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991.
Henry C. Orr Kyle H. Sibinovic Peter G. Probst H. Donald Hochstein Dewitt C. Littlejohn 《In vitro cellular & developmental biology. Plant》1975,11(4):230-233
Summary Bacteriological tests were made on 24 lots of unfiltered calf serum collected for subsequent use as a component of tissue
culture media. The examination included the isolation and identification of bacteria, assay of phages, and demonstration of
endotoxin material. Only Gram-positive bacteria were isolated and 96% of the sera were contaminated with bacteria. The prevalent
strains of bacteria found wereBacillus species and streptococci and 63% of the sera coagulatedLimulus amebocyte lysate. More than 90% of the lots contained phages demonstrable with the C-3000 strain ofEscherichia coli. Only one lot of the serum was found to be free from bacteria, phages, and endotoxin by the tests used. 相似文献
992.
993.
The prostaglandin synthesis inhibitors, indomethacin and eicosa-5,8,11, 14-tetraynoic acid (ETA), have been tested on the isolated lamb ductus arteriosus at low and high PO2 levels. Both compounds produced a gradual contraction of the hypoxic vessel, and at equal doses the effect of indomethacin was stronger. The maximal tension output of the hypoxic tissue under indomethacin was equal to that of the oxygen-contracted control. ETA- and indomethacin-treated preparations contracted further upon transfer from a low to a high oxygen environment, and the response under indomethacin exceeded significantly control values. Control preparations were relaxed markedly by PGE2 in low oxygen but showed little or no response in high oxygen. In contrast, preparations pretreated with the inhibitors retained their sensitivity to PGE2 during exposure to high oxygen. The data are consistent with the idea that E-type prostaglandins play a role in the regulation of the intrinsic tone of the ductus arteriosus during foetal life. It is also suggested that the sensitivity of ductal muscle to E-type prostaglandins is controlled by the rate of endogenous prostaglandin formation. 相似文献
994.
995.
996.
Zihua Wang Andrea B Moffitt Peter Andrews Michael Wigler Dan Levy 《Nucleic acids research》2022,50(20):e116
Tandem repeats of simple sequence motifs, also known as microsatellites, are abundant in the genome. Because their repeat structure makes replication error-prone, variant microsatellite lengths are often generated during germline and other somatic expansions. As such, microsatellite length variations can serve as markers for cancer. However, accurate error-free measurement of microsatellite lengths is difficult with current methods precisely because of this high error rate during amplification. We have solved this problem by using partial mutagenesis to disrupt enough of the repeat structure of initial templates so that their sequence lengths replicate faithfully. In this work, we use bisulfite mutagenesis to convert a C to a U, later read as T. Compared to untreated templates, we achieve three orders of magnitude reduction in the error rate per round of replication. By requiring agreement from two independent first copies of an initial template, we reach error rates below one in a million. We apply this method to a thousand microsatellite loci from the human genome, revealing microsatellite length distributions not observable without mutagenesis. 相似文献
997.
Peter C. Reifsnyder Kevin Flurkey Rosalinda Doty Nigel A. Calcutt Robert A. Koza David E. Harrison 《Aging cell》2022,21(9)
Rapamycin treatment has positive and negative effects on progression of type 2 diabetes (T2D) in a recombinant inbred polygenic mouse model, male NONcNZO10/LtJ (NcZ10). Here, we show that combination treatment with metformin ameliorates negative effects of rapamycin while maintaining its benefits. From 12 to 30 weeks of age, NcZ10 males were fed a control diet or diets supplemented with rapamycin, metformin, or a combination of both. Rapamycin alone reduced weight gain, adiposity, HOMA‐IR, and inflammation, and prevented hyperinsulinemia and pre‐steatotic hepatic lipidosis, but exacerbated hyperglycemia, hypertriglyceridemia, and pancreatic islet degranulation. Metformin alone reduced hyperinsulinemia and circulating c‐reactive protein, but exacerbated nephropathy. Combination treatment retained the benefits of both while preventing many of the deleterious effects. Importantly, the combination treatment reversed effects of rapamycin on markers of hepatic insulin resistance and normalized systemic insulin sensitivity in this inherently insulin‐resistant model. In adipose tissue, rapamycin attenuated the expression of genes associated with adipose tissue expansion (Mest, Gpam), inflammation (Itgam, Itgax, Hmox1, Lbp), and cell senescence (Serpine1). In liver, the addition of metformin counteracted rapamycin‐induced alterations of G6pc, Ppara, and Ldlr expressions that promote hyperglycemia and hypertriglyceridemia. Both rapamycin and metformin treatment reduced hepatic Fasn expression, potentially preventing lipidosis. These results delineate a state of “insulin signaling restriction” that withdraws endocrine support for further adipogenesis, progression of the metabolic syndrome, and the development of its comorbidities. Our results are relevant for the treatment of T2D, the optimization of current rapamycin‐based treatments for posttransplant rejection and various cancers, and for the development of treatments for healthy aging. 相似文献
998.
999.
For nearly 50 years, analyses of coral physiology have used small coral fragments (nubbins) to make inferences about larger colonies. However, scaling in corals shows that linear extrapolations from nubbins to whole colonies can be misleading, because polyps in nubbins are divorced of their morphologically complex and physiologically integrated corallum. We tested for the effects of integration among branches in determining size-dependent calcification of the coral Pocillopora spp. under elevated PCO2. Area-normalized net calcification was compared between branches (nubbins), aggregates of nubbins (complex morphologies without integration) and whole colonies (physiologically integrated) at 400 versus approximately 1000 µatm PCO2. Net calcification was unaffected by PCO2, but differed among colony types. Single nubbins grew faster than whole colonies, but when aggregated, nubbins changed calcification to match whole colonies even though they lacked integration among branches. Corallum morphology causes the phenotype of branching corals to differ from the summation of their branches. 相似文献
1000.
Freddie W. Leith Jennifer L. Grigg Barbara J. Barham Peter J. Barham Katrin Ludynia Cuan McGeorge Andile Mdluli Nola J. Parsons Lauren J. Waller Richard B. Sherley 《Ecology and evolution》2022,12(9)
In long‐lived species, reproductive skipping is a common strategy whereby sexually mature animals skip a breeding season, potentially reducing population growth. This may be an adaptive decision to protect survival, or a non‐adaptive decision driven by individual‐specific constraints. Understanding the presence and drivers of reproductive skipping behavior can be important for effective population management, yet in many species such as the endangered African penguin (Spheniscus demersus), these factors remain unknown. This study uses multistate mark‐recapture methods to estimate African penguin survival and breeding probabilities at two colonies between 2013 and 2020. Overall, survival (mean ± SE) was higher at Stony Point (0.82 ± 0.01) than at Robben Island (0.77 ± 0.02). Inter‐colony differences were linked to food availability; under decreasing sardine (Sardinops sagax) abundance, survival decreased at Robben Island and increased at Stony Point. Additionally, reproductive skipping was evident across both colonies; at Robben Island the probability of a breeder becoming a nonbreeder was ~0.22, versus ~0.1 at Stony Point. Penguins skipping reproduction had a lower probability of future breeding than breeding individuals; this lack of adaptive benefit suggests reproductive skipping is driven by individual‐specific constraints. Lower survival and breeding propensity at Robben Island places this colony in greater need of conservation action. However, further research on the drivers of inter‐colony differences is needed. 相似文献