Extensive gross genomic rearrangements between chicken and Old World vultures (Falconiformes: Accipitridae)

The karyotypes of most birds consist of a small number of macrochromosomes and numerous microchromosomes. Intriguingly, most accipitrids which include hawks, eagles, kites, and Old World vultures (Falconiformes) show a sharp contrast to this basic avian karyotype. They exhibit strikingly few microchromosomes and appear to have been drastically restructured during evolution. Chromosome paints specific to the chicken (GGA) macrochromosomes 1-10 were hybridized to metaphase spreads of three species of Old World vultures (Gyps rueppelli, Gyps fulvus, Gypaetus barbatus). Paints of GGA chromosomes 6-10 hybridize only to single chromosomes or large chromosome segments, illustrating the existence of high chromosome homology. In contrast, paints of the large macrochromosomes 1-5 show split hybridization signals on the chromosomes of the accipitrids, disclosing excessive chromosome rearrangements which is in clear contrast to the high degree of chromosome conservation substantiated from comparative chromosome painting in other birds. Furthermore, the GGA chromosome paint hybridization patterns reveal remarkable interchromosomal conservation among the two species of the genus Gyps.     

Identification of the linkage group of the Z sex chromosomes of the sand lizard (Lacerta agilis,Lacertidae) and elucidation of karyotype evolution in lacertid lizards

The sand lizard (Lacerta agilis, Lacertidae) has a chromosome number of 2n?=?38, with 17 pairs of acrocentric chromosomes, one pair of microchromosomes, a large acrocentric Z chromosome, and a micro-W chromosome. To investigate the process of karyotype evolution in L. agilis, we performed chromosome banding and fluorescent in situ hybridization for gene mapping and constructed a cytogenetic map with 86 functional genes. Chromosome banding revealed that the Z chromosome is the fifth largest chromosome. The cytogenetic map revealed homology of the L. agilis Z chromosome with chicken chromosomes 6 and 9. Comparison of the L. agilis cytogenetic map with those of four Toxicofera species with many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) showed highly conserved linkage homology of L. agilis chromosomes (LAG) 1, 2, 3, 4, 5(Z), 7, 8, 9, and 10 with macrochromosomes and/or macrochromosome segments of the four Toxicofera species. Most of the genes located on the microchromosomes of Toxicofera were localized to LAG6, small acrocentric chromosomes (LAG11–18), and a microchromosome (LAG19) in L. agilis. These results suggest that the L. agilis karyotype resulted from frequent fusions of microchromosomes, which occurred in the ancestral karyotype of Toxicofera and led to the disappearance of microchromosomes and the appearance of many small macrochromosomes.     

Cytogenetic analysis of California condor (Gymnogyps californianus) chromosomes: comparison with chicken (Gallus gallus) macrochromosomes

The California condor is the largest flying bird in North America and belongs to a group of New World vultures. Recovering from a near fatal population decline, and currently with only 197 extant individuals, the species remains listed as endangered. Very little genetic information exists for this species, although sexing methods employing chromosome analysis or W-chromosome specific amplification is routinely applied for the management of this monomorphic species. Keeping in mind that genetic conditions like chondrodystrophy have been identified, preliminary steps were undertaken in this study to understand the genome organization of the condor. This included an extensive cytogenetic analysis that provided (i) a chromosome number of 80 (with a likelihood of an extra pair of microchromosomes), and (ii) information on the centromeres, telomeres and nucleolus organizer regions. Further, a comparison between condor and chicken macrochromosomes was obtained by using individual chicken chromosome specific paints 1-9 and Z and W on condor metaphase spreads. Except for chromosomes 4 and Z, each of the chicken (GGA) macrochromosomes painted a single condor (GCA) macrochromosome. GGA4 paint detected complete homology with two condor chromosomes, viz., GCA4 and GCA9 providing additional proof that the latter are ancestral chromosomes in the birds. The chicken Z chromosome showed correspondence with both Z and W in the condor. The homology suggests that the condor sex chromosomes have not completely differentiated during evolution, which is unlike the majority of the non-ratites studied up till now. Overall, the study provides detailed cytogenetic and basic comparative information on condor chromosomes. These findings significantly advance the effort to study the chondrodystrophy that is responsible for over ten percent mortality in the condor.     

