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PubMedDate not supplied

[Brain tyrosine hydroxylase activity in behavior-selected silver foxes].

In two groups of silver foxes--i.e. selected by the domestic type of behaviour and aggressive ones--studies have been made on the activity of the key enzyme in biosynthesis of catecholamines--i.e. tyrosine hydroxylase from the brain. Domesticated animals exhibited higher enzymic activity in the locus coeruleus, hypothalamus and cortex. Animals from both groups did not differ with respect to the level of tyrosine hydroxylase activity in the corpus striatum. The enzymic reactions of homogenates from locus coeruleus region of the brain in both groups of animals, as well as homogenates from the corpus striatum of the brain of aggressive animals exhibited low and approximately equal values of Michaelis constant for tyrosine. The value of KM was 3 times higher in the hypothalamus in both groups of foxes and in the corpus striatum of tame animals. Presumably, selection of silver foxes for the domestic type of behaviour resulted in the increase of biosynthesis of catecholamines in the brain due to the increase in the number of enzyme molecules. The increase in the activity of tyrosine hydroxylase in noradrenaline system of the brain may be associated with changes in the behavioural pattern of animals resulting from selection.

Aggression↗
PubMed1997

Commercial approaches to genetic selection for growth and feed conversion in domestic poultry.

Tremendous genetic progress has been observed historically for growth and feed conversion through the efforts of the primary breeding companies. However, significant between-strain variation still exists due to differences in selection emphasis and selection techniques practiced by these organizations. This paper provides an overview of methods currently employed in commercial poultry breeding with reference to factors complicating program design and future challenges facing the industry. Mass selection for body weight has resulted in a significant reduction in the number of days required to grow bird to market weight with indirect improvements in feed conversion. Direct selection for feed conversion is accomplished through part record testing of males that have been preselected for body weight, conformation, and defect traits. Data are commonly subjected to complex statistical analysis both to correct feed conversion for variation in body weight and to improve the accuracy of breeding value estimates. Feed conversion breeding values of male sibs are sometimes used for the selection of female candidates as well. Selection for growth rate and efficiency has resulted in negative complications, such as ascites, reduced reproductive performance, skeletal abnormalities, and increased carcass fatness. Some of these factors may be partially ameliorated through modified selection practices. If not addressed by the breeding industry, the disruption of physiological homeostasis might ultimately represent economic and genetic barriers to further progress in improving growth and efficiency. Modern techniques in molecular genetics, utilized in conjunction with traditional quantitative genetic approaches, will provide additional opportunities to circumvent these physiological complications associated with genetic selection for growth and feed efficiency.

Animals↗
PubMed2004

Selection versus demography: a multilocus investigation of the domestication process in maize.

The domestication of maize (Zea mays ssp. mays) from its wild ancestor (Zea mays ssp. parviglumis) led to a loss of genetic diversity both through a population bottleneck and through directional selection at agronomically important genes. In order to discriminate between those effects and to investigate the nature of the domestication bottleneck, we analyzed nucleotide diversity data from 12 chromosome 1 loci in parviglumis. We found an average loss of nucleotide diversity of 38% across genes, but this average was skewed downward by four putatively selected loci (tb1, d8, ts2, and zagl1). To better understand the domestication process, we used the coalescent with recombination to simulate bottlenecks under various lengths and population sizes. For each locus, we determine the likelihood of the observed data using three summary statistics: the number of segregating sites, an estimate of the population recombination parameter, and Tajima's D. Based on the eight neutrally evolving loci, a model with a bottleneck had a significantly higher likelihood than a model without one. The four putatively selected loci had significantly different likelihood optimums than the neutral loci, and this approach confirmed that ts2 and d8 were selected either during domestication or breeding. Overall, the best-fitting models had a bottleneck in which the population size and the bottleneck duration had a ratio of approximately 4- to approximately 5; for example, if the initial domestication event occurred over a 500-year period, the population size was roughly 2,000 to 2,500 individuals. However, this range did vary with the summary statistic used to assess the fit of simulations to data. In this context, Tajima's D performed poorly as a goodness-of-fit statistic, probably because Z. mays ssp. parviglumis has a frequency spectrum that is significantly skewed toward low-frequency variants. Finally, we found that demography is unlikely to account for the previously observed positive correlation between nucleotide diversity and the population-recombination parameter in maize, leaving this observation difficult to interpret.

Amino Acid Sequence↗
PubMed1983

Effects of selective breeding and age on the ability of the domestic fowl (Gallus domesticus) to oxidize trimethylamine.

