Utilization of F1 information in estimating QTL effects in F2 crosses between outbred lines

Quantitative trait loci (QTL) analysis in designed experiments is investigated using a mixed model framework through the modification of segment mapping techniques. Allele effects are modelled in the F₁ generation allowing the estimation of additive substitution effects while accounting for QTL segregation within lines and differences in mean QTL effects between lines. The resulting approach is called F₁ segment mapping. Simulation is used to illustrate the method and its properties. F₁ segment mapping has advantages over F₂ segment mapping in the derivation of exact additive genetic covariances and in the computation time for variance component estimation.     

A simulation study on the detection of causal mutations from F2 experiments

A simulation study has been performed to evaluate the power and the rate of false positives for the detection of causal mutations under two different models of analysis. We used an F₂ design generated from an F₀ population of five sires of line 1 and 40 dams of line 2 to produce an F₁ population of 10 sires and 80 dams. Two different locations of the causal mutation and several frequencies of the mutations in the parental populations were considered. The first model included only the genetic configuration of the mutation, while the second model also included the probability of line origin given the neutral markers. Both models performed well when the mutation at the candidate gene was the causal mutation, although a greater power was obtained using the first model, because of its relative simplicity compared to the second one. However, when the candidate gene mutation was a neutral mutation, the second model presented a lower rate of false positives than the first. Moreover, in some cases the second model allowed distinction between the neutral and the causal mutation. The F₂ design has a great power to detect quantitative trait loci provided by linkage disequilibrium, but also makes it difficult to discriminate between causal and neutral mutations. Therefore a high percentage of false positives can be expected. The limitations of F₂ designs for discriminating between neutral and causal mutations are discussed.     

Trait values of growth,carcass and meat quality in Wild Boar,Meishan and Pietrain pigs as well as their crossbred generations

The genetic diversity between European Wild Boar, Pietrain and Meishan and their crossbred generations are described on the basis of performance traits for growth, carcass composition and meat quality. Using the results of 1333 pigs, the highest growth rates were found in crossbred generations, indicating positive heterosis effects. In carcass composition, high meat content is associated with Pietrain and high fat content with Meishan alleles. Weights of organs were greatest in Wild Boar, the weight of the head was greatest in Meishan. Meat quality and stress resistance parameters point to superior gene effects in Wild Boar and Meishan. Crossbred animals of these genetically diverse pig sources generate the maximum variability for all traits, help to demonstrate the range of values for the specified breeds of pig and allow an efficient analysis of the genes influencing performance traits.     

Fibre structure and metabolites in M. longissimus dorsi of Wild Boar, Pietrain and Meishan pigs as well as their crossbred generations

Fibre traits and glycolytic metabolites in musculus longissimus dorsi of European Wild Boar, Pietrain and Meishan as well as their F₁ and F₂ crossbred generations were evaluated and compared. Pietrain had the highest relative number of white fibres and the largest muscle fibres. Wild Boar showed the smallest muscle fibres. The R -value and lactate level of Wild Boar and Meishan were low, whereas Pietrain had high R -values and lactate levels. The glycogen level was highest in Wild Boar and lowest in Meishan. The F₁- and F₂-crossbreds often had trait values between those of their founder breeds. Several antagonistic relations between fibre characteristics, muscle metabolites and performance traits for carcass and meat quality have been found. They are family-specific and strongest within the crossbreds of the Pietrain-based families.     

Agreement of SpO2, SaO2 and ScO2 in anesthetized cynomolgus monkeys (Macaca fascicularis)