Chromosome repatterning in three representative parrots (Psittaciformes) inferred from comparative chromosome painting

Parrots (order: Psittaciformes) are the most common captive birds and have attracted human fascination since ancient times because of their remarkable intelligence and ability to imitate human speech. However, their genome organization, evolution and genomic relation with other birds are poorly understood. Chromosome painting with DNA probes derived from the flow-sorted macrochromosomes (1-10) of chicken (Gallus gallus, GGA) has been used to identify and distinguish the homoeologous chromosomal segments in three species of parrots, i.e., Agapornis roseicollis (peach-faced lovebird); Nymphicus hollandicus (cockatiel) and Melopsittacus undulatus (budgerigar). The ten GGA macrochromosome paints unequivocally recognize 14 to 16 hybridizing regions delineating the conserved chromosomal segments for the respective chicken macrochromosomes in these representative parrot species. The cross-species chromosome painting results show that, unlike in many other avian karyotypes with high homology to chicken chromosomes, dramatic rearrangements of the macrochromosomes have occurred in parrot lineages. Among the larger GGA macrochromosomes (1-5), chromosomes 1 and 4 are conserved on two chromosomes in all three species. However, the hybridization pattern for GGA 4 in A. roseicollis and M. undulatus is in sharp contrast to the most common pattern known from hybridization of chicken macrochromosome 4 in other avian karyotypes. With the exception of A. roseicollis, chicken chromosomes 2, 3 and 5 hybridized either completely or partially to a single chromosome. In contrast, the smaller GGA macrochromosomes 6, 7 and 8 displayed a complex hybridization pattern: two or three of these macrochromosomes were found to be contiguously arranged on a single chromosome in all three parrot species. Overall, the study shows that translocations and fusions in conjunction with intragenomic rearrangements have played a major role in the karyotype evolution of parrots. Our inter-species chromosome painting results unequivocally illustrate the dynamic reshuffling of ancestral chromosomes among the karyotypes of Psittaciformes.     

A phylogenetic study of bird karyotypes

Karyotypes were compared in 48 species, including 6 subspecies, of birds from 12 orders: Casuariiformes, Rheiformes, Sphenisciformes, Pelecaniformes, Ciconiiformes, Anseriformes, Phoenicopteriformes, Gruiformes, Galliformes, Columbiformes, Falconiformes and Strigiformes. — With the exception of the family Accipitridae, all the species studied are characterized by typical bird karyotypes with several pairs of macrochromosomes and a number of microchromosomes, though the boundary between the two is not necessarily sharp. The comparative study of complements revealed that a karyotype with 3 morphologically distinct pairs of chromosomes is frequently encountered in all orders except the Strigiformes. Those 3 pairs, submetacentric nos. 1 and 2, and a subtelocentric or telocentric no. 3, are not only morphologically alike but also have conspicuous homology revealed by the G-banding patterns. Furthermore, G-banding analysis provided evidence for the derivation of the owl karyotype from a typical bird karyotype.—The above cytogenetic features led to the assumption that the 3 pairs of marker chromosomes had been incorporated into an ancestral bird karyotype. It seems probable that those chromosomes have been transmitted without much structural changes from a common ancestor of birds and turtles, since the presence of the same marker chromosomes in the fresh water turtle Geoclemys reevesii is ascertained by G-banding patterns. — A profile of a primitive bird karyotype emerged through the present findings. Hence, it has become possible to elucidate mechanisms involved in certain structural changes of macrochromosomes observed in birds. It was concluded that a major role had been played by centric fission as well as fusion, translocation, and pericentric inversion.     

Karyotypic characterization of <Emphasis Type="Italic">Trachemys dorbigni</Emphasis> (Testudines: Emydidae) and <Emphasis Type="Italic">Chelonoidis (Geochelone) donosobarrosi</Emphasis> (Testudines: Testudinidae), two species of Cryptodiran turtles from Argentina

We describe for the first time the karyotypes of two species of Cryptodiran turtles from Argentina, namely, Trachemys dorbigni (Emydidae) and Chelonoidis (Geochelone) donosobarrosi (Testudinidae). The karyotype of T. dorbigni (2n = 50) consists of 13 pairs of macrochromosomes and 12 pairs of microchromosomes, whereas the karyotype of C. donosobarrosi (2n = 52) consists of 11 pairs of macrochromosomes and 15 pairs of microchromosomes. Fluorescence in situ hybridization (FISH) with a (TTAGGG)n telomeric probe showed that the chromosomes of these species have four telomeric signals, two at each end, indicating that none of the chromosomes of T. dorbigni and C. donosobarrosi are telocentric. The fact that no interstitial telomeric signals were observed after FISH, suggests that interstitial telomeric sequences did not have a major role in the chromosomal evolution of these species. Additional data will be needed to elucidate if interstitial telomeric sequences have a major role in the karyotypic evolution of Testudines.     

Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis,Gekkonidae): The Process of Microchromosome Disappearance in Gekkota

The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.     

The karyotype of the osprey,Pandion haliaetus (Aves: Falconiformes)

The karyotype of the osprey consists of 74 chromosomes. There are no large macrochromosomes and no typical microchromosomes. Autosome No. 2 has a prominent secondary constriction in the long arm. The Z chromosome is similar in size and shape to the largest autosome, the W is a small metacentric. Among the Falconiformes, the osprey karyotype mainly resembles the karyotypes of some accipitrid species. However, certain characteristic features of the karyotype, a unique secondary constriction chromosome and absence of microchromosomes, speak in favour of maintaining the osprey in a family of its own, Pandionidae.     

The karyotype of Lacerta horváthi (Reptilia,Sauria, Lacertidae)

The chromosomes of Lacerta horváthi have been studied by means of conventional, C-banding, and silver-NOR techniques. The karyotype of this species, characterized by 36 acrocentric macrochromosomes, lacks the typical pair of microchromosomes shared by all other lacertid lizards. It is hypothesized that the microchromosomes could have been translocated to the large elements of the karyotype. The occurrence of such a rearrangement in the chromosome complement of L. horváthi underlines its isolation from the other species of the subgenus Archaeolacerta. The C-banding analysis evidences the existence of a female sex heteromorphism in which the W-chromosome has the same shape and size of the Z, but differs from it in being completely heterochromatic. The nucleolar organizer regions (NORs) are located on a pair of medium size chromosomes in subtelomeric position, where the standard Giemsa-staining reveals secondary constrictions.     

A comparative cytogenetic study of chromosome homology between chicken and Japanese quail

In order to construct a chicken (Gallus gallus) cytogenetic map, we isolated 134 genomic DNA clones as new cytogenetic markers from a chicken cosmid DNA library, and mapped these clones to chicken chromosomes by fluorescence in situ hybridization. Forty-five and 89 out of 134 clones were localized to macrochromosomes and microchromosomes, respectively. The 45 clones, which localized to chicken macrochromosomes (Chromosomes 1-8 and the Z chromosome) were used for comparative mapping of Japanese quail (Coturnix japonica). The chromosome locations of the DNA clones and their gene orders in Japanese quail were quite similar to those of chicken, while Japanese quail differed from chicken in chromosomes 1, 2, 4 and 8. We specified the breakpoints of pericentric inversions in chromosomes 1 and 2 by adding mapping data of 13 functional genes using chicken cDNA clones. The presence of a pericentric inversion was also confirmed in chromosome 8. We speculate that more than two rearrangements are contained in the centromeric region of chromosome 4. All 30 clones that mapped to chicken microchromosomes also localized to Japanese quail microchromosomes, suggesting that chromosome homology is highly conserved between chicken and Japanese quail and that few chromosome rearrangements occurred in the evolution of the two species.     

The somatic chromosome complements of 16 species of falconiformes (Aves) and the karyological relationships of the order

Using short term leucocyte culture techniques, the somatic chromosome complements of 16 species of diurnal birds of prey, belonging to four different families of the order Falconiformes were studied. The karyotypes are described and illustrated, and of some species idiograms are presented. In accordance with the family classification, four karyologically different groups can be distinguished in the Falconiformes: (1) Cathartidae, with karyotypes which show only 7 pairs of biarmed macrochromosomes and a considerable number of small acrocentrics and microchromosomes (the diploid numbers are approximately 80). This is the only group in which really large macrochromosomes are found (over 10% TCL); (2) Falconidae, the karyotypes of which include only a single pair of biarmed macrochromosomes, all other elements being acrocentrics of medium to small size or microchromosomes (diploid numbers of approximately 84 and 52); (3) the secretary bird (Sagittariidae), with 36 biarmed macrochromosomes and 44 small acrocentrics and microchromosomes (2n=80 approximately); (4) Accipitridae, the representatives of which never possess more than about 8 real microchromosomes, while their karyotypes show varying numbers of biarmed and acrocentric macrochromosomes of small to medium size (diploid numbers range from 78 to 60).The possible karyological relationships within each of these groups are briefly discussed, while a more extensive discussion is dedicated to the possible relationships between these groups, and those between them and other avian taxa.The variation in karyotypic structures found in the Falconiformes is much wider than that in other avian groups. However, it remains an unanswered question whether this karyological heterogenelty points to a polyphyletic origin of the diurnal birds of prey. Especially the chromosome complements of the Accipitridae are most uncommon among birds, because of their extremely low numbers of real microchromosomes. However, of all the Falconiformes only the karyotypes of the Cathartidae have clear counterparts outside the order, since nearly identical complements were found in representatives of the Phoenicopteriformes and Gruiformes.The present work was partially carried out at the Institute of Genetics and the Center for Clinical Cytogenetics (both in Utrecht).     

