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71.
羊狂蝇化蛹、羽化的生物学研究 总被引:6,自引:0,他引:6
本文揭示羊狂蝇羽化与环境因素的相关性,幼虫在土壤栖息定位,蛹态,蛹与幼虫大小的相关性,成蝇活动行为和寿命,雌雄蝇比率等生物学特性,为羊狂蝇应用研究提供具有指导意义的基础资料。 相似文献
72.
大豆子叶内酸性磷酸酶活性的超微结构定位 总被引:6,自引:0,他引:6
开花后35~50 d 期间和萌发早期(播种后4~8 d)的大豆(Glycinem ax L.)种子中,酸性磷酸酶主要分布在子叶细胞中的蛋白体内;在内质网内也检测到酸性磷酸酶活性。此外,在萌发早期的部分子叶细胞的质膜外侧及其细胞壁基质中可见密集的酸性磷酸酶活性;而且在近质膜的胞质中常见到一些富含磷酸铅沉淀的胞质小泡,似与质膜融合 相似文献
73.
Victor D. Ramirez Jianbiao Zheng Khawar M. Siddique 《Cellular and molecular neurobiology》1996,16(2):175-198
Summary 1. There are numerous circumstantial evidence supporting the concept that steroid hormones control cellular function by means other than the nuclear receptor steroid binding mechanism. It is the intent of this report to present evidence indicating that steroids bind to specific sites in neuronal membranes.2. Some of the criteria to define steroid membrane receptors using steroid-BSA conjugates that can be radioiodinated to desired specific activity have been fulfilled for each of the three sex steroids using crude synaptosomal membrane preparations (P2 fractions) from the CNS of female and male rats. Ligand binding for each of the three steroids indicate high-affinity and high-capacity sites with distinct brain selectivity and stereospecificity. For example, 17-E-6-[125I]BSA binds hypothalamic P2 fractions (HYP-P2) with an estimatedK
d of about 3±0.7 nM (X ± SE;n=3), whereas the cerebellum P2 (CB-P2) fractions bind the ligand with aK
d of 34±7 nM and, aB
max of 3 and 42 pmol/mg protein, respectively. Estrogen and testosterone binding fit best a one-single site, while progesterone binding sites can be best represented by a two-binding site, one high-affinity (K
d=1–2 nM) and one low affinity (K
d=62 nM), in CB-P2 fractions from intact adult female rat brain. Kinetics studies for T-3-[125I]BSA indicate that the estimatedK
d of 30±2 nM for the olfactory bulb P2 fractions (OB-P2) from male rats is in good agreement withK
d values computed from Scatchard-derived data using the LIGAND algorithm.3. 17-E-6-[125I]BSA binding sites are stereospecific and appears to be present as early as 5 days of age in both the OB- and the CB-P2 fractions without changes during development. In contrast, P-6-[125I]BSA binding sites are practically absent during days 5 and 12 and appear by day 22.4. Finally, membrane receptor molecules for estrogen and progesterone have been isolated and purified by affinity chromatography and characterized by PAGE and Western blot. Microsequencing of one of the membrane estrogen binding proteins indicates that the high-affinity site corresponds to the OSCP subunit of the proton ATP synthase.5. It remains to be determined if P and T also bind to this complex enzyme or if they bind to other subunits of the family of proton ATPases. Overall the data indicate that steroid hormones conjugated to BSA are important tools to study the reality of membrane steroid receptors. 相似文献
74.
Hair samples of 23 male professional drivers and 20 male university teachers in Hong Kong were collected, and the concentrations of Al, Sb, As, Ca, Cu, Fe, Pb, Mg, Mn, Hg, K, Sr, S, V, and Zn were measured. Both of the target groups fell within the same age group of 35–45. The washing method of using detergent and powder was found to be comparable to that of using ether. Difference in the mean concentration of each detected element in the two groups was tested by the Student'st-test and the Wilcoxon rank-sums test. Hair concentrations of Al, Sb, Pb, Mg, Mn, and K in the «Driver Group» were significantly (p<0.05) higher than those in the “Teacher Group.” On the other hand, As and Hg were found to have a higher concentration in hair of teachers. Interpretation of the findings in terms of the environmental factor and the metabolic rate was attempted. 相似文献
75.
Phospholipase D (PLD; EC 3.1.4.4) has been proposed to play a pivotal role in various cellular processes, but molecular understanding of this enzyme is rather limited. This report describes the nucleotide sequence, structure, and genomic organization of a PLD gene from castor bean (Ricinus communis L. cv. Hale). The PLD gene was isolated from a castor bean genomic library using the PLD cDNA as a hybridization probe. Sequence comparison with the PLD cDNA revealed that the PLD gene consisted of four exons and three introns, one of which interrupts the 5-untranslated region. Southern blot analysis indicated that the cloned PLD gene was present as a single-copy gene, and yet there were other PLD or PLD-related sequences in the castor bean genome. 相似文献
76.
