康定虫草主要寄主斜脉蝠蛾的研究

冬虫夏草是一味名贵的中药材.四川康定虫草的主要寄主斜脉蝠蛾翅面色斑多变异,可区分成“黑白斑”和“黄毛斑”两大色斑型.经交配试验和成虫形态特征(触角、口器、翅脉、前足、雌雄外生殖器和鳞片的超微结构等)的观察,证明为同一种,经鉴定是斜脉蝠蛾(Hepialus oblifurcus Chu et Wang)^**.     

鹅掌楸种子和胚胎发育的研究

应用控制授粉、软 X-射线法、常规石蜡制片法和荧光检测等手段,研究了鹅掌楸(Lirio-dendron chinense(Hemsl.)Sarg.胚胎发育和控制授粉与结籽率的相关性。控制授粉后2小时花粉萌发,6小时萌发率最高,柱头可授期持续30小时左右。花粉管借助于柱头毛之间的分泌物进入柱头沟,经花柱沟、珠孔塞和珠心冠原进入胚囊,行珠孔受精。授粉后2周,胚乳为2至3细胞厚的狭组织;第6周,胚乳充满胚囊腔,珠心随之解体殆尽;第7到8周,球形胚、心形胚发生;第14到16周,子叶形成;第22周种子或熟,胚乳丰富。单株自然授粉结籽率不足1%。控制授粉后,单个聚合果的最高结籽率可达39%,9个聚合果的平均结籽率为17.7%。     

Control of nitrogenase inAzospirillum sp.

Many N₂-fixing organisms can turn off nitrogenase activity in the presence of NH₄ ⁺ and turn it on again when the NH₄ ⁺ is exhausted. One of the most interesting systems for accomplishing this is by covalent modification of one subunit of dinitrogenase reductase by dinitrogenase reductase ADP-ribosyltransferase (DRAT). The system can be reactivated when NH₄ ⁺ is exhausted, by dinitrogenase reductase activating glycohydrolase (DRAG) which removes the inactivating group. It is fascinating that some species of the genusAzospirillum possess the DRAT and DRAG systems (A. lipoferum andA. brasilense), whereasA. amazonense in the same genus lacks DRAT and DRAG.A. amazonense responds to NH₄ ⁺ but does not exhibit modification of dinitrogenase reductase characteristic of the action of DRAT. However, it has been possible to clone DRAT and DRAG and to introduce them intoA. amazonense, whereupon they become functional in this organism. The DRAT and DRAG system does not appear to function inAcetobacter diazotrophicus, an organism isolated from sugar cane, that fixes N₂ at a pH as low as 3.0.A. diazotrophicus does show a rather sluggish response to NH₄ ⁺. A level of about 10 M NH₄ ⁺ is required to switch off the system. The response to NH₄ ⁺ is influenced by the dissolved oxygen concentration (DOC) as has been reported forAzospirillum sp. A DOC in equilibrium with 0.1 to 0.2 kPa O₂ seems optimal for the response inA. diazotrophicus.     

Role of magnesium in combination with liming in alleviating acid-soil stress with the aluminium-sensitive sorghum genotype CV323

An experiment to study the effects of Mg nutrition on root and shoot development of the Al-sensitive sorghum (Sorghum bicolor (L.) Moench) genotype CV323 grown in pots of sandy loam under different acid soil stress is reported. This experiment had a factorial design: four rates of liming were combined with four rates of Mg fertilization. When no Mg was added, the pH of the soil solutions (collected in ceramic cups) increased from 4.0 (unlimed) to 4.2, 4.7 and 5.9 at the increasing rates of liming. After 30 days of growth dry matter yields of the limed treatments were 40%, 115% and 199% higher than that of the unlimed treatment. Without liming and at the highest liming rate, adding Mg did not affect plant biomass significantly. At the two intermediate levels of liming, however, 11.3 mg extra Mg per kg soil increased dry matter yield to the same levels as found at the highest liming rate. Concentrations of Mg in the soil solution rose after Mg was added and fell when lime was added, but adding both Mg and lime increased Mg concentrations in the plant shoots. In plants of the limed treatments, dry matter yield was correlated closely with the Mg concentration in the shoot. This was not so in the unlimed treatment. Furthermore, in the unlimed treatments root development was inhibited, but reduced Mg uptake by the plants resulted mainly from the direct effect of Al- (or H-) ions in the soil solution rather than from impaired root development. It is concluded that Mg fertilization counteracted the interfering effects of Al- and H ions on Mg uptake.     

