Genetic analysis of sterility in hybrids from crosses of Glossina morsitans submorsitans and Glossina morsitans centralis (Diptera: Glossinidae)

1993 ◽  
Vol 71 (10) ◽  
pp. 1963-1972 ◽  
Author(s):  
R. H. Gooding

When genetically marked Glossina morsitans submorsitans Newstead were mated to Glossina morsitans centralis Machado, viable offspring were obtained when using G. m. submorsitans females but not when using G. m. centralis females. The maternally inherited sterility factor, from G. m. submorsitans, that causes this asymmetry was inactivated or replaced during recurrent backcrossing to G. m. centralis. F1 hybrid males were sterile but most F1 hybrid females were fertile. There was little evidence for differential transmission of G. m. submorsitans and G. m. centralis chromosomes by hybrid females. Almost all backcross males were sterile if they had an X and a Y chromosome from two different taxa; the exceptional males had recombinant X chromosomes. The X chromosome locus for X/Y compatibility lies closer to the locus for esterase-X than to the locus for glucose-6-phosphate dehydrogenase. Heterozygosity in linkage group II is also a factor in causing hybrid male sterility; the locus for compatibility is closer to the locus for octanol dehydrogenase than to the locus for esterase-1. Among the backcross males that had an X and a Y chromosome from the same taxon, 12% of those obtained by backcrossing to G. m. centralis were fertile and 65% of those obtained by backcrossing to G. m. submorsitans were fertile. Backcrossing F1 hybrid females to G. m. submorsitans produced females that were equally likely to be fertilized by G. m. submorsitans and G. m. centralis. However, backcrossing to G. m. centralis produced females that had a much lower probability of being fertilized by G. m. submorsitans than by G. m. centralis.


1989 ◽  
Vol 67 (4) ◽  
pp. 869-871 ◽  
Author(s):  
R. H. Gooding

In hybrid females of Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado that carried four well-separated marker genes, suppression of intrachromosomal recombination occurred between the loci for glucose-6-phosphate dehydrogenase (G6pd) and arginine phosphokinase (Apk) on the X chromosome. Fertility of backcross females was not influenced by whether they mated with G. m. morsitans or G. m. centralis, but it was higher in females that received both of their X chromosomes from G. m. morsitans than it was in females that received one X chromosome from G. m. morsitans and the other from G. m. centralis.



Genome ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 479-485 ◽  
Author(s):  
R. H. Gooding

Glossina morsitans submorsitans Newstead and Glossina morsitans morsitans Westwood carrying two marker genes on the X chromosome, two in linkage group II, and one in linkage group III were hybridized. About 17% of the F1 and from 33 to 56% of the backcross males fertilized G. m. submorsitans, but only one F1 and two backcross males fertilized G. m. morsitans. Similarly, F1 and backcross females were fertilized by G. m. submorsitans but rarely by G. m. morsitans. Chromosomal composition of F1 and backcross males indicated that hybrid male sterility is due to incompatibility of the X chromosome from one subspecies and the Y from the other subspecies or possibly an incompatibility between X chromosomes and autosomes from different subspecies. Results are discussed in the context of a model for evolution of X and Y incompatibility and a model for evolution of maternally inherited factors that cause unidirectional sterility in males. In hybrid females, intrachromosomal recombination was suppressed in the X chromosome and in linkage group II. Fertility of backcross females, mated to G. m. submorsitans, could not be related to the chromosomal composition of the females.Key words: Glossina, hybrid sterility, tsetse, X chromosomes.



1990 ◽  
Vol 68 (8) ◽  
pp. 1727-1734 ◽  
Author(s):  
R. H. Gooding

Postmating barriers to gene flow between closely related species and subspecies of tsetse flies include (i) reduced fecundity of hybridized and hybrid females and (ii) sterility of hybrid and backcross males, owing mainly to incompatibility between X and Y chromosomes from two different taxa or, possibly, incompatibility between the X from one taxon and autosomes from the other. There are also maternally inherited factors that confer unidirectional sterility upon males; these factors may influence the direction of gene flow. When Glossina morsitans morsitans and Glossina morsitans centralis are crossed, these factors appear to be unstable and lose their effectiveness as barriers to gene flow when hybrid females, from several consecutive generations, are backcrossed to G. m. centralis. In hybrid females of the morsitans group, intrachromosomal recombination is suppressed in the X chromosomes, but it may occur at near normal levels in at least part of linkage group II. Some backcross flies with chromosomes composed of segments from two different taxa are fertile. Naturally occurring hybrids have been found, but it appears that hybridization zones are narrow. It remains to be determined whether introgression of genes plays a significant role in the evolution of tsetse flies.



