Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Breeding”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,693 records · Page 94Linked to original sources
PubMed2025

From convention to innovation: the role of genetic modification and genome editing in Australian wheat breeding.

Wheat is the most cultivated crop worldwide, and Australia consistently ranks among the top wheat-exporting countries. Although modern technology has expanded the speed and accuracy of conventional breeding, progress is constrained by limited genetic diversity and linkage drag, with new wheat varieties often taking 8-12 years to reach the market. Biotech methods involving the transformation of foreign DNA into genomes [genetic modification (GM)], or editing of native DNA [genome editing (GEd)], provide novel opportunities to efficiently improve traits alongside conventional breeding. In 2020, the world's first GM drought-tolerant bread wheat (HB4) hit the market in Argentina. The USA recently approved HB4 wheat for commercial cultivation, and human consumption of HB4 wheat has been approved by nine countries, including Australia. Currently, 25 countries, Australia included, have deregulated GEd crops in some form, and many other countries have indicated that they will follow suit. As of March 2025, no GM or GEd wheat is commercially grown in Australia. The rate at which private industry integrates GM and GEd into wheat breeding programmes will depend on several factors, including the regulatory consistency governing GM and GEd crops within Australia and among international trading partners, the return on investments relative to deregulation costs including licensing, the level of acceptance amongst growers and consumers, and technical considerations including wheat's amenability to tissue culture. This review contextualizes GM and GEd applications in wheat, often drawing on examples from crop species where biotechnology has been more widely employed, and considers the key stakeholders that will shape the future of GM and GEd wheat in Australia.

GMO↗
PubMed1984

Genetic linkage in the horse. II. Distribution of male recombination estimates and the influence of age, breed and sex on recombination frequency.

In the present study an extensive amount of data, comprising more than 30,000 offspring in total, was analyzed to evaluate the influence of age and sex on the recombination frequency in the K-PGD segment of the equine linkage group (LG) I and the influence of age, breed and sex on recombination in the Al-Es segment of LG II. A highly significant sex difference is reported for both segments. Male and female recombination values in the K-PGD segment were estimated at 25.8 +/- 0.8 and 33.3 +/- 2.5%, respectively. Similarly, recombination was less frequent in the male (36.6 +/- 0.7%) than in the female (46.6 +/- 1.2%) in the Al-Es segment. Comparison of data from two Swedish horse breeds revealed no significant breed differences in either sex for recombination in the Al-Es segment. No evidence of an age effect was found in any segment or sex. The distribution of individual male recombination estimates was also investigated, and a significant heterogeneity among stallions was revealed in the K-PGD segment. The results are discussed in relation to previous studies on factors affecting recombination in mammals.

Age Factors↗
PubMed2000

Prediction of rates of inbreeding in populations selected on best linear unbiased prediction of breeding value.

Predictions for the rate of inbreeding (DeltaF) in populations with discrete generations undergoing selection on best linear unbiased prediction (BLUP) of breeding value were developed. Predictions were based on the concept of long-term genetic contributions using a recently established relationship between expected contributions and rates of inbreeding and a known procedure for predicting expected contributions. Expected contributions of individuals were predicted using a linear model, u(i)(()(x)()) = alpha + betas(i), where s(i) denotes the selective advantage as a deviation from the contemporaries, which was the sum of the breeding values of the individual and the breeding values of its mates. The accuracy of predictions was evaluated for a wide range of population and genetic parameters. Accurate predictions were obtained for populations of 5-20 sires. For 20-80 sires, systematic underprediction of on average 11% was found, which was shown to be related to the goodness of fit of the linear model. Using simulation, it was shown that a quadratic model would give accurate predictions for those schemes. Furthermore, it was shown that, contrary to random selection, DeltaF less than halved when the number of parents was doubled and that in specific cases DeltaF may increase with the number of dams.

Animal Husbandry↗
PubMed2026

Integrating genomic additive relationship matrices improves the efficiency in diploid banana breeding.

