Bridging the Gap between Farmers and Researchers through Collaborative Experimentation. Cost and Labour Reduction in Soybean Production in South-Nyanza, Kenya

The Tropical Soil Biology and Fertility Institute of the International Centre of Tropical Agriculture (TSBF-CIAT) introduced dual purpose soybean varieties in south-west Kenya both to improve soil fertility by nitrogen fixation and to provide a source of better food and income. Since the start of the project in 2005, the Uriri Farmer Cooperative Society was successful in spreading the seeds over the district. Nevertheless, farmers still had problems with soybean agronomy. We therefore started a Collaborative Experiment (CE) Approach in March 2006 to make soybean production more accessible to farmers. The approach consisted of four stages: 1) information sessions; 2) participatory rural appraisal; 3) collaboration in the whole process of experimentation, from problem identification, to the design and analysis; 4) handing over to farmers. In this case study, farmers identified two main constraints to the recommended soybean production methods: 1) high labour requirement 2) lack of income to purchase the inputs. The results and discussions with farmers during the field days allowed demonstrating that the CE approach had been successful on two main aspects. First, CE was successful in defining problems and yield enhancing treatments which are accessible to deprived people. During field days, all farmers felt there was at least one of the treatments accessible to them. The second main success of the CE process was the increased awareness and interest about soybean. After less than a year of collaboration, farmers saw that soybean can bring a better life, cash for school fees and better health. The number of farmers registered in the soybean cooperative also increased from a few hundreds to 4500 that year. Several farmers started their own experiments to further adapt the recommendations to their own needs. The CE approach was thus successful in bridging the power-relations and knowledge gap between researchers and farmers and in designing appropriate technologies.Collaborative research, soybean, participation, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Identities and distributions of the co-invading ectomycorrhizal fungal symbionts of exotic pines in the Hawaiian Islands

Pine species have become invasive throughout the globe and threaten to replace native biota. The threat of pine invasion is particularly pressing in parts of the tropics where there are no native pines. The factors that govern pine invasion are not often well understood. However, key to pine survival is an obligate and mutualistic interaction with ectomycorrhizal fungi. Thus for pines to successfully invade new habitats compatible ectomycorrhizal fungi must already be present, or be co-introduced. The purpose of this study was to examine the community structure of non-native ectomycorrhizal fungi associated with pine invasions in the Hawaiian Islands. To accomplish this we executed a field and greenhouse study and used a molecular ecology approach to identify the fungi associating with invasive pines in Hawai‘i. We show that: (1) ectomycorrhizal fungal species richness in non-native pine plantations is far less than what is found in pine’s native range, (2) there was a significant decrease in average ectomycorrhizal fungal species richness as distance from pine plantations increased and, (3) Suillus species were the dominant fungi colonizing pines outside plantations. The keystone ectomycorrhizal fungal taxa responsible for pine establishment in Hawai‘i are within genera commonly associated with pine invasions throughout the globe. We surmise that these fungi share functional traits such as the ability for long-distance dispersal from plantations and host tree colonization via spore that lead to their success when introduced to new habitats

Predictability of marine nematode biodiversity

In this paper, we investigated: (1) the predictability of different aspects of biodiversity, (2) the effect of spatial autocorrelation on the predictability and (3) the environmental variables affecting the biodiversity of free-living marine nematodes on the Belgian Continental Shelf. An extensive historical database of free-living marine nematodes was employed to model different aspects of biodiversity: species richness, evenness, and taxonomic diversity. Artificial neural networks (ANNs), often considered as “black boxes”, were applied as a modeling tool. Three methods were used to reveal these “black boxes” and to identify the contributions of each environmental variable to the diversity indices. Since spatial autocorrelation is known to introduce bias in spatial analyses, Moran's I was used to test the spatial dependency of the diversity indices and the residuals of the model. The best predictions were made for evenness. Although species richness was quite accurately predicted as well, the residuals indicated a lack of performance of the model. Pure taxonomic diversity shows high spatial variability and is difficult to model. The biodiversity indices show a strong spatial dependency, opposed to the residuals of the models, indicating that the environmental variables explain the spatial variability of the diversity indices adequately. The most important environmental variables structuring evenness are clay and sand fraction, and the minimum annual total suspended matter. Species richness is also affected by the intensity of sand extraction and the amount of gravel of the sea bed

Mycoheterotrophic plants preferentially target arbuscular mycorrhizal fungi that are highly connected to autotrophic plants

