Homozygous CADPS2 Mutations Cause Neurodegenerative Disease with Lewy Body-like Pathology in Parrots.

BACKGROUND: Several genetic models that recapitulate neurodegenerative features of Parkinson's disease (PD) exist, which have been largely based on genes discovered in monogenic PD families. However, spontaneous genetic mutations have not been linked to the pathological hallmarks of PD in non-human vertebrates. OBJECTIVE: To describe the genetic and pathological findings of three Yellow-crowned parrot (Amazona ochrocepahala) siblings with a severe and rapidly progressive neurological phenotype. METHODS: The phenotype of the three parrots included severe ataxia, rigidity, and tremor, while their parents were phenotypically normal. Tests to identify avian viral infections and brain imaging studies were all negative. Due to their severe impairment, they were all euthanized at age 3 months and their brains underwent neuropathological examination and proteasome activity assays. Whole genome sequencing (WGS) was performed on the three affected parrots and their parents. RESULTS: The brains of affected parrots exhibited neuronal loss, spongiosis, and widespread Lewy body-like inclusions in many regions including the midbrain, basal ganglia, and neocortex. Proteasome activity was significantly reduced in these animals compared to a control (P < 0.05). WGS identified a single homozygous missense mutation (p.V559L) in a highly conserved amino acid within the pleckstrin homology (PH) domain of the calcium-dependent secretion activator 2 (CADPS2) gene. CONCLUSIONS: Our data suggest that a homozygous mutation in the CADPS2 gene causes a severe neurodegenerative phenotype with Lewy body-like pathology in parrots. Although CADPS2 variants have not been reported to cause PD, further investigation of the gene might provide important insights into the pathophysiology of Lewy body disorders. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Do glucocorticoids or carotenoids mediate plumage coloration in parrots? An experiment in Platycercus elegans.

Conspicuous coloration can indicate phenotypic quality, and may reflect exposure or vulnerability to stress, or access to essential nutrients such as pigments. Although the production of pigmented colours is well understood, much less is known about how structural colours are affected by physiological state. In this study, we tested whether glucocorticoids (corticosterone) predicted expression of plumage coloration in an Australian parrot, the crimson rosella (Platycercus elegans). Parrots provide an interesting and unique test, as they possess conspicuous coloration produced by distinctive pigments known as psittacofulvins, in addition to structural coloration. We have previously documented that coloration in P. elegans is condition-dependent and responds to dietary manipulation. Here, n = 21 P. elegans underwent a dietary manipulation (including food restriction or carotenoid supplementation) during which they moulted, and the change in reflectance was measured for three structural and three pigmentary plumage patches. Stress-induced corticosterone (10 min after handling) measured at the start of the experiment predicted change in coloration in two pigmentary patches (crown and front). We also found that change in stress-induced corticosterone during the experiment was associated with the change in coloration of the crown and two structural patches (cheek and epaulette). Baseline corticosterone (<3 min after handling) was not associated with any measure of coloration. We found no effects of dietary manipulation on baseline or stress-induced corticosterone, but carotenoid supplementation was associated with an increase in a measure of chronic stress (heterophil/lymphocyte ratio), and the corticosterone response to handling decreased over the course of the study. Our results suggest that corticosterone may be linked to colour expression more broadly than previously recognised, including psittacofulvin and structural coloration in parrots, and they confirm the independence of plumage pigmentation in parrots from carotenoid accumulation. Moreover, our study provides new insight into the stress responses of Psittaciformes, one of the most highly threatened avian orders.

Unique oestrogen receptor ligand-binding domain sequence of native parrots: a possible link between phytoestrogens and breeding success.

