Identification of Genes Directly Involved in Shell Formation and Their Functions in Pearl Oyster, Pinctada fucata

Mollusk shell formation is a fascinating aspect of biomineralization research. Shell matrix proteins play crucial roles in the control of calcium carbonate crystallization during shell formation in the pearl oyster, Pinctada fucata. Characterization of biomineralization-related genes during larval development could enhance our understanding of shell formation. Genes involved in shell biomineralization were isolated by constructing three suppression subtractive hybridization (SSH) libraries that represented genes expressed at key points during larval shell formation. A total of 2,923 ESTs from these libraries were sequenced and gave 990 unigenes. Unigenes coding for secreted proteins and proteins with tandem-arranged repeat units were screened in the three SSH libraries. A set of sequences coding for genes involved in shell formation was obtained. RT-PCR and in situ hybridization assays were carried out on five genes to investigate their spatial expression in several tissues, especially the mantle tissue. They all showed a different expression pattern from known biomineralization-related genes. Inhibition of the five genes by RNA interference resulted in different defects of the nacreous layer, indicating that they all were involved in aragonite crystallization. Intriguingly, one gene (UD_Cluster94.seq.Singlet1) was restricted to the ‘aragonitic line’. The current data has yielded for the first time, to our knowledge, a suite of biomineralization-related genes active during the developmental stages of P.fucata, five of which were responsible for nacreous layer formation. This provides a useful starting point for isolating new genes involved in shell formation. The effects of genes on the formation of the ‘aragonitic line’, and other areas of the nacreous layer, suggests a different control mechanism for aragonite crystallization initiation from that of mature aragonite growth

育仔放棄されたネズミイルカの初乳の成分分析と人工哺育の試み

The harbor porpoise is a marine mammal rarely seen in aquariums. The ecology of this species is not well known, and captive breeding is difficult without essential information such as milk composition, amount consumed and frequency nursed per day, and lactation period. At the Otaru Aquarium in Japan, several deliveries of harbor porpoise offspring have occurred, but the calves have not survived. In the present study, we analyzed the colostrum of a harbor porpoise and attempted to hand-rear a calf using artificial milk after the mother denied nursing. The crude fat and crude protein contents of the colostrum were relatively high compared to values for other odontocetes. The present information will be helpful for future efforts to hand-rear harbor porpoises.本研究では，おたる水族館で育仔放棄されたネズミイルカ幼獣の人工哺育を試みた。生後14日で幼獣は死亡したが，母獣から貴重な初乳を得た。ハクジラ類の中でも本種は授乳期間が短いが，成分分析の結果，その初乳には粗脂肪と粗蛋白質が豊富に含まれていた

Survey of ophthalmic disorders among captive pinnipeds in Japan

Pinnipeds have evolved enlarged ocular bulbs to catch fish in the dark. However, their large protruding eyes are easily damaged, which increases the risk of blindness and death in these animals. In captivity, ophthalmic disorders, manifested as keratitis and cataracts, are common among pinnipeds. In this study, we investigated symptoms of ophthalmic disorders in pinniped species using a questionnaire distributed to 32 zoos and aquariums throughout Japan. We conducted this study in cooperation with the Japanese Association of Zoos and Aquariums. The survey included 295 pinnipeds from four otariid species, five phocid species, and one odobenid species. Of these, 43.1% of the pinnipeds had diseases affecting the lens, cornea, and/or other eye parts. Age was positively associated with lens disorders in California sea lions, South American sea lions, and spotted seals. Conflicts and public appearances were also associated with corneal and/or lens disorders in California sea lions. Treatments were evaluated as effective for corneal disorders and conjunctivitis. The results of this study indicate that ophthalmic disorders in pinnipeds are related to the conditions of their captive environment. Aquariums and zoos should be encouraged to share information regarding optimal maintenance practices to improve the living conditions of pinnipeds