In vitro secretion of ecdysteroids by Y-organs of the crayfish,Procambarus clarkii

It was demonstrated that excised Y-organs of the crayfish,Procambarus clarkii, synthesize in vitro 3-dehydroecdysone (3-DHE) as the major product, together with small amounts of ecdysone. Both were identified by immunological and spectroscopic methods. The increase of ecdysteroidogenesis in the Y-organs was accompanied by an increase of the major free ecdysteroid, 20-hydroxyecdysone, in the hemolymph. This suggests a physiological role of 3-DHE, the details of which are still to be elucidated.     

Two new species of Xironogiton (Clitellata: Branchiobdellida) from western North America

Xironogiton, a genus of crayfish worm (order Branchiobdellida), is historically endemic to North America. To date, six species of Xironogiton have been described, including five and one from areas west and east of the Continental Divide, respectively. Recent collections of the crayfishes Pacifastacus connectens and Pacifastacus leniusculus from the endorheic Harney Basin in south-eastern Oregon, USA, revealed the presence of two previously unknown Xironogiton species, which we describe herein. Discovery and characterisation of Xironogiton bibendumi sp. nov. and Xironogiton malheurensis sp. nov. suggests that much work remains to understand branchiobdellidan diversity in western North America, and additional targeted sampling is needed to determine intra- and interspecific variation, and thus define species limits.http://www.zoobank.org/urn:lsid:zoobank.org:pub:B24AA844-4A73-48F2-B269-7CD08DC8389A http://www.zoobank.org/urn:lsid:zoobank.org:pub:F1787846-BF04-44A6-949B-551EE3453F26     

红螯螯虾的摄食行为及饵料选择性

对红螯螯虾的摄食行为进行了观察,并比较了红螯螯虾对几种饵料的选择性。结果表明,红螯螯虾的摄食过程可分为寻食、取食和清洗3个阶段。对单只红螯螯虾的摄食行为观察结果显示,投喂鱼肉、玉米、胡萝卜和配合饲料4种饵料时,红螯螯虾首次选择的饲料比率最高的为鱼肉,其次为玉米、胡萝卜,未选择配合饲料。对每次1 h的摄食过程的分析结果表明,红螯螯虾对玉米的摄食次数最多,且摄食时间最长,其次为鱼肉、胡萝卜,最后为配合饲料。小群体摄食观察结果表明,红螯螯虾会通过打斗获取优先摄食的机会,当每只红螯螯虾有机会同时摄取食物而不相遇时,未发现红螯螯虾因摄食而出现打斗行为。体重90 g左右的红螯螯虾对玉米颗粒粒径的偏好性强弱依次为2.5 mm、5 mm、1.5 mm和10 mm。投喂浸泡处理过的玉米,红螯螯虾的摄食速度提高。在鱼肉、玉米、胡萝卜和配合饲料4种饵料中,当同时投喂2种等量的饵料时,红螯螯虾对鱼肉的摄食速度最快,其次是玉米和配合饲料,对胡萝卜的摄食速度最慢。研究结果提示:在研制专用配合饲料时,必须考虑诱食性物质;在养殖过程中,可在饲料中添加诱食剂,以便红螯螯虾能尽快发现饲料,促进摄食;在喂养时,饵料宜分散投放。     

The site of synthesis of hemocyanin in the crayfish,Astacus leptodactylus

Summary The in vitro incorporation of³⁵S-methionine into hemocyanin was tested in the crayfish,Astacus leptodactylus. All organs assayed (hemocytes, heart, hypodermis, midgut gland, muscle and stomach) were able to synthesize proteins under our experimental conditions, but only midgut gland (=hepatopancreas) incorporated labeled methionine into a protein which was precipitated by an antibody againstAstacus hemocyanin, and which comigrated with authentic hemocyanin on SDS gels.     

