|884 entries were found! |
| Photochem Photobiol Sci volume issue 721-728|
Authors: Hammer-Wilson MJ, Cao D, Kimel S, Berns MW.
Org: Beckman Laser Institute, University of California, Irvine, CA 92612, USA. email@example.com
Title:Photodynamic parameters in the chick chorioallantoic membrane (CAM) bioassay for photosensitizers administered intraperitoneally (IP) into the chick embryo.
The chick chorioallantoic membrane (CAM) assay was used to determine the photodynamic response (PDR) of blood vessels to Photofrin, 5-aminolevulinic acid (ALA), benzoporphyrin derivative monoacid ring A (BPD-MA) and lutetium texaphyrin (Lutex). The photosensitizers were administered systemically via intraperitoneal injection into the chick embryo. Forward stepwise regression analysis of the PDR results enabled the individual contributions of seven experimental variables to be ranked: drug dose, light dose, fluence rate, drug uptake time, vessel type (whether arterioles or venules), vessel diameter, and embryo age. The order of importance of the variables, the PDR profile, was determined for each photosensitizer. Relative contributions of the experimental variables from this study to the CAM PDR were compared with those from our previous study on PDR of CAM blood vessels following topical application of the same photosensitizers. PDR profiles were interpreted in terms of biophysical and biochemical characteristics of the individual photosensitizers and the variation in their interactions with the delivery/distribution environment.
PMID: 12665312[PubMed - indexed for MEDLINE]
| Genetika volume issue 1304-1308|
Authors: Semenova SK, Moiseeva IG, Vasil'ev VA, Filenko AL, Nikiforov AA, Sevast'ianova AA, Ryskov AP.
Org: Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia.
Title:[Genetic polymorphism of Russian, European, and Asian chicken breeds as revealed with DNA and protein markers]
The variation in polymorphic DNA (RAPD and minisatellite) and protein markers was compared for nine Russian chicken breeds differing in morphological and productivity types and in origin, three European egg breeds, and three broiler breeds of the Asian origin. Genetic diversity indices were calculated for each breed group and each marker type and were used to construct dendrograms of genetic similarity. In all breed groups, minisatellites and RAPD markers revealed higher genetic diversity as compared with protein markers. With any type of markers, genetic diversity of the Russian and Asian broiler breeds proved to be significantly higher than that of the European egg breeds. The differentiating potentialities of molecular and genetic biochemical markers at the breed level and the origin of the Russian chicken breeds are discussed.
PMID: 12391894[PubMed - indexed for MEDLINE]
| Poult Sci volume issue 1567-1570|
Authors: Jones DR, Fletcher DL, Lyon CE.
Org: USDA-ARS, Russell Research Center, Poultry Processing and Meat Quality Research Unit, Athens, Georgia, USA. firstname.lastname@example.org
Title:Variations in levels of acid phosphatase present in chicken whole leg meat.
Acid phosphatase (ACP) has been identified as a potential biomarker for endpoint temperature determination in further-processed poultry. Multiple analyses of the same sample for ACP have produced consistent results. The degree of variation in ACP levels present in different production lots has not been identified. This study was conducted utilizing a single flock of broilers. Birds were slaughtered on four separate days (replications), and whole leg, without skin, was homogenized. Proximate composition was analyzed for each replication. Water-soluble proteins were extracted from raw meat and assessed for initial ACP levels. Samples of meat were cooked to an internal temperature of 71.1 C. There were differences (P < 0.05) between replications for both moisture and fat content. When dry fat content was analyzed, no significant differences occurred between replicates. Initial ACP levels were different (P < 0.0001) between replicates (500.33 to 348.97 units of activity/kg). Levels of ACP activity after cooking were also different (P < 0.0001) between replicates (17.61 to 10.82 units of activity/kg). Percentage degradation of activity during cooking was similar (96.98 to 95.89%) between replicates. ACP levels were consistently measured within a replicate. Differences between replicates for both initial and cooked levels indicate a threshold level for determination of thermal endpoint would be difficult to establish. ACP may not be a sensitive measure to estimate the degree of doneness of meat samples in which initial ACP concentration is unknown. Identical raw sample required for such a comparison would be difficult for the processing industry to maintain.
