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Results for “Palaeognathae”

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At least 19 recordsLinked to original sources
PubMed2005

The kinematics of feeding and drinking in palaeognathous birds in relation to cranial morphology.

Cranial kinesis is an important feature in avian feeding behaviour and involves the transmission of quadrate movement to the upper bill by the Pterygoid-Palatinum Complex (PPC). The PPC in Palaeognathae is remarkably different from that found in Neognathae. In this study we analyse whether the special morphology of the PPC is an adaptation to the feeding behaviour of the Palaeognathae. Behavioural analyses of the rhea Rhea americana showed that the feeding behaviour of the rhea is typical ;Catch and Throw' behaviour, independent of the size of the food item. Drinking is achieved by a scooping movement followed by a low-amplitude tip-up phase. During feeding rhynchokinetic movements of the upper bill were observed. However, cranial kinesis was limited and may differ from rhynchokinesis in neognathes as a clear bending zone seemed absent. Since the movement patterns are considered very similar to the basic feeding behaviour in neognathous birds it is concluded that the specific morphology of the PPC is not the result of specific functional demands from palaeognathous feeding behaviour.

Animals↗
PubMed1998

The complete mitochondrial genome of Rhea americana and early avian divergences.

The complete mitochondrial DNA, mtDNA, molecule of the greater rhea, Rhea americana, was sequenced. The size of the molecule is 16,710 nucleotides. The organization of the molecule conforms with that described for the chicken and the ostrich. It has been shown previously that relative to other vertebrates the NADH3 gene of the ostrich has an insertion of one nucleotide in position 174 of the gene. The same observation was made in the rhea and in the newly sequenced NADH3 gene of the emu, Dromaius novaehollandiae. Comparison with the NADH3 gene of the chicken and the rook suggests that the inserted nucleotide may be deleted by RNA editing. The divergence between the two struthioniform species, the ostrich and the rhea, was molecularly dated at approximately 51 million years before present, MYBP. This dating is more recent than commonly acknowledged. Phylogenetic analysis of the complete cytochrome b genes of seven avian orders placed the Passeriformes basal in the avian tree with the Struthioniformes among the remaining Neognathae. These findings challenge the commonly accepted notion that the most basal avian divergence is that between the Palaeognathae and Neognathae.

Animals↗
PubMed2006

A novel family of repetitive DNA sequences amplified site-specifically on the W chromosomes in Neognathous birds.

A novel family of repetitive DNA sequences was molecularly cloned from ApaI-digested genomic DNA of two Galliformes species, Japanese quail (Coturnix japonica) and guinea fowl (Numida meleagris), and characterized by chromosome in-situ hybridization and filter hybridization. Both the repeated sequence elements produced intensely painted signals on the W chromosomes, whereas they weakly hybridized to whole chromosomal regions as interspersed-type repetitive sequences. The repeated elements of the two species had high similarity of nucleotide sequences, and cross-hybridized to chromosomes of two other Galliformes species, chicken (Gallus gallus) and blue-breasted quail (Coturnix chinensis). The nucleotide sequences were conserved in three other orders of Neognathous birds, the Strigiformes, Gruiformes and Falconiformes, but not in Palaeognathous birds, the Struthioniformes and Tinamiformes, indicating that the repeated sequence elements were amplified on the W chromosomes in the lineage of Neognathous birds after the common ancestor diverged into the Palaeognathae and Neognathae. They are components of the W heterochromatin in Neognathous birds, and a good molecular cytogenetic marker for estimating the phylogenetic relationships and for clarifying the origin of the sex chromosome heterochromatin and the process of sex chromosome differentiation in birds.

Animals↗
PubMed2003

Evolution of the spindlin gene in birds: independent cessation of the recombination of sex chromosomes at the spindlin locus in neognathous birds and tinamous, a palaeognathous avian family.

Tinamous (Aves, Palaeognathae, Tinamiformes) are primitive birds, generally considered to be the sister group to the ratites. Tinamous possess a W sex-chromosome, intermediate in heterochromatization between the largely euchromatic W chromosome of the ratites and the highly condensed W chromosome of the neognathous birds. Of the four genes which are known to have diverged copies on the neognathous avian W and Z chromosome (ATP5A1, CHD1, PKC and SPIN) only the spindlin gene has W- and Z-chromosomal forms in the tinamiformes. This paper describes experiments which show that the sequences of these forms are more similar to each other and to the homologous undifferentiated spindlin gene sequences in the ratite genome than to the W or Z forms of the spindlin gene in other, neognathous species. This suggests that cessation of recombination at the spindlin locus of the ancestral W and Z chromosomes of the paleognathous tinamiformes and the neognathous avian species were independent events.

