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PubMed2004

Evolution of preproinsulin gene in birds.

The coding region of the preproinsulin gene has been cloned and partly sequenced in a variety of marine and terrestrial birds (28 species). All genes showed the "ancestral" structure with a large intron-2. The size of intron-2 changed considerably during the evolution of birds (2.4-4.2kb). The hydrophobicity of signal peptides was conserved. Bird C-peptides were predicted to be 28 amino acids long, but circulating C-peptides would be only 26 amino acids long, with Passer as a possible exception. Bird C-peptides were found to lack the sequences identified in mammals as responsible for peptide bioactivity and the structure of the central part. In contrast, predicted insulin sequences were highly conserved. Only two types of analog were identified: the hypoactive form (GluA8), present only in Anseriformes and the hyperactive form (His A8), present in all other species. Based on 3'-nucleotide sequence analysis (extending into intron-2), birds appeared to be monophyletic. Five groups were clearly identified: Paleognathae, Galliformes, Anseriformes, Passeriformes, and Charadriiformes. Paleognathae were suggested as the basal group, supporting the traditional view of avian evolution. Subsequent branching identified a gallo-anserae group and a group containing all other Neognathae. Surprisingly, Columba livia (Columbiforme order) clustered with Galliformes. With represented species, Procellariiformes and possibly Ciconiiformes, and Pelicaniformes were suggested as paraphyletic, in agreement with conclusions from some studies based on mitochondrial DNA sequences.

Animals↗
PubMed1982

Variation in arbovirus infection rates in species of birds sampled in a serological survey during an encephalitis epidemic in the Murray Valley of South-eastern Australia, February 1974.

There was extensive and exuberant breeding of waterbirds before and during an epidemic of arboviral encephalitis in the Murray Valley of south eastern Australia in 1974. As estimated by haemagglutination inhibition tests on 432 bird sera collected between 4th and 13th February, 1974, infection with Murray Valley encephalitis virus, Kunjin virus and possibly other flaviviruses was concentrated in species of the Order Ciconiiformes (55% positive) and Pelecaniformes (41%), compared with only 5% in Anseriformes. Although Sindbis virus infections were also highest in these 2 Orders (56% and 46%, respectively), the incidence of antibodies was spread more uniformly through other Orders than with the flaviviruses: e.g. Anseriformes, 33%, Podicipitiformes, 27%. As viruses were recovered virtually only from Culex annulirostris mosquitoes, the different patterns of infection seem unrelated to host preference by mosquito species or behavioural response to mosquito attack, and suggest a specific relationship between MVE/KUN and Ciconiiformes and Pelecaniformes. The highest infection rate was 22/25 in mature rufous night herons (formerly nankeen night herons) Nycticorax calendonicus, and here tolerance to mosquito attack was probably a contributing factor. Assays of sera from 13 horses indicated high infection rates both alphaviruses and flaviviruses.

Alphavirus↗
PubMed2025

Avian Migration-Mediated Transmission and Recombination Driving the Diversity of Gammacoronaviruses and Deltacoronaviruses.

In the wake of pandemics like COVID-19, which have zoonotic origins, the role of wildlife as reservoirs for emerging infectious diseases has garnered heightened attention. Migratory birds, traversing continents, represent a potent but under-researched vector for the spread of infectious diseases, including novel coronaviruses. This study delves into the genetic diversity and transmission dynamics of coronaviruses in migratory birds, presenting pivotal findings. From April 2019 to April 2023, we screened 5,263 migratory bird samples collected from Shanghai, China, identifying 372 coronavirus-positive samples belonging to five avian-related coronavirus subgenera and subsequently obtaining 120 complete genome sequences. To facilitate further research with a global perspective, the study curated all available 19,000 avian-associated coronaviruses and expanded the original 12 species to 16, including three novel coronavirus species identified in our study and one re-classified species from the public domain. The study illuminates the intricate genetic evolution and transmission dynamics of birds-related coronaviruses on a global scale. A notable aspect of our research is the identification of complex recombination patterns within the spike protein across different virus species and subgenera, highlighting migratory birds as a reservoir of coronavirus. Notably, the coronaviruses found in migratory birds, predominantly from the orders Anseriformes, Charadriiformes, and Pelecaniformes, with domestic ducks from Anseriformes playing a key role in bridging the transmission of coronaviruses between migratory and non-migratory birds. These findings reveal the genetic and recombination characteristics of coronaviruses in migratory birds, emphasizing the critical role of ecologically pivotal bird species in coronavirus transmission and genetic diversity shaping.