Groups of adults which were selected for low and high (normal) TMA oxidase activities produced chickens with a predominance of the same character showing that capacity for synthesizing the enzyme is strongly inherited. The low and high strains became homogenous in generations 2 and 3, respectively, demonstrating that the genetic factor that impairs the synthesis of TMA oxidase can be readily removed by selective breeding. There was a 7-fold difference in the hepatic TMA oxidase activities of the strains at the age of 1 day and a 26-fold difference at 22 days. The synthesis of the enzyme increased rapidly in the high strain between the ages of 8 and 36 days but did not alter significantly in the low strain. Sex had no effect on TMA oxidase synthesis. The high strain showed better feather development and laid eggs with paler shells. There was no difference in their growth rate, egg production or hatchability.

Age Factors↗
PubMed1988

Complications inherent in scaling the basal rate of metabolism in mammals.

The scaling of the basal rate of metabolism in mammals is reexamined. Both the power and level of the scaling function are sensitive to various factors that interact with body mass and rate of metabolism, including the precision of temperature regulation, food habits, and activity level. This sensitivity implies that the rate of metabolism is a highly plastic character in the course of evolution. Consequently, the singular effect of mass on the rate of metabolism is most effectively analyzed in ecologically and physiologically uniform sets of species, rather than in taxonomically defined groups, which often are ecologically and physiologically diverse. Otherwise, all fitted curves for mammals integrate a variety of competing factors, thereby reflecting the species used and denying unique analytic significance to the power in scaling relations. Kleiber's eutherian curve may represent a relatively uniform set of data because all the species included were domesticated and because selection for high rates of production (and high rates of metabolism) occurred in the process of domestication. In the analysis of scaling relationships, the standard error of estimate (Sy.x) is a more valuable measure of the residual variation than is (1.0-r2) because r2 is a non-linear measure of the conformation of data to the relation and because Sy.x, unlike r2, is independent of the units used in the scaling relationship. At present the best estimate indicates that total rate of metabolism scales proportionally to approximately m0.60 at small masses (less than 300 g), as long as small species do not enter torpor, and scales proportionally to approximately m0.75 at large masses (greater than or equal to 300 g). Physiological properties other than metabolism are potentially sensitive to secondary factors, so their scaling functions also would be most clearly defined for physiologically uniform groups of species. This view suggests that insight into the significance of scaling relations can be obtained by examining the residual variation around a scaling function as well as by examining conformation to the function.

Animals↗
PubMedDate not supplied

[Adrenal function in the mink Mustela vison selected for the type of behavior].

Glucocorticoid function of adrenals and its reactivity to stress caused by immobilization and to ACTH stimulation have been studied in the male minks selected both for domestic and aggressive behavior towards man. In autumn period the regression of cortisol content in adrenals was observed in domesticated males and particularly in aggressive ones compared with control. At the same period the increased level of cortisol in blood as the result of immobilization was noticed in aggressive minks compared with the domesticated and control ones. At ACTH stimulation in spring time the increase of cortisol level in blood was shown for animals of all the groups but it was more marked for the aggressive ones.

Adrenal Glands↗
PubMed1983

Motoneurons of M. semitendinosus in domestic and wild pigs. A horseradish peroxidase and cord-survey study.

In domestic and wild pigs motor nuclei of the M. semitendinosus were labelled by retrograde transport of horseradish peroxidase (HRP) from muscle to spinal cord. Further motoneurons in the lumbosacral cord were stained with Luxol-fast-blue and cresyl violet. Motoneurons innervating M. semitendinosus were present in the ventral horns of the last (6th) lumbal and the first sacral cord segments. They were localized within two motor columns lying parallel to each other in the medial and lateroventral position. Both parts of the semitendinosus motor nuclei showed a spindle-like shape with both cranial and caudal enlargements. Localization, extent, and shape of the semitendinosus motor nuclei were similar in domestic and wild pigs. The average motoneuron diameter was larger in domestic than in wild pigs. The lumbosacral cord of the wild pig was thicker than that of the domestic pig. It is suggested that the size of alpha-motoneurons has increased as a result of selective breeding after domestication. This process might correlate with a higher incidence of myopathies in domestic pigs.

Animals↗
PubMed2026

Selection of GhTT2-A07 promoter enhances fiber quality in improved cotton varieties.

