Two genes required for diabetes in BB rats: Evidence from cyclical intercrosses and backcrosses

The BB rat strain spontanteously develops diabetes mellitus which rapidly progresses to ketoacidosis and death if not treated with exogenous insulin. 40-60% of BB rats develop overt diabetes and exhibit prominent insulitis, selective pancreatic beta cell destruction, and circulating antibodies to islet cell surfaces. Diabetes can be prevented with multiple forms of immunotherapy and can be transferred with activated splenic iymphocytes. In addition to the diabetic syndrome, BB rats have a striking lymphophenia characterized by an almost total lack of circulating T cells. Colle et al., using a sequential breeding program, have described associations between the development of diabetes and the inheritance of major histocompatibility complex (MHC) 1 genes, lymphopenia, and susceptibility to pancreatic lymphocytic infiltrates

Major histocompatibility complex restriction fragment length polymorphisms define three diabetogenic haplotypes in bb and bbn rats

BB rats spontaneously develop insulin-dependent, ketosis-prone diabetes mellitus (DM)) Their disease is of autoimmune etiology, since it is characterized by: (a) lymphocytic and rnacrophage inflammation of pancreatic islets (1), (b) circulating autoantibodies that bind to pancreatic islets of Langerhans (2), (c) increased incidence of Ia antigen-bearing T lymphocytes associated with the development of diabetes (3), (d) progressive and selective destruction of insulin-producing beta ceils (1, 4), (e) the ability to transfer disease to immunodeficient animals with concanavalin A-activated splenic lymphocytes (5), and (f) selective destruction of beta cells in transplanted islets (6); in addition, it can be prevented with many forms of immunotherapy (7). BB rats also exhibit a profound T cell lymphocytopenia with an almost total lack of circulating T lymphocytes, although their thymocytes are normal in number and cell surface phenotype (8). In breeding studies, we and others (9, 10) have shown that at least two genes contribute to the development of diabetes in the BB rat. One is autosomal recessive and determines the profound T cell immunodeficiency present in affected rats at birth. The second is linked to RTI, the rat major histocompatibility complex (MHC)

The importance of long‐term experiments in agriculture: their management to ensure continued crop production and soil fertility; the Rothamsted experience

Summary Long‐term field experiments that test a range of treatments and are intended to assess the sustainability of crop production, and thus food security, must be managed actively to identify any treatment that is failing to maintain or increase yields. Once identified, carefully considered changes can be made to the treatment or management, and if they are successful yields will change. If suitable changes cannot be made to an experiment to ensure its continued relevance to sustainable crop production, then it should be stopped. Long‐term experiments have many other uses. They provide a field resource and samples for research on plant and soil processes and properties, especially those properties where change occurs slowly and affects soil fertility. Archived samples of all inputs and outputs are an invaluable source of material for future research, and data from current and archived samples can be used to develop models to describe soil and plant processes. Such changes and uses in the Rothamsted experiments are described, and demonstrate that with the appropriate crop, soil and management, acceptable yields can be maintained for many years, with either organic manure or inorganic fertilizers. Highlights Long‐term experiments demonstrate sustainability and increases in crop yield when managed to optimize soil fertility. Shifting individual response curves into coincidence increases understanding of the factors involved. Changes in inorganic and organic pollutants in archived crop and soil samples are related to inputs over time. Models describing soil processes are developed from current and archived soil data

Persistent navigation and mapping using a biologically inspired SLAM system

The challenge of persistent navigation and mapping is to develop an autonomous robot system that can simultaneously localize, map and navigate over the lifetime of the robot with little or no human intervention. Most solutions to the simultaneous localization and mapping (SLAM) problem aim to produce highly accurate maps of areas that are assumed to be static. In contrast, solutions for persistent navigation and mapping must produce reliable goal-directed navigation outcomes in an environment that is assumed to be in constant flux. We investigate the persistent navigation and mapping problem in the context of an autonomous robot that performs mock deliveries in a working office environment over a two-week period. The solution was based on the biologically inspired visual SLAM system, RatSLAM. RatSLAM performed SLAM continuously while interacting with global and local navigation systems, and a task selection module that selected between exploration, delivery, and recharging modes. The robot performed 1,143 delivery tasks to 11 different locations with only one delivery failure (from which it recovered), traveled a total distance of more than 40 km over 37 hours of active operation, and recharged autonomously a total of 23 times

Regional, three-dimensional assessment of the ozone formation potential of organic compounds

A direct sensitivity analysis technique was used for three-dimensional atmospheric ozone formation potential (also termed reactivity) assessment in central California. Spatially and temporally resolved absolute and relative reactivities of 31 organic compounds and CO were calculated. In order to compare different species, the emissions of all the targeted organic compounds were perturbed equally. This perturbation followed the same spatial distribution as the total anthropogenic VOC emissions. Despite the variability (both spatial and temporal) in the absolute values, relative reactivities were fairly constant. Different types of domain-wide reactivity metrics were considered. All the three-dimensional metrics showed a high level of inter-species consistency among them and had a low day-to-day variability. Domain-wide metrics were comparable with box model scales, but showed a less dynamic inter-species behavior. Ranking of the three-dimensional metrics was very similar to the box model scales. It was also found that including the biogenic VOC emissions in the perturbation pattern has little effect on the results. Finally, local relative reactivities for six sites were fairly consistent in ranking but more variable than the domain-wide metrics