reveals that, despite obvious differences, there are many continuities between the dictatorship and other regimes, emphasising the dangers of a politics that encourages a nation ,re-malvinizada'. [source] Can sensitization to aeroallergens disappear over time in children with allergic disease?ACTA PAEDIATRICA, Issue 9 2010KD Jacobs Abstract Background:, Remittance of aeroallergen sensitization has been shown in population-based studies, but there is a common perception that sensitization to aeroallergens rarely if ever disappears in children with allergic disease. Methods:, We retrospectively reviewed all specific IgE tests carried out in children aged 0,18 years at our hospital laboratory over a 14-year period. Of 3115 children sensitized to one or more aeroallergens, 244 (7.8%) were retested after a mean (SD) period of 45 (28) months at their physician's discretion. Results:, Disappearance of sensitization to individual aeroallergens did occur, with remittance rates ranging from 3.1% for house dust mite to 17.5% for cat. However, complete remittance of aeroallergen sensitization was found in only one subject. In up to 35% of cases, remittance of sensitization was offset by the appearance of one or more new aeroallergen sensitizations. Remittance was only observed in children sensitized to multiple allergens (with a median of 3 aeroallergen sensitizations), and their median degree of sensitization was low (median 2.1 kU/L). Conclusion: Aeroallergen sensitization can disappear in children with allergic disease, but only in polysensitized individuals. Complete remittance of sensitization to aeroallergens is rare in symptomatic children. [source] Epidemiologic Analysis of Factors Associated with Local Disappearances of Native Ranid Frogs in ArizonaCONSERVATION BIOLOGY, Issue 2 2008CARMEL L. WITTE análisis de factores de riesgo; declinación de anfibios; declinación de ranas; epidemiología de vida silvestre; métodos de control de casos Abstract:,We examined factors that may independently or synergistically contribute to amphibian population declines. We used epidemiologic case,control methodology to sample and analyze a large database developed and maintained by the Arizona Game and Fish Department that describes historical and currently known ranid frog localities in Arizona, U.S.A. Sites with historical documentation of target ranid species (n= 324) were evaluated to identify locations where frogs had disappeared during the study period (case sites) and locations where frog populations persisted (control sites). Between 1986 and 2003, 117 (36%) of the 324 sites became case sites, of which 105 were used in the analyses. An equal number of control sites were sampled to control for the effects of time. Risk factors, or predictor variables, were defined from environmental data summarized during site surveys and geographic information system data layers. We evaluated risk factors with univariate and multifactorial logistic-regression analyses to derive odds ratios (OR). Odds for local population disappearance were significantly related to 4 factors in the multifactorial model. Disappearance of frog populations increased with increasing elevation (OR = 2.7 for every 500 m, p < 0.01). Sites where disappearances occurred were 4.3 times more likely to have other nearby sites that also experienced disappearances (OR = 4.3, p < 0.01), whereas the odds of disappearance were 6.7 times less (OR = 0.15, p < 0.01) when there was a source population nearby. Sites with disappearances were 2.6 times more likely to have introduced crayfish than were control sites (OR = 2.6, p= 0.04). The identification of factors associated with frog disappearances increases understanding of declines occurring in natural populations and aids in conservation efforts to reestablish and protect native ranids by identifying and prioritizing implicated threats. Resumen:,Examinamos los factores que pueden contribuir independiente o sinérgicamente a la declinación de poblaciones de anfibios. Utilizamos una metodología epidemiológica de control de casos para muestrear y analizar una base de datos desarrollada y mantenida por el Departamento de Caza y Pesca de Arizona que describe las localidades históricas y actuales de ranas en Arizona, E. U. A. Los sitios con documentación histórica de las especies de ránidos (n= 324) fueron evaluados para identificar localidades donde las ranas desaparecieron durante el período de estudio (sitios caso) y localidades donde las poblaciones de ranas persistieron (sitios control). Entre 1986 y 2003, 36% (117) de los 324 sitios se volvieron sitios caso, de los cuales 105 fueron utilizados en los análisis. El mismo número de sitios control fueron muestreados para controlar los efectos del tiempo. Los factores de riesgo, o variables