Melanin as a natural germ cell marker for intraspecific transplantation experiments in Ambystoma mexicanum (Urodela,Amphibia)

Summary In urodele amphibians, the lack of a reliable germ cell marker restricts the experimental study of the germ lineage. In the present work, we conducted genetic and histological analyses in order to demonstrate that melanin from oocytes constitutes a germ cell marker available for intraspecific experiments in Ambystoma mexicanum. Then, using this marker, we implanted germ cells from undifferentiated gonads (stage 48) into the blastocoel of host embryos and investigated their fate and determined state. Our results show that, from this stage on, the donor cells do not differentiate into other cell types; therefore, they are restricted in developmental capacity and irreversibly determined as germ cells. On the other hand, exogenous germ cells were found in an isotopic position until the young tail-bud stage, and then were found in an ectopic position; these results suggest that, from the middle tail-bud stage on, an active process contributes to migration of primordial germ cells to the gonadal territory.     

固定化酶的微环境效应—载体离子基团性质的影响

作者合成了阴离子型和阳离子型葡聚糖,以此为载体,用CNBr活化其剩余羟基,固定化了葡萄糖淀粉酶和葡萄糖异构酶。就离子型载体对固定化酶的蛋白载量、最适pH和热稳定性等的影响做了考察。发现固定化酶的蛋白载量不仅与载体的电性质有关,也与酶分子自身的电性质有关。当载体电性质与酶蛋白电性质相反时,固定化酶的蛋白载量增加,热稳定性提高、载体电性质与酶蛋白电性质相同时,固定化酶的蛋白载量不变或下降,其热稳定性不变。作者还发现当离子型载体孔度和体系缓冲液浓度一定时,酶分子能否进入多孔性载体内部,对其最适pH是否变化影响极大。若酶分子仅被连接在载体的外表层,其最适pH不发生变化,反之亦然。作者还观察到当多糖类载体引入氨基或羧基后,大大增强了其抵抗微生物侵蚀的能力。     

染色体辐射效应的微机检测 Ⅱ断片率 微核率与细胞畸变率间的相关性检测

本文继前文后,按照设计的线性回归程序在“IBM—PC/XT”微型计算机上,进一步检测了断片率、微核率与细胞畸变率之间的相关性,肯定了微核测定法,断片测定法可以替代染色体畸变分析法。     

Sex ratio and intrasexual kin competition in mammals

Summary Asymmetries in both intrasexual competition and generation overlap occur in Antechinus (Dasyuridae; Marsupialia). We show that the range of interpopulation variation in the sex ratio of pouch young spans and exceeds the range of sex ratios at birth hitherto recorded from eutherians (Clutton-Brock and Albon 1983). Although postweaning dispersal and male mortality are similar among all Antechinus populations, interpopulation variance in female longevity leads to variable duration of mother/daughter interaction. As this duration increases, parental investment is increasingly biased toward males, supporting the view that local competition among female kin for resources may influence mammalian sex ratios.     

Relationship between bacteriophage T4 and T6 DNA topoisomerases. T6 39-protein subunit is equivalent to the combined T4 39- and 60-protein subunits

T6 DNA topoisomerase has been purified from bacteriophage T6 infected Escherichia coli. Unlike the T4 DNA topoisomerase which has three subunits, it consists of two subunits of molecular weights 75,000 and 51,000. They are the products of T6 genes 39 and 52, respectively. The purified T6 enzyme can stimulate in vitro T6 DNA replication. It has an ATP-dependent DNA relaxation activity similar to the T4 enzyme. Either ATP or dATP can be used in both reactions. Using a "Western blotting" and radioimmuno-detection methods, we show that T6 39 subunit contains protein sequences specified by both the T4 39 and 60 genes. The 52-proteins of both phages appear to be identical. The T4 and T6 topoisomerase genes represent a naturally occurring example of gene separation or fusion.     

