Activation of fatty acids by non-glyoxysomal peroxisomes

Ethylene treatment (approx. 20 l ·1^-1 in air for 2 d) of tobacco (Nicotiana tabacum L. cv. Havana 425) plants markedly increases the endo--1,3-glucanase (EC 3.2.1.39) content of leaves. The antigenic form of the enzyme induced is the same one whose production is blocked by treating cultured cells with combinations of auxin (1.1 · 10^-5 M -naphthaleneacetic acid) and cytokinin (1.4 · 10^-6 M kinetin). Evidence is presented that cultured tobacco cells require ethylene for -1,3-glucanase accumulation: i) ethylene treatment increased the accumulation of \-1,3-glucanase in callus tissues >10 d after subculturing and in cell-suspension cultures; ii) callus tissues can produce ethylene; iii) conditions known to inhibit ethylene production (1 mM CoCl₂; 33° C treatment) or ethylene action (approx. 1.6 mmol · 1^-1 norbornadiene in air) inhibited -1,3-glucanase accumulation by callus tissues treated for 4 d following subculturing; and, these inhibitory effects were prevented by exogenous ethylene. Combinations of auxin and cytokinin blocked ethylene-induced accumulation of -1,3-glucanase by cell-suspension cultures. The results favor a model in which ethylene induces results favor a model in which ethylene induces 1,3-glucanase accumulation, and auxin and cytokinin inhibit this induction process.Abbreviations NAA -naphthaleneacetic acid - NDE norbornadiene     

Auxin-stimulated ethylene production in fern gametophytes and sporophytes

The auxins indole-3-acetic acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) stimulated ethylene production from gametophytes of the fern Pteridium aquilinum (L.) Kuhn. var. latiusculum (Desv) underw. ex Heller and sporophytes of the ferns Matteuccia struthiopteris (L.)Todaro and Polystichum munitum (Kaulf.) Presl. Treatment with Co²⁺ or l -α -(2-aminoethoxyvinyl)-glycine (AVG) eleminated or significantly reduced the stimulatory effects of IAA. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) resulted in significantly greater rates of ethylene production from all tissues tested. Based on their response to auxin, ACC, AVG and Co²⁺, the ethylene biosynthetic pathway in these three lower vascular plants appears similar to that existing in angiosperms.     

Characterization ofR. fredii QB1130, a strain effective on commercial soybean cultivars

Summary Two rhizobial strains (QB1130 and C3A) from northeast China were identified asRhizobium fredii on the basis of growth rate, media acidification and growth on a wide range of carbon substrates. The strains were shown to be distinct from USDA 191 on the basis of plasmid number and size. Bothnif and commonnod genes were located on the 295 kb plasmid of strains QB1130 and USDA 191, while onlynif genes were identified on this plasmid in C3A. When used to inoculate four commercial soybean (Glycine max) cultivars, one of the strains (C3A) was found to be ineffective, while the other (QB1130) was at least as effective as USDA 191, a strain ofR. fredii reported to be widely effective on North American cultivars of soybean. Further, QB1130 was capable of more effective nodulation of cowpea or the uncultivated soybean line, Peking, than either USDA 191 or the slow-growingBradyrhizobium japonicum USDA 16. Strain QB1130 should be useful for studies directed at improving symbiotic performance in soybean, or for studies of the comparative physiology and genetics of FG and SG strains on a single host.     

C-banding polymorphism and the analysis of nucleolar activity in Dasypyrum villosum (L.) Candargy,its added chromosomes to hexaploid wheat and the amphiploid Triticum dicoccum — D. villosum

Summary C-banding patterns and nucleolar activity were analyzed in Dasypyrum villosum, its added chromosomes to hexaploid wheat and the hexaploid amphiploid Triticum dicoccum-D. villosum. Two different populations of the allogamous species D. villosum (2n= 14, VV) from Greece and Italy were analyzed showing a similar polymorphism for C-banding pattern. Six of the seven addition lines were identified by their characteristic C-banding pattern. No polymorphism between both members of each added alien chromosome was found. Furthermore, nucleolar activity and competition were studied by using silver staining procedure. In D. villosum only one chromosome pair, A, was found to be responsible for organizing nucleoli. The results obtained in the amphiploid and in the addition lines demonstrate that nucleolar activity is restricted to SAT-chromosomes 1B and 6B of wheat, while those of D. villosum remain inactive.     