Animals↗
PubMedDate not supplied

[New species of the Rhinonyssid mites (Gamasina: Rhinonyssidae) from birds of Russia and neighboring countries].

Four new species of the nasal mite family Rhinonyssidae collected in different regions of the former USSR are described: Neonyssus (Otocorinyssus) alaudae sp. n. from Alauda arvensis L. (Alaudidae, Passeriformes) from Turkmenistan; Rhinonyssus clangulae sp. n. from Clangula hyemalis (L.) (Anatidae, Anseriformes) from Yakutia; R. marilae sp. n. from Aythya marilae L. (Anatidae, Anseriformes) from the Russian Far East; Locustellonyssus sibiricus sp. n. from Locustella certhiola (Pall.) (Sylviidae, Passeriformes) from Siberia.

Animals↗
PubMedDate not supplied

[Different receptor specificity of influence viruses from ducks and chickens and its reflection in the composition of sialosides on host cells and mucins].

The ability of influenza viruses from different hosts to bind to the intestinal epithelium of various birds (Anseriformes (Anatidae), Galliformes, Charadriiformes (sandpipers and sea gulls), Ciconiiformes (storks), Podicipediformes (grebes), and Gruiformes was studied. The composition of sialo-containing receptors on the epithelia was examined, by using lectins. Intestinal epitheliocytes of the Anatidae (Anseriformes) family was shown to have a low content of receptors binding both Sambucus nigra agglutinin (SNA) lectin specific to Siaalpha-6Gal, and Maackia amurensis agglutinin (MAA) lection specific to Siaalpha2-2Gal. Nevertheless, these cells well bound duck influenza viruses. The intestinal epithelium of Ciconiiformes, Podicipediformes, and Gruiformes well bound MMA lection, but avian influenza viruses weakly bound the latter. The intestinal cells of Gallinaceae bound both MMA and SNA lectins and avian and human influenza viruses. Thus, the composition of natural sialosides is different in various avian species whereas the receptor specificity of influenza viruses from various hosts reflects these differences. This can be accounted for by the differences in the ability of influenza viruses from different birds to break through the interspecies barrier, infecting mammals and human beings in particular.

Animals↗
PubMedDate not supplied

Prevalence of Campylobacter jejuni in selected domestic and wild birds in Louisiana.

Prevalence of Campylobacter jejuni was determined in a selected population of domestic and free-living birds submitted for necropsy to the Louisiana State Veterinary Medical Diagnostic Laboratory. The 445 cases examined included 13 orders of birds and yielded C. jejuni in 45 cases, representing an isolation rate of 10.1%. Prevalence was highest in Galliformes (25.2%), followed by Anseriformes (12.9%) and Columbiformes (8.3%). Only one isolation was made out of 179 Psittaciformes examined. Penner serotypes 1, 2, 4, and 16 were most commonly identified among the C. jejuni isolates. This study emphasizes the importance of Galliformes as reservoirs of C. jejuni. The commonality of these serotypes with isolates derived from humans suggests the zoonotic potential of Galliformes in relation to human campylobacteriosis. The isolation rate of 12.9% in Anseriformes implicates free-living and migratory waterfowl as carriers of C. jejuni. Results confirm that Psittaciformes represent a low risk of C. jejuni infection in humans.

Animals↗
PubMed1981

Blood parasites of birds in Central Europe. 3. Plasmodium and Haemoproteus.

The present paper is the third in the series on blood parasites of birds in Central Europe. It is devoted to the genera Plasmodium and Haemoproteus. Plasmodium has been found in 11.3% of birds belonging to 54 species, most abundant being in Galliformes and Columbiformes. On the other hand, this parasite seems to be absent in Anseriformes, Falconiformes, Hirundinidae and Sturnidae in Central Europe. Haemoproteus has been encountered in the studied region in 11.8% of birds belonging to 85 species. It is most abundant in Falconiformes, Strigiformes, Hirundinidae, Emberizidae, Fringillidae, Muscicapidae, Paridae and Turdidae, but it has not been encountered in Anseriformes. The paper also discusses the dependence of the incidence of these parasites on migratory ability of their hosts and on the nest ecology of birds. Moreover, an ecological outline is given of the representatives of the genera Plasmodium and Haemoproteus in birds in Central Europe, mainly on the basis of the ecological model of avian malaria after Beaudoin et al. (1971).

