Hydrophobia, lectin binding, and molecular order in the stratum corneum of adult and neonatal rats and in human breast cells in culture.

A search for differences due to ANS staining (hydrophobia), Con A and PNA binding capacity, and birefringence was carried out on stratified epithelia of rat skin and human breast cells (HBC) in culture. Microfluorimetric measurements confirm that the ANS fluorescence of the stratum corneum from adults is higher than that of newborns. HBC exhibited an unexpected deep ANS-fluorescence. Differences in the binding capacity of the epithelial layers to Con A and PNA were detected with advancing age. Retardation measurements revealed that the form birefringence of the stratum corneum is higher in adult animals specially as revealed by the fact that its form birefringence curve branch from n = 1.414 to n = 1.479 is steeper, i.e. depict higher values. The strong birefringence of the cytoplasmic tonofilaments presented by cultured human breast cells was considered an unexpected finding and attributed to changes that the cells underwent following the in vitro conditions.     

Malaria Parasite-Infected Erythrocytes Secrete PfCK1, the Plasmodium Homologue of the Pleiotropic Protein Kinase Casein Kinase 1

Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite’s life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion.     

Copepods of the Juréia ecological reserve,state of São Paulo,Brazil. II. The genera Hesperocyclops,Muscocyclops, and Bryocyclops (Cyclopoida,Cyclopidae)

Cyclopid copepods collected mainly in aquatic microcosms and semiterrestrial habitats in the Juréia Ecological Reserve are studied. Hesperocyclops herbsti and Bryocyclops campaneri are described as new species and their taxonomical relationships discussed. Females of Muscocyclops operculatus (Chappuis) are redescribed and the males described for the first time. An emended diagnosis for Muscocyclops is proposed.     

Molecular analysis of yellow fever virus 17DD vaccine strain.

The Oswaldo Cruz Foundation produces most of the yellow fever (YF) vaccine prepared worldwide. As part of a broader approach to determine the genetic variability in YF 17D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purified directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF 17D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot hybridization of virion RNAs of purified 17DD with two other strains of YF 17D virus revealed only genome-sized molecules for all three viruses. These observations suggest that the vaccine phenotype is primarily associated with the accumulation of mutations.     

Resialylation of sialidase-treated sheep and human erythrocytes by Trypanosoma cruzi trans-sialidase: restoration of complement resistance of desialylated sheep erythrocytes.

Trypanosoma cruzi trans-sialidase (TS) is a recently described enzyme which transfers alpha(2-3)-linked sialic acid from host-derived sialylated glycoconjugates to parasite surface molecules [Schenkman et al. (1991) Cell, 65, 1117]. We report here on the ability of TS to transfer sialic acid from donor sialyl-alpha(2-3)lactose to sialidase-treated sheep and human erythrocytes. Up to approximately 50% resialylation of both desialylated red cells could be attained. Resialylation of desialylated sheep erythrocytes restores their resistance to lysis by human complement. This ascribes a possible biological role for T. cruzi TS and demonstrates directly that sialic acid is solely responsible for preventing alternative pathway activation of human complement by sheep erythrocytes.     

Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis.

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.