27 resultados para Juifs. 1729, dossier Worms

em University of Queensland eSpace - Australia


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Glow-worms are the larvae of a fly from the family Keroplatidae. Their closest relatives are the “fungus flies” that seek out mushrooms for their larvae to consume. Glow-worms have gone out on an evolutionary limb, albeit a successful one. They have lost their association with fungi and have instead become carnivorous. The unique feature of glow-worms is their ability to bioluminesce—to produce light.

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nsect-based tourism mainly caters to a niche market, but its popularity has been growing in recent years. Despite its popularity this form of tourism has remained under-researched and in a sense its contribution to the tourism industry has gone mostly unnoticed. This paper reports the results of a study undertaken on one form of popular insect-based tourism, namely glow worms. The study was undertaken in Springbrook National Park (Natural Bridge section) southeast Queensland, which has one of the largest glow worm colonies in Australia that attracts thousands of visitors each year. A study of this form of tourism is important and useful for several reasons. It is important to understand this hitherto under-studied tourism activity to determine the type of visitors, their socio-economic attributes, economic benefits to the local economy, visitors’ knowledge of glow worms, education imparted, visitor satisfaction of glow worm viewing and visitor attitudes for the introduction of a user fee system to view glow worms. An understanding of these issues could not only help to better manage this valuable biological resource, but can be used to develop the industry to cater to a growing number of visitors. Tourism in glow worms can potentially be used not only to educate the public on the threats affecting glow worms and their colonies, but could also be used to conserve them. Lessons learnt from glow worms as an attraction to Springbrook National Park can be used to better manage and further develop other existing and new glow worm sites in Australia and elsewhere for tourism. Furthermore, it could provide some guidance for the management and development of other forms of current insect-based tourism activities (eg. butterflies) and develop new tourism ventures based on species such as stick insects and jewel beetles for which Australia is well known (Reader’s Digest, 1997)

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Human and animal infection rates with the Oriental schistosome have steadily declined in China over the last half-century, but the Three Gorges Dam may reverse this decline by creating new, or enlarging existing, ideal environments for the worm and its aquatic snail intermediate host.

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While our understanding of lipid microdomains has advanced in recent years, many aspects of their formation and dynamics are still unclear. In particular, the molecular determinants that facilitate the partitioning of integral membrane proteins into lipid raft domains are yet to be clarified. This review focuses on a family of raft-associated integral membrane proteins, termed flotillins, which belongs to a larger class of integral membrane proteins that carry an evolutionarily conserved domain called the prohibitin homology (PHB) domain. A number of studies now suggest that eucaryotic proteins carrying this domain have affinity for lipid raft domains. The PHB domain is carried by a diverse array of proteins including stomatin, podocin, the archetypal PHB protein, prohibitin, lower eucaryotic proteins such as the Dictyostelium discoideum proteins vacuolin A and vacuolin B and the Caenorhabditis elegans proteins unc-1, unc-24 and mec-2. The presence of this domain in some procaryotic proteins suggests that the PHB domain may constitute a primordial lipid recognition motif. Recent work has provided new insights into the trafficking and targeting of flotillin and other PHB domain proteins. While the function of this large family of proteins remains unclear, studies of the C. elegans PHB proteins suggest possible links to a class of volatile anaesthetics raising the possibility that these lipophilic agents could influence lipid raft domains. This review will discuss recent insights into the cell biology of flotillins and the large family of evolutionarily conserved PHB domain proteins.

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A meeting was convened in Canberra, Australia, at the request of the Australian Drug Evaluation Committee (ADEC), on December 3-4, 1997 to discuss the role of population pharmacokinetics and pharmacodynamics in drug evaluation and development. The ADEC was particularly concerned about registration of drugs in the pediatric age group. The population approach could be used more often than is currently the case in pharmacokinetic and pharmacodynamic studies to provide valuable information for the safe and effective use of drugs in neonates, infants, and children. The meeting ultimately broadened to include discussion about other subgroups. The main conclusions of the meeting were: 1. The population approach, pharmacokinetic and pharmacodynamic analysis, is a valuable tool both for drug registration purposes and for optimal dosing of drugs in specific groups of patients, 2. Population pharmacokinetic and pharmacodynamic studies are able to fill in the gaps' in registration of drugs, for example, to provide information on optimal pediatric dosing. Such studies provide a basis for enhancing product information to improve rational prescribing, 3. Expertise is required to perform the population studies and expertise, with a clinical perspective, is also required to evaluate such studies if they are to be submitted as part of a drug registration dossier Such expertise is available in the Australasian region and is increasing. Centers of excellence with the appropriate expertise to advise and assist should be encouraged to develop and grow in the region, 4. The use of the population approach by the pharmaceutical industry needs to be encouraged to provide valuable information not obtainable by other techniques. The acceptance of population pharmacokinetic and pharmacodynamic analyses by regulatory agencies also needs to be encouraged, and 5. Development of the population approach to pharmacokinetics and pharmacodynamics is needed from a public health perspective to ensure that all available information is collected and used to improve the way drugs are used. This important endeavor needs funding and support at the local and international levels.