predictivas, fueron definidos a partir de datos ambientales obtenidos de los muestreos en los sitios y de capas de datos de un sistema información geográfica. Evaluamos los factores de riesgo con análisis de regresión logística univariada y multivariada para derivar proporciones de probabilidades (PP). Las probabilidad para la desaparición de una población local estuvo relacionada significativamente con 4 factores en el modelo multifactorial. La desaparición de poblaciones de ranas incrementó con la elevación (PP = 2.7 por cada 500 m, p < 0.01). Los sitios donde ocurrieron las desapariciones fueron 4.3 veces más propensos a estar cerca de otros sitios donde ocurrieron desapariciones (PP = 4.3, p < 0.01), mientras que la probabilidad de desaparición fue 6.7 veces menos (PP = 0.15, p < 0.01) cuando había una población fuente cercana. Los sitios con desapariciones fueron 2.6 veces más propensos a tener langostinos introducidos que los sitios control (PP = 2.6, p= 0.04). La identificación de factores asociados con la desaparición de ranas incrementa el conocimiento de las declinaciones de poblaciones naturales y ayuda a los esfuerzos de conservación para el reestablecimiento y la protección de ránidos nativos mediante la identificación y priorización de las amenazas implicadas. [source] Evaluating wastewater-induced plant genotoxicity using randomly amplified polymorphic DNAENVIRONMENTAL TOXICOLOGY, Issue 1 2008K. M. Swaileh Abstract Wastewater often contains genotoxic substances that can resist different stages of the treatment process. In the present study, randomly amplified polymorphic DNA technology was applied to evaluate the genotoxic effects of wastewater (treated and raw) irrigation on oat plants (Avena sativa). RAPD profiles obtained showed that both treated and raw wastewater (RWW) were having genotoxic effects on oat plants. This was apparent by the appearance/disappearance of bands in the treatments compared with the control plants. From the 15 primers used, 186 bands were obtained with an average of 12.4 bands per primer. Irrigating plants with RWW caused 51 new bands to appear and 19 to disappear. Treated wastewater (TWW) caused only 16 new bands and the loss of 17 bands. This makes TWW less genotoxic than RWW. The Euclidean distances shown on the dendrogram, revealed the presence of two clusters according to dissimilarity values. One cluster contained the control plants and those irrigated with TWW, whereas the second contained the plants irrigated with RWW. Similarity indices calculated between the treatments and the control plants showed that the control and the plants irrigated with TWW had a similarity index of 0.87, the control and plants irrigated with RWW 0.73 and between the treatments 0.75. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Epidemiologic Analysis of Factors Associated with Local Disappearances of Native Ranid Frogs in ArizonaCONSERVATION BIOLOGY, Issue 2 2008CARMEL L. WITTE análisis de factores de riesgo; declinación de anfibios; declinación de ranas; epidemiología de vida silvestre; métodos de control de casos Abstract:,We examined factors that may independently or synergistically contribute to amphibian population declines. We used epidemiologic case,control methodology to sample and analyze a large database developed and maintained by the Arizona Game and Fish Department that describes historical and currently known ranid frog localities in Arizona, U.S.A. Sites with historical documentation of target ranid species (n= 324) were evaluated to identify locations where frogs had disappeared during the study period (case sites) and locations where frog populations persisted (control sites). Between 1986 and 2003, 117 (36%) of the 324 sites became case sites, of which 105 were used in the analyses. An equal number of control sites were sampled to control for the effects of time. Risk factors, or predictor variables, were defined from environmental data summarized during site surveys and geographic information system data layers. We evaluated risk factors with univariate and multifactorial logistic-regression analyses to derive odds ratios (OR). Odds for local population disappearance were significantly related to 4 factors in the multifactorial model. Disappearance of frog populations increased with increasing elevation (OR = 2.7 for every 500 m, p < 0.01). Sites where disappearances occurred were 4.3 times more likely to have other nearby sites that also experienced disappearances (OR = 4.3, p < 0.01), whereas the odds of disappearance were 6.7 times less (OR = 0.15, p < 0.01) when there was a source population nearby. Sites with disappearances were 2.6 times more likely to have introduced crayfish than were control sites (OR = 2.6, p= 0.04). The identification of factors