A matter of timing | ScienceGate

Abstract The tra-1 gene is a terminal regulator of somatic sex in Caenorhabditis elegans: high tra-1 activity elicits female development, low tra-1 activity elicits male development. To investigate the function and evolution of tra-1, we examined the tra-1 gene from the closely related nematode C. briggsae. Ce-tra-1 and Cb-tra-1 are unusually divergent. Each gene generates two transcripts, but only one of these is present in both species. This common transcript encodes TRA-1A, which shows only 44% amino acid identity between the species, a figure much lower than that for previously compared genes. A Cb-tra-1 transgene rescues many tissues of tra-1(nul1) mutants of C. elegans but not the somatic gonad or germ line. This transgene also causes nongonadal feminization of XO animals, indicating incorrect sexual regulation. Alignment of Ce-TRA-1A and Cb-TRA-1A defines several conserved regions likely to be important for tra-1 function. The phenotypic differences between Ce-tra-1(null) mutants rescued by Cb-tra-1 transgenes and wild-type C. elegans indicate significant divergence of regulatory regions. These molecular and functional studies suggest that evolution of sex determination in nematodes is rapid and genetically complex.

Download Full-text

Neuropeptide signalling shapes feeding and reproductive behaviours in male C. elegans

10.1101/2021.11.29.470485 ◽

2021 ◽

Author(s):

Matthew J Gadenne ◽

Iris Hardege ◽

Djordji Suleski ◽

Paris Jaggers ◽

Isabel Beets ◽

...

Keyword(s):

Synaptic Connectivity ◽

Male Mating ◽

Sexually Dimorphic ◽

C Elegans ◽

Mating Efficiency ◽

Sexually Dimorphic Expression ◽

Pharyngeal Pumping ◽

Insight Into ◽

Feeding Behaviours ◽

Dimorphic Expression

Sexual dimorphism occurs where different sexes of the same species display differences in characteristics not limited to reproduction. For the nematode Caenorhabditis elegans, in which the complete neuroanatomy has been solved for both hermaphrodites and males, sexually dimorphic features have been observed both in terms of the number of neurons and in synaptic connectivity. In addition, male behaviours, such as food-leaving to prioritise searching for mates, have been attributed to neuropeptides released from sex-shared or sex-specific neurons. In this study, we show that the lury-1 neuropeptide gene shows a sexually dimorphic expression pattern; being expressed in pharyngeal neurons in both sexes but displaying additional expression in tail neurons only in the male. We also show that lury-1 mutant animals show sex differences in feeding behaviours, with pharyngeal pumping elevated in hermaphrodites but reduced in males. LURY-1 also modulates male mating efficiency, influencing motor events during contact with a hermaphrodite. Our findings indicate sex-specific roles of this peptide in feeding and reproduction in C. elegans, providing further insight into neuromodulatory control of sexually dimorphic behaviours.

Download Full-text

The heparan sulfate 3‐O‐sulfotransferase hst‐3.2 is required for neural development in C. elegans

The FASEB Journal ◽

10.1096/fasebj.26.1_supplement.232.1 ◽

2012 ◽

Vol 26 (S1) ◽

Author(s):

Hannes Erich Buelow ◽

Eillen Tecle ◽

Carlos A Diaz-Balzac ◽

Magali Richard ◽

Jean-Louis Bessereau

Keyword(s):

Heparan Sulfate ◽

Neural Development ◽

C Elegans

Download Full-text

Regulation of axon repulsion by MAX-1 SUMOylation and AP-3

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1804373115 ◽

2018 ◽

Vol 115 (35) ◽

pp. E8236-E8245

Author(s):

Shih-Yu Chen ◽

Chun-Ta Ho ◽

Wei-Wen Liu ◽

Mark Lucanic ◽

Hsiu-Ming Shih ◽

...

