title: Gene expression analysis of parthenogenetic embryonic development of the pea aphid, Acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.
abstract: Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity.
authors.affiliation: Howard Hughes Medical Institute and Department of Ecology and Evolutionary Biology, Guyot Hall, Princeton University, Princeton, NJ, 08544, United States of America; Department of Biological Science, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ, 08028, United States of America.
authors.forename: Dayalan G
authors.initials: DG
authors.lastname: Srinivasan
authors.affiliation: Department of Biological Science, Rowan University, 201 Mullica Hill Rd, Glassboro, NJ, 08028, United States of America.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Abdelhady
authors.affiliation: Howard Hughes Medical Institute and Department of Ecology and Evolutionary Biology, Guyot Hall, Princeton University, Princeton, NJ, 08544, United States of America.
authors.forename: David L
authors.initials: DL
authors.lastname: Stern
mesh_terms: D000818:Animals; D001042:Aphids / Q000196:embryology*; D005075:Biological Evolution; D017931:DNA Primers / Q000235:genetics; D004706:Endodeoxyribonucleases / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000378:metabolism*; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D009866:Oogenesis / Q000235:genetics / Q000502:physiology*; D010312:Parthenogenesis / Q000502:physiology*; D016133:Polymerase Chain Reaction; D000099257:Meiotic Recombination Protein SPO11
chemical_list: D017931:DNA Primers; D004706:Endodeoxyribonucleases; D019476:Insect Proteins; D000099257:Meiotic Recombination Protein SPO11