Photochemical reactions in interstellar grains photolysis of co,NH3, and H2O

A simulation of the organic layer accreted onto interstellar dust particles was prepared by slow deposition of a CO:NH₃:H₂O gas mixture on an Al block at 10K, with concomitant irradiation with vacuum UV. The residues were analyzed by GC-MS, HPLC, and near IR; a reaction pathway leading from NH₃ to complex alcohol, fatty acid, and amide products in 27 stages is postulated. The astronomical relevance and significance of the observations are discussed.     

Teratogenic effect of trifluoperazine in rats and mice

Trifluoperazine was administered to pregnant mice and rats by gastric intubation during the period of organogenesis. Dams were treated at doses of 0.5, 5, 50 (mice and rats) and 100 (only rats) mg/kg/day. The drug affected the pregnant weight increment in a dose-related manner in rats but only the 50 mg/kg/day dose level affected the weight gain of mice. The foetal weight was not markedly affected in either species. The drug induced cleft palate and micrognathia in rats but did not produce a teratogenic effect in mice. Trifluoperazine caused abortions in mice and there were significant increases in the number of resorptions with the top dose levels in both species.     

The amino terminal half of the MS2-coded lysis protein is dispensable for function: implications for our understanding of coding region overlaps.

We have asked whether genetic overlaps only evolve to provide extra coding capacity in genomes of restricted size. As a model system we have used the lysis gene of the RNA bacteriophage MS2. This gene overlaps with the distal part of the coat protein gene and with the proximal part of the replicase gene. Using recombinant DNA procedures we have determined whether either of the two overlaps codes for amino acids that are not essential for the function of the 75 amino acid long lysis protein. We find that the first 40 amino acids of the lysis protein are dispensable for function. Thus all of the genetic information essential to the synthesis of the active C-terminal peptide lies within the overlap with the replicase gene, whereas all dispensable residues are encoded in the overlap with the coat protein gene and in the intercistronic region. This suggests that the overlap with the coat protein gene is not required for extra coding capacity but serves to regulate the expression of the lysis gene. Comparative sequence analysis is consistent with this idea.     

Purification and subunit structure of RNA polymerases I and II from Dictyostelium discoideum vegetative cells

Summary A purification procedure to obtain RNA polymerases I (or A) and II (or B) from Dictyostelium discoideum amoeba has been developed. The enzymes were solubilized from purified nuclei and separated by DEAF-Sephadex chromatography. RNA polymerases I and II were further purified by a second chromatography on DEAE-Sephadex followed by chromatographies on phosphocellulose and heparin-sepharose. The specific activities of purified RNA polymerases I and II are 92 units/ mg protein and 70 units/ mg protein, respectively. The subunit structure of both RNA polymerases were analyzed by polyacrylamide gel electrophoresis under denaturing conditions after glycerol gradient centrifugation of the enzymes. The putative subunits of RNA polymerase I have molecular weights of 180 000,125 000,43 000,40 000,34 000, 31 000, 25 000,19 000, 17 000 and 14 000. The putative subunits of RNA polymerase II have molecular weights of 200 000 (170 000), 130 000, 33 000, 25 000, 19 000, 17 000, 15 000, 13 000. There are three polypeptides with common molecular weight in Dictyostelium RNA polymerases I and 11. The subunit of 25 000 daltons of both enzymes has common immunological determinants with RNA polymerase II from crustacean Artemia.Abbreviations TLCK tosyl-lysine-chloromethyl-ketone - DPT diazophenylthioether     

Disturbances in toxicological experiments caused by Microsporum canis

Cutaneous lesions which can lead to false positive results have been observed in several rabbits used for the determination of the cutaneous irritation capacity of a product (ITA, PII). The responsible agent was Microsporum canis. A preventive treatment by an antifungal agent did not modify toxicological experimental results.     

Rhodotorula nothofagi sp. nov., isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

An unusual Rhodotorula isolated from decayed wood of Nothofagus obliqua (Mirb.) Blume is described and illustrated. This species differs from all accepted Rhodotorula species (1–7, 10) to warrant its establishment as a new species, Rhodotorula nothofagi sp. nov.Postgraduate student from the Instituto de Ecología y de Evolución, Universidad Austral de Chile, Valdivia.     

Condensation of DNA by the C-terminal domain of histone H1. A circular dichroism study

The condensation of DNA by the C-terminal domain of histone H1 has been studied by circular dichroism in physiological salt concentration (0.14 M NaF). As the intact H1 molecule, its C-terminal domain induces the so-called psi state of DNA that is characterized by a nonconservative circular dichroism spectrum which is currently attributed to ordered aggregation of the DNA molecules. On a molar basis, intact H1 and its C-terminal domain give spectra of similar intensity. Neither the globular domain of H1 nor an N-terminal fragment, that includes both the globular and N-terminal domains, has any effect on the conservative circular dichroism of DNA. From these results it is concluded that the condensation of DNA mediated by histone H1 is mainly due to its C-terminal domain. The effect of the salt concentration and the size of DNA molecules on the circular dichroism of the complexes are also examined.     

In vitro determination of phagocytic indices of Candida berkhout species by rat peritoneal macrophages

The aims of this investigation were to study and describe the behaviour of 13 different species of Candida, as compared with C. albicans, by means of phagocytosis assays in vitro.Tests were carried out with rat peritoneal macrophages in contact with quantified suspensions of live yeasts. Phagocytic indices, candidacidal activity and filamentation rat were tested microscopically after 3 h incubation at 37 ° C.The phagocytic indices obtained allowed us to separate the fungi into four groups. Candida albicans and tropicalis belong to Group I; diddensii and shehatae, among others, belong to Group II; sake, krusei, viswanathii, etc., Group III; and C. glaebosa and haploid strains of Pichia ohmeri (C. guilliermondii var. membranaefaciens), Group IV. These data would suggest a possible correlation between pathogenesis and phagocytic indices.There were no evidences of any phagocytes ability to kill yeasts. Candidacidal activity was absent in the species assayed. Yeast lysis may have been observed if our assays would have taken longer than 3 h.