984 resultados para post-harvest conservation
Resumo:
The nature of an experiment involving 204 residents is outlined and the results are reported and analysed. Two consecutive surveys of the respondents provide data about their stated knowledge of 23 wildlife species present in tropical Australia, most of which exclusively occur there. In addition, these surveys provide data about the willingness of respondents to pay for the conservation of those species belonging to three taxa; reptiles, mammals, and birds. Thus it is possible to compare the respondents’ stated knowledge of the species with their willingness to pay for their conservation, and to draw relevant inferences from this. From the initial survey and these associations, interesting relationships can be observed between those variables (knowledge and willingness to pay). The second survey was completed after the respondents’ knowledge of the species was experimentally increased and became more balanced. This is shown to result in increased dispersion (greater discrimination) in willingness to contribute to conservation of the different species in the set of wildlife species considered. Both theoretical and policy conclusions are drawn from the results.
Resumo:
This case study concentrates on the extent of knowledge of members of the Australian public of Australia’s tropical bird species and their willingness to pay for their conservation. In order to place this issue in context, it first provides background information on the status of Australian bird species, focusing attention on species that occur in tropical Australia. Then, using survey results, this study considers the hypothesis that the public’s relative support for the conservation of different bird species depends on its comparative knowledge of their existence and status. Based on experimental results from a sample of residents of Brisbane, Queensland (Australia), it is found that their knowledge of bird species that occur exclusively in the Australian tropics (including tropical Queensland) is very poor compared to those that also occur in the Brisbane area and are relatively common. Experimental results indicate that when respondents in the sample had an option to allocate $1,000 between ten bird species listed in the survey, it resulted in a greater allocation of funds to the better known and more common species than when they were provided with balanced information about all the selected species. With balanced information the average allocation to bird species confined mostly to the Australian tropics, particularly those threatened or endangered, increased. The general consequences of this for policies for the conservation of birds are discussed.
Resumo:
This fully updated and comprehensively revised edition of a classic text concentrates on the economics of conserving the living environment. It begins by covering the ethical foundations and basic economic paradigms’ essential for understanding and assessing ecological economics. General strategies for global environmental conservation, policies for government intervention, developing countries, preserving wildlife and biodiversity, open-access to and common property in natural resources, conservation of natural areas, forestry, agriculture and the environment, tourism, sustainable development and demographic change are also all covered.
Resumo:
The linearity of daily linear harvest index (HI) increase can provide a simple means to predict grain growth and yield in field crops. However, the stability of the rate of increase across genotypes and environments is uncertain. Data from three field experiments were collated to investigate the phase of linear HI increase of sunflower (Helianthus annuus L,) across environments by changing genotypes, sowing time, N level, and solar irradiation level. Linear increase in HI was similar among different genotypes, N levels, and radiation treatments (mean 0.0125 d(-1)). but significant differences occurred between sowings, The linear increase in HI was not stable at very low temperatures (down to 9 degrees C) during grain filling, due to possible limitations to biomass accumulation and translocation (mean 0.0091 d(-1)). Using the linear increase in HI to predict grain yield requires predictions of the duration from anthesis to the onset of linear HI increase (lag phase) and the cessation of linear RT increase. These studies showed that the lag phase differed, and the linear HI increase ceased when 91% of the anthesis to physiological maturity period had been completed.
Resumo:
We have determined the post-translational modifications of the major capsid protein, L1 of human papillomavirus (HPV) type 6b. Since this virus cannot be cultured in the laboratory to obtain sufficient material for a study, a recombinant L1 protein produced in a vaccinia virus expression system was used in this investigation. Our results show that this protein is phosphorylated at serine residues and is also glycosylated. No myristoylation or palmitoylation was detected. The fraction of L1 protein incorporated into virus-like particles was not glycosylated. Since recombinant L1 protein is a potential human vaccine candidate, knowledge of the post-translation modifications of this protein may prove useful for the design of anti-HPV vaccines. (C) 1999 Elsevier Science B.V. All rights reserved.
Resumo:
Recent structural studies of proteins mediating membrane fusion reveal intriguing similarities between diverse viral and mammalian systems. Particularly striking is the close similarity between the transmembrane envelope glycoproteins from the retrovirus HTLV-1 and the filovirus Ebola. These similarities suggest similar mechanisms of membrane fusion. The model that fits most currently available data suggests fusion activation in viral systems is driven by a symmetrical conformational change triggered by an activation event such as receptor binding or a pH change. The mammalian vesicle fusion mediated by the SNARE protein complex most likely occurs by a similar mechanism but without symmetry constraints.
Resumo:
Many harvested marine and terrestrial populations have segments of their range protected in areas free from exploitation. Reasons for areas being protected from harvesting include conservation, tourism, research, protection of breeding grounds, stock recovery, harvest regulation, or habitat that is uneconomical to exploit. In this paper we consider the problem of optimally exploiting a single species local population that is connected by dispersing larvae to an unharvested local population. We define a spatially-explicit population dynamics model and apply dynamic optimization techniques to determine policies for harvesting the exploited patch. We then consider how reservation affects yield and spawning stock abundance when compared to policies that have not recognised the spatial structure of the metapopulation. Comparisons of harvest strategies between an exploited metapopulation with and without a harvest refuge are also made. Results show that in a 2 local population metapopulation with unidirectional larval transfer, the optimal exploitation of the harvested population should be conducted as if it were independent of the reserved population. Numerical examples suggest that relative source populations should be exploited if the objective is to maximise spawning stock abundance within a harvested metapopulation that includes a protected local population. However, this strategy can markedly reduce yield over a sink harvested reserve system and may require strict regulation for conservation goals to be realised. If exchange rates are high, results indicate that spawning stock abundance can be less in a reserve system than in a fully exploited metapopulation. In order to maximise economic gain in the reserve system, results indicate that relative sink populations should be harvested. Depending on transfer levels, loss in harvest through reservation can be minimal, and is likely to be compensated by the potential environmental and economic benefits of the reserve.
