Isolation and characterization of the rat proenkephalin gene

The rat proenkephalin gene has been isolated by molecular cloning and characterized by DNA-sequence analysis. The gene exhibits a structural organization similar to that of the human gene. The nucleotide sequence encoding the biologically active opioid peptides which are generated from the proenkephalin precursor as well as the 3' untranslated region of the mRNA are found on a large exon at the 3' end of the gene (Exon III). The nucleotide sequence encoding the N terminus of the mature protein and its signal peptide are located on Exon II while Exon I encodes the 5' untranslated region of the mRNA. The nucleotide sequence of these exons and their flanking regions has been determined and compared to the human proenkephalin gene. Analysis of the nucleotide sequence homology between the human and rat proenkephalin gene reveals the presence of highly conserved regions within both the coding and noncoding portions of the genes. Enkephalin-coding sequences as well as 5' flanking sequences appear to be the most highly conserved. The importance and possible function of these sequences are discussed.     

Abnormal PfEMP1/knob display on Plasmodium falciparum-infected erythrocytes containing hemoglobin variants: fresh insights into malaria pathogenesis and protection

Hemoglobin (Hb) variants are associated with reduced risk of life-threatening Plasmodium falciparum malaria syndromes, including cerebral malaria and severe malarial anemia. Despite decades of research, the mechanisms by which common Hb variants - sickle HbS, HbC, α-thalassemia, fetal HbF - protect African children against severe and fatal malaria have not been fully elucidated. In vitro experimental and epidemiological data have long suggested that Hb variants do not confer malaria protection by restricting the growth of parasites in red blood cells (RBCs). Recently, four Hb variants were found to impair cytoadherence, the binding of P. falciparum-infected RBCs (PfRBCs) to microvascular endothelial cells (MVECs), a centrally important event in both parasite survival and malaria pathogenesis in humans. Impaired cytoadherence is associated with abnormal display of P. falciparum erythrocyte membrane protein 1 (PfEMP1), the parasite's major cytoadherence ligand and virulence factor, on the surface of host RBCs. We propose a model in which Hb variants allow parasites to display relatively low levels of PfEMP1, sufficient for sequestering PfRBCs in microvessels and avoiding their clearance from the bloodstream by the spleen. By preventing the display of high levels of PfEMP1, Hb variants may weaken the binding of PfRBCs to MVECs, compromising their ability to activate endothelium and initiate the downstream microvascular events that drive the pathogenesis of malaria.     

AMPA receptor-dependent clustering of synaptic NMDA receptors is mediated by Stargazin and NR2A/B in spinal neurons and hippocampal interneurons

Under standard conditions, cultured ventral spinal neurons cluster AMPA- but not NMDA-type glutamate receptors at excitatory synapses on their dendritic shafts in spite of abundant expression of the ubiquitous NMDA receptor subunit NR1. We demonstrate here that the NMDA receptor subunits NR2A and NR2B are not routinely expressed in cultured spinal neurons and that transfection with NR2A or NR2B reconstitutes the synaptic targeting of NMDA receptors and confers on exogenous application of the immediate early gene product Narp the ability to cluster both AMPA and NMDA receptors. The use of dominant-negative mutants of GluR2 further showed that the synaptic targeting of NMDA receptors is dependent on the presence of synaptic AMPA receptors and that synaptic AMPA and NMDA receptors are linked by Stargazin and a MAGUK protein. This system of AMPA receptor-dependent synaptic NMDA receptor localization was preserved in hippocampal interneurons but reversed in hippocampal pyramidal neurons.     

