On the thermal unfolding character of globular proteins

A theoretical model is presented to study the stepwise thermal unfolding of globular proteins using the stabilizing/destabilizing characters of amino acid residues in protein crystals. A multiple regression relation connecting the melting temperature and the amounts of stabilizing and destabilizing groups of residues in a protein, when used for the thermal behavior of peptide segments, provides reliable results on the stepwise unfolding nature of the protein. In ribonuclease A, the shell residues 16–22 are predicted to unfold earlier in the temperature range 30–45°C; the -sheet structures undergo thermal denaturation as a single cooperative unit and there is evidence indicating the segment 106–118 as a nucleation site. In ribonuclease S, the S-peptide unfolds earlier than S-protein. The predicted average and the range of melting temperatures, and the folding pathways of a set of globular proteins, agree very well with the experimental results. The results obtained in the present study indicate that (i) most of the nucleation parts possess high relative thermal stability, (ii) the unfolded state retains some residual structure, and (iii) some segments undergo gradual and overlapping thermal denaturation.     

On hygienic and ecological approaches in radiation protection

In this paper the problem of substantiation of one of the basic radiation protection ensurance principle is considered: sufficiency of a man radiation safety ensuring for guaranteed ensuring of radiation safety of the environment living components. This paradigm formulated in ICRP recommendations and is often referred to as hygienic or anthropocentric approach to environment radiation protection is laid down the basis of all national, including Russian, regulations in the field of radiation safety. During the last 5-10 years a lot of papers have been published, in which the hygienic principle of environmental safety ensuring is considered as a matter of dispute and the certain logical basis and the quantitative comparative estimations of human exposure doses and most irradiated vulnerable parts of nature doses are given. Change of one of the main radiation protection paradigms will demand for resolution of the enormously difficult and labor-consuming scientific problems. In the present paper, on the basis of UNSCEAR models of critical population groups dose formation and consistent application of conservativeness principle it is shown that for the ground ecosystems today there is no strong reasons for refusal of a hygienic radiation protection principle for benefit of ecological one.     

On the haemoprotein character of prostaglandin endoperoxide synthetase.

Prostaglandin endoperoxide synthetase is a membrane-bound glycoprotein isolated as a dimer of molecular weight of approximately 129 000 consisting of two identical polypeptide chains. Several research workers have reported that haemin (ferri-protoporphyrin-IX) is required to restore the full enzymic activity of the pure apoprotein. Difference spectroscopy shows association of haemin up to two molecules per polypeptide chain of molecular weight 70 000. Both the cyclooxygenase and the peroxidase activity displayed by the enzyme can be optimally stimulated by similar quantities of haemin. The restored haemin-enzyme complex has a millimolar absorption coefficient at 408 nm of 61 mM-1 . cm-1 per haem. Using this value, the presence of non-haem iron in the enzyme is virtually excluded. These findings and the spectra of the reassociated enzyme-haemin complex point to a haemoprotein character. The availability of haemin to the enzyme might play a regulating r?le in its action.     

On the role of hypotheses in science

Scientific research progresses by the dialectic dialogue between hypothesis building and the experimental testing of these hypotheses. Microbiologists as biologists in general can rely on an increasing set of sophisticated experimental methods for hypothesis testing such that many scientists maintain that progress in biology essentially comes with new experimental tools. While this is certainly true, the importance of hypothesis building in science should not be neglected. Some scientists rely on intuition for hypothesis building. However, there is also a large body of philosophical thinking on hypothesis building whose knowledge may be of use to young scientists. The present essay presents a primer into philosophical thoughts on hypothesis building and illustrates it with two hypotheses that played a major role in the history of science (the parallel axiom and the fifth element hypothesis). It continues with philosophical concepts on hypotheses as a calculus that fits observations (Copernicus), the need for plausibility (Descartes and Gilbert) and for explicatory power imposing a strong selection on theories (Darwin, James and Dewey). Galilei introduced and James and Poincaré later justified the reductionist principle in hypothesis building. Waddington stressed the feed-forward aspect of fruitful hypothesis building, while Poincaré called for a dialogue between experiment and hypothesis and distinguished false, true, fruitful and dangerous hypotheses. Theoretical biology plays a much lesser role than theoretical physics because physical thinking strives for unification principle across the universe while biology is confronted with a breathtaking diversity of life forms and its historical development on a single planet. Knowledge of the philosophical foundations on hypothesis building in science might stimulate more hypothesis-driven experimentation that simple observation-oriented “fishing expeditions” in biological research.     

植物园与植物园学

随着全世界植物园数量的增加、功能和转变和我学科的综合,需要发展植物园学,以引导植物园的发展。植物园学主要包括10个方面的内容：1）植物园的性质、任务和功能;2）历史;3）规划设计;4）物种保护,尤其是迁地保护;5）活植物收集圃及其管理;6）引种驯化的理论与实践和新经济植物的发掘;7）植物展出的技术与方法;8）城市生物多样性保护和利用;9）环境教育和旅游;10）维护和管理。生物多样性是植物园的核心。美丽的外貌、科学的内涵和人与自然和谐共外的准则是植物园的基本要素。     

On the character of the nuclear membrane-associated DNA of HeLa cells.

The nature of the nascent DNA-membrane complexes isolated from synchronized HeLa cells was examined. It was found that membrane-associated DNA is not the result of repair replication. A study of the stability of the complexes to various degradative agents and enzymes suggest that the DNA is associated with a structure which is composed of a lipoprotein. An examination of the physical structure of this DNA indicates that it might be a "nicked" duplex with a base content similar to that of the bulk DNA.