Analysis of the env gene of a molecularly cloned and biologically active Moloney mink cell focus-forming proviral DNA.

A biologically active molecular clone of BALB/Moloney mink cell focus-forming (Mo-MCF) proviral DNA has been reconstructed in vitro. It contains the 5' half of BALB/Moloney murine leukemia virus (Mo-MuLV) DNA and the 3' half of BALB/Mo-MCF DNA. The complete nucleotide sequence of the env gene and the 3' long terminal repeat (LTR) of the cloned Mo-MCF DNA has been determined and compared with the sequence of the corresponding region of parental Mo-MuLV DNA. The substitution in the Mo-MCF DNA encompasses 1,159 base pairs, beginning in the carboxyl terminus of the pol gene and extending to the middle of the env gene. The Mo-MCF env gene product is predicted to be 29 amino acids shorter than the parental Mo-MuLV env gene product. The portion of the env gene encoding the p15E peptide is identical in both viral DNAs. There is an additional A residue in the Mo-MCF viral DNA in a region just preceding the 3' LTR. The nucleotide sequence of the 3' LTR of Mo-MCF DNA is similar to that of the 5' LTR of BALB/Mo-MuLV DNA with the exception of two single base substitutions. We conclude that the sequence substitution in the env gene is responsible for the dual-tropic properties of Mo-MCF viruses.     

Surface layers ofXanthomonas malvacearum,the cause of bacterial blight of cotton

Mureins were isolated from two strains ofXanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70–95 % and the amino acid and amino sugar components (glutamic acid, alanine, meso-diaminopimelic acid, muramio acid and glucosamine) were present at the molar ratio of 1: 1.9: 1: 1.12: 0.85. The bacterium secreted a copious amount of slime which masked its surface structure. The slime was composed of densely interwoven network of filamentous material originating from the cell surface and extended into the medium without any discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formation of bacterial cells.     

Oral D2O administration and enzymatic changes in rat testis.

Heavy water caused marked gradual decrease in the weight of the body as well as the testes throughout the treatment interval ranging from 1 to 6 weeks. Following D2O oral administration, an overall significant fall in the activity of acid phosphatase and glucose-6-phosphatase was registered. On the other hand, the activity of lactic and succinic dehydrogenases, alkaline phosphatase and adenosine triphosphatase increases following D2O treatment. These changes in the enzyme activity are suggestive of an altered metabolism of the testes in response to D2O administration. Our data corroborate the view that biological systems do discriminate between H2 and D2.     

Anomalous side chain amidation in plasma membrane proteins of simian virus 40-transformed lymphocytes indicated by isoelectric focussing and laser Raman spectroscopy.

Plasma membranes isolated from normal hamster lymphocytes and lymphoid cells transformed by SV40¹ have been compared. Isoelectric focussing in 1% Triton $\text{X-100}\text{8M}$ urea reveals higher isoelectric points than normal for the non-glycosylated proteins in the membranes of transformed cells. This suggests greater amidation of membrane aspartates and/or glutamates. The focussing patterns also reveal a shift to lower pH for the isoelectric points of most glycosylated proteins suggesting increased silalylation. The Amide I – Amide II laser Raman spectra of the two membrane categories are consistent with greater side chain amidation in the membranes of neoplastic lymphocytes.     

A possible cause of non-disjunction of additional chromosome 21 in Down syndrome

Summary A possible cause of non-disjunction of chromosome 21 in Down Syndromes has been cytogenetically evaluated by examining the parents by Ag-staining technique. In all the cases studied so far, the contributing parents have active ribosomal cistrons on both chromosomes 21 i.e. both chromosomes are stained positively by silver staining. These results show that the active NORs might play an essential role in meiotic non-disjunction. Furthermore, the preliminary results demonstrate that the acrocentric associations of homologous and non-homologous nature involving chromosome 21 are the most frequent in the contributing parent which may further indicate the role of multiple cellular factors affecting the associations in promoting the non-disjunction in addition to active NORs. The possible mechanisms regarding the non-disjunction of chromosome 21 have been described.Presented at the 34th Annual Meeting of the American Society of Human Genetics, Norfolk, VA, USA