Biology of Ixodes Rubicundus Ticks under Laboratory Conditions: Observations on Oviposition and Egg Development

Observations on oviposition and egg development of Ixodes rubicundus were made under laboratory conditions. Engorged females were exposed to temperatures in the range 10–25°C and relative humidities (RHs) of 33 and 93%. The pre-oviposition period, oviposition period, incubation period, conversion efficiency index (CEI) values and fecundity were determined. The mean pre-oviposition period varied from 13.3 days (temperature 25°C and RH 33%) to 68.3 days (temperature 10°C and RH 93%). Oviposition extended from a mean of 39 days (temperature 25°C and RH 93%) to 201.7 days (temperature 10°C and RH 93%). The developmental zero temperature for the pre-oviposition period was 9.2°C. The mean total number of eggs produced by engorged I. rubicundus females varied from 2045.7 (temperature 10°C and RH 93%) to 3777.7 (temperature 20°C and RH 93%). Both female mass and RH significantly (p < 0.01) influenced the number of eggs produced. CEI values varied between 43.1–54.4% (RH 93%) and 34.1–42.5% (RH 33%). At 93% RH females produced between 14.2 and 17.7 eggs per mg body mass compared to the 13.2–14.6 eggs per mg body mass at 33% RH. The shortest mean incubation period recorded was 164.3 days (temperature 25°C and RH 93%). The developmental zero temperature for incubation was 6.5°C. Both the pre-oviposition and oviposition periods of I. rubicundus are more extended compared to other species of the genus. Ixodes rubicundus produces a large number of small eggs compared to other prostriate ticks.     

The performance of field sampling for parasite detection in a wild passerine

Parasites can impact the behavior of animals and alter the interplay with ecological factors in their environment. Studying the effects that parasites have on animals thus requires accurate estimates of infections in individuals. However, quantifying parasites can be challenging due to several factors. Laboratory techniques, physiological fluctuations, methodological constraints, and environmental influences can introduce measurement errors, in particular when screening individuals in the wild. These issues are pervasive in ecological studies where it is common to sample study subjects only once. Such factors should be carefully considered when choosing a sampling strategy, yet presently there is little guidance covering the major sources of error. In this study, we estimate the reliability and sensitivity of different sampling practices at detecting two internal parasites—Serratospiculoides amaculata and Isospora sp.—in a model organism, the great tit Parus major. We combine field and captive sampling to assess whether individual parasite infection status and load can be estimated from single field samples, using different laboratory techniques—McMaster and mini‐FLOTAC. We test whether they vary in their performance, and quantify how sample processing affects parasite detection rates. We found that single field samples had elevated rates of false negatives. By contrast, samples collected from captivity over 24 h were highly reliable (few false negatives) and accurate (repeatable in the intensity of infection). In terms of methods, we found that the McMaster technique provided more repeatable estimates than the mini‐FLOTAC for S. amaculata eggs, and both techniques were largely equally suitable for Isospora oocysts. Our study shows that field samples are likely to be unreliable in accurately detecting the presence of parasites and, in particular, for estimating parasite loads in songbirds. We highlight important considerations for those designing host–parasite studies in captive or wild systems giving guidance that can help select suitable methods, minimize biases, and acknowledge possible limitations.     

Action mechanism of PEGylated magainin 2 analogue peptide

PEGylation is frequently used to improve the efficacy of protein and peptide drugs. Recently, we investigated its effects on the action mechanism of the cyclic β-sheet antimicrobial peptide tachyplesin I isolated from Tachypleus tridentatus [Y. Imura, M. Nishida, Y. Ogawa, Y. Takakura, K. Matsuzaki, Action Mechanism of Tachyplesin I and Effects of PEGylation, Biochim. Biophys. Acta 1768 (2007) 1160-1169]. PEGylation did not change the basic mechanism behind the membrane-permeabilizing effect of the peptide on liposomes, however, it decreased the antimicrobial activity and cytotoxicity. To obtain further information on the effects of PEGylation on the activities of antimicrobial peptides, we designed another structurally different PEGylated antimicrobial peptide (PEG-F5W, E19Q-magainin 2-amide) based on the α-helical peptide magainin 2 isolated from the African clawed frog Xenopus laevis. The PEGylated peptide induced the leakage of calcein from egg yolk l-α-phosphatidylglycerol/egg yolk l-α-phosphatidylcholine large unilamellar vesicles, however, the activity was weaker than that of the control peptides. The PEGylated peptide induced lipid flip-flop coupled to the leakage and was translocated into the inner leaflet of the bilayer, indicating that PEGylation did not alter the basic mechanism of membrane permeabilization of the parent peptide. The cytotoxicity of the non-PEGylated peptides was nullified by PEGylation. At the same time, the antimicrobial activity was weakened only by 4 fold. The effects of PEGylation on the activity of magainin were compared with those for tachyplesin.     

