淡水轮虫休眠卵的研究进展

本文综述了温度、休眠卵形态、光照条件和休眠卵贮存条件等因子对轮虫休眠卵萌发的影响, 以及休眠卵萌发型式差异的生态学意义。温度骤变可以诱导休眠卵萌发, 光照条件对休眠卵萌发率的影响存在种间差异, 母体轮虫的食物和休眠卵贮存条件影响其萌发率。     

萼花臂尾轮虫休眠卵萌发的研究

报道了萼花臂尾轮虫休眠卵的低温贮存时间、萌发温度、光照、孵化液等因子对其萌发的影响．休眠卵萌发率随低温贮存时间的延长而提高,以贮存30～50d作用最显著．在10～30℃温度范围内．萌发率随温度的升高而增加,超过30℃时,萌发率则有所下降．光对休眠卵的萌发是一非必需条件。把休眠卵从不新鲜的孵化液转移到新鲜的孵化液中能刺激其萌发．     

不同培养条件下萼花臂尾轮虫休眠卵的萌发

为确定萼花臂尾轮虫休眠卵的最适形成条件 ,或为提高特定培养条件下形成的休眠卵的萌发率 ,对不同温度、食物、光照和 pH条件下萼花臂尾轮虫形成的休眠卵进行了萌发研究。发现不同培养条件下形成的休眠卵在不同萌发条件下的萌发历时均为实验开始后的第 1～ 7天 ,萌发率高峰均出现在第 1～ 3天。在萌发温度为15℃～ 30℃范围内 ,2 0℃下形成的休眠卵在 2 0℃的萌发温度下累积萌发率最高 ,为 5 2 5 0± 6 89% ;母体以小球藻为食物时 ,其所产休眠卵的平均累积萌发率为 2 7 92 % ,显著大于以斜生栅藻或蛋白核小球藻和斜生栅藻所组成的混合藻为食物时 ;休眠卵形成和萌发时的光照条件对其累积萌发率无显著的影响 ;pH6 5和 7 5条件下形成的休眠卵的累积萌发率较高 ,分别为 32 5 0± 7 0 7%和 38 75± 15 5 3%。本研究和已报道的研究结果表明 :不同培养条件下形成的休眠卵在不同条件下萌发时均呈同步萌发型式 ;2 0℃和pH7 5分别是武汉东湖萼花臂尾轮虫休眠卵形成的最适温度和最适 pH条件。     

环境因子对萼花臂尾轮虫休眠卵萌发率的影响

萼花臂尾轮虫（Ｂｒａｃｈｉｏｕｎｕｓ ｃａｌｙｃｉｆｌｏｒｕｓ Ｐａｌｌａｓ）休眠卵在不同萌发条件下累积萌发率的结果显示,保存在休眠卵形成的原液中,温度为２０℃～３０℃时萌发率均较高,３０℃时用过滤湖水萌发时的萌发率最高（６５％）,保存在无机培养中的休虎卵,用曝气自来水萌发时最主,用湖水次之,无机液萌发效果较差;２０℃和２５℃时三种萌发液中的萌发率接近,母体投喂小球藻形成的休眠卵的累积萌发率高于投     

养鱼池轮虫休眠卵分布和萌发的研究

东北地区部分鱼场养鱼池底泥中轮虫的休眠卵,表层(0—5厘米)数量每平方米为1．2—503万个,个别池塘高达1,573万个,其中完全暴露于泥表面的数量约占1—2％。休眠卵数量差别和池塘环境条件关系密切;各泥层中的轮虫休眠卵数量呈“V”形垂直分布的趋势。萼花臂尾轮虫和角突臂尾轮虫的休眠卵在水温10-40℃;pH4．5-11．5;溶氧0．3毫克／升以上和盐度8．5%以下的条件下可以萌发。10℃为其发育的生物学零度。根据轮虫休眠卵分布和它的环境条件的关系,以及萌发的生态条件,阐述了在养鱼池中增殖轮虫所应采取的措施及其理论根据。     

种子萌发和休眠的调控

种子的萌发和休眠受外界因子和种子本身的特征如种子的结构、植物激素的含量以及种子所携带的遗传信息等的影响。在种子发育后期,种子成熟脱水,处于发育停滞(develop-mental arrest)。在这个阶段,种子可能是休眠(初生休眠)或者是非休眠(图1)。休眠种子不可能被完全适合的萌发条件诱导萌发。通常应用一定的温度范围能够打破干燥种子的     