Modern cultivated cotton fibers are predominantly white with enhanced quality compared to their wild ancestors. However, the molecular mechanisms and evolutionary drivers linking fiber color to quality remain least focused. In this study, we identified FQC1 (Fiber Quality and Color 1), a major quantitative trait locus (QTL) on chromosome A07 that concurrently regulates both fiber quality and pigmentation. Through map-based cloning, we revealed that Gossypium hirsutum TRANSPARENT TESTA2-A07 (GhTT2-A07), an R2R3-MYB transcription factor, resides within this locus. GhTT2-A07 modulates fiber development by directly activating genes in the general phenylpropanoid pathway, thereby promoting the metabolic flux toward downstream secondary metabolites. Variations in the GhTT2-A07 promoter led to its reduced expression in modern white cotton cultivars. This down-regulation suppresses the accumulation of S/G/H-type lignin monomers and proanthocyanidins, resulting in altered secondary cell wall composition and ultimately enhancing the quality of mature white fibers. Population genetic analyses further indicate that the white-fiber allele GhTT2-A07W has been fixed in modern breeding genotypes, underscoring the impact of artificial selection during cotton domestication. Overall, our study elucidates the biochemical and molecular mechanisms underlying fiber quality and pigmentation in cotton, clarifies the selection criteria for high-quality white fibers in modern cultivars, and provides a theoretical basis for future targeted genetic improvement of cotton fibers.

Alleles↗
PubMed1989

[Change in tryptophan hydroxylase activity in the brain of silver foxes and wild Norway rats in the course of selection according to behavior].

The activity of tryptophan hydroxylase, the key enzyme of serotonin biosynthesis, was determined in the brain of silver foxes and wild rats selected, according to domestic or aggressive behavior, in respect to man. Significant increase of enzyme activity in midbrain of both domesticated rats and domesticated foxes was found, in comparison with that of aggressive animals. It was suggested that genetic mechanisms of the selection according to aggressive behavior, involve the changes of genes responsible for the synthesis of serotonin, the brain neurotransmitter which inhibits this type of behavior.

Aggression↗
PubMedDate not supplied

[The role of brain noradrenaline in regulating the endocrine function of the gonads in male brown rats selected for behavior].

In two groups of gray rats--nonaggressive ones, selected by the lack of aggression towards investigator, and aggressive animals--studies have been made on the relationship between noradrenaline system of the brain and the activity of pituitary-testicular system. In tame rats, less evident dependence of the gonadal activity on activating effect of noradrenaline was noted. After injection of norepinephrine, dopamine, and serotonin in the same brain region. *****were less significant in tame rats as compared to those in aggressive ones. The disturbed relationship between noradrenaline system of the brain and hypothalamo-pituitary-testicular complex is presumably one of the causes of associate changes in the reproductive system during selection for the domestic type of behaviour.

Aggression↗
PubMed2004

Perceptual and acoustic evidence for species-level differences in meow vocalizations by domestic cats (Felis catus) and African wild cats (Felis silvestris lybica).

To test for possible anthropogenic selection effects on meows in domestic felids, vocalizations by domestic cats (Felis catus) were compared with cries by their closest wild relative, the African wild cat (Felis silvestris lybica). Comparisons included analysis of acoustic characteristics and perceptual studies with human (Homo sapiens) listeners. The perceptual studies obtained human listener ratings of call pleasantness. Both the acoustic and perceptual comparisons revealed clear species-level differences: The domestic cat meows were significantly shorter in mean duration than the wild cat meows, showed higher mean formant frequencies, and exhibited higher mean fundamental frequencies. Human listeners at all levels of experience and affinity for cats rated domestic cat meows as far more pleasant sounding than wild cat vocalizations. These results are consistent with a model of cat domestication that posits selective pressure on meows based on human perceptual biases.

Acoustics↗
PubMed2025

Genomic insights into the population history of fat-tailed sheep and identification of two mutations that contribute to fat tail adipogenesis.

