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排序方式: 共有69条查询结果,搜索用时 15 毫秒
51.
Yoshito Nagano Toru Fukushima Kazuo Okemoto Keiichiro Tanaka David DL Bowtell Ze'ev A Ronai John C Reed Shu-ichi Matsuzawa 《Cell cycle (Georgetown, Tex.)》2011,10(15):2592-2602
p27kip1 has been implicated in cell cycle regulation, functioning as an inhibitor of cyclin-dependent kinase activity. In addition, p27 was also shown to affect cell migration, with accumulation of cytoplasmic p27 associated with tumor invasiveness. However, the mechanism underlying p27 regulation as a cytoplasmic protein is poorly understood. Here we show that glucose starvation induces proteasome-dependent degradation of cytoplasmic p27, accompanied by a decrease in cell motility. We also show that the glucose limitation-induced p27 degradation is regulated through an ubiquitin E3 ligase complex involving Siah1 and SIP/CacyBP. SIP−/− embryonic fibroblasts have increased levels of cytosolic p27 and exhibit increased cell motility compared with wild-type cells. These observations suggest that the Siah1/SIP E3 ligase complex regulates cell motility through degradation of p27.Key words: p27kip1, Siah1, SIP, glucose starvation, cell migration 相似文献
52.
Bik HM Porazinska DL Creer S Caporaso JG Knight R Thomas WK 《Trends in ecology & evolution》2012,27(4):233-243
Microscopic eukaryotes are abundant, diverse and fill critical ecological roles across every ecosystem on Earth, yet there is a well-recognized gap in understanding of their global biodiversity. Fundamental advances in DNA sequencing and bioinformatics now allow accurate en masse biodiversity assessments of microscopic eukaryotes from environmental samples. Despite a promising outlook, the field of eukaryotic marker gene surveys faces significant challenges: how to generate data that are most useful to the community, especially in the face of evolving sequencing technologies and bioinformatics pipelines, and how to incorporate an expanding number of target genes. 相似文献
53.
Although nematodes are the most abundant metazoan animals on Earth, their diversity is largely unknown. To overcome limitations of traditional approaches (labour, time, and cost) for assessing biodiversity of nematode species in environmental samples, we have previously examined the suitability of high-throughput sequencing for assessing species level diversity with a set of control experiments employing a mixture of nematodes of known number and with known sequences for target diagnostic loci. Those initial experiments clearly demonstrated the suitability of the approach for identification of nematode taxa but lacked the replicate experiments necessary to evaluate reproducibility of the approach. Here, we analyze reads generated from three different PCR amplifications and three different sequencing reactions to examine the differential PCR amplification, the possibility of emulsion PCR artefacts, and differences between sequencing reactions. Our results suggest that both qualitative and quantitative data are consistent and highly reproducible. Variation associated with in-house PCR amplification or emPCR and sequencing are present but the representation of each nematode is very consistent from experiment to experiment and supports the use of read counts to estimate relative abundance of taxa in a metagenetic sample. 相似文献
54.
With the cancellation of fenamiphos in the near future, alternative nematode management tactics for plant-parasitic nematodes (PPN) on golf courses need to be identified. The use of entomopathogenic nematodes (EPN) has been suggested as one possible alternative. This paper presents the results of 10 experiments evaluating the efficacy of EPN at managing PPN on turfgrasses and improving turf performance. These experiments were conducted at various locations throughout Florida over the course of a decade. In different experiments, different EPN species were tested against different species of PPN. Separate experiments evaluated multiple rates and applications of EPN, compared different EPN species, and compared single EPN species against multiple species of PPN. In a few trials, EPN were associated with reductions in certain plant-parasite species, but in other trials were associated with increases. In most trials, EPN had no effect on plant parasites. Because EPN were so inconsistent in their results, we conclude that EPN are not acceptable alternatives to fenamiphos by most turf managers in Florida at this time. 相似文献
55.
