Simultaneous assessment of various responses of the soil microflora to bentazone

The effect of bentazone at 10 and 100 ppm in two soils on microbial activities and populations was investigated for 32 weeks. The higher concentration caused reductions in carbon dioxide output and oxygen uptake in both soils, In soil I (pH 6.4, organic C 1.7%) an increase in total mineral nitrogen occurred throughout but in soil H (pH 5.6, organic C 3.7%) a reduction in both mineralization of nitrogen and nitrification was observed from week 22 onwards. In general, populations of fungi and actinomycetes were resistant to or stimulated by bentazone, especially in soil II at 100 ppm. With bacteria, including cellulolytic and spore formers, cellulolytic fungi and actinomycetes, there was some inhibition even at the low concentration, effects being more pronounced in soil II than in soil I. The herbicide at 20 ppm had very little effect on growth and morphology of four fungal species in pure culture. Residue analyses showed that bentazone degraded more rapidly in soil II than in soil I although appreciable effects occurred throughout the experiment in both soils. Evaluation simultanée de diverses réactions de la microflore du sol à la bentazone. L'effet de la bentazone à 10 et 100 ppm sur les activités et les populations microbiennes a étéétudié pendant 32 semaines. La concentration la plus forte a provoqué des réductions du dégagement de dioxyde de carbone et de l'absorption d'oxygéne dans les deux sols. Dans le sol I (pH 6,4, teneur en carbone organique 1,7%) un accroissement de I'azote mineral total s'est constamment manifesté, mais, dans le sol II (pH 5,6, teneur en carbone organique 3,7%) une réduction simultanée de la minéralisation de I'azote et de la nitrification a été observée a partir de la 22ème semaine. D'une façon générale, les populations de champignons et d'actinomycétes se sont montrées résistantes à la bentazone, ou même stimulées par elle, en particulier pour le sol II à la concentration de 100 ppm. Avec les bactéries, y compris les formes sporultés et cellulolytiques, les champignons cellulolytiques et les aainomycétes, il s'est produit une certaine inhibition même à la concentration faible, ces cffets étant plus prononcés dans le sol II que dam le sol I. L'herbicide à 20 ppm n'a eu qu'une trés faible action sur la croissance et la morphologie de quatre espéces de champignons en culture pure Des analyses de résidus ont montré que la bentazone s'est dégradée plus rapiderment dans le sol II que dans le sol I, bien que des effets appréciables soieni apparus dans toute l'expérience avec les deux sols. Gleichzeitige Erfassung verschiedener Reaktionen der Bodenmikroflora auf Bentazon Es wurde die Wirkung von Bentazon (10 und 100 ppm) über 32 Wochen auf die mikrobielle Aktivität und auf die Mikroorganismenpopulationen zweier Boden untersucht. Durch die höhere Konzentration ging in beiden Boden die Abgabe von Kohlendioxid und die Aufnahme von Sauerstoff zurück. Im Boden I (pH 6,4; org. C l,7%) wurde während der gesamten Versuchszeit ein Anstieg des mineralischen Stickstoffs festgestellt, während im Boden II (pH 5,6; org. C 3,7%) ein Rückgang in der Stickstoffmineralisierung und der Nitrifikation ab der 22. Woche zu beobachten war. Im allgemeinen waren die Pilz- und Actinomycetenpopulationen gegenüber Bentazon resistent oder sie wurden durch das Herbizid gefördert, besonders im Boden II bei 100 ppm. Beiden Bakterien, einschliesslich zellulolytischer und sporenbildender Arten, den zellulolytischen Pilzen und Actinomyceten wurde eine geringe Hemmung, sogar bei der niedrigen Konzentration, festgestellt. Diese Effekte waren im Boden II stärker als im Boden I ausgeprägt. In Reinkultur hatten 20 ppm Bentazon nur eine gennge Wirkung auf das Wachstum und die Morphologie von vier Pilzarten. Rückstandsuntersuchungen ergaben, dass Bentazon im Boden II schneller ais im Boden I abgebaut wurde, es kam aber in beiden Böden zu deutlichen Effekten.     