INTRODUCTION: Since their domestication, domestic sheep (Ovis aries) have been culturally and economically significant farming animals worldwide. Fat-tailed sheep serve as a unique genetic resource for understanding adipogenesis and adaptive evolution in livestock. OBJECTIVES: Several genomic analyses have been conducted on various sheep breeds to elucidate the genome and regulation mechanism of the fat tail trait, prior genomic studies have failed to reconcile conflicting evidence about the genetic basis of tail morphology, particularly regarding the roles of PDGFD and BMP2. METHODS: Here, we conducted whole-genome resequencing of 283 sheep, encompassing 66 domestic breeds and 5 wild ovine species, to investigate the domestication history and selection signatures of fat-tailed sheep. Additionally, we performed transcriptome sequencing on adipose tissue to identify differentially expressed genes and cellular assays to validate these results. RESULTS: Demographic analysis revealed that domestic sheep descended from Asiatic mouflon and fat-tailed sheep began to diverge from thin-tailed sheep approximately 4.4-7.5 thousand years ago in East Asia. Chinese indigenous sheep were classified into Mongolian, Kazakh, Tibetan, and Yunnan populations. The Yunnan population may have experienced more recent genetic introgression from wild species, rather than an independent domestication event. Moreover, many potential regions associated with the fat-tailed phenotype (DDI1, PDGFD, and BMP2) were identified by selective sweep and genome-wide association analyses. Additionally, a fine-scale analysis of fat-tailed and thin-tailed sheep revealed two novel mutations: a G/A missense variant of PDGFD (Chr15: 3900312) and a C/T missense variant of BMP2 (Chr13: 48462350), both of which were significantly associated with tail adiposity. Functional validation demonstrated that mutant A-PDGFD significantly activated PFGFD expression and reduced fat deposition compared to wildtype. The C-BMP2 mutant activated BMP2 expression and promoted preadipocyte fat deposition. CONCLUSION: Our study provides the first evidence that these genes jointly regulate fat tail development through complementary mechanisms: PDGFD promotes adipose expansion, whereas BMP2 modulates energy partitioning. These findings offer new insights into the evolutionary history of fat-tailed sheep and identify potential targets for precision breeding in small ruminants.

Animals↗
PubMed1991

Succinylcholine-stimulated muscle tensions following botulinum injection in the domestic cat.

Succinylcholine (SCh) selectively stimulates, and can therefore selectively assay, the multiple innervated (MI) fiber system of the extraocular muscles. Since botulinum-A toxin has been observed to induce changes in eye position in humans, SCh was used to assess the effect of botulinum-A on the SCh-sensitive MI fibers of extraocular muscles. Intravenous SCh infusion (40 micrograms-1 kg-1 min-1 was performed in the anesthetized domestic cat. Thirty-eight infusions were performed in 19 normal controls, measuring the peak tensions generated in the four horizontal and four vertical rectus muscles. Succinylcholine-stimulated muscle tensions (SSMT) were then repeated in nine animals, 4 weeks and 10 weeks following injection of botulinum-A toxin into both medial rectus muscles. Mean peak SSMTs were unchanged at 4 and 10 weeks following botulinum injection when compared to controls. We propose that botulinum chemo-denervation has no acute or chronic effect on the MI SCh-sensitive muscle fibers of the medial recti of the domestic cat. This lack of effect on the postsynaptic MI fibers indirectly supports light and electron microscopic studies which show changes predominantly in the singly innervated (SI), rather than the MI fibers following botulinum injection. Mean peak SSMTs were also greater for medial and superior rectus muscles compared to lateral and inferior recti respectively, suggesting a greater number or proportion of MI fibers in medial and superior recti.

Animals↗
PubMed2026

Domestication as gene-culture coevolution.

Human preferences can shape the genetic evolution of other species via conservation practices, public health actions, and domestication. While the dynamics of domestication have been explored in depth through empirical and theoretical analyses, few studies have analyzed models for the coevolution of human cultural preferences with the genetics of a domesticate population. Humans shape the fitness landscape of domesticate populations both intentionally and unconsciously, by selecting for desirable traits and modifying environments; in turn, changes in domesticate phenotypes can affect the cultural preferences in the domesticator population. We present a model for the dynamics of domestication which includes interactions between genetic evolution, cultural transmission, and selective pressures. The model includes forms of selection due to culturally transmitted domesticator preferences that can affect the dynamics of domesticate genetic variants, which then affect the dynamics of domesticators. Equilibria with simultaneous genetic and cultural polymorphisms may exist, and may occur under apparent heterozygote disadvantage in the domesticate. Stable quasiperiodic cycles in both domesticates and domesticators are also possible.

Humans↗
PubMed1978

The influence of total hip replacement on selected activities of daily living and on the use of domestic aid.

The effect of total hip replacement (McKee-Farrar and Brunswik prostheses) on selected activities of daily living and on the use of domestic aid in these activities was evaluated by interviewing 539 patients operated on. The mean age of the patients was 64.7 years and the mean follow-up time 4.2 years. After eliminating other diseases affecting mobility, a "proper" series of 294 patients was obtained. There was marked improvement in all activities. Walking ability was limited in 95% before and in 12% after the operation. The proportion of those unable to clean their homes decreased from 67% to 16%, to shop from 46% to 10%, to tie their shoes from 75% to 29%, to pull on stockings from 43% to 3% and to dress in other ways from 30% to 1%. The proportion of patients who were able to take care of themselves increased from 21% to 62%. The reliability of the interview was tested by comparing some objective observations with the information given by the patients. Thus a correlation was observed between the ability to walk and shop on the one hand, and pull on stockings and the flexion range of the hip, on the other.

