Alcohol dehydrogenase isozymes in the mouse: Genetic regulation, allelic variation among inbred strains and sex differences of liver and kidney A2 isozyme activity

Genetic analysis of a proposed cis-acting temporal locus ( Adh-3t ), which regulates alcohol dehydrogenase C₂ (ADH-C₂) acitivity in mouse epididymis extracts, among F₁ (ddN × BALB/c) × ddN male backcross progeny provided evidence for genetic distinctness between the structural ( Adh-3 ) and temporal ( Adh-3t ) loci on chromosome 3. Genetic analysis also confirmed the close, linkage of Adh-1 (encoding liver and kidney ADH-A₂) and Adh-3 (encoding stomach ADH-C₂) to within 0.3 centimorgans on the mouse genome. Evidence is presented for a proposed closely linked cis-acting temporal locus (designated Adh-1t ) for the A₂ isozyme (encoded by Adh-1 ) controlling the activity of this enzyme in mouse kidney extracts, but having no apparent affect on liver and intestine ADH-A₂ activities. An extensive survey of the distribution of Adh-1, Adh-3 and Adh-3t alleles among 65 strains of mice is reported — with the exception of two Japanese strains (ddN and KF), linkage disequilibrium between Adh-3 and Adh-3t was observed. Sex differences in mouse liver and kidney ADH-A₂ activities were observed, with male/female ratios of approximately 0.6 and 3 respectively for these tissue extracts.     

N-Linked Oligosaccharides of Aspergillus awamori Feruloyl Esterase Are Important for Thermostability and Catalysis

A unique N-linked glycosylation motif (Asn⁷⁹-Tyr-Thr) was found in the sequence of type-A feruloyl esterases from Aspergillus spp. To clarify the function of the flap, the role of N-linked oligosaccharides located in the flap region on the biochemical properties of feruloyl esterase (AwFAEA) from Aspergillus awamori expressed in Pichia pastoris was analyzed by removing the N-linked glycosylation recognition site by site-directed mutagenesis. N79 was replaced with A or Q. N-glycosylation-free N79A and N79Q mutant enzymes had lower activity than that of the glycosylated recombinant AwFAEA wild-type enzyme toward α-naphthylbutyrate (C4), α-naphthylcaprylate (C8), and phenolic acid methyl esters. Kinetic analysis of the mutant enzymes indicated that the lower catalytic efficiency was due to a combination of increased K _m and decreased k _cat for N79A, and to a considerably decreased k _cat for N79Q. N79A and N79Q mutant enzymes also exhibited considerably reduced thermostability relative to the wild-type.     

Genetic characterisation of a further homoeoallelic series of grain esterase loci,Est-6, in wheat

Summary Isoelectric focussing in alkaline pH gels has permitted the identification of a new homoeoallelic series of genes,Est-6, encoding grain esterases in bread wheat,Triticum aestivum. Nullisomic analysis located these genes to the short arms of the homoeologous group 2 chromosomes. A search for polymorphism withinEst-6 revealed null alleles at each ofEst-A6,Est-B6 andEst-D6. A further homoeolocus,Est-M6, is present on chromosome arm2MS ofAegilops comosa.     

Enantioselective hydrolysis of esters of secondary alcohols using lyophilized Bakers'' yeast

A number of acetoxycarboxylic acid esters were hydrolysed enantioselectively by Saccharomyces cerevisiae Hansen leading to chiral hydroxycarboxylic acid esters of high optical purity. The scope and limitations of this method with respect to the substitutional pattern of substrates were investigated. Subcellular localization of the hydrolytic activity on the plasma membrane led to the assumption that unspecific carboxyl esterases are responsible for hydrolysis of this type of substrate. Comparative experiments using viable cells and lyophilized cells as source of enzyme revealed the latter to be superior with respect to enantioselection and ease of handling.     

