Genes determining leucine aminopeptidase and mildew resistance from the ornamental apple, ‘White Angel’

Mildew resistance in the ornamental apple White Angel was found to be determined by complementary genes. The gene R _w was found to be necessary for the expression of resistance controlled by the resistance gene Pl _w . The close linkage between the isoenzyme gene, Lap-2, for leucine aminopeptidase and P1 _w was confirmed. The efficiency of Lap-2 as a marker in screening for mildew resistance is limited, as it cannot account for susceptible plants with the r _w r _w P1 _w p1 _w genotype. It has, however, an important role to play in combining resistance genes from different sources. The genotypes of White Angel (R _w r _w , Pl _w pl _w , Lap-2an), Jester (R _w r _w , p1 _w p _w , Lap-2an) Katja (R _w r _w ,p1 _w p1 _w , Lap-2an) and Gloster 69 (r _w r _w , p1 _w p1 _w , Lap-2an) were determined. It also appeared that R _w might influence Lap-2 activity in young seedlings.     

Are isocitrate dehydrogenases and 2-oxoglutarate involved in the regulation of glutamate synthesis?

In plants, nitrogen assimilation into amino acids relies on the availability of the reduced form of nitrogen, ammonium. The glutamine synthetase–glutamate synthase pathway, which requires carbon skeletons in the form of 2-oxoglutarate, achieves this. To date, the exact enzymatic origin of 2-oxoglutarate for plant ammonium assimilation is unknown. Isocitrate dehydrogenases synthesize 2-oxoglutarate. Recent efforts have concentrated on evaluating the involvement of different isocitrate dehydrogenases, distinguished by co-factor specificity and sub-cellular localization. Furthermore, several observations indicate that 2-oxoglutarate is likely to be a metabolic signal that regulates the coordination of carbon:nitrogen metabolism. This is discussed in the context of recent advances in bacterial signalling processes.     

Differences in the Structure of A and B Forms of Human Monoamine Oxidase

Abstract: [³H]Pargyline-labeled polypeptides associated with the A and B types of monoamine oxidase (MAO) activity in human tissues were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). [³H]Pargyline was bound to MAO A in a crude mitochondrial fraction from the placental trophoblast of a male newborn and to MAO B in blood platelets from the umbilical vein of the same newborn. [³H]Pargyline was also bound to MAO A and B in a crude mitochondrial fraction from cultured skin fibroblasts of a male adult and to MAO B in blood platelets from the same individual. Specific labeling of proteins associated with type A or type B activity in fibroblast cells was achieved by preincubation with selective B or A inhibitors, respectively. For all tissues, SDS-PAGE of [³H]pargyline-bound samples revealed a labeled protein band of apparent molecular weight 63,000 for MAO A and 60,000 for MAO B. When SDS-solubilized, [³H]pargyline-labeled MAO A and B proteins from the same male newborn were subjected to limited proteolysis and one-dimensional peptide mapping in SDS gels, different patterns of [³H]pargyline-labeled peptides were obtained. These findings indicate that distinct enzyme molecules are associated with the A and B types of human MAO activity.     

华根霉胞内脂肪酶同功酶酶学性质研究

华根霉(Rhizopus chinensis CCTCCM201021)细胞破碎液经硫酸铵分级盐析、Phenyl-Sepharose FF疏水层析、DEAE-Sepharose FF离子交换层析和Sephadex G100凝胶层析得到两种脂肪酶同功酶:Lip1和Lip2。SDS-PAGE显示其亚基分子量分别为59.2kD和39.4kD。Lip1和Lip2的最适反应pH和最适反应温度相近,分别为8.0、8.5和40℃、35℃。但底物专一性差异明显:Lip1对pNP脂肪酸酯的长链脂肪酸有较高的专一性,Lip2对pNP脂肪酸酯的短链脂肪酸专一性较好;Lip1对三油酸甘油酯表现1,3-位置特异性,而Lip2没有位置选择性。1mmol/L的Ca2 、Mg2 对Lip1、Lip2有较好的激活作用;SDS强烈抑制酶活力。Lip1、Lip2在环己烷、正己烷、正庚烷和异辛烷(30%V/V)中稳定性良好。     

中国内蒙古鄂伦春、鄂温克、达斡尔族人五种酶型和二种血清型遗传多样性分析

应用G6PD ACP ADA AK1和GC-Tf同步电泳的方法及GPT凝胶电泳的方法,分别对内蒙古境内鄂温克、鄂伦春、达斡尔族人476份血痕红细胞酶型:GPT、6-PGD、ACP、ADA、AK1和血清型GC、Tf的遗传多样性进行检测。根据所测表型频率分布、计算出基因频率分布,识别能力和累积识别能力,就其多态性特征及其在法医学鉴定中的应用价值进行了分析讨论。同国内外不同资料进行了比较研究,阐明了三群体上述酶型和血清型遗传多样性分布的规律和特点。从血型遗传学角度探讨了鄂伦春、鄂温克、达斡尔族间的族源、血缘关系。被调查人群中未发现各酶型和血清型的变异型。     

