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Biomedical subjects

T Shiroishi

Publications and source records attributed to T Shiroishi.

101 records · Page 6Linked to original sources

Further evidence for the parasitic origin of the surface coat on Malaria merozoites.

It has been observed that a surface coat, 20 nm in thickness, extends from the plasma membrane of extracellular merozoites and that this coat contains strain-specific antigens. In the present study we determined the possible effect of protein in the culture medium on this structure. The surface coat on merozoites in culture medium devoid of protein was indistinguishable by transmission electron microscopy from the coat in a protein-containing medium. This supports the hypothesis that the surface coat originates from the parasite rather than from adsorbed serum protein.

Animals↗

Invasion of erythrocytes by malaria merozoites.

An electro-optical system was developed to record microscope images with high resolution at low light intensities. The system was used to study the invasion of erythrocytes by malaria merozoites. Invasion consists of attachment of the anterior end of the parasite to the erythrocyte, deformation of the erythrocyte, and the entry of the parasite by erythrocyte membrane invagination.

Animals↗

Influence of erythrocyte membrane components on malaria merozoite invasion.

Chymotrypsin- and Pronase-treated human erythrocytes were refractory to invasion by P. knowlesi merozoites; invasion was not inhibited by trypsin or neurammidase treatment. These data implicate a surface protein other than sialoglycoprotein as the receptor site for merozoites. Invasion of rhesus erythrocytes was unaffected by pretreatment with these enzymes. Differences in membrane structure of erythrocytes from various species may explain the absence of an enzyme effect on rhesus erythrocytes.

Animals↗

Molecular cloning of rat and mouse membrane cofactor protein (MCP, CD46): preferential expression in testis and close linkage between the mouse Mcp and Cr2 genes on distal chromosome 1.

Human membrane cofactor protein (MCP, CD46) is widely distributed and is one of the plasma membrane complement inhibitors. We isolated cDNA clones encoding genetic homologues of human MCP from a rat testis cDNA library. Northern blot analysis indicated that rat MCP is preferentially expressed in testis, similar to what is found with guinea pig MCP. We identified several different cDNAs, which were presumably generated by alternative splicing from a single-copy gene. The most prevalent isoform corresponded to the Ser/Thr/Pro-rich C type of human MCP. Mouse MCP cDNA was cloned by polymerase chain reaction based on the nucleotide sequence of rat MCP. The deduced amino acid sequence showed 77.8% identity to rat MCP. Mouse MCP was also preferentially expressed in testis. Unique expression in testis in rat and mouse as well as guinea pig suggests that MCPs in these species not only act as complement regulatory proteins but may also have more specialized functions in fertilization or reproduction. Genetic mapping by linkage analysis indicated that the mouse Mcp gene is located on distal chromosome 1, closely linked to the complement receptor 2 (Cr2) gene.

Amino Acid Sequence↗