秦岭产珠子参叶的达玛烷型皂甙研究(1)

从陕西省秦岭产珠子参(Panax japonicus C.A.Meyer var.major(Burk.)Wu etFeng)的叶中分离到十个新的达玛烷型四环三萜皂甙,经光谱测定和化学降解,其中四个的化学结构分别为珠子参甙(majoroside)F_1(1)、F_2(2)、F_3(3)和F_4(4)。同时,还分离到已知的人参甙(ginsenoside)Rd(5)、Re(6)、Rg_1(7)、Rg_2(8)和F_2(9)。     

盾叶薯蓣地上部分的三个新甾体皂甙

从盾叶薯蓣Dioscorea zingiberensis Wright地上部分分离鉴定了四个甾体皂甙,经鉴定甙A为约莫皂甙元-3-O-[α-L-鼠李吡喃糖基(1→2)]-β-D-葡萄吡喃糖甙;甙B为24α-羟基约莫皂甙元-3-O-[α-L-鼠李吡喃糖基(1→2)]β-D-葡萄吡喃糖甙;甙C为约莫皂甙元-3-O-[α-L-鼠李吡喃糖基(1→2)][β-D-葡萄吡喃糖基(1→4)]-β-D-葡萄吡喃糖基;甙D为约莫皂甙元-3-O-[α-L-鼠李吡喃糖基(1→2)][β-D-葡萄吡喃糖基(1→3)]-β-D-葡萄吡喃糖甙。前三者为新化合物,分别命名为盾叶皂甙A_1、A_2、A_3(zingiberoside A_1、A_2、A_3),其中盾叶皂甙A_2的甙元为一新甾体皂甙元,命名为盾叶皂甙元(zingiberogenin)。     

Site-directed mutagenesis to determine essential residues of ribulose-bisphosphate carboxylase ofRhodospirillum rubrum

Both Lys-166 and His-291 of ribulosebisphosphate carboxylase/oxygenase fromRhodospirillum rubrum have been implicated as the active-site residue that initiates catalysis. To decide between these two candidates, we resorted to site-directed mutagenesis to replace Lys-166 and His-291 with several amino acids. All 7 of the position-166 mutants tested are severely deficient in carboxylase activity, whereas the alanine and serine mutants at position 291 are ∼40% and ∼18% as active as the native carboxylase, essentially ruling out His-291 in theRhodospirillum rubrum carboxylase (and by inference His-298 in the spinach enzyme) as a catalytically essential residue. The ability of some of the mutant proteins to undergo carbamate formation or to bind either ribulosebisphosphate or a transition-state analogue remains largely unimpaired. This implies that Lys-166 is not required for substrate binding; rather, the results corroborate the earlier postulate that Lys-166 functions as an acid-base group in catalysis or in stabilizing a transition state in the reaction pathway.     

Interaction of Cibacron Blue F3G-A and Procion Red HE-3B with sheep liver 5,10-methylenetetrahydrofolate reductase

Cibacron Blue F3G-A, a probe used to monitor nucleotide binding domains in enzymes, inhibited sheep liver 5,10-methylenetetrahydrofolate reductase competitively with respect to 5-methyltetrahydrofolate and NADPH. TheK _i values obtained by kinetic methods and theK _d value for the binding of the dye to the enzyme estimated by protein fluorescence quenching were in the range 0.9–1.2 μM. Another triazine dye, Procion Red HE-3B interacted with the enzyme in an essentially similar manner to that observed with Cibacron Blue F3G-A. These results as well as the interaction of the dye with the enzyme monitored by difference spectroscopy and intrinsic protein fluorescence quenching methods indicated that the dye was probably interacting at the active site of the enzyme by binding at a hydrophobic region.     

五种雀形目鸟类核型的比较研究

染色体核型的比较研究,对于了解物种的特性,探索物种的遗传、进化、系统发育及分类地位都有一定的意义。有关鸟类的核型研究,国外已有不少报道(Castrovicja,1969; Hammar,1966,1975; Ray-Chaudhuri et al.,1969;Shidds,1982;Ta—kagi,1972等)国内在这方面的工作开展较迟,已作过核型分析的鸟类为数不多,仅见王应祥等(1982)的报道。迄今,作过核型研究的鸟类已达500多种,其中雀形目有200种。本文比较分析了五种野生雀形目鸟类的核型,它们是黑头蜡嘴雀,斑鸫,黄腹山雀,红尾伯劳和灰背椋鸟。