Dried blood spots (DBS) on filter paper are widely used for serological diagnosis because they require minimal blood volumes and enable storage and transport without refrigeration, making them particularly useful in remote and resource-limited settings. However, DBS-based serology may be compromised by methodological variability and the lack of standardized preservation protocols. We evaluated the effects of preservation factors and quality indicators on DBS serological performance for Toxoplasma gondii, a pathogen with a broad host range and limited seasonal variability. We analyzed 787 dB samples from 17 mammal species collected by subsistence hunters in an Indigenous community in the northern Peruvian Amazon between 2008 and 2020. Recorded variables included filter paper type, time to cold-chain initiation, time to analysis, blood saturation, fungal contamination, and colorimetric values of reconstituted blood. Linear models with Type II ANOVA and AIC-based model selection were used to identify factors associated with seropositivity. Filter paper type was the primary determinant of serological outcomes, while severe fungal contamination was associated with reduced seropositivity. Colorimetric values were significantly related to serological results and may serve as a simple indicator of sample quality. These findings highlight the importance of standardized preservation protocols to minimize false negatives under tropical conditions. DBS-based serological studies should prioritize Protein Saver cards, limit fungal growth, and incorporate basic quality assessments to improve the reliability of wildlife disease surveillance within a One Health framework.
Tag: contamination
Interactions between regenerative strategies and edaphic, climatic and topographic factors mediate mitigation or exacerbation of soil and crop toxicity in global cadmium contaminated lands
Cadmium (Cd) contamination in agroecosystems is a global concern, due to its negative influence on soil health and crop performance. Regenerative strategies have been widely recognised as vital to improve soil quality and crop yields. Yet strategies are needed that also mitigate rather than exacerbate the impacts of Cd contamination. In this context, interactions between regenerative strategies, and edaphic, climatic and topographic factors are poorly understood. This study presents a meta-analysis with effect size statistics, evaluating the interactions between regenerative strategies (biochar, manure and compost), non- regenerative strategies (sewage-sludge and fertilizer), soil properties (pH, SOM and Cd levels), climatic factors (temperature and precipitation), and elevation. In acidic or high SOM soils, fertilizer increased Cd uptake by 50% to 76%. However, biochar or compost addition in these soils reduced Cd uptake. Under high Cd contamination, biochar application increased shoot biomass, but fertilizer application decreased shoot-biomass. The application of fertilizer or sewage-sludge under higher temperatures increased Cd uptake, whereas biochar reduced Cd uptake. At wet sites, fertilizer addition increased soil Cd accumulation. At high elevations, biochar was more effective than manure at reducing Cd accumulation. We conclude that there are complex interactions between regenerative strategies and environmental conditions; determining impacts on soil and crop health. The interactions between environmental factors and use of sewage-sludge or fertilizer could exacerbate soil and plant Cd toxicity. Regenerative strategies, especially biochar, could mitigate Cd toxicity in agroecosystems.
Environmental implications of high metal content in soils of a titanium mining zone in Kenya
Mining activities contribute to an increase of specific metal contaminants in soils. This may adversely affect plant life and consequently impact on animal and human health. The objective of this study was to obtain the background metal concentrations in soils around the titanium mining in Kwale County for monitoring its environmental impacts. Forty samples were obtained with half from topsoils and the other from subsoils. X-ray fluorescence spectrometry was used to determine the metal content of the soil samples. High concentrations of Ti, Mn, Fe, and Zr were observed where Ti concentrations ranged from 0.47 to 2.8 %; Mn 0.02 to 3.1 %; Fe 0.89 to 3.1 %; and Zr 0.05 to 0.85 %. Using ratios of elemental concentrations in topsoil to subsoil method and enrichment factors concept, the metals were observed to be of geogenic origin with no anthropogenic input. The high concentrations of Mn and Fe may increase their concentration levels in the surrounding agricultural lands through deposition, thereby causing contamination on the land and the cultivated food crops. The latter can cause adverse human health effects. In addition, titanium mining will produce tailings containing low-level titanium concentrations, which will require proper disposal to avoid increasing titanium concentrations in the soils of the region since it has been observed to be phytotoxic to plants at high concentrations. The results of this study will serve as reference while monitoring the environmental impact by the titanium mining activities. © 2016, Springer-Verlag Berlin Heidelberg.
