Gap formation and species diversity in Japanese beech forests: a test of the intermediate disturbance hypothesis on a geographic scale

To evaluate whether the intermediate-disturbance hypothesis applies on regional scales, the relationship between the species diversity and gap formation regime of beech forests was examined. The mean gap size and the variation of gap sizes showed no correlation with species diversity. The mean windstorm interval varied widely, but geographical trends, such as latitudinal gradient, were not observed. However, locations that sustained an intermediate frequency of disturbance had the highest species diversity. Although a latitudinal gradient of disturbance was not apparent, the intermediate-disturbance hypothesis was partly supported on a geographic scale. The most predictable model for species diversity was a multiple regression model composed of two factors, the windstorm interval and the cumulative temperature of the growing season. The fact that the temperature was of greater importance than the disturbance interval indicates that the most important factor in predicting forest species diversity is the amount of available energy on a geographic scale.     

Geographic and between-generation variation in the parasitoid communities associated with an invading gallwasp,Andricus quercuscalicis (Hymenoptera: Cynipidae)

The knopper gallwasp Andricus quercuscalicis Burgsdorf 1783 (Hymenoptera: Cynipidae) has invaded western and northern Europe from southern and eastern Europe over the last 400 years. A. quercuscalicis has two alternating generations, which differ in phenology, structure, and host oak species. This study describes geographic variation in the community in the tiny catkin galls of the sexual generation on Turkey oak, Quercus cerris, and compares the patterns obtained with those in the community attacking the alternate agamic generation. As predicted from considerations of parasitoid recruitment to the communities of invading phytophagous insects (Cornell and Hawkins 1993), in its native range the sexual generation shows (1) higher parasitoid community species richness, (2) higher total mortality due to parasitoid attack and (3) a higher ratio of specialist to generalist parasitoid species than is evident in the invaded range. Counter to predictions, there is no indication that parasitoid community richness in the invaded range has increased with time since the arrival of the new host. Higher host mortality in the native range is due principally to a single specialist, Aulogymnus obscuripes Mayr 1877 (Hymenoptera: Eulophidae), and is not distributed evenly among parasitoid species which attack the gall-former only in this area. This contrasts with the community in Britain, where three principal generalist parasitoids cause approximately equal mortalities. The agamic gall contains a taxonomically and structurally diverse guild of parasitoid and inquiline species, associated with the changing resource provided by a large, long-lived, complex gall. In contrast, the sexual community includes a taxonomically and structurally narrow guild, associated with a resource which is structurally simple, small in size and short-lived. No parasitoid species attacks the gall-former in both generations. Surprisingly, in spite of these differences in the nature of the gall resource in the two generations, over their entire range (native and invaded) the parasitoid guilds of the two are equally species rich.     

原生质体电融合酵母多倍体生理特性的研究

对原生质体电融合技术获得的11株酵母多倍体融合株,进行了一系列生理特性的分析比较．结果发现,在电融合过程中,融合株的细胞体积及DNA含量并不随着核倍性呈线性递增．而是有其特殊的变化规律。当糖化酵母sta1、sta2和sta3在细胞核中各自纯合时,明显表现出表达的剂量效应。其中sta1、sta2纯合的融合株．在YEPS培养中,GA分泌可被淀粉大量诱导,表现出一定的二次生长特性。从分析结果推测,在亲株5301-14D及HU-TY—1A中可能有对GA分泌不利的因素。     

异色芋生物学特性观察

本文对观赏植物异色芋（ＣｏｌｏｃａｓｉａｈｅｔｅｒｏｃｈｒｏｍａＨ．ＬｉｅｔＺ．Ｘ．Ｗｅｉ）在昆明栽培环境下的生物学特性进行总结,为商品化栽培异色芋提供了理论依据,为其分类也提供了一定的有益补充。结果表明：一年生植株不开花,根茎也不产生分枝;二年生植株开花率为７３．６％,根茎平均分枝３．６条。异色芋３月上旬开始萌动,７月中旬抽花梗,８月上旬开花,１１月份地上部分枯萎,因此在昆明异色芋生育期约２６０ｄ。     

Methanogenic granular sludge formation in an upflow anaerobic sludge blanket reactir treating synthetic methanolic waste

A laboratory upflow anaerobic sludge blanket reactor, seeded with fine, suspended, bacterial floc with 1.76 g volatile suspended solids/l, was used to treat synthetic methanolic waste. After 180 days of continuous peration, granular sludge with discrete granules of 1 to 2 mm diam. was formed, with 52 g volatile suspended solids/l. Granules were brown, relatively soft and had a settling velocity of 1.61 cm/s. Extracellular polymeric matter extracted from the granular sludge had high carbohydrate content but low nucleic acid content. The ash of the granular sludge contained Na⁺, K⁺ and Mg²⁺ up to 15.0, 11.7 and 3.75 mg/g, respectively. Scanning and transmission electron microscopy revealed that the granular sludge was dominated by methanogens resembling Methanosarcina.The authors are with the Department of Environmental Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565, Japan     

