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Biomedical subjects

B Dixon

Publications and source records attributed to B Dixon.

204 records · Page 12Linked to original sources
PubMedDate not supplied

Fish major histocompatibility complex genes: an expansion.

The advent of polymerase chain reaction technology has provoked a large amount of progress in the field of fish major histocompatibility complex (MHC) research. Many new teleost sequences have been reported in the last four years, including representatives of all classes of MHC genes. While the intron-exon structure of teleost MHC genes is now becoming clear, the organisation of the genes within the teleost MHC is still unclear. The sequences reported to date have been used for phylogenetic analysis and, due to their evolutionary position, are discussed in relation to hypotheses regarding the origin of the MHC. Teleost MHC gene sequences are also examined to see if conserved features of the both the nucleotide and amino acid sequences of higher vertebrate MHC genes are present. Differences in these features will reflect functional differences between teleost and mammalian MHC genes and may also have evolutionary implications.

Amino Acid Sequence↗
PubMedDate not supplied

The relationship between major histocompatibility receptors and innate immunity in teleost fish.

Studies of the innate immune system have recently shown that, in addition to its role in producing the primary response that slows down pathogens, it may also play an important role in initiating and directing the type of response that the adaptive immune system makes. These discoveries have shown a complex web of control containing new roles for the innate immune system in organizing responses of T-cell to antigens being presented by major histocompatibility receptors, as well as new roles for those receptors in innate immune responses. Both of these activities are managed through feedback networks involving elements of both the innate and adaptive immune system. This paper will discuss these newly discovered interactions and how they are influencing current theories regarding the initiation of adaptive immune responses. In particular, it will highlight the recent progress that is being made towards understanding these relationships in the immune systems of teleost fish.

Adaptation, Physiological↗
PubMedDate not supplied

Expression of MhcCyca class I and class II molecules in the early life history of the common carp (Cyprinus carpio L.)

In this study transcription of class I alpha chain (Cyca-UA), beta2-microglobulin (Cyca-B2m) and class II alpha (Cyca-DXA) and beta (Cyca-DAB) during the early stages of embryo development was investigated by semiquantitative PCR. No transcripts of the genes under investigation were detected in the unfertilized egg. The expression of the genes encoding for the class II molecules revealed to be synchronized starting at day 1, unlike those for the class I molecules. Transcription of Cyca-B2m was first detected at day 7, whereas Cyca-UA was already present on day 1. This discrepancy would suggest absence of class I molecules during early development. The transcription of the Mhc genes in lymphoid organs was well established on day 21, with the exception of the spleen. In later stages of ontogeny cell surface expression of class I molecules was studied using polyclonal antibodies to Cyca-UA and Cyca-B2m in conjunction with detection of surface Ig. In week 3-10 Cyca-B2m was found on a higher percentage of cells from pronephros, spleen and thymus compared to Cyca-UA, suggesting the use of an alternative class I alpha chain. In the thymus, unlike the other organs, this difference remained present in the adult stage. The most likely candidates are alpha chains encoded by non-classical class I genes.

Animals↗