PMID: 12412925[PubMed - indexed for MEDLINE]
| Microb Ecol volume issue 286-293|
Authors: van der Wielen PW, Keuzenkamp DA, Lipman LJ, van Knapen F, Biesterveld S.
Org: Centre for Veterinary Public Health and Environmental Protection, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 2, 3508 TD Utrecht, The Netherlands. P.W.J.J van-der.Wielen@biol.rug.nl
Title:Spatial and temporal variation of the intestinal bacterial community in commercially raised broiler chickens during growth.
The objective of this study was to determine whether host, compartment, or environmental specific factors play an important role in the establishment of the intestinal microflora in broiler chickens during growth. This objective was addressed using a 16S rDNA approach. PCR-amplicons from the V6 to V8 regions of the 16S rDNA of intestinal samples were separated by denaturing gradient gel electrophoresis (DGGE). The number of bands in all intestinal compartments increased when broilers grew older, indicating that the dominant bacterial community becomes more complex when chickens age. Each chicken had a unique banding pattern for all locations in the intestinal tract, irrespective of the age of chickens. This suggests that host-related factors affect the establishment of the dominant bacterial community. Banding patterns of intestinal compartments within one chicken were different from each other for broilers older than 4 days, except for both ceca which were highly similar. In 4-day-old broilers, banding patterns from crop, duodenum, and ileum were very similar. We conclude that (unknown) host specific factors play an important role in the development of the intestinal bacterial community in each broiler chicken. Furthermore, compartment-specific factors play an important role in the bacterial development of each intestinal compartment within one chicken.
PMID: 12219265[PubMed - indexed for MEDLINE]
| Mol Microbiol volume issue 381-394|
Authors: Antikainen J, Anton L, Sillanpaa J, Korhonen TK.
Org: Department of Biosciences, University of Helsinki, Helsinki, Finland.
Title:Domains in the S-layer protein CbsA of Lactobacillus crispatus involved in adherence to collagens, laminin and lipoteichoic acids and in self-assembly.
The protein regions in the S-layer protein CbsA of Lactobacillus crispatus JCM 5810, needed for binding to collagens and laminin, anchoring to bacterial cell wall, as well as self-assembly, were mapped by deletion analysis of His-tagged peptides isolated from Escherichia coli and by heterologous expression on Lactobacillus casei. Mature CbsA is 410 amino acids long, and stepwise genetic truncation at both termini revealed that the region 32-271 carries the infor-mation for self-assembly of CbsA into a periodic structure. The lactobacillar S-layer proteins exhibit sequence variation in their assembly domain, but the border regions 30-34 and 269-274 in CbsA are conserved in valine-rich short sequences. Short deletions or substitutions at these regions affected the morphology of His-CbsA polymers, which varied from sheet-like to cylindrical tubular polymers, and further truncation beyond the DNA encoding residues 32 and 271 leads to a non-periodic aggregation. The self-assembly of the truncated peptides, as seen by electron microscopy, was correlated with their behaviour in a cross-linking study. The shorter peptides not forming a regular polymer were observed by the cross-linking study and mass spectrometry to form dimers, trimers and tetramers, whereas the other peptides were cross-linked to large multimers only. Binding of solubilized type I and IV collagens was observed with the His-CbsA peptides 1-274 and 31-287, but not with the smaller peptides regardless of their ability to form regular polymers. Strain JCM 5810 also adheres to immobilized laminin and, in order to analyse the possible laminin binding by CbsA, cbsA and its fragments were expressed on the surface of L. casei. Expression of the CbsA peptides 1-274, 1-287, 28-287 and 31-287 on L. casei conferred adhesiveness to both laminin and collagen immobilized on glass as well as to laminin- and collagen-containing regions in chicken colon and ileum. The C-terminal peptides 251-410 and 288-410 bound to L. crispatus JCM 5810 cells from which the S-layer had been depleted by chemical extraction, whereas no binding was seen with the His-CbsA peptides 1-250 or 1-269 or to cells with an intact S-layer. The His-CbsA peptides 251-410 and 288-410 bound to teichoic acids of several bacterial species. The results show that CbsA is an adhesive complex with an N-terminal assembly domain exhibiting affinity for pericellular tissue components and a cationic C-terminal domain binding to negatively charged cell wall components.
PMID: 12406216[PubMed - indexed for MEDLINE]
| Avian Pathol volume issue 473-483|
Authors: Rodriguez-Chavez IR, Rosenberger JK, Cloud SS.
Org: Department of Animal and Food Sciences, Allen Biotechnology Laboratory, University of Delaware, 601 Sincock Lane, Newark, DE 19717, USA. email@example.com
Title:Characterization of the antigenic, immunogenic, and pathogenic variation of infectious bursal disease virus due to propagation in different host systems (bursa, embryo, and cell culture). II. Antigenicity at the epitope level.
Department of Animal and Food Sciences, Allen Biotechnology Laboratory, University of Delaware, 601 Sincock Lane, Newark, DE 19717, USA. firstname.lastname@example.org
PMID: 12427341[PubMed - indexed for MEDLINE]
| Avian Pathol volume issue 463-471|
Authors: Rodriguez-Chavez IR, Rosenberger JK, Cloud SS.
Org: Department of Animal and Food Sciences, Allen Biotechnology Laboratory, University of Delaware, 601 Sincock Lane, Newark, DE 19717, USA. email@example.com
Title:Characterization of the antigenic, immunogenic, and pathogenic variation of infectious bursal disease virus due to propagation in different host systems (bursa, embryo, and cell culture). I. Antigenicity and immunogenicity.
In vitro and in ovo virus neutralization assays were conducted to assess the role of different host systems in infectious bursal disease virus (IBDV) antigenic and immunogenic variation. Four different strains, two variant (1084 E and GLS) and two standard (Edgar and STC), were propagated separately in the bursa of Fabricius and embryos, and were compared with cell culture-adapted preparations of the homologous strains. Chicken polyclonal antisera were prepared against each IBDV and neutralizing antibody titres were determined. Normalized IBDV antibody concentrations were used in neutralization assays against homologous and heterologous IBDVs in 10-day-old specific pathogen free embryos. Both antigenic and immunogenic changes occurred in IBDVs evaluated, as evidenced by differences in the ability of normalized antibody to neutralize IBDV propagated in different host systems. Antibody induced by bursal-derived IBDV neutralized all isolates equally well, whereas antibody induced by cell culture-derived virus neutralized bursal-derived IBDV much less effectively.
PMID: 12427340[PubMed - indexed for MEDLINE]
| Biophys J volume issue 2280-2291|
Authors: Turnay J, Olmo N, Gasset M, Iloro I, Arrondo JL, Lizarbe MA.
Org: Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid, Spain.
Title:Calcium-dependent conformational rearrangements and protein stability in chicken annexin A5.
The conformational rearrangements that take place after calcium binding in chicken annexin A5 and a mutant lacking residues 3-10 were analyzed, in parallel with human annexin A5, by circular dichroism (CD), infrared spectroscopy (IR), and differential scanning calorimetry. Human and chicken annexins present a slightly different shape in the far-UV CD and IR spectra, but the main secondary-structure features are quite similar (70-80% alpha-helix). However, thermal stability of human annexin is significantly lower than its chicken counterpart (approximately 8 degrees C) and equivalent to the chicken N-terminally truncated form. The N-terminal extension contributes greatly to stabilize the overall annexin A5 structure. Infrared spectroscopy reveals the presence of two populations of alpha-helical structures, the canonical alpha-helices (approximately 1650 cm(-1)) and another, at a lower wavenumber (approximately 1634 cm(-1)), probably arising from helix-helix interactions or solvated alpha-helices. Saturation with calcium induces: alterations in the environment of the unique tryptophan residue of the recombinant proteins, as detected by near-UV CD spectroscopy; more compact tertiary structures that could account for the higher thermal stabilities (8 to 12 degrees C), this effect being higher for human annexin; and an increase in canonical alpha-helix percentage by a rearrangement of nonperiodical structure or 3(10) helices together with a variation in helix-helix interactions, as shown by amide I curve-fitting and 2D-IR.
PMID: 12324445[PubMed - indexed for MEDLINE]
| Vis Neurosci. volume issue 755-766|
Authors: Feldkaemper MP, Schaeffel F.
