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821.
Daniel?J. McGrail Kathleen?M. McAndrews Chandler?P. Brandenburg Nithin Ravikumar Quang?Minh?N. Kieu Michelle?R. Dawson 《Biophysical journal》2015,109(7):1334-1337
For a solid tumor to grow, it must be able to support the compressive stress that is generated as it presses against the surrounding tissue. Although the literature suggests a role for the cytoskeleton in counteracting these stresses, there has been no systematic evaluation of which filaments are responsible or to what degree. Here, using a three-dimensional spheroid model, we show that cytoskeletal filaments do not actively support compressive loads in breast, ovarian, and prostate cancer. However, modulation of tonicity can induce alterations in spheroid size. We find that under compression, tumor cells actively efflux sodium to decrease their intracellular tonicity, and that this is reversible by blockade of sodium channel NHE1. Moreover, although polymerized actin does not actively support the compressive load, it is required for sodium efflux. Compression-induced cell death is increased by both sodium blockade and actin depolymerization, whereas increased actin polymerization offers protective effects and increases sodium efflux. Taken together, these results demonstrate that cancer cells modulate their tonicity to survive under compressive solid stress. 相似文献
822.
Simon Cauchemez Peter Horby Annette Fox Le Quynh Mai Le Thi Thanh Pham Quang Thai Le Nguyen Minh Hoa Nguyen Tran Hien Neil M. Ferguson 《PLoS pathogens》2012,8(12)
Serological studies are the gold standard method to estimate influenza infection attack rates (ARs) in human populations. In a common protocol, blood samples are collected before and after the epidemic in a cohort of individuals; and a rise in haemagglutination-inhibition (HI) antibody titers during the epidemic is considered as a marker of infection. Because of inherent measurement errors, a 2-fold rise is usually considered as insufficient evidence for infection and seroconversion is therefore typically defined as a 4-fold rise or more. Here, we revisit this widely accepted 70-year old criterion. We develop a Markov chain Monte Carlo data augmentation model to quantify measurement errors and reconstruct the distribution of latent true serological status in a Vietnamese 3-year serological cohort, in which replicate measurements were available. We estimate that the 1-sided probability of a 2-fold error is 9.3% (95% Credible Interval, CI: 3.3%, 17.6%) when antibody titer is below 10 but is 20.2% (95% CI: 15.9%, 24.0%) otherwise. After correction for measurement errors, we find that the proportion of individuals with 2-fold rises in antibody titers was too large to be explained by measurement errors alone. Estimates of ARs vary greatly depending on whether those individuals are included in the definition of the infected population. A simulation study shows that our method is unbiased. The 4-fold rise case definition is relevant when aiming at a specific diagnostic for individual cases, but the justification is less obvious when the objective is to estimate ARs. In particular, it may lead to large underestimates of ARs. Determining which biological phenomenon contributes most to 2-fold rises in antibody titers is essential to assess bias with the traditional case definition and offer improved estimates of influenza ARs. 相似文献
823.
Taiana Rivière-Dobigny Lan Pham Doan Nam Le Quang Jean-Charles Maillard Johan Michaux 《Zoo biology》2009,28(2):127-136
Since the second Indochina war, habitat destruction and overhunting has resulted in fragmentation of the remaining populations of Bos javanicus and B. gaurus. Nowadays, both species are in serious danger, especially the gaur. In Vietnam, where these species have become almost impossible to capture in the wild, non-invasive investigations are the only feasible approach to obtain data on populations. However, non-invasive derived DNA, especially in tropical areas, is usually characterized by low concentrations, poor quality and/or contamination from alien DNA. To assist in tropical conservation management, baseline information is provided here on assessing the reliability of species identification, molecular sexing and microsatellite genotyping using fecal DNA from B. gaurus and B. javanicus. For species identification using bovine fecal samples, cytochrome b fragment between positions 867 and 1140 was found to contain species diagnostic sites, which distinguishes the four species encountered in the region: B. gaurus, B. indicus, B. javanicus and B. taurus. For sex determination, primers were initially tested on DNA obtained from blood. Then, these primers were successfully used on DNA derived from fecal material. Finally, we also evaluate the feasibility of non-invasive microsatellite genotyping on fecal samples collected in Vietnamese nature reserves. The results presented here improve on current molecular methods based on fecal material obtained from tropical areas. Zoo Biol 28:127–136, 2009. © 2008 Wiley-Liss, Inc. 相似文献
824.
G.L. Adessi C. Goutte-Coussieu Tran Quang Nhuan D. Eichenberger M.F. Jayle 《Steroids》1978,32(3):295-306
Different cellular fractions of guinea-pig placenta were incubated in the presence of (7n-3H) testosterone. Microsomal aromatization of 3H-testosterone into estrone and estradiol-17β was demonstrated in the presence of NADPH. The predominance of estrone after incubation with 17β-hydroxylated precursors, (7n-3H) testosterone and (6,7-3H) estradiol-17β, indicate that there is a microsomal 17β-hydroxysterold dehydrogenase activity. In this report, cytosolic sulfurylation of estrogens is demonstrated. This latter activity represents a quite original characteristic of the placental metabolism of estrogens in guinea-pigs. In contrast with the human placenta where there is considerable sulfatase activity, the guinea-pig placenta can sulfurylate estrogens. 相似文献
825.