associated with frog disappearances increases understanding of declines occurring in natural populations and aids in conservation efforts to reestablish and protect native ranids by identifying and prioritizing implicated threats. Resumen:,Examinamos los factores que pueden contribuir independiente o sinérgicamente a la declinación de poblaciones de anfibios. Utilizamos una metodología epidemiológica de control de casos para muestrear y analizar una base de datos desarrollada y mantenida por el Departamento de Caza y Pesca de Arizona que describe las localidades históricas y actuales de ranas en Arizona, E. U. A. Los sitios con documentación histórica de las especies de ránidos (n= 324) fueron evaluados para identificar localidades donde las ranas desaparecieron durante el período de estudio (sitios caso) y localidades donde las poblaciones de ranas persistieron (sitios control). Entre 1986 y 2003, 36% (117) de los 324 sitios se volvieron sitios caso, de los cuales 105 fueron utilizados en los análisis. El mismo número de sitios control fueron muestreados para controlar los efectos del tiempo. Los factores de riesgo, o variables predictivas, fueron definidos a partir de datos ambientales obtenidos de los muestreos en los sitios y de capas de datos de un sistema información geográfica. Evaluamos los factores de riesgo con análisis de regresión logística univariada y multivariada para derivar proporciones de probabilidades (PP). Las probabilidad para la desaparición de una población local estuvo relacionada significativamente con 4 factores en el modelo multifactorial. La desaparición de poblaciones de ranas incrementó con la elevación (PP = 2.7 por cada 500 m, p < 0.01). Los sitios donde ocurrieron las desapariciones fueron 4.3 veces más propensos a estar cerca de otros sitios donde ocurrieron desapariciones (PP = 4.3, p < 0.01), mientras que la probabilidad de desaparición fue 6.7 veces menos (PP = 0.15, p < 0.01) cuando había una población fuente cercana. Los sitios con desapariciones fueron 2.6 veces más propensos a tener langostinos introducidos que los sitios control (PP = 2.6, p= 0.04). La identificación de factores asociados con la desaparición de ranas incrementa el conocimiento de las declinaciones de poblaciones naturales y ayuda a los esfuerzos de conservación para el reestablecimiento y la protección de ránidos nativos mediante la identificación y priorización de las amenazas implicadas. [source] Effects of Habitat Fragmentation by Damming on the Persistence of Stream-Dwelling Charr PopulationsCONSERVATION BIOLOGY, Issue 5 2002Kentaro Morita We assessed the effect of habitat fragmentation by damming on the population persistence of a stream-dwelling fish, the white-spotted charr (Salvelinus leucomaenis), in streams of southwestern Hokkaido, Japan. We sampled for charr at 52 dammed-off sites by electrofishing or snorkeling and measured five habitat characteristics: isolation period, watershed area, gradient, elevation, distance from sea. Of the 52 study sites above dams, white-spotted charr were absent at 17 sites and were present at 35 sites. Because the charr occupied all undammed upstream reaches, the damming would cause the absence of charr upstream. Among five habitat characteristics examined, stepwise logistic-regression analysis showed that disappearance was promoted with increasing isolation period, with decreasing watershed area (i.e., habitat size), and with decreasing gradient. The resulting logistic model explained 82.7% of the present white-spotted charr occurrence and forecasted that 12 of 35 extant populations will disappear after 50 years. Our findings imply that extirpation of small, dammed-off populations is inevitable unless efficient fish ladders are installed or dams are removed. Resumen: La construcción de presas tiene serias consecuencias sobre los ecosistemas acuáticos y uno de los mas serios es el "efecto de barrera" ( la prevención de que un organismo migre a través del sistema). Evaluamos los efectos de la fragmentación del hábitat ocasionados por la construcción de presas en la persistencia de un pez morador de arroyos, la trucha de montaña de manchas blancas ( Salvelinus leucomaenis), en arroyos del suroeste de Hokkaido, Japón. Muestreamos en 52 sitios con represas empleando electropesca o buceo con esnórquel y medimos cinco características del hábitat ( periodo de aislamiento, área de la cuenca, gradiente, elevación y distancia al mar). De los 52 sitios de estudio ubicados arriba de las represas las truchas de montaña estuvieron ausentes en 17 sitios y presentes en 35 sitios. Debido a que las truchas de montaña ocupaban todos los rangos sin represas arroyo arriba, la creación de represas pudo causar la ausencia de truchas de montaña arroyo arriba. Dentro de las cinco