1985 ◽  
Vol 63 (11) ◽  
pp. 2694-2702 ◽  
Author(s):  
R. H. Gooding

Two colonies of Glossina morsitans morsitans Westwood, two colonies of Glossina morsitans submorsitans Newstead, and one colony of Glossina morsitans centralis Machado, each originating from a different geographic location, were compared genetically and by their ability to hybridize. There were marked asymmetries in results of intersubspecific hybridization. Most F1 males were sterile but most F1 females were fertile. Nei's mean genetic identity (based on 12 loci) and four hybridization indices (based upon proportion of females fertilized, puparia produced per fertilized female, F1 adults per fertilized female, and proportion of females fertilized in backcross experiments) yielded the same results: intrasubspecific similarities are greater than intersubspecific similarities, and G. m. centralis is more similar to G. m. morsitans than it is to G. m. submorsitans. Evidence is presented indicating that a phenogram based upon allele frequencies is as good as phenograms based upon hybridization as a means of representing relationships among tsetse flies.



Genetics ◽  
1973 ◽  
Vol 74 (2) ◽  
pp. 331-342
Author(s):  
Gustavo Maroni ◽  
Walter Plaut

ABSTRACT The level of activity of the enzyme glucose-6-phosphate dehydrogenase was determinel in flies having seven different chromosomic constitutions. All those having an integral number of chromosomes [XAA, XXAA, XAAA, XXAAA, and XXXAAA (X=X chromosome, A=set of autosomes)] were found to have similar units of enzyme activity/mg live weight, while diploid females with a duplication and triploid females with a deficiency showed dosage effect. The amount of enzyme activity per cell, on the other hand, is also independent of the number of X's present but appears roughly proportional to the number of sets of autosomes.—It is proposed that dosage-compensated sex-linked genes are controlled by a positively acting regulatory factor(s) of autosomal origin. With this hypothesis it is possible to explain dosage compensation as a consequence of general regulatory mechanisms without invoking a special device which applies only to the X chromosomes.



1990 ◽  
Vol 35 (3) ◽  
pp. 219-231 ◽  
Author(s):  
J.G. Grootenhuis ◽  
R.H. Dwinger ◽  
R.B. Dolan ◽  
S.K. Moloo ◽  
Max Murray


2020 ◽  
Author(s):  
Samuel J. Widmayer ◽  
Mary Ann Handel ◽  
David L. Aylor

AbstractHybrid male sterility (HMS) contributes to reproductive isolation commonly observed among house mouse (Mus musculus) subspecies, both in the wild and in laboratory crosses. Incompatibilities involving specific Prdm9 alleles and certain Chromosome (Chr) X genotypes are known determinants of fertility and HMS, and previous work in the field has demonstrated that genetic background modifies these two major loci. We constructed hybrids that have identical genotypes at Prdm9 and identical X chromosomes, but differ widely across the rest of the genome. In each case, we crossed female PWK/PhJ mice representative of the M. m. musculus subspecies to males from a classical inbred strain representative of M. m. domesticus: 129S1/SvImJ, A/J, C57BL/6J, or DBA/2J. We detected three distinct trajectories of fertility among the hybrids using breeding experiments. The PWK129S1 males were always infertile. PWKDBA2 males were fertile, despite their genotypes at the major HMS loci. We also observed age-dependent changes in fertility parameters across multiple genetic backgrounds. The PWKB6 and PWKAJ males were always infertile before 15 weeks and after 35 weeks, yet some PWKB6 and PWKAJ males were fertile between fifteen and 35 weeks. This observation could resolve previous contradictory reports about the fertility of PWKB6. Taken together, these results point to multiple segregating HMS modifier alleles, some of which have age-related modes of action. The ultimate identification of these alleles and their age-related mechanisms will advance understanding both of the genetic architecture of HMS and of how reproductive barriers are maintained between house mouse subspecies.



1989 ◽  
Vol 9 (6) ◽  
pp. 2322-2331
Author(s):  
A H Beggs ◽  
B R Migeon

Part of the higher-order structure of chromatin is achieved by constraining DNA in loops ranging in size from 30 to 100 kilobase pairs; these loops have been implicated in defining functional domains and replicons and possibly in facilitating transcription. Because the human active and inactive X chromosomes differ in transcriptional activity and replication, we looked for differences in their chromatin loop structures. Since the islands of CpG-rich DNA at the 5' ends of X-linked housekeeping genes are the regions where functional differences in DNA methylation and nuclease sensitivity are found, we looked for scaffold association of these sequences after extraction of histones with lithium diiodosalicylate. Specifically, we examined the 5' CpG islands within the hypoxanthine phosphoribosyltransferase, glucose 6-phosphate dehydrogenase, P3, GdX, phosphoglycerate kinase type 1, and alpha-galactosidase loci in human lymphoblasts obtained from individuals with 1 to 4 X chromosomes. Although we detected no scaffold-associated regions near these genes, we found several such regions at the ornithine transcarbamylase and blood clotting factor IX loci. Our results suggest that the CpG islands are excluded from the nuclear scaffold and that even though transcriptionally active, housekeeping genes are less likely than X-linked tissue-specific genes to be scaffold associated. In all cases, the pattern of scaffold association was the same for loci on active and inactive X chromosomes.



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