The Decline of the Cow: Agricultural and Settlement Change in Early Medieval Ireland

This article considers cows and dairying as the basis a17of value system in early societies, particularly in Ireland. Only in a very few instances is it possible to demonstrate that such systems existed. When it does, it can be shown that cows and dairying were imbedded in the social or religious institutions of these cultures. Cattle had a value and meaning much greater than their economic worth in terms of food, hides, tallow etc. Such a systems, however, does not allow economic development as dairy produce does not easily lend itself to the production, and accumulation, of significant surplus nor is dairy produce particularly suitable for economic expansion based on trade. Its perishable nature militates against both roles. In order to develop political power that is based on economic power and wealth it is necessary to change the emphasis from livestock to cereal production.

Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis

Several insect species show an increase in cuticular melanism in response to high densities. In some species, there is evidence that this melanism is correlated with an up-regulation of certain immune system components, particularly phenoloxidase (PO) activity, and with the down-regulation of lysozyme activity, suggesting a trade-off between the two traits. As melanism has a genetic component, we selected both melanic and nonmelanic lines of the phase-polyphenic lepidopteran, Spodoptera littoralis, in order to test for a causative genetic link between melanism, PO activity and lysozyme activity, and to establish if there are any life-history costs associated with the melanic response. We found that, in fact, melanic lines had lower PO activity and higher lysozyme activity than nonmelanic lines, confirming a genetic trade-off between the two immune responses, but also indicating a genetic trade-off between melanism and PO activity. In addition, we found that lines with high PO activity had slower development rates suggesting that investment in PO, rather than in melanism, is costly.

Costs of resistance: genetic correlations and potential trade-offs in an insect immune system

Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.

Do minimum wages raise employment? Evidence from the US retail-trade sector

This paper examines the impact of minimum wages on earnings and employment in selected branches of the retail-trade sector, 1990-2005, using county-level data on employment and a panel regression framework that allows for county-specific trends in sectoral outcomes. We focus on specific subsectors within retail trade that are identified as particularly low-wage. We find little evidence of disemployment effects once we allow for geographic-specific trends. Indeed, in many sectors the evidence points to modest (but robust) positive employment effects. (C) 2009 Elsevier B.V. All rights reserved.

Comparison of three adjuvants used to produce polyclonal antibodies to veterinary drugs

Two commercially available adjuvants, Gerbu LQ 3000 and Montanide ISA 50V, were assessed as potential replacements for Freund's adjuvant by evaluating their efficacy in the production of polyclonal antibodies to veterinary drugs in rabbits. The aim was to find an adjuvant that could produce a similar (or enhanced) immune response in the host animal without the undesirable side effects associated with Freund's complete and incomplete adjuvant. The assessment involved the examination of each injection site and the characterisation of the resultant antibodies with regards to antibody titre and sensitivity. It was found that the rabbits immunised with Gerbu adjuvant produced some of the most sensitive antibodies. However, titres were relatively low and adverse effects at injection sites were relatively common. Montanide adjuvant produced no adverse effects and the related antibodies were found to be of adequate sensitivity when compared to those from rabbits immunised with Freund's. It was concluded that Montanide ISA 50V could be considered as a suitable replacement to Freund's for the production of polyclonal antibodies, to low molecular weight compounds in rabbits. (C) 2007 Elsevier B.V. All rights reserved.

Use of antigen mimics to produce specific antibodies to anti-coccidial drugs

A range of polyclonal antibodies was successfully produced to the coccidiostatic drugs diclazuril and robenidine. Initial attempts to make immunogenic complexes of both drugs were ineffective due to difficulties encountered while trying to couple the compounds to large carrier proteins. Structural mimics, which could act as haptens for each drug, were sought and identified. The compounds identified were more open to chemical manipulation and were conjugated to carrier proteins to produce effective immunogens. The most sensitive antisera produced displayed IC(50)s of 1.5 ng/ml and 13 ng/ml for diclazuril and robenidine respectively. The antibody for diclazuril was shown to be specific, cross-reacting only with clazuril by 15%. The robenidine antibody displayed a low cross-reactivity of 1.2% to the compound used to produce the antibody. (C) 2007 Elsevier B.V. All rights reserved.

Macronutrient balance mediates trade-offs between immune function and life history traits

1. Diet and health are intimately linked and recent studies have found that caloric restriction can affect immune function. However, when given a choice between diets that differ in their macronutrient composition, pathogen-infected individuals can select a diet that improves their survival, suggesting that the nutritional composition of the diet, as well as its calorie content, can play a role in defence against disease. Moreover, as individuals change their diet when infected, it suggests that a diet that is optimal for growth is not optimal for immunity, leading to trade-offs.
2. Currently, our knowledge of the effects of diet on immunity is limited because previous experiments have manipulated either single nutrients or the calorie content of the diet without considering their interactive effects. By simultaneously manipulating both the diet composition (quality) and its caloric density (quantity), in both naive and immune-challenged insects, we asked how do diet quality and quantity influence an individual's ability to mount an immune response? And to what extent are allocation trade-offs driven by quantity- versus quality-based constraints?
3. We restricted individuals to 20 diets varying in their protein and carbohydrate content and used 3D response surfaces to visualize dietary effects on larval growth and immune traits. Our results show that both constitutive and induced immune responses are not limited by the total quantity of nutrients consumed, but rather different traits respond differently to variation in the ratios of macronutrients (diet quality), and peak in different regions of macronutrient space. The preferred dietary composition therefore represents a compromise between the nutritional requirements of growth and immune responses. We also show that a non-pathogenic immune challenge does not affect diet choice, rather immune-challenged insects modify their allocation of nutrients to improve their immune response.
4. Our results indicate that immune traits are affected by the macronutrient content of the diet and that no diet can simultaneously optimize all components of the immune system. To date the emphasis has been on the effects of micronutrients in improving immunity, our findings indicate that this must be widened to include the neglected impact of macronutrients on defence against disease.