2017
DOI: 10.1159/000484423
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Abstract: The genus Colomesus is the sole representative of the family Tetraodontidae in the Amazon region. Here, Colomesus asellus was analyzed using conventional and molecular cytogenetic protocols. Its diploid chromosome number is 2n = 46 with 12 meta-, 10 submeta-, 16 subtelo-, and 8 acrocentric chromosomes and a fundamental number of FN = 84. An XX/XY sex chromosome system was identified. Mapping of 18S rDNA correlated with the nucleolus organizer regions (Ag-NORs) in the short arms of the 2 X chromosomes in female… Show more

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Cited by 12 publications
(11 citation statements)
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“…Therefore, an enlargement of the Y chromosome in this spider could be ascribed to considerable accumulation of repetitive sequences, which usually predominate in constitutive heterochromatin [67,79,80]. Cases of enlargement of sex-limited sex chromosomes due to repetitive DNA accumulation are known in several organisms [8,45,[81][82][83][84][85][86][87][88]. As described in diverse animal taxa, these sequences could even expand from the Y chromosome via ectopic recombination and/or transposition [6,[70][71][72].…”
Section: Evolution Of the X 1 X 2 Y System In Haplogyne Spidersmentioning
confidence: 79%
“…Therefore, an enlargement of the Y chromosome in this spider could be ascribed to considerable accumulation of repetitive sequences, which usually predominate in constitutive heterochromatin [67,79,80]. Cases of enlargement of sex-limited sex chromosomes due to repetitive DNA accumulation are known in several organisms [8,45,[81][82][83][84][85][86][87][88]. As described in diverse animal taxa, these sequences could even expand from the Y chromosome via ectopic recombination and/or transposition [6,[70][71][72].…”
Section: Evolution Of the X 1 X 2 Y System In Haplogyne Spidersmentioning
confidence: 79%
“…In many vertebrate groups, ITS repeat has constantly been attributed to relics of ancient chromosomal rearrangements [ 33 , 80 , 81 ]; however, ITSs exhibit a random amplification across lineages [ 80 , 82 ], and, due to their dynamic functioning [ 78 ], sometimes do not represent artifacts or ghosts of past intra/interchromosomal rearrangements. Since the most of closely related species to R. rufipes also exhibits the 2 n = 58, with very similar karyotype structure [ 5 , 7 , 42 , 47 ], the ITS present on the centromeric position of the sole metacentric pair could indeed be the result of past intrachromosomal rearrangements, but combined with the fact that these interstitial telomeric motifs are rarely found in some turtle lineages [ 79 ] and taking into account their dynamic behavior [ 78 ], it is also plausible that such ITSs may have arisen from other mechanisms, such as telomerase activity adding these motifs to nonterminal regions, duplication events, or even association with mobile elements and/or other repetitive sequences [ 83 , 84 , 85 , 86 , 87 , 88 ]. The karyotype of other South American chelids is also required to infer whether this ITS present in R. rufipes is a classical exception to the rule [ 82 ] or ITS sites are frequent and are shaping the karyotype diversity evident in Neotropical chelids.…”
Section: Discussionmentioning
confidence: 99%
“…Interestingly, as revealed here in our study, even with ancient origin, they can also be found practically intact in recent lineages, where the X and Y of R. rufipes are undistinguished from each other, with the Y sex chromosome being identified solely by comparative genomic hybridization and recruitment of several SSR motifs. The sex chromosomes may remain undifferentiated for many reasons, for example, transitions and turnovers involving XY and ZW, evolutionary advantages promoted by the recombination between XY and/or Z and W, as well as shifts involving autosomes [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , …”
Section: Discussionmentioning
confidence: 99%
“…Unlike several vertebrate species, including Caenophidian snakes, no association of rDNA sequences and the sex chromosome of S. pullatus and S. sulphureus was identified [34,63,64,65,66]. This likely implies that NORs and rDNA sites located in two microchromosomes of S. pullatus , indeed represent an atypical condition for the Spilotes clade, as almost all Colubridae, analyzed up to now, present the NORs and 18S rDNA located on a pair of macrochromosomes (often on the 2nd).…”
Section: Discussionmentioning
confidence: 99%