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PubMed1983

Maximizing the impact of dairy and beef bulls through breeding technology.

Both biological and monetary considerations influence adoption of new breeding technologies. Therefore, genetic, reproductive, and economic factors that determine productivity of dairy and beef operations are reviewed. Improved sire evaluation programs, more efficient artificial insemination, and effective natural service are discussed and related to the present and future impact of dairy and beef bulls. Potential benefits of heterosis, artificial control of reproduction, improved bull management, computers, and multidiscipline research also are suggested. The dramatic impact of artificial insemination on genetic improvement and profitability of most commercial dairy herds is outlined. The uncertain expansion of beef artificial insemination is examined. Comparisons of dairy and beef industries indicate that expectation of similar results from the same animal breeding technologies are unwarranted. Dairy artificial insemination is and should continue to be economically feasible for commercial operations. Commercial beef producers will use little artificial insemination and rely on natural service bulls until precise human control of conception in the bovine is cost effective.

Animal Husbandry↗
PubMed2004

Timeline: Raising the profile of genetics in primary care.

Primary care practitioners recognize that genetics is relevant to their daily practice, for example, for detecting and managing the risk of multifactorial disorders and genetic reproductive risks, and, in future, for targeted drug therapy. However, they lack confidence in their ability to apply genetic approaches. In fact, genetics is already ingrained in current practice, and the development of appropriate guidelines and web-based information resources will help practitioners to make personalized genetic risk assessment a part of holistic, patient-oriented primary health care.

Genetic Counseling↗
PubMed2004

Spatial structure and genetic diversity of two tropical tree species with contrasting breeding systems and different ploidy levels.

Analyses of the spatial distribution pattern, spatial genetic structure and of genetic diversity were carried out in two tropical tree species with contrasting breeding systems and different ploidy levels using a 50-ha demographic plot in a lowland dipterocarp forest in Peninsular Malaysia. Shorea leprosula is a diploid and predominantly outcrossed species, whereas S. ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Genetic diversity parameters estimated for S. leprosula using microsatellite were consistently higher than using allozyme. In comparisons with S. leprosula and other tropical tree species, S. ovalis ssp. sericea also displayed relatively high levels of genetic diversity. This might be explained by the lower pressure of genetic drift due to tetrasomic inheritance, and for autotetraploids each locus can accommodate up to four different alleles and this allows maintenance of more alleles at individual loci. The observed high levels of genetic diversity in S. ovalis ssp. sericea can also be due to a random retention of more heterogeneous individuals in the past, and the apomictic mode of reproduction might be an evolutionary strategy, which allows the species to maintain high levels of genetic diversity. The spatial distribution pattern analyses of both species showed significant levels of aggregation at small and medium but random distribution at the big diameter-class. The decrease in magnitude of spatial aggregation from small- to large-diameter classes might be due to compensatory mortality during recruitment and survival under competitive thinning process. Spatial genetic structure analyses for both species revealed significant spatial genetic structure for short distances in all the three diameter-classes. The magnitude of spatial genetic structure in both species was observed to be decreasing from smaller- to larger-diameter classes. The high spatial genetic structuring observed in S. ovalis ssp. sericea at the small-diameter class is due primarily to limited seed dispersal and apomictic mode of reproduction. The similar observation in S. leprosula, however, can be explained by limited seed and pollen dispersal, which supports further the fact that the species is pollinated by weak fliers, mainly of Thrips and Megalurothrips in the lowland dipterocarp forest.

Age Factors↗
PubMed2002

Paternal familial twinning: hypothesis and genetic/medical implications.

The phenomenon of paternally dependent familial twinning has been known in human and animal genetics since the 1920s, but still remains without any theoretical explanation and is indeed a neglected field of inquiry. Over the last two decades investigations in reproduction biology have discovered the significant role of multiple paternally dependent errors in fertilization including androgenic triploidy and moles. We suggest the hypothesis that the fathers of twins in the relevant families carry gene variants that increase the probability of dispermy, diplospermy and male pronucleus heterochrony as well as involvement of two male pronuclei in the fertilization of two female meiotic products. Any resulting twins would be an exceptional intermediate between MZ and DZ twins - and might properly be described as "sesquizygotic" (SZ). Paternal familial twinning may also go together with infertility due to triploidy, moles and chimerism. The hypothesis: (i) places the curiosities of paternally derived twinning within the framework of current knowledge of reproductive genetics and verifiable phenomena; (ii) predicts the existence of families in which twinning is associated with reproductive abnormalities; (iii) predicts an occurrence in relevant families of the third and intermediate category of SZ twins. Families with paternal twinning may thus provide the natural selective system for the search of unusual cases of primary chimeras, the frequency of which is still unknown.