The New Zealand (NZ) native parrots kakapo, kaka and kea are classified as critically endangered, endangered and vulnerable respectively. Successful reproduction of kakapo and kaka is linked to years of high levels of fruiting in native flora (mast years). To assess a possible hormonal link between native plants and reproductive success in these parrots in mast years, we examined the ligand-binding domains (LBD) of the progesterone receptor (PR), androgen receptor (AR), estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2) in NZ native (kakapo, kaka, kea and kakariki) and non-native (Australian cockatiel) parrots and compared them with those in the chicken. The amino acid sequences for PR, AR, ESR1 and ESR2 shared >90% homology among the NZ parrots, the cockatiel and, in most cases, the chicken. The exception was for the ESR1 LBD, which contained an extra eight amino acids at the C-terminal in all the parrots compared with the chicken and with published sequences of non-parrot species. These results support the notion that the ESR1 LBD of parrots responds differently to putative oestrogenic compounds in native trees in NZ during times of intermittent masting. In turn, this may provide important information for generating parrot-specific bioassays and linkages to steroidogenic activity in native plants.

Urofecal steroid profiles of captive Blue-fronted parrots (Amazona aestiva) with different reproductive outcomes.

Despite Psitaciformes (parrots) being the third largest nonpasserine order (398 species), it currently ranks second in number of threatened species (28%) according to the Internatinal Union for Conservation of Nature (IUCN) criteria. Since most of the literature concerning reproductive endocrinology in avian species derives from domestic and song birds, it is puzzling that advances in reproductive science for the Psitaciformes order lags far behind, in spite of the growing threats against them. In order to expand our knowledge of Neotropical parrots (Psittacidae), we examined annual changes in urofecal sex steroid metabolites of Blue-fronted amazon pairs (Amazona aestiva) exhibiting successful (nestlings) and unsuccessful breeding (infertile or no eggs). Urofecal samples were collected over a year from eight breeding pairs housed under the same environmental and management conditions. Fecal androgen and progestagen concentrations were determined in males and females, respectively, by enzyme immunoassays previously validated for this species. All eggs were registered between late winter and mid-spring, and egg-laying intervals varied between females (range: 1-8 days; average 3.60 ±â€¯0.51 days). Similar profiles of urofecal progestagens were observed in reproductively successful females and females producing infertile eggs, with progestagen peaks preceding egg laying events (1.77 ±â€¯0.50 days). In contrast, non-laying females had no rises in progestagens during the year. Successful and unsuccessful males did not displayed distinct annual patterns of androgen production, and apart from the peaks during the breeding season, more than half of the individuals intriguingly presented significant increases from late summer to early autumn, a period without reproductive activity. Finally, we noticed that samples with progestagen levels exceeding 40 ng/g had very high probability (>97.5%) to be from females in pre-laying or laying phases, suggesting a feasible application of this characteristic to noninvasively discriminate the reproductive status in amazon females with an accuracy and sensitivity of 94.55% and 58.13%, respectively. Our findings confirmed that urofecal progestagens and androgens are good indicators of the gonadal condition in Blue-fronted amazons, but there is still much to be done for their extensive use in artificial insemination or selection of the most suitable breeding birds for the season.

Early procurement of scarlet macaws and the emergence of social complexity in Chaco Canyon, NM.

High-precision accelerator mass spectrometer (AMS) (14)C dates of scarlet macaw (Ara macao) skeletal remains provide the first direct evidence from Chaco Canyon in northwestern New Mexico that these Neotropical birds were procured from Mesoamerica by Pueblo people as early as ∼ A.D. 900-975. Chaco was a prominent prehistoric Pueblo center with a dense concentration of multistoried great houses constructed from the 9th through early 12th centuries. At the best known great house of Pueblo Bonito, unusual burial crypts and significant quantities of exotic and symbolically important materials, including scarlet macaws, turquoise, marine shell, and cacao, suggest societal complexity unprecedented elsewhere in the Puebloan world. Scarlet macaws are known markers of social and political status among the Pueblos. New AMS (14)C-dated scarlet macaw remains from Pueblo Bonito demonstrate that these birds were acquired persistently from Mesoamerica between A.D. 900 and 1150. Most of the macaws date before the hypothesized apogeal Chacoan period (A.D. 1040-1110) to which they are commonly attributed. The 10th century acquisition of these birds is consistent with the hypothesis that more formalized status hierarchies developed with significant connections to Mesoamerica before the post-A.D. 1040 architectural florescence in Chaco Canyon.

