High mortality of embryos of a distinct autochthonous Austrian coregonid population during Zuger jar incubation

For a distinct autochthonous Austrian coregonid population called Reinanke Coregonus sp., embryo viability was very low in Zuger jars (mean ± s.d. 36·1 ± 16·1% eyed stage embryos in experiment 1, 15·1 ± 17·0% in experiment 2) but high in vertical flow incubators (63·3 ± 29·0% eyed stage embryos in experiment 1, 57·8 ± 18·9% in experiment 2). Mechanical shock sensitivity is a possible explanation for high embryo mortality.     

Diapause Induction and Termination in Eggs of the Fruit Tree Red Spider Mite Panonychus Ulmi in Northern Greece

In apple orchards in northern Greece, females of Panonychus ulmi Koch were found to lay diapause eggs from late August to the beginning of October. The course of diapause termination in the field was determined by transferring diapause eggs during winter and early spring from apple orchards with the varieties Starkinson and Firiki to short days (LD 8:16) (1992–1996), and long days (LD 16:8) (1994–1995), both at 20 °C. Percentages of diapause termination were very low to zero from October to the beginning of January, then progressively increased throughout January and February. Diapause termination in 50% of the eggs occurred in the first half of February in lowland mite populations irrespective of the year and location from which the eggs originated, and about one month earlier in a population originating from an altitude of 300 m. For each sampling date throughout the winter, the mean number of days required for 50% egg hatch at 20 °C (T_50%) was similar under either a long (LD 16:8) or a short (LD 8:16) photoperiod. Diapause eggs collected in October 1995 from two orchards and maintained at 0, 5, 10 and 15 °C for various periods were subsequently transferred to 20 °C and LD 8:16, where TP_50% was determined. It was shown that temperature, duration of maintenance at the different temperatures and the orchard from which the eggs originated had a significant effect on T_50% and therefore on diapause development. Additionally, in our strains diapause intensity was much weaker than in strains from more northern latitudes and was terminated even without any cold exposure. The variation in diapause intensity in different strains of P. ulmi may have an adaptive significance for this widespread species.     

小鼠受精卵微注射Cdc25b mRNA可提高卵裂率并促进受精卵发育

为了观察Cdc25B蛋白及PKA/Cdc25B 信号途径在小鼠受精卵发育中的作用,将突变型和野生型Cdc25b转录成 mRNA,显微注射到小鼠受精卵中,放入含有或不含有dbcAMP的M16中,相差显微镜下观察受精卵卵裂情况;用蛋白激酶活性测定方法检测MPF的活性;利用Western 印迹检测Cdc2-Tyr15的磷酸化状态.结果显示,未加dbcAMP的Cdc25b- S321A mRNA注射组与Cdc25b-WT组相比,能够提前使受精卵发生G ₂/M期转变,导致卵裂,并明显提高卵裂率;MPF的活性测定和Cdc2-Tyr15磷酸化状态的检测结果也显示,Cdc25b-S321A组先于Cdc25b-WT组提前激活MPF.此外, Cdc25b-S321A mRNA注射组可以有效恢复由PKA引起的受精卵G ₂期阻滞,显著增加卵裂率;MPF的活性测定和Cdc2-Tyr15磷酸化状态的检测结果也显示,在PKA持续激活的情况下,对比于Cdc25b-WT组,Cdc25b-S321A组提前激活MPF.因此,在小鼠受精卵发育过程中PKA主要通过磷酸化Cdc25B的321位丝氨酸,从而调控MPF的激活与失活来控制有丝分裂进程.     

湖北安陆新的恐龙蛋类型的发现及其意义

本文记述的恐龙蛋化石标本,采自湖北省江汉盆地公安寨组下部.蛋化石保存完好.在普通光学显微镜和扫描电镜下观察,蛋壳的显微结构完整,清晰可见.根据钙质蛋壳基本结构单位的形态及排列特征,笔者建立了—新属,新种——Dendroolithus wangdianensis gen. et sp. nov.,代表恐龙蛋类一个新科——Dendroolithidae fam. nov.此外,残存的卵壳膜纤维化石的发现,将为进一步研究恐龙蛋卵壳膜的结构和氨基酸组成提供宝贵材料.     

