500 research outputs found
A Review of the South Pacific Tuna Baitfisheries: Small Pelagic Fisheries Associated with Coral-Reefs
A review is given of current information concerning small pelagic fishes exploited for tuna bait in the South Pacific. These fishes are usually caught over or near coral reefs using light attraction and lift nets. The most common and widespread species are anchovies (Engraulidae), sprats (Clupeidae), silversides (Atherinidae), and herrings (Clupeidae). Recorded yields ranged from 0.5 to 2.6t/km2, and methods are described to estimate potential yields empirically in the absence of catch data. Environmental effects on small pelagic fish production are discussed, and evidence is presented to suggest that rainfall markedly affects stolephorid anchovy production. Some species of small pelagic fish, such as Selar spp., Decapterus spp., and Herklotsichthys sp., have been fished traditionally by artisanal fishermen, but anchovy and sprat stocks were probably unexploited prior to pole-and-line tuna fishing in the South Pacific
Predicting consumer biomass, size-structure, production, catch potential, responses to fishing and associated uncertainties in the world's marine ecosystems
Existing estimates of fish and consumer biomass in the world’s oceans are disparate. This creates uncertainty about the roles of fish and other consumers in biogeochemical cycles and ecosystem processes, the extent of human and environmental impacts and fishery potential. We develop and use a size-based macroecological model to assess the effects of parameter uncertainty on predicted consumer biomass, production and distribution. Resulting uncertainty is large (e.g. median global biomass 4.9 billion tonnes for consumers weighing 1 g to 1000 kg; 50% uncertainty intervals of 2 to 10.4 billion tonnes; 90% uncertainty intervals of 0.3 to 26.1 billion tonnes) and driven primarily by uncertainty in trophic transfer efficiency and its relationship with predator-prey body mass ratios. Even the upper uncertainty intervals for global predictions of consumer biomass demonstrate the remarkable scarcity of marine consumers, with less than one part in 30 million by volume of the global oceans comprising tissue of macroscopic animals. Thus the apparently high densities of marine life seen in surface and coastal waters and frequently visited abundance hotspots will likely give many in society a false impression of the abundance of marine animals. Unexploited baseline biomass predictions from the simple macroecological model were used to calibrate a more complex size- and trait-based model to estimate fisheries yield and impacts. Yields are highly dependent on baseline biomass and fisheries selectivity. Predicted global sustainable fisheries yield increases ≈4 fold when smaller individuals (< 20 cm from species of maximum mass < 1kg) are targeted in all oceans, but the predicted yields would rarely be accessible in practice and this fishing strategy leads to the collapse of larger species if fishing mortality rates on different size classes cannot be decoupled. Our analyses show that models with minimal parameter demands that are based on a few established ecological principles can support equitable analysis and comparison of diverse ecosystems. The analyses provide insights into the effects of parameter uncertainty on global biomass and production estimates, which have yet to be achieved with complex models, and will therefore help to highlight priorities for future research and data collection. However, the focus on simple model structures and global processes means that non-phytoplankton primary production and several groups, structures and processes of ecological and conservation interest are not represented. Consequently, our simple models become increasingly less useful than more complex alternatives when addressing questions about food web structure and function, biodiversity, resilience and human impacts at smaller scales and for areas closer to coasts
Toxicity in Beef Cattle Grazing \u3cem\u3eLeucaena leucocephala\u3c/em\u3e in Queensland, Australia
Improved pastures based on the leguminous shrub Leucaena leucocephala (leucaena) are the most productive, profitable and sustainable for beef cattle production in northern Australia. Leucaena forage contains the toxic, non-protein amino acid mimosine, which is rapidly converted to 3-hydroxy-4(1H)-pyridone (DHP) upon ingestion by grazing cattle. This is a potent goitrogen and appetite suppressant. Animals suffering severe DHP toxicity exhibit distinctive symptoms (e.g. hair loss, excessive salivation, goitre and weight loss), while subclinical DHP toxicity can suppress live weight gain by 30-50% without producing any obvious symptoms. Prior to the discovery and introduction of the DHP-degrading rumen bacteria Synergistes jonesii into Australia in 1982, DHP toxicity severely limited animal performance from leucaena pastures and was a major impediment to adoption. Initial rumen inoculation of cattle in Australia with S. jonesii successfully protected them against DHP toxicity and the bacterium appeared to be easily and rapidly transmitted between grazing animals. Consequently many scientists and graziers believed that a single inoculation of a herd with S. jonesii, combined with simple ongoing herd management, was sufficient to overcome the problem of DHP toxicity. However, during the 2003 drought there were several reports of severe leucaena toxicity (including animal deaths) in cattle grazing leucaena in Queensland. Toxicity was evident even in herds that had followed recommended control measures. Preliminary results are presented of a study, designed to ascertain the prevalence and possible causes of leucaena toxicity in Queensland cattle herds. Meat and Livestock Australia Limited funded this research (NBP.340)
