The linkage of hooded (h) and hood-modifier (Hm) loci was studied in the backcross of inbred rat strains (ACI X DI)F1 X DI. Four distinct hooded phenotypes were found in 128 offspring. Two had the parental phenotype and two were recombinants. The results of statistical analyses showed that the h and Hm autosomal loci are linked; the corrected distance is 47 +/- 4 cm. The Hm gene is transmitted in normal Mendelian pattern and has two alleles that manifest short (HmS) or long (HmI) pattern of the hooded pigmentation.

Animals↗

PubMedDate not supplied

Genetic polymorphism of ceruloplasmin in the rat.

The genetic heterogeneity of ceruloplasmin in serum was studied in the progeny of the (LEW X BN)F1 X (LEW X BN)F1 rats. The results of the statistical analysis showed that the Hbb and c loci were linked. However, the autosomal Ces gene was not linked to the Hbb or c loci. The Ces gene was expressed in normal Mendelian pattern and had two alleles that manifested a low (Cesl) or high (Cesh) level of the enzyme in serum. The Cesl gene was expressed as a dominant in the F1 generation. Two phenotypes CES-H and CES-L were found in the F2 rats; the females in the parental strain and hybrid had higher ceruloplasmin concentration than the male rats.

Animals↗

PubMedDate not supplied

Genetic control of blood neutrophil concentration in the rat.

Two phenotypes that characterize low and high neutrophil concentrations in blood were found in the rat. It is possible that either two regulating alleles control the high (Nr-1a) and the low (Nr-1b) neutrophil concentration or that a polygenic system affects the neutrophil concentration in blood. The F1 hybrids of four intercrosses had low neutrophil levels in blood that suggested a dominant effect of the Nr-1b allele. The backcross progeny showed abnormal segregation of the neutrophil phenotypes. The high phenotype was expressed in only 5% of the offspring. The presence of the two phenotypes and their distribution in the backcross progeny was confirmed by the computer program SKUMIX that resolved the quantitative traits into two discrete distributions with 95% and 5% representation. Because the logistic of SKUMIX can not rule out the polygenic effect, only further breeding studies using linked markers can resolve the mechanism of the genetic control of neutrophil concentration in the rat.

Alleles↗

PubMedDate not supplied

Linkage of neutrophil response to a mutagen gene (Nrm-1) to the agouti locus in the rat.

The ACI or BDIV rats responded with decreased or increased neutrophil levels in blood after the N-methyl-N-nitrosourea (MNU) administration. The F1 hybrids had decreased neutrophil counts, and the BDIV x (BDIV x ACI)F1 backcross offspring showed two phenotypes. The sex of the rats and the neutrophil response to MNU assorted independently. The results indicated that the neutrophil response to MNU was regulated by autosomal gene Nrm-1 with two alleles. The Nrm-1d regulates the decrease and the Nrm-1i regulates the increase of neutrophils in blood after the MNU administration. The results were confirmed by the SKUMIX computer program. We found that the Nrm-1 gene was linked to the agouti locus (chi-square = 10.3, P less than 0.001). The map distance between two genes was 33 +/- 5 cM. The Nrm-1 gene thus resides on the linkage group IV of the rat.

Alleles↗

PubMedDate not supplied

Size and frequency of the DNA fragments in the rearranged immunoglobulin heavy chain joining regions in the lymphocytic leukemias.

Four distinct groups of DNA fragments produced by the rearrangement of the joining regions of the immunoglobulin heavy chain gene were found after hydrolysis of the leukemic DNA with the EcoR I restriction enzyme. Three fragments were smaller than the genomic fragment (16 kb) and their average sizes were 9.6, 11.2, and 13.7 kb. The largest fragment was 18.7 kb. The fragment groups 2 and 3 (11.2 and 13.7 kb) were found in 65 per cent of the cases. There was no correlation between the fragment groups and the acute or chronic lymphocytic leukemia or B-cell lymphoma.

Base Sequence↗

PubMedDate not supplied

Identification of quantitative phenotypes in backcross and intercross offspring.

The computer program SKUMIX was used to analyze the values of quantitative traits in controlled breeding experiments using inbred rat strains. The SKUMIX program iterated parameters were used to determine the number of expected phenotypes, the values of means and their ratios in the progeny. The computer computed parameters were identical with the results calculated using the real values. The SKUMIX program may be valuable to analyze quantitative data obtained from intercross and backcross breeding experiments yielding overlapping values that cannot be individually assigned to a particular phenotype.

Animals↗