Peptidase N of Pseudomonas aeruginosa

Abstract Pseudomonas aeruginosa possesses a peptidase N activity analogous to those described in Escherichia coli and Salmonella typhimurium . This activity resides in a protein with an M _r value of 85 000. Part of this peptidase activity appears to be associated with the cytoplasmic membrane. The K _M value for this peptidase bound to the cytoplasmic membrane is in the range of 0.5 mM.     

Chlorosphaeropsis epidemica,spec. nova,eine neue Grünalge mit endophytischer Lebensweise

The new parasitic algaChlorosphaeropsis epidemica is a member of theChlorosarcinales and lives endophytically in the leaf-tissue ofPotamogeton species. It forms stacks of cells and appears in great numbers, especially in dying leaf-blades. Sexual reproduction is described for the first time in this genus. Apart from its endophytic way of life,Chl. epidemica is characterized by mononuclear cells with a parietal chloroplast of irregular thickness and with a few perforations, sometimes of complicated reticulate shape, and with 1–5 pyrenoids. The usually sphaerical gametes (respectively zoospores) are provided with two equal flagella, a parietal plastid, one pyrenoid and one stigma. In connection with the asexual reproduction the terms vegetative division and desmoschisis are critically discussed.

     

Immunofluorescence of somatostatin-producing sites in the hypothalamus of the tadpole,Alytes obstetricans Laur.

Summary Three sites of somatostatin-synthesizing perikarya, or a related antigen, were determined by immunofluorescence in the hypothalamus of the tadpole, Alytes obstetricans (Amphibia, Anura). Two sites of neurosecretory perikarya were localized in the preoptic nuclei of the anterior hypothalamus; the axons extended either to the anterior diencephalon or to the median eminence and the pituitary. The third site was found in the posterior hypothalamus. These neurosecretory cells showed a strong immunofluorescent reaction; their axons all terminated at the level of the median eminence. Somatostatin cells were only found in intact or hypophysectomized tadpoles given somatotropin (STH). The strong reaction observed in hypophysectomized tadpoles was possibly due to the loss of the terminal portion of the neurosecretory pathway (median eminence and pituitary) by which the agent is transported to the site of discharge.     

Calcium and sulphur in neurosecretory granules and calcium in mitochondria as determined by electron microscope X-ray microanalysis

Summary Sections of neurosecretory cells fixed in glutaraldehyde and osmium tetroxide were studied by means of an EMMA-4 analytical microscope. Secretory granules in neurosecretory cells of the corpus cardiacum and of the brain, both in the desert locust Schistocerca and in the blowfly Calliphora, as well as neurosecretory granules in posterior pituitaries of the frog Rana and of the albino rat all contain a high concentration of calcium. A distinct sulphur peak was also a constant feature.In neurosecretory cells of the corpus cardiacum of Schistocerca the chromatin contained a high concentration of calcium. The mitochondria also contained much calcium, but part of this disappeared during preparation except when fixative and wash contained calcium chloride. By block staining with uranyl acetate most calcium is displaced from the mitochondria, whereas most of the calcium remains in the neurosecretory granules. Since the calcium peaks in spectra from neurosecretory granules appear of similar size, regardless of variations in the preparative procedure, this calcium must be firmly bound. The possible role of the calcium bound to the neurosecretory substance is discussed.The presence of sulphur in insect neurosecretory granules indicates the presence of a protein besides the hormone, i.e., an insect neurophysin.We wish to thank Dennis Greer for the operation of the analytical microscope. This work was supported by a Wellcome-Carlsberg Travelling Research Fellowship awarded to T.N. The EMMA-4 facility is supported by a grant from the British Science Research Council     

Prostaglandin D2, another renal prostaglandin?

Prostaglandin (PG) D₂ was biosynthesized by rabbit renal papillae incubates in vitro. Quantification of the renal prostaglandins by gas chromatography-mass spectroscopy demonstrated that the concentration of PGD₂ generated by renal papillae was to the amount of PGE₂ or about 1 μg/g tissue/30 min. Infusion of the sodium salt of PGD₂ into the renal artery of the dog produced a dose related increase in renal blood flow and urine flow, free water clearance, sodium excretion and potassium excretion without changes in systemic hemodynamics. At low doses PGD₂ increased renal blood flow to all cortical zones. Higher concentrations of PGD₂ produced a shift in the intrarenal distribution of blood flow toward the juxtamedullary nephrons.     

Synthesis of ribonucleotides and their participation in ribonucleic acid synthesis by Coxiella burnetii.

Synthesis of ribonucleic acid (RNA) by the deoxyribonucleic acid-dependent RNA polymerase of Coxiella burnetii required adenosine, uridine, guanosine, and cytidine 5'-triphosphates. Cell-free preparations of this obligate intracellular procaryotic parasite had competence to phosphorylate ribonucleoside mono- and diphosphates in the presence of exogenous adenosine and guanosine 5'-triphosphates to the corresponding di- and triphosphates. C. burnetii contained about 2 nmol of adenosine 5'-triphosphate per mg of protein, which could serve as a approximately P donor for in vivo synthesis of nucleoside triphosphates. The latter were then used as substrates in the synthesis of RNA in a coordinated metabolic system with C. burnetii RNA polymerase. It is suggested that during infection the rickettsiae might obtain the nucleotides necessary for RNA synthesis from the vacuoles in which C. burnetii proliferates.     