人粒细胞集落刺激因子（hG－CSF）cDNA3′－UTR对其表达的影响

利用人粒细胞集落刺激因子（ｈＧ－ＣＳＦ）ｃＤＮＡ３′端非翻译区（３′－ＵＴＲ）中存在的ＤｒａⅠ酶切位点,通过部分酶切与完全酶切,删除３′－ＵＴＲ不同长度,构建了四种ｈＧ－ＣＳＦｃＤＮＡ瞬时重组表达质粒。转染ＣＯＳ－７细胞后,生物活性测定结果提示,ｈＧ－ＣＳＦｃＤＮＡ３′－ＵＴＲ对其表达起负调控作用,其关键性序列位于紧接终止密码子ＴＧＡ下游的６５ｂｐ范围内,３′－ＵＴＲ对ｈＧ－ＣＳＦｃＤＮＡ表达的影响与转录水平的差别有一定关系。     

Research Progress on Anti-Inflammatory Mechanisms of Black Ginseng

In recent years, black ginseng, a new type of processed ginseng product, has attracted the attention of scholars globally. Ginsenoside and ginseng polysaccharide, the main active substances of black ginseng, have been shown to carry curative effects for many diseases. This article focuses on the mechanism of their action in anti-inflammatory response, which is mainly divided into three aspects: activation of immune cells to exert immune regulatory response; participation in inflammatory response-related pathways and regulation of the expression level of inflammatory factors; effect on the metabolic activity of intestinal flora. This study identifies active anti-inflammatory components and an action mechanism of black ginseng showing multi-component, multi-target, and multi-channel characteristics, providing ideas and a basis for a follow-up in-depth study of its specific mechanism.     

EFFECTS OF HELPER PROTEINS ENCODED BY p19 AND orf1-orf2 GENES ON Cyt1Aa PROTEIN EXPRESSION IN ACRYSTALLIFEROUS STRAIN OF BACILLUS THURINGIENSIS

A series of plasmids were constructed to examine the effects of p19 and orf1‐orf2 genes from Bacillus thuringiensis on Cyt1Aa synthesis and inclusion formation. The plasmids expressed the cyt1Aa gene along with either p19 or orf1‐orf2, or each of them coordinatively with p20 in the acrystalliferous strain of B. thuringiensis subsp. israelensis 4Q7. No effect on the expression of Cyt1Aa protein was found when P19 or Orf1‐Orf2 co‐expressed with Cyt1Aa. However, when including p20 gene, the constructs with p19 or orf1‐orf2 gene produced lower yield of Cyt1Aa proteins than without p19 or orf1‐orf2 gene. Electron microscopy observation and bioassay showed that P19 and Orf1‐Orf2 have no influence on the crystal size and toxicity of Cyt1Aa protein. It is presumed that P19 and Orf1‐Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis.     

中药固真方对一些与细胞增殖有关基因表达的影响

 中药固真方对一些与细胞增殖有关基因表达的影响姚明忠,顾文聪,丁卫,韩志芬,杜国光（上海中医药大学生物化学教研室,上海２０００３２）（北京医科大学生物化学与分子生物学系,北京１０００８３）中药固真方（ＶＲＦ）具有补肾益精、延缓衰老的作用［１］．能提高成...     

Insulin-like growth factor I levels decrease in the development of diabetes inMacaca nigra

Members of the monkey speciesMacaca nigra spontaneously develop impairments in insulin secretion and glucose clearance, and eventually become overtly diabetic. Changes in certain metabolic signals such as clearance of glucose and insulin increment secreted in an intravenous glucose tolerance test have allowed the identification of four stages in the progression from non-diabetes to diabetes in monkeys — non-diabetic, hormonally impaired, borderline diabetic, and diabetic. Recently, another metabolic stage, hyperinsulinemic, was also identified in these animals. In recent years, other factors besides those listed above have been implicated to be correlated with the metabolic progression from a nondiabetic to a diabetic state. One of these factors, is insulin like growth factor I (IGF-I). In diabetic humans who are in poor metabolic control, and in rats with streptozotocin induced ketotic diabetes, serum levels of IGF-I are lowered by as much as 40–50% of control non-diabetics. If indeed decreased IGF-I levels are correlated with the onset of diabetes then changes in IGF-I concentrations prior to the clinically diagnosed disease state would be expected. Using serum samples collected from different animals in a colony ofMacaca nigra in a variety of metabolic states, we have found that IGF-I and insulin levels decrease in each defined metabolic state as the animals progress from nondiabetic to diabetic. Since IGF-I and insulin levels decrease in a similar fashion in the progression of this disease then this maybe indicative of the coordinate expression of these two factors.