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The synthesis and structures of (R)-tuberculostearic acid from commercially available (S)-citronellol and differentially acylated glycerol incorporating R)-tuberculostearic acid from R-benzyl glycidol are described. It is found that the natural phosphatidylinositol mannoside (PIM) and R)-tuberculostearic acid have modulated the release of the pro-inflammatory cytokine, interleukin-12 (IL-12), in a dendritic cell assay.

Mental images constructed after visual examination of a spatial configuration or after processing a verbal description of that configuration have been shown to share similar properties, in particular the capacity to preserve metric information contained in the configuration represented. In the present study, we investigated the properties of mental images constructed under learning conditions resulting from the combination of a visual or a verbal mode of acquisition and a survey or route perspective. Participants memorized a virtual environment (a garden containing six objects) under one of four learning conditions: (a) viewing a map of the garden (visual--survey); (b) viewing a video presentation of a journey along the path around the garden (visual--route); (c) listening to a verbal description of the map of the garden (verbal-survey); and (d) listening to a verbal description of the journey around the garden (verbal--route). The participants were then invited to compare the distances separating objects in the garden mentally. Experiment 1, where the pairs of distances to be compared had a common starting point, revealed that the frequency of correct responses was higher, and response times were shorter when participants had learned about the environment visually rather than by a verbal description. The conditions involving a survey perspective resulted in a higher frequency of correct responses and shorter response times than those involving a route perspective. Lastly, a symbolic distance effect was obtained in the first three conditions, in that the greater the difference between the two distances being compared, the higher the frequency of correct responses, and the shorter the response times. Experiment 2, where the pairs of distances had different starting points, replicated these results, although longer response times revealed that the comparison process was more costly. Taken together, these findings support the view that mental spatial representations derived from different sources and adopting different perspectives contain genuine metric properties, except when the verbal modality and the route perspective are combined during learning.

When grown in the absence of a source of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops, within 24 h, a differentiated cell type called a heterocyst that is specifically involved in the fixation of [N.sub.2]. Cell division is required for heterocyst development, suggesting that the cell cycle could control this developmental process. In this study, we investigated several key events of the cell cycle, such as cell growth, DNA synthesis, and cell division, and explored their relationships to heterocyst development. The results of analyses by flow cytometry indicated that the DNA content increased as the cell size expanded during cell growth. The DNA content of heterocysts corresponded to the subpopulation of vegetative cells that had a big cell size, presumably those at the late stages of cell growth. Consistent with these results, most proheterocysts exhibited two nucleoids, which were resolved into a single nucleoid in most mature heterocysts. The ring structure of FtsZ, a protein required for the initiation of bacterial cell division, was present predominantly in big cells and rarely in small cells. When cell division was inhibited and consequently cells became elongated, little change in DNA content was found by measurement using flow cytometry, suggesting that inhibition of cell division may block further synthesis of DNA. The overexpression of minC, which encodes an inhibitor of FtsZ polymerