马立克氏病毒单克隆抗体的研究

获得了4株分泌马立克氏病毒(MDV)特异性单克隆抗体(McAb)的杂交瘤细胞:4BS10对MDV所有毒株呈阳性反应;4CN8 对MDV血清1,3型毒株发生反应;2BN90和4CN24只对MDV血清1型毒株有阳性反应。3个McAb属IgG1,1个为IgG2b,均不中和MDV,免疫扩散试验也无沉淀线。对禽白血病毒(ALV)无交叉反应。 以2BN90和辣根过氧化物酶、异硫氰酸荧光素的结合物进行直接酶联免疫吸附试验和直接荧光抗体试验,均获得成功。抗体滴度前者为1/51,200,后者为1/640。对ALV无交叉反应。     

Whole-cell antigens of members of the sulfate-reducing genus Desulfovibrio

Antisera have been developed against the wholecell antigens of Desulfovibrio africanus Benghazi and Walvis Bay, D. vulgaris Hildenborough, D. salexigens British Guiana, D. gigas, and D. desulfuricans Essex 6. An enzymelinked immunoadsorption assay (ELISA) was developed to measure the reaction of these antisera with the homologous and heterologous antigens. The ELISA method demonstrated a reaction between pre-immune sera and cells of D. africanus, D. gigas and D. desulfuricans, suggesting the presence of a lectin-like substance on these cell surfaces. Extensive cross-reactions were seen between the antisera and heterologous cells, suggesting the sharing of a number of surface antigens amongst the Desulfovibrio. However, the pattern of these cross-reactions was different from that observed for an ELISA reaction developed for the cytochrome c₃ from various Desulfovibrio.Abbreviation ELISA enzyme-linked immunoadsorption assay     

Cellobiose metabolism in Erwinia: genetic study

Summary The study of mutants of Erwinia specifically unable to ferment cellobiose indicates that the mutations are clustered between arg and ile on the chromosome of this organism. In vivo cloning of the genes responsible for cellobiose utilization lead to a plasmid, pBEC2, which complements all Erwinia Clb^- specific mutants. When introduced into wild-type E. coli it allows this organism to use cellobiose, arbutin and salicin; it also complements bglB and bglC mutants of Escherichia coli indicating that arbutin and salicin utilization is due to the products of the pBEC2 cloned genes. From the characterization of mutants pleiotropically affected in the utilization of various carbon sources, including cellobiose, arbutin and salicin, it is proposed that the three--glucosides are substrates of the phosphoenolpyruvate-dependent phosphotransferase system (PTS).     

Identification of the dye gene product, mutational loss of which alters envelope protein composition and also affects sex factor F expression in Escherichia coli K-12

Summary The product of the dye gene of Escherichia coli, mapping at 99–100 min, is required for expression of the sex factor F, and also appears to be involved in the regulation of envelope proteins. Mutation of dye thus results in loss of expression of the F-factor (Fex^–, i.e. male sterility, and dye sensitivity (Dye^s). We have isolated a plasmid, pRB38, in which a 6 kb SalI fragment carrying the dye ⁺ gene was cloned into the plasmid pACYC184. This 6 kb SalI fragment also carries two nearby markers, chlG, involved in the synthesis of the molybdenum cofactor, and phoM, required for constitutive expression of alkaline phosphatase.Some of the polypeptides synthesised by pRB38 were identified using the maxi-cell procedure. The product of the dye gene was found to be a polypeptide of M_r=29,000. Thus derivatives of pRB38 in which the transposon was inserted into dye, resulting in a Dye^S Fex^– phenotype when these plasmids were in a dye strain, failed to produce this polypeptide and in some cases produced a truncated product. Such insertions also resulted in a Chl^r and Pho^– phenotype when the plasmid was in a (dye-chlG-phoM) phoR strain, although complementation tests suggested that the phoM ⁺ and chlG ⁺ genes were still intact. Insertions of into the promoter distal end of dye did not result in a Dye^S Fex^– phenotype, although a truncated Dye protein was synthesised, and a Chl^r Pho^– phenotype was produced.It has been suggested (Gaffney et al. 1983) that the dye (=sfrA) gene product is necessary for F-factor expression because it is required for translocation of the F-factor TraJ protein to the outer membrane. Our results suggest that the Dye protein is also required for expression of the molybdenum cofactor and of alkaline phosphatase, and could perhaps be involved in the translocation of these proteins to the membrane.     

A proton-deuterium exchange study of three types ofDesulfovibrio hydrogenases

Summary Hydrogenases are among the main enzymes involved in bacterial anaerobic corrosion of metals. The study of their mode of action is important for a full comprehension of this phenomenon. The three types ofDesulfovibrio hydrogenases [(Fe), (NiFe), (NiFeSe)] present different patterns in the pH dependence of their activity. The periplasmic enzyme fromDesulfovibrio salexigens and the cytoplasmic enzyme fromDesulfovibrio baculatus both have pH optima at 7.5 for H₂ uptake and 4.0 for H₂ evolution and H⁺–D₂ exchange reaction (measured by membrane-inlet mass-spectrometry). The H₂ to HD ratio at pH above 5.0 is higher than 1.0. The periplasmic hydrogenase fromD. gigas presents the same pH optimum (8.0) for the H⁺–D₂ exchange as for H₂ consumption. In contrast, the enzyme fromD. vulgaris has the highest activity in H₂ production and in the exchange at pH 5.0. Both hydrogenases have a H₂-to-HD ratio below 1.0.     

