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Goose parvovirus--an autonomous member of the dependovirus genus?

Goose parvovirus is the etiological agent of Derzsy's disease, a fatal hepatitis of young geese. The virus infects geese and Muscovy ducks and can be propagated in the laboratory in primary embryonic goose fibroblasts. To date the virus has only been classified by morphological, biochemical, and culture characteristics as an autonomous parvovirus. We now report the cloning and partial sequencing of 3434 nucleotides of the viral genome. Three overlapping clones were obtained, encoding regions in the nonstructural and capsid coding region. The nucleotide sequence show little homology to other autonomous parvoviruses but 55% homology to the dependovirus AAV2. The homology to AAV2 was also confirmed at the amino acid level (nonstructural protein 55%, capsid coding region 51%). DNA cross hybridization studies indicate an even closer similarity of goose parvovirus to the yet unsequenced human dependoviruses AAV1 and AAV3 than to AAV2. These findings suggest that goose parvovirus may be genetically related to the dependovirus genus rather than to the other autonomous parvoviruses.

Amino Acid Sequence↗

Are avian intrapulmonary CO2 receptors chemically modulated mechanoreceptors or chemoreceptors?

Openings of paleopulmonic parabronchi in paralyzed, unidirectionally ventilated geese were photographed through small holes in the birds' mediodorsal secondary bronchi during single-unit recording from intrapulmonary CO2 receptors. Changes in the discharge frequency of the receptors as fractional CO2 concentration of ventilating gas was alternated between 0 and 0.05 were compared with the changes in cross-sectional areas of randomly selected parabronchial lumina. Intrapulmonary CO2 receptors, similar to those found in other avian species, are also present in geese. Changes in intrapulmonary CO2 concentration greatly influenced the discharge of these receptors but did not induce movement of parabronchial smooth muscle in this region of the lung. If most of the receptors are located in the paleopulmonic parabronchi, as currently appears to be the case, we must conclude that changes in receptor discharge in response to changes in intrapulmonary CO2 concentration do not result from mechanical distortion of the receptors induced by smooth muscle contraction; intrapulmonary CO2 receptors appear to be true chemoreceptors.

Action Potentials↗

Oxygen transport during progressive hypoxia in high-altitude and sea-level waterfowl.

Under conditions of progressive hypoxia, oxygen transport was compared in bar-headed geese (Anser indicus), a species which breeds on the Tibetan Plateau and migrates at altitudes up to 9200 m, and Pekin ducks (Anas platyrhynchos, forma domestica), a similarly sized, sea-level water fowl that does not fly. Pekin ducks showed no altitude-induced behavioral effects (e.g., restlessness) up to 7620 m, while bar-headed geese tolerated 10,668 m with no observable behavioral changes. Ventilatory and cardiac responses to hypoxia as functions of PaO2 followed a typical hyperbolic contour, but the response began at almost 20 Torr lower in the bar-headed goose. Both ventilation and cardiac output appeared to follow a common response curve for the two species, when the independent variable was expressed as arterial oxygen content. The goose had a high oxygen affinity hemoglobin, compared with the duck; the oxyhemoglobin curves of both shifted slightly to the right as a result of acclimation to 5640 m; but only the duck developed erythrocytosis as a consequence of acclimation. Under sea level conditions the duck maintained a higher mixed venous PO2, but with acute hypoxic exposures PVO2 was higher in the goose. Following acclimation, cardiac output in the duck was lower than in pre-acclimatized state, but in the goose it was higher up to the altitude at which it migrates. The selective pressures leading to the evolution of favorable oxygen transport in the bar-headed goose are discussed.

Adaptation, Physiological↗

Ventilatory and intrapulmonary chemoreceptor sensitivity to CO2 in the burrowing owl.