características del hábitat examinadas, el análisis de regresión logística mostró que la desaparición era promovida por un incremento en el periodo de aislamiento, con una disminución en el área de la cuenca (i.e. tamaño del hábitat) y con una disminución del gradiente. El modelo logístico resultante explicó 82.7% de la presencia de truchas de montaña y pronosticó que 12 de la 35 poblaciones actuales desaparecerían después de 50 años. Nuestros resultados implican que la extirpación es pequeña y que la exclusión por construcción de represas es inevitable a menos que se instalen desvíos para peces o que se remuevan las presas. [source] Acute exercise reverses TRB3 expression in the skeletal muscle and ameliorates whole body insulin sensitivity in diabetic miceACTA PHYSIOLOGICA, Issue 1 2010A. Matos Abstract Aim:, TRB3 became of major interest in diabetes research when it was shown to interact with and inhibit the activity of Akt. Conversely, physical exercise has been linked to improved glucose homeostasis. Thus, the current study was designed to investigate the effects of acute exercise on TRB3 expression and whole body insulin sensitivity in obese diabetic mice. Methods:, Male leptin-deficient (ob/ob) mice swam for two 3-h-long bouts, separated by a 45-min rest period. After the second bout of exercise, food was withdrawn 6 h before antibody analysis. Eight hours after the exercise protocol, the mice were submitted to an insulin tolerance test (ITT). Gastrocnemius muscle samples were evaluated for insulin receptor (IR) and IRS-1 tyrosine phosphorylation, Akt serine phosphorylation, TRB3/Akt association and membrane GLUT4 expression. Results:, Western blot analysis showed that TRB3 expression was reduced in the gastrocnemius of leptin-deficient (ob/ob) mice submitted to exercise when compared with respective ob/ob mice at rest. In parallel, there was an increase in the insulin-signalling pathway in skeletal muscle from leptin-deficient mice after exercise. Furthermore, the GLUT4 membrane expression was increased in the muscle after the exercise protocol. Finally, a single session of exercise improved the glucose disappearance (KITT) rate in ob/ob mice. Conclusion:, Our results demonstrate that acute exercise reverses TRB3 expression and insulin signalling restoration in muscle. Thus, these results provide new insights into the mechanism by which physical activity ameliorates whole body insulin sensitivity in type 2 diabetes. [source] Rearrangement of microtubule polarity orientation during conversion of dendrites to axons in cultured pyramidal neuronsCYTOSKELETON, Issue 5 2007Daisuke Takahashi Abstract Axons and dendrites of neurons differ in the polarity orientation of their microtubules. Whereas the polarity orientation of microtubules in axons is uniform, with all plus ends distal, that in dendrites is nonuniform. The mechanisms responsible for establishment and maintenance of microtubule polarity orientation in neuronal processes remain unclear, however. We previously described a culture system in which dendrites of rat cortical neurons convert to axons. In the present study, we examined changes in microtubule polarity orientation in such dendrites. With the use of the hooking procedure and electron microscopy, we found that microtubule polarity orientation changed from nonuniform to uniform, with a plus end-distal arrangement, in dendrites that gave rise to axons during culture of neurons for 24 h. Microtubule polarity orientation remained nonuniform in dendrites that did not elongate. Axon regeneration at the dendritic tip thus triggered the disappearance of minus end-distal microtubules from dendrites. These minus end-distal microtubules also disappeared from dendrites during axon regeneration in the presence of inhibitors of actin polymerization, suggesting that actin-dependent transport of microtubules is not required for this process and implicating a previously unidentified mechanism in the establishment and maintenance of microtubule polarity orientation in neuronal processes. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Ca2+ -dependent in vitro contractility of a precipitate isolated from an extract of the heliozoon Actinophrys solCYTOSKELETON, Issue 2 2006Mikihiko Arikawa Abstract Contraction of axopodia in actinophrid heliozoons (protozoa) is induced by a unique contractile structure, the "contractile tubules structure (CTS)". We have previously shown that a cell homogenate of the heliozoon Actinophrys sol yields a precipitate on addition of Ca2+ that is mainly composed of filamentous structures morphologically identical to the CTS. In this study, to further characterize the nature of the CTS in vitro, biochemical and physiological properties of the precipitate were examined. SDS-PAGE analysis showed