Allelic isoforms of the chicken and duck histone H1.a

Two isoforms of the erythrocyte histone H1.a were identified in two conservative flocks of Rhode Island Red chickens and six conservative flocks of ducks. The H1.a1 and H1.a2 isoforms formed three phenotypes (a1, a2 and a1a2) and were electrophoretically similar in the two species. The frequency of phenotype and histone H1.a allele occurrence varied within the genetic groups of birds, but the relatively rare allele a ² was only detected in chicken and duck strains with colored feathers. Using mass spectrometry, we established that the difference between the measured masses of the duck H1.a isoforms was 156 Da. Since this value corresponds to the mass of the arginine residue alone or to the combined mass of the valine and glycine residues, we believe that the polymorphism of duck histone H1.a might have originated from sequence variation. A mass difference of 1 Da observed between chicken H1.a isoforms corresponded well to the previously detected Glu/Lys substitution (0.9414 Da) at position 117.     

Linker histone-like proteins in Muscovy duck (Cairina moschata L) erythrocyte chromatin

Linker Histone-Like proteins (LHL1 and LHL2) were identified within a linker histone complement of Muscovy duck erythrocyte chromatin. Polyacrylamide gel electrophoretic patterns of N-bromosuccinimide-cleaved LHL products as well as liquid chromatography-electrospray-ion trap mass spectrometry analyses of trypsin-digested LHL peptides revealed structural similarity of LHL1 to histone H5 and between LHL2 and histone H1 subtypes.Since the LHL proteins were stable in the presence of 2-mercaptoethanol and dithiothreitol that reduce disulfide bonds, it appeared unlikely that this doublet was a thiol-derived product of linker histones. A loss of LHL1, with a concomitant maintenance of LHL2 after treatment with dilute alkali, seems to suggest that they might represent disparate protein conjugates resulting from linker histone modifications through ester linkages.     

Natural allelic variation of duck erythrocyte histone H1b

In our previous work (J. Palyga, Genetic polymorphisms of histone H1. b in duck erythrocytes. Hereditas 114, 85-89, 1991) we reported a genetic polymorphism of duck erythrocyte histone H1.b. Here, we screened H1 preparations in a two-dimensional polyacrylamide gel to refine the distribution of allelic forms of H1.b in fifteen duck populations. We have revealed that the frequency of H1.b allelic variants was significantly different among many conservative and breeding duck groups. While b(1) and b(3) were common in all populations screened, the allele b(2), with a slightly lower apparent molecular weight, was confined mainly to brown-feathered ducks (Khaki Campbell and Orpington) and descendent lines.The C- and N-terminal peptides released upon cleavage with N-bromosuccinimide and Staphylococcus aureus protease V8 from duck allelic histones H1. b2 and H1.b3, respectively, migrated differently in the gel, probably as a result of potential amino acid variation in a C-terminal domain.     

A comparison of the histone H1 complements of avian erythrocytes.

1. Histone H1 from chicken, turkey, duck and goose erythrocytes was resolved into six bands and that from quail into seven bands in an acetic acid-urea polyacrylamide gel. 2. A fast migrating minor subtype H1.e was detected in avian erythrocytes using two-dimensional polyacrylamide gel electrophoresis. 3. Although histone subtype H1.z from quail, turkey and duck was well separated in acid-urea gel, a similar protein in goose was found only in two-dimensional gel. This spot was absent in chicken. 4. Histone H1 spots .c, .c' and .d migrate in two-dimensional gel in a relatively constant manner forming a triangle-shaped pattern that facilitates comparison of H1 subtypes among various avian species.     

