Homologues of catalytic domains of Cellulomonas glucanases found in fungal and Bacillus glycosidases

We demonstrate homology between the catalytic domains of exoglucanase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) from Cellulomonas fimi and those of endoxylanases (1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8) from Bacillus sp. strain C-125 and the fungus Cryptococcus albidus; and between the catalytic domains of endoglucanase (1,4-(1,3:1,4)-beta-D-glucan 4-glucanohydrolase, EC 3.2.1.4) from Cellulomonas fimi and exoglucanase II from Trichoderma reesei. These five enzymes apparently evolved by reshuffling of two catalytic domains and several substrate-binding domains.     

The influence of temperature on the fluorine and calcium composition of fish scales

Proton microprobe studies of the scales of the kahawai (Arripis trutta) and the snapper (Chrysophrys auratus) showed non-linear changes in the fluorine to calcium ratio that increase with increasing temperature, but both species showed a different temperature sensitivity. Fluorine and calcium levels vary within years from summer to winter by up to 1000%, making fluorine and calcium levels good markers of seasonal events.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

关于几种避孕植物药的药理初筛及成份预试

本文对云南滇西地区民间用于避孕和绝育秘方中的槌果藤,野花椒寄生、花椒寄生、螃蟹树寄生、鸡矢藤及野花椒的醇提取物进行了小鼠最大耐受量测定及小鼠抗生育实验,结果表明,花椒寄生、螃蟹树寄生的醇提取物具有明显抗生育活性,槌果藤也具有一定的抗生育作用。此外,还对槌果藤、野花椒寄生进行了化学成份预试。     

Bleomycin-Iron Damage To Dna With Formation Of 8-Hydroxydeoxyguanosine and Base Propenals. Indications That Xanthine Oxidase Generates Superoxide From Dna Degradation Products

Bleomycin, in the presence of ferric salts, oxygen and a suitable reductant, degrades DNA with the release of base propenals, detected as thiobarbituric acid (TBA) reactivity, and the formation of 8-hydroxydeo-xyguanosine (80HdG) detected by HPLC. When xanthine oxidase is added to the incubated mixture of DNA degradation products, TBA-reactivity is destroyed but 80HdG formation is increased. EPR Spin trapping experiments show that hydroxyl radicals (OH) are formed in the reaction mixture and can be inhibited by the inclusion of either superoxide dismutase or catalase. These findings suggest that the base propenals and possibly malondialdehyde, formed from them, are aldehydic substrates for xanthine oxidase and, the product of this reaction is superoxide (O₂^-) and hydrogen peroxide (H₂O₂). Thus, TBA reactivity is destroyed in the formation of O₂^- and H₂O₂ which stimulate further oxidative damage to DNA resulting in increased 8OHdG formation.     

Effect of common dead space on VA/Q distribution in the dog

Several previous studies have shown worsening ventilation-perfusion (VA/Q) relationships in humans during heavy exercise at sea level. However, the mechanism of this deterioration remains unclear because of the correlation with ventilatory and circulatory variables. Our hypothesis was that the decrease in the series dead space-to-tidal volume ratio during exercise might be partly responsible because mixing in the common dead space can reduce apparent inequality. We tested this notion in 10 resting anesthetized normocapnic dogs passively hyperventilated by increase tidal volume and a) inspired CO2 or b) external dead space. We predicted less apparent VA/Q inequality in condition b because of mixing in the added dead space. After base-line measurements, conditions a and b were randomly assigned, and after a second set of base-line measurements they were repeated in the reverse order in each dog. VA/Q inequality was measured by the multiple inert gas elimination technique. Comparison of conditions a and b demonstrated that additional external dead space improved (P less than 0.001) the blood flow distributions as hypothesized [log standard deviation of perfusion = 0.49 +/- 0.02 (SE) in condition b and 0.61 +/- 0.03 in condition a with respect to 0.52 +/- 0.03 at base line]. This study suggests that the increased tidal volume during exercise could uncover VA/Q inequality not evident at rest because of the higher ratio of common dead space to tidal volume at rest.     

The Differentiation of a Cell Sorting Mutant of Dictyostelium discoideum

As a result of transfecting Dictyostelium discoideum with an actin 6/ lac Z fusion transgene, strain HW80 was created which expresses the β-galactosidase gene product uniformly throughout development. When mixed with an excess of unmarked wild-type cells, however, HW80 cells selectively migrate to the positions of anterior-like cells surrounding the prespore cell mass, and differentiate as if they were anterior-like cells. As the proportion of HW80 cells is increased, they also sort to positions adjacent to anterior-like cells and some differentiate as prespore cells. Thus sorting of HW80 cells toward the opposite ends of the prespore cell zone supersedes how they differentiate, suggesting that position influences whether cells differentiate as anterior-like or prespore cells.