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41.
Restriction fragment length polymorphisms in dairy and beef cattle at the growth hormone and prolactin loci 总被引:2,自引:0,他引:2
Two bovine populations, a Holstein-Friesian dairy stock and a synthetic (Baladi X Hereford X Simmental X Charolais) beef stock, were screened for restriction fragment length polymorphisms (RFLPs) at the growth hormone and prolactin genes. Most RFLPs at the growth hormone gene are apparently the consequence of an insertion/deletion event which was localized to a region downstream of the structural gene. The restriction map for the genomic region including the growth hormone gene was extended. Two HindIII RFLPs at the growth hormone locus, as well as several RFLPs at the prolactin gene, seemed to be the consequence of a series of point mutations. The results are discussed in terms of the possibility that minor genomic variability underlies quantitative genetic variation. 相似文献
42.
Host immunoglobulin G titre and antibody activity in haemolymph of the tick, Ornithodoros moubata 总被引:1,自引:0,他引:1
Immunoglobulin G (IgG) in tick haemolymph was analysed immunochemically and biochemically for its antigenicity, antibody activity and relative concentration in a soft tick, Ornithodoros moubata (Murray) sensu Walton 1962 (Acari: Argasidae). Ouchterlony immunodiffusion tests showed that haemolymph from a tick engorged on rabbit IgG (or human IgG) through an artificial membrane, reacted with anti-rabbit IgG (anti-human IgG) but not with anti-human IgG (anti-rabbit IgG). This indicates that haemolymph of the fed tick contains IgG with a similar antigen specificity to host blood IgG. IgG from tick haemolymph was demonstrated by enzyme immunoassay to have the same antibody activity as ingested IgG. The IgG concentration in tick haemolymph was measured by a quantitative single immunodiffusion test. Changes of IgG titre after a bloodmeal were correlated with IgG activity, which was low for 5 days after a bloodmeal and then suddenly increased. The IgG titre reached a maximum 7 days post-engorgement, and remained high for over 4 months during and after oviposition. 125I-labelled IgG was injected into the tick haemocoel to determine the persistence of IgG in the haemolymph. Recovery of labelled IgG was low at 1 and 3 days, and high at 5, 8 and 16 days after engorgement. The data suggest that IgG in haemolymph disappears quickly soon after engorgement possibly by degradation and/or absorption (adhesion to tissues). 相似文献
43.
Glutamine synthetase (GS) from the chick brain was purified to apparent homogeneity by ammonium sulfate fractionation followed by affinity chromatography, electrofocusing and Sephadex G-150 chromatography. The purified enzyme showed a single band on sodium dodecyl sulfate analysis in polyacrylamide gel. By sedimentation equilibrium analysis and gel electrophoresis analysis, it was shown that the enzyme has a subunit molecular weight of 45,000 and a native molecular weight of 364,000, which is consistent with an octameric structure. Sedimentation analysis in the presence of Mg2+ revealed three different forms of macromolecules corresponding respectively to a monomer, a tetramer and an octamer. Among eight cations tested (Ca2+, Co2+, Fe2+, Li+, Mg2+, Mn2+, Ni2+, Zn2+) only Co2+, Mg2+ and Mn2+ supported GS activity; the order of activatory ability was Mg2+>Co2+>Mn2+. The maximum activating effect of Mn2+ occurs only within a very narrow range of concentration: with an excess of cation causing strong inhibition of GS activity. For each cation, maximal GS activity occurs at a defined cation/ATP ratio. A regulatory system in which Mn2+, modulates the Mg2+ dependent GS activity, is proposed; such cation interactions may be of significance in the intracellular control of glutamine synthesis. 相似文献
44.
Extracellular enzymes of mycobacteria 总被引:1,自引:0,他引:1
Abstract Extracellular enzymes were studied in different mycobacteria using a plate substrate assay. All the pathogenic mycobacteria included in the study showed the presence of protease, while lipase, ribonuclease, mucinase and β-lactamase could also be detected in some strains. In contrast, no protease was detected in the 3 saprophytic mycobacteria studied. DNase was not detected in any of the species studied. Thus, the demonstration of extracellular enzymes, in particular of protease, in mycobacteria may be relevant in understanding their role in pathogenicity. 相似文献
45.
Jay C. D. Hinton Julie M. Sidebotham Lizbeth J. Hyman Michel C. M. Pérombelon George P. C. Salmond 《Molecular & general genetics : MGG》1989,217(1):141-148
Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi- mutants has allowed us to consider some factors that affect Eca virulence. 相似文献
46.