Cell Division↗
PubMed1991

Analysis of problems in making the reproductive decision after genetic counselling.

A follow up study of 164 couples to evaluate reproductive decision making two to three years after genetic counselling showed that 43% had problems making the reproductive decision. These couples (1) had experienced difficulty in the decision making process, (2) had doubts about the decision they had made, or (3) had been unable to make a decision. Using logistic regression analysis we identified the following factors as independently and significantly associated with problems in the decision making process: (1) no postcounselling relief, (2) anticipation of a high risk level, (3) relatives' disapproval of decision, (4) a decision against having children, and (5) the presence of an affected child. Interestingly, of the couples that decided to have children, 45% of those who were eligible for prenatal diagnosis experienced the decision making process as difficult compared with 23% of those for whom prenatal diagnosis was not available (p less than 0.05). Problems in the decision making process may become apparent after genetic counselling rather than in the course of it. We suggest a structured follow up three to six months after genetic counselling to identify couples that would benefit from additional supportive counselling.

Decision Making↗
PubMed1990

[The role of genetic counseling in reproduction decisions].

In the literature dealing with the impact of genetic counsel in the reproduction decision, two aspects are discussed: 1. memorization and appraisal of the recurrence risk, chosen options for family planning, appraisal of genetic counsel by the patients 2. mechanisms of decision making and psychological impact of genetic counsel.

Decision Making↗
PubMed2003

Genetic variation in organisms with sexual and asexual reproduction.

The genetic variation in a partially asexual organism is investigated by two models suited for different time scales. Only selectively neutral variation is considered. Model 1 shows, by the use of a coalescence argument, that three sexually derived individuals per generation are sufficient to give a population the same pattern of allelic variation as found in fully sexually reproducing organisms. With less than one sexual event every third generation, the characteristic pattern expected for asexual organisms appear, with strong allelic divergence between the gene copies in individuals. At intermediary levels of sexuality, a complex situation reigns. The pair-wise allelic divergence under partial sexuality exceeds, however, always the corresponding value under full sexuality. These results apply to large populations with stable reproductive systems. In a more general framework, Model 2 shows that a small number of sexual individuals per generation is sufficient to make an apparently asexual population highly genotypically variable. The time scale in terms of generations needed to produce this effect is given by the population size and the inverse of the rate of sexuality.

Gene Frequency↗
PubMed2000

Genetics of growth and reproduction in the turkey. 14. Changes in genetic parameters over thirty generations of selection for increased body weight.

A line (F) of turkeys was selected over 30 generations for increased 16-wk BW. The base population for the F line was a randombred control population (RBC2) that was maintained without conscious selection and used to remove yearly environmental variation in the F line. Selection was effective in increasing 16-wk BW in the F line. Selection differentials based on the mean of selected parents minus mean of entire population (intended) and intended selection differentials weighted for number of offspring produced (actual) did not consistently differ, indicating that natural selection was not significantly opposing artificial selection. The realized heritability (h2) of 16-wk BW in the F line, based on the linear regression of the selection response on accumulated actual selection differentials, declined with selection; the decline appeared to be slightly different for males than females. For both sexes combined, the realized h2 was 0.309+/-0.022 (SE), 0.268+/-0.033, 0.242+/-0.026, and 0.254+/-0.007, respectively, for Generations 1 to 10, 11 to 20, 21 to 30, and 1 to 30. Genetic increases in 16-wk BW in the F line were positively associated with BW at other ages (8, 20, and 24 wk of age and at 50% production), days from stimulatory lighting to production of the first egg, and egg weight. Genetic increases were negatively associated with egg production, intensity of lay (maximum and average clutch length and rate of lay), and hatch of fertile eggs. There was no significant relationship between 16-wk BW and total days lost from broodiness or fertility. The genetic changes in some correlated traits were not consistent in all generation intervals studied, indicating that the genetic correlation between the selected trait (16 wk BW) and the correlated trait changed with selection.

