Digestive capacity, intestinal morphology, and microflora of 1-year and 2-year old Atlantic cod (Gadus morhua) fed standard or bioprocessed soybean meal

The objectives of this work were to evaluate how dietary soybean meal (SBM) or a soy meal made by bioprocessing the SBM (BPSBM) to remove anti-nutritional factors affected hydrolytic capacity, amino acid absorption, intestinal morphology, and microflora along the intestinal tract of Atlantic cod at two life stages. Three fish meal based standard cod diets were formulated to contain no soy (FM control), 25% SBM, or 22% BPSBM. Prior to sampling the diets were fed to duplicate groups of 0.5 kg (1-year old) and 1.7 kg (2-year old) cod for a period of 3 months, and the groups reached 0.9 and 2.5 kg, respectively. Digesta was then sampled from different intestinal sections for analyses of trypsin and amylase activity as well as absorption of amino acids, nitrogen, and sulphur. Gastrointestinal sections were sampled for measurements of relative weight (kg^− 1 body weight), and tissues from these sections were sampled for analyses of brush border enzyme (alkaline phosphatase (ALP), leucine aminopeptidase (LAP), and maltase) activity and histological examination. Microflora was sampled from both digesta and the intestinal wall. The SBM diet stimulated relative growth of all gastrointestinal sections except the distal intestine in both age classes. Relative growth of the pyloric intestine was also stimulated by BPSBM. The pyloric caeca and the upper mid intestine were found to be the major sites for enzymatic hydrolysis of protein and starch and for amino acid absorption. Dietary SBM and BPSBM did not alter the activity of trypsin and LAP, but the activity of these enzymes in the proximal intestine was affected by age, being higher in 1-year old than in 2-year old cod. The rate of amino acid, nitrogen, and sulphur absorption along the gastrointestinal tract was not affected by SBM, but was slowed by BPSBM. Dietary SBM or BPSBM did not alter the morphology of the intestinal mucosa in any sections of the cod intestine. The distal-most structure of the intestine, a compartment with inlet and outlet (anus) valves, showed very high microbial colonisation in the mucosal brush border. Inclusion of SBM in the diet changed the intestinal microflora, increasing the population level of transient bacteria in the pyloric and mid intestine, but reducing the population level of adherent bacteria throughout the intestine. To conclude, Atlantic cod appeared to have a robust and flexible digestive system able to adjust to high dietary levels of soy protein meals.     

黑龙江银鲫雌雄同体的组织学

从方正银鲫自交繁殖的当年鱼群体中发现约有２％左右的雌雄同体。外形观察两侧性腺的分配和着生方式十分复杂和多样。一般为一侧精巢,另一侧为卵巢,但常见到一侧性腺,精巢和卵巢交替着生,有时则从卵巢旁生出一个球状精巢或囊状组织,但未见精巢旁长出球状卵巢的。组织学观察,两种组织的界限分明,雌雄同体的精巢和卵巢都发育良好。精巢壶腹中充满各时相的精原细胞、精母细胞和精子。卵巢则充满Ⅳ期中的卵母细胞,但与精巢交接处的卵细胞或进入精巢中少量卵细胞则发育迟缓,一般处于Ⅱ、Ⅲ时相。非常奇特的是：从卵巢旁生长的小囊状组织,一半为精巢,一半为卵巢,精巢发育良好,可见到各时相的精细胞,但卵巢发育不良,大多是Ⅱ、Ⅲ时相的卵细胞。两种组织交接处有膜分隔,同时有血管通过,供两组织营养。     

牙鲆脑垂体早期发育的组织学观察

垂体作为鱼类最重要的内分泌器官之一,在生长、发育、生殖以及其他一些内分泌相关生理活动中起重要作用。作者采用组织学方法观察了牙鲆的脑垂体发生,对不同发育时期的腺垂体细胞进行了初步鉴定。结果表明,孵化后1d仔鱼的间脑下方可见一实心细胞团,于孵化后3d迁移至间脑后方的漏斗体下,与来自漏斗体的神经内分泌细胞及其神经纤维结合共同形成脑垂体,前者形成腺垂体,后者则主要形成神经垂体。孵化后8d腺垂体分为中间部(Pars intermedia,PI)和外侧部(Pars distalis,PD)两部分。孵化后14d腺垂体分化为前外侧部(Rostral pars distalis,RPD)、中外侧部(Proximal pars distalis,PPD)和PI共3部分,为"前后型"脑垂体。稚鱼变态期间及变态完成后的幼鱼,各部分从"前后型"排列开始向"背腹型"排列转变。孵化后14d的牙鲆仔鱼中,PPD细胞多呈强嗜酸性,至变态完成后一直是PPD的主要细胞;PI靠近神经纤维的细胞呈强嗜碱性。孵化后42d的牙鲆幼鱼RPD中,与神经垂体相邻的少量细胞呈嗜碱性,而其下方细胞则呈嗜酸性。根据成体牙鲆激素分泌细胞的染色特征对上述各细胞类型进行了推测。     

哲罗鱼肝脏和胰脏发生和发育的组织学研究

采用形态观察与连续组织切片技术,观察和研究了哲罗鱼（Hucho tai men）肝脏和胰脏在胚胎期（水温7～8℃）和胚后期（水温3～14℃）的发育。结果表明,与大多数硬骨鱼类不同,哲罗鱼的肝脏是在破膜前就开始发生、发育,而胰脏是在破膜后出现,以后逐渐发育完善。受精18 d肝原基细胞出现,破膜8 d,胰细胞出现,破膜8 ...     

