Differences between drosophila melanogaster and its sibling species D. simulans in sensitivity to acridine orange treatment

Larvae and adults of D. melanogaster and D. simulans were fed with acridine orange, in order to test sensitivity differences between the species. Our results show that, of the two species, D. simulans is more resistant in the larval stages, and D. melanogaster is more resistant in the adult stage. Furthermore, adult males of both species are more sensitive than adult females.     

Internal control of the coated vesicle pp50-specific kinase complex

The polyhedral surface lattice of coated vesicles consists of three-legged hexameric protein complexes called triskelions which constitute the basic assembly unit. The triskelion is a molecular complex of molecular weight 630,000 (Mr 630K) composed of three clathrin heavy chains (subunit 180K) and three light chains (subunits 33K and 36K) (refs 2,3). The presence of additional coated vesicle-specific proteins in the 100-130K and 50-55K range have been reported. We previously described the presence of a cyclic nucleotide- and Ca2+-independent protein kinase activity in coated vesicles which was confirmed by others. This protein kinase specifically phosphorylates the 50K protein (pp50). In this report, we show that the coated vesicle kinase and its 50K protein substrate are part of a stable multimolecular system. In addition we show that the clathrin-light chain complex stimulates the pp50 phosphorylation and only light chains are implicated in this stimulation and that the pp50 phosphorylation does not seem to be affected by the vesicle.     

Asymmetries in conditional mean and variance: modelling stock returns by asMA‐asQGARCH

We propose a nonlinear time series model where both the conditional mean and the conditional variance are asymmetric functions of past information. The model is particularly useful for analysing financial time series where it has been noted that there is an asymmetric impact of good news and bad news on volatility (risk) transmission. We introduce a coherent framework for testing asymmetries in the conditional mean and the conditional variance, separately or jointly. To this end we derive both a Wald and a Lagrange multiplier test. Some of the new asymmetric model's moment properties are investigated. Detailed empirical results are given for the daily returns of the composite index of the New York Stock Exchange. There is strong evidence of asymmetry in both the conditional mean and the conditional variance functions. In a genuine out‐of‐sample forecasting experiment the performance of the best fitted asymmetric model, having asymmetries in both conditional mean and conditional variance, is compared with an asymmetric model for the conditional mean, and with no‐change forecasts. This is done both in terms of conditional mean forecasting as well as in terms of risk forecasting. Finally, the paper presents some evidence of asymmetries in the index stock returns of the Group of Seven (G7) industrialized countries. Copyright © 2004 John Wiley & Sons, Ltd.     

Cross-bridge interaction with oppositely polarized actin filaments in double-overlap zones of insect flight muscle

An unresolved problem in understanding muscular contraction is why the internal resistance to sarcomere shortening increases progressively during contraction. We have addressed this problem here by investigating the movement of detached acting filaments in the sarcomeres of insect flight muscle. The final position of the detached actin filaments shows that they were able to slide freely into regions where they have the wrong polarity to interact actively with myosin (double-overlap zones) but where they prevent the exertion of force by cross-bridges between myosin and the correctly polarized acting filaments. These observations indicate that the isometric tension at all sarcomere lengths is directly proportional to the number of cross-bridges in the region of single-overlap of correctly polarized actin and myosin filaments. The decrease in tension as sarcomeres shorten is thus the result of the decrease in the number of effective cross-bridges as actin filaments slide into regions where they are of the wrong polarity to form cross-bridges, and where they inhibit the existing cross-bridges.     

Ornithine decarboxylase,S-adenosyl-L-methionine decarboxylase and arginine decarboxylase fromMycobacterium bovis (BCG)

Summary Ornithine decarboxylase (ODC), S-adenosyl-L-methionine decarboxylase (AMDC) and arginine decarboxylase (ADC) activities were detected for the first time in extracts ofMycobacterium bovis (BCG). All the decarboxylases differed from corresponding known bacterial decarboxylases in that: a) ODC did not require GTP for activity; b) ODC was not inhibited by any known inhibitor of bacterial ODCs; c) AMDC and ADC did not require Mg²⁺-ion for activity and were not markedly inhibited by any known inhibitor of the decarboxylases of other bacteria.