Partitioning of genetic variance into additive and non-additive components using the pedigree-based best linear unbiased prediction (P-BLUP) model is possible because of the family structure and replicated clones in clonally propagated crops, but this model may overestimate these components. However, the genomic best linear unbiased prediction (G-BLUP) method, which integrates the genetic relationship through molecular marker information reduces the overestimation. Alternatively, a combination of the P-BLUP and G-BLUP, sourcing to create a hybrid matrix that estimates hybrid best linear unbiased prediction (H-BLUP), is proposed. We investigated if integrating molecular information into the clonal model could improve the partitioning of the variance components leading to more accurate estimates of genetic parameters and prediction accuracy of breeding values of 14 key traits in diploid banana. In this study, we used clones of 14 full-sib families from a factorial mating design of four female and five diploid male banana (Musa acuminata) parents, generated at the International Institute of Tropical Agriculture in Arusha. The genomic-based relationship matrices were constructed using a set of 2792 filtered single-nucleotide polymorphism markers. Additive variance and heritability derived from G-BLUP and H-BLUP models reduced bias compared to the P-BLUP model. The H-BLUP estimated the highest prediction accuracies for yield-related and cycling traits, while the P-BLUP model had the highest prediction accuracy estimates for agronomic traits. The use of marker-based models enhances the accuracy of predicting breeding values, contributing to accurate estimates of genetic gain while paving a way for further genomic exploration in diploid banana breeding programs.

Journal Article↗
PubMedDate not supplied

Breed differences in allele frequency of the dopamine receptor D4 gene in dogs.

We previously reported that the dog dopamine receptor D4 (DRD4) gene is polymorphic as observed in humans, and four alleles were identified based on the number and/or order of the 12 and 39 bp sequences located in the homologous region of human DRD4. To assess the diversity of the DRD4 gene in dogs we examined the allelic variations in four breeds (beagle, golden retriever, Shetland sheepdog, and shiba) employing the polymerase chain reaction (PCR). As a result, we found three novel alleles and determined the DNA sequences of these alleles. The beagle shared four alleles, including 396, 435, 447a, and 447b, with the 435 (52.6%) and 447a (39.5%) alleles being common. The golden retriever had the 435 and 447a alleles, and the 435 allele was frequent (73.3%). In the Shetland sheepdog, the 435, 447a, and 498 alleles were observed, of which the 447a allele was most frequent (82.5%). The shiba had five alleles-447a, 447b, 486, 498, and 549-and the 447b allele was most common (55.4%). These findings suggest that the allele frequency varied among the four dog breeds, and analysis of the DRD4 polymorphism may therefore be useful for elucidating the relationships among dog breeds.

Alleles↗
PubMed1994

Postirrigation breeding patterns of surface water mosquitoes in the Mahaweli Project, Sri Lanka, and comparisons with preceding developmental phases.

A 2-yr (1988-1989) survey of mosquitoes breeding in surface water was done in an area of the Mahaweli Project of Sri Lanka that underwent irrigation development and human settlement during the preceding 3 yr. In total, 78,649 immatures of 42 species were collected during the survey. Species of medical importance in the area were Anopheles annularis van der Wulp, An. culicifacies Giles, An. jamesii Theobald, An. nigerrimus Giles, An. subpictus Grassi, An. vagus Doenitz, An. varuna Iyengar, Mansonia annulifera (Theobald), Ma. uniformis (Theobald), Culex fuscocephala Theobald, Cx. gelidus Theobald, Cx. pseudovishnui Colless, Cx. tritaeniorhynchus Giles, and Cx. vishnui Theobald. These and other species used breeding habitats associated with irrigation development (i.e., canals, reservoirs, seepage pools, and rice fields) as well as natural habitats (i.e., rainwater pools, riverbed pools, streams, and marshes). Trends in the use of breeding habitats that were observed with the onset of irrigated rice cultivation in 1987, continued during the period under stable irrigation in 1988 and 1989. Mosquito species richness declined, but species equitability (as indexed by Shannon-Weaver diversity values) did not change. The overall study showed that ecosystem changes concomitant with irrigation development in the Mahaweli Project resulted in long-term changes in the composition of the mosquito fauna, which was characterized by the increasing dominance of species with the potential to transmit human pathogens.