Resumo:
1. The spatial and temporal distribution of eggs laid by herbivorous insects is a crucial component of herbivore population stability, as it influences overall mortality within the population. Thus an ecologist studying populations of an endangered butterfly can do little to increase its numbers through habitat management without knowledge of its egg-laying patterns across individual host-plants under different habitat management regimes. At the other end of the spectrum, a knowledge of egg-laying behaviour can do much to control pest outbreaks by disrupting egg distributions that lead to rapid population growth. 2. The distribution of egg batches of the processionary caterpillar Ochrogaster lunifer on acacia trees was monitored in 21 habitats during 2 years in coastal Australia. The presence of egg batches on acacias was affected by host-tree 'quality' (tree size and foliar chemistry that led to increased caterpillar survival) and host-tree 'apparency' (the amount of vegetation surrounding host-trees). 3. In open homogeneous habitats, more egg batches were laid on high-quality trees, increasing potential population growth. In diverse mixed-species habitats, more egg batches were laid on low-quality highly apparent trees, reducing population growth and so reducing the potential for unstable population dynamics. The aggregation of batches on small apparent trees in diverse habitats led to outbreaks on these trees year after year, even when population levels were low, while site-wide outbreaks were rare. 4. These results predict that diverse habitats with mixed plant species should increase insect aggregation and increase population stability. In contrast, in open disturbed habitats or in regular plantations, where egg batches are more evenly distributed across high-quality hosts, populations should be more unstable, with site-wide outbreaks and extinctions being more common. 5. Mixed planting should be used on habitat regeneration sites to increase the population stability of immigrating or reintroduced insect species. Mixed planting also increases the diversity of resources, leading to higher herbivore species richness. With regard to the conservation of single species, different practices of habitat management will need to be employed depending on whether a project is concerned with methods of rapidly increasing the abundance of an endangered insect or concerned with the maintenance of a stable, established insect population that is perhaps endemic to an area. Suggestions for habitat management in these different cases are discussed. 6. Finally, intercropping can be highly effective in reducing pest outbreaks, although the economic gains of reduced pest attack may be outweighed by reduced crop yields in mixed-crop systems.
Resumo:
The phenomenon of agricultural land degradation in the Philippine uplands has been regarded by scientists and policy-makers as a major environmental and rural development problem. Numerous conservation farming projects have been implemented in the past two decades to address this problem, apparently with little success. Most of these projects have espoused the currently fashionable principles of community-based sustainable development. This paper examines case histories of three completed upland conservation projects. The aim is to compare the rhetoric of project documents and evaluations with the reality of on-going land management practices as seen from the perspective of the land managers themselves. (C) 2000 Elsevier Science Ltd. All rights reserved.
Resumo:
Regional and national surveys provide a broadscale description of the koala's present distribution in Australia. A detailed understanding of its distribution is precluded, however, by past and continuing land clearing across large parts of the koala's range. Koala population density increased in some regions during the late 1800s and then declined dramatically in the early 1900s. The decline was associated with habitat loss, hunting, disease, fire, and drought. Declines are continuing in Queensland and New South Wales. In contrast, dense koala populations in habitat isolates in Victoria and South Australia are managed to reduce population size and browse damage. Current understanding of koala distribution and abundance suggests that the species does not meet Australian criteria as endangered or vulnerable fauna. Its conservation status needs to be reviewed, however, in light of the extensive land clearing in New South Wales and Queensland since the last (1980s) broadscale surveys. Consequently, we recommend that broadacre clearing by curtailed in New South Wales and Queensland and that regular, comprehensive, standardized, national koala surveys be undertaken. Given the fragmentation of koala habitat and regional differences in the status of the koala, we recommended that studies on regional variation in the koala be intensified and that koala ecology in fragmented and naturally restricted habitats be developed. More generally, the National Koala Conservation Strategy should be implemented.
Resumo:
Virus-like particles (VLPs) are being currently investigated in vaccines against viral infections in humans. There are different recombinant-protein-expression systems available for obtaining the necessary VLP preparation for vaccination. However, the differences in post-translational modifications of the recombinant proteins obtained and their differences in efficacy in eliciting an anti-viral response in vaccines are not well established. In this study we have compared the posttranslational modifications of human papillomavirus type-6b major capsid protein L1 (HPV 6bL1) expressed using recombinant baculovirus (rBV) in Sf9 (Spodoptera frugiperda) insect cells, with the protein expressed using recombinant vaccinia virus (rVV) in CV-1 kidney epithelial cells, Two-dimensional gel electrophoresis of biosynthetically labelled rBV-expressed HPV 6bL1 showed several post-translationally modified variants of the protein, whereas rVV-expressed HPV 6bL1 showed only a few variants. Phosphorylations were detected at threonine and serine residues for the L1 expressed from rBV compared with phosphorylation at serine residues only for the L1 expressed from rVV. HPV 6bL1 expressed using rBV incorporated [H-3]mannose and [H-3]galactose, whereas HPV 6bL1 expressed using rVV incorporated only [H-3]galactose. We conclude that post-translational modification of recombinant HPV 6bL1 can differ according to the system used for its expression. Since recombinant L1 protein is a potential human-vaccine candidate, the implication of the observed differences in post-translational modifications on immunogenicity of L1 VLPs warrants investigation.