Xrp1 and Irbp18 trigger a feed-forward loop of proteotoxic stress to induce the loser status

Cell competition induces the elimination of less-fit “loser” cells by fitter “winner” cells. In Drosophila, cells heterozygous mutant in ribosome genes, Rp/+, known as Minutes, are outcompeted by wild-type cells. Rp/+ cells display proteotoxic stress and the oxidative stress response, which drive the loser status. Minute cell competition also requires the transcription factors Irbp18 and Xrp1, but how these contribute to the loser status is partially understood. Here we provide evidence that initial proteotoxic stress in RpS3/+ cells is Xrp1-independent. However, Xrp1 is sufficient to induce proteotoxic stress in otherwise wild-type cells and is necessary for the high levels of proteotoxic stress found in RpS3/+ cells. Surprisingly, Xrp1 is also induced downstream of proteotoxic stress, and is required for the competitive elimination of cells suffering from proteotoxic stress or overexpressing Nrf2. Our data suggests that a feed-forward loop between Xrp1, proteotoxic stress, and Nrf2 drives Minute cells to become losers

The potential of coffee stems gasification to provide bioenergy for coffee farms:a case study in the Colombian coffee sector

The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas

Proteotoxic stress is a driver of the loser status and of cell competition

Cell competition allows “winner” cells to eliminate less fit “loser” cells in tissues. In Minute cell competition, cells heterozygous mutant in ribosome genes, such as RpS3 (+/-) cells, are eliminated by wild-type cells. How cells are primed as losers is partially understood and it has been proposed that reduced translation underpins the loser status of ribosome mutant, or Minute, cells. Here, using Drosophila, we show that reduced translation does not cause cell competition. Instead, we identify proteotoxic stress as the underlying cause of the loser status for Minute competition and competition induced by mahjong, an unrelated loser gene. RpS3 (+/-) cells exhibit reduced autophagic and proteasomal flux, accumulate protein aggregates, and can be rescued from competition by improving their proteostasis. Conversely, inducing proteotoxic stress is sufficient to turn otherwise wild-type cells into losers. Thus, we propose that tissues may preserve their health through a proteostasis-based mechanism of cell competition and cell selection

Proteotoxic stress is a driver of the loser status and cell competition.

Cell competition allows winner cells to eliminate less fit loser cells in tissues. In Minute cell competition, cells with a heterozygous mutation in ribosome genes, such as RpS3+/- cells, are eliminated by wild-type cells. How cells are primed as losers is partially understood and it has been proposed that reduced translation underpins the loser status of ribosome mutant, or Minute, cells. Here, using Drosophila, we show that reduced translation does not cause cell competition. Instead, we identify proteotoxic stress as the underlying cause of the loser status for Minute competition and competition induced by mahjong, an unrelated loser gene. RpS3+/- cells exhibit reduced autophagic and proteasomal flux, accumulate protein aggregates and can be rescued from competition by improving their proteostasis. Conversely, inducing proteotoxic stress is sufficient to turn otherwise wild-type cells into losers. Thus, we propose that tissues may preserve their health through a proteostasis-based mechanism of cell competition and cell selection

Adaptation to the Edge of Chaos in the Self-Adjusting Logistic Map

Self-adjusting, or adaptive systems have gathered much recent interest. We present a model for self-adjusting systems which treats the control parameters of the system as slowly varying, rather than constant. The dynamics of these parameters is governed by a low-pass filtered feedback from the dynamical variables of the system. We apply this model to the logistic map and examine the behavior of the control parameter. We find that the parameter leaves the chaotic regime. We observe a high probability of finding the parameter at the boundary between periodicity and chaos. We therefore find that this system exhibits adaptation to the edge of chaos.Comment: 3 figure

Defining Polio: Closing the Gap in Global Surveillance

Background: By late 2012 the Global Polio Eradication Initiative (GPEI) had nearly eradicated this ancient infectious disease. Successful surveillance programs for acute flaccid paralysis however rely on broad governmental support for implementation. With the onset of conflict, public health breakdown has contributed to the resurgence of polio in a number of regions. The current laboratory based case definition may be a contributory factor in these regions. Objective: We sought to compare case definition rates using strict laboratory based criteria to rates obtained using the clinical criteria in modern day Syria. We also sought to examine this distribution of cases by sub-region. Methods: We examined the World Health Organization (WHO) reported figures for Syria from 2013–2014 using laboratory based criteria. We compared these with cases obtained when clinical criteria were applied. In addition we sought data from the opposition controlled Assistance Coordination Unit which operates in non-Government controlled areas where WHO data maybe incomplete. Cases were carefully examined for potential overlap to avoid double reporting. Findings: Whilst the WHO data clearly confirmed the polio outbreak in Syria, it did so with considerable delay and with under reporting of cases, particularly from non-government controlled areas. In addition, laboratory based case definition led to a substantial underestimate of polio (36 cases) compared with those found with the clinically compatible definition (an additional 46 cases). Rates of adequate diagnostic specimens from suspected cases are well below target, no doubt reflecting the effect of conflict in these areas. Conclusions: We have identified a gap in the surveillance of polio, a global threat. The current laboratory based definition, in the setting of conflict and insecurity, leads to under diagnosis of polio with potential delays and inadequacies in coordinating effective responses to contain outbreaks and eradicate polio. Breakdown in public health measures as a contributing factor is likely to result in a resurgence of previously controlled infectious diseases. The clinical definition should be reinstituted to supplement the lab-based definition

The potential of coffee stems gasification to provide bioenergy for coffee farms: a case study in the Colombian coffee sector

From Springer Nature via Jisc Publications RouterHistory: received 2019-04-24, rev-recd 2019-07-01, registration 2019-07-15, accepted 2019-07-15, pub-electronic 2019-08-03, online 2019-08-03, pub-print 2020-12Publication status: PublishedFunder: Fondo de CTeI del Sistema General de Regalías del Departamento del Atlántico; Grant(s): Doctoral scholarship call 673 of 2014 “Formación de Capital Humano de Alto Nivel para el Departamento del Atlántico”Abstract: The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas