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PubMed1995

Polymorphism of blood plasma proteins in the Anser and Branta genera.

An electrophoretical analysis of blood plasma proteins of eight Anser and two Branta species was performed. Ten polymorphic proteins in blood plasma pattern were distinguished and described: four prealbumin proteins, albumin, three postalbumin proteins, transferrin, and a single posttransferrin protein. Genus-specific and species-specific variants of Pr-1, Al, Pa-3, Pa-X, and Tf proteins were found. The species of Branta differed in Pr-1, Pa-3, Pa-X, and Tf loci. The Anser species differed, apparently, in allele frequencies of described gene loci. A single species-specific protein marker was found in swan geese only. The electrophoretic mobilities of Pr-1, TfB, and PtfA, B, and C were similar for several species of Anser and Branta genera.

Alleles↗
PubMed1981

Fine structural study of Eimeria truncata from the domestic goose (Anser anser dom.).

Eimeria truncata oocysts were isolated from a naturally infected goose stock. Domestic geese and ducks were inoculated with sporulated oocysts. Meronts, merozoites, macro- and microgamonts, and microgametes were studied with the light and electron microscope. These stages were located in the epithelial cells of the kidney tubules only. The meronts and merozoites showed the characteristic fine structures of Eimeria species. The macrogamonts only possessed one type of wall-forming bodies. It resembled the wall-forming bodies type I of other Eimeria species. One of the most prominent observations seemed to be the occurrence of osmiophilic granular material in the parasitophorous vacuoles of all endogenous stages of E. truncata.

Animals↗
PubMed2003

Feedback dynamics of grazing lawns: coupling vegetation change with animal growth.

We studied the effects of grazing by Black Brant (Branta bernicla nigricans) geese (hereafter Brant) on plant community zonation and gosling growth between 1987 and 2000 at a nesting colony in southwestern Alaska. The preferred forage of Brant, Carex subspathacea, is only found as a grazing lawn. An alternate forage species, C. ramenskii, exists primarily as meadow but also forms grazing lawns when heavily grazed. We mowed plots of ungrazed C. ramenskii meadows to create swards that Brant could select and maintain as grazing lawns. Fecal counts were higher on mowed plots than on control plots in the year after plots were mowed. Both nutritional quality and aboveground biomass of C. ramenskii in mowed plots were similar to that of C. subspathacea grazing lawns. The areal extent of grazing lawns depends in part on the population size of Brant. High Brant populations can increase the areal extent of grazing lawns, which favors the growth of goslings. Grazing lawns increased from 3% to 8% of surface area as the areal extent of C. ramenskii meadows declined between 1991 and 1999. Gosling mass was lower early in this time period due to density dependent effects. As the goose population stabilized, and area of grazing lawns increased, gosling mass increased between 1993 and 1999. Because larger goslings have increased survival, higher probability of breeding, and higher fecundity, herbivore-mediated changes in the distribution grazing lawn extent may result in a numerical increase of the population within the next two decades.

Alaska↗
PubMed2004

Herbivory and competition slow down invasion of a tall grass along a productivity gradient.

Competition models including competition for light predict that small plant species preferred by herbivores will be outshaded by taller unpreferred plant species with increasing productivity. When the tall plant species is little grazed by the herbivores, it can easily invade and dominate short vegetation. The tall-growing grass Elymus athericus dominates the highly productive stages of a salt-marsh succession in Schiermonnikoog and is not preferred by the herbivores which occur there, hares and geese. We studied how interspecific competition and herbivory affected performance during early establishment of this species with increasing productivity. Seedlings were planted in the field in a full factorial design, manipulating both interspecific competition and herbivory. The experiment was replicated along a natural productivity gradient. Competition reduced above-ground biomass production and decreased the number of ramets that were produced but did not affect survival of seedlings. The negative effects of competition on seedling performance increased with increasing productivity. In contrast to our expectations, herbivory strongly reduced seedling survival, especially at the unproductive sites and had only small effects on seedling growth. The present study shows that unpreferred tall-growing species cannot easily invade vegetation composed of short preferred species. Grazing by (intermediate-sized) herbivores can prevent establishment at unproductive sites, and increased competition can prevent a rapid invasion of highly productive sites. Herbivores can have a long-lasting impact on vegetation succession by preventing the establishment of tall-growing species, such as E. athericus, in a window of opportunity at young unproductive successional stages.

Adaptation, Physiological↗
PubMed2005

The goose reovirus genome segment encoding the minor outer capsid protein, sigma1/sigmaC, is bicistronic and shares structural similarities with its counterpart in Muscovy duck reovirus.

