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D Pomp

Publications and source records attributed to D Pomp.

At least 55 records · Page 3Linked to original sources
PubMed1997

Ontogeny of elongation and gene expression in the early developing porcine conceptus.

Early porcine conceptus development is characterized by rapid trophoblastic elongation between Days 11 and 12 of pregnancy, a period of embryonic loss in the pig. Growth factors and steroids secreted by the conceptus and uterus, as well as ligand receptors produced by the conceptus, are thought to regulate trophoblastic elongation. Therefore, the objectives of this study were to characterize conceptus gene expression for the steroidogenic enzymes 17alpha-hydroxylase and aromatase and the mesodermal marker brachyury, as well as the expression of receptors for fibronectin (integrin beta-1), progesterone, estrogen, oxytocin, prostaglandin F2alpha, and leukemia inhibitory factor (LIF), prior to and during trophoblastic elongation. Total RNA was extracted from individual conceptuses from Day 10 to Day 12 of pregnancy. Gene expression was determined by reverse transcription polymerase chain reaction on conceptuses having 2- to 4-, 5-, 6-, 7-, 8-, 9-, and 10- to 12-mm spherical, 13- to 25-mm tubular, and > 100-mm filamentous morphologies. There was a stage of development effect on both 17alpha-hydroxylase (p < 0.001) and aromatase (p < 0.003) gene expression. Initial 17alpha-hydroxylase gene expression was detected in early spherical conceptuses (2-4 mm), increasing abruptly through to 7-mm conceptuses. Aromatase gene expression increased dramatically in 6- to 7-mm conceptuses, with increased expression throughout development. Gene expression for LIF receptor (LIFR) (p < 0.02) was similar to that for 17alpha-hydroxylase, while brachyury gene expression began in 6-mm conceptuses and increased (p < 0.001) throughout development. Integrin beta-1 was expressed at all stages of development. Conceptus gene expression was not detected for progesterone, estrogen, oxytocin, and prostaglandin F2alpha receptors. Prior to elongation, dynamic changes in gene expression are occurring that appear to be associated with estrogen production and preparation of the conceptuses for elongation. LIFR expression is highly associated with steroidogenic enzyme production with an initial peak preceding rapid trophoblastic elongation, suggesting that LIF may be involved in early conceptus development in the pig.

Animals↗
PubMed1997

Feasibility of the grandprogeny design for quantitative trait loci (QTL) detection in purebred beef cattle.

The grandprogeny design (GPD) was developed for dairy cattle to use existing pedigreed populations for quantitative trait locus (QTL) detection. Marker genotypes of grandsires and sons are determined, and trait phenotypic data from grandprogeny are analyzed. The objective of this study was to investigate the potential application of GPD in purebred beef cattle populations. Pedigree structures of Angus (n = 123,319), Hereford (n = 107,778), Brangus (n = 14,449), and Gelbvieh (n = 8,114) sire evaluation reports were analyzed to identify potentially useful families. Power of QTL detection was calculated for a range of QTL effects (.1 to .5 SD) and two Type I error rates (.01 and .001). Reasonable power (> .75) could be achieved using GPD in Angus and Hereford for QTL having moderate effects (.3 SD) on weaning weight and large effects (.4 to .5 SD) on birth, yearling, and maternal weaning weights by genotyping 500 animals. Existing Gelbvieh and Brangus families useful for GPD were limited, and reasonable power could be expected only for QTL having large effects on weaning or birth weights. Although family structures suitable for GPD exist in purebred beef populations, large amounts of genotyping would be required to achieve reasonable power, and only QTL having moderate to large effects could be expected to be identified.

Aging↗
PubMed1996

Development of obesity following inactivation of a growth hormone transgene in mice.

