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排序方式: 共有363条查询结果,搜索用时 15 毫秒
1.
Susan H. McKiernan Murray K. Clayton Barry D. Bavister 《Molecular reproduction and development》1995,42(2):188-199
Hamster embryo development to the blastocyst stage in vitro can be modulated by amino acids. This series of experiments employed both empirically and statistically designed approaches to elucidate which of 20 amino acids inhibit or stimulate development and to devise a complement of amino acids that best supports in vitro development of hamster 1-cell embryos. Development and/or mean cell number were significantly inhibited by the presence of leucine, tyrosine, valine, isoleucine, phenylalanine, arginine, methionine, or cysteine (at 0.5 mM) and isoleucine, phenylalanine, or tryptophan (at 0.05 mM). Three amino acids—glutamine, taurine, and glycine—were stimulatory and in combination improved development; the culture medium containing these amino acids was designated Hamster Embryo Culture Medium-5. Moreover, addition of another eight amino acids—asparagine, aspartic acid, serine, glutamic acid, histidine, lysine, proline and cysteine (medium designated HECM-6)—had a significant stimulatory effect on development over previously formulated culture media for hamster embryos. These results demonstrated that amino acids, alone and in combination, can markedly stimulate or inhibit hamster embryo development in vitro up to the blastocyst stage. Embryo transfer experiments showed that HECM-5 and ?6 (chemically defined, protein-free culture media) supported normal preimplantation embryo development in vitro. This study also indicates that empirically designed embryo culture media formulations can be as effective as those obtained by application of statistical methodologies. © 1995 wiley-Liss, Inc. 相似文献
2.
Interaction cloning of Rabin3, a novel protein that associates with the Ras-like GTPase Rab3A. 总被引:9,自引:3,他引:6
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W H Brondyk C J McKiernan K A Fortner P Stabila R W Holz I G Macara 《Molecular and cellular biology》1995,15(3):1137-1143
Rab3A is a small, Ras-like GTPase expressed in neuroendocrine cells, in which it is associated with secretory vesicle membranes and regulates exocytosis. Using the yeast two-hybrid system, we have identified a rat brain cDNA encoding a novel 50-kDa protein, which we have named Rabin3, that interacts with Rab3A and Rab3D but not with other small GTPases (Rab3C, Rab2, Ran, or Ras). Several independent point mutations in the effector domain of Rab3A (F51L, V55E, and G56D) which do not alter nucleotide binding by the GTPase abolish the interaction with Rabin3, while another mutation (V52A) appears to increase the interaction. These results demonstrate that the interaction is highly specific. However, a glutathione S-transferase-Rabin3 fusion protein associates only weakly in vitro with recombinant Rab3A and possesses no detectable GTPase-activating protein or nucleotide exchange activity, and Rabin3 overexpressed in adrenal chromaffin cells has no observable effect on secretion. The protein possess a sequence characteristic of coiled-coil domains and a second small region with sequence similarity to a Saccharomyces cerevisiae protein, Sec2p, Sec2p is essential for constitutive secretion in yeast cells and interacts with Sec4p, a close relative of the Rab3A GTPase. Rabin3 mRNA and protein are widely expressed but are particularly abundant in testes. 相似文献
3.
