Inheritance of Variegation

Ohne Zusammenfassung     

中国秋海棠属植物叶片斑纹多样性研究

通过对野生和引种栽培植物的观察,结合文献和标本的查阅,对中国秋海棠属植物斑叶类资源及叶斑多样性进行了研究.发现中国分布的203种(含变种和亚种)秋海棠属植物中有斑纹的种类达84种,叶斑色彩多表现为淡绿色、银绿色、银白色、白色.从园艺学角度出发,根据中国秋海棠属植物斑纹在叶片的分布位置,首次提出了中国秋海棠属植物叶斑分类标准,并对观察到的斑叶类秋海棠进行了分类,方便人们选择利用.根据斑纹与叶脉的关系分为叶脉相关类型(Ⅰ)和非叶脉相关类型(Ⅱ),前者细分为脉间斑纹类(Ⅰ A)、沿脉斑纹类(Ⅰ B)、中脉及脉间斑纹类(ⅠC)3种,后者细分为环状面斑类(ⅡA)、掌状面斑类(ⅡB)、近完全面斑类(ⅡC)、完全面斑类(ⅡD)、混合面斑类(ⅡE)和不规则面斑类(ⅡF)6种.中国产野生秋海棠属植物中较常见的叶斑类型为Ⅰ A1、ⅠA2、Ⅰ B1、Ⅰ B2和ⅡA.同时对叶斑的产生机理和遗传特性进行了讨论和展望.中国斑叶类秋海棠属植物种质资源及其叶斑类型的多样性极其丰富,有望通过研究摸清其遗传特性,实现特定观赏性状新品种的定向选育.     

The Effect of Modifiers of Position-Effect Variegation on the Variegation of Heterochromatic Genes of Drosophila Melanogaster

Dominant modifiers of position-effect variegation of Drosophila melanogaster were tested for their effects on the variegation of genes normally located in heterochromatin. These modifiers were previously isolated as strong suppressors of the variegation of euchromatic genes and have been postulated to encode structural components of heterochromatin or other products that influence chromosome condensation. While eight of the modifiers had weak or no detectable effects, six acted as enhancers of light (lt) variegation. The two modifiers with the strongest effects on lt were shown to also enhance the variegation of neighboring heterochromatic genes. These results suggest that the wild-type gene products of some modifiers of position-effect variegation are required for proper expression of genes normally located within or near the heterochromatin of chromosome 2. We conclude that these heterochromatic genes have fundamentally different regulatory requirements compared to those typical of euchromatic genes.     

beta-Galactosidases in Ripening Tomatoes

Tomatoes (Lycopersicon esculentum L.) contained a high level of β-galactosidase activity which was due to three forms of the enzyme. During tomato ripening, the sum of their activities remained relatively constant, but the levels of the individual forms of β-galactosidase changed markedly. The three enzymes were separated by a combination of chromatography of DEAE-Sephadex A-50 and Sephadex G-100. During ripening of tomatoes, β-galactosidases I and III levels decreased but the β-galactosidase II level increased more than 3-fold. The three enzymes were optimally active near pH 4, and all were inhibited by galactose and galactonolactone. However, the enzymes differed in molecular weight, K_m value with p-nitrophenyl-β-galactoside, and stability with respect to pH and temperature. β-Galactosidase II was the only enzyme capable of hydrolyzing a polysaccharide that was isolated from tomatoes and that consisted primarily of β-1, 4-linked galactose. The ability of β-galactosidase II to degrade the galactan and the increase in its activity during tomato ripening suggest a possible role for this enzyme in tomato softening.     

一种非基因效应的遗传机制

一种非基因效应的遗传机制祝其昌（江苏省农业科学院经济作物研究所,南京２１００１４）ＡＮｏｎｇｅｎｉｃＨｅｒｅｄｉｔａｒｙＭｅｃｈａｎｉｓｍＺｈｕＱｉｃｈａｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＥｃｏｎｏｍｉｃＣｒｏｐｓ,ＪｉａｎｇｓｕＡｃａｄｅｍｙｏｆＡｇｒｉ...     

番茄的耐盐性与耐盐转基因番茄

由于土壤盐渍化的日益加剧导致作物大量减产,通过基因工程的方法将耐盐基因转入作物,培育耐盐作物新品种是开发利用盐碱地的一种经济、有效的手段.番茄是一种栽培广泛,具有重要经济价值的蔬菜,又是基因工程的模式生物之一,开展番茄耐盐性研究具有重要意义.分析了番茄的耐盐性和转耐盐基因番茄的研究现状.     

A Hereditary Skin Defect in Sheep

Some years ago a lamb with abnormal skin was received at the State veterinary research station for small ruminants (SVRS), Stavanger, from a farm in Ryfylke. The lamb had apparently been normal at birth, but by normal activity and contact with its mother, extensive wounds developed, with large, loose skin areas. The lamb’s condition had deteriorated so much that it was killed when it was two days old. Two ewes sired by the same ram had given birth to similar lambs the same year, while some years earlier, lambs with the same defect had been born by other ewes in the flock.