Multiattribute evaluation of regional cotton variety trials

Summary The Australian Cotton Cultivar Trials (ACCT) are designed to investigate various cotton [Gossypium hirsutum (L.)] lines in several locations in New South Wales and Queensland each year. If these lines are to be assessed by the simultaneous use of yield and lint quality data, then a multivariate technique applicable to three-way data is desirable. Two such techniques, the mixture maximum likelihood method of clustering and three-mode principal component analysis, are described and used to analyze these data. Applied together, the methods enhance each other's usefulness in interpreting the information on the line response patterns across the locations. The methods provide a good integration of the responses across environments of the entries for the different attributes in the trials. For instance, using yield as the sole criterion, the excellence of the namcala and coker group for quality is overlooked. The analyses point to a decision in favor of either high yields of moderate to good quality lint or moderate yield but superior lint quality. The decisions indicated by the methods confirmed the selections made by the plant breeders. The procedures provide a less subjective, relatively easy to apply and interpret analytical method of describing the patterns of performance and associations in complex multiattribute and multilocation trials. This should lead to more efficient selection among lines in such trials.     

纳米孔测序技术在病毒性传染病检测及研究中的应用

快速、准确鉴定出病原体是临床感染性疾病诊断和传染病预防控制的基础。高通量测序基因检测技术突破了传统检测手段的时效性、灵敏度等的局限，为病原体检测和研究提供了便捷、高效的途径。本综述以高通量测序技术发展过程为基础，回顾纳米孔三代测序技术，及其在病毒性传染病检测鉴定及研究中的应用，并对该技术的应用前景及可能存在的问题进行阐述，期望它能在病毒性传染病的防控方面发挥更大的作用。     

Aggregating land use quantity and intensity to link water quality in upper catchment of Miyun Reservoir

Eutrophication resulting from nutrient enrichment decreases water quality and harms ecosystem structure and function, and its degree is significantly affected by land use in the catchment. Quantifying the relationship between eutrophication and land use can help effectively manage land use to improve water quality. Previous studies principally utilized land use quantity as an indicator to link water quality parameters, but these studies lacked insight into the impact of land use intensity. Taking the upper catchment of Miyun Reservoir as a case study, we developed a method of aggregating land use quantity and intensity to build a new land use indicator and tested its explanatory power on water quality. Six nutrient concentrations from 52 sub-watersheds covering the whole catchment were used to characterize the spatial distribution of eutrophication. Based on spatial techniques, empirical conversion coefficients, remote sensing data, and socio-economic statistical data, land use intensity was measured and mapped visually. The new land use indicator was calculated and linked to nutrient concentrations by Pearson correlation coefficients. Results demonstrated that our new indicator incorporating intensity information can quantify the different nutrient-exporting abilities of different land use areas. Compared to traditional indicators that only incorporate land use quantity, most Pearson correlation coefficients between the new indicator and water nutrient concentrations increased. This new information enhanced the explanatory power of land use on water nutrient concentrations, and so will be able to help us understand the impact of land use on water quality and guide decision making for better land use management.     

Modeling nutrients,oxygen and critical phosphorus loading in a shallow reservoir in China with a coupled water quality – Macrophytes model

Many macrophyte-dominated clear lakes switch to a phytoplankton-dominated turbid state when the lake becomes eutrophic. An existing Yuqiao Reservoir Water Quality Model (YRWQM) and the macrophyte submodel were coupled to simulate the effect of submerged macrophytes on nutrients and dissolve oxygen cycles in a shallow reservoir in China. The level of phosphorus loading in a transition from a clear to turbid state was addressed using the integrated model. The model runs from seedling establishment until dying out, from March 1 to July 18 in 2009. The simulations were performed for a contingent range of P loadings, starting from three different initial conditions. The results indicated that the integrated model improves accuracy of predictions compared to YRWQM. The concentrations of nutrients declined slightly during the macrophyte growth period in the reservoir and dissolved oxygen increased slightly. Although nutrient concentrations increased by submerged macrophyte release during the extinction period, the effect on the nutrients was less than that of transfer with nutrient-rich water. More released nutrients may enhance increases in substantial abundance. The critical phosphorus loading level during a switch from the clear to turbid state was estimated by these scenarios. The threshold for the switch is ∼6.1 mgP m⁻² d⁻¹ with an initial total phosphorus concentration of 160 μg l⁻¹. Moreover, the results demonstrated that the switch was also dependent on the initial total phosphorus concentration. These results suggest that the reservoir in a clear water state is at risk of a switch as nutrient levels are close to the critical levels.     

Three dimensional in vitro culture of preantral follicles following slow-freezing and vitrification of mouse ovarian tissue