The <i>Pratylenchus penetrans</i> transcriptome as a source for the development of alternative control strategies:mining for putative genes involved in parasitism and evaluation of <i>in planta</i> RNAi
The root lesion nematode Pratylenchus penetrans is considered one of the most economically important species within the genus. Host range studies have shown that nearly 400 plant species can be parasitized by this species. To obtain insight into the transcriptome of this migratory plant-parasitic nematode, we used Illumina mRNA sequencing analysis of a mixed population, as well as nematode reads detected in infected soybean roots 3 and 7 days after nematode infection. Over 140 million paired end reads were obtained for this species, and de novo assembly resulted in a total of 23,715 transcripts. Homology searches showed significant hit matches to 58% of the total number of transcripts using different protein and EST databases. In general, the transcriptome of P. penetrans follows common features reported for other root lesion nematode species. We also explored the efficacy of RNAi, delivered from the host, as a strategy to control P. penetrans, by targeted knock-down of selected nematode genes. Different comparisons were performed to identify putative nematode genes with a role in parasitism, resulting in the identification of transcripts with similarities to other nematode parasitism genes. Focusing on the predicted nematode secreted proteins found in this transcriptome, we observed specific members to be up-regulated at the early time points of infection. In the present study, we observed an enrichment of predicted secreted proteins along the early time points of parasitism by this species, with a significant number being pioneer candidate genes. A representative set of genes examined using RT-PCR confirms their expression during the host infection. The expression patterns of the different candidate genes raise the possibility that they might be involved in critical steps of P. penetrans parasitism. This analysis sheds light on the transcriptional changes that accompany plant infection by P. penetrans, and will aid in identifying potential gene targets for selection and use to design effective control strategies against root lesion nematodes
Root canal instrumentation efficacy of non-fused and fused primary molar roots:a micro-computed tomography study
Purpose Pulpectomy may be indicated in restorable primary teeth exhibiting irreversible pulpitis or pulpal necrosis. The purpose of this study was to compare the cleaning and shaping efficacy of NiTi systems (Reciproc(R) Blue and MTwo(R)) with manual stainless-steel instrumentation in primary molars using micro-CT analysis. Methods Fifty-seven maxillary second primary molars were scanned using micro-CT. Teeth with three divergent roots were divided randomly (n = 15) according to instrument type (K file, MTwo (R), and Reciproc (R) Blue). Teeth with root fusion were instrumented manually as a separate group (n = 12). Pre- and post-instrumentation micro-CT images were superimposed, and the instrumentation area (IA) and procedural complications were recorded. Results No statistically significant differences in IA between file systems was observed in the non-fused teeth. The mean IA of fused roots was significantly lower than in the non-fused distobuccal (p = 0.003) and palatal (p 60%) occurred in both non-fused and fused primary teeth with fewer procedural complications observed after manual instrumentation
Critical Issues in the Development of Health Information Systems in Supporting Environmental Health: A Case Study of Ciguatera
Emerging environmental pressures resulting from climate change and globalization challenge the capacity of health information systems (HIS) in the Pacific to inform future policy and public health interventions. Ciguatera, a globally common marine food-borne illness, is used here to illustrate specific HIS challenges in the Pacific and how these might be overcome proactively to meet the changing surveillance needs resulting from environmental change.We review and highlight inefficiencies in the reactive nature of existing HIS in the Pacific to collect, collate, and communicate ciguatera fish poisoning data currently used to inform public health intervention. Further, we review the capacity of existing HIS to respond to new data needs associated with shifts in ciguatera disease burden likely to result from coral reef habitat disruption.Improved knowledge on the ecological drivers of ciguatera prevalence at local and regional levels is needed, combined with enhanced surveillance techniques and data management systems, to capture environmental drivers as well as health outcomes data.The capacity of public HIS to detect and prevent future outbreaks is largely dependent on the future development of governance strategies that promote proactive surveillance and health action. Accordingly, we present an innovative framework from which to stimulate scientific debate on how this might be achieved by using existing larger scale data sets and multidisciplinary collaborations
