取食不同牧草对亚洲小车蝗发育速率和类胰岛素信号通路的影响

亚洲小车蝗是重要的草地生物灾害,对不同牧草的食物适应存在差异。为揭示不同牧草对亚洲小车蝗生长发育的影响机理,本研究定量分析了取食不同牧草条件下亚洲小车蝗的发育速率和类胰岛素信号通路(ISP)基因表达。结果表明,西北针茅饲喂的亚洲小车蝗发育速率最高,ISP通路中gIGF1、gINSR、gIRS1、gPI_3K、gAKT及gmTor基因表达显著上调(P0.05),调控下游发育和代谢相关的表皮蛋白(cuticle protein, gLCP)、胰凝乳蛋白酶(chymotrypsin, gCHY)及α-葡萄糖苷酶(α-glucosidase, gALP)基因表达上调。相反,冷蒿饲喂的蝗虫发育速率显著降低(P0.05),上述基因显著下调(P0.05),调控下游解毒相关的gP450s 6K1、gUDP 2C1及gCarE基因表达上调。亚洲小车蝗ISP通路响应食物差异,调控发育速率,以适应更广泛的生态区域,这可能是其分布广、易暴发成灾的原因之一。     

Soil and water conservation in Tigray (Northern Ethiopia): the traditional dagat technique and its integration with introduced techniques

Between the cultivated fields in the highlands of Tigray, one finds, besides the recently introduced stone bunds, many lynchets, with a height ranging from 0·3–3 m. Grasses occupy the riser and a more or less large strip on the shoulder. Traditionally, farmers established an untilled strip of about 2 m wide at the lower plot limit. This grass strip reduced runoff velocity, allowed for water to infiltrate and trapped sediment. Year after year, these lynchets, locally called dagat, continued to grow. In this study, the dagat technique is characterized and its evolution and reasons for partial destruction are outlined. Stereoscopic aerial photo analysis shows for the study area near Hagere Selam (13 °39′N, 39 °10′E, 2650 m a.s.l.) that 20·7 per cent of the major dagats (more than 1 metre high) have disappeared between 1974 and 1994. These lynchets, however, remain an important linear element in the landscape (22·7 m ha⁻¹, i.e. their density on cultivated fields is much higher). Of the smaller lynchets, a great proportion has been levelled in order to increase plot surfaces and spread fertile soil over the field. Famines and impoverishment caused the farmers to increase short‐term agricultural production in this way. Since the 1980s, the farmers built stone bunds on most of the cultivated land. Their average length equals 56·1 m ha⁻¹ in the study area. The establishment of stone bunds results in the development of small terraces. Especially during recent years, there is a tendency to integrate the traditional knowledge of dagat with the building of stone bunds. A quantitative assessment of the effectiveness of both techniques must be made. Copyright © 2000 John Wiley & Sons, Ltd.     

优良牧草和饲料作物中的有毒物质及其影响因素

论述了我国主要优良牧草和饲料作物中的一些种或品种，其中包括全国４３个当家草种的十几种牧草，所含有的有毒成分和毒物含量，及其对采食家畜产生的多种毒害作用和不良影响。同时，对影响有毒成分和毒物含量的各种因素进行了论述，为适时、合理地调整牧草和饲料作物的栽培管理技术和家畜日常管理尤其是放牧管理提供科学依据。     