Environmental variables influencing in vitro development of hamster 2-cell embryos to the blastocyst stage 总被引:6,自引:0,他引:6
This study is a systematic analysis of environmental variables influencing development of 2-cell hamster embryos to the blastocyst stage in vitro. Experiments were done using a chemically defined (protein-free) culture medium (HECM-2). Physicochemical variables examined were temperature, the concentrations of CO2, HCO3-, Ca2+, Mg2+, K+, and O2, the presence of a silicone oil overlay, and osmotic pressure. The optimal temperature for development in vitro was 37.5 degrees C; lower temperatures were inhibitory. There was no significant effect on blastocyst development of alterations in the concentrations of NaHCO3, CaCl2, MgCl2, and KCl, or in the ratios of Ca2+:Mg2+ and Na+:K+, over the ranges tested. Development to the blastocyst stage was significantly stimulated by increased CO2 concentrations (7.5% and 10%), by reduced O2 concentrations (10% and 5%), and by the presence of silicone oil overlying the culture medium. Reduction of blastocyst development in the absence of an oil overlay was not caused by increased osmotic pressure. Cleavage stage embryos were not affected by osmolalities ranging from 250 to 350 mOsmols, but blastocyst development was inhibited at greater than or equal to 325 mOsmols. Under optimized conditions (37.5 degrees C, 10% CO2, 25 mM HCO3-, 2.0 mM Ca2+, 0.5 mM Mg2+, 3.0 mM K+, 10% O2, 250-300 mOsmols, with silicone oil overlay), 51-57% of 2-cell hamster embryos developed to the blastocyst stage. This represents a significant improvement over previous "standard" culture conditions, which supported development of 26% blastocysts from 2-cell hamster embryos. The culture system described here provides an adequate baseline response to support detailed investigations into the regulation of embryo development in the hamster. 相似文献
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Christopher I Keeling Macaire MS Yuen Nancy Y Liao T Roderick Docking Simon K Chan Greg A Taylor Diana L Palmquist Shaun D Jackman Anh Nguyen Maria Li Hannah Henderson Jasmine K Janes Yongjun Zhao Pawan Pandoh Richard Moore Felix AH Sperling Dezene P W Huber Inanc Birol Steven JM Jones Joerg Bohlmann 《Genome biology》2013,14(3):R27
8.
Willem F. Wolkers Sheri A. Looper Ariane E. McKiernan Nelly M. Tsvetkova Fern Tablin John H. Crowe 《Molecular membrane biology》2013,30(3):201-210
Membrane properties and the overall protein secondary structure of freeze-dried trehalose-loaded mouse platelets were studied using steady state fluorescence anisotropy and Fourier transform infrared spectroscopy (FTIR). FTIR results showed that fresh control mouse platelets have a main phase transition at ~14°C, whereas, freeze-dried platelets exhibited a main phase transition ~12°C. However, the cooperativity of the transition of the rehydrated platelets was greatly enhanced compared to that of control platelets. Anisotropy experiments performed with 1,6 diphenyl-1,3,5 hexatriene (DPH) complemented FTIR results and showed that the lipid order in the core of the membrane was affected by freeze-drying procedures. Similar experiments with trimethyl ammonium 1,6 diphenyl-1,3,5 hexatriene (TMA-DPH), a membrane surface probe, indicated that membrane properties at the membrane/water interface were less affected by freeze-drying procedures than the core of the membrane. Lyophilization did not result in massive protein denaturation, but the overall protein secondary structure was altered, based on in situ assessment of the amide-I and amide-II band profiles. Lyophilization-induced changes to endogenous platelet proteins were further investigated by studying the protein's heat stability. In fresh control platelets, proteins denatured at 42°C, whereas proteins in the rehydrated platelets denatured at 48°C. 相似文献
9.
The molecular integrity of the active site of phytases from fungi is critical for maintaining phytase function as efficient catalytic
machines. In this study, the molecular dynamics (MD) of two monomers of phytase B from Aspergillus niger, the disulfide intact
monomer (NAP) and a monomer with broken disulfide bonds (RAP), were simulated to explore the conformational basis of the
loss of catalytic activity when disulfide bonds are broken. The simulations indicated that the overall secondary and tertiary
structures of the two monomers were nearly identical but differed in some crucial secondary–structural elements in the vicinity of
the disulfide bonds and catalytic site. Disulfide bonds stabilize the β-sheet that contains residue Arg66 of the active site and
destabilize the α-helix that contains the catalytic residue Asp319. This stabilization and destabilization lead to changes in the shape
of the active–site pocket. Functionally important hydrogen bonds and atomic fluctuations in the catalytic pocket change during the
RAP simulation. None of the disulfide bonds are in or near the catalytic pocket but are most likely essential for maintaining the
native conformation of the catalytic site.
Abbreviations
PhyB - 2.5 pH acid phophatese from Aspergillus niger, NAP - disulphide intact monomer of Phytase B, RAP - disulphide reduced monomer of Phytase B, Rg - radius of gyration, RMSD - root mean square deviation, MD - molecular dynamics. 相似文献10.