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431.
Little is known of the control of gene expression in the animal hemisphere of the Xenopus embryo. Here we show that expression of FoxI1e, a gene essential for normal ectoderm formation, is expressed regionally within the animal hemisphere, in a highly dynamic fashion. In situ hybridization shows that FoxI1e is expressed in a wave-like fashion that is initiated on the dorsal side of the animal hemisphere, extends across to the ventral side by the mid-gastrula stage, and is then turned off in the dorsal ectoderm, the neural plate, at the neurula stage. It is confined to the inner layers of cells in the animal cap, and is expressed in a mosaic fashion throughout. We show that this dynamic pattern of expression is controlled by both short- and long-range signals. Notch signaling controls both the mosaic, and dorsal/ventral changes in expression, and is controlled, in turn, by Vg1 signaling from the vegetal mass. FoxI1e expression is also regulated by nodal signaling downstream of VegT. Canonical Wnt signaling contributes only to late changes in the FoxI1e expression pattern.These results provide new insights into the roles of vegetally localized mRNAs in controlling zygotic genes expressed in the animal hemisphere by long-range signaling. They also provide novel insights into the role of Notch signaling at the earliest stages of vertebrate development. 相似文献
432.
The effect of a beta‐lactamase inhibitor peptide on bacterial membrane structure and integrity: a comparative study 下载免费PDF全文
Begum Alaybeyoglu Bilge Gedik Uluocak Berna Sariyar Akbulut Elif Ozkirimli 《Journal of peptide science》2017,23(5):374-383
Co‐administration of beta‐lactam antibiotics and beta‐lactamase inhibitors has been a favored treatment strategy against beta‐lactamase‐mediated bacterial antibiotic resistance, but the emergence of beta‐lactamases resistant to current inhibitors necessitates the discovery of novel non‐beta‐lactam inhibitors. Peptides derived from the Ala46–Tyr51 region of the beta‐lactamase inhibitor protein are considered as potent inhibitors of beta‐lactamase; unfortunately, peptide delivery into the cell limits their potential. The properties of cell‐penetrating peptides could guide the design of beta‐lactamase inhibitory peptides. Here, our goal is to modify the peptide with the sequence RRGHYY that possesses beta‐lactamase inhibitory activity under in vitro conditions. Inspired by the work on the cell‐penetrating peptide pVEC, our approach involved the addition of the N‐terminal hydrophobic residues, LLIIL, from pVEC to the inhibitor peptide to build a chimera. These residues have been reported to be critical in the uptake of pVEC. We tested the potential of RRGHYY and its chimeric derivative as a beta‐lactamase inhibitory peptide on Escherichia coli cells and compared the results with the action of the antimicrobial peptide melittin, the beta‐lactam antibiotic ampicillin, and the beta‐lactamase inhibitor potassium clavulanate to get mechanistic details on their action. Our results show that the addition of LLIIL to the N‐terminus of the beta‐lactamase inhibitory peptide RRGHYY increases its membrane permeabilizing potential. Interestingly, the addition of this short stretch of hydrophobic residues also modified the inhibitory peptide such that it acquired antimicrobial property. We propose that addition of the hydrophobic LLIIL residues to the peptide N‐terminus offers a promising strategy to design novel antimicrobial peptides in the battle against antibiotic resistance. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
433.
O.?KurtEmail author F.?Ozdal-Kurt I.?Tuglu S.?I.?Deliloglu-Gurhan M.?Ozturk 《Russian Journal of Marine Biology》2009,35(4):342-350
In the present study, antiproliferative, apoptotic and especially neurotoxic effects of Caulerpa racemosa var. cylindracea dry and wet extracts on mouse neuroblastoma cell line, NA2B were investigated by neurotoxicity screening test (NST). C. racemosa var. cylindracea wet and dry extracts were obtained by methanol (MT) extraction. The effect of the extracts on viability and proliferation
was measured by MTT. NA2B cells were induced to differentiate using 1 μM dcAMP and the amount of inhibition of growing neurites
in different dilutions (50, 35, 25, 15, 10 and 5 μl/ml) by extracts was measured. The number of apoptotic cells was computed
by TUNEL method using cells in culture. It was found that majority of the cells died with dry extract above the level of 15
μl/ml due to the MT effect. Below this level, on the other hand, presence of cell death and antiproliferative effect was noted
due to the toxic effects of C. racemosa var. cylindracea which was independent of MT. In all doses of wet extracts, similar but less prominent dose-dependent effects were observed.
Below the level of 15 μl/ml, mild toxic effect presented itself with neurite inhibition. In addition to the toxic, apoptotic
and antiproliferative effects of C. racemosa var. cylindracea, its neurotoxic effects possessing property at low concentrations which manifesting itself by neurite inhibition was also
showed. This species offers a potential for developing new drugs due to its antiproliferative, toxic and apoptotic effects.
Nevertheless, its neurotoxic effect is a factor to be considered as multifunctional agents especially in neuronal metabolism. 相似文献
434.
Summary A control‐versus‐treatment multiple comparison test procedure is developed based on ranked set samples. The test, constructed based on K‐independent exact median confidence intervals corresponding to the K populations, rejects the null hypothesis of equal medians if the median confidence intervals of the control group and any one of the other K ? 1 treatment groups are disjoint. The use of the proposed test is illustrated with data from an agricultural experiment. 相似文献
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Hydrobiologia - Volcanoes serve as natural laboratories expanding our understanding of the recent and past ecological and evolutionary processes. Here, we present data elucidating the developmental... 相似文献
438.
Cheryl L. Rock Jennifer A. Emond Shirley W. Flatt Dennis D. Heath Njeri Karanja Bilge Pakiz Nancy E. Sherwood Cynthia A. Thomson 《Obesity (Silver Spring, Md.)》2012,20(11):2296-2301
Low circulating concentrations of vitamin D metabolites have been associated with increased risk for several diseases and clinical conditions. Large observational studies and surveys have shown that obesity is independently associated with lower serum 25‐hydroxyvitamin D (25(OH)D) concentration. Few studies have examined the effect of weight loss on serum 25(OH)D concentration. The purpose of this study was to prospectively examine the effect of weight loss on serum 25(OH)D concentration. Data were collected from 383 overweight or obese women who participated in a 2‐year clinical trial of a weight‐loss program, in which 51% (N = 195) lost at least 5% of baseline weight by 24 months, 18% (N = 67) lost 5–10%, and 33% (N = 128) lost >10%. Women who did not lose weight at 24 months had an increase in serum 25(OH)D of 1.9 (9.7) ng/ml (mean (SD)); 25(OH)D increased by 2.7 (9.1) ng/ml for those who lost 5–10% of baseline weight; and 25(OH)D increased by 5.0 (9.2) ng/ml for those who lost >10% of baseline weight (P = 0.014). At baseline, 51% (N = 197) of participants met or exceeded the recommended serum concentration of 20 ng/ml. By study end, 64% (N = 230) of overweight or obese women met this goal, as well as 83% (N = 20) of those whose weight loss achieved a normal BMI. These findings suggest that weight loss, presumably associated with a reduction in body fat, is associated with increased serum 25(OH)D concentration in overweight or obese women. 相似文献
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