Objective To assess the agreement between three measurements of arterial oxygen saturation (SpO₂, SaO₂ and ScO₂) in anesthetized cynomolgus monkeys. Study Design Prospective study. Animals Eleven mature, male cynomolgus monkeys (Macaca fasicularis). Methods Monkeys were anesthetized with intramuscular ketamine followed by intravenous propofol. The trachea of each was intubated and the lungs ventilated. Arterial oxygen saturation was measured with a Nonin 8500 V pulse oximeter, using a lingual clip on the cheek. Arterial blood samples were taken from an indwelling catheter. Inspired oxygen concentration was varied from 12 to 20%, and 88 paired arterial blood samples and saturation measurements were taken. Arterial oxygen saturation in the blood samples was measured using a cooximeter. The saturation was also calculated from the arterial oxygen tension using the Adair equation. The results were compared using Bland and Altman's method. Results The pulse oximeter readings were 2.7% higher than that of the cooximeter, with a limit of agreement of ?3.9 to 9.3%. The pulse oximeter readings were 1.8% higher than the calculated saturation, with a limit of agreement of ?6.5% to 10.1%. The cooximeter readings were 0.9% lower than the calculated saturation, with a limit of agreement of ?5.6% to 3.8%. Conclusions The agreement between SpO₂ and other measurements of arterial oxygen saturation in this study is typical for this technique. The bias and limits of agreement are consistent with reports in other species. Clinical relevance The Nonin 8500 V is a useful pulse oximeter for clinical use in primates.     

Prostaglandins F2α and E2 Secretion by Porcine Epithelial and Stromal Endometrial Cells on Different Days of the Oestrous Cycle

The endometrial tissue of the uterus plays a key role in reproduction and is a source of hormones and factors responsible for the proper physiological function of reproductive tract during the oestrous cycle and pregnancy. In this study, we investigated the pattern of PGF(2alpha) and PGE(2) secretion from cultured porcine endometrial cells at different days of the oestrous cycle. Epithelial and stromal cells were isolated by differential enzymatic digestion on days 6-8, 10-12 and 14-16. After attachment cells were incubated for 3 and 24 h to estimate PGF(2alpha) and PGE(2) output. The purity of culture was 85-90% for epithelial and 95-98% for stromal cells as determined by immunofluorescent staining. Release of PGF(2alpha) and PGE(2) was affected by cell type, days of the oestrous cycle and the time of incubation. After 3 h of incubation epithelial cells secreted more PGF(2alpha) than PGE(2) during all studied periods of the oestrous cycle (p < 0.01 and p < 0.001, respectively), whereas stromal cells released more PGE(2) (p < 0.01) on days 10-12 and 14-16. Longer incubation of stromal cells revealed that PGF(2alpha) output tended to overcome PGE(2) on days 10-16. The lowest secretion of prostaglandins was observed on days 6-8 in both cell types. The highest secretion of PGF(2alpha) from epithelium was measured on days 10-12 after 24 h of incubation when compared with other days studied (p < 0.001). In stromal cells, PGE(2) output increased on consecutive days studied (p < 0.001) after 3 h of incubation. The differential properties of endometrial cell types seem to play an important role in the profile of PGF(2alpha) and PGE(2) release before and during luteolysis. Described endometrial cells culture might serve as the model for further studies on the hormonal regulation of prostaglandin production in the pig.     

Role of Tumour Necrosis Factor α in Stimulation of Prostaglandins F2α and E2 Release by Cultured Porcine Endometrial Cells

The present studies were undertaken to examine the effect of tumour necrosis factor (TNF) alpha on prostaglandins (PGs) F(2alpha) and E(2) release by cultured porcine endometrial cells harvested on days 13-16 after oestrus in comparison to stimulation with oxytocin (OT) and luteinizing hormone (LH). A time-dependent effect of TNFalpha (10 ng/ml) on PGF(2alpha) release was observed in stromal and luminal epithelial cells. Moreover, TNFalpha increased PGF(2alpha) secretion from both endometrial cell types with effective concentrations of 1 (p < 0.05), 10 and 50 ng/ml (p < 0.01). The effect of TNFalpha (10 ng/ml) on endometrial PGF(2alpha) and PGE(2) release was compared with OT (100 nmol/l) and LH (100 ng/ml). All factors affected PGF(2alpha) secretion from stromal cells, however, the stimulation tended to be more potent after OT and LH (p < 0.01) than after TNFalpha (p < 0.05) treatment. In epithelial cells, only TNFalpha was able to stimulate PGF(2alpha) release (p < 0.001). PGE(2) secretion from stromal cells increased after incubation with TNFalpha and OT (p < 0.05). Only LH stimulated PGE(2) release from epithelium (p < 0.001), and its action was very effective when compared with TNFalpha or OT (p < 0.01). Summarizing, TNFalpha induces both PGs secretion from cultured porcine endometrium, but preferentially stimulates PGF(2alpha) release from luminal epithelial cells. Therefore, similarly to OT and LH, TNFalpha may be considered as a potential modulator of endometrial PGF(2alpha) production during luteolysis in the pig.     

