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1.
Deon. C. Nel Peter G. Ryan Jeanne L. Nel Norbert T. W. Klages Rory P. Wilson Graham Robertson & Geoff N. Tuck 《Ibis》2002,144(3):E141-E154
Wandering Albatrosses Diomedea exulans are frequently killed when they attempt to scavenge baited hooks deployed by long-line fishing vessels. We studied the foraging ecology of Wandering Albatrosses breeding on Marion Island in order to assess the scale of interactions with known long-line fishing fleets. During incubation and late chick-rearing, birds foraged further away from the island, in warmer waters, and showed high spatial overlap with areas of intense tuna Thunnus spp. long-line fishing. During early chick-rearing, birds made shorter foraging trips and showed higher spatial overlap with the local Patagonian Toothfish Dissostichus eleginoides long-line fishery. Tracks of birds returning with offal from the Toothfish fishery showed a strong association with positions at which Toothfish long-lines were set and most diet samples taken during this stage contained fishery-related items. Independent of these seasonal differences, females foraged further from the islands and in warmer waters than males. Consequently, female distribution overlapped more with tuna long-line fisheries, whereas males interacted more with the Toothfish long-line fishery. These factors could lead to differences in the survival probabilities of males and females. Non-breeding birds foraged in warmer waters and showed the highest spatial overlap with tuna long-line fishing areas. The foraging distribution of Marion Island birds showed most spatial overlap with birds from the neighbouring Crozet Islands during the late chick-rearing and non-breeding periods. These areas of foraging overlap also coincided with areas of intense tuna long-line fishing south of Africa. As the population trends of Wandering Albatrosses at these two localities are very similar, it is possible that incidental mortality during the periods when these two populations show the highest spatial overlap could be driving these trends. 相似文献
2.
Steffen H. Büttner Eric W. Isemonger Michelle Isaacs Deon van Niekerk Rachel E. Sipler Rosemary A. Dorrington 《Geobiology》2021,19(1):35-47
In the geological record, fossil phosphatic stromatolites date back to the Great Oxidation Event in the Paleoproterozoic, but living phosphatic stromatolites have not been described previously. Here, we report on cyanobacterial stromatolites in a supratidal freshwater environment at Cape Recife, South African southern coast, precipitating Ca carbonate alternating with episodes of Ca phosphate deposition. In their structure and composition, the living stromatolites from Cape Recife closely resemble their fossilized analogues, showing phosphatic zonation, microbial casts, tunnel structures and phosphatic crusts of biogenic origin. The microbial communities appear to be also similar to those proposed to have formed fossil phosphatic stromatolites. Phosphatic domains in the material from Cape Recife are spatially and texturally associated with carbonate precipitates, but form distinct entities separated by sharp boundaries. Electron Probe Micro‐Analysis shows that Ca/P ratios and the overall chemical compositions of phosphatic precipitates are in the range of octacalcium phosphate, amorphous tricalcium phosphate and apatite. The coincidence in time of the emergence of phosphatic stromatolites in the fossil record with a major episode of atmospheric oxidation led to the assumption that at times of increased oxygen release the underlying increased biological production may have been linked to elevated phosphorus availability. The stromatolites at Cape Recife, however, form in an environment where ambient phosphorus concentrations do not exceed 0.28 μM, one to two orders of magnitude below the previously predicted minimum threshold of >5 μM for biogenic phosphate precipitation in paleo‐systems. Accordingly, we contest the previously proposed suitability of phosphatic stromatolites as a proxy for high ambient phosphate concentrations in supratidal to shallow ocean settings in earth history. 相似文献
3.
Hassan Mahomed Rodney Ehrlich Tony Hawkridge Mark Hatherill Lawrence Geiter Fazlin Kafaar Deborah Ann Abrahams Humphrey Mulenga Michele Tameris Hennie Geldenhuys Willem Albert Hanekom Suzanne Verver Gregory Dudley Hussey 《PloS one》2013,8(3)
Background
Tuberculosis (TB) is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa.Methods
We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST) performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment.Results
A total of 6,363 adolescents were enrolled (58% of the school population targeted). During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.29–0.72). Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis.Conclusion
The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease. 相似文献4.
Carla Cristina Gonçalves Rosado Lúcio Mauro da Silva Guimarães Danielle Assis Faria Marcos Deon Vilela de Resende Cosme Damião Cruz Dario Grattapaglia Acelino Couto Alfenas 《Tree Genetics & Genomes》2016,12(4):72
Ceratocystis wilt caused by the fungus Ceratocystis fimbriata, is currently one of the major diseases in commercial plantations of Eucalyptus trees in Brazil. Deployment of resistant genotypes has been the main strategy for effective disease management. The present study aimed at identifying genomic regions underlying the genetic control of resistance to Ceratocystis wilt in Eucalyptus by quantitative trait loci (QTL) mapping in an outbred hybrid progeny derived from a cross between (Eucalyptus dunnii × Eucalyptus grandis) × (Eucalyptus urophylla × Eucalyptus globulus). A segregating population of 127 individuals was phenotyped for resistance to Ceratocystis wilt using controlled inoculation under a completely randomized design with five clonal replicates per individual plant. The phenotypic resistance response followed a continuous variation, enabling us to analyze the trait in a quantitative manner. The population was genotyped with 114 microsatellite markers and 110 were mapped with an average interval of 12.3 cM. Using a sib-pair interval-mapping approach five QTLs were identified for disease resistance, located on linkage groups 1, 3, 5, 8, and 10, and their estimated individual heritability ranged from 0.096 to 0.342. The QTL on linkage group 3 overlaps with other fungal disease-resistance QTLs mapped earlier and is consistent with the annotation of several disease-resistance genes on this chromosome in the E. grandis genome. This is the first study to identify and attempt to quantify the effects of QTLs associated with resistance to Ceratocystis wilt in Eucalyptus. 相似文献
5.
Roman Zoss Fernando Medina Ferrer Beverly E. Flood Daniel S. Jones Deon.C. Louw Jake Bailey 《Geobiology》2019,17(1):76-90
The processes that lead to the precipitation of authigenic calcium phosphate minerals in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate‐accumulating bacteria. These bacteria are believed to concentrate phosphate in sediment pore waters, creating supersaturated conditions with respect to apatite precursors. However, the relationship between microbes and phosphorite formation is not fully resolved. To further study this association, we examined microbial community data generated from two sources: sediment cores recovered from the shelf of the Benguela upwelling region where phosphorites are currently forming, and DNA preserved within phosphoclasts recovered from a phosphorite deposit along the Benguela shelf. iTag and clone library sequencing of the 16S rRNA gene showed that many of our sediment‐hosted communities shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfate‐reducing bacteria and sulfur‐oxidizing bacteria were particularly abundant in our datasets, as were phylotypes that are known to carry out nitrification and the anaerobic oxidation of ammonium. The DNA extracted from phosphoclasts contained the signature of a distinct microbial community from those observed in the modern sediments. While some aspects of the modern and phosphoclast communities were similar, we observed both an enrichment of certain common microbial classes found in the modern phosphogenic sediments and a relative depletion of others. The phosphoclast‐associated DNA could represent a relict signature of one or more microbial assemblages that were present when the apatite or its precursors precipitated. While these taxa may or may not have contributed to the precipitation of the apatite that now hosts their genetic remains, several groups represented in the phosphoclast extract dataset have the genetic potential to metabolize polyphosphate, and perhaps modulate phosphate concentrations in pore waters where carbonate fluorapatite (or its precursors) are known to be precipitating. 相似文献
6.