水淹对钉螺卵影响的透射电镜观察

春汛期钉螺繁殖期在洞庭湖现场进行水淹螺卵试验，观察螺卵结构的动态变化。结果显示，对照组螺卵胶膜由胶原纤维层和基底膜组成，卵细胞核大，呈圆形或椭圆形，染色质丰富，细胞内含丰富线粒体、内质网和分泌颗粒等。水淹１０ｄ时，结构尚未见明显变化；至２０ｄ时，胶膜胶原纤维横纹不清，断裂有空洞，线粒体肿胀，嵴结构不清，核内染色质减少；３０ｄ时，出现核固缩或崩解，线粒体消失。说明在螺卵发育期水淹能很快使其发生病理损     

黑水虻卵胚胎发育过程及在生产上的应用

黑水虻作为近年来广受关注的资源昆虫,其规模化应用的基础理论研究成为热点。本文对其胚胎发育过程进行研究,利用显微镜对资源昆虫黑水虻卵孵化发育过程进行观察并拍照,对胚胎各个时期的发育时间和形态进行记录。试验发现,在32℃下,黑水虻卵的发育历期为51 h。黑水虻的胚胎发育经过卵裂期、胚盘胚带形成期、原肠形成期、胚体分节期、体壁形成期、器官形成期6个典型时期。试验对孵化过程中的15个具体发育时期的特征和发育时间进行记录,形成了一套虫卵镜检技术应用于实际生产。在生产上,通过镜检技术对每一批次待孵化虫卵进行镜检观察,可初步判定该批次待孵化虫卵所处的发育阶段和死亡率,预估虫卵孵化时间和孵化率,为规模化稳定培育黑水虻苗种提供理论依据。     

新疆石河子棉蚜越冬卵的发育规律

棉蚜雌性蚜交配个体平均产卵量为 6 3± 1 1粒 ;未交配个体也产卵 ,卵亦变色 ,但卵量极少。越冬卵经 5 %NaOH浸泡 2 4h后卵壳透明 ,镜下观察可见受精卵胚胎发育到体躯分节期开始越冬。冬后胚胎发育仅处在颗粒团状的饱满卵应为无效卵 ,不会孵化 ;颜色发亮的卵处理后胚胎外貌清晰可见 ,此种卵当天即可破壳。棉蚜卵为滞育卵 ,春季降水对孵化有促进作用 ;室外棉蚜卵的饱满率和饱满卵的孵化率较低。该地区秋冬气候特点可能是石河子地区棉蚜卵低温条件下安全越冬的重要因素     

Oceanic transport of calcified eggs: taphonomic and biogeographic implications

Estimates of the temporal and spatial resolution of fossil egg assemblages are required to constrain the inferences that can logically be drawn during assemblage analysis. Consequently, understanding egg transport mechanisms is required before conclusions are developed. Bird eggs are buoyant during part of development and can float from near shore nests during high tides, storm surges, or flooding. Complete and unbroken eggs have survived transoceanic transport. Evidence of these transport processes operating in the past is suggested by the recovery of fossil eggshell in marine deposits. Transport of eggs can potentially confound fossil assemblage spatial analysis since evidence of oceanic transport may not be present on an eggshell when collected. Bird embryos exposed to cold temperatures and immersed in both fresh and salt water can survive from hours to two days, suggesting that oceanic transport of viable eggs is possible, a conclusion further supported by field observations. Eggs of other taxa show similar environmental survival trends and may also be capable of surviving oceanic transport through floatation or rafting. In addition, if viable eggs are transported across seas and hatch, emigration or gene flow of terrestrial egg-laying vertebrates may be possible between landmasses.     

Ecdysteroids in females and eggs of the Ixodid tick Amblyomma hebraeum

Summary

A mated Amblyomma hebraeum female will engorge on a host for about 8 days before detaching and beginning the maturation of its single egg batch which is laid during a period of about 30 days. The feeding period is characterized by an important synthesis of endocuticular material occurring before the rapid feeding phase. This latter phase, correlated with an enormous weight uptake, shows an increase of ecdysteroid levels measured in the whole animal by RIA. However, the hemolymphatic levels of ecdysteroids remain very low (12 pg 20-hydroxyecdysone equivalent (20-OH-E eq.) per μ1. Within 4 days after detachment, the salivary glands degenerate. Ecdysteroid levels in the whole animal continue to increase, reaching high values (about 500 ng 20-OH-E eq./tick) at the moment of oviposition which begins 10–14 days after dropping. During the same period, hemolymphatic ecdysteroid levels increase, rising to a peak (600 pg 20-OH-E eq./μ1) 1 day prior to the beginning of oviposition. Then, the levels decrease and stabilize around 250 pg 20-OH-E eq./μl during egg-laying. Freshly laid eggs contain large amounts of ecdysteroids (2744 pg 20-OH-E eq./mg).

20-Hydroxyecdysone and ecdysone have been found to be the major free ecdysteroids in hemolymph, ovaries and eggs (verified by the HPLC-RIA technique and GC-MF of silylated HPLC fractions). Helix juice (or esterase) labile ecdysteroid conjugates do not seem to be present to any noticeable extent in hemolymph, ovaries and eggs.