Org: University Eye Hospital Tuebingen, Section of Neurobiology of the Eye, Calwerstrasse 7/1. 72076 Tuebingen, Germany. firstname.lastname@example.org
Title:Evidence for a potential role of glucagon during eye growth regulation in chicks.
Eye growth and refraction are regulated by visual processing in the retina. Until now, the messengers released by the retina to induce these changes are largely unknown. Previously, it was found that glucagon amacrine cells respond to defocus in the retinal image and even to its sign. The expression of the immediate-early gene product ZENK increased in this cell population in eyes wearing plus lenses and decreased in minus lens-treated chicks. Moreover, it was shown that the amount of retinal glucagon mRNA increased during treatment with positive lenses. Therefore, it seems likely that these cells contribute to the visual regulation of ocular growth and that glucagon may act as a stop signal for eye growth. The purpose of the present study was to accumulate further evidence for a role of glucagon in the visual control of eye growth. Chicks were treated with plus and minus lenses after injection of different amounts of the glucagon antagonist des-His1-Glu1-glucagon-amide or the agonist Lys17,18,Glu21-glucagon, respectively. Refractive development and eye growth were recorded by automated infrared photorefraction and A-scan ultrasound, respectively. The glucagon antagonist inhibited hyperopia development, albeit only in a narrow concentration range, and at most by 50%, but not myopia development. In contrast, the agonist inhibited myopia development in a dose-dependent fashion. At high concentrations, it also prevented hyperopia development. The amount of glucagon peptide in the retinae and choroids of lens-treated chicks and its diurnal variation was measured by using a radio-immunoassay. Retinal glucagon content decreased after minus lens treatment and choroidal glucagon content increased after plus lens treatment. No diurnal variation in the retinal amount of glucagon was detected. In addition, using an optokinetic nystagmus paradigm, the effect of glucagon and the antagonist des-His1-Glu9-glucagon-amide on suprathreshold contrast sensitivity was studied. Glucagon reduced contrast sensitivity (which might be linked to a signal for growth inhibition) whereas the antagonist des-His1-Glu9-glucagon-amide increased contrast sensitivity. The results of the study are in line with the hypothesis that glucagon plays a role in the visual control of eye growth in the chick.
PMID: 12688670[PubMed - indexed for MEDLINE]
| Vision Res volume issue 2747-2756|
Authors: Guggenheim JA, Erichsen JT, Hocking PM, Wright NF, Black R.
Org: Department of Optometry and Vision Sciences, Cardiff University, CF10 3NB, Cardiff, UK. email@example.com
Title:Similar genetic susceptibility to form-deprivation myopia in three strains of chicken.
Myopia development in humans depends on a complex interplay between genetic and environmental factors. Many of those who become myopic when exposed to a myopigenic environment are likely to do so because of a genetic susceptibility, whereas others somehow remain immune. In the most intensively studied model of environmentally induced myopia, form-deprivation myopia in the chick, there is convincing evidence of differential genetic susceptibility to myopia development, both within-strains and between-strains. To date, however, these have involved relatively small differential responses. The aim of this investigation was to examine genetic susceptibility to a highly uniform regimen of form-deprivation in three strains of chick (white leghorn, brown leghorn and broiler) expected to differ greatly in genetic background and in normal eye size, and to gauge the potential for mapping the quantitative trait loci (QTL) underlying this differential susceptibility. Despite striking differences in normal eye size, all three strains studied developed a similar degree of induced myopia. Whilst the degree of induced vitreous chamber elongation differed significantly between-strains, it was concluded that the high within-strain variation in the response to form-deprivation would prevent the effective application of QTL mapping approaches to identify genes conferring this susceptibility. In contrast, the strains used here would be ideal for use in mapping QTL controlling normal ocular component dimensions.
PMID: 12450494[PubMed - indexed for MEDLINE]
| J Clin Microbiol volume issue 4197-4202|
Authors: Huang FF, Haqshenas G, Shivaprasad HL, Guenette DK, Woolcock PR, Larsen CT, Pierson FW, Elvinger F, Toth TE, Meng XJ.
