Cytoplasmic Nucleoids in the Generative Cell,Sperm Cell and Egg Cell of Calystegia heder acea

Cytoplasmic nucleoids in the generative cell of mature pollens, sperm cells of pollens cultured in vitro and egg cell of mature embryo sac in Calystegia bederacea Wall. were studied by means of the DNA fluorochrome DAPI in conjunction with epitluorescence microscopy for in situ detection of cytoplasmic DNA in cells. Results showed that many cytoplasmic DNA nucleoids were present in the generative cell and speim cells. Two types of nucleoids were observed, one with big and strong fluorescent dots, and the other with small and weak fluorescence. Many dot-shaped and a few circle-shaped nucleoids were randomly distributed in the thin layered cytoplasm of the egg cell. It was suggested that different types of nucleoids might represent plastid DNA and mitochondrion DNA respectively. Results provided cytological data that Calystegia hederaeea had the potential of plastid DNA biparental inheritance, and the mode of which merits further study via molecular biological methods.     

THE EVOLUTION OF OVIPARITY WITH EGG GUARDING AND VIVIPARITY IN LIZARDS AND SNAKES: A PHYLOGENETIC ANALYSIS

This paper investigates the evolution of viviparity and of egg guarding in lizards and snakes in which three modes of reproduction can be described: oviparity without egg guarding, oviparity with egg guarding, and viviparity. All possible transitions of reproductive modes were detected in each taxon using Maddison's method. We then tested two specific hypotheses. First, egg guarding can be regarded as an alternative to viviparity. A relatively frequent association of egg guarding and viviparous species in the same taxon may be due to similar environmental conditions or species characteristics leading to two different solutions. Second, egg guarding may facilitate the evolution of viviparity. This hypothesis is supported by the high frequency of viviparous species in taxa containing egg guarding species and by a tendency for prolonged uterine retention of eggs in brooding squamates. Our analyses demonstrate that the first hypothesis is the best supported. Egg guarding and viviparity most often evolved independently. If a major benefit of egg guarding is the repulsion of potential predators, size is one of the most obvious morphological characters that should be correlated with the evolution of reproductive modes. The two reproductive traits were correlated to a reduction in body size for viviparous species and an increase in body size for egg guarding species. This could partly explain why the evolution of these reproductive modes seems almost antagonist.     

中华鳖卵孵化过程中物质和能量的动态

在温,温度分别为30℃,－220kPa条件下孵化中华鳖（Pelodiscus sinensis)卵,以检测孵化过程中胚胎生长及对物质和能量的利用,孵化过程中,每隔7天测定卵重,孵化第10天始,每隔5天解剖15枚卵,分离为胚胎,卵黄和卵壳,初生幼体称重后冰冻处死,随后解剖分离为躯干,剩余卵黄和脂肪体,所有样品65℃恒温干燥,用索氏抽提仪测定脂肪含量,氧弹式热量计测定能量含量,马福炉测定无机物含量,本研究中华鳖卵的平均孵化期为45．5天,卵重量在孵化过程中基本维持恒定,表明中华鳖镦与环境的水分交换不明显,孵化第0－20天,20－30,30－40天和40－45天,胚胎分别利用新生孵内总能量的6％,24％,59％和4％,0－30天,胎生长缓慢,30－40天,胚胎生长最迅速,孵化末期胚胎生长减缓,胎发育所需的无机物来自卵黄和卵壳,卵壳提供的无机物约占初生幼体无机物总量的13．5％,孵化过程中,干物质,脂肪和能量的转化率分别为79．6％,58．7％和66．5％,初生幼体的能组成为：躯干占71．8％,脂肪体占19．4％,剩余卵黄占8．8％。     

Phylloplane bacteria increase the negative impact of food limitation on insect fitness

