Автор: Age. Recombination Nodules Recombination nodules (RNs) is actually thick, oval (otherwise near round) structures for the synaptonemal complex throughout the late zygotene to very early diplotene. The term recombination nodule try coined from the Carpenter [36-381 immediately after this lady comprehensive data of your own S C s regarding Drosophilu melunoguster girls, the nuts-sort of while the recombination bad mutants (elizabeth.g., mei9, mei218, and you can mei41). She found that the amount and shipments regarding RNs closely suits that from hereditary transfers. She in addition to discovered of the EM autoradiography the urban centers of your own RNs may be the web sites off repair DNA synthesis .She suggested that Rn is an enzyme cutting-edge getting hereditary recombination .She revealed two types of nodules-ellipsoidal and you will round. The brand new ellipsoidal are available first in high quantity, with the fresh new round in shorter amounts. Considering their analyses out of mei9 and you may mei218, where gene sales events and you may replace events are uncoupled, Carpenter advised the ellipsoidal nodules are coordinated into gene conversion incidents, in addition to round nodules iyi site is generally coordinated to your exchange incidents. Since that time, the brand new RNs were examined in several higher eukaryotes. Indeed, both the recombination nodules and you can chiasma let you know nonrandom chromosomal distribu-
Where research from genetic exchanges (otherwise chiasmata) arrive, the results seem to be the same; the new Rn regularity and their chromosomal metropolises usually fits that from chiasma frequency and their chromosomal locations
tion and you can positive interference, that’s a professional hereditary occurrence. The fresh RNs have been assessed in a few fungus [25,31,35,75,178,221].Whcn the chiasmata is counted, as in the situation out-of Sorduriu, its number frequently buy into the quantity of RNs; there are 18-19 chiasmata from the diplotenediakinesis, there is actually 18-19 RNs on pachytene and you will diplotene SCs. Overall, the content on the exchange volume and their withdrawals is actually decreased. Nevertheless, this new Rn shipment is definitely nonrandom, and positive interference are shown. From inside the Neurosporu, Bojko revealed two types of RNs; the first nodule (spherical) was at random marketed due to the fact later one to (ellipsoidal) is nonrandomly delivered. The newest morphological difference isn’t therefore noticeable regarding facial skin pass on plans [120a]; most RNs be seemingly distally discover. In the Coprinus, the amount of RNs try higher at the midzygotene, in addition they exhibit a haphazard shipments; such number try less nearly because of the half of (from 46 in order to twenty six) within middle-late pachytene, and so they display a nonrandom delivery. Comparable email address details are found in Schizophyllum and you may Sordariu. Once more, brand new commonplace towns and cities could be the telomere countries [thirty-five,178,221].
F. The question away from Homology Search Most of the observations suggest the newest opinion that Sc while the meiotic amount of recombination are intimately relevant
This new South carolina becomes necessary to the noticed meiotic levels of hereditary recombination. You will be able that Sc serves as an excellent “cast” or a great zipper to hold homologues with her for enough time to allow recombination processes to start working . Mutants that are faulty on the system from SCs also are defective from inside the meiotic recombination. The latest converse is not genuine; mutants that will be defectivein meiotic recombination have normal SCs, since the recombination means state-of-the-art enzymatic tips. Examples include mei9 regarding Drosophila melunogaster ,usy2-17 from S.macrospora , and you will rud52 away from S. cerevisiae . Inquiries was indeed raised if or not 1.)SCs come before initiation out of recombination, dos.) the fresh initiation off recombination will come before assembly out-of SCs, otherwise 3.) both incidents try parellel. Out of various findings, it is clear your synthesis out of healthy protein parts as well as their system towards the axial cores and main aspects will be very early actions. With out them, meiotic recombination is even faulty. For the D. melanogaster, females homozygous into the mutation c(3)G don’t means SCs, and you may meiotic recombination is actually considerably smaller; the fresh gametes brought are typically inviable . Inside the yeast, diploid homozygous for hopl and additionally doesn’t means SCs which will be defective when you look at the meiotic crossovers and you may gene sales, but mitotic and you will intrachromosomal recombinations commonly affected. The fresh hopl mutation affects fungus meiosis you might say analogous so you can compared to the latest c(3)G mutation from Drosophila . Thus the fresh HOP1 gene in the S. cerevisiae is essential towards South carolina construction, and it requirements to have a necessary protein element of the newest lateral function .