Animals↗
PubMed2005

Geographic distribution and breeding site preference of Aedes albopictus and Aedes aegypti (Diptera: culicidae) in Cameroon, Central Africa.

Presence in Cameroon of the recently introduced Aedes (Stegomyia) albopictus (Skuse) in association with the indigenous Aedes aegypti (L.) raises public heath concerns because it might alter the risk of arbovirus transmission. The breeding site and distribution of the two Stegomyia species are updated and reported following entomological surveys carried out in 22 localities throughout Cameroon, with a total of 1,353 containers with water visited. Ae. aegypti was found in every location sampled, showing higher infestation rates in northern Cameroon. Breeding populations of Ae. albopictus were observed in all 19 southern localities, up to the Adamaoua mountains, but the species was not recorded further north. In the area where both species are present, they were often sampled in the same larval developmental sites, suggesting convergent habitat segregation. The most frequently encountered artificial and natural breeding sites were used tires, discarded tins and plastic containers, abandoned car parts, brick holes, dead leaves on the ground, tree holes, and rock pools. Further monitoring of the demographic as well as geographic expansion of Ae. albopictus in this Afrotropical environment and its relationships with indigenous Ae. aegypti should provide insight into the biology of this highly invasive species and help to implement arboviruses surveillance programs in the area.

Aedes↗
PubMedDate not supplied

A cytogenetic survey of five breeds of cattle from Brazil.

One-hundred-and-thirty-nine animals from five breeds of cattle were studied cytogenetically. Three types of karyotype abnormalities were detected, two of them structural, t(1; 29) and ins(16), and one numerical (60,XY/61,XY + F). The first two, found in the Charolais race, presented familial recurrences; the last one, observed in the Norman breed, was sporadic. Pedigree studies showed that ins(16), an aberration not previously described in cattle, segregated in the ratio of 5 carriers to 10 normals. t(1; 29) occurred in mother and daughter. A variant of constitutive heterochromatin also presented familial recurrence in the Charolais breed.

Animals↗
PubMed2002

Reconstitution of a chicken breed by inter se mating of germline chimeric birds.

Blastoderm cells from chicken embryos of a donor breed (Green-legged Partridgelike; GP) were transferred to embryos of a recipient breed (White Leghorn; WL) to form chimeric progeny that, after inter se mating, permitted successful reconstitution of the donor breed. Among 23 chimeric chicks hatched from WL embryos injected with GP cells, 20 (87%) were raised until maturity, and progeny were tested by mating with GP birds to determine the ability of blastodermal cells to form germline chimeras. Six of the tested birds (30%) produced recipient-derived and donor-derived offspring, indicating that they were germline chimeras. The mean percentages of donor-derived germ cells in these birds were 21.1 (17.6 to 50.0%) and 16.9 (5.3 to 23.1%) in males and females, respectively. Among 477 chicks, resulting from mating the germline chimeric male with four germline chimeric females, 10 chicks (2.1%) exhibited a GP phenotype, indicating that the original donor stock had been reconstituted. Only one germline chimeric hen produced GP offspring, but the expected and calculated percentages of GP offspring were similar (2.99 and 2.08, respectively). Two methods of DNA analyses (RFLP and PCR amplification of polymorphic microsatellite loci) of chimeras and their offspring indicated that through mating of a relatively small number of chimeras it is possible to reconstitute a highly diverse population.

Animals↗
PubMed2007

Effect of lighting stress on fluctuating asymmetry, heterophil-to-lymphocyte ratio, and tonic immobility duration in eleven breeds of chickens.