1. When populations of herbivorous insects increase in density, they can alter the quantity or quality of their food. The impacts of diet‐related stressors on insect fitness have been investigated singly, but not simultaneously. 2. Foliage quantity and quality of red alder, Alnus rubra, were manipulated together with the presence of non‐entomopathogenic phylloplane bacteria to investigate their impacts, singly and in combination, on survival, pupal mass, growth rate, fecundity and egg quality of a cyclic forest insect, the western tent caterpillar, Malacosoma californicum pluviale. 3. Food limitation (half food) had strong negative impacts on all life‐history traits. When the larvae were fed continuously, however, neither ingesting phylloplane bacteria nor eating leaves from damaged branches (induced foliage) affected survival. In the half‐food treatment, ingesting bacteria further increased mortality, while feeding on induced foliage improved survival. 4. Growth rate and pupal mass of both sexes were reduced for larvae with food limitation compared with continuously fed insects and this was exacerbated when the larvae also ate bacteria‐treated leaves. A combination of bacteria and induced foliage also reduced larval growth rate by 5% in the full‐food treatment. 5. Fecundity (eggs per egg mass) was 2.7 times greater in full‐food than in food‐limited treatments but neither phylloplane bacteria nor plant induction had an effect. Insects fed induced foliage produced smaller eggs. Overall, there was no evidence of a three‐way interaction between the three stressors, although there were negative synergistic effects, primarily between food limitation and the ingestion of phylloplane bacteria.     

Thermal Requirements and Parasitism Capacity of Trissolcus brochymenae (Ashmead) (Hymenoptera: Scelionidae) Under Constant and Fluctuating Temperatures, and Assessment of Development in Field Conditions

In order to understand the relative importance of Trissolcus brochymenae , a common egg parasitoid of the predatory stinkbug Podisus nigrispinus in areas where this predator is released, the thermal requirements and developmental periods (egg to adult) at constant (17, 20, 25, 28 and 32°C) and fluctuating (10-20, 13-23, 15-25, 17-27, 20-30 and 25-35°C) temperatures, and the effect of constant and fluctuating temperatures systems on the longevity and parasitism capacity of T. brochymenae were investigated. Based on thermal requirements of the parasitoid and field day/night temperature variation in the regions where P. nigrispinus was released, we calculated monthly and yearly number of generations of the parasitoid. Parameters of biological and thermal requirements of T. brochymenae were not affected when the insects were reared under constant or fluctuating temperatures. It was shown that males have a shorter developmental period and lower thermal requirements than females. The lowest parasitism capacity and shortest longevity of T. brochymenae were observed under fluctuating temperature regimes of 10-20oC and 25-35°C. A higher parasitism capacity was obtained under a 20-30°C regime (96.0 ±33.6 offspring per female), while longevity was longer at a constant temperature of 27°C (17.6 ±0.6 days). T. brochymenae showed a continuous development during all seasons through the year under field conditions, accomplishing 2.7, 2.4, 2.9 generations per month in the CAF, Pains, and Refloralje areas. An average of 26.4 and 25.8, 25.8 and 25.3, and 24.7 and 23.6 generations per year under constant and fluctuating temperatures systems was estimated for the CAF, Pains, and Refloralje areas, respectively. No significant difference between thermal systems in each area was observed; however, a significantly smaller number of generations per year were estimated to occur in the Refloralje area. Implications of these results for the forecasting of parasitoid population development and its impact on the host stinkbug predator are discussed.     

被子植物雌雄配子及早期胚胎的分离与研究应用

被子植物的有性生殖过程复杂精巧并深藏于母体组织内进行,一直以来难以对该过程进行直接的细胞学和分子生物学研究。如今在多种植物中获得了有活力而无污染的配子细胞和早期胚胎,结合少量细胞m RNA提取技术、基因组深度测序以及离体授精系统等技术,人们已能对被子植物受精过程中的配子识别、配子融合、合子激活等重要发育事件进行深入分析。本文对有代表性的被子植物配子和早期胚胎的分离技术及其在受精作用研究中的应用、存在的问题和前景进行了总结,旨在为植物生殖发育研究提供帮助。     

中国对虾受精过程中精卵核的细胞学变化

中国对虾精子以其棘部顶端随机附着在卵上,精子在凝胶膜形成后,第一极体排出前入卵,精子入卵后,絮状的精核经过重建形成雄原核,中国对虾卵子排放时处于第一次成熟分裂的中期,卵子入海水时,纺锤体的长轴与质膜平行,卵子激活后,纺锤体的长轴开始旋转,旋转至纺鲑体长轴与质膜垂直时,由纺锤丝牵引着染色体向两极移动,外侧的染色体由质膜包裹形成第一极体,受膜举起后,由次级卵母细胞排放出第二极体,此后,单倍雌核重建形成雌原核,雄原核形成早于雌原核,雌雄原核于卵子中央联会形成联合核,受精后的50分钟纺锤丝牵关染色体称向两极,质膜内缢断裂形成两个细胞的胚胎。     

