Month: September 2022

PIWI-INTERACTING RNAS. (piRNAs) "are derived from various repetitive elements of the genome, such as centromeric and telomeric heterochromatin, and are very rich in sequences cognate to all classes of transposable elements. Approximately one million piRNA molecules have been reported per spermatocyte or round spermatid." (Munshi A, Mohan V and Ahuja YR). View in LinkedIn

PIWI FUNCTIONS. "Although the exact function and targets of piRNAs are unclear, piRNAs ensure genomic stability in the germline by silencing selfish genetic elements like transposons by heterochromatin formation." (piRNAs = PIWI-interacting RNAs). (Munshi A, Mohan V and Ahuja YR View in LinkedIn

JUMPING GENE DEFENSE. "Retrotransposable elements comprise around 50% of the mammalian genome. piRNAs are produced from inactive transposable elements through a ping-pong mechanism and form a surveillance system against active transposable element invasion and silence their activities by antisense targeting their mRNA. piRNAs can significantly increase the fitness of organisms by reducing the fitness of retrotransposons." (Munshi A, Mohan V and Ahuja YR). View in LinkedIn

KEY FACT. "Transcription actually occurs essentially everywhere, including both coding regions and non-coding regions, and often on both strands." (Munshi A, Mohan V and Ahuja YR). View in LinkedIn

LONG NON-CODING RNAS. "Recently, (studies) have shown the interplay between the expression of two long ncRNAs, transcribed on opposite strands, which can exert epigenetic metastatic control on the transcription of the adjacent protein-encoding FLOW11 gene in yeast (Sacchoromyces cerevisiae). This regulatory mechanism has a profound effect on the life cycle of yeast." (Munshi A, Mohan V and Ahuja YR). View in LinkedIn

"GENOMIC IMPRINTING is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed. If the allele from the mother is imprinted, then only the allele from the father is expressed." https://lnkd.in/dWAQheg View in LinkedIn

NON-MENDELIAN INHERITANCE. "Forms of genomic imprinting have been demonstrated in fungi, plants and animals. As of 2014, there are about 150 imprinted genes known in the mouse and about half that in humans." https://en.m.wikipedia.org/wiki/Genomic_imprinting View in LinkedIn

GENE CLUSTERS. "Genomic imprinting is a cis acting epigenetic process by which a subset of autosomal genes is not expressed in a parent of origin-specific manner. In mammals approximately 100 such genes clustered in 25 regions have been identified. A typical imprinted cluster consists of 2-12 protein coding genes, and at least one long ncRNA, which is usually expressed from the maternal allele and invariably shows bidirectional reciprocal expression to the coding genes." View in LinkedIn

Ref for non-cited article: Non-Coding RNAs: A Dynamic and Complex Network of Gene Regulation" "Munshi A Mohan V and Ahuja YR View in LinkedIn

GENE CLUSTER CONTROL. "A key feature of imprinted gene clusters is the presence of an imprint control element (ICE). The ICE is epigenetically modified only on one parental chromosome by a DNA methylation ‘imprint’, which is acquired during maternal or paternal gametogenesis and is maintained on the same chromosome in the diploid embryo."" "Munshi A, Mohan V and Ahuja YR View in LinkedIn