Precipitating antibodies of the duck (Anas platyrhynchos)

1. Ducks do not usually produce precipitating antibodies. However, when hyperimmunized with the dinitrophenyl (DNP)-human IgG (HIgG) conjugate, ducks made precipitating antibodies to the HIgG carrier, though not to the DNP hapten. 2. Precipitation did not require NaCl and occurred over a wide range of molarities and pH. 3. Antigenic and polyacrylamide gel analysis of affinity-purified antibodies, indicated that the major constituent of the antibody population was electrophoretically homogeneous 5.7S IgG. 4. The Ig heavy chains were in two populations, viz MW 37,000 and 41,000; non-precipitating duck 5.7S IgG antibodies to HIgG had only the MW 37,000 heavy chains. 5. It is suggested that duck precipitins belong to a previously unrecognized subclass of duck 5.7S IgG, with minor physical and antigenic differences from their non-precipitating counterparts.     

Retinohypothalamic pathway in the duck (Anas platyrhynchos)

Summary Retinohypothalamic connections were studied in the duck after unilateral optic nerve transection using both light and electron microscopic techniques. Degenerated endings of optic fibers were found only in a circumscribed part of the anterior hypothalamic area, i.e. the ventral region of the contralateral suprachiasmatic nucleus. Images of degenerating boutons were observed in frozen sections (method according to Johnstone-Bowsher), and their presence confirmed by electron microscopic examination. These degenerating boutons make synaptic contacts with dendrites or dendritic spines of neurons of the suprachiasmatic nucleus.In the same material, the decussation of the optic chiasma was studied with the light microscope. Uncrossed retinal fibers were found in the marginal optic tract, the basal optic root and occasionally also in the isthmo-optic tract.Dedicated to Professor Dr. W. Bargmann on the occasion of his 70th birthdaySupported by the DGRST and European Training Program Brain and Behaviour ResearchI wish to express my gratitude to Professor Andreas Oksche, who repeatedly offered me the scientific facilities at the Department of Anatomy of the University of Giessen, and who provided me with valuable neuroanatomical suggestions throughout the progress of these studies.     

Description of the mallard duck (Anas platyrhynchos) karyotype

The karyotype of the mallard duck, Anas platyrhynchos, was characterised on the basis of R and C bands. Chromosomal preparations obtained from in vitro blood lymphocyte cultures were RBG- and CBG-stained. The structures of nine and 14 pairs of chromosomes were analysed by the RBG and CBG chromosome banding techniques, respectively. The location of R bands, as well as the size and arrangement of constitutive heterochromatin blocks were determined. Ideograms of R and C banded patterns of the analysed chromosomes were drawn. The morphological makeup of the analysed chromosomes was assessed.     

Adrenergic control of hypothalamic function during osmotic stress in the mallard duck (Anas platyrhynchos)

Summary The role of the paraventricular nucleus (PVN) and biogenic amines (BA) in regulating the level of corticoids in the serum of osmotically stressed mallard ducks (Anas platyrhynchos) was analyzed employing three experimental approaches: 1) pharmacologic alteration of central BA levels, 2) microscopic evaluation of BA distribution, and 3) placement of electrolytic lesions into the PVN. Reserpine and -methyl-p-tyrosine (mpt), agents that decrease the amount of BA's in the central nervous system, produced a fivefold increase in the concentration of serum corticoids. Conversely, pargyline and amphetamine, agents that increase the functional pool of BA's, prevented the rise in serum corticoid concentration normally observed in birds challenged with an intraperitoneal injection of hypertonic saline. When the topographic distribution of BA's was analyzed in the brains of osmotically stressed and nonstressed ducks distinct changes in the intensity of catecholamine (CA) fluorescence were observed in only one location, the PVN of the hypothalamus. Additionally, electrolytic lesions stereotaxically placed in the PVN blocked the osmotic stress-induced rise in serum corticoid concentration. These data therefore indicate that the PVN in the mallard duck plays some role in regulating the observed stress-induced rise in serum corticoid concentration, and that this regulatory function is probably inhibited by catecholamines.This research was supported by research grant No. GB 33321 from the National Science Foundation. We wish to express our sincere thanks to Mr. Howard Funk, research director, Colorado Division of Wildlife, for the use of the State's animal facilitiesThis research was submitted as partial fulfillment for the degree of Doctor of Philosophy, Department of Physiology and Biophysics, Colorado State University, Ft. Collins, CO 80521     

