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Mandrioli, Mauro; Manicardi, Gian Carlo; Bizzaro, Davide; Bianchi, Umberto

doi:10.1023/a:1009215721904

Cited by 42 publications

(3 citation statements)

References 21 publications

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“…Different hypotheses attempt to explain this variation, including the terminal localization of rDNA sites that influence variation in the number of copies of the genes (Hanson et al, 1996), the occurrence of unequal crossing over and the differential amplification of intergenic sequences in NOR (nucleolar organizer regions) (Fernandes & Martins-Santos, 2006). The heteromorphism in these sites has been well documented in Megoura viciae (Aphididae) Buckton (Mandrioli et al, 1999), Drosophila (Roy et al, 2005), Maxillaria (Orchidaceae) (Cabral et al, 2006) and Salvelinus (Salmonidae) (Śiliwińska-Jewsiewicka et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Comparative molecular cytogenetics in Melipona Illiger species (Hymenoptera, Apidae)

et al. 2018

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Cytogenetic studies in Melipona are scarce with only 24 species analyzed cytogenetically. Of these, six species had the rDNA sites physically mapped and characterized by Fluorescent in situ Hybridization (fish). The aim of this study was to perform karyotype analyzes on Melipona species from different regions of Brazil, with a greater sampling representative of the Amazonian fauna and using conventional, fluorochrome staining and FISH with heterologous rDNA probes. The predominant chromosome number was 2n = 18, however, the subspecies M. seminigra abunensis and M. s. pernigra showed 2n = 22 chromosomes. The karyotypes were symmetrical, however M. bicolor, M. quadrifasciata, M. flavolineata, M. fuscopilosa, M. nebulosa presented the first pair heteromorphic in length. CMA3+ blocks also exhibited heteromorphism of size and in almost all cases coincided with rDNA sites, except for M. crinita and M. nebulosa, which presented additional non-coincident CMA3+ blocks. The CMA/ rDNA sites were terminal and interstitial in species with high heterochromatic content, and pericentromeric in those species with low heterochromatic content. In addition to pointing out cytogenetic features of cytotaxonomic importance, the reorganization of the genome in Melipona is discussed.

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Section: Discussionmentioning

confidence: 99%

Comparative molecular cytogenetics in Melipona Illiger species (Hymenoptera, Apidae)

et al. 2018

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“…Considerable efforts have focused on finding evidence of cryptic X chromosome recombination during parthenogenesis in aphids of the tribe Macrosiphini [22] , and no recombinants were found in the 1493 individuals screened at multiple X-linked loci. However, mitotic recombination has been implicated in the concentration of rDNA arrays on the ends of only one X chromosome in obligately parthenogenetic aphid lineages [20] , [23] . Whilst future experimental work is necessary to determine whether the patterns we report here are attributable to mitotic recombination within superclonal lineages, our observations are consistent with this scenario.…”

Section: Discussionmentioning

confidence: 99%

Biased Transmission of Sex Chromosomes in the Aphid Myzus persicae Is Not Associated with Reproductive Mode

2014

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Commonly, a single aphid species exhibits a wide range of reproductive strategies including cyclical parthenogenesis and obligate parthenogenesis. Sex determination in aphids is chromosomal; females have two X chromosomes, while males have one. X chromosome elimination at male production is generally random, resulting in equal representation of both X chromosomes in sons. However, two studies have demonstrated deviations from randomness in some lineages. One hypothesis to account for such deviations is that recessive deleterious mutations accumulate during bouts of asexual reproduction and affect male viability, resulting in overrepresentation of males with the least deleterious of the two maternal X chromosomes. This hypothesis results in a testable prediction: X chromosome transmission bias will increase with time spent in the asexual phase and should therefore be most extreme in the least sexual aphid life cycle class. Here we test this prediction in Myzus persicae. We used multiple heterozygous X-linked microsatellite markers to screen 1085 males from 95 lines of known life cycle. We found significant deviations from equal representation of X chromosomes in 15 lines; however, these lines included representatives of all life cycles. Our results are inconsistent with the hypothesis that deviations from randomness are attributable to mutation accumulation.

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“…However, there are only two reports of inter-specific crosses inferred by DNA analysis: Sitobion avenae × Sitobion fragariae [37] and asexual hybrid lineages of Rhopalosiphum padix cryptic species of Rhopalosiphum [38]. No satisfactory explanations on the mechanisms responsible for the variation found in the rDNA of parthenogenetic organisms such as aphids were proposed [39].…”

Section: Phylogenetic Analysismentioning

confidence: 99%

Heterogeneity in the Second Internal Transcribed Spacer (ITS2) of rDNA in the Genetically Distinct Metopolophium dirhodum Isofemale Lineages (Hemiptera: Aphididae)

Lopes-da-Silva¹,

Vieira²

2014

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The aim of this study was to investigate the level of evolutionary divergence among five isofemale lineages of Metopolophium dirhodum Walker (Hemiptera: Aphididae) using sequences of the Internal Transcribed Spacer (ITS) of ribosomal DNA (rDNA). These isofemalelineages were derived from parthenogenetic females, previously genetically characterized by having strong association of RAPD (Random Amplified Polymorphic DNA) molecular markers and host plant preference. Out of 25 sequences, only 17 containing ITS2 (the second spacer) were used for analysis due to their quality. Within 250 nucleotide sites originated by multiple alignments, 10.4% were variable, with the predominance of indels over substitutions. The average of nucleotide diversity (π) within isofemale lineages was similar to the diversity found among all isofemale lineages. The topology inferred by the Neighbor-Joining method showed that no evolutionary divergence inferred by ITS2 sequences among isofemale lineages typified by RAPD could be associated with host preference. The ITS2 sequence differences found within lineages and their causes are discussed.

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Cited by 42 publications

References 21 publications

Comparative molecular cytogenetics in Melipona Illiger species (Hymenoptera, Apidae)

Comparative molecular cytogenetics in Melipona Illiger species (Hymenoptera, Apidae)

Biased Transmission of Sex Chromosomes in the Aphid Myzus persicae Is Not Associated with Reproductive Mode

Heterogeneity in the Second Internal Transcribed Spacer (ITS2) of rDNA in the Genetically Distinct Metopolophium dirhodum Isofemale Lineages (Hemiptera: Aphididae)

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