scholarly journals Development of steroid-producing cells in pink salmon and lamprey fries during gonadal sex differentiation

2015 ◽  
Author(s):  
Marina Mosyagina ◽  
Oleg Zelennikov
Keyword(s):  
Comparative Study ◽  
Gradual Increase ◽  
Sex Differentiation ◽  
Pink Salmon ◽  
Gonad Development ◽  
Sex Change ◽  
Secretory Cells

A comparative study of the first stages of gametogenesis and ultrastructure of steroid-secretory cells in the gonads of juvenile pink salmon and lamprey was performed. In individuals of both species the gonad development is accompanied by natural sex change. It has been shown that increasing of the number and activity of steroid-producing cells in the testes coincides with resorption of previtelligenous oocytes. In the ovaries there is a gradual increase in the activity of steroid-producing cells and change of their localization from stroma towards follicular layers of oocytes. Based on these results we can conclude that the described processes are similar in taxonomically different species. Refs 21. Figs 3. Tables 2.

Sex, Gonad Development and Seasonal Gonad Changes in Paphia staminea Conrad

1943 ◽  
Vol 6b (2) ◽  
pp. 140-151 ◽  
Author(s):  
D. B. Quayle
Keyword(s):  
British Columbia ◽  
Sex Differentiation ◽  
Time Lag ◽  
Gonad Development ◽  
Follicle Cells ◽  
Active Growth ◽  
Spawning Cycle ◽  
Sex Cells

In the little-neck clam, Paphia staminea, as occurring in British Columbia waters, the first sign of the gonad was found in individuals slightly over 1 mm. in length. Sex differentiation occurs at lengths of 15 to 30 mm. or in 2nd or 3rd year. Maturity is achieved at 22 to 35 mm. P. staminea is not protandric. Seasonal gonad changes are: by end of October all active spawning over; by December to January tubules of ovary filled with follicle cells; active growth of sex cells reaches peak in March; first spawning in April and by September most clams spawned out. Male spawning cycle parallels that of female, with certain time lag apparent. Some males may remain in spawned-out state during most of winter.

scholarly journals Aromatase pathway mediates sex change in each direction

2005 ◽  
Vol 272 (1570) ◽  
pp. 1399-1405 ◽  
Author(s):  
Frederieke J Kroon ◽  
Philip L Munday ◽  
David A Westcott ◽  
Jean-Paul A Hobbs ◽  
N. Robin Liley
Keyword(s):  
Sexual Development ◽  
Sex Differentiation ◽  
Sex Change ◽  
Experimental Manipulation ◽  
Social Cues ◽  
Environmental Sex Determination ◽  
Bidirectional Sex Change ◽  
Key Enzyme ◽  
Development And Differentiation ◽  
First Time

The enzyme aromatase controls the androgen/oestrogen ratio by catalysing the irreversible conversion of testosterone into oestradiol (E 2 ). Therefore, the regulation of E 2 synthesis by aromatase is thought to be critical in sexual development and differentiation. Here, we demonstrate for the first time that experimental manipulation of E 2 levels via the aromatase pathway induces adult sex change in each direction in a hermaphroditic fish that naturally exhibits bidirectional sex change. Our results demonstrate that a single enzymatic pathway can regulate both female and male sexual differentiation, and that aromatase may be the key enzyme that transduces environmental, including social, cues to functional sex differentiation in species with environmental sex determination.

A Comparative Study of Femoral Head Diameters and Sex Differentiation in Nigerians

1998 ◽  
Vol 162 (4) ◽  
pp. 232-237 ◽  
Author(s):  
S.A. Asala ◽  
F.E. Mbajiorgu ◽  
B.A. Papandro
Keyword(s):  
Femoral Head ◽  
Comparative Study ◽  
Sex Differentiation

Comparative Study between Candida antarctica Lipase B and Pseudomonas floroscens as Catalyst for Polycaprolactone Production

2012 ◽  
Vol 626 ◽  
pp. 547-550
Author(s):  
Senthil Kumar Senthil ◽  
M.H. Uzir ◽  
Z. Ahmad
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Comparative Study ◽  
Ring Opening ◽  
Gradual Increase ◽  
Candida Antarctica ◽  
Novozym 435 ◽  
Lipase B ◽  
Polymerization System ◽  
Effects Of Temperature

The Effects of temperature on ring-opening bulk polymerizations of ε-caprolactone was studied by using two different lipases Novozym 435 (immobilized form of lipase B from Candida antarctica), and Pseudomonas Floroscens as biocatalyst. The polymerization of ε-caprolactone was carried out at 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C. For Novozym 435 the results showed that increasing the reaction time of the polymerization system resulted in an increased rate of monomer consumption and hence increased the molecular weight. For an increase in reaction time the conversion increases steadily and after a gradual increase there is a decrease which is found uniform for all the temperature showing a uniform trend. For a temperature of 70°C and 4 hours molecular weight was found to be 8.4 x 104 daltons which were the highest of all the readings that were obtained. In the copolymerizaton of ε-caprolactone (ε-CL) and δ-valerolactone using Pseudomonas fluorescens lipase at 60°C for 20 days a copolymer with molecular weight of 1.97 x 105 was obtained. Effects of the reaction time and temperature on the copolymerization have been examined.

Ovarian aromatase and estrogens: A pivotal role for gonadal sex differentiation and sex change in fish

2010 ◽  
Vol 165 (3) ◽  
pp. 352-366 ◽  
Author(s):  
Yann Guiguen ◽  
Alexis Fostier ◽  
Francesc Piferrer ◽  
Ching-Fong Chang
Keyword(s):  
Sex Differentiation ◽  
Sex Change ◽  
Pivotal Role
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