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Measurement of corticosterone metabolites in chicken droppings.

(1) A non-invasive technique for stress assessment is needed. Therefore, an enzyme immunoassay (EIA) for measurement of glucocorticoid metabolites in chicken droppings was established and validated. (2) Radiolabelled corticosterone was administered intravenously to detect the time course of excreted metabolites. The metabolites were then characterised by chemical and immunological methods to find a suitable antibody. (3) Reversed-phase high-performance liquid chromatography (RP-HPLC) separations of the peak concentration samples revealed that corticosterone was extensively metabolised, mainly to more polar substances. (4) HPLC fractions were tested in several EIAs for glucocorticoid metabolites, where the highest quantities were detected by a newly established cortisone assay, measuring metabolites with a 3,11-dione structure. (5) The biological relevance of this cortisone EIA was confirmed by stimulation of adrenocortical activity by adrenocorticotropic hormone (ACTH). (6) With this newly developed EIA it should be possible to measure adrenocortical activity non-invasively in chickens and other galliformes, thus providing a tool for a variety of research fields, such as poultry production, ethology and behavioural ecology.

Adrenocorticotropic Hormone↗

The mitochondrial genome of Cygnus columbianus, the Whistling Swan.

The nucleotide sequence of the mitochondrial genome of the Whistling Swan, Cygnus columbianus, is reported. Many of the features common to avian mitochondrial genomes are present in C. columbianus and are described here. The gene order is the same as in Gallus gallus. The sequence of this mitochondrial genome allows relationships within the family Anatidae (swans, geese and ducks) to be reconsidered in the light of a large suite of mitochondrial characters. Protein-coding gene sequences of C. columbianus were concatenated to form a supergene, which was analyzed phylogenetically with similar constructs from previously published avian genomes. Relationships within Anatidae and between the Anatidae and the galliform birds were addressed. Three independent phylogenetic methods confirmed traditional classifications and the existence of the Galloanseres clade.

Animals↗

Data set incongruence and correlated character evolution: an example of functional convergence in the hind-limbs of stifftail diving ducks.

The unwitting inclusion of convergent characters in phylogenetic estimates poses a serious problem for efforts to recover phylogeny. Convergence is not inscrutable, however, particularly when one group of characters tracks phylogeny and another set tracks adaptive history. In such cases, convergent characters may be correlated with one or a few functional anatomical units and readily identifiable by using comparative methods. Stifftail ducks (Oxyurinae) offer one such opportunity to study correlated character evolution and function in the context of phylogenetic reconstruction. Morphological analyses place stifftail ducks as part of a large clade of diving ducks that includes the sea ducks (Mergini), Hymenolaimus, Merganetta, and Tachyeres, and possibly the pochards (Aythyini). Molecular analyses, on the other hand, place stifftails far from other diving ducks and suggest, moreover, that stifftails are polyphyletic. Mitochondrial cytochrome b gene sequences of eight stifftail species traditionally supposed to form a clade were compared with each other and with sequences from 50 other anseriform and galliform species. Stifftail ducks are not the sister group of sea ducks but lie outside the typical ducks (Anatinae). Of the four traditional stifftail genera, monophyly of Oxyura and its sister group relationship with Nomonyx are strongly supported. Heteronetta probably is the sister group of that clade, but support is weak. Biziura is not a true stifftail. Within Oxyura, Old World species (O. australis, O. leucocephala, O. maccoa) appear to form a clade, with New World species (O. jamaicensis, O. vittata) branching basally. Incongruence between molecules and morphology is interpreted to be the result of adaptive specialization and functional convergence in the hind limbs of Biziura and true stifftails. When morphological characters are divided into classes, only hind-limb characters are significantly in conflict with the molecular tree. Likewise, null models of synonymous and nonsynonymous substitution based on patterns of codon-degeneracy and chemical dissimilarity indicate that the nucleotide and amino acid changes postulated by the molecular tree are more plausible than those postulated by the morphological tree. These findings teach general lessons about the utility of highly adaptive characters (in particular those related to foraging ecology) and underscore the problems that convergence can pose for attempts to recover phylogeny. They also demonstrate how the concept of natural data partitions and simple models of evolution (e.g., parsimony, likelihood, neutrality) can be used to test the accuracy of independent phylogenetic estimates and provide arguments in favor of one tree topology over another.

