Unmasking of the fast sodium channel in less than 4 day old embryonic chicken heart by inhibitors of sodium inactivation]

Embryonic Chick hearts aged less than 4 days are not always sensitive to tetrodotoxin, an inhibitor of fast sodium channel. It is shown that in the most frequent cases, in which tetrodotoxin sensitivity is apparently absent, this sensitivity can be demonstrated after previous treatment by veratridine or by toxin II of androctonus australis Hector Scorpion venom. It is concluded that the fast tetrodotoxin-sensitive sodium channel is regularly present in the heart of Chick embryos aged 2 and 3 days, but most often in a permanently inactivated state.     

Is the process of localized lysosomal exocytosis responsible for the cytolytic action of killer T-lymphocytes?]

In this paper, we formulate the hypothesis that in the process of target cell lysis a lysosomal enzyme regurgitation, performed by killer cells at the level of the target effector junction, accounts for the target lesion which precedes the lysis (lethal hit). This process of exocytosis, similar to the one described previously in polymorphonuclear neutrophils is supported by cytological studies performed directly on identified killers isolated by micromanipulation. Light and electron microscopy observations confirm a previous report which describes the effector cells rich in lysosomal bodies. In addition, when a killer cell is associated with a target cell to form a conjugate, lysosomes are concentrated near the cell junction and, after incubation at 37 degrees C, acid phosphatases may be detected at the junction. Lysosomal enzyme exocytosis explains why target lysis needs an effector target binding to occur and also the other conditions required for any exocytosis process such as Ca++ in the medium, integrity of the microtubular apparatus, a low level of cyclic AMP and energy dependancy.     

Genome sequence and comparative analysis of the model rodent malaria parasite Plasmodium yoelii yoelii

Species of malaria parasite that infect rodents have long been used as models for malaria disease research. Here we report the whole-genome shotgun sequence of one species, Plasmodium yoelii yoelii, and comparative studies with the genome of the human malaria parasite Plasmodium falciparum clone 3D7. A synteny map of 2,212 P. y. yoelii contiguous DNA sequences (contigs) aligned to 14 P. falciparum chromosomes reveals marked conservation of gene synteny within the body of each chromosome. Of about 5,300 P. falciparum genes, more than 3,300 P. y. yoelii orthologues of predominantly metabolic function were identified. Over 800 copies of a variant antigen gene located in subtelomeric regions were found. This is the first genome sequence of a model eukaryotic parasite, and it provides insight into the use of such systems in the modelling of Plasmodium biology and disease.