Biology subjects

Kiontke, K. C.

Publications and source records attributed to Kiontke, K. C..

4 recordsLinked to original sources

bioRxiv2024

Morphologically defined substages of tail tip morphogenesis in C. elegans males

BackgroundSex-specific morphogenesis occurs in C. elegans in the vulva of the hermaphrodite and in the male tail during the last larval stage. Temporal progression of vulva morphogenesis has been described in fine detail. However, a similar precise description of male tail morphogenesis was lacking. ResultsWe here describe morphogenesis of the male tail at time points matching vulva development with special focus on morphogenesis of the tail tip. Using fluorescent reporters, we follow changes in cell shapes, cell fusions, nuclear migration, modifications in the basement membrane and formation of a new apical extracellular matrix at the end of the tail. ConclusionOur analysis answers two open questions about tail tip morphogenesis (TTM) by showing that one of the four tail tip cells, hyp11, remains separate while the other cells fuse with each other and with two additional tail cells to form a ventral tail syncytium. This fusion begins early during TTM but is only completed towards the end of the process. This work provides a framework for future investigations of cell-biological factors that drive male tail morphogenesis.

developmental biology↗

bioRxiv2024

Tissue-specific RNA-seq defines genes governing male tail tip morphogenesis in C. elegans

Caenorhabditis elegans males undergo sex-specific tail tip morphogenesis (TTM) under the control of the transcription factor DMD-3. To find genes regulated by DMD-3, We performed RNA-seq of laser-dissected tail tips. We identified 564 genes differentially expressed (DE) in wild-type males vs. dmd-3(-) males and hermaphrodites. The transcription profile of dmd-3(-) tail tips is similar to that in hermaphrodites. For validation, we analyzed transcriptional reporters for 49 genes and found male-specific or male-biased expression for 26 genes. Only 11 DE genes overlapped with genes found in a previous RNAi screen for defective TTM. GO enrichment analysis of DE genes finds upregulation of genes within the UPR (unfolded protein response) pathway and downregulation of genes involved in cuticle maintenance. Of the DE genes, 40 are transcription factors, indicating that the gene network downstream of DMD-3 is complex and potentially modular. We propose modules of genes that act together in TTM and are coregulated by DMD-3, among them the chondroitin synthesis pathway and the hypertonic stress response.

developmental biology↗

bioRxiv2019

Deep sampling of Hawaiian Caenorhabditis elegans reveals high genetic diversity and admixture with global populations

Recent efforts to understand the natural niche of the keystone model organism Caenorhabditis elegans have suggested that this species is cosmopolitan and associated with rotting vegetation and fruits. However, most of the strains isolated from nature have low genetic diversity likely because recent chromosome-scale selective sweeps contain alleles that increase fitness in human-associated habitats. Strains from the Hawaii Islands are highly divergent from non-Hawaiian strains. This result suggests that Hawaiian strains might contain ancestral genetic diversity that was purged from most non-Hawaiian strains by the selective sweeps. To characterize the genetic diversity and niche of Hawaiian C. elegans, we sampled across the Hawaiian Islands and isolated 100 new C. elegans strains. We found that C. elegans strains are not associated with any one substrate but are found in cooler climates at high elevations. These Hawaiian strains are highly diverged compared to the rest of the global population. Admixture analysis identified 11 global populations, four of which are from Hawaii. Surprisingly, one of the Hawaiian populations shares recent ancestry with non-Hawaiian populations, including portions of globally swept haplotypes. This discovery provides the first evidence of gene flow between Hawaiian and non-Hawaiian populations. Most importantly, the high levels of diversity observed in Hawaiian strains might represent the complex patterns of ancestral genetic diversity in the C. elegans species before human influence.

ecology↗

bioRxiv2018

Comparative genomics of ten new Caenorhabditis species

The nematode Caenorhabditis elegans has been central to the understanding of metazoan biology. However, C. elegans is but one species among millions and the significance of this important model organism will only be fully revealed if it is placed in a rich evolutionary context. Global sampling efforts have led to the discovery of over 50 putative species from the genus Caenorhabditis, many of which await formal species description. Here, we present species descriptions for ten new Caenorhabditis species. We also present draft genome sequences for nine of these new species, along with a transcriptome assembly for one. We exploit these whole-genome data to reconstruct the Caenorhabditis phylogeny and use this phylogenetic tree to dissect the evolution of morphology in the genus. We show unexpected complexity in the evolutionary history of key developmental pathway genes. The genomic data also permit large scale analysis of gene structure, which we find to be highly variable within the genus. These new species and the associated genomic resources will be essential in our attempts to understand the evolutionary origins of the C. elegans model.

evolutionary biology↗