Studies on senescing tobacco leaf disks with special reference to peroxidase

Summary Senescing tobacco leaf disks were treated with hydroxyproline (hypro). Chlorophyll breakdown and -amino-nitrogen increase were partially inhibited, but the decrease in soluble protein was stimulated. The normal increase in absolute acid-phosphatase activity was reversed, but the increase in peroxidase activity occurred although after a lag phase. Kinetin inhibition of senescence was reversed by hypro and kinetin actually reinforced the effects of hypro. Proline only partially overcame the effects of hypro plus kinetin. In the presence of kinetin, proline considerably stimulated the increase in peroxidase activity.Discussed are the way in which hypro may be acting, and the possibility of peroxidase being involved in proline hydroxylation.     

Studies on mammalian intestinal peroxidase.

A peroxidase, purified from rat small intestine to apparent homogeneity as judged by polyacrylamide-gel electrophoresis, exhibited an absorbance ratio (A412/A280) of 0.783. Its Mr (44000 +/- 1000) and spectral properties were similar to those of the pig intestinal enzyme. The velocity constant for the reaction between rat intestinal peroxidase and hydrogen peroxide was found to be 1.8 x 10(7) M-1 . s-1. Benzhydroxamic acid inhibited the peroxidative oxidation of guaiacol by intestinal peroxidase from both species but the concentration required to cause half-inhibition of the enzyme from the rat was higher by one order of magnitude than for the pig enzyme. The amino acid composition of highly-purified pig intestinal peroxidase showed a relative abundance of basic amino acids (lysine and arginine) and was similar to that of lactoperoxidase, but not that of myeloperoxidase. The initial ten amino acid residues of this enzyme (the first reported partial sequence for a mammalian peroxidase) were also determined.     

The embryonic development of the intestinal mucosa with special reference to its epithelium

Electron microscopic examinations were made of different parts of the bovine intestine (n = 13) up to the 10th week of embryonic development. During the 'phase of undifferentiated epithelium' the embryonic intestinal epithelium can be classified as stratified and is perhaps a pool of cells. Microvilli of the apical plasmalemma appear at first in neighboring and opposing cells in the centre of the epithelium. They already show microfilaments as well as a glycocalix. The supranuclear cytoplasm shows many granules, vesicles and arciform structures which may be used in the process of microvilli formation. The importance of infranuclear basal granules in the peripheral epithelial cells is still unknown; perhaps they are merely phylogenetic remnants of a principle of development common to all vertebrate intestines. Single cilia which are formed in the periluminal cytoplasm presumably suppress mitotic activities of the epithelial cells and induce their ensuing differentiation. Epithelial proliferation is the initial event of villigenesis, giving rise to epithelial primary villi. Immediately following is the formation of secondary villi during proliferation of the mesenchyme.     

Studies on mycobacteria isolated from animals, with special reference to the agglutination test

Ninety-three strains of slowly-growing mycobacteria were studied biochemically. Ninety of these were isolated from animals (pigs, cattle, dog and poultry) and three from dust and sawdust-bedding in a pighouse. One strain from a lymph node of a pig was identified as M. gordonae. Ninety-two strains fitted into the M. aviam-intracellulare complex. Of the 92 biochemically confirmed M. avium-intracellulare strains, 78 were tested serologically ad modum Schaefer. Of 73 strains from pigs, one was serotype 1, fifty serotype 2 and eight serotype 8, while two could not be type and twelve were autoagglutinable. Three strains from pighouse environment were serotype 8 and two from cattle and a dog were both serotype 2. A slight modification of Schaefer's agglutination method, using smaller amounts of antigen and antiserum, was developed.     

Characterization of mammalian heart annexins with special reference to CaBP33 (annexin V)

Porcine heart was observed to express annexins V (CaBP33) and VI in large amounts, and annexins III and IV in much smaller amounts. Annexin V (CaBP33) in porcine heart was examined in detail by immunochemistry. Homogenization and further processing of heart in the presence of EGTA resulted in the recovery of annexin V (CaBP33) in the cytosolic fraction and in an EGTA-resistant, Triton X-100-soluble fraction from cardiac membranes. Including Ca2+ in the homogenization medium resulted in a significant decrease in the annexin V (CaBP33) content of the cytosolic fraction with concomitant increase in the content of this protein in myofibrils, mitochrondria, the sarcoplasmic reticulum and the sarcolemma. The amount of annexin V (CaBP33) in each of these subfractions depended on the free Ca2+ concentration in the homogenizing medium. At the lowest free Ca2+ concentration tested, 0.8 microM, only the sarcolemma appeared to contain bound annexin V (CaBP33). Membrane-bound annexins V (CaBP33) and VI partitioned in two fractions, one EGTA-resistant and Triton X-100-extractable, and one Triton X-100-resistant and EGTA-extractable. Altogether, these data suggest that annexins V and VI are involved in the regulation of membrane-related processes.     

Systematics of theLactobacillus population on rat intestinal mucosa with special reference toLactobacillus reuteri

The systematics of theLactobacillus population of the intestines of 88 different rats was studied; 80 rats had been fed on fermented oat-meal soup (Molin et al. 1992). One-hundred-twenty-twoLactobacillus strains from the intestinal mucosa were phenotypically classified together with twenty-eight reference strains ofLactobacillus andLeuconostoc, using 49 unit characters. Data were examined using Jaccard coefficient, and unweighted pair group algorithm with arithmetic averages. Two major and eleven minor clusters were defined at the 76% S_J-similarity level: Cluster 1 included thirty isolates which could not be identified further, but had resemblance to the type strains ofL. jensenii, L. gasseri, L. crispatus, and to some extent toL. acidophilus. Cluster 12 including fifty-four intestinal isolates was identified asL. reuteri; and so was cluster 13 (five isolates). Isolates of the major clusters were found in all parts of the intestines. The genomic homogeneity of theL. reuteri isolates was scrutinized by endonuclease restriction analysis of the chromosomal DNA, and the isolates could be divided into six genomic strains.