Diagnosis for ecological intensification of maize-based smallholder farming systems in the Costa Chica, Mexico

Enhanced utilization of ecological processes for food and feed production as part of the notion of ecological intensification starts from location-specific knowledge of production constraints. A diagnostic systems approach which combined social-economic and production ecological methods at farm and field level was developed and applied to diagnose extent and causes of the perceived low productivity of maize-based smallholder systems in two communities of the Costa Chica in South West Mexico. Social-economic and production ecological surveys were applied and complemented with model-based calculations. The results demonstrated that current nutrient management of crops has promoted nutrition imbalances, resulting in K- and, less surprisingly N-limited production conditions, reflected in low yields of the major crops maize and roselle and low resource use efficiencies. Production on moderate to steep slopes was estimated to result in considerable losses of soil and organic matter. Poor crop production, lack of specific animal fodder production systems and strong dependence on animal grazing within communal areas limited recycling of nutrients through manure. In combination with low prices for the roselle cash crop, farmers are caught in a vicious cycle of cash shortage and resource decline. The production ecological findings complemented farmers opinions by providing more insight in background and extent of livelihood constraints. Changing fertilizer subsidies and rethinking animal fodder production as well as use of communal lands requires targeting both formal and informal governance structures. The methodology has broader applicability in smallholder systems in view of its low demand on capital intensive resource

Exploring the potential for improved internal nutrient cycling in dairy farming systems, using an eco-mathematical model

Nutrient management at Dutch dairy farms is changing rapidly from strong reliance on external inputs to more prudent utilization of internal resources. This paper explores opportunities and constraints arising from this shift towards eco-technological management. A mathematical model of inorganic and organic nitrogen (N) flows in a dairy farming system was formulated based on ecological concepts, integrating processes of nutrient input, recycling, immobilization and mineralization. Recycling is defined as the mineralization of N within the year of its incorporation into herbage, which occurs through release from faeces, animal urine and non-harvested biomass. We simulated changes in inorganic and organic N per hectare, and the consequent emission (E), mineralization (MS) and recycling (R) of N for different initial amounts of inorganic and organic N. Results demonstrate that in the long term, the system evolves to equilibrium amounts of inorganic and organic N, which are strongly determined by the imposed management practices, such as fertilizer input and grassland management. In the short term, moving away from the equilibrium is possible for particular initial amounts of inorganic and organic N. In the equilibrium state, E was reduced by lowering inorganic fertilizer input rate, increasing grassland productivity and improving animal N conversion efficiency, i.e., only by production-related parameters. Only in the short term E was affected by adjustments in quality-related parameters: lower N content, lower digestibility of herbage, reduced degradability of non-harvested biomass and faeces, and parameters determining the functioning of soil biota (degradation rate, efficiency, C/N ratio). Qualityrelated parameters had no effect on internal nutrient cycling in the equilibrium state, because adjustments in MS were completely compensated by changes in R. A comparison of farming systems demonstrated that farming systems can be designed in such a way that improvement of internal nutrient cycling supports the same production with lower inputs and lower emissions

Een natuurgebied inrichten op particulier terrein

Artikel over herinrichting van een gebied met een tweeledig doel: een bloemenweide maken die de bijen- en vlinderstand helpt verbeteren en aantrekkelijk is voor de mensen die in het huis verblijven en het onderhoud beperken tot een paar maal per jaar, omdat de eigenaren er zelf niet altijd zijn

Quantification of Cre-mediated recombination by a novel strategy reveals a stable extra-chromosomal deletion-circle in mice

<p>Abstract</p> <p>Background</p> <p>Inducible conditional knockout animals are widely used to get insight in the function of genes and the pathogenesis of human diseases. These models frequently rely on Cre-mediated recombination of sequences flanked by Lox-P sites. To understand the consequences of gene disruption, it is essential to know the efficiency of the recombination process.</p> <p>Results</p> <p>Here, we describe a modification of the multiplex ligation-dependent probe amplification (MLPA), called extension-MLPA (eMLPA), which enables quantification of relatively small differences in DNA that are a consequence of Cre-mediated recombination. eMLPA, here applied on an inducible <it>Pkd1 </it>conditional deletion mouse model, simultaneously measures both the reduction of the floxed allele and the increase of the deletion allele in a single reaction thereby minimizing any type of experimental variation. Interestingly, with this method we were also able to observe the presence of the excised DNA fragment. This extra-chromosomal deletion-circle was detectable up to 5 months after activation of Cre.</p> <p>Conclusion</p> <p>eMLPA is a novel strategy which easily can be applied to measure the Cre-mediated recombination efficiency in each experimental case with high accuracy. In addition the fate of the deletion-circle can be followed simultaneously.</p