Pharmacokinetics of meloxicam after intravenous, intramuscular and oral administration of a single dose to African grey parrots (Psittacus erithacus).

Meloxicam is a nonsteroidal anti-inflammatory drug commonly used in avian species. In this study, the pharmacokinetic parameters for meloxicam were determined following single intravenous (i.v.), intramuscular (i.m.) and oral (p.o.) administrations of the drug (1 mg/kg·b.w.) in adult African grey parrots (Psittacus erithacus; n = 6). Serial plasma samples were collected and meloxicam concentrations were determined using a validated high-performance liquid chromatography assay. A noncompartmental pharmacokinetic analysis was performed. No undesirable side effects were observed during the study. After i.v. administration, the volume of distribution, clearance and elimination half-life were 90.6 ± 4.1 mL/kg, 2.18 ± 0.25 mL/h/kg and 31.4 ± 4.6 h, respectively. The peak mean ± SD plasma concentration was 8.32 ± 0.95 µg/mL at 30 min after i.m. administration. Oral administration resulted in a slower absorption (tmax  = 13.2 ± 3.5 h; Cmax  = 4.69 ± 0.75 µg/mL) and a lower bioavailability (38.1 ± 3.6%) than for i.m. (78.4 ± 5.5%) route. At 24 h, concentrations were 5.90 ± 0.28 µg/mL for i.v., 4.59 ± 0.36 µg/mL for i.m. and 3.21 ± 0.34 µg/mL for p.o. administrations and were higher than those published for Hispaniolan Amazon parrots at 12 h with predicted analgesic effects.

Mutations in SLC45A2 lead to loss of melanin in parrot feathers.

Bird plumage coloration is a complex and multifactorial process that involves both genetic and environmental factors. Diverse pigment groups contribute to plumage variation in different birds. In parrots, the predominant green color results from the combination of 2 different primary colors: yellow and blue. Psittacofulvin, a pigment uniquely found in parrots, is responsible for the yellow coloration, while blue is suggested to be the result of light scattering by feather nanostructures and melanin granules. So far, genetic control of melanin-mediated blue coloration has been elusive. In this study, we demonstrated that feather from the yellow mutant rose-ringed parakeet displays loss of melanosome granules in spongy layer of feather barb. Using whole genome sequencing, we found that mutation in SLC45A2, an important solute carrier protein in melanin synthetic pathway, is responsible for the sex-linked yellow phenotype in rose-ringed parakeet. Intriguingly, one of the mutations, P53L found in yellow Psittacula krameri is already reported as P58A/S in the human albinism database, known to be associated with human OCA4. We further showed that mutations in SLC45A2 gene affect melanin production also in other members of Psittaculidae family such as alexandrine and plum-headed parakeets. Additionally, we demonstrate that the mutations associated with the sex-linked yellow phenotype, localized within the transmembrane domains of the SLC45A2 protein, affect the protein localization pattern. This is the first evidence of plumage color variation involving SLC45A2 in parrots and confirmation of associated mutations in the transmembrane domains of the protein that affects its localization.

Molecular and cellular changes associated with the evolution of novel jaw muscles in parrots.

