An early history of T cell-mediated cytotoxicity.

After 60 years of intense fundamental research into T cell-mediated cytotoxicity, we have gained a detailed knowledge of the cells involved, specific recognition mechanisms and post-recognition perforin-granzyme-based and FAS-based molecular mechanisms. What could not be anticipated at the outset was how discovery of the mechanisms regulating the activation and function of cytotoxic T cells would lead to new developments in cancer immunotherapy. Given the profound recent interest in therapeutic manipulation of cytotoxic T cell responses, it is an opportune time to look back on the early history of the field. This Timeline describes how the early findings occurred and eventually led to current therapeutic applications

The sustainability of changes in agricultural technology:The carbon, economic and labour implications of mechanisation and synthetic fertiliser use

New agricultural technologies bring multiple impacts which are hard to predict. Two changes taking place in Indian agriculture are a transition from bullocks to tractors and an associated replacement of manure with synthetic fertilisers. This paper uses primary data to model social, environmental and economic impacts of these transitions in South India. It compares ploughing by bullocks or tractors and the provision of nitrogen from manure or synthetic urea for irrigated rice from the greenhouse gas (GHG), economic and labour perspective. Tractors plough nine times faster than bullocks, use substantially less labour, with no significant difference in GHG emissions. Tractors are twice as costly as bullocks yet remain more popular to hire. The GHG emissions from manure-N paddy are 30 % higher than for urea-N, largely due to the organic matter in manure driving methane emissions. Labour use is significantly higher for manure, and the gender balance is more equal. Manure is substantially more expensive as a source of nutrients compared to synthetic nutrients, yet remains popular when available. This paper demonstrates the need to take a broad approach to analysing the sustainability impacts of new technologies, as trade-offs between different metrics are common

Assessment of nutrient use in annual and perennial crops: a functional concept for analyzing nitrogen use efficiency

The use of more nutrient-efficient crops is important for maintaining yields while enhancing environmental sustainability. Various approaches are being applied to evaluate aspects of plant nutrient use efficiency, among them ecological concepts based on accumulation and losses of biomass and nutrients, agronomic concepts with a major focus on agricultural crops and harvested products, and physiological approaches assessing single physiological processes important for nutrient use. Unfortunately, the various approaches are often not compatible. Here we propose, with the example of nitrogen (N) use efficiency (NUE) of cereals, to integrate the functionally important components of NUE in a common conceptual framework. We link productivity to N in crops and seeds and consider the whole life-cycle of the crop (including seeds). Three major components of NUE are separated: The N uptake efficiency, grain-specific N efficiency and grain N concentration. The three components combine to a measure of overall NUE in terms of the N yield in harvested grain per unit of N in seed grain or soil N. The concept can be applied for both annual and perennial plants, which is demonstrated with the examples of winter wheat and a perennial energy crop (Salix) grown in Central Sweden