Org: Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0342, USA.
Title:Heterogeneity and seroprevalence of a newly identified avian hepatitis e virus from chickens in the United States.
We recently identified and characterized a novel virus, designated avian hepatitis E virus (avian HEV), from chickens with hepatitis-splenomegaly syndrome (HS syndrome) in the United States. Avian HEV is genetically related to but distinct from human and swine HEVs. To determine the extent of genetic variation and the seroprevalence of avian HEV infection in chicken flocks, we genetically identified and characterized 11 additional avian HEV isolates from chickens with HS syndrome and assessed the prevalence of avian HEV antibodies from a total of 1,276 chickens of different ages and breeds from 76 different flocks in five states (California, Colorado, Connecticut, Virginia, and Wisconsin). An enzyme-linked immunosorbent assay using a truncated recombinant avian HEV ORF2 antigen was developed and used to determine avian HEV seroprevalence. About 71% of chicken flocks and 30% of chickens tested in the study were positive for antibodies to avian HEV. About 17% of chickens younger than 18 weeks were seropositive, whereas about 36% of adult chickens were seropositive. By using a reverse transcription-PCR (RT-PCR) assay, we tested 21 bile samples from chickens with HS syndrome in California, Connecticut, New York, and Wisconsin for the presence of avian HEV RNA. Of the 21 bile samples, 12 were positive for 30- to 35-nm HEV-like virus particles by electron microscopy (EM). A total of 11 of the 12 EM-positive bile samples and 6 of the 9 EM-negative bile samples were positive for avian HEV RNA by RT-PCR. The sequences of a 372-bp region within the helicase gene of 11 avian HEV isolates were determined. Sequence analyses revealed that the 11 field isolates of avian HEV had 78 to 100% nucleotide sequence identities to each other, 79 to 88% identities to the prototype avian HEV, 76 to 80% identities to chicken big liver and spleen disease virus, and 56 to 61% identities to other known strains of human and swine HEV. The data from this study indicated that, like swine and human HEVs, avian HEV isolates are genetically heterogenic and that avian HEV infection is enzoonotic in chicken flocks in the United States.
PMID: 12409397[PubMed - indexed for MEDLINE]
| Poult Sci volume issue 1609-1617|
Authors: Emara MG, Kim H, Zhu J, Lapierre RR, Lakshmanan N, Lillehojt HS.
Org: Department of Animal and Food Sciences, University of Delaware, Newark, 19717, USA. firstname.lastname@example.org
Title:Genetic diversity at the major histocompatibility complex (B) and microsatellite loci in three commercial broiler pure lines.
Genetic diversity at the MHC and non-MHC loci was investigated in three commercial broiler chicken pure lines. The MHC class II and IV loci were evaluated in Southern hybridizations and molecular genotypes based on RFLP were interpreted from pedigreed families. Four MHC class II and eight class IV genotypes were identified in the broiler lines, and their frequencies differed among the lines. Line-specific MHC genotypes were identified. The observed heterozygosities (59 to 67%) suggest that the MHC loci are highly polymorphic in the broiler lines. At least 9% of the genetic variation at the MHC was due to line differences; the remainder reflected individual variations. To characterize non-MHC genes, 41 microsatellite loci located throughout the chicken genome were evaluated in the broiler lines. Genetic variation was also observed at the microsatellite loci for the broiler lines; the number of alleles at a single locus ranged from one to eight, and the average number of alleles per locus was 3.5, 2.8, and 3.1 for each of the lines, respectively. The observed heterozygosities for microsatellite loci ranged between 0 and 89% in the lines. Based on the fixation index (Fst), about 19% of the genetic variation at microsatellite loci was attributed to broiler line differences. Deviations from Hardy-Weinberg equilibrium were detected at both MHC and non-MHC loci. Possible explanations for these deviations include genetic selection by the primary broiler breeder or the presence of null alleles that were not identified by the typing procedures described in this report. This study contributes to our knowledge on the molecular characteristics and genetic structure of a commercial broiler chicken population. Analysis of MHC and non-MHC loci suggests that there is still sufficient genetic diversity in the broiler lines to continue the progress toward improved broiler chicken production.
