Collagen type I fibril packing in vivo and in vitro

Reviewed are works concerning the mechanisms of collagen (type I) fibril packing and the influence of macromolecular structure and physicochemical parameters of the medium on the process.     

Effects of organic fluorosilicone compounds on the development of tumors in mice

The influence of new synthesized fluoro-silicium-organic complexes on the virus-induced Rauscher leukosis and cell-transferred MX-11 mouse sarcoma was studied. We also studied the cytotoxic effects of these complexes in vitro in the human CaOv cells. Two complexes from seven studied were cytotoxic for CaOv cells. Five complexes from seven studied diminished the mortality of animals with MX-11 tumors on the 27-th day of observation, but the total life duration of the animals in the experimental group was the same as in controls. One complex from seven studied increased the life duration of mice with MX-11 tumors. No effects were noted in relation to mice virus-induced Rauscher leukosis.     

Erythrocyte antigen: isolation, biochemical and immunologic properties]

The authors suggest a simple method of obtaining erythrocytic antigen in considerable amounts. This antigen is of stromal origin, contains from 10 to 20% protein, and is relatively homogenous. With the concentration of from 1 to 50 microgram by protein the preparation represents a transparent solution; with greater concentrations the antigen is white, turbid, but is well dissolved and convenient for administration to the animals. In case of a single administration without any adjuvants the antigen is highly immunogenic in low doses by protein. To the optimal immunizing dose of erythrocytes (5 X 10(8)) correspond about 100 microgram of the antigen by protein. The primary response to the antigen is similar to the response to sheep red blood cells (SRBC). It is exceedingly effective for the formation of immunological memory. The level of secondary responses in the adoptive transfer to all the EAG doses always exceeded the secondary response to SRBC. By adding EAG into agar during the local hemolysis in gel test determined the avidity of the antibodies synthesized at various periods of the immune response to SRBC.     

The effect of picolinic acid and iron ions on the proliferation of SPEV cells

The effect of picolinic acid (PA) on SPEV cell proliferation is found to be different from that on normal and virus transformed NRC cells, and on spontaneously transformed CHO cells. It is shown that SPEV cells are arrested by PA at the end of G1-phase and at the beginning of S-phase and probably in G2-phase of the cell cycle. Ferrous ions remove the G1/S block induced by PA to permit the cell transfer through S-phase. On the one hand, PA chelates ferrous ions from the cells, and on the other one it inhibits the replicative DNA synthesis. It can be suggested that PA may arrest the SPEV cell growth affecting the iron-depend stable radical formation which is introduced into the active centre of ribonucleotiDE reduCTase. This results in the lower enzyme activity.     

Improved Dot-Blot Hybridization Assay for Large-Scale Detection of Potato Viruses in Crude Potato Tuber Extracts

Abstract A rapid and simple technique has been developed to enhance the sensitivity of virus detection in dot-blot hybridization assay by up to 1000 fold. The procedure generally follows that of B aulcombe et al. (1984) but includes moderate heating of the nitrocellulose filter in 10XSSC, 0.5% SDS solution at 55°C after sample application. Using this procedure, four potato viruses (PVX, PVS, PVM and PVY) were detected with cloned virus-specific ³²P-cDNA probes in 2 μl spots containing 0.2–2 pg of purufied virus (0.1–1 ng/ml). The procedure was also successfully applied for the detection of PVX, PVS, PVM and PVY in crude potato tuber extracts.     

Evolutionary conservation of the chromosomal configuration and regulation of amylase genes among eight species of the Drosophila melanogaster species subgroup

Nuclear DNA was extracted from each of the eight species comprising the Drosophila melanogaster species subgroup. Southern hybridization of this DNA by using a molecular probe specific for the alpha-amylase coding region showed that the duplicated structure of the amylase locus, first found in D. melanogaster, is conserved among all species of the melanogaster subgroup. Evidence is also presented for the concerted evolution of the duplicated genes within each species. In addition, it is shown that the glucose repression of amylase gene expression, which has been extensively studied in D. melanogaster, is not confined to this species but occurs in all eight members of the species subgroup. Thus, both the duplicated gene structure and the glucose repression of Drosophila amylase gene activity are stable over extended periods of evolutionary time.      

Effect of radiation on cell interactions in the phenomenon of non-syngeneic stem cell inactivation. Changes in B-lymphocyte function after irradiation

A study was made of the changes in the mode of interaction between T- and B-lymphocytes of mouse lymph nodes with respect to the phenomenon of inactivation of non-syngeneic haemopoietic stem cells. It was shown that irradiation of B-lymphocytes with doses of 77.4--232.2 mC/kg changes their helper activity into a suppressor activity with regard to T-cell-killers having a low electrophoretic mobility.     

Growth of Phytomonas serpens in a Defined Medium; Nutritional Requirements

ABSTRACT. Three strains of Phytomonas serpens two from tomatoes, Lycopersicon esculentum one from the insect Phtia picta (Hemiptera, Coreidae), were cultivated in a chemically defined medium developed from a defined medium for cultivating insect flagellates. Besides organic growth factors required by other insect trypanosomatids this flagellate requires, serine and inositol. Glutamine stimulates growth, and, surprisingly, does not require heme.     

Sequence variation in the outer-surface-protein genes of Borrelia burgdorferi

Borrelia burgdorferi is a spirochete pathogen transmitted among warm- blooded hosts by ixodid ticks. Frequency-dependent selection for variant outer-surface proteins might be expected to arise in this species, since rare variants are more likely to avoid immune surveillance in previously infected hosts. We sequenced the OspA and OspB genes of nine North American strains and compared them with nine strains previously described. For each gene, the mean number of synonymous substitutions per synonymous site and the mean number of nonsynonymous substitutions per nonsynonymous site show only a twofold excess of silent mutations. Synonymous rates vary widely along the OspB protein. Some regions show a significant excess of silent substitutions, while divergence in other regions is constrained by biased base composition or selection. The presence, in antigenically important regions of the protein, of significant variation among strains, as well as evidence for recombination among strains, should be considered in attempts to develop vaccines against this disease.      

Characterisation of a 34 kD protein from potato cyst nematodes, using monoclonal antibodies with potential for species diagnosis

Two monoclonal antibodies, which differentially recognise the two species of potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are described. They have been shown to have potential for quantification of these two species, recognising proteins of the same molecular weight (34 kD) in both species. Further investigation showed these proteins to have isoelectric points at pH values of 5.7 in G. pallida and 5.9 in G. rostochiensis, in common with the proteins used by Fleming & Marks (1983) to differentiate the species of PCN. They are likely to be structurally very similar, with the same physiological function (and therefore similar concentrations) in the two species. In cross-reactivity tests with a wide range of soil nematode species, the antibodies reacted strongly only with species of the genus Globodera, and thereby confirmed their potential as the basis of a quantitative immunoassay likely to be useful in management of PCN populations.