Parasitism of Ixodes (Multidentatus) auritulus Neumann (Acari: Ixodidae) on birds from the city of Curitiba, State of Parana, Southern Brazil.
(41/4610)
The tick-bird relationship of 56 specimens of birds (Passeriformes and Columbiformes) collected in the city of Curitiba, State of Parana, between 1990 and 1995, among which 102 specimens of Ixodes (Multidentatus) auritulus were found and analyzed. New host records were also produced including the first report of I. auritulus on a Columbiformes bird in Brazil. (+info)
Microbial impact of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus) on aquatic ecosystems.
(42/4610)
Quantitative and qualitative analyses of the intestinal bacterial flora of Canada geese and whistling swans were carried out with the finding that wild birds harbor significantly more fecal coliforms than fecal streptococci. The reverse was typical of captive and fasting birds. Neither Salmonella spp. nor Shigella spp. were isolated from 44 migratory waterfowl that were wintering in the Chesapeake Bay region. Enteropathogenic Escherichia coli were detected in seven birds. Geese eliminated 10(7) and swans 10(9) fecal coliforms per day. Results of in situ studies showed that large flocks of waterfowl can cause elevated fecal coliform densities in the water column. From the data obtained in this study, it is possible to predict the microbial impact of migratory waterfowl upon aquatic roosting sites. (+info)
Widespread accumulation of [(3)H]testosterone in the spinal cord of a wild bird with an elaborate courtship display.
(43/4610)
Elaborate courtship displays are relatively common features of the masculine reproductive behavior in birds. However, little is known about their neural and hormonal control. One bird that performs such a display is the golden-collared manakin (Manacus vitellinus) of Panamanian forests. Adult males, but not females, perform a physically intense display requiring substantial neuromuscular control of the wings and legs. We tested the hypothesis that steroid sensitivity is a property of neurons in the manakin spinal cord. Males and females were captured from active courtship leks, treated with drugs to block steroidogenesis, injected with (3)H-labeled testosterone, and the spinal cords were removed and processed for autoradiography. Sex steroid-accumulating cells were widely distributed in the spinal cords in each of six males and in one of five females. Cells, including presumptive motoneurons, reached their highest density in the ventral horns of the cervical and lumbosacral enlargements, regions associated with motor control of the wings and legs. These results suggest that neurons in the adult manakin spinal cord can express sex-steroid receptors, but do so less in females than in males. This evidence for androgen sensitivity and sexual dimorphism in the adult avian spinal cord suggests that sex steroids may control diverse behaviors in male birds in part by acting directly on the spinal neural circuits. (+info)
Carboxypeptidase D is an avian hepatitis B virus receptor.
(44/4610)
The receptor molecules for human and animal hepatitis B viruses have not been defined. Previous studies have described a 170 to 180 kDa molecule (p170 or gp180) that binds in vitro to the pre-S domain of the large envelope protein of duck hepatitis B virus (DHBV); cDNA cloning revealed the binding protein to be duck carboxypeptidase D (DCPD). In the present study, the DCPD cDNA was transfected into several nonpermissive human-, monkey-, and avian species-derived cell lines. Cells transfected with a plasmid encoding the full-length DCPD protein bound DHBV particles, whereas cells expressing truncated versions of DCPD protein that fail to bind the pre-S protein did not. The DHBV binding to DCPD-reconstituted cells was blocked by a monoclonal antibody that neutralizes DHBV infection of primary duck hepatocytes (PDH) and also by a pre-S peptide previously shown to inhibit DHBV infection of PDH. In addition to promoting virus binding, DCPD expression was associated with internalization of viral particles. The entry process was prevented by incubation of reconstituted cells with DHBV at 4 degrees C and by the addition of energy-depleting agents known to block DHBV entry into PDH. These results demonstrated that DCPD is a DHBV receptor. However, the lack of complete viral replication in DCPD-reconstituted cells suggested that additional factors are required for postentry events in immortalized cell lines. (+info)
Genetic reassortment of avian, swine, and human influenza A viruses in American pigs.