We measured the ventilatory response of anesthetized, unidirectionally ventilated pigeons and burrowing owls to changes in intrapulmonary CO2 concentration and the static CO2 sensitivity of intrapulmonary chemoreceptors (IPC) in these species and the domestic goose. Compared with pigeons, burrowing owls showed a significantly reduced respiratory frequency and amplitude response to increases in FICO2 from 0.05 to 0.10, which corroborates similar findings in intact, awake individuals of the same species. The average static CO2 sensitivity of IPC in geese, pigeons, and burrowing owls, as reflected by the average slope of the linear regressions of receptor discharge frequency on ln(PICO2), was -7.96, -11.1 and -6.87 imp/sec . ln(PICO2), respectively. The sensitivities of individual receptors were normally distributed in geese and pigeons, but skewed in burrowing owls. Therefore, the median CO2 sensitivity [-5.50 imp/sec . ln(PICO2)] is a more appropriate measure of the typical CO2 sensitivity of IPC in burrowing owls. The static CO2 sensitivity of IPC in burrowing owls is the lowest reported for euthermic birds with a normal acid-base balance and may materially contribute to the blunted ventilatory response of these birds to the elevated CO2 levels they encounter in nature.

Animals↗

A goose head holder device for chronic experiments.

A special device is described which allows experiments to be performed on chronic non-anaesthetized geese. This system is composed of two elements: one is fixed to the stereotaxic apparatus, the other is implanted on the goose skull. The use of ear bars and eye and bill pieces is thus eliminated. This non-painful adaptation is well tolerated by the bird. In addition, the position of the animal with regard to stereotaxic coordinates is unchanged. This technique provides an essential tool for furthering investigations on the central nervous system in geese.

Animals↗

Generation of virus-like particles consisting of the major capsid protein VP1 of goose hemorrhagic polyomavirus and their application in serological tests.

Goose hemorrhagic polyomavirus (GHPV) is the causative agent of hemorrhagic nephritis and enteritis of geese (HNEG), a fatal disease of young geese with high mortality rates. GHPV cannot be efficiently propagated in tissue culture. To provide antigens for diagnostic tests and vaccines, its major structural protein VP1 was recombinantly expressed in Sf9 insect cells and in the yeast Saccharomyces cerevisiae. As demonstrated by density gradient centrifugation and electron microscopy, GHPV-VP1 expressed in insect cells formed virus-like particles (VLPs) with a diameter of 45 nm indistinguishable from infectious polyomavirus particles. However, efficiency of VLP formation was low as compared to the monkey polyomavirus SV-40-VP1. In yeast cells, GHPV-VP1 alone formed smaller VLPs, 20 nm in diameter. Remarkably, co-expression of GHPV-VP2 resulted in VLPs with a diameter of 45 nm. All three types of GHPV-VLPs were shown to hemagglutinate chicken erythrocytes. ELISA and hemagglutination inhibition tests using the VLPs as antigen detected GHPV-specific antibodies in up to 85.7% of sera derived from flocks with HNEG but in none of the sera of a clinically healthy flock. However, GHPV-specific antibodies were also detected in sera from two other flocks without HNEG indicating a broad distribution of GHPV due to subclinical or unrecognised infections.

Animals↗

Role of hepatic lipogenesis in the susceptibility to fatty liver in the goose (Anser anser).

In response to overfeeding, the Landes goose develops a fatty liver that is twice as large as that of the Poland goose, despite similar food intake. The role of hepatic lipogenesis in the genetic susceptibility to fatty liver was assessed in male overfed geese of the two breeds. For a similar hepatic protein content, total activities of malic enzyme, glucose-6-phosphate dehydrogenase, acetyl-Coa-carboxylase and fatty acid synthase, and specific activity and mRNA level of malic enzyme were about two-fold higher in the Landes goose. In the Poland goose, the weight of the fatty liver was correlated positively with the specific activity of ME and the VLDL concentration, which was not the case in the Landes breed. These results show that: (1) hepatic lipogenesis remains very active until the end of the overfeeding period; (2) the pentose-phosphate pathway may function in birds, contrary to what is assumed usually; (3) the level of hepatic lipogenesis is a major factor in the susceptibility to hepatic steatosis in different breeds of geese; and (4) ME activity may be a limiting factor of lipid synthesis in the less susceptible Poland breed.