The distribution of QTL additive and dominance effects in porcine F2 crosses

The present study used published quantitative trait loci (QTL) mapping data from three F2 crosses in pigs for 34 meat quality and carcass traits to derive the distribution of additive QTL effects as well as dominance coefficients. Dominance coefficients were calculated as the observed QTL dominance deviation divided by the absolute value of the observed QTL additive effect. The error variance of this ratio was approximated using the delta method. Mixtures of normal distributions (mixtures of normals) were fitted to the dominance coefficient using a modified EM‐algorithm that considered the heterogeneous error variances of the data points. The results suggested clearly to fit one component which means that the dominance coefficients are normally distributed with an estimated mean (standard deviation) of 0.193 (0.312). For the additive effects mixtures of normals and a truncated exponential distribution were fitted. Two components were fitted by the mixtures of normals. The mixtures of normals did not predict enough QTL with small effects compared to the exponential distribution and to literature reports. The estimated rate parameter of the exponential distribution was 5.81 resulting in a mean effect of 0.172.     

Effect of flunixin meglumine on prostaglandin F2α synthesis and metabolism in the pig

The effect of flunixin meglumine on prostaglandin synthesis and metabolism was evaluated in the pig in vivo. It was found that the prostaglandin metabolite, 15-ketodihydro-PGF2 alpha, was decreased in the peripheral circulation within 20 min of injection of the drug. In therapeutic doses in the pig the drug had no effect on the metabolism of PGF2 alpha. Flunixin was compared with some other non-steroidal anti-inflammatory drugs in an in vitro test system utilizing sheep vesicular gland microsomes. It was concluded that this drug is a potent inhibitor of prostaglandin synthesis.     

Comparisons of the resistance to Japanese theileriosis among Santa Gertrudis × Japanese Shorthorn F1, Japanese Shorthorn and their reciprocal crosses

To improve the resistance of Japanese Shorthorn (JS) calves to the hemoprotozoan parasite Theileria sergenti (Ts), Santa Gertrudis (SG) × JS F₁ and its reciprocal backcross (F₁ × JS and JS × F₁) calves were produced. All the calves were born from February to April and kept on pasture with their dams from May to October. Blood samples were collected biweekly until 18 weeks of grazing and two indices of resistance to the parasite, percentage of parasitized erythrocytes (PE) and hematocrit value (Ht) were monitored. There was a weak negative correlation between daily gain (DG) on pasture and the average PE (P < 0.1), and was a significantly positive correlation between DG on pasture and the average Ht (P < 0.01) in the experimental period. Although maximum PE observed at six or eight weeks of grazing period was not significantly different among the four mating types, SG × JS F₁ calves exhibited a significantly larger decrease in PE compared to purebred JS after the peak PE. F₁ calves also showed maximum Ht through the grazing period. There were no apparent differences in the two indices among the two reciprocal backcrosses and purebred JS. These results indicated that Ts infection and subsequent decrease in Ht affected the DG of calves in the grassland. The present study also demonstrated that the introduction of the SG gene into JS was effective at the F₁ level in regard to the resistance to theileriosis, and that in the backcrosses an improvement in resistance could not be expected.     

The role of thromboxane A2 in regulating porcine basilar arterial tone

The aim of the present study was to clarify the participation of endogenous arachidonic acid (AA) metabolites in regulating porcine basilar, coronary, pulmonary and mesenteric arterial tones in vitro . A cyclooxygenase inhibitor, indomethacin, relaxed basilar artery but not other arteries examined. Quinacrine (a phospholipase A₂ inhibitor), OKY-046 (a thromboxane (TX) A₂ synthetase inhibitor) and ONO-3708 (a TXA₂/prostaglandin H₂ receptor antagonist) produced relaxation in basilar arteries with intact endothelium. Nordihydroguaiaretic acid (a lipoxygenase inhibitor) had no effect on the tone. The amount of TXB₂ (a stable metabolite of TXA₂) spontaneously released from porcine basilar arteries was 6–10 fold more than those from other arteries. Indomethacin and OKY-046 mostly inhibited the production of TXB₂. Endothelial denudation decreased indomethacin-induced relaxation and the amount of TXB₂. These results suggest that a vasoconstricting substance(s) is released from endothelial cells and possibly smooth muscle cells in porcine basilar arteries in vitro . The main constricting substance is proposed to be TXA₂. On the other hand, several arteries from peripheral vascular beds did not release this vasoconstricting substance.     