PMID: 12455584[PubMed - indexed for MEDLINE]
| Poult Sci volume issue 642-648|
Authors: Emara MG, Lapierre RR, Greene GM, Knieriem M, Rosenberger JK, Pollock DL, Sadjadi M, Kim CD, Lillehoj HS.
Org: Department of Animal and Food Sciences, University of Delaware, Newark 19717, USA. email@example.com
Title:Phenotypic variation among three broiler pure lines for Marek's disease, coccidiosis, and antibody response to sheep red blood cells.
To identify candidate genes, chicken lines with the most divergent phenotypes are usually crossed to generate resource mapping populations, for example, either backcrossed or F2 populations. Linkage between the genetic marker and the phenotypic trait locus is then tested in the mapping population. As an initial step in the development of a mapping population from commercial broilers, the goal of the current research was to evaluate the phenotypic variation among three pure lines for antibody response to SRBC and in resistance to two economically important poultry diseases, Marek's disease (MD) and coccidiosis (Eimeria acervulina). Chicks from each line were received and separated into three experimental studies to evaluate each of their responses. In summary, broiler Line 3 had significantly lower antibody responses to SRBC immunizations compared to the other two lines, and nonvaccinated birds from Line 3 were also more susceptible to MD. With coccidiosis, the response was complex, and ranking of the lines was dependent on the age of infection, and whether it was a first or second challenge. With the first challenge, Line 1 was most susceptible at the younger age (Day 30), whereas Line 3 was susceptible at the older age (Day 58). Upon the second challenge, broiler Line 1 remained susceptible at the younger age, but Line 2 was more susceptible at the older age. Line 3 was completely resistant to the second challenge at the older age. Thus, although the broiler lines have been intensively selected for productivity and general livability, this study also demonstrates that the lines differ for immune response and disease resistance. Based on the phenotypic differences between Lines 1 and 3, they were chosen to establish a mapping population for identifying candidate genes that affect MD and coccidiosis in commercial broiler chickens.
PMID: 12033413[PubMed - indexed for MEDLINE]
| Biophys J volume issue 2548-2564|
Authors: Littlefield R, Fowler VM.
Org: Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA. firstname.lastname@example.org
Title:Measurement of thin filament lengths by distributed deconvolution analysis of fluorescence images.
The lengths of the actin (thin) filaments in sarcomeres directly influence the physiological properties of striated muscle. Although electron microscopy techniques provide the highest precision and accuracy for measuring thin filament lengths, significant obstacles limit their widespread use. Here, we describe distributed deconvolution, a fluorescence-based method that determines the location of specific thin filament components such as tropomodulin (Tmod) or probes such as phallacidin (a phalloidin derivative). Using Tmod and phallacidin fluorescence, we were able to determine the thin filament lengths of isolated chicken pectoralis major myofibrils with an accuracy and precision comparable to electron microscopy. Additionally, phallacidin fluorescence intensity at the Z line provided information about the width of Z lines. Furthermore, we detected significant variations in thin filaments lengths among individual myofibrils from chicken posterior latissimus dorsai and embryonic chick cardiac myocytes, suggesting that a ruler molecule (e.g., nebulin) does not strictly determine thin filament lengths in these muscles. This versatile method is applicable to myofibrils in living cells that exhibit significant variation in sarcomere lengths, and only requires a fluorescence microscope and a CCD camera.
PMID: 11964243[PubMed - indexed for MEDLINE]
| Infect Immun volume issue 2472-2479|
Authors: Smith AL, Hesketh P, Archer A, Shirley MW.
Org: Institute for Animal Health, Compton Laboratory, Compton, Newbury, Berks RG20 7NN, United Kingdom. email@example.com
Title:Antigenic diversity in Eimeria maxima and the influence of host genetics and immunization schedule on cross-protective immunity.
