鼎湖山亚热带季风常绿阔叶林的生物量和光能利用效率

报道鼎湖山自然保护区黄果厚壳桂群落的生物量、生产力和光能利用效率。根据群落的种类成分和结构特征,分层选主要树种,用样本收获法和红外线ＣＯ２气体分析法,测定了群落的生物量、光合速率和呼吸速率,计算了群落的生产力和光能利用效率．结果表明,群落的生物量为２０８ｔ·ｈｍ－２;总生产力为１２８７０４ｋＪ·ｍ－３·ａ－１,净生产力为３０４５１ｋＪ·ｍ－２·ａ－１;由总生产力计算光合有效辐射能的吸收利用率为９,６６％,净生产力的利用率为２．２８６％,并与厚壳桂群落作比较,阐明了南亚热带森林群落的生产潜力．     

Cerebral Blood Flow and Oxidative Metabolism in Conscious Fischer-344 Rats of Different Ages

Abstract: The cerebral metabolic rates for O₂ and for glucose were measured in conscious, fasted male Fischer-344 rats at the ages of 3, 12, and 24 months, and cerebral blood flow was determined with ¹⁴C-iodoantipyrine. The metabolic rates for oxygen and glucose were obtained by multiplying blood flow by the O₂ and glucose concentration differences, respectively, between blood in the femoral artery and in the superior sagittal sinus. Mean cerebral blood flow and the metabolic rates for oxygen and glucose did not differ significantly (p > 0.05) between 3 and 12 or between 12 and 24 months. Nor did the arteriovenous differences for O₂ and for glucose change significantly with age. Because the superior sagittal sinus drains blood mainly from the cerebral cortex, the results indicate that average cerebral cortical oxidative metabolism, and the coupling ratios between the cerebral metabolic rate for oxygen and cerebral blood flow and between the cerebral metabolic rate for glucose and cerebral blood flow, do not change significantly with age in the Fischer-344 rat.     

Spruce budworm growth,development and food utilization on young and old balsam fir trees

Laboratory rearing of spruce budworm, Choristoneura fumiferana, in conjunction with field rearing, gravimetric analyses, a transfer experiment, and foliage chemical analyses at six dates during the period of budworm feeding activity indicated that the age of balsam fir, Abies balsamea, trees (70-year-old mature trees or 30-year-old juvenile trees) affected tree suitability for the spruce budworm via the chemical profile of the foliage. Insects reared on old trees had greater survival and pupal weight, shorter development times, and caused more defoliation than those reared on young trees. Young trees were more suitable for the development of young larvae (instars 2–5), while old trees were more suitable for the development of older, sixth-instar larvae. These results were confirmed by the laboratory transfer experiment. Young larvae fed foliage from young trees had higher relative growth rates (RGR), digestibility (AD), and efficiency of conversion of ingested foliage (ECI) than those fed foliage from old trees. These differences appeared to be related to the high N:tannins ratio, and the high contents of P present in young trees during the development of the young larvae. Old larvae fed foliage from old trees had higher relative growth rates, relative consumption rates (RCR), and digestibility of the foliage than those fed foliage from young trees. The high digestibility of the foliage of old trees was compensated for by a lower efficiency of conversion of digested food (ECD), which in turn resulted in no significant effect of tree age on the efficiency of conversion of ingested foliage by old larvae. The low relative consumption rate of old larvae fed foliage from young trees appeared to be related to the low N:tannins ratio, and the high contents of bornyl acetate, terpinolene, and °-3-carene present in young trees during the budworm sixth instar. Variations in these compounds in relation to tree age may serve as mechanisms of balsam fir resistance to spruce budworm by reducing the feeding rate of sixth instar larvae.     

Density and potential utilisation of medicinal grassland plants from Abe Bailey Nature Reserve, South Africa

The Abe Bailey Nature Reserve, South Africa has been identified as a potential community resource reserve compatible with biodiversity conservation. As part of the planning and public participation phase this study investigated the potential for sustainably harvesting medicinal plants. Medicinal plant use data on local species, parts used and harvesting techniques, in collaboration with neighbouring traditional healers were collected. A census of these plants was conducted in the reserve and frequency, density and abundance were calculated. A medicinal plant rating system for assessing conservation priorities was used to combine both social-qualitative and ecological-quantitative data. Five medicinal species suitable for high impact harvesting were identified. Thirty-four species have potential to be set up as harvesting trials to determine sustainable quotas. Thirty-one medicinal species including Boophane disticha, Dicoma anomala, Eucomis autumnalis, Hypoxis hemerocallidea, Pentanisia prunelloides and Indigofera daleoides are considered to be site-specific sensitive species and should not be harvested from the reserve. Following this research an on site nursery has been started at the reserve. A multi-pronged approach involving harvesting trials, propagation and plant rescue from developments to cope with escalating demand and dwindling natural populations needs to be implemented.     

