PubMed · 7167361
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D B Wake. 1982. Functional and evolutionary morphology.. https://doi.org/10.1353/pbm.1982.0059
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We present the first genome-wide study of recent evolution in Culex pipiens species complex focusing on the genomic extent, functional targets and likely causes of global and local adaptations. We resequenced pooled samples of six populations of C. pipiens and two populations of the outgroup Culex torrentium. We used principal component analysis to systematically study differential natural selection across populations and developed a phylogenetic scanning method to analyse admixture without haplotype data. We found evidence for the prominent role of geographical distribution in shaping population structure and specifying patterns of genomic selection. Multiple adaptive events, involving genes implicated with autogeny, diapause and insecticide resistance were limited to specific populations. We estimate that about 5-20% of the genes (including several histone genes) and almost half of the annotated pathways were undergoing selective sweeps in each population. The high occurrence of sweeps in non-genic regions and in chromatin remodelling genes indicated the adaptive importance of gene expression changes. We hypothesize that global adaptive processes in the C. pipiens complex are potentially associated with South to North range expansion, requiring adjustments in chromatin conformation. Strong local signature of adaptation and emergence of hybrid bridge vectors necessitate genomic assessment of populations before specifying control agents.
The characteristics of biological systems of adaptation are developed from the principle that the manifestations of life are modified by and must conform with their environment in order to enable organismic persistence. The two roles of the environment, termed "modifying" and "adaptive", give rise to the distinction of three elementary and sequentially coupled subsystems characterizing the adaptational system: the modifying system, comparator system, and state regulation system. The third system determines which state alterations are required for adaptation of manifestations (responses) to the demands of the adaptive environment. Adaptational valuation is introduced as a measure of adaptedness of response to adaptive environment. The dynamical aspect of adaptation is shown to be completely described by the timing of feedback. Discrete and continuous forms of adaptation can thus be treated on the same conceptional basis. All steps of the generic system formulation are illustrated with the help of a simple model with additive effects and linear state regulation. The system representation is used to demonstrate how basic intuitive conceptions, such as adaptational lag or adaptational capacity, can be made amenable to precise analysis. Another demonstration concerns recognition of adaptational clues resulting from the distinction between the two environmental classes, modifying and adaptive. Among these clues are challenges of low correlation between the two classes to adaptational systems and the specification of questions of the evolution of phenotypic plasticity.
Tirapazamine (TPZ, 3-amino-1,2,4-benzotriazine 1,4-di-N-oxide, SR 4233, WIN 59075) is a bioreductive antitumor agent with a high selective toxicity for hypoxic cells. The selective hypoxic toxicity of TPZ results from the rapid reoxidation of the one-electron reduction product, the TPZ radical, in the presence of molecular oxygen with the concomitant production of superoxide radical. Under hypoxia the TPZ radical kills cells by causing DNA double-strand breaks and chromosome aberrations. However, the mechanism of aerobic cytotoxicity is still a matter of debate. In this study, we investigated the mechanism of aerobic cytotoxicity by adapting human lung adenocarcinoma A549 cells to aerobic TPZ exposure and characterizing the changes associated with drug resistance. The adapted cells were resistant to aerobic TPZ exposures (with dose-modifying factors of up to 9.2), although hypoxic sensitivity was largely unchanged. Relative to the parental A549 cell line, adaptation to continuous aerobic TPZ exposure resulted in increased levels of manganese superoxide dismutase (up to 9.4-fold), moderate increases in glutathione reductase (up to 2.1-fold), and loss of both quinone oxidoreductase (DT-diaphorase) activity and NADPH cytochrome P450 reductase activity. There was essentially no change in the activity of the cytoplasmic form of superoxide dismutase (CuZnSOD), catalase, or glutathione peroxidase. The increased activity of antioxidant enzymes in the resistant cell lines (in particular MnSOD) strongly suggests that reactive oxygen species are, in large part, responsible for the toxicity of TPZ under aerobic conditions, and is consistent with aerobic and hypoxic drug cytotoxicity resulting from different mechanisms.