that the Ca2+ -induced precipitate was composed of many proteins, and that no proteins in the precipitate showed any detectable changes in electrophoretic mobility on addition of Ca2+. Addition of extraneous proteins such as bovine serum albumin to the cell homogenate resulted in cosedimentation of the proteins with the Ca2+ -induced precipitate, suggesting that the CTS has a high affinity for other proteins that are not related to precipitate formation. Appearance and disappearance of the precipitate were repeatedly induced by alternating addition of Ca2+ and EGTA, and its protein composition remained unchanged even after repeated cycles. When adhered to a glass surface, the precipitate showed Ca2+ -dependent contractility with a threshold of 10,100 nM, and this contractility was not inhibited by colchicine or cytochalasin B. The precipitate repeatedly contracted and relaxed with successive addition and removal of Ca2+, indicating that the contraction was controlled by Ca2+ alone with no need for any other energy supply. From our characterization of the precipitate, we concluded that its Ca2+ -dependent formation and contraction are associated with the unique contractile organelle, the "contractile tubules structure". Cell Motil. Cytoskeleton 2006. © 2005 Wiley-Liss, Inc. [source] How does premenstrual dysphoric disorder relate to depression and anxiety disorders?DEPRESSION AND ANXIETY, Issue 3 2003Mikael Landén M.D., Ph.D. Abstract Premenstrual dysphoric disorder (PMDD) is a severe variant of premenstrual syndrome that afflicts approximately 5% of all women of fertile age. The hallmark of this condition is the surfacing of symptoms during the luteal phase of the menstrual cycle, and the disappearance of symptoms shortly after the onset of menstruation. Whereas many researchers have emphasized the similarities between PMDD and anxiety disorders, and in particular panic disorder, others have suggested that PMDD should be regarded as a variant of depression. Supporting both these notions, the treatment of choice for PMDD, the serotonin reuptake inhibitors (SRIs), is also first line of treatment for depression and for most anxiety disorders. In this review, the relationship between PMDD on the one hand, and anxiety and depression on the other, is being discussed. Our conclusion is that PMDD is neither a variant of depression nor an anxiety disorder, but a distinct diagnostic entity, with irritability and affect lability rather than depressed mood or anxiety as most characteristic features. The clinical profile of SRIs when used for PMDD, including a short onset of action, suggests that this effect is mediated by other serotonergic synapses than the antidepressant and anti-anxiety effects of these drugs. Although we hence suggest that PMDD should be regarded as a distinct entity, it should be emphasized that this disorder does display intriguing similarities with other conditions, and in particular with panic disorder, which should be the subject of further studies. Also, the possibility that there are subtypes of PMDD more closely related to depression, or anxiety disorders, than the most common form of the syndrome, should not be excluded. Depression and Anxiety 17:122,129, 2003. © 2003 Wiley-Liss, Inc. [source] Development and fine structure of the yolk nucleus of previtellogenic oocytes in the medaka Oryzias latipesDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 6 2000Hirokuni Kobayashi The development and fine structure of yolk nuclei in the cytoplasm of previtellogenic oocytes were examined by electron microscopy during several stages of oogenesis in the medaka, Oryzias latipes. Shortly after oogenesis starts, oocytes 20,30 ,m in diameter have much electron-dense (basophilic) cytoplasm, within which a continuous or discontinuous, irregular ring-shaped lower electron-dense area of flocculent appearance (LF) begins to emerge around the nucleus. The yolk nucleus is first recognized within an LF area as a few fragments of dense granular thread measuring 20,25 nm in width. The threads consist of two rows of very dense granules resembling ribosomes or ribonucleoprotein (RNP)-like particles in size and electron density. These thread-like fragments gradually increase in number and length until they assemble into a compact, spherical mass of complicated networks. Analysis of serial sections suggests that the yolk nucleus is a complicated mass of numerous, small deformed vacuoles composed of a single lamella with double layers of ribosomes or RNP-like granules, rather than a mass of granular threads. When oocytes develop to greater than 100 ,m in diameter, the yolk nucleus begins to fragment before dispersing throughout the surrounding cytoplasm, concomitantly with the disappearance of LF areas. At this stage of