不同等位HXT3基因对酿酒酵母EC1118发酵特性的影响

葡萄酒酿酒酵母果糖利用能力与酒精发酵中止和发酵不彻底密切相关,其果糖利用分子机制的研究备受关注。以高果糖利用葡萄酒酿酒酵母菌EC1118为试验材料,利用重组技术获得了HXT3基因敲除菌,通过酶切和基因测序鉴定,首次发现EC1118具有2个不同的HXT3等位基因,并研究了不同HXT3等位基因缺失对菌体发酵过程中葡萄糖、果糖利用的影响。结果表明,突变的HXT3-champ基因对保证菌体发酵后期高果糖利用能力起到了重要的作用,对筛选和构建高果糖利用优良葡萄酒酿酒酵母研究具有重要指导意义。     

盐胁迫下施肥对棉花生长及氮素利用的影响

利用海水配制不同含盐量(0、0.15%、0.3%)的土壤盆栽棉花,在可移动遮雨棚内研究了不同施肥(N、NK、NP、NPK)处理对棉花生长、氮素吸收与利用的影响.结果表明: 盐胁迫和施肥均影响棉花生物产量、棉株氮素农学利用效率、氮素生物利用效率和氮素积累量,且两者存在显著的互作效应.施肥能提高盐胁迫下棉株氮素利用效率及氮素积累量,并显著增产,不同施肥处理中以N、P、K肥料配合施用的效果最好;施肥效果受盐胁迫程度的影响,低盐胁迫(0.15%)下的施肥效果好于中度盐胁迫(0.3%).     

B型烟粉虱在四种葫芦科寄主植物上的发育和繁殖

研究了B型烟粉虱在4种葫芦科寄主植物黄瓜、节瓜、苦瓜和丝瓜上的发育和繁殖特性.结果表明,B型烟粉虱在节瓜上的世代发育历期最短,为19.3 d,在苦瓜上的世代发育历期最长,为29.0 d;世代存活率在黄瓜上最高,为92.85％,在苦瓜上最低,为53.08％;平均单雌产卵量在黄瓜上最多,为187.4粒,苦瓜上最少,为30.0粒;雌成虫寿命以在黄瓜上最长,为25.2 d,在苦瓜上最短,为10.9 d.B型烟粉虱在黄瓜、节瓜、苦瓜和丝瓜上的内禀增长率（r_m）分别为0.1453、0.1429、0.0616和0.1055.综合比较4种葫芦科植物,黄瓜是B型烟粉虱的最适宜寄主.     

一些海洋浮游植物量子产值的研究

现场实验以及用硅藻、金藻和绿藻所做的实验表明,在光饱和深度以下,随着深度的增加,浮游植物的量子产懂具有不变、增加和下降3种垂直变化趋势。偏离理论模式的后两种结果可能是由浮游植物的光强适应(Light-shade adaptation)等原因引起。还探讨了量子产值作为初级生产力模型和光利用效率模型中的参数的问题。     

Regulating Near-Space Activities: Using the Precedent of the Exclusive Economic Zone as a Model?

Abstract

The deployment of high-altitude vehicles in near space with the purpose of providing Internet, communication, and other services represents the new frontier of aerospace activities. Near-space operations are attracting growing interest due to their mult-purpose nature and their anticipated high profitability. Despite such positive perceptions, near-space plans are, however, hampered by the uncertain international legal status of near space. Using the precedent of the exclusive economic zone (EEZ), this article suggests a new categorization of the near space as the exclusive utilization space (EUS) and a set of rules to manage its utilization.     

An unusual pattern of carbohydrate utilization in Corallococcus (Myxococcus) coralloides (Myxobacterales)

The myxobacterium, Corallococcus (Myxococcus) coralloides strain Cc c127, could not utilize mono- and disaccharides, but maltotriose and the polysaccharides starch, amylose, amylopectin, and pullulan stimulated growth. Radioactive CO₂ was set free from ¹⁴C-labeled starch. When starch was degraded, small amounts of maltose and glucose accumulated in the culture supernatant. Maltotriose, however, appeared only temporarily. Outside the cells, the trisaccharide could not be split into glucose and maltose. Pullulan was hydrolyzed exclusively into a trisaccharide which during growth was immediately consumed. Hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and phosphoglucomutase could readily be demonstrated in cell extracts, but fructose-1,6-diphosphate aldolase was present with low activity only. The data suggest that intracellular glucose is metabolized mainly via the pentose phosphate pathway.Prof. Dr. Gerhard Drews gratefully dedicated to his 60th birthday