Characterization of 35 novel microsatellite DNA markers from the duck (Anas platyrhynchos) genome and cross-amplification in other birds

In order to study duck microsatellites, we constructed a library enriched for (CA)n, (CAG)n, (GCC)n and (TTTC)n. A total of 35 pairs of primers from these microsatellites were developed and used to detect polymorphisms in 31 unrelated Peking ducks. Twenty-eight loci were polymorphic and seven loci were monomorphic. A total of 117 alleles were observed from these polymorphic microsatellite markers, which ranged from 2 to 14 with an average of 4.18 per locus. The frequencies of the 117 alleles ranged from 0.02 to 0.98. The highest heterozygosity (0.97) was observed at the CAUD019 microsatellite locus and the lowest heterozygosity (0.04) at the CAUD008 locus, and 11 loci had heterozygosities greater than 0.50 (46.43%). The polymorphism information content (PIC) of 28 loci ranged from 0.04 to 0.88 with an average of 0.42. All the above markers were used to screen the polymorphism in other bird species. Two markers produced specific monomorphic products with the chicken DNA. Fourteen markers generated specific fragments with the goose DNA: 5 were polymorphic and 9 were monomorphic. But no specific product was detected with the peacock DNA. Based on sequence comparisons of the flanking sequence and repeat, we conclude that 2 chicken loci and 14 goose loci were true homologous loci of the duck loci. The microsatellite markers identified and characterized in the present study will contribute to the genetic map, quantitative traits mapping, and phylogenetic analysis in the duck and goose.     

Ependymal and neuronal specializations in the lateral ventricle of the Pekin duck,Anas platyrhynchos

Summary The lateral ventricles of the Pekin duck, Anas platyrhynchos, display characteristic ependymal and hypendymal specializations. Adjacent to the nucleus accumbens and the basal pole of the lateral septum the ventricular surface shows a highly folded pattern either with protrusions into the ventricular lumen or deep invaginations into the brain tissue. These medial and basal ependymal folds are found exclusively in a circumscribed region extending over a range of 600 m in the rostrocaudal direction. Ependymal folds occurring in the lateral wall of the ventricles were traced up to the level of the interventricular foramen. Numerous capillaries are observed in the subependymal layer of these folds.By means of immunocytochemistry with antibodies against chicken vasoactive intestinal polypeptide (VIP) an aggregation of classical cerebrospinal fluid-contacting neurons is shown in the region of the nucleus accumbens and the lateral septum. These neurons are closely related to the ependymal folds. Additional VIP-immunoreactive neurons are scattered in deeper layers of the lateral septum and the nucleus accumbens. The latter are richly innervated by VIP-immunoreactive nerve fibers.The results of the present study are discussed with particular reference to the hypothesis of Kuenzel and van Tienhoven (1982) that ependymal specializations demonstrated in the lateral ventricles of the domestic fowl might represent a new circumventricular organ (lateral septal organ).The authors are greatly indebted to Professor A. Oksche for stimulating discussionsSupported by the Deutsche Forschungsgemeinschaft (Ko 758/2-2; 2-3) and the P. Carl Petersen Foundation     

Silencing Pax3 by shRNA inhibits the proliferation and differentiation of duck (Anas platyrhynchos) myoblasts

The Pax3 gene has been proven to play a crucial role in determining myogenic progenitor cell fate during embryonic myogenesis; however, the molecular role of Pax3 in myoblast development during later stages of myogenesis is unknown. We hypothesized that Pax3 would function in myoblast proliferation and differentiation; therefore, we employed three short hairpin RNAs (shRNAs) (shRNA1, shRNA2, and shRNA3) that target Pax3 to characterize the function of Pax3 in duck myoblast development. The mRNA and protein expression levels of Pax3 in duck myoblasts were detected using real-time PCR and Western blotting. Cell proliferation was assessed using the MTT and BrdU assays, while cell differentiation was assayed using immunofluorescence labeling with a MyoG antibody. Additionally, folic acid (FA), which is a rescue tool, was added into the medium of duck myoblasts to indirectly examine the function of Pax3 on duck myoblast proliferation and differentiation. The results revealed that one of the shRNA vectors, shRNA1, could significantly and stably reduce the expression of Pax3 (P < 0.05). Silencing Pax3 by shRNA1 significantly reduced the proliferation and differentiation of duck myoblasts (P < 0.05) due to downregulated expression of myogenic regulator factors. These trends could be rescued by adding FA; and Pax7, a paralog gene of Pax3, was involved in those processes. Overall, Pax3 had a positive function in duck myoblast proliferation and differentiation by modulating the expression of myogenic regulation factors, and shRNA targeting of Pax3 might be a new approach for understanding the function of Pax3 in the development of diverse tissues.     

