Ecological intensification for feeding rohu Labeo rohita (Hamilton, 1822): A review and proposed steps towards an efficient resource fishery

Labeo rohita (rohu) is a commercially popular Indian major carp species in polyculture fish farming system. It feeds mainly on plankton. The adults of rohu have a strong positive selection for phytoplankton, whereas the fingerlings have a strong positive selection for both zooplanktonic and smaller phytoplanktonic sources. Conversely, adults of rohu exhibit a strong negative selection for all zooplanktonic sources and a positive selection for most phytoplanktonic sources. In periphytic environments, the fish grow better feeding on the sub‐periphytic zone in proximity to the substrate. We conclude that rohu is an excellent aquaculture candidate, thanks to its ability to explore natural resources (plankton and periphyton) and transform them to fish biomass in polyculture practice. In contrast to over‐reliance on artificial feed, translation of natural resources for exploration by rohu could be the next step for sustainable carp‐based polyculture practice.     

帆张网网囊网目尺寸对小黄鱼的选择性

为探索帆张网不同网目尺寸网囊对小黄鱼的选择性,2017年4月在舟山渔场中部用传统方法(套网法)对5种不同网目尺寸(35 mm、45 mm、55 mm、60 mm、65 mm)网囊开展了选择性实验。应用Logistic模型对小黄鱼选择性曲线进行拟合,采用极大似然法估算模型参数。结果显示:①实验期间主要捕获对象为小黄鱼,数量和重量分别占比66.94%和84.48%,体长范围71～190 mm,平均体长124 mm;②随着网目尺寸的增加,网囊中小黄鱼优势体长总体上大于套网;③网囊网目尺寸为35 mm、45 mm、55 mm、60 mm和65 mm时,小黄鱼L50分别为80.425 mm、103.496 mm、119.711 mm、122.676 mm和137.026 mm,SR分别为50.202 mm、52.540 mm、61.120 mm、41.730 mm和63.560 mm,L50呈现逐渐增大的趋势;④小黄鱼网囊网目尺寸(m)与50%选择体长(L50)的关系为L50=1.776 m+20.300 (R2=0.980);⑤5种网目尺寸网囊中小黄鱼尾数逃逸率均高于重量逃逸率,网囊网目尺寸≤45 mm时,其尾数及重量逃逸率均低于5%,网囊网目尺寸≥55 mm时,其尾数及重量逃逸率均超过10%,甚至可达50%。综合分析,目前实施的55 mm网目尺寸能有效释放小黄鱼幼鱼,但网目尺寸仍需扩大。     

传播学视角下选择性理论对高校思想政治教育工作的启示

高校思想政治教育工作可以视为一种传播活动,即思想政治教育信息在教育者和大学生之间的传递和接受。将传播学选择性理论研究同高校思想政治教育实践联系起来,探索高校思想政治教育工作新思路和新方法。通过大量的理论研究和实证分析,认为深入有效的了解和沟通、尊重个性差异的因材施教、易得易懂易记的信息传播、妥帖有效的方法技巧,是提高思...     

生态经济区建设分析

对现有生态经济区理论和实践的梳理,认为促使生态经济区建设的充分、必然条件是自然的可能性、经济的可行性、政策的可容性和民众的选择性。现实中,自然的可能性和政策的可容性是生态经济区建设的主要驱动力;而经济发展和民众需求不充分是生态经济区建设的限制性因素。环境外部性强与生态环境脆弱、处在重要经济区内与自身经济发展水平低、政策约束性强与政策可操作性弱、城乡二元性与民众需求不一致是四个因素中的主要矛盾方面。矛盾的根源在于选择的经济发展模式与当地所处的生产力发展阶段不相适应。破解矛盾的主要办法是加快发展生产力,而加快发展的必要条件是有重要经济区支持。     

夏季东海区带鱼的网具选择性试验研究

由于渔业高强度捕捞压力及频繁的海洋工程导致近海海洋环境恶化,东海带鱼（Trichiurus haumela）资源量发生了严重衰退。为可持续利用东海带鱼资源,于2014年夏季8月在东海区渔场采用底拖网菱形目50、55、60、65、70、75 mm和80 mm对带鱼的逃逸率网具选择性进行试验研究,采用套网法对不同尺寸的囊网网目的选择性进行了分析比较。结果表明：带鱼渔获物肛长范围为55～283 mm,平均肛长为159 mm,优势肛长组为140～190 mm,囊网中带鱼渔获的主要肛长组分布在140～220 mm,在套网中主要肛长分布在130～190 mm;随着网目由小变大,囊网中带鱼的平均肛长、体质量也逐渐变大;在数量和体质量逃逸率方面,随着网目增大整体呈先降低后上升的趋势;由于其他非目标渔获和带鱼体型容易挂网的特点,造成囊网中渔获积累产生的堵塞效应,严重影响相关网目中带鱼的逃逸率;根据带鱼的50%选择体长（L_0.5）与不同网目尺寸拟合的直线：L_0.5=2.241 9M+17.503（r=0.930）。以此利用推测的拟合线性关系,并参考相关文献得出的带鱼雌雄个体的L_0.5标准反向推出,捕捞雌性带鱼L_0.5的最小网目尺寸为65.63 mm,雄性带鱼L_0.5的最小网目尺寸为68.76 mm。运用现行可捕标准以及渔业生产,故建议专门用于捕捞带鱼的拖网网目尺寸至少为65mm。同时研究表明海水温度变化对带鱼的体质量资源密度与尾数资源密度的分布有一定影响,其为影响渔具选择性的重要自然因素之一。     