The purpose of the present study was to analyze the effect of a lighting stress on the fluctuating asymmetry (FA), the heterophil-to-lymphocyte ratio, and the tonic immobility duration of chickens. The experiment (440 birds) measured the FA of several traits (outer, middle, inner, and hind toe lengths and leg, wing, second primary feather, and spur lengths), the heterophil-to-lymphocyte ratio, and the tonic immobility duration in 36-wk-old hens and cocks of 8 Spanish breeds of chickens (Black-Barred Andaluza, Black-Red Andaluza, Black Castellana, Buff Prat, Red-Barred Vasca, Red Villafranquina, Birchen Leonesa, and Blue Leonesa), a synthetic breed (Quail Castellana), a White Leghorn population, and the e(y) tester line, which had been housed in continuous light (24L:0D) or in a light-dark regimen (14L:10D) for 16 wk. There was a significant difference between lighting treatments in both females and males on the combined FA of the 4 toes (P < 0.01) and the combined FA of toe, leg, wing, feather, and spur (in males) lengths (P < 0.05), the FA of birds housed under continuous light being greater than that of control birds. There was a significant difference (P < 0.001) for the heterophil-to-lymphocyte ratio and the tonic immobility duration between lighting treatments, the ratio being higher and the duration being longer in the group of birds housed under continuous light. Thus, birds exposed to continuous light were more stressed and fearful than control hens. Results were consistent across the breeds and indicate that a continuous light regimen seriously negatively affects the welfare of birds.

Animals↗
PubMed1993

Temperature and water conditions mediate the effects of day length on the breeding cycle of a Sahelian rodent, Arvicanthis niloticus.

Laboratory studies of variations in testicular activity (testicular weight and plasma testosterone concentration) were carried out on two populations of Arvicanthis niloticus, a Sahelian rodent that displays the particularity of being able to breed in the dry season. The animals were captured during phases of sexual activity or inactivity and were maintained in the laboratory for 50 days under humid conditions (water-rich diet, 90% atmospheric relative humidity) or dry conditions (water-deficit diet, 20% atmosphere relative humidity) and at low temperatures (20-25 degrees C) or high temperatures (30-35 degrees C). The results show that humid conditions or low temperatures stimulate testicular activity in Arvicanthis niloticus whereas dry conditions or high temperatures inhibit breeding. 1) Humid conditions coupled with low temperatures caused the most marked stimulation of testicular activity and maintained sexual activity at its highest level. 2) Humid conditions coupled with high temperatures, or dry conditions coupled with low temperatures, brought about mild sexual activity in animals that were sexually inactive and a regression of testicular weight and plasma testosterone in animals that were sexually active at the beginning of the experiment. In the latter, the results show that testicular activity was maintained and animals remained capable of breeding. 3) High temperatures and dry conditions inhibited short-day gonadal stimulation. On the other hand, in animals maintained under humid conditions or at low temperatures, gonadal stimulation occurred only under a short photoperiod.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Gonadotropin-releasing hormone analog-induced patterns of luteinizing hormone secretion in female Wapiti (Cervus elaphus nelsoni) during the breeding season, anestrus, and pregnancy.

We conducted two studies to determine the pattern of GnRH analog-induced LH secretion in adult female wapiti during the breeding season, anestrus, and pregnancy. In the first study, we measured LH secretion during the breeding season and anestrus in five females challenged with each of five doses of GnRH analog (0.3, 1, 3, 10, and 30 micrograms/50 kg BW). In the second study, LH response was determined in six pregnant females treated with six doses of GnRH analog (0.5, 1, 2, 4, 8, and 16 micrograms/50 kg BW). Animals were fitted nonsurgically with indwelling jugular catheters, and blood samples were collected at 0, 30, 60, 90, 120, 180, 240, 300, 360, 420, and 480 min postinjection. Mean maximum serum concentrations of LH were not different (p = 0.45) between females treated during the breeding season (mean = 29.1 +/- 1.9 [SE] ng/ml) and anestrus (mean = 32.4 +/- 4.3 [SE] ng/ml); however, anestrous females required 3.3 times more GnRH analog (3 vs. 10 micrograms/50 kg BW) to produce the same response. Maximal inducible LH concentrations were lowest (mean = 7.7 +/- 2.5 [SE] ng/ml) for pregnant wapiti, and the magnitude of the response decreased exponentially (r2 = 0.98, p = 0.002, SEb = 0.65) during gestation. Although the magnitude of the response declined over time, maximal release consistently occurred at the same dose (2 micrograms/50 kg BW) (treatment x trial interaction, p = 0.53). We conclude from these studies that the amount of LH released in response to a given dose of GnRH analog depends on reproductive status.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗
PubMed2001

Effects of breed, parity, and folic acid supplement on the expression of leptin and its receptors' genes in embryonic and endometrial tissues from pigs at day 25 of gestation.