Eimeria spp. are a group of highly successful intracellular protozoan parasites that develop within enterocytes. Eimeria maxima from the chicken is characterized by high immunogenicity (a small priming infection gives complete immunity to subsequent homologous challenge) and naturally occurring antigenically variant populations that do not completely cross-protect. In this study we examined the expression of antigenic diversity in E. maxima, as manifested by cross-strain protection in a series of inbred chicken lines. The IAH line of Light Sussex chickens and all lines of inbred White Leghorns were susceptible to primary infections with either of two strains (H and W) of E. maxima and were protected completely against challenge with the homologous strain of parasite. The extent of cross-protection against the heterologous parasite strain varied from 0 to almost 100% depending on host genetics. Interestingly, in one inbred line of chickens (line 15I) the cross-protective phenotype was directional and intensely influenced by the infection history of the host. The basis for the observed variation in cross-protection is not known, but our results suggest that the major histocompatibility complex is not a major genetic component of the phenotype. These results are discussed in relation to the number of protective antigens presented by complex pathogens and the development of immunoprotective responses in hosts of different genetic backgrounds.
PMID: 11953384[PubMed - indexed for MEDLINE]
| Vet Res volume issue 109-125|
Authors: Zekarias B, Ter Huurne AA, Landman WJ, Rebel JM, Pol JM, Gruys E.
Org: ID-Lelystad, Institute for Animal Science and Health, The Netherlands. B.Zekarias@id.wag-ur.nl
Title:Immunological basis of differences in disease resistance in the chicken.
Genetic resistance to diseases is a multigenic trait governed mainly by the immune system and its interactions with many physiologic and environmental factors. In the adaptive immunity, T cell and B cell responses, the specific recognition of antigens and interactions between antigen presenting cells, T cells and B cells are crucial. It occurs through a network of mediator proteins such as the molecules of the major histocompatibility complex (MHC), T cell receptors, immunoglobulins and secreted proteins such as the cytokines and antibodies. The diversity of these proteins that mainly is due to an intrinsic polymorphism of the genes causes phenotypic variation in disease resistance. The well-known linkage of MHC polymorphism and Marek's disease resistance difference represents a classic model revealing immunological factors in resistance differences and diversity of mediator molecules. The molecular bases in any resistance variation to infectious pathogens are vaguely understood. This paper presents a review of the major immune mediators involved in resistance and susceptibility to infectious diseases and their functional mechanisms in the chicken. The genetic interaction of disease resistance with production traits and the environment is mentioned.
PMID: 11944802[PubMed - indexed for MEDLINE]
| J Hered volume issue 107-118|
Authors: Deeb N, Lamont SJ.
Org: Department of Animal Science, Iowa State University, 2255 Kildee Hall, Ames, IA 50011, USA.
Title:Genetic architecture of growth and body composition in unique chicken populations.
A resource population was established by crossing one modern broiler sire from a commercial broiler breeder male line with dams from two unrelated highly inbred lines; F1 birds were intercrossed to produce two F2 populations. A variety of phe notypic measurements related to growth, muscling, internal organs, and skeleton were recorded for the F2 populations and contemporary pure inbred and broiler birds. Based on the means and phenotypic distributions of the F2 populations com pared to their parental lines, the effective number of genes affecting each trait and heterosis were estimated and discussed relative to the known genetic selection history for each trait. The results suggest that a high number of genes with small epistatic effects are involved in determining the phenotype for traits that broilers were traditionally selected for, and a lower number of genes with major effects are involved in determining the phenotype for traits related to fitness. The estimated number of genes and the phenotypic distributions of the different traits suggest that a quantitative trait loci (QTL) search might be more effectively applied for traits with a low number of involved genes and a high phenotypic distribution among the F2 birds than for traits that show a lower phenotypic distribution and a high number of genes.
PMID: 12140270[PubMed - indexed for MEDLINE]
| Am J Physiol Regul Integr Comp Physiol volume issue 917-927|
Authors: Villamor E, Ruijtenbeek K, Pulgar V, De Mey JG, Blanco CE.
Org: Department of Pediatrics, University Hospital Maastricht, Research Institute Growth and Development, University of Maastricht, 6202 AZ Maastricht, The Netherlands. firstname.lastname@example.org
Title:Vascular reactivity in intrapulmonary arteries of chicken embryos during transition to ex ovo life.