Vertebrates have achieved great evolutionary success due in large part to the anatomical diversification of their jaw complex, which allows them to inhabit almost every ecological niche. While many studies have focused on mechanisms that pattern the jaw skeleton, much remains to be understood about the origins of novelty and diversity in the closely associated musculature. To address this issue, we focused on parrots, which have acquired two anatomically unique jaw muscles: the ethmomandibular and the pseudomasseter. In parrot embryos, we observe distinct and highly derived expression patterns for Scx, Bmp4, Tgfß2 and Six2 in neural crest-derived mesenchyme destined to form jaw muscle connective tissues. Furthermore, immunohistochemical analysis reveals that cell proliferation is more active in the cells within the jaw muscle than in surrounding connective tissue cells. This biased and differentially regulated mode of cell proliferation in cranial musculoskeletal tissues may allow these unusual jaw muscles to extend towards their new attachment sites. We conclude that the alteration of neural crest-derived connective tissue distribution during development may underlie the spatial changes in jaw musculoskeletal architecture found only in parrots. Thus, parrots provide valuable insights into molecular and cellular mechanisms that may generate evolutionary novelties with functionally adaptive significance.

The effect of premedication with ketamine, alone or with diazepam, on anaesthesia with sevoflurane in parrots (Amazona aestiva).

BACKGROUND: Premedication is rarely used in avian species. The aim of this study was to evaluate the effect of premedication on the quality of sevoflurane induction and anaesthesia in parrots. We hypothesised that premedication would facilitate handling and decrease the minimum anaesthetic dose (MAD). Thirty-six adult parrots were randomly distributed in three groups: group S (n = 12) was premedicated with NaCl 0.9%; group KS (n = 12) was premedicated with 10 mg.kg-1 ketamine; and group KDS (n = 12) was premedicated with 10 mg.kg-1 ketamine and 0.5 mg.kg-1 diazepam, delivered intramuscularly. After induction using 4.5% sevoflurane introduced through a facemask, the MAD was determined for each animal. The heart rate (HR), respiratory rate (RR), systolic arterial blood pressure (SAP), and cloacal temperature (CT) were recorded before premedication (T0), 15 minutes after premedication (T1), and after MAD determination (T2). Arterial blood gas analyses were performed at T0 and T2. The quality of anaesthesia was evaluated using subjective scales based on animal behaviour and handling during induction, maintenance, and recovery. Statistical analyses were performed using analysis of variance or Kruskal-Wallis tests followed by Tukey's or Dunn's tests. RESULTS: The minimal anaesthetic doses obtained were 2.4 ± 0.37%, 1.7 ± 0.39%, and 1.3 ± 0.32% for groups S, KS, and KDS, respectively. There were no differences in HR, RR, or CT among groups, but SAP was significantly lower in group S. Sedation was observed in both the premedicated S-KS and S-KDS groups. There were no differences in the quality of intubation and recovery from anaesthesia among the three groups, although the induction time was significantly shorter in the pre-medicated groups, and the KS group showed less muscle relaxation. CONCLUSIONS: Ketamine alone or the ketamine/diazepam combination decreased the MAD of sevoflurane in parrots (Amazona aestiva). Ketamine alone or in combination with diazepam promoted a good quality of sedation, which improved handling and reduced the stress of the birds. All protocols provided safe anaesthesia in this avian species.

Seasonal thermoregulation in the burrowing parrot (Cyanoliseus patagonus).

Birds exposed to seasonal environments are faced with the problem of maintaining thermogenic homoeostasis. Previous studies have established that birds native to the Holarctic increase their Resting Metabolic Rate at different ambient temperatures (RMRTa) and Basal Metabolic Rate (BMR) in winter as an adaptation to cold temperature since winters are more severe, while their non-Holarctic counterparts generally decrease their winter BMR as an energy saving mechanism during unproductive and dry winter months. In this study, we examined seasonal thermoregulation in the burrowing parrot (Cyanoliseus patagonus), a colonial psittacine native to the Patagonian region of Argentina, a region with an unpredictable environment. We found significantly higher mass specific RMRTa and BMR in summer than in winter. Both summer and winter BMR of the species fell within the predicted 95% confident interval for a parrot of its size. Body mass was significantly higher in winter than in summer. The burrowing parrot had broad thermo-neutral zones in winter and summer. The circadian rhythm of core body temperature (Tb) of burrowing parrots was not affected by season, showing that this species regulated its Tb irrespective of season. These results suggest that the burrowing parrots' seasonal thermoregulatory responses represent that of energy conservation which is important in an unpredictable environment.

