[
WormBook,
2005]
The features that differentiate the C. elegans male from the hermaphrodite arise during postembryonic development. The major male mating structures, consisting of the blunt tail with fan and rays, the hook, the spicules and proctodeum, and the thin body, form just before the last larval molt. Male and hermaphrodite embryogenesis are similar but some essential male cell fates are already established at hatching. The male mating structures arise from three important sets of male-specific blast cells. These cells generate a total of 205 male-specific somatic cells, including 89 neurons, 36 neuronal support cells, 41 muscles, 23 cells involved in differentiating the hindgut, and 16 hypodermal cells associated with mating structures. Genetic and molecular studies have identified many genes required for male development, most of which also function in the hermaphrodite. Cell-cell interactions play a role in patterning all three of the generative tissues. Male-specific neurons, including sensory neurons of the rays, hook, post-cloacal sensilla, and spicules, differentiate at the end of the last larval stage and send out axons to make connections into the existing neuropil, greatly enlarging the posterior ganglia. The hindgut is highly differentiated to accommodate the spicules and the joining of the reproductive tract to the cloaca. A complex male-specific program generates many new muscles for copulation. The cell lineage and genetic program that gives rise to the one-armed male gonad appears to be a variation on that of the hermaphrodite.
[
Mitochondrion,
2020]
Mitochondria are key components of eukaryotic cells, so their proper functioning is monitored via different mitochondrial signalling responses. One of these mitochondria-to-nuclear 'retrograde' responses to maintain mitochondrial homeostasis is the mitochondrial unfolded protein response (UPR<sup>mt</sup>), which can be activated by a variety of defects including blocking mitochondrial translation, respiration, protein import or transmembrane potential. Although UPR<sup>mt</sup> was first reported in cultured mammalian cells, this signalling pathway has also been extensively studied in the nematode Caenorhabditis elegans. In yeast, there are no published studies focusing on UPR<sup>mt</sup> in a strict sense, but other unfolded protein responses (UPR) that appear related to UPR<sup>mt</sup> have been described, such as the UPR activated by protein mistargeting (UPR<sup>am</sup>) and mitochondrial compromised protein import response (mitoCPR). In plants, very little is known about UPR<sup>mt</sup> and only recently some of the regulators have been identified. In this paper, we summarise and compare the current knowledge of the UPR<sup>mt</sup> and related responses across eukaryotic kingdoms: animals, fungi and plants. Our comparison suggests that each kingdom has evolved its own specific set of regulators, however, the functional categories represented among UPR<sup>mt</sup>-related target genes appear to be largely overlapping. This indicates that the strategies for preserving proper mitochondrial functions are partially conserved, targeting mitochondrial chaperones, proteases, import components, dynamics and stress response, but likely also non-mitochondrial functions including growth regulators/hormone balance and amino acid metabolism. We also identify homologs of known UPR<sup>mt</sup> regulators and responsive genes across kingdoms, which may be interesting targets for future research.