Annual reproductive cycle of the Japanese holothurian Eupentacta chronhjelmi

1994 ◽  
Vol 72 (3) ◽  
pp. 387-396 ◽  
Author(s):  
Maria Antonina B. Catalan ◽  
Masamichi Yamamoto
Keyword(s):  
Reproductive Cycle ◽  
Wall Thickness ◽  
Histological Analysis ◽  
Seawater Temperature ◽  
Annual Reproductive Cycle ◽  
Index Method ◽  
Ambient Seawater ◽  
The Seto Inland Sea ◽  
Gonadal Index ◽  
Inland Sea Of Japan

The reproductive cycle of the small temperate dendrochirote holothurian Eupentacta chronhjelmi was studied in the intertidal zone of Aoshima Island, in the Seto Inland Sea of Japan, from July 1989 to January 1991. Reproductive status was assessed by the gonadal index method and histological analysis of the largest (tertiary) gonadal tubules. The primary and secondary tubules are cryptic and difficult to find, so no reference to the animal's annual cycle in terms of gametogenesis is made. The gonad wall was thickest in September for females and October for males, when the gonadal index was at its peak the rapid final stages of vitellogenesis in females (and completion of spermatogenesis in males) depleted reserves in the gonad wall, producing gametes that were spawned in October to December. When gametes were spawned in December the gonadal index and gonad wall thickness decreased. We suggest that the gonadal index reflects gonadal growth by oocyte production and an increase in gonad wall thickness. In the laboratory, spawning occurred from midnight to 04:00, at ambient seawater temperature (12 °C). Individuals elevated their anterior, oral end, waved their tentacles, and released gametes for about an hour. Based on its large egg size (300 ± 5 μm (mean ± SE) diameter) and low fecundity (1500 ± 10 ripe oocytes per individual), we infer lecithotropic development with an abbreviated larval stage.

Mechanisms underlying pituitary microvascular remodelling in thoroughbred horses during the annual reproductive cycle

2014 ◽  
Author(s):  
Angus Yeomans ◽  
Nichol Thompson ◽  
Jennifer Castle-Miller ◽  
David O Bates ◽  
Domingo Tortonese
Keyword(s):  
Reproductive Cycle ◽  
Annual Reproductive Cycle ◽  
Thoroughbred Horses

scholarly journals Proliferative and Apoptotic Pathways in the Testis of Quail Coturnix coturnix during the Seasonal Reproductive Cycle

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1729
Author(s):  
Sara Falvo ◽  
Luigi Rosati ◽  
Maria Maddalena Di Fiore ◽  
Federica Di Giacomo Russo ◽  
Gabriella Chieffi Baccari ◽  
...  
Keyword(s):  
Reproductive Cycle ◽  
Second Messengers ◽  
Reproductive Period ◽  
Annual Reproductive Cycle ◽  
Coturnix Coturnix ◽  
Immunohistochemistry Analysis ◽  
17Β Estradiol ◽  
Apoptotic Pathways ◽  
Camp And Cgmp ◽  
Activation Phase

The quail Coturnix coturnix is a seasonal breeding species, with the annual reproductive cycle of its testes comprising an activation phase and a regression phase. Our previous results have proven that the testicular levels of both 17β-estradiol (E2) and androgens are higher during the reproductive period compared to the non-reproductive period, which led us to hypothesize that estrogens and androgens may act synergistically to initiate spermatogenesis. The present study was, therefore, aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasonality, with a focus on the molecular pathways elicited in both active and regressive quail testes. Western blotting and immunohistochemistry analysis revealed that the expression of ERα, which is the predominant form of estrogen receptors in quail testis, was correlated with E2 concentration, suggesting that increased levels of E2-induced ERα could play a key role in the resumption of spermatogenesis during the reproductive period, when both PCNA and SYCP3, the mitotic and meiotic markers, respectively, were also increased. In the reproductive period we also found the activation of the ERK1/2 and Akt-1 kinase pathways and an increase in second messengers cAMP and cGMP levels. In the non-reproductive phase, when the E2/ERα levels were low, the inactivation of ERK1/2 and Akt-1 pathways favored apoptotic events due to an increase in the levels of Bax and cytochrome C, with a consequent regression of the gonad.

Annual reproductive cycle of the greasyback shrimp Metapenaeus ensis in Ise Bay, Japan

2021 ◽  
Author(s):  
Fumihiro Yamane ◽  
Katsuyoshi Suitoh ◽  
Takuji Okumura ◽  
Kenji Toyota ◽  
Naoaki Tsutsui ◽  
...  
Keyword(s):  
Reproductive Cycle ◽  
Annual Reproductive Cycle ◽  
Metapenaeus Ensis ◽  
Ise Bay

Changes in Proto-oncogene Activity in the Testis of the Frog, Rana esculenta, during the Annual Reproductive Cycle

1995 ◽  
Vol 99 (2) ◽  
pp. 127-136 ◽  
Author(s):  
Paolo Chieffi ◽  
Sergio Minucci ◽  
Gilda Cobellis ◽  
Silvia Fasano ◽  
Riccardo Pierantoni
Keyword(s):  
Reproductive Cycle ◽  
Rana Esculenta ◽  
Annual Reproductive Cycle

scholarly journals Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

2008 ◽  
Vol 72 (1) ◽  
pp. 239-242 ◽  
Author(s):  
M. Cusack ◽  
A. Pérez-Huerta ◽  
P. Chung ◽  
D. Parkinson ◽  
Y. Dauphin ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Seawater Temperature ◽  
Environmental Data ◽  
Ambient Seawater ◽  
Secondary Layer ◽  
Vital Effect ◽  
Vital Effects ◽  
Stable Oxygen ◽  
Isotope Equilibrium

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

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