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J J Bitgood

Publications and source records attributed to J J Bitgood.

34 records · Page 2Linked to original sources
PubMed1987

Studies of the pirouette mutation. 1. Lack of linkage association with marked regions of chromosomes 1 and 2.

The pirouette mutation was tested for possible genetic linkage with naked neck, tardy feathering, the MN t(Z;1) chromosome rearrangement, all assigned to distinctly different regions of Chromosome 1, and the OH inv(2) chromosome rearrangement and shankless (associated with the OH inv(2) rearrangement). No linkage associations were found in any of these tests. This eliminates specific regions of Chromosomes 1 and 2 as possible locations for the pirouette mutation.

Animals↗
PubMed1987

Studies of the pirouette mutation. 2. A detrimental phenotypic interaction with naked neck.

During a study to determine if any genetic linkage existed between the chicken mutations pirouette and naked neck, it was found that when both traits are expressed simultaneously in an individual, an "automutilation" condition can be created in some cases. The tremulous head movements of naked neck-pirouette chicks cause scraping of the skin on the neck against the egg shell during hatching, resulting in lacerations of the neck in varying degrees. Because of this potential for injury, it is suggested that matings between carriers of tremulous neurological disorders and carriers of mutations that result in lack of down cover be avoided whenever possible.

Animals↗
PubMed1987

Lighting and sex ratio for breeding ringnecked pheasants in confined housing.

In two trials with breeding pheasants, pheasants were assigned to two male:female sex ratios (1:12 and 1:18) arranged factorially with two lighting regimens (14 or 16 hr of light) in a 24-hr period. In each trial, 1644 or 1680 pheasant hens divided in two replicates were assigned to each experimental treatment and placed in controlled environment housing. Hen mortality, percent culled eggs, total eggs per hen-housed, fertility, hatchability, and usable chicks per hen-housed were determined over a 9-week production period. Although mortality and percent hatch were not affected by either sex ratio or lighting, percent culled eggs increased with increased light (16 hr light) and usable chicks per hen-housed decreased with increased light. Increasing the sex ratio from 1:12 to 1:18 increased egg production but decreased fertility. These data demonstrate that pheasants reared in a controlled environment require less than 16 hr light for maximizing usable chick production per hen-housed and there is a trade-off between fertility and egg production.

Animals↗
PubMed1985

Relationship of plasma estradiol and progesterone levels to egg productivity in domestic chicken hens.

Female chickens from eight different genetic stocks, ranging from 13 to 21 months of age, and exhibiting various levels of egg production were studied. Plasma samples were collected between 1700 and 2200 hr to determine basal circulating levels of progesterone (P4) and 17 beta-estradiol (E2) by radioimmunoassay. Linear regression analysis was used to describe the relation between mean hormone levels (E2, P4, and E2/P4) and mean egg production from these groups, and correlation coefficients were used to evaluate the general usefulness of these hormone parameters for estimating egg production within a group or flock of hens. Of the three hormone parameters evaluated, basal circulating E2/P4 was found to be the best estimator of egg productivity.

Animals↗
PubMed1985

Additional linkage relationships within the Z chromosome of the chicken.

Genetic linkage tests were conducted using four Z-linked loci and three Z-linked chromosome rearrangements (interchanges). Z-linked recessive white skin (y) segregated independently from the Z-linked barring (B) and silver (S) loci. A map distance of 18.2 +/- 3.2 was found between y and the MN t(Z;1) interchange. A previous report had shown that B was located 22 map units from this interchange, therefore, because B and y were found not to show measurable recombination, the linear order is B-interchange-y. The MN t(Z;3) interchange was tested against S, and no recombinants were recovered in 217 backcross progeny, indicating very close genetic linkage. The NM 7659 t(Z;1) interchange was tested against the dermal melanin locus (id+) and independent assortment was noted. This supports other work that has shown that the S and id+ loci lie on opposite arms of the Z chromosome. Evidence is reviewed that supports the concept that S and the NM 7659 and MN t(Z;3) interchange break points are located on the short arm, while B, id+, y, and the MN t(Z;1) interchange break point are located on the long arm of the Z chromosome.

Animals↗
PubMed1984

A study of linkage relationships of blood group P with naked neck, silkie feathering, and recessive white in chicken.

