Genetic Regulation of Development in Sorghum bicolor (VIII. Shoot Growth,Tillering, Flowering,Gibberellin Biosynthesis,and Phytochrome Levels Are Differentially Affected by Dosage of the ma3R Allele

Sorghum [Sorghum bicolor (L.) Moench] homozygous for ma3R lacks a type II, light-stable phytochrome of 123 kD and has a number of phenotypic characteristics consistent with the absence of functional phytochrome B. We have used plants heterozygous at Ma3 (Ma3/ma3R and ma3/ma3R) to determine the effect of dosage of ma3R on plant growth, flowering, gibberellin (GA) levels, and content of the 123-kD phytochrome. Both Ma3/ma3R and ma3/ma3R produced the same number of tillers per plant as their respective homozygous non-ma3R parents. Height of the heterozygotes was intermediate between the homozygous parents, although it was more similar to the non-ma3R genotypes. In both field and growth-chamber environments, the timing of floral initiation and anthesis in the heterozygotes also was intermediate, again more similar to non-ma3R plants. In Ma3/ma3R, levels of GA53, GA19, GA20, and GA1 were almost exactly intermediate between levels detected in Ma3/Ma3 and ma3R/ma3R plants. Immunoblot analysis indicated that there was less of the 123-kD phytochrome in Ma3/ma3R than in homozygous Ma3, whereas none was detected in ma3R/ma3R. The degree of dominance of Ma3 and ma3 over ma3R varies with phenotypic trait, indicating that mechanisms of activity of the 123-kD phytochrome vary among the biochemical processes involved in each phenotypic character. Although the heterozygotes were similar to homozygous Ma3 and ma3 plants in growth and flowering behavior, Ma3/ma3R contained 50% less of the bioactive GA (GA1) than non-ma3R genotypes. Thus, sensitivity to endogenous GAs also may be regulated by the 123-kD phytochrome. To fully regulate plant growth and development, two copies of Ma3 or ma3 are required to produce sufficient quantities of the light-stable, 123-kD phytochrome.     

Mitochondria. II. The nuclear-mitochondrial relationship in Pelomyxa carolinensis Wilson (Chaos chaos L.)

This study has demonstrated that in the ameba, Pelomyxa carolinensis Wilson (Chaos chaos L.) the limiting membranes of mitochondria and postdivision nuclei are often continuous. The morphological relationship may be functional in that it permits an exchange of material resulting directly or indirectly in an increased enzyme content of the mitochondria. It is suggested that through a series of progressive foldings of its envelope, the nucleus may be a site of formation of mitochondria.     

复制型HBV转基因小鼠的遗传与繁育研究

本文采用类似系祖建系的方法,对复制型ＨＢＶ转基因小鼠模型的１７、２１、２５三个系列进行了繁育,通过ＰＣＲ和Ｓｏｕｔｈｅｒｎ分子杂交的方法,检测三个系列小鼠尾组织和血清的ＤＮＡ样品,以确定ＨＢＶ基因的整合和复制情况。结果表明,ＨＢＶ基因已稳定地遗传至第五代（Ｆ５）,且各世代小鼠血清中都存在ＨＢＶＤＮＡ,此外,整合阳性小鼠的血清中能测出ＨＢＶＤＮＡ的比率很高,Ｆ１代为９４．４４％（１０２／１０８）,Ｆ２、Ｆ３代为９５．３１％（６１／６４）,故在繁育中可以通过测血清中的ＨＢＶＤＮＡ来确定小鼠是否整合。