In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded. In this study, we examined the pejerrey population of Salada de Pedro Luro Lake (south-east of Buenos Aires Province, Argentina) to clarify its taxonomic identity. An integrative taxonomic analysis based on traditional meristic, landmark-based morphometrics and genetic techniques suggests that the Salada de Pedro Luro pejerrey population represents a novel case of physiological and morphological adaptation of a marine pejerrey species to a landlocked environment and emphasises the environmental plasticity of this group of fishes. 相似文献
The nucleus-encoded 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) regulates cyclophilin D (cypD) in the mitochondrial matrix. CypD regulates opening of mitochondrial permeability transition pores. Both mechanisms may be affected by amyloid β peptides accumulated in mitochondria in Alzheimer's disease (AD). In order to clarify changes occurring in brain mitochondria, we evaluated interactions of both mitochondrial proteins in vitro (by surface plasmon resonance biosensor) and detected levels of various complexes of 17β-HSD10 formed in vivo (by sandwich ELISA) in brain mitochondria isolated from the transgenic animal model of AD (homozygous McGill-R-Thy1-APP rats) and in cerebrospinal fluid samples of AD patients. By surface plasmon resonance biosensor, we observed the interaction of 17β-HSD10 and cypD in a direct real-time manner and determined, for the first time, the kinetic parameters of the interaction (ka 2.0?×?105 M1s?1, kd 5.8?×?104 s?1, and KD 3.5?×?10–10 M). In McGill-R-Thy1-APP rats compared to controls, levels of 17β-HSD10–cypD complexes were decreased and those of total amyloid β increased. Moreover, the levels of 17β-HSD10–cypD complexes were decreased in cerebrospinal fluid of individuals with AD (in mild cognitive impairment as well as dementia stages) or with Frontotemporal lobar degeneration (FTLD) compared to cognitively normal controls (the sensitivity of the complexes to AD dementia was 92.9%, that to FTLD 73.8%, the specificity to AD dementia equaled 91.7% in a comparison with the controls but only 26.2% with FTLD). Our results demonstrate the weakened ability of 17β-HSD10 to regulate cypD in the mitochondrial matrix probably via direct effects of amyloid β. Levels of 17β-HSD10–cypD complexes in cerebrospinal fluid seem to be the very sensitive indicator of mitochondrial dysfunction observed in neurodegeneration but unfortunately not specific to AD pathology. We do not recommend it as the new biomarker of AD.
When differentiated lineages come into contact, their fates depend on demographic and reproductive factors. These factors have been well-studied in taxa of the same ploidy, but less is known about sympatric lineages that differ in ploidy, particularly with respect to demographic factors. We assessed prezygotic, postzygotic, and total reproductive isolation in naturally pollinated arrays of diploid-tetraploid and tetraploid-hexaploid population mixes of Campanula rotundifolia by measuring pollinator transitions, seed yield, germination rate, and proportion of hybrid offspring. Four frequencies of each cytotype were tested, and pollinators consistently overvisited rare cytotypes. Seed yield and F1 hybrid production were greater in 4X-6X arrays than 2X-4X arrays, whereas germination rates were similar, creating two distinct patterns of reproductive isolation. In 2X-4X arrays, postzygotic isolation was near complete (3% hybrid offspring), and prezygotic isolation associated with pollinator preference is expected to facilitate the persistence of minority cytotypes. However, in 4X-6X arrays where postzygotic isolation permitted hybrid formation (44% hybrids), pollinator behavior drove patterns of reproductive isolation, with rare cytotypes being more isolated and greater gene flow expected from rare into common cytotypes. In polyploid complexes, both the specific cytotypes in contact and local cytotype frequency, likely reflecting spatial demography, will influence likelihood of gene exchange. 相似文献
