Molecular Variability of the Capsid Protein of the Prune Dwarf Virus

Sequences of the capsid protein gene and the preceding intergenic region of eleven isolates of prune dwarf virus from central Europe were determined. The isolates were obtained from plum, cherry and peach trees. Comparison of all sequenced isolates (including two sequences published previously) revealed high (88%) conservation of the capsid protein gene. The highest degree of identity was observed in the C-terminal half, where only 13 amino acid substitutions could be observed in contrast to the N-terminal half with 22 substitutions. No reasonable correlation between amino acid substitutions and host species and/or geographic origin of the isolates was observed. Alignment with capsid protein genes of other ilarviruses revealed apple mosaic virus, elm mottle virus, lilac ring mottle virus and prunus necrotic ringspot virus as the most related to prune dwarf virus. Unlike the isolates of related prunus necrotic ringspot virus all the isolates of prune dwarf virus shared extensive conservation of the intergenic region. Portions of RNA3 were selected for design of universal primers for PCR detection.     

生态公路建设中野生动物保护意义与对策

随着公路建设的飞速发展,生态公路作为公路建设新理念受到了相关部门的高度重视,本文在总结国内外生态公路研究和实际工作经验的基础上,分析了生态公路内涵,并指出野生动物保护在生态公路建设中的意义以及保护对策,这对今后的生态公路建设具有一定的借鉴意义。     

思澜二级公路改建工程石拱桥加固利用

公路改建工程主要依托老路进行,旧桥加固利用是公路改建工程中重要的环节,对降低工程造价、缩短施工周期、缓解施工中的保通压力有其现实意义,针对思澜公路石拱桥加固利用,对老石拱桥加固技术和经济效益进行探讨。     

不同氨氮和溶解氧条件下循环海水养殖系统生物滤池对氨氮、化学耗氧量及颗粒悬浮物的处理效果

为了建立优化的循环海水养殖系统,采用水质国标检测方法分析了珊瑚石生物滤池在不同氨氮和溶解氧(DO)负荷实验条件下对养殖废水中氨氮、化学耗氧量(COD)及颗粒悬浮物(SS)的处理效果。结果显示,进水氨氮浓度对出水氨氮(正相关)、COD(正相关)均有极显著的影响(P0.01),对SS处理效果影响不显著。当进水氨氮浓度为0.45~0.65 mg/L时,滤池对水体处理效果最优(氨氮平均清除率为82.1%±3.3%;COD平均清除率为7.1%±1.5%;SS平均清除率为5.8%±1.6%)。DO浓度对水体氨氮(负相关)和COD(负相关)处理效果的影响显著(P0.05),对SS处理效果影响不显著。DO浓度为5.0~7.0 mg/L时,水体处理效果最优(氨氮平均清除率为78.7%±3.5%;COD平均清除率为23.0%±5.3%;SS平均清除率为7.1%±2.0%)。因此,本实验环境下的循环海水养殖系统珊瑚石生物滤池在氨氮浓度为0.45~0.65 mg/L,DO浓度为5.0~7.0 mg/L时,对水体中的氨氮、COD、SS的综合处理效果最优。     

麦饭石对重金属镉吸附效果的研究

通过体外试验分别从麦饭石的添加量、溶液pH、溶液初始浓度、吸附时间等方面研究麦饭石对重金属镉的吸附作用,确定其最佳吸附条件,并进一步研究麦饭石对其他矿物元素的吸附性。结果表明,麦饭石对重金属镉的吸附率随麦饭石添加量、溶液pH的增加而增加;随着溶液中镉的初始浓度的增加麦饭石的吸附率下降,麦饭石对镉的单位吸附量在镉的初始浓度为50 mg/L时达到最大,而吸附率随着溶液中镉的初始浓度的升高而降低;麦饭石对重金属镉的吸附在60 min时达到吸附平衡;在锌、铁、铜、锰、硒、镉和钴离子的混合溶液中,麦饭石对各种矿物元素的吸附大小为 Cd＞Fe＞Se＞Co＞Cu＞Zn＞Mn。     

丘陵区村镇水厂取水水源地水环境特征与综合治理-以四川省乐至县为例

对乐至县石河堰型水源地和水库型水源地进行调研,在对其自然环境和水环境对比分析的基础上,对石河堰型水源地和水库型水源地的水环境治理模式进行探讨,提出了源头控制结合生态修复的综合治理模式。     

The influence of instream cover and predation risk on microhabitat selection of stone loach Barbatula barbatula (L.)

