Genetic diversity of a natural population of Sinorhizobium meliloti, detected during analysis of a cryptic plasmid and ISRm2011-2 fingerprints]

Fifty-six natural strains of alfalfa nodule bacteria were isolated from samples of the soil under wild legume and alfalfa in two different field sites of Irkutsk oblast. Based on the results of analysis of plasmid profile, 11 different types of strains were detected, and 43 types were identified based on the results of hybridization with the insertion sequence element ISRm2011-2. Significant differences were found in the plasmid profile and IS fingerprints between strains isolated from the soil under alfalfa and the soil under legume. In contrast, strains growing at some distance from each other differed only in the IS fingerprints. From a comparison of results obtained in the assessment of plasmid profile and in analysis of IS fingerprints with results of RFLP analysis in strains, the conclusion about the transference of cryptic plasmids between strains and genetic rearrangements in strains of this population was drawn.     

Fluorescence of meso-tetrakis(4-(carboxy)phenyl)porphine covalently bound to oligonucleotides d(CG)5 and d(TA)5

The amino-reactive derivative of tetraphenylporphine meso-tetrakis[4-(carboxy)phenyl]porphine (TCPP) was synthesized, which is characterized by a high molar absorption coefficient (epsilon 416 = 36,500 M-1.cm-1). TCPP was covalently attached to oligonucleotides d(CG)5 [d(CG)5-TCPP] and d(TA)5 [d(TA)5-TCPP]. The spectral characteristics of these complexes were studied in 0.01 M phosphate buffer, pH 7 at 23 degrees C. UV-visible absorption spectra of these complexes have a clearly pronounced Soret band at (414 +/- 1) nm for d(CG)5-TCPP and at (412 +/- 1) nm for d(TA)5-TCPP. The fluorescence spectra of these complexes have maxima at (648 +/- 2) nm for d(CG)5-TCPP and at (658 +/- 2) nm for d(TA)5-TCPP. In this study we also determined fluorescence quantum yields q and fluorescence lifetimes tau [q = 0.099 +/- 0.011, tau = (9.0 +/- 0.3) ns for d(CG)5-TCPP and q = 0.080 +/- 0.011, tau = (8.7 +/- 0.3) ns for d(TA)5-TCPP]. A temperature rise from 5 to 50 degrees C produced only slight (within 23%) emission changes in both samples studied. Taking into account: a) high fluorescence yields (q), b) weak dependence of q on temperature, c) weak q dependence of q on the oligonucleotide type, we conclude that TCPP may be used as a sensitive fluorescence label in DNA studies.     

Genetics of partial trisomies. I. Trisomy 2q

The family, where 2 children had partial trisomy 2q33-q ter, due to paternal translocation t(2;18) (q33;p11.1), was examined. The analysis of 36 cases of trisomy 2q showed that the forms connected with parental chromosomal rearrangement prevailed in the genesis of trisomy 2q. Moreover, the balanced carrier-mothers were more common than fathers. The 2q34-q ter segment may be considered "critical" for occurrence of trisomy 2q syndrome. In case of equal triplication, the similarity between the patients within the same family is greater than between those from different families. The value of intragroup similarity between the patients with equal trisomies may be used for evaluation of phenotypical similarity at different triplicated segments.     

Trisomy for distal segments of the long arm of chromosome 1

Clinical genetic analysis of distal trisomies 1q, based on the study of a t(1; 6) (q42.1; p24) family and the literature data, was performed. It was demonstrated that phenotypical manifestations of the trisomy are formed by nonspecific anomalies, due to imbalance as such, and by rather specific anomalies caused by triplication of a "critical segment". 1q42-1qter appeared to be such a segment for distal trisomy 1q.     

Genetics of partial trisomies. Trisomy 4p

Phenotypic picture for two cytogenetically different variants of trisomy 4p (with and without involvement of the proximal part of 4q) obtained on the data of Minsk Teratologic Center and on the review of 64 cases from the world literature is presented. Mathematical evaluation of intrapair, within- and interfamilial similarity, depending on a duplicated segment, is given. It is shown that phenotypic similarity among patients in case of duplicated distal segments 4p15(16)----pter is significantly greater, while as the size of trisomic segment increases, the similarity goes down. Significant excess of within- over interfamilial similarity is shown, the fact that may be ascribed to a greater similarity of the genofonds in the group of relatives.     

Cerebellar neurones: Differentiation and modulation of sensitivity to excitotoxic treatment

The neurite outgrowth and adhesion complex (NOAC), isolated from rabbit sera has been dissociated in its major components by reverse-phase chromatography in HPLC by using a C₁₈ column. SDS-PAGE analisys of the active fractions revealed the presence of three major bands of approximately 100, 70 and 50 kDa. Studies on the biological activity of NOAC were carried out on rat cerebellar granule cells. NOAC-cultured cells exhibit a marked resistance to excitotoxic stimuli carried by glutamate.     

Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.      

Interactions of Photobleaching and Inorganic Nutrients in Determining Bacterial Growth on Colored Dissolved Organic Carbon

Abstract Bacteria are key organisms in the processing of dissolved organic carbon (DOC) in aquatic ecosystems. Their growth depends on both organic substrates and inorganic nutrients. The importance of allochthonous DOC, usually highly colored, as bacterial substrate can be modified by photobleaching. In this study, we examined how colored DOC (CDOC) photobleaching, and phosphorus (P) and nitrogen (N) availability, affect bacterial growth. Five experiments were conducted, manipulating nutrients (P and N) and sunlight exposure. In almost every case, nutrient additions had a significant, positive effect on bacterial abundance, production, and growth efficiency. Sunlight exposure (CDOC photobleaching) had a significant, positive effect on bacterial abundance and growth efficiency. We also found a significant, positive interaction between these two factors. Thus, bacterial use of CDOC was accelerated under sunlight exposure and enhanced P and N concentrations. In addition, the accumulation of cells in sunlight treatments was dependent on nutrient availability. More photobleached substrate was converted into bacterial cells in P- and N-enriched treatments. These results suggest nutrient availability may affect the biologically-mediated fate (new biomass vs respiration) of CDOC.     

Preparation and characteristics of protoplasts of Streptomyces kanamyceticus

To prepare actively regenerating protoplasts of S. kanamyceticus, the influence of the conditions of the mycelium cultivation, the culture age, lytic conditions, composition of the regeneration medium, the procedure of the culture inoculation to the regeneration medium and other parameters were studied. The study resulted in development of optimal conditions for preparation of S. kanamyceticus protoplasts in a number of 1.10(9) protoplasts per ml. The cultivation on the ST medium with 10 to 15% sucrose and addition of glycine up to 1% for 30 hours (the stationary growth phase) followed by treatment of the culture with lysozyme in an amount of 2 mg/ml for 1 hour at 32 degrees C provided preparation of up to 100% of actively regenerating protoplasts free of mycelium fragments. The size of the protoplasts increased up to 1.5 micron against the usually observed size of 0.7 to 1.0 micron with using modified lyzing buffer with 20% of sucrose according to the method recommended for S. erythreus. However, 50 to 70% of the protoplasts had point of linear regions in the cell walls, which suggested that spheroplasts were mainly forming and the phenomenon was associated with the characteristic properties of the strain cell wall structure.