An HPLC procedure for monitoring penicillin G fermentations

Summary An HPLC procedure for the quantification of the precursor, intermediates, product, and degradation product of penicillin G fermentations is described. The method involves the use of an acetonitrile gradient and direct UV detection with a total run-time of 45 minutes including column regeneration. The technique can be exploited for on-line monitoring of penicillin G fermentations using defined or complex media.     

Species boundaries and global biogeography of the Alexandrium tamarense complex (Dinophyceae)1

Alexandrium catenella (Whedon et Kof.) Balech, A. tamarense (M. Lebour) Balech, and A. fundyense Balech comprise the A. tamarense complex, dinoflagellates responsible for paralytic shellfish poisoning worldwide. The relationships among these morphologically defined species are poorly understood, as are the reasons for increases in range and bloom occurrence observed over several decades. This study combines existing data with new ribosomal DNA sequences from strains originating from the six temperate continents to reconstruct the biogeography of the complex and explore the origins of new populations. The morphospecies are examined under the criteria of phylogenetic, biological, and morphological species concepts and do not to satisfy the requirements of any definition. It is recommended that use of the morphospecies appellations within this complex be discontinued as they imply erroneous relationships among morphological variants. Instead, five groups (probably cryptic species) are identified within the complex that are supported on the basis of large genetic distances, 100% bootstrap values, toxicity, and mating compatibility. Every isolate of three of the groups that has been tested is nontoxic, whereas every isolate of the remaining two groups is toxic. These phylogenetic groups were previously identified within the A. tamarense complex and given geographic designations that reflected the origins of known isolates. For at least two groups, the geographically based names are not indicative of the range occupied by members of each group. Therefore, we recommend a simple group‐numbering scheme for use until the taxonomy of this group is reevaluated and new species are proposed.     

Enzymic Interesterification of fats: Immobilization and Immunogold Localization of Lipase on Ion-Exchange Resins

A 1,3 specific lipase from Mucor miehei has been immobilized to two phenolformaldehyde resins with active tertiary amine groups and different porous structures (Duolite ES562 and ES568N). Duolite ES568N has a more uniform pore structure, allowing more rapid uptake of lipase. Immobilized lipase particles were treated by washing, dehydration with glycolmethacrylate and embedding in polymer. Following immunogold staining of thin sections, examined by electron or light microscopy showed that the location of the lipase was dependent on the pore structure of the support material and the immobilization time.     

The involvement of cAMP in lymphocyte capping

We have observed that agents that are known to elevate intracellular levels of cAMP such as N⁶,O²-dibutyryl adenosine 3′,5′-cyclic monophosphoric acid (dbcAMP) and theophylline cause a remarkable stimulatory effect on the lymphocyte receptor mobility phenomenon. Increased intracellular concentration of cAMP enhances not only antibody-induced but also Con A-induced lymphocyte capping events in T-lymphoma cells. In addition, we have noted that N²,O²-dibutyryl guanosine 3′,5′-cyclic monophosphoric acid (dbcGMP) does not stimulate but actually slightly inhibits the receptor movement. Furthermore, we have determined cAMP levels to increase greater than twofold during ligand-induced capping using a radioimmunoassay. Therefore, our data strongly suggest that cyclic adenylic monophosphoric acid (and not cGMP) is specifically involved in the redistribution of lymphocyte membrane proteins induced by both antibody and Con A.     

Fv-1 regulation of lymphoma development and of thymic ecotropic and xenotropic MuLV expression in mice of the AKR/J x RF/J cross.

The incidence of spontaneous thymic lymphoma has been studied in crosses between AKR/J and RF/J mice. AKR mice develop a high incidence of this disease. RF mice transmit a marked resistance to development of the disease to F1 hybrid mice of the AKR x RF cross. This resistance is associated with a reduction of endogenous ecotropic and xenotropic MuLV expression in the prelymphomatous thymus. The RF gene governing the coordinate suppression of these three phenotypes has been mapped to the Fv-1 locus. These results indicate that the particular Fv-1 allele of AKR mice provides a permissive genetic background for endogenous ecotropic and xenotropic MuLV expression and that these viral activities may be etiologically involved in the development of spontaneous thymic lymphoma in the mouse.     

HIV-1 gp120-mediated apoptosis of T cells is regulated by the membrane tyrosine phosphatase CD45

The molecular mechanism of the human immunodeficiency virus type 1 (HIV-1) gp120-induced apoptosis of bystander T cells is not well defined. Here, we demonstrate that CD45, a key component of the T cell receptor pathway, plays a crucial role in apoptosis induced by HIV-1 gp120. We observed that HIV-1 gp120-induced apoptosis was significantly reduced in a CD45-deficient cell line and that reconstitution of CD45 in these cells restored gp120-induced apoptosis. However, expression of a chimeric protein containing only the intracellular phosphatase domain was not able to restore the apoptotic function in the CD45-negative clone, indicating an important role for the extracellular domain of CD45 in this function. The role of CD45 in gp120-induced apoptosis was further confirmed in T cell lines and peripheral blood mononuclear cells using a selective CD45 inhibitor as well as CD45-specific small interfering RNA. We also observed that gp120 treatment induced CD45 association with the HIV coreceptor CXCR4. Further elucidation of downstream signaling events revealed that CD45 modulates HIV-1 gp120-induced apoptosis by regulating Fas ligand induction and activation of the phosphoinositide 3-kinase/Akt pathway. These results suggest a novel CD45-mediated mechanism for the HIV envelope-induced apoptosis of T cells.     

β2-Adrenergic receptor polymorphisms: pharmacogenetic response to bronchodilator among African American asthmatics

Beta2-adrenergic receptor (beta2AR) gene polymorphisms have been reported to be associated with various asthma-related traits in different racial/ethnic populations. However, it is unknown whether beta2AR genetic variants are associated with asthma in African Americans. In this study, we have examined whether there is association between beta2AR genetic variants and asthma in African Americans. We have recruited 264 African American asthmatic subjects and 176 matched healthy controls participating in the Study of African Americans, Asthma, Genes and Environments (SAGE). We genotyped seven known and recently identified beta2AR SNP variants, then tested genotype and haplotype association of asthma-related traits with the beta2AR SNPs in our African American cohort with adjustment of confounding effect due to admixture background and environmental risk factors. We found a significant association of the SNP -47 (Arg-19Cys) polymorphism with DeltaFEF(25-75), a measure of bronchodilator drug responsiveness, in African American asthmatics after correction for multiple testing (P = 0.001). We did not observe association of the SNP +46 (Arg16Gly) variant with asthma disease diagnosis and asthma-related phenotypes. In contrast to previous results between the Arg16Gly variant and traits related to bronchodilator responsiveness, our results indicate that the Arg-19Cys polymorphism in beta upstream peptide may play an important role in bronchodilator drug responsiveness in African American subjects. Our findings highlight the importance of investigating genetic risk factors for asthma in different populations.