Keyword(s):

Axon Guidance ◽

Neural Development ◽

Biochemical Analysis ◽

Genetic Interaction ◽

Motor Axons ◽

Surface Receptors ◽

C Elegans ◽

Guidance Receptors ◽

Axon Repulsion

During neural development, growing axons express specific surface receptors in response to various environmental guidance cues. These axon guidance receptors are regulated through intracellular trafficking and degradation to enable navigating axons to reach their targets. In Caenorhabditis elegans, the UNC-5 receptor is necessary for dorsal migration of developing motor axons. We previously found that MAX-1 is required for UNC-5–mediated axon repulsion, but its mechanism of action remained unclear. Here, we demonstrate that UNC-5–mediated axon repulsion in C. elegans motor axons requires both max-1 SUMOylation and the AP-3 complex β subunit gene, apb-3. Genetic interaction studies show that max-1 is SUMOylated by gei-17/PIAS1 and acts upstream of apb-3. Biochemical analysis suggests that constitutive interaction of MAX-1 and UNC-5 receptor is weakened by MAX-1 SUMOylation and by the presence of APB-3, a competitive interactor with UNC-5. Overexpression of APB-3 reroutes the trafficking of UNC-5 receptor into the lysosome for protein degradation. In vivo fluorescence recovery after photobleaching experiments shows that MAX-1 SUMOylation and APB-3 are required for proper trafficking of UNC-5 receptor in the axon. Our results demonstrate that SUMOylation of MAX-1 plays an important role in regulating AP-3–mediated trafficking and degradation of UNC-5 receptors during axon guidance.

Download Full-text

Cross-sexual Transfer

Developmental Plasticity and Evolution ◽

10.1093/oso/9780195122343.003.0021 ◽

2003 ◽

Author(s):

Mary Jane West-Eberhard

Keyword(s):

Sex Determination ◽

Sexually Dimorphic ◽

Male And Female ◽

Alternative Phenotypes ◽

Opposite Sex ◽

Critical Age ◽

Sexual Traits ◽

Discrete Traits ◽

Dimorphic Species ◽

Determination Mechanism

Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.

Download Full-text

Role of autonomous and non-autonomous sex determination signals in sexually dimorphic development of the Drosophila embryonic gonad

Developmental Biology ◽

10.1016/j.ydbio.2007.03.114 ◽

2007 ◽

Vol 306 (1) ◽

pp. 313 ◽

Cited By ~ 2

Author(s):

N.R. Crnkovich ◽

T.J. DeFalco ◽

S Le Bras ◽

A.L. Casper ◽

M.B. Van Doren

Keyword(s):

Sex Determination ◽

Sexually Dimorphic ◽

Embryonic Gonad

Download Full-text

Post-transcriptional regulation of sex determination in Caenorhabditis elegans: widespread expression of the sex-determining gene fem-1 in both sexes.

Molecular Biology of the Cell ◽

10.1091/mbc.7.7.1107 ◽

1996 ◽

Vol 7 (7) ◽

pp. 1107-1121 ◽

Cited By ~ 35

Author(s):

J Gaudet ◽

I VanderElst ◽

A M Spence

Keyword(s):

Sex Determination ◽

Signal Transduction Pathway ◽

Functional Expression ◽

Noncoding Sequences ◽

Somatic Development ◽

C Elegans ◽

Somatic Tissues ◽

Germline Expression ◽

Post Transcriptional Regulation ◽

Do So

The fem-1 gene of C. elegans is one of three genes required for all aspects of male development in the nematode. Current models of sex determination propose that the products of the fem genes act in a novel signal-transduction pathway and that their activity is regulated primarily at the post-translational level in somatic tissues. We analyzed the expression of fem-1 to determine whether it revealed any additional levels of regulation. Both XX hermaphrodites and XO males express fem-1 at approximately constant levels throughout development. Somatic tissues in hermaphrodites adopt female fates, but they nonetheless express fem-1 mRNA and FEM-1 protein, suggesting that the regulation of fem-1 activity is post-transcriptional and probably post-translational. A compact promoter directs functional expression of fem-1 transgenes, as assayed by their masculinizing activity in fem-1 mutants. Activity also requires any two or more introns, suggesting that splicing may enhance fem-1 expression. The minimal noncoding sequences required for activity of fem-1 transgenes suffice to direct expression of a fem-1::lacZ reporter gene in all somatic tissues in both sexes. Many fem-1 transgenes, including those that rescue male somatic development in fem-1 mutants, paradoxically feminize the germline. We suggest that they do so by interfering with the germline expression of the endogenous fem-1 gene.

Download Full-text