Data Mining Identifies Differentially Expressed Circular RNAs in Skeletal Muscle of Thermally Challenged Turkey Poults

Genomic scans for selection and runs of homozygosity in southern Italian turkey populations

Basilicata and Apulian (BAS-APU) turkeys, a native population in the Basilicata and Puglia regions of southern Italy, are known for their high meat quality and tolerance to local conditions. Understanding the genomic patterns of BAS-APU turkeys is critical for effective breeding and preservation strategies. In this study, we characterized runs of homozygosity (ROH), and selection signatures using the integrated haplotype score (iHS) and ROH approaches. A total of 73 BAS-APU turkeys from five populations were sequenced (12X). The inbreeding coefficients based on ROH ranged from 0.177 to 0.405. A total of 120,956 ROH were detected in BAS-APU populations. We identified 27 genomic regions that harbor 61 candidate genes in ROH islands in which single nucleotide polymorphisms (SNPs) occur in more than 90 % of individuals. In addition, we detected 608 genomic regions under positive selection using the iHS method being 104, 98, 130, 102, and 174 for BAS, APU_C, APU_M, APU_PN, and APU_PS, respectively. For both methods, most of the genes within these regions are related to production performance, reproduction, immune responses, and adaptation. This study contributes significantly to our understanding of the genetic makeup of native turkey populations in southern Italy. The identified genes under selection can aid future breeding and conservations programs for southern Italian native turkeys. The results of inbreeding levels, especially in the absence of complete pedigrees or when only a few samples are available, which is often the case for local breeds, will help to avoid genetic relatedness in the mating plan in breeding and conservation plans for BAS-APU populations. Also, the detected genes in the selective sweep regions could be used as a marker-assisted selection to improve productive traits and adaptation of BAS-APU local populations.

Circular RNA expression in turkey skeletal muscle satellite cells is significantly altered by thermal challenge

Introduction

Understanding the genetic mechanisms behind muscle growth and development is crucial for improving the efficiency of animal protein production. Recent poultry studies have identified genes related to muscle development and explored how environmental stressors, such as temperature extremes, affect protein production and meat quality. Non-coding RNAs, including circular RNAs (circRNAs), play crucial roles in modulating gene expression and regulating the translation of mRNAs into proteins. This study examined circRNA expression in turkey skeletal muscle stem cells under thermal stress. The objectives were to identify and quantify circRNAs, assess circRNA abundance following RNAse R depletion, identify differentially expressed circRNAs (DECs), and predict potential microRNA (miRNA) targets for DECs and their associated genes.

Materials and methods

Cultured cells from two genetic lines (Nicholas commercial turkey and The Ohio State Random Bred Control 2) under three thermal treatments: cold (33°C), control (38°C), and hot (43°C) were compared at both the proliferation and differentiation stages. CircRNA prediction and differential expression and splicing analyses were conducted using the CIRIquant pipeline for both the untreated and RNase R depletion treated libraries. Predicted interactions between DECs and miRNAs, as well as the potential impact of circRNA secondary structure on these interactions, were investigated.

Results

A total of 11,125 circRNAs were predicted within the treatment groups, between both untreated and RNase R treated libraries. Differential expression analyses indicated that circRNA expression was significantly altered by thermal treatments and the genetic background of the stem cells. A total of 140 DECs were identified across the treatment comparisons. In general, more DECs within temperature treatment comparisons were identified in the proliferation stage and more DECs within genetic line comparisons were identified in the differentiation stage.

Discussion

This study highlights the significant impact of environmental stressors on non-coding RNAs and their role in gene regulation. Elucidating the role of non-coding RNAs in gene regulation can help further our understanding of muscle development and poultry production, underscoring the broader implications of this research for enhancing animal protein production efficiency.

The emerging role of circRNAs on skeletal muscle development in economical animals

CircRNAs are a novel type of closed circular molecules formed through a covalent bond lacking a 5'cap and 3' end tail, which mainly arise from mRNA precursor. They are widely distributed in plants and animals and are characterized by stable structure, high conservativeness in cells or tissues, and showed the expression specificity at different stages of development in different tissues. CircRNAs have been gradually attracted wide attention with the development of RNA sequencing, which become a new research hotspot in the field of RNA. CircRNAs play an important role in gene expression regulation. Presently, the related circRNAs research in the regulation of animal muscle development is still at the initial stage. In this review, the formation, properties, biological functions of circRNAs were summarized. The recent research progresses of circRNAs in skeletal muscle growth and development from economic animals including livestock, poultry and fishes were introduced. Finally, we proposed a prospective for further studies of circRNAs in muscle development, and we hope our research could provide new ideas, some theoretical supports and helps for new molecular genetic markers exploitation and animal genetic breeding in future.

Circular RNA Profiles in Viremia and ART Suppression Predict Competing circRNA–miRNA–mRNA Networks Exclusive to HIV-1 Viremic Patients

Since the onset of the HIV-1/AIDS epidemic in 1981, 75 million people have been infected with the virus, and the disease remains a public health crisis worldwide. Circular RNAs (circRNAs) are derived from excised exons and introns during backsplicing, a form of alternative splicing. The relevance of unconventional, non-capped, and non-poly(A) transcripts to transcriptomics studies remains to be routinely investigated. Knowledge gaps to be filled are the interface between host-encoded circRNAs and viral replication in chronically progressed patients and upon treatment with antiviral drugs. We implemented a bioinformatic pipeline and repurpose publicly archived RNA sequence reads from the blood of 19 HIV-1-positive patients that previously compared transcriptomes during viremia and viremia suppression by antiretroviral therapy (ART). The in silico analysis identified viremic patients’ circRNA that became undetectable after ART. The circRNAs originated from a subset of host genes enriched in the HDAC biological pathway. These circRNAs and parental mRNAs held in common a small collection of miRNA response elements (MREs), some of which were present in HIV-1 mRNAs. The function of the MRE-containing target mRNA enriched the RNA polymerase II GO pathway. To visualize the interplay between individual circRNA–miRNA–target mRNA, important for HIV-1 and potentially other diseases, an Interactive Circos tool was developed to efficiently parse the intricately competing endogenous network of circRNA–miRNA–mRNA interactions originating from seven circRNA singled out in viremic versus non-viremic patients. The combined downregulation of the identified circRNAs warrants investigation as a novel antiviral targeting strategy.