鲻鱼早期卵子发生的超微结构研究

用电子显微镜技术观察鲻鱼早期卵子发生进入第一次成熟分裂前期联会丝复合体期、粗线期、双线期和网状期卵原细胞和初级卵母细胞生发泡和胸质的超微结构特点。在联会丝复合体期,生发泡内同源染色体配对,联会丝复合体中央出现重组节,胞质中不同发育类型的核仁样及其相关线粒体的分布及其数量可作为划分鲻鱼早期卵子发生各个时期的依据。另外,首次观察到靠近膜细胞有一种不规则形细胞,推测是分泌成熟抑制肽细胞。     

Coexistence of Mugil cephalus and M. curema in a coastal lagoon in the Gulf of Mexico

Mugil cephalus and M. curema coexist in Tamiahua Lagoon, with no difference in diet or digestive system, but with a separation of 3 months in reproductive timing.     

Mugil cephalus L.—a first British record and a further 5°N

The occurrence of a 29 mm juvenile Mugil cephalus in the Camel estuary at 50°30' N represents the first British record of this widespread tropical and subtropical species. Its origins, however, are obscure.     

盐度胁迫对鲻鱼幼鱼鳃丝Na+/K+-ATP酶活力 和体含水量的影响

研究了环境盐度急性胁迫对鲻鱼幼鱼(Mugil cephalus)鳃丝Na+/K+-ATPase(NKA)活性及体内含水量的影响.结果表明,将幼鱼从S33(盐度33)的对照组中直接转移至S0(盐度0)、S10(盐度10)、S20(盐度20)、S33和S40(盐度40)的水体中,随盐度降低各盐度处理的死亡率迅速升高.各处理...     

Effects of tail loss on the movement patterns of the lizard, Psammodromus algirus

1. Many lizards use caudal autotomy as a defensive strategy. However, subsequent costs related to the alteration of locomotor abilities might decrease the fitness of individuals. In this paper, the movement patterns of spontaneously moving Psammodromus algirus lizards and their escape performance running at high speed were compared before and after tail loss. A control tailed group was also studied to assess the repeatability of locomotor patterns between trials.
2. Tail loss had a significant effect on spontaneous movement patterns. Tailless individuals moved at significantly slower speeds during bursts of locomotion, and distances moved within bursts were significantly reduced. The overall time spent pausing increased, and, as a result, overall speeds decreased to an even greater extent than burst speeds. However, mean durations of individual locomotor bursts and mean pause durations did not change significantly after tail loss.
3. Loss of the tail decreased mean stride length, although the positive relation between stride length and speed was retained.
4. Escape performance was also greatly affected; loss of the tail resulted in substantially reduced attained, maximal and overall escape speeds. These changes resulted in shorter escape distances (the time of the first pause after the initiation of the escape response) because the mean duration of escape responses did not change.
5. The relevance of these alterations for the ecology of this species, and how individuals may compensate for the costs of tail loss, favouring autotomy as an escape strategy, are discussed.     

Effect of rearing density on the blood and tissues of mullet (Mugil cephalus L.)

This study evaluated the biological effects of high stocking density on mullet (Mugil cephalus). Fifty fish, caught from Faro lake, were divided into two groups, a low-density control group (n = 15), stocked at 3.4 kg/m³ in an 800 l tank and a high-density experimental group (n = 35), stocked at 8.4 kg/m³ an 800 l tank. The ammonia concentration in the control group tank reached 0.3 mg/l after 2 days while that in the experimental tank reached 5 mg/l. Haematological parameters and serum protein profiles were determined following blood sampling. An Unpaired T-test showed significant differences between the two groups on Red Blood Cell Count, Haematocrit, Haemoglobin, White Blood Cell Count, Mean Corpuscular Haemoglobin, Mean Corpuscular Haemoglobin Concentration, total proteins, albumin and α-globulins. In the experimental group, the disappearance of prealbumin and the γ-globulin fraction was particularly evident. Histopathological changes indicated that mucosal electrolytic failure was the main function compromised. This could eventually lead to death. The findings suggest that mullet is sensitive to stocking density linked to ammonia toxicosis.     