Acetyl-CoA Carboxylase↗

Determination of 4,4'-dinitrocarbanilide (DNC), a component of Nicarbazin, in Canada goose (Branta canadensis) eggshells using high-performance liquid chromatography.

A method was developed using high-performance liquid chromatography to assay 4,4'-dinitrocarbanilide (DNC), the active ingredient in Nicarbazin, in eggshells collected from Canada geese fed a formulated feed fortified with Nicarbazin at doses of 0, 125, 250, and 500 microg/g. The method was developed using chicken eggshells fortified with DNC. The method was used to quantify DNC in both the shell-associated membranes and the calcified shell extracellular matrix. These values were compared to those obtained for a composite sample consisting of both the membranes and the calcified shell extracellular matrix. The validated method was used to quantify DNC in eggshells from geese fed fortified feed to ascertain the effect of Nicarbazin feed concentration on shell DNC concentration. DNC levels in the eggshells were highly correlated with feed dose.

Animal Feed↗

Pathology of spontaneous and experimental infections by Goose haemorrhagic polyomavirus.

Haemorrhagic nephritis enteritis of geese (HNEG) is a fatal disease of geese aged from 3 to 12 weeks. The causative virus, Goose haemorrhagic polyomavirus (GHPV), is a member of the Polyomaviridae family We examined goslings either spontaneously or experimentally infected with GHPV. Tissues were sampled for histology, GHPV DNA detection and electron microscopy. Clinical signs and gross lesions observed in experimentally infected goslings were largely consistent with those noticed in field cases. Histological examination showed that, in the acute phase of HNEG, GHPV replicates in almost all the tissues with a particular tropism for endothelial and lymphoid cells. Haemorrhagic foci were widespread in many tissues, including brain. Ultrastructural features were largely consistent with other polyomavirus infections, with accumulation of virions in the nucleus. Non-typical, double-membraned organelles were observed in the cytoplasm. GHPV DNA distribution was widespread in tissues of infected birds, from day 5 post-infection. GHPV therefore induces a systemic disease in its host, leading to severe vascular dysfunction and immunosuppressive B-cell depletion.

Animals↗

Serological diagnosis of goose circovirus infections.

Infections with goose circovirus (GoCV) are associated with growth retardation and developmental problems in farmed geese. An indirect immunofluorescence assay for detecting virus-specific serum antibody was developed for diagnostic and epidemiological purposes. In the absence of a method for growing GoCV in cell culture, the assay was based on the reaction of antibodies with the GoCV capsid protein produced within baby hamster kidney cells using the eukaryotic Semliki forest virus expression vector. Using an optimized test that involved screening sera at 1:50 dilution and the use of a fluorescein isothiocyanate anti-duck immunoglobulin conjugate, GoCV-specific antibody was detected in 141 (88.6%) of 159 samples obtained from 27 of 28 breeder flocks aged from 1 to 6 years. Testing also showed the presence of GoCV-specific antibody in 85 (40.9%) of 208 serum samples from birds aged 30 weeks or less. Although maternally derived antibody was detected in birds when 1 and 4 days old, actively acquired antibody was first detected in birds aged 53 days. Following experimental inoculation of 21-day-old geese with tissue homogenate containing GoCV, virus-specific antibody was detected in serum samples collected at 27 and 34 days post inoculation. It is concluded that the SFV expression vector approach may prove useful for developing serological tests for other viruses, including other avian circoviruses, that do not grow in cell culture.

Animals↗

A live attenuated West Nile virus strain as a potential veterinary vaccine.

