Ribosome biogenesis is vital for sustaining stem cell properties, yet its regulatory mechanisms are obscure. Herein, we show unique properties of zebrafish mutants in which spermatogonial stem cells (SSCs) do not differentiate or upregulate rRNAs. Meioc colocalized with Piwil1 in perinuclear germ granules, but Meioc depletion resulted in Piwil1 accumulation in nucleoli. Nucleolar Piwil1 interacted with 45S pre-rRNA. spermatogonia with reduced Piwil1 upregulated rRNAs, and spermatogonia recovered differentiation later than those in . Further, Piwil1 interacted with Setdb1 and HP1α, and spermatogonia exhibited high levels of H3K9me3 and methylated CpG in the 45S-rDNA region. These results indicate that zebrafish SSCs silence rRNA transcription with repressive marks similar to piRNA targets of RNA polymerase II, and that Meioc has a unique function on preventing localization of Piwil1 in nucleoli to upregulate rRNA transcripts and to promote SSC differentiation.
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http://dx.doi.org/10.1101/2024.11.17.623901 | DOI Listing |
Gut Microbes
December 2025
School of Microbiology, University College Cork, Cork, Ireland.
Crohn's disease (CD) and ulcerative colitis (UC) are chronic relapsing inflammatory bowel disorders (IBD), the pathogenesis of which is uncertain but includes genetic susceptibility factors, immune-mediated tissue injury and environmental influences, most of which appear to act via the gut microbiome. We hypothesized that host-microbe alterations could be used to prognostically stratify patients experiencing relapses up to four years after endoscopy. We therefore examined multiple omics data, including published and new datasets, generated from paired inflamed and non-inflamed mucosal biopsies from 142 patients with IBD (54 CD; 88 UC) and from 34 control (non-diseased) biopsies.
View Article and Find Full Text PDFCRISPR J
January 2025
Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA.
Bacteria and archaea acquire resistance to genetic parasites by preferentially integrating short fragments of foreign DNA at one end of a Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR). "Leader" DNA upstream of CRISPR loci regulates transcription and foreign DNA integration into the CRISPR. Here, we analyze 37,477 CRISPRs from 39,277 bacterial and 556 archaeal genomes to identify conserved sequence motifs in CRISPR leaders.
View Article and Find Full Text PDFrRNA-derived fragments (rRFs) are a class of emerging post-transcriptional regulators of gene expression likely binding to the transcripts of target genes. However, the lack of knowledge about such targets hinders our understanding of rRF functions or binding mechanisms. The paucity of resources supporting the identification of the targets of rRFs creates a bottleneck in the fast-developing field.
View Article and Find Full Text PDFGenetica
January 2025
Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab, Alexandria, Egypt.
The presence of Azotobacter bacteria in the soil plays an important role in increasing its fertility and enhancing plant health. Azotobacter diversity depends on several environmental factors, particularly soil texture, pH, and nutrient content. The current study investigated the diversity of Azotobacter in various soil samples collected from 10 different governorates along the river Nile valley and its delta, Northern Mediterranean shore, Sinai, and Upper Egypt regions.
View Article and Find Full Text PDFPLoS One
January 2025
Faculty of Biology, VNU University of Science, Vietnam National University, Hanoi, Vietnam.
The ribosomal genes (rDNA genes) encode 47S rRNA which accounts for up to 80% of all cellular RNA. At any given time, no more than 50% of rDNA genes are actively transcribed, and the other half is silent by forming heterochromatin structures through DNA methylation. In cancer cells, upregulation of ribosome biogenesis has been recognized as a hallmark feature, thus, the reduced methylation of rDNA promoter has been thought to support conformational changes of chromatin accessibility and the subsequent increase in rDNA transcription.
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