Abstract. Measurement of insect immune effector system function aimed at identifying costs has largely been stimulated by the ideas of Hamilton & Zuk (1982), who proposed that choosy females may derive some genetic benefit from selecting parasite-resistant males. Field studies of such systems assume that most variation in measured immune traits is affected strongly by genes and pay little attention subsequently to the role of nutritional status in determining the magnitude of assayed immune effector systems. In this paper the effects of nutrient deprivation on immune function are measured in the mealworm beetle (Tenebrio molitor L.) reared in otherwise ideal conditions. The results suggest that immune effector system function is down-regulated during short-term nutritional deprivation, but is rapidly up-regulated to pre-deprivation levels after animals are allowed access to food. This rapid modulation of immune function in the context of nutritional status has important implications for measuring immune function in the field, as well as the interpretation of those measures.

Central to the conceptual basis of ecological immunity is the notion that immune effector systems are costly to produce, run, and ⁄ or maintain. Using the mealworm beetle, Tenebrio molitor, as a model we investigated two aspects of the costs of innate immunity. We conducted an experiment designed to identify the cost of an induced immune response, and the cost of constitutive investment in immunity, as well as potential interactions. The immune traits under consideration were the encapsulation response and prophylactic cuticular melanization, which are mechanistically linked by the melaninproducing phenoloxidase cascade. If immunity is costly, we predicted reduced longevity and ⁄ or fecundity as a consequence of investment in either immune trait. We found a measurable longevity cost associated with producing an inducible immune response (encapsulation). In contrast to other studies, this cost was expressed under ad libitum feeding conditions. We found no measurable costs for constitutive investment in immunity (prophylactic investment in cuticular colour).

Accurate estimates of HLA-A, B, DR and DQ phenotype, gene and haplotype frequencies (HF) in the normal population are of importance in, for example, disease susceptibility studies, platelet transfusion support and transplantation. HLA population genetics studies have been performed on numerous groups, however, no major studies have been carried out on the population of Wales. As part of the validation process for our routine HLA-A and B typing by PCR using sequence-specific primers (PCR-SSP) we examined 1,798 normal, unrelated Caucasoid blood donors living in Wales and recruited onto the Welsh Bone Marrow Donor Registry (WBMDR). Typing was performed by serology (HLA-A, B) and PCR-SSP at low resolution (HLA-A, B, DR, DQ) resulting in a particularly rigorous level of HLA specificity assignment. Four discrepancies were found between the HLA-A and B serological and PCR-SSP specificity assignments: (1) two instances of HLA-A2 by serology were undetected by PCR-SSP and were a new HLA-A2 allele – A*0224; (2) one example of HLA-B*15 by PCR-SSP failed to react by serology, and remained undetectable by serology in subsequent samples, and (3) one example of HLA-B45 by serology was identified as HLA-B*5002 by PCR-SSP. Hardy-Weinberg and homozygosity analysis showed that the goodness-of-fit was excellent (p > 0.05), for both phenotype distribution and the number of homozygotes identified, for all four loci. The phenotype and gene frequencies for the 18 HLA-A, 34 -B, 15 -DR and 8 -DQ specificities identified and two- and three-locus HF, linkage disequilibrium and related values for HLA-A/B, B/DR, DR/DQ and HLA-A/B/DR and B/DR/DQ were essentially typical of a northern European population. HLA-A2, B44, DR4 and DQ2 were the highest frequency phenotypes and HLA-A2403, A34, A74, B42, B75, B2708, B48, B67 and B703 occurred once only. There were no examples of: A36, A43, A69, A80, B46, B54, B59, B73, B76, B77, B7801, B8101 or DR18 specificities. DR17, DQ2 and A1, B8, DR17 were the highest frequency two- and three-locus haplotypes identified. Diverse HLA-A, B, DR phenotypes were identified in 87.0% (1,564) of subjects. When HLA-DQ was also considered, different four locus phenotypes were identified in 89.1% (1,602) of subjects. This frequency information will be beneficial as a high-quality reference control for disease susceptibility studies and in calculating the chances of identifying a bone marrow donor in a patient’s extended family. This process was successful for the validation of our HLA-A and -B PCR-SSP typing procedure and the findings suggest an accurate level of specificity assignment of WBMDR panel donors who had previously been typed by serology alone.

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The outer layers of the cell envelope of a pseudomonad of marine origin were removed by washing the cells in 0.5 M NaCl followed by suspension in 0.5 M sucrose. The term mureinoplast has been suggested for the rod-shaped forms which resulted from this treatment. As previously established, these forms lacked the outer cell wall layers but still retained a rigid peptidoglycan structure. Mureinoplasts remained stable if suspended in a balanced salt solution containing 0.3 M NaCl, 0.05 M MgSO4, and 0.01 M KCI but, unlike whole cells, lost ultraviolet (UV)-absorbing material if suspended in 0.5 M NaCl or 0.05 M MgCl2. Sucrose added to the balanced salt solution also enhanced the loss of UV-absorbing material. Addition of lysozyme to suspensions of mureinoplasts in the balanced salt solution produced spherical forms which, by electron microscopy and the analysis of residual cell wall material, appeared to be true protoplasts. Only undamaged mureinoplasts, as judged by their capacity to fully retain a-aminoisobutyric acid, were capable of being converted to protoplasts. Protoplasts and undamaged mureinoplasts retained 100% transport capacity when compared to an equal number of whole cells. The Na+ requirement for transport of a-aminoisobutyric acid and the sparing action of Li+ on this Na+ requirement were the same for both protoplasts and whole cells. These observations indicate that, in this gram-negative bacterium, the cell wall does not participate in the transport process though it does stabilize the cytoplasmic membrane against changes in porosity produced by unbalanced salt solutions. The results also indicate that the requirements for Na+ for transport and for the retention of intracellular solutes are manifested at the level of the cytoplasmic membrane. 1014 on July 10, 2020 by guest http://jb.asm.org/ Downloaded from 1015