Dietary conjugated linoleic acid differentially alters fatty acid composition and increases conjugated linoleic acid content in porcine adipose tissue

Conjugated linoleic acids (CLA) have been shown to decrease body fat content in pigs. It is possible that feeding pigs diets rich in CLA may increase carcass lipid CLA to levels that could provide health benefits when included as a part of a healthy diet. Therefore, the aim of the present study was to determine whether dietary CLA supplementation has any effect on the fatty acid composition of subcutaneous and intramuscular adipose tissue in pigs. Thirty-five female cross bred (Large White X Landrace) pigs (initial weight 57·2 kg and initial P2 back fat 11·5 mm) were used in the present study. Pigs were housed individually and randomly allocated to one of six dietary treatments (0·00, 1·25, 2·50, 5·00, 7·50 and 10·00 g CLA55 (55 g CLA isomers/100 g total fatty acids; Natural Lipids Ltd, Hovdebygda, Norway)/kg)
and fed their respective diets for 8 weeks. Twelve CLA isomers in the diet and in pig tissue lipids were separated by Agþ-HPLC. CLA was incorporated at fivefold higher levels in subcutaneous fat as compared with intramuscular fat and in a dose-dependant manner. Overall, the transfer efficiency of CLA was maximized at 5·00 g CLA55/kg. However, there was clear selectivity in the uptake or incorporation of cis,trans-9,11 isomer over the trans,cis-10,12 isomer. In general, CLA supplementation produced significant changes in skeletal muscle and adipose tissue fatty acid composition, indicating that dietary CLA had a potent affect on lipid transport and metabolism in vivo. Significant increases in myristic, palmitic and palmitoleic acids and a reduction in arachidonic acid were observed, suggesting an alteration in
activity of Δ5-, Δ6- and Δ9-desaturases in pig adipose tissue. In conclusion, feeding pigs diets supplemented with CLA increases carcass lipid CLA, but also results in changes in the fatty acid profile in pig fat that could potentially outweigh the benefits of CLA.

The first case of porcine epidemic diarrhea in Canada

In January, 2014, increased mortality was reported in piglets with acute diarrhea on an Ontario farm. Villus atrophy in affected piglets was confined to the small intestine. Samples of colon content were PCR-positive for porcine epidemic diarrhea virus (PEDV). Other laboratory tests did not detect significant pathogens, confirming this was the first case of PED in Canada.

Investigation into the role of potentially contaminated feed as a source of the first-detected outbreaks of porcine epidemic diarrhea in Canada

In January 2014, approximately 9 months following the initial detection of porcine epidemic diarrhea (PED) in the USA, the first case of PED was confirmed in a swine herd in south-western Ontario. A follow-up epidemiological investigation carried out on the initial and 10 subsequent Ontario PED cases pointed to feed as a common risk factor. As a result, several lots of feed and spray-dried porcine plasma (SDPP) used as a feed supplement were tested for the presence of PEDV genome by real-time RT-PCR assay. Several of these tested positive, supporting the notion that contaminated feed may have been responsible for the introduction of PEDV into Canada. These findings led us to conduct a bioassay experiment in which three PEDV-positive SDPP samples (from a single lot) and two PEDV-positive feed samples supplemented with this SDPP were used to orally inoculate 3-week-old piglets. Although the feed-inoculated piglets did not show any significant excretion of PEDV, the SDPP-inoculated piglets shed PEDV at a relatively high level for ≥9 days. Despite the fact that the tested PEDV genome positive feed did not result in obvious piglet infection in our bioassay experiment, contaminated feed cannot be ruled out as a likely source of this introduction in the field where many other variables may play a contributing role.

Natriuretic peptide receptors in the central vasculature of the toad, Bufo marinus

Natriuretic peptide receptors in the central vasculature of the toad, Bufo marinus, were characterized using autoradiographical, molecular, and physiological techniques. Specific ¹²⁵I-rat ANP binding sites were present in the carotid and pulmonary arteries, the lateral aorta, the pre- and post-cava, and the jugular vein, and generally occurred in each layer of the blood vessel. The ¹²5I-rat ANP binding was partially displaced by the specific natriuretic peptide receptor C ligand, C-ANF, which indicates the presence of two types of natriuretic peptide receptors in the blood vessels. This was confirmed by a RT-PCR study, which demonstrated that guanylyl cyclase receptor (NPR-GC) and NPR-C mRNAs are expressed in arteries and veins. An in vitro guanylyl cyclase assay showed that frog ANP stimulated the production of cGMP in arterial membrane fractions. Physiological recordings from isolated segments of the carotid and pulmonary arteries and the lateral aorta, which had been pre-constricted with arginine vasotocin, showed that rat ANP, frog ANP and porcine CNP relaxed the vascular smooth muscle with relatively similar potency. Together, the data show that the central vasculature contains two types of natriuretic peptide receptors (NPR-C and NPR-GC) and that the vasculature is a target for ANP and CNP.