Systematics,morphology and biological control

Accurate systematics is the foundation on which all meaningful research in biology is based. The importance of sound systematics to practical biological control is illustrated by results from several projects on biological control of coccid pests. Correct identification of the pest species or their natural enemies, and recognition of cryptic species or infraspecific entities, have been of utmost importance to the success of many projects. Accurate morphology is the basis of reliable systematics. Unfortunately, basic morphology of the parasitic Hymenoptera is still imperfectly understood and that which is known often is inadequately used. The scanning electron microscope is a valuable tool for comparative morphological research that will go far toward solving these problems. The taxonomic validity of morphological characters, and the extent of intraspecific variation, should be determined by a detailed biometrical study of large series of cultured specimens whenever possible. This approach is illustrated with results obtained in our recent revision of the species ofAphytis, important parasites of diaspine scale insects. Comparative morphology of developmental stages of parasitic Hymenoptera is recognized as an important approach to the study of cryptic species needing much more emphasis.     

Endothelial cells are central orchestrators of cytokine amplification during influenza virus infection

Cytokine storm during viral infection is a prospective predictor of morbidity and mortality, yet the cellular sources remain undefined. Here, using genetic and chemical tools to probe functions of the S1P(1) receptor, we elucidate cellular and signaling mechanisms that are important in initiating cytokine storm. Whereas S1P(1) receptor is expressed on endothelial cells and lymphocytes within lung tissue, S1P(1) agonism suppresses cytokines and innate immune cell recruitment in wild-type and lymphocyte-deficient mice, identifying endothelial cells as central regulators of cytokine storm. Furthermore, our data reveal immune cell infiltration and cytokine production as distinct events that are both orchestrated by endothelial cells. Moreover, we demonstrate that suppression of early innate immune responses through S1P(1) signaling results in reduced mortality during infection with a human pathogenic strain of influenza virus. Modulation of endothelium with a specific agonist suggests that diseases in which amplification of cytokine storm is a significant pathological component could be chemically tractable.     

The effect of follicular fluid hormones on oocyte recovery after ovarian stimulation: FSH level predicts oocyte recovery

Background  

Ovarian stimulation for assisted reproductive technology (ART) overcomes the physiologic process to develop a single dominant follicle. However, following stimulation, egg recovery rates are not 100%. The objective of this study is to determine if the follicular fluid hormonal environment is associated with oocyte recovery.     

Identification of a protein encoded by the trans activator gene tatIII of human T-cell lymphotropic retrovirus type III.

The human T-cell lymphotropic virus type III (HTLV-III/LAV) is a retrovirus associated with acquired immune deficiency syndrome. The region on the viral genome that is necessary for trans-activation of the HTLV-III/LAV long terminal repeat called tatIII has previously been determined to lie between nucleotides 5365 and 5607. Here we report that a bacterial fusion protein containing amino acid sequences specified by the first coding exon of the tatIII gene is recognized by some patient antisera. We also demonstrate that lymphoid and epithelial cells that express the trans activator function express a 14-kilodalton (kDa) protein recognized by a patient antiserum that reacts with the bacterial tatIII fusion protein. Cells transiently transfected with a deletion mutant of the trans activator protein produce a 12-kDa protein rather than the 14-kDa protein. These observations indicate that the tatIII region contains a functional gene and is capable of expressing a protein that migrates with an apparent molecular size of 14 kDa in some lymphoid and epithelial cells transfected with plasmids containing the tatIII region. We propose that the product of the trans activator gene be designated p14tat-III.     

Targeted disruption of the mouse Asna1 gene results in embryonic lethality

The bacterial ArsA ATPase is the catalytic component of an oxyanion pump that is responsible for resistance to arsenicals and antimonials. Homologues of the bacterial ArsA ATPase are widespread in nature. We had earlier identified the mouse homologue (Asna1) that exhibits 27% identity to the bacterial ArsA ATPase. To identify the physiological role of the protein, heterozygous Asna1 knockout mice (Asna1+/-) were generated by homologous recombination. The Asna1+/- mice displayed similar phenotype as the wild-type mice. However, early embryonic lethality was observed in homozygous Asna1 knockout embryos, between E3.5 (E=embryonic day) and E8.5 stage. These findings indicate that Asna1 plays a crucial role during early embryonic development.