Distribution of Allelic Forms of Erythrocyte H1 Histones in Japanese Quail Populations Divergently Selected for Amount of Weight Loss After Transient Starvation

Three polymorphic subtypes of erythrocytehistone H1 (H1.a, H1.b, and H1.z) were analyzed using asodium dodecyl sulfate polyacrylamide gel in quailpopulations divergently selected for a high (line 1) or low (line 2) reduction in body massfollowing temporary food withdrawal. Both H1.b and H1.zhistone alleles were found to be differently distributedin these populations during the selection period. The frequency of b¹ in line 2 wasapproximately 1.9-2.8 times lower than in line 1 andapproached the values in line 1 when the selection wassuspended. Similarly, the frequency of allelez² at locus H1.z increased significantly (about 1.6-2.3 times)in line 2 during selection and returned to the initialvalues when selection was stopped. On the other hand,allele a⁰ at locus H1.a was kept atrelatively low levels (usually below 0.05) in both linesduring selection. At that time its level wasapproximately three to four times lower than in a randommating control population. When selection was suspended, the frequency of a⁰ in line 1increased significantly, approaching the values in thecontrol line, and remained essentially unchanged in line2. Thus, all three polymorphic histone H1 loci in quailresponded through changes in allele frequencies to thebreeding selection, which was directed at the amount ofbody weight loss upon transient starvation. It seemsthat either H1 histone locus could be linked to loci controlling the rate of body weightreduction following starvation or weight loss duringfasting might be influenced by a panel of H1 histonealleles that can contribute to functional differences in avian chromatin.     

Duck hepatitis B virus infection of Muscovy duck hepatocytes and nature of virus resistance in vivo.

To test the hypothesis that in vivo resistance to hepadnavirus infection was due to resistance of host hepatocytes, we isolated hepatocytes from Muscovy ducklings and chickens, birds that have been shown to be resistant to duck hepatitis B virus (DHBV) infection, and attempted to infect them in vitro with virus from congenitally infected Pekin ducks. Chicken hepatocytes were resistant to infection, but we were able to infect approximately 1% of Muscovy duck hepatocytes in culture. Infection requires prolonged incubation with virus at 37 degrees C. Virus spread occurs in the Muscovy cultures, resulting in 5 to 10% DHBV-infected hepatocytes by 3 weeks after infection. The relatively low rate of accumulation of DHBV DNA in infected Muscovy hepatocyte cultures is most likely due to inefficient spread of virus infection; in the absence of virus spread, the rates of DHBV replication in Pekin and Muscovy hepatocyte cultures are similar. 5-Azacytidine treatment can induce susceptibility to DHBV infection in resistant primary Pekin hepatocytes but appears to have no similar effect in Muscovy cultures. The relatively inefficient infection of Muscovy duck hepatocytes that we have described may account for the absence of a detectable viremia in Muscovy ducklings experimentally infected with DHBV.     

Genes for Polymorphic H1 Histones Are Linked in the Japanese Quail Genome

In a previous report (Palyga, J., Biochem.Genet. 29, 431-445, 1991), three subtypes oferythrocyte histone H1 were found to vary in a Japanesequail population. While H1.b and H1.z histones were eachrepresented by two electromorphs differing in apparentmolecular weights, a polymorphism of histone H1.a wasconnected with a lack of this protein in some birds. Asa genetic basis for this variability was demonstrated only in H1.b, here genetic data are providedwhich indicate that both H1.a and H1.z are encoded bytwo codominant alleles at a locus. A linkage analysis offamily data in 13 quail pedigrees has revealed a significant linkage between H1.a and H1.z andbetween H1.b and H1.z ( lod scores about 12 and 5,respectively). Thus, a gene for histone H1.z is locatedbetween H1.a and H1.b in the quail genome.     

A highly conserved sequence in H1 histone genes as an oligonucleotide hybridization probe: Isolation and sequence of a duck H1 gene

A 3.5-kb HindIII fragment of a histone gene cluster was isolated from a recombinant phage out of a duck genomic library. This DNA contains a duck H1 gene and its flanking sequences. The hybridization probe, which was used to screen for the H1 gene, had been designed on the basis of a comparative analysis of available H1 gene and protein data. Most H1 histones contain repeated motifs in their C-terminal domain, and these form part of an octapeptide (ser pro lys lys ala lys lys pro) that is highly conserved in many H1 histone proteins. A comparison of the duck H1 described here with two different published chicken H1 histone sequences reveals conservative amino acid exchanges at 22 (of 217 and 218, respectively) positions. The homology is maintained at the flanking sequences, and includes the putative H1 histone gene-specific signal structures and the established 3' stem and loop structures and the CAAGA box. The duck H1 gene and its flanking sequence have been found in identical arrangements in two recombinant bacteriophages, but minor sequence variations and genomic Southern blotting after HindIII digestion suggest that we have either isolated alleles of this genome segment or that the gene described may occur twice per haploid duck genome.     

Effects of heat stress on antioxidant defense system,inflammatory injury,and heat shock proteins of Muscovy and Pekin ducks: evidence for differential thermal sensitivities

Rising temperatures are severely affecting the mortality, laying performance, and meat quality of duck. Our aim was to investigate the effect of acute heat stress on the expression of heat shock proteins (HSPs: HSP90, 70, 60, 40, and 10) and inflammatory factors (nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)) and antioxidant enzyme activity (superoxide dismutase (SOD), malondialdehybe (MDA), catalase (CAT), total antioxidant capacity (T-AOC)) in livers of ducks and to compare the thermal tolerance of Pekin and Muscovy ducks exposed to acute heat stress. Ducks were exposed to heat at 39 ± 0.5 °C for 1 h and then returned to 20 °C for 1 h followed by a 3-h recovery period. The liver and other tissues were collected from each individual for analysis. The mRNA levels of HSPs (70, 60, and 40) increased in both species, except for HSP10, which was upregulated in Muscovy ducks and had no difference in Pekin ducks after heat stress. Simultaneously, the mRNA level of HSP90 decreased in the stress group in both species. Morphological analysis indicated that heat stress induced tissue injury in both species, and the liver of Pekin ducks was severely damaged. The activities of several antioxidant enzymes increased in Muscovy duck liver, but decreased in Pekin duck. The mRNA levels of inflammatory factors were increased after heat stress in both duck species. These results suggested that heat stress could influence HSPs, inflammatory factors expression, and the activities of antioxidant enzymes. Moreover, the differential response to heat stress indicated that the Muscovy duck has a better thermal tolerance than does the Pekin duck.     

Complete Genomic Sequence of a Reovirus Isolate from Pekin Ducklings in China

The complete genomic sequence of a Pekin duck origin reovirus (DRV) from China was determined. The genome comprises 23,419 bp, with segments ranging from 1,191 bp (S4) to 3,959 bp (L1). Pairwise comparisons and phylogenetic analysis indicate that the Pekin duck origin reovirus is more closely related to the new type of Muscovy duck origin reovirus (N-MDRV) identified recently than to the chicken origin avian orthoreovirus (ARV) and the originally described Muscovy duck origin reovirus (ARV-Md).     

Chromosome-level genome assembly of the Muscovy duck provides insight into fatty liver susceptibility

The Muscovy duck (Cairina moschata) is an economically important poultry species, which is susceptible to fatty liver. Thus, the Muscovy duck may serve as an excellent candidate animal model of non-alcoholic fatty liver disease. However, the mechanisms underlying fatty liver development in this species are poorly understood. In this study, we report a chromosome-level genome assembly of the Muscovy duck, with a contig N50 of 11.8 Mb and scaffold N50 of 83.16 Mb. The susceptibility of Muscovy duck to fatty liver was mainly attributed to weak lipid catabolism capabilities (fatty acid β-oxidation and lipolysis). Furthermore, conserved noncoding elements (CNEs) showing accelerated evolution contributed to fatty liver formation by down-regulating the expression of genes involved in hepatic lipid catabolism. We propose that the susceptibility of Muscovy duck to fatty liver is an evolutionary by-product. In conclusion, this study revealed the potential mechanisms underlying the susceptibility of Muscovy duck to fatty liver.     

Conserved organization of an avian histone gene cluster with inverted duplications of H3 and H4 genes

Summary The organization of histone gene clusters of the duckCairina moschata was studied in the DNA inserts of two recombinant phage that overlap and feature identical histone gene arrangements but differ in sequence details and in the extent of repetition of an AT-rich motif in one of the nontranscribed spacer regions. These few but substantial differences between otherwise nearly identical histone gene groups suggest that we have independently isolated alleles of the same site of the duck genome or that this gene arrangement occurs (with slight variations) more than once per haploid genome. Within the histone gene cluster described, H3 and H4 genes are duplicated (with inverted orientation), whereas one H1 gene is flanked by single H2A and H2B genes. The arrangement of duck histone genes described here is identical to a subsection of the chicken genome but differs from any other published histone gene cluster.     

One novel SNP of growth hormone gene and its associations with growth and carcass traits in ducks

In this study, the growth hormone (GH) gene was studied as a candidate gene for growth and carcass traits of three duck populations (Cherry Valley duck, Muscovy duck and Jingjiang duck). Three pairs of primers were designed to detect single nucleotide polymorphisms of introns 2, 3 and 4 of the GH gene by polymerase chain reaction-restriction fragment length polymorphism and sequencing methods. Only the products amplified from intron 2 displayed polymorphism. The results showed one novel polymorphism: a variation in intron 2 of GH gene (C172T, JN408701 and JN408702). It was associated with some growth and carcass traits in three duck populations including birth weight, 8-week weight, carcass weight, breast muscle weight, leg muscle weight, eviscerated weight, lean meat rate, dressing percentage, etc. And the TT and CT genotypes were associated with superior growth and carcass traits in carcass weight, dressing percentage and percentage of eviscerated weight. Therefore, the variation in intron 2 of GH may be a molecular marker for superior growth and carcass traits in above duck populations.     

Structure of allelic variants of subtype 5 of histone H1 in pea Pisum sativum L

The pea genome contains seven histone H1 genes encoding different subtypes. Previously, the DNA sequence of only one gene, His1, coding for the subtype H1-1, had been identified. We isolated a histone H1 allele from a pea genomic DNA library. Data from the electrophoretic mobility of the pea H1 subtypes and their N-bromosuccinimide cleavage products indicated that the newly isolated gene corresponded to the H1-5 subtype encoded by His5. We confirmed this result by sequencing the gene from three pea lines with H1-5 allelic variants of altered electrophoretic mobility. The allele of the slow H1-5 variant differed from the standard allele by a nucleotide substitution that caused the replacement of the positively charged lysine with asparagine in the DNA-interacting domain of the histone molecule. A temperature-related occurrence had previously been demonstrated for this H1-5 variant in a study on a worldwide collection of pea germplasm. The variant tended to occur at higher frequencies in geographic regions with a cold climate. The fast allelic variant of H1-5 displayed a deletion resulting in the loss of a duplicated pentapeptide in the C-terminal domain.     

利用微卫星标记研究鸭品种的遗传多样性

利用32个微卫星标记研究了5个福建省地方鸭品种（金定鸭、连城白鸭、莆田黑鸭、山麻鸭和番鸭）和2个对照品种（北京鸭和卡基康贝尔鸭）的遗传多样性和种质特性.结果表明：32个微卫星标记在7个鸭品种中检测到371个等位基因,平均每个基因座有11.719个等位基因,平均多态信息含量为0.522,有效等位基因数在5.141～6961,基因杂合度变化范围在0.512～0.700,杂合度较高;基于Nei氏标准遗传距离(D_S)和D_A遗传距离,采用UPGMA方法构建了系统发生树,将金定鸭、莆田黑鸭、连城白鸭、山麻鸭和卡基康贝尔鸭聚为一类,而北京鸭和番鸭各自聚为一类.所得聚类图与种群的真实关系较为符合.     

