Solid-state conformation of some basic sequential polypeptides

We have studied the structure of solid films obtained by x-ray diffraction, from several basic polypeptides with a defined sequence. The alterating polypeptides poly(Ala-Lys), poly(Leu-Lys), poly(Val-Lys), and poly(Arg-Leu) all show a cross-β-structure in which layers of hydrophilic side chains alternate with layers containing hydrophobic side chains. The other polypeptides studied are not in the β-conformation and appear to be in the α-helical conformation. The helices obtained from poly(Lys-Ala-Ala) and poly(Lys-Ala-Ala-Lys) appear to be packed in an unusual fashion, which favors interaction between alanine side chains. Such behavior is not found in poly(Lys-Leu-Ala).     

Onychomycosis due to saprophytic fungi

Twenty five cases of onychomycosis due to filamentous saprophytic agents were diagnosed within the period 1981–1982 in two mycology laboratories in Medellín, Colombia. These cases represented 4.5% and 9.5% respectively of the total fungal nail lesions (FNL) seen at those institutions. No explanation was found for the high frequencies, which sharply contrast with the previous local experience with the disease (0.4% of FNL). The responsible agents belonged to the following genera in decreasing order of frequency: Fusarium, Aspergillus, Scopulariopsis, Penicillium and Lasiodiplodia; two patients were infected with unidentified dematiaceous fungi and two more had the association of a saprophyte and a dermatophyte. In every case direct KOH preparations revealed septate hyphae, associated in 14 patients (56%) with chlamydoconidia. The only predisposing factors that were common to all these patients were age above 20 years and the use of footwear.     

Protoplast forming ability in the genusBrevibacterium

Formation of protoplasts and their reversion were followed in 7 strains of brevibacteria. The formation of protoplasts and their reversion differed both between various species of brevibacteria and between various mutant strains of the same species.     

Effect of rhodium (III) complex on experimental carcinogenesis in the livers of rats treated with thioacetamide

Enzyme activities and protein content were determined in the cytosolic and mitochondrial fractions of liver homogenates obtained from Rh(III) complex-, thioacetamide- and thioacetamide + Rh(III) complex-treated rats. The Rh(III) complex administered to nonthioacetamide-treated rats produced no significant changes either in the enzymatic activities assayed or in the protein concentration. The Rh(III) complex administered to thioacetamide-treated rats produced significant restoration of the following altered values: cytosolic and mitochondrial aspartate aminotransferase, glutamate dehydrogenase, NADP-isocitrate dehydrogenase, and protein concentration. However, a further increase was produced in the activities of glucose-6-phosphate dehydrogenase and malic enzyme. These increases can be interpreted in terms of an enhancement of the NADPH-dependent detoxifying processes and of nucleic acid synthesis and repair.     

Desangeloylshairidin,X-ray structure determination of a sesquiterpene lactone from Guillonea scabra

The structure and absolute configuration of desangeloylshairidin, a guaianolide isolated from Guillonea scabra, have been established by X-ray diffraction analysis. No conformational change was observed in its seven-membered ring between the crystal and deuterochloroform solution states.     

Heterochromatin distribution and chiasma localization in the grasshopper Bryodema tuberculata (fabr.) (Acrididae)

The problem of extreme localisation of chiasmata in the grasshopper species Bryodema tuberculata has been reinvestigated, using C-banding, Q-banding and benzimidazol techniques. These techniques reveal the precise localisation of heterochromatin in different chromosomes. Single or double heterochromatic blocks are present near the centromeric regions, except in chromosomes 5 and 11, which have larger blocks. These two chromosomes possess a distal chiasma while the other autosomes have a proximal chiasma. The results with regard to the distribution of chiasmata, in relation to the localisation of heterochromatin, as well as the existence of a short arm, are compared with the earlier observations of White, and discussed briefly.