Molecular characterization of an ethephon-induced Hsp70 involved in high and low-temperature responses in Hevea brasiliensis.

Hsp70s have been shown to play important roles in helping cells to cope with adverse environments, especially in response to temperature. In this study a novel ethephon-induced Hsp gene, designated as HbHsp70, was isolated from Hevea brasiliensis. The HbHsp70 cDNA contained a 1965 bp open reading frame encoding 655 amino acids. The deduced HbHsp70 protein showed high identities to Hsp70s from other plants. Expression studies revealed more significant accumulation of HbHsp70 transcripts in leaves and stems than in roots, barks and latex. The transcription of HbHsp70 was induced by ethephon, heat treatment and low temperature stress, whereas jasmonic acid had little effects. Recombinant HbHsp70 was expressed in Escherichia coli and purified by Ni-NTA affinity chromatography. Measuring the light scattering of luciferase (Luc) revealed that HbHsp70 prevents the aggregation of luc during high-temperature stress. In vitro experiments showed that HbHsp70 had protective functions not only against heat stress but also against chilling stress. All these data suggest that HbHsp70 may play roles in responses to heat shock and low temperature in H. brasiliensis.

[Maximum entropy principle and population genetic equilibrium].

A general mathematic model of population genetic equilibrium was constructed based on the maximum entropy principle. We proved that the maximum entropy probability distribution was equivalent to the Hardy-Weinberg equilibrium law. A population reached genetic equilibrium when the genotype entropy of the population reached the maximal possible value. In information theory, the entropy or the information content is used to measure the uncertainty of a system. In population genetics, we can use entropy to measure the uncertainty of the genotype of a population. The agreement of the maximum entropy principle and the hardy-Weinberg equilibrium law indicated that random crossing is an irreversible process, which increases the genotype entropy of the population, while inbreeding and selection decrease the genotype entropy of the population. In animal or plant breeding, we often use selection and/or inbreeding to decrease the entropy of a population, and use intercrossing to increase the entropy of the population. In this point of view, breeding is actually regulating the entropy of population. By applying the basic principle of informatics in population genetics, we revealed the biological significance of the genotype entropy and demonstrated that we can work over population genetic problems with the principles and methods of informatics and cybernetics.