The relationship between hydrogen metabolism,sulfate reduction and nitrogen fixation in sulfate reducers

Summary Hydrogenase and nitrogenase activities of sulfate-reducing bacteria allow their adaptation to different nutritional habits even under adverse conditions. These exceptional capabilities of adaptation are important factors in the understanding of their predominant role in problems related to anaerobic metal corrosion. Although the D₂–H⁺ exchange reaction indicated thatDesulfovibrio desulfuricans strain Berre-Sol andDesulfovibrio gigas hydrogenases were reversible, the predominant activity in vivo was hydrogen uptake. Hydrogen production was restricted to some particular conditions such as sulfate or nitrogen starvation. Under diazotrophic conditions, a transient hydrogen evolution was followed by uptake when dinitrogen was effectively fixed. In contrast, hydrogen evolution proceeded when acetylene was substituted as the nitrogenase substrate. Hydrogen can thus serve as an electron donor in sulfate reduction and nitrogen metabolism.     

An interpretation of Fujita's frequency diagrams in phyllotaxis

Fujita's diagrams in phyllotaxis, showing the frequencies of divergence angles as a function of these angles for low phyllotactic patterns such as (2, 1) and (3, 2), which are approximately normal curves centered at the limitdivergence angle of 137.51°, are shown to be puzzling when compared to results and observations in the field. An analysis of these diagrams is proposed, in the context of Fujita's methodology, of data from other sources, of a mathematical theorem on lattices, and of the contact pressure theory of phyllotaxis.     

A reinvestigation of the Gn-RH (gonadotrophin-releasing hormone) systems in the goldfish brain using antibodies to salmon Gn-RH

Summary The organization of Gn-RH systems in the brain of teleosts has been investigated previously by immunohistochemistry using antibodies against the mammalian decapeptide which differs from the teleostean factor. Here, we report the distribution of immunoreactive Gn-RH in the brain of goldfish using antibodies against synthetic teleost peptide.Immunoreactive structures are found along a column extending from the rostral olfactory bulbs to the pituitary stalk. Cell bodies are observed within the olfactory nerves and bulbs, along the ventromedial telencephalon, the ventrolateral preoptic area and the latero-basal hypothalamus. Large perikarya are detected in the dorsal midbrain tegmentum, immediately caudal to the posterior commissure. A prominent pathway was traced from the cells located in the olfactory nerves through the medial olfactory tract and along all the perikarya described above to the pituitary stalk. In the pituitary, projections are restricted to the proximal pars distalis. A second immunoreactive pathway ascends more dorsally in the telencephalon and arches to the periventricular regions of the diencephalon. Part of this pathway forms a periventricular network in the dorsal and posterior hypothalamus, whereas other projections continue caudally to the medulla oblongata and the spinal cord. Lesions of the ventral preoptic area demonstrate that most of the fibers detected in the pituitary originate from the preoptic region.     

The disappearance of isocitrate lyase from the green alga Chlorella fusca studied by immunoprecipitation

When acetate-adapted cultures of Chlorella fusca were transferred to nitrogen-free medium containing glucose, isocitrate lyase activity was lost over a period of about 25 h. Using a combination of in vivo isotope labelling and immunoprecipitation with anti-isocitrate lyase IgG it was shown that: 1. The onset of loss of enzyme activity preceeded the complete cessation of enzyme synthesis. 2. Disappearance of isocitrate lyase activity was accompanied by loss of enzyme protein, without accumulation of antigenic protein distinguishable from the normal subunit polypeptide of the enzyme, as judged by SDS gel electrophoresis of immunoprecipitated samples from supernatant cell-free extracts. 3. SDS gel electrophoresis of immunoprecipitated isocitrate lyase revealed the presence of antigenic protein bands of M_r about twice that of the normal subunit polypeptide, but the appearance of these apparent dimer forms did not obviously correlate with enzyme degradation. 4. Isoelectric focusing of immunoprecipitated isocitrate lyase showed that the enzyme became progressively more oxidised during the period of its degradation in vivo. 5. By titrating crude broken cell suspensions with anti-isocitrate lyase antibody, preliminary evidence was obtained for transfer of the enzyme from the soluble fraction to an insoluble form as part of the process of disappearance.     

Laryngeal papillomas: local cellular immune response,keratinization and viral antigen

Virchows Archiv B Cell Pathology - Various parameters of the local cellular response have been studied in 16 laryngeal papillomas from ten patients with recurrent papillomas as well as normal...