A Microarray-Based Analysis Reveals that a Short Photoperiod Promotes Hair Growth in the Arbas Cashmere Goat

Many animals exhibit different behaviors in different seasons. The photoperiod can have effects on migration, breeding, fur growth, and other processes. The cyclic growth of the fur and feathers of some species of mammals and birds, respectively, is stimulated by the photoperiod as a result of hormone-dependent regulation of the nervous system. To further examine this phenomenon, we evaluated the Arbas Cashmere goat (Capra hircus), a species that is often used in this type of research. The goats were exposed to an experimentally controlled short photoperiod to study the regulation of cyclic cashmere growth. Exposure to a short photoperiod extended the anagen phase of the Cashmere goat hair follicle to increase cashmere production. Assessments of tissue sections indicated that the short photoperiod significantly induced cashmere growth. This conclusion was supported by a comparison of the differences in gene expression between the short photoperiod and natural conditions using gene chip technology. Using the gene chip data, we identified genes that showed altered expression under the short photoperiod compared to natural conditions, and these genes were found to be involved in the biological processes of hair follicle growth, structural composition of the hair follicle, and the morphogenesis of the surrounding skin appendages. Knowledge about differences in the expression of these genes as well as their functions and periodic regulation patterns increases our understanding of Cashmere goat hair follicle growth. This study also provides preliminary data that may be useful for the development of an artificial method to improve cashmere production by controlling the light cycle, which has practical significance for livestock breeding.     

酸敏感离子通道与脑梗死

急性脑梗死约占全部脑卒中的70%,病死率和致残率高,且极易复发。但目前针对急性脑梗死在时间窗内溶栓、抗凝等治疗手段不能从根本上切实有效地修复受损脑组织,且伴有出血等风险。寻找脑梗死形成发展的原因并予以治疗迫在眉睫。酸中毒是引起缺血性脑损伤的重要机制。大量实验研究表明,酸中毒能加重神经元的缺血性损伤,且其梗死面积与酸中毒的程度直接相关。但缺血产生的酸中毒如何引起神经元损伤的确切机制尚不明确。最近研究发现酸中毒能激活一种在中枢及周围神经中广泛存在的膜通道,即酸敏感离子通道,它对Ca2+通透,能引起细胞内Ca2+超载,同时能激活胞内酶引起细胞内蛋白质、脂类及核酸的降解,加重缺血后脑损伤。本文就酸敏感离子通道1a与脑梗死做一综述。     

Analyzing the normal mode dynamics of macromolecules by the component synthesis method: Residue clustering and multiple-component approach

A study of the component synthesis method (CSM) for analyzing the normal mode dynamics of macromolecules is reported. The procedure involves a reduction of the dimensions of the normal mode problems for large molecular systems and the accurate extraction of the low-frequency modes. A macromolecule is divided into small components based on a hierarchical clustering of the residues in the structure. Interactions between coupled components are treated by the method of static correlation. The normal modes of the components are obtained first, and a fraction of the low-frequency normal modes of the components under mutual correlations are then used as a reduced basis for solving for the normal modes of the whole molecule. Multiple components are introduced for large macromolecules so that the dimensions of the eigenvalue problems at the component level are small. The method is applied to the protein crambin. In test calculations in which the dimensions of the eigenvalue equations are reduced to 1/6 of their natural size, the errors in the normal mode frequencies calculated by the CSM procedure are only about 1–2% when compared with the exact values. The rms fluctuations of all atoms in crambin calculated by the CSM procedure are basically identical to the exact results. The CSM procedure is shown to be accurate for calculating the normal modes of large macromolecules with a significant reduction of the size of the problem. © 1994 John Wiley & Sons, Inc.     

The FER gene is evolutionarily conserved and encodes a widely expressed member of the FPS/FES protein-tyrosine kinase family.

We have recently isolated human and rat cDNAs (designated FER and flk, respectively) which encode nonreceptor protein-tyrosine kinases which are very similar to one another and related in sequence and domain structure to the c-fps/fes gene product. We show that FER and flk are human and rat counterparts of an evolutionarily conserved gene, hereafter termed FER regardless of species. The human and rat FER genes encode a widely expressed 94-kilodalton protein-tyrosine kinase which is antigenically related to the fps/fes protein-tyrosine kinase. The structural and antigenic similarities between the FER and fps/fes proteins suggest that they are members of a new family of nonreceptor protein-tyrosine kinases.     

Modeling DNA supercoils and knots with B-spline functions

A method is offered to model the complex trajectories of closed circular DNA supercoils and knots. The trajectories are approximated by polygons and analytical expressions of the curves are generated from the polygons with B-spline functions. The resulting curves are used to evaluate the writhe and elastic energy of a series of interrelated supercoils, and to generate detailed atomic models of the deformed double helix.