Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

B Chromosomes in Free-Living Flatworms of the Genus Macrostomum (Platyhelminthes, Macrostomorpha)

Version 1 : Received: 8 December 2021 / Approved: 10 December 2021 / Online: 10 December 2021 (13:52:37 CET)

How to cite: Zadesenets, K.S.; Rubtsov, N.B. B Chromosomes in Free-Living Flatworms of the Genus Macrostomum (Platyhelminthes, Macrostomorpha). Preprints 2021, 2021120186 (doi: 10.20944/preprints202112.0186.v1). Zadesenets, K.S.; Rubtsov, N.B. B Chromosomes in Free-Living Flatworms of the Genus Macrostomum (Platyhelminthes, Macrostomorpha). Preprints 2021, 2021120186 (doi: 10.20944/preprints202112.0186.v1).

Abstract

B chromosomes (Bs) or supernumerary chromosomes are extra chromosomes in the species karyotype that can vary in their copy number. Bs are widespread. Usually, the Bs of specimens collected from natural populations are involved in studies. We applied another approach analyzing the Bs in animals of laboratory cultures. In this study, three species of the Macrostomum genus that underwent a recent whole-genome duplication (WGD) were involved. In laboratory lines of M. lignano and M. janickei, the frequency of Bs was less than 1%, while in the laboratory culture of M. mirumnovem, it was nearer 30%. Their number in specimens of the culture varied from 1 to 14. Mosaicism on Bs was discovered in parts of these animals. We analyzed the distribution of Bs among the worms of the laboratory cultures during long-term cultivation, the transmission rates of Bs in the progeny obtained from crosses of worms with different numbers of Bs, and from self-fertilized isolated worms. The DNA content of the Bs in M. mirumnovem was analyzed with the chromosomal in situ suppression (CISS) hybridization of microdissected DNA probes derived from A chromosomes (As). Bs mainly consisted of repetitive DNA. The cytogenetic analysis also revealed the divergence and high variation in large metacentric chromosomes (LMs) containing numerous regions enriched for repeats. The possible mechanisms of the appearance and evolution of Bs and LMs in species of the Macrostomum genus were also discussed.

Keywords

B chromosome; karyotype variation; inheritance pattern; crossing experiment; interspecific hybridization; flatworms

Subject

BIOLOGY, Other

Comments (0)

We encourage comments and feedback from a broad range of readers. See criteria for comments and our diversity statement.

Leave a public comment
Send a private comment to the author(s)
Views 0
Downloads 0
Comments 0
Metrics 0


×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.
We use cookies on our website to ensure you get the best experience.
Read more about our cookies here.