Reoviruses have recently been shown to be associated with disease in young geese and to be involved in epizooties of severe outcome in Hungary. To assess the genetic variability among these pathogenic goose reoviruses (GRVs), we sequenced the S4 genome segment of five GRV strains isolated from different diseased flocks. We found that the GRV S4 genome segment, consisting of two partially overlapping open reading frames (ORFs), shares substantial structural similarity with its counterpart in muscovy duck reoviruses (DRVs). ORF1 is predicted to encode a polypeptide highly similar to the p10 polypeptide of DRV, and ORF2 supposedly encodes the minor outer capsid protein, sigma1/sigmaC. In one of the five GRV strains examined, we identified a single uracil base insertion close to the middle of ORF2. This insertion resulted in a frameshift and in concomitant acquisition of a termination codon (UAA) a few codons downstream, apparently causing truncation of the C-terminal part of the protein. The functional consequences of this assumed mutation, which would result in loss of more than a half of the protein, have yet to be determined. Nonetheless, the sequence and structural similarities between the genome segment encoding sigmal/sigmaC in GRVs and DRVs suggest that these viruses belong to a species distinct from other established species within subgroup 2 of orthoreoviruses.

Amino Acid Sequence↗
PubMed1987

Stimulation of the pontomedullary reticular formation initiates locomotion in decerebrate birds.

The initiation and control of spinal locomotor mechanisms by supraspinal brainstem centers has been studied in many vertebrate species. However there is very little information regarding brainstem-spinal pathways involved in avian locomotion. To undertake these studies, birds (geese or ducks) were placed in a stereotaxic frame and decerebrated under halothane anesthesia. After anesthesia was discontinued, discrete brainstem regions were electrically stimulated. Locomotion could be evoked from several areas within the pontomedullary reticular formation. The stimulus threshold for evoking walking ranged from 25-50 microA at 30-80 Hz (pulse duration 0.5 ms). At slightly higher current strengths (50-100 microA) wing flapping ('flying') was initiated. Histological examination of the stimulation sites indicated that the predominant locomotor areas were restricted to the ventromedial gigantocellular reticular formation and a more dorsolateral location within the parvocellular reticular formation. To ascertain whether neurons in these regions of the avian brainstem project directly to the spinal cord, a retrograde fluorescent tracer dye, True blue, was injected into either the cervical or low thoracic spinal cord. Comparing the positions of the retrogradely labeled neurons and the effective locomotor stimulation sites indicated a high degree of overlap. The present results, when compared with previous studies, suggest strong similarities in descending brainstem control of locomotion for all vertebrates.

Animals↗
PubMed1983

Some mechanical properties of goose femoral cortical bone.

The ultimate compressive strength and modulus of elasticity of femoral cortical bone from adult geese (Anser anser), were determined by sex and by quadrant by compressing small right circular cylinders which were 2.4 mm in height and 0.8 mm in diameter. The average ultimate compressive strength was 183 +/- 29 MPa. The average modulus of elasticity was 13.2 +/- 3.4 GPa. The bending strength and bending modulus of elasticity were determined by a three point bend test on rectangular prisms which had the approximate dimensions 0.75 mm X 0.75 mm X 25 mm. The average bending strength was 263 +/- 44 MPa while the average bending modulus was 19.6 +/- 3.1 GPa. The calcium content was determined by atomic absorption spectrophotometry and no correlation was found with the mechanical properties. The histology of the cortical bone was examined both quantitatively and qualitatively. A unique type of Haversian bone is described. Goose bone was found to be morphologically similar to adolescent human bone and to have mechanical properties similar to those of adult human bone.

Animals↗
PubMed1989

The transport and culture conditions for optimum transformation responses of wildfowl lymphocytes to mycobacterial antigens.

A method has been developed for increasing the survival of wildfowl lymphocytes during transport over considerable distances. Blood in an equal volume of heparinised RPMI was maintained at close to avian body temperature, i.e., approximately 40 degrees C. Using this system lymphocyte transformation in the presence of antigen (mycobacterial) has been successfully performed with wildfowl mononuclear cells for the first time. Duck cells were cultured in 10% autologous sera with 8 x 10(5) cells/well for 4 days. Cells from Hawaiian geese (Branta sandvicensis) required similar culture conditions but were incubated for 3 days.

Animals↗
PubMed1985

Effects of V.M.H. lesions on plasma insulin in the goose.

The effects of bilateral electrolytic lesions of the ventromedial hypothalamus (V.M.H.) were examined in male geese. In addition to the known effects (hyperphagia, obesity and liver steatosis), V.M.H. lesions slightly increased plasma insulin level in the fasting and the fed state and largely enhanced insulin levels observed during an oral glucose and amino acid load. Therefore, V.M.H. lesions potentiate insulin release which may in turn participate in the development of hyperphagia and fattening in the goose as in mammals.

Animals↗
PubMed1979

Corrections to the Hazelhoff model of airflow in the avian lung.