H. -X. Lin H. -R. Qian J. -Y. Zhuang J. Lu S. -K. Min Z. -M. Xiong N. Huang K. -L. Zheng 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,92(8):920-927
Quantitative triat loci (QTLs) for yield and related traits in rice were mapped based on RFLP maps from two indica/indica F2 populations, Tesanai 2/CB and Waiyin 2/CB. In Tesanai 2/CB, 14 intervals carrying QTLs for eight traits were detected, including 3 for grain weight per plant (GWT), 2 for number of panicles per plant (NP), 2 for number of grains per panicle (NG), 1 for total number of spikelets per panicle (TNS), 1 for spikelet fertility (SF), 3 for 1000-grain weight (TGWT), 1 for spikelet density (SD), and 1 for number of first branches per main panicle. The 3 QTLs for GWT were located on chromosomes 1, 2, and 4, with 1 in each chromosome. The additive effect of the single locus ranged from 2.0 g to 9.1 g. A major gene (np4) for NP was detected on chromosome 4 within the interval of RG143–RG214, about 4cM for RG143, and this locus explained 26.1% of the observed phenotypic variance for NP. The paternal allele of this locus was responsible for reduced panicles per plant (3 panicles per plant). In another population, Waiyin 2/CB, 12 intervals containing QTLs for six of the above-mentioned traits were detected, including 3 for GWT, 2 for each of NP, TNS, TGWT and SD, 1 for SF. Three QTLs for GWT were located on chromosome 1, 4, and 5, respectively. The additive effect of the single locus for GWT ranged from 6.7 g to 8.8 g, while the dominance effect was 1.7–11.5 g. QTL mapping in two populations with a common male parent is compared and discussed. 相似文献
77.
The LIM domain-containing Dbm1 GTPase-activating protein is required for normal cellular morphogenesis in Saccharomyces cerevisiae. 总被引:1,自引:0,他引:1
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Normal cell growth in the yeast Saccharomyces cerevisiae involves the selection of genetically determined bud sites where most growth is localized. Previous studies have shown that BEM2, which encodes a GTPase-activating protein (GAP) that is specific for the Rho-type GTPase Rho1p in vitro, is required for proper bud site selection and bud emergence. We show here that DBM1, which encodes another putative Rho-type GAP with two tandemly arranged cysteine-rich LIM domains, also is needed for proper bud site selection, as haploid cells lacking Dbm1p bud predominantly in a bipolar, rather than the normal axial, manner. Furthermore, yeast cells lacking both Bem2p and Dbm1p are inviable. The nonaxial budding defect of dbm1 mutants can be rescued partially by overproduction of Bem3p and is exacerbated by its absence. Since Bem3p has previously been shown to function as a GAP for Cdc42p, and also less efficiently for Rho1p, our results suggest that Dbm1p, like Bem2p and Bem3p, may function in vivo as a GAP for Cdc42p and/or Rho1p. Both LIM domains of Dbm1p are essential for its normal function. Point mutations that alter single conserved cysteine residues within either LIM domain result in mutant forms of Dbm1p that can no longer function in bud site selection but instead are capable of rescuing the inviability of bem2 mutants at 35 degrees C. 相似文献
78.
Characterization of universal small-subunit rRNA hybridization probes for quantitative molecular microbial ecology studies. 总被引:31,自引:18,他引:13
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Universal oligonucleotide hybridization probes targeting the small-subunit rRNA are commonly used to quantify total microbial representation in environmental samples. Universal probes also serve to normalize results obtained with probes targeting specific phylogenetic groups of microorganisms. In this study, six universal probes were evaluated for stability of probe-target duplexes by using rRNA from nine organisms representing the three domains of Bacteria, Archaea, and Eucarya. Domain-specific variations in dissociation temperatures were observed for all probes. This could lead to a significant bias when these probes are used to quantify microbial populations in environmental samples. We suggest lowering the posthybridization wash stringency for two of the universal probes (S-*-Univ-1390-a-A-18 and S-*-Univ-1392-a-A-15) examined. These two probes were evaluated with traditional and modified hybridization conditions to characterize defined mixtures of rRNAs extracted from pure cultures and rRNA samples obtained from anaerobic digester samples. Probe S-*-Univ-1390-a-A-18 provided excellent estimations of domain-level community composition of these samples and is recommended for future use in microbial ecology studies. 相似文献
79.
将菠菜叶片匀浆后.用差速离心和梯度率心分离叶绿体、过氧物酶体、微粒体等细胞器和100000×g上清法部分。用酶活测定法测定各部分甜菜碱醛脱氢酶(BADH)的活性;用免疫扩散法鉴定各组分的BADH。除叶绿体外,过氧物酶体、微粒体.以及100000×g上清液中也存在BADH。 相似文献
80.
The ability of neurotrophin-4/5 (NT-4/5), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and nerve growth factor (NGF) to promote survival of postnatal rat vestibular ganglion neurons (VGNs) was examined in dissociated cell cultures. Of the four neurotrophins, NT-4/5 and BDNF were equally effective but more potent than NT-3 in promoting the survival of VGNs. In contrast, NGF showed no detectable effects. As expected, TrkB-IgG (a fusion protein of extracellular domain of TrkB and Fc domain of human immunoglobulin G) specifically inhibited the survival-promoting effects by NT-4/5 or BDNF and TrkC-IgG fusion protein completely blocked that of NT-3. Immunohistochemistry with TrkB, TrkA, and p75 antisera revealed that VGNs made TrkB and p75 proteins, but not TrkA protein. Ototoxic therapeutic drugs such as cisplatin and gentamicin often induce degeneration of hair cells and ganglion neurons in both auditory and vestibular systems that leads to impairment of hearing and balance. When cisplatin and gentamicin were added to the dissociated VGN culture in which the hair cells were absent, additional cell death of VGNs was induced, suggesting that the two ototoxins may have a direct neurotoxic effect on ganglion neurons in addition to their known toxicity on hair cells. However, if the cultures were co-treated with neurotrophins, NT-4/5, BDNF, and NT-3, but not NGF, prevented or reduced the neurotoxicity of the two ototoxins. Thus, the three neurotrophins are survival factors for VGNs and are implicated in the therapeutic prevention of VGN loss caused by injury and ototoxins. © 1995 John Wiley & Sons, Inc. 相似文献