轮虫休眠卵形成和萌发的生态机理研究进展

休眠卵的形成是单巢目轮虫生殖行为中最显著的特征之一。作为一系列有性生殖过程的产物,休眠卵具有抵抗外界不良环境、易于扩散和通过重组产生遗传多样性等特点。轮虫休眠卯是轮虫集约化培养的重要种源,通过轮虫快速的孤雌生殖在短时间内大量繁殖,使得轮虫作为鲜活饵料为水产经济动物的苗种生产起到了极其重要的作用。但是在生产实践中,利用孤雌生殖批量培养轮虫常会因难以预测的种群突然崩溃而造成水产经济动物苗种生产的重大损失。为此,Ｌｕｂｚｅｎｓ等［１］提出以轮虫休眠卵的萌发产生幼体供苗种生产所需要;李永函等也曾提出通过…     

毛叶山桐子种子休眠与萌发特性的研究

目的：探究毛叶山桐子种子(Idesia polycarpa Maxim. var. vestita Diels)的休眠类型和解除休眠的最适方法，为生产实践中的种苗繁育提供一种能有效解除毛叶山桐子种子休眠和提高萌发率的方法。方法：以成熟的毛叶山桐子种子为材料，研究种子的水分透性及温度、光照、去垢剂、后熟、层积和植物激素对种子休眠与萌发的影响。结果：(1)种子具有发育成熟的胚，种皮被有蜡质层但具有透水性；(2)在10～35℃和交替光照(12 h光照/12 h黑暗，光强度为144μmol·m^-2·s^-1)下萌发30 d，种子的萌发率低于30%，具有休眠特性；(3)种子在完全黑暗条件下几乎不萌发，是一种需光性种子；(4)4℃和10℃层积30 d显著地增加种子的萌发速率和萌发率，后熟90 d则对种子萌发没有影响；(5)GA3能部分解除种子的休眠和促进萌发，将萌发率提高至56.7%，氟啶酮则没有作用。结论：毛叶山桐子种子的休眠类型为非深度生理休眠，解除休眠和促进萌发的最适方法是将种子在4℃或者10℃中层积30 d，然后在25℃和交替光照中萌发。     

镜湖沉积物中轮虫休眠卵的原位萌发

将2004年春季采于芜湖市镜湖的沉积物样品在不同季节进行原位萌发发现,除冬季未见有轮虫孵出外,其余3个季节共孵出轮虫39种,隶属于7科19属;大湖区每200ml沉积物中休眠卵萌发出的轮虫数量平均为212.2个±48.9个,显著高于小湖区的39.1个±10.3个。大湖区沉积物在夏季萌发出的小巨头轮虫(Cephalodella exigua)、大肚须足轮虫(Euchlanis dilatata)和壶状臂尾轮虫(Brachionus urceolaris)、秋季萌发出的裂足臂尾轮虫(B.diversicornis)和角突臂尾轮虫(B.angularis)以及春季萌发出的暗小异尾轮虫(Trichocerca pusilla)和等刺异尾轮虫(T.similis)分别占各季节总萌发数的51.1%、19.7%、15.7%、14.7%、11.1%、38.4%和23.7%,小湖区沉积物在夏季萌发出的多须伪前翼轮虫(Proalides tentaculates)和暗小异尾轮虫、秋季萌发出的裂痕龟纹轮虫(Anuraeopsis fissa)、尖趾单趾轮虫(Monostyla closterocerca)和大肚须足轮虫以及春季萌发出的尖趾单趾轮虫、盘状鞍甲轮虫(Lepadella patella)和暗小异尾轮虫分别占各季节总萌发数的53.9%、31.6%、18%、17%、13%、31%、24.1%和17.2%。各季节萌发出的轮虫与同季节水体中存在的轮虫种类及数量间存在的较大差异表明,那些常年存在于水体中的轮虫所产的休眠卵的萌发对其种群增长的直接贡献可能不大;而那些每年都要从水体中消失一段时间的轮虫所产的休眠卵的萌发在其种群重建中的作用可能因种类的不同而异。     

河口近海桡足类休眠卵生态学研究进展

桡足类是水域生态系统的关键类群,在物质循环、能量流动和信息传递中起着重要作用.休眠卵是桡足类的重要生存策略,在抵抗不利环境、维持种群延续等方面起着重要作用.本文综述了河口近海桡足类休眠卵种类组成及其分布、休眠卵存活时间、休眠卵萌发率和沉积物中休眠卵丰度以及对水体的潜在补充量及其影响因素等.对河口近海桡足类休眠卵生态学研究提出了展望,以期为相关研究提供新的思路.     

