异种嫁接的水螅畸形体初步观察

把强壮水螅(Hydra robusta)和普通水螅(H.vulgaris)除头后进行异种切口嫁接实验,共获得3例畸形体,对其进行280 d的培养,获得78只畸形子代。追踪观察发现:①畸形体及其无性生殖子代均具有2种钩刺丝囊(强壮水螅钩刺丝囊和普通水螅钩刺丝囊);②其身体伸展时最长达52 mm;③无性出芽生殖的平均生殖周期10 d以上;④个体无性生殖3～8代后凋亡;⑤触手数为4、5和6条的个体分别占80%、10%和10%;⑥不发生有性生殖;⑦切割再生时间长,再生后形态与发育特性同术前个体;⑧外胚层表面出现增生组织,这些增生组织在体柱上发生凋亡或脱离母体后1～2 d解体;内胚层上常有细胞团块脱离身体,进入消化腔。来源于异种水螅嫁接的畸形体上出现的组织增生、细胞脱落等现象揭示了水螅可能具备识别和排斥异种组织的原始免疫机制。

说说鲫鱼

鲫鱼,又叫鲫瓜子,雌性的特别多,生活在淡水里,体形扁宽,秋、春季肥硕。其肉质鲜嫩、营养丰富,秋季孕籽,立夏前后产卵,再体外受精。生活在水温过低或盐分高的水域,产卵时间拖延。一年大部分时间,雌鱼都挺着大肚子,被戏称＂鲫鱼大嫂。＂蓟运河汉沽段两岸,坐落有汉沽农场、清河农场、芦台农场、八一盐场,有大面积的水面供养着鲫鱼的生长。曾经还有桥沽、茶淀、大田、杨家泊四个农村公社,村落多,坑塘淀洼多,水源丰富。

Morphological Deformities in the Wild Population of C. gariepinus in Ado-Ekiti, Nigeria

Clarias ganepinus from wild population, which was purchased from fish mongers in Ado-Ekiti, Nigeria, were examined for possible deformities in their body. Eighty individuals were collected. Various types of deformities observed were recorded and later photographed. The present study reported for the first time the occurrence of morphological deformities in C. gariepinus natural ecosystem in Ado-Ekiti, Nigeria. The rivers, where the fish were collected, were found to have been exposed to persistent human activities. The possible causes of the deformities may be pollution from human activities or other factors such as poor nutrition, heredity, diseases. The etiology of the deformities in Clarias under this condition is recommended to be studied in detail.

双头无基盘水螅的初步观察

自然形成的双头无基盘畸形体水螅极为罕见，为探索其形成原因，人工嫁接水螅14例，获得5例相同的双头水螅。对其分别进行连续观察发现：嫁接的双头水螅的双头可同时摄食，食物集聚于1个胃区。随个体生长其体柱延长，逐渐发育为2个胃区，在2个胃区间发生2～6个芽体，所有子代发育正常。出芽位置至触手环的距离同正常水螅。之后分化为2个出芽区，出芽区之间体柱较透明，同茎区组织。第21天开始发生基盘，发生过程异常缓慢。