Mammalian cytochrome b

Digestion of a preparation of cytochromes b and c(1) with pancreatic protease followed by ammonium sulfate precipitation resulted in a soluble cytochrome b uncontaminated by cytochrome C(l). This preparation, which was free of succinic dehydrogenase and cytochrome oxidase activity, had an estimated deltaE(1 cm)(1g/ml) of 102 for its alpha-peak. In the reduced form absorption maxima were found at 560 to 562, 530 to 532, and 427 to 428 mmicro, and in the oxidized form, at 413 mmicro.     

Mammalian scent marking

Mammals mark frequently in any situation where they are both intolerant of and dominant to other members of the same species. In other words, they mark when they are likely to attack another member of the same species, and are likely to win if they do attack. Such a situation occurs, as Hediger (13) pointed out, in connection with territoriality but it also occurs in other kinds of social systems. Frequent, vigorous marking occurs at times when there is reason to infer that the animal is motivated to aggression. The effects of marks and marking upon other individuals are poorly understood. Many species mark with more than one source of scent in response to one stimulus or set of stimuli.     

Mammalian neural stem cells

Neural stem cells exist not only in the developing mammalian nervous system but also in the adult nervous system of all mammalian organisms, including humans. Neural stem cells can also be derived from more primitive embryonic stem cells. The location of the adult stem cells and the brain regions to which their progeny migrate in order to differentiate remain unresolved, although the number of viable locations is limited in the adult. The mechanisms that regulate endogenous stem cells are poorly understood. Potential uses of stem cells in repair include transplantation to repair missing cells and the activation of endogenous cells to provide "self-repair. " Before the full potential of neural stem cells can be realized, we need to learn what controls their proliferation, as well as the various pathways of differentiation available to their daughter cells.     

哺乳动物性别控制的研究进展

性别控制是一项能显著提高养殖业经济效益的生物工程技术。目前哺乳动物的性别控制的方法很多,主要是通过XY精子分离和早期胚胎性别鉴定来实现。在生产中,还经常采用其它性别控制的方法,如:受精时间控制法、阴道pH值调节法和营养调节法等。就性别决定的机理、XY精子分离以及早期胚胎性别鉴定的几种方法进行了综述,并对性别控制存在的问题及发展前景进行了讨论。     

哺乳动物脑垂体研究进展

脑垂体 (Hypophysis) ,又称垂体腺或垂体 ,结构复杂 ,是机体内分泌中枢的重要组成部分 ,可分泌多种激素 ,在中枢神经的控制下 ,调节其它内分泌激素的合成和分泌 ,直接或间接地影响高等哺乳动物的各种生理活动。不断探索其在不同条件下的大体解剖学和组织学特征 ,对哺乳动物的一系列生理活动变化及机制的研究有重要的指导价值。1　哺乳动物垂体的发生和发育垂体包括腺垂体 (Adenohypophysis)和神经垂体 (Neurohypophysis)两部分 ,二者的发生和发育被认为是机体其他器官发育的启动密码[40 ] 。传统的胚胎学认为垂体是由外胚层分化而来 ,腺垂…     

Mammalian oocytes: X chromosome activity

The glucose-6-phosphate dehydrogenase and lactate dehydrogenase contents of oocytes from XO and XX female mice have been measured. The activity of the former in the oocytes of XO mice is half of that in the oocytes of XX mice, whereas the lactate dehydrogenase activities in the two groups of ova are the same. These results indicate that glucose-6-phosphate dehydrogenase from a mouse oocyte is an X-linked enzyme, that its synthesis occurs in the oocyte and is dosage dependent, and that inactivation of the X chromosome does not occur in the mouse oocyte.     

哺乳动物抗菌肽的研究

抗菌肽在宿主抵抗病原微生物感染中起重要作用，是天然免疫的重要介质，其通过改变细菌细胞膜的通透性而发挥抗菌作用，这不同于抗生素通过阻断大分子生物合成的作用机理，因而致病菌不易对其产生耐药性，下面就几种哺乳动物抗菌肽特性，抗菌机理，基因工程研究，应用前景及存在问题进行综述。