Expression of protein gene product 9.5 and Sal-like protein 4 in canine seminomas.

The aim of the present study was to characterize canine classical seminoma (SE) and spermatocytic seminoma (SS) by immunohistochemical expression of gonocytic and spermatogonial cellular markers (c-Kit, placental alkaline phosphatase [PLAP], protein gene product 9.5 [PGP9.5] and Sal-like protein 4 [Sall4]) and histochemically by the periodic acid-Schiff (PAS) reaction. Twenty-five cases of SE and 23 cases of SS were investigated. Two cases of dysgerminoma were also examined. c-Kit was expressed on the cell membrane of 13 of 25 cases of SE (52%) and four of 23 cases of SS (16%). This marker was not expressed in dysgerminoma. PLAP immunoreactivity was observed in the cytoplasm of neoplastic cells of six of 25 cases of SE (24%). PLAP was not expressed in cases of SS and dysgerminoma. All samples of SE, SS and dysgerminoma showed cytoplasmic expression of PGP9.5 and nuclear immunoreactivity for Sall4. There was fine granular cytoplasmic PAS staining in neoplastic cells in five of 25 cases of SE (20%), while all samples of SS and dysgerminoma cases were PAS negative. These findings suggest that it is not possible to differentiate canine SE and SS using these markers. This may be because canine SS may be derived from spermatogonia that can differentiate to spermatocytes and also because cases of canine SE might consist of neoplastic cells that have lost their gonocytic nature. This study was the first to show positive immunoreactivity for Sall4 in canine seminomas and dysgerminomas and expression of PGP9.5 in canine dysgerminomas.

A non-joint tissue biphasic synovial sarcoma in a dog.

A subcutaneous tumour was identified in the malar region of a 14-year-old neutered female mixed breed dog. The dog was humanely destroyed and necropsy examination was performed. The tumour did not invade neighbouring tissues and no metastasis was found. Microscopically, the tumour showed a range of features including the presence of multinucleated giant cells, chondrocyte differentiation and cystic or slit-like structures. All of these features are consistent with previously reported descriptions of synovial sarcomas in dogs. Mesenchymal cells accounted for the majority of the tumour, but cytokeratin-positive epithelioid components were also confirmed by immunohistochemistry. The tumour was diagnosed as a biphasic type of synovial sarcoma. Synovial sarcoma in man may develop in tissues unrelated to joints and this is the first report of a non-joint synovial sarcoma in a dog.

Phylogeny of hydrothermal-vent-endemic gastropods Alviniconcha spp. from the western Pacific revealed by mitochondrial DNA sequences.

Mitochondrial genes for cytochrome oxidase I (COI) from hydrothermal-vent-endemic gastropods of the genus Alviniconcha were sequenced to determine the phylogenetic relationships among specimens from three areas in the western Pacific. Individuals of Alviniconcha hessleri were collected at two vent fields (depths 1470 m and 3600 m) in the Mariana Trough. Specimens collected in the North Fiji Basin could be divided into two genetically distinct groups, both of which also differed from A. hessleri from the Mariana Trough. None of the specimens of the genus Alviniconcha collected in the Manus Basin differed genetically from the dominant group from the North Fiji Basin. We suggest that the specimens of the genus Alviniconcha analyzed in the present study can be tentatively classified into A. hessleri and two undescribed species.

Genetic Differentiation of Populations of a Hydrothermal Vent-Endemic Gastropod, Ifremeria nautilei, between the North Fiji Basin and the Manus Basin revealed by Nucleotide Sequences of Mitochondrial DNA.

The genetic differentiation of populations of a hydrothermal vent-endemic gastropod, Ifremeria nautilei, between two back-arc basins in the south Western Pacific, namely the Manus Basin and the North Fiji Basin, was analyzed on the basis of nucleotide sequences of the mitochondrial gene for cytochrome oxidase I. The two populations of I. nautilei had no common haplotypes and appeared, therefore, to be isolated from one another. All haplotypes obtained from the North Fiji Basin formed a monophyletic group supported by a high bootstrap probability and the genetic diversity of the population in the North Fiji Basin was much smaller than that of the population in the Manus Basin. The population in the North Fiji Basin might have been founded by relatively recent migrants from the Manus Basin. The present results suggest that the larval dispersal ability of I. nautilei might be lower than that of an undescribed species in the closely related genus Alviniconchay.

Evolution of pulmonate gastropod mitochondrial genomes: comparisons of gene organizations of Euhadra, Cepaea and Albinaria and implications of unusual tRNA secondary structures.

Complete gene organizations of the mitochondrial genomes of three pulmonate gastropods, Euhadra herklotsi, Cepaea nemoralis and Albinaria coerulea, permit comparisons of their gene organizations. Euhadra and Cepaea are classified in the same superfamily, Helicoidea, yet they show several differences in the order of tRNA and protein coding genes. Albinaria is distantly related to the other two genera but shares the same gene order in one part of its mitochondrial genome with Euhadra and in another part with Cepaea. Despite their small size (14.1-14.5 kbp), these snail mtDNAs encode 13 protein genes, two rRNA genes and at least 22 tRNA genes. These genomes exhibit several unusual or unique features compared to other published metazoan mitochondrial genomes, including those of other molluscs. Several tRNAs predicted from the DNA sequences possess bizarre structures lacking either the T stem or the D stem, similar to the situation seen in nematode mt-tRNAs. The acceptor stems of many tRNAs show a considerable number of mismatched basepairs, indicating that the RNA editing process recently demonstrated in Euhadra is widespread in the pulmonate gastropods. Strong selection acting on mitochondrial genomes of these animals would have resulted in frequent occurrence of the mismatched basepairs in regions of overlapping genes.