A monomeric rat beta-galactoside-binding lectin previously purified from extracts of rat lung has been localized to erythrocytes, and the cDNA encoding it has been isolated from a rat reticulocyte cDNA library. The deduced amino acid sequence of the cDNA predicts a protein with a M(r) of 16,199, with no evidence of a signal peptide. The deduced sequence is identical to the sequences of seven proteolytic peptides derived from the purified lectin. Peptide analysis by mass spectrometry indicates that the N-terminal methionine is cleaved and that serine 2 is acetylated. The lectin shares all the strictly conserved amino acid residues of other members of the mammalian galectin family and is designated galectin-5 (GenBank accession number L36862). Galectin-5 is a weak agglutinin of rat erythrocytes, despite its monomeric structure. The gene encoding galectin-5 (LGALS5) has been mapped in mouse to chromosome 11, approximately 50 centimorgans from the centromere and 1.8 +/- 1.8 centimorgans from the polymorphic marker D11Mit34n, a region syntenic with human chromosome 17q11.

Spoligotyping and mycobacterial interspersed repetitive unit-variable-number tandem repeat analysis (MIRU-VNTR) were evaluated for the ability to differentiate 64 Mycobacterium tuberculosis isolates from 10 IS6110-defined clusters. MIRU-VNTR performed slightly better than spoligotyping in reducing the number of clustered isolates and the sizes of the clusters. All epidemiologically related isolates remained clustered by MIRU-VNTR but not by spoligotyping.

The malarial parasite dramatically alters its host cell by exporting and targeting proteins to specific locations within the erythrocyte. Little is known about the mechanisms by which the parasite is able to carry out this extraparasite transport. The fungal metabolite brefeldin A (BFA) has been used to study the secretory pathway in eukaryotes. BFA treatment of infected erythrocytes inhibits protein export and results in the accumulation of exported Plasmodium proteins into a compartment that is at the parasite periphery. Parasite proteins that are normally localized to the erythrocyte membrane, to nonmembrane bound inclusions in the erythrocyte cytoplasm, or to the parasitophorous vacuolar membrane accumulate in this BFA-induced compartment. A single BFA-induced compartment is detected per parasite and the various exported proteins colocalize to this compartment regardless of their final destinations. Parasite membrane proteins do not accumulate in this novel compartment, but accumulate in the endoplasmic reticulum (ER), suggesting that the parasite has two secretory pathways. This alternate secretory pathway is established immediately after merozoite invasion and at least some dense granule proteins also use the alternate pathway. The BFA-induced compartment exhibits properties that are similar to the ER, but it is clearly distinct from the ER. We propose to call this new organelle the secondary ER of apicomplexa. This ER-like organelle is an early, if not the first, step in the export of Plasmodium proteins into the host erythrocyte.