Zur fortpflanzungsbiologie von mesostoma ehrenbergii (Focke, 1836) (Turbellaria)

1. At temperature levels from 10 to 25°C animals from resting eggs produce subitaneous eggs independent on temperature. In contrast animals from subitaneous eggs produce subitaneous eggs dependent on temperature. At a high rate subitaneous eggs are only formed at temperature levels above 20°C.
2. Below 10°C no development occurs in the juveniles. At temperatures of 30/22°C (24.7°C) the first subitaneous eggs are formed after 6–9 days, at 14/9°C (10.7°C) they are formed after 34 days. At different temperature levels the developmental rate of the young is from 10.5 to 42 days. One generation extends over 16.5 (30/22°C) to 75 days (14/9°C). The average egg production is 10–20 subitaneous eggs or 30–60 resting eggs. The maximum egg production of one individual is 50 subitaneous eggs or 84 resting eggs. 50% of the animals have just formed resting eggs, before the juveniles are hatched. Resting eggs in the first egg-batch are formed 6–20 days later than subitaneous eggs. The duration of life is between 65 (30/22°C) and 140 days (19/13°C).
3. Young worms in resting eggs have a dormance period of at least 15–30 days.

At room temperatures (20°C) no juvenile in resting eggs hatches from water. By combining room and refrigerator (3.5°C) temperatures the hatching rate increases to a maximum of 85%. To reach a hatching rate of 50–65% the influence of low temperatures must be at least 30 days. At room temperatures 60% of the young in resting eggs hatch from mud covered with water. Combining high and low temperatures the hatching success is between 67 and 81%, where the highest percentage of the young may hatch at room temperature. Up to 90 days low temperatures cause a maximum hatching rate of 79%. It decreases to approximately 30% after 180 days. At high temperatures resting eggs preserved in 100% moist mud, survive for two months. By adding a period of low temperatures the hatching rate increases to a maximum of 52%. Low temperatures are survived for more than 6 months. Up to 30 days preservation at 3.5°C causes a maximum hatching rate of 61%, up to 12o days it decreases to 30%. At room temperature the young in resting eggs are not resistant against air-dried mud (30–40% rel. air moisture). Combining high and low temperatures air-dried mud is endured 1 month (hatching rate 5–14%). Preservation of 30–120 days at 3.5°C and 70% rel. air moisture result in a hatching rate of 43–61%. li]4. In the open air in Middle-Europe there occur 5–6 generations of M. ehrenbergii per life-cycle. The first generation hatches from resting eggs in May, where the production of subitaneous eggs is independent on temperature. All other generations up to October hatch from subitaneous eggs. The egg-production of those worms is dependent on environmental factors. In summer subitaneous egg production prevails, in autumn resting egg production. The abundance during the life-cycle is dependent on the number of animals which produce subitaneous eggs. Resting eggs are predestinated to endure periods of dryness and cold. The life-cycles of the species M. lingua and M. productum are different from those of M. ehrenbergii in length and in the number of generations. In both species 7 generations occur over 8 to 8.5 respectively 5.5 months. M. nigrirostrum only forms resting eggs. The life-cycle consists of one generation from February/March to May/June.     

Resting eggs in rotifers

The biology of resting eggs of monogonont rotifers is reviewed, covering literature published since the last major review by Gilbert (1974). The topics examined include resting egg production, morphology and species specificity, hatching, and evolutionary significance. Four major determinants of resting egg production are identified: mictic female production, male activity and fertility, female susceptibility to fertilization, and fertilized female fecundity. Recent work in these four areas is discussed as well as resting egg production in natural populations. Resting egg morphology, particularly shell structure and internal organization, is compared among species. Recent reports on the control of resting egg hatching in the laboratory are examined and the importance of temperature, light, diet, and salinity is reviewed. Two hatching patterns are contrasted, the first where eggs hatch at regular intervals over extended periods and the second where hatching is synchronized to some environmental cue. A latent period after resting egg formation, during which no hatching occurs, is defined for several species. The adaptive features of resting eggs are outlined including their contribution to genetic variability through recombination, their provision for environmental escape by dormancy, and their colonizing function resulting from their ease of dispersal. The type of cue utilized to initiate mictic female production as well as the pattern of resting egg hatching is related to environmental predictability.     

