Rhodobacter capsulatus strain BK5 possesses a membrane bound respiratory nitrate reductase rather than the periplasmic enzyme found in other strains

Rhodobacter capsulatus strain BK5 possesses a membrane bound respiratory nitrate reductase rather than the periplasmic enzyme found in other strains. The enzyme in strain BK5 is shown to be both functionally and structurally related to the nitrate reductase of Paracoccus denitrificans and Escherichia coli.Abbreviation TMAO trimethylamine-N-oxide     

Organization and nucleotide sequence of the genes for ribosomal protein S2 and elongation factor Ts in Spirulina Platensis

A 6.5 kb region from the genome of the cyanobacterium Spirulina platensis was cloned using as a probe the Escherichia coli gene for ribosomal protein S2. Sequence analysis revealed, in this region, the presence of the gene for ribosomal protein S2 and part of the gene for the elongation factor Ts (EF-Ts). The arrangement rpsB-spacer-tsf resembles that reported for E. coli. The deduced amino acid sequences of the platensis S2 and EF-Ts show significant homology with the E. coli counterparts.     

Hypothesis: A nicotine-dopamine interaction linking smoking with Parkinson's disease and tardive dyskinesia

1. Nicotine, an important pharmacological component of cigarette smoke, is known to have significant effects on central nervous system (CNS) dopaminergic function. Although acute doses of nicotine have been shown to facilitate dopamine release, recent data indicate that chronic nicotine treatment may actually decrease CNS dopamine turnover in the striatum. 2. A number of epidemiological investigations have demonstrated that individuals who are or who have been smokers are less likely to develop idiopathic Parkinson's disease (a disorder involving a deficit in nigrostriatal dopaminergic neurotransmission). In addition, there is preliminary evidence that individuals with tardive dyskinesia (a hyperkinetic movement disorder observed in some cases of chronic neuroleptic treatment and thought by some to be associated with striatal dopamine receptor supersensitivity) are more likely to be smokers. 3. A unitary hypothesis is presented, proposing that smoking in early adult life may decrease CNS catecholamine turnover, thereby protecting against free radical formation from catecholamine oxidation that in turn damages striatal neurons. These individuals are thereby "protected" from the later development of Parkinson's disease. In this hypothetical scheme, individuals who are given neuroleptics and who also are smokers may develop a greater degree of dopamine receptor supersensitivity due to combined receptor blockade by neuroleptics and a decrease in CNS dopamine turnover caused by nicotine, resulting in an increased prevalence of tardive dyskinesia in this group.     

Recovery of functional DNA inserts by electroendosmotic elution during gel electrophoresis

In contrast to all previous preparative electrophoresis apparatus which used a pump, electroendosmotic elution uses bound electrical charges at the end of the separating gel to generate a buffer flow. The electroendosmotic flow increased with increasing currents and decreasing buffer concentrations: its exact characteristics for the built apparatus were determined. The electroendosmotic device was able to separate two DNA fragments differing in size by only 5% with a recovery over 95%. As demonstrated in practical examples of recovery and uses of DNA inserts, up to 10 micrograms of DNA per band can be loaded at a time. The recovered DNA can be used directly for nick-translation, ligation... without further treatment. The performances of the method are expected to improve still further if the charge density and pores of the electroendosmotic medium can be "made-to-order" to provide a better flow profile of the eluting buffer.     

Human sperm chromosome studies in a reciprocal translocation t(2;5)

Summary Sperm chromosome complements have been studied in a man heterozygous for a reciprocal translocation t(2;5)(p11;q15). Human sperm chromosomes were obtained after fertilization of zona-free hamster eggs. A total of 75 human sperm metaphases were analysed. Of the complements studied, 59 (78.6%) resulted from a 2:2 segregation and 16 (21.3%) from a 3:1 segregation, 4:0 segregation was not observed. Our results indicate that at least 36% of sperm complements were unbalanced with respect to the translocation. The frequency of other chromosome anomalies unrelated to the translocation was 16%.     

The altered expression of MHC-class II determinants on monocytes of cancer patients

Summary The expression of MHC class II determinants Ia.7 (detected by cross reactive mouse anti-Ia^k antibody) and HLA-DR on monocytes (MO) of gastric and colorectal cancer patients was examined. An increased proportion of MO bearing the Ia.7 determinant was found, while the number of MO expressing DR was not elevated. In gastric cancer patients the increased expression of the Ia.7 determinant was most pronounced in advanced cancer (stage IVA and IVB). The increased expression of this determinant was related to the presence of the tumour as the number of MO expressing Ia.7 decreased 6 months following surgical resection of the tumour. Further, the increased expression of Ia.7 on MO correlated with the tumour infiltration of the serosa. The Ia.7 determinants were mainly expressed on MO which also expressed the receptor for the Fc part of immunoglobulin. Immunostaining in cellular infiltrates surrounding the tumour revealed that Ia.7⁺ macrophages (MØ) were more numerous than in normal gastric mucosa and severe chronic gastritis and were mostly present in close proximity to tumour cells, while DR⁺ MØ were mainly localized within the stromal tissue of the tumour and their number was not increased in cancer infiltrates. These observations indicate that the Ia.7⁺ subpopulation of MØ may be involved in the anti-tumour response of the host.     

The T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate

The murine T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate, as indicated by several independent lines of evidence. First, three out of four arsonate-reactive T cell clones tested (two I-Ad-and one I-Ak-restricted) utilized V alpha 3. Second, bulk splenic cultures enriched for arsonate/H-2d and arsonate/H-2k responsive T cells showed increased expression of V alpha 3 mRNA. Third, a V alpha 3-containing alpha chain (Ar-5: arsonate/I-Ad) transferred arsonate responsiveness to an appropriate recipient T cell (O3: ovalbumin/I-Ad). Fourth, an independently derived V alpha 3-expressing T cell clone (2C: alloreactive to Ld) showed a response to arsonate/Ld. Thus, a V alpha 3 gene segment, in conjunction with at least two different J alpha segments (J alpha 20'(Ar-5) and J alpha pHDS58(2C)) and at least three different beta chains (V beta 2(Ar-5), V beta 6(O3), and V beta 8(2C], confers reactivity to arsonate in association with at least three different MHC proteins (I-Ad, I-Ak, and Ld). We suggest that V alpha 3 encodes a protein sequence with a binding site for the arsonate hapten.     

Selective solubilization of xylan in pulp using a purified xylanase fromTrichoderma harzianum

Summary The specificity of action of a cellulase-free xylanase preparation on pulp fibers was revealed by the composition of the solubilized products after enzyme treatment. The neutral carbohydrates released by the treatment of two hardwood kraft pulps were composed exclusively of xylooligomers. A similar treatment of Solka Floc showed no detrimental effect on the degree of polymerization of the cellulose fibers, as determined by size exclusion chromatographic analysis.     

Revision of the Brazilian species of the genus Halipegus Looss, 1899 (Trematoda: Derogenidae)

Halipegus dubius Klein, 1905 is redescribed and illustrated from a Brazilian frog Leptodactylus ocellatus. The type-material of Halipegus genarchella (Travassos, Artigas & Pereira, 1928) and Halipegus parva (Travassos, Artigas & Pereira, 1928) are redescribed with original figures. New synonyms are proposed: Halipegus salmini Yamaguti, 1958 is considered a synonym of H. genarchella, H. tropicus (Manter, 1936) sensu Kloss (1966) of H. parva and Genarchella lenti Fábio, 1984 of H. overstreeti (Brooks, Mayes & Thorson, 1979) n. comb.