Animals↗
PubMed1997

The mtDNA sequence of the ostrich and the divergence between paleognathous and neognathous birds.

The complete mitochondrial DNA (mtDNA) molecule of the ostrich, Struthio camelus, was sequenced. The size of the molecule is 16,591 nucleotides. Since the ostrich represents the paleognathous birds, comparison with the mtDNA of the neognathous chicken, the only avian species reported so far in databases, made it possible to identify common and, probably, general avian mtDNA characteristics. Relative to other vertebrates, the avian NADH6 and tRNA-Glu genes are positioned upstream of the control region rather than the cytochrome b gene. The NADH3 gene of the ostrich is terminated by a stop codon at position 207. Thus, the gene is about 140 nucleotides shorter than in other vertebrates. The sequence for L-strand origin of replication is missing in both birds, and four transfer RNA genes of the two avian mtDNAs deviate from common characteristics of tRNAs of vertebrate mtDNAs by having an adenine (and not a thymidine) at position 8. Due to the absence of suitable fossils, most paleontological datings of avian divergences are conjectural. Molecular dating of the divergence between the ostrich and the chicken indicates that these two avian lineages separated 80-90 MYA. Phylogenetic analysis of complete cytochrome b genes of six avian orders showed that Passeriformes represent the earliest divergence among recent birds, contradicting the commonly accepted notion of a basal position of the Palaeognathae among recent birds.

Animals↗
PubMed2001

Three-dimensional kinematics of skeletal elements in avian prokinetic and rhynchokinetic skulls determined by Roentgen stereophotogrammetry.

Several different types of cranial kinesis are present within modern birds, enabling them to move (part of) the upper bill relative to the braincase. This movement of the upper bill results from movement of the quadrate and the pterygoid-palatine complex (PPC). The taxon Palaeognathae is characterised by a very distinct PPC and a special type of cranial kinesis (central kinesis) that is very different from that found in the Neognathae. This has led some authors to hypothesise that there is a functional relationship between the morphology of the PPC and the type of cranial kinesis. This hypothesis is tested here by analysing the movement pattern of both the upper bill and the PPC in birds with three different types of cranial kinesis: prokinesis, distal rhynchokinesis and central rhynchokinesis. Movement patterns were determined using a Roentgen stereophotogrammetry method, which made it possible to detect very small displacements (0.5 mm) of bony elements in three dimensions, while the jaw muscles and ligaments remained intact. We found that in all types of kinesis investigated the movements of the quadrate, jugal bars and PPC are similar. Movement of the quadrate is transferred to the upper beak by the jugal bar and the PPC, which moves almost exclusively forwards and backwards, thereby elevating or depressing the upper bill. The differences between the types of kinesis lie only in the position of the point of rotation. These findings indicate that there is no correlation between the specific morphology of the PPC and the type of cranial kinesis. Several other factors, including the external forces applied during food acquisition, may influence the morphology of the PPC. Differences in PPC morphology therefore appear to be the result of different functional demands acting on the system simultaneously but with different strengths, depending on the species.

Animals↗
PubMed2005

Postnatal ontogeny, population structure, and extinction of the giant moa Dinornis.

Recent reinterpretation of the giant moa Dinornis as consisting of two sexually dimorphic allospecies permits thorough site-by-site investigation of the ontogeny and population biology of this genus. Analysis of subadult skeletal material from natural swamp sites in the North and South Islands of New Zealand forms the basis for recognition of growth series for each long bone element, characterized by sequential formation of fossulae in the femur and fusion of bones in the tibiotarsus and tarsometatarsus. Femora reached progressive developmental stages more rapidly than the other long bones, but all three elements reached maturity at about the same time. Patterns of bone fusion in Dinornis are more similar to those in Apteryx than in Struthio, and kiwi are recognized as a suitable developmental analog for interpreting moa ontogeny. Samples from Bell Hill Vineyard Swamp (South Island) and Makirikiri swamp (North Island) are interpreted as representing autochthonous moa populations; comparison with stages of kiwi long bone development suggests that Dinornis at these sites had high adult survivorship in strongly K-selected populations, with 72.5-87.3% of individuals having achieved adult body mass, and 55.9-78.2% being sexually mature. The pattern of low fecundity and probable high longevity in both Dinornis species suggests that populations were vulnerable to loss of adults, primarily through hunting, rather than as a result of habitat destruction.