Estimation of the membrane potential of cultured macrophages from the fast potential transient upon microelectrode entry 总被引:3,自引:1,他引:2
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Analysis of membrane potential recordings upon microelectrode impalement of four types of macrophages (cell lines P388D1 and PU5-1.8, cultured mouse peritoneal macrophages, and cultured human monocytes) reveals that these cells have membrane potentials at least two times more negative than sustained potential values (E(s)) frequently reported. Upon microelectrode entry into the cell (P388D1), the recorded potential drops to a peak value (E(p)) (mean -37 mV for 50 cells, range -15 to -70 mV) within 2 ms, after which it decays to a depolarized potential (E(n)) (mean -12 mV) in about 20 ms. Thereafter, the membrane develops one or a series of slow hyperpolarizations before a final sustained membrane potential (E(s)) (mean -14 mV, range -5 to -40) is established. The mean value of the peak of the first hyperpolarization (E(h)) is -30 mV (range -10 to -55 mV). The initial fast peak transient, measured upon microelectrode entry, was first described and analyzed by Lassen et al. (Lassen, U.V., A.M. T. Nielson, L. Pape, and L. O. Simonsen, 1971, J. Membr. Biol. 6:269-288 for other change in the membrane potential from its real value before impalement to a sustained depolarized value. This was shown to be true for macrophages by two-electrode impalements of single cells. Values of E(p), E(n), E(h), E(s), and membrane resistance (R(m)) measured for the other macrophages were similar to those of P388D1. From these results we conclude that E(p) is a better estimate of the true membrane potential of macrophages than E(s), and that the slow hyperpolarizations upon impalement should be regarded as transient repolarizations back to the original membrane potentials. Thus, analysis of the initial fast impalement transient can be a valuable aid in the estimation of the membrane potential of various sorts of small isolated cells by microelectrodes. 相似文献
56.
Stable expression of mammalian beta 1,4-galactosyltransferase extends the N-glycosylation pathway in insect cells 总被引:5,自引:2,他引:3
An established lepidopteran insect cell line (Sf9) was cotransfected with
expression plasmids encoding neomycin phosphotransferase and bovine beta
1,4-galactosyltransferase. Neomycin-resistant transformants were selected,
assayed for beta 1,4-galactosyltransferase activity, and the transformant
with the highest level of enzymatic activity was characterized. Southern
blots indicated that this transformed Sf9 cell derivative contained
multiple copies of the galactosyltransferase- encoding expression plasmid
integrated at a single site in its genome. One-step growth curves showed
that these cells supported normal levels of baculovirus replication.
Baculovirus infection of the transformed cells stimulated beta
1,4-galactosyltransferase activity almost 5-fold by 12 h postinfection.
This was followed by a gradual decline in activity, but the infected cells
still had about as much activity as uninfected controls as late as 48 h
after infection and they were able to produce a beta 1,4-galactosylated
virion glycoprotein during infection. Infection of the transformed cells
with a conventional recombinant baculovirus expression vector encoding
human tissue plasminogen activator also resulted in the production of a
galactosylated end-product. These results demonstrate that stable
transformation can be used to add a functional mammalian
glycosyltransferase to lepidopteran insect cells and extend their N-
glycosylation pathway. Furthermore, stably-transformed insect cells can be
used as modified hosts for conventional baculovirus expression vectors to
produce foreign glycoproteins with "mammalianized" glycans which more
closely resemble those produced by higher eucaryotes.
相似文献
57.
The impact of gender and/or hormone variations on a wide variety of neural functions makes the choice between studying males or females (or both) of a given species difficult. Although female rats are widely used experimentally, few studies control for the stage of estrus. More detailed information about how to distinguish the various stages of the estrous cycle is needed. For the present study, vaginal smears were obtained once a day and stained using an adaptation of the Papanicolaou (PAP) procedure. Images are provided of unstained “wet” samples and the corresponding PAP stained smears illustrating the cellular profile for each stage of the cycle as well as post-ovariectomy. The different cell populations across the cycle were quantified and ratios determined to show trends between the predominant and other cell types in each stage of the estrous cycle. Both stained and unstained images and cell quantification data provide valuable guidelines for distinguishing the stages of the estrous cycle. 相似文献
58.
Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
59.
The impact of gender and/or hormone variations on a wide variety of neural functions makes the choice between studying males or females (or both) of a given species difficult. Although female rats are widely used experimentally, few studies control for the stage of estrus. More detailed information about how to distinguish the various stages of the estrous cycle is needed. For the present study, vaginal smears were obtained once a day and stained using an adaptation of the Papanicolaou (PAP) procedure. Images are provided of unstained “wet” samples and the corresponding PAP stained smears illustrating the cellular profile for each stage of the cycle as well as post-ovariectomy. The different cell populations across the cycle were quantified and ratios determined to show trends between the predominant and other cell types in each stage of the estrous cycle. Both stained and unstained images and cell quantification data provide valuable guidelines for distinguishing the stages of the estrous cycle. 相似文献
60.
Lisa?M?VallelyEmail author Angela?Kelly Martha?Kupul Ruthy?Neo Voletta?Fiya John?M?Kaldor Glen?DL?Mola Heather?Worth 《International breastfeeding journal》2013,8(1):6