点纹斑竹鲨晚期胚胎侧线系统的研究

通过阿利新蓝染色、石蜡切片和扫描电镜,对点纹斑竹鲨晚期胚胎侧线系统的分布、形态和表面结构进行了观察。结果表明,点纹斑竹鲨的侧线系统与多数软骨鱼板鳃类相一致,包括有机械感受功能的侧线管和陷器,以及有电感受功能的罗伦氏壶腹器。侧线管分布呈典型的“七管模式”,其内的管道神经丘位于侧线管内远离体表的一侧,由覆盖细胞、支持细胞和感觉细胞组成。陷器分布于背部两体侧线管之间,单个陷器位于两盾鳞间,深陷在真皮中,由1短管通向表面,管壁不规则,上段由表皮细胞组成,管深40~60 μm。罗伦氏壶腹器由管孔、罗伦管和罗伦瓮3部分组成,呈长颈瓶状,很多罗伦管都较长,从1 mm~50 mm 不等,管壁规则;罗伦瓮由7个罗伦小囊组成,每个小囊直径约50 μm。通过与其他软骨鱼类进行比较,点纹斑竹鲨的侧线系统分布和感受器结构不但印证了软骨鱼类的系统发育关系,同时也与其生活习性相适应。     

Fine structure of the canal neuromasts of the lateral line system in the adult zebrafish

The mechanosensory lateral line system of fish is responsible for several functions such as balance, hearing, and orientation in water flow and is formed by neuromast receptor organs distributed on head, trunk and tail. Superficial and canal neuromasts can be distinguished for localization and morphological differences. Several information is present regarding the superficial neuromasts of zebrafish and other teleosts especially during larval and juvenile stages, while not as numerous data are so far available about the ultrastructural characteristics of the canal neuromasts in adult zebrafish. Therefore, the aim of this study was to investigate by transmission electron microscopy the ultrastructural aspects of cells present in the canal neuromasts. Besides the typical cellular aspects of the neuromast, different cellular types of hair cells were observed that could be identified as developing hair cells during the physiological turnover. The knowledge of the observed cellular types of the canal neuromasts and their origin could give a contribution to studies carried out on adult zebrafish used as model in neurological and non‐neurological damages, such as deafness and vestibular disorders.     

Exquisite structure of the lateral line system in eyeless cavefish Sinocyclocheilus tianlinensis contrast to eyed Sinocyclocheilus macrophthalmus (Cypriniformes: Cyprinidae)

In this study, the lateral line systems in Chinese cavefish eyeless Sinocyclocheilus tianlinensis and eyed Sinocyclocheilus macrophthalmus were investigated to reveal their morphological changes to survive in harsh environments. Compared with the eyed cavefish S. macrophthalmus (atypical), the lateral line system in the eyeless cavefish S. tianlinensis (typical) has certain features to adapt to the dark cave environments: the superficial lateral line system in the eyeless species possesses a higher number of superficial neuromasts and more hair cells within an individual neuromast, and the trunk lateral line canal system in S. tianlinensis exhibits larger canal pores, higher canal diameter and more pronounced constrictions. Fluid–structure interaction analysis suggested that the trunk lateral line canal system in the eyeless S. tianlinensis should be more sensitive than that in the eyed S. macrophthalmus. These morphological features of the lateral line system in the eyeless S. tianlinensis probably enhance the functioning of the lateral line system and compensate for the lack of eyes. The revelation of the form–function relationship in the cavefish lateral line system provides inspiration for the design of sensitive artificial flow sensors.     

Eya1-Six1信号在斑马鱼侧线神经丘毛细胞再生过程中的表达

机械感觉毛细胞对于脊椎动物的听力和平衡能力至关重要,低等脊椎动物毛细胞在遭受损伤后具有很强的再生能力。鱼类侧线神经丘毛细胞与内耳毛细胞具有相似的结构、功能、发育和再生过程。我们将受精后5~6 d的斑马鱼仔鱼置于400 μmol/L新霉素溶液中处理1 h破坏神经丘毛细胞。分别对处理后2、4、8、12及24 h的斑马鱼仔鱼进行组织学切片及功能基因eya1和six1b的整体原位杂交。组织学切片结果显示：对照组神经丘毛细胞与支持细胞形态及排布都很规则,毛细胞和支持细胞分别位于上层和下层;处理后2~4 h,上层毛细胞数量显著下降;处理后8~12 h,支持细胞和毛细胞之间界限模糊,部分支持细胞变长,且与基膜脱离;处理后24 h,部分神经丘内毛细胞及支持细胞数量、形态及排布接近对照组水平。整体原位杂交结果显示：eya1和six1b在对照组斑马鱼仔鱼整个神经丘都有表达;处理后4 h内神经丘中央毛细胞中eya1和six1b的表达量显著下降,周围的支持细胞中仍保持一定量的表达;这两个基因的表达量从处理后8 h起逐渐提高,在处理后12~24 h恢复甚至超过对照组。综上结果表明：神经丘毛细胞再生过程中可能有支持细胞的参与,且重启了神经丘毛细胞发育过程中的功能基因eya1和six1b。     

Chronic ulcerative dermatopathy in cultured marine fishes. Comparative study in sharpsnout sea bream, Diplodus puntazzo (Walbaum)

Chronic ulcerative dermatopathy (CUD) also known as chronic erosive dermatopathy, hole-in-the-head, head and lateral line erosion syndrome (HLLE) and lateral line depigmentation (LLD) is a chronic disease of unknown aetiology that affects the lateral line canals of the head and the trunk of various fish species. It has been described only in freshwater species although there are reports that it also affects marine fish. Here, we describe the disease in cultured sharpsnout sea bream using histology and scanning electron microscopy and identify several marine species as CUD sensitive. The results of this study correlate the development of the disease with the use of borehole water, indicating that the aetiology is probably associated with water quality rather than nutritional imbalance or infectious agents.