The present study aimed to characterize pulmonary vascular reactivity in the chicken embryo from the last stage of prenatal development and throughout the perinatal period. Isolated intrapulmonary arteries from non-internally pipped embryos at 19 days of incubation and from internally and externally pipped embryos at 21 days of incubation were studied. Arterial diameter and contractile responses to KCl, endothelin-1, and U-46619 increased with incubation but were unaffected by external pipping. In contrast, the contractions induced by norepinephrine, phenylephrine, and electric field stimulation decreased with development. No developmental changes were observed in endothelium-dependent [acetylcholine (ACh) and cyclopiazonic acid] or endothelium-independent [sodium nitroprusside (SNP)] relaxation. These relaxations were abolished by the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. Endothelium-dependent relaxation was unaffected by blockade of cyclooxygenase or heme oxygenase but was significantly reduced by nitric oxide (NO) synthase inhibitors. Reduction of O2 concentration from 95 to 5% produced a marked reduction in ACh and SNP-induced relaxations. Chicken embryo pulmonary arteries show a marked endothelium-dependent relaxation that is unaffected by transition to ex ovo life. Endothelium-derived NO seems to be the main mediator responsible for this relaxation.
PMID: 11832415[PubMed - indexed for MEDLINE]
| Poult Sci volume issue 283-292|
Authors: Lipkin E, Fulton J, Cheng H, Yonash N, Soller M.
Org: Department of Genetics, The Hebrew University of Jerusalem, Israel. email@example.com
Title:Quantitative trait locus mapping in chickens by selective DNA pooling with dinucleotide microsatellite markers by using purified DNA and fresh or frozen red blood cells as applied to marker-assisted selection.
Many large, half-sib sire families are an integral component of chicken genetic improvement programs. These family structures include a sufficient number of individuals for mapping quantitative trait loci (QTL) at high statistical power. However, realizing this statistical power through individual or selective genotyping is yet too costly to be feasible under current genotyping methodologies. Genotyping costs can be greatly reduced through selective DNA pooling, involving densitometric estimates of marker allele frequencies in pooled DNA samples. When using dinucleotide microsatellite markers, however, such estimates are often confounded by overlapping "shadow" bands and can be confounded further by differential amplification of alleles. In the present study a shadow correction procedure provided accurate densitometric estimates of allele frequency for dinucleotide microsatellite markers in pools made from chicken purified DNA samples, fresh blood samples, and frozen-thawed blood samples. In a retrospective study, selective DNA pooling with thawed blood samples successfully identified two QTL previously shown by selective genotyping to affect resistance in chickens to Marek's disease. It is proposed that use of selective DNA pooling can provide relatively low-cost mapping and use in marker-assisted selection of QTL that affect production traits in chickens.
PMID: 11902402[PubMed - indexed for MEDLINE]
| Mol Ecol volume issue 1125-1130|
Authors: Freeman-Gallant CR, Johnson EM, Saponara F, Stanger M.
Org: Department of Biology, Skidmore College, Saratoga Springs, New York 12866, USA. firstname.lastname@example.org
Title:Variation at the major histocompatibility complex in Savannah sparrows.
The class I and class II genes of the major histocompatibility complex (Mhc) encode dimeric glycoproteins responsible for eliciting the adaptive immune response of vertebrates. Recent work with birds suggests that the number, size, and arrangement of these genes can differ markedly across species, although the extent of this variation, and its causes and consequences, are poorly understood. We have used a 157-base-pair (bp) portion of the second exon of a class II B gene to probe the Mhc in a free-living population of Savannah sparrows (Passerculus sandwichensis). Segregation analysis of Mhc bands suggests that class II B genes can be found in two independently assorting clusters, as previously described for domestic chickens (Gallus gallus) and ring-necked pheasants (Phasianus colchicus) but unlike gene organization in mammals. The Mhc in Savannah sparrows appears large (with many class II B genes) and variable; we found 42 unique genotypes among 48 adults breeding on Kent Island, New Brunswick, Canada in 1995. Savannah sparrows are long-distance migrants, and these results support recent predictions that migratory birds should show higher levels of Mhc polymorphism and/or a greater number of genes than sedentary species. Savannah sparrows are also socially polygynous with high levels of extra-pair paternity, suggesting that a history of sexual selection might also influence the size and/or structure of the avian Mhc.
PMID: 12030987[PubMed - indexed for MEDLINE]