Mice with a temporally regulatable ovine metallothionein 1a--ovine growth hormone transgene (oMT1a-oGH) were utilized to study the effects of withdrawal of elevated circulating levels of growth hormone (GH) on growth and body composition. The transgene was activated from 21-42 days of age by provision of zinc sulfate in the drinking water. At 42 days, mice were allocated to either activated transgenic (remain on zinc sulfate) or inactivated transgenic (removal of zinc sulfate) groups, and to receive either ad libitum or restricted (80-90% of ad libitum) access to feed. Non-transgenic control mice were treated similarly. Body weights and intakes were recorded weekly. Mice were killed at 70 d and epididymal and subcutaneous fat pads, trimmed hind carcass and various organs were weighed. The main findings of this study are: (1) food-restricted mice possessing an activated oMT1a-oGH transgene fail to demonstrate increased growth, but exhibit significantly reduced levels of fat (P < 0.05) relative to all other genotype x feed level combinations; and (2) inactivation of the oMT1a-oGH transgene, following a period of elevated GH levels, leads to development of obesity as evidenced by two to three fold increases in epididymal and subcutaneous fat pad weights (P < 0.01) relative to both activated transgenic and non-transgenic control mice. These large increases in fat deposition also occurred when intake was restricted to 80-90% of ad libitum levels, indicating that metabolic changes independent of intake occur in these inactivated transgenic mice. It is possible that highly elevated production of GH in activated oMT1a-oGH transgenic mice leads to (1) enhanced promotion of preadipocyte differentiation, leading to increased numbers of adipocytes that, upon cessation of oGH production, are available for lipid deposition resulting in obesity, or (2) alterations in production of or responsiveness to insulin, leading to increased fat deposition upon removal of the chronic anti-lipogenic actions of GH. The oMT1a-oGH transgenic mouse line should provide a new genetic model with which to investigate the mechanisms by which growth hormone affects obesity.

Adipose Tissue↗
PubMed1996

Quantitative genetics of transgenic mice: components of phenotypic variation in body weights and weight gains.

Transgenic mice possessing an ovine growth hormone gene were used to study the effects of elevated growth hormone on quantitative genetic variation. Males hemizygous for the transgene were mated to wild-type females to produce half- and full-sib families in which approximately half the progeny were transgenic and half were wild type. Analyses of body weights at 3-10 weeks, and weight gains from 3 to 6, and 6 to 10 weeks produced estimates of the proportion of total variance due to additive genetic effects (h2) and common litter effects (c2), and the genetic correlation between transgenic and wild-type expression of each trait. At 10 weeks, body weight of transgenics exceeded that of wild types by 26 and 49% in males and females, respectively. Estimated genetic variances in the transgenic group were significantly greater than zero for body weights at most ages and for both measurements of gain. Common litter effects accounted for a similar proportion of variation in the wild-type and transgenic groups. Additive genetic correlations between wild-type and transgenic expression of body weights tended to decline with age, indicating that a partially different array of genes may have begun to affect body weight in the transgenic group.

Age Factors↗
PubMed1996

Linkage mapping of the retinoic acid receptor-gamma gene to porcine chromosome 5.

The porcine retinoic acid receptor-gamma gene (RARG) has been mapped by restriction fragment length polymorphism analysis to porcine chromosome 5. The placement of RARG distal to the diacylglycerol kinase gene increases the length of the existing map (PiGMaP) and adds a fifth type-I marker to this sparsely mapped chromosome. This augments the homology of pig chromosome 5 and human chromosome 12 established by previous comparative mapping.

Animals↗
PubMed1996

Polymerase chain reaction-based polymorphisms in the porcine cholecystokinin (CCK) gene and assignment to chromosome 13.

Polymorphisms were identified in the porcine cholecystokinin (CCK) gene by digestion of products from polymerase chain reaction (PCR) with the restriction enzyme DpnII. Individuals from the European pig gene mapping project (PiGMaP) consortium reference families (eight full-sib families, 91 total progeny) were genotype to determine linkage relationships between the CCK gene and previously mapped loci. Linkage analysis revealed that the CCK gene is located on porcine chromosome 13.

Animals↗
PubMed1996

Characterization of DNA polymorphisms in three populations of hereford cattle and their associations with growth and maternal EPD in line 1 herefords.