Functional analysis of natriuretic peptide receptors in the bladder of the toad, bufo marinus

This study aimed to localize and characterize natriuretic peptide binding sites in the urinary bladder of Bufo marinus and to then examine the effect of natriuretic peptides on the bladder vascular tone and water reabsorption in isolated perfused bladder preparations. Specific ¹²⁵I-rat atrial natriuretic peptide (¹²⁵I-rANP) binding sites were present on blood vessels, muscle, and epithelium. In tissue sections and/or isolated membranes, the binding was completely displaced by frog ANP, rat ANP, and porcine C-type natriuretic peptide (CNP; membranes only). However, a reduction in binding was observed after incubation with ¹²⁵I-rANP and 1 μM of the natriuretic peptide receptor-C (NPR-C) ligand C-ANF, but residual binding remained suggesting the presence of two distinct binding sites. Electrophoresis of bladder membranes cross-linked to ¹²⁵I-rANP identified two bands at approximately 70 and 140 kDa that correspond to the monomeric mass of NPR-C and the guanylate cyclase receptors, respectively. Furthermore, the presence of natriuretic peptide receptor-A and NPR-C mRNA in the bladder was demonstrated with reverse transcription–polymerase chain reaction. In addition, rat ANP, frog ANP, and porcine CNP stimulated a significant increase in cGMP generation in bladder membrane preparations, which indicated the presence of guanylate cyclase-linked receptors. In perfused bladder preparations, arginine vasotocin increased perfusion pressure and water permeability. The infusion of frog ANP or porcine CNP failed to alter perfusion pressure or water reabsorption in the presence or absence of arginine vasotocin. This study identified a well-developed natriuretic peptide receptor system in the urinary bladder of B. marinus but the function of the receptors remains unclear.

Guanylyl cyclase stimulation by homologous and heterologous natriuretic peptides in salmonids

A range of homologous (trout ANP, trout CNP, trout VNP) and heterologous (eel ANP, eel ANP-NH₂, rat ANP, porcine CNP) NPs were tested for their effect on guanylyl cyclase in gill and kidney membrane preparations from freshwater and seawater-acclimated rainbow trout and Atlantic salmon. All NPs stimulated guanylyl cyclase at 1 µmol l^-1in all preparations. ANP was the most potent stimulator of kidney guanylyl cyclase and CNP the most potent stimulator of guanylyl cyclase in gills. Some differences were apparent between the potencies of homologous and heterologous peptides at 1 µmol l^-1: tANP was more potent than rANP in the SW trout kidney and tCNP was more potent than pCNP in FW salmon tissues. While eANP was more potent than tANP in trout gills, it was less potent than tANP in FW salmon gills. However, there was no significant difference between the potencies of eANP and eANP-NH₂ in trout or salmon gills. Salinity did not affect guanylyl cyclase activity with the exception that trout ANP at 1 µmol l^-1was more potent in SW trout kidneys than in FW trout kidneys. These results suggest a predomination of NPR-A in the kidney and NPR-B in the gill. It appears that salmonid NPR-A and NPR-B are relatively promiscuous in their ligand affinity, with few differences in the potencies of trout and mammalian NPs and only small differences in cGMP production where these differences do occur.

Natriuretic peptides and their receptors in the brain of the amphibian, Bufo marinus

