Fine mapping quantitative trait loci under selective phenotyping strategies based on linkage and linkage disequilibrium criteria

In fine mapping of a large‐scale experimental population where collection of phenotypes are very expensive, difficult to record or time‐demanding, selective phenotyping could be used to phenotype the most informative individuals. Linkage analyses based sampling criteria (LAC) and linkage disequilibrium‐based sampling criteria (LDC) for selecting individuals to phenotype are compared to random phenotyping in a quantitative trait loci (QTL) verification experiment using stochastic simulation. Several strategies based on LAC and LDC for selecting the most informative 30%, 40% or 50% of individuals for phenotyping to extract maximum power and precision in a QTL fine mapping experiment were developed and assessed. Linkage analyses for the mapping was performed for individuals sampled on LAC within families and combined linkage disequilibrium and linkage analyses was performed for individuals sampled across the whole population based on LDC. The results showed that selecting individuals with similar haplotypes to the paternal haplotypes (minimum recombination criterion) using LAC compared to random phenotyping gave at least the same power to detect a QTL but decreased the accuracy of the QTL position. However, in order to estimate unbiased QTL parameters based on LAC in a large half‐sib family, prior information on QTL position was required. The LDC improved the accuracy to estimate the QTL position but not significantly compared to random phenotyping with the same sample size. When applying LDC (all phenotyping levels), the estimated QTL effect were closer to the true value in comparison to LAC. The results showed that the LDC were better than the LAC to select individuals for phenotyping and contributed to detection of the QTL.     

Gene cloning of porcine adiponectin gene from adipose tissue and construction of its eukaryotic expression vector

To clone adiponectin (ADPN) gene from Shaziling porcine adipocyte and construct its eukaryotic expression vector, total RNA was extracted from subcutaneous fatty tissue. One pair of specific primers was designed by Primer 5.0 software according to the sequence of ADPN gene of porcine available in GenBank. The ADPN gene was amplified by PCR from cDNA and cloned into pMD18‐T vector to construct recombinant clonal vector pMD‐ADPN, sequenced and analysed. A recombinant expression plasmid pPICZaA‐ADPN was constructed by subcloning the cloned ADPN gene into the linearized pPICZaA vector. Then, the plasmid pPICZaA‐ADPN was expressed in Pichia pastoris (GS115) by electrotransformation. Western blot and Bradford analysis were used to determine the target protein induced by methanol. Results showed that the genome size of ADPN was 732 bp and encoded 244 amino acid, the nucleotide sequence of ADPN shared 100% identity with that of porcine available in GenBank. Western blot and Bradford analysis showed that the recombinant ADPN was expressed in GS115 correctly and has certain immune activity. The expression level of ADPN was 28.5 μg/ml. In conclusion, the recombinant ADPN could express in eukaryotic expression vector pPICZaA‐ADPN constructed in this study effectively.     

Twin pregnancy experimental model for transvaginal ultrasound-guided twin reduction in mares

Multiple pregnancies are still an important cause of noninfectious abortion, stillbirth, neonatal mortality, and significant delays in reproductive performance in mares. Despite new management techniques, reduction in multiple pregnancies is an ongoing preoccupation and challenge for the equine veterinarian. The aim of the present study was to establish a twin pregnancy experimental model in the mare to study the effectiveness of a transvaginal ultrasound-guided embryonic vesicle injection. Mares in heat were inseminated and then received an embryo at day 7 of the estrous cycle. At days 14 and 30, 53.5% (n = 23) and 23% (n = 10) of the mares, respectively, were carrying twins. Twin pregnancies were reduced at day 30 by transvaginal ultrasound-guided puncture of the embryonic vesicle (control, n = 5) or by transvaginal ultrasound-guided injection (TVUEVI) of 25 mg of amikacin into the embryonic vesicle (n = 5). The TVUEVI treatment had a 40% success rate and no significant variations in progesterone and prostaglandin metabolite were observed. Even though the technique does not seem very effective, the experimental model could be useful for clinical research in embryo reduction and early embryonic loss.     

