SIM1基因第8外显子的SNP对猪背膘厚的影响

采用PCR-SSCP方法检测了约克夏、杜洛克、皮特兰、长白猪、嘉兴黑猪和金华猪6个品种共169头猪的SIM1基因外显子8的SNP及其基因型频率。结果共发现CC、CT、TT 3种基因型, 其基因型频率在国内外猪品种之间具有较大差异。其中, 国内猪种嘉兴黑猪和金华猪只存在TT基因型, 而国外猪种约克夏、杜洛克、皮特兰、长白猪则都存在3种基因型。用最小二乘法分析SNP对长白猪、约克夏猪和杜洛克猪的背膘厚的效应的结果表明, 纯合基因型个体的背膘厚大于杂合基因型个体。SIM1基因型对国外猪种背膘厚有显著效应(P< 0.05), 并且不同部位效应不同。     

猪Mx1基因第14外显子多态性分析及新突变位点的 发现

采用PCR-RFLP方法对国内外7个猪种Mx1基因第14外显子的多态性进行分析, 共检测到3个等位基因, 6种基因型。其中杜洛克中仅存在AA基因型, 苏太猪中存在全部基因型, 只有在梅山猪和具有梅山猪血统的苏太猪中出现基因型BB。所有猪种中, 只有在地方猪种和培育猪种中出现等位基因B, 所有猪种除松辽黑猪外均以A为优势等位基因。卡方检验结果表明, 不同猪种间基因型分布差异较大, 梅山猪和松辽黑猪与其他所有猪种的基因型频率差异极显著(P＜0.01) , 苏太猪与除皮特兰猪外的所有猪种的基因型频率差异也极显著(P＜0.01) , 淮猪与杜洛克和约克夏这两个国外猪种基因型频率差异不显著(P＞0.05), 而与皮特兰和其他地方猪种的基因型频率均存在极显著差异(P＜0.01) 。通过测序在扩增片段中新发现了3种类型的碱基突变, 前2个分别导致了Thr和Glu向Ala和Arg的替换, 最后一个突变不引起氨基酸的变化, 且后两个突变位点为BB基因型所特有。     

The role of luminal gastrin in the regulation of pancreatic juice secretion in preruminant calves

The effect of luminal gastrin on the secretion of pancreatic juice was studied in seven conscious preruminant calves employing luminal infusions of gastrin and cholecystokinin (CCK)-9 and pharmacological CCK1 and CCK2 receptor blocks with antagonists. The study was performed in the preprandial and prandial states. Pharmacological blocking of the CCK2 receptor, like that of the CCK1 receptor, resulted in reduction of pancreatic postprandial secretion and increased the duration of the prandial pattern of duodenal electrical activity. Exogenous luminal gastrin, like luminal CCK-9, enhanced the secretion of pancreatic juice proteins, though the overall effect of gastrin was weaker than that of CCK-9. The effect was inhibited by infusion of CCK2 but also by CCK1 receptor antagonist. In conclusion, duodenal luminal gastrin can stimulate exocrine pancreatic secretion by a mechanism that depends on CCK2 receptors in calves. Involvement of the CCK1 receptor in this mechanism needs further investigation. Prandial pancreatic secretory and duodenal motility cycles can be regulated by endogenous gastrin release.     

Pancreatic secretory response to feeding in the calf: CCK-A receptors, but not CCK-B/gastrin receptors are involved

In bovine species, as in human, the pancreas predominantly expresses cholecystokinin-B (CCK-B)/gastrin receptors. However, the role of this receptor in the regulation of meal-stimulated pancreatic enzyme release has not been determined. In milk-fed calves, we previously described prandial patterns of exocrine pancreatic secretion and a long prefeeding phase was observed. The present study was aimed at determining both the role of external stimuli in the outset of the prefeeding phase and the implication of pancreatic CCK-A and CCK-B/gastrin receptors in the mediation of pancreatic response to feeding. The first objective was studied by suppressing external stimuli associated with food intake (unexpected meal) and the second by infusing highly specific and potent antagonists of CCK-A (SR 27897) and CCK-B/gastrin (PD 135158) receptors during the prandial period. When calves were given an unexpected meal, the long prefeeding increase in pancreatic secretion was absent. SR 27897 (but not PD 135158) inhibited the preprandial phase and greatly reduced postprandial pancreatic juice and enzyme outflows. The expectancy of a meal seemed to elicit an increased pancreatic response right before a meal and CCK-A receptors may mediate this information via neural pathways. The implication of CCK and CCK-A receptors in mediating the postfeeding pancreatic response was also demonstrated. The participation of CCK-B/gastrin receptors in this regulation was not demonstrated.     