Recent evidence has pointed toward a possible role of leptin (Lep) and its receptor (Lepr) in early gestation materno-fetal cross-talk. However, in gestating sows, exhaustive characterization of leptin mRNA expression in backfat and leptin-receptor mRNA expression in endometrial and embryonic tissues is still pending. The objectives of this study were to characterize the Lep, Lepr, and long Lepr-L isoform mRNA expression according to the breed and parity of gestating sows or to specific folic acid (B(9)) + glycine dietary treatments. To this end, nulliparous (GT) and multiparous occidental Yorkshire-Landrace (YL) sows as well as multiparous Chinese Meishan-Landrace (ML) sows were used. These sows were randomly assigned to two different dietary treatments: 0 or 15 ppm of B(9) + 0.6% glycine, given from the estrous preceding mating until slaughter on Day 25 of gestation. Jugular blood samples were collected at mating and on Day 25 of gestation and assayed for circulating leptin concentrations. Expression levels of Lep in backfat and of Lepr and Lepr-L in endometrial and embryonic tissues were performed using semiquantitative reverse transcription-polymerase chain reaction. Results demonstrated that on Day 25 of pregnancy, the ML sows showed higher concentrations of circulating leptin along with higher backfat thickness and higher expression of Lep in backfat tissue. Moreover, in embryonic tissues, the mRNA expression levels of Lepr and Lepr-L genes were higher in ML than in YL sows. Parity effects were observed for mRNA expression of Lepr in both endometrial and embryonic tissues, whereas mRNA levels were higher in YL than in GT sows. In addition, embryonic Lepr-L mRNA levels were higher in GT than in YL sows, and B(9) + glycine dietary supplement decreased the mRNA expression levels of Lep in backfat and of Lepr in embryonic tissues. These decreases were independent of breed or parity of the sows. The effect of B(9) + glycine on Lepr-L mRNA expression levels was only seen in YL sows, whereas the treatment lowered Lepr-L expression levels in both endometrial and embryonic tissues. These results indicate that leptin and its receptor may play a role during early stages of development of the pig embryo-fetus, and that these roles could be modulated according to the breed and parity of the sows. Moreover, the effects of B(9) + glycine on expression levels of embryonic and endometrial Lepr-L mRNA in YL sows may explain the previously reported effects of B(9) on embryo survival rate and litter size observed in occidental multiparous sows.

Adipose Tissue↗
PubMedDate not supplied

Automatic brain tissue extraction method using erosion-dilation treatment (BREED) from three-dimensional magnetic resonance imaging T1-weighted data.

To improve the efficiency of brain image analysis, we propose a full-automatic method for extracting brain tissue from three-dimensional magnetic resonance imaging of T1-weighted data on the human head (brain tissue extraction method using erosion-dilation treatment [BREED]). The extraction processing is realized by combining signal intensity thresholding by means of the discriminant analysis method and an erosion-dilation treatment of the image. The accuracy of BREED is evaluated using both simulated and subject data. BREED can extract brain tissues with high accuracy (approximately 97%) for either simulated or subject data.

Automation↗
PubMed1994

Microsatellite DNA variation within and among European cattle breeds.

