Thermodynamic and sequential characteristics of phase separation and droplet formation for an intrinsically disordered region/protein ensemble

Liquid–liquid phase separation (LLPS) of some IDPs/IDRs can lead to the formation of the membraneless organelles in vitro and in vivo, which are essential for many biological processes in the cell. Here we select three different IDR segments of chaperon Swc5 and develop a polymeric slab model at the residue-level. By performing the molecular dynamics simulations, LLPS can be observed at low temperatures even without charge interactions and disappear at high temperatures. Both the sequence length and the charge pattern of the Swc5 segments can influence the critical temperature of LLPS. The results suggest that the effects of the electrostatic interactions on the LLPS behaviors can change significantly with the ratios and distributions of the charged residues, especially the sequence charge decoration (SCD) values. In addition, three different forms of swc conformation can be distinguished on the phase diagram, which is different from the conventional behavior of the free IDP/IDR. Both the packed form (the condensed-phase) and the dispersed form (the dilute-phase) of swc chains are found to be coexisted when LLPS occurs. They change to the fully-spread form at high temperatures. These findings will be helpful for the investigation of the IDP/IDR ensemble behaviors as well as the fundamental mechanism of the LLPS process in bio-systems.     

Population genetics strategies to characterize long-distance dispersal of insects

Population genetics strategies offer an alternative and powerful approach for obtaining information about long-distance movement, and have been widely used for examining patterns and magnitude of insect dispersal over geographic and temporal scales. Such strategies are based on the principle that genetic divergence between local populations reflects the interplay between genetic drift and gene flow, and thus can function as an indicator of dispersal capacity. Relatively new approaches for inferring population history are widely applicable for documenting introduction routes of invasive or quarantine species. These approaches are based on genetic variability calculated from changes in gene frequency of subpopulations, measured using molecular genetic markers. Inferences from population genetics can supplement and corroborate conventional observational approaches for characterizing insect dispersal and have provided important clues to many questions raised in the field of behavior and ecology of insects. Here, we summarize our work on the boll weevil as a case study to illustrate the kinds of information on dispersal capacity and dispersal patterns that can be obtained from population genetics techniques that would be difficult or impossible to acquire in other ways. Then we provide examples of how the molecular markers and population genetics tools have been applied to answer immediate questions of relevance to eradication program managers. Though the latter are idiosyncratic to this particular pest, they demonstrate the kinds and range of problems that can be addressed in other systems through application of population genetics strategies.     

Reactivation of Horseradish peroxidase in organic solvent using extraction

A novel extraction method was developed aiming at increasing the stability of enzymes in organic solvent media. Horseradish peroxidase (HRP), inactivated in a tetrahydrofuran (THF)/water (1:1, v/v), regained and maintained its activity when HRP was extracted by adding a THF/benzene mixture to the original solution. However, the HRP activity was drastically lowered in the enzyme-free blank solution that had been formed by employing the same extraction procedure. As a result, the reactivation after the extraction is believed to depend on enzyme history, and might be arisen from an irreversible structural change of the enzyme.     

Pediatrics: New Antiepileptic Drugs for the Treatment of Childhood Epilepsies

The Council on Scientific Affairs of the California Medical Association presents the following epitomes of progress in pediatrics. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and clinical importance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, and scholars to stay abreast of progress in medicine, whether in their own field of special interest or another.The epitomes included here were selected by the Advisory Panel to the Section on Pediatrics of the California Medical Association, and the summaries were prepared under the direction of Susan B. Conley, MD, and the panel.     

Agriculture driving male expansion in Neolithic Time

正Dear Editor,Dispute between agriculture and initial population expansion in Neolithic Time has been in suspense for a long time.Agriculture first appeared in the Fertile Crescent of West Asia about 11–12 thousand years ago(kya),with domesticating few wild plant and animal species.There is also evidence of the cultivation of rice and millet in Yangtze and Yellow River Basins of China approximately 9 kya.During the subsequent times between 9 and 4 kya,agriculture arose     

Activity of protein kinase C during the differentiation of chick limb bud mesenchymal cells

Abstract. To investigate the relationship between protein kinase C (PKC) and chondrogenesis, PKC activity was assayed in cultures of stage 23/24 chick limb bud mesenchymal cells under various conditions. PKC activities of cytosolic and particulate fractions were low in 1 day cultured cells. As chondrogenesis proceeds, cytosolic PKC activity increased more than twofold, while that of the particulate fraction increased only slightly. Three days' treatment of cultures with phorbol-12-myristate-13-acetate (PMA, 5 × 10⁻⁸ M ) inhibited chondrogenesis judged by the accumulation of Alcian blue bound to the extracellular matrix and depressed PKC activity in cytosolic fraction. When cells were grown for 3 days in control medium after 3 days' treatment with PMA, chondrogenesis resumed and PKC activity recovered to normal values. PKC activity in cultures plated at low density (2 × 10⁶ cells/ml) where chondrogenesis is reduced was as low as that in 1 day cultured cells plated at high density (2 × 10⁷ cells/ml) or that in PMA treated cells. On the other hand, staurosporine promoted chondrogenesis without affecting PKC activity. Furthermore, reversal of PMA's inhibitory effect on chondrogenesis by staurosporine was not accompanied by recovery of PKC activity. These data indicate that increases in PKC activity is closely related to chondrogenesis and that PMA inhibits chondrogenesis by depressing PKC. However, staurosporine's enhancing effect on chondrogenesis is not related to PKC activity.