Chromosome rearrangements between chicken and guinea fowl defined by comparative chromosome painting and FISH mapping of DNA clones

Chromosome homology between chicken (Gallus gallus) and guinea fowl (Numida meleagris) was investigated by comparative chromosome painting with chicken whole chromosome paints for chromosomes 1-9 and Z and by comparative mapping of 38 macrochromosome-specific (chromosomes 1-8 and Z) and 30 microchromosome-specific chicken cosmid DNA clones. The comparative chromosome analysis revealed that the homology of macrochromosomes is highly conserved between the two species except for two inter-chromosomal rearrangements. Guinea fowl chromosome 4 represented the centric fusion of chicken chromosome 9 with the q arm of chicken chromosome 4. Guinea fowl chromosome 5 resulted from the fusion of chicken chromosomes 6 and 7. A pericentric inversion was found in guinea fowl chromosome 7, which corresponded to chicken chromosome 8. All the chicken microchromosome-specific DNA clones were also localized to microchromosomes of guinea fowl except for several clones localized to the short arm of chromosome 4. These results suggest that the cytogenetic genome organization is highly conserved between chicken and guinea fowl.     

Arthropods in the nests of lesser spotted eagle (Aquila pomarina)

In 2001–2007, altogether 57 nests of lesser spotted eagle were collected in the Orava region in northwestern Slovakia and four groups of arthropods were extracted from them. Richest in number of species and individuals were mites (23 species, 17,500 ind.), followed by beetles (12 species, 725 ind.), whereas pseudoscorpions were represented only by Pselaphochernes scorpioides (39 ind.) and fleas by Ceratophyllus garei (3 ind.). Unlike nests of other birds, free-living mites predominated in the nests fauna (83% of individuals), followed by nidicolous species with more or less free relationship to the nests, while parasitic species represented only a negligible part of the fauna. For the first time we observed phoresy of Nenteria pandioni, a specific and abundant mite in the eagles’ nests, on the nidicolous staphylinid Haploglossa puncticollis. The beetle fauna in the nests was much poorer than in nests of other birds. The predatory H. puncticollis was dominant in the nests (83%) and occurred continuously during the whole investigation period. Other beetles, even the widely distributed nidicols such as the histerid Gnathoncus buyssoni, were found rarely in nests. Predators were also the only abundant trophic group of beetles in the nests, while other trophic groups of beetles abundantly co-occur in nests of majority of other birds. The occurrence of all beetles was very unevenly distributed during the investigation period, but was positively correlated with occurrence of mites. The relatively low number of species and individuals of mites and beetles in the lesser spotted eagle nests resulted from their position on tree tops, at a height of 20–30 m and their quick drying out by sun and wind. It was also indicated by an enormously low number of species and individuals of mycetophagous beetles, which represent a significant component of the fauna in nests of other birds.     

Origin and evolution of avian microchromosomes

The origin of avian microchromosomes has long been the subject of much speculation and debate. Microchromosomes are a universal characteristic of all avian species and many reptilian karyotypes. The typical avian karyotype contains about 40 pairs of chromosomes and usually 30 pairs of small to tiny microchromosomes. This characteristic karyotype probably evolved 100-250 million years ago. Once the microchromosomes were thought to be a non-essential component of the avian genome. Recent work has shown that even though these chromosomes represent only 25% of the genome; they encode 50% of the genes. Contrary to popular belief, microchromosomes are present in a wide range of vertebrate classes, spanning 400-450 million years of evolutionary history. In this paper, comparative gene mapping between the genomes of chicken, human, mouse and zebrafish, has been used to investigate the origin and evolution of avian microchromosomes during this period. This analysis reveals evidence for four ancient syntenies conserved in fish, birds and mammals for over 400 million years. More than half, if not all, microchromosomes may represent ancestral syntenies and at least ten avian microchromosomes are the product of chromosome fission. Birds have one of the smallest genomes of any terrestrial vertebrate. This is likely to be the product of an evolutionary process that minimizes the DNA content (mostly through the number of repeats) and maximizes the recombination rate of microchromosomes. Through this process the properties (GC content, DNA and repeat content, gene density and recombination rate) of microchromosomes and macrochromosomes have diverged to create distinct chromosome types. An ancestral genome for birds likely had a small genome, low in repeats and a karyotype with microchromosomes. A "Fission-Fusion Model" of microchromosome evolution based on chromosome rearrangement and minimization of repeat content is discussed.     