Luteolytic Effect of Prostaglandin F2α on Bovine Corpus Luteum Depends on Cell Composition and Contact

Prostaglandin F_2α (PGF_2α) is a main luteolytic factor in vivo; however, its direct luteolytic influence on steroidogenic cells of bovine corpus luteum (CL) is controversial and not fully understood. The aim of the study was to clarify PGF_2α action on bovine CL in different in vivo and in vitro conditions and to examine whether the contact among all main types of CL cells is necessary for luteolytic PGF_2α action. In experiment 1, the bovine CL (day 15 of the oestrous cycle) was perfused using in vivo microdialysis system with dinoprost (an analogue of PGF_2α) for 0.5 h. Dinoprost caused a short‐time increase in progesterone (P4), whose concentration decreased thereafter (at 6‐, 10‐, 12‐ and 24‐h after treatment). In experiment 2, the direct effect of PGF_2α on P4 accumulation in CL steroidogenic cells cultured in monolayer (day 15 of the cycle) was determined. PGF_2α after 24 h of incubation increased P4 accumulation in steroidogenic CL cells. In experiment 3 steroidogenic, endothelial CL and immune cells (day 15 of the cycle) were incubated with PGF_2α in cocultures for 24 h in glass tubes and the levels of P4, stable metabolites of nitric oxide (NO) and leukotriene (LT) C₄ were determined. Although PGF_2α treatment increased P4 secretion in homogeneous steroidogenic CL cell culture, the decrease in P4 secretion in cocultures of all types of CL cells was observed. The secretion of NO and LTC₄ increased after the treatment of PGF_2α both in pure cultures of CL cells and in cocultures. The interactions between endothelial and immune cells with steroidogenic CL cells are needed for luteolytic PGF_2α action within the bovine CL. Our results indicate that the cell coculture model, including the main types of CL cells, is the most approximate to study PGF_2α role in vitro.     

Assessment of histamine, bradykinin, prostaglandins E1 and E2 and carrageenin as vascular permeability agents in the horse

The vascular leakage induced by histamine, bradykinin, serotonin and prostaglandin E1 and E2 was assessed. The test agents were injected intradermally into the shaved thoracic skin of horses and the vascular leakage estimated either semi-quantitatively by recording the diameter of the lesions or by measuring the actual volume of extravasated plasma in microliters using iodine-125-labelled human serum albumin (125I-HSA) as a marker in the blood plasma. Using the latter method, the vascular leakage induced by carrageenin and the effect of coadministered prostaglandins E1 and E2 upon the vascular leakage of both histamine and bradykinin were also investigated. No obvious lesions resulted when serotonin (10(-2) mol/l) was injected but histamine and bradykinin produced circular lesions which increased in diameter for approximately 30 min. The size of the lesions and volume of extravasated plasma was dose dependent. On a molar basis, bradykinin (10(-6) mol/l, 10(-5) mol/l) was more potent than histamine but they were equipotent at 10(-4) mol/l. The size of the lesions induced by carrageenin were independent of their anatomical location on the thorax. Except for the second hour, the hourly volume of vascular leakage increased until the fifth hour when the experiment was concluded. The maximum vascular leakage resulting from the injection of prostaglandin E1 or E2 (1, 10, 100 or 1000 ng) was 7 microliters but when co-administered with bradykinin (10(-6) mol/l), the volume of leaked plasma increased from 29 to 78 microliters. No synergy was observed when either prostaglandin was co-administered with histamine (10(-5) mol/l).     