A genetic and cytogenetic map for the duck (Anas platyrhynchos)

A genetic linkage map for the duck (Anas platyrhynchos) was developed within a cross between two extreme Peking duck lines by linkage analysis of 155 polymorphic microsatellite markers, including 84 novel markers reported in this study. A total of 115 microsatellite markers were placed into 19 linkage groups. The sex-averaged map spans 1353.3 cM, with an average interval distance of 15.04 cM. The male map covers 1415 cM, whereas the female map covers only 1387.6 cM. All of the flanking sequences of the 155 polymorphic loci--44 monomorphic loci and a further 41 reported microsatellite loci for duck--were blasted against the chicken genomic sequence, and corresponding orthologs were found for 49. To integrate the genetic and cytogenetic map of the duck genome, 28 BAC clones were screened from a chicken BAC library using the specific PCR primers and localized to duck chromosomes by FISH, respectively. Of 28 BAC clones, 24 were detected definitely on duck chromosomes. Thus, 11 of 19 linkage groups were localized to 10 duck chromosomes. This genetic and cytogenetic map will be helpful for the mapping QTL in duck for breeding applications and for conducting genomic comparisons between chicken and duck.     

Pre-natal development of the adrenal gland in the mallard duck (Anas platyrhynchos)

Summary The differentiating nephrotome in the 10-day-old mallard duck embryo is able to synthesize corticosterone, aldosterone and deoxycorticosterone even though an adrenal anlage cannot be identified histologically until the 12th day of incubation. At this time, sudanophilic cells containing much smooth endoplasmic reticulum and numerous mitochondria with tubular cristae are located adjacent to the developing mesonephros. Chromaffm cells appear in this region on about the 14th day of embryogenesis. A discrete glandular structure containing measurable quantities of corticosteroids can be identified on the 15th day, and during the next 2 days the tissue becomes encapsulated. Concomitantly, the ACTH-inducible rates of corticosteroid hormone synthesis increase several fold. The corticotropic responsiveness of the developing adrenal steroidogenic tissue increases progressively during the remainder of embryogenesis.This work was supported by grants to James Cronshaw and W.N. Holmes from the University of California Committee on Research and the National Science Foundation (DIR-8820923), Washington, DC, USA     

Proteomic analysis of liver development of lean Pekin duck (Anas platyrhynchos domestica)

The liver plays vital roles in digestion, metabolism and immune defense. To elucidate the molecular mechanism of nutrient metabolism and antioxidation of lean Pekin duck liver from hatching to slaughter, the proteome changes were investigated using 2-DE, MS, quantitative real-time PCR and bioinformatics. A total of 59 differentially expressed proteins were identified. Proteins involved in transportation were highly up-regulated in newborn ducks whereas 37 proteins associated with metabolism, defense and antioxidation were up-regulated in adult ducks. The over-expression of proteins at the last developmental stage presumably occurs to fulfill the needs of multiple functions of the liver. However, the over-expressed proteins related to transportation during the first developmental stage are involved in maintaining the high basal metabolism of newborn ducks. The functional enrichment analysis also confirmed these results. Furthermore, the protein interaction network predicted 28 proteins acting as key nodes for liver development. The validated expression between proteins and genes provides us target genes for future genetic analyses to improve the health and performance of these ducks. These significant advanced proteome data expand our knowledge on the physiology of the duck liver, thereby providing a potentially valuable foundation for molecular breeding to enhance feed efficiency and immunity and for optimizing the feeding strategy.     

Response-contigent prenatal experience of maternal calls in the Peking duck (Anas platyrhynchos)

As the time of hatching approaches, an incubating bird often vocalizes in apparent response to the movements and calls of the embryos beneath. An experiment was designed to see whether Peking duck embryos, exposed to (mallard or chicken) maternal calls presented to them in response to their foot-movements (as indicator of their motor-activity) on the day before hatching, differed in their responsiveness from other embryos exposed to the same calls but not contingent upon their own movements. The results show that response rate was significantly increased to the mallard maternal call, but not to the chiken maternal call, as a function of the contingency.     