The karyotype of the Iberian imperial eagle (Aquila adalberti) analyzed by classical and DNA replication banding.

We report here for the first time the karyotype of the Iberian imperial eagle (Aquila adalberti). All eagles examined had a diploid number of 82 chromosomes and a greater number of microchromosomes (12 pairs) than has been found in all other species of the Accipitridae family. This karyotypic evidence corroborates the recent separation of A. adalberti from A. heliaca on the basis of molecular data. RB-FPG banding induced a specific banding pattern that allowed us to identify homologous chromosome pairs and revealed features about late and early replicating regions. Several chromosome banding techniques (C-, CMA3-, and restriction endonuclease banding and silver staining) were used to characterize the karyotype more accurately. Two GC-rich, late-replicating heterochromatin regions were found in the W chromosome. These regions are AluI resistant and can be used for sex determination in this species. All microchromosomes were heterochromatic, GC rich, and late replicating. Silver staining revealed active nucleolus organizing regions on a pair of microchromosomes that were entirely heterochromatic and stained intensely after CMA3-banding. Different chromosome rearrangements are discussed in order to establish the phylogenetic relationship between A. adalberti and its most closely related species, A. heliaca.     

New insights into sex chromosome evolution in anole lizards (Reptilia,Dactyloidae)

Anoles are a clade of iguanian lizards that underwent an extensive radiation between 125 and 65 million years ago. Their karyotypes show wide variation in diploid number spanning from 26 (Anolis evermanni) to 44 (A. insolitus). This chromosomal variation involves their sex chromosomes, ranging from simple systems (XX/XY), with heterochromosomes represented by either micro- or macrochromosomes, to multiple systems (X₁X₁X₂X₂/X₁X₂Y). Here, for the first time, the homology relationships of sex chromosomes have been investigated in nine anole lizards at the whole chromosome level. Cross-species chromosome painting using sex chromosome paints from A. carolinensis, Ctenonotus pogus and Norops sagrei and gene mapping of X-linked genes demonstrated that the anole ancestral sex chromosome system constituted by microchromosomes is retained in all the species with the ancestral karyotype (2n?=?36, 12 macro- and 24 microchromosomes). On the contrary, species with a derived karyotype, namely those belonging to genera Ctenonotus and Norops, show a series of rearrangements (fusions/fissions) involving autosomes/microchromosomes that led to the formation of their current sex chromosome systems. These results demonstrate that different autosomes were involved in translocations with sex chromosomes in closely related lineages of anole lizards and that several sequential microautosome/sex chromosome fusions lead to a remarkable increase in size of Norops sagrei sex chromosomes.     

Synteny conservation of chicken macrochromosomes 1-10 in different avian lineages revealed by cross-species chromosome painting

Cross-species chromosome painting can directly visualize syntenies between diverged karyotypes and, thus, increase our knowledge on avian genome evolution. DNA libraries of chicken (Gallus gallus, GGA) macrochromosomes 1 to 10 were hybridized to metaphase spreads of 9 different species from 3 different orders (Anseriformes, Gruiformes and Passeriformes). Depending on the analyzed species, GGA1-10 delineated 11 to 13 syntenic chromosome regions, indicating a high degree of synteny conservation. No exchange between the GGA macrochromosome complement and microchromosomes of the analyzed species was observed. GGA1 and GGA4 were distributed on 2 or 3 chromosomes each in some of the analyzed species, indicating rare evolutionary rearrangements between macrochromosomes. In all 6 analyzed species of Passeriformes, GGA1 was diverged on 2 macrochromosomes, representing a synapomorphic marker for this order. GGA4 was split on 2 chromosomes in most karyotypes, but syntenic to a single chromosome in blackcap (Passeriformes). GGA5/10 and also GGA8/9 associations on chromosomes were found to be important cytogenetic features of the Eurasian nuthatch (Passeriformes) karyotype. Fusion of GGA4 and GGA5 segments and of entire GGA6 and GGA7, respectively, was seen in the 2 analyzed species of Gruiformes. Consistent with the literature, our inter-species chromosome painting demonstrates remarkable conservation of macrochromosomal synteny over 100 million years of avian evolution. The low rate of rearrangements between macrochromosomes and the absence of detectable macrochromosome-microchromosome exchanges suggests a predominant role for rearrangements within the gene-dense microchromosome complement in karyotypic diversification.     