美洲斑潜蝇对豆科与葫芦科主要蔬菜品种(系)的选择性研究

在实验室条件下,以取食痕／ｃｍ＾２,着卵数／ｃｍ＾２等指标,采用自由选择法与非自由选择法了美洲斑潜蝇对菜豆属,豇豆属,甜瓜属,丝瓜属,苦瓜属,葫芦属中１６个蔬菜品种（系）的选择性差异,结果表明美洲斑潜蝇对黄瓜津杂４号,菜豆特长架豆,豇豆之豇２８－２品种的取食、产卵选择性较差,表现为非嗜好;而对黄瓜津春４号,菜豆玉豆３５、豇豆无架豆的取食产卵选择性较强,表现为嗜好性;对不同属植物的选择从以弱依次为菜     

Study of Structure–Activity Relationships of the Marine Alkaloid Fascaplysin and Its Derivatives as Potent Anticancer Agents

Marine alkaloid fascaplysin and its derivatives are known to exhibit promising anticancer properties in vitro and in vivo. However, toxicity of these molecules to non-cancer cells was identified as a main limitation for their clinical use. Here, for the very first time, we synthesized a library of fascaplysin derivatives covering all possible substituent introduction sites, i.e., cycles A, C and E of the 12H-pyrido[1-2-a:3,4-b’]diindole system. Their selectivity towards human prostate cancer versus non-cancer cells, as well as the effects on cellular metabolism, membrane integrity, cell cycle progression, apoptosis induction and their ability to intercalate into DNA were investigated. A pronounced selectivity for cancer cells was observed for the family of di- and trisubstituted halogen derivatives (modification of cycles A and E), while a modification of cycle C resulted in a stronger activity in therapy-resistant PC-3 cells. Among others, 3,10-dibromofascaplysin exhibited the highest selectivity, presumably due to the cytostatic effects executed via the targeting of cellular metabolism. Moreover, an introduction of radical substituents at C-9, C-10 or C-10 plus C-3 resulted in a notable reduction in DNA intercalating activity and improved selectivity. Taken together, our research contributes to understanding the structure–activity relationships of fascaplysin alkaloids and defines further directions of the structural optimization.     

有机物离子选择性电极对季铵的选择性规律

Electrode selectivities toward quaternary ammoniums are controlled by the ability of the cation to be extracted into the membrane phase. We has proved in this paper theoretically that logK_(ij) can be expressed as function of alkyl chain length of quatern     

不同种松树对松树蜂毒素抗性的初步研究

松树蜂(Sirex noctilio Fabricius)是一种重要的国际检疫性蛀干害虫。目前在我国松树蜂潜在寄主范围内,不同树种对松树蜂毒素抗性之间的差异尚不明确。本文以室内栽培的2~3 a生油松、樟子松、红松、湿地松、马尾松及雪松这6种树种为供试寄主,培育3个月后分别接种毒素、毒素真菌混合液并测定每株枝条针叶的RGB值以及叶绿素含量。结果表明,形态上油松和樟子松幼苗接种毒素、毒素真菌混合液后一段时间内,均出现了比较明显的针叶枯黄、脱落的现象,且混合组长势萎蔫,脱落严重,对照组无明显变化。马尾松幼苗只有接种混合液后变化明显,雪松、红松、湿地松接种后长势强劲,长出新芽。从数值化的角度,油松和樟子松幼苗接种毒素、毒素和真菌混合液后,针叶的RGB值减小及叶绿素含量值显著降低。马尾松幼苗只有接种混合液后,RGB值和叶绿素含量才减小。雪松、红松、湿地松接种毒素以及毒素真菌混合液后,RGB值及叶绿素含量均没有明显变化。以上可以看出樟子松和油松对于松树蜂毒素、毒素真菌混合液的抗性较弱,马尾松对松树蜂毒素具有一定的抗性,对毒素真菌混合液的抗性较弱,红松、湿地松、雪松对两者都具有一定的抗性。该结果可为明确松树蜂在我国潜在的寄主范围及寄主选择性提供科学依据。     

Gillnet Selectivity and Length at Maturity of Nile Tilapia （Oreochromis niloticus L.） in a Tropical Reservoir （Amerti： Ethiopia）

The selectivity of gillnets for Oreochromis niloticus in Amerti reservoir （9°63′ N, 37°23′ E） was determined from gillnets with four mesh sizes （60, 80, 100 and 120 mm）. Four selectivity models （a normal model assuming fixed spread, a normal model assuming that spread is proportional to mesh size, a lognormal model and a gamma model） were fitted to the data by using the share each length＇s catch total （SELECT） method. A total of 657 specimens of Oreochromis niloticus were caught （12.0-35.5 cm total length, TD. The sizes at first sexual maturity were 21.5 cm TL and 18.9 cm TL, respectively, for male and female Oreochromis niloticus. The lognormal selectivity curve provided the best fit to the data according to model deviance estimates with optimum selectivity of 16.66, 22.26, 27.78 and 33.38 cm TL for the 60, 80, 100 and 120 mm mesh sizes, respectively.