let-7 microRNA absent in many Caenorhabditis nematodes

A recent paper by Nelson and Ambros [1] reports that let-7 heterochronic microRNA is absent in Caenorhabditis species of the japonica group. Research in C. elegans has shown that let-7 plays an essential role during larval to adult transition and mutations in let-7 cause lethality. Authors used one species of the japonica group, C. sulstoni, to further investigate microRNA gene regulatory network. The results revealed that the loss of let-7 function in this species is compensated by other let-7 family members, i.e., miR-48, miR- 84, and miR-241.

Considering that let-7 is highly conserved across bilaterians [2], the results presented in this paper are exciting. However, more work is needed to understand the basis of such an evolutionary change and other potential changes in microRNA-mediated processes.

Reference:
1. Nelson C. and Ambros V. (2021). A cohort of Caenorhabditis species lacking the highly conserved let-7 microRNA. G3, 11(3), jkab022. DOI: 10.1093/g3journal/jkab022.

2. Pasquinelli A.E. et al. (2000). Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA. Nature. 408:86–89.

Control of life-history trade-off by cis-regulatory mutation in eak-3

A new paper by Billard et al. (DOI: j.cub.2020.08.004) reports that a 92-bp deletion in eak-3 alters steroid hormone dafachronic acid (DA) signaling in C. elegans resulting in increased environmental sensitivity for dauer induction and delayed reproductive growth. The findings reveal the genetic basis of choice between somatic maintenance and reproductive growth in response to environmental variation.

Billard, B., Vigne, P. & Braendle, C. A. (2020). Natural Mutational Event Uncovers a Life History Trade-Off via Hormonal Pleiotropy. Curr Biol, vol. 30, 1–13, November 2, 2020.

2020 March 22

Update on the topic meeting “Ecology, Evolution and Genomics of C. elegans and Other Nematodes”:

Due to the COVID-19 crisis, physical meeting has been cancelled. The possibility of a virtual, on-line meeting is being explored.

The other two topic meetings and European meeting are not affected as yet. More details will be released in coming weeks. These are,

Neuronal Development, Synapse Function and Behavior
July 8-11, 2020
University of Vienna, Austria

Metabolism, Aging, Pathogenesis, Stress and Small RNAs
July 16th-19th, 2020
University of Wisconsin, Madison, USA

European C. elegans meeting
July 12-15, 2020
Luminy Campus, Marseille, France

The Indian worm meeting has been postponed. Visit the website for details: https://www.indiancelegansmeet2020.com