Repertoire Of Variants Research Articles

The role of monoclonal antibody technology in immunoparasitology

Research on the immunology of parasit ic infections has three outstanding characteristics: complexity, because successful parasi t ism involves the interweaving of in t r ica te mechanisms of host and pa ras i t e ; fascinatzon in view of the many insights into fundamental immunological, genetic and biochemical processes which study of this topic involves; and zmportance since parasit ic infections constitute an enormous (although largely unappreciated) burden of disease on mankind, not to mention domestic and other animals, with social and economic consequences which it would be difficult to exaggerate. Although parasit ic infections are at t ract ing increasing at tention from immunologists it must be confessed that knowledge is patchy and often inadequate as a basis for the development of vaccines and tests needed for disease control. For example, antigenic variation is considered to be one important way by which parasites may evade the host's immune response. Such variation is well-recognized in the surface coat protein of the t rypanosomes which in Africa cause sleeping sickness in man and chronic disease in cattle. Knowledge of the size of the variant repertoire, of structural differences associated with variation, of the circumstances under which variation is induced and of the underlying genetic mechanisms is now rapidly emerging, a ided recently by the use of monoclonal antibodies ~. Antigenic variation has also been demonstrated in one variety of malar ia parasite, Plasmodium knowlesi, which infects monkeys. Red cells containing the schizonts of this parasite carry a series of different antigens recognizable by differential agglutinabil i ty 2, However, these potentially important antigens have not yet been characterized, nor is it agreed whether comparable variation exists in malarial parasites which infect man. There are a number of reasons for the present unsatisfactory state of knowledge. Immunologists only recently have established a general framework for the understanding of the immune response, including control and effector mechanisms. Prior to that it was

Song repertoires and territory defence in the great tit

BIRD song is generally considered to have one or both of two main functions : attracting a mate and proclaiming a territory. The great tit (Parus major) is a typical songbird in that song is primarily a male vocalisation and it is produced before and during the breeding season (that is, from January to May in southern England). We have shown that great tit song plays a part in territory maintenance by experiments in which we ‘occupied’ territories with loudspeakers after removing resident pairs1,2. New pairs seeking an empty space in which to settle moved into control areas more rapidly than into song-occupied territories. We report here on three experiments designed to study the effect of a varied song repertoire in territory maintenance. Each male great tit, in common with many other songbird species, has a repertoire of song variants some of which are usually shared between birds in a locality. In the great tit, repertoire size commonly varies between two and eight song types. In some species, for example the canary, elaborate repertoires seem to be favoured by sexual selection3,4, but we have found no evidence for this in the great tit (Table 1), in which pairing takes place before the spring peak of song. We therefore tested the possibility that repertoires enhance the effectiveness of song as a territorial display.