Membrane fluidity in normal and cystic fibrosis fibroblasts

We have observed distinct differences in the polarization of fluorescence and temperature dependent emission intensity of the highly fluorescent phospholipid derivative (1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)--aminocaproyl phosphatidylcholine (NBD-PC), when incorporated in the plasma membranes of normal and cystic fibrosis fibroblasts. Fluorescence polarization measurements indicate that the fluorochrome has a much higher degree of rotational mobility in cystic fibrosis fibroblasts as compared with normal cells. Temperature dependent transitions in the emission intensity of NBD-PC incorporated in normal fibroblasts are indicated at 17.7 and 21.2° C while the abnormal cell membranes apparently undergo transitions at 8.7 and 13.5° C. These differences might be due to changes in plasma membrane composition and/or organization, in the case of the cystic fibrosis cells.     

Partial trisomy 1 due to a "shift" and probable location of the Duffy (Fy) locus.

Transposition of 1q31-1q32 from the q to p arm in a parent followed by crossing over resulted in a child with a duplication of this region. Concomitant C- and GTG-banding and genotyping were used to position the single crossover and to localize Fy to 1q2.     

Analysis of the regulation of adenosine 5′-phosphosulfate sulfotransferase activity inLemna minor L. using15N-density labeling

The role of de novo synthesis in the regulation of adenosine 5-phosphosulfate sulfotransferase activity by H₂S inLemna minor L. was investigate using density labeling with¹⁵N applied as¹⁵NO ₃ ^– in the culture medium. While adenosine 5-phosphosulfate sulfotransferase activity was rapidly reduced by H₂S and rapidly recovered upon removal of H₂S, O-acetyl-L-serine sulfhydrylase (EC 4.2.99.8) did not show changes in extractable activity in response to H₂S and could therefore be used as an internal marker enzyme for density labeling. The incorporation of¹⁵N into adenosine 5-phosphosulfate sulfotransferase was strongly reduced upon transfer of plants into a H₂S-containing atmosphere. Half-maximal labeling was reached only after 70–80 h compared to 40–50 h in the control. After removal of H₂S, adenosine 5-phosphosulfate sulfotransferase activity increased to the initial level within 20 h, and the enzyme reached halfmaximal labeling after only 15 h. The time course of the density increase of O-acetyl-L-serine sulfhydrylase was not affected very significantly by H₂S. These results provide evidence that de novo synthesis of enzyme protein is involved in the regulation of adenosine 5-phosphosulfate sulfotransferase activity by H₂S.Abbreviations APS adenosine 5-phosphosulfate - APSSTase adenosine 5-phosphosulfate sulfotransferase - BSA Bovine serum albumine - DTE dithioerythritol - OAS O-acetyl-L-serine - OASSase O-acetyl-L-serine sulfhydrylase - POPOP 1,4-bis-(5-phenyl-2-oxazolyl)-benzene - PPO 2,5-diphenyloxazole This is no. 9 in the series Regulation of Sulfate Assimilation in Plants     

Regulation of adenosine 5′-phosphosulfate sulfotransferase activity by H2S and cyst(e)ine in primary leaves of Phaseolus vulgaris L.

During chloroplast development in the primary leaves of Phaseolus vulgaris, the extractable activity of adenosine 5-phosphosulfate sulfotransferase increased ten-fold. When chloroplast development took place in air enriched with 3.5 l H₂S·l^-1 there was a decrease in adenosine 5-phosphosulfate sulfotransferase activity. Cyst(e)ine in concentrations up to 1 mM (in the external medium) did not affect the increase in adenosine 5-phosphosulfate sulfotransferase activity in intact plants. In plants with excised roots, 0.75 mM cyst(e)ine inhibited this increase. In green primary leaves, H₂S or cyst(e)ine treatment resulted in a decrease of extractable adenosine 5-phosphosulfate sulfotransferase activity. In intact plants, this effect of cyst(e)ine was observed at a concentration of 1 mM, and in plants with excised roots, 0.25 mM had a comparable effect.In developing plants, the extractable activities of O-acetyl-L-serine sulfhydrylase (EC 4.2.99.9) and ribulosebisphosphate carboxylase (EC 4.1.1.39.) were not affected by H₂S or cyst(e)ine.Abbreviations APS adenosine 5-phosphosulfate - APSSTase adenosine 5phosphosulfate sulfotransferase - BSA bovine serum albumin - DTE dithioerythritol - EDTA ethylenediaminetetra-acetic acid - OASSase O-acetyl-L-serine sulfhydrylase - PAPS adenosine 3-phosphate 5-phosphosulfate - POPOP 1,4 Di 2-(5-phenyloxazolyl)-benzene - PPO 2,5-diphenyloxazol - RubP ribulose-bisphosphate - RubPCase ribulosebiphosphate carboxylase This is no. 8 in the series Regulation of Sulfate Assimilation in Plants. The term cysteine is used when it is clear that cystine is not involved; cyst(e)ine is used for an undefined mixture of cysteine and cystine. The concentrations are expressed in all cases relative to cysteine