Isolation and characterization of 18 microsatellites in the Peking duck (Anas platyrhynchos) and their application in other waterfowl species

We have isolated and characterized 18 microsatellite loci in the Peking duck (Anas platyrhynchos). The average number of alleles per locus was 3.5, ranging from one to six in domestic Peking ducks (n = 40). All of the markers were polymorphic in a sample of five mallards (A. platyrhynchos; two to eight alleles). Seventeen of the 18 markers amplified in Muscovy ducks (Cairina moschata) with 11 being polymorphic in our sample (n = 14). Amplification of the markers in different species comprising the subfamilies Anatinae and Anserinae indicates their potential value for population genetic applications in a wide range of waterfowl species.     

Configuration of the medial and lateral segments of duck (Anas platyrhynchos) salt glands

Salt glands of the domestic duck Anas platyrhynchos differ from those of the herring gull Larus argentatus and other birds. In ducks, each salt gland consists of distinct medial and lateral segments. Centrally located drainage ducts that extend along the entire length of these medial and lateral segments collect hypertonic fluid secreted by an array of lobules. Each lobule is formed by a single mass of branched tubules in which the direction of capillary blood flow is opposite to that of the secreted fluid. This fluid drains from the medial segment through an external duct that opens into the nasal cavity at the base of the vestibular fold. A duct from the lateral segment loops and opens onto the surface of the nasal septum. The structure and function of the secretory cells is reviewed briefly within the context of our study of the configuration of duck nasal salt glands.     

Urocortin-like immunoreactivity in the primary lymphoid organs of the duck (Anas platyrhynchos)

Urocortin (UCN) is a 40 aminoacid peptide which belongs to corticotropin-releasing factor (CRF) family. This family of peptides stimulates the secretion of proopiomelanocortin (POMC)-derived peptides, adrenocorticotropic hormone (ACTH), β-endorphin and melanocyte-stimulating hormone (MSH) in the pituitary gland. In the present study, using Western blotting and immunohistochemistry, the distribution of UCN in the primary lymphoid organs of the duck was investigated at different ages. In the cloacal burse and thymus, Western blot demonstrated the presence of a peptide having a molecular weight compatible with that of the mammalian UCN. In the cloacal burse, immunoreactivity was located in the medullary epithelial cells and in the follicular associated and corticomedullary epithelium. In the thymus, immunoreactivity was located in single epithelial cells. Double labelling immunofluorescence studies showed that UCN immunoreactivity completely colocalised with cytokeratin immunoreactivity in both the thymus and cloacal burse. Statistically significant differences in the percentage of UCN immunoreactivity were observed between different age periods in the cloacal burse. The results suggest that, in birds, urocortin has an important role in regulating the function of the immune system.Key words: cloacal burse, thymus, cytokeratin, medullary reticular epithelial cells, CRFUrocortin (UCN) is a 40-amino acid peptide belonging to the mammalian corticotropin- releasing hormone (CRH) family which was first discovered in the rat midbrain (Vaughan et al., 1995). On the basis of its selective ability to bind CRH-receptor type 2 (CRH-R2), different types of UCN, i.e. UCN1, UCN2 and UCN3, have been identified (Lewis et al., 2001; Reyes et al., 2001). In mammals, UCN has been found in the central nervous (Vaughan et al., 1995), digestive (Muramatsu et al., 2000) and immune systems (Bamberger et al., 1998; Kageyama et al., 1999; Baigent et al., 2000), and in genital organs (Petraglia et al., 1996). UCN has also been found to play a role in regulating some CRH-receptor-mediated effects (Turnbull et al., 1999). While UCN2 and UCN3 selectively bind to CRH-R2, UCN1 binds to both CRH-R1 and CRH-R2 and shows a greater affinity to CRH-R2 than CRH alone (Chalmers et al., 1996). Despite the ability to interact with the same receptors, different functions are attributed to UCN and CRH. CRH is the primary neuroregulator of the vertebrate stress response in so far as it has been shown to be the major hypothalamic releasing factor for pituitary adrenocorticotropic hormone, whereas UCN seems not to be involved in the activation of the hypothalamus- hypophysis-adrenal axis (Turnbull et al., 1999). Conversely, UCN influences the function of the cardiovascular and nervous systems by increasing anxiety, decreasing appetite and influencing behavioral activity (Latchman, 2001). In non-mammalian vertebrates, few data have been reported on the presence and the role of UCN.The molecule, however, may have been conserved during vertebrate evolution, given that it has also been detected in amphibians and birds (Kozicz et al., 2002; Cavani et al., 2003; Boorse et al., 2005; Calle et al., 2005). In amphibians, UCN and CRH receptors have been found in the brain as well as in many other organs and tissues, including the pituitary gland, heart, kidney and alimentary canal (Kozicz et al., 2002; Boorse et al., 2005, 2006); thus suggesting a potential role for diverse actions in tissue maintenance and function. In Xenopus laevis, UCN injected in the third ventricle has been found to suppress food intake (Boorse et al. 2005). Moreover, it has been found to act as a cytoprotective factor in tadpole tail during metamorphosis (Boorse et al. 2006). In birds, UCN-ir has been found in neurons of the pigeon paramedian subgriseal mesencephalon which appear to be part of the brain circuitry involved in sympathetic nervous system-mediated behavioral responses to stress (Cavani et al. 2003; Cunha et al., 2007). Intracerebroventricular administered UCN, moreover, has been reported to decrease food intake in the chicken (Zhang et al., 2001). Up until now, however, no data are available regarding the presence and role of UCN in tissues and organs of birds outside the central nervous system (CNS). Since UCN and its receptors have been reported to be extensively expressed in immune tissues and addressed to play important roles in the regulation of the immune response (Baigent, 2001), the present study has investigated the presence and distribution of UCN in the primary lymphoid organs of the duck by means of Western blotting and immunohistochemistry. In addition, in order to verify if UCN also plays a role in the maturation of bird primary lymphoid organs, UCN expression was evaluated at different age periods.     