Werner J. Geldenhuys Robert Skolik Mary E. Konkle Michael A. Menze Timothy E. Long Aaron R. Robart 《Bioorganic & medicinal chemistry letters》2019,29(7):901-904
Nutrient-deprivation autophagy factor-1 (NAF-1, miner1; gene cisd2) is part of the [2Fe-2S]-containing protein family which includes mitoNEET (gene cisd1) and MiNT (miner2; gene cisd3). These proteins are redox active and are thought to play an important role in cellular energy homeostasis with NAF-1 playing a critical role in calcium regulation and aging. To date, no studies have investigated potential ligand interaction with NAF-1. Here we show that the thiazolidinediones pioglitazone and rosiglitazone along with the mitoNEET ligand, NL-1, bind to NAF-1 with low micromolar affinities. Further, we show that overexpression of NAF-1 in hepatocellular carcinoma (HepG2) cells reduces inhibition of mitochondrial respiration by pioglitazone. Our findings support the need for further efforts of the rational design of selective NAF-1 ligands. 相似文献
7.
The molecular identification, expression and cloning of membrane-bound organic cation transporters are being completed in isolated in vitro membranes. In vivo studies, where cation specificity overlaps, need to complement this work. Method: Cross-inhibition of [3H]choline and [3H]thiamine brain uptake by in situ rat brain perfusion. Results: [3H]Choline brain uptake was not inhibited by thiamine at physiologic concentrations (100 nM). However, choline ranging from 100 nM to 250 M inhibited [3H]thiamine brain uptake, though not below levels observed at thiamine concentrations of 100 nM. Conclusion: (1) The molecular family of the blood–brain barrier (BBB) choline transporter may be elucidated in vitro by its interaction with physiologic thiamine levels, and (2) two cationic transporters at the BBB may be responsible for thiamine brain uptake. 相似文献
8.
Back signaling by the Nrg-1 intracellular domain 总被引:4,自引:0,他引:4
Transmembrane isoforms of neuregulin-1 (Nrg-1), ligands for erbB receptors, include an extracellular domain with an EGF-like sequence and a highly conserved intracellular domain (ICD) of unknown function. In this paper, we demonstrate that transmembrane isoforms of Nrg-1 are bidirectional signaling molecules in neurons. The stimuli for Nrg-1 back signaling include binding of erbB receptor dimers to the extracellular domain of Nrg-1 and neuronal depolarization. These stimuli elicit proteolytic release and translocation of the ICD of Nrg-1 to the nucleus. Once in the nucleus, the Nrg-1 ICD represses expression of several regulators of apoptosis, resulting in decreased neuronal cell death in vitro. Thus, regulated proteolytic processing of Nrg-1 results in retrograde signaling that appears to mediate contact and activity-dependent survival of Nrg-1-expressing neurons. 相似文献
9.
Linden Birthe Dalton Desiré L. Van Wyk Anna de Jager Deon Moodley Yoshan Taylor Peter J. 《Primates; journal of primatology》2022,63(3):245-260
Primates - Forests affected by fragmentation are at risk of losing their primate populations over the long term. The impact of fragmentation on primate populations has been studied in several... 相似文献
10.
A novel binding assay identifies high affinity ligands to the rosiglitazone binding site of mitoNEET
Geldenhuys WJ Funk MO Awale PS Lin L Carroll RT 《Bioorganic & medicinal chemistry letters》2011,21(18):5498-5501
A novel outer mitochondrial membrane protein containing [2Fe-2S] clusters, mitoNEET was first identified through its binding to the anti-diabetic drug pioglitazone. Pioglitazone belongs to a family of drugs that are peroxisome proliferator-activated receptor (PPAR) gamma agonists, collectively known as glitazones. With the lack of pharmacological tools available to fully elucidate mitoNEET's function, we developed a binding assay to probe the glitazone binding site with the aim of developing selective and high affinity compounds. We used multiple thiazolidine-2,4-dione (TZD), 2-thioxothiazolidin-4-one (TTD), and 2-iminothiazolidin-4-one (ITD) compounds to establish several trends to enhance ligand development for the purpose of elucidating mitoNEET function. 相似文献