This article reviews the development of two attenuated West Nile virus (WNV) variants, WNI-25 and WNI-25A. These variants have lost the neuroinvasion trait of the parental virus. Attenuation was achieved through serial passages in mosquito cells and neutralization escape from WNV-specific monoclonal antibody. Genetic analysis reveals amino acid changes between the parental and each of the variants. The attenuated variants preserve the ability to replicate in mice and geese and to induce a protective immune response. WNI-25A was found to be a genetically stable virus. This variant was successfully used as a live vaccine to protect geese against a wild-type virulent WNV field isolate that closely resembles the WNV isolated during the 1999 New York epidemic.

Animals↗

Effects of electrical stunning frequency and voltage combinations on the presence of engorged blood vessels in goose liver.

The purpose of this study was to investigate the influence of nine electrical stunning methods using various frequency and voltage combinations on the occurrence of engorged blood vessels in goose liver. Two hundred seventy Gourmaud geese (liver-type line SI 14) were slaughtered at 12 wk of age, in groups of 90 at three different times. Thirty birds each were subjected to one of the nine stunning methods. Neck cutting was performed immediately after stunning. The duration of exsanguination was 11 min. After completion of bleeding, the birds were scalded, defeathered manually, and kept refrigerated. At 1 d postmortem, the carcasses were eviscerated and cut up. From the slaughterhouse, the livers chilled in ice were transported to the cannery where they were weighed and graded at 2 d postmortem and were further processed. All of the veins and capillaries full of blood were removed from livers, because their presence was a hazard to product quality by causing discoloration of the canned liver, and the percentage of liver weight loss was then determined. The loss in liver weight due to removal of engorged blood vessels was reduced (P < 0.05) at 350 Hz, 70 to 90 V, and 80 to 85 mA when compared to the results obtained with any other stunning method tested. It was concluded that the use of high-frequency currents for electrical stunning of liver geese might have considerable commercial advantages.

Animals↗

Effect of method of delivering nicarbazin to mallards on plasma 4,4'-dinitrocarbanilide levels and reproduction.

Nicarbazin (NCZ), a coccidiostat used in the poultry industry, has been developed as a contraceptive for resident Canada geese. We tested the efficacy of NCZ as a contraceptive using mallards (Anas platyrhynchos) as a model for Canada geese. Nicarbazin-treated corn was fed ad libitum for 14 d at 0, 750, 1,000, or 1,500 ppm. Plasma and egg levels of 4,4'-dinitrocarbanilide (DNC), the active anticoccidial component of NCZ, differed among treatment groups in a dose-response relationship, but plasma levels did not differ between sexes. Nicarbazin caused a decrease in egg weight, but there was no effect of NCZ on the numbers of eggs laid per female per day. Nicarbazin did not significantly impact bird health. An additional trial tested the effect of the method of NCZ delivery on plasma DNC levels. Mallards were given NCZ daily for 12 d either by gavage with a corn oil suspension, gavage with a water suspension, peroral administration of a capsule, or feeding 500 mg of NCZ/kg of pelleted feed ad libitum. The method of delivery significantly affected plasma DNC levels, with the highest levels in the corn oil suspension group and the lowest levels in the pelleted feed group. This is likely due to decreased availability of NCZ in a pellet compared with gavage with a suspension or capsule. Mallards receiving 34.2 mg of NCZ/kg of BW when fed cracked corn coated with NCZ daily for 14 d had higher plasma DNC levels than those obtained by liquid gavage, capsule, or pelleted NCZ feed. For maximum effect in the field, NCZ should be coated onto corn. A higher concentration of NCZ is needed in pelleted feed to obtain comparable plasma DNC levels to allow for the decreased absorption of DNC.

Animals↗

Avian collision risk at an offshore wind farm.

We have been the first to investigate whether long-lived geese and ducks can detect and avoid a large offshore wind farm by tracking their diurnal migration patterns with radar. We found that the percentage of flocks entering the wind farm area decreased significantly (by a factor 4.5) from pre-construction to initial operation. At night, migrating flocks were more prone to enter the wind farm but counteracted the higher risk of collision in the dark by increasing their distance from individual turbines and flying in the corridors between turbines. Overall, less than 1% of the ducks and geese migrated close enough to the turbines to be at any risk of collision.

