Complex genome evolution in Anopheles coluzzii associated with increased insecticide usage in Mali

In certain cases, a species may have access to important genetic variation present in a related species via adaptive introgression. These novel alleles may interact with their new genetic background, resulting in unexpected phenotypes. In this study, we describe a selective sweep on standing variation on the X chromosome in the mosquito Anopheles coluzzii, a principal malaria vector in West Africa. This event may have been influenced by the recent adaptive introgression of the insecticide resistance gene known as kdr from the sister species Anopheles gambiae. Individuals carrying both kdr and a nearly fixed X‐linked haplotype, encompassing at least four genes including the P450 gene CYP9K1 and the cuticular protein CPR125, have rapidly increased in relative frequency. In parallel, a reproductively isolated insecticide‐susceptible A. gambiae population (Bamako form) has been driven to local extinction, likely due to strong selection from increased insecticide‐treated bed net usage.     

Inhibition of prostaglandin biosynthesis by sulphasalazine and its metabolites

Sulphasalazine (SZ) inhibits prostaglandin (PG) biosynthesis $\text{in vitro}$ with a potency comparable to that of aceylsalicylate. The metabolites of SZ, sulphapyridine and 5-aminosalicylic acid, were of considerably lower potency as inhibitors of PG biosynthesis in the synthetase preparations used. The inhibition of prostaglandin production by SZ could at least partly account for the clinical utility of sulphasalazine in ulcerative colitis. Sulphapyridine may help to maintain inhibitory concentrations of SZ by restraining bacterial breakdown of the active drug.     

Completion of diapause in field populations of the cabbage root fly (Delia radicum)

The various diapause and post-diapause stages entered by cabbage root fly pupae during the overwintering period are shown schematically. Although diapause induction started in mid-Aug., the early-pupating insects did not develop further but were maintained in diapause by the warm autumn temperatures. Therefore, diapause development was simultaneous in all Wellesbourne pupae, whether of second or third generation origin. Diapause development started only in mid-Oct., when mean soil temperatures fell below 10°. In the field, 90% of the overwintering population of cabbage root fly pupae had completed pleted diapause by 5 March 1980, 17 Feb. 1981 and 18 Feb. 1982. This was equivalent to a duration of 19 weeks from mid-Oct. onwards, during the winters of 1979–80, 1980–81 and 1981–82 respectively. A further break between the completion of diapause and the warm conditions required to start post-diapause development also helps to condense the emergence of flies in the spring. Hence, an accurate forecast of the time of spring attack by populations of flies similar to those at Wellesbourne should be possible.This study was financed partly by the Commission of the European Communities as CEC Contract No. 0771.     

Sexual dimorphism in relation to big-game hunting and economy in modern human populations

Postcranial skeletal data from two recent Eskimo populations are used to test David Frayer's model of sexual dimorphism reduction in Europe between the Upper Paleolithic and Mesolithic. Frayer argued that a change from big-game hunting and adoption of new technology in the Mesolithic reduced selection for large body size in males and led to a reduction in skeletal sexual dimorphism. Though aspects of Frayer's work have been criticized in the literature, the association of big-game hunting and high sexual dimorphism is untested. This study employs univariate and multivariate analysis to test that association by examining sexual dimorphism of cranial and postcranial bones of two recent Alaskan Eskimo populations, one being big-game (whale and other large marine mammal) hunting people, and the second being salmon fishing, riverine people. While big-game hunting influences skeletal robusticity, it cannot be said to lead to greater sexual dimorphism generally. The two populations had different relative sexual dimorphism levels for different parts of the body. Notably, the big-game hunting (whaling) Eskimos had the lower multivariate dimorphism in the humerus, which could be expected to be the structure under greatest exertion by such hunting in males. While the exertions of the whale hunting economic activities led to high skeletal robusticity, as predicted by Frayer's model, this was true of the females as well as the males, resulting in low sexual dimorphism in some features. Females are half the sexual dimorphism equation, and they cannot be seen as constants in any model of economic behavior. © 1993 Wiley-Liss, Inc.     

Cytoplasmic and mitochondrial arginine kinases inDrosophila: Evidence for a single gene

Mitochondrial and cytoplasmic isozymes of arginine kinase have been identified inDrosophila melanogaster. On the basis of their immunological similarity, parallel dosage responses, and cosegregation of electrophoretic mobility differences, it is concluded that both isozymes are the product of a single gene. The consequences of this in relation to the regulation and evolution of this unusual gene-enzyme system are discussed. It is inferred that the origin of the phosphagen shuttle must predate the divergence of invertebrates and vertebrates.     

Pseudomonas aeruginosa exotoxin A: alterations of biological and biochemical properties resulting from mutation of glutamic acid 553 to aspartic acid

Glutamic acid 553 of Pseudomonas aeruginosa exotoxin A (ETA) was identified earlier as a putative active-site residue by photoaffinity labeling with NAD. Here ETA-E553D, a cloned form of the toxin in which Glu-553 has been replaced by aspartic acid, was purified from Escherichia coli extracts and characterized. Cytotoxicity of the mutant toxin for mouse L-M cells was less than 1/400,000 that of the wild type. The mutation caused a 3200-fold reduction in NAD:elongation factor 2 ADP-ribosyltransferase activity, as estimated by assays with an active fragment derived from the toxin by digestion with thermolysin. NAD glycohydrolase activity was reduced somewhat less, by a factor of 50, and photoaffinity labeling with NAD by a factor of 2. We detected less than 2-fold change in the values of KM for NAD or elongation factor 2 and no change in KD for NAD, as determined by quenching of protein fluorescence. The drastic reduction of ADP-ribosyltransferase activity therefore results primarily from an effect of the mutation on kcat, implying that Glu-553 plays an important and possibly direct role in catalyzing this reaction. The effects of the E553D mutation are similar to those of the E148D mutation in diphtheria toxin, supporting the notion that these two Glu residues perform the same function in their respective toxins.