Integration of four genes,a pseudogene,thirty-one STSs,and a highly polymorphic STRP into the 7–10 Mb YAC contig of 5q34–q35

Thirty-one sequence tagged sites and a highly polymorphic short tandem repeat polymorphism have been isolated from 5q34–q35 and integrated into the yeast artificial chromosome (YAC) contig of 5q34–q35. In addition, four genes (MSX2, CSX, DRDI, andCLI00) and a pseudogene (GLUT6) were localized on this map. The high density of new markers in the region allowed further refinement of the YAC contig of distal 5q. This is a prerequisite for the conversion of this YAC into a cosmid contig.     

Interdemic variation in haematocrit and lactate dehydrogenase in the African cyprinid Barbus neumayeri

This study evaluated whether the African cyprinid Barbus neumayeri from Rwembaita Swamp (low‐oxygen) and Njuguta River (high‐oxygen) in the Kibale National Park, Uganda differed in traits related to aerobic and anaerobic metabolic potential. Haematocrit was measured as an index of blood oxygen‐carrying capacity, and tissue activities and isozyme composition of lactate dehydrogenase (LDH) were measured as indices of tissue anaerobic capacity. To address whether site‐dependent differences were acute responses v . longer‐term adjustments to environmental conditions, these variables were measured in fish sampled shortly after collection and after laboratory maintenance under well‐aerated conditions. In fish sampled in the field, those from the low‐oxygen site had significantly higher haematocrit, but this difference disappeared after long‐term laboratory maintenance. In contrast, fish from the low‐oxygen site had higher liver LDH activities than fish from the high‐oxygen site, and this difference persisted during laboratory maintenance. Polymorphism was detected at both the LDH‐A and LDH‐B loci, and genotype frequencies for LDH‐B differed significantly between collection sites. These results demonstrate physiological, biochemical and genetic differences in B. neumayeri from habitats differing in dissolved oxygen availability and suggest both acute and long‐term responses to local environmental conditions.     

Sequence of a cDNA for mouse thymidylate synthase reveals striking similarity with the prokaryotic enzyme

We report the nucleotide sequence of a cloned cDNA, pMTS-3, that contains a 1-kb insert corresponding to mouse thymidylate synthase (E.C. 2.1.1.45). The open reading frame of 921 nucleotides from the first AUG to the termination codon specifies a protein with a molecular mass of 34,962 daltons. The predicted amino acid sequence is 90% identical with that of the human enzyme. The mouse sequence also has an extremely high degree of similarity (as much as 55% identity) with prokaryotic thymidylate synthase sequences, indicating that thymidylate synthase is among the most highly conserved proteins studied to date. The similarity is especially pronounced (as much as 80% identity) in the 44-amino-acid region encompassing the binding site for deoxyuridylic acid. The cDNA sequence also suggests that mouse thymidylate synthase mRNA lacks a 3' untranslated region, since the termination codon, UAA, is followed immediately by a poly(A) segment.      

Induction of sister chromatid exchanges by benzidine in rat and human hepatoma cell lines and inhibition by indomethacin

The genotoxic activity of benzidine was studied in two cell lines derived from rat (H4) and human (HepG2) hepatomas which have been shown to be capable of activating certain promutagens. The responses were compared to results in two lung-derived fibroblast lines (IMR-90 and V79) which appear to have little or no metabolizing capability. Benzidine was found to induce sister chromatid exchanges in the two liver-derived cell lines in a dose-dependent fashion but failed to induce sister chromatid exchanges in the fibroblast lines. Since one proposed pathway for benzidine activation involves prostaglandin-mediated metabolism, we tested the effect of pretreatment with indomethacin, an inhibitor of this metabolic pathway. Indomethacin was highly effective in inhibiting benzidine-induced sister chromatid exchanges in both H4 and HepG2 cells. These results suggest that some DNA damage may occur in the livers of fast acetylating species such as the rat without prior N-acetylation and that some amount of DNA damage may occur in the livers of slow acetylating species, even when the liver is not the target organ for carcinogenesis.Abbreviations RI replication index - SCE sister chromatid exchanges     

Inhibition of a nutrient-dependent pinocytosis in dictyostelium discoideum by the amino acid analogue hadacidin

