A case of trisomy 22 in Pongo pygmaeus.

A behaviorally and clinically abnormal female orangutan was analyzed cytologically using general banding techniques and by an alkaline silver method for staining nucleolus organizer regions. The karyotype had 49 chromosomes, including an extra chromosome 22 (49,XX + 22). No variant chromosome types or heterozygous structural rearrangements were found. Nine of the 14 large acrocentric chromosomes, Nos. 11--17, and three of the five presumptive human G-group equivalents, i.e., two of three chromosomes 22, and one chromosome from pair 23, exhibited positive silver staining of the nucleolus organizer region (NOR).     

Characterization of immunologically active peptides from the cell wall of T.mentagrophytes

A low molecular weight fraction from chitinase digested cell walls ofT. mentagrophytes containing both polysaccharide and peptide moieties was found to have immunological reactivity at both the cellular and humoral level. This fraction (UM₂(a)) was further degraded by treatment with either a combination of pronase and carboxypeptidase A or with trypsin. Peptides were separated from the carbohydrate-rich fraction by ultrafiltration. The carbohydrate-rich fraction retained the ability to induce both immediate and delayed skin reactions in sensitized guinea pigs and to stimulate the proliferation of sensitized lymphocytesin vitro. The peptide moieties retained reactivity in that they caused delayed reactions and lymphocyte proliferation but were unable to induce immediate or Arthus reactions in sensitized animals. Tryptic peptides from UM₂(a) were purified by ion exchange chromatography. A high proportion of these peptides demonstrated immunological activity at both the cellular and humoral level since they were capable of inducing delayed reactions and/or lymphocyte transformation, as well as being capable of blocking the complement fixation reaction between UM₂ (a) and specific antiserum.This work was supported by grant number 6411 from the Medical Research Council of Canada.A. Kh. Al-Rammahy was supported by a scholarship from the Ministry of High Education, Iraq.     

Analysis of nucleolus organizer regions (NORs) in mitotic and polytene chromosomes ofPhaseolus coccineus by silver staining and Giemsa C-banding

Chromosomes with active nucleolus organizer regions (NORs) were visualized in root tip metaphases ofPhaseolus coccineus using the silver staining technique. A mean number of 5.5 Ag-NORs per cell was observed in 54 cells from eight plants. In the endopolyploid nuclei of the suspensor the silver technique did not demonstrate the reported specificity for nucleolus organizer activity, because there was usually pale staining of nucleoli and preferential staining of heterochromatic regions in the polytene chromosomes including pericentromeric material, telomeres and NORs. The mean number of NORs per nucleolus as detected by this method was 5.8 (28 nucleoli analysed). Using a modified preparation technique, giant chromosomes stained pale, but nucleoli of suspensor cells displayed darkly silver staining internal domains, each of which originating from a nucleolus organizer.—Giemsa C-banding of endopolyploid suspensor nuclei revealed C-positive nucleolus organizers with darkly staining intranucleolar fibrils. The latter were frequently involved in inter-NOR associations. In 34 nucleoli analysed, the mean number of Giemsa C-positive NORs per nucleolus was 6.0.Dedicated to Professor Dr.Lothar Geitler on the occasion of his 80th birthday.     

The involvement of the anticodon adjacent modified nucleoside N-(9-(BETA-D-ribofuranosyl) purine-6-ylcarbamoyl)-threonine in the biological function of E. coli tRNAile.

tRNAile was isolated from E. coli Cp 79 (leu-, arg-, thr-, his-, thiamin-, RCrel) which had been grown on a sub-optimal concentration of thr and was found to contain an average of 50% less N-[9-(beta-D-ribofuranosyl)- purin-6-ylcarbamoyl]threonine, t6Ado, than tRNAile from cells grown on an optimum concentration of thr and containing a normal complement of t6Ado. The two tRNA's were identical in their ability to be aminoacylated, to accept the 3'-terminal dinucleotide, and to form an ile-tRNAile-Tu-GTP complex. In contrast, the t6Ado-deficient-tRNA was significantly less efficient in binding to ribosomes compared to the normal tRNA. This difference was seen in the binding of deacylated tRNA and in the nonenzymatic and enzymatic binding of ile-tRNA, all in response to poly AUC. The t6Ado-deficient ile-tRNA demonstrated no binding at Mg2+ concentrations less than or equal to 10 mM, while the normal ile-tRNA bound at low Mg2+ concentrations. Tetracycline had the same effect on the normal as on the t6Ado-deficient ile-tRNA binding. As a control, the binding of phe-tRNA (which does not contain t6Ado) from normal and thr-starved cells in response to poly U was identical. It was concluded that t6Ado is required for proper codon-anticodon interaction.