Microhabitat use by the larvae of cryptic lamprey species in <Emphasis Type="Italic">Lethenteron reissneri</Emphasis> in a sympatric area

Microhabitat use by the larvae of two cryptic lamprey species in Lethenteron reissneri, Lethenteron sp. N (northern form) and Lethenteron sp. S (southern form) larvae, as well as intraspecific variations on a size-related basis, were examined in a study area (500 × 5 m) located on a stream where they showed sympatric distribution. The total number of individuals collected from each of 31 quadrats (60 × 60 cm) ranged from 0 (0 n/m²) to 13 (36.1 n/m²). The distinct difference in habitat use was not observed between the two species in the present study area. Lamprey density was not significantly independent among the size groups (small and large) for each of Lethenteron sp. N and Lethenteron sp. S. The density of each size group of the two species was significantly correlated with some habitat variables, and stepwise multiple regression analysis revealed a positive association for a substrate with a smaller particle size and deeper depth for large individuals of Lethenteron sp. N and Lethenteron sp. S, respectively, suggesting that these conditions would be suitable for burrowing. On the other hand, small individuals of both species tended to occur in areas where there was a high content of medium sand and a faster current velocity, probably reflecting a preference for respiratory efficiency. Various condition of habitat should be maintained to conserve the cryptic lampreys.     

A comprehensive analysis of root morphological changes and nitrogen allocation in maize in response to low nitrogen stress

The plasticity of root architecture is crucial for plants to acclimate to unfavourable environments including low nitrogen (LN) stress. How maize roots coordinate the growth of axile roots and lateral roots (LRs), as well as longitudinal and radial cell behaviours in response to LN stress, remains unclear. Maize plants were cultivated hydroponically under control (4 mm nitrate) and LN (40 μm ) conditions. Temporal and spatial samples were taken to analyse changes in the morphology, anatomical structure and carbon/nitrogen (C/N) ratio in the axile root and LRs. LN stress increased axile root elongation, reduced the number of crown roots and decreased LR density and length. LN stress extended cell elongation zones and increased the mature cell length in the roots. LN stress reduced the cell diameter and total area of vessels and increased the amount of aerenchyma, but the number of cell layers in the crown root cortex was unchanged. The C/N ratio was higher in the axile roots than in the LRs. Maize roots acclimate to LN stress by optimizing the anatomical structure and N allocation. As a result, axile root elongation is favoured to efficiently find available N in the soil.     

云纹石斑鱼幼鱼血清生化指标对低温胁迫的响应

设置9、13、17℃3个温度梯度(17℃对照组),对云纹石斑鱼(Epinephelus moara)幼鱼进行7 d的胁迫实验,检测了血清中生化指标和代谢酶活力。结果表明:血清总蛋白(TP)和葡萄糖(GLU)含量在温度骤降后虽有变化,但无显著性差异(P0.05);血清中甘油三酯(TG)和肌酐(CREA)含量在水温骤降至9℃和13℃,7 d后与胁迫前比较均差异显著(P0.05);代谢酶指标中碱性磷酸酶(AKP)、谷草转氨酶(GOT)、谷丙转氨酶(GPT)和乳酸脱氢酶(LDH)的活力,随低温胁迫的强度和胁迫时间的延长活力都呈上升趋势,且实验结束时均与胁迫前差异显著(P0.05);乳酸脱氢酶活力在实验结束时各低温胁迫实验组之间也有显著性差异(P0.05);研究认为,在耐受温度范围的下限云纹石斑鱼幼鱼遭受低温骤降胁迫时,短期内血清生化指标不发生显著变化;幼鱼通过血清代谢酶活力的升高来响应低温胁迫,以提高抗应激能力;但停食会导致免疫力和抗氧化能力下降,因此实际生产中仍应降低胁迫强度和缩短胁迫时间。     

Design of the dike-pond system in the littoral zone of a tributary in the Three Gorges Reservoir, China

