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1.
2.
The Dicer1 allele is used to show that microRNAs (miRNAs) play important roles in astrocyte development and functions. While it is known that astrocytes that lack miRNAs are dysregulated, the in vivo phenotypes of these astrocytes are not well understood. In this study, we use Aldh1l1-EGFP transgene, a marker of astrocytes, to characterize mouse models with conditional Dicer1 ablation (via either human or mouse GFAP-Cre). This transgene revealed novel features of the defective astrocytes from the absence of miRNA. Although astrocyte miRNAs were depleted in both lines, we found histological and molecular differences in the Aldh1l1-EGFP cells between the two Cre lines. Aldh1l1-EGFP cells from hGFAP-Cre mutant lines displayed up-regulation of Aldh1l1-EGFP with increased proliferation and a genomic profile that acquired many features of wildtype primary astrocyte cultures. In the young mGFAP-Cre mutant lines we found that Aldh1l1-EGFP cells were disorganized and hyperproliferative in the developing cerebellum. Using the Aldh1l1-EGFP transgene, our work provides new insights into the roles of miRNAs in astrocyte development and the features of astrocytes in these two mouse models. 相似文献
3.
Jeniffer Concepción-Acevedo Howard N. Weiss Waqas Nasir Chaudhry Bruce R. Levin 《PloS one》2015,10(6)
The maximum exponential growth rate, the Malthusian parameter (MP), is commonly used as a measure of fitness in experimental studies of adaptive evolution and of the effects of antibiotic resistance and other genes on the fitness of planktonic microbes. Thanks to automated, multi-well optical density plate readers and computers, with little hands-on effort investigators can readily obtain hundreds of estimates of MPs in less than a day. Here we compare estimates of the relative fitness of antibiotic susceptible and resistant strains of E. coli, Pseudomonas aeruginosa and Staphylococcus aureus based on MP data obtained with automated multi-well plate readers with the results from pairwise competition experiments. This leads us to question the reliability of estimates of MP obtained with these high throughput devices and the utility of these estimates of the maximum growth rates to detect fitness differences. 相似文献
4.
Lauren Porter Jennifer Duke Meredith Hennon David Dekevich Erik Crankshaw Ghada Homsi Matthew Farrelly 《PloS one》2015,10(5)
Recent youth trends in the prevalence of e-cigarette and traditional cigarette use in Florida were examined in a cross-sectional, representative state sample from 2011 to 2014. Traditional cigarette use among youth declined during the study period. Experimentation with and past 30-day use of e-cigarettes among Florida youth tripled over 4 years. Past 30-day e-cigarette use exceeded traditional cigarette use in 2014; 10.8% of high school and 4.0% of middle school students reported recent e-cigarette use, compared with 8.7% of high school and 2.9% of middle school students for traditional cigarettes (P<0.001). By 2014, 20.5% of high school and 8.5% of middle school students reported ever use of e-cigarettes. Among ever e-cigarette users in 2014, 30.3% of high school and 42.2% of middle school students had never smoked traditional cigarettes. Given the concern that significant rates of e-cigarette use by U.S. adolescents may have a negative effect on public health, further review of e-cigarette advertising, marketing, sales, and use among U.S. youth is warranted. 相似文献
5.
Janne Alahuhta Sarian Kosten Munemitsu Akasaka Dominique Auderset Mattia M. Azzella Rossano Bolpagni Claudia P. Bove Patricia A. Chambers Eglantine Chappuis John Clayton Mary de Winton Frauke Ecke Esperança Gacia Gana Gecheva Patrick Grillas Jennifer Hauxwell Seppo Hellsten Jan Hjort Mark V. Hoyer Christiane Ilg Agnieszka Kolada Minna Kuoppala Torben Lauridsen En Hua Li Balázs A. Lukács Marit Mjelde Alison Mikulyuk Roger P. Mormul Jun Nishihiro Beat Oertli Laila Rhazi Mouhssine Rhazi Laura Sass Christine Schranz Martin Søndergaard Takashi Yamanouchi Qing Yu Haijun Wang Nigel Willby Xiao Ke Zhang Jani Heino 《Journal of Biogeography》2017,44(8):1758-1769
6.