To evaluate the effects slow-freezing and vitrification on three dimensional in vitro culture of preantral follicles, ovaries of 12–14 days old female NMRI mice were isolated and randomly assigned to fresh control, slow-freezing and vitrification groups. Slow-freezing was performed using programmable freezer. Vitrification was carried out in a medium consisting of ethylene glycol (EG) and dimethyl sulphoxide (Me₂SO) by needle immersion method. middle sized preantral follicles were mechanically isolated and cultured for 12 days in 0.7% sodium alginate gel. The follicles development and quantitative expression of oocyte specific genes (Bmp15, Gdf9, Fgf8) and the growth related genes (Igf1, Kit, Kit-l) were assessed after 1, 8 and 12 days of culture. Both cryopreserved groups showed reduction of follicular survival rates compared to the control group on days 8 and 12 of culture (P < 0.05). Antrum formation rates reduced in slow-freezing after 12 days of culture (P < 0.05). Evaluation of gene expression showed reduction of Bmp15, Gdf9, Fgf8, Kit and Kit-l during 12 days of culture (P < 0.05). Kit and Kit-l expression in slow-freezing group significantly reduced on day 8 of culture (p < 0.05). Igf1 expression was lower in slow-freezing group on 1st day of culture than vitrification and control groups (P < 0.05). Finally, intergroup comparison showed same expression pattern of genes after 12 days of culture. Thus, cryopreservation of mouse ovaries by both methods can preserve most developmental parameters and expression of maturation genes. However, vitrification is a better method for cryopreservation of mouse ovaries due to greater antrum formation and expression of growth related markers.     

长江三峡库区蝶类群落的物种获得率、小生境占有率及相对多度

研究于 1998～ 2 0 0 3年在库区 10个区县 ,35个调查点进行。研究时 ,库区蝴蝶的生活环境被划分为 80个小生境 ,设置样带6 6 1条 ;调查期间获得 (Sampled)蝴蝶 331种 ,10 780只个体。报道三峡库区蝴蝶群落的部分参数 :2 5 3种蝴蝶的小生境占有率低于 10 % ,占有 4 0 %以上小生境的蝴蝶只有 7种 ;在 6 0条以上样带都获得的蝴蝶有 16种 ,而在 10条以下样带内获得的蝴蝶 2 19种 ,占总数的 6 6 .2 % ;优势种 2 1个 (6 .3% ) ,常见种 12 5个 (37.8% ) ,少见种 10 3个 (31.1% ) ,罕见种 82个 (2 4 .8% ) ;相对多度高于 1%的种类 2 2个 ,仅占总数的 6 .6 % ;个体数分布的规律接近对数级数法则。三峡库区蝶类现在的分布反映了库区生境破碎化的结果 ,意味着适宜的生境斑块周围分布不适宜生境 ,种群受到面积、隔离、边缘等多种效应的影响 ,形成了现有的物种多样性及其空间格局     

三峡库区景观格局变化及其影响因素——以重庆市云阳县为例

从20世纪90年代中期至今是三峡库区生态-经济系统与景观格局发生重大变化的一段时期。论文通过对库区重庆市云阳县1994年与2002年遥感影像的解译,分析景观格局的变化,探讨生态建设、城镇化、基础设施建设、生态移民、农业产业结构调整等短时期内高强度的人类活动对该区域景观格局的影响。地形破碎、高差悬殊的山地特点以及在亚热带湿润气候主导下的山地立体气候分异等自然因素造成了景观格局的基本分异;有限的土地资源及其利用与分布状况是控制景观格局变化的主导因子;为保证三峡工程的顺利建设和安全运行而采取一系列生态经济建设活动成为促使景观格局变化的最重要的驱动因素;政治、经济和社会决策对景观格局变化具有重要影响。     

密度对濒危物种疏花水柏枝幼苗存活与生长的影响

疏花水柏枝(Myricarialaxiflora)原产于三峡库区长江干流的河滩,三峡水库的蓄水淹没了其所有的野生种群,使之濒临绝灭。通过一系列的密度处理实验,我们研究了不同密度下疏花水柏枝幼苗的存活率、幼苗总生物量、地下生物量、地上生物量、一级枝数、二级枝数、一级枝长度的变化,揭示了密度对一年生幼苗存活与生长的影响。结果显示,随着密度的增加,疏花水柏枝种群内部的竞争加剧,幼苗的死亡率增加,特别是当密度大于250ind./m2时,死亡率显著上升,上述体现植株生长状况的各指标值也随密度的增加而显著减小。表明疏花水柏枝一年生幼苗的存活与生长受到密度的影响。文中还建立了密度影响下疏花水柏枝各构件部分生长发育的回归模型,解释了密度对它们的调节作用。最后对疏花水柏枝种群重建中的相关问题进行了分析讨论,以求为回归引种实践提供参考。     

微囊藻毒素合成酶基因的PCR检测方法

针对微囊藻毒素合成酶基因簇的核酸序列,筛选特异性引物,探索一种适用于自然水样中微囊藻产毒潜能检测的全细胞PCR方法。经灵敏度测试表明,这种PCR方法的检测下限相当于100cells。该方法不需要提取基因组DNA,检测所需水样量少,具有操作简便、快速、成本低、灵敏度高等优点,能应用于水库等饮用水源水体中具有产毒潜能的微囊藻的检测。     

三峡水库及香溪河库湾理化特征的比较研究

根据2003年6月三峡水库初期蓄水后对香溪河库湾的常规监测,对该水域的理化特征及其动态进行了分析,并与三峡水库库首的数据进行了比较研究。结果显示库湾TN、NO3-N浓度要显著低于库首,前者两周年平均值为1.29mg/L,0.88mg/L,后者两周年平均值为1.62mg/L,1.22mg/L。而PO4-P则是库湾显著高于库首,并且在7—9月库首的TP/PO4-P有显著提高。结果同时表明库首的水土流失较严重,而库湾则有较好的水土保持。最后对TSIM的计算结果表明,由于TP、TN都处于高水平,库首呈现中营养化(TSIM>37),而库湾则呈现严重富营养化(TSIM>53)。