Effect of Bacillus mucilaginosus biomass on the exocrine function of the pancreas in piglets]

The effect of mucous bacilli on the excretory activity of pancreas in pigs has been investigated. The use of biomass at doses of 0.1, 0.2 and 0.3 g/kg stimulates to a different extent the pancreatic exocrine function in pigs: the pancreatic juice volume increases, on the average, by 17-20% and the secretion of amylolytic, proteolytic and lipolytic enzymes of the pancreatic juice becomes 1.6-2.2, 1.5-1.8 and 1.4-1.7 times higher, respectively. The increased functional activity of pancreas indicates the high reserve secretory potential of the pancreatic secretory apparatus. When brought into action, this apparatus favours more complete segregation and absorption of food nutrients.     

Presence of somatostatin-like immunoreactivity in rat pancreatic juice: a physiological phenomenon

These studies were performed to assess the effects of various exocrine pancreatic stimuli on somatostatin-like immunoreactivity (SLI) secretion in pure rat pancreatic juice. Ingestion of a meal and subcutaneous injections of caerulein (CA), secretin (SE), and their combination (CA + SE) were compared. Basal fasting SLI output over 5 1/2 h averaged 13.7 ng/30 min; the response to feeding resulted in decreased SLI outputs from 9.7 to 1.7 ng/30 min, a reduction of 81%. SLI secretion following CA, SE, and CA + SE was similar to that obtained following feeding but the reductions of 29, 32, and 39% were less marked and of shorter duration. A return to basal SLI levels was observed only 2 1/2 h following CA administration. Increases in pancreatic volume and protein outputs following CA, SE, and CA + SE were comparable to the feeding response although less pronounced. These data indicate that SLI secretion in pure pancreatic juice can be modulated by two peptides and feeding and that its release is reduced when compared with increases in pancreatic volume and protein secretion. The observation that the peptide's response in terms of SLI output as well as protein and volume were in the same range, although less sustained than the response to a meal, indicates that all stimuli used induced a physiological response of the pancreas.     

Identification of insulin in the human pancreatic juice

In this study, we purified insulin-like substance (ILS) in the human pancreatic juice by the combined use of affinity chromatography and radioimmunoassay (RIA). The amino acid sequence of ILS in the N-terminal region is the same as that of human insulin. The influence of the enzymes present in the pancreatic juice on the RIA procedure, was examined. Trypsin, chymotrypsin and amylase showed steep influences on radioactivity. The addition of enzyme inhibitors could not reduce pseudo-activity, but the elimination of enzymes in the pancreatic juice by ultrafiltration with the Mole-Cut (Millipore, Japan) resulted in a lowering of the pseudo-insulin activity. Affinity chromatography on Sepharose 4B coupled with anti-porcine insulin was used to capture ILS. ILS was eluted by 1 M acetic acid from the affinity column monitoring pH and the insulin activity by RIA. The amino acid sequences of two components of ILS in amino terminal region were Phe-Val and Gly-Ile-Val. This indicates that ILS obtained from human pancreatic juice was the insulin derived from endocrine secretion of pancreas.     

Effect of sire breed on carcass characteristics and meat and fat quality of heavy pigs reared outdoor and intended for dry-cured meat production

A trial was conducted to study the effect of sire line (Duroc (DU) and Pietrain (PI)) on carcass, meat and fat quality of pigs reared outdoor and destined to dry-cured meat production. No differences between sire genotypes were detected in carcass fat thickness (P > 0.10) but carcasses from DU-sired pigs were longer (P < 0.05) and tended to have a higher yield of trimmed shoulders (P = 0.07) and hams (P = 0.06) than carcasses from PI-sired pigs. Loins from DU-sired genotype showed higher (P < 0.05) L* value and lower (P < 0.01) a* value than loins from PI-sired genotype. Pork from DU-sired offspring tended to have higher (P = 0.09) intramuscular fat (IMF) percentage and lower (P < 0.05) moisture proportion than meat from PI-sired offspring. Also, loins from DU-sired pigs had lower (P < 0.001) thawing losses than loins from PI-sired pigs. The subcutaneous fat from the DU-sired line tended to show lower (P = 0.08) percentage of total polyunsaturated fatty acids (PUFAs) than that from the PI-sire line, mostly due to the higher proportion of C18:2 (P = 0.09) and C20:3 (P < 0.01). However, no effect of crossbreed was detected on the total proportion of saturated, monounsaturated fatty acid (MUFAs) or PUFAs of IMF (P > 0.10). We conclude that both sire lines can be used successfully under outdoor conditions but DU boars are more adequate than PI boars for the production of heavy pigs intended for the dry-cured meat industry.     