The ventilatory activity of the anterior and posterior groups of air sacs was simulated in unidirectionally-ventilated geese and the resultant flow of air in the mediodorsal secondary bronchi was used as an indicator of the route which air followed through the lung. The results were used to isolate the roles of the respective groups of air sacs in the shaping of the unidirectional pattern of airflow known to exist during normal respiration. Findings indicated that, in contrast to Hazelhoff's model, the anterior and not the posterior sacs are responsible for producing the caudo-cranial flow of air through the parabronchi during inspiration. The posterior sacs, as predicted by Hazelhoffs model, and primarily responsible for driving the caudo-cranial current through the parabronchi during expiration.

Air Sacs↗
PubMed1979

Observations on the avian pulmonary and bronchial circulation using labelled microspheres.

Domestic fowl, ducks, geese, Guinea-fowl, quail and pigeons were anaesthetised with intravenous pentabarbitone sodium. Carbonised microspheres (40,000-60,000), 15 micrometer +/- 5 micrometer in diameter and labelled with 85Sr (3M Company) were injected into the cannulated right atrium. After spontaneous breathing of room air the birds were killed and the radioactivity measured in the spleen, kidneys, brain, lungs and extrapulmonary primary bronchi. Small pieces of lung tissue were removed from the beginning (costal region), middle (costovertebral region), and the end (vertebral region) of the paleopulmonic parabronchi, in the direction of air flow. Microspheres found in samples of parabronchial tissue indicated the relative perfusion rates of the three regions. Thermal panting was induced in six domestic fowl and six pigeons, followed by injection of microspheres. No arteriovenous anastomoses were found to exist across the pulmonary bed in any of the species examined at rest or in the panting domestic fowl and pigeons. The extrapulmonary primary bronchus was found to be well perfused from the pulmonary artery in the domestic fowl and to a lesser extent in the other species. The perfusion of the parabronchi in the domestic fowl and pigeons at rest decreased in the direction of ventilatory gas flow. This blood flow gradient was significantly increased during thermal panting in the domestic fowl, but not in the pigeon.

Animals↗
PubMed1982

Morphometrics of the avian lung. 2. The wild mallard (Anas platyrhynchos) and graylag goose (Anser anser).

The lungs of 5 wild mallard ducks (Anas platyrhynchos) and 5 feral graylag geese (Anser anser) of mean body weight 1.04 and 3.84 kg, respectively, were fixed in situ by intratracheal infusion of 2.3% glutaraldehyde, pH 7.4 and total osmolarity 350 mOsm, at a pressure head of 25 cm, and analysed by standard morphometric techniques. The following data apply to both lungs together, in the fixed state, the first value relating to Anas and the second to Anser in each case: lung volume, 30.4 and 95.3 cm3; volume of exchange tissue, 12.32 and 38.50 cm3; volume of capillary blood, 4.06 and 12.49 cm3; surface area of blood-gas (tissue) barrier per unit body weight, 28.56 and 23.10 cm2/g; surface area of the blood-gas (tissue) barrier per unit volume of lung, 977 and 932 cm2/cm3; surface area of blood-gas (tissue) barrier per unit volume of exchange tissue, 241 and 230 mm2/mm3; harmonic mean thickness of tissue barrier, 0.133 and 0.118 microns; arithmetic mean thickness of tissue barrier, 0.903 and 0.887 microns; harmonic mean thickness of plasma layer, 0.369 and 0.322 microns; mean total morphometric pulmonary diffusing capacity per unit body weight, 3.85 and 3.59 ml O2/min/mm Hg/kg. These morphometric parameters of Anas and Anser are compared with those reported in the literature for the domestic fowl (Gallus gallus), the budgerigar (Melopsittacus undulatus), the house sparrow (Passer domesticus), and the violet-eared hummingbird (Colibri coruscans). The lungs of these six avian species show progressively advancing adaptations, from Gallus, through Anser, Anas, Melopsittacus and Passer, to Colibri, which appear to be consistent with the energetic characteristics of these birds.

Animals↗
PubMed1982

Measurement of continuous distributions of ventilation-perfusion in non-alveolar lungs.

We modified the multiple inert gas elimination technique, which was originally developed for alveolar lungs, to measure continuous distributions of V/Q in the cross-current lungs of birds. In theory, the method is also applicable to counter-current gas exchangers. The algorithms for inferring essentially continuous V/Q distributions from a limited number of measurements and the least-squares approach for dealing with experimental error are independent of the model of gas exchanger being studied. A Monte-Carlo procedure was used to predict the expected frequency of occurrence of given magnitudes of experimental error for each model. If the observed frequency distribution of error exceeds the predicted, then this indicates an incorrect choice of model (analogous to chi-square tests). Thirty-four data sets from 8 geese indicate that: (1) the assumptions of the technique are adequately met; (2) the alveolar model is not appropriate for birds, but the cross-current model is; and therefore; (3) the cross-current modification of the multiple inert gas elimination technique can be used to assess V/Q inequality in avian lungs.

