PubMed · 5732370
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W Höfler. 1968-07-31. [Heat acclimatization].. https://pubmed.ncbi.nlm.nih.gov/5732370/
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Understanding the genetic bases and modes of adaptation to current climatic conditions is essential to accurately predict responses to future environmental change. We conducted a genome-wide scan to identify climate-adaptive genetic loci and pathways in the plant Arabidopsis thaliana. Amino acid-changing variants were significantly enriched among the loci strongly correlated with climate, suggesting that our scan effectively detects adaptive alleles. Moreover, from our results, we successfully predicted relative fitness among a set of geographically diverse A. thaliana accessions when grown together in a common environment. Our results provide a set of candidates for dissecting the molecular bases of climate adaptations, as well as insights about the prevalence of selective sweeps, which has implications for predicting the rate of adaptation.
Isolated microtubule proteins from the cold-adapted fish, Atlantic cod (Gadus morhua), assemble at temperatures between 8 and 30 degrees C, while avian and mammalian microtubules normally do not assemble at temperatures below 20 degrees C. Tubulin, the main component in microtubules, is expressed as many isotypes. Microtubules with different isotype composition have been shown to have different dynamic properties in vitro. Our hypothesis was that cold-tolerance of microtubules is caused by tubulin isotypes that differ in the primary sequence compared to mammalian tubulins. Here we show that transfection of human HepG2 cells with cod beta-tubulin induced cold-adaptation of the endogenous microtubules. Incorporation of one single tubulin isotype can induce cold-tolerance to cold-intolerant microtubules. Three cod beta-tubulin isotypes were tested and two of these (beta1 and beta2) transferred cold-tolerance to HepG2 microtubules, thus not all cod beta-tubulins were able to confer cold-stability.
The structure-function relationships of fast skeletal myosin isoforms remain poorly understood. To shed some light, we constructed chimeric myosins comprised of Dictyostelium myosin heavy chain backbone with carp loop sequences and analyzed their functional properties. A loop 2-10 chimeric myosin having the loop 2 sequence of the fast skeletal isoform predominantly expressed in carp acclimated to 10 degrees C showed V(max) in actin-activated Mg(2+)-ATPase activity 1.4-fold higher than a loop 2-30 chimera constructed from the loop 2 sequence of the dominant isoform in carp acclimated to 30 degrees C. These two chimera exhibited no significant differences in sliding velocity of actin filaments in in vitro motility assay. Contrastingly, both loop 1-associated chimeras, loop 1-10 and loop 1-30, did not differ in both ATPase activity and in sliding velocity of actin filaments.