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31.
M P Boland C D Nancarrow J D Murray R J Scaramuzzi R Sutton R M Hoskinson I G Hazelton 《Journal of reproduction and fertility》1986,78(2):423-431
Ewes were immunized against androstenedione (Fecundin) and assigned to be mated 14 days (179 ewes Group C) or 25 days (174 ewes Group B) after a booster immunization with Fecundin. The anti-androstenedione titres at these times were 6790 and 3240 respectively (P less than 0.01). The remaining 169 ewes were untreated controls (Group A). Ewes were mated to entire rams (12 rams to 180 ewes) at their second oestrus after synchronization of oestrus. Immunization against androstenedione caused a shortening of the time from sponge removal to mating (Day 0) and a decrease in the percentage of ewes mated by the rams. Also, ovulation rate was increased after immunization (P less than 0.01), being 1.42, 2.16 and 1.93 for Groups A, C and B respectively. Egg recovery rates on Day 2 were lower in immunized ewes and there was some indication that fertilization rates were lowered. On Day 13 after mating a higher proportion of blastocysts was recovered from ewes in Group A than from those in Groups B and C. Immunization resulted in lower fertilization rates and smaller blastocysts with lower mitotic indexes (P less than 0.01). At Days 24-32 of pregnancy fetal weight was lower in the immunized ewes. At all sampling stages, the proportion of ewes pregnant (fertility) was lowered in immunized ewes. The results of the present study show that significant reproductive wastage occurs in androstenedione-immunized Merino ewes, with lower rates of embryo recovery and delayed embryonic development being found in comparison to controls.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
32.
R Boland A Norman E Ritz W Hasselbach 《Biochemical and biophysical research communications》1985,128(1):305-311
The presence of a specific receptor for 1,25-dihydroxy-vitamin D3 was investigated in myoblasts released from chick embryo skeletal muscle by trypsin and collagenase treatment. Density gradient analysis of the cytosol obtained from these muscle cell preparations showed that 1,25-dihydroxy-vitamin D3 binds specifically to a 3.7 S macromolecule. Scatchard analysis yielded an equilibrium dissociation constant of 2.46 x 10(-10) M and a Nmax of 74 fmol/mg of cytosol protein. The data is in agreement with previous evidence which indicates that the action of the vitamin D metabolite on muscle Ca uptake is mediated by de novo protein and RNA synthesis, and supports the concept that muscle is a target organ for 1,25-dihydroxy-vitamin D3. 相似文献
33.
Solanum elaeagnifolium Cav. fruits contain high concentrations of steroidal saponins. Treatment of 3-day-old clover seedlings with aqueous fruit extracts modified Ca2+ uptake without significantly altering K+ and H2 PO4 − uptake. The extracts increased Ca2+ uptake in the concentration range of 0.2 to 20 m M Ca2+ . Uptake curves could be represented by two phases. In the lower phase (0.2-1.0 m M Ca2+ ), this change could be related to an increase in Vmax . Pretreatment of seedlings with saponin extracts significantly reduced ATP-dependent Ca2+ uptake and Ca2+ -dependent ATPase activity in a fraction isolated from root homogenates by centrifugation at 1500 g for 15 min. Saponins purified from S. eleagnifolium extracts by thin-layer chromatography modified in vitro the Ca2+ -ATPase activity of this fraction, indicating that the steroid may act directly on Ca2+ transport across membranes. 相似文献
34.
Summary Two new species of the genus Heterokrohnia, H. longidentata and H. fragilis, are described and compared with the other three known Heterokrohnia species, H. mirabilis Ritter-Záhony 1911; H. bathybia Marumo and Kitou 1966 and H. involucrum Dawson 1968. The species have been found at great depths (1,000 m–2,000 m) near Elephant Island, north of the Antarctic Peninsula. 相似文献
35.
36.
Astrid Christiani Peter Hügelmeyer Prof. Dr. Wilhelm Stockem 《Cell and tissue research》1986,246(1):163-168
Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure. 相似文献
37.