宽口裂腹鱼消化系统解剖和组织学观察

该研究采用解剖、石蜡切片和HE染色法对宽口裂腹鱼(Schizothorax eurystomus)消化系统解剖特征和组织切片进行观察。结果显示,其消化管管壁由内向外分别为黏膜层、黏膜下层、肌层和浆膜,主要差别在于黏膜层和肌层。食道黏膜上皮为复层扁平上皮,上皮间分布有大量杯状细胞;前肠和中肠黏膜上皮为单层柱状上皮,明显可见刷状缘、杯状细胞和淋巴细胞分布其间;后肠黏膜上皮为假复层柱状上皮,其间也有杯状细胞和淋巴细胞分布,肠道中杯状细胞由前至后逐渐增多。食道肌层为内环外纵的骨骼肌;前肠肌层为内环外纵的平滑肌;中肠和后肠为内螺旋外环行的平滑肌。消化腺由肝脏和胰腺组成,胰腺弥散状分布在肝脏中,肝小叶不明显。研究表明,宽口裂腹鱼消化系统组织学特征与其食性具有适应性。     

施氏鲟仔鱼眼的组织学观察

对施氏鲟仔鱼的眼球进行组织学观察,发现其眼球结构由外至内分为角膜—巩膜层、虹膜—脉络膜层、晶状体及视网膜层。其未发现脉络腺,且有眼柄;未发现参与晶状体调节的平滑肌,并有类似镰状突的特殊结构;同时施氏鲟仔鱼的视网膜中只有视杆细胞和单视锥细胞,这些结构特征不同于软骨鱼,也与大部分硬骨鱼有差异。     

The reproductive biology of the baby clam, Marcia opima, from two geographically separated areas of India

A study of the reproductive cycle of the baby clam, Marcia opima (Gmelin) was conducted at two sites along the southeast (Tuticorin Bay) and southwest (Ashtamudi estuary) coast of India from December 1998 to January 2000. Histological evidence showed that baby clam from both the sites showed two spawning seasons. First spawning season was recorded from May to July in the southeast coast. In the southwest coast, the first spawning season was observed through March to May. A second spawning season from September to December was recorded in both the coasts. In the southeast coast, minimum and maximum condition indices were obtained in January 2000 and April 1999 respectively and decreased from May to June and November to January, signifying the two spawning periods. Most of the animals were either in spent or indeterminate gonadal stage from May to August and November to January indicating the active spawning during that months in the southeast coast.     

Effects of weaning age and diets on ontogeny of digestive activities and structures of pikeperch (<Emphasis Type="Italic">Sander lucioperca</Emphasis>) larvae

Growth and ontogeny of digestive function were studied in pikeperch (Sander lucioperca) larvae weaned on artificial food at different ages. Three weaning treatments initiated respectively on day 9 (W9), day 15 (W15) or day 21 (W21) post-hatching (p.h.) were compared with a control group, fed Artemia nauplii from first feeding until the end of the rearing trial on day 36 p.h. The digestive enzyme activities and the ontogeny of digestive structures were investigated using enzymatic assays and histological methods. Growth of pikeperch larvae was significantly affected by precocious weaning. Pancreatic (trypsin and amylase) and intestinal (leucine-alanine peptidase, leucine aminopeptidase N and alkaline phosphatase) enzyme activities were detected from hatching onwards, increased at the moment of first feeding and then decreased. Pepsin secretion occurred at day 29 p. h. only, concurrently with the stomach development and differentiation of gastric glands. In the early weaning group (W9) the maturation process of intestinal enterocytes seems to be impaired and/or delayed and several signs of malnutrition were recorded. Except for alkaline phosphatase activity, no differences in enzyme activities and development of digestive structures were observed among the control, W21, and W15 groups. Moreover, at the end of the experiment, no differences in proteolytic activities were observed among larvae from the different treatments, indicating that, in surviving individuals, the digestive structures were properly developed and the larvae had acquired an adult mode of digestion. Based on the artificial diet used, our results suggested that pikeperch larvae can be weaned from day 15 p.h. without significant adverse effect on digestive capacities (except for alkaline phosphatase) or development of digestive tract, while earlier weaning impaired the onset of the maturation processes of the digestive system, both in terms of morphological structures and enzymatic activities.     

真鲷消化道的组织学和形态学研究

采用扫描电镜和光镜技术对真鲷的消化道进行了组织学和形态学研究。具发达颌齿的口咽腔之后，真鲷消化道由分化明显的食道、胃、小肠和直肠构成。口咽腔粘膜表面为复层上皮，其中含有怀状细胞和味蕾，表层细胞具微褶（脊）；食道粘膜也衬着复层上皮，由表层具微褶（脊）的扁平细胞、中层的怀状细胞及底部的基底细胞组成，食道粘部分区域 衬着单层柱状上皮；胃Ｖ形，粘膜表层为单层柱状上皮，贲门部和盲囊部上皮下有一厚层胃腺组织；