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排序方式: 共有137条查询结果,搜索用时 15 毫秒
51.
Cryptic species continue to be uncovered in many fish taxa, posing challenges for fisheries conservation and management. In Sardinella gibbosa, previous investigations revealed subtle intra-species variations, resulting in numerous synonyms and a controversial taxonomy for this sardine. Here, we tested for cryptic diversity within S. gibbosa using genetic data from two mitochondrial and one nuclear gene regions of 248 individuals of S. gibbosa, collected from eight locations across the Philippine archipelago. Deep genetic divergence and subsequent clustering was consistent across both mitochondrial and nuclear markers. Clade distribution is geographically limited: Clade 1 is widely distributed in the central Philippines, while Clade 2 is limited to the northernmost sampling site. In addition, morphometric analyses revealed a unique head shape that characterized each genetic clade. Hence, both genetic and morphological evidence strongly suggests a hidden diversity within this common and commercially-important sardine. 相似文献
52.
ADAM10 activation is required for green tea (-)-epigallocatechin-3-gallate-induced alpha-secretase cleavage of amyloid precursor protein 总被引:4,自引:0,他引:4
Obregon DF Rezai-Zadeh K Bai Y Sun N Hou H Ehrhart J Zeng J Mori T Arendash GW Shytle D Town T Tan J 《The Journal of biological chemistry》2006,281(24):16419-16427
Recently, we have shown that green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) exerts a beneficial role on reducing brain Abeta levels, resulting in mitigation of cerebral amyloidosis in a mouse model of Alzheimer disease. EGCG seems to accomplish this by modulating amyloid precursor protein (APP) processing, resulting in enhanced cleavage of the alpha-COOH-terminal fragment (alpha-CTF) of APP and corresponding elevation of the NH(2)-terminal APP product, soluble APP-alpha (sAPP-alpha). These beneficial effects were associated with increased alpha-secretase cleavage activity, but no significant alteration in beta-or gamma-secretase activities. To gain insight into the molecular mechanism whereby EGCG modulates APP processing, we evaluated the involvement of three candidate alpha-secretase enzymes, a-disintegrin and metalloprotease (ADAM) 9, 10, or 17, in EGCG-induced non-amyloidogenic APP metabolism. Results show that EGCG treatment of N2a cells stably transfected with "Swedish" mutant human APP (SweAPP N2a cells) leads to markedly elevated active ( approximately 60 kDa mature form) ADAM10 protein. Elevation of active ADAM10 correlates with increased alpha-CTF cleavage, and elevated sAPP-alpha. To specifically test the contribution of ADAM10 to non-amyloidogenic APP metabolism, small interfering RNA knockdown of ADAM9, -10, or -17 mRNA was employed. Results show that ADAM10 (but not ADAM9 or -17) is critical for EGCG-mediated alpha-secretase cleavage activity. In summary, ADAM10 activation is necessary for EGCG promotion of non-amyloidogenic (alpha-secretase cleavage) APP processing. Thus, ADAM10 represents an important pharmacotherapeutic target for the treatment of cerebral amyloidosis in Alzheimer disease. 相似文献
53.
Cindy Gonzalez Bautisse Postaire Rodrigo R. Domingues Kevin A. Feldheim Susana Caballero Demian Chapman 《Journal of fish biology》2021,99(6):1899-1911
Resolving the identity, phylogeny and distribution of cryptic species within species complexes is an essential precursor to management. The bonnethead shark, Sphyrna tiburo, is a small coastal shark distributed in the Western Atlantic from North Carolina (U.S.A.) to southern Brazil. Genetic analyses based on mitochondrial markers revealed that bonnethead sharks comprise a species complex with at least two lineages in the Northwestern Atlantic and the Caribbean (S. tiburo and Sphyrna aff. tiburo, respectively). The phylogeographic and phylogenetic analysis of two mitochondrial markers [control region (mtCR) and cytochrome oxidase I (COI)] showed that bonnethead sharks from southeastern Brazil correspond to S. aff. tiburo, extending the distribution of this cryptic species >5000 km. Bonnethead shark populations are only managed in the U.S.A. and in the 2000s were considered to be regionally extinct or collapsed in southeast Brazil. The results indicate that there is significant genetic differentiation between S. aff. tiburo from Brazil and other populations from the Caribbean (ΦST = 0.9053, P < 0.000), which means that collapsed populations in the former are unlikely to be replenished from Caribbean immigration. The species identity of bonnethead sharks in the Southwest Atlantic and their relationship to North Atlantic and Caribbean populations still remains unresolved. Taxonomic revision and further sampling are required to reevaluate the status of the bonnethead shark complex through its distribution range. 相似文献
54.