Yolk-sac transmission and post-hatching ontogeny of serum immunoglobulins in the duck (Anas platyrhynchos)

1. To investigate the immunoglobulin (Ig) class which is active in yolk-sac transmission of maternal antibodies in ducks, sera from laying ducks, yolks from their eggs, and sera from ducklings 0-87 days of age were examined by immunoelectrophoresis (IE), and Na2SO4-precipitated Igs from these sera and yolks were run in polyacrylamide gel electrophoresis (PAGE) under reducing conditions. 2. In yolk, 7.8S IgG was greatly enriched compared to 5.7S IgG and IgM, and was the only Ig to reach the sera of newly hatched ducklings. 3. The levels of maternally derived 7.8S IgG in duckling sera decreased after 5 days of age, reaching minimum levels at about 14 days of age. 4. Increases in the serum levels of 7.8S IgG, 5.7S IgG and IgM occurred after 20 days of age, reflecting de novo synthesis by the duckling, and the adult serum profile was achieved by 71 days of age. 5. The involvement of 7.8S rather than 5.7S IgG in yolk-sac transmission was probably determined by the additional heavy chain components of this molecule.     

烟酰胺在原代培养的猪前体脂肪细胞增殖分化中的作用

为研究烟酰胺(Nicotinamide,NAM)在原代培养的猪前体脂肪细胞增殖分化中的作用,探讨其作用的分子机制,用不同浓度(0-500μmol/L)的NAM处理猪前体脂肪细胞。MTT和油红O染色及提取法检测结果表明:在不同的作用时间内,与对照组相比,100-500μmol/L的NAM均可以促进猪前体脂肪细胞的增殖分化,随着NAM浓度的增加,其对前体脂肪细胞增殖分化的促进作用逐渐上升,当浓度为300μmol/L时达到高峰,即300μmol/L NAM的促进效果最为显著(P<0.05);随后,400和500μmol/L NAM的促进作用逐渐减弱。RT-PCR法分析结果表明,Sirt1 mRNA表达显著下降(P<0.05),而其靶基因FoxO1和脂肪细胞分化标志基因PPARγ2、C/EBPα mRNA表达量明显升高(P<0.01),aP2和LPL表达也显著增加(P<0.05)。表明NAM是Sirt1的一个有效抑制剂,它可能通过抑制Sirt1的表达来促进猪前体脂肪细胞增殖和分化。