oogenesis, a restricted region of the granulosa cell layer adjacent to the yolk nucleus becomes somewhat columnar in morphology, fixing the vegetal pole region of the oocyte. [source] Inhibition of SMAD2 expression prevents murine palatal fusionDEVELOPMENTAL DYNAMICS, Issue 7 2006Nobuyuki Shiomi Abstract Transforming growth factor (TGF)-beta 3 is known to regulate the disappearance of murine medial edge epithelium (MEE) during palatal fusion. Our previous studies showed that SMAD2, a TGF-beta signaling mediator, was expressed and phosphorylated primarily in the MEE and that SMAD2 phosphorylation in the MEE was temporospatially regulated by TGF-beta 3. The goal of this study was to examine the requirement for SMAD2 to complete the developmental events necessary for palatal fusion. SMAD2 expression was inhibited with Smad2 siRNA transfection into palatal tissues in vitro. The results showed that Smad2 siRNA transfection resulted in the maintenance of MEE cells in the palatal midline. Western blot and immunofluorescence analyses confirmed that the endogenous SMAD2 and phospho-SMAD2 levels were reduced following siRNA transfection. The SMAD3 level was not altered by the Smad2 siRNA transfection. The persistence of the MEE and the decreased SMAD2/phospho-SMAD2 levels were coincident with increased MEE cell proliferation. Addition of exogenous TGF-beta 3 increased p-SMAD2 level but not the total SMAD2 level. Therefore, exogenous TGF-beta 3 was not able to induce p-SMAD2 enough to rescue the palatal phenotype in the Smad2 siRNA group. The results indicated that the endogenous SMAD2 level is crucial in the regulation of disappearance of MEE during palatal fusion. Developmental Dynamics 235:1785,1793, 2006. © 2006 Wiley-Liss, Inc. [source] TGF-,3,dependent SMAD2 phosphorylation and inhibition of MEE proliferation during palatal fusionDEVELOPMENTAL DYNAMICS, Issue 3 2003Xiao-Mei Cui Abstract Transforming growth factor (TGF) -,3 is known to selectively regulate the disappearance of murine medial edge epithelium (MEE) during palatal fusion. Previous studies suggested that the selective function of TGF-,3 in MEE was conducted by TGF-, receptors. Further studies were needed to demonstrate that the TGF-, signaling mediators were indeed expressed and phosphorylated in the MEE cells. SMAD2 and SMAD3 were both present in the MEE, whereas SMAD2 was the only one phosphorylated during palatal fusion. SMAD2 phosphorylation was temporospatially restricted to the MEE and correlated with the disappearance of the MEE. No phosphorylated SMAD2 was found in MEE in TGF-,3,/, mice, although nonphosphorylated SMAD2 was present. The results suggest that TGF-,3 is required for initiating and maintaining SMAD2 phosphorylation in MEE. Phospho-SMAD3 was not detectable in palate during normal palatal fusion. Previous results suggested TGF-,,induced cessation of DNA synthesis in MEE cells during palatal fusion in vitro. The present results provide evidence that inhibition of MEE proliferation in vivo was controlled by endogenous TGF-,3. The number of 5-bromo-2,-deoxyuridine (BrdU) -labeled MEE cells was significantly reduced in TGF-,3+/+ compared with TGF-,3,/, mice when the MEE seam formed (t -test, P < 0.05). This finding suggests that TGF-,3 is required for inhibiting MEE proliferation during palatal fusion. The inhibition of MEE proliferation may be mediated by TGF-,3,dependent phosphorylation of SMAD2. Developmental Dynamics 227:387,394, 2003. © 2003 Wiley-Liss, Inc. [source] Predictive tracking over occlusions by 4-month-old infantsDEVELOPMENTAL SCIENCE, Issue 5 2007Claes Von Hofsten Two experiments investigated how 16,20-week-old infants visually tracked an object that oscillated on a horizontal trajectory with a centrally placed occluder. To determine the principles underlying infants' tendency to shift gaze to the exiting side before the object arrives, occluder width, oscillation frequency, and motion amplitude were manipulated resulting in occlusion durations between 0.20 and 1.66 s. Through these manipulations, we were able to distinguish between several possible modes of behavior underlying ,predictive' actions at occluders. Four such modes were tested. First, if passage-of-time determines when saccades are made, the tendency to shift gaze over the occluder is expected to be a function of time since disappearance. Second, if visual salience of the exiting occluder edge determines when saccades are made, occluder width would determine the pre-reappearance gaze shifts but not oscillation frequency, amplitude, or velocity. Third, if memory of the duration of the previous occlusion determines when the subjects shift gaze over the occluder, it is expected that the gaze will shift after the same latency at the next occlusion irrespective of