A Method for Visualizing the Acrosome by Light Microscopy

A silver staining technique applied to squash preparations of material previously fixed in 3:1 ethanol: acetic acid produces differential staining of the acrosomal region of spermatids during spermiogenesis in orthopteroid species. The method includes treatment with saline sodium citrate solution for 15 min at 60 C, and staining with 50% aqueous silver nitrate adjusted to pH 2.9 with formic acid.     

Sequential homologies between procarboxypeptidases A and B from porcine pancreas

Automated Edman degradation of monomeric procarboxypeptidases A and B from porcine pancreas shows that their N-terminal regions (from residue 1 to 34-37) present a high degree of sequential homology to each other as well as to other related procarboxypeptidases. Conformational predictions based on these sequences confirm their structural homology and indicate the probable existence of two beta-turns, one beta-chain and a long alpha-helix in them. On the other hand, tryptic peptide maps on a reverse-phase column indicate great sequential similarities (if not identity) between monomeric procarboxypeptidase A and the procarboxypeptidase A subunit isolated from its binary complex with proproteinase E.     

Nodular fasciitis initially diagnosed by aspiration cytology

A case of nodular fasciitis diagnosed by fine needle aspiration cytology is described. The cytologic findings included fusiform cells, mitoses, macrophages, multinucleated giant cells and mesenchymal elements in a characteristic granular background substance. The cytopathologic diagnosis was subsequently confirmed by the histopathologic study of the tumor and by electron microscopy.     

Maximal exercise capacity in adolescent European and Amerindian high-altitude natives

Forty-seven highland natives were given maximal exercise tests on a treadmill ergometer at 3,600 m. The subjects were grouped into four subsamples on the basis of ethnicity (European vs. Aymara) and age (young vs. old adolescent). Two-way ANOVA indicated that VO2max adjusted for body size did not differ significantly between ethnic groups but was significantly larger in older than younger boys within each ethnic group (p less than .05). This finding does not support the hypothesis that Amerindian highland natives have adapted genetically to hypoxia but is consistent with the hypothesis that the relatively high VO2max's of highlanders are acquired by developmental adaptation. Several measures of ventilation and oxygen transport capacity differed significantly between ethnic groups, suggesting that growing European and Aymara boys may respond somewhat differently to the stress of high-altitude hypoxia. However, despite these differences, VO2max, an integrated measure of the overall functional capacity of the oxygen transport system, did not differ significantly between ethnic groups, suggesting that both groups are equally capable of meeting the body's oxygen requirements during maximal exercise at high altitude.     

19q distal trisomy due to a de novo (19;22)(q13.2;p11) translocation

A 2 4/12-year-old girl whith a de novo 46,XX,-22 + der(22), t(19;22)(q13.2;p11) karyotype is described. From this and other eight similar cases previously published, a typical phenotype in distal 19q trisomy is concluded.     

Cationic amino acid transport by two renal epithelial cell lines: LLC-PK1 and MDCK cells

LLC-PK1 and MDCK cells take up cationic amino acids (lysine and arginine) by a specific sodium independent transport system. Uptake is inhibited by ornithine in LLC-PK1 and MDCK cells either in the presence or absence of sodium and by glutamine or homoserine in MDCK cells in the presence of sodium. Trans-stimulation of uptake occurs in the presence of intracellular cationic amino acids. Experiments with valinomycin or with different extracellular potassium concentrations suggest that uptake is dependent on the membrane potential of these cells. These transport features are similar to those previously ascribed to a transport system denominated y+ in other cells. Further experiments suggested that this carrier system is localised to the basolateral membrane in each cell type.     

Inhibition of geranylgeranyl diphosphate synthesis in in vitro systems

The incorporation of [¹⁴C]mevalonate and [¹⁴C]isopentenyl diphosphate into geranylgeranyl diphosphate was investigated in in vitro systems from Cucurbita pepo (pumpkin) endosperm and from Avena sativa etioplasts. Mevalonate incorporation was effectively inhibited in the pumpkin system by geranylgeranyl diphosphate and geranylgeranyl monophosphate but less effectively by phytyl diphosphate or inorganic diphosphate. Membrane lipids, geranyllinalool, or lecithin enhanced mevalonate incorporation in the Cucurbita system. Incorporation of isopentenyl diphosphate was also enhanced by lecithin and inhibited by geranylgeranyl diphosphate in the Cucurbita system. No lipid enhancement was found in the Avena system; inhibition by GGPP required a much higher GGPP concentration than in the Cucurbita system.     

Microgeographic and Temporal Genetic Differentiation in Natural Populations of DROSOPHILA SUBOBSCURA

Evidence of microgeographic and temporal genetic differentiation in natural populations of Drosophila subobscura is presented. The alcohol dehydrogenease locus was used as a genetic marker. Behavioral differences among the sexes and genotypes may explain these observations, although the molecular basis remains obscure.     

Methylation of type II and type I collagen genes in differentiated and dedifferentiated chondrocytes

The methyl-sensitive restriction endonucleases HpaII and HhaI as well as the methyl-insensitive enzyme MspI were used to examine the methylation status of the pro-alpha 1(II) collagen gene of cartilage. Five different cell types with varying abilities to express type II collagen were studied. Chick embryo chondrocytes express type II collagen, while 5-bromodeoxyuridine-treated chondrocytes, retinoic acid-treated chondrocytes, chick embryo fibroblasts, and erythrocytes do not synthesize type II collagen. Both cDNA and genomic probes for the pro-alpha 1(II) collagen gene were used, covering the complete 3' end of the gene and its flanking sequences. The pro-alpha 1(II) collagen DNA was undermethylated in chondrocytes, compared to either fibroblasts or erythrocytes. However, the methylation of the 5-bromodeoxyuridine-treated and retinoic acid-treated chondrocytes was identical to that of control chondrocytes. The methylation pattern of two regions of the gene of the pro-alpha 2(I) collagen chain was identical in all cell types tested, whether or not the gene was expressed. Our results indicate that genes for these collagen chains differ in their methylation pattern. The type II collagen gene shows reduced methylation in expressing cartilage, but does not acquire an increase in methylation in "dedifferentiated" chondrocytes. The changes in DNA methylation that occur during cell differentiation do not appear to be sufficient to explain gene activation and deactivation.     

Inhibition of non-genomic responses to oestrogen in the rat uterus by testosterone propionate

Testosterone propionate (50 mg/kg), administered together with oestradiol, inhibited the oestrogen-induced uterine eosinophilia, deep endometrial oedema and the increase in uterine wet weight, 6 h after treatment. The same dose of the androgen decreased the number of eosinophils in the blood and increased their degranulation, explaining the effect of testosterone in the uterus. The high doses of the androgen used were in the range of the doses reported by others to block selectively the oestrogen-induced increase in uterine peroxidase content but not other responses to oestrogen or the cytosolic oestrogen receptor translocation to the nucleus. The dissociation by high doses of testosterone of the oestrogen-induced uterine eosinophilia, wet weight increase and oedema from other responses to oestrogen in the absence of any measurable effect of testosterone upon cytosolic-nuclear oestrogen receptors supports the idea that uterine eosinophilia and oedema are oestrogenic responses regulated by mechanisms different from those of the genomic responses, and is in agreement with the hypothesis of the mediation of uterine oedema by eosinophils.