鲻鱼嗅囊组织形态结构观察及功能探讨

实验用鱼为全长35.5~40.0 cm的野生鲻(Mugil cephalus),采用石蜡切片以及透射电镜技术对鲻的嗅囊以及嗅板细胞进行观察。结果表明:鲻的嗅觉器官由左右两个呈扁平椭球形嗅囊构成,分别由前后两个鼻孔与外界相通。嗅囊长径与眼径之比为0.80,长径与短径之比为2.09。嗅囊的嗅轴左右两边分别有垂直于嗅轴并向上倾斜排列整齐的18~25个披针形嗅板,只有初级嗅板未见次级嗅板。嗅板由中央髓和两侧的嗅上皮两部分构成,中央髓由疏松的结缔组织和毛细血管组成。嗅上皮又分为感觉区和非感觉区,感觉区位于嗅板的内侧,具有发达纤毛,呈连续分布状态,非感觉区位于嗅板边缘,细胞纤毛较少。通过光镜和电镜的综合研究结果显示嗅上皮细胞大致可分为5类:基细胞、支持细胞、纤毛非感觉细胞、纤毛感觉细胞和柱状细胞。文章讨论了鲻的感官活动类型。     

Behavioural asymmetry affects escape performance in a teleost fish

Escape performance is fundamental for survival in fish and most other animals. While previous work has shown that both intrinsic (e.g. size, shape) and extrinsic (e.g. temperature, hypoxia) factors can affect escape performance, the possibility that behavioural asymmetry may affect timing and locomotor performance in startled fish is largely unexplored. Numerous studies have found a relationship between brain lateralization and performance in several cognitive tasks. Here, we tested the hypothesis that behavioural lateralization may affect escape performance in a teleost, the shiner perch Cymatogaster aggregata. Escape responses were elicited by mechanical stimulation and recorded using high-speed video (250 Hz). A number of performance variables were analysed, including directionality, escape latency, turning rate and distance travelled within a fixed time. A lateralization index was obtained by testing the turning preference of each subject in a detour test. While lateralization had no effect on escape directionality, strongly lateralized fish showed higher escape reactivity, i.e. shorter latencies, which were associated with higher turning rates and longer distances travelled. Therefore, lateralization is likely to result in superior ability to escape from predator attacks, since previous work has shown that escape timing, turning rate and distance travelled are among the main determinants of escape success.     

鲻和鲮鳃丝的扫描电镜比较观察

对鲻（Mugil cephalus）和鲮（Cirrhina molitorella）的鳃丝表面结构进行了扫描电镜比较观察,结果表明,鲻鳃丝杆状部比鲮粗．鲻鳃小片高度比鲮低;两者鳃丝表面分泌孔洞口径和密度不同;鲻和鲮细胞外被不同,鲻细胞外被稀疏,鲮的则致密复杂;鳃小片细胞和鳃丝表皮细胞的表面形态存在差异,文章还描述了鳃丝表皮形态特异的细胞。     

THE DISTRIBUTION AND ECOLOGY OF TWO MULLET SPECIES IN SOME FRESH WATER RIVERS IN THE EASTERN CAPE,SOUTH AFRICA

SUMMARY

Data on the relative abundance, penetration and breeding biology of the freshwater mullet Mugil cephalus and the flathead mullet Mugil cephalus in the freshwater reaches of some Eastern Cape coastal rivers are described. The differences found between the two species indicate that Myxus capensis is more specialized for a catadromous life history in an unstable riverine environment. Evidence showing the importance of the freshwater phase for the latter species is given and the disastrous effects of the erection of barriers to fish movement are stressed.     

鲻鱼甲状腺免疫组织化学与超微结构

用组织学、免疫组织化学和电镜技术对鲻鱼甲状腺的分布与形态结构进行研究。结果表明,鲻鱼甲状腺滤泡分散地分布在第1对至第3对鲻弓的入鳃动脉之间;构成同一滤泡的单层上皮细胞呈扁平形和立方形两种形态,反映出同一滤泡中上皮细胞生理活动的不同步,且发现不同发育时期的鲻鱼这两种形态细胞的比例有显著差异。用特异性甲状腺球蛋白(TG)抗体对甲状腺滤泡的免疫染色反应显示,阳性物质分布在滤泡上皮细胞的脑膜及围绕滤泡腔的周边与中央胶质,幼年与成年鲻鱼甲状腺滤泡的免疫阳性反应部位有所不同。两种不同活动状态的细胞,扁平形细胞和立方形细胞,在核与胞质的超微结构上有显著不同。扁平形细胞的核为扁平形或椭圆形,核内常染色质十分丰富,核膜光滑,核周腔和核孔没有扩张,胞质中各种细胞器发育较差;立方形细胞的核膜高度凹陷,将核分为2叶至3叶,核周腔和核孔扩张,胞质中各种细胞器发育良好,出现长棒形和哑铃形线粒体,且数量明显多于扁平形细胞,多层粗面内质网呈板层状排列,还有发育好的高尔基复合体。另外,我们还观察到一种介于扁平形细胞和立方形细胞之间的中间型细胞,其胞质和核的发育明显好于扁平形细胞,但比立方形细胞差。上述结果可为了解鲻鱼甲状腺滤泡细胞分泌活动的机制提供基础资料[动物学报49(2)：230—237,2003]。