Activities of Daily Living↗
PubMed1999

Predicting correlated responses in natural populations: changes in JHE activity in the bermuda population of the sand cricket, gryllus firmus

Quantitative genetic methods have been used to examine selection responses in domesticated organisms but there are few cases of their application to predict changes in natural populations: there are, to our knowledge, no cases in which correlated responses to selection have been predicted. In the present paper we use quantitative genetic parameters estimated from a half-sib experiment to predict the changes expected in juvenile hormone esterase (JHE) activity in the Bermuda population of the wing dimorphic cricket, Gryllus firmus. JHE activity is genetically correlated with wing form in this cricket and hence changes in the proportion of macroptery (volant morph) are predicted to bring about a correlated response in JHE activity. The Bermuda population has a higher proportion of macropterous individuals (95%) compared to the stock (35%, originally from Florida) from which the heritabilities and correlations were estimated. The quantitative genetic analysis makes three predictions which were tested both qualitatively and quantitatively. In all cases the null hypothesis that the observed results correspond to those predicted cannot be rejected. As predicted, in the Bermuda population there is: (i) an increase in the population mean JHE activity; (ii) a leftwards shift in the curve relating the probability of microptery (flightless morph) to JHE activity; and (iii) a decrease in the mean JHE activity within each morph.

Journal Article↗
PubMed1998

Genetic control of host resistance to flavivirus infection in animals.

Flaviviruses are small, enveloped RNA viruses which are generally transmitted by arthropods to animals and man. Although flaviviruses cause important diseases in domestic animals and man, flaviviral infection of animals which constitute the normal vertebrate reservoir may be mild or sub-clinical, which suggests that some adaptation between virus and host may have occurred. While this possibility is difficult to study in wild animals, extensive studies using laboratory mice have demonstrated the existence of innate, flavivirus-specific resistance. Resistance is heritable and is attributable to the gene Flvr, which is located on chromosome 5 in this species. The mechanism of resistance is at present unknown, but acts early and limits the replication of flaviviruses in cells. While some evidence supports a role for Flvr in enhancing the production of defective interfering virus, thereby restricting the production of infectious virus, other reports suggest that Flvr interferes with either virus RNA replication or RNA packaging. Recent research suggests that cytoplasmic proteins bind to the viral replication complex and that allelic forms of these proteins in resistant mice may restrict the production of infectious progeny. Apparent resistance to flaviviruses has been described in other vertebrates, although it remains to be seen if this is attributable to a homologue of Flvr. Nonetheless, knowledge gained of the characteristics and function of Flvr in mice should be applicable to other host species, and improvement of resistance to flaviviral infection in domestic animals by selective breeding or gene technology may ultimately be possible.

Animals↗
PubMed2001

Indigenous domestic breeds as reservoirs of genetic diversity: the Argentinean Creole cattle.

Contrary to highly selected commercial breeds, indigenous domestic breeds are composed of semi-wild or feral populations subjected to reduced levels of artificial selection. As a consequence, many of these breeds have become locally adapted to a wide range of environments, showing high levels of phenotypic variability and increased fitness under natural conditions. Genetic analyses of three loci associated with milk production (alpha(S1)-casein, kappa-casein and prolactin) and the locus BoLA-DRB3 of the major histocompatibility complex indicated that the Argentinean Creole cattle (ACC), an indigenous breed from South America, maintains high levels of genetic diversity and population structure. In contrast to the commercial Holstein breed, the ACC showed considerable variation in heterozygosity (H(e)) and allelic diversity (A) across populations. As expected, bi-allelic markers showed extensive variation in He whereas the highly polymorphic BoLA-DRB3 showed substantial variation in A, with individual populations having 39-74% of the total number of alleles characterized for the breed. An analysis of molecular variance (AMOVA) of nine populations throughout the distribution range of the ACC revealed that 91.9-94.7% of the total observed variance was explained by differences within populations whereas 5.3-8.1% was the result of differences among populations. In addition, the ACC breed consistently showed higher levels of genetic differentiation among populations than Holstein. Results from this study emphasize the importance of population genetic structure within domestic breeds as an essential component of genetic diversity and suggest that indigenous breeds may be considered important reservoirs of genetic diversity for commercial domestic species.

Alleles↗