Shannon J. O'Leary Lyndie A. Hice Kevin A. Feldheim Michael G. Frisk Anne E. McElroy Mark D. Fast Demian D. Chapman 《PloS one》2013,8(6)
In contrast to freshwater fish it is presumed that marine fish are unlikely to spawn with close relatives due to the dilution effect of large breeding populations and their propensity for movement and reproductive mixing. Inbreeding is therefore not typically a focal concern of marine fish management. We measured the effective number of breeders in 6 New York estuaries for winter flounder (Pseudopleuronectes americanus), a formerly abundant fish, using 11 microsatellite markers (6–56 alleles per locus). The effective number of breeders for 1–2 years was remarkably small, with point estimates ranging from 65–289 individuals. Excess homozygosity was detected at 10 loci in all bays (FIS = 0.169–0.283) and individuals exhibited high average internal relatedness (IR; mean = 0.226). These both indicate that inbreeding is very common in all bays, after testing for and ruling out alternative explanations such as technical and sampling artifacts. This study demonstrates that even historically common marine fish can be prone to inbreeding, a factor that should be considered in fisheries management and conservation plans. 相似文献
55.
56.
Salemi J Obregon DF Cobb A Reed S Sadic E Jin J Fernandez F Tan J Giunta B 《Molecular neurodegeneration》2011,6(1):3-8
Microglial dysfunction is associated with the pathogenesis and progression of a number of neurodegenerative disorders including HIV associated dementia (HAD). HIV promotion of an M1 antigen presenting cell (APC) - like microglial phenotype, through the promotion of CD40 activity, may impair endogenous mechanisms important for amyloid- beta (Aβ) protein clearance. Further, a chronic pro-inflammatory cycle is established in this manner. CD45 is a protein tyrosine phosphatase receptor which negatively regulates CD40L-CD40-induced microglial M1 activation; an effect leading to the promotion of an M2 phenotype better suited to phagocytose and clear Aβ. Moreover, this CD45 mediated activation state appears to dampen harmful cytokine production. As such, this property of microglial CD45 as a regulatory "off switch" for a CD40-promoted M1, APC-type microglia activation phenotype may represent a critical therapeutic target for the prevention and treatment of neurodegeneration, as well as microglial dysfunction, found in patients with HAD. 相似文献
57.
58.
Deng J Hou H Giunta B Mori T Wang YJ Fernandez F Weggen S Araki W Obregon D Tan J 《Journal of neurochemistry》2012,120(5):732-740
Several prior investigations of Alzheimer's disease (AD) patients have indicated naturally occurring autoantibodies against amyloid-β (Aβ) species are produced. Although many studies have focused on the relative concentrations or binding affinities of autoantibodies against Aβ-related proteins in AD and aging, data regarding their functional properties are limited. It is generally believed that these antibodies act to aid in clearance of Aβ. However, as antibodies which bind to Aβ also typically bind to the parent amyloid precursor protein (APP), we reasoned that certain Aβ-targeting autoantibodies may bind to APP thereby altering its conformation and processing. Here we show for the first time, that naturally occurring Aβ-reactive autoantibodies isolated from AD patients, but not from healthy controls, promote β-secretase activity in cultured cells. Furthermore, using monoclonal antibodies to various regions of Aβ, we found that antibodies generated against the N-terminal region, especially Aβ(1-17) , dose dependently promoted amyloidogenic processing of APP viaβ-secretase activation. Thus, this property of certain autoantibodies in driving Aβ generation could be of etiological importance in the development of sporadic forms of AD. Furthermore, future passive or active anti-Aβ immunotherapies must consider potential off-target effects resulting from antibodies targeting the N-terminus of Aβ, as co-binding to the corresponding region of APP may actually enhance Aβ generation. 相似文献
59.
Listeria monocytogenes cytosolic metabolism promotes replication,survival, and evasion of innate immunity 总被引:1,自引:0,他引:1
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Listeria monocytogenes, the causative agent of listeriosis, is an intracellular pathogen that is exquisitely evolved to survive and replicate in the cytosol of eukaryotic cells. Eukaryotic cells typically restrict bacteria from colonising the cytosol, likely through a combination of cell autonomous defences, nutritional immunity, and innate immune responses including induction of programmed cell death. This suggests that L. monocytogenes and other professional cytosolic pathogens possess unique metabolic adaptations, not only to support replication but also to facilitate resistance to host‐derived stresses/defences and avoidance of innate immune activation. In this review, we outline our current understanding of L. monocytogenes metabolism in the host cytosol and highlight major metabolic processes which promote intracellular replication and survival. 相似文献
60.
Desorption electrospray ionization (DESI) allows the direct analysis of ordinary objects or pre-processed samples under ambient conditions. Among other applications, DESI is used to identify and record spatial distributions of lipids and drug molecules in biological tissue sections. This technique does not require sample preparation other than production of microtome tissue slices and does not involve the use of ionization matrices. This greatly simplifies the procedure and prevents the redistribution of analytes during matrix deposition. Images are obtained by continuously moving the sample relative to the DESI sprayer and the inlet of the mass spectrometer. The timing of the protocol depends on the size of the surface to be analyzed and on the desired resolution. Analysis of organ tissue slices at 250 microm resolution typically takes between 30 min and 2 h. 相似文献