Animals↗
PubMed2006

Microstructure and chemical composition of giant avian eggshells.

The microstructure and composition of the layers of two giant avian eggshells were investigated using a combination of scanning electron microscopy, electron probe microanalyses, and X-ray absorption near-edge structure spectroscopy (XANES). The two species have some similarities and differences in their microstructure and composition; the composition is not homogeneous throughout the eggshell thickness. XANES studies show that sulfur is associated with amino acids in the inner organic membranes, whereas in the mineralised layers the sulfur is mainly associated with sulfated polysaccharides. These results are similar to those obtained on chicken eggshells, and confirm the active role of sulfated acidic polysaccharides in biomineralisation processes of carbonate skeletons.

Animals↗
PubMed2007

Comparison of the Z and W sex chromosomal architectures in elegant crested tinamou (Eudromia elegans) and ostrich (Struthio camelus) and the process of sex chromosome differentiation in palaeognathous birds.

To clarify the process of avian sex chromosome differentiation in palaeognathous birds, we performed molecular and cytogenetic characterization of W chromosome-specific repetitive DNA sequences for elegant crested tinamou (Eudromia elegans, Tinamiformes) and constructed comparative cytogenetic maps of the Z and W chromosomes with nine chicken Z-linked gene homologues for E. elegans and ostrich (Struthio camelus, Struthioniformes). A novel family of W-specific repetitive sequences isolated from E. elegans was found to be composed of guanine- and cytosine-rich 293-bp elements that were tandemly arrayed in the genome as satellite DNA. No nucleotide sequence homologies were found for the Struthioniformes and neognathous birds. The comparative cytogenetic maps of the Z and W chromosomes of E. elegans and S. camelus revealed that there are partial deletions in the proximal regions of the W chromosomes in the two species, and the W chromosome is more differentiated in E. elegans than in S. camelus. These results suggest that a deletion firstly occurred in the proximal region close to the centromere of the acrocentric proto-W chromosome and advanced toward the distal region. In E. elegans, the W-specific repeated sequence elements were amplified site-specifically after deletion of a large part of the W chromosome occurred.

Animals↗
PubMed2005

Incorporating patterns of disperser behaviour into models of seed dispersal and its effects on estimated dispersal curves.

The processes determining where seeds fall relative to their parent plant influence the spatial structure and dynamics of plant populations and communities. For animal dispersed species the factors influencing seed shadows are poorly understood. In this paper we test the hypothesis that the daily temporal distribution of disperser behaviours, for example, foraging and movement, influences dispersal outcomes, in particular the shape and scale of dispersal curves. To do this, we describe frugivory and the dispersal curves produced by the southern cassowary, Casuarius casuarius, the only large-bodied disperser in Australia's rainforests. We found C. casuarius consumed fruits of 238 species and of all fleshy-fruit types. In feeding trials, seeds of 11 species were retained on average for 309 min (+/-256 SD). Sampling radio-telemetry data randomly, that is, assuming foraging occurs at random times during the day, gives an estimated average dispersal distance of 239 m (+/-207 SD) for seeds consumed by C. casuarius. Approximately 4% of seeds were dispersed further than 1,000 m. However, observation of wild birds indicated that foraging and movement occur more frequently early and late in the day. Seeds consumed early in the day were estimated to receive dispersal distances 1.4 times the 'random' average estimate, while afternoon consumed seeds received estimated mean dispersal distances of 0.46 times the 'random' estimate. Sampling movement data according to the daily distribution of C. casuarius foraging gives an estimated mean dispersal distance of 337 m (+/-194 SD). Most animals' behaviour has a non-random temporal distribution. Consequently such effects should be common and need to be incorporated into seed shadow estimation. Our results point to dispersal curves being an emergent property of the plant-disperser interaction rather than being a property of a plant or species.

Animals↗
PubMed2006

Amino acid sequences and phosphorylation sites of emu and rhea eggshell C-type lectin-like proteins.

