Native American Oral Traditions: Collaboration and Interpretation.

Native American Oral Traditions: Collaboration and Interpretation. Larry Evers and Barre Toelken. eds. Logan: Utah State University Press, 2001. 264 pp.     

Wnt not, waste not

The molecular signals that regulate the regenerative function of satellite cells in the skeletal muscle remain largely obscure. In this issue of Cell Stem Cell, Brack et al. (2008) report that direct molecular crosstalk between stem cell self-renewal and differentiation pathways determines the timing and efficiency of muscle repair.     

Glycan Evolution in Response to Collaboration,Conflict, and Constraint

Glycans, oligo- and polysaccharides secreted or attached to proteins and lipids, cover the surfaces of all cells and have a regulatory capacity and structural diversity beyond any other class of biological molecule. Glycans may have evolved these properties because they mediate cellular interactions and often face pressure to evolve new functions rapidly. We approach this idea two ways. First, we discuss evolutionary innovation. Glycan synthesis, regulation, and mode of chemical interaction influence the spectrum of new forms presented to evolution. Second, we describe the evolutionary conflicts that arise when alleles and individuals interact. Glycan regulation and diversity are integral to these biological negotiations. Glycans are tasked with such an amazing diversity of functions that no study of cellular interaction can begin without considering them. We propose that glycans predominate the cell surface because their physical and chemical properties allow the rapid innovation required of molecules on the frontlines of evolutionary conflict.     

朝向人类起源与演化研究的共业:古人类学、考古学与遗传学的交叉与整合

对于方兴未艾的现代人类起源与演化问题的研究,目前主要在遗传学、古人类学和旧石器时代考古学三个领域内进行。学者们提出了"多地区进化说"、"连续进化附带杂交说"、"出自非洲说"、"融合说"等观点与假说,有的学说针锋相对,南辕北辙。究其原因,除了相关研究还处于盲人摸象的阶段,只是在局部问题与材料上做分析和解释,尚无法得出全面、能被普遍接受的结论外,由于不同学科存在研究对象、方法和思路的不同,学科间缺少了解、沟通与协作,出现一些学术语言和研究结论不被彼此理解和接受的情况,存在一定的误解与无谓的争论,影响了相互之间的借鉴、互动和成果的共享,进而妨碍了跨学科的整合研究并达成学术共识。其实,每个学科都有自己的特点和不可替代的优势,每个学科也有难以克服的弱点,在解决人类起源与演化这样重大的学术问题上,任何一个学科都不可能包打天下,独享其成。因而,开展相关领域的交流合作,尤其是传统的古人类学、考古学与新兴的分子生物学之间的交叉与协作,明确彼此的关注点、需求和专长,凝练共同的学术问题和目标,整合现有的研究问题、资源与成果并向着共同的学术方向一道前行,是推动相关研究走向深入并破译现代人起源这一重大命题的必要举措。     

Gender differences in leucine, but not lysine, kinetics.

There is a controversy in the literature as to the effects of gender on leucine kinetics. Two research groups found that men oxidize more leucine during exercise, whereas another group showed no gender effects. The purpose of our study was to examine the effects of gender on leucine and, for comparison purposes, lysine kinetics. Our subjects (n = 14) were seven matched pairs of men and women selected for their exercise habits and age. After 1 wk of a standardized diet, they exercised at 50% of maximal O(2) uptake for 1 h. There was an effect of exercise in both genders: an increased leucine oxidation and an attenuation in nonoxidative leucine disposal compared with rest (P < 0.05). Furthermore, our study confirms that there are gender differences in leucine, but not lysine, kinetics. Men had a higher rate of leucine oxidation and a lower rate of nonoxidative leucine disposal during exercise (P < 0.05). For women, a larger proportion of their exercise energy needs came from fat; for men, a greater fraction came from carbohydrate (P < 0.05). We conclude that female exercisers rely to a greater extent on fat as an energy source, thereby using less carbohydrate, amino acid, and protein as a fuel source.