A comparative karyological study of the blue-breasted quail (Coturnix chinensis, Phasianidae) and California quail (Callipepla californica, Odontophoridae)

We conducted comparative chromosome painting and chromosome mapping with chicken DNA probes against the blue-breasted quail (Coturnix chinensis, CCH) and California quail (Callipepla californica, CCA), which are classified into the Old World quail and the New World quail, respectively. Each chicken probe of chromosomes 1-9 and Z painted a pair of chromosomes in the blue-breasted quail. In California quail, chicken chromosome 2 probe painted chromosomes 3 and 6, and chicken chromosome 4 probe painted chromosomes 4 and a pair of microchromosomes. Comparison of the cytogenetic maps of the two quail species with those of chicken and Japanese quail revealed that there are several intrachromosomal rearrangements, pericentric and/or paracentric inversions, in chromosomes 1, 2 and 4 between chicken and the Old World quail. In addition, a pericentric inversion was found in chromosome 8 between chicken and the three quail species. Ordering of the Z-linked DNA clones revealed the presence of multiple rearrangements in the Z chromosomes of the three quail species. Comparing these results with the molecular phylogeny of Galliformes species, it was also cytogenetically supported that the New World quail is classified into a different clade from the lineage containing chicken and the Old World quail.     

Fecal steroid monitoring for assessing gonadal and adrenal activity in the golden eagle and peregrine falcon

We examined the efficacy of noninvasive monitoring of endocrine function via fecal steroid immunoassays in the golden eagle and peregrine falcon. High-pressure liquid chromatography analyses of fecal glucocorticoid metabolites (fGCM) revealed that minor percentages of immunoreactive fGCM co-eluted with [³H]corticosterone in both sexes of the eagle (2.5–2.7%) and falcon (7.5–11.9%). In contrast, most fecal estrogen metabolites in eagle and falcon females co-eluted with radiolabeled estradiol-17β ([³H]; 57.6, 64.6%, respectively) or estrone ([³H]; 26.9, 4.1%, respectively). Most fecal progestin metabolite immunoreactivity in the female eagle (24.8%) and falcon (21.7%) co-eluted with progesterone ([¹⁴C]). Most fecal androgen metabolite immunoreactivity in eagle (55.8%) and falcon (63.7%) males co-eluted with testosterone ([¹⁴C]). Exogenous adrenocorticotropin hormone induced increased fGCM excretion above pre-treatment in both species, but only significantly (P < 0.05) in the eagle. Both species showed increased fGCM after saline administration, suggesting the detection of ‘handling stress.’ Both species exhibited enterohepatic and renal recirculation of administered steroids as demonstrated by biphasic and triphasic excretion patterns. Thus, noninvasive fecal hormone monitoring is a valid and promising tool for assessing gonadal and adrenal status in rare and threatened birds-of-prey.     

FISH mapping of 57 BAC clones reveals strong conservation of synteny between Galliformes and Anseriformes

Karyotypes of chicken (Gallus gallus domesticus; 2n = 78) and mallard duck (Anas platyrhynchos; 2n = 80) share the typical organization of avian karyotypes including a few macrochromosome pairs, numerous indistinguishable microchromosomes, and Z and W sex chromosomes. Previous banding studies revealed great similarities between chickens and ducks, but it was not possible to use comparative banding for the microchromosomes. In order to establish precise chromosome correspondences between these two species, particularly for microchromosomes, we hybridized 57 BAC clones previously assigned to the chicken genome to duck metaphase spreads. Although most of the clones showed similar localizations, we found a few intrachromosomal rearrangements of the macrochromosomes and an additional microchromosome pair in ducks. BAC clones specific for chicken microchromosomes were localized to separate duck microchromosomes and clones mapping to the same chicken microchromosome hybridized to the same duck microchromosome, demonstrating a high conservation of synteny. These results demonstrate that the evolution of karyotypes in avian species is the result of fusion and/or fission processes and not translocations.