Pathological changes in the microstructure of longissimus lumborum muscle from five breeds of pigs

The aim of the study was to determine the extent of histopathological changes in m. longissimus lumborum of PL, PLW, Duroc, Pietrain, and Pu?awska pigs (N = 30 per breed) aged 210 days. Changes in fibre size (atrophy, hypertrophy - giant fibres), changes in fibre shape (angular fibres), degenerative lesions (necrosis with phagocytosis) and connective tissue hypertrophy were evaluated. The percentage of individual pathological changes in m. longissimus lumborum of the analysed pig breeds was relatively low. Significantly more normal fibres were found in the muscles of Pu?awska compared to Pietrain pigs. Muscle fibre atrophy was the most frequent and extensive histopathological change. The muscles of Pu?awska pigs had significantly fewer atrophic, giant and angular fibres, significantly less necrosis with phagocytosis, and less animals with connective tissue hypertrophy compared to the other pig breeds. On the other hand, Pietrain pigs were characterized by a greater number of animals with giant fibres and a significantly higher proportion of giant fibres compared to the other breeds. Also the diameter of giant fibres was the largest in Pietrain, intermediate in PL and PLW, and the smallest in Duroc and Pulawska pigs. Moreover, current findings indicate that giant fibres may arise from each muscle fibre type (I, IIA and IIB). It is concluded that selection of pigs for increased leanness contributes to the incidence of histopathological changes, which may decrease pork quality.     

SNPs in the porcine <Emphasis Type="Italic">PPARGC1a</Emphasis> gene: Interbreed differences and their phenotypic effects

Due to its function, the peroxisome proliferative activated receptor-γ, coactivator-1α (PPARGC1A) gene is a candidate in the search for genes that may affect production traits in the pig. The purpose of this study was to screen for new SNPs in exon 8 of the porcine PPARGC1A gene and to test their possible association with production traits. Altogether 736 pigs representing five breeds Polish Landrace, n=242; Polish Large White, n=192; Hampshire, n=27; Duroc, 21; Pietrain, n=12) and synthetic line 990 (n=242) were scanned via SSCP assay. Four SNPs were found; two new ones: C/G (His338Gln) and G/A Thr359Thr), and two previously reported ones: C/A (Arg369Arg) and T/A Cys430Ser). The missense T/A and C/G SNPs demonstrated pronounced interbreed variability in terms of allele frequencies, including the exclusive presence of the C/G substitution in the Hampshire breed. The tested SNPs occurred in five putative haplotypes, and their frequency also differed substantially between breeds. The association of the SNPs with production traits was tested for G/A (Thr359Thr), C/A (Arg369Arg) and T/A (Cys430Ser) substitutions in Polish Large White, Polish Landrace and line 990. The analysis revealed only breed-specific associations. The T/A (Cys430Ser) SNP was related to the feed conversion ratio in the Polish Large White (P=0.02), and the silent G/A and C/A substitutions were respectively associated with abdominal fat in line 990 and backfat thickness in Polish Landrace (P=0.04). The combined effects of the substitutions were estimated as haplotype effects. Three significant contrasts between haplotypes were calculated, but the observed associations were again only breed-specific.     

Investigation of uniformity in pig carcass and meat quality traits

The study was carried out to provide information on uniformity of commercial pigs on some of the most important traits determining pork quality: carcass, loin, ham and shoulder weights, fatness, drip loss, pH and colour. Three batches of pigs raised at the same farm and slaughtered at four different dates in the same commercial abattoir were considered. Batches included halothane-free females and castrated males, Duroc and Pietrain sire lines and two slaughter weights, but a common maternal line. The first batch was obtained using commercial Duroc sire boars, and included a total of 112 animals (56 castrated males and 56 females). The second batch used Duroc and Pietrain sire boars with the target to achieve two different final weights (105 and 115 kg live weight); 128 animals were controlled (64 castrated males and 64 females), 16 for each combination of sire boar, sex and final weight. The last batch used only Pietrain sire boars with 96 controlled pigs (48 castrated males and 48 females). The uniformity was measured by the coefficient of variation (CV) and the coefficient of dispersion (CD) for all data available, and for groups of common sex, sire breed and slaughter weight. Differences in uniformity were tested among traits and groups by using confidence intervals (CIs) at 95% confidence level (CI95%) for the CV and CD. Results showed a significantly lower uniformity for drip loss (CV = 40.4%, CI95% 36.9% to 44.7%; CD = 32.1%, CI95% 28.7% to 35.4%) and backfat (CV = 22.8%, CI95% 21.1% to 24.8%; CD = 18.3%, CI95% 17.1% to 20.2%) the pH being the most uniform trait (CV = 3.2%, CI95% 3.0% to 3.5%; CD = 2.6%, CI95% 2.4% to 2.9%). When comparing different 'sire breed-sex-slaughter weight' groups, no consistent sex and slaughter weight differences in uniformity were found, but animals from Pietrain sire breed showed a tendency to be less uniform for carcass traits than animals from Duroc sire breed. Nevertheless, variability within those groups was very high and often similar to that observed when considering all the animals from all the groups. Small differences were found comparing uniformity when using the CV or the CD. CIs of these coefficients have proved to be a simple and useful tool for testing differences in uniformity.     