Animals↗
PubMed1993

Ultrastructure of ostrich (Struthio camelus) spermatozoa: I. Transmission electron microscopy.

The origin and relationships of the tinamous (Order Tinamiformes), ratites (Order Struthioniformes, Rheiformes, Casuariiformes, Apterygiformes) and birds of the order Galliformes and Anseriformes is the subject of much debate and it has been suggested that the ultrastructural analysis of a wide variety of avian sperm may provide information relevant to this problem. This paper describes the fine structure of ostrich sperm and compares the results with published information for other non-passerine birds. Ostrich sperm display a short, conical acrosome which covers the tapered tip of the long, cylindrical nucleus. A nuclear invagination housing an acrosomal rod extends deep within the karyoplasm. A centriolar complex is situated beneath the head and consists of a short proximal centriole and a long (3.0 microns) distal centriole which extends the complete length of the midpiece. The central cavity of the distal centriole contains a pair of microtubules embedded in a rod of electron-dense material. The midpiece is surrounded by a mitochondrial sheath. Concentrations of fine granular material are present between the mitochondria. The principal-piece of the tail is demarcated from the midpiece by a distinct annulus and characterized by a ribbed fibrous sheath enclosing a typical axoneme. Rudimentary coarse fibres are observed between the fibrous sheath and the doublet microtubules of the axoneme in the proximal region of the principal-piece. The end-piece contains a disorganized collection of axonemal microtubules. Ostrich sperm differ in a number of respects from that of other non-passerine birds (the absence of a typical perforatorium; the presence of a ribbed fibrous sheath; a deep nuclear invagination; the structure and length of the distal centriole) but show a close similarity to sperm of the rhea and crested tinamou, both representatives of primitive avian families. These observations add further support to the theory that the ratites and tinamous constitute a monophyletic group. The evidence presented also reinforces the hypothesis that the ratites were the first group to branch off from the main avian stem, to be followed by the Galliformes & Anseriformes. Although it was impossible to determine whether the sperm of the tinamou are more "primitive" than those of the ostrich or rhea, it is clear that ostrich and rhea sperm are closely allied and distinct from tinamou sperm.

Animals↗
PubMedDate not supplied

Avian paramyxoviruses serotype 3 isolated from captive birds in Israel: clinical signs, pathology, and antigenic characterization.

Thirteen HA agents were isolated in Israel from captive flamingoes (Phoenicopterus ruber), Egyptian geese (Alopochen aegyptiacus) belonging to order Anseriformes, and ibis (Guara rubra) belonging to order Ciconiiformes. The isolation was done from postmortem materials in three cases of severe respiratory disease with high mortality. The isolates were examined serologically and identified as belonging to the serotype 3 of avian paramyxoviruses (APMV-3). The isolates were more close antigenically to the APMV-3b variety (prototype strain--APMV-3/Parakeet/Netherlands/449/75) than to the APMV-3a variety (prototype strain--APMV-3/Turkey/Wisconsin/68). This is the first isolation of APMV-3 from birds belonging to the orders Anseriformes and Ciconiiformes.

Animals↗
PubMed2004

Cryptic species within the Tetratrichomonas gallinarum species complex revealed by molecular polymorphism.

Tetratrichomonas gallinarum is a widespread intestinal parasite of galliform and anseriform birds. The pathogenicity of this species is controversial, presenting an unsettled problem as yet. We analysed the polymorphism and genetic relationship among 29 isolates of T. gallinarum obtained from eight bird species and five T. gallinarum-like isolates from the oral cavity and lower respiratory tract of human patients. Two methods were used for the analyses: RAPD and sequencing of 16S rRNA, 5.8S rRNA, ITS1 and ITS2 genes, both producing consistent and well-supported results. The isolates were divided into five groups, A-E, with eleven subgroups. The distance between groups E, D and the cluster A-B-C considerably exceeded usual intraspecific polymorphism seen in trichomonads. Moreover, the largest subgroup, A2 (containing 18 isolates), was divided into three branches according to the host specificity. All isolates from humans were placed into avian subgroups A2 and B2. We conclude that our isolates represent, at least, three morphospecies or rather complexes of several cryptic species. Since certain species of the T. gallinarum complex can differ in their biological characteristics and some of them can infect humans, the problem of T. gallinarum pathogenicity should be re-examined with regard to specific genetic groups and zoonotic potential of some of these lineages should be considered.

Animals↗
PubMed2006

Identification of a novel bile acid in swans, tree ducks, and geese: 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid.

By HPLC, a taurine-conjugated bile acid with a retention time different from that of taurocholate was found to be present in the bile of the black-necked swan, Cygnus melanocoryphus. The bile acid was isolated and its structure, established by (1)H and (13)C NMR and mass spectrometry, was that of the taurine N-acyl amidate of 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid. The compound was shown to have chromatographic and spectroscopic properties that were identical to those of the taurine conjugate of authentic 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid, previously synthesized by us from ursodeoxycholic acid. By HPLC, the taurine conjugate of 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid was found to be present in 6 of 6 species in the subfamily Dendrocygninae (tree ducks) and in 10 of 13 species in the subfamily Anserinae (swans and geese) but not in other subfamilies in the Anatidae family. It was also not present in species from the other two families of the order Anseriformes. 3alpha,7alpha,15alpha-Trihydroxy-5beta-cholan-24-oic acid is a new primary bile acid that is present in the biliary bile acids of swans, tree ducks, and geese and may be termed 15alpha-hydroxy-chenodeoxycholic acid.

Animals↗
PubMed1998

Posthatching myofiber development in the M. pectoralis of White Pekin Ducks.

BACKGROUND: A posthatching transformation of fast-twitch oxidative-glycolytic (FTO) to fast-twitch glycolytic (FTG) fibers in the breast muscle in domestic chickens and turkeys is well documented. There is, however, no information on the situation in Anseriformes having a M. pectoralis with a mixed fiber composition in adults. Differences in the growth of the different fiber types were reported for some muscles in ducks as well as in other birds. They are examined in the main flight muscle using growth curve analysis, until now mostly applied to the analysis of overall growth. METHODS: Biopsies were taken longitudinally from the M. pectoralis, Pars thoracica, of 40 White Pekin Ducks at 11 different ages from hatching through day 146. The samples were processed for a combination of nicotinamide adenine dinucleotide tetrazolium reductase and myosin adenosine triphosphatase after acid preincubation at pH 4.1. Mean fiber diameter was determined for the different fiber types in relation to age. The Janoschek growth curve was fitted to these values. RESULTS: FTG fibers were first detected at 20 days of age. Thereafter, the fiber composition hardly changed. When distinguishable by enzyme histochemistry, FTG fibers were already larger in diameter than FTO. There were only gradual differences in the growth pattern. FTG fibers, however, showed much higher absolute, percentage, and relative growth rates. The radial growth of myofibers is slow when compared to other one-dimensional measurements. CONCLUSIONS: Fiber transformation seems to take place within a short age period. However, further studies are necessary to discriminate effects resulting from sample depth. FTG fibers are presumably recruited from those FTO fibers that show higher growth rates. Growth curve analysis, more frequently used in gross morphological studies, provides an analytical tool for evaluating growth processes of cells and tissues as well. Fiber size differences are mainly due to a higher growth rate in FTG fibers, whereas the growth patterns show only minor differences.

Adenosine Triphosphatases↗
PubMed2003

Friedrich Sigmund Merkel and his "Merkel cell", morphology, development, and physiology: review and new results.

Merkel nerve endings are mechanoreceptors in the mammalian skin. They consist of large, pale cells with lobulated nuclei forming synapse-like contacts with enlarged terminal endings of myelinated nerve fibers. They were first described by F.S. Merkel in 1875. They are found in the skin and in those parts of the mucosa derived from the ectoderm. In mammals (apart from man), the largest accumulation of Merkel nerve endings is found in whiskers. In all vertebrates, Merkel nerve endings are located in the basal layer of the epidermis, apart from birds, where they are located in the dermis. Cytoskeletal filaments consisting of cytokeratins and osmiophilic granules containing a variety of neuropeptides are found in Merkel cells. In anseriform birds, groups of cells resembling Merkel cells, with discoid nerve terminals between cells, form Grandry corpuscles. There has been controversy over the origin of Merkel cells. Results from chick/quail chimeras show that, in birds, Merkel cells are a subpopulation of cells derived from the neural crest, which thus excludes their development from the epidermis. Most recently, also in mammals, conclusive evidence for a neural crest origin of Merkel cells has been obtained. Merkel cells and nerve terminals form mechanoreceptors. Calcium ions enter Merkel cells in response to mechanical stimuli, a process which triggers the release of calcium from intracellular stores resulting in exocytosis of neurotransmitter or neuromodulator. Recent results suggest that there may be glutamatergic transmission between Merkel cell and nerve terminal, which appears to be essential for the characteristic slowly adapting response of these receptors during maintained mechanical stimuli. Thus, we are convinced that Merkel cells with associated nerve terminals function as mechanoreceptor cells. Cells in the skin with a similar appearance as Merkel cells, but without contact to nerve terminals, are probably part of a diffuse neuroendocrine system and do not function as mechanoreceptors. Probably these cells, rather than those acting as mechanoreceptors, are the origin of a highly malignant skin cancer called Merkel cell carcinoma.

Animals↗
PubMed1993

Estrogen receptors in the avian brain: survey reveals general distribution and forebrain areas unique to songbirds.

Estrogens play an important role in the control and differentiation of species-typical behavior and in endocrine homeostasis of birds, but the distribution and evolution of cells that contain estrogen receptors in the avian brain are poorly understood. This study therefore surveys 26 species in the avian orders Anseriformes (1 species), Galliformes (2), Columbiformes (3), Psittaciformes (1), Apodiformes (2), and Passeriformes (3 suboscines, 14 oscines). Indirect immunocytochemistry with the estrogen receptor (ER) antibody H222Spy revealed a general pattern of ER-antibody-immunoreactive cells (ER-IRC) in all 26 species, with ER-IRC in consistent, well-defined locations in the limbic forebrain, the midbrain striatum, the hippocampus, the hindbrain, and especially in the preoptic area and the tuberal hypothalamus. For some species, the microdistribution of ER-IRC in some of these general areas differed, such as in the hippocampus and the anterior hypothalamus of suboscine species and in the preoptic area of the Japanese quail. Brains of oscine songbirds of both sexes, unlike brains of nonsongbirds, had ER-IRC in three specific structures of the nonlimbic forebrain: in the area surrounding the nucleus robustus archistriatalis; in the rostral forebrain; and, for all individuals, in the caudale neostriatum, including the nucleus hyperstriatalis ventrale, pars caudale (HVc). Among songbird families or subfamilies, adult males of the Estrildinae had much lower numbers of ER-IRC in HVc than did adult males of the Fringillidae, Paridae, Sturnidae, and Ploceinae. Differences occurred, too, among closely related species: the songbird canary (Serinus canaria) had an ER-IRC area in the rostral forebrain that was lacking in all other songbird species, including other cardueline finches. The cells with ER that are found only in the songbird forebrain but not in reptiles, nonpasserine birds, and nonoscine passerine birds very likely coevolved with steroid-dependent differentiation of vocal control areas. The songbird-specific expression of ER in the forebrain could be an example in which taxon-specific behavior is due to taxon specific neurochemical properties of the brain.

Age Factors↗
PubMed2004

Location of the ureteral openings in the cloacas of tinamous, some ratite birds, and crocodilians: a primitive character.

Cloacas of 67 avian species, of both sexes, from various habitats and differing dietary habits, were examined macro- and microscopically to investigate possible variation in the location of the ureteral openings. Differing from most birds studied, in adult male Rhea americana and several tinamous species the ureters were found to open into the coprodeum. In these species the urodeum receives only the vas deferens or oviduct. Similarly, in crocodiles Caiman crocodilus yacare, but not in lizards Tropidurus montanus and snakes Crotalus durissus terrificus, the ureters empty into the coprodeum. This similarity between ancient birds (ratites and tinamous) and crocodiles may indicate a primitive character linking reptiles and birds. This unusual position of the ureteral orifice can represent an adaptation to facilitate urine collection into the coprodeum and large intestine. Another possibility is that this variation in ureter position is a male reproductive strategy to avoid the mixture of urine and semen in the cloaca. There were no evident correlations between the location of the ureteral openings and the birds' habitat, diet, or histology of the coprodeal mucosa. The occurrence of a phallus in eight species of birds was detected, as well as a peculiar vascularization related to the coprodeal epithelium of anseriformes. Together, these data add to the scarce information about the morphophysiology of the avian cloaca, and also contribute to clarify avian phylogenetic linkages.

Animals↗
PubMed1994

Analysis of directional mutation pressure and nucleotide content in mitochondrial cytochrome b genes.

We present a new approach for analyzing directional mutation pressure and nucleotide content in protein-coding genes. Directional mutation pressure, the heterogenicity in the likelihood of different nucleotide substitutions, is used to explain the increasing or decreasing guanine-cytosine content (GC%) in DNA and is represented by microD, in agreement with Sueoka (1962, Proc Natl Acad Sci USA 48:582-592). The new method uses simulation to facilitate identification of significant A+T or G+C pressure as well as the comparison of directional mutation pressure among genes, even when they are translated by different genetic codes. We use the method to analyze the evolution of directional mutation pressure and nucleotide content of mitochondrial cytochrome b genes. Results from a survey of 110 taxa indicate that the cytochrome b genes of most taxa are subjected to significant directional mutation pressure and that the gene is subject to A+T pressure in most cases. Only in the anseriform bird Cairina moschata is the cytochrome b gene subject to significant G+C pressure. The GC% at nonsynonymous codon sites decreases proportionately with increasing A+T pressure, and with a slope less than one, indicating a presence of selective constraints. The cytochrome b genes of insects, nematodes, and eumycotes are subject to extreme A+T pressures (microD = 0.123, 0.224, and 0.130) and, in parallel, the GC% of the nonsynonymous codon sites has decreased from about 0.44 in organisms that are not subjected to A+T or G+C pressure to about 0.332, 0.323, and 0.367, respectively. The distribution of taxa according to the GC% at nonsynonymous codon sites and directional mutation pressure supports the notion that variation in these parameters is a phylogenetic component.

Biological Evolution↗
PubMed1993

Pathways of lysozyme evolution inferred from the sequences of cytochrome b in birds.

A reliable phylogeny relating the major groups of Galliformes was sought in order to shed light on an unusual case of coupled amino acid replacements in the lysozymes c of these birds. The New World quail and the African guinea fowl share a unique trio of amino acids at three internal positions but have been separated phylogenetically by the majority of trees based on morphological characters. Alternative hypotheses based on molecular data have suggested an arrangement that would be more parsimonious with regard to the lysozyme data. The entire mitochondrial cytochrome b gene (1,143 bp) was amplified via the polymerase chain reaction (PCR) and sequenced for nine galliforms and a representative anseriform to provide DNA sequence data for a phylogenetic reconstruction. The mode and tempo of change in these sequences were analyzed to determine the characters most appropriate for phylogenetic reconstruction. Our results place the New World quail outside all other representative game birds except the cracids. Although in conflict with various morphological analyses, this finding is consistent with the results of DNA-DNA hybridization studies. A model to account for the coupled replacements in the lysozymes is presented. Our results also suggest a rapid but ancient radiation among the Galliformes such that the majority of cytochrome b sequence differences among taxa have accumulated on the terminal branches of the reconstructed phylogenetic trees.

Amino Acid Sequence↗
PubMed1989

Primary structure of hemoglobin alpha-chain of Columba livia (gray wild pigeon).

Primary structure of hemoglobin of alpha-chain of Columba livia is presented. The separation of alpha-chain was obtained from globin by ion-exchange chromatography (CMC-52) and reversed-phase HPLC (RP-2 column). Amino acid sequence of intact as well as tryptic digested chain was determined on gas-phase sequencer. Structure is aligned homologously with 21 other species. Among different exchanges, positions alpha 24 (Tyr----Leu), alpha 26 (Ala----Gly), alpha 32 (Met----Leu), alpha 64 (Asp----Glu), alpha 113 (Leu----Phe), and alpha 129 (Leu----Val) are unique to pigeon hemoglobin. The various exchanges in alpha-chain are discussed with reference to evolution and phylogeny. The results show that the order Columbiformes is evolutionarily closer to the order Anseriformes. Since the pigeon is homogeneous, having HbA (alpha A-chain) and lacks alpha D-chain, its phylogenetic placement could be established among birds having single hemoglobin components.

Amino Acid Sequence↗