Follicular growth,differentiation and atresia

Only limited numbers of primordial follicles in mammalian ovary grow and differentiate to reach the stage of dominate follicles and ovulate. 99% of the follicles in the ovary undergo atresia at various stages of development.Regulation of follicular growth, development and atresia is a complex process and involves interactions between endocrine factors and intraovarian regulators. This review summarized: i ) FSH may not be a survival factor in regulating slow-growing preantral follicles. Some locally produced growth factors, activin and orphan receptors might play a more important role at this stage, ii ) Estrogen, activin/inhibin and follistatin coordinate with FSH to regulate and control follicle differentiation, iii) There are two types of follicular atresia induced by apoptosis which originates from GC or oocyte, respectively. Early translation of tPA mRNA into tPA protein in oocyte may be associated with oocytea apoptosis.     

活性碳,碳黑,石墨与金刚石晶种的生长

介绍了活性碳、碳黑与石墨在过剩压驱动下金刚石晶种的生长．对两种无定形碳以及石墨在触媒中的分散溶解输运与再结晶进行了观察，对活性碳、碳黑在金刚石晶种生长中的机理作了探索性的讨论．三种碳片上的晶种均有明显长大，无定形碳作晶种生长的碳源是可行的     

寿命不确定性、生育率与随机经济增长

在生育率内生的情况下,引入寿命不确定性,建立生育率、死亡概率和经济增长率的随机动态模型,在本文中的假设下,当风险厌恶系数足够大时,生育率关于死亡概率的函数曲线是倒U型的,经济增长率关于死亡概率的函数曲线则是U型的,此时个人福利存在一个最优值;当风险厌恶系数较小时,生育率与死亡率是正相关的,经济增长率与死亡概率也是正相关的,另外,死亡风险和抚养成本的大小对生育率和经济增长也有不同的影响.     

信息不对称、金融中介与经济增长

金融中介能有效地将社会闲置资金配置到资金短缺部门,促进经济增长。在借鉴新古典经济学和内生经济增长理论的基础上,将金融中介作为经济增长的外生变量,建立相应的经济数学动态模型,以其分析物质生产部门利润和创新的价值、金融中介的最优化问题、信贷市场出清和银行及物质生产企业的就业情况,并对中国金融业的发展提出了相关的政策建议。     

Capillary endothelial cells express basic fibroblast growth factor, a mitogen that promotes their own growth

Angiogenesis, the formation of new capillaries, which is observed in embryonic and injured tissue and is particularly prominent in the vicinity of solid tumours, involves the migration and proliferation of capillary endothelial cells. It is probably triggered by agents, such as basic fibroblast growth factor (bFGF), thought to be released from tissues adjacent to proliferating capillaries. As well as being a potent inducer of cell division in capillary endothelial cells in vitro, bFGF can act as an angiogenic agent in vivo. It is present in a wide variety of richly vascularized tissues including brain, pituitary, retina, adrenal gland, kidney, corpus luteum, placenta and various tumours. So far, however, the normal bFGF-producing cell species in these tissues have not been identified. We report here that capillary endothelial cells express the bFGF gene, that they produce and release bFGF and that bFGF derived from them can stimulate the proliferation of capillary endothelial cells. We conclude that bFGF can act as a self-stimulating growth factor for capillary endothelial cells, and that it is possible that the formation of new capillaries is induced by capillary endothelial cells themselves.     

Ricci曲率,共轭半径和大体积增长

研究了一类具有非负Ricci曲率和大体积增长的完备非紧黎曼流形.证明了在共轭半径有正下界以及流形M上测地球与欧氏空间上单位球的体积增长相差不大的条件下,流形M微分同胚于Rn.该文将体积增长条件改进,推广了M.Do.Carmo和C.Xia的结果.     

社会地位、财政政策和随机经济增长

在一个具有生产性政府花费的随机经济增长模型中,把体现社会地位的财富引入消费者效用函数．在政府发行债券的情况下,利用随机最优化方法,确定了均衡状态下的消费一财富比、期望经济增长率以及资本和债券份额．讨论了社会地位、财政政策和随机扰动对经济增长的影响．同时,考察了社会地位对财政政策的制定是否有影响的问题．     

Rac GTPases control axon growth, guidance and branching

Growth, guidance and branching of axons are all essential processes for the precise wiring of the nervous system. Rho family GTPases transduce extracellular signals to regulate the actin cytoskeleton. In particular, Rac has been implicated in axon growth and guidance. Here we analyse the loss-of-function phenotypes of three Rac GTPases in Drosophila mushroom body neurons. We show that progressive loss of combined Rac1, Rac2 and Mtl activity leads first to defects in axon branching, then guidance, and finally growth. Expression of a Rac1 effector domain mutant that does not bind Pak rescues growth, partially rescues guidance, but does not rescue branching defects of Rac mutant neurons. Mosaic analysis reveals both cell autonomous and non-autonomous functions for Rac GTPases, the latter manifesting itself as a strong community effect in axon guidance and branching. These results demonstrate the central role of Rac GTPases in multiple aspects of axon development in vivo, and suggest that axon growth, guidance and branching could be controlled by differential activation of Rac signalling pathways.     

尿素和硼及生长调节剂对荔枝花粉萌发与生长的影响

25度条件下,在荔枝花粉萌发培养基上添加0．1％－0．4％的尿素,0．1－1．5％的硼酸及0．1－1．0mg.L^-1的萘乙酸均不同程度地促进花粉萌发与花粉管生,5－50mg.L^-1乙烯对花粉的萌发与花粉管生长则有抑制作用,抑制程度与其浓度呈正相关,在1－5mg.L^-1的BA下,花粉萌发率下降,但花粉管生长受促,25mg.L^-1BA可显著抑制花粉的萌花与生长,三个荔枝品种花粉萌发对温度较敏感,18度时不萌发。     

一株多氯联苯降解菌的分离鉴定及其生长条件优化

文章从垃圾渗滤液中分离得到一株具有降解多氯联苯能力的菌株,对其进行16srDNA序列分析,确定为枯草杆菌(Bacillus subtilis),编号为WF1。实验考查了该菌的生长和降解特性,分别研究pH值、温度、装液量等因素对菌株降解能力的影响;并通过正交试验对其生长条件进行优化,结果表明菌株适宜生长条件与降解条件基本一致。其中pH值为最主要影响因素,温度和摇床转速为次要因素,装液量为不重要因素。pH值7.0、温度35℃、摇床转速150r/min为菌株的适宜生长条件。     

Structure, expression and function of a schwannoma-derived growth factor

During the development of the nervous system, cells require growth factors that regulate their division and survival. To identify new growth factors, serum-free growth-conditioned media from many clonal cell lines were screened for the presence of mitogens for central nervous system glial cells. A cell line secreting a potent glial mitogen was established from a tumour (or 'schwannoma') derived from the sheath of the sciatic nerve. The cells of the tumour, named JS1 cells, were adapted to clonal culture and identified as Schwann cells. Schwann cells secrete an autocrine mitogen and human schwannoma extracts have mitogenic activity on glial cells. Until now, neither mitogen has been purified. Here we report the purification and characterization of a mitogenic molecule, designated schwannoma-derived growth factor (SDGF), from the growth-conditioned medium of the JS1 Schwann cell line. SDGF belongs to the epidermal growth factor family, and is an autocrine growth factor as well as a mitogen for astrocytes, Schwann cells and fibroblasts.