Early recognition of graft compatibility in Uapaca kirkiana Müell Arg. clones, provenances and species
Examination of callus micro-grafts in Uapaca kirkiana Müell Arg. was carried out with the objective of determining early signs of graft compatibility. Leaves from U. kirkiana, U. nitida and Jatropha curcas trees were used for callus induction. Two pieces of callus were co-cultured on Murashige and Skoog (MS) medium with different supplements. Co-cultured calli were embedded in paraffin wax and dissected. The specimens were stained in safranin and fast green before viewing under a light microscope. Results showed that MS medium with 0.1 mg l-1 thidiazuron (TDZ) and 0.5 mg l-1 naphthaleneacetic acid (NAA) or 1.0 mg l-1 dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l-1 NAA was effective for callus induction. There were no necrotic layers at the unions within U. kirkiana clones and provenances, but a differential growth (irregularity) between U. kirkiana and U. nitida co-cultured calli. Phenol deposits were observed at the union interfaces of U. kirkiana combinations and were high on calli derived from mature trees. Phenol deposits were absent at the union of J. curcas heterografts. Necrotic layers developed at the unions of U. kirkiana and J. curcas micro-grafts and indicating an outright graft incompatibility. Accumulation of phenol deposits at the union interfaces inhibited graft compatibility in many U. kirkiana combinations. Callus fusion technique can be used to identify partners with an outright graft incompatibility, especially for distant related plant species
Agriculture’s Contribution to Nitrate Contamination of Californian Groundwater (1945–2005)
Nitrogen (N) use in intensive agriculture can degrade groundwater resources. However, considerable time lags between groundwater recharge and extraction complicate source attribution and remedial responses. We construct a historic N mass balance of two agricultural regions of California to understand trends and drivers of past and present N loading to groundwater (1945–2005). Changes in groundwater N loading result from historic changes in three factors: the extent of agriculture (cropland area and livestock herd increased 120 and 800%, respectively), the intensity of agriculture (synthetic and manure waste effluent N input rates increased by 525 and 1500%, respectively), and the efficiency of agriculture (crop and milk production per unit of N input increased by 25 and 19%, respectively). The net consequence has been a greater-than-order-of-magnitude increase in nitrate (NO3) loading over the time period, with 163 Gg N yr1 now being leached to groundwater from approximately 1.3 million ha of farmland (not including alfalfa [Medicago sativa L.]). Meeting safe drinking water standards would require NO3 leaching reductions of over 70% from current levels through reductions in excess manure applications, which accounts for nearly half of all groundwater N loading, and through synthetic N management improvements. This represents a broad challenge given current economic and technical conditions of California farming if farm productivity is to be maintained. The findings illustrate the growing tension—characteristic of agricultural regions globally—between intensifying food, feed, fiber, and biofuel production and preserving clean water.
Rhizospheric microbiomics integrated with plant transcriptomics provides insight into the Cd response mechanisms of the newly identified Cd accumulator Dahlia pinnata
Phytoremediation that depends on excellent plant resources and effective enhancing measures is important for remediating heavy metal-contaminated soils. This study investigated the cadmium (Cd) tolerance and accumulation characteristics of Dahlia pinnata Cav. to evaluate its Cd phytoremediation potential. Testing in soils spiked with 5–45 mg kg–1 Cd showed that D. pinnata has a strong Cd tolerance capacity and appreciable shoot Cd bioconcentration factors (0.80–1.32) and translocation factors (0.81–1.59), indicating that D. pinnata can be defined as a Cd accumulator. In the rhizosphere, Cd stress (45 mg kg–1 Cd) did not change the soil physicochemical properties but influenced the bacterial community composition compared to control conditions. Notably, the increased abundance of the bacterial phylum Patescibacteria and the dominance of several Cd-tolerant plant growth–promoting rhizobacteria (e.g., Sphingomonas, Gemmatimonas, Bryobacter, Flavisolibacter, Nocardioides, and Bradyrhizobium) likely facilitated Cd tolerance and accumulation in D. pinnata. Comparative transcriptomic analysis showed that Cd significantly induced (P < 0.001) the expression of genes involved in lignin synthesis in D. pinnata roots and leaves, which are likely to fix Cd2+ to the cell wall and inhibit Cd entry into the cytoplasm. Moreover, Cd induced a sophisticated signal transduction network that initiated detoxification processes in roots as well as ethylene synthesis from methionine metabolism to regulate Cd responses in leaves. This study suggests that D. pinnata can be potentially used for phytoextraction and improves our understanding of Cd-response mechanisms in plants from rhizospheric and molecular perspectives.
Use of biochar and Moringa oleifera in greywater treatment to remove heavy metals and contaminants of emerging concern
This study investigated the combination of biochar derived from carbonized local feedstock and Moringa oleifera seed extract-based flocculant, a novel combination in the context of greywater treatment missed in the previous studies, with a focus on the removal of organic contaminants (caffeine, chloramphenicol, trimethoprim, carbamazepine, diclofenac, and bisphenol A) and heavy metals (Cr(VI), As(III), Co(II), Ni(II), Cu(II), Zn(II), and Pb(II)). The research focused on the optimization of dosage, application procedure, and relevance to greywater (presence of humic acids, clay, and surfactants).
Ectomycorrhizal Mushrooms as a Natural Bio-Indicator for Assessment of Heavy Metal Pollution
Environmental changes and heavy metal pollution are some of the consequences of anthropogenic activities. Many ecosystems, including edaphic ecosystems, suffer from the effects of pollution. The accurate assessment of soil heavy metal contamination leads to better approaches for remediating soils. The exploration of different ways, including biological methods, to conduct environmental monitoring is still ongoing. Here, we focus on reviewing the potential of ectomycorrhizal fungi as a natural indicator of soil heavy metal pollution. Mycorrhizal fungi fulfill basic criteria required as natural bio-indicators for heavy metal contamination. These fungi use different mechanisms such as avoidance and tolerance to survive in metalliferous soils. Thus, we promote ectomycorrhizal fungi as natural indicators. This review also synthesizes existing research on ectomycorrhizal mushrooms as natural bio-indicators for heavy metal pollution and the elaboration of mechanisms, by which ectomycorrhizal fungi meet the criteria required for a successful bio-indicator.