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.     

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.     

土地利用变化对三峡库区重庆段植被净初级生产力的影响

研究土地利用变化对区域植被净初级生产力(Net Primary Productivity,NPP)的影响对于明确区域植被固碳能力与土地利用变化的关系,以及维持生态系统结构稳定具有重要意义。以三峡库区重庆段为例,基于2000—2015年MOD17A3数据和土地利用数据,分析研究区NPP时空分布特征并从景观生态学的角度探讨土地利用变化对区域植被NPP的影响。研究表明:(1)NPP年均值16年间波动不大,空间分布上从东到西逐渐减少;(2)研究期内林地面积增加,耕地和草地面积减小,而NPP总量从25.6 TgC增加到了28.5 TgC,其中耕地NPP约占总量的44%,林地次之(40%),草地最少(14%),2000—2005年、2005—2010年、2010—2015年土地利用变化对NPP变化的贡献率分别为26.49%、59.76%、17.27%;(3)区域生态景观指数中的香农多样性指数SHDI、斑块密度PD与NPP呈正相关,而聚合度AI与NPP呈负相关,景观格局类型和景观格局变化均影响区域植被NPP的增长。要提高区域植被NPP,需优化土地利用格局,增加景观异质性和斑块密度,重视培育幼龄林,并控制成熟林的数量。     

三峡库区不同水文类型支流大型底栖动物对蓄水的响应

为探究三峡水库修建对库区不同水文类型支流大型底栖动物的影响,于2015年7月和2016年1月对三峡水库四条支流的大型底栖动物进行调研,分别对周期性受蓄水影响支流的非回水区与回水区和长期受蓄水影响支流的非回水区与回水区大型底栖动物群落结构进行比较研究,结果表明:⑴7月份三峡水库145米低水位时期共采集到底栖动物655头计59种(属),在受蓄水影响河段采集到底栖动物4种共40头,优势种为日本沼虾(占受蓄水影响区域的57.5%); 1月份三峡水库175米蓄水时期共采集到底栖动物1123头计69种(属),在受蓄水影响河段采集到16种238头,优势种为锯齿新米虾(占受蓄水影响区域的14.2%)。⑵周期性受蓄水影响支流的非回水区与回水区底栖动物密度、生物量和多样性指数无显著差异(P0.05);长期受蓄水影响支流的非回水区与回水区之间底栖动物密度和Pielou均匀度指数无显著差异(P0.05),但非回水区底栖动物生物量显著高于回水区(P0.05),底栖动物多样性和丰富度极显著高于回水区(P0.01)。⑶7月份影响底栖动物分布的主要环境因子共6个,分别是水深、流速、硝态氮、溶解氧、水温和电导率; 1月份影响底栖动物分布的主要环境因子共7个,分别是水温、溶解氧、总磷、流速、深度、电导率和透明度。     

三峡库区支流生境因子对库区蓄水的响应

三峡水库的运行调度,使库区支流形成了截然不同的3种河段类型:完全受水库蓄水影响的145m回水段(完全河段),既受蓄水影响又受自然洪汛影响的145—175m回水段(双重河段)以及不受蓄水影响的大于175m的自然河流段(自然河段)。为明确库区蓄水对河流不同河段生境因子的影响程度及差异,对三峡库区36条重要支流的254个河段进行河流生境调查,进行不同河段下生境指标的因子分析,并进一步分析水文情势自然性与不同河段各生境因子的相关关系。结果表明,植被状况对3种不同河段来说均为重要生境因子,但受三峡水库蓄水影响,完全河段植被结构不完整;受库区蓄水影响,完全河段与双重河段及自然河段相比,流速流态状况、表层覆盖物状况、河岸带宽度、湿润率等生境因子有明显改变;水文情势自然性对不同河段生境因子的影响不同。     