Linkage relationships of blood group P (Ea-P), naked neck (Na), silkie feathering (h), and recessive white plumage (c) were studied to attempt to clarify the h-Na-Ea-P region of linkage group III of the chicken. The Na-Ea-P linkage values obtained in this test agreed with previous reports, and pooled data were used to recalculate a map distance of 27.9 +/- 2.3 map units between these two loci. A significant chi square for linkage was calculated between Na and c; however, because of the relatively low numbers of progeny tested, the high linkage value calculated, and the absence of detectable linkage between c and the other marker genes, this was probably a chance deviation. All other linkage relationships appeared negative, supporting the current suggested linear order of these loci as h-Na-Ea-P with c not being in this chromosomal region.

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↗
PubMed1981

Effect of dietary zearalenone on reproduction of chickens.

Variable quantities of zearalenone (0, 10, 25, 50, 100, 200, 400, or 800 mg/kg diet) were incorporated into a practical laying hen diet and fed to 30-week-old White Leghorn females in egg production. During the 3 week pretest and 8 week experimental periods hens were inseminated weekly with .05 ml of pooled semen from males fed normal diets. Zearalenone was without effect on egg production, egg size, feed consumption, change in body weight, fertility, hatchability of fertile eggs, growth of progeny to 3 weeks of age, comb, weight, oviduct weight, heart weight, liver weight, spleen weight, egg shell thickness, Haugh units, blood hematology, serum calcium, serum inorganic phosphorus, and serum alkaline phosphatase. Zearalenone above 50 mg/kg of diet caused reduced serum cholesterol. In a reciprocal study, adult male New Hampshire chickens were fed diets containing 0, 100, or 800 mg/kg zearalenone for an 8 week period. Semen was collected and inseminated into White Leghorn females fed normal diets. Zearalenone was without effect on fertility or hatch of fertile eggs resulting from matings of these males. Zearalenone resulted in reduced serum inorganic phosphorus, serum cholesterol, and serum alkaline phosphatase in males. Histological examination of a number of tissues in both males and females revealed no changes due to zearalenone feeding. It is concluded that zearalenone up to 800 mg/kg of diet is without effect on reproductive performance of mature chickens.

Animal Feed↗
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↗
PubMedDate not supplied

A new recessive ametapodia mutation in the chicken (Gallus domesticus).

An apparently new mutation that is associated with abnormal limb development appeared in a strain of Light Brown Leghorn chickens. Mutants are characterized by the complete absence of the tarsometatarsals, while severely hypoplastic development of the metacarpals is also present. The phenotype of the new mutant (ametapodia-2) closely resembles ametapodia-1, described in 1967, but ametapodia-2 is inherited as an autosomal recessive (AMET*A), while ametapodia-1 was associated with an incompletely dominant gene (MP*A). Only heterozygous ametapodia-1 (MP*N/MP*A) were viable and able to reproduce, while homozygous ametapodia-2 mutants do not normally survive beyond 2-4 days of age. The shankless mutation (SHL*S) also reduces development of the metatarsal and metacarpal bones and has been shown to be associated with a pericentric inversion of chromosome 2. No obvious cytologic abnormality was apparent in ametapodia-2 birds, and offspring of a cross between AMET*A carriers and shankless birds were normal, indicating that the two mutations are not alleles. Ametapodia-1 (MP*A) was found to be linked to the rose comb locus (R) by 16 crossover units. Linkage test matings between AMET*A and (R*R) showed independent segregation, strongly suggesting that the mutation occurred at a relatively distant locus and therefore is probably not allelic to MP*A.

Animals↗
PubMedDate not supplied

Pop-eye: an inherited Z-linked keratoglobus in the chicken.

A Z-linked recessive mutation in the domestic fowl is reported that results in a keratoglobus of both eyes. It does not appear to have any effect on the vision of affected individuals. The keratoglobus is not noticeable at hatching, but becomes obvious by 5-6 weeks of age. The mutant has been designated pop-eye, gene symbol pop. Initial studies suggest linkage with the late feathering (K) locus, and with the NM 7092 t (Z;1) translocation, which had previously been shown to be closely linked with Z-linked silver (S). There appear to be no other detrimental effects associated with this mutant. Preliminary analysis of T3 and T4 thyroid hormone levels do not indicate any thyroid malfunction.

Animals↗
PubMedDate not supplied

Tardy feathering locus (t) located on chromosome 1 in the chicken.

The locus for tardy feathering (t), a recessive autosomal rate of feathering mutation, had been previously suggested to be on chromosome 1 in the chicken. Tests using both pea comb (P) and the breakpoint (B) of a chromosome translocation involving chromosome 1 (MN t(Z;l] verify that t lies on the long arm of chromosome 1, and shows linkage of 41.7 +/- 2.2 map units, with P located on the short arm.

Animals↗