Three populations of Hereford cattle differing in inbreeding levels and genetic potential for growth were genotyped for seven DNA polymorphisms. The populations were compared to determine differences in allele frequency and genetic variation. Significant differences in allele frequency among the populations were found at six of the seven polymorphisms genotyped, and average genetic variation differed as expected when inbreeding levels were considered. Effects of several polymorphisms on growth and maternal EPD were evaluated for one population (Miles City Line 1 Herefords) using regression analysis. Substitution of a B allele for an A allele of the kappa-casein polymorphism accounted for significant decreases in direct birth weight and maternal 180-d gain from birth to weaning EPD explaining 15% and 8%, respectively, of EPD variability. Several other significant effects accounting for small portions of EPD variability were also detected.

Alleles↗
PubMed1995

Rescue of pregnancy and maintenance of corpora lutea in infertile transgenic mice expressing an ovine metallothionein 1a-ovine growth hormone fusion gene.

Transgenic female mice expressing a temporally regulatable ovine metallothionein 1a-ovine growth hormone (oMT1a-oGH) fusion gene can cycle, mate, and support early embryonic development; but they fail to maintain pregnancy or, in most cases, to exhibit signs of pseudopregnancy. The present study was designed to determine whether or not the infertility of oMT1a-oGH transgenic female mice is due to luteal insufficiency. A series of five experiments was conducted in which various hormonal therapies were utilized in an attempt to overcome this infertility. Provision of 1 mg progesterone to oMT1a-oGH females from Days 1 to 17 of gestation rescued pregnancy in 19 of 20 females with an increased mean litter size (p < 0.01) compared to that of wild-type control females. Supplementation with progesterone also appeared on the basis of gross anatomical appearance to maintain CI. Provision of 2 mg progesterone in combination with 25 ng estradiol-17 beta from Days 4 to 17 rescued pregnancy in 14 of 24 oMT1a-oGH females, while provision of 100 or 25 micrograms ovine prolactin from Days 3 to 17 failed to overcome oMT1a-oGH infertility. Transgenic females with rescued pregnancies lactated and raised heavier pups than wild-type females by Day 15 postnatal (p < 0.05). Results indicate that infertility of oMT1a-oGH transgenic mice is caused by luteal insufficiency. Supplementation of transgenic females with progesterone appeared to maintain morphologically normal CL and pregnancy with subsequently increased litter size and normal lactation.

Animals↗
PubMed1995

Assignment of the growth hormone receptor gene to bovine chromosome 20 using linkage analysis and somatic cell mapping.

A polymorphism was identified in the bovine growth hormone receptor (GHR) gene by digesting polymerase chain reaction (PCR) products with the restriction enzyme Alul. Two alleles were segregating in cattle of Bos indicus descent, but one allele appears to be fixed in Bos taurus cattle. GHR was localized to bovine chromosome 20 using bovine-rodent hybrid cell lines and linkage analysis.

Animals↗
PubMed1995

Sex identification in mammals with polymerase chain reaction and its use to examine sex effects on diameter of day-10 or -11 pig embryos.

The objectives of this study were to develop a rapid method for sex determination for several mammalian species using polymerase chain reaction (PCR) and to use this method to determine whether there is a significant developmental difference in spherical diameter between male and female d-10 or -11 porcine embryos. The PCR system was developed and verified using genomic DNA from pigs of known sex, then it was tested with genomic DNA from several other mammalian species. Sex is determined by amplification of two genes in a single reaction. The presence or absence of a region of the Sry (sex-determining region Y) gene determines sex, and amplification of the Zfy (male) or Zfx (female) genes acts as a positive control for PCR. Sex determination was successful for all animals tested, including pigs, cattle, sheep, goats, llamas, horses, humans, baboons, dogs, cats, rats, and mice. A total of 209 embryos were collected from 21 crossbred gilts on d 10 or 11 of gestation, and their diameters were measured. No significant difference in embryo diameter was detected between male and female embryos, indicating that sexual dimorphism in embryonic growth in pigs does not occur before the period of rapid embryo elongation. The present sexing technique using PCR is rapid (approximately 6 h from receipt of embryos to results), and it may be useful for examining the effects of sex on any trait of interest in early porcine embryos and embryos from several other mammals.

Animals↗