Amino Acid Substitution↗

Multiple and independent cessation of recombination between avian sex chromosomes.

Birds are characterized by female heterogamety; females carry the Z and W sex chromosomes, while males have two copies of the Z chromosome. We suggest here that full differentiation of the Z and W sex chromosomes of birds did not take place until after the split of major contemporary lineages, in the late Cretaceous. The ATP synthase alpha-subunit gene is now present in one copy each on the nonrecombining part of the W chromosome (ATP5A1W) and on the Z chromosome (ATP5A1Z). This gene seems to have evolved on several independent occasions, in different lineages, from a state of free recombination into two sex-specific and nonrecombining variants. ATP5A1W and ATP5A1Z are thus more similar within orders, relative to what W (or Z) are between orders. Moreover, this cessation of recombination apparently took place at different times in different lineages (estimated at 13, 40, and 65 million years ago in Ciconiiformes, Galliformes, and Anseriformes, respectively). We argue that these observations are the result of recent and traceable steps in the process where sex chromosomes gradually cease to recombine and become differentiated. Our data demonstrate that this process, once initiated, may occur independently in parallel in sister lineages.

Amino Acid Sequence↗

Characterization and chromosomal distribution of a novel satellite DNA sequence of Japanese quail (Coturnix coturnix japonica).

A novel satellite DNA sequence of Japanese quail (Coturnix coturnix japonica) was isolated from genomic DNA digested with restriction endonuclease, Bg/II. Sequence analysis of three different-size clones revealed the presence of a tandem array of a GC-rich 41 bp repeated element. This sequence was localized by fluorescence in situ hybridization (FISH) primarily to microchromosomes of Japanese quail (2n = 78); approximately 50 of the 66 microchromosomes showed positive signals, although hybridization signals were also detected on chromosomes 4 and W. This satellite DNA did not cross-hybridize with genomic DNA of chicken (Gallus gallus) and Chinese painted quail (Excalfactoria chinensis) under moderately stringent conditions, suggesting that this class of repetitive DNA sequences was species specific and fairly divergent in Galliformes species.

Animals↗

Gene conversion drives the evolution of HINTW, an ampliconic gene on the female-specific avian W chromosome.

The HINTW gene on the female-specific W chromosome of chicken and other birds is amplified and present in numerous copies. Moreover, as HINTW is distinctly different from its homolog on the Z chromosome (HINTZ), is a candidate gene in avian sex determination, and evolves rapidly under positive selection, it shows several common features to ampliconic and testis-specific genes on the mammalian Y chromosome. A phylogenetic analysis within galliform birds (chicken, turkey, quail, and pheasant) shows that individual HINTW copies within each species are more similar to each other than to gene copies of related species. Such convergent evolution is most easily explained by recurrent events of gene conversion, the rate of which we estimated at 10(-6)-10(-5) per site and generation. A significantly higher GC content of HINTW than of other W-linked genes is consistent with biased gene conversion increasing the fixation probability of mutations involving G and C nucleotides. Furthermore, and as a likely consequence, the neutral substitution rate is almost twice as high in HINTW as in other W-linked genes. The region on W encompassing the HINTW gene cluster is not covered in the initial assembly of the chicken genome, but analysis of raw sequence reads indicates that gene copy number is significantly higher than a previous estimate of 40. While sexual selection is one of several factors that potentially affect the evolution of ampliconic, male-specific genes on the mammalian Y chromosome, data from HINTW provide evidence that gene amplification followed by gene conversion can evolve in female-specific chromosomes in the absence of sexual selection. The presence of multiple and highly similar copies of HINTW may be related to protein function, but, more generally, amplification and conversion offers a means to the avoidance of accumulation of deleterious mutations in nonrecombining chromosomes.

Animals↗

Calibration of avian molecular clocks.

