Neurosteroidogenic enzymes and their regulation in the early brain of the protogynous grouper Epinephelus coioides during gonadal sex differentiation

In this study, we systematically investigated the process of sex reversal induced by 17-methyltestosterone (MT) feeding and MT-feeding withdrawal at the ovary differentiation stage in orange-spotted groupers, Epinephelus coioides. Gonadal histology showed that MT feeding induced a precocious sex reversal from immature ovaries to testes, bypassing the formation of an ovarian cavity, and MT-feeding withdrawal led to an ovarian fate. In both the MT feeding and MT-feeding withdrawal phases, cytochrome P450 family 11 subfamily B (cyp11b) gene expression and serum 11-KT levels were not significantly changed, suggesting that the MT-treated fish did not generate endogenous steroids, even though active spermatogenesis occurred. Finally, by tracing doublesex-expressing and Mab-3-related transcription factor 1 (dmrt1)-expressing cells and TUNEL (terminal deoxynucleotidyl transferase 2-deoxyuridine, 5-triphosphate nick end labeling) assays, we found that the efferent duct formed first, and then, the germ cells and somatic cells of the testicular tissue were generated around the efferent duct during MT-feeding-induced precocious sex reversal. Collectively, our findings provide insights into the molecular and cellular mechanisms underlying sex reversal induced by exogenous hormones during sex differentiation in the protogynous orange-spotted grouper.

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MR measurement of normal corpus callosum: age and sex differentiation

Journal of the Korean Radiological Society ◽

10.3348/jkrs.1992.28.4.527 ◽

1992 ◽

Vol 28 (4) ◽

pp. 527

Author(s):

Myung Seob Lee ◽

Myung Soon Kim ◽

Hyun Ju Park

Keyword(s):

Corpus Callosum ◽

Sex Differentiation ◽

Age And Sex

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Sex determination and Y chromosome constitutive heterochromatin

Current Research in Biochemistry and Molecular Biology ◽

10.33702/crbmb.2019.1.1.1 ◽

2019 ◽

Vol 1 (1) ◽

pp. 1-5

Author(s):

Abyt Ibraimov

Keyword(s):

Sex Determination ◽

Y Chromosome ◽

Constitutive Heterochromatin ◽

Sex Differentiation ◽

Secondary Sexual Characteristics ◽

Biological Meaning ◽

Heterochromatin Block ◽

Sexual Characteristics ◽

Open Question ◽

Efficient Elimination

In many animals, including us, the genetic sex is determined at fertilization by sex chromosomes. Seemingly, the sex determination (SD) in human and animals is determined by the amount of constitutive heterochromatin on Y chromosome via cell thermoregulation. It is assumed the medulla and cortex tissue cells in the undifferentiated embryonic gonads (UEG) differ in vulnerability to the increase of the intracellular temperature. If the amount of the Y chromosome constitutive heterochromatin is enough for efficient elimination of heat difference between the nucleus and cytoplasm in rapidly growing UEG cells the medulla tissue survives. Otherwise it doomed to degeneration and a cortex tissue will remain in the UEG. Regardless of whether our assumption is true or not, it remains an open question why on Y chromosome there is a large constitutive heterochromatin block? What is its biological meaning? Does it relate to sex determination, sex differentiation and development of secondary sexual characteristics? If so, what is its mechanism: chemical or physical? There is no scientifically sound answer to these questions.

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