Biochemische Untersuchungen über Bakteriensporen

Ohne Zusammenfassung     

Influence of thioacetamide-provoked liver injury on female rat blood and alveolar bone under stress

Experimental liver injury with different stages was induced to adult female test rats with daily injection of thioacetamide (ThAA). The doses administered intraperitoneally were 50 mg/kg body weight. In the liver sections progressive changes of damage, regeneration and fat substitution were noticed. Kidney sections revealed enhanced glomerular atrophy, particularly in the cortical tubules, provoked in the 3-week traumatization period. The influence of ThAA on female rat blood was assayed using standard biochemical methods. The analyses done were: the percentage of blood obtainable and the serum/blood ratio; the serum alanine transferase; serum alkaline phosphatase; serum creatinine; serum hydroxyproline and serum beta-glucuronidase activity in the acute, subacute, chronic and highly chronic stage of liver injury. The biochemical findings show continuously progressing damages when traumatization proceeds. In the 3-week test period the histological findings processed showed an increase in osteoclastic resorption in the alveolar bone around the occlusally stressed tooth simultaneously with a horizontal bone loss. Some indications of recovering incidents were seen, too. Only in the histological findings was no difference seen in the deterioration between both sexes, contrarily to the biochemical results also discussed in this study.     

Ca2+-induced lateral phase separation in phosphatidic acid/phosphatidylcholine monolayers as revealed by fluorescence microscopy

Phase separation in mixed monolayers of phosphatidylcholine (PC) and pyrene-labeled phosphatidic acid (PA) was observed by fluorescence microscopy on an air/water interface as a function of subphase Ca2+ concentration and lateral packing pressure of the film. Below 45 mN m-1 and in the absence of Ca2+ no indications of phase immiscibility were observed. Addition of 1 mM Ca2+ caused extensive phase separation, which was evident immediately after spreading of the film. Further increase in Ca2+ concentration up to 30 mM increased the pyrene excimer intensity of the separated phosphatidic acid enriched domains. In the presence of Ca2+ (1-30 mM) and at surface pressures below 10 mN m-1 phase separation was always evident. However, as surface pressure exceeded 10 mN m-1, mixing of PC and PA occurred. Upon decompression of the film, phase separation reappeared at surface pressures close to 10 mN m-1. The surface textures of the film before and after the compression and subsequent relaxation were different. Inclusion of 30 mol% cholesterol increased the number and decreased the size of the PA domains. In films containing 50 mol% cholesterol no phase separation could be detected at the resolution available.     

The Effect of Prevention of Flowering on the Vegetative Growth of Inoculated Pea Plants

The removal of the apical buds from the top of inoculated pea ptants before flowering caused the axillary buds of the stem leaves to develop and thus further to branch. The vegetative growth of the test plants continued to be luxuriant when blooming was delayed. While the control ptants formed seeds and ripined. the vegetative growth of the stem of the test ptants increased at most eight-fold during the same time. A new, additional red part grew at the same time in the root nodules, which had already partly become green. The new red part branched later so that the imusuatty large nodules appeared quite odd. The weight of the branched, large nodules had at the same time increased on the average six-fold and the vegetatively grown test plants synthesized even eight times more nitrogen than did the control plants. The concentration of teghaemoglobin in the nodules formed by the bacterial strain used in the experiment was not inereased, but the absolute amount of the pigment was raised six-fold as a result of the increased nodule mass. While the vegetative growth was going on, oxidation of the leghaemoglobin was delayed. Analyses of nitrogen and amino acids were made for both test and control plants. The total length of the branches in the largest test plant was 32 m compared with the unbranched control plant which was 1.30 m.     

