No abstract

Three major organic matrix components, nacrein, MSI60 and N16 have been reported from the nacreous layer of Japanese pearl oyster, Pinctada fucata. Though several in vitro experiments have been carried out to elucidate the functions of these molecules details have not yet been clarified. In this report, we tempt to clarify the gene expression levels encoding the above three proteins between samples of 1) summer and winter seasons and 2) ocean and aquarium environments by using realtime polymerase chain reaction (PCR).It was confirmed that the biomineralization process of P. fucata is mainly influenced by the circatidal rhythm of the ocean environment. The gene expressions coding for N16 and MSI60 increased at the time of high tide, while that of nacrein increased at the time of low tide. The similar tendency observed in N16 and MSI60 showed the possibility that both components are secreted simultaneously, supporting a hypothesis that N16 forms crosslinkage with MSI60 to form the membrane. The expressions of MSI60, N16 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were remarkable in winter season, while no variation was found in the expression level of the nacrein gene in summer and winter season.The study is the first attempt regarding the seasonal and circadian rhythms observed on gene expressions incorporated into molluscan shell formation. The results will give a new insight into the relationship between molluscan physiology and the mechanism of shell formation.

We prepared a map of the cleavage lines for beagle dogs, as a guideline for use of cleavage lines in dermatoplasty. The cleavage lines at the head resembled the orientation of the underlying muscles. Although the cleavage lines in the trunk were perpendicular to the body axis, those in the thoraco-abdominal region were parallel to the body axis. The cleavage lines at the limbs were parallel to the long axis of the limb on the cranial surface, but were perpendicular to the long axis of the limb on the lateral and caudal surfaces. Also, we recorded in detail the cleavage lines in the distal regions of the limbs.