Abstract— The microhabitat selection of stone loach ( Barbatula barbatula ) in relation to instream cover and predation risk was investigated in artificial streams. In one experiment, stone loach were presented different combinations of shelter structures, two at a time, that provided visual isolation, flow refuge, both, or none. In all cases, visual isolation shelters were selected by the fish, with little use of clear shelters and no apparent selection of flow refuges. In a second experiment, diel activity patterns and habitat selection of stone loach were measured when visual isolation structures were placed in the riffle only, pool only, both riffle and pool or in no habitat. Stone loach were marked with passive integrated transponder tags and a sensor plate was placed between the riffle and pool habitats to measure diel activity patterns. Habitat use was measured by releasing drop gates between the two habitats at the end of each trial. More stone loach used the pool than the riffle in all treatments, but use of the riffle increased when cover was present only there. Furthermore, stone loach were most active between 2100 and 0300. To determine the effect of predation threat on habitat use by stone loach, one adult brown trout ( Salmo trutta ) was added to each pool. The presence of trout caused stone loach to move into the riffle, especially the smaller loach. Overall, the study showed that stone loach used cover in a visual isolation context, preferring deeper water when there was no predation risk, but made more use of shallower water in the presence of brown trout.     

考虑雷诺数和形状影响的坝岸根石水平水流拖曳力系数修正

对于水利工程坝岸散抛根石冲揭失稳,水流作用下根石的拖曳力是重要的力学分析参数。该文基于黄河坝岸散抛根石的形状参数特征,利用水槽试验量测球体及不同形状块体受水流作用的水平拖曳力,研究雷诺数、物体形状指标与拖曳力相关关系及变化规律,明确影响因素,率定双因素影响下块体的拖曳力系数函数。结果表明,水下球体或近似球状物体的拖曳力系数,基本不受水流及物体形态影响,拖曳力系数趋于0.40～0.56;有棱角块体的水流拖曳力系数,块体雷诺数小于3×104的影响区域,系数函数呈双曲线趋势变化;块体雷诺数大于3×104的影响区域,迎水面宽高比不大于侧立面长高比,拖曳力系数趋于0.80～0.90,迎水面宽高比大于侧立面长高比,拖曳力系数趋于1.00～1.10。进一步通过试验修正了水流作用下不同形态物体的水平拖曳力系数,提出了块体雷诺数、形状参数双因素影响下物体水平拖曳力系数函数,得到了以不同物体来流方向投影响面积为基准的水平拖曳计算公式,经拟合公式的合理性分析与验证,拖曳力系数拟合优度达到0.90以上,平均相对误差为8.7%;修正后拖曳力平均相对误差仅为7.5%,公式计算效果良好,更准确地反映散抛根石的水下受力特征,为分析水下抛石受水流冲击离散形态提供理论依据。     

石灰岩山区果园生草对果树根系生态系统的效应

石灰岩山区果园生草可以提高生长季土壤含水量 ,稳定周年地温 ,提高土壤基础养分含量 ;改善土壤物理性能 ,从而促进果树根系发育。无芒雀麦和鸭茅草是石灰岩山区果园比较适宜的优良草种     

鸭梨果实石细胞分化特性研究

以鸭梨为试材,利用透射电镜显微技术和组织化学技术对梨果实石细胞分化及次生壁形成过程进行研究。结果表明,石细胞分化始于开花第7天,原生质体收缩于细胞一侧,随后胞内出现颗粒状凝聚物,次生壁逐渐增厚,之后胞质继续收缩消失,早期形成的石细胞多以群体形式同时出现。石细胞次生壁形成是逐步进行的,即先形成纤维素或半纤维素网架结构,再进行木质化填充。透射电镜下石细胞分化过程中依次呈现出细胞核染色质凝聚、细胞核变形、核膜界限不清晰的现象;胞内出现同心层次的自噬泡,形成大量囊泡;细胞核消失,内质网断裂并大量增生,质膜向内突起形成泡状结构;次生壁增厚,胞内细胞器仅有线粒体和内质网,最终细胞质收缩消失。