Zum Problem der menschlichen Stammesgeschichte

Ohne Zusammenfassung     

C-band differentiation between the chromosomes of two subspecies of the chironomid midgeChironomus thummi

Summary The metaphase chromosomes ofChironomus th. thummi contain approximately 17% more pericentric C-band heterochromatin than the chromosomes ofChironomus th. piger with 11% heterochromatin. InCh. th. thummi, the proportion of heterochromatin appeared to be much larger in metaphase chromosomes than in polytene chromosomes. This discrepancy is interpreted as being due to the specific chromosome organization and not as the result of an underreplication of heterochromatin during polytenization.     

甲状旁腺素(PTH)对氯化钾引起大白鼠输精管收缩的舒张作用

本研究探讨甲状旁腺素(PTH)对输精管平滑肌的舒张作用及其机制。不同剂量的氯化钾(20、40、60mM)引起大白鼠输精管的收缩,同样可被牛型—PTH(1—34)或人型—PTH(1—34)所舒张,而且均呈现剂量的依从关系。异丙肾上腺素舒张输精管的作用可被心得安所阻滞,但心得安或酚妥拉明均不抑制甲状旁腺素舒张输精管的作用,提示甲状旁腺素和异丙肾上腺素对输精管的舒张作用是通过不同的受体实现的。不同剂量的氯化钙引起输精管不同张力强度的收缩,甲状旁腺素对这种外源性钙引起的收缩呈现明显的抑制作用,说明甲状旁腺素有减少钙离子进入平滑肌组织的作用。     

Reciprocal biological activities of the cyclic tetrapeptides chlamydocin and HC-toxin

Summary Chlamydocin, a potent cytostatic agent against cultured mammalian cells, and HC-toxin, a host-specific phytotoxin, are cyclic tetrapeptides containing the same epoxide -amino acid. We show here that these compounds have reciprocal biological activity; HC-toxin is cytostatic against cultured mastocytoma cells, and chlamydocin has host-specific toxin activity against maize. Chlamydocin and another related cyclic peptide, Cyl-2, are less host-specific than HC-toxin because maize tolerant to HC-toxin is more sensitive to chlamydocin and Cyl-2.     

Oviposition-deterring pheromone inRhagoletis cerasi L.: Purification and determination of the chemical constitution

Summary An oviposition-deterring pheromone (ODP) of the European cherry fruit flyRhagoletis cerasi L. was isolated from faeces using cellulose and several reverse phase TLC and HPLC procedures. The biological activity was evaluated by means of behavior tests and by electrophysiological recordings from tarsal contact chemoreceptors. The compound was structurally characterized as a N[15(-glucopyranosyl)oxy-8-hydroxypalmitoyl]-taurine by spectroscopic means. The configurations of C-8 and C-15 of the fatty acid constituent remain to be established by synthetic work.     

On assessing the relative performance of default predictions

We compare the accuracy of default predictions as, for instance, produced by professional rating agencies. We extend previous results on partial orderings to nonidentical sets of obligors and show that the calibration requirement virtually rules out the possibility of some partial orderings and that the partial ordering based on the ROC curve is most easily achieved in practice. As an example, we show for more than 5,000 firms rated by Moody's and S&P that these ratings cannot be ranked according to their grade distributions given default or nondefault, but that Moody's dominate S&P with respect to the ROC criterion and the Gini curve.