Hatching of cladoceran resting eggs: temperature and photoperiod

Summary 1. We identified temperature and photoperiod conditions under which the hatching of 45 cladoceran species could be elicited. Identification of appropriate hatching cues is of primary importance for the exploration of the ties between active and diapausing stages.
2. Incubation temperature affected the hatching success of resting eggs isolated from Danish, Belgian/Dutch and Spanish sediments. In general, most hatchlings and species were retrieved at 15 °C. Danish and Belgian/Dutch resting eggs hatched more successfully under a long day photoperiod than in continuous illumination.
3. Most species could be retrieved after incubation of resting eggs isolated from a limited amount of sediment (0.4 kg) under a single, well chosen combination of temperature and photoperiod. Processing additional sediment samples under seven more incubation regimes only allowed detection of 21% (Spain) to 34% (Denmark) more species.
4. The incubation period for resting eggs to hatch was strongly influenced by incubation temperature. Our results show that hatching experiments aimed at assessing cladoceran species richness and conducted at 15 °C should be continued for a period of at least 2 weeks, after which a random subset of hatchlings (e.g. n  = 100) can be selected from the total hatchling assemblage.     

池塘桡足类休眠卵对浮游种群的潜在补充及其影响因素

休眠卵是桡足类的重要生存策略,其在沉积物中的丰度对水体种群的补充具有重要意义.干塘是池塘养殖管理的重要措施,对池塘生态系统具有重要影响.2014年2月15日(干塘前)和3月2日(干塘后),分别采集广州市南沙区养殖池塘内表层沉积物,研究沉积物中桡足类休眠卵对浮游种群的潜在补充及影响因素.结果表明: 干塘前未冷藏沉积物样品在盐度20时的潜在补充量和孵化率最高,4 ℃冷藏4周后最高值出现在盐度为15的处理组.干塘后未冷藏沉积物样品在盐度15时的潜在补充量和孵化率最高,冷藏4周后最高值出现在盐度为20的处理组.这说明干塘前桡足类休眠卵的潜在补充量显著高于干塘后,且干塘对沉积物中休眠卵的持续孵化时间有影响.     

Effect of incubation and preservation on resting egg hatching and mixis in the derived clones of the rotifer Brachionus plicatilis

The marine rotifer Brachionus plicatilis typicus (Clone 8105A, Univ. of Tokyo) was cultured in 500 ml beakers to form resting eggs. Tetraselmis tetrathele was used as a culture food. Just after formation, resting eggs were exposed to various temperature (5–25 °C) and light regimes (24L: OD and OL : 24D). When eggs were exposed to light just after formation, the eggs hatched sporadically over a month. No hatching was observed for six months when eggs were preserved under dark conditions regardless of the temperature. These eggs hatched simultaneously after being exposed to light and eggs preserved at 5 °C showed twice as high hatching rate (40%) as that of eggs preserved at 15–25 °C (24%). Clones from resting eggs that were kept under different temperature and light regimes were reared individually to the third generation. Incubation at 25 °C with lighting produced the highest (5.4% and 5.2 %) rate of mictic females during their 2nd and 3rd generations, respectively. The lowest rates (0 and 1.5%) were found when the eggs were kept at 5 °C in total darkness for six months. A lower rate of amictic female production was found in clones with higher rates of mixis.     

Methods for the activation of the resting eggs of Daphnia

SUMMARY. 1. The conditions required to initiate development of resting eggs of thirty-six clones of Daphnia representing seven species were investigated.
2. The temperature of both dark incubation and subsequent light treatment are shown to affect hatch success. By varying these parameters the majority of resting eggs from each test clone were stimulated to develop. Arctic clones required a low hatching temperature (7°C), whereas clones from warmer climates hatched best at 14–21°C.
3. Variation in hatching cues existed between conspecific individuals from different collection sites. These differences suggest that research determining macro- and microgeographic patterns in hatching phenology would be fruitful.     

Hatching rates of resting eggs of 'Cladocera' (Crustacea; Branchiopoda) at a tropical bay, Brazil.