Intermediate filament proteins and epithelial differentiation in the embryonic ovary of the rat

Abstract. The development and sexual differentiation of gonads in female rat embryos and fetuses between the ages of 11 and 17 days was studied by immunocytochemical analysis of intermediate filament proteins and laminin by light and electron microscopy. In the 11-day-old pregonadal embryo, the surface epithelial cells in the ventral cortex of the mesonephros contained desmin but not cytokeratin or vimentin. The development of the gonad began on the following day by proliferative growth of the mesonephric surface cells, which like the subepithelial cells soon expressed vimentin in addition to desmin. The differentiation continued by formation of separate epithelial cell clusters, which joined into cords, irregular in shape and size. Desmin disappeared from the cord cells and cytokeratins appeared while vimentin remained in all somatic cell types. Desmin was especially abundant in some stromal cells adjacent to the epithelial tissues. After the segration of the basic ovarian tissues, vimentin and desmin decreased and cytokeratins appeared in the surface epithelial cells. New changes in cytokeratin expression appeared with the differentiation of the embryonic cords in a sex-specific manner with gradual decrease of reactivity for cytokeratin 18. No immunoreaction to the neurofilament proteins was found at the present ages, and the germ cells were negative for intermediate filaments. The results show that desmin is expressed in several primitive ovarian and mesonephric cells even though they are not myogenic. The sexual differences emerge after the incipient formation of the genetically female gonad, as different organization of the internal epithelial tissue with different timing of changes in intermediate filament proteins when compared with the male gonad.     

Identification of the active site of poly(A)-specific ribonuclease by site-directed mutagenesis and Fe(2+)-mediated cleavage.

Poly(A)-specific ribonuclease (PARN) is the only mammalian exoribonuclease characterized thus far with high specificity for degrading the mRNA poly(A) tail. PARN belongs to the RNase D family of nucleases, a family characterized by the presence of four conserved acidic amino acid residues. Here, we show by site-directed mutagenesis that these residues of human PARN, i.e. Asp(28), Glu(30), Asp(292), and Asp(382), are essential for catalysis but are not required for stabilization of the PARN x RNA substrate complex. We have used iron(II)-induced hydroxyl radical cleavage to map Fe(2+) binding sites in PARN. Two Fe(2+) binding sites were identified, and three of the conserved acidic amino acid residues were important for Fe(2+) binding at these sites. Furthermore, we show that the apparent dissociation constant ((app)K(d)) values for Fe(2+) binding at both sites were affected in PARN polypeptides in which the conserved acidic amino acid residues were substituted to alanine. This suggests that these residues coordinate divalent metal ions. We conclude that the four conserved acidic amino acids are essential residues of the PARN active site and that the active site of PARN functionally and structurally resembles the active site for 3'-exonuclease domain of Escherichia coli DNA polymerase I.     

Immuno-electron-microscopic localization of types III pN-collagen and IV collagen,laminin and tenascin in developing and adult human spleen

The distribution of the extracellular matrix proteins types III pN-collagen and IV collagen, laminin and tenascin was investigated in fetal, infant, and adult human spleens by using immuno-electron microscopy. The presence of type III pN-collagen was assessed by using an antibody against the aminoterminal propeptide of type III procollagen. All the proteins other than type III pN-collagen were found in reticular fibers throughout development. In the white pulp of the fetus aged 16 gestational weeks, only an occasional type III pN-collagen-containing fibril was present, although type III pN-collagen was abundant in the reticular fibers of the red pulp. Conversely, in adults, most of the reticular fibers of the white pulp, but not of the red pulp, were immunoreactive for type III pN-collagen. Ring fibers, the basement membranes of venous sinuses, were well developed in both infant and adult spleens. The first signs of their formation could be seen as a discontinuous basement membrane, which was immunoreactive for type IV collagen, laminin, and tenascin in the fetus aged 20 gestational weeks. Intracytoplasmic immunoreactivity for all the proteins studied was visible in the mesenchymal cells of the fetus aged 16 gestational weeks and in the reticular cells of the older fetuses, which also showed labeling for type IV collagen and laminin in the endothelial cells. The results suggest that proteins of the extracellular matrix are produced by these stationary cells.