A xenograft mantle transplantation technique for producing a novel pearl in an akoya oyster host.

The brightness and color of pearls varies among different pearl-producing shellfish and have been a source of human fascination since ancient times. When produced through cultivation, the characteristics and quality of a pearl depend on the kind of shellfish used and also the transplanted mantle graft. This suggests that the Akoya pearl oyster, which is generally used in Japan for pearl culturing, can produce different kinds of pearl through the use of mantles from different species of shellfish.

Proliferating spermatogonia are susceptible to reactive oxygen species attack in Japanese eel (Anguilla japonica).

Oxidative stress has been implicated in pathogenesis of many diseases, but few studies describe its influence on spermatogenesis. In this study, we analyzed the direct influence of hypoxanthine (Hx)-induced reactive oxygen species (ROS) on spermatogenesis in fish using the Japanese eel (Anguilla japonica) testicular organ culture system. Testicular fragments of eels were cultured in 0.

Taurine plays an important role in the protection of spermatogonia from oxidative stress.

It has been demonstrated that taurine has various physiological functions in the body. We demonstrated that taurine is abundant in the serum, liver, muscle and testis of the Japanese eel (Anguilla japonica). In the eel testis, taurine is found mainly in spermatogonia and is weakly expressed also in the Sertoli cells.

The synthesis and role of taurine in the Japanese eel testis.

In teleost fish, the progestin 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) is an essential component of the spermatogenesis pathway. In a series of investigations on the mechanisms underlying progestin-stimulated spermatogenesis, we have found that DHP up-regulates the expression of cysteine dioxygenase1 (CDO1) in the Japanese eel testis. CDO1 is one of the enzymes involved in the taurine biosynthesis pathway.

Tolerance of spermatogonia to oxidative stress is due to high levels of Zn and Cu/Zn superoxide dismutase.

Background: Spermatogonia are highly tolerant to reactive oxygen species (ROS) attack while advanced-stage germ cells such as spermatozoa are much more susceptible, but the precise reason for this variation in ROS tolerance remains unknown.

Methodology/principal Findings: Using the Japanese eel testicular culture system that enables a complete spermatogenesis in vitro, we report that advanced-stage germ cells undergo intense apoptosis and exhibit strong signal for 8-hydroxy-2'-deoxyguanosine, an oxidative DNA damage marker, upon exposure to hypoxanthine-generated ROS while spermatogonia remain unaltered. Activity assay of antioxidant enzyme, superoxide dismutase (SOD) and Western blot analysis using an anti-Copper/Zinc (Cu/Zn) SOD antibody showed a high SOD activity and Cu/Zn SOD protein concentration during early spermatogenesis.

Zinc is an essential trace element for spermatogenesis.

Zinc (Zn) plays important roles in various biological activities but there is little available information regarding its functions in spermatogenesis. In our current study, we further examined the role of Zn during spermatogenesis in the Japanese eel (Anguilla japonica). Human CG (hCG) was injected into the animals to induce spermatogenesis, after which the concentration of Zn in the testis increased in tandem with the progression of spermatogenesis.

Arsenic inhibits in vitro spermatogenesis and induces germ cell apoptosis in Japanese eel (Anguilla japonica).

The precise mechanism and direct effects of arsenic on fish, particularly in reproduction, are not well clarified. The aim of this study is to investigate the direct influence of arsenic on fish spermatogenesis using the Japanese eel (Anguilla japonica) in vitro testicular organ culture system. Eel testicular fragments were cultured in vitro with 0.

Effects of arsenic on gonadal development in freshwater crab, Somanniathelphusa pax, in Vietnam and Geothelphusa dehaani in Japan.

To estimate the influence of water contamination by arsenic (As) on reproduction of crustaceans in Vietnam, we collected wild freshwater crab Somanniathelphusa pax from the Mekong Delta area in Vietnam, investigated gonadal development, and measured As concentration in hepatopancreas. In female crab, vitellogenesis was delayed in association with the increase of As accumulation in hepatopancreas, whereas there was no significant correlation between testicular development and As accumulation in male crab. To clarify the effects of As on gonadal development of crustaceans, we investigated the effects of oral As administration on gonadal development in Japanese freshwater crab Geothelphusa dehaani.