D Le Quoc K Le Quoc Y Gaudemer 《Comptes rendus des séances de la Société de biologie et de ses filiales》1977,171(4):935-941
Evidence for energy dependent variations of mitochondrial SH groups accessibility or reactivity was obtained using alkylating agents. These variations are thought to be consecutive to conformational changes affecting some proteins among them the phosphate carrier and the adenylic nucleotide translocator. 相似文献
826.
Dan Vanderpool Bui Quang Minh Robert Lanfear Daniel Hughes Shwetha Murali R. Alan Harris Muthuswamy Raveendran Donna M. Muzny Mark S. Hibbins Robert J. Williamson Richard A. Gibbs Kim C. Worley Jeffrey Rogers Matthew W. Hahn 《PLoS biology》2020,18(12)
Our understanding of the evolutionary history of primates is undergoing continual revision due to ongoing genome sequencing efforts. Bolstered by growing fossil evidence, these data have led to increased acceptance of once controversial hypotheses regarding phylogenetic relationships, hybridization and introgression, and the biogeographical history of primate groups. Among these findings is a pattern of recent introgression between species within all major primate groups examined to date, though little is known about introgression deeper in time. To address this and other phylogenetic questions, here, we present new reference genome assemblies for 3 Old World monkey (OWM) species: Colobus angolensis ssp. palliatus (the black and white colobus), Macaca nemestrina (southern pig-tailed macaque), and Mandrillus leucophaeus (the drill). We combine these data with 23 additional primate genomes to estimate both the species tree and individual gene trees using thousands of loci. While our species tree is largely consistent with previous phylogenetic hypotheses, the gene trees reveal high levels of genealogical discordance associated with multiple primate radiations. We use strongly asymmetric patterns of gene tree discordance around specific branches to identify multiple instances of introgression between ancestral primate lineages. In addition, we exploit recent fossil evidence to perform fossil-calibrated molecular dating analyses across the tree. Taken together, our genome-wide data help to resolve multiple contentious sets of relationships among primates, while also providing insight into the biological processes and technical artifacts that led to the disagreements in the first place.Combining three newly sequenced primate genomes with other published genomes, this study adapts a little-known method for detecting ancient introgression to genome-scale data, revealing multiple previously unknown examples of hybridization between primate species. 相似文献
827.
Thi Thanh Thuy Hoang Loan Thi Cam Tu Nga Phi Le Quoc Phu Dao Phuong Hong Trinh 《Wetlands Ecology and Management》2012,20(5):399-408
Vietnamese coastal wetlands have traditionally been used for shrimp farming, but with the expansion of commercial shrimp farming and the associated clearance of mangroves, these valuable ecosystems have been rapidly degraded. The application of veterinary antibiotics in shrimp culture is one of the major threats to Vietnamese mangroves. These antibiotics are released into the environment through wastewater streams from shrimp ponds and cause environmental problems as well as the occurrence of antibiotic resistant bacteria. However, there is only a limited amount of information available on the occurrence and fate of antibiotics in Vietnamese mangroves. Ciprofloxacin and norfloxacin are two of most commonly fluoroquinolones used in shrimp culture. Laboratory experiments were therefore carried out using saline shrimp pond water to investigate the fate of both antibiotics in a coastal wetland ecosystem. Furthermore, two wetland plant species (Ceratophyllum demersum and Chrysopogon zizanioides), were used for studying phytoremediation of both antibiotics through a hydroponic experiment. Both ciprofloxacin and norfloxacin were photodegradable but at a slow rate, whereas the biodegradation seemed to be insignificant. If given at an initial concentration of 5 or 10?mg/L, a higher removal of antibiotics was achieved using C. demersum: 40?% for norfloxacin and 44?C39?% for ciprofloxacin, respectively. With C. zizanioides, ciprofloxacin and norfloxacin were reduced by 40?C38 and 36?C34?%, respectively. These results indicated that phytoremediation could be effective in the removal of both antibiotics. 相似文献
828.
829.
V. K. Nezdolii D. S. Pavlov Tran Thanh Lan Pham Hong Phuong Nguyen Quoc Khanh 《Journal of Ichthyology》2010,50(11):1002-1013
The first material is presented on downstream migration of fish juveniles in the Krasnaya River, one of the largest rivers
in South-East Asia. The spatial-temporal structure of distribution of downstream-migrating fish juveniles in the Krasnaya
River has traits usually characteristic of migration in rovers with turbid water. Concentration of fish was extremely variable
by the time of the day, river length, and depth. In length-wise distribution, there was a tendency to increasing concentration
of downstream migrants from the upper stretches to the downstream stretch. In the upper reaches, Perciformes prevailed, in
the middle part, Cypriniformes prevailed, and in the lower reaches of the river Clupeiformes prevailed. During 24 h, Clupeiformes
and Perciformes migrated more intensively at night and Cypriniformes migrated more in the daytime. By depth horizons, Clupeiformes
made downstream migration predominantly at the surface and Cypriniformes and Perciformes did at the bottom. These differences
may be caused by species differences in fish biology, local specific traits of stream hydraulics, anthropogenous factors,
etc. 相似文献
830.
Notes on some rust fungi in Vietnam 总被引:1,自引:0,他引:1
Sixteen rust species and two unconnected Peridermium collected in Vietnam are enumerated. For all the rust species except Hemileia vastarix, Olivea tectonae, and Puccinia thwaitesii, these are the first records of their occurrence in Vietnam. Some taxonomic and pathological considerations are noted for
two economically important pine stem rusts. 相似文献