Animals↗
PubMedDate not supplied

The new genetic era in reproductive medicine: possibilities, probabilities and problems.

The "New Genetic Era" will be a period of enormous exponential growth in our knowledge of the structure and function of the basic information blocks of life. The Human Genome Project will soon provide a complete and accurate sequence of the human genome. This will give us an abundance of basic genetic knowledge and provide a molecular understanding of disease, allowing for improved diagnosis and more sensitive and specific screening for disease. This will, we hope, lead to better treatments, prevention and cures through gene therapy, patient-specific drug design, and earlier and more specific behavioral interventions to prevent disease. With this information comes a complexity of legal, ethical and social concerns about potential use and abuse. The public has expressed its concerns about the potential for genetic discrimination. However, genetic information is enhancing our knowledge as to the causes of infertility, allowing diagnosis of more diseases in the prenatal period, and may aid our identification of patients at increased risk for breast and ovarian cancer. Doctors involved in reproductive medicine must become knowledgeable about the new genetic era so as to offer our patients the most appropriate and informed care.

Cloning, Organism↗
PubMed1992

Genetic effects on beef heifer puberty and subsequent reproduction.

Significant genetic variation exists within and between breeds of beef cattle for age at puberty (AP). In general, faster-gaining breed groups of larger mature size reach puberty at a later age than do slower-gaining breed groups of smaller mature size; breeds selected for milk production reach puberty at younger ages than do those breeds not selected for milk production. Heterosis, independent of heterosis effects on weight, influences most measures of puberty in females and scrotal circumference (SC) in males. Crossbred heifers reach puberty at younger ages and heavier weights than their straightbred counterparts. Scrotal circumference has been shown to be an excellent indicator of AP in yearling bulls. Furthermore, a favorable genetic relationship exists between SC in bulls and AP of female offspring. Beef cattle breeders may take a direct approach to breeding for AP and subsequent reproduction by directly selecting for measures of fertility such as SC. However, an indirect approach, involving selection for an array of traits that provide an appropriate "genetic environment" for the expression of fertility (i.e., size, milk production, calving ease) may be preferred. Although seedstock producers are limited to making change through within-breed selection, commercial producers can take advantage of both within- and between-breed selection as well as crossbreeding to achieve the same goal.

Age Factors↗
PubMed2004

Preimplantation genetic diagnosis: new reproductive options for carriers of haemophilia.

Preimplantation genetic diagnosis for haemophilia offers couples at risk for transmitting the condition the opportunity to embark on a pregnancy knowing that the embryo is unaffected by the disease. The technique aims to increase the range of reproductive options available to these couples and remove the need for invasive prenatal diagnosis and the difficult decision on whether to terminate an affected pregnancy. This aims to reduce the anxiety associated with reproduction often seen in these couples. Patients undergo a cycle of in vitro fertilization followed by embryo biopsy. The single blastomeres are then analysed using fluorescent in situ hybridization to detect the sex of the embryo, and only female embryos are transferred to the uterus. Recently a PCR based approach has allowed specific mutation detection, and therefore the transfer of unaffected male and female embryos.

Biopsy↗
PubMed2000

Global phylogeography of a cryptic copepod species complex and reproductive isolation between genetically proximate "populations".

