河西走廊不同生态型芦苇核酸代谢季节动态研究

分布在甘肃河西走廊的４ 种生态型芦苇（Ｐｈｒａｇｍ ｉｔｅｓｃｏｍ ｍ ｕｎｉｓＴｒｉｎ．）的核酸代谢季节变化有差异。盐化草甸芦苇ＲＮＡ 含量持续增加,ＤＮＡ 含量相对稳定,其它３ 种生态型芦苇的ＲＮＡ 和ＤＮＡ 含量以５月份为最高。过渡带芦苇的ＲＮＡ 含量、沼泽芦苇及沙丘芦苇的ＤＮＡ含量９ 月份略有增高。盐化草甸芦苇与过渡带芦苇的ＤＮａｓｅ和ＲＮａｓｅ的活性７ 月份最高,沼泽芦苇与沙丘芦苇的ＤＮａｓｅ和ＲＮａｓｅ活性５—９ 月份呈增高趋势。盐化草甸芦苇的ＤＮＡ 和ＲＮＡ 合成活性不断升高,过渡带芦苇和沼泽芦苇的ＤＮＡ 和ＲＮＡ 合成活性及沙丘芦苇的ＲＮＡ 合成活性５—９月份均降低,仅沙丘芦苇的ＤＮＡ合成活性增强。ＲＮＡ 聚丙烯酰胺梯度凝胶电泳分析结果表明,４ 种生态型芦苇均含有２５Ｓ、２３Ｓ、１８Ｓ、１６Ｓ大分子量ｒＲＮＡ 和小分子量５．８Ｓ、５Ｓ、４．５ＳｒＲＮＡ 及４ＳｔＲＮＡ。大分子量ＲＮＡ 的含量高于小分子量ＲＮＡ 含量。不同生态型及同一生态型芦苇的不同发育时期,相同的ＲＮＡ 组分含量各不相同。且发育过程中２３Ｓ、１８Ｓ、１６ＳｒＲＮＡ 在不同月份发生不同程度的降解。由此,我们认为,核酸代谢的差异性是４ 种生态型由生长转入衰     

芦苇耐盐变异植株及其细胞学鉴定

用甲基磺酸乙酯（ＥＭＳ）处理芦苇（Ｐｈｒａｇｍ ｉｔｅｓｃｏｍ ｍ ｕｎｉｓ Ｔｒｉｎ．）胚性愈伤组织。从处理后的愈伤组织诱导获得芦苇耐盐变异植株Ｒ５００２－１２。变异植株能在含有１％ ＮａＣｌ的ＭＳ培养基上生长。细胞学检查变异植株是混倍体,染色体数目变异范围在１００至３３ 之间。分蘖植株具有相似的形态学及染色体变异特性     

Oviposition preference of Anthocoris nemorum and A. nemoralis for apple and pear

Anthocoris nemorum L. and Anthocoris nemoralis Fabricius (Heteroptera: Anthocoridae) are important predators of insect pests in pome fruit. Females insert their eggs in leaf tissue. The females’ choice of oviposition site is important for the subsequent distribution of nymphs on host plants. Oviposition preference for apple and pear leaves was tested in the laboratory in four experiments (experiments 1–4). In three experiments it was tested whether simulated insect damage to leaves (experiments 5 and 6) or the presence of prey (experiment 7) influenced oviposition preference. The effect of the presence of prey was only tested for A. nemorum on apple leaves. There was a highly significant anthocorid species × plant interaction for the number of eggs laid on apple and pear leaves. Anthocoris nemorum laid more eggs on apple than on pear leaves, while A. nemoralis preferred pear. Anthocoris nemorum's preference for apple increased over the 6‐week period in which experiments 1–4 were performed, from 66% to 91% eggs laid on apple leaves. No change over time in preference was found for A. nemoralis. Across experiments 1–4, the majority of A. nemorum eggs were laid near leaf margins, whereas eggs of A. nemoralis were more commonly found in the leaf centre, 5 mm or more from the margin, with a highly significant leaf region × species interaction. There was no significant difference in preference for leaf side between A. nemorum and A. nemoralis, but there was a highly significant plant × leaf side × experiment interaction. Thus, more eggs were laid on the ventral than on the dorsal side of pear leaves in experiment 4, while significantly more eggs were laid on the dorsal side of apple leaves in experiments 3 and 4. Choice tests between damaged and healthy leaves showed that A. nemorum laid significantly more eggs on the damaged leaves, while A. nemoralis preferred healthy leaves. Anthocoris nemorum showed a near‐significant preference for ovipositing on leaves with eggs of Operophtera brumata (Lepidoptera: Geometridae). The oviposition preferences found correspond to the natural distribution of these predators in apple and pear orchards. The preference of A. nemorum for leaf margins, and of A. nemoralis for the leaf centre as an oviposition site, supports earlier observations. A preference for leaf side for oviposition site has not been reported earlier. Preference for damaged leaves could help A. nemorum to locate prey in a field situation.     

