School of Biological Sciences, Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh, United Kingdom.
Published: May 2021
AI Article Synopsis
Article Abstract
Genetic conflict is considered a key driver in the evolution of reproductive systems with non-Mendelian inheritance, where parents do not contribute equally to the genetic makeup of their offspring. One of the most extraordinary examples of non-Mendelian inheritance is paternal genome elimination (PGE), a form of haplodiploidy which has evolved repeatedly across arthropods. Under PGE, males are diploid but only transmit maternally inherited chromosomes, while the paternally inherited homologues are excluded from sperm. This asymmetric inheritance is thought to have evolved through an evolutionary arms race between the paternal and maternal genomes over transmission to future generations. In several PGE clades, such as the mealybugs (Hemiptera: Pseudococcidae), paternal chromosomes are not only eliminated from sperm, but also heterochromatinized early in development and thought to remain inactive, which could result from genetic conflict between parental genomes. Here, we present a parent-of-origin allele-specific transcriptome analysis in male mealybugs showing that expression is globally biased toward the maternal genome. However, up to 70% of somatically expressed genes are to some degree paternally expressed, while paternal genome expression is much more restricted in the male reproductive tract, with only 20% of genes showing paternal contribution. We also show that parent-of-origin-specific gene expression patterns are remarkably similar across genotypes, and that genes with completely biparental expression show elevated rates of molecular evolution. Our results provide the clearest example yet of genome-wide genomic imprinting in insects and enhance our understanding of PGE, which will aid future empirical tests of evolutionary theory regarding the origin of this unusual reproductive strategy.
The memory of cellular identity is crucial for the correct development of an individual and is maintained throughout life by the epigenome. Chromatin marks, such as DNA methylation and histone modifications, ensure the stability of gene expression programmes over time and through cell division. Loss of these marks can lead to severe pathologies, including cancer and developmental syndromes.
Background: The human ZFP57 gene is a major regulator of imprinted genes, maintaining DNA methylation marks that distinguish parent-of-origin-specific alleles. DNA methylation of the gene itself has shown sensitivity to environmental stimuli, particularly folate status. However, the role of DNA methylation in ZFP57's own regulation has not been fully investigated.
This study aimed to explore the impact of genomic imprinting on the genetic variance of composite reproductive traits across three parities in Baluchi sheep. The traits analyzed included litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW). We employed a univariate linear animal model for each trait, treating performance across parities as separate traits.
To assess the suitability of genome sequencing (GS) as the second step in the diagnostics of patients with the features of 11p15.5-associated imprinting disorders (ImpDis: Silver-Russell syndrome [SRS], Beckwith-Wiedemann syndrome [BWS]), we performed short-read GS in patients negatively tested for imprinting disturbances. Obtaining a genetic diagnosis for patients with the features of these syndromes is challenging due to the clinical and molecular heterogeneity and overlap, and many patients remain undiagnosed after the currently suggested stepwise diagnostic workup.