Avian calcified eggshell layers contain in their organic matrix one or two C-type lectin-like proteins. Previously characterized eggshell proteins of this family are chicken ovocleidin-17 (OC-17), goose ansocalcin and ostrich struthiocalcins 1 and 2 (SCA-1, SCA-2). In this report we present the amino acid sequences of two emu (Dromaius novaehollandiae) (dromaiocalcin-1 and -2; DCA-1, DCA-2) and of two rhea (Rhea americana) (rheacalcin-1 and -2; RCA-1, RCA-2) C-type lectin-like eggshell proteins, thus doubling the data set for comparison of these major specific eggshell proteins. The ratite proteins can be divided into two groups. Group 1, comprising SCA-1, DCA-1 and RCA-1, shows by 70--77% identity of sequences, the lack of phosphorylation, and a variable number (7--9) of cysteines. Group 2, consisting of SCA-2, DCA-2 and RCA-2, shows 78--85% identical sequences, 2--3 phosphorylated serines located at almost identical sites, and contains only the common set of six conserved cysteins characteristic for this family of proteins. While goose ansocalcin fits perfectly into group 1 with a sequence identity of 63--70% to the other members, no phosphorylation, and seven cysteines, chicken OC-17 was assigned to group 2 in spite of only 42--47% sequence identity (and 37--39% to group 1) because of its two phosphorylated serines and its regular set of six cysteines. At present it remains unknown why ratites, but not goose or chicken, require two different types of C-type lectin-like proteins to construct their eggshells.

Amino Acid Sequence↗
PubMed2003

Clarification of emu serum for peptide hormone assay using polyethylene glycol precipitation.

Interference in radioimmunoassays (RIAs) was frequently encountered during endocrinological studies of the emu (Dromaius novaehollandiae). Interference was greatest when serum was cloudy or opaque. Such samples appeared seasonally, in spring and summer during the phase of fat deposition, and in the winter when females were laying. These poor quality samples did not allow accurate measurement by RIAs of several peptide hormones for a full year. To prepare them for assay, these sera were clarified using a polyethylene glycol (PEG) solution at a final concentration of 7.5%. This treatment was effective in most cases. After treatment with the PEG, recoveries of LH, glucagon, and prolactin were greater than 75% and that for insulin was 40%. Regardless of the level of recovery, there was a high correlation of assay results between non-opaque native and PEG-treated sera. Serum samples containing large amounts of interfering high molecular weight components, such as lipoproteins, can be clarified with PEG, enabling their accurate measurement by RIA.

Animals↗
PubMed1998

Ratite diagnostic imaging.

Diagnostic imaging of ratite species is a challenge, even to the specialist. A portable radiography unit is frequently inadequate to penetrate the coelomic cavity of large birds, but should provide diagnostic quality radiographs of the extremities. Ultrasonography allows visualization of the coelomic structures, but will not penetrate gas or air. Use of both technologies often provides diagnostic information helpful to the clinician.

Animals↗
PubMed1998

Ratite reproduction.

The role of the veterinarian in ostrich production in the future will be to develop least-cost management programs. This article focuses on the ostrich as the only current commercially viable ratite species. Managing a successful ranch involves disease prevention, genetic selection, environmental management, and nutrition.

Animals↗
PubMed1998

Infectious diseases and parasites of ratites.

This article discusses infectious and parasitic disease conditions in the three ratite species. Diseases and parasitic conditions are reviewed in relation to etiology, transmission, pathology, diagnosis, treatment, and prevention. To ensure optimum reproduction and growth of birds on large production units, a veterinarian must understand management in relation to biosecurity and disease problems.

Animals↗
PubMed1998

Current ratite therapy.

This article describes the use of drugs and therapeutic techniques in the treatment of ratite diseases. Effective routes of administration are documented. Appropriate selection and dose regimens are provided for bacterial and parasitic conditions. This article includes empirical formularies for antibiotics and anthelmintics. Metabolic drug dosage and nutrient scaling for ratites are outlined.

Animal Feed↗
PubMed1998

Anesthesia and surgery of ratites.

Veterinary practitioners should apply common principles of anesthesia and surgery used in domestic livestock to ratites. Routine procedures can be accomplished in the field or in a veterinary hospital, provided practitioners become familiar with response of ratites to sedation and anesthesia.

Anesthesia↗