The copepod Eurytemora affinis has a broad geographic range within the Northern Hemisphere, inhabiting coastal regions of North America, Asia, and Europe. A phylogenetic approach was used to determine levels of genetic differentiation among populations of this species, and interpopulation crosses were performed to determine reproductive compatibility. DNA sequences from two mitochondrial genes, large subunit (16S) rRNA (450 bp) and cytochrome oxidase I (COI, 652 bp), were obtained from 38 populations spanning most of the species range and from two congeneric species, E. americana and E. herdmani. Phylogenetic analysis revealed a polytomy of highly divergent clades with maximum sequence divergences of 10% in 16S rRNA and 19% in COI. A power test (difference of a proportion) revealed that amount of sequence data collected was sufficient for resolving speciation events occurring at intervals greater than 300,000 years, but insufficient for determining whether speciation events were approximately simultaneous. Geographic and genetic distances were not correlated (Mantel's test; r = 0.023, P = 0.25), suggesting that populations had not differentiated through gradual isolation by distance. At finer spatial scales, there was almost no sharing of mtDNA haplotypes among proximate populations, indicating little genetic exchange even between nearby sites. Interpopulation crosses demonstrated reproductive incompatibility among genetically distinct populations, including those that were sympatric. Most notably, two geographically distant (4000 km) but genetically proximate (0.96% 16S, 0.15% COI) populations exhibited asymmetric reproductive isolation at the F2 generation. Large genetic divergences and reproductive isolation indicate that the morphologically conservative E. affinis constitutes a sibling species complex. Reproductive isolation between genetically proximate populations underscores the importance of using multiple measures to examine patterns of speciation.

Animals↗
PubMed2002

Reproductive mode and genetic variation suggest a North American origin of European Letharia vulpina.

Our data on the intercontinental population biology of Letharia vulpina show an unexpected shift from a recombining North American population with unique haplotypes to genetically depauperate Swedish and Italian populations, each with many representatives of a single repeated haplotype. Analysis of eight loci in 47 individuals supported recombination in North American populations and showed almost no variation among European populations. We infer that a genetic bottleneck caused by limited long-distance dispersal accounts for the lack of genetic variation found in marginal populations. This lack of variation in the European populations makes it impossible to use population genetic means to distinguish clonal reproduction from self-fertilization or even outcrossing, but phenotype indicates that reproduction in the marginal populations is by clonal spread, via soredia and isidioid soredia.

Ascomycota↗
PubMedDate not supplied

[The feral pig (Sus scrofa, Suidae) in Cocos Island, Costa Rica: composition of its diet, reproductive state and genetics].

Feral pigs (Sus scrofa) cause different kinds of damage specially on oceanic islands. Pigs were introduced at Cocos Island, Costa Rica, during 1793 and bred successfully. I analyzed feral pigs diet, reproductive state, genetics and the effects of predation, in order to gather data on their ecology and impact on certain Cocos Island communities. The diet was studied, during a dry and a wet period, through stomach contents. The genetic variability was determined through PCR analysis on tissue samples which were taken from feral (Cocos Island) and domestic (mainland) pig ear-lobes. Pigs at Cocos were omnivorous, the most important diet category in both seasons was fruits. More pigs consumed fruits during the wet season but the fruits did occupy more somuch volume during the dry season. Feral pigs did not disperse exotic seeds nor prey on animal endemic species. 56% of the hunted pigs were males and 44% were females. From females in reproductive age, 46% were pregnant or suckling, and the average number of fetuses in a litter was 4.4. I confirmed a reproductive peak during January/February but could not demonstrate a reproductive peak during June/July. The low fetuses number per litter could be related with some levels of stress. The genetic variability for all the evaluated parameters within the feral population was low but not as low as expected. I suggest a compensatory mechanism were the inbreeding depression reduces consanguinity and a species susceptible to stocastic, demographic or environmental factors turns to be an adapted species with high resilience.

Animals↗
PubMed2000

Burden of genetic disorders in India.