Accrediting outputs of noisy intermediate-scale quantum computing devices
We present an accreditation protocol for the outputs of noisy
intermediate-scale quantum devices. By testing entire circuits rather than
individual gates, our accreditation protocol can provide an upper-bound on the
variation distance between noisy and noiseless probability distribution of the
outputs of the target circuit of interest. Our accreditation protocol requires
implementation of quantum circuits no larger than the target circuit, therefore
it is practical in the near term and scalable in the long term. Inspired by
trap-based protocols for the verification of quantum computations, our
accreditation protocol assumes that noise in single-qubit gates is bounded (but
potentially gate-dependent) in diamond norm. We allow for arbitrary spatial and
temporal correlations in the noise affecting state preparation, measurements
and two-qubit gates. We describe how to implement our protocol on real-world
devices, and we also present a novel cryptographic protocol (which we call
`mesothetic' protocol) inspired by our accreditation protocol.Comment: Accepted versio
Nematode neuropeptides as transgenic nematicides
NDW was supported by a Bill and Melinda Gates Foundation grand challenge exploration grant. LW was supported by a PhD studentship from the EUPHRESCO Plant Health Fellowship Scheme, and an Eaton Visitorship Award. JJD was supported by a Leverhulme Trust early career fellowship and a Bill and Melinda Gates Foundation grand challenge exploration grant.Plant parasitic nematodes (PPNs) seriously threaten global food security. Conventionally an
integrated approach to PPN management has relied heavily on carbamate, organophosphate and fumigant nematicides which are now being withdrawn over environmental health
and safety concerns. This progressive withdrawal has left a significant shortcoming in our
ability to manage these economically important parasites, and highlights the need for novel
and robust control methods. Nematodes can assimilate exogenous peptides through retrograde transport along the chemosensory amphid neurons. Peptides can accumulate within
cells of the central nerve ring and can elicit physiological effects when released to interact
with receptors on adjoining cells. We have profiled bioactive neuropeptides from the neuropeptide-like protein (NLP) family of PPNs as novel nematicides, and have identified numerous discrete NLPs that negatively impact chemosensation, host invasion and stylet thrusting
of the root knot nematode Meloidogyne incognita and the potato cyst nematode Globodera
pallida. Transgenic secretion of these peptides from the rhizobacterium, Bacillus subtilis, and
the terrestrial microalgae Chlamydomonas reinhardtii reduce tomato infection levels by up to
90% when compared with controls. These data pave the way for the exploitation of nematode
neuropeptides as a novel class of plant protective nematicide, using novel non-food transgenic delivery systems which could be deployed on farmer-preferred cultivars
Grouping of UVCB substances with dose-response transcriptomics data from human cell-based assays
The application of in vitro biological assays as new approach methodologies (NAMs) to support grouping of UVCB (unknown or variable composition, complex reaction products, and biological materials) substances has recently been demonstrated. In addition to cell-based phenotyping as NAMs, in vitro transcriptomic profiling is used to gain deeper mechanistic understanding of biological responses to chemicals and to support grouping and read-across. However, the value of gene expression profiling for characterizing complex substances like UVCBs has not been explored. Using 141 petroleum substance extracts, we performed dose-response transcriptomic profiling in human induced pluripotent stem cell (iPSC)-derived hepatocytes, cardiomyocytes, neurons, and endothelial cells, as well as cell lines MCF7 and A375. The goal was to determine whether transcriptomic data can be used to group these UVCBs and to further characterize the molecular basis for in vitro biological responses. We found distinct transcriptional responses for petroleum substances by manufacturing class. Pathway enrichment informed interpretation of effects of substances and UVCB petroleum-class. Transcriptional activity was strongly correlated with concentration of polycyclic aromatic compounds (PAC), especially in iPSC-derived hepatocytes. Supervised analysis using transcriptomics, alone or in combination with bioactivity data collected on these same substances/cells, suggest that transcriptomics data provide useful mechanistic information, but only modest additional value for grouping. Overall, these results further demonstrate the value of NAMs for grouping of UVCBs, identify informative cell lines, and provide data that could be used for justifying selection of substances for further testing that may be required for registration
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