Pharmacokinetics of paroxetine, a selective serotonin reuptake inhibitor, in Grey parrots (Psittacus erithacus erithacus): influence of pharmaceutical formulation and length of dosing.

Paroxetine, a selective serotonin reuptake inhibitor, may be beneficial in the treatment of behavioural disorders in pet birds. The lack of pharmacokinetic data and clinical trials currently limits the use of this drug in clinical avian practice. This paper evaluates the pharmacokinetic properties and potential side effects of single and repeated dosing of paroxetine in Grey parrots (Psittacus erithacus erithacus). Paroxetine pharmacokinetics were studied after single i.v. and single oral dosing, and after repeated oral administration during 1 month. Plasma paroxetine concentrations were determined by liquid chromatography-tandem mass spectrometry. No undesirable side effects were observed during the study. Pharmacokinetic analysis revealed a quick distribution and rapid elimination after i.v. administration. Oral administration of paroxetine HCl dissolved in water resulted in a relatively slow absorption (T(max)=5.9±2.6 h) and a low bioavailability (31±15%). Repeated administration resulted in higher rate of absorption, most likely due to a saturation of the cytochrome P450-mediated first-pass metabolism. This study shows that oral administration of paroxetine HCl (4 mg/kg twice daily) in parrots results in plasma concentrations within the therapeutic range recommended for the treatment of depressions in humans. Further studies are needed to demonstrate the clinical efficacy of this dosage regimen in parrots with behavioural disorders.

Colourful parrot feathers resist bacterial degradation.

The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage.

The B-type natriuretic peptide of the Congo and Timneh grey parrot.

In captivity, cardiovascular diseases are common in grey parrots. The diagnosis of these diseases in living birds is difficult, and new diagnostic possibilities would be desirable. The heart is an important endocrine organ in which cardiomyocytes synthetise B-type natriuretic peptide (BNP) and release it into the bloodstream. This hormone has a significant role in cardiovascular and body fluid regulation. The blood concentration of BNP is used in human medicine and small animal medicine as a diagnostic tool in the identification of heart diseases and as a prognostic marker for the risk of mortality. The nucleotide and amino acid sequence of BNP was described in Congo (n = 4) and Timneh (n = 3) grey parrots by PCR after RNA isolation from the atria and ventricles. The results showed a high similarity between the nucleotide sequences of the grey parrots' BNP and the already known sequence of this hormone in chickens. The amino acid sequence of the mature peptide region is consistent in these three species. BNP plasma concentration could be a possible blood parameter for identifying clinically manifest cardiovascular diseases in grey parrots as it is in other species.

The plasma lipidome of the Quaker parrot (Myiopsitta monachus).

Dyslipidemias and lipid-accumulation disorders are common in captive parrots, in particular in Quaker parrots. Currently available diagnostic tests only measure a fraction of blood lipids and have overall problematic cross-species applicability. Comprehensively analyzing lipids in the plasma of parrots is the first step to better understand their lipid metabolism in health and disease, as well as to explore new lipid biomarkers. The plasma lipidome of 12 Quaker parrots was investigated using UHPLC-MS/MS with both targeted and untargeted methods. Targeted methods on 6 replicates measured 432 lipids comprised of sterol, cholesterol ester, bile acid, fatty acid, acylcarnitine, glycerolipid, glycerophospholipid, and sphingolipid panels. For untargeted lipidomics, precursor ion mass-to-charge ratios were matched to corresponding lipids using the LIPIDMAPS structure database and LipidBlast at the sum composition or acyl species level of information. Sterol lipids and glycerophospholipids constituted the majority of plasma lipids on a molar basis. The most common lipids detected with the targeted methods included free cholesterol, CE(18:2), CE(20:4) for sterol lipids; PC(36:2), PC(34:2), PC(34:1) for glycerophospholipids; TG(52:3), TG(54:4), TG(54:5), TG(52:2) for glycerolipids; SM(d18:1/16:0) for sphingolipids; and palmitic acid for fatty acyls. Over a thousand different lipid species were detected by untargeted lipidomics. Sex differences in the plasma lipidome were observed using heatmaps, principal component analysis, and discriminant analysis. This report presents the first comprehensive database of plasma lipid species in psittacine birds and paves the way for further research into blood lipid diagnostics and the impact of diet, diseases, and drugs on the parrot plasma lipidome.

