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81.
Griffiths MK Mayfield S Branch GM 《Journal of experimental marine biology and ecology》2000,247(2):223-232
Dietary analyses are important components of ecological studies. However, some methods of collecting organisms may expose them to exceptionally high densities of prey items, leading to inaccurate dietary assessments. These methods include the use of baited traps. We hypothesised that such a "trap effect" occurred during work on the diet of the rock lobster Jasus lalandii, because baited traps attracted isopods, which were then eaten opportunistically by trapped J. lalandii. To test this hypothesis, rock lobsters were collected at two sites using both baited-traps and Scuba diving. Results showed that large numbers of isopods were attracted to, and consumed, the trap-bait. Analyses of the stomach contents of trap-caught J. lalandii from both localities reflected a larger occurrence and significantly greater abundance of isopods in stomach samples from trap- rather than Scuba-caught rock lobsters. For probably similar reasons, small fish were significantly over-represented in the gut contents of trap-caught rock lobsters, although the evidence is less clear-cut and there may be other explanations for the high proportions of fish in the diet. Although isopods and fish may be naturally consumed at a low rate, predation on them is greatly inflated in traps, and the dietary analyses of trap-caught J. lalandii. All assessments of the diets of animals traditionally caught with traps should consider and account for such "trap effects", by calibrating the data for trap-caught animals against an alternative sampling method. 相似文献
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83.
Sundin GW Mayfield CT Zhao Y Gunasekera TS Foster GL Ullrich MS 《Molecular genetics and genomics : MGG》2004,270(6):462-476
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Partially denatured DNAs from mouse, cow, and chicken were visualized in the electron microscope by the basic protein film technique and the size and distribution of the denatured regions characterized. A-T rich sequences visualized at 15% denaturation average about 1500 bases in length for all three species and are arranged quite non-randomly in the genome. This arrangement is such that 30–50% of the entire genome contains no A-T rich DNA, and another 20% is composed about one-half of A-T rich sequences and one-half of other sequences. Comparison with DNA denaturation profiles indicates that for each organism these sequences are from 25–35% G+C and that there is very little if any DNA more A-T rich than these. Estimates from published studies of fluorescence enhancement of quinacrine bound to A-T rich DNAs suggest that the observed non-random organization of A-T rich sequences is sufficient to account for Q banding of metaphase chromosomes. 相似文献
86.
Algal chloroplast produced camelid VHH antitoxins are capable of neutralizing botulinum neurotoxin
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Daniel J. Barrera Julian N. Rosenberg Joanna G. Chiu Yung‐Nien Chang Michelle Debatis Soo‐Mun Ngoi John T. Chang Charles B. Shoemaker George A. Oyler Stephen P. Mayfield 《Plant biotechnology journal》2015,13(1):117-124
We have produced three antitoxins consisting of the variable domains of camelid heavy chain‐only antibodies (VHH) by expressing the genes in the chloroplast of green algae. These antitoxins accumulate as soluble proteins capable of binding and neutralizing botulinum neurotoxin. Furthermore, they accumulate at up to 5% total soluble protein, sufficient expression to easily produce these antitoxins at scale from algae. The genes for the three different antitoxins were transformed into Chlamydomonas reinhardtii chloroplasts and their products purified from algae lysates and assayed for in vitro biological activity using toxin protection assays. The produced antibody domains bind to botulinum neurotoxin serotype A (BoNT/A) with similar affinities as camelid antibodies produced in Escherichia coli, and they are similarly able to protect primary rat neurons from intoxication by BoNT/A. Furthermore, the camelid antibodies were produced in algae without the use of solubilization tags commonly employed in E. coli. These camelid antibody domains are potent antigen‐binding proteins and the heterodimer fusion protein containing two VHH domains was capable of neutralizing BoNT/A at near equimolar concentrations with the toxin. Intact antibody domains were detected in the gastrointestinal (GI) tract of mice treated orally with antitoxin‐producing microalgae. These findings support the use of orally delivered antitoxins produced in green algae as a novel treatment for botulism. 相似文献
87.
Manu E. Saunders Gary W. Luck Margaret M. Mayfield 《Journal of Insect Conservation》2013,17(5):1011-1025
Wild pollinators are becoming more valuable to global agriculture as the commercial honeybee industry is increasingly affected by disease and other stressors. Perennial tree crops are particularly reliant on insect pollination, and are often pollen limited. Research on how different tree crop production systems influence the richness and abundance of wild pollinators is, however, limited. We investigated, for the first time, the richness and abundance of potential wild pollinators in commercial temperate almond orchards in Australia, and compared them to potential pollinator communities in proximate native vegetation. We quantified ground cover variables at each site and assessed the value of ground cover on the richness and abundance of potential wild pollinators in commercial almond systems focussing on three common taxa: bees, wasps and flies. More insects were caught in orchards with living ground cover than in native vegetation or orchards without ground cover, although overall species richness was highest in native vegetation. Percent ground cover was positively associated with wasp richness and abundance, and native bee richness, but flies showed no association with ground cover. The strongest positive relationship was between native bee abundance and the richness of ground cover plants. Our results suggest that maintaining living ground cover within commercial almond orchards could provide habitat and resources for potential wild pollinators, particularly native bees. These insects have the potential to provide a valuable ecosystem service to pollinator-dependent crops such as almond. 相似文献
88.
Damien A. Fordham Camille Mellin Bayden D. Russell Reşit H. Akçakaya Corey J. A. Bradshaw Matthew E. Aiello‐Lammens Julian M. Caley Sean D. Connell Stephen Mayfield Scoresby A. Shepherd Barry W. Brook 《Global Change Biology》2013,19(10):3224-3237
Evidence is accumulating that species' responses to climate changes are best predicted by modelling the interaction of physiological limits, biotic processes and the effects of dispersal‐limitation. Using commercially harvested blacklip (Haliotis rubra) and greenlip abalone (Haliotis laevigata) as case studies, we determine the relative importance of accounting for interactions among physiology, metapopulation dynamics and exploitation in predictions of range (geographical occupancy) and abundance (spatially explicit density) under various climate change scenarios. Traditional correlative ecological niche models (ENM) predict that climate change will benefit the commercial exploitation of abalone by promoting increased abundances without any reduction in range size. However, models that account simultaneously for demographic processes and physiological responses to climate‐related factors result in future (and present) estimates of area of occupancy (AOO) and abundance that differ from those generated by ENMs alone. Range expansion and population growth are unlikely for blacklip abalone because of important interactions between climate‐dependent mortality and metapopulation processes; in contrast, greenlip abalone should increase in abundance despite a contraction in AOO. The strongly non‐linear relationship between abalone population size and AOO has important ramifications for the use of ENM predictions that rely on metrics describing change in habitat area as proxies for extinction risk. These results show that predicting species' responses to climate change often require physiological information to understand climatic range determinants, and a metapopulation model that can make full use of this data to more realistically account for processes such as local extirpation, demographic rescue, source‐sink dynamics and dispersal‐limitation. 相似文献
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90.
Recent advances in bacterial heme protein biochemistry 总被引:1,自引:0,他引:1
Recent progress in genetics, fed by the burst in genome sequence data, has led to the identification of a host of novel bacterial heme proteins that are now being characterized in structural and mechanistic terms. The following short review highlights very recent work with bacterial heme proteins involved in the uptake, biosynthesis, degradation, and use of heme in respiration and sensing. 相似文献