Neil A. Littlefield Bruce S. Hass Lynda J. McGarrity Suzanne M. Morris 《Cell biology and toxicology》1991,7(3):203-214
The effects of magnesium (Mg) restriction on cell growth and the cell cycle were determined in transformed (TRL-8) and non-transformed (TRL-12-15) epithelial-like rat liver cells. Cells were cultured in RPMI 1640 medium in which the Mg concentration was reduced to 0.5, 0.1, and 0 × the concentration in the regular RPMI 1640 media (100mg/l). Cell growth in the transformed cells was not influenced by the Mg restriction as greatly as in the non-transformed cell line. Transit through the cell cycle also exhibited an independence of the Mg in the medium in the transformed cells. When transformed cells were grown for two generations in Mg-limited medium, the growth rate slowed to a rate similar to that demonstrated by the non-transformed cells. Analysis by flow cytometry showed that transit through the cell cycle was minimally slowed in Mg deficient transformed cells; however, transit through the G1 and S phases in the non-transformed cells was slowed. The TRL-8 cells in Mg-limited medium resulted in fewer nuclei in G1 with subsequent increases in the percentages of S-phase nuclei. The TRL 12-15 cells reacted oppositely with the number of G1 nuclei increased and the number of S-phase nuclei decreased. In respect to growth, these results show that epithelial cells respond in a similar manner to Mg-limitation as do fibroblast cells. The transformed cells exhibited a level of independence from Mg in respect to growth, reproduction, and cell-cycle kinetics. 相似文献
7.
A rearing system based on a diet gelled with Water-Lock G-400, a synthetic superabsorbent (poly(2-propenamide-co-2-propenoic acid, sodium salt)) (WL), was compared with the standard rearing system (liquid diet suspended in acetate fibers) for the mass production of screwworms, Cochliomyia hominivorax (Coquerel). The WL rearing system yielded 2% heavier pupae, 32% higher egg to pupa survival, and required 54% less diet and 88% less labor than the standard rearing system. Other advantages of the WL system include reduced susceptibility to suboptimal environmental conditions and labor practices and characteristics conducive to centralization and mechanization of rearing procedures. 相似文献
8.
Neurofilament Proteins Are Distributed in a Diminishing Proximodistal Gradient Along Rat Sciatic Nerve 总被引:3,自引:2,他引:1
Neurofilament (NF) proteins are distributed in a diminishing proximodistal gradient along rat sciatic nerve when compared with total noncollagen or other proteins in nerve. About a twofold decline of NF proteins can be detected by quantitating nerve proteins that have been separated by gel electrophoresis. A similar decrease of immunoreactivity to each NF subunit is seen in distal nerve segments when noncollagen nerve proteins are immunoblotted. Parallel decreases occur in all three NF proteins, thereby maintaining neurofilament subunit stoichiometry along the neuraxis. The same NF gradient can be detected when the NF contents in nerve branches to the gluteus and gastrocnemius muscles are compared with each other and with those in nerve segments taken from the same proximodistal levels of the parent sciatic nerve. The gradient of NF proteins increases during postnatal development and is readily detected by postnatal day 16. During the same period of development, the heavy NF subunit appears for the first time and is rapidly incorporated throughout the sciatic nerve. Hence, the NF gradient becomes manifest during the development and maturation of the adult form of the axonal cytoskeleton. The basis for the proximodistal gradient of NF proteins in peripheral nerve is presently unknown. The extent of the gradient cannot be accounted for on the basis of diminishing numbers of nerve fibers or increasing amounts of other nerve proteins, e.g., collagen, in distal nerve. An alternative interpretation is that the gradient reflects a low level of NF protein turnover during axonal transport. 相似文献
9.
New germline mutations in the human retinoblastoma gene are known to arise preferentially on paternally derived chromosomes,
but the magnitude of that bias has not been measured. We evaluated 49 cases with a new germline mutation and found that in
40 cases (82%) the mutation arose on the paternally derived allele. We also evaluated 48 cases likely to have a somatic initial
mutation; in this group the initial mutation arose on paternal or maternal chromosomes with approximately equal frequency.
There was no statistically significant difference in the average age of fathers of children with new paternal germline mutations
from the average age of fathers of children with new maternal germline mutations or somatic initial mutations. Combining the
data with that from previous reports from other groups, the proportion of new germline mutations arising on a paternally derived
allele is 85% (based on 72 cases; 95% confidence interval = 76–93%). This number can be useful in the genetic counseling of
some families with retinoblastoma.
Received: 18 December 1996 / Accepted: 30 April 1997 相似文献
10.