Day 7 to 9 embryos were frozen by a rapid two-step method to ?38°C before being plunged into liquid nitrogen. Glycerol was used as the cryoprotectant and, following thawing, the embryos were cultured for 12 – 24 hours in PBS + 15% heat-treated steer serum. In Experiment 1, embryos were frozen in 2.0 ml glass ampoules or 0.5 ml Cassou straws. Two levels of glycerol (1.0M and 1.4M) gave comparable survival rates ( and , respectively). A greater proportion of embryos developed in culture after freezing in straws. In Experiment 2, embryos were classified morphologically before and after freezing into 5 grades (1 = excellent; 2 = good; 3 = fair; 4 = poor; 5 = degenerate). Only embryos of grade 1, 2 and 3 were frozen. The post-thaw survival rates for embryos graded 1, 2 and 3 before freezing were 100% (), 86% () and 83% (), respectively. Furthermore, the porportion of surviving embryos estimated to be of poor quality (grade 4) was greater for embryos graded 3 before freezing () than for embryos graded 2 () or 1 (). The percentage of embryos which developed normally after culture for each of the pre-freezing grades 1, 2 and 3 was 91% (), 50% () and 29% (), respectively. Of the total number of frozen-thawed embryos which developed in culture, (16%) were of poor quality. The proportion of poor quality developing embryos was greater inembryos graded 3 before freezing () than those graded 2 (). All of the embryos graded 1 before freezing and which developed in culture were of good quality. Results indicate that, if high post-thaw survival rates are to be obtained, stringent embryo selection processes will be required. 相似文献
38.
Cristoph Zimmer Gerhard Luck Eckhard Birch-Hirschfeld Roland Weiss Federico Arcamone Wilhelm Guschlbauer 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,741(1):15-22
Different binding affinities of various distamycin analogs including the deformylated derivative with poly(dA-dC)·poly(dG-dT) were investigated using CD measurements. The inhibitory effect of distamycins on the DNAase I cleavage activity of DNA duplexes strongly supports the binding data. The base specificity of the ligand interaction with duplex DNA depends on the chain length of distamycin analogs. Netropsin, distamycin-2 and the deformylated distamycin-3 show no binding to dG·dC containing sequences at moderate ionic strength and are classified as highly dA·dT specific. In contrast distamycin having three, four or five methylpyrrolecarboxamide groups also forms more or less stable complexes with dG·dC-containing duplexes. These ligands possess a lower basepair specificity. The correlation between binding behavior and oligopeptide structure shows that presence of the number of hydrogen acceptor and donor sites determines the basepair and sequence specificity. The additional interaction with dG·dC pairs becomes essential when the number of hydrogen acceptor sites exceeds n = 3. 相似文献
39.
The effects of vitamin D-3 on calcium and phosphate transport in skeletal muscle plasma membranes were studied. Sarcolemma vesicles were isolated from vitamin D-deficient and vitamin D-treated (one week) chicks by sucrose density gradient centrifugation of a crude muscle plasma membrane fraction. Measurement of (Na+ + K+)-ATPase activity, cholesterol to phospholipid molar ratios and levels of intracellular marker enzymes showed a high degree of purification of the preparations. Administration of vitamin D-3 significantly increased active Ca2+ and phosphate uptake into the vesicles. The efflux of both ions from preloaded vesicles was only slightly altered by the sterol. Ca2+-ATPase activity was higher in sarcolemma from treated animals. This confirms that the effects of vitamin D-3 on calcium transport are related to the Ca2+ pump and not to the passive permeability properties of the membrane. No changes in the protein composition of vesicles from both experimental groups were observed. However, treatment with vitamin D-3 increased sphingomyelin and phosphatidylcholine concentrations. These changes in lipid structure may play a role in the effects of vitamin D-3 on transport characteristics of sarcolemma. 相似文献
40.
Dynamics of the cytoskeleton in Amoeba proteus 总被引:3,自引:0,他引:3
Fluorescein-labeled muscle actin was microinjected into Amoeba proteus and followed during intracellular redistribution by means of the image-intensification technique. The fully polymerization-competent protein becomes part of the endogenous actomyosin system undergoing dynamic changes over time periods of several hours. Single-frame analysis of long-term sequences enabled the direct demonstration of both the contractile activities and morphological transformations of microfilaments in normally locomoting, immobilized and phagocytozing specimens. In normally locomoting cells the filament layer undergoes continuous changes in spatial distribution depending on the actual pattern of cytoplasmic streaming and cell shape. The highest degree of differentiation is always maintained in the intermediate region between the front and the uroid, thus indicating this segment of the cortex to be the most important site in generating motive force for pseudopodium formation and ameboid movement. In immobilized cells contracted by the application of ruthenium red or relaxed by different anesthetics, the filament layer forms a continuous thick sheath beneath the cell surface or becomes completely disintegrated. In phagocytozing cells the local polymerization of actin at the tip of pseudopodia forming the food-cup and around the nascent phagosome points to a significant participation of the actomyosin system in the process of capturing and constricting prey organisms. Although our results provide clear evidence for the overall importance of motive force generation according to the hydraulic pressure theory, some motile phenomena exist in Amoeba proteus that cannot exclusively be explained by this mechanism. 相似文献