Inshore spawning of cobia (Rachycentron canadum) in South Carolina

We documented inshore spawning of the recreationally important cobia (Rachycentron canadum) in Port Royal Sound (PRS) and St. Helena Sound (SHS), South Carolina, during the period from April to June in both 2007 and 2008. Histological analysis of ovaries confirmed the presence of actively spawning females inshore, and gonadosomatic index (GSI) values from females collected inshore (mean=7.8) were higher than the values from females caught offshore (mean=5.6); both of these mean values indicate that spawning occurred locally. Additionally, we conducted an ichthyoplankton survey in 2008 and found cobia eggs and larvae as far as 10 and 15 km inshore from the mouths of SHS and PRS, respectively. A study of egg development that we conducted in 2007 and 2008 using hatchery-reared cobia eggs provided descriptions of embryological development of cobia. Comparison of visual and quantitative characteristics of the field-collected eggs with those of the hatchery-reared eggs allowed positive identification of eggs collected in plankton samples. The ages of field-collected eggs and presence of females with hydrated oocytes in PRS and SHS observed in our ichthyoplankton survey and histological analysis indicated that wild cobia spawn in the afternoon and early evening. The inshore migration of cobia from April to June, the presence of actively spawning females, significantly higher GSI values, and the collection of eggs inside PRS and SHS all confirm that these estuaries provide spawning habitat for cobia. Because of the potential for heavy exploitation by recreational anglers as cobia move inshore to spawn in South Carolina, current management strategies may require review.

Measurement of stressful postures during daily activities: An observational study with older people.

This study measured the postures of older people during cooking and laundry. A sample of men and women aged 75+ years (n=27) was recruited and observed in a home-like environment. Postures were recorded with a measurement system in an objective and detailed manner. The participants were videotaped to be able to see where 'critical' postures occurred, as defined by a trunk inclination of ≥60°. Analysis of data was facilitated by specially developed software. Critical postures accounted for 3% of cooking and 10% of laundry, occurring primarily during retrieving from and putting in lower cabinets, the refrigerator, laundry basket or washing machine as well as disposing into the waste bin. These tasks involve a great variation in postural changes and pose a particular risk to older people. The results suggest that the use of stressful postures may decrease efficiency and increase fatigue, eventually leading to difficulties with daily activities. The specific tasks identified during which critical postures occurred should be targeted by designers in order to improve the activities. A few examples are given of how better design can reduce or eliminate some of the postural constraints.

Nonautonomous elementary net systems and their application to programmable logic control

In this paper, a novel approach to Petri net modeling of programmable logic controller (PLC) programs is presented. The modeling approach is a simple extension of elementary net systems, and a graphical design tool that supports the use of this modeling approach is provided. A key characteristic of the model is that the binary sensory inputs and binary actuation outputs of the PLC are explicitly represented. This leads to the following two improvements: outputs are unambiguous, and interaction patterns are more clearly represented in the graphical form. The use of this modeling approach produces programs that are simple, lightweight, and portable. The approach is demonstrated by applying it to the development of a control module for a MonTech Positioning Station. © 2008 IEEE.

分子标记技术在甘兰型杂交油菜育种上的研究与应用

本文应用RAPD分标记技术对我国重要的油料作物“杂油59”杂种种子的Fl代杂种的纯度进了技术鉴定，并完善了这一技术，摸索出这一适合于目前生产应用的实用方法，填补了这一技术在油菜作物应用上的空白。用RFLP技术对我国重要的雄性不育材料“陕2A”细胞质进行了分子水平的鉴定，为证明“陕2A”是一类新型的雄性不育材料提供了重要的实验证据。 对甘蓝型油菜采用DNA快速提取法、酚仿法和CTAB法应用于不同的分子标记分析，实验结果显示： CTAB法适用于样品量大，纯度要术高的RFLP技术，酚仿法适用于引物筛选、DNA模板用量大的PCR反应，而快速提取法特别适合于生产上对种子纯度检测，是生产上推广前景很好的实用技术。 对甘蓝型油菜RAPD技术应用当中PCR体系的建立进行了探讨。实验结果显示：热启动对PCR结果的影响至关重要。而Mg++浓度、dNTP浓度、模板浓度、Tag酶用量对反应结果有不同程度的影响。经过反复实验：当PCR各组分按Mg++，2mM;dNTP，200uM;模板浓度，50ng - lOOng时，PCR的结果最好。PCR反应条件经反复实验后确定为：第一个循环：（热启动）94℃，Imin20sec．OoC 2min循环一次;第二个循环：（解链）94℃ 50sec，（退火）40℃ Imin30sec;（延伸）72℃lmin;循环40次。第三个循环：72℃lOmin，循环1次。反应总体积为20ul时最为适用。 用40个lOmer的RAPD随机引物对“杂油59”的2个亲本“垦C8”和“陕3A” 进行RAPD分析，共出现290条带，分布于3530-220bp之间。引物opA-06、opK-03、opK-13、opj-12出现阳性扩增。经重复实验后确定： opK-03的PCR结果重复性最好，该引物序列为：CCAGCTTAGG。用它对两个亲本进行RAPD分析，PCR结果共出现9条带，其中510bp、260bp为二条特征带。在Fl代中这两条特征带重现性很好。用50个商品用种萌发的F1单株进行验证，检测结果为3个个体没有出现510bp的特征带，4个个体没有出现260bp的特征带，有5个个体出现了其它带，纯度为78%，与生产用种的纯度相符。 通过对“杂优59”不同生育时期及不同取样部位作酯酶同工酶电泳方法与RAPD方法相比较，结果显示：RAPD方法可以弥补同工酶方法的缺限。由于它是基于基因水平的分析技术，可以不受环境条件、发育时期、取材部位等客观条件的限制，并具有取样量小、易操作、费用低、灵敏度高、可以检测出亲缘关系相当近的种闾或种内的材料，具有独到的优点。是值得今后在生产上推广的新技术。 用6个雄性不育材料线粒体的特异探针：ALXR 18（线粒体ATPaseα亚基）;COB 640(脱辅基细胞色素-b);COX -I（细胞色素氧化酶亚基-I）;COX -Ⅱ（细胞色素氧化酶亚基-II;PDC - 12（胡萝卜线粒体随机片断）;C2（玉米线粒随机片断），对“陕2A”，Hybrides Polima，Ogura NSL 94/96, Ogura MLCH036, Ogura NSL, Polima, Fu27,Fu38, Anand等9个材料进行RFLP分析，结果显示：用限制性内切酶EcoR I消化后的DNA与探针COB 640杂交，“陕2A”材料在4.5 kb处缺失，与ALXR 18探针杂交，在4.4 kb、4.2 kb处也明显缺失，证明“陕2A”显然不同与其它不育材料。用ALXR l8为探针，与用内切酶Nc01的酶切片断作Sourthern杂交，在RFLP谱带上6.1 kb、2.4 kb、2.5 kb处明显缺带，进一步为“陕2A”是一种新型的甘蓝型油莱雄性不育系提供了证据。