Basidiomycetous fungi, two saprophytes and three mycorrhizal, were used to assess the specificity of DNA hybridization for
distinguishing genera from one another. Interspecific comparisons were done with several isolates of mycorrhizal fungi,Laccaria bicolor andL. laccata, collected from diverse geographical sites. The DNAs were digested with four restriction nucleases and separated by gel electrophoresis
into patterns of DNA fragments called restriction fragment length polymorphisms (RFLPs). The RFLPs were hybridized with a
radioactively-labeled DNA probe encoding Basidiomycetous ribosomal RNA genes. The five genera were discernable using both
unprobed and probed RFLPs. Hybridization of probe DNA with RFLPs was isolate-specific for all nine Laccaria isolates examined.
The reclassification of aL. bicolor isolate is supported, demonstrating that hybridization of RFLPs offers an additional tool for taxonomy of ectomycorrhizal
fungi. The method may have field application for distinguishing known isolates if their DNA fingerprints are previously ascertained
and are distinct from RFLPs of indigenous organisms. 相似文献
47.
Komandoor E. Achyuthan Ann Mary Robin Bhaermani Charles S. Greenberg 《Molecular and cellular biochemistry》1989,85(1):57-65
Calcium ions are crucial for expression of transglutaminase activity. Although lanthanides have been reported to substitute for calcium in a variety of protein functions, they did not replace the calcium requirement during transglutaminase activity measurements. Furthermore, lanthanides strongly inhibited purified liver transglutaminase activity using either casein or fibrinogen as substrates. Terbium (III) inhibition of transglutaminase-catalyzed putrescine incorporation into casein was not reversed by the presence of 10–200 fold molar excess of calcium ions (Ki for Tb(III)=60 µM). Conformational changes in purified liver transglutaminase upon Tb(III) binding were evident from a biphasic effect of Tb(III) on transglutaminase binding to fibrin. Low concentrations of Tb(III) (1 µM to 10 µM inhibited the binding of transglutaminase to fibrin, whereas higher concentrations (20 µM to 100 µM promoted binding. Conformational changes in purified liver transglutaminase consequent to Tb(III) binding were also demonstrated by fluorescence spectroscopy due to Forster energy transfer. Fluorescence emission was stable to the presence of 200 mM NaCl and 100 mM CaCl2 only partially quenched emission. Purified liver transglutaminase strongly bound to Tb(III)-Chelating Sepharose beads and binding could not be disrupted by 100 mM CaCl2 solution. Our data suggest that Tb(III)-induced conformational changes in transglutaminase are responsible for the observed effects on enzyme structure and function. The potential applications of Tb(III)-transglutaminase interactions in elucidating the structure-function relationships of liver transglutaminase are discussed. 相似文献
48.
49.
Green cybrids with a new nucleus-chloroplast combination cannot be selected after protoplast fusion in the intersubfamilial Nicotiana-Solanum combination. As an approach to overcome the supposed plastomegenome incompatibility, a partial plastome transfer by genetic recombination has been considered. After fusions of protoplasts of a light-sensitive Nicotiana tabacum (tobacco) plastome mutant and lethally irradiated protoplasts of wild-type Solanum tuberosum (potato), a single green colony was recovered among 2.5×104 colonies. The regenerated plants had tobacco-like (although abnormal) morphology, but were normally green, and sensitive to tentoxin, demonstrating chloroplast markers of the potato parent. Restriction enzyme analysis of the chloroplast DNA (cpDNA) revealed recombinant, nonparental patterns. A comparison with physical maps of the parental cpDNA demonstrated the presence of a considerable part of the potato plastome flanked by tobacco-specific regions. This potacco plastome proved to be stable in backcross and backfusion experiments, and normally functional in the presence solely of N. tabacum nucleus. 相似文献
50.
Mitochondrial DNA polymorphism in native Philippine cattle based on restriction endonuclease cleavage patterns 总被引:4,自引:0,他引:4
Tomomasa Watanabe Joseph S. Masangkay Shigeharu Wakana Naruya Saitou Takeshi Tomita 《Biochemical genetics》1989,27(7-8):431-438
An analysis of patterns of cleavage of mtDNA by restriction endonucleases was performed for nine individuals from the Philippine
population of native cattle. MtDNA polymorphisms were detected in the restriction patterns generated by the following six
enzymes,BamHI,BglII,EcoRV,HindIII,PstI, andScaI. The restriction patterns showing polymorphisms were distributed nonrandomly among the nine individuals examined from the
Philippine population of native cattle, indicating the existence of two separate types of mtDNA. These two types of mtDNA
are very different from each other, at the level of subspecies. Since the native Philippine cattle are considered to represent
an admixture of European and Indian cattle, the two types of mtDNA must be derived from the mtDNAs of both varieties. The
polymorphic sites in mtDNA have been located on a restriction map, and the nucleotide substitutions at some of the sites have
also been estimated. 相似文献