落羽杉根系有机酸与NSC代谢对三峡消落带水位变化的响应

为探究三峡库区消落带水位变化下落羽杉根系有机酸和非结构性碳水化合物(NSC)的响应特征,以适生木本植物落羽杉为对象,在消落带原位环境中设置对照-SS(海拔175 m,试验期间无水淹)、MS(海拔170 m,中度水淹胁迫)和DS(海拔165 m,深度水淹胁迫)3个处理,分别于海拔170 m和165 m退水时采集样品,测定并分析根系有机酸和NSC的变化。结果表明:(1)库区水淹对落羽杉基径无显著影响,仅有DS组明显抑制了高生长,落羽杉生长能较积极地响应库区水淹。(2)库区水淹对落羽杉侧根和总根有机酸的影响一致,侧根有机酸代谢作用优于主根。与SS组相比,MS组根系有机酸含量增高,DS组根系有机酸含量降低,除部分根系酒石酸、苹果酸、柠檬酸变化达到显著水平外,其余有机酸均无显著变化。(3)库区不同强度水淹对落羽杉根系NSC有不同程度的影响。与SS组相比,MS组可溶性糖无显著变化,淀粉、NSC含量显著增加,但总根NSC在水淹前与水淹后无明显差异;形成鲜明对比的是,DS组显著降低了可溶性糖、NSC含量,对淀粉无显著影响,且水淹后总根NSC显著低于水淹前。(4)相关分析表明,主根、总根草酸、苹果酸、柠檬酸及侧根、总根莽草酸分别与淀粉、NSC间表现出显著相关性(P0.05)。研究结果表明,在三峡库区消落带水淹胁迫下,落羽杉根系有机酸与NSC代谢联系紧密。通过维持一定的根系淀粉含量,保持植株正常的有机酸代谢水平,较好地适应三峡库区消落带生境。     

Spatial patterns of landscape change in the Three Rivers Headwaters Region of China, 1987–2015

The Three Rivers Headwaters Region is one of the most import ecological protection regions and Tibetan inhabited regions in China. Located in the Qinghai province of China, the Region is the source of the Yangtze, the Yellow and the Lantsang-Mekong Rivers. This study region was based on remote sensing imagery. An ecological landscape classification of the area is presented, as well as a suite of landscape indices for landscape pattern changes from 1987 to 2015. The influence of human activities on the landscape change of study area is discussed. The results showed landscape structure complexity, fragmentation gradually increased, while the indices of contagion and evenness were decreased. Structure characteristic of landscape change in this region are more obvious, especially, the difference in space distributions of part and the whole. There were trend of uniform distribution of different types and diversity gradually increased in the source of Yangtze River. And an opposite tendency is showing in the Yellow River and Lantsang-Mekong River. Physical-geographical conditions, climate change and government policy at study period were the main reasons of significant landscape pattern change. This study proposes management measures for sustainable development in the Three Rivers Headwaters Region.     

Biology, fisheries, and conservation of sturgeons and paddlefish in China

This paper reviews five of the eight species of acipenseriforms that occur in China, chiefly those of the Amur and Yangtze rivers. Kaluga Huso dauricus and Amur sturgeon Acipenser schrenckii are endemic to the Amur River. Both species still support fisheries, but stocks are declining due to overfishing. Acipenseriformes of the Yangtze River are primarily threatened by hydroelectric dams that block free passage to spawning and feeding areas. The Chinese paddlefish Psephurus gladius now is rare in the Yangtze River system, and its spawning activities were severely limited by completion of the Gezhouba Dam in 1981. Since 1988, only 3–10 adult paddlefishes per year have been found below the dam. Limited spawning still exists above the dam, but when the new Three Gorges Dam is complete, it will further threaten the paddlefish. Artificial propagation appears to be the only hope for preventing extinction of P. gladius, but it has yet to be successfully bred in captivity. Dabry's sturgeon A. dabryanus is a small, exclusively freshwater sturgeon found only in the Yangtze River system. It is concentrated today in reaches of the main stream above Gezhouba Dam. The fishery has been closed since 1983, but populations continue to decline. Acipenser dabryanus has been cultured since the 1970s, and holds promise for commercial aquaculture; availability of aquacultural methods offers hope for enhancing natural populations. The Chinese sturgeon A. sinensis occurs in the Yangtze and Pearl rivers and seas of east Asia. There is still disagreement about the taxonomy of the Pearl and Yangtze River populations. The Yangtze River population is anadromous. Adults begin spawning at about age 14 years (males) and 21 years (females), and adults spend over 15 months in the river for reproduction. Spawning sites of A. sinensis were found every year since 1982 below the Gezhouba Dam, but it seems that insufficient suitable ground is available for spawning. Since 1983, commercial fishing has been prohibited but more measures need to be taken such as establishing protected areas and characterizing critical spawning, summering and wintering habitats.     