How mycoheterotrophic plants that obtain carbon and soil nutrients from fungi are integrated in the usually mutualistic arbuscular mycorrhizal networks is unknown. Here, we compare autotrophic and mycoheterotrophic plant associations with arbuscular mycorrhizal fungi and use network analysis to investigate interaction preferences in the tripartite network. We sequenced root tips from autotrophic and mycoheterotrophic plants to assemble the combined tripartite network between autotrophic plants, mycorrhizal fungi, and mycoheterotrophic plants. We compared plant-fungal interactions between mutualistic and antagonist networks, and searched for a diamond-like module defined by a mycoheterotrophic and an autotrophic plant interacting with the same pair of fungi to investigate whether pairs of fungi simultaneously linked to plant species from each interaction type were overrepresented throughout the network. Mycoheterotrophic plants as a group interacted with a subset of the fungi detected in autotrophs but are indirectly linked to all autotrophic plants, and fungi with high overlap in autotrophic partners tend to interact with a similar set of mycoheterotrophs. Moreover, pairs of fungi sharing the same mycoheterotrophic and autotrophic plant species are overrepresented in the network. We hypothesize that the maintenance of antagonistic interactions is maximized by targeting well-linked mutualistic fungi, thereby minimizing the risk of carbon supply shortages

Revealing species assembly rules in nematode communities

Species assemblages are not randomly assembled from a local species pool; they often show segregated or aggregated distribution patterns. These patterns may be attributed to both biotic and abiotic factors. On a large scale abiotic factors may be important, while on a smaller scale other factors such as species interactions may become essential. Here we will focus on small-scale patterns in nematode communities. Species patterns are generally revealed by null models based on presence/absence data. Since there is an increasing chance of falsely rejecting the null hypothesis of a random assembled community with increasing matrix size, we used an algorithm generating independent null matrices and applied a large number of swap attempts to build a null matrix. Moreover, we applied an additional test to reveal the susceptibility of the analyses of checker and the C-, T- and Vscore to a Type I error for randomised data. To minimise the influence of the abiotic environment, we restricted the swapping algorithm of the null model to the replicate samples of one sampling event. Since stronger species interactions are expected for species of the same functional type, the nematode data was split according to the four feeding types defined by Wieser (1953). Our data indicate that species tend to aggregate and co-occur more often in some replicate samples than would be expected from a random species distribution of the local species pool. This is in accordance with the patchy distribution patterns known for nematode species. These aggregated patterns are also found for the different feeding types. The factors causing these aggregated patterns cannot be established since they are not included in the data, but the data do indicate that competitive exclusion is unlikely at the scale of a sample core

Quantifying variability in maize yield response to nutrient applications in the northern Nigeria Savanna

Open Access JournalDiagnostic on-farm nutrient omission trials were conducted over two cropping seasons (2015 and 2016) to assess soil nutrients related constraints to maize yield in the northern Nigerian savanna agro-ecological zone and to quantify their variability. Two sets of trials were conducted side by side, one with an open pollinated maize variety (OPV) and the other one with a hybrid maize variety and each set had six equal treatments laid out in 198 farmers’ fields. The treatments comprised (i) a control, (ii) a PK (‘−N,’ without N), (iii) an NK (‘−P,’ without P), (iv) an NP (‘−K,’ without K), (v) an NPK and (vi) an NPK + S + Ca + Mg + Zn + B (‘+SMM,’ NPK plus secondary macro- and micro-nutrients). Moderate to a large variability in most soil characteristics was observed in the studied fields. Consequently, cluster analysis revealed three distinct yield-nutrient response classes common for the two types of maize varieties. These define classes were fields that have (i) no-response to any nutrient, (ii) a large response to N and P and (iii) a large response to N alone. Although overall yield performance of OPV and hybrid varieties was similar, a distinct fourth class was identified for the hybrid variety, (iv) fields with a large response to N and secondary macro- and micro-nutrients. The results indicate that the large variability in soil nutrients related constraints need to be accounted for to optimize maize yield in the northern Nigerian savanna. The development of field- and area-specific fertilizer recommendations is highly needed, using simple decision support tools that consider variable soil fertility conditions and yield responses as obtained from this study

Prevalence, Risk Factors, and Clinical Relevance of Fluoroquinolone-Resistant Organisms in Rectal Cultures: Should We Target Antibiotic Prophylaxis Prior to Prostate Biopsy?

The rise of infectious complications after prostate biopsy has been linked to the growing resistance of enterobacteria to fluoroquinolone (FQ) antibiotics. In this review, we investigated the potential benefit of targeted antibiotic prophylaxis based on rectal cultures prior to prostate biopsy. An electronic search for all related literature published in English was performed from April until June 2015 using the MEDLINE and EMBASE databases. Data were obtained regarding the true prevalence of FQ-resistant bacteria in the rectum of patients, the identification of those patients at risk of harbouring FQ-resistant bacteria, the risk of infectious complications after transrectal prostate biopsy in patients with FQ-resistant bacteria, and the effect of targeted prophylaxis. Although there is limited evidence that a targeted approach might be beneficial, we conclude that current studies on the use of rectal cultures in the prebiopsy setting have too many limitations and confounding variables to definitely accept this approach in clinical practice. Whether this methodology is useful in a certain region will greatly depend on local fluoroquinolone-resistance rates

Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS