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Yamaguchi S.,Kanagawa University | Higashiji T.,Okinawa Churashima Foundation | Sawada K.,Graduate University for Advanced Studies | Yamato S.,Kyoto University
Marine Biodiversity Records | Year: 2014

The specimens of Paralepas maculata on a sea urchin, Prionocidaris sp. were collected in Okinawa, southern Japan. This species has not been reported since its original description. This represents the first observation of this species from Okinawa and the first instance found on this sea urchin species. In this paper, the morphology of the new P. maculata specimens is reported, and compared with the type series of this species. Small individuals were found on the holotype. The probable androdioecious sexual system of the species, which includes dwarf-male like individuals and hermaphrodites, is discussed. This study was facilitated by the collaboration of scientists and aquarium staff, suggesting the potential of such collaborations in biodiversity studies. © Marine Biological Association of the United Kingdom, 2014. Source

Takatsu K.,University of Shizuoka | Miyaoku K.,University of Shizuoka | Roy S.R.,University of Shizuoka | Murono Y.,University of Shizuoka | And 4 more authors.
Scientific Reports | Year: 2013

This study investigated whether undifferentiated germ and/or somatic stem cells remain in the differentiated ovary of a species that does not undergo sex changes under natural conditions and retain their sexual plasticity. The effect of aromatase inhibitor (AI)-treatment on sexually mature female zebrafish was examined. A 5-month AI treatment caused retraction of the ovaries after which testes-like organs appeared, and cyst structures filled with spermatozoa-like cells were observed in sections of these tissues. Electron microscopic observations revealed that these cells appeared as large sperm heads without tails. Sperm formation was re-examined after changing the diet to an AI-free food. A large number of normal sperm were obtained after eight weeks, and no formation of ovarian tissue was observed. Artificial fertilization using sperm from the sex-changed females was successful. These results demonstrated that sex plasticity remains in the mature ovaries of this species. Source

Kawazu I.,Okinawa Churashima Foundation | Nakada K.,Rakuno Gakuen University | Maeda K.,Okinawa Churashima Foundation | Sawamukai Y.,Yokoo Veterinary Clinic
Current Herpetology | Year: 2016

Blood levels of progesterone (P4), estradiol-17β (E2), calcium (Ca), triglyceride (TG), and total protein (TP) were monitored in a captive female loggerhead turtle throughout a nesting season that included three 13-or 14-d internesting intervals. We observed the turtle's ovaries to monitor the appearance of shelled eggs, using ultrasonography, and compared the results of blood analyses and ovary observations. The blood P4 level remained low (<0.2 ng/mL), with the exception of three sharp peaks (1.7, 2.2, and 4.2 ng/ mL) immediately after the initial three nestings. Eggshell formation occurred immediately after the P4 peaks. The blood Ca level gradually dropped to approximately 3.0 μmol/mL during each eggshell formation period but then recovered to approximately 3.7 μmol/mL prior to the next eggshell formation. The blood E2 level fluctuated between 44 and 299 pg/mL, but with two higher peaks (734 and 419 pg/mL) after eggshell formation in the first and second internesting intervals, respectively. During the nesting season, the blood TG level (initially 20 μmol/mL) showed a stepwise drop to 7.6 μmol/mL, while the blood TP level fluctuated between 57 and 69 mg/mL with no distinct peaks. The periodic cycle of P4 and Ca changes aligned with albumen layer secretion around ovulated follicles immediately after nesting, followed by eggshell c alcification i n t he c lutch. T he r elatively small fl uctuations i n E2, TG, and TP during the nesting season suggested that lipid deposition and preovulatory follicular development were completed prior to the start of nesting. Source

Miyamoto K.,Okinawa Churashima Foundation | Nonaka A.,Smithsonian Institution | Oka S.-I.,Okinawa Churashima Foundation
Zootaxa | Year: 2015

We describe 5 specimens of Choerodon margaritiferus Fowler and Bean, 1928 (94.5-107.0 mm standard length, 1 male and 4 females) collected near Okinawa Island, southern Japan. This is the northernmost record of this species and the first record of it in Japanese waters; until now, C. margaritiferus was recorded only from the western central Pacific. This species was originally described on the basis of 1 male specimen, and all additional specimens described in the literature were also male. Morphological characters of both sexes are described, and new diagnostic characters of the female are presented. © 2015 Magnolia Press. Source

Oka S.-I.,Okinawa Churashima Foundation | Odoriba S.,Okinawa Churashima Foundation
Ichthyological Research | Year: 2014

Larvae and juveniles of Alectis indica reared in captivity are described based on 47 specimens (3.2-32.0 mm in body length: BL). Development was typical for the tribe Carangini except for the presence of elongated fin filaments. Elongated dorsal-fin filaments were present at preflexion (3.2 mm BL). During flexion, the anal- and pelvic-fin rays elongated and the body deepened. The full complement of fin spines and rays was present by 7.1 mm BL. The larvae of A. indica could be differentiated from those of Alectis ciliaris, which also inhabits in the Indo-Pacific waters, by the presence of a ventral series of melanophores on the tail, elongated pelvic fins, and the timing of anal-fin spine migration. The rounded body and elongated fin rays of A. indica cause it to resemble venomous Cubomedusae. © 2014 The Ichthyological Society of Japan. Source

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