三峡工程运行后对洞庭湖湿地的影响

长江三峡工程建成运行后,其下游第一个大型通江湖泊——洞庭湖的水文、水质以及湿地环境等均发生了很大变化。三峡工程已经开始影响到洞庭湖的泥沙淤积、水位波动、水质以及植被演替等。以三峡水库调度运行方案、河湖交互作用和洞庭湖湿地植被分布格局为基础,从长江三峡工程对洞庭湖水文、水质以及湿地植被演替等方面综述了三峡工程对洞庭湖湿地的综合影响。三峡工程减缓了长江输入洞庭湖泥沙的淤积速率,对短期内增加洞庭湖区调蓄空间、延长洞庭湖寿命有利。总体上减少了洞庭湖上游的来水量,改变了洞庭湖原来的水位/量变化规律。给洞庭湖水环境质量造成了直接或间接的影响,对其水质改变尚存一定争议,但至少在局部地区加剧了污染。水位变化和泥沙淤积趋缓协同改变了洞庭湖湿地原有植被演替方式,改以慢速方式演替,即群落演替的主要模式为:水生植物—虉草或苔草—芦苇—木本植物。展望了今后的研究趋势与方向,为三峡工程与洞庭湖关系的进一步研究提供参考。     

三峡库区不同阶段蓄水前后江面江岸冬季鸟类动态

2003~2013年的隆冬季节(2011年除外),对三峡库区长江主河道的重庆朝天门港-秭归茅坪港江段(全程约618.30 km)和12条一级支流(合计调查河道长度约619.49 km),以及2个湖泊(长寿湖65.5 km~2,大洪湖30 km~2;调查年份2000~2013年,2003和2011年除外),进行了水禽及傍水栖息鸟类的监测调查。观察统计到鸟类76种,隶属8目14科39属,其中国家Ⅰ级重点保护野生动物1种,Ⅱ级重点保护野生动物3种。鉴于不同类群鸟类对环境变化的反应差别较大,将观察到的与水域生境密切相关的鸟类分为游禽类(32种)、鸥类(6种)、涉禽类(23种)、傍水栖息鸟类(13种)和空中傍水栖息鸟类[2种,以崖沙燕(Riparia riparia)为主体]等5种类型,并对各类群鸟类在三峡水库不同工程阶段蓄水高程前后的数量分布状况进行对比分析。结果显示,长江主河道中的游禽类在蓄水139 m高程前后数量波动幅度不大,蓄水156 m高程后表现出增长趋势,并且趋向于尾水点集中分布,直至最终蓄水目标175 m高程后的第5个冬季(2013年1月)数量猛增到最高,与蓄水139 m水位线前后的2个冬季(2003年1月和2004年1月)数量相比,增幅分别达171.83%和179.91%;然而2个湖泊中的游禽数值却表现出下降趋势,蓄水175 m高程后5个冬季(2008~2013年)与2000年冬季数值相比,降幅达52.96%~83.29%;大多数支流河道中的游禽数量呈现波动幅度不大或是明显下降趋势,只有乌江和小江这2条支流河道中的游禽数量呈现出增长趋势,并且小江中的游禽数量一度表现出"爆发式"增长现象后又大幅回落(2012~2013年),可能与水质富营养化程度的变化相关。涉禽类在长江主河道中的分布格局类似于游禽类(偏向于上游),其数量分别在蓄水139 m高程和156 m高程后的第1个冬季出现峰值,蓄水前后的其他年份数量差别不大;多数支流河道中涉禽类分布数量不高,只有嘉陵江、乌江、小江、大宁河与梅溪河的涉禽数量较多且数值波动明显。傍水栖息型鸟类总体数量在蓄水前后出现急剧变动,数量下降明显,个别鸟种甚至消失不见。空中傍水栖息型鸟类蓄水之后在长江主河道数量锐减,在大多数支流河道中几乎绝迹。鸥类主要分布在长江主河道,其数量在不同阶段蓄水初期出现峰值,至最终蓄水目标175 m后的第5个冬季其数量趋于接近蓄水之前。