虎嘉鱼保护生物学的研究V.生境特点及保护对策

本文报道了虎嘉鱼的生境特点及保护对策,主要是加强宣传教育,严禁滥捕,深入研究,开展人工养殖试验和建立自然保护区等措施,确保物种生存和繁衍。     

Semen characteristics of Muturu Bulls--Bos brachyceros

Six mature Muturu Bulls were elecroejaculated once a week for nine weeks to study their semen quality and ejaculate characteristics. The semen volume was 1.8 ml +/- 0.1, the sperm concentration 2.16 x 10(8)/ml +/- 0.29, and the progressive sperm motility 36.2% +/- 2.6. Morphologically normal sperm averaged 70.0% +/- 3.1, primary abnormalities 13.4% +/- 1.0 and secondary abnormalities 15.1% +/- 2.3. Except in one bull, no measurable levels of fructose were observed. The contents of major cations and chloride ions in whole semen and seminal plasma were also determined.     

Nodulation studies on legumes exotic to Australia: Hedysarum coronarium

Abstract Symbiotic experiments in glasshouse, controlled environment cabinet, and field were conducted with four lines of sulla ( Hedysarum coronarium ) and 15 strains of Rhizobium spp. This plant is highly Rhizobium -specific and appropriate strains are most unlikely to occur naturally in Australia. Under several sets of experimental conditions, H. coronarium nodulated abundantly and effectively with homologous rhizobia introduced from Spain and Italy. The optimum temperature for nitrogen fixation was relatively low (approx. 21°C) but significant interactions between line of host, strain of rhizobia, and growth temperature were frequent. The rhizobia were persistent in soil.     

Amine transport at the plasmalemma of Riccia fluitans

Green thallus cells of the aquatic liverwort, Riccia fluitans, are rapidly depolarized in the presence of 1–20 μM NH₄Cl and 5–100 μM CH₃NH₃Cl, respectively. Simultaneously, the membrane conductance is increased from 0.41 to 1.2 S · m^?2. Uptake of [¹⁴C]methylamine is stimulated by increasing [K⁺]_o and inhibited by increasing [Na⁺]_o or [H⁺]_o, is highly voltage sensitive, and saturates at low amine concentrations.Double-reciprocal plots of (a) maximal membrane depolarization and (b) methylamine uptake vs. external amine concentration give apparent K_m values of 2 ± 1 μM ammonia and 25–50 μM methylamine; K_m values for changes in conductance and membrane current are greater and voltage dependent. Whereas the amine transport into the cell is strongly inhibited by CN^?, the amine efflux is stimulated.The current-voltage characteristics of the ammonia transport are represented by a sigmoid curve with an equilibrium potential of ?60 mV, and this is understood as a typical carrier curve with a saturation current of about 70 mA · m^?2. It is further concluded that the evidently carrier-mediated transport is competitive for the two amines tested, and that ammonia and methylamine are transported in the protonated form as NH₄⁺ and CH₃NH₃⁺ into the cytoplasm.     

Properties of enzymes from bacteria grown in the 70–100°C range

In chemostat cultures of Bacillus caldolyticus, adaptation in a single step from 70–100°C was followed under aerobic and oxygen-limited conditions and was found to proceed more smoothly under the latter circumstances. Variations of the medium (e.g. yeast extract or silicate concentrations) showed that growth at 100°C is in all respects similar to that of cultures at moderate temperatures.Enzyme preparations derived from cultures at 5°C intervals between 70 and 100°C were used to determine the temperature range. For all nine enzymes tested, the optimum temperature was found to be 67°C; the latter was independent of the growth temperature. Differences were found, however, with respect to the maximum temperature of individual enzymes, and three groups, with maxima between 70 and 80°C, 80 and 90°C and 90 and 100°C can be distinguished. Again, there was no correlation with the growth temperature.Stability experiments also revealed that enzymes from the same organism can have different thermal properties: Some were found to be quite thermolabile (e.g. the pyruvate kinase), while others (e.g. hexokinase and glutamate-pyruvate transaminase) exhibited a high thermostability. These properties were not related to the growth temperature within the 70–100°C range, too.Six of the enzymes tested could be stabilized by their respective substrates, but the degree of protection varied for individual enzymes. Three enzymes (acetate kinase, glutamate dehydrogenase and myokinase) could not be stabilized by their substrates.Comparative experiments with the hexokinase suggested, that the thermal integrity of the enzymes is better protected within the cell as compared to the stability of the enzyme preparations.Abbreviations used AK acetate kinase - Ala-DH alanine dehydrogenase - Ald aldolase - GIDH glutamate dehydrogenase - G6P-DH glucose-6-phosphate dehydrogenase - GTP glutamate-pyruvate transaminase - HK hexokinase - ICDH isocitrate dehydrogenase - MK myokinase - PK pyruvate kinase