Compensatory growth response in three-spined stickleback in relation to feed-deprivation protocols

Different protocols of food deprivation were used to bring two groups of juvenile three-spined sticklebacks Gaslerosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum. One group experienced I week or deprivation then 2 weeks on maintenance rations. The second group experienced I week of ad lithium feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass ore. 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the three-spined sticklebacks had reached the reduced body mass. The compensatory response was Sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipid-free dry mass. Hyperphagia and increased growth efficiency were present in the re-feeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature three-spined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts. (C) 2003 The Fisheries Society of the British isles.

EFFECT OF RATION SIZE ON THE GROWTH AND ENERGY BUDGET OF THE GRASS CARP, CTENOPHARYNGODON-IDELLA VAL

Young grass carp (12-13 g) were kept at five ration levels ranging from starvation to ad libitum feeding at 30-degrees-C. They were fed duckweed. Food consumption, absorption efficiency and growth were determined directly, and metabolism and nitrogenous excretion calculated indirectly from energy and nitrogen budgets, respectively. The relationship between specific growth rate and ration size was linear. Absorption efficiency for energy was not affected by ration size and averaged 50.6 +/- 0.57% (mean +/- s.e.). Depending on ration size, energy lost in excretion accounted for 4.5-5.9% of the food energy, energy channelled to metabolism accounted for 34.4-48.3% of the food energy, and energy retained as growth accounted for 6.7-11.9% of the food energy. Regardless of ration, a constant proportion of food energy (30.7%) was accounted for by feeding metabolism (total metabolism minus fasting metabolism). The energy budget at the maximum ration was: 100 C = 49.1F + 4.5U + 3.6R(fa) + 30.9R(fe) + 11.9G, where C, F, U, R(fa), R(fe) and G represent food consumption, faecal production, excretion, fasting metabolism, feeding metabolism and growth, respectively.

Expression of Scophthalmus maximus CD83 correlates with bacterial infection and antigen stimulation

CD83 is a transmembrane glycoprotein of the immunoglobulin (Ig) superfamily and a surface marker for fully matured dendritic cells (DCs) in humans and mice. In teleosts, DC-like cells and their molecular markers are largely unknown. In this report, we described the identification and expressional analysis of a CD83 homologue, SmCD83, from turbot Scophthalmus maximus. The open reading frame of SmCD83 is 639 bp, which is preceded by a S'-untranslated region (UTR) of 87 bp and followed by a 3'-UTR of 1111 bp. The SmCD83 gene is 4716 bp in length, which contains five exons and four introns. The deduced amino acid sequence of SmCD83 shares 40-50% overall identities with the CD83 of several fish species. Like typical CD83, SmCD83 possesses an Ig-like extracellular domain, a transmembrane domain, and a cytoplasmic domain. The conserved disulfide bond-forming cysteine residues and the N-linked glycosylation sites that are preserved in CD83 are also found in SmCD83. Expressional analysis showed that constitutive expression of SmCD83 was high in gill, blood, spleen, muscle, and kidney and low in heart and liver. Bacterial infection and poly(I:C) treatment enhanced SmCD83 expression in kidney in time-dependent manners. Likewise, bacterial challenge caused significant induction of SmCD83 expression in cultured macrophages. Vaccination of turbot with a bacterin and a purified recombinant subunit vaccine-induced significant SmCD83 expression during the first week following vaccination. These results demonstrate that SmCD83 expression correlates with microbial challenge and antigen stimulation, which suggests the possibility that there may exist in turbot DC-like antigen-presenting cells that express SmCD83 upon activation by antigen uptake. In addition, these results also suggest that SmCD83 may serve as a marker for activated macrophages in turbot. (C) 2010 Elsevier Ltd. All rights reserved.

