Pneumocystis carinii shows DNA homology with the ustomycetous red yeast fungi

Pneumocystis carinii causes life-threatening pneumonia in T-lymphocyte-immunodeficient subjects in transplant and oncology units or with acquired immune deficiency syndrome (AIDS). Recent DNA homology studies show P. carinii to be a fungus. To investigate the biology and epidemiology of this parasite further, we elected to determine for it a more precise taxonomic assignment within the fungal kingdom. We screened a wide range of organisms representing the major orders of fungi using DNA amplification and subsequently sequenced a portion of the mitochondrial gene encoding the large subunit ribosomal RNA. Our data show that the opportunistic pulmonary pathogen P. carinii is closely related to the ustomycetous red yeast fungi, a group which includes organisms that are extensively distributed throughout the environment and which release many widely dispersed airborne spores.     

Structure and expression of the Chlorobium vibrioforme hemA gene

The green sulfur bacterium, Chlorobium vibrioforme, synthesizes the tetrapyrrole precursor, -aminolevulinic acid (ALA), from glutamate via the RNA-dependent five-carbon pathway. A 1.9-kb clone of genomic DNA from C. vibrioforme that is capable of transforming a glutamyl-tRNA reductase-deficient, ALA-dependent, hemA mutant of Escherichia coli to prototrophy was sequenced. The transforming C. vibrioforme DNA has significant sequence similarity to the E. coli, Salmonella typhimurium, and Bacillus subtilis hemA genes and contains a 1245 base open reading frame that encodes a 415 amino acid polypeptide with a calculated molecular weight of 46174. This polypeptide has over 28% amino acid identity with the polypeptides deduced from the nucleic acid sequences of the E. coli, S. typhimurium, and B. subtilis hemA genes. No sequence similarity was detected, at either the nucleic acid or the peptide level, with the Rhodobacter capsulatus or Bradyrhizobium japonicum hemA genes, which encode ALA synthase, or with the S. typhimurium hemL gene, which encodes glutamate-1-semialdehyde aminotransferase. These results establish that hemA encodes glutamyl-tRNA reductase in species that use the five-carbon ALA biosynthetic pathway. A second region of the cloned DNA, located downstream from the hemA gene, has significant sequence similarity to the E. coli and B. subtilis hemC genes. This region contains a potential open reading frame that encodes a polypeptide that has high sequence identity to the deduced E. coli and B. subtilis HemC peptides. hemC encodes the tetrapyrrole biosynthetic enzyme, porphobilinogen deaminase, in these species. Preliminary evidence was obtained for the existence of a 3.0-kb polycistronic meassge that includes the hemA sequence, in exponentially growing C. vibrioforme cells. Results of condon usage analysis for the C. vibrioforme hemA gene indicate that green sulfur bacteria are more closely related to purple nonsulfur bacteria than to enteric bacteria. Sequences corresponding to a polyadenylation signal and a poly(A) attachment site were found immediately downstream from the 3 end of the hemA open reading frame.     

Lithium suppresses ovariectomy-induced surges in plasma gonadotropins in rats

We have reported earlier that administration of lithium, the widely-used drug for the treatment of acute mania and prophylaxis of recurrent manic-depressive bipolar disorders, leads to a disruption of estrous cycle and a significant suppression of the proestrous surge of luteinizing hormone (LH) in a number of laboratory rodents. In this report we have examined the effects of this antimanic drug on plasma and pituitary levels of LH and follicle stimulating hormone (FSH) in rats following ovariectomy (OVX), an altered endocrine state in which the levels of serum LH and FSH are highly and chronically elevated. Adult OVX rats, maintained under standardized laboratory conditions (LD 12: 12; white lights on at 06.00 h, CST) were injected (ip) with lithium, 40 days post-operation, at a dosage of 3.0 and 2.0 mEq/Kg b. wt. for 3 and 7 days respectively (twice daily at 08.00 and 16.00 h). Control OVX rats received nothing or saline injections, whereas an intact control (C) received no surgical manipulation or drug injections of any kind. As expected, the levels of plasma LH and FSH in OVX (only) group showed nearly 6-fold and 75-fold increase respectively compared to those in C. Lithium injections in OVX rats for 3 and 7 days resulted in a significant reduction in plasma LH (P less than .005 and P less than .02 respectively) and FSH (P less than .001) levels when compared with those in the OVX control groups. Lithium also led to a significant reduction in the levels of pituitary LH after both 3 (P less than .02) and 7 days (P less than .02), but the levels of pituitary FSH remained unchanged. These results suggest that the pituitary gonadotropes constitute a definitive target for lithium's action, either directly or via the hypothalamus.     

Lipase-catalysed esterification reaction in a tubular reactor

Summary Lipozyme catalysed esterification of oleic acid with lauryl alcohol was studied in a tubular recycle reactor. Water formed during the reaction was removed by adsorption, either by passing the product mixture through another column packed with molecular sieve, or by packing the reactor partially with silica gel.     

The structures of garcinones a,b and c: Three new xanthones from Garcinia mangostana

Three new tetraoxygenated xanthones (garcinones A, B and C), each disubstituted with C₅-units, have been isolated from the chloroform extract of the fruit-hulls of Garcinia mangostana. Their structures were established by a combination of spectral interpretation and chemical correlation.     

Majvinine: A new indole alkaloid of Vinca major

A new alkaloid, majvinine, was isolated from aerial parts of Vinca major. Its structure was determined by chemical and spectroscopic investigations     

Membrane lipid composition modulates the binding specificity of a monoclonal antibody against liposomes

A hybridoma secreting a monoclonal IgM 'anti-liposome' antibody was produced after injecting a mouse with liposomes containing dipalmitoylphosphatidylcholine, cholesterol, dicetyl phosphate, and lipid A. The antibody was selected by assaying for complement-dependent damage to liposomes lacking lipid A. The monoclonal antibody reacted best with liposomes containing the original immunizing mixture of lipids. Deletion of individual lipid constituents from liposomes diminished the ability of the liposomes to bind (adsorb) the antibody. Binding of the antibody was enhanced by including lipid A or galactosylceramide in the lipid bilayer, or by substituting egg phosphatidylcholine for dimyristoyl- (or dipalmitoyl-) phosphatidylcholine. Sphingomyelin could be substituted for dimyristoylphosphatidylcholine without altering the adsorption of antibody. Although the monoclonal anti-liposome antibody was completely inhibited by phosphocholine, it was probably not a conventional anti-phosphocholine antibody. The antibody apparently had a partial specificity for phosphate, and was inhibited by glycerophosphocholine, glycerophosphate, sodium phosphate, sodium sulfate, and inositol hexaphosphate, but not by choline or inositol.     

Cyclo (His-Pro): a selective inhibitor of rat prolactin secretion in vitro

Cyclo (His-Pro) (10 ng/ml), inhibits KCl (59 mM) or thyrotropin-releasing hormone (10 ng/ml) stimulated, but not basal, release of prolactin from rat hemipituitaries $\text{in vitro}$. However, cyclo (His-Pro) has no effect on the basal or stimulated release of thyrotropin and growth hormone. Cyclo (His-Pro) does not inhibit the binding of thyrotropin-releasing hormone to pituitary membrane suggesting that cyclo (His-Pro) inhibition of prolactin release is not mediated via the pituitary TRH-receptor.