In the present study we examine the effects of the drug hadacidin (N-formyl-N- hydroxyglycine) on pinocytosis in the eukaryotic microorganism dictyostelium discoideum. At concentrations of up to approximately 8 mg/ml, hadacidin inhibited the rate of pinocytosis of fluorescein isothiocyanate (FITC) dextran in cells in growth medium in a concentration-dependent manner but had no effect on cells in starvation medium. Because hadacidin also inhibits cellular proliferation at this concentration, the relationship between growth rate and pinocytosis was studied further using another drug, cerulenin, to produce growth-arrest. These experiments showed no changes in the rate pinocytosis even after complete cessation of cellular proliferation. Other studies showed that the transfer of cells from growth to starvation medium reduced the rate of pinocytosis by approximately 50 percent. A reduction of similar magnitude occurred if cells were transferred from growth to starvation medium containing hadacidin. Also, no additional reduction in pinocytosis occurred when cells that had been treated with hadacidin were transferred to starvation medium containing hadacidin. These cells were able to take up [(14)C]hadacidin in the starvation medium. In contrast to the results with hadacidin-treated cells, cells in a cerulenin-induced state of growth-arrest when transferred to starvation medium exhibited the same 50 percent reduction in pinocytosis observed in cells not previously exposed to either drug. Cells treated with azide, in either growth or starvation medium, exhibited an immediate inhibition of all pinocytotic activity. After the transfer of log-phase cells to starvation medium supplemented with glucose, the reduction in rate was only approximately 10-15 percent. In contrast, a 50 percent reduction was observed after supplementation of starvation medium with sucrose, KCl, or concanavalin A. Maintaining the cells in growth medium containing hadacidin for as long as 16 h had no effect on the rate at which cells aggregated. These results are consistent with the conclusion that D. discoideum exhibits two types of pinocytotic activity: one that is nutrient dependent and the other independent of nutrients. This latter activity persists in starvation medium and is unaffected by hadacidin, whereas the nutrient-dependent activity is present in growth medium and is inhibited by hadacidin.     

Venous Graft Surgery in Treatment of Coronary Heart Disease

Sixty-seven patients have had aortocoronary venous graft bypass surgery by one surgeon for the relief of symptoms of severe coronary heart disease, including eight emergency operations. The overall operative, hospital, and late mortality was low in patients with favourable myocardial function and no previous myocardial infarction. There was a 7% mortality in patients with a normal preoperative chest radiogram, 8% mortality when the left ventricular end-diastolic pressure was normal preoperatively, and a 5% mortality in patients who had normal left ventricular angiograms. The overall mortality in all elective operations for cardiac pain resistant to medical treatment was 15·8%. 89% of survivors improved; 67% are pain-free. Exercise tolerance in survivors is increased by 135%, atrial pacing results are improved by 10%. Left ventricular end-diastolic pressure is unchanged. Left ventricular function on angiography is improved. The improvement in left ventricular function assessed objectively correlates positively with vein-graft patency, as does freedom from angina pectoris.     

CYTOTAXONOMIC STUDIES IN THE EUPHORBIACEAE,SUBTRIBE PHYLLANTHINAE

Webster , Grady L. (Purdue U., Lafayette, Ind.), and J. R. Ellis . Cytotaxonomic studies in the Euphorbiaceae, subtribe Phyllanthinae. Amer. Jour. Bot. 49:(1): 14–18. Illus. 1962.—Chromosome numbers are reported for 18 species of mostly West Indian Euphorbiaceae, subtribe Phyllanthinae, 13 of these for the first time (including the first published count for the genus Margaritaria). For 4 species, a number different from previous determinations has been recorded. The base chromosome number in Breynia, Fluggea, Margaritaria, and most species of Phyllanthus appears to be 13. However, in Phyllanthus subg. Isocladus haploid numbers of 8 and 18 were observed. One species, Phyllanthus pulcher, is a sterile hexaploid (n = 39) of presumably hybrid origin. The cytological data do not support Perry's suggestion that annual taxa are primitive in the Euphorbiaceae.     

MICROBODIES IN EXPERIMENTALLY ALTERED CELLS

A rapid and sustained increase in the number of microbodies in liver and kidney cells can be induced in male rats by ethyl chlorophenoxyisobutyrate (CPIB), a hypolipidemic drug. This phenomenon permits investigation of several aspects of microbody behavior in experimental conditions. Reversal experiments demonstrate that liver cells revert to normal between 2 and 3 weeks after withdrawal of CPIB and that one of the mechanisms for removal of excess microbodies is their incorporation into structures indistinguishable from lysosomes. In a state of rapid cell division, such as that present during liver regeneration, microbody proliferation apparently occupies a high biological priority. In necrotic or degenerating cells microbody structure remains relatively normal. The increase in microbodies induced by CPIB is inhibited by chloramphenicol. No increase in microbodies occurred in female rats or in chickens, guinea pigs, or rabbits at the dosage used (0.25% in diet). No changes in microbodies were seen in monkey liver. Catalase activity was generally parallel to the numerical response in microbodies. Additional observations suggest that the microbody response to CPIB is not related to hepatomegaly induced by this agent but may be related to the hypolipidemic effect of CPIB, though hypolipidemia per se is not a specific or sufficient cause of microbody proliferation.