New disease resistance genes in soybean against Pseudomonas syringae pv glycinea: evidence that one of them interacts with a bacterial elicitor

Summary Soybean [Glycine max (L.) Merr.] cultivars Flambeau and Merit differed in their resistance to Pseudomonas syringae pv glycinea (Psg) race 4, carrying each of four different avirulence (avr) genes cloned from Psg or the related bacterium, Pseudomonas syringae pv tomato. Segregation data for F₂ and F₃ progeny of Flambeau x Merit crosses indicated that single dominant and nonallelic genes account for resistance to Psg race 4, carrying avirulence genes avrA, avrB, avrC, or avrD. Segregants were also recovered that carried all four or none of the disease resistance genes. One of the disease resistance genes (Rpg1, complementing bacterial avirulence gene B) had been described previously, but the other three genes — designated Rpg2, Rpg3, and Rpg4 — had not here to fore been defined. Rpg3 and Rpg4 are linked (40.5 ± 3.2 recombination units). Rpg4 complements avrD, cloned from Pseudomonas syringae pv tomato, but a functional copy of this avirulence gene has not thus far been observed in Pseudomonas syringae pv glycinea. Resistance gene Rpg4 therefore may account in part for the resistance of soybean to Pseudomonas syringae pv tomato and other pathogens harboring avrD.     

Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium

The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNA^Ile (GAU) and tRNA^Ala (UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by small-sized rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.     

浙江猫蛛科一新种：蜘蛛目

在浙江三门发现猫蛛科一新种,暂归人哈猫蛛属,定名为三门哈猫蛛Hamataliwa sanmenensis sp.nov.本新种与三突哈猫蛛H.tricuspidata相近似,但有明显区别。本属为我国新纪录属。     

Interacting effects of increased tannin levels on leaf-mining insects

Tannin-rich extracts were painted on leaves of Q. emoryi (Fagaceae) that contained first instar larvae of a leaf miner, Cameraria sp. (Lepidoptera: Gracillariidae, Agrifoliella group), to test the role of tannins in increasing parasitism, while controlling for changes in protein content and physical damage. Miners from leaves that were treated with tannins had higher rates of parasitism by hymenopterans, but decreased mortality from other causes. The negative and positive effects of tannins balanced since overall larval survivorship was equivalent for leaf miners on tannin-enriched and control leaves. The tannin-rich extract also affected larval development because pupal weight was decreased for leaf miners in treated leaves. Tannins can have both adverse and beneficial effects on these phytophagous insects.

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Résumé Des extraits riches en tanins ont été étalés sur des feuilles de Quercus emoryi contenant des chenilles de ler stade de Cameraria sp., pour contrôler l'influence du tanin dans l'accroissement du parasitisme sans modifier la teneur en protéines ni provoquer de dommages physiques. Les mineuses de feuilles traitées avaient des taux plus élevés de parasitisme par les hyménoptères, mais une diminution des autres causes de mortalité. Les effets négatifs et positifs des tanins se sont équilibrés, puisque la survie des mineuses était la même pour les feuilles traitées que pour les témoins. Les extraits riches en tanin ont agi sur le développement larvaire puisque le poids des chrysalides des mineuses de feuilles traitées était plus faible. Les tanins peuvent ainsi avoir des effets nuisibles et bénéfiques sur ces insectes phytophages.

     

横断山齿突蟾属一新种(两栖纲:锄足蟾科)

1982年在横断山区考察期间,发现四川木里截族自治县的齿突蟾Scutiger标本在第二性征、趾蹼等特征与已知的各种齿突蟾均不相同,描述为新种木里齿突蟾Scutiger muliensis。     

神农香菊干花净油成分的研究

神农香菊全草提取的香浸膏香气浓郁独特,可用于调配多种高档化妆用香精,也可直接用于饮料中,在香精香料工业中具有较大的实用价值。本文首次报告了我们用毛细管气相色谱仪和色谱/质谱/计算机联用分析仪,对神农香菊干花净油成分进行分析的初步结果。鉴定出的已知成分包括脂肪族类,含氧或非含氧的单萜及倍半萜类化合物32个。