whether occlusion duration is changed or not. Finally, if infants base their pre-reapperance gaze shifts on their ability to represent object motion (cognitive mode), it is expected that the latency of the gaze shifts over the occluder is scaled to occlusion duration. Eye and head movements as well as object motion were measured at 240 Hz. In 49% of the passages, the infants shifted gaze to the opposite side of the occluder before the object arrived there. The tendency to make such gaze shifts could not be explained by the passage of time since disappearance. Neither could it be fully explained in terms of visual information present during occlusion, i.e. occluder width. On the contrary, it was found that the latency of the pre-reappearance gaze shifts was determined by the time of object reappearance and that it was a function of all three factors manipulated. The results suggest that object velocity is represented during occlusion and that infants track the object behind the occluder in their ,mind's eye'. [source] Cognitive behaviour therapy with coping training for persistent auditory hallucinations in schizophrenia: a naturalistic follow-up study of the durability of effectsACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2001D. Wiersma Objective: To investigate the durability of positive effects of cognitive behaviour therapy (CBT) with coping training on psychotic symptoms and social functioning. Method: Forty patients with schizophrenia or related psychotic disorders and refractory auditory hallucinations were given CBT and coping training in an integrated single family treatment programme. In a naturalistic study patients were followed after 2 and 4 years since the start of treatment. Results: The treatment improved overall burden of ,hearing voices', with a generalization into daily functioning. Improvement with regard to fear, loss of control, disturbance of thought and interference with thinking was sustained by 60% of the patients while one-third improved further. Complete disappearance of hallucinations occurred in 18% of the patients. Conclusion: CBT with coping training can improve both overall symptomatology and quality of life, even over longer periods of time, but a status of persistent disablement indicates a continuing need for mental health care. [source] Diaconiae, xenodochia, hospitalia and monasteries: ,social security' and the meaning of monasticism in early medieval RomeEARLY MEDIEVAL EUROPE, Issue 4 2008Hendrik W. Dey The first section of this article examines the various types of charitable institutions operative in Rome between the seventh and the ninth centuries, in the light of what available textual and comparative evidence reveals about their respective functions. It is then suggested that these centres of assistance were staffed by resident monastic communities, an arrangement which accounts well for their many apparent similarities; which may help to explain the disappearance of the most commonly attested types (xenodochia and diaconiae) over the course of the ninth century; and which opens a window onto an alternative conception of monastic practice hitherto under-represented in the scholarly tradition. [source] Extinction debt on oceanic islandsECOGRAPHY, Issue 2 2010Kostas A. Triantis Habitat destruction is the leading cause of species extinctions. However, there is typically a time-lag between the reduction in habitat area and the eventual disappearance of the remnant populations. These "surviving but ultimately doomed" species represent an extinction debt. Calculating the magnitude of such future extinction events has been hampered by potentially inaccurate assumptions about the slope of species,area relationships, which are habitat- and taxon-specific. We overcome this challenge by applying a method that uses the historical sequence of deforestation in the Azorean Islands, to calculate realistic and ecologically-adjusted species,area relationships. The results reveal dramatic and hitherto unrecognized levels of extinction debt, as a result of the extensive destruction of the native forest:>95%, in<600,yr. Our estimations suggest that more than half of the extant forest arthropod species, which have evolved in and are dependent on the native forest, might eventually be driven to extinction. Data on species abundances from Graciosa Island, where only a very small patch of secondary native vegetation still exists, as well as the number of species that have not been found in the last 45,yr, despite the extensive sampling effort, offer support to the predictions made. We argue that immediate action to restore and expand native forest habitat is required to avert the loss of numerous endemic species in the near future. [source] | ||||||||||||||||||||||||||||||||||||||||||||||