Plant regeneration from cultured immature embryos of Sorghum bicolor (L.) Moench

Summary Immature embryos of 20 sorghum genotypes were cultured on MS 5 medium containing MS mineral salts supplemented with 2,4-D, zeatin, glycine, niacinamide, Ca-pantothenate, L-asparagine, and vitamins. For regeneration, calli were transferred onto the same medium with the exception that IAA was substituted for 2,4-D. In general, immature embryos obtained 9–12 days after pollination resulted in the best redifferentiation. Ability of calli to regenerate varied among genotypes; cultivars C401-1 and C625 had the highest redifferentiation frequencies. Ability to redifferentiate was heritable and acted as a dominant trait. At least two gene pairs were involved. Regenerated R₀ plants were planted in a greenhouse and their selfed (R₁ and R₂) progenies were planted in the field and examined for morphological and cytological variations. The majority of the phenotypic variations noted in R₀ were not transmitted to later generations. However, variants for plant height, degree of fertility, and midrib color persisted in R₁ and R₂ generations. A variation in tallness was attributable to one dominant mutant gene. Short stature and male sterility variants appeared to be consequences of recessive mutant genes controlling those traits. Minor variations in peroxidase banding patterns were found among R₀ plants.This study was supported by a research grant from Kansas Sorghum Commission and by a Research Fellowship to the senior author from the Ministry of Agriculture, Animal Husbandry, and Fisheries, China. Contribution 86-456-J from the Kansas Agricultural Experiment Station     

矮生型苹果苗的预选标志

用淀粉凝胶电泳,分析苹果实生苗新梢皮层的过氧化物酶同工酶,其酶9带(A_9)与苹果的矮生习性相关,且不受树龄、苹果类型以及栽培条件等影响。在矮生型苹果育种中,A_9可以作为预选标志,其准确率为86.14%。     

意蜂和中蜂四种同工酶的研究

用聚丙烯酰胺凝胶等电聚焦电泳分析了意蜂和中蜂的酯酶(Est)、异柠檬酸脱氢酶(Idh)、苹果酸酶(Me)和苹果酸脱氢酶(Mdh)同工酶.两个蜂种的四种同工酶谱有不同程度的差别、意蜂酯酶Ⅳ和苹果酸脱氢酶Ⅲ是多态性的;中蜂的四种同工酶没有多态现象.     

Neuropathy Target Esterase: Rates of Turnover In Vivo Following Covalent Inhibition with Phenyl Di-n-Pentylphosphinate

Phenyl di-n-pentylphosphinate is a reasonably stable easily synthesized inhibitor of neuropathy target esterase (NTE) with low anticholinesterase activity. Like phenylmethylsulphonyl fluoride it protects hens against neuropathic effects of compounds such as diisopropylphosphorofluoridate. At intervals up to 15 days after dosing hens (10 mg/kg s.c. to inhibit 90% NTE) assays were made of catalytically active and of phosphinylated NTE in autopsy tissue. The sum of these components was always within the range of catalytic activity in undosed controls. However, the half-life of reappearance of active NTE was 2.07 days +/- 0.13 (SD, n = 6) for brain and 3.62 days +/- 0.23 (SD, n = 6) for spinal cord--shorter than after dosing with phenylmethylsulphonyl fluoride. It is proposed that: (1) The physiological turnover mechanism cannot distinguish between catalytically active and di-n-pentylphosphinylated NTE although initiation of organophosphate-induced delayed polyneuropathy might involve recognition of aged di-alkyl-phosphorylated NTE as "foreign". (2) The short half-lives indicate a slow spontaneous dephosphinylation of inhibited NTE occurs in vivo as well as de novo synthesis. The difference in half-lives for brain and spinal cord NTE may be due to different rates of synthesis de novo or (more likely) to different rates of spontaneous reactivation of the inhibited NTE in the two tissues.     

蛋白和酯酶电泳在根霉鉴定上的应用

对根霉(Rhizopus)属的十个种或变种共二十四株菌的菌体可溶性蛋白和酯酶同工酶进行了电泳的研究得到对这个属分类上更多的依据.在严格控制培养,提取和电泳条件的情况下,同一株菌不同批次所得菌体蛋白电泳图谱有较好的重复性.在相同的条件下,每个种的根霉有各自特征性蛋白图谱,种内不同菌株的蛋白图谱和酯酶酶谱基本相同.特别是形态特征明显、分类地位明确的种,种内各株的图谱也较一致,如R. stolonifer;与R.circinans.在确定新变种R. delemar var. latoapicalis时,电泳图谱与R.delemar var.delema:有明显不同,起到了佐证作用.因此认为,蛋白图谱与酯酶酶谱相辅相成,在根霉种的分类中是一有效的辅助手段.