Growth hormone restriction fragment length polymorphisms that segregate with 42-day live weight of mice

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 235-239 ◽  
Author(s):  
Dianne C. Winkelmann ◽  
Laura D. Querengesser ◽  
Ross B. Hodgetts

The known correlation between growth hormone levels and growth rate in a number of species prompted us to examine if polymorphic restriction fragment alleles at the growth hormone locus in mice might be associated with differentiable rates of growth. An F2 population of mice was generated from crosses between a line selected for high 42-day weight and an unselected control line. The original selected and control lines exhibited mean 42-day weights of 30.6 ± 3.8 and 20.5 ± 2.6 g, respectively. Since the two lines also differed with respect to the restriction fragments detected by hybridization to a rat growth hormone cDNA probe, an analysis of the F2 generation was carried out to determine whether this polymorphism could be considered a quantitative trait locus for 42-day weight. The results of the analysis indicated that a polymorphic HindIII restriction fragment was correlated (P < 0.05) with 42-day weight. However, the allele that was positively correlated with weight was the one that was fixed in the original control line, rather than the one from the selected line. While these findings support the potential use of restriction fragment length polymorphisms in quantitative trait evaluation of livestock, they also emphasize the requirement for testing such potential quantitative trait loci in the appropriate genetic background.Key words: mice, growth rate, quantitative trait loci, restriction fragment length polymorphism.

Genome ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 404-417 ◽  
Author(s):  
James P. Prince ◽  
Edmond Pochard ◽  
Steven D. Tanksley

A molecular map of pepper (Capsicum sp.) totalling 720 cM has been constructed in an interspecific F2 cross with restriction fragment length polymorphisms and isozymes. Nineteen linkage groups were formed from 192 molecular markers. Twenty-six markers showed no linkage to any others. Twenty-eight markers showed significant deviation from expected Mendelian ratios and clustered in the genome. Two quantitative trait loci controlling the number of flowers per node were mapped to linkage group 10. The order of markers in at least 228 cM (31.7%) of the pepper genome is conserved with respect to the tomato genome, with a minimum of 15 chromosome breakage events postulated to have occurred since their divergence from a common ancestor. Comparisons of meiotic recombination in 14 conserved intervals indicates that tomato has a higher rate of recombination than does pepper in the crosses studied. Evidence suggests that centric fusions and resulting chromosome breakage events are mechanisms for genome evolution in the Solanaceae.Key words: restriction fragment length polymorphism, genome evolution, quantitative trait loci, multiple flowers, Capsicum, Lycopersicon esculentum.


1991 ◽  
Vol 69 (1) ◽  
pp. 43-48 ◽  
Author(s):  
A. M. Bork ◽  
C. M. Strobeck ◽  
F. C. Yeh ◽  
R. J. Hudson ◽  
R. K. Salmon

To evaluate the genetic relationship within and between wood and plains bison of Elk Island National Park, genomic DNA samples were screened for restriction fragment length polymorphisms (RFLP) with cDNA probes for growth hormone, growth hormone releasing factor, somatostatin, and insulin-like growth factor-1. Of the 28 fragments identified, two revealed RFLPs, both of which were associated with the growth hormone releasing factor locus. The observed frequencies of the polymorphic sites did not differ from a Hardy–Weinberg distribution in either population, which is indicative of random mating populations. The contingency χ2 tests for homogeneity indicate that the fragment frequencies of the polymorphic restriction sites differ significantly (P = 0.00) between the wood and plains bison. The number of net nucleotide substitutions between the two populations was 0.0007, indicative of a recent divergence. Conversion of the bison nucleotide divergence results in a relative protein divergence of 0.007 to 0.018. This converted divergence corresponds closely to the divergence reported for other geographically isolated populations; thus, this preliminary analysis suggests the bison have at least reached the stage of geographic isolation in their evolutionary divergence.


Genome ◽  
1992 ◽  
Vol 35 (6) ◽  
pp. 1019-1025 ◽  
Author(s):  
M. Heun

To map the genes underlying the quantitative resistance (QR) of the spring barley cultivars Proctor and Nudinka to powdery mildew, the relative pustule number of F1-derived doubled haploids (DHs) was determined and combined with the restriction fragment length polymorphism (RFLP) mapping data of these DHs via MAPMAKER/QTL. Applying a log-likelihood (LOD) threshold of 2.50, two putative quantitative trait loci (QTLs) were found in two different genome areas that accounted for 19.8% of the observed variance. One of the QR-related RFLPs (Xcnl.CDO36) is located on chromosome 1S, the other one (Xcnl.CDO749) is tightly linked with the nucleolus organizer region on chromosome 7. By comparing the means of subpopulations of DHs carrying alternative parental marker alleles, it was found that both RFLPs were also linked with some genes causing thousand kernel weight differences in this population. For the QR trait measured, LOD scores < 1.00 were found for the Mla12 region on chromosome 5S indicating that the Mla12 virulent isolate used neutralized this major resistance gene and that no residual effect of that locus occurred.Key words: barley, powdery mildew, restriction fragment length polymorphism, quantitative trait loci.


Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1711-1717
Author(s):  
D W Severson ◽  
V Thathy ◽  
A Mori ◽  
Y Zhang ◽  
B M Christensen

Abstract Susceptibility of the mosquito Aedes aegypti to the malarial parasite Plasmodium gallinaceum was investigated as a quantitative trait using restriction fragment length polymorphisms (RFLP). Two F2 populations of mosquitoes were independently prepared from pairwise matings between a highly susceptible and a refractory strain of A. aegypti. RFLP were tested for association with oocyst development on the mosquito midgut. Two putative quantitative trait loci (QTL) were identified that significantly affect susceptibility. One QTL, pgs[2,LF98], is located on chromosome 2 and accounted for 65 and 49% of the observed phenotypic variance in the two populations, respectively. A second QTL, pgs[3,MalI], is located on chromosome 3 and accounted for 14 and 10% of the observed phenotypic variance in the two populations, respectively. Both QTL exhibit a partial dominance effect on susceptibility, wherein the dominance effect is derived from the refractory parent. No indication of epistasis between these QTL was detected. Evidence suggests that either a tightly linked cluster of independent genes or a single locus affecting susceptibility to various mosquito-borne parasites and pathogens has evolved near the LF98 locus; in addition to P. gallinaceum susceptibility, this general genome region has previously been implicated in susceptibility to the filarial nematode Brugia malayi and the yellow fever virus.


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