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排序方式: 共有147条查询结果,搜索用时 31 毫秒
1.
High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
相似文献
2.
Segmental mobility dynamic peculiarities of poly(U), poly(A) and poly(C) synthetic polymers and their complexes were investigated by spin-label method. Imidazolide spin-label was introduced into 2'-oxi-groups of polymer ribose in correlation: one spin-label on 18-20 bases. Formation of complexes was observed by ESR spectra at two pH: 4.2 and 7.2. Segmental mobility of only single strand spin-labelled polymer segment and in the complex was evaluated by measuring rotational correlation time (tau) determined by dependence of distances between outer wide extrema in ESR spectra from solvent viscosity at different temperatures. It turned out that correlation time tau of single strand structures in a high degree depend on pH and temperature. For three strand structures abrupt increase of tau because of appearance of rigidity was observed. It is possible to evaluate part of triple complexes poly(U.A.A) and poly(U.U.A) existing in dynamic equilibrium depending on pH and temperature by the form of outer wide extrema. Adding of dye to complex of poly(U).poly(A) causes an increase of rigidity of the supermolecular structure. Quantitative characteristics of formed complexes were obtained by simulation of ESR spectra on computer. 相似文献
3.
A V Tepliakov I P Kuranova E G Arutiunian C Fr?mmel W E H?hne 《Bioorganicheskaia khimiia》1990,16(4):437-447
Crystal structure of thermitase, a serine proteinase from Thermoactinomyces vulgaris, has been determined by X-ray diffraction at 1.4 A resolution. The atomic model of thermitase refined to an R-factor of 0.149 contains 1997 protein atoms, 182 water molecules and 2 Ca2+ ions. The tertiary structure of thermitase is similar to that of subtilisin BPN'. The greatest variations are connected with insertions and deletions in the amino acid sequence, which are located on the surface of the molecule. Higher thermostability of thermitase can be explained in terms of the three-dimensional structure. The Ca2+ ions, bound to the protein molecule, as well as the ionic and hydrophobic interactions are supposed to give the main contribution to the stabilization of the structure. 相似文献
4.
RS Fisher 《The Journal of general physiology》1977,69(5):571-604
When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport. 相似文献
5.
pH-dependence of initial (admixture) adenosine triphosphate (ATP) changes (ATP synthesis and hydrolysis) was studied for aerated and deaerated aqueous solutions during the incubation of adenosine diphosphate (ADP) and inorganic phosphate (Pi) in the presence of reduced nicotinamide adenine dinucleotide (NADH) and riboflavin (Rf). The preferential pH regions were indicated both for ATP synthesis and ATP hydrolysis (pH less than pH 5.4, 5.9 divided by pH 6.5 and pH greater than 6.6, pH 5.5 divided by pH 5.8 respectively). 'Free radical content measurements were paralleled by ESR technique. On the basis of the obtained results it was assumed that a part of ESP signal attributed to ADP radicals was increased during ATP synthesis. 相似文献
6.
It was shown that the decrease in the rigidity (persistent length) of phage lambda DNA, revealed previously by laser correlation spectroscopy, occurs in an aqueous solution at concentrations of sodium salts less than 10(-2) M in the pH range 4-9.5. DNA coils of anomalously small size (approximately twofold less than the size reported by other authors) are formed. The formation of these coils is likely to be due to the separation of "normal", i.e., rigid DNA coils into two phases, which occurs as the concentration of sodium salts decreases to 1.5 x 10(-3) M and pH of the solution decreases to 4. The phase of small-size (nonrigid) coils makes the major contribution to the scattering spectra. The phase of large-size coils disappears at pH 9.5. As pH increases, the size of small coils increases. The occurrence of coils of anomalously small size was registered by another method, quick precipitation. It is assumed that the phase separation of coils is related to the structural features of water. 相似文献
7.
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9.
Anisimov VN Khavinson VKh Zavarzina NIu Zabezhinskiĭ MA Zimina OA Popovich IG Shtylik AV Arutiunian AV Oparina TI Prokopenko VM 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2001,87(1):125-136
Female CBA mice were injected with s.c. synthetic tetrapeptide Epithalon from a 6-month age until death. The drug failed to affect the body weight or food consumption, physical activity or behavioural parameters. However, it slowed down the age-related switching off of the estrus function, decreased body temperature, decelerated free redical processes, prolonged the mice life span with an accompanying drop in spontaneous tumour incidence. 相似文献
10.
Paula H Suss Luiz Guilherme A Capriglione Fabiane Barchiki Lye Miyague Danielle Jackowski Letícia Fracaro Andressa V Schittini Alexandra C Senegaglia Carmen LK Rebelatto Márcia Olandoski Alejandro Correa Paulo RS Brofman 《Experimental biology and medicine (Maywood, N.J.)》2015,240(7):969-978
The development of new therapeutic strategies is necessary to reduce the worldwide social and economic impact of cardiovascular disease, which produces high rates of morbidity and mortality. A therapeutic option that has emerged in the last decade is cell therapy. The aim of this study was to compare the effect of transplanting human umbilical cord-derived stromal cells (UCSCs), human umbilical cord blood-derived endothelial cells (UCBECs) or a combination of these two cell types for the treatment of ischemic cardiomyopathy (IC) in a Wistar rat model. IC was induced by left coronary artery ligation, and baseline echocardiography was performed seven days later. Animals with a left ventricular ejection fraction (LVEF) of ≤40% were selected for the study. On the ninth day after IC was induced, the animals were randomized into the following experimental groups: UCSCs, UCBECs, UCSCs plus UCBECs, or vehicle (control). Thirty days after treatment, an echocardiographic analysis was performed, followed by euthanasia. The animals in all of the cell therapy groups, regardless of the cell type transplanted, had less collagen deposition in their heart tissue and demonstrated a significant improvement in myocardial function after IC. Furthermore, there was a trend of increasing numbers of blood vessels in the infarcted area. The median value of LVEF increased by 7.19% to 11.77%, whereas the control group decreased by 0.24%. These results suggest that UCSCs and UCBECs are promising cells for cellular cardiomyoplasty and can be an effective therapy for improving cardiac function following IC. 相似文献