Accident Prevention↗

Estimates of relatedness and inbreeding in goose strains from DNA fingerprints.

The purpose of this study was to determine if DNA fingerprints (DFPs) could be used to estimate relatedness and inbreeding of strains of geese and to compare three methods of calculating relatedness indices. Strains included a control and selected strain from each of the Chinese and Synthetic (Chinese, Hungarian and Pilgrim) breeds. DFP patterns for each strain were based on individual DNA samples from six females, or on pooled DNA from 15 females different from those used for individual samples. Three relatedness indices were used, namely, genetic distance, modified Rogers distance and band sharing. All relatedness indices showed a closer relationship of strains within than between breeds. Correlation coefficients among relatedness indices were higher based on pooled DNA (r > or = magnitude of 0.97) than those based on individual DNA (r > or = magnitude of 0.741). Inbreeding estimates were higher for selected compared with control strains. It appears that the use of DFPs to estimate relatedness, regardless of index used, and inbreeding can be valuable for studying geese where there is a limited breeding history.

Animals↗

Conserved genetic basis of a quantitative plumage trait involved in mate choice.

A key question in evolutionary genetics is whether shared genetic mechanisms underlie the independent evolution of similar phenotypes across phylogenetically divergent lineages. Here we show that in two classic examples of melanic plumage polymorphisms in birds, lesser snow geese (Anser c. caerulescens) and arctic skuas (Stercorarius parasiticus), melanism is perfectly associated with variation in the melanocortin-1 receptor (MC1R) gene. In both species, the degree of melanism correlates with the number of copies of variant MC1R alleles. Phylogenetic reconstructions of variant MC1R alleles in geese and skuas show that melanism is a derived trait that evolved in the Pleistocene.

Animals↗

Development of goose- and duck-specific DNA markers to determine sources of Escherichia coli in waterways.

The contamination of waterways with fecal material is a persistent threat to public health. Identification of the sources of fecal contamination is a vital component for abatement strategies and for determination of total maximum daily loads. While phenotypic and genotypic techniques have been used to determine potential sources of fecal bacteria in surface waters, most methods require construction of large known-source libraries, and they often fail to adequately differentiate among environmental isolates originating from different animal sources. In this study, we used pooled genomic tester and driver DNAs in suppression subtractive hybridizations to enrich for host source-specific DNA markers for Escherichia coli originating from locally isolated geese. Seven markers were identified. When used as probes in colony hybridization studies, the combined marker DNAs identified 76% of the goose isolates tested and cross-hybridized, on average, with 5% of the human E. coli strains and with less than 10% of the strains obtained from other animal hosts. In addition, the combined probes identified 73% of the duck isolates examined, suggesting that they may be useful for determining the contribution of waterfowl to fecal contamination. However, the hybridization probes reacted mainly with E. coli isolates obtained from geese in the upper midwestern United States, indicating that there is regional specificity of the markers identified. Coupled with high-throughput, automated macro- and microarray screening, these markers may provide a quantitative, cost-effective, and accurate library-independent method for determining the sources of genetically diverse E. coli strains for use in source-tracking studies. However, future efforts to generate DNA markers specific for E. coli must include isolates obtained from geographically diverse animal hosts.

Animals↗

Avian reservoirs and zoonotic potential of the emerging human pathogen Helicobacter canadensis.

A polyphasic identification approach was used to investigate the taxonomic position of Campylobacter-like isolates recovered from barnacle geese (Branta leucopsis) and Canada geese (Branta candensis). Seven strains were selected from a collection of 21 isolates and analyzed by extensive phenotypic testing; four strains were characterized by 16S rRNA gene sequence analysis. The results clearly identified the bird isolates as Helicobacter canadensis, recently described as an emerging human pathogen. This is the first report of an animal reservoir for this organism and of its presence in Europe and confirms the zoonotic potential of H. canadensis.

Animals↗