低能N+诱导拟南芥突变体DNA变异的研究

低能离子束的诱变效应首先由我国科学家发现并将其广泛应用于育种实践，但是离子注入诱导DNA变异的研究结果主要是以微生物离体质粒DNA为材料获得的，以活体高等生物为材料的研究尚未见报道。 我们以30 keV N+（注入剂量80×1015 ions/cm2）注入拟南芥后获得的稳定突变体T80II为实验材料，对突变体植株进行了RAPD标记，并将T80II和对照部分RAPD特异条带进行克隆测序和DNA序列分析。结果显示，在可分辨的总计397个RAPD条带中，T80II株系中有52个条带表现出差异，包括条带的缺失和增加，条带变异率为13.1%;克隆的T80II序列中，平均每16.8个碱基出现一个碱基变异位点，表现出较高频率的碱基突变。碱基突变的类型包括碱基的颠换、转换、缺失、插入等。在检测到的275个碱基突变中，主要是单碱基置换（97.09%），碱基缺失或者插入的比例较小（2.91%）。在碱基置换中，转换的频率（66.55%）高于颠换的频率（(30.55%)。此外，构成DNA的四种碱基均可以被离子束辐照诱发变异，而且每一种碱基都可以被其它三种碱基所替换，但是胸腺嘧啶（T）的辐射敏感性要高于其它三种碱基。通过分析突变碱基周边序列，对低能N+离子注入拟南芥突变体引发的碱基突变热点进行了讨论。 另外，低能离子注入诱变获得的突变体特异表达基因的克隆方面也没有报道。我们以突变体T80II作为实验材料，用PCR增效的减法杂交技术构建了T80II特异表达的cDNA减法文库，克隆特异表达的cDNA片段，并对其中1个与14-3-3 protein GF14 nu (GRF7) gene有部分同源性、长712 bp的cDNA片段进行了讨论。我们的研究证明通过减法杂交技术克隆低能离子诱发的突变体特异表达的cDNA是可能的，这为低能离子注入技术在分子生物学上的应用开辟了一个新思路。

Severe decline in abundance of the red porgy (Pagrus pagrus) population off the southeastern United States

Status of the southeastern U.S. stock of red porgy (Pagrus pagrus) was estimated from fishery-dependent and fishery-independent data, 1972–97. Annual population numbers and fishing mortality rates at age were estimated from virtual population analysis (VPA) calibrated with fishery-independent data. For the VPA, a primary matrix of catch at age was based on age-length keys from fishery-independent samples; an alternate matrix was based on fishery-dependent keys. Additional estimates of stock status were obtained from a surplus-production model, also calibrated with fishery-independent indices of abundance. Results describe a dramatic increase in exploitation of this stock and concomitant decline in abundance. Estimated fully recruited fishing mortality rate (F) from the primary catch matrix increased from 0.10/yr in 1975 to 0.88/yr in 1997, and estimated static spawning potential ratio (SPR) declined from about 67% to about 18%. Estimated recruitment to age 1 declined from a peak of 3.0 million fish in 1973–74 to 94,000 fish in 1997, a decline of 96.9%. Estimated spawning-stock biomass declined from a peak of 3530 t in 1979 to 397 t in 1997, a decline of 88.8%. Results from the alternate catch matrix were similar. Retrospective patterns in the VPA suggest that the future estimates of this population decline will be severe, but may be less than present estimates. Long-term and marked declines in recruitment, spawning stock, and catch per unit of effort (both fishery-derived and fishery-independent)are consistent with severe overexploitation during a period of reduced recruitment. Although F prior to 1995 has generally been estimated at or below the current management criterion for overfishing (F equivalent to SPR=35%), the recent spawning-stock biomass is well below the biomass that could support maximum sustainable yield. Significant reductions in fishing mortality will be needed for rebuilding the southeastern U.S. stock.