Large changes in detected selection signatures after a selection limit in mice bred for voluntary wheel-running behavior.

In various organisms, sequencing of selectively bred lines at apparent selection limits has demonstrated that genetic variation can remain at many loci, implying that evolution at the genetic level may continue even if the population mean phenotype remains constant. We compared selection signatures at generations 22 and 61 of the "High Runner" mouse experiment, which includes 4 replicate lines bred for voluntary wheel-running behavior (HR) and 4 non-selected control (C) lines. Previously, we reported multiple regions of differentiation between the HR and C lines, based on whole-genome sequence data for 10 mice from each line at generation 61, which was >31 generations after selection limits had been reached in all HR lines.

Genetic Basis of Aerobically Supported Voluntary Exercise: Results from a Selection Experiment with House Mice.

The biological basis of exercise behavior is increasingly relevant for maintaining healthy lifestyles. Various quantitative genetic studies and selection experiments have conclusively demonstrated substantial heritability for exercise behavior in both humans and laboratory rodents. In the "High Runner" selection experiment, four replicate lines of were bred for high voluntary wheel running (HR), along with four nonselected control (C) lines.

The Evolutionary Fates of a Large Segmental Duplication in Mouse.

Gene duplication and loss are major sources of genetic polymorphism in populations, and are important forces shaping the evolution of genome content and organization. We have reconstructed the origin and history of a 127-kbp segmental duplication, R2d, in the house mouse (Mus musculus). R2d contains a single protein-coding gene, Cwc22 De novo assembly of both the ancestral (R2d1) and the derived (R2d2) copies reveals that they have been subject to nonallelic gene conversion events spanning tens of kilobases.

R2d2 Drives Selfish Sweeps in the House Mouse.

A selective sweep is the result of strong positive selection driving newly occurring or standing genetic variants to fixation, and can dramatically alter the pattern and distribution of allelic diversity in a population. Population-level sequencing data have enabled discoveries of selective sweeps associated with genes involved in recent adaptations in many species. In contrast, much debate but little evidence addresses whether "selfish" genes are capable of fixation-thereby leaving signatures identical to classical selective sweeps-despite being neutral or deleterious to organismal fitness.

The Mouse Universal Genotyping Array: From Substrains to Subspecies.

Genotyping microarrays are an important resource for genetic mapping, population genetics, and monitoring of the genetic integrity of laboratory stocks. We have developed the third generation of the Mouse Universal Genotyping Array (MUGA) series, GigaMUGA, a 143,259-probe Illumina Infinium II array for the house mouse (Mus musculus). The bulk of the content of GigaMUGA is optimized for genetic mapping in the Collaborative Cross and Diversity Outbred populations, and for substrain-level identification of laboratory mice.

A multi-megabase copy number gain causes maternal transmission ratio distortion on mouse chromosome 2.

Significant departures from expected Mendelian inheritance ratios (transmission ratio distortion, TRD) are frequently observed in both experimental crosses and natural populations. TRD on mouse Chromosome (Chr) 2 has been reported in multiple experimental crosses, including the Collaborative Cross (CC). Among the eight CC founder inbred strains, we found that Chr 2 TRD was exclusive to females that were heterozygous for the WSB/EiJ allele within a 9.

Temporal transcriptome analysis of the chicken embryo yolk sac.

Background: The yolk sac (YS) is an extra-embryonic tissue that surrounds the yolk and absorbs, digests and transports nutrients during incubation of the avian embryo as well as during early term mammalian embryonic development. Understanding YS functions and development may enhance the efficient transfer of nutrients and optimize embryo development. To identify temporal large-scale patterns of gene expression and gain insights into processes and mechanisms in the YS, we performed a transcriptome study of the YS of chick embryos on embryonic days (E) E13, E15, E17, E19, and E21 (hatch).

Changes in yolk sac membrane absorptive area and fat digestion during chick embryonic development.

The capacity of yolk sac (YS) utilization by the chick embryo may be affected by structural changes in the YS membrane (YSM) and by the mechanisms within its cells for digestion, absorption, and transfer of nutrients. Two experiments were conducted to examine structural and digestive changes in the YS of the broiler chick embryo; weights of embryo, YS, and YSM, as well as the total area of the YSM and the absorptive area of the YSM, were measured between embryonic day (E) 5 and E21. In addition, fat content, lipase activity, and bile acid concentration in the YSM and YS contents (YSC) were measured between E11 and E21.

Gene expression of nutrient transporters and digestive enzymes in the yolk sac membrane and small intestine of the developing embryonic chick.

Chick embryos derive nutrients from the yolk during incubation and transition to intestinal absorption of nutrients posthatch. The uptake of nutrients is mediated by a variety of membrane-bound transporter proteins. The objective of this study was to determine the expression profiles of nutrient transporters and digestive enzymes during incubation in the yolk sac membrane (YSM) and embryonic intestine of egg-laying (Leghorn) and meat-producing (Cobb) chickens derived from 22 to 30 wk (young) and 45 to 50 wk (old) breeder flocks.

Yolk sac carbohydrate levels and gene expression of key gluconeogenic and glycogenic enzymes during chick embryonic development.

Glycogen and glucose concentrations (mg/g of tissue) and amounts (mg) were determined in the yolks of fertile eggs on the day of set and in the yolk sac (YS) and liver of broiler chick embryos between 11 and 21 embryonic days of age (E). On the day of set, the yolk contained 50 mg of glucose (0.31% of yolk) but did not contain glycogen.

The chick embryo yolk sac membrane expresses nutrient transporter and digestive enzyme genes.

The yolk sac membrane plays a major role in the transport of nutrients from the yolk contents to the chick embryo. We examined whether the yolk sac membrane expresses genes for nutrient digestion, enzymes, and nutrient transporters. We evaluated relative mRNA abundance of the digestive enzymes aminopeptidase N (APN) and sucrase-isomaltase (SI); the nutrient transporters oligopeptide transporter Pept1, cationic amino acid transporter CAT1, and sodium glucose transporter SGLT1; and the micronutrient transporters type IIb sodium phosphate cotransporter NPT2b, calcium transporter TRPV6, and zinc transporter ZnT-1 from embryonic d 11 (11E) to 21E (day of hatch) by real-time reverse-transcription PCR.

The viability and performance under hot conditions of featherless broilers versus fully feathered broilers.

Hot conditions decrease the difference between ambient temperature (AT) and the average temperature of the body surface. A smaller difference reduces the rate of sensible heat loss of excessive internal heat, elevates the body temperature (BT), and may lead to mortality during heat waves. Under conditions of chronic heat, broilers avoid lethal BT elevation by reducing their feed intake; consequently, growth rate and meat yield are lower.

Yolk sac nutrient composition and fat uptake in late-term embryos in eggs from young and old broiler breeder hens.

In the present study, we examined the composition, amount, and uptake of yolk nutrients [fat, protein, water, and carbohydrates (COH)] during incubation of eggs from 30- and 50-wk-old broiler breeder hens. Eggs were sampled at embryonic d 0 (fresh eggs), 13, 15, 17, 19, and 21 (hatch). Egg, embryo, yolk content, and yolk sac membrane were weighed, and the yolk sac (YS; i.