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The Ratio of X Chromosome to Autosomes

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In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
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Related Experiment Video

Updated: Jul 9, 2026

Dissection of Larval Zebrafish Gonadal Tissue

Dissection of Larval Zebrafish Gonadal Tissue

Published on: April 26, 2017

Somatic sex determination.

David Zarkower¹

¹Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA. zarko001@umn.edu

Wormbook : the Online Review of C. Elegans Biology

|December 1, 2007

Summary

The sex determination pathway in C. elegans, involving SDC proteins and the her-1 gene, controls both sex identity and dosage compensation. This pathway

Area of Science:

Genetics
Developmental Biology
Evolutionary Biology

Background:

The nematode C. elegans has two sexes: XX hermaphrodites and XO males.
Somatic sexual differences arise from a global sex determination regulatory pathway.
This pathway coordinates sex determination with X chromosome dosage compensation via SDC proteins.

Purpose of the Study:

To elucidate the molecular mechanisms of the C. elegans sex determination pathway.
To identify additional sex regulators within this pathway and downstream of TRA-1.
To investigate the evolutionary history of sex determination.

Main Methods:

Analysis of the global sex determination regulatory pathway in C. elegans.
Investigating the roles of SDC proteins, her-1, HER-1, TRA-2, FEM proteins, and TRA-1.

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A Seminiferous Tubule Squash Technique for the Cytological Analysis of Spermatogenesis Using the Mouse Model

Published on: February 6, 2018

Related Experiment Videos

Last Updated: Jul 9, 2026

Dissection of Larval Zebrafish Gonadal Tissue

Dissection of Larval Zebrafish Gonadal Tissue

Published on: April 26, 2017

Accurate and Phenol Free DNA Sexing of Day 30 Porcine Embryos by PCR

Accurate and Phenol Free DNA Sexing of Day 30 Porcine Embryos by PCR

Published on: February 14, 2016

A Seminiferous Tubule Squash Technique for the Cytological Analysis of Spermatogenesis Using the Mouse Model

A Seminiferous Tubule Squash Technique for the Cytological Analysis of Spermatogenesis Using the Mouse Model

Published on: February 6, 2018

Utilizing genetic and genomic technologies and comparative studies.

Main Results:

SDC proteins repress her-1, controlling somatic and germline sex.
HER-1 acts on a regulatory module including TRA-2, FEM proteins, and TRA-1.
TRA-1 regulates downstream targets like EGL-1 and MAB-3, controlling sexual differentiation.

Conclusions:

The C. elegans sex determination pathway shows potential links to the Hedgehog signaling pathway.
DM domain proteins like MAB-3 are conserved across phyla for sexual differentiation.
Further research is needed on pathway mechanisms, additional regulators, and evolutionary aspects.