Venomous Loxosceles Species (Araneae, Haplogynae, Sicariidae) from Brazil: 2n♂ = 23 and X1X2Y Sex Chromosome System as Shared Characteristics

Araujo, Douglas; Schneider, Marielle Cristina; Zacaro, Adilson Ariza; Oliveira, Edson Gabriel de; Martins, Rosana; Brescovit, Antônio D.; Knysak, Irene; Cella, Doralice Maria

doi:10.2108/zs190128

Cited by 8 publications

(9 citation statements)

References 46 publications

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“…The diploid number 2n=19, the X 1 X 2 Y sex chromosome system and the chromosomal morphology predominantly metacentric herein observed in S. cariri and S. ornatus are similar to those previously described for S. tropicus and only one species of the genus Loxosceles, L. spinulosa (Král et al, 2006;Araujo et al, 2020). Additionally, the X 1 X 2 Y sex chromosome system verified in S. cariri and S. ornatus is the most common in Sicariidae, occurring in 12 out of the 15 species cytogenetically characterized so far (Araujo et al, 2020).…”

Section: Discussionsupporting

confidence: 85%

“…The genus Loxosceles presents 12 species chromosomally characterized, in which the following diploid numbers were identified: 2n♂=18 in L. reclusa Gertsch & Mulaik, 1940;2n♂=19 in L. spinulosa Purcell, 1904;2n♂=20 in L. rufipes (Lucas, 1834);2n♂=20-21 in L. rufescens (Dufour, 1820);2n♂=23 in L. amazonica Gertsch, 1967, L. gaucho Gertsch, 1967, L. hirsuta Mello-Leitão, 1931, L. intermedia Mello-Leitão, 1934, L. laeta (Nicolet, 1849, L. puortoi Martins, Knysak & Bertani, 2002, L. similis Moenkhaus, 1898and L. variegata Simon, 1897. All these species showed X 1 X 2 Y sex chromosomes system, except L. rufipes and L. reclusa that exhibited X 1 X 2 0 system (Beçak y Beçak, 1960;Diaz y Saez, 1966;Hetzler, 1979;Silva, 1988;Tugmon et al, 1990;Oliveira et al, 1996Oliveira et al, , 1997Silva et al, 2002;Král et al, 2006;Kumbiçak, 2014;Araujo et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…A cytogenetic analysis of three Sicarius species from the Brazilian fauna was accomplished in the present study, using standard staining, silver impregnation to reveal the active nucleolar organizer regions (NORs), and fluorescent in situ hybridization (FISH) with 18S rDNA probe to map the number and localization of the major ribosomal genes. Among the 21 Scytodoidea spiders karyotyped, only 10 species were examined regarding to the NOR distribution (Král et al, 2006;Araujo et al, 2008Araujo et al, , 2020. Additionally, based on the phylogenetic approach, we discussed about the chromosome evolution of Scytodoidea, focusing in the variation of diploid number, types of sex chromosome system and change in the localization of ribosomal genes.…”

Section: Introductionmentioning

confidence: 99%

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Chromosomic Studies in Zephyranthes Citrina Baker (Amaryllidaceae), a Polyploid Ornamental

Daviña

Aquino

Mata

et al. 2022

BAG

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Zephyranthes citrina is an ornamental American bulbous plant used as an ornamental garden crop for the aesthetic qualities of its yellow perigonium. The objective of this work was to characterize the species by classical chromosome staining and fluorochrome banding. A sporophytic chromosome number of 2n=8x=48 chromosomes was observed, being the karyotypic formula 20 m + 26 sm + 2 st. Satellites were detected in the short arm of metacentric chromosomes 8, 9, 11 and 12, which colocalized with constitutive heterochromatin CMA+/DAPI-/0 bands. The karyotype comprised chromosome pairs with terminal constitutive heterochromatin bands that included satellites and heteromorphic clusters indicating that it is an allooctoploid. These results will be used as a tool for monitoring genetic improvement, in interspecific crosses and its progenies and in biotechnological procedures by in vitro culture. Key words: constitutive heterochromatin, chromosome banding, bulbous, plant genetic resources, karyotype

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Section: Discussionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chromosomic Studies in Zephyranthes Citrina Baker (Amaryllidaceae), a Polyploid Ornamental

Daviña

Aquino

Mata

et al. 2022

BAG

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“…metacentric and submetacentric) chromosomes [ 9 ]. Karyotypes of many haplogynes contain the peculiar X 1 X 2 Y system (♂X 1 X 2 Y/♀X 1 X 1 X 2 X 2 ), a sex chromosome constitution that has been found in seven families [ 9 , 14 – 17 ]. Chromosomes of the X 1 X 2 Y system usually exhibit a metacentric morphology.…”