(45/4610)
In late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of North Carolina, Texas, Minnesota, and Iowa. Four viral isolates from outbreaks in different states were analyzed genetically. Genotyping and phylogenetic analyses demonstrated that the four swine viruses had emerged through two different pathways. The North Carolina isolate is the product of genetic reassortment between H3N2 human and classic swine H1N1 influenza viruses, while the others arose from reassortment of human H3N2, classic swine H1N1, and avian viral genes. The hemagglutinin genes of the four isolates were all derived from the human H3N2 virus circulating in 1995. It remains to be determined if either of these recently emerged viruses will become established in the pigs in North America and whether they will become an economic burden. (+info)
An update on safety studies of SAD B19 rabies virus vaccine in target and non-target species.
(46/4610)
SAD B19 is an attenuated vaccine virus for oral vaccination of carnivores against rabies. The safety of SAD B19 was investigated in 16 animal species by different routes of administration. During the observation period all animals given the vaccine virus, irrespective of the route of administration, did not show any clinical signs of rabies, with the exception of certain rodent species. In these animals a low residual pathogenicity was observed, however transmission of the vaccine virus to control animals was not demonstrable. No vaccine virus could be detected in the saliva of the six mammal species examined. Furthermore, the genetical stability was shown for SAD B19 through passaging in neural tissue of dogs, foxes and mice. From the results presented here on innocuity and stability, it can be concluded that SAD B19 rabies vaccine is suitable for oral vaccination campaigns for carnivores against rabies. (+info)
A trade-off between energy intake and exposure to parasites in oystercatchers feeding on a bivalve mollusc.
(47/4610)
Models of animal dispersion between habitat patches that differ in resource density assume that animals maximize their fitness by maximizing the rate at which they consume resources. How valid is this assumption? Studies on wading birds have been central to the application of dispersion models to predator-prey systems. However, these birds do not always attempt to maximize their rate of energy intake, implying that maximization involves costs as well as benefits. Overwintering oystercatchers feeding on cockles in the Burry Inlet, South Wales, do not consume the larger more energetically profitable cockles even though consuming these prey would increase their rate of energy intake. This paper tests the hypothesis that maximizing energy intake involves a trade-off with exposure to helminth parasites. Cockles are important intermediate hosts for helminth parasites, for which oystercatchers are the definitive host. The helminth intensity of cockles increased significantly with cockle size. A functional response model was used to examine how size selection by the birds influenced energy intake and the ingestion rate of parasites. To maximize energy intake birds should selectively consume the larger size classes, but to minimize the ingestion rate of parasites they should consume the smallest size classes. In the wild, birds selectively consumed intermediate size classes, which could represent a compromise between these conflicting demands. The implications for animal dispersion models are discussed. (+info)
Directional acoustic radiation in the strut display of male sage grouse Centrocercus urophasianus.
(48/4610)
We present evidence that the acoustic component of the strut display of male sage grouse Centrocercus urophasianus is highly directional and that the nature of this directionality is unique among measured vertebrates. Where vertebrate acoustic signals have been found to be directional, they are most intense anteriorly and are bilaterally symmetrical. Our results show that sage grouse acoustic radiation (beam) patterns are often asymmetric about the birds' anterior-posterior axis. The beam pattern of the 'whistle' note is actually strikingly bilobate with a deep null directly in front of the displaying bird. While the sage grouse display serves to attract potential mates, male sage grouse rarely face females head on when they call. The results of this study suggest that males may reach females with a high-intensity signal despite their preference for an oblique display posture relative to those females. We characterized these patterns using a novel technique that allowed us to map acoustic radiation patterns of unrestrained animals calling in the wild. Using an eight-microphone array, our technique integrates acoustic localization with synchronous pressure-field measurements while controlling for small-scale environmental variation in sound propagation. (+info)