Transposition of the bobbed locus in Drosophila melanogaster

Due to the complete absence of ribosomal DNA (genetic symbol bb-), the Xbb- chromosome of Drosophila is lethal both in homozygous conditions and in compound with the Xbb- chromosome. However, in the cross between the C(1)RM/Ybb- females and the Xbb-/BSYbb+ males, characterized by the development of lethal Xbb-/Ybb- zygotes, two fertile males were detected. These males possessed all the markers of the Xbb- chromosome but lacked the Y chromosome BS marker. Genetic analysis of their progeny showed that genes responsible for restoration of viability and fertility of these exceptional males were associated with the X chromosome. The crossover tests showed that in one case these genes were tightly linked to the w locus (the bbAM1 allele), and in the second case they were located 12.6 map units to the right of the Tu locus (the bbAM7 allele). It has also been shown that the bb locus was transposed to the X chromosome within the short arm of Y chromosome. Transposition of the BSYbb+ chromosome-specific rDNA sequences to the X chromosome was confirmed by means of Southern blotting. These data indicate that replacement of the bb locus is realized by transposition rather than recombination.     

Synthetic peptide designs based on immunoactive fragments of the VP1 protein of the foot-and-mouth disease virus strain A22

Peptide constructs consisting of 44-53 aa were synthesized on the basis of sequences 135-159, 170-190 and 197-213 of VP1 from the foot-and-mouth disease A22 strain. Immunogenic and protective properties of the peptide constructs were studied in guinea pigs and mice of three lines. The constructs were shown to induce higher levels of antibodies and exhibit higher protective effects than the separate peptides. The most active among the peptides studied was the construct involving the VP1 fragments 135-160 and 170-190: it protected pigs from the experimental infection by the foot-and-mouth disease virus.     

Effect of pancreatic DNAse on the nuclear DNA topology of Candida tropicalis yeasts

It has been shown that pancreatic DNAase added to the nutritious medium caused the change in the nuclear DNA topology of asporogenic Candida tropicalis yeast. DNA conformative changes are due to the unwinding of supertwisted molecules as a result of single-strand ruptures formation which induce DNA synthesis acceleration, cell growth and division.     

Carbonic anhydrase of the alkaliphilic cyanobacterium Microcoleus chthonoplastes

The activity of carbonic anhydrase (CA) was studied in different cell fractions of the alkaliphilic cyanobacterium Microcoleus chthonoplastes. The activity of this enzyme was found in the soluble and membrane protein fractions, as well as in intact cells and in a thick glycocalyx layer enclosing the cyanobacterium cells. The localization of CA in glycocalyx of M. chthonoplastes was shown by the western blot analysis and by immunoelectron microscopy studies with antibodies to the thylakoid CA from Chlamydomonas reinhardtii (Cah3). At least one of the CA forms occurring in M. chthonoplastes CA was shown to be an alpha-type enzyme. A possible mechanism of the involvement of the glycocalyx CA in calcification of cyanobacteria is discussed.     

Cytogenetical approaches to the problem of form-formation and subspeciation in the complex Lacerta (Zootoca) vivipara (Lacertidae, Sauria)

Results of the author's long-term study of the karyotype of Lacerta (Zootoca) vivipara (family Lacertidae, Sauria) have been generalized and supplemented with relevant literature data. Within the species an interpopular karyotype variability was established, and several chromosomal forms were described. Karyotypes of L. (Z.) vivipara from four new, previously not examined populations have been first presented in this paper, and cytogenetical features of their chromosomes are given. Finally, cytogenetical analysis of particular specimens from different localities enabled the author to reveal a new chromosomal form and to define the limits of distribution of other forms of the species. The complex L. (Z.) vivipara has appeared to be more complicated than earlier believed. This complex includes several chromosomal forms of unclear taxonomic status, and some subspecies characterized by various modes of reproduction and distinct distribution ranges. It has been confirmed that in the complex L. (Z.) vivipara intensive chromosomal changes accompany the processes of form-formation and subspeciation. Some cytogenetical regularities of these processes have been demonstrated and compared with hybridogeneous form-formation and speciation. Based on the critical analysis of the available karyological data, some mechanisms of chromosomal changes were described, and their tendencies were determined. In addition, intraspecific relationships were analysed. The proposed scheme was compared with the pattern of intraspecific phylogeny of L. (Z.) vivipara based on molecular data. It has been shown that a high cytogenetical differentiation of the found chromosomal forms and subspecies is correlated with their low morphological differentiation and with a rather low genetical differentiation. The results of the combined analysis suggest the leading role of cytogenetical data for understanding the processes of form-formation and subspeciation. The importance of chromosomal rearrangements in these processes is emphasized, with special reference to their role in the evolution and phylogeny of the complex L. (Z.) vivipara. Some modes of form-formation and subspeciation in this complex are discussed.     

Cytotoxicity of effector cells of the peripheral blood, lymph nodes and spleen in Hodgkin's disease

The mononuclear cells and T-lymphocytes of the blood, spleen and lymph nodes from 83 patients with Hodgkin's disease and 50 healthy donors were tested in assays for lectin-dependent (LD) and natural killer (NK) cytotoxic activity (CTA). On an average, peripheral blood T cell LD-CTA of patients did not differ from that of the donors. However, the CTA appeared to be dependent on the stage of the disease; in the IVth stage LD-CTA was decreased 2-fold. The LD-CTA was also dependent on the histological type of disease and the lowest level of LD-CTA (50% of the control level) was associated with the "lymphocyte depletion" type. The CTA of T-lymphocytes from the affected areas of the patients' spleen was more marked than that of the unaffected areas. Spleen cell CTA showed no other correlations. The CTA of lymphocytes from the affected lymph nodes was drastically lower than CTA of blood and spleen lymphocytes. The NK activity of the patients' blood and spleen lymphocytes was twice as less as the control level (healthy donors) and did not correlate with a stage and/or a histological type of the disease. It was assumed that in Hodgkin's disease the specific antitumor immunity remains mostly within normal and is decreased only in the last, terminal stage of the disease.     

Effect of pancreatic DNAse on Bacillus subtilis multiplication depending on the physiological state of the culture

The effect of pancreatic DNAase on the growth of Bacillus subtilis, the synthesis of DNA, RNA and protein in the cells was studied as a function of their physiological state. The cells were found to be sensitive to the action of DNAase at the end of the linear growth phase, which coincided with their transition into the competence state and with their ability to adsorb the enzyme on the cell surface.     

Evolutionary divergence of the ribosomal internal transcribed spacer 2 (ITS2) in lizards

During the pre-rRNA cleavage pathway, the excision of ITS2, a eukaryotic specific insertion, remains the most elusive processing step, even in yeast. Comparison of the ITS2 sequences in different organisms permits to reveal conservative, presumably functionally important elements as well as obtain new information about ITS2 divergence in evolution. We have cloned and sequenced the ITS2 of three lizard species, Agama caucasia (Agamidae), Darevskia armeniaca and Lacerta strigata (Lacertidae) and detected in them a set of specific and conservative structural elements employing secondary structure consensus for vertebrate ITS2. Furthermore, we have performed an alignment and comparative analysis of the ITS2 sequences for the two lizards families. It enables us to propose that modern lizard species formation in evolution was accompanied by ITS2 duplication in the rDNA of their common progenitors.