The molecular basis of meiotic crossover distribution

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My laboratory has identified the molecular basis of a gene responsible for establishing the distribution of crossover events in meiosis of Caenorhabditis elegans.  This is a significant result because the phenotype o rec-1 is unique in that it alters the position of the measured crossover event without any other measurable effects on frequency of recombination, fecundity or developmental processes.  A notable feature of the rec-1 gene is that it is poorly conserved at the level of primary sequence with other species, even though all species characterized to date show a meiotic pattern, which is another way of saying that the distribution of crossing over is not uniform along a chromosome.  There are a number of explanations for this apparent paradox; however the hypothesis that will be tested here is that rec-1 is an example of a***meiosis-specific function that is conserved functionally, but not in its primary sequence.  The rationale for this proposal is that it is selectively advantageous for a species to protect its meiotic functions from cross-speciation using species-specific molecules to perform the processes involved in the basic biological function of meiosis.  A process widely used by all sexually reproducing individuals.******In order to test this hypothesis, the proposed orothologs will be identified in closely related species. This will be achieved by examining the genes flanking rec-1, which are conserved.  Using these flanking genes to find the syntenic region where rec-1 is situated in C. elegans, we will look for a coding region in the position where we expect rec-1 to be.  We have done some preliminary experiments and found that there is a coding region in the expected location, but one that is not highly conserved sequence-wise with rec-1. To confirm that the coding region corresponds to the rec-1 gene, we will characterize it in the closely related species, C. briggsae.  The gene in C. briggsae will be mutated (knocked out) using the CRISPR system.  The C. briggsae mutant knock-out and the wild-type strain will be characterized with regard to the distribution of crossing over along an orthologous chromosome. There are mutant strains in C. briggsae that identify orthologous genes to those in C. elegans and the wild-type strain has been sequenced and characterized with regard to synteny with C. elegans.  So the basic tools are available to address the question of whether or not the proposed ortholog performs the same function in the two species.  ******In addition, we will investigate how the meiotic pattern is established by identifying interacting partners with the REC-1 protein.  To do this we will take both a genetic approach, examining gene interactions with known meiotic functions along with a molecular approach to identify protein interactions.  In this way characterize the molecular basis responsible for a phenomenon that has been the object of a long-standing, out-standing question in biology.****** *****