Implantable loop recorders: a viable diagnostic tool in veterinary medicine

Objective : The purpose of this study was to investigate whether implantable loop recorders could be used in the diagnosis of unexplained collapse in dogs. Methods : The medical records of six dogs presented to the University of Liverpool Small Animal Teaching Hospital between May 2003 and October 2006 for further evaluation of intermittent syncopal episodes, collapse or episodic weakness, were reviewed. All these dogs underwent standard investigations and had implantable loop recorders placed. Results : A provisional diagnosis of supraventricular tachycardia was made in one dog, and diagnoses of exclusion of arrhythmogenic right ventricular cardiomyopathy and idiopathic epilepsy was made in two dogs. One dog suffered no further syncopal episodes, a diagnosis was not reached in another dog and the final dog was lost to follow‐up. Clinical Significance : The implantable loop recorder can be used successfully for the diagnosis of unexplained collapse in dogs.     

Detection of virulent feline herpesvirus-1 in the corneas of clinically normal cats

To evaluate the clinically normal feline cornea for the presence of virulent feline herpesvirus-1 (FHV-1), corneas from 31 cats (25 with normal eyes and six with active disease or corneal scarring) euthanased at a shelter were collected. Corneas from two specific pathogen-free cats were included as negative controls. Virus isolation (VI), fluorescent antibody (FA) staining and real-time polymerase chain reaction (rt-PCR) were performed on all samples. The presence or absence of dexamethasone in the media was evaluated for its effect on VI. VI was positive for FHV-1 in six corneas from five cats, all with clinically normal eyes. One cornea was positive for feline calicivirus (FCV) in addition to FHV-1, but only in media that included dexamethasone. Eight corneas were positive on rt-PCR for FHV-1, all from cats with clinically normal eyes. All positive VI samples were confirmed with FA staining. VI and rt-PCR were negative for FHV-1 and FCV in cats with active disease or corneal scarring. Data from this study indicate that virulent FHV-1 and FCV can be present in feline corneas that are clinically normal. Dexamethasone may enhance viral spread through a cell receptor mechanism.     

Caudal epidural analgesia induced by xylazine administration in cows

Xylazine (0.05 mg/kg of body weight diluted to a 5-ml volume, using 0.9% NaCl) or 5 ml of 0.9% NaCl was administered epidurally into the first caudal intervertebral space (Co1-Co2) in 8 cows (mean +/- SD body weight, 583 +/- 150 kg). Cows were observed for responses to deep needle pricking of the caudal dermatomes (S3 to Co), sedation, and ataxia. Heart rate, respiratory rate, body temperature, rate of ruminal contractions, coccygeal arterial blood pressure, pHa, blood gas tension (PaO2, PaCO2), base excess, total solids concentration, and PCV were determined before and after xylazine administration. Epidurally administered xylazine induced sedation and selective (S3 to Co) analgesia for at least 2 hours. Mild ataxia of hind limbs was observed in 6 cows, but all cows remained standing. Heart rate, respiratory rate, rate of ruminal contractions, arterial blood pressure, PaO2, PCV, and total solids concentration were significantly (P less than 0.05) decreased, and PaCO2, base excess, and bicarbonate concentration were significantly (P less than 0.05) increased after xylazine administration. Epidurally administered 0.9% NaCl did not alter sensory perception to needle pricking and did not affect any of the physiologic variables determined. Although epidural administration of xylazine induced analgesia and sedation in healthy cows, it should be avoided for epidural analgesia in cattle with heart disease, lung disease, and/or gastrointestinal disease because of its potent cardiopulmonary and ruminal depressant effects.     

Bone strength of laying hens kept in an alternative system, compared with hens in cages and on deep-litter

1. Observations of vigorous wing movements and measurements of bone strength were compared in two experiments with birds in three different housing systems: a semi-intensive alternative system under development, a battery cage system and a deep-litter system. 2. A significant effect of housing system on the frequency of vigorous wing movements was found. The highest frequency was seen in the deep-litter system, about half this number in the alternative system, while in the battery cages they were never observed. 3. Corresponding to this a reduction in humerus strength of 9% was found in hens from the alternative system and of 45% in hens from cages, compared with deep-litter. A reduction in tibial breaking strength was also found in caged hens, when compared to deep-litter hens. 4. Keeping hens in cages thus restricts their movements, especially wing movements, to the degree that bone strength is greatly reduced. 5. This has welfare implications, for hens with low bone breaking strength risk a possibility of breakage, especially when handled and transported. When alternative systems are designed opportunities for movement in the three dimensions should be considered.