Synthesis of L-2-oxothiazolidine-4-carboxylic acid

An improved synthesis of L-2- oxothiazolidine -4-carboxylic acid is described. The new procedure, which leads to excellent yields of product, does not require the use of phosgene. The new method is thus less hazardous than the original one, and is readily adaptable to the preparation of 35S-labeled product.     

Biogeographic comparisons of marine algal polyphenolics: evidence against a latitudinal trend

Summary Marine allelochemicals generally are present in greater quantity and diversity in tropical than in temperate regions. Marine algal polyphenolics have been reported as an apparent exception to this biogeographic trend, with literature values for phenolic concentrations significantly higher in temperate than in tropical brown algae. In contrast, our results, the first reported for Caribbean brown algae (orders Dictyotales and Fucales), show that many species have high phenolic levels. In addition, both our study and previous studies with north temperate and tropical species demonstrate that there is marked variation in algal phenolic levels within species from different locations. We conclude that high phenolic concentrations occur in species from both temperate and tropical regions, indicating that latitude alone is not a reasonable predictor of plant phenolic concentrations.     

The effect of neonatal rat graft-vs-host disease (GVHD) on Fc receptor lymphocytes.

The level of Fc receptor rosette-forming lymphocytes (Fc-RFL) was examined in spleen and lymph node cell suspension from neonatal DA and BN rats inoculated within 24 hr of birth with either allogeneic L (experimental) or syngeneic (control) lymphoid cells. In addition, these levels were compared to fetal and neonatal animals that received no injection. The indicator cells (EA) were sheep erythrocytes sensitized with one-half concentration of the highest dilution of rabbit anti-sheep erythrocyte IgG(A) which agglutinated an equal amount of 1% suspension of E. Care was taken to exclude scoring macrophages by injecting colloidal carbon at least 1 hr before killing the test animals. The spleen of 19-day DA fetal rats exhibited a level of 19.3% Fc-RFL, similar to that of animals having received adult syngeneic cells at birth (40.0%) by day 7. Thereafter the level of Fc-RFL did not vary appreciably between these two groups. However, as early as 2 days after inoculation there was a significantly greater number of Fc-RFL in the spleen of experimental DA neonates compared to controls. The lymph nodes of experimental animals did not exhibit a significantly greater number of Fc-RFL until day 6 with both tissue compartments peaking at day 10 and remaining significantly higher than controls until death. In neonatal BN animals significantly higher levels of Fc-RFL in experimental animals were not evident as early and peaked later (day 12) in both tissue compartments but again these differences remained until death. Cytotoxic alloantisera demonstrated that on days 6, 10, and 12 most, if not all, of the Fc-RFL were host in origion in both DA and BN GVHD, with a very significant host plasma cell response in such GVHD animals. One-micron tissue section revealed the presence of a great number of plasma cell especially prominent in the medulla of lymph nodes with the cortex of lymph nodes and white pulp of the spleen markedly depleted of lymphocytes indicative of cytotoxicity.     

Conformation-specific binding of alpha-synuclein to novel protein partners detected by phage display and NMR spectroscopy

Alpha-synuclein (AS) is an intrinsically unstructured protein in aqueous solution but is capable of forming beta-sheet-rich fibrils that accumulate as intracytoplasmic inclusions in Parkinson disease and certain other neurological disorders. However, AS binding to phospholipid membranes leads to a distinct change in protein conformation, stabilizing an extended amphipathic alpha-helical domain reminiscent of the exchangeable apolipoproteins. To better understand the significance of this conformational change, we devised a novel bacteriophage display screen to identify protein binding partners of helical AS and have identified 20 proteins with roles in diverse cellular processes related to membrane trafficking, ion channel modulation, redox metabolism, and gene regulation. To verify that the screen identifies proteins with specificity for helical AS, we further characterized one of these candidates, endosulfine alpha (ENSA), a small cAMP-regulated phosphoprotein implicated in the regulation of insulin secretion but also expressed abundantly in the brain. We used solution NMR to probe the interaction between ENSA and AS on the surface of SDS micelles. Chemical shift perturbation mapping experiments indicate that ENSA interacts specifically with residues in the N-terminal helical domain of AS in the presence of SDS but not in aqueous buffer lacking SDS. The ENSA-related protein ARPP-19 (cAMP-regulated phosphoprotein 19) also displays specific interactions with helical AS. These results confirm that the helical N terminus of AS can mediate specific interactions with other proteins and suggest that membrane binding may regulate the physiological activity of AS in vivo.     

1H, 13C, and 15N resonance assignment of the cAMP-regulated phosphoprotein endosulfine-alpha in free and micelle-bound states

¹³C, ¹⁵N, and ¹H chemical shift assignments are presented for the cAMP-regulated phosphoprotein endosulfine-alpha in its free and micelle-bound states. Secondary chemical shift analysis demonstrates formation of four helices in the micelle-bound state, which are not present in the absence of detergent.     

Tyrosine-Phosphorylated Caveolin-1 Blocks Bacterial Uptake by Inducing Vav2-RhoA-Mediated Cytoskeletal Rearrangements

Certain bacterial adhesins appear to promote a pathogen''s extracellular lifestyle rather than its entry into host cells. However, little is known about the stimuli elicited upon such pathogen host-cell interactions. Here, we report that type IV pili (Tfp)-producing Neisseria gonorrhoeae (P⁺GC) induces an immediate recruitment of caveolin-1 (Cav1) in the host cell, which subsequently prevents bacterial internalization by triggering cytoskeletal rearrangements via downstream phosphotyrosine signaling. A broad and unbiased analysis of potential interaction partners for tyrosine-phosphorylated Cav1 revealed a direct interaction with the Rho-family guanine nucleotide exchange factor Vav2. Both Vav2 and its substrate, the small GTPase RhoA, were found to play a direct role in the Cav1-mediated prevention of bacterial uptake. Our findings, which have been extended to enteropathogenic Escherichia coli, highlight how Tfp-producing bacteria avoid host cell uptake. Further, our data establish a mechanistic link between Cav1 phosphorylation and pathogen-induced cytoskeleton reorganization and advance our understanding of caveolin function.     

Use of the 16S-23S rDNA internal transcribed spacer of Roseovarius crassostreae for epizootiological studies of juvenile oyster disease (JOD)

Juvenile oyster disease (JOD) in Crassostrea virginica is caused by the marine bacterium Roseovarius crassostreae. Although the 16S rRNA genes of the bacterial isolates exhibit little variation, 2 genetic signatures (GSI and GSII) may be discerned by Ava I digestion of the 16S-23S internal transcribed spacer (ITS). In this study we analyzed isolates from JOD epizootics throughout the northeastern USA (including affected adults for the first time) to better understand how oyster populations encounter and become affected by the pathogen. Isolates from a given epizootic usually had the same ITS signature; however, the involvement of both genetic signatures was occasionally detected, even within the same oyster. Sequencing was used to localize the variable Ava I site to a 100 bp region of low sequence identity, and detection of additional base changes resulted in the identification of 11 distinct genotypes. One genotype was found only in Martha's Vineyard, Massachusetts, USA and persisted in JOD survivors. Two genotypes were associated with Maine epizootics, and both were believed to be unique to that region until 2004, when one was detected in Martha's Vineyard among oysters that had survived colonization by the local genotype. Apparent competition between those 2 genotypes was also detected among a population of juveniles. Five genotypes were found only in New York, and the other 3 were isolated from both New York and from around Cape Cod, Massachusetts. Relationships between the geographic occurrence and phylogenetic relatedness of genotypes were compared with regional current patterns to identify possible mechanisms controlling their distribution.