三种海水经济鱼类早期发育生物学的研究

海水经济鱼类的养殖在我国已经形成第四次海水养殖浪潮，经济效益显著，有力地推动了我国海水养殖的产业结构调整和可持续发展。然而在海水养殖发展过程中也存在着诸多问题，尤其是早期发育阶段的高死亡率，严重制约了我国海水养殖产业的稳定和健康发展。 海水鱼类养殖的关键为高质量，高存活率苗种的生产和培育，由于鱼类种类繁多，生物多样性丰富，对应实际的繁育技术，尤其是新品种的开发，必须要做出相应的调整。这就要求我们必须对每一种鱼类早期发育有所了解，并将形态和组织上的数据用于指导生产。 本文通过显微观察和组织学研究，主要描述和研究了我国北方三种重要的海水经济鱼类(条斑星鲽、杂交鲆、条石鲷)的早期发育生物学，并结合实际生产进一步阐明关键期的产生原因，机理以及采用相应的对策。具体结果如下： 1.条斑星鲽：作为冷温性鲆鲽鱼类，条斑星鲽早期发育过程的特征主要有： ① 条斑星鲽受精卵无油球，卵子呈半浮性；不同步卵裂现象提前，发生在第三次卵裂；卵裂期裂球大小差异大。孵化过程较长，在水温8 ± 0.3℃，盐度33的条件下，经9 d孵化。条斑星鲽胚胎发育的不同时期对温度的敏感性不同，其中原肠期对温度比较敏感。 ②在8-10℃，盐度33的条件下，8-9 dph开口摄食。且开口时，其吻前端出现有一点状黑褐色素，构成了条斑星鲽仔鱼“开口期”的重要标志。卵黄囊于消失。在后期仔鱼末期，背鳍和臀鳍上形成特有的黑褐色条斑带。 ③杯状细胞首先出现在咽腔后部和食道前段，胃腺和幽门盲囊出现于29 dph，变态期始于30dph。在条斑星鲽早期发育过程中，观察到其直肠粘膜层细胞质出现大量嗜伊红颗粒，为仔鱼肠道上皮吸收的蛋白质。 ④首先淋巴化的免疫器官是头肾，然后是胸腺和脾脏，这与大部分硬骨鱼类不同。条斑星鲽除头肾和脾脏外，胸腺实质也形成MMCs。其中以脾脏形成MMCs最为丰富，形态多样。 2. 杂交鲆：为同属的牙鲆和夏鲆间的远缘杂交种，其发育过程的特点为： ① 在温度为15.4～16.0℃，杂交鲆胚胎从受精到孵化所需的时间为76 h左右，胚孔关闭前期，胚胎先出现视囊及克氏囊，而后形成体节。孵出前胚体在卵膜内环绕不到1周。 ② 孵化后消失。杂交鲆群体变态间隔长(34-60 dph)，且变态高峰期出现的冠状幼鳍不明显(与母本牙鲆相比)，数量为7-8根。 ③组织学观察发现，其消化系统中胃腺出现较晚，且胃腺发育过程缓慢(与母本牙鲆相比)。甲状腺滤泡增生不明显，颜色较浅，数量较少。杂交鲆在早期发育过程中，并没有出现鳔原基。 3. 条石鲷作为岩礁性的暖水性鱼类，早期发育过程也较为特殊，包括外形以及内部的器官结构。主要特点有： ① 受精卵：受精卵卵黄上具有龟裂结构，为鱼卵的分类特征之一。 ② 初孵仔鱼：初孵仔鱼背鳍膜上的黑色素，从体背面向背鳍膜边缘移动，到3dph仔鱼基本消失，此为本种仔鱼发育所特有的特点。 ③ 后期仔鱼和稚鱼：肠道肌肉层加厚明显，仔稚鱼胃肠排空率急剧上升，死亡率增加，通过改善常规的投饵方式部分解决了这个死亡高峰的问题。在幼鱼初期，牙齿融合为骨喙，为石鲷科鱼类的特征。 ④胸腺上皮分泌细胞：类似的现象同样在虹鳟鱼中发现，但是虹鳟鱼胸腺上皮分泌细胞不如条石鲷的丰富，同样也不如条石鲷的排列整齐，而是零星分布在胸腺上皮与咽腔接触的表面。除了正常的造血器官—脾脏和头肾外，肝脏、胰腺和鳔等多种组织等也出现MMCs，此现象在硬骨鱼类不多见，一般发生在软骨鱼类。