钠钾泵是怎样发现的

钠钾泵是人类发现的第1个离子泵,具有里程碑的意义。回顾了人类对钠钾泵的认识过程;从科学家发现细胞内、外液之间Na^＋、K^＋浓度的差异、静息电位和动作电位,提出有关学说和发现钠钾泵作了追踪溯源的介绍。主要从静息电位及“膜学说”、动作电位及“离子学说”、“钠泵”假设与钠钾泵的发现3个方面作了论述。     

Plant stress proteins of the thaumatin-like family discovered in animals

Thaumatin-like proteins (TLPs) are polypeptides of about 200 residues synthesized by plants in response to fungal infection. In addition to the exceptionally strong sweet taste exhibited by some members, they are also reported to be endowed with endo-beta-1,3-glucanase activity and alpha-amylase inhibiting properties. However, the detailed mechanism of their antifungal action is not completely understood. So far, TLPs have only been described in plants, with several members of the family expressed in the same species. Here, for the first time in animals, we report the identification of two genes encoding members of the thaumatin-like proteins family in the desert locust Schistocerca gregaria and show their expression in different parts of the body. Southern blot and Western blot experiments revealed the presence of orthologous genes and their expression products in the related species Locusta migratoria. A search through the available genomes yielded similar sequences in the nematode Caenorhabditis but not in Drosophila and other insects. A three-dimensional model of S. gregaria TLP suggests a glucanase function. As in plants, TLPs could play a defense role in insects against pathogens.     

Chinese Mongolian horses may retain early domestic male genetic lineages yet to be discovered

The Mongolian horse represents one of the most ancient extant horse populations. In this study we determined the male‐specific region of the Y chromosome (MSY) haplotype distribution in 60 Chinese Mongolian horses representing five distinct populations. Cosmopolitan male lineages were predominant in horses from one improved (Sanhe), one Chinese Mongolian subtype (Baicha Iron Hoof) and one indigenous (Abaga Black) population. In contrast, autochthonous Y chromosome diversity was evident among the two landrace populations (Wushen and Wuzhumuqin), as the majority of their MSY haplotypes were situated at root nodes in a network. Our results also suggest gene flow between Chinese Mongolian and Arabian horses, as an appreciable number of Wuzhumuqin horses carried haplotypes that are typically observed in Arabian horses. Although most horses carried modern haplotypes as a direct result of recent breed improvement, authentic Chinese Mongolian horses retain an ancient signature of paternal lineages that has not previously been described in extant horse populations. Therefore, further characterization of MSY variation in these populations will be important for the discovery of lost diversity in modern domestic horses and also for understanding the evolutionary history of equine paternal lineages.     

Spiteful soldiers and sex ratio conflict in polyembryonic parasitoid wasps

The existence of spiteful behaviors remains controversial. Spiteful behaviors are those that are harmful to both the actor and the recipient, and they represent one of the four fundamental types of social behavior (alongside selfishness, altruism, and mutual benefit). It has generally been assumed that the conditions required for spite to evolve are too restrictive, and so spite is unlikely to be important. This idea has been challenged in recent years, with the realization that localized competition can relax the conditions required for spite to evolve. Here we develop a theoretical model for a prime candidate for a spiteful behavior, the production of the sterile soldier caste in polyembryonic wasps. Our results show that (a) the biology of these soldiers is consistent with their main role being to mediate conflict over the sex ratio and not to defend against competitors and (b) greater conflict will occur in more outbred populations. We also show that the production of the sterile soldier caste can be classed as a spiteful behavior but that, to an extent, this is merely a semantic choice, and other interpretations such as altruism or indirect altruism are valid. However, the spite interpretation is useful in that it can lead to a more natural interpretation of relatedness and facilitate the classification of behaviors in a way that emphasizes biologically interesting differences that can be empirically tested.