India, like other developing countries, is facing an accelerating demographic switch to non-communicable diseases. In the cities congenital malformations and genetic disorders are important causes of morbidity and mortality. Due to the high birth rate in India a very large number of infants with genetic disorders are born every year almost half a million with malformations and 21,000 with Down syndrome. In a multi-centric study on the causes of referral for genetic counselling the top four disorders were repeated abortions (12.4%), identifiable syndromes (12.1%), chromosomal disorders (11.3%) and mental retardation (11%). In a more recent study in a private hospital the top reasons for referral were reproductive genetics (38.9%)--comprising prenatal diagnosis, recurrent abortions, infertility and Torch infections--mental retardation +/- multiple congenital anomalies (16.1%), Down syndrome (9.1%), thalassemia/haemophilia (8.8%), and muscle dystrophy/spinal muscular atrophy (8.4%). The disorders for which prenatal has been done over an 18-month-period are given. A recent study carried out in three centers (Mumbai, Delhi and Baroda) on 94,610 newborns by using a uniform proforma showed a malformation frequency of 2.03%, the commonest malformations are neural tube defects and musculo-skeletal disorders. The frequency of Down syndrome among 94,610 births was 0.87 per 1000, or 1 per 1150. Screening of 112,269 newborns for aminoacid disorders showed four disorders to be the commonest--tyrosinemia, maple syrup urine disease and phenylketonuria. Screening of cases of mental retardation for aminoacid disorders revealed four to be the commonest--hyperglycinemia, homocystinuria, alkaptonuria, and maple syrup urine disease. Metabolic studies of cases of mental retardation in AIIMS, Delhi and KEM Hospital, Mumbai, demonstrated that common disorders were those of mucopolysaccharides, lysosomes, Wilson disease, glycogen storage disease and galactosemia. It is estimated that beta- thalassemia has a frequency at birth of 1:2700, which means that about 9,000 cases of thalassemia major are born every year. Almost 5200 infants with sickle cell disease are born every year. Disorders, which deserve to be screened in the newborn period, are hypothyroidism and G-6-PD deficiency, while screening for aminoacid and other metabolic disorders could presently be restricted to symptomatic infants.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

[Genetic-physiologic features of reproduction in prolific animals].

Genetic and physiological functional relationships between major reproductive parameters were studied in domestic prolific mammals with special reference to selection-induced changes in fertility and mothering ability in ten generations of pigs of sino-European Tiameslan composite line, which was first bred in France. Based on our hypothesis, balance equations were derived describing highly adaptive functional coadaptations of reproductive traits. Properties of these equations were examined with regard to natural selection. Selection changes of secretory traits of mammary glands were shown to play a leading role in a correlated increase of biological fertility. Genetically controlled regulatory relationships maintained by natural stabilizing selection were established between fertility, sow milk production, perinatal survival, and survival to weaning. Thus, a system of simple complementary equations characterizing an independent integrative reproductive physiological mother-young(s) system was obtained, which had not been previously published. The self-regulated homeostatic mother-young(s) system, studied for the first time ever, ensured homeostatic development of suckling piglets, compensatory regulation, and stabilization at the optimal level of biological (11.6 +/- 0.17 piglets at birth) and actual (10.0 +/- 0.08 piglets at weaning) fertility in the Tiameslan line.

Animals↗
PubMed2004

Preimplantation genetic diagnosis for polycystic kidney disease.

OBJECTIVE: To use preimplantation genetic diagnosis for achieving a polycystic kidney disease (PKD)-free pregnancy for a couple in which the female partner was affected by PKD but whose PKD1 or PKD2 carrier status was not established. DESIGN: Case report. SETTING: The IVF program of Reproductive Genetics Institute, Chicago, Illinois. PATIENT(S): An at-risk couple with the female partner affected by PKD, whose PKD1 or PKD2 carrier status was not established. INTERVENTION(S): Removal of PB1 and PB2 and testing for three closely linked markers to PKD1 (Kg8, D16S664, and SM7) and four closely linked markers to PKD2 (D4S2922, D4S2458, D4S423, and D4S1557) after standard IVF. MAIN OUTCOME MEASURE(S): Deoxyribonucleic acid analysis of PB1 and PB2 indicating whether corresponding oocytes were PKD1 or PKD2 allele free, for the purpose of transferring only embryos resulting from mutation-free oocytes. RESULT(S): Of 11 oocytes tested by PB1 and PB2 DNA analysis, 7 were predicted to contain PKD1 or PKD2, with the remaining 4 free of both mutations. Three embryos resulting from these oocytes were transferred, yielding a twin pregnancy and the birth of two unaffected children. CONCLUSION(S): This is the first preimplantation genetic diagnosis for PKD, which resulted in the birth of healthy twins confirmed to be free of PKD1 and PKD2. Preimplantation genetic diagnosis based on linked marker analysis provides an alternative for avoiding the pregnancy and birth of children with PKD, even in at-risk couples without exact PKD1 or PKD2 carrier information.

Chromosome Mapping↗