Responses of the exocrine pancreatic secretion to spontaneous feeding in rats with bile-pancreatic juice diversion

The regulatory response of the exocrine pancreas was examined in rats under unanesthetized and unrestrained conditions. The previous study demonstrated that the pancreatic protease secretion increased 2-fold after spontaneous feeding of a low protein diet in chronically bile-pancreatic cannulated rats (normal rats) whose bile-pancreatic juice (BPJ) was returned to the duodenum. In the present study, we observed the response of the exocrine pancreatic secretion to spontaneous feeding of a low protein diet in rats with chronic diversion of BPJ from the proximal small intestine for 6 days (bypass rat) whose diverted BPJ was returned to the upper ileum. During BPJ diversion, the dry weight and the protein content of the pancreas were increased 2-fold, compared with normal rats. Also, the levels of trypsinogen and chymotrypsinogen in the pancreas were increased several times, but amylase was decreased. The basal secretion of enzymes after a 24-hr fast was enhanced in bypass rats in proportion to the pancreatic enzyme contents. After spontaneous feeding of 8% casein fat-free diet, the increases in the pancreatic secretion of bypass rats were much smaller than those of normal rats. In contrast, the increase of BPJ flow of bypass rats after feeding was greater than that of normal rats. These findings represent that the chronic diversion of BPJ exerts hypergrowth of pancreas and hypersecretion of proteases in the fasting state, and less sensitivity of pancreatic enzyme secretion to dietary feeding.     

Novel Polymorphisms in Porcine 3′UTR of the Leptin Gene,Including a Rare Variant within Target Sequence for MIR-9 Gene in Duroc Breed,not Associated with Production Traits

The leptin gene (LEP) is considered as a functional candidate for production traits in livestock due to its crucial role in energy homeostasis. Because polymorphisms in regulatory sequences may affect gene expression, we searched for them in the 3′UTR of LEP and analyzed their association with production traits. Four breeds and a composite line were studied. In the Polish Landrace and Polish Large White breeds, 8 SNPs and 1 indel were observed; whereas, in the Duroc breed, 9 specific SNPs were found. Pietrain and Line 990 were monomorphic. One SNP (g.+168C>T), observed in the Duroc breed only, was located within a target site for microRNA (miR-9). Association studies showed a weak association between one SNP (c.+846C>T) and abdominal fat weight in the Polish Landrace only. Thus, we concluded that contribution of polymorphisms in the 3′UTR to phenotypic variability of pig production traits is marginal. Moreover, we presented an overview of known polymorphisms (128) in the pig leptin gene.     

Two hypotheses on the feedback regulation of pancreatic enzyme secretion

We review the mechanisms underlying the feedback regulation of pancreatic enzyme secretion in response to a meal. Pancreatic enzyme secretion in the rat and pig is known to be regulated by a negative feedback mechanism mediated by intestinal trypsin and chymotrypsin. Such a mechanism has recently been noted in humans. The presence of these enzymes in the small intestine suppresses pancreatic enzyme secretion, whereas their removal increases it. Two novel peptides have been proposed to account for the stimulation of pancreatic enzyme secretion in response to feeding trypsin inhibitor. One was assumed to be present in rat pancreatic juice and the other to be spontaneously secreted from the rat small intestine. In either case, trypsin and trypsin inhibitors do not directly interact with the luminal surface of the small intestine, but their actions are mediated by a trypsin-sensitive, cholecystokinin-releasing peptide. This is a novel explanation of the well-recognized stimulation of pancreatic enzyme secretion in response to dietary protein intake.     

