Evaluation of in-vessel co-composting of yard waste and development of kinetic models for co-composting

BackgroundOrganic solid waste management is a major challenge in high population density areas like apartments, educational institutions, hospitals, etc., as their disposal with other wastes could not only lead to issues like vector menace, odour generation but also would lead to loss of resources that could be reused such as nutrients which will benefit soil. In places like educational institutions, the major portion of waste generated is organic waste, especially food waste and yard waste from the campus, apart from paper waste. Composting is an organic waste treatment method that is cost effective and leads to resource recovery. In this study, the characteristics of composting of yard waste and co-composting of yard waste with wastes generated in an institution (university campuses of Anna University, Chennai, India) are examined. The composts were characterized in terms of total solids, volatile solids, pH, electrical conductivity, carbon: nitrogen (C:N) ratio and total Kjeldahl nitrogen. The stability index and germination index of the compost were assessed.ResultsThe C:N ratio of all the different composts (except the one generated from yard with canteen waste consisting of vegetable waste) produced in this study has a value less than 30:1, which satisfies the basic requirements for the compost. It was also observed that the mature compost from these feedstocks did not have heavy metals at toxic levels.ConclusionThis study demonstrated that the co-composting of yard wastes with paper and canteen wastes (fruit, coffee grounds, tea leaf waste) could produce value-added products. In addition to that, kinetic models were developed to predict the decomposition rate constant of the process

Sustained translational repression by eIF2α-P mediates prion neurodegeneration

The mechanisms leading to neuronal death in neurodegenerative disease are poorly understood. Many of these disorders, including Alzheimer's, Parkinson's and prion diseases, are associated with the accumulation of misfolded disease-specific proteins. The unfolded protein response is a protective cellular mechanism triggered by rising levels of misfolded proteins. One arm of this pathway results in the transient shutdown of protein translation, through phosphorylation of the α-subunit of eukaryotic translation initiation factor, eIF2. Activation of the unfolded protein response and/or increased eIF2α-P levels are seen in patients with Alzheimer's, Parkinson's and prion diseases, but how this links to neurodegeneration is unknown. Here we show that accumulation of prion protein during prion replication causes persistent translational repression of global protein synthesis by eIF2α-P, associated with synaptic failure and neuronal loss in prion-diseased mice. Further, we show that promoting translational recovery in hippocampi of prion-infected mice is neuroprotective. Overexpression of GADD34, a specific eIF2α-P phosphatase, as well as reduction of levels of prion protein by lentivirally mediated RNA interference, reduced eIF2α-P levels. As a result, both approaches restored vital translation rates during prion disease, rescuing synaptic deficits and neuronal loss, thereby significantly increasing survival. In contrast, salubrinal, an inhibitor of eIF2α-P dephosphorylation, increased eIF2α-P levels, exacerbating neurotoxicity and significantly reducing survival in prion-diseased mice. Given the prevalence of protein misfolding and activation of the unfolded protein response in several neurodegenerative diseases, our results suggest that manipulation of common pathways such as translational control, rather than disease-specific approaches, may lead to new therapies preventing synaptic failure and neuronal loss across the spectrum of these disorders. © 2012 Macmillan Publishers Limited. All rights reserved