Evolution of preproinsulin gene in birds

Chickens from lines artificially selected for juvenile low and high body weight differ in glucose homeostasis and pancreas physiology

Artificial selection of White Plymouth Rock chickens for juvenile (day 56) body weight resulted in two divergent genetic lines: hypophagic low weight (LWS) chickens and hyperphagic obese high weight (HWS) chickens, with the latter more than 10-fold heavier than the former at selection age. A study was designed to investigate glucose regulation and pancreas physiology at selection age in LWS chickens and HWS chickens. Oral glucose tolerance and insulin sensitivity tests revealed differences in threshold sensitivity to insulin and glucose clearance rate between the lines. Results from real-time PCR showed greater pancreatic mRNA expression of four glucose regulatory genes (preproinsulin, PPI; preproglucagon, PPG; glucose transporter 2, GLUT2; and pancreatic duodenal homeobox 1, Pdx1) in LWS chickens, than HWS chickens. Histological analysis of the pancreas revealed that HWS chickens have larger pancreatic islets, less pancreatic islet mass, and more pancreatic inflammation than LWS chickens, all of which presumably contribute to impaired glucose metabolism.

Birds and longevity: does flight driven aerobicity provide an oxidative sink?

Birds generally age slower and live longer than similar sized mammals. For birds this occurs despite elevated blood glucose levels that for mammals would in part define them as diabetic. However these data were acquired in respiration states that have little resemblance to conditions in healthy tissues and mitochondrial RS production is probably minimal in healthy animals. Indeed mitochondria probably act as net consumers rather than producers of RS. Here we propose that (1) if mitochondria are antioxidant systems, the greater mitochondrial mass in athletic species, such as birds, is advantageous as it should provide a substantial sink for RS. (2) The intense drive for aerobic performance and decreased body density to facilitate flight may explain the relative insensitivity of birds to insulin, as well as depressed insulin levels and apparent sensitization to glucagon. Glucagon also associates with the sirtuin protein family, most of which are associated with caloric restriction regulated pathways, mitochondrial biogenesis and life span extension. (3) We note that telomeres, which appear to be unusually long in birds, bind Sirtuins 2 and 4 and therefore may stabilize and protect nuclear DNA. Ultimately these flight driven responses may suppress somatic growth and protect DNA from oxidative damage that would otherwise lead to ageing and non-viral cancers.

[Genetic variance of duck preproinsulin gene and its correlations to the traits of carcasses]

Genetic polymorphisms of exon 2 and partial intron of preproinsulin gene were studied in Peking duck and Cherry Valley duck by PCR-SSCP and DNA sequencing technologies. Two single nucleotide mutations, T179C and C195T, were found, respectively. chi2 test reflects that the tested population of Peking duck and Cherry Valley duck were in the Hardy-Weinberg equilibrium state (P>0.05). The relationships between SNPs and the traits of carcasses were analyzed by the least square analysis, which showed that the genotype BB in three lines of Peking duck was significantly higher in carcass weight, carcass net weight and breast muscle weight than AA and BB (P<0.01) and significantly higher in leg muscle weight and sebum weight than AB (P<0.01). In addition, the genotype AA was significantly greater than AB in sebum rate (P<0.01) and carcass net weight (P<0.05), respectively. However, for Cherry Valley duck, only the genotype AB was significantly higher than AA in sebum weight and abdomen fat weight (P<0.05). The results indicated that there was significant correlation between the genetic polymorphisms of preproinsulin gene and the traits of duck carcasses and the allele B was valuable for increasing the carcass weight and breast muscle weight.

Diabetes mellitus concurrent with hepatic haemosiderosis in two macaws (Ara severa, Ara militaris)

Diabetes mellitus was diagnosed in a 5-year-old male chestnut-fronted macaw (Ara severa) and an 8-year-old female Military macaw (Ara militaris) based on persistent hyperglycaemia and glucosuria. Hepatic biopsies showed marked hepatic haemosiderosis, while pancreatic biopsies showed no inflammatory lesions. Repeatable and titratable responses to bovine or porcine protamine zinc insulin were recorded in both patients, who were followed up for more than 2 years. In addition, iron-elimination therapy was initiated by chelation or phlebotomy, and the birds' diet was changed to low-iron content pellets. Both birds responded favourably to this therapy, showing a decreased demand for extrinsic insulin. Follow-up biopsies demonstrated marked reduction in hepatic haemosiderin. Plasma fructosamine and beta-hydroxybutyric acid levels were measured periodically in both birds and compared with euglycaemic psittacines. Both tests appeared useful for monitoring treatment success. The potential association between diabetes mellitus and excessive iron storage in birds should be further investigated.

Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion

In recent years, avian systematics has been characterized by a diminished reliance on morphological cladistics of modern taxa, intensive palaeornithogical research stimulated by new discoveries and an inundation by analyses based on DNA sequences. Unfortunately, in contrast to significant insights into basal origins, the broad picture of neornithine phylogeny remains largely unresolved. Morphological studies have emphasized characters of use in palaeontological contexts. Molecular studies, following disillusionment with the pioneering, but non-cladistic, work of Sibley and Ahlquist, have differed markedly from each other and from morphological works in both methods and findings. Consequently, at the turn of the millennium, points of robust agreement among schools concerning higher-order neornithine phylogeny have been limited to the two basalmost and several mid-level, primary groups. This paper describes a phylogenetic (cladistic) analysis of 150 taxa of Neornithes, including exemplars from all non-passeriform families, and subordinal representatives of Passeriformes. Thirty-five outgroup taxa encompassing Crocodylia, predominately theropod Dinosauria, and selected Mesozoic birds were used to root the trees. Based on study of specimens and the literature, 2954 morphological characters were defined; these characters have been described in a companion work, approximately one-third of which were multistate (i.e. comprised at least three states), and states within more than one-half of these multistate characters were ordered for analysis. Complete heuristic searches using 10 000 random-addition replicates recovered a total solution set of 97 well-resolved, most-parsimonious trees (MPTs). The set of MPTs was confirmed by an expanded heuristic search based on 10 000 random-addition replicates and a full ratchet-augmented exploration to ascertain global optima. A strict consensus tree of MPTs included only six trichotomies, i.e. nodes differing topologically among MPTs. Bootstrapping (based on 10 000 replicates) percentages and ratchet-minimized support (Bremer) indices indicated most nodes to be robust. Several fossil Neornithes (e.g. Dinornithiformes, Aepyornithiformes) were placed within the ingroup a posteriori either through unconstrained, heursitic searches based on the complete matrix augmented by these taxa separately or using backbone-constraints. Analysis confirmed the topology among outgroup Theropoda and achieved robust resolution at virtually all levels of the Neornithes. Findings included monophyly of the palaeognathous birds, comprising the sister taxa Tinamiformes and ratites, respectively, and the Anseriformes and Galliformes as monophyletic sister-groups, together forming the sister-group to other Neornithes exclusive of the Palaeognathae (Neoaves). Noteworthy inferences include: (i) the sister-group to remaining Neoaves comprises a diversity of marine and wading birds; (ii) Podicipedidae are the sister-group of Gaviidae, and not closely related to the Phoenicopteridae, as recently suggested; (iii) the traditional Pelecaniformes, including the shoebill (Balaeniceps rex) as sister-taxon to other members, are monophyletic; (iv) traditional Ciconiiformes are monophyletic; (v) Strigiformes and Falconiformes are sister-groups; (vi) Cathartidae is the sister-group of the remaining Falconiformes; (vii) Ralliformes (Rallidae and Heliornithidae) are the sister-group to the monophyletic Charadriiformes, with the traditionally composed Gruiformes and Turniciformes (Turnicidae and Mesitornithidae) sequentially paraphyletic to the entire foregoing clade; (viii) Opisthocomus hoazin is the sister-taxon to the Cuculiformes (including the Musophagidae); (ix) traditional Caprimulgiformes are monophyletic and the sister-group of the Apodiformes; (x) Trogoniformes are the sister-group of Coliiformes; (xi) Coraciiformes, Piciformes and Passeriformes are mutually monophyletic and closely related; and (xii) the Galbulae are retained within the Piciformes. Unresolved portions of the Neornithes (nodes having more than one most-parsimonious solution) comprised three parts of the tree: (a) several interfamilial nodes within the Charadriiformes; (b) a trichotomy comprising the (i) Psittaciformes, (ii) Columbiformes and (iii) Trogonomorphae (Trogoniformes, Coliiformes) + Passerimorphae (Coraciiformes, Piciformes, Passeriformes); and (c) a trichotomy comprising the Coraciiformes, Piciformes and Passeriformes. The remaining polytomies were among outgroups, although several of the highest-order nodes were only marginally supported; however, the majority of nodes were resolved and met or surpassed conventional standards of support. Quantitative comparisons with alternative hypotheses, examination of highly supportive and diagnostic characters for higher taxa, correspondences with prior studies, complementarity and philosophical differences with palaeontological phylogenetics, promises and challenges of palaeogeography and calibration of evolutionary rates of birds, and classes of promising evidence and future directions of study are reviewed. Homology, as applied to avian examples of apparent homologues, is considered in terms of recent theory, and a revised annotated classification of higher-order taxa of Neornithes and other closely related Theropoda is proposed. (c) 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 149, 1-95.

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.