ATP-consuming and ATP-generating enzymes secreted by pancreas

Pancreatic acini release ATP in response to various stimuli, including cholecystokinin octapeptide (CCK-8), as we show in the present study. There were indications that pancreatic juice also contains enzymes that could hydrolyze ATP during its passage through the ductal system. The aim of this study was to determine which ATP-degrading and possibly ATP-generating enzymes were present in pancreatic secretion. For this purpose, pancreatic juice was collected from anesthetized rats stimulated with infusion of CCK-8. Purine-converting activities in juice samples were assayed by TLC using either [gamma-(32)P]ATP or (14)C/(3)H-labeled and unlabeled nucleotides as appropriate substrates. Data show that the juice contains the enzyme ecto-nucleoside triphosphate diphosphohydrolase that can hydrolyze both [(14)C]ATP and [(3)H]ADP about equally well, i.e. CD39. Reverse-phase high-performance liquid chromatography analysis additionally shows that this enzyme has broad substrate specificity toward other nucleotides, UTP, UDP, ITP, and IDP. In addition, secretion contains ecto-5'-nucleotidase, CD73, further converting [(3)H]AMP to adenosine. Along with highly active hydrolytic enzymes, there were also ATP-generating enzymes in pancreatic juice, adenylate kinase, and NDP kinase, capable of sequentially phosphorylating AMP via ADP to ATP. Activities of nonspecific phosphatases, nucleotide pyrophosphatase/phosphodiesterases, and adenosine deaminase were negligible. Taken together, CCK-8 stimulation of pancreas causes release of both ATP-consuming and ATP-generating enzymes into pancreatic juice. This newly discovered richness of secreted enzymes underscores the importance of purine signaling between acini and pancreatic ducts lumen and implies regulation of the purine-converting enzymes release.     

The footprint of recent and strong demographic decline in the genomes of Mangalitza pigs

The Mangalitza pig breed has suffered strong population reductions due to competition with more productive cosmopolitan breeds. In the current work, we aimed to investigate the effects of this sustained demographic recession on the genomic diversity of Mangalitza pigs. By using the Porcine Single Nucleotid Polymorphism BeadChip, we have characterized the genome-wide diversity of 350 individuals including 45 Red Mangalitza (number of samples; n=20 from Hungary and n=25 from Romania), 37 Blond Mangalitza, 26 Swallow-belly Mangalitza, 48 Blond Mangalitza × Duroc crossbreds, 5 Bazna swine, 143 pigs from the Hampshire, Duroc, Landrace, Large White and Pietrain breeds and 46 wild boars from Romania (n=18) and Hungary (n=28). Performance of a multidimensional scaling plot showed that Landrace, Large White and Pietrain pigs clustered independently from Mangalitza pigs and Romanian and Hungarian wild boars. The number and total length of ROH (runs of homozygosity), as well as F_ROH coefficients (proportion of the autosomal genome covered ROH) did not show major differences between Mangalitza pigs and other wild and domestic pig populations. However, Romanian and Hungarian Red Mangalitza pigs displayed an increased frequency of very long ROH (>30 Mb) when compared with other porcine breeds. These results indicate that Red Mangalitza pigs underwent recent and strong inbreeding probably as a consequence of severe reductions in census size.     

Associations of functional candidate genes derived from gene-expression profiles of prenatal porcine muscle tissue with meat quality and muscle deposition

Ten genes (ANK1, bR10D1, CA3, EPOR, HMGA2, MYPN, NME1, PDGFRA, ERC1, TTN), whose candidacy for meat-quality and carcass traits arises from their differential expression in prenatal muscle development, were examined for association in 1700 performance-tested fattening pigs of commercial purebred and crossbred herds of Duroc, Pietrain, Pietrain x (Landrace x Large White), Duroc x (Landrace x Large White) as well as in an experimental F(2) population based on a reciprocal cross of Duroc and Pietrain. Comparative sequencing revealed polymorphic sites segregating across commercial breeds. Genetic mapping results corresponded to pre-existing assignments to porcine chromosomes or current human-porcine comparative maps. Nine of these genes showed association with meat-quality and carcass traits at a nominal P-value of < or = 0.05; PDGFRA revealed no association reaching the P < or = 0.05 threshold. In particular, HMGA2, CA3, EPOR, NME1 and TTN were associated with meat colour, pH and conductivity of loin 24 h postmortem; CA3 and MYPN exhibited association with ham weight and lean content (FOM) respectively at P-values of < 0.003 that correspond to false discovery rates of < 0.05. However, none of the genes showed significant associations for a particular trait across all populations. The study revealed statistical-genetic evidence for association of the functional candidate genes with traits related to meat quality and muscle deposition. The polymorphisms detected are not likely causal, but markers were identified that are in linkage disequilibrium with causal genetic variation within particular populations.