盐碱土微生物功能群季节动态与土壤理化因子的关系

选取河西走廊东端永登县6种盐碱土壤类型,对各样地微生物功能群的季节动态与土壤理化因子之间的关系进行分析.结果表明:①盐碱环境中土壤细菌＞放线菌＞真菌,细菌和放线菌数量在夏季出现峰值,真菌数量在秋季和冬季出现峰值;不同微生物功能群基本上只有一个峰值且峰值出现的季节不同,与碳循环相关的纤维素分解菌功能群的峰值出现在冬季,与...     

以蔗糖为碳源制备1,6-二磷酸果糖的研究

研究了以蔗糖为碳源,用啤酒酵母发酵生产1,6-二磷酸果糖(FDP)的最佳条件.其优化控制条件为:摇床转速150 r/min,发酵温度28℃,pH 7.0,培养7 h,蔗糖浓度0.08 g/mL、磷酸二氢钠浓度0.05 g/mL、甲苯浓度0.05 mL/mL、啤酒酵母∶水=1∶4时,FDP的积累量最高,达42.87 mg/mL.     

Changes in urinary and plasma oestrone sulphate concentrations after induction of foetal death in mares at 45 days of gestation

Foetal death was induced in 10 Standardbred mares at day 45 of gestation by injecting 20 to 45 ml of hypertonic (24% W/V) saline into the conceptus at surgery. Ten mares underwent sham treatment and acted as controls. Blood and urine samples were collected every other day between days 30 and 45 post ovulation and at 0, 3 and 6 h relative to the infusion of saline in the treated mares, or sham treatment in control mares. Blood and urine samples were then collected daily between days 46 and 55 post ovulation. Urine oestrone sulphate (E1S) concentrations, measured by radioimmunoassay, increased between day 34 and day 36 of gestation in treated and control groups. In mares in which foetal death was induced, urine E1S concentrations declined post-operatively and were significantly (p less than .05) lower than controls by day 50. In plasma, E1S concentrations showed a major increase between days 36 and 40 in both groups. This was followed by a rapid decline after treatment in saline-injected mares, so that by day 48 plasma E1S concentrations in treated mares were significantly (P less than .05) lower than the controls. The results show that urinary and plasma E1S concentrations rise rapidly during early pregnancy, and are associated with a viable foetus after day 45 of pregnancy.     

基于PSR模型的都市近郊乡村旅游社区参与模式研究——以重庆市璧山县为例

[目的]完善旅游社区参与模式研究,为相似区域乡村旅游社区参与模式的构建提供借鉴.[方法]以重庆市璧山县为研究对象,分析都市近郊乡村旅游社区参与的特点,并通过该类区域PSR模型的分析,探讨不同游憩带适宜的乡村旅游社区参与模式.[结果]通过充分考虑PSR模型下的区域特点,分别总结出城市游憩圈带、近程游憩带和远程游憩带的游憩地配置模式、社区参与模式及社区发展核心.[结论]乡村旅游社区开发模式的选择应当依托区域要素,构建合理发展机制,避免各种经济、文化冲突.     

Wildlife veterinarian, conservation and public health

In recent years wildlife diseases (infectious and non-infectious) have played a relevant role in both wildlife conservation and public health. Global environmental changes have determined a bimodal evolution of wildlife. On one side a huge loss of biodiversity has been observed leading to the increasing of threatened or endangered species. In contrast few opportunistic taxa increased their aboundances and ranges. The above scenarios claim the intervention of wildlife veterinarians. In conservation the understanding of the ecological role of the host parasite relationship and the perturbations on the host population dynamics have to be assessed and eventually modified. In public health the increased overlapping among wildlife, livestock, pets and human beings represents a risk for diseases spread (no matter in which directions). Serious limits are, still now, observed in the acceptance of this 'new world' by veterinary academics. As a consequence curricula often fail in providing adequate skill at both undergraduate and graduate levels. An addressed approach towards wildlife diseases should be promoted as an essential component of environmental management.     