Evolution and diversity in avian vocal system: an Evo-Devo model from the morphological and behavioral perspectives.

Birds use various vocalizations to mark their territory and attract mates. Three groups of birds (songbirds, parrots, and hummingbirds) learn their vocalizations through imitation. In the brain of such vocal learners, there is a neural network called the song system specialized for vocal learning and production. In contrast, birds such as chickens and pigeons do not have such a neural network and can only produce innate sounds. Since each avian species shows distinct, genetically inherited vocal learning abilities that are related to its morphology, the avian vocal system is a good model for studying the evolution of functional neural circuits. Nevertheless, studies on avian vocalization from an evolutionary developmental-biological (Evo-Devo) perspective are scant. In the present review, we summarize the results of songbird studies and our recent work that used the Evo-Devo approach to understand the evolution of the avian vocal system.

Intraspecific geographic variation in rod and cone visual pigment sensitivity of a parrot, Platycercus elegans.

Variation in wavelength sensitivity among subspecies is unknown among vertebrates. The parrot Platycercus elegans has extreme plumage variation between subspecies ranging from pale yellow to crimson which, with differences in background colour and light environment between subspecies, makes it a good candidate for the evolution of within-species differences in vision. We report differences in visual pigments between populations of P. elegans from two subspecies, providing the first known support for population and subspecies variation in visual pigments within a vertebrate species; it is also the first instance of intraspecific variation in rod sensitivity within any vertebrate species. Differences in wavelength sensitivity of rods and cones corresponded to geographic differences in plumage colour. Between study populations, visual pigments varied but not oil droplets. Adaptive functions for the visual pigment differences are untested but they could cause divergence in behaviours associated with colour as well as in dim light, and provide insights into the role of senses in divergence and speciation.

Pharmacokinetics of fluconazole after oral administration of single and multiple doses in African grey parrots.

OBJECTIVE: To determine the pharmacokinetics and effects of orally administered fluconazole in African grey parrots. ANIMALS: 40 clinically normal Timneh African grey parrots (Psittacus erithacus timneh). PROCEDURE: In single-dose trials, parrots were placed into groups of 4 to 5 birds each and fluconazole was administered orally at 10 and 20 mg/kg. Blood samples for determination of plasma fluconazole concentrations were collected from each group at 2 or 3 of the following time points: 1, 3, 6, 9, 12, 24, 31, 48, and 72 hours. In multiple-dose trials, fluconazole was administered orally to groups of 5 birds each at doses of 10 and 20 mg/kg every 48 hours for 12 days. Trough plasma concentrations were measured 3 times during treatment. Groups receiving 20 mg/kg were monitored for changes in plasma biochemical analytes, and blood samples were collected on days 1 and 13 of treatment to allow comparison of terminal half-life. RESULTS: Peak plasma concentrations of fluconazole were 7.45 and 18.59 microg/mL, and elimination half-lives were 9.22 and 10.19 hours for oral administration of 10 and 20 mg/kg, respectively. Oral administration of fluconazole for 12 days at 10 or 20 mg/kg every 48 hours did not cause identifiable adverse effects or change the disposition of fluconazole. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of fluconazole to parrots at 10 to 20 mg/kg every 24 to 48 hours maintains plasma concentrations above the minimum inhibitory concentration for several common yeast species. The prolonged dosing interval is an advantage of this treatment regimen.