Renal Normothermic Machine Perfusion:The Road Toward Clinical Implementation of a Promising Pretransplant Organ Assessment Tool

The increased utilization of high-risk renal grafts for transplantation requires optimization of pretransplant organ assessment strategies. Current decision-making methods to accept an organ for transplantation lack overall predictive power and always contain an element of subjectivity. Normothermic machine perfusion (NMP) creates near-physiological conditions, which might facilitate a more objective assessment of organ quality prior to transplantation. NMP is rapidly gaining popularity, with various transplant centers developing their own NMP protocols and renal viability criteria. However, to date, no validated sets of on-pump viability markers exist nor are there unified NMP protocols. This review provides a critical overview of the fundamentals of current renal NMP protocols and proposes a framework to approach further development of ex vivo organ evaluation. We also comment on the potential logistical implications of routine clinical use of NMP, which is a more complex procedure compared to static cold storage or even hypothermic machine perfusion. Supplemental Visual Abstract; http://links.lww.com/TP/C232

Ex Situ Dual Hypothermic Oxygenated Machine Perfusion for Human Split Liver Transplantation

Liver splitting allows the opportunity to share a deceased graft between 2 recipients but remains underutilized. We hypothesized that liver splitting during continuous dual hypothermic oxygenated machine perfusion (DHOPE) is feasible, with shortened total cold ischemia times and improved logistics. Here, we describe a left lateral segment (LLS) and extended right lobe (ERL) liver split procedure during continuous DHOPE preservation with subsequent transplantation at 2 different centers. Methods: After transport using static cold storage, a 51-year-old brain death donor liver underwent end-ischemic DHOPE. During DHOPE, the donor liver was maintained 106 kPa. An ex situ ERL/LLS split was performed with continuing DHOPE throughout the procedure to avoid additional ischemia time. Results: Total cold ischemia times for the LLS and ERL were 205 minutes and 468 minutes, respectively. Both partial grafts were successfully transplanted at 2 different transplant centers. Peak aspartate aminotransferase and alanine aminotransferase were 172 IU/L and 107 IU/L for the LLS graft, and 839 IU/L and 502 IU/L for the ERL graft, respectively. The recipient of the LLS experienced an episode of acute cellular rejection. The ERL transplantation was complicated by severe acute pancreatitis with jejunum perforation requiring percutaneous drainage and acute cellular rejection. No device-related adverse events were observed. Conclusions: Liver splitting during continuous DHOPE preservation is feasible, has the potential to substantially shorten cold ischemia time and may optimize transplant logistics. Therefore liver splitting with DHOPE can potentially improve utilization of split liver transplantation

Magnetic resonance imaging assessment of renal flow distribution patterns during ex vivo normothermic machine perfusion in porcine and human kidneys

Acceptance criteria of deceased donor organs have gradually been extended toward suboptimal quality, posing an urgent need for more objective pre-transplant organ assessment. Ex vivo normothermic machine perfusion (NMP) combined with magnetic resonance imaging (MRI) could assist clinicians in deciding whether a donor kidney is suitable for transplantation. Aim of this study was to characterize the regional distribution of perfusate flow during NMP, to better understand how ex vivo kidney assessment protocols should eventually be designed. Nine porcine and 4 human discarded kidneys underwent 3 h of NMP in an MRI-compatible perfusion setup. Arterial spin labeling scans were performed every 15 min, resulting in perfusion-weighted images that visualize intrarenal flow distribution. At the start of NMP, all kidneys were mainly centrally perfused and it took time for the outer cortex to reach its physiological dominant perfusion state. Calculated corticomedullary ratios based on the perfusion maps reached a physiological range comparable to in vivo observations, but only after 1 to 2 h after the start of NMP. Before that, the functionally important renal cortex appeared severely underperfused. Our findings suggest that early functional NMP quality assessment markers may not reflect actual physiology and should therefore be interpreted with caution