温度和食物浓度对萼花臂尾轮虫休眠卵形成的影响

应用群体累积培养法,在3种温度(20℃、25℃和30℃)和3种斜生栅藻浓度(6.0×106cells/mL、3.0×106cells/mL和1.5×106cells/mL)共9个条件组合下对萼花臂尾轮虫休眠卵形成的研究表明,温度为20℃和食物浓度为6.0×106cells/mL的条件组合下轮虫休眠卵的产量和形成效率最大,此为轮虫休眠卵规模化生产的最适条件;6.0×106cells/mL和3.0×106cells/mL的食物浓度分别是25℃和30℃下轮虫休眠卵生产的最适食物浓度.20℃时轮虫的混交雌体百分率显著大于25℃和30℃时,而温度和食物浓度以及两者间的交互作用均对混交雌体受精率无显著的影响.     

菱斑巧瓢虫替代饲料的研究

瓢虫成虫饥饿24h后,通过室内对菱斑巧瓢虫Oenopia conglobata (Linnaeus)成虫饲喂24种人工饲料,研究菱斑巧瓢虫的取食行为;以桃蚜(MP)作对照,选择羊肝+蔗糖(SLS)、猪肝+蔗糖(PLS)、黄粉虫蛹+蔗糖(TMPS)3种饲料研究瓢虫产卵量;以白蛾周氏啮小蜂蛹(CCP)、SLS、PLS和MP对瓢虫成虫进行交叉饲喂试验,每周期7d,研究饥饿后恢复产卵时间和产卵量的差异;最后以CCP和MP饲喂瓢虫幼虫,观察其发育历期。结果表明:在羊肝、鸡心、菜蛾幼虫、鸡肝和黄粉虫蛹组中,无论是否添加蔗糖,瓢虫取食情况较好。瓢虫成虫饲喂SLS、TMPS、PLS及MP后,MP组的14d单雌产卵量为166.25粒、SLS组为18.15粒、PLS为9.65粒和TMPS组3.90粒,瓢虫恢复产卵的时间也有差异,MP组仅需要1d,而其它组需要3d至至5d。交叉饲喂试验发现,CCP组产卵量(40.67～46.87粒/雌)明显高于常用饲料-PLS组(4.53～7.13粒/雌),但与MP组(61.80～82.07粒/雌)仍有一定差距。利用CCP饲喂瓢虫幼虫,可以完成整个发育历期,但是存活率较低,1～4龄幼虫各龄期内存活率在63.64%～87.50%之间,并且发育历期(21.23d)明显长于饲喂MP组(15.71d)。     

合浦珠母贝的配子发生

本文研究了合浦珠母贝精子和卵子的发生过程,详细描述了原始生殖细胞,精原细胞,卵原细胞,精母细胞,卵母细胞以及精子和卵子的形态结构;另外还报道了合浦珠母贝中独特的精、卵退化现象,并讨论了它们对合浦珠母贝人工育苗生产的影响。     

仿野生鳖卵的磷脂及粗蛋白含量测定

仿野生鳖卵内容物冻干粉收率为 30 .6 1% ,它的粗蛋白质及磷脂含量分别为 5 0 .0 1%和 12 .74 %。TLC分析结果表明仿野生鳖卵含有 5种磷脂成份 ,而鹌鹑卵及猪脑仅含有 3种磷脂     

四川省赫坎按蚊种团各蚊种卵形态鉴别的可靠性研究

本文论证用蚊卵形态鉴别四川省赫坎按蚊种团各蚊种的可靠性。中华按蚊同嗜人按蚊、筠连接蚊、八代按蚊、贵阳按蚊,凉山按蚊同嗜人按蚊等,用卵形态鉴别比较可靠;其余各蚊种之间卵形态鉴别不完全可靠,必须结合蚊虫生活史中其他阶段的形态进行鉴别;卵甲板定同卵宽、甲板定同浮囊内缘间距离、浮囊内缘至甲板边缘距离同甲板宽等的比值,以及甲板的形状等卵外部形态,在赫坎按蚊种团各蚊种之间的鉴别上占有比较重要的地位。     

中华绒螯蟹成熟卵形态和超微结构的研究

中华绒螯蟹的成熟卵仅有初级卵膜，无次级和三级卵巢，质膜初期厚而多层，且具皱褶，卵核在卵的发育过程中变化很大，未发见中心粒，内质网和高尔基体均始见于蟹卵发育的初期，皮层颗粒先出现于蟹卵深部，随后移到卵的表层，无滋养细胞，蟹卵由卵泡细胞提供物质，形成卵黄，此外，还可直接从血淋巴内摄取卵黄前身物质。