Spawning behavior of Arctic charr (Salvelinus alpinus): Spawning synchrony,vibrational communication,and mate guarding

A mismatch in synchrony between male and female gamete release in external fertilizers can result in reduced or failed fertilization, sperm competition, and reduced paternity. In Arctic charr (Salvelinus alpinus), males can adopt either a guard or sneak tactic resulting in both pre‐ and postcopulatory competition between males with alternative reproduction tactics. Here, spawning behavior of free‐living Arctic charr was video‐recorded, and their reproductive behavior was analyzed. From evaluating 157 spawning events, we observed that females mainly spawned with a guarding male and that the female and the guarding male synchronized timing of gamete release under sperm competition. Although sneakers spawned with higher synchrony than the guarding male in single‐male spawning events, the average sneaker released his milt less synchronized with the female than the guarding male under sperm competition. Approximately 50% of the recorded spawning events occurred under sperm competition, where each event included an average of 2.7 males. Additionally, sneakers were more exposed to sperm competition than guarding males. An influx of males, in close proximity to the female, occurred during the behavioral sequences leading up to egg release, but this influx seemed not dependent on egg release, suggesting that something else than gonadal product attracts sneaker males to the spawning female. Just before and during the actual release of gametes, the spawning couple vibrates their bodies in close contact and it seems likely that this vibrational communication between the spawning couple, which results in a larger amplitude sound wave than seen under regular courting, reveals time of gamete release to sneaker males. Thus, vibrational communication may enable synchrony between the guarding male and the female, and this might be traded against the cost of higher detectability from surrounding sneaker males, eavesdropping in close proximity.     

滇池金线鲃亲鱼培育、繁殖力以及卵径大小与胚胎存活率的关系

2007—2010年,对滇池金线鲃(Sinocyclocheilus grahami)进行了亲鱼培育、繁殖力和卵径(egg diameter,ED)大小的研究。滇池金线鲃的催产率、核偏位率和孵化率分别由2007年的25.2%、61.5%和30.4%到2010年的91.3%、85.2%和44.5%。四年间这3项指标均有不同程度提高,其中,催产率提高的幅度最大。提供适合滇池金线鲃营养全面的饵料可以保证亲鱼培育的最佳效果,获得高质量的鱼卵和鱼苗。滇池金线鲃绝对怀卵量与体长的关系是F=0.0004826SL3.166(R2=0.6424,P<0.05)。四年来滇池金线鲃的平均产卵量为(2118.4±899.1)粒,平均绝对怀卵量为(2402.9±881.9)粒,平均相对怀卵量为(70.4±20.8)粒。产卵量、绝对怀卵量和相对怀卵量都有随着体长增加而增加的趋势。卵的大小与胚胎存活相关,在胚胎发育的前两天,不同批次胚胎的死亡呈现一种稳定的或低的死亡率;而后5～7d不同大小的卵呈现不同的死亡率,即小的卵具有更高的死亡率;而卵径>2.0mm的胚胎死亡率趋于稳定;大的卵有更高的生存潜力,能保证仔鱼开口前继续完善身体器官的形成或发生所需要的能量。     

The behaviour of laying workers and the morphology and viability of their eggs in Melipona bicolor bicolor

Abstract. As in many other stingless bees, Melipona bicolor bicolor Lepeletier (Apidae: Meliponinae) workers lay two morphologically distinct types of eggs: slender ones that have a typical patterned chorion, and larger ones that lack this pattern. In this paper we report on the relation between egg morphology and the behaviour of the workers that lay such eggs. In most cases, the laying of each of these egg types is accompanied by a unique sequence of behaviours. After a worker has laid the unpatterned type of egg, she generally leaves the cell, giving the queen the possibility of eating this egg. In the case of the patterned egg type, the worker usually closes the cell immediately after her egg laying. When worker egg laying occurs right after a series of regurgitations, it stops the queen from ovipositing. When, instead, a worker lays an egg after queen oviposition, the cell contains two eggs. This study also revealed cases in which workers laid slender, patterned eggs without closing the cell, and other cases where workers laid large, spherical, unpatterned eggs and instantly closed the cell. Experiments in which worker eggs, destined to be eaten by the queen, were protected by covering the cell artificially with a piece of wax showed that some of these eggs developed into larvae, although they were occasionally relatively small. The occurrence of a range of combinations of egg-laying behaviours and egg morphologies in M. b. bicolor workers is discussed from the perspective of worker egg laying in other stingless bees.