The aim of this study was to determine the development time of embryos and to estimate the hatching rates of resting eggs of cladocerans found in the sediment of Guanabara Bay, Rio de Janeiro, Brazil, under experimental conditions. Eggs were sorted by species (Penilia avirostris--Sididae; Pleopis polyphemoides and Pseudevadne tergestina--Podonidae) and incubated at a temperature of 25 degrees C, salinity 35 and photoperiod 12 hours light/ 12 hours dark. Hatching rates were about 38% for Pseudevadne tergestina and 28% for Pleopis polyphemoides. Embryos of resting eggs of Penilia avirostris developed comparatively slowly (hatching after 86 days of incubation), with a hatching rate of only 5%. It was observed that development and hatching of resting eggs of marine cladocerans suggest that pulses of recruitment may exist, thus contributing to the rapid appearance and maintenance of planktonic populations of these crustaceans in Guanabara Bay.     

Patterns in the abundance,phenology, and hatching of the resting egg stage of the invasive zooplankter <Emphasis Type="Italic">Bythotrephes longimanus</Emphasis>: implications for establishment

To examine how dormancy contributes to the establishment and persistence of Bythotrephes longimanus, we investigated resting egg production and hatching in relation to the demography of the planktonic stage and environmental conditions in Island Lake Reservoir (USA). During a 3-year study, the largest contribution to the egg bank occurred in autumn and most eggs hatched in spring, but we also detected some resting egg production and hatching in summer. The difference between summer and late autumn densities of eggs in sediments averaged 47% (range 0–98%) for 18 sites throughout the reservoir, which was similar to experimental estimates of in situ hatching fraction of 67% for eggs in the spring and summer following their production. Based on emergence traps, neonates hatch in the field during May and June. We estimated mortality rates of 64% for resting eggs and embryos, and 59% for newly emerged neonates. Although hatching fraction saturated at the same level, eggs incubated offshore hatched later than those nearshore where water temperature was warmer and light was detectable at the sediment surface. Low dissolved oxygen concentration did not significantly reduce hatching fraction but resulted in some eggs that initiated development but failed to hatch. Collectively, our results demonstrate substantial annual turnover in the resting egg bank of B. longimanus and high mortality of resting eggs during recruitment from the egg to the first molt of the planktonic stage. These patterns suggest that propagule pressure in the form of resting eggs requires large numbers for establishment, and that considerable post-establishment resting egg production is necessary for inter-annual persistence.     

休眠卵孵化对策与食物浓度对萼花臂尾轮虫(Brachionus calyciflorus)两品系干雌体种群增长的影响

周期性孤雌繁殖的轮虫靠休眠卵度过不良环境,等环境适宜时休眠卵孵化出干雌体,再次通过孤雌繁殖建立种群。通常休眠卵要经历一段休眠期再孵化,但也有些休眠卵生成后很快孵化,称为早孵化现象。有关休眠卵不同孵化对策如何影响其干雌体克隆种群的增长,目前尚不清楚。分别观测了萼花臂尾轮虫（Brachionus calyciflorus）的两个品系H1（窄温度生态位）和D1（宽温度生态位）的休眠卵在不同孵化对策和不同食物浓度下所生产的干雌体克隆群的种群增长差异。孵化对策包括早孵化（early hatching,EH）和晚孵化（late hatching,LH）;食物浓度包括高食物浓度（high food concentration,HF：2×10⁶个细胞/mL）和低食物浓度（low food concentration,LF：5×10⁵个细胞/mL）,每个品系下各设置4个实验组（LH-HF、LH-LF、EH-HF、EH-LF）,每组10个重复。结果发现,对D1品系来说：孵化对策和食物浓度对最大种群数量具有显著的综合影响（P=0.002）,但两因素间不存在交互作用（P=0.911）;早孵化的干雌体种群在最大种群数量上显著高于晚孵化的干雌体种群（P=0.001）。对H1品系：孵化对策和食物浓度对最大种群数量综合影响显著（P<0.001）,且两个因素之间存在交互作用（P<0.001）;高食物浓度下,EH干雌体克隆群的最大种群数量显著低于LH干雌体克隆群（P<0.001）。高食物浓度下干雌体克隆群开始有性生殖的密度阈值,D1品系EH组显著高于LH组（P=0.041）;而H1品系EH组却显著低于LH组（P=0.022）。最高种群密度下,H1品系的有性生殖率在两种孵化对策之间存在显著差异（P=0.044）,EH种群的有性生殖率低于LH种群,而D品系却未见有性生殖率在不同孵化对策间存在明显差异。本研究结果显示休眠卵的孵化对策会影响其后代干雌体种群的增长特性,其影响的结果可能与种群的生境适应相关。