呋喃唑酮对饲养水及草鱼体表粘液中菌群的影响

对饲养水中泼洒不同浓度（０．２ｍｇ／Ｌ、０．５ｍｇ／Ｌ和１．０ｍｇ／Ｌ）的呋喃唑酮后,研究了饲养水及草鱼体表粘液中好氧与兼性厌氧细菌的数量及组成变化。结果表明：用药前,饲养水及粘液中的菌群主要有Ａｅｒｏｍｏｎａｓ、Ｅｎｔｅｒｏｂａｃｔｅｒｉａｃｅａｅ、Ｖｉｂｒｉｏ、Ｆｌａｖｏｂａｃｔｅｒｉｕｍ、Ａｃｉｎｅｔｏｂａｃｔｅｒ、Ｐｓｅｕｄｏｍｏｎａｓ、Ｃｏｒｙｎｅｂａｃｔｅｒｉｕｍ、Ｓｔａｐｈｙｌｏｃｏｃｕｓ和Ｂａｃｉｌｕｓ,此外,水体中还检测到Ｍｉｃｒｏｃｏｃｕｓ和Ａｌｃａｌｉｇｅｎｅｓ。水体及粘液中的细菌数量在用药后１２ｈ或２４ｈ时降至最低,在４８ｈ或９６ｈ时恢复到原来的水平。用药后,水体及粘液中的优势菌群未发生改变,但Ｆｌａｖｏｂａｃｔｅｒｉｕｍ的比例显著增加,Ａｅｒｏｍｏｎａｓ、Ｖｉｂｒｉｏ和Ｅｎｔｅｒｏｂａｃｔｅｒｉａｃｅａｅ明显减少,Ｐｓｅｕｄｏｍｏｎａｓ和Ａｃｉｎｅｔｏｂａｃｔｅｒ则未能检测到,其他各类群的比例也有一定的变化。菌群的变化速度与用药浓度有关。     

Ⅱ型草鱼呼肠孤病毒在稀有鮈鲫中的传播途径研究

草鱼呼肠孤病毒（GCRV）引起的草鱼出血病是造成我国草鱼养殖风险的主要疾病之一。II型草鱼呼肠孤病毒（GCRV-Ⅱ）是草鱼出血病的主要致病毒株,为了研究其流行规律,本文基于稀有鮈鲫感染GCRV-JX02的研究模型,利用分子生物学检测,RT-qPCR定量等方法开展GCRV-II水平和垂直传播的研究,结果显示,水平传播中浸泡感染和共培养感染都能使稀有鮈鲫成为GCRV-II的无症状携带者,阳性检出率分别为50%和80%;其中共培养感染直接导致8%的稀有鮈鲫死亡。感染后无症状的稀有鮈鲫经热休克处理,浸泡感染与共培养感染组的死亡率分别为57.14%和100%,总体阳性检出率分别为80.95%和100%。腹腔注射感染GCRV-JX02后存活的无症状稀有鮈鲫每0.01克精巢与卵巢中病毒拷贝数分别为3.64×106和6.84×106。垂直传播实验中稀有鮈鲫单个的卵子、未受精卵、受精卵和幼鱼的平均病毒拷贝数为1.98×103、1.15×104、4.75×103和6.74×104,幼鱼中病毒的拷贝数显著高于卵子与受精卵时期,表明GCRV-JX02不仅能够在稀有鮈鲫中垂直传播,还能伴随幼鱼的发育不断扩增。本研究阐明了不同传播途径下GCRV-Ⅱ的传播潜力,有助于评估草鱼出血病的流行风险,且为筛选阻断草鱼呼肠孤病毒传播的药物提供了有效的动物模型。     

百色市野生草坪草生物学及坪用特性评价

为筛选适合百色市气候环境条件及符合荫蔽地带绿化要求的野生草坪草植物资源,对百色市乡土野生草坪草资源进行了调查和物种鉴定,并作了初步的驯化栽培试验,结果表明,狗牙根、链荚豆和中华结缕草适合作游憩草坪、保土草坪和运动草坪,铺地蝙蝠草和铜锤玉带草宜与其他草种混播建坪,而酢浆草和三点金是林下、建筑物阴面等荫蔽地带绿化的适宜草种。     

SCAR标记在作物和牧草上的应用现状及前景

测序扩增区段(SCAR)标记是基于PCR技术的单基因位点多态性标记,相对其他分子标记,他具有开发成本低,稳定性高,单位点多态等特点,近10年内被广泛用于分子标记辅助选择、抗病(虫)基因连锁定位、高密度遗传图谱构建、种质纯度及品种鉴别等方面。回顾了近几年国内外关于SCAR标记的研究进展,应加强SCAR标记在牧草品种选育(尤其是抗病虫、抗逆),鉴定和种质评价方面的研究。     

