Heterogeneity of constitutive heterochromatin in somatic Syrian hamster chromosomes.

Syrian hamster constitutive heterochromatin was analyzed for C-band distribution and for BrU late-replication pattern. Characteristic for this species is relatively large amounts of sex-chromosome and autosomal heterochromatin. The distribution of constitutive heterochromatin was determined. The long term of the X chromosome, the whole Y, the short arms of 8 autosomal pairs, the long arm of the smallest metacentric pair, and the centromeric regions of 12 pairs stained intensely dark on C-band preparations. In contrast to the heterochromatin in the centromeric regions, the autosomal short-arm heterochromatin has an increased susceptibility to the denaturation process, as indicated by prolonged exposure to NaOH or Ba(OH)2. Such further exposure to denaturing agents results in an intense dark stain only on the sex-chromosome heterochromatin and centromeric regions of the autosomes. The BrdU late-replication pattern demonstrated that the late-replicating regions correspond to C-bands. Centromeric regions replicate late in the S phase; however, no centromeric region is among the latest replicating segments of the complement. Centromeric and noncentromeric heterochromatin are two distinct categories of constitutive heterochromatin.     

Chromosomal localization of a bovine male specific probe

The B.C.1.2. probe, a fairly repeated sequence of the bovine male genome, was located by in situ hybridization on cattle karyotype. Of a total of 711 silver grains, 139 (19.5%) clustered on chromosome Y and about 71% of the grains were located on the short arm. This Y specific bovine male probe could be useful for routine embryo sexing in connection with embryo transfer.     

Morphogenesis and pathogenesis of chronic lung diseases. XX. Effects of repeated hypersensitivity reactions upon experimental immuno-granulomas of the lung

In order to analyse the effects of repeated hypersensitivity reactions upon chronic lung lesions, lung granulomas were experimentally induced in rabbits by an intravenous injection of 1 ml of the complete Freund's adjuvant added with 10 per cent human gammaglobulin. Groups of rabbits with 14- and 21-day-granulomas were intratracheally challenged with 1.000 I.U. human gammaglobulin injected two or three times at 7-9 days interval. The responses of the lung tissue were of the Arthus type with neutrophil granulocytic accumulations and proteasic action; the intensity of cell accumulations was decreasing after the 2nd and 3rd challenge. The lesional evolution after challenge showed intra- and perigranulomatous infiltrations with alkaline-phosphatase positive lymphocytes and plasma cells. The density of the intragranulomatous reticulin network developed after the hypersensitivity reactions increased progressively and was morphometrically assessed as statistically significant. Cellular and fibrillar lesions led to the restructuring of the lung tissue.     

Profiling thimet oligopeptidase-mediated proteolysis in Arabidopsis thaliana

Protein homeostasis (proteostasis) is crucial for proper cellular function, including the production of peptides with biological functions through controlled proteolysis. Proteostasis has roles in maintenance of cellular functions and plant interactions with the environment under physiological conditions. Plant stress continues to reduce agricultural yields causing substantial economic losses; thus, it is critical to understand how plants perceive stress signals to elicit responses for survival. As previously shown in Arabidopsis thaliana, thimet oligopeptidases (TOPs) TOP1 (also referred to as organellar oligopeptidase) and TOP2 (also referred to as cytosolic oligopeptidase) are essential components in plant response to pathogens, but further characterization of TOPs and their peptide substrates is required to understand their contributions to stress perception and defense signaling. Herein, label-free peptidomics via liquid chromatography-tandem mass spectrometry was used to differentially quantify 1111 peptides, originating from 369 proteins, between the Arabidopsis Col-0 wild type and top1top2 knock-out mutant. This revealed 350 peptides as significantly more abundant in the mutant, representing accumulation of these potential TOP substrates. Ten direct substrates were validated using in vitro enzyme assays with recombinant TOPs and synthetic candidate peptides. These TOP substrates are derived from proteins involved in photosynthesis, glycolysis, protein folding, biogenesis, and antioxidant defense, implicating TOP involvement in processes aside from defense signaling. Sequence motif analysis revealed TOP cleavage preference for non-polar residues in the positions surrounding the cleavage site. Identification of these substrates provides a framework for TOP signaling networks, through which the interplay between proteolytic pathways and defense signaling can be further characterized.     

Bronchiolar pathology. IV. a morphometric analysis of the incidence and location of lesions induced in rabbits by intratracheally injected detergent solutions

An experimental model of bronchiolar lesions was elaborated. It consisted of three intratracheal administrations in rabbits of 2 ml of a 3 per cent detergent solution, pH 2.5-3; the adequate development of the process was induced when the second injection was given 48 h after the first and the third on days 5-6. The induced process evolved during three phases: a) hypertrophy with hyperfunction of Clara cells, cell beheading by apo- and merocrinia and denudation of basement membranes; b) lesions of subepithelial components, mainly of capillaries, with granulative response and restructuration of the peribronchiolar tissue, and c) tardy regenerative response of epithelial cells, sometimes with neoformation of bronchioli. The morphometric analysis of this experimental process asserted the validity of the model which led to damages involving at less 70 per cent of the bronchioli (under 200 epithelial nuclei on a circumferential section) and of the small bronchi (with 200-500 epithelia nuclei); the other small and large bronchi were never involved. The morphometric analysis also showed the relations of the intervals between injections to the lesional intensity and stereotyping.