The natriuretic peptides, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are members of a family of hormones that play an important role in mammalian fluid and electrolyte balance. In the periphery, natriuretic peptides reduce blood volume and subsequently blood pressure by increasing renal natriuresis and diuresis and relaxation of vascular smooth muscle. The actions of natriuretic peptides are mediated via two membrane-linked guanylate cyclase receptors (NPR-GC); natriuretic peptide receptor-A (NPR-A) which has a high affinity for ANP and BNP; and natriuretic peptide receptor-B (NPR-B)which has the greatest affinity for CNP. A third receptor not linked to guanylate cyclase, natriuretic peptide receptor-C (NPR-C) also exists, which binds to ANP, BNP and CNP with a relatively equal affinity, and is involved with clearance of the peptides from the circulation and tissues. The natriuretic peptides are present in the brain and are particularly predominant in cardiovascular and fluid and electrolyte regulating areas such as the anteroventral third ventricle (AV3V) region. This distribution has led to the suggestion natriuretic peptides play a neuromodulatory role in the central control of fluid homeostasis. Natriuretic peptides in the brain have been observed to inhibit the release of other fluid and electrolyte regulating hormones such as arginine vasopressin (AVP) and angiotensin II (AII). Natriuretic peptides have also been identified in the non-mammalian vertebrates although information regarding the distribution of the peptides and their receptors in the non-mammalian brain is limited. In amphibians, immunohistochemical studies have shown that natriuretic peptides are highly concentrated in the preoptic region of the brain, an area believed to be analogous to the A\T3\ region in mammals, which suggests that natriuretic peptides may also be involved in central fluid and electrolyte regulation in amphibians. To date, CNP is the only natriuretic peptide that has been isolated and cloned from the lower vertebrate brain, although studies on the distribution of CNP binding sites in the brain have only been performed in one fish species. Studies on the distribution of ANP binding sites in the lower vertebrate brain are similarly limited and have only been performed in one fish and two amphibian species. Moreover, the nature and distribution of the natriuretic peptide receptors has not been characterised. The current study therefore, used several approaches to investigate the distribution of natriuretic peptides and their receptors in the brain of the amphibian Bufo marinus. The topographical relationship of natriuretic peptides and the fluid and electrolyte regulating hormone arginine vasotocin was also investigated, in order to gain a greater understanding of the role of the natriuretic peptide system in the lower vertebrate brain. Immunohistochemical studies showed natriuretic peptides were distributed throughout the brain and were highly concentrated in the preoptic region and interpeduncular nucleus. No natriuretic peptide-like immunoreactivity (NP-IR) was observed in the pituitary gland. Arginine vasotocin-like immunoreactivity (AvT-IR) was confined to distinct regions, particularly in the preoptic/hypothalamic region and pituitary gland. Double labelling studies of NP-JR and AvT-IR showed the peptides are not colocalised in the same neural pathways. The distribution of natriuretic peptide binding sites using the ligands 125I-rat ANP (125I-rANP) and 125I-porcine CNP (125I-pCNP) showed different distributions in the brain of B. marinus. The specificity of binding was determined by displacement with unlabelled rat ANP, porcine CNP and C-ANF, an NPR-C specific ligand. 125I-rANP binding sites were broadly distributed throughout the brain with the highest concentration in pituitary gland, habenular, medial pallium and olfactory region. Minimal 125I-rANP binding was observed in the preoptic region. Residual 125I-rANP binding in the presence of C-ANF was observed in the olfactory region, habenular and pituitary gland indicating the presence of both NPR-GC and NPR-C in these regions. 125I-pCNP binding was limited to the olfactory region, pallium and posterior pituitary gland. All 125I-pCNP binding was displaced by C-ANF which suggests that CNP in the brain of B. marinus binds only to NPR-C. Affinity cross-linking and SDS-PAGB demonstrated two binding sites at 136 kDa and 65 kDa under reducing conditions. Guanylate cyclase assays showed 0.1 µM ANP increased cGMP levels 50% above basal whilst a 10-fold higher concentration of CNP was required to produce the same result. Molecular cloning studies revealed a 669 base pair fragment showing 91% homology with human and rat NPR-A and 89% homology with human, rat and eel NPR-B. A 432 base pair fragment showing 67% homology to the mammalian NPR-C and 58% homology with eel NPR-D was also obtained. The results show natriuretic peptides and their receptors are distributed throughout the brain of B. marinus which indicates that natriuretic peptides may participate in a range of regulatory functions throughout the brain. The potential for natriuretic peptides to regulate the release of the fluid and electrolyte regulating hormone AVT also exists due to the high number of natriuretic peptide binding sites in the posterior pituitary gland. At least two populations of natriuretic peptide receptors are present in the brain of B. marinus, one linked to guanylate cyclase and one resembling the mammalian clearance receptor. Furthermore, autoradiography and guanylate cyclase studies suggest ANP may be the major ligand in the brain of B. marinus, even though CNP is the only natriuretic peptide that has been isolated from the lower vertebrate brain to date.