The aim of this study was to contribute to a general understanding of the response of the Antarctic macrobenthos to environmental variability and climate-induced changes. The change in population size of selected macrobenthic organisms was investigated in the Larsen A area east of the Antarctic Peninsula in 2007 and 2011 using ROV-based imaging methods. The results were complemented by data from the Larsen B collected in 2007 to allow a conceptual reconstruction of the environment-driven changes before the period of investigation. Both Larsen areas are characterised by ice-shelf disintegration in 1995 and 2002, respectively, as well as high inter-annual variability in sea-ice cover and oceanographic conditions. In 2007 one ascidian species, Molgula pedunculata, was abundant north and south of the stripe of remaining ice shelf between Larsen A and B. Population densities decreased drastically in the Larsen A between 2007 and 2011, coincident with the decrease in Corella eumyota, another ascidian. Among the ophiuroids, the population of deposit feeders increased, while suspension feeders halved their abundance. Current measurements indicated a northward flow between the Larsen B and Larsen A, suggesting that a major physical forcing on benthic population development comes from the South. The results demonstrate that Antarctic macrobenthic populations can exhibit dramatic population dynamics. Analyses of sea-ice dynamics, salinity, temperature and surprisingly ice-shelf disintegration history, however, did not provide any clear evidence for environmental drivers underlying the apparent changes. 相似文献
Bax Inhibitor-1 (BI-1) is an evolutionarily conserved six-transmembrane domain endoplasmic reticulum (ER)-localized protein that protects against ER stress-induced apoptotic cell death. This function is closely connected to its ability to lower steady-state ER Ca2+ levels. Recently, we elucidated BI-1's Ca2+-channel pore in the C-terminal part of the protein and identified the critical amino acids of its pore. Based on these insights, a Ca2+-channel pore-dead mutant BI-1 (BI-1D213R) was developed. We determined whether BI-1 behaves as a bona fide H+/Ca2+ antiporter or as an ER Ca2+-leak channel by investigating the effect of pH on unidirectional Ca2+-efflux rates. At pH 6.8, wild-type BI-1 expression in BI-1−/− cells increased the ER Ca2+-leak rate, correlating with its localization in the ER compartment. In contrast, BI-1D231R expression in BI-1−/−, despite its ER localization, did not increase the ER Ca2+-leak rate. However, at pH < 6.8, the BI-1-mediated ER Ca2+ leak was blocked. Finally, a peptide representing the Ca2+-channel pore of BI-1 promoting Ca2+ flux from the ER was used. Lowering the pH from 6.8 to 6.0 completely abolished the ability of the BI-1 peptide to mediate Ca2+ flux from the ER. We propose that this pH dependence is due to two aspartic acid residues critical for the function of the Ca2+-channel pore and located in the ER membrane-dipping domain, which facilitates the protonation of these residues. 相似文献
O cervo-do-pantanal (Blastocerus dichotomus, Cervidae) é uma espécie sul americana ameaçada de extinção. Existe pouca informação sobre a biologia desta espécie, incluindo dieta e requerimentos de habitat. O objetivo deste estudo foi determinar as espécies de plantas forrageadas pelo cervo no Pantanal, Brazil, onde se localiza a maior parte de sua população. A dieta do cervo-do-pantanal foi estudada através de microhistologia de restos vegetais em amostras de fezes. Um total de 41 espécies foram identificadas como componentes da dieta, 32 delas sendo consumidas durante a estação de cheias e 31 na estação seca. A maioria das espécies de plantas detectadas na dieta do cervo-do-pantanal é composta de plantas aqu ticas e/ou que apresentam tolerância a inundaç[otilde]es sazonais ou solos encharcados. Blastocerus pode ser melhor definido como um estrategista "pastador-podador" porque grande parte de sua dieta é composta de brotos de várias espécies arbustivas e macrófitas de folha larga. The marsh deer (Blastocerus dichotomus, Cervidae) is a South American endangered species. There is little information on the biology of this species, including diet and habitat requirements. The objective of this study was to determine the plant species foraged by the marsh deer in the Pantanal wetland, Brazil, where most of its population is found. Marsh deer's diet was studied through microscopic analysis of fecal samples for remnants of plant species. A total of 41 species were identified as components of the diet, 32 of them found to be consumed during the flooding season and 31 in the dry season. Most plant species detected in the marsh deer's diet are aquatic and/or present tolerance to seasonal flooding and water-logged soils. Blastocerus could be best defined as a grazer-browser strategist because large part of its diet is composed of shoots of several species of shrub and broad-leaved aquatic macrophytes. 相似文献