Molecular clocks can be calibrated using fossils within the group under study (internal calibration) or outside of the group (external calibration). Both types of calibration have their advantages and disadvantages. An internal calibration may reduce extrapolation error but may not be from the best fossil record, raising the issue of nonindependence. An external calibration may be more independent but also may have a greater extrapolation error. Here, we used the advantages of both methods by applying a sequential calibration to avian molecular clocks. We estimated a basal divergence within birds, the split between fowl (Galliformes) and ducks (Anseriformes), to be 89.8 +/- 6.97 MYA using an external calibration and 12 rate-constant nuclear genes. In turn, this time estimate was used as an internal calibration for three species-rich avian molecular data sets: mtDNA, DNA-DNA hybridization, and transferrin immunological distances. The resulting time estimates indicate that many major clades of modern birds had their origins within the Cretaceous. This supports earlier studies that identified large gaps in the avian fossil record and suggests that modern birds may have coexisted with other avian lineages for an extended period during the Cretaceous. The new time estimates are concordant with a continental breakup model for the origin of ratites.

Animals↗

Reinterpreting the origins of flamingo lice: cospeciation or host-switching?

The similarity of the louse faunas of flamingos and ducks has been used as evidence that these two groups of birds are closely related. However, the realization that ducks actually are more closely related to Galliformes caused many workers to reinterpret this similarity in parasite faunas as host switching from ducks to flamingos. Recent unexpected phylogenetic results on the relationships of waterbirds and their lice call for a reinterpretation of the origins of the lice of the enigmatic flamingos. Here, we bring together new evidence on the phylogenetic relationships of flamingos and their lice and show that the lice of flamingos and grebes are closely related because their hosts share a common ancestor (cospeciation). We also demonstrate that the similarity of the louse faunas of flamingos and ducks is a result of host switching from flamingos to ducks, rather than from ducks to flamingos.

Animals↗

Resolution of the phylogenetic position of the Congo peafowl, Afropavo congensis: a biogeographic and evolutionary enigma.

Afropavo congensis, the Congo peafowl, has long fascinated ornithologists because of its uncertain phylogenetic position and unusual geographic distribution. While some researchers have placed Afropavo as a sister taxon to the true peafowl, Pavo species, others have suggested relationships with the guineafowl or an Old World partridge, Francolinus. These divergent opinions are due, at least in part, to (i) the unique morphological characteristics, lack of elaborate ornamentation, and monogamous mating system in Afropavo which differentiates it from Pavo; and (ii) the restricted distribution of Afropavo in Zaire, which is far removed from the Asian distribution of all other pheasant species. We obtained complete cytochrome b and partial D-loop sequences of Afropavo and compared them to Pavo, guineafowl, Francolinus and other galliform taxa. Our results strongly support a close relationship between Afropavo and Pavo, and we were able to reject alternative phylogenetic hypotheses. Molecular clock estimates of the divergence time place the separation of Afropavo and Pavo in the late Miocene. We also discuss other relatives of Afropavo and Pavo and use this information to propose hypotheses regarding the evolution of ornamentation and sexual dimorphism within this group of pheasants.

Animals↗

Avian evolution, Gondwana biogeography and the Cretaceous-Tertiary mass extinction event.

The fossil record has been used to support the origin and radiation of modern birds (Neornithes) in Laurasia after the Cretaceous-Tertiary mass extinction event, whereas molecular clocks have suggested a Cretaceous origin for most avian orders. These alternative views of neornithine evolution are examined using an independent set of evidence, namely phylogenetic relationships and historical biogeography. Pylogenetic relationships of basal lineages of neornithines, including ratite birds and their allies (Palaleocognathae), galliforms and anseriforms (Galloanserae), as well as lineages of the more advanced Neoves (Gruiformes, (Capimulgiformes, Passeriformes and others) demonstrate pervasive trans-Antarctic distribution patterns. The temporal history of the neornithines can be inferred from fossil taxa and the ages of vicariance events, and along with their biogeographical patterns, leads to the conclusion that neornithines arose in Gondwana prior to the Cretaceous Tertiary extinction event.

Animals↗

Rising burden of immature sheep ticks (Ixodes ricinus) on red grouse (Lagopus lagopus scoticus) chicks in the Scottish uplands.