Adaptive mechanically controlled lubrication mechanism found in articular joints

Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple "modes" of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an "adaptive" role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) "boundary lubricant"-reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication; however, the system as a whole requires both HA and LUB to function optimally under all conditions.

Phylogenetic analysis of beak and feather disease virus across a host ring-species complex

Pathogens have been hypothesized to play a major role in host diversity and speciation. Susceptibility of hybrid hosts to pathogens is thought to be a common phenomenon that could promote host population divergence and subsequently speciation. However, few studies have tested for pathogen infection across animal hybrid zones while testing for codivergence of the pathogens in the hybridizing host complex. Over 8 y, we studied natural infection by a rapidly evolving single-strand DNA virus, beak and feather diseases virus (BFDV), which infects parrots, exploiting a host-ring species complex (Platycercus elegans) in Australia. We found that host subspecies and their hybrids varied strikingly in both BFDV prevalence and load: both hybrid and phenotypically intermediate subspecies had lower prevalence and load compared with parental subspecies, while controlling for host age, sex, longitude and latitude, as well as temporal effects. We sequenced viral isolates throughout the range, which revealed patterns of genomic variation analogous to Mayr's ring-species hypothesis, to our knowledge for the first time in any host-pathogen system. Viral phylogeny, geographic location, intraspecific host density, and parrot community diversity and composition did not explain the differences in BFDV prevalence or load between subpopulations. Overall, our analyses suggest that functional host responses to infection, or force of infection, differ between subspecies and hybrids. Our findings highlight the role of host hybridization and clines in altering host-pathogen interactions, dynamics that can have important implications for models of speciation with gene flow, and offer insights into how pathogens may adapt to diverging host populations.

Lipid profiles, in vitro digestion and oxidative stability of mutton bird oil

The lipid profile, in vitro digestion and oxidative stability of mutton bird oil were investigated. Wax ester, triacylglycerol and sterol were the major lipids present as determined using capillary chromatography with flame ionisation detector (Iatroscan). Fatty acid analysis by gas chromatography (GC) showed that wax esters had a higher total omega-3 fatty acids content including EPA, DPA and DHA than TAGs (31 % and 24 %, respectively). In TAGs, 13C nuclear magnetic resonance (NMR) data showed that EPA was statistically positioned at sn-1,3 and sn-2, while DHA was preferentially at sn-2. In vitro digestion using porcine pancreatic lipase resulted in 75 % of TAG and 10 % wax ester hydrolysis in 120 min. As reflected in the measured conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS) values during accelerated oxidation at 60 °C for 5 days, the oil was relatively stable against oxidation considering its high omega-3 content.

A colostrum trypsin inhibitor gene expressed in the Cape fur seal mammary gland during lactation

The colostrum trypsin inhibitor (CTI) gene and transcript were cloned from the Cape fur seal mammary gland and CTI identified by in silico analysis of the Pacific walrus and polar bear genomes (Order Carnivora), and in marine and terrestrial mammals of the Orders Cetartiodactyla (yak, whales, camel) and Perissodactyla (white rhinoceros). Unexpectedly, Weddell seal CTI was predicted to be a pseudogene. Cape fur seal CTI was expressed in the mammary gland of a pregnant multiparous seal, but not in a seal in its first pregnancy. While bovine CTI is expressed for 24-48h postpartum (pp) and secreted in colostrum only, Cape fur seal CTI was detected for at least 2-3months pp while the mother was suckling its young on-shore. Furthermore, CTI was expressed in the mammary gland of only one of the lactating seals that was foraging at-sea. The expression of β-casein (CSN2) and β-lactoglobulin II (LGB2), but not CTI in the second lactating seal foraging at-sea suggested that CTI may be intermittently expressed during lactation. Cape fur seal and walrus CTI encode putative small, secreted, N-glycosylated proteins with a single Kunitz/bovine pancreatic trypsin inhibitor (BPTI) domain indicative of serine protease inhibition. Mature Cape fur seal CTI shares 92% sequence identity with Pacific walrus CTI, but only 35% identity with BPTI. Structural homology modelling of Cape fur seal CTI and Pacific walrus trypsin based on the model of the second Kunitz domain of human tissue factor pathway inhibitor (TFPI) and porcine trypsin (Protein Data Bank: 1TFX) confirmed that CTI inhibits trypsin in a canonical fashion. Therefore, pinniped CTI may be critical for preventing the proteolytic degradation of immunoglobulins that are passively transferred from mother to young via colostrum and milk.