Designing a sampling scheme to reveal correlations between weeds and soil properties at multiple spatial scales

Weeds tend to aggregate in patches within fields, and there is evidence that this is partly owing to variation in soil properties. Because the processes driving soil heterogeneity operate at various scales, the strength of the relations between soil properties and weed density would also be expected to be scale‐dependent. Quantifying these effects of scale on weed patch dynamics is essential to guide the design of discrete sampling protocols for mapping weed distribution. We developed a general method that uses novel within‐field nested sampling and residual maximum‐likelihood (reml ) estimation to explore scale‐dependent relations between weeds and soil properties. We validated the method using a case study of Alopecurus myosuroides in winter wheat. Using reml , we partitioned the variance and covariance into scale‐specific components and estimated the correlations between the weed counts and soil properties at each scale. We used variograms to quantify the spatial structure in the data and to map variables by kriging. Our methodology successfully captured the effect of scale on a number of edaphic drivers of weed patchiness. The overall Pearson correlations between A. myosuroides and soil organic matter and clay content were weak and masked the stronger correlations at >50 m. Knowing how the variance was partitioned across the spatial scales, we optimised the sampling design to focus sampling effort at those scales that contributed most to the total variance. The methods have the potential to guide patch spraying of weeds by identifying areas of the field that are vulnerable to weed establishment.     

Simple sequence repeat analysis of genetic diversity among Acetyl‐CoA carboxylase inhibitor‐resistant and ‐susceptible Echinochloa crus‐galli and E. oryzicola populations in Korea

Echinochloa species are amongst the most problematic weeds in rice fields of Korea. The steady reliance on the Acetyl‐CoA carboxylase (ACCase) and acetolactate synthase inhibiting herbicides for control of these weeds has led to resistance to these herbicides. The objective of this study was to assess the genetic diversity among populations of ACCase inhibitor‐resistant and ‐susceptible Echinochloa crus‐galli and E. oryzicola in Korea, to better understand their population structure and possible origins of resistance. Seven simple sequence repeat markers were applied to assess the genetic diversity between resistant and susceptible E. crus‐galli and E. oryzicola from 12 populations in Korea. Genetic diversity was slightly higher in the resistant group. The Unweighted Pair Group Method using Arithmetic algorithm (UPGMA) dendrogram generated two distinct clades. One clade consisted of Echinochloa spp. from three populations, i.e. Anmyeondo, Gimje 4 and Gongju, which are resistant and differentiated from the susceptible populations, and the other clade contained the rest of the populations. Structure modelling supported two clades of UPGMA clustering. Based on these data, we can infer that some resistant populations are greatly differentiated, whereas other resistant biotypes are still building up resistance in rice fields in Korea. Resistance traits will be fixed and continue to spread over time without proper control measures.     

高寒矿区人工种草对露天排土场渣山表层基质的影响

露天煤矿开采引起了祁连山区高寒湿地生态环境的部分破坏,本文通过调查7个矿区植被恢复状况,研究了青海木里煤田矿区人工种草对排土场渣山表层基质理化性质的影响,为高寒矿区植被复绿提供参考。结果表明：人工种草可以有效改善排土场渣山表层基质含水量,增加土壤微生物的数量,影响排土场渣山表层基质有机质含量。种草区域细菌、真菌、放线菌平均数量分别是不种草区域的4.20,4.05和2.29倍。7个矿区排土场渣山表层基质速效氮分布极不均衡,差异显著（P<0.05）,种草区域明显高于非种草区域。人工种草后绝大多数矿区全氮、速效磷和速效钾含量明显增加,全钾含量降低。除汞元素外,种草对其它7种重金属（砷、铬、镉、铜、铅、镍、锌）含量产生不同程度的影响,7个矿区砷含量平均值从4.61 mg·kg^-1增加到6.06 mg·kg^-1。