Mitochondrial Genes Collectively Suggest the Paraphyly of Crustacea with Respect to Insecta

Complete sequences of seven protein coding genes from Penaeus notialis mitochondrial DNA were compared in base composition and codon usage with homologous genes from Artemia franciscana and four insects. The crustacean genes are significantly less A + T-rich than their counterpart in insects and the pattern of codon usage (ratio of G + C-rich versus A + T-rich codon) is less biased. A phylogenetic analysis using amino acid sequences of the seven corresponding polypeptides supports a sister-taxon status for mollusks–annelid and arthropods. Furthermore, a distance matrix-based tree and two most-parsimonious trees both suggest that crustaceans are paraphyletic with respect to insects. This is also supported by the inclusion of Panulirus argus COII (complete) and COI and COIII (partial) sequence data. From analysis of single and combined genes to infer phylogenies, it is observed that obtained from single genes are not well supported in most topologies cases and notably differ from that of the tree based on all seven genes. Received: 25 August 1998 / Accepted: 8 March 1999     

Amputation‐induced activity of progenitor cells leads to rapid regeneration of olfactory tissue in lobsters

Lobsters have a self‐renewing olfactory system and, like many animals, continuously replace old or dying olfactory receptor neurons. In addition, lobsters are able to regenerate the peripheral olfactory system even after complete loss. The olfactory sensors in lobsters are located distally on a pair of antennules. These antennules are often damaged, but this has little impact on the lobster's sense of smell because damaged olfactory tissue is rapidly replaced. In this study, we investigated damage‐induced regeneration of the olfactory system by measuring cell proliferation following controlled amputation. We show that amputation‐induced regeneration occurs as a result of up‐regulating the normal development of olfactory sensors. A unique feature of up‐regulated development is the formation of patches of proliferating cells within the antennular epithelium. Epithelial patches were typically formed between 3 and 10 days postamputation on the amputated side. They were characterized by their: proximal position with respect to developing clusters of olfactory receptor neurons (ORNs); tendency to form two discrete patches within the borders of each existing annulus; cell size, which was approximately twice that of mature ORNs; and location within the ventral epithelium. The development of epithelial patches was immediately followed by proliferation of clusters of ORNs and associated glial cells, and the level of this proliferation increased significantly during the premolt stage of the lobster's molt cycle. These epithelial patches may represent populations of precursor cells, because they develop in response to amputation and immediately precede development of cell clusters composed of ORNs and glia. Possible regulatory signals controlling epithelial patch development are discussed. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 97–114, 2003     

pH值对中国龙虾消化酶活力的影响

采用酶学分析方法研究了pH对中国龙虾胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶活力的影响。结果表明,在设定的pH范围内,中国龙虾各消化酶的活力均随着pH的升高呈现先升后降的变化趋势。其中,胃、肠、肝胰腺内胃蛋白酶最适pH均为2.2,类胰蛋白酶最适pH分别为8.8-9.2、8.4、8.8,淀粉酶最适pH分别为7.0、7.0、7.4,纤维素酶最适pH分别为4.2、4.2-4.6、5.4,脂肪酶最适pH分别为7.2-7.6、7.2、6.8-7.2。同时测得中国龙虾胃、肠、肝胰腺内的生理pH分别为5.33、6.93、6.60。中国龙虾的消化酶活力存在器官特异性。在最适pH下,胃蛋白酶活力顺序为胃>肠>肝胰腺,类胰蛋白酶、纤维素酶、脂肪酶的活力顺序均为肝胰腺>肠>胃,淀粉酶的活力顺序为肠>肝胰腺>胃。     

锦绣龙虾人工繁殖和胚胎发育的研究

锦绣龙虾(Panulirus ornatus)是世界名贵的经济虾类, 也是我国捕捞和养殖的大型虾类, 但资源匮乏,育苗还没有取得成功, 因此, 需要开展人工繁殖研究以保护和增殖资源。实验用人工养殖26 月龄的锦绣龙虾进行人工繁殖和胚胎发育研究, 结果表明, 锦绣龙虾在5 个月内繁殖2 次。切除锦绣龙虾单侧眼柄能加速其性腺发育, 在第一和第二次繁殖中, 切除眼柄的雌龙虾比对照组的卵巢成熟时间分别缩短17.7d 和11.3d。锦绣龙虾在交配后1—10d 内产卵。锦绣龙虾切除眼柄与否对怀卵量没有显著影响。第一、二次繁殖平均产卵量分别为40.34×104 粒和32.97×104 粒, 平均孵化率分别为77.29%和77.72%, 孵化出叶状幼体平均数量分别为31.38×104/尾和25.62×104/尾。锦绣龙虾的胚胎发育分为11 个时期: 受精卵、卵裂期、囊胚期、原肠期、膜内无节幼体期、七对附肢期、九对附肢期、十一对附肢期、复眼色素形成期、准备孵化期和孵化期。在水温29.2℃, 盐度30, 受精卵经22—23d 孵化出叶状幼体。       

A re-evaluation of the cytology of cat Pacinian corpuscles

Summary The aesthetascs of the spiny lobster, Panulirus argus, are hair sensilla located on the lateral filaments of the antennules. Each hair is about 0.8 mm long and innervated by about 320 bipolar sensory neurons, the dendrites of which project as a bundle into the hair shaft. Each of the dendrites develops two cilia. Within a very short distance each of these cilia branches repetitively and dichotomously resulting in 8000 to 10000 outer dendritic segments per hair, or about 20 to 30 branches per neuron. The branches intertwine frequently before running to the tip of the hair. Each hair also possesses inner and outer auxiliary cells. The inner auxiliary cells surround the bundle of dendrites, extending distally to the origin of the ciliary segments. Extensions of these cells project into the bundle of dendrites, separating groups of dendrites into discrete clusters. Outer auxiliary cells wrap the inner ones, but do not extend beyond the base of the hair.     

An evaluation of lipid‐ and morphometric‐based indices of nutritional condition for early benthic stage spiny lobsters,Panulirus argus

Assessing the nutritional condition of field‐caught animals has obvious ecological utility, but few indices of condition have been developed for spiny lobsters. We evaluated two potential indices of nutritional condition for the Caribbean spiny lobster, Panulirus argus, using early benthic stage lobsters maintained in the laboratory on two food treatments (100% and 25% of maximum daily consumption) for four months. Every two weeks, we sampled lobsters to ascertain their condition using both a weight/carapace length ratio and triacylglycerol/bodyweight ratio. Triacylglycerol (TAG) content in the hepatopancreas, abdominal, and periopod tissue was determined using thin‐layer chromatography‐flame ionization detection. There was a significant difference in both carapace length and weight of lobsters in the two experimental treatments through time, confirming that our feeding treatments created a detectable difference in growth. We also found a corresponding significant difference between treatments for the weight/carapace length ratio, but the TAG/bodyweight ratio did not differ between treatments, and the variance among individuals was high.