Specific 16S rDNA sequences associated with naphthalene degradation under sulfate-reducing conditions in harbor sediments.

Previous studies have demonstrated that naphthalene and other polycyclic aromatic hydrocarbons (PAHs) can be anaerobically oxidized with the reduction of sulfate in PAH-contaminated marine harbor sediments, including those in San Diego Bay. In order to learn more about the microorganisms that might be involved in anaerobic naphthalene degradation, the microorganisms associated with naphthalene degradation in San Diego Bay sediments were evaluated. A dilution-to-extinction enrichment culture strategy, designed to recover the most numerous culturable naphthalene-degrading sulfate reducers, resulted in the enrichment of microorganisms with 16S rDNA sequences in the d-Proteobacteria, which were closely related to a previously described pure culture of a naphthalene-degrading sulfate reducer, NaphS2, isolated from sediments in Germany. A more traditional enrichment culture approach, expected to enrich for the fastest-growing naphthalene-degrading sulfate reducers, yielded 16S rDNA sequences closely related to those found in the dilution-to-extinction enrichments and NaphS2. Analysis of 16S rDNA sequences in sediments from two sites in San Diego Bay that had been adapted for rapid naphthalene degradation by continual amendment with low levels of naphthalene suggested that the microbial community composition in the amended sediments differed from that present in the unamended sediments from the same sites. Most significantly, 6-8% of the sequences recovered from 100 clones of each of the naphthalene-amended sediments were closely related to the 16S rDNA sequences in the enrichment cultures as well as the sequence of the pure culture, NaphS2. No sequences in this NaphS2 phylotype were recovered from the sediments that were not continually exposed to naphthalene. A PCR primer, which was designed based on these phylotype sequences, was used to amplify additional 16S rDNA sequences belonging to the NaphS2 phylotype from PAH-degrading sediments from Island End River (Boston), MA, and Liepaja Harbor, Latvia. Closely related sequences were also recovered from highly contaminated sediment from Tampa Bay, FL. These results suggest that microorganisms closely related to NaphS2 might be involved in naphthalene degradation in harbor sediments. This finding contrasts with the frequent observation that the environmentally relevant microorganisms cannot be readily recovered in pure culture and suggests that further study of the physiology of NaphS2 may provide insights into factors controlling the rate and extent of naphthalene degradation in marine harbor sediments.

Selective reduction in CD2 expression on CD2bright/CD8+ lymphocytes from cynomolgus monkeys (Macaca fascicularis) in response to acute stress.

Numerous reports have demonstrated a link between stressful stimuli and immune suppression. However, the cellular mechanisms by which stress impairs immune function are largely unknown. We have examined the effects of an acute stressor on the T cell population, specifically, the number and phenotype of T cells in a nonhuman primate model. In nonstressed adult monkeys, we found differences in the level of expression of CD2 on T cells, revealing two distinct subsets of T cells, CD2dim and CD2bright cells, with CD2bright cells predominately coexpressing CD8. In response to acute stress, we observed a significant loss in the number and percent of CD2bright/CD8+ cells, with percent of CD2bright cells returning to pre-stress values within 24 h.

Characterization and comparison of the lytic function of NKR-P1+ and NKR-P1-rat natural killer cell clones established from NKR-P1bright/TCR alpha beta-cell lines.

From sorted rat NKR-P1bright/T cell receptor (TCR) alpha beta-cells, we established interleukin (IL)-2-dependent cell lines with the morphology, phenotype and function of natural killer (NK) cells. The cell lines NKbr11.3 and NKbr1.28 had large-granular-lymphocyte morphology, were capable of lysing NK-and lymphokine-activated-killer-susceptible target cells, and had the phenotype NKR-P1bright/CD3-/CD4-/CD5-/CD25-/gp42+/TCR alpha beta-. Both cell lines mediated reverse antibody-dependent cellular cytotoxicity via NKR-P1. NKR-P1-subpopulations, identical in all other aspects of phenotype, spontaneously developed in both cell lines. Cloning of NKbr11.3 and NKbr1.28 by limiting dilution resulted in two NKR-P1+ clones, 11.3(6B) and 1.28(3D), and three NKR-P1- clones, 11.3(8A), 11.3(10B), and 1.28(9F). The NKR-P1- clones were lytic and their target preference resembled that of the parental lines, except that C1498 and P815 appeared to be poor targets for 11.3(8A) and 11.3(10B). These cells represent the first reported rat IL-2-dependent NK cell lines and clones. They will be useful for the study of NK cell function as well as the function and expression of NKR-P1.

Bidimensional sorting in preschoolers with an instrumental learning task.

74 lower- and middle-class children aged 2 1/2, 3 1/2, and 4 1/2 years who were successful at unidimensional sorting of 2 objects by either color or form were given feedback for correct bidimensional sorting of 3 objects, 2 of which had been used in unidimensional testing. Four of the 10 2 1/2-year-olds and 58 of the 64 3 1/2- and 4 1/2-year-olds reached criterion on the bidimensional sorting task. Neither social class nor performance on a verbal comprehension test (the Peabody Picture Vocabulary Test) was significantly correlated with success on either unidimensional or bidimensional sorting, although social class and test scores were significantly correlated. The results indicate that Piagetian centration (i.e., the inability to transcend unidimensional attention) is a task- or situation-specific phenomenon, and biodimensional responding is the rule rather than the exception for 3 1/2- and 4 1/2-year-olds in an instrumental situation involving a limited number of stimuli.