ICTV Virus Taxonomy Profile: Nyamiviridae 2021

Nyamiviridae is a family of viruses in the order Mononegavirales, with unsegmented (except for members of the genus Tapwovirus), negative-sense RNA genomes of 10–13 kb. Nyamviruses have a genome organisation and content similar to that of other mononegaviruses. Nyamiviridae includes several genera that form monophyletic clades on phylogenetic analysis of the RNA polymerase. Nyamiviruses have been found associated with diverse invertebrates as well as land- and seabirds. Members of the genera Nyavirus and Socyvirus produce enveloped, spherical virions. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Nyamiviridae, which is available at ictv.global/report/nyamiviridae.

SSIM can robustly identify changes in 3D genome conformation maps

We previously presented Comparison of Hi-C Experiments using Structural Similarity (CHESS), an approach that applies the concept of the structural similarity index (SSIM) to Hi-C matrices, and demonstrated that it could be used to identify both regions with similar 3D chromatin conformation across species, and regions with different chromatin conformation in different conditions. In contrast to the claim of Lee et al. that the SSIM output of CHESS is independent of the input data, here we confirm that SSIM depends on both local and global properties of the input Hi-C matrices. We provide two approaches for using CHESS to highlight regions of differential genome organisation for further investigation, and expanded guidelines for choosing appropriate parameters and controls for these analyses.

Nuclear organisation and replication timing are coupled through RIF1–PP1 interaction

Three-dimensional genome organisation and replication timing are known to be correlated, however, it remains unknown whether nuclear architecture overall plays an instructive role in the replication-timing programme and, if so, how. Here we demonstrate that RIF1 is a molecular hub that co-regulates both processes. Both nuclear organisation and replication timing depend upon the interaction between RIF1 and PP1. However, whereas nuclear architecture requires the full complement of RIF1 and its interaction with PP1, replication timing is not sensitive to RIF1 dosage. The role of RIF1 in replication timing also extends beyond its interaction with PP1. Availing of this separation-of-function approach, we have therefore identified in RIF1 dual function the molecular bases of the co-dependency of the replication-timing programme and nuclear architecture.

Genome organisation and evolution of a eukaryotic nicotinate co-inducible pathway

We describe an HxnR-dependent regulon composed of 11 hxn genes (hxnS, T, R, P, Y, Z, X, W, V, M and N). The regulon is inducible by a nicotinate metabolic derivative and repressible by ammonium and under stringent control of the GATA factor AreA. This is the first publication of a eukaryotic, complete nicotinate metabolic cluster including five novel genes. While in A. nidulans the regulon is organised in three distinct clusters, this organisation is variable in the Ascomycota. In some Pezizomycotina species all the 11 genes are organised in a single cluster, in other in two clusters. This variable organisation sheds light on cluster evolution. Instances of gene duplication, followed by or simultaneous with integration in the cluster; partial or total cluster loss; horizontal gene transfer of several genes, including an example of whole cluster re-acquisition in Aspergillus of section Flavi were detected, together with the incorporation in some clusters of genes not found in the A. nidulans co-regulated regulon, which underlie both the plasticity and the reticulate character of metabolic cluster evolution. This study provides the first comprehensive protein sequence comparison of six members of the cluster across representatives of all Ascomycota classes, including several hundreds of species.

Genomic loci mispositioning in Tmem120a knockout mice yields latent lipodystrophy

Little is known about the proteins that direct the highly conserved patterns of spatial genome organisation in fat. Here we report that adipocyte-specific knockout of the gene encoding nuclear envelope protein Tmem120a disrupts fat genome organisation, thus causing a novel lipodystrophy syndrome. Tmem120a deficiency broadly suppresses lipid metabolism pathway gene expression and induces myogenic gene expression by repositioning genes, enhancers and miRNA-encoding loci between the nuclear periphery and interior. Tmem120a-/- mice, particularly females, exhibit a lipodystrophy syndrome similar to human familial partial lipodystrophy FPLD2, with profound insulin resistance and metabolic defects that manifests upon exposure to an obesogenic diet. Interestingly, similar genome organisation defects occurred in cells from FPLD2 patients that harbour nuclear envelope protein laminA mutations. Our data suggest TMEM120A may mediate/instigate novel categories of adipose tissue dysfunction across the adiposity spectrum and provide a new miRNA-based mechanism possibly driving the unexplained muscle hypertrophy in human lipodystrophy.

The Human Genome Organisation (HUGO) and the 2020 COVID-19 pandemic

This letter is the Human Genome Organisation’s summary reaction to the 2020 COVID-19 pandemic. It identifies key areas for genomics research, and areas in which genomic scientists can contribute to a global response to the pandemic. The letter has been reviewed and endorsed by the HUGO Committee on Ethics, Law and Society (CELS) and the HUGO Council.

Diversity of SARS-CoV-2 isolates driven by pressure and health index

One of the main concerns about the fast spreading coronavirus disease 2019 (Covid-19) pandemic is how to intervene. We analysed severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) isolates data using the multifractal approach and found a rich in viral genome diversity, which could be one of the root causes of the fast Covid-19 pandemic and is strongly affected by pressure and health index of the hosts inhabited regions. The calculated mutation rate (mr) is observed to be maximum at a particular pressure, beyond which mr maintains diversity. Hurst exponent and fractal dimension are found to be optimal at a critical pressure (Pm), whereas, for P > Pm and P < Pm, we found rich genome diversity relating to complicated genome organisation and virulence of the virus. The values of these complexity measurement parameters are found to be increased linearly with health index values.