Animals↗
PubMed1982

Ventilation-perfusion inequally in avian lungs.

We assessed ventilation-perfusion inequality in 8 anesthetized, tidally ventilated geese in terms of continuous V/Q distributions using the multiple inert gas elimination technique modified for cross-current avian lungs (Powell and Wagner, 1982). Thirty-four data sets were collected. Allowing for differences in solubility, high molecular weight gases (Enflurane, SF6) were not retained in the blood to any greater extent than the other gases, suggesting that diffusion in the gas phase is functionally complete. Shunt averaged only 0.4 +/- 0.1% (SEM) of cardiac output and areas of low V/Q were seldom seen. Twenty-nine of the 34 data sets had bimodal V/Q distributions with 10.6 +/- 1.4% of expired ventilation and 0.3 +/- 0.1% of cardiac output in a high V/Q mode; the physiological basis of the high mode is unknown. The log-standard deviation of the main Q mode averaged 0.56 or slightly greater than that for healthy men, dogs, or earlier estimates from unidirectionally ventilated birds. It is predicted that CO2 will be more impaired by such V/Q inequality than O2, but that increased ventilation will overcome the CO2 impairment more easily than that of O2 transport.

Animals↗
PubMed1987

Inspiratory aerodynamic valving in goose lungs depends on gas density and velocity.

The non-reversing gas flow pattern in the avian lung has been attributed to 'aerodynamic valves'. A fundamental property of all aerodynamic valves is their dependence on inertial forces in the gas stream: sufficient reduction of inertial forces will cause aerodynamic valves to fail. If valving in the avian lung is aerodynamic, it should fail when gas stream momentum is reduced. We tested the dependence of the inspiratory valves in the goose lung on gas density and gas flow velocity. A bolus of tracer gas was placed in the tracheal cannula during an end-expiratory pause. Tracer gas appearance in a cranial air sac during the following inspiration and pause was used to deduce failure of the 'inspiratory valve' in cyclically ventilated geese. Little or no tracer entered the sac under control conditions, which approximated resting breathing, indicating highly effective valving. Lower flow rate or lower gas density caused increased tracer appearance, indicating valve failure. These results demonstrate the importance of gas inertial forces to normal valve function, and are direct evidence for the aerodynamic nature of the avian inspiratory valve.

Animals↗
PubMed1978

The fine structure of granules in eosinophil leucocytes from aquatic and terrestrial birds.

The ultrastructure of eosinophil granules from various aquatic and terrestrial birds has been described. Granules of three basic types were found. The first had a crystalline internum and was found only in the order Anseriformes, which included the black-necked screamer, ducks, geese and swans. The crystals occurred in three morphological forms. The second and least common granule examined contained a non-crystalline internum which was either homogeneous or composed of microfilaments or microtubules. The largest and most common group of birds had a homogenous granule with no internum shown. Homogeneous granules occurred less frequently than did those with interna.

Animals↗
PubMed1979

Dual sites of occurrence of malonyl-CoA decarboxylase and their possible functional significance in avian tissues.

1. Uropygial glands of domestic goose and mallard which synthesize methyl-branched fatty acids, contain large quantities of cytosolic malonyl-CoA decarboxylase and a small quantity of mitochondrial enzyme. 2. Uropygial glands of chicken and the liver of geese which generate little methyl-branched acids, contain only small quantities of malonyl-CoA decarboxylase and in such cases the enzyme is in the mitochondria. 3. The mitochondrial decarboxylase from the uropygial gland and liver of goose is immunologically similar to the cytosolic decarboxylase of the uropygial gland. 4. The mitochondrial enzyme probably protects the mitochondrial enzymes which are susceptible to inhibition by malonyl-CoA, whereas the cytosolic enzyme promotes the synthesis of methyl-branched acids.

Animals↗
PubMed1979

Kidney and liver carnosinase activity and carnosine level in goose.

Activity of kidney and liver carnosinase and concentration of carnosine in leg muscles were determined for 8 weeks in old geese of three races: Italian white, Bilgoraj and Lublin. significant differences were noted between the three races with respect to all parameters under study. the following correlations were found: 1. Between live goose weight and carnosine concentration in muscles (r= 0.5276). 2. Between weight of leg muscles and carnosine level in these muscles (r=0.4912). 3. Between liver weight and carnosine level in muscles (r= 0.3292). 4. Between kidney carnosinase activity and liver carnosinase activity (r= .2104). 5. Between liver carnosinase activity and carnosine level (r= 0.2280). 6. Between kidney carnosinase activity and carnosine level (r= -0.1675). 7. Between the ratio of kidney:liver carnosinase activity and carnosine level in muscles (r =0.1816).

Animals↗