Malinovskaya LP, Tishakova KV, Bikchurina TI, Slobodchikova AY, Torgunakov NY, Torgasheva AA, Tsepilov YA, Volkova NA, Borodin PM. Negative heterosis for meiotic recombination rate in spermatocytes of the domestic chicken Gallus gallus.
Vavilovskii Zhurnal Genet Selektsii 2021;
25:661-668. [PMID:
34782886 PMCID:
PMC8558918 DOI:
10.18699/vj21.075]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/24/2022] Open
Abstract
Benef its and costs of meiotic recombination are a matter of discussion. Because recombination breaks
allele combinations already tested by natural selection and generates new ones of unpredictable f itness, a high
recombination rate is generally benef icial for the populations living in a f luctuating or a rapidly changing environment
and costly in a stable environment. Besides genetic benef its and costs, there are cytological effects of recombination,
both positive and negative. Recombination is necessary for chromosome synapsis and segregation. However,
it involves a massive generation of double-strand DNA breaks, erroneous repair of which may lead to germ
cell death or various mutations and chromosome rearrangements. Thus, the benef its of recombination (generation
of new allele combinations) would prevail over its costs (occurrence of deleterious mutations) as long as the population
remains suff iciently heterogeneous. Using immunolocalization of MLH1, a mismatch repair protein, at the
synaptonemal complexes, we examined the number and distribution of recombination nodules in spermatocytes
of two chicken breeds with high (Pervomai) and low (Russian Crested) recombination rates and their F1 hybrids and
backcrosses. We detected negative heterosis for recombination rate in the F1 hybrids. Backcrosses to the Pervomai
breed were rather homogenous and showed an intermediate recombination rate. The differences in overall recombination
rate between the breeds, hybrids and backcrosses were mainly determined by the differences in the crossing
over number in the seven largest macrochromosomes. The decrease in recombination rate in F1 is probably
determined by diff iculties in homology matching between the DNA sequences of genetically divergent breeds. The
suppression of recombination in the hybrids may impede gene f low between parapatric populations and therefore
accelerate their genetic divergence.
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