Section: Introductionmentioning

confidence: 99%

Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders

et al. 2021

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Background Despite progress in genomic analysis of spiders, their chromosome evolution is not satisfactorily understood. Most information on spider chromosomes concerns the most diversified clade, entelegyne araneomorphs. Other clades are far less studied. Our study focused on haplogyne araneomorphs, which are remarkable for their unusual sex chromosome systems and for the co-evolution of sex chromosomes and nucleolus organizer regions (NORs); some haplogynes exhibit holokinetic chromosomes. To trace the karyotype evolution of haplogynes on the family level, we analysed the number and morphology of chromosomes, sex chromosomes, NORs, and meiosis in pholcids, which are among the most diverse haplogyne families. The evolution of spider NORs is largely unknown. Results Our study is based on an extensive set of species representing all major pholcid clades. Pholcids exhibit a low 2n and predominance of biarmed chromosomes, which are typical haplogyne features. Sex chromosomes and NOR patterns of pholcids are diversified. We revealed six sex chromosome systems in pholcids (X0, XY, X1X20, X1X2X30, X1X2Y, and X1X2X3X4Y). The number of NOR loci ranges from one to nine. In some clades, NORs are also found on sex chromosomes. Conclusions The evolution of cytogenetic characters was largely derived from character mapping on a recently published molecular phylogeny of the family. Based on an extensive set of species and mapping of their characters, numerous conclusions regarding the karyotype evolution of pholcids and spiders can be drawn. Our results suggest frequent autosome–autosome and autosome–sex chromosome rearrangements during pholcid evolution. Such events have previously been attributed to the reproductive isolation of species. The peculiar X1X2Y system is probably ancestral for haplogynes. Chromosomes of the X1X2Y system differ considerably in their pattern of evolution. In some pholcid clades, the X1X2Y system has transformed into the X1X20 or XY systems, and subsequently into the X0 system. The X1X2X30 system of Smeringopus pallidus probably arose from the X1X20 system by an X chromosome fission. The X1X2X3X4Y system of Kambiwa probably evolved from the X1X2Y system by integration of a chromosome pair. Nucleolus organizer regions have frequently expanded on sex chromosomes, most probably by ectopic recombination. Our data suggest the involvement of sex chromosome-linked NORs in achiasmatic pairing.

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“…Some of these cases represent neo-sex chromosomes, which evolve by structural chromosome rearrangements between gonosomes and autosomes [18,21,[30][31][32][33][34][35]. Furthermore, the Y chromosome is involved in a peculiar X 1 X 2 Y system, which occurs in several families of haplogyne spiders [31,[36][37][38]. In all haplogynes described to date, the X 1 X 2 Y system is characterised by a specific structure and unusual achiasmatic pairing during male meiosis.…”

Section: Introductionmentioning

confidence: 99%

Patterns of Sex Chromosome Differentiation in Spiders: Insights from Comparative Genomic Hybridisation

Sember

Pappová

Forman

et al. 2020

Genes

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Spiders are an intriguing model to analyse sex chromosome evolution because of their peculiar multiple X chromosome systems. Y chromosomes were considered rare in this group, arising after neo-sex chromosome formation by X chromosome-autosome rearrangements. However, recent findings suggest that Y chromosomes are more common in spiders than previously thought. Besides neo-sex chromosomes, they are also involved in the ancient X1X2Y system of haplogyne spiders, whose origin is unknown. Furthermore, spiders seem to exhibit obligatorily one or two pairs of cryptic homomorphic XY chromosomes (further cryptic sex chromosome pairs, CSCPs), which could represent the ancestral spider sex chromosomes. Here, we analyse the molecular differentiation of particular types of spider Y chromosomes in a representative set of ten species by comparative genomic hybridisation (CGH). We found a high Y chromosome differentiation in haplogyne species with X1X2Y system except for Loxosceles spp. CSCP chromosomes exhibited generally low differentiation. Possible mechanisms and factors behind the observed patterns are discussed. The presence of autosomal regions marked predominantly or exclusively with the male or female probe was also recorded. We attribute this pattern to intraspecific variability in the copy number and distribution of certain repetitive DNAs in spider genomes, pointing thus to the limits of CGH in this arachnid group. In addition, we confirmed nonrandom association of chromosomes belonging to particular CSCPs at spermatogonial mitosis and spermatocyte meiosis and their association with multiple Xs throughout meiosis. Taken together, our data suggest diverse evolutionary pathways of molecular differentiation in different types of spider Y chromosomes.

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Venomous Loxosceles Species (Araneae, Haplogynae, Sicariidae) from Brazil: 2n♂ = 23 and X1X2Y Sex Chromosome System as Shared Characteristics

Cited by 8 publications

References 46 publications

Chromosomic Studies in Zephyranthes Citrina Baker (Amaryllidaceae), a Polyploid Ornamental

Chromosomic Studies in Zephyranthes Citrina Baker (Amaryllidaceae), a Polyploid Ornamental

Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders

Patterns of Sex Chromosome Differentiation in Spiders: Insights from Comparative Genomic Hybridisation

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