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Seventy-two epaulette sharks, Hemiscyllium ocellatum (Bonnaterre), were infected with the nematode parasite Proleptus australis Bayliss, 1933. The parasite population was overdispersed. Infection intensity ranged from 3 to 1002 worms per fish stomach, and there was a positive correlation between shark length and number of parasites present. The majority of worms were attached to the stomach wall, and scanning electron microscopy and histological examination showed that worms penetrated the stomach lining. Worms were observed within the lamina propria of the stomach and occasionally penetrated the muscularis mucosa. Little to no inflammatory or cellular immune reaction to the presence of the parasites was observed, except in one case where a worm was being degraded by a host tissue response. There was a large amount of connective tissue proliferation as a result of nematode attachment,, but no obvious effects on the overall health of the sharks were seen. Three sharks were also found to be infected by the cestode Callitetrarhynchus sp.

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The diet and feeding habits of the epaulette shark, Hemiscyllium ocellatum, were investigated through stomach content analysis. Five groups of prey items were found. The index of relative importance showed worms and crabs,to be of greatest value at 51.3% and 40.1% respectively. The three minor prey groups were shrimps (7.7%), small fishes (0.7%) and amphipods (0.3%). Epaulette sharks tend to be crepuscular, although feeding bouts may occur at any time. They appear to be opportunistic predators, using olfaction and electroreception in prey capture. This species appears to be an important benthic predator in the reef flat environment on Heron Island Reef.

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Closantel binds to the serum proteins of the host and affects blood sucking parasites when they ingest the brood of treated hosts. Closantel binds specifically to ovine serum albumin (K-a of 9.3 x 10(6)M(-1)) at site I, the warfarin/phenylbutazone binding site of albumin Closantel also binds to invertebrate haemocyanin and haemolymph. The strongest binding of closantel in homogenates of H. contortus is found in fractions containing soluble proteins. This binding is of low affinity and, because the site itself is not fully denaturable, it may not be proteinaceous. There is no detectable difference in binding affinity between homogenate fractions from closantel susceptible and resistant isolates of adult or larval worms suggesting that closantel resistance is not due to changes in the closantel receptor or carrier. (C) 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.

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Several heteracanthocephalid specimens were recovered from the flatfish Rhombosolea leporina (Gunther), a host of Heteracanthocephalus peltorhamphi (Baylis, 1944) Petrochenko, 1956 from New Zealand. Unlike H. peltorhamphi, these new specimens have trunk spines. Measurements and proboscis armament of the new specimens are consistent with the worms being Aspersentis minor Edmonds & Smales, 1992 originally described from the Australian flounder Rhombosolea tapirina Gunther. A review of the family Heteracanthocephalidae Petrochenko, 1956 was undertaken to assess the validity of its four genera and eight species. The validity of Aspersentis megarhynchus (Linstow, 1892) Golvan, 1960 (syn. Echinorhynchus megarhynchus Linstow, 1892) is questioned. E. megarhynchus is not considered to be an heteracanthocephalid and is relegated to a species inquirenda. A. megarhynchus (Linstow, 1892) of Golvan (1960) nec E. megarhynchus Linstow, 1892 is considered a synonym of A. austrinus Van Cleave, 1929. The monotypic genus Heteracanthocephalus Petrochenko, 1956 is proposed as a synonym of Aspersentis Van Cleave, 1929 because there appear to be insufficient morphological differences between them. Aspersentis peltorhamphi n. comb. is proposed for Heteracanthocephalus peltorhamphi. The monotypic genus Sachalinorhynchus Krotov & Petrochenko in Petrochenko, 1956 is considered valid, but the other heteracanthocephalid genus, Bullockrhynchus Chandra, Rao & Shyamasundari, 1985, also monotypic, is not. B. indicus Chandra, Rao & Shyamasundari, 1985 possesses more features resembling rhadinorhynchids than heteracanthocephalids but only females are known, and therefore the genus and species cannot be placed. There are currently four valid species of Aspersentis and one of Sachalinorhynchus.

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Closantel is an anthe lmintic which associates with plasma albumin and is useful for the control of sheep parasites, such as Haemonchus contortus, that ingest blood. However, the utility of closantel for parasite control has been threatened by the emergence of resistance. The mechanisms of resistance are unknown. A closantel-resistant and a closantel-susceptible isolate of H. contortus were compared with respect to the distribution and metabolism of closantel. Neither strain appeared to metabolise closantel in vitro or in vivo. Following treatment of infected sheep with radioactively labelled closantel, isotope levels in closantel-resistant adult H. contortus were significantly lower than in susceptible worms. This reduced accumulation of drug could contribute to closantel resistance by mechanisms such as reduced feeding, failure to dissociate the drug-albumin complex in the gut or increased efflux of closantel from resistant worms. (C) 1997 Australian Society for Parasitology.

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This study continues the collection of data on the anterior adhesive areas and secretions of monopisthocotylean monogenean (flatworm) parasites and begins an investigation of their phylogenetic usefulness. Here, two species of parasitic worms from an elasmobranch, Troglocephalus rhinobatidis (Monocotylidae: Dasybatotreminae) and Neoheterocotyle rhinobatidis (Monocotylidae: Heterocotylinae), are compared and contrasted. It has been suggested in recent literature that these two taxa are more closely related than is currently recognised. Our data support this view. Both species have multiple apertures on the ventral anterior margin through which adhesive is secreted. Two types of secretion exit from multiple adjacent duct endings terminating in each aperture: rod-shaped (S1) and spherical-shaped (S2) bodies. S1 bodies of both species show nano-banding of similar size and are membrane bound. Ultrastructure of the glands, ducts, duct endings and secreted adhesive is similar for both species, but aperture shape differs. Away from the adhesive areas, tegumental inclusions are found to differ between the two species and another, apparently non-adhesive, secretion is found in N. rhinobatidis.