DNA Methylation Is Linked to Deacetylation of Histone H3, but Not H4, on the Imprinted Genes Snrpn and U2af1-rs1

The relationship between DNA methylation and histone acetylation at the imprinted mouse genes U2af1-rs1 and Snrpn is explored by chromatin immunoprecipitation (ChIP) and resolution of parental alleles using single-strand conformational polymorphisms. The U2af1-rs1 gene lies within a differentially methylated region (DMR), while Snrpn has a 5' DMR (DMR1) with sequences homologous to the imprinting control center of the Prader-Willi/Angelman region. For both DMR1 of Snrpn and the 5' untranslated region (5'-UTR) and 3'-UTR of U2af1-rs1, the methylated and nonexpressed maternal allele was underacetylated, relative to the paternal allele, at all H3 lysines tested (K14, K9, and K18). For H4, underacetylation of the maternal allele was exclusively (U2af1-rs1) or predominantly (Snrpn) at lysine 5. Essentially the same patterns of differential acetylation were found in embryonic stem (ES) cells, embryo fibroblasts, and adult liver from F1 mice and in ES cells from mice that were dipaternal or dimaternal for U2af1-rs1. In contrast, in a region within Snrpn that has biallelic methylation in the cells and tissues analyzed, the paternal (expressed) allele showed relatively increased acetylation of H4 but not of H3. The methyl-CpG-binding-domain (MBD) protein MeCP2 was found, by ChIP, to be associated exclusively with the maternal U2af1-rs1 allele. To ask whether DNA methylation is associated with histone deacetylation, we produced mice with transgene-induced methylation at the paternal allele of U2af1-rs1. In these mice, H3 was underacetylated across both the parental U2af1-rs1 alleles whereas H4 acetylation was unaltered. Collectively, these data are consistent with the hypothesis that CpG methylation leads to deacetylation of histone H3, but not H4, through a process that involves selective binding of MBD proteins.     

Structure of a duck H3 variant histone gene: a H3 subtype with four cysteine residues

A duck recombinant DNA phage library was screened for H3 histone genes, and the sequence of a variant H3 gene, which appears not to be part of a histone gene cluster, has been determined. As derived from the nucleotide sequence, this gene codes for a 135-amino acid (aa) protein (as any other H3) and shows 10 aa substitutions compared with most published H3 structures. Six of these aa changes are based on one nucleotide (nt) substitutions in arginine codons. This results in three new histidines and, in addition to the highly conserved cysteine at position 110, three more cysteines are found in this H3 histone subtype.     

Ontogeny of heart rate responses to exogenous melatonin in Muscovy duck and chicken embryos

One of the major physiological effects of melatonin is coupling the internal clock with different organ functions. Despite the long list of functional responses to melatonin discovered in the past, it has been unclear when responsiveness to melatonin develops during ontogeny. The aim of the present study was therefore to investigate in Muscovy duck and chicken embryos, when they start to exhibit heart rate (HR) changes to exogenous melatonin. HR was recorded continuously in Muscovy duck embryos from day 24 of incubation (D24) and in chicken embryos from D17 until hatching. Every day four doses of 10 microg melatonin were injected into each egg at 30 min intervals. In Muscovy duck embryos HR responses to melatonin were first observed on D25; from D27 all embryos responded. In all cases HR decreased immediately after the injection. HR deviation from baseline values and duration of decreased HR period increased during the experimental period. Chicken embryos showed similar responses as Muscovy ducks from D17 onwards; from D18 the response rate was 100%. On D19 dose-response data revealed a partial responsiveness to exogenous melatonin at doses of 0.1 to 1 ng and full responsiveness from 10 ng to 10 microg. The time of the first occurrence of HR responses to melatonin coincides with published results on the start of periodic pineal melatonin secretion. These data suggest that the output signal of the avian internal clock, periodic plasma melatonin fluctuations, could result in periodic cardiac function already prenatally in these two avian species.