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Biomedical subjects

J S Otis

Publications and source records attributed to J S Otis.

11 recordsLinked to original sources
PubMed1996

Gene mapping by chromosome microdissection and microisolation in the chicken.

A chromosome microdissection and microisolation technique in combination with filter hybridization was developed for chromosomal localization of cloned chicken genes. The DNA was obtained from microdissected chromosome regions of metaphase spreads. Dissected DNA was amplified by polymerase chain reaction (PCR). The chicken MHC gene located on the nucleolar chromosome and beta-actin gene located on chromosome 2q were chosen as tests for the procedure and then detected by dot blot analysis using amplified chromosomal DNA probed with biotinylated DNA. The study establishes the technique of using chromosome microdissection and microisolation for localization of cloned genes as a complementary or alternative approach to both in situ DNA/chromosome hybridization and fluorescent in situ hybridization.

Actins↗
PubMed1993

Association of dominant marker traits and metric traits in chickens.

This study was initiated to determine whether an allelic substitution of a dominant marker gene would identify a region close to a locus affecting expression in a metric trait. The rationale for the experiment was to utilize disequilibrium between a multiple recessive randombred Rhode Island Red (RRc) stock previously selected for quantitative trait performance and an unimproved dominant marker stock (MDM). The reporter genes in the MDM were: barring (B), silver (S), creeper (Cp), rose comb (R), double uropygial gland (U), crest (Cr), dominant white (I), frizzle (F), duplex comb (D), multiple spurs (M), polydactyly (Po), blue egg (O), pea comb (P), naked neck (Na), extended black (E), white skin (W+), muffs and beard (Mb), and feathered shanks (Fsh). Appropriate reciprocal crosses of MDM with RRc and F1 to RRc produced segregating full sibs that were evaluated for association with reporter traits. Carriers of Cr, I, and F were significantly later in sexual maturity than their recessive full sibs. The pleiotropic effects of F are believed to account for the later maturity. None of the marker traits had a significant association with egg numbers or egg weight. Birds expressing E were distinctly heavier at 8 and 32 wk. There is no obvious explanation for the significant larger size for the E phenotype. The CR-I-F phenotypes were significantly smaller at 32 wk than noncarrier full sibs.

Alleles↗
PubMed1990

Cryopreservation of semen from unique lines of chicken germ plasm.

Frozen semen is a practical means of preserving valuable germ plasm. Monitored samples of semen cryopreserved with glycerol for heterozygous, dominant marker stocks and for nine chromosomal rearrangement lines had sufficiently high fertility for germ-line retrieval. The results also indicated a potential for the genetic selection of certain lines for the freezability of spermatozoa, since stock and line differences in fertility occurred when previously frozen semen was used for insemination. Freezing the semen of stocks routinely reproduced provides insurance against possible disasters.

Animals↗
PubMed1990

Borate G-banding technique applicable to in situ deoxyribonucleic acid/deoxyribonucleic acid hybridized chicken chromosomes.

The borate G-banding technique produced excellent longitudinal bands similar to trypsin G-bands on chicken chromosomes prepared from embryo material. Aged chromosome preparations on slides were pretreated in borate buffer (pH 9.2) for 10 to 30 s at 37 C, then stained in Giemsa solution. This simple G-banding procedure gave high-resolution chromosome banding and permitted the visualization of silver grains that localized cloned gene sequences or cloned DNA fragments to specific regions by in situ hybridization.

Animals↗
PubMed1989

Restriction enzymes MspI, HpaII, HaeIII, and HinfI applied to chicken mitotic chromosomes.

The restriction enzymes MspI, HpaII, HaeIII, and HinfI were applied in situ to chicken metaphase chromosomes to determine if they denatured specific regions to produce banding patterns. Human metaphase chromosomes were treated simultaneously to serve as controls. The MspI, HpaII, and HaeIII enzymes produced no visible banding patterns in chicken chromosomes. There was slight banding on a few chromosomes in HinfI preparations, which was similar to the occasional spontaneous banding observed in chicken chromosome preparations. The results indicate that these four enzymes do not denature C-band regions in sufficient magnitude to be detected in chicken metaphase chromosomes.

Animals↗
PubMed1982

Recombinant inversion chromosomes in phenotypically normal chickens.

Some progeny resulting from interbreeding of individuals heterozygous for a pericentric inversion of chromosome 1 in the chicken have the two complementary types of recombinant chromosomes arising from a single crossing-over within the inverted segment. These individuals are capable of reproduction. Their progeny can have one or the other of the two recombinant chromosomes or, if crossing-over occurs, either a normal or an inversion chromosome.

Animals↗
PubMed1980

Mapping of the genes for pea comb, blue egg, barring, silver, and blood groups A, E, H, and P in the domestic fowl.

Five chromosomal rearrangements involving chromosome 1 were utilized to test linkage relationships of the blue egg--pea comb--naked neck (O-P-Na) linkage group. An F1 stock was created by crossing rearrangement carriers with individuals carrying the traits being studied. The F1 was then backcrossed to recessive, normal chromosome tester stocks. Chromosomal and phenotypic descriptions were made for each of the segregating progeny. Significant linkage relationships were shown for blue egg and pea comb on the proximal one third of the short (p) arm of chromosome 1. No linkage was found for naked neck. Barring and silver were tested against the two arms of the Z (sex) chromosome, and the linkage values suggest that these loci are on opposite arms. Blood group loci linkages between Ea-H and W4, Ea-P and Na, and Ea-A and Ea-E were confirmed. However, no linkage was observed between these loci and the marker rearrangements on the p arm of chromosome 1.

Animals↗
PubMed1980

An autosomal recessive blind mutant in the chicken.

A type of blindness due to lack of rods and cones in the retina was found to be controlled by a single autosomal recessive gene, rc. The mutation was first identified in the second generation descendants of a male carrying an ethyl methanesulfonate (EMS) induced chromosome translocation involving one arm of the Z sex chromosome and the long (q) arm of chromosome 3. A linkage test between the locus causing the blindness and the translocation break-point on chromosome 3 was not significant. There is no proof that the mutation was EMS induced.

Animals↗
PubMedDate not supplied

Estimating meiotic disjunction frequencies in chicken translocation heterozygotes based on embryonic mortality.

Chickens heterozygous for a chromosomal translocation [MN t(1;4)] were intercrossed and the progeny were analyzed for their chromosome complement. A ratio of 1 homozygous translocation carrier to 4 heterozygous translocation carriers to 1 homozygous standard chromosome carrier was noted (n = 520), rather than the 1:2:1 ratio expected from Mendelian segregation. The excess of heterozygous carriers was apparently caused by union of complementary duplication/deficient gametes. Embryonic death occurred in 68% of fertile zygotes. This finding fits very closely to expectations if alternate and adjacent meiotic disjunctions occurred at equal frequencies. As alternate disjunction frequencies increase from 0.5 to 1.0 in inter se matings, the proportion of inviable zygotes among fertilized ova will decrease from 0.625 to 0 and the proportion of translocation heterozygotes among viable progeny will decrease from 0.667 to 0.5. In instances where alternate and adjacent disjunction occur at equal frequency, preferential recovery of translocation carriers will occur. This may contribute to chromosomal diversity within a species, and possibly lead to speciation.

Animals↗