Cytogenetic evidences of genome rearrangement and differential epigenetic chromatin modification in the sea lamprey (Petromyzon marinus)

Abstract

This work explores both the chromatin loss and the differential genome methylation in the sea lamprey (Petromyzon marinus) from a molecular cytogenetic point of view. Fluorescent in situ hybridization experiments on meiotic bivalents and mitotic chromosomes corroborate the chromatin loss previously observed during the development of the sea lamprey and demonstrate that the elimination affects not only to Germ1 sequences but also to the rpt200 satellite DNA and most part of the major ribosomal DNA present on the germinal line. 5-Methylcytosine immunolocation revealed that the GC-rich heterochromatin is highly methylated in the germ line but significantly less in somatic chromosomes. These findings not only support previous observations about genome rearrangements but also give new information about epigenetic changes in P. marinus. The key position of lampreys in the vertebrate phylogenetic tree makes them an interesting taxon to provide relevant information about genome evolution in vertebrates.

Molecular cytogenetic characterization of chromosome site-specific repetitive sequences in the Arctic lamprey (Lethenteron camtschaticum, Petromyzontidae)

“…In other species, the 18S–28S rRNA genes were localized to the pericentromeric regions of four and two chromosomes in somatic cells of La. zanandreai 12 and P marinus , 14 respectively. These results suggest that the chromosomal location of the 18S–28S rRNA genes in lampreys is variable.…”

“…planeri [2 n  = 164], La. zanandreai [2 n  = 164]), 8 , 12 and Petromyzon marinus (2 n  = 164–168) 7 , 10 , 14 . C-positive bands were distributed in the centromeric regions of ∼30 pairs of chromosomes, which was more than the 20 pairs reported in La.…”

“…Thus, identification and comparison of site-specific repetitive sequences aids in tracing the evolutionary process of speciation. An EcoRI family of satellite DNA sequences identified in the sea lamprey Petromyzon marinus (Petromyzontidae) was the first reported in lampreys 18 and was shown to be distributed in the centromeric regions of 12 or 34 chromosomes 14 , 18 . This repetitive sequence has high AT content and contains short repeat units.…”

Current Advances in Functional Genomics in Aquaculture

“…As a result of these advances, epigenetics studies in aquaculture have tremendously increased in the last decades with the view to identifying biological markers relevant for improving the production of farmed aquatic organisms. Technologies used for epigenetics analyses in aquaculture include (i) RNA-seq in Medaka [207] and Nile tilapia [208]; (ii) genome-wide methylated DNA immunoprecipitation sequencing (MeDIP-seq) in Nile tilapia [209] and Medaka [207]; (iii) bisulite sequencing (BS-seq) in smooth tongue sole (Cynoglossus semilaevis) [210,211], rainbow trout [212] and Nile tilapia [208]; (iv) genetic linkage map analysis using simple sequence length polymorphisms (SSLPs) in medaka [213,214]; (v) methylation sensitivity ampliied polymorphism (MSAP) in Atlantic salmon [18], grass carp [215], brown trout [17], sea urchin (Glyptocidaris crenularis) [216] and sea cucumber (Apostichopus japonicas) [217]; (vi) 5-methylcytosine immunolocation in sea lamprey (Petromyzon marinus) [218]; (vii) restriction endonuclease hydrolysis of DNA using methylation enzymes in Zebraish [219] and (viii) bisulite sequencing PCR in Paciic Oyster (Crassostrea gigas) [220] and grass carp [221]. As shown in Table 3, epigenetics studies carried out this far include studies on reproduction, growth and adaptation traits.…”

Epigenetics—Potential for Programming Fish for Aquaculture?

“…Using a sequencing approach for methylation studies is advantageous because such data can also be used for identifying variations including single-nucleotide polymorphisms (SNPs) and insertion/deletion at the genome level. High Performance Capillary Electrophoresis (e.g., [28]), 5-Methylcytosine Immunolocation (e.g., [29]) and Methylation-sensitive Amplified Polymorphism (e.g., [30]) are other potentially useful methods that could be considered for non-model species where fully sequenced genomes are unavailable.…”