Effects of UVB radiation on calcium metabolism in psittacine birds.

The effects of providing ultraviolet (uv) radiation (285 to 315 nm, ultraviolet B) on calcium metabolism in two groups of 20 healthy grey parrots (Psittacus e erithacus) fed either a seed or pellet-based diet were investigated. There was a significant increase in the concentration of ionised calcium in the plasma of both groups, independent of the calcium and vitamin D(3) content of the diets fed, and a significant increase in the plasma concentration of 25-hydroxycholecalciferol in only the seed-fed group. In a separate study there were no significant increases in plasma ionised calcium or 25-hydroxycholecalciferol between March and August in a group of 28 South American parrots (Pionus species) exposed to unfiltered natural sunlight.

Differential expression of glutamate receptors in avian neural pathways for learned vocalization.

Learned vocalization, the substrate for human language, is a rare trait. It is found in three distantly related groups of birds-parrots, hummingbirds, and songbirds. These three groups contain cerebral vocal nuclei for learned vocalization not found in their more closely related vocal nonlearning relatives. Here, we cloned 21 receptor subunits/subtypes of all four glutamate receptor families (AMPA, kainate, NMDA, and metabotropic) and examined their expression in vocal nuclei of songbirds. We also examined expression of a subset of these receptors in vocal nuclei of hummingbirds and parrots, as well as in the brains of dove species as examples of close vocal nonlearning relatives. Among the 21 subunits/subtypes, 19 showed higher and/or lower prominent differential expression in songbird vocal nuclei relative to the surrounding brain subdivisions in which the vocal nuclei are located. This included relatively lower levels of all four AMPA subunits in lMAN, strikingly higher levels of the kainite subunit GluR5 in the robust nucleus of the arcopallium (RA), higher and lower levels respectively of the NMDA subunits NR2A and NR2B in most vocal nuclei and lower levels of the metabotropic group I subtypes (mGluR1 and -5) in most vocal nuclei and the group II subtype (mGluR2), showing a unique expression pattern of very low levels in RA and very high levels in HVC. The splice variants of AMPA subunits showed further differential expression in vocal nuclei. Some of the receptor subunits/subtypes also showed differential expression in hummingbird and parrot vocal nuclei. The magnitude of differential expression in vocal nuclei of all three vocal learners was unique compared with the smaller magnitude of differences found for nonvocal areas of vocal learners and vocal nonlearners. Our results suggest that evolution of vocal learning was accompanied by differential expression of a conserved gene family for synaptic transmission and plasticity in vocal nuclei. They also suggest that neural activity and signal transduction in vocal nuclei of vocal learners will be different relative to the surrounding brain areas.

Exceptional cellular resistance to oxidative damage in long-lived birds requires active gene expression.

Previous studies indicated that renal tubular epithelial cells from some long-lived avian species exhibit robust and/or unique protective mechanisms against oxidative stress relative to murine cells. Here we extend these studies to investigate the response of primary embryonic fibroblast-like cells to oxidative challenge in long- and short-lived avian species (budgerigar, Melopsittacus undulatus, longevity up to 20 years, vs Japanese quail, Coturnix coturnix japonica, longevity up to 5 years) and short- and long-lived mammalian species (house mouse, Mus musculus, longevity up to 4 years vs humans, Homo sapiens, longevity up to 122 years). Under the conditions of our assay, the oxidative-damage resistance phenotype appears to be associated with exceptional longevity in avian species, but not in mammals. Furthermore, the extreme oxidative damage resistance phenotype observed in a long-lived bird requires active gene transcription and translation, suggesting that specific gene products may have evolved in long-lived birds to facilitate resistance to oxidative stress.