The sheep tick Ixodes ricinus (L.) (Acari: Ixodidae) is an ectoparasite of major economic and pathogenic importance in Scotland. Its distribution in the Scottish uplands is assumed to be governed by the abundance and distribution of its definitive hosts (deer and sheep) and climatic variables such as temperature and rainfall. As the numbers of its major host in Scotland, red deer, have increased dramatically and climatic conditions have become more favourable, the level of parasitism could have been expected to rise. We use data gathered from tick counts on over 4000 red grouse chicks Lagopus lagopus scoticus Latham (Galliformes: Tetraonidae) in various experiments over the past 19 years to ascertain whether the intensity and prevalence of parasitism has been increasing. From 1985 to 2003 the average tick burden of a parasitized red grouse chick has grown from 2.60 +/- 1.12 ticks per chick to 12.71 +/- 1.44. Over this period the percentage of chicks of a given brood parasitized has also increased from 4 +/- 2% to 92 +/- 3%. The possible implications of this increase in parasitism for red grouse production are discussed.

Animals↗

Identification and characterization of a functional, alternatively spliced Toll-like receptor 7 (TLR7) and genomic disruption of TLR8 in chickens.

Based upon the recognition of antiviral compounds and single stranded viral RNA the Toll-like receptors TLR7 and TLR8 are suggested to play a significant role in initiating antiviral immune responses. Here we report the molecular characterization of the chicken TLR7/8 loci which revealed an intact TLR7 gene and fragments of a TLR8-like gene with a 6-kilobase insertion containing chicken repeat 1 (CR1) retroviral-like insertion elements. The chicken TLR7 gene encodes a 1047-amino-acid protein with 62% identity to human TLR7 and a conserved pattern of predicted leucine-rich repeats. Highest levels of chicken TLR7 mRNA were detected in immune-related tissues and cells, especially the spleen, caecal, tonsil and splenic B cells. Alternative spliced forms of TLR7 mRNA were identified in chicken, mouse and human and expressed in similar tissues and cell types to the major form of chicken TLR7. The chicken TLR7+ HD11 cell line and fresh splenocytes produced elevated levels of interleukin-1beta (IL-1beta) mRNA after exposure to the agonists R848 and loxoribine. Interestingly, none of the TLR7 agonists stimulated increased type I interferon (IFN) mRNA whereas poly(I:C) (a TLR3 agonist) up-regulated both chicken IFN-alpha and chicken IFN-beta mRNA. In contrast, TLR7 agonists, particularly R848 and poly(U) stimulated up-regulation of chicken IL-1beta, and chicken IL-8 mRNAs more effectively than poly(I:C). Stimulation of chicken TLR7 with R848 was chloroquine sensitive, suggesting signalling within an endosomal compartment, as for mammalian TLR7. The deletion of TLR8 in galliforms, accompanied with the differential response after exposure to TLR7 agonists, offers insight into the evolution of vertebrate TLR function.

Amino Acid Sequence↗

Plasmodium durae Herman from the introduced common peafowl in northern Nigeria.

Plasmodium (Giovannolaia) durae Herman was originally described from Kenya, the type host being the common turkey, Meleagris gallopavo Linnaeus. There are no field records of this association outside of Africa, where the parasite, herein reported from another introduced and domesticated bird (the common peafowl, Pavo cristatus Linnaeus), was recently listed from 2 native Phasianidae of the genus Francolinus. The justification for the present identification is submitted against background data concerning malaria parasites from turkeys and other Galliformes in Africa and elsewhere, and restraint is urged in describing yet more "new species" of avian Plasmodium belonging to morphologically close taxa within Novyella and Giovannolaia. A near relative of P. durae, Plasmodium dissanaikei de Jong, is transferred from the former subgenus to the latter one.

Animals↗

Eimeria tahamensis N. sp. (Apicomplexa: Eimeriidae) from the Arabian quail (Coturnix delegorguei arabica).

