A spontaneously occurring malignant ovarian Sertoli cell tumor in a young Sprague Dawley rat

Primary ovarian tumors are generally uncommon in rats used in toxicologic studies. A malignant Sertoli cell tumor was present in the ovary of a 19-week-old female Sprague Dawley rat. Macroscopically, the mass was white and firm, 10 × 13 × 17 mm in size, and located in the right ovary. Histopathologically, the mass was composed of nests of pleomorphic cells, which formed seminiferous-like tubules separated by a thin fibrovascular stroma. The tubules were lined by tumor cells, which had basally located nuclei and abundant eosinophilic and vacuolated cytoplasm. In some areas, the tumor cells were arranged in a retiform growth pattern, mimicking a rete testis/ovarii. Disseminated metastases to the surfaces of the mesentery, spleen and liver were also present. Immunohistochemically, many tumor cells were strongly positive for vimentin, estrogen receptor α and Ki 67. Some tumor cells were positive for pancytokeratin and inhibin α. These findings closely resemble those of an ovarian-derived human malignant Sertoli cell tumor. From our review of the literature, we believe this is the first report of a spontaneous malignant Sertoli cell tumor in the ovary of a young laboratory rat. This case might provide useful historical control information for rat toxicity studies.     

Matrix-metalloproteinases-2 and -9 production in bovine endometrial cell culture

In vitro cell culture is a convenient tool for studying cellular mechanisms. In the present study, production of matrix-metalloproteinases (MMPs) in bovine endometrial (containing both epithelial and stromal cells) monolayer cells was examined. Blastocysts attached to the endometrial cells in a monolayer culture were examined for their effects on MMP-2 production. Initial attachment of blastocysts to the monolayer inhibited MMP-2 production by endometrial cells. But once trophoblast cells began to migrate into the endometrial cell layer, MMP-2 production increased, and at the same time MMP-9 production also became evident in the medium. In order to understand how blastocysts affected MMP-2 production, we examined the effect of progesterone, estradiol, insulin-like growth factors (IGFs), tumor necrosis factors (TNFs), and interferon-tau (IFN-tau) supplementation. It was IFN-tau that inhibited the production of MMP-2. In addition, progesterone at a lower dose appeared to inhibit MMP-2 production. Both TNF-alpha and TNF-beta strongly stimulated the production of MMP-2 and MMP-9, whereas IGFs had no effect. Based on these findings, it appears that conceptus has the capacity to inhibit MMP activity.     

Appearance of race Pfs:5 of spinach downy mildew fungus, Peronospora farinosa f. sp. spinaciae, in Japan

The races for the causal agent of spinach downy mildew Peronospora farinosa f. sp. spinaciae were identified by inoculation of race-differential cultivars. One isolate was identified as Pfs:5s and the others belonged to a new race. This is the first report of race Pfs:5 and another new race in Japan.     

Preliminary experiments on mechanical stretch-induced activation of skeletal muscle satellite cells in vivo

We have shown in vitro that mechanical stretch triggers activation of quiescent satellite cells of skeletal muscle to enter the cell cycle through an intracellular cascade of events including nitric oxide (NO) synthesis that results in the release of hepatocyte growth factor (HGF) from its extracellular association and its subsequent presentation to signaling receptors. In order to explore the activation mechanism in vivo, stretch experiments were conducted in the living animal using our suspension model developed. This system used the weight of the hind portion of rats to stretch the inside muscles of the left hind limb suspended for a period of 0.5–2.0 h. At the end of the stretch period, the rats received an intraperitoneal injection of bromodeoxyuridine followed by immunocytochemistry for its incorporation as an index of satellite cell activation in vivo. Depending on the period of stretch, bromodeoxyuridine labeling was increased significantly over the contralateral unstretched leg or control muscle from untreated rats. A stretched muscle extract prepared from the 2 h stretched tissue by incubating it in PBS, showed the active form of HGF as revealed by immunoblotting and it could stimulate the activation of unstretched satellite cells. Also, administering NO synthase inhibitor L‐NAME prior to muscle stretch abolished the stretch activation of satellite cells. Therefore, the results from these experiments demonstrate that stretching muscle triggers NO synthesis and HGF release, which could activate satellite cells in vivo.     

The effect of strain, growth stage, and cultivating condition of Ganoderma lucidum on 5α-reductase inhibition

The inhibitory effects of 102 methanol extracts of 40 mycelia, 9 culture fluids, and 53 fruiting bodies of 40 strains of Ganoderma lucidum on 5-reductase were investigated. The methanol extract of the fruiting body of each strain was found to show the strongest 5-reductase inhibitory activity among the extracts tested.     

Na?ve-like conversion enhances the difference in innate in vitro differentiation capacity between rabbit ES cells and iPS cells

Quality evaluation of pluripotent stem cells using appropriate animal models needs to be improved for human regenerative medicine. Previously, we demonstrated that although the in vitro neural differentiating capacity of rabbit induced pluripotent stem cells (iPSCs) can be mitigated by improving their baseline level of pluripotency, i.e., by converting them into the so-called “naïve-like” state, the effect after such conversion of rabbit embryonic stem cells (ESCs) remains to be elucidated. Here we found that naïve-like conversion enhanced the differences in innate in vitro differentiation capacity between ESCs and iPSCs. Naïve-like rabbit ESCs exhibited several features indicating pluripotency, including the capacity for teratoma formation. They differentiated into mature oligodendrocytes much more effectively (3.3–7.2 times) than naïve-like iPSCs. This suggests an inherent variation in differentiation potential in vitro among PSC lines. When naïve-like ESCs were injected into preimplantation rabbit embryos, although they contributed efficiently to forming the inner cell mass of blastocysts, no chimeric pups were obtained. Thus, in vitro neural differentiation following naïve-like conversion is a promising option for determining the quality of PSCs without the need to demonstrate chimeric contribution. These results provide an opportunity to evaluate which pluripotent stem cells or treatments are best suited for therapeutic use.     

Growth,Reproductive Performance,Carcass Characteristics and Meat Quality in F1 and F2 Progenies of Somatic Cell-Cloned Pigs

The objective of this study was to examine the health and meat production of cloned sows and their progenies in order to demonstrate the application of somatic cell cloning to the pig industry. This study compared the growth, reproductive performance, carcass characteristics and meat quality of Landrace cloned sows, F1 progenies and F2 progenies. We measured their body weight, growth rate and feed conversion and performed a pathological analysis of their anatomy to detect abnormalities. Three of the five cloned pigs were used for a growth test. Cloned pigs grew normally and had characteristics similar to those of the control purebred Landrace pigs. Two cloned gilts were bred with a Landrace boar and used for a progeny test. F1 progenies had characteristics similar to those of the controls. Two of the F1 progeny gilts were bred with a Duroc or Large White boar and used for the progeny test. F2 progenies grew normally. There were no biological differences in growth, carcass characteristics and amino acid composition among cloned sows, F1 progenies, F2 progenies and conventional pigs. The cloned sows and F1 progenies showed normal reproductive performance. No specific abnormalities were observed by pathological analysis, with the exception of periarteritis in the F1 progenies. All pigs had a normal karyotype. These results demonstrate that cloned female pigs and their progenies have similar growth, reproductive performance and carcass quality characteristics and that somatic cell cloning could be a useful technique for conserving superior pig breeds in conventional meat production.