CCR4-NOT subunit CCF-1/CNOT7 promotes transcriptional activation to multiple stress responses in Caenorhabditis elegans

Identification of pararosaniline as a modifier of RNA splicing in Caenorhabditis elegans

Posttranscriptional splicing of premessenger RNA (mRNA) is an evolutionarily conserved eukaryotic process for producing mature mRNA that is translated into proteins. Accurate splicing is necessary for normal growth and development, and aberrant splicing is increasingly evident in various human pathologies. To study environmental factors that influence RNA splicing, we employed a fluorescent Caenorhabditis elegans in vivo splicing reporter as a biomarker for splicing fidelity to screen against the US EPA ToxCast chemical library. We identified pararosaniline hydrochloride as a strong modifier of RNA splicing. Through gene expression analysis, we found that pararosaniline activates the oxidative stress response and alters the expression of key RNA splicing regulator genes. Physiological assays show that pararosaniline is deleterious to C. elegans development, reproduction, and aging. Through a targeted RNAi screen, we found that inhibiting protein translation can reverse pararosaniline's effect on the splicing reporter and provide significant protection against long-term pararosaniline toxicity. Together, this study reveals a new chemical modifier of RNA splicing and describes translation inhibition as a genetic mechanism to provide resistance.

Investigation of PAL-1 requirement in C. elegans physiology using the auxin-inducible degradation system

The C. elegans PAL-1 protein encodes a caudal-like transcription factor that is required for posterior development and was recently implicated in stress response. We generated a transgenic strain of C. elegans with AID*::3xFLAG::wrmScarlet cassette knocked in at the C-terminal end of the pal-1 locus to enable an auxin-inducible degradation of PAL-1 . We found that auxin-induced degradation of PAL-1 starting from the L1 larval stage does not affect body length development but renders the animal sterile and shortens lifespan. This pal-1 ::AID*::3xFLAG::wrmScarlet strain will be a valuable resource for studying the requirement of PAL-1 in a temporal and tissue-specific manner.

Aging and group selection: New arguments in favor of partially directed evolution

In this study, theories of aging and its mechanisms under various environmental conditions were analyzed. The analysis of published data suggested that aging is a controlled process. It is known that many mathematical algorithms utilize an analogy of aging. However, this is possible only when a "target set" is known in advance. Various forms of selection in relation to aging were analyzed both collectively and separately. The general conclusion is that aging is one of the mechanisms of directed evolution. A model was constructed, which shows how aging is integrated into partially directed evolution.

Evolutionary Change in Gut Specification in Caenorhabditis Centers on the GATA Factor ELT-3 in an Example of Developmental System Drift

Cells in a developing animal embryo become specified by the activation of cell-type-specific gene regulatory networks. The network that specifies the gut in the nematode Caenorhabditis elegans has been the subject of study for more than two decades. In this network, the maternal factors SKN-1/Nrf and POP-1/TCF activate a zygotic GATA factor cascade consisting of the regulators MED-1,2 → END-1,3 → ELT-2,7, leading to the specification of the gut in early embryos. Paradoxically, the MED, END, and ELT-7 regulators are present only in species closely related to C. elegans, raising the question of how the gut can be specified without them. Recent work found that ELT-3, a GATA factor without an endodermal role in C. elegans, acts in a simpler ELT-3 → ELT-2 network to specify gut in more distant species. The simpler ELT-3 → ELT-2 network may thus represent an ancestral pathway. In this review, we describe the elucidation of the gut specification network in C. elegans and related species and propose a model by which the more complex network might have formed. Because the evolution of this network occurred without a change in phenotype, it is an example of the phenomenon of Developmental System Drift.