Determination of lactate dehydrogenase isoenzymes in single lymphocytes from normal and leukemia cell lines

This work demonstrates that our previously developed technique for single-erythrocyte analysis by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) can be applied to study individual lymphocytes, with some modification in the cell lysing procedure. A tesla coil was shown to be capable of lysing the lymphocyte cells inside the capillary. The electromagnetic field induced by the tesla coil was believed to be responsible for breaking the cell membrane. The lactate dehydrogenase (LDH) isoenzyme activities and the relative ratios between different LDH isoenzymes were measured for normal lymphocytes as well as B-type and T-type acute lymphoblastic leukemia cells. Both the LDH activity and the isoenzyme ratios show large variations among individual cells. The former is expected due to variations in cell size. The latter implies that single-cell measurements are less useful than the average values over a cell population as markers for leukemia.     

NAD-dependent aromatic alcohol dehydrogenase in wheats (Triticum L.) and goatgrasses (Aegilops L.): evolutionary genetics

Summary Evolutionary electrophoretic variation of a NAD-specific aromatic alcohol dehydrogenase, AADH-E, in wheat and goatgrass species is described and discussed in comparison with a NAD-specific alcohol dehydrogenase (ADH-A) and a NADP-dependent AADH-B studied previously. Cultivated tetraploid emmer wheats (T. turgidum s. l.) and hexaploid bread wheats (T. aestivum s. l.) are all fixed for a heterozygous triplet, E^0.58/E^0.64. The slowest isoenzyme, E^0.58, is controlled by a homoeoallelic gene on the chromosome arm 6AL of T. aestivum cv. Chinese Spring and is inherent in all diploid wheats, T. monococcum s. Str., T. boeoticum s. l. and T. urartu. The fastest isoenzyme, E^0.64, is presumably controlled by the B- and D-genome homoeoalleles of the bread wheat and is the commonest alloenzyme of diploid goat-grasses, including Ae. speltaides and Ae. tauschii. The tetraploid T. timopheevii s. str. has a particular heterozygous triplet E^0.56/E^0.71, whereas the hexaploid T. zhukovskyi exhibited polymorphism with electromorphs characteristic of T. timopheevii and T. monococcum. Wild tetraploid wheats, T. dicoccoides and T. araraticum, showed partially homologous intraspecific variation of AADH-E with heterozygous triplets E^0.58/E^0.64 (the commonest), E^0.58/E^0.71, E^0.45/E^0.58, E^0.48/E^0.58 and E^0.56/E^0.58 recorded. Polyploid goatgrasses of the D-genome group, excepting Ae. cylindrica, are fixed for the common triplet E^0.58/E^0.64. Ae. cylindrica and polyploid goatgrasses of the C^u-genome group, excepting Ae. kotschyi, are homozygous for E^0.64. Ae. kotschyi is exceptional, showing fixed heterozygosity for both AADH-E and ADH-A with unique triplets E^0.56/E^0.64 and A^0.49/A^0.56.     

Trypanosoma brucei: The peptidases of bloodstream trypanosomes

Peptidases (EC.3.4.11 and EC.3.4.13.9) from bloodstream Trypanosoma brucei were examined by starch gel electrophoresis and substrate specificities and relative activities of six peptidases (S,B,E,A,F,D,) determined. The substrate specificities corresponded closely to those of the peptidases of human blood cells and tissues although human peptidase C appeared not to have a T. brucei equivalent.     

Genetic variability in wild cherry populations in France. Effects of colonizing processes

 Isoenzymes were used to evaluate gene diversity and genetic differentiation among six populations of wild cherry (Prunus avium L.) in France. We contrast the genetic characteristics of a population resulting from a recent colonization with those of a much older population of the same species. No significant genetic structure was observed among populations; in this respect wild cherry does not differ from other forest trees. No founder effects could be detected in the newly colonized population. To explain the results, we discuss classic explanations for the lack of genetic differentiation among populations, including balancing selection and neutral drift/migration. In order to account for the absence of founder effects, we propose a hypothesis based on the life cycle of forest trees, namely that the length of the juvenile phase reduces the impact of small numbers of initial founders. Received : 26 November 1996 / Accepted : 20 December 1996