Microsatellite markers offer great potential for genetic comparisons within and between populations. We report the analysis of 12 microsatellite loci in six breeds of European cattle. This yielded a wide spectrum of variability with observed heterozygosities ranging from 0.00 to 0.91. Deviations from Hardy-Weinberg equilibrium were noted for some locus-population combinations, particularly at a microsatellite located within the prolactin gene. Also, significant linkage disequilibrium was detected between two microsatellite loci located within the bovine major histocompatibility complex, and this association was maintained across breeds, providing evidence for marker stability during short-term evolution. The mode of mutation was investigated by comparing the observed data with that expected under the infinite alleles model of neutral mutation, and six of the microsatellite loci were found to deviate significantly, suggesting that a stepwise mutation model may be more appropriate. One indication of marker utility is that, when genetic distance estimates were computed, the resultant dendrogram showed concordance with known breed histories.

Alleles↗
PubMed1996

Reproductive suppression in subordinate, non-breeding female Damaraland mole-rats: two components to a lifetime of socially induced infertility.

The Damaraland mole-rat Cryptomys damarensis exhibits an extreme reproductive division of labour. Reproduction in the colony is restricted to a single breeding pair, resulting from a two-fold control: (i) a reduced pituitary synthesis and/or secretion of luteinizing hormone leading to a block to ovulation in non-reproductive females; and (ii) a strong inhibition to breeding with familiar kin. Circulating basal concentrations of luteinizing hormone as well as luteinizing hormone levels measured in response to a single exogenous gonadotrophin releasing hormone challenge, were significantly lower in non-reproductive females in the presence of the reproductive female than those in colonies lacking a reproductive female. Urinary progesterone concentrations before the removal of the reproductive female were significantly higher in non-reproductives than the post removal values. Behavioural studies from sib-sib and non-sib pairings provide evidence for a strong incest avoidance, probably resulting from an inhibition of breeding with familiar colony members. A total of four pairings of non-sibs resulted in copulatory activity and eventual conception. In contrast, four couples of sib-sib combinations failed to produce any sexual activity or offspring. Thus, suppression of reproduction in these non-reproductive, subterranean bathyergids is complicated by the masking effect of familiarity that prevents incest, in addition to the physiological inhibition of fertility in the presence of the reproductive female.

Animals↗
PubMed2001

The evolution of cooperative breeding through group augmentation.

Some individuals (helpers) in cooperatively breeding species provide alloparental care and often suppress their own reproduction. Kin selection is clearly an important explanation for such behaviour, but a possible alternative is group augmentation where individuals survive or reproduce better in large groups and where it therefore pays to recruit new members to the group. The evolutionary stability of group augmentation is currently disputed. We model evolutionarily stable helping strategies by following the dynamics of social groups with varying degrees of subordinate help. We also distinguish between passive augmentation, where a group member benefits from the mere presence of others, and active augmentation, where their presence as such is neutral or harmful, but where helping to recruit new group members may still be beneficial if they in turn actively provide help for the current reproductives ('delayed reciprocity'). The results show that group augmentation (either passive or active) can be evolutionarily stable and explain costly helping by non-reproductive subordinates, either alone or leading to elevated help levels when acting in concert with kin selection. Group augmentation can thus potentially explain the weak relationships between relatedness and helping behaviour that are observed in some cooperatively breeding species. In some cases, the superior mutualistic performance of cooperatively behaving groups can generate an incentive to stay and help which is strong enough to make ecological constraints unnecessary for explaining the stability of cooperatively breeding groups.

Animals↗
PubMed2003

Cooperative breeding in oscine passerines: does sociality inhibit speciation?

Cooperative breeding in birds is much more prevalent than has been previously realized, occurring in 18.5% of oscine passerines known to have biparental care, and is the predominant social system of some ancient oscine clades. Cooperation is distributed unevenly in clades that contain both cooperative and pair breeders, and is usually confined to a few related genera in which it can be ubiquitous. Cooperative clades are species poor compared with pair-breeding clades, because pair breeders evolve migratory habits, speciate on oceanic islands and are more likely to have distributions spread across more than one biogeographic region. These differences reflect the increased capacity for colonization by pair breeders because their young disperse. Thus cooperative breeding has macroevolutionary consequences by restricting rates of speciation and macroecological implications by influencing the assembly of island and migrant faunas.

Animal Migration↗