Estimating the young evolutionary age of marbled crayfish from museum samples

ABSTRACT

The obligately parthenogenetic, all-female marbled crayfish, Procambarus virginalis, is a triploid descendant of the similarly looking, sexually reproducing slough crayfish, Procambarus fallax, native to Florida and southern Georgia. We have earlier hypothesised that marbled crayfish may have originated from P. fallax only some 25 years ago, perhaps in captivity. In order to investigate the young evolutionary age hypothesis in more detail, I searched the P. fallax collection of the Smithsonian Institution Museum of Natural History (USNM, Washington, D.C.) for evidence of marbled crayfish before its detection in the German aquarium trade in 1995. In particular, I analysed the sex ratio of P. fallax and the frequency of pure female samples throughout its entire distribution range to detect potentially misidentified marbled crayfish among the P. fallax. If marbled crayfish had originated from P. fallax long ago, spread throughout Florida and Georgia and erroneously been sampled as P. fallax, then the sex ratio of the P. fallax in the collection should be significantly biased towards females and pure female samples should be much more frequent than in related Procambarus species. Comparison of P. fallax (n = 2299) with its closest relatives P. seminolae (n = 801) and P. leonensis (n = 150) revealed female proportions of 55.33%, 53.93% and 54.67%, respectively, which are not significantly different from each other. The average female proportion of the 14 Procambarus species investigated (8641 specimens) was 52.54 ± 7.54% (mean ± standard deviation). Moreover, pure female samples consisting of more than 3 specimens that could represent hidden marbled crayfish were not conspicuously more common in P. fallax (2.33%) than in all Procambarus species investigated (1.24 ± 1.79%). These data suggest that the P. fallax collection of the USNM consists of real, sexually reproducing P. fallax and does most likely not include hidden marbled crayfish, supporting the young evolutionary age hypothesis for marbled crayfish.     

基于机器视觉的小龙虾分级算法设计

小龙虾是中国重要经济水产,其价格随产品等级波动较大。传统的分级技术对小龙虾销售有一定限制,发展分级技术对于提高小龙虾经济价值有重要意义。根据小龙虾销售规范的要求,设计了小龙虾分级算法,分别利用R分量占比统计法、椭圆近似法、椭圆切割法对虾体生命状态、尺寸及残缺度进行检测。实验结果显示,在100个随机检测样品中,算法误判率约3%。相较传统分级方式,该算法不仅具有效率优势,同时具有相对低的误判率。     

Cambarus loughmani,a new species of crayfish (Decapoda: Cambaridae) endemic to the pre-glacial Teays River Valley in West Virginia,USA

ABSTRACT

A new species of crayfish, Cambarus loughmani sp. nov., is described from the preglacial Teays River Valley of Cabell, Kanawha, Lincoln, Mason, and Putnam counties, West Virginia. The species was previously considered to be part of the Cambarus dubius complex. Loughman et al. restricted C. dubius to an orange colour morph found in central and northern portions of the Allegheny Mountains and Appalachian Plateau in central West Virginia, western Maryland, and south-central Pennsylvania. The new species described herein can be distinguished from all other members of Cambarus Erichson, 1846 by a double row of cristiform tubercles on the palm, an open areola with two rows of punctations, and a consistent blue colouration.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:5BC7C861-038E-457C-80F3-ED7A66E10D73     

Hg^2＋,Pb^2＋对克氏螯虾触角神经放电联合作用研究

本实验应用多通道电生理记录方法，观察Ｈｇ＾２＋和Ｐｂ＾２＋对克氏螯虾第一触角内侧枝神经放电的联合作用。结果显示，从表示其放电频率（Ｆｎ／Ｆ１）与作用时间关系的直线回归方程的ｂ值可知，水中Ｈｇ＾２＋的浓工只有其渔业水体最高允许量（０．０００１ｍｇ／Ｌ）的１／２，水中若还含有浓度≥０．０１２５ｍｇ／Ｌ的Ｐｂ＾２＋，或水中Ｐｂ＾２＋的浓度只有其渔业水体最高允许量（０．１ｍｇ／Ｌ）的１／２，水中若还含有浓     

克氏原螯虾受精卵结构观察

观察了克氏原螯虾受精卵的结构.取固定好的克氏原螯虾受精卵进行冷冻切片,苏木精-伊红染色,镜检,拍照.结果表明,克氏原螯虾受精卵属于中黄卵,细胞质被排挤到受精卵一侧,位于受精卵表面.受精卵有致密的中心区,由此向周围发散出呈指状突起的卵黄柱,卵黄柱内充满大小不等的卵黄颗粒.克氏原螯虾受精卵的结构可以通过冷冻切片观察.     

A survey of 3-dehydroretinal as a visual pigment chromophore in various species of crayfish and other freshwater crustaceans

Summary 3-Dehydroretinal (vitamin A₂ aldehyde) was found in the eyes of three species among 10 species of freshwater crayfish examined. Since dark-adapted eyes contained the 11-cis form of 3-dehydroretinal, this compound must be the chromophore of the visual pigment. 3-Dehydroretinal always coexisted with retinal (vitamin A₁ aldehyde), indicating the presence of a rhodopsin-porphyropsin visual pigment system.