Germline tumor formation in <i>trd-1(RNAi)</i> animals suggests a defect in the mitosis-meiosis switch.

<p>Young adult animals (L4+1day) were stained with DAPI and the gonads scored for the presence of sperm and oocytes (essentially wild type gonads), germlines which contained only sperm (Sp), or only oocytes (Oo) or were tumorous (Tum), a phenotype in which no differentiated nuclei are observed in the germline and all nuclei remain in mitosis. <i>trd-1</i> RNAi synergistically enhances the Tum phenotype of <i>gld-3(q741)</i> mutants.</p><p>Germline tumor formation in <i>trd-1(RNAi)</i> animals suggests a defect in the mitosis-meiosis switch.</p

Germline tumor formation in <i>trd-1(RNAi)</i> animals suggests a defect in the mitosis-meiosis switch.

<p>Young adult animals (L4+1day) were stained with DAPI and the gonads scored for the presence of sperm and oocytes (essentially wild type gonads), germlines which contained only sperm (Sp), or only oocytes (Oo) or were tumorous (Tum), a phenotype in which no differentiated nuclei are observed in the germline and all nuclei remain in mitosis. <i>trd-1</i> RNAi synergistically enhances the Tum phenotype of <i>gld-3(q741)</i> mutants.</p><p>Germline tumor formation in <i>trd-1(RNAi)</i> animals suggests a defect in the mitosis-meiosis switch.</p

Epistasis analysis suggests that <i>trd-1</i> functions downstream of <i>tra-2</i> and upstream of <i>fem-3</i>.

<p>Worms were bleach synchronized at 15°C then L1s hatched, fed and shifted to 20°C or 25°C as indicated. Following whole worm DAPI on L4+1 day old animals, the presence of sperm (Sp) and oocytes (Oo) was recorded. <i>fog-1(q253, lf)</i> and <i>fem-3(e2006, lf)</i> mutants produce only oocytes at the restrictive temperature of 25°C, a phenotype which is unaltered by <i>trd-1</i> RNAi, suggesting that <i>trd-1</i> is operating upstream. The <i>fbf-2(q738)</i> mutation has a 23% penetrant feminized germline phenotype at 20°C which is completely suppressed by <i>trd-1</i> RNAi. These animals are masculinized to the same extent as <i>trd-1</i> RNAi animals alone, suggesting that <i>trd-1</i> operates downstream of (or in parallel to) <i>fbf-2</i>. <i>tra-2 (e2020, gf)</i> mutants are feminized at 20°C, a phenotype that is significantly suppressed by <i>trd-1</i> RNAi (again, these animals are masculinized to a similar extent to <i>trd-1</i> RNAi animals alone). This suggests that <i>trd-1</i> is downstream of <i>tra-2</i>. Overall, therefore, <i>trd-1</i> appears to be operating downstream of <i>tra-2</i> but upstream of <i>fem-3</i> to regulate germline sex determination.</p><p>Epistasis analysis suggests that <i>trd-1</i> functions downstream of <i>tra-2</i> and upstream of <i>fem-3</i>.</p

Genetic regulation of germline sex determination.

<p>The pathway consists of a cascade of regulatory interactions driving sexual fate. Essentially, <i>fem-1</i>, -<i>2</i> and -<i>3</i> together with <i>fog-1</i> and <i>fog-3</i> promote spermatogenesis. To allow hermaphrodite animals to switch to oocyte production at the late L4 stage, <i>tra-2</i> is repressed by the action of FOG-2 and GLD-1. <i>fem-3</i> is repressed at the level of mRNA by multiple factors. Thus, regulation of the balance of TRA-2 and FEM-3 levels allows the timely transition from sperm to oocyte production, in order to generate fully fertile hermaphrodites. Factors that promote male and female fates are highlighted in blue and red, respectively. Adapted from Kimble and Crittenden <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114998#pone.0114998-Thompson1" target="_blank">[14]</a> and Rybarska <i>et al.</i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114998#pone.0114998-Rybarska1" target="_blank">[41]</a>.</p

Strains used in this investigation.

<p>Strains used in this investigation.</p