The mycorrhizal status of the woody Mediterranean shrub Myrtus communis L.

  Myrtus communis L. (myrtle), a typical Mediterranean plant species belonging to the family Myrtaceae, was shown to form arbuscular mycorrhizal symbioses in nature. Many different spore types were isolated from its rhizosphere and grown in pot cultures; six of them were identified as Glomus species. In the laboratory, the myrtle root system was colonized by indigenous endophytes as well as by an Italian isolate of Glomus intraradices. In greenhouse experiments, mycorrhizal inoculation reduced transplant stress in 60-day-old myrtle seedlings; their growth was renewed immediately after transplanting, whereas non-mycorrhizal plants stopped development. Significantly larger growth responses were obtained using indigenous fungi than the Italian isolate of Glomus intraradices. Accepted: 16 January 1997     

The validity of the lead precipitation technique for the localization of ATPase activity in plant cells

Summary The claim that osmium-containing deposits which lack lead are frequently and incorrectly interpreted as enzymatic reaction products in lead precipitation techniques for ATPase localization in plants is without foundation. Proper controls clearly demonstrate the enzymatic origin of membrane-located deposits and the presence of lead is confirmed by analytical electron microscopy.     

Characterization of solute/proton cotransport in plasma membrane vesicles from Ricinus cotyledons,and a comparison with other tissues

Plasma membrane vesicles, purified by aqueous two-phase partitioning, were used to investigate the presence of sugar and amino acid carriers in cotyledons and roots of Ricinus communis L. and in roots of red beet (Beta vulgaris L.). Artificial pH and electrical gradients were generated across the plasma membrane, and [¹⁴C]acetate and [¹⁴C]tetraphenylphosphonium were used to demonstrate the presence of an internal alkaline pH gradient and an internal negative membrane potential, respectively. In Ricinus cotyledons, uptake of sucrose was more strongly inhibited than that of glutamine by p-chloromercuribenzenesulphonic acid, phlorizin and phenylglyoxal. The sucrose transport system showed a high degree of substrate specificity with only the presence of maltose and phenyl--glucoside significantly affecting sucrose uptake; in contrast, the glutamine transport system was inhibited by a number of other amino acids. pH+gD-driven glutamine uptake showed saturation kinetics with a K _m of 0.35 mol · m^–3. Sucrose and glutamine -driven uptake was pH dependent with an optimum in the acidic range (pH 6.25) and a decrease at higher pH values. Vesicles obtained from cotyledons and roots of Ricinus showed different transport properties. In the cotyledons, gDH+gD-driven transport for both sucrose and glutamine were observed at similar levels; however, in the root tissue, pH--driven glutamine transport was the dominant uptake process. Uptake rates for glucose and fructose were low in the cotyledons whereas, in the roots, glucose and sucrose transport were slightly higher than that of fructose. In vesicles from red beet tissue there was a different uptake profile, with evidence of proton-coupled cotransport systems for sucrose and glucose, but lower uptake of glutamine and fructose. The results are discussed in relation to the reported different pathways for loading and unloading of solutes in these tissues.Abbreviations CCCP carbonyl cyanide-m-chlorophyenyl hydrazone - DEPC diethyl pyrocarbonate - NEM N-ethylmaleimide - PCMBS p-chloromercuribenzenesulfonic acid - TPP tetraphenylphosphonium ion - gDH⁺ proton electrochemical potential gradient - membrane potential We would like to thank the SERC(UK) and the Royal Society for financial support.     

江苏省不同种植年限的西/甜瓜农田土壤线虫群落特征

在江苏省主要西/甜瓜产区,采集不同种植年限的西/甜瓜农田土壤,采用线虫形态学的鉴定方法,分析了不同种植年限西/甜瓜农田土壤线虫的数量、群落结构及相关生态指数的变化。结果表明:所有调查样点中,共发现土壤线虫54属,平均682条·100 g^-1干土,其中原杆属线虫、拟丽突属线虫和矮化属线虫在不同种植年限的西/甜瓜农田土壤中均为优势属;随着种植年限的增加,土壤线虫的总数量虽无显著变化,但其中食细菌类线虫和杂食-捕食类线虫数量显著减少,而植物寄生类线虫数量显著增加;植物寄生类线虫中的矮化属、根结属线虫数量不断增加;随着种植年限的增加,土壤线虫的多样性指数(H)、瓦斯乐斯卡指数(WI)、自由生活线虫成熟度指数(MI)显著降低,线虫通道指数(NCR)、植物寄生线虫成熟度指数(PPI)、PPI/MI显著升高,其他指数无显著变化;相关性分析结果显示,土壤线虫数量与土壤pH、速效磷、有效锌和有效硼均呈显著正相关;土壤p H、有机质、全氮、速效钾、有效硼和有效锌对土壤优势属线虫的影响较大;连续种植西/甜瓜会增加土壤植物寄生类线虫数量,进而可能造成西/甜瓜连作障碍的发生;连续种植6~10年,土壤线虫的多样性最低、稳定性最差,土壤环境已趋于恶化。