The Three Gorges Dam is the greatest water control project in the world with the largest fresh water littoral zone. Emergence of the littoral zone during the growing season provides some plants with the opportunity to complete their growth cycle, but the fluctuating water level also brings about some environmental problems, such as soil erosion, water pollution, and biodiversity reduction. A series of cascading terraced ponds located in the littoral zone of a secondary branch of the Yangtze River at Laotudi Bay was designed to be a dike-pond system for resolving the environmental problems of this special littoral zone while also making use of resources in an eco-friendly manner. The design of the dike-pond system is described in detail in this article, and some monitoring protocols are recommended for evaluating the environmental benefits of the system. The economic value of the dike-ponds was estimated to be about ¥125,986. Due to the ecological management mode adopted, 14 species of wild aquatic plants and 6 species of wading birds were found in the dike-pond system, in contrast to 9 species of wild aquatic plants and 3 species of wading birds in a comparable conventional farming area. It is hoped that dike-pond ecological engineering will be instrumental in reducing water pollution and increasing biodiversity in the littoral zone of the Three Gorges Reservoir.     

Co-digestion of intermediate landfill leachate and sewage sludge as a method of leachate utilization

This study examines the co-digestion of intermediate landfill leachate and sewage sludge from a municipal wastewater treatment plant. Application of leachate as a co-fermentation component increased the concentrations of soluble organic compounds (expressed as total organic carbon), ammonium nitrogen, and alkalinity in the digester influents.The biogas yield obtained from the co-fermentation of a 20:1 sewage sludge: intermediate leachate mixture was 1.30 m³ per kg of removed volatile solids (VS), while that from a 10:1 mixture was 1.24 m³ per kg of removed VS. These values exceeded the biogas yield for the sludge alone by 13% and 8%, respectively. The leachate addition influenced the proportion of methane to a minor extent. Increased methane yields of 16.9% and 6.2% per kg of removed VS were found for the two sewage sluge:intermediate leachate mixtures, respectively.     

药用植物富贵菜的研究现状与展望

富贵菜(Gynura divaricata DC.)是中国民间传统的药食兼用型多年生草本植物资源,具有清热、凉血、止痛、调节免疫、降血糖和抗肿瘤的功效。对富贵菜国内外研究进展进行了综述,内容涉及植物学特性、生态学特性、营养与保健、采后保鲜、栽培繁殖病虫害防治、功能化学成分及药理作用研究等方面。并在对其所存在的问题进行初步讨论的基础上,提出在加强种植资源遗传多样性研究与保护的同时,开展现在育种技术和栽培技术的研究,结合新兴生物技术和药理研究,开展富贵菜资源的综合运用。     

mRNA expression of genes involved in fatty acid utilization in skeletal muscle and white adipose tissues of sows during lactation

Rodents are able to lower fatty acid utilization in liver and muscle during lactation in order to spare fatty acids for the production of milk triacylglycerols, an effect which is mediated by a down-regulation of peroxisome proliferator-activated receptor α (PPARα). The present study was performed to investigate whether similar fatty acid sparing effects are developing in lactating sows. We considered PPARα and its target genes involved in fatty acid utilization in biopsy samples from muscle and adipose tissue of lactating compared to non-lactating sows. In muscle, PPARα target genes involved in fatty acid utilization were up-regulated during lactation indicating that the fatty acid utilization in muscle was increased. Activation of PPARα was probably due to increased concentrations of non-esterified fatty acids in plasma observed in the lactating sows. In contrast to muscle, PPARα and its target genes involved in β-oxidation in white adipose tissue were down-regulated in early lactation. Overall, the present study shows that sows, unlike rats, are not able to reduce the fatty acid utilization in muscle in order to spare fatty acids for milk production. However, fatty acid oxidation in adipose tissue is lowered during early lactation, an effect that might be helpful to conserve fatty acids released from adipose tissue for the delivery into other tissues, including mammary gland, via the blood.