Timing of Ovulation and Fertility of Heifers After Synchronization of Oestrus with GnRH and Prostaglandin F2α

Synchronization of oestrus and/or ovulation can reduce workload in heifer reproductive management. The objective of this study was to compare two protocols to synchronize oestrus and/or ovulation using GnRH and prostaglandin F_2α (PGF_2α) in dairy heifers concerning their effect on follicular dynamics and reproductive performance. Four trials were carried out. In trial 1, 282 heifers were treated with GnRH and PGF_2α 7 days apart (GP protocol). One group was inseminated on detection of oestrus (IDO 1), and the other group received two timed artificial inseminations (AI) 48 and 72 h after PGF_2α administration (TAI 1). In trial 2, 98 heifers were synchronized with the same GP protocol. Heifers in IDO 2 were treated as in IDO 1, heifers in TAI 2 received two TAI 48 and 78 h after PGF_2α administration. In trial 3, heifers in IDO 3 (n = 71) were again treated as in IDO 1. Heifers in TAI 3 (n = 166) received a second dose of GnRH 48 h after PGF_2α (GPG protocol) and TAI together with this treatment and 24 h later. Trial 4 compared the timing of ovulation after the GP and the GPG protocol, using a subgroup of the heifers from trials 1 to 3. The ovaries of the heifers were scanned via ultrasound at 48, 56, 72, 80, 96 and 104 h after PGF_2α administration. Timing of ovulation and size of the ovulatory follicles were compared between the two groups. In trials 1 to 3, conception rates to first service were between 49 and 66%. They did not differ significantly between IDO and TAI groups within or between trials. Pregnancy rates per synchronization were numerically higher in the TAI groups, but the difference was not significant. Conception rates to breeding on spontaneous oestrus in heifers returning to oestrus were higher than that after synchronized oestrus. In trial 4, more heifers ovulated before the end of the observation period in GPG than in GP (96.5% vs 74.7%; p < 0.001). Overall, ovulatory follicles were smaller in GPG (13.1 ± 1.9 mm vs 14.3 ± 1.9 mm; p < 0.001).     

Pharmacokinetics of flunixin and its effect on prostaglandin F2α metabolite concentrations after oral and intravenous administration in heifers

Flunixin meglumine (FM) was administered either orally as granules or intravenously to six heifers in a two period crossover study. Single doses of 2.2 mg/kg body weight were used. Pharmacokinetic variables were calculated using statistical moment methods. The effect exerted by flunixin was measured as changes in the basal plasma concentration of the main metabolite of prostaglandin (PG) F_2α. After oral FM the arithmetic means of pharmacokinetic variables were: MRT = 12.7 h; MAT = 6.3 h; C _max= 0.9 μg/mL; t _max= 3.5 h. The bioavailability was 60% and the mean half-life (harmonic mean) was 6.2 h. Oral administration of FM inhibited as effectively as intravenous administration the prostaglandin biosynthesis. The concentration of the PG metabolite decreased almost as rapidly as after intravenous administration. The duration of the effect was prolonged and the PG metabolite concentration was significantly lower between 10 and 30 h after oral than after intravenous administration. The results indicate that oral dosing of flunixin, in the form of granules, can be an alternative to intravenous administration for therapeutic use in cattle.     

Specific binding of dl-cloprostenol and d-cloprostenol to PG F2α receptors in bovine corpus luteum and myometrial cell membranes

Prostaglandin F_2α receptors (PGF_2α Rs) were measured in bovine corpus luteum and myometrial cell membranes using a radiometric method. The inhibition of labelled PGF_2α binding exerted by d-cloprostenol, dl-cloprostenol, PGF_2α and PGE₁ (l0–¹¹ M to 10^–4 M) was evaluated in vitro. Results strongly suggest that cloprostenol binding to PGF_2αRs is stereospecific. d-Cloprostenol and PGF_2α were equipotent, about 150 times more potent than d-cloprostenol (P < 0.05) and approximately 280 times more potent than PGE, (P < 0.05) in inhibiting [3H]PGF_2α binding to corpus luteum cell membranes. Such differences were less evident in myometrial cell membranes, where d-cloprostenol and PGF_2α were about 10 times more potent than d-cloprostenol (P < 0.05) and approximately 95 times more potent than PGE_l (P < 0.05).