斜茎黄芪生物碱成分GC-MS分析

采用生物碱系统提取、薄层色谱和GC-MS分析技术,研究斜茎黄芪生物碱成分.结果表明,4.5 kg斜茎黄芪得到酸性和碱性氯仿部分生物碱分别为5.4g和3.6g,提取率为1.3％和0.8％;薄层色谱分析,酸性和碱性氯仿部分生物碱分别在氯仿∶甲醇=15∶1(Ⅴ∶ Ⅴ)和甲醇∶氨水=10∶1(Ⅴ∶Ⅴ)展开体系展开效果最佳,均呈现5个显色斑点;GC-MS分析,酸性和碱性氯仿部分各鉴定出7种生物碱,酸性氯仿部分以别隐品碱(34.84％)、原阿片碱(31.36％)和坎那定(21.46％)含量较高,碱性氯仿部分以别隐品碱(71.74％)、Oxyhydrostinine (7.45％)和坎那定(5.35％)含量较高.斜茎黄芪含有生物碱,且以别隐品碱、原阿片碱、坎那定碱和Oxyhydrostinine为主.     

云冷杉过伐林主要树种结构特征分析

选择长白山针阔比9∶1、8∶2、7∶3的云冷杉过伐混交林,探讨直径结构、空间格局、蓄积生长、林下更新以及植物多样性等林分结构问题,为恢复红松为主的针阔混交林,提出结构调整思路。研究表明:由于过去以不合理的非经营性采伐,红松成主要择伐对象,红松不同年份各径阶株数变化幅度较大,直径18 cm开始出现缺损株数现象,缺乏中、大径组株数,导致母树数量、结实量和种源减少,造成在主要树种中红松更新最差的问题,不利于林分正向演替。不同针阔比混交林空间格局与其主要树种空间格局并非完全一致,在同一林分不同树种间存在差异。针阔比9∶1、8∶2、7∶3的混交林空间格局分别为随机分布、聚集分布和均匀分布。其中,红松分布格局主要呈聚集分布。因此,恢复以红松为主的针阔混交林,以红松和珍贵阔叶树种作为目标树种,采取目标树培育方法,伐除影响其更新和生长的林木,而将云冷杉和一般阔叶树作为伴生树种,逐渐减少云冷杉的优势,最终逐渐恢复成红松阔叶混交林;对针阔比8∶2和7∶3混交林红松分布格局,采取人工补植、间伐等措施,结合天然更新,向随机分布进行调整;采取人工补植、清理母树周围枯枝落叶层等措施人工辅助红松天然更新。     

低剂量铅对大鼠大脑皮质神经细胞的毒性效应

本试验旨在研究低剂量铅对原代培养的大鼠大脑皮质神经细胞的存活及凋亡的影响。用新生24 h内SD大鼠,建立了大脑皮质神经细胞原代培养方法,通过不同浓度醋酸铅染毒后,用MTT法测定神经细胞的存活率;应用Hoechst 33258荧光染色和流式细胞仪检测铅对神经细胞凋亡的影响。结果表明,低剂量铅（50μmol/L）在3～6 h对神经细胞生长无明显作用,12 h后则表现抑制作用,其他各染毒组随剂量增加和作用时间的延长,细胞存活率逐渐下降,与对照组相比,作用12 h以上差异显著（P〈0.05）;Hoechst 33258荧光染色随染铅剂量的增加,细胞核呈新月形,染色质浓缩,出现凋亡小体,甚至核碎裂;细胞凋亡率随染毒剂量的增加而逐渐升高,对照组为0.7%,染铅组依次为1.1%、1.5%、1.9%、2.2%,而各染铅组细胞坏死率均为0.2%,与对照组比较只增加了0.1%。表明本试验所选择的铅浓度引起神经细胞死亡是以凋亡为主,低剂量铅具有抑制神经细胞存活和促进其凋亡的毒性作用。     

Niobium/Uranium Evidence for Early Formation of the Continental Crust

Niobium/uranium ratios in greenstone-belt basalts and gabbros indicate that parts of the Late Archean mantle beneath Western Australia underwent a level of melt extraction, resulting in formation of the continental crust, comparable to that seen in the present mantle. The implication is either that (i) the amount of continental crust that formed before 2.7 x 10(9) years ago was much greater than generally thought or (ii) crustal growth occurred by severe depletion of small volumes of the mantle rather than by moderate depletion of a large volume of mantle.