Eimeria tahamensis n. sp. is described from the harlequin quail (Coturnix delegorguei arabica) from Tahama, Saudi Arabia. The sporulated oocysts of E. tahamensis n. sp. are ellipsoid, 36.5-42 X 25.5-29 (41.2 +/- 1.34 X 28.4 +/- 0.81) micron, with a thick two-layered wall and one polar granule but without a micropyle or an oocyst residuum. The sporocysts are ovoid, 14-16 X 9-11.5 (15.3 +/- 0.7 X 10.8 +/- 0.64) micron, with a knob-like Stieda body and sporocyst residuum, but without a substiedal body. The sporozoites are often located transversely at the two ends of the sporocysts. The host bird belongs to the order Galliformes.

Animals↗

Cryptosporidium meleagridis in an Indian ring-necked parrot (Psittacula krameri).

OBJECTIVE: To perform a morphological and genetic characterisation of a Cryptosporidium infection in an Indian ring-necked parrot (Psittacula krameri) and to compare this with C meleagridis from a turkey. DESIGN: Tissue and intestinal sections from an Indian ring-necked parrot were examined microscopically for Cryptosporidium. The organism was also purified from the crop and intestine, the DNA extracted and a portion of the 18S rDNA gene amplified, sequenced and compared with sequence and biological information obtained for C meleagridis from a turkey as well as sequence information for other species of Cryptosporidium. RESULTS: Morphological examination of tissue sections from an Indian ring-necked parrot revealed large numbers of Cryptosporidium oocysts attached to the apical border of enterocytes lining the intestinal tract. Purified Cryptosporidium oocysts measured about 5.1 x 4.5 microns, which conformed morphologically to C meleagridis. The sequence obtained from this isolate was identical to sequence information obtained from a C meleagridis isolate from a turkey. CONCLUSION: Cryptosporidium meleagridis was detected in an Indian ring-necked parrot using morphological and molecular methods. This is the first time that this species of Cryptosporidium has been reported in a non-galliform host and extends the known host range of C meleagridis.

Animals↗

Wing-assisted incline running and the evolution of flight.

Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient wings in feathered theropod dinosaurs and offers a previously unstudied explanation for the evolution of avian flight.

Acceleration↗

Slow mortality rate accelerations during aging in some animals approximate that of humans.

A general measure of the rate of senescence is the acceleration of mortality rate, represented here by the time required for the mortality rate to double (MRD). Rhesus monkeys have an MRD close to that of humans, about 8 years; their shorter life-span results mainly from higher mortality at all ages. In contrast, some groups with short life-spans (rodents and galliform birds) have shorter MRDs and faster senescence. On the basis of the Gompertz mortality rate model, one may estimate the MRD from the maximum life-span (tmax) and the overall population mortality rate. Such calculations show that certain birds have MRDs that are as long as that of humans. These results show that high overall mortality rates or small body sizes do not preclude slow rates of senescence.

Adolescent↗

Serotyping of European isolates of Chlamydia psittaci from poultry and other birds.

A panel of five serovar-specific monoclonal antibodies which distinguish the five known avian serovars of Chlamydia psittaci was used to serotype 45 European avian Chlamydia psittaci isolates. Chlamydial antigen was grown in Buffalo green monkey (BGM) cells or in embryonated chicken eggs and was then inoculated into BGM cells. Serotyping was performed in an indirect immunofluorescence test. The 45 European isolates included 22 isolates from the order Psittaciformes, 9 isolates from the order Columbiformes, 6 isolates from the order Galliformes, 5 isolates from the order Passeriformes, and 3 isolates from the order Anseriformes. All of these were successfully serotyped. No additional serovars were found. One isolate from a duck and two isolates from psittacine birds gave positive immunofluorescences with two monoclonal antibodies considered to be specific for two different serovars. These three isolates were cloned by an agar overlay method. Serotyping of the clones demonstrated that the duck and one psittacine bird each were infected with two different serovars. After cloning, one isolate from a psittacine bird reacted only with serovar A. From these results it was concluded that this serotyping system allows the classification of all isolates tested so far. The results show that similar serovars are prevalent in avian species in Europe and the United States. The results also indicate that birds from a certain order are more susceptible to a distinct serovar. The use of a panel of serovar-specific monoclonal antibodies in the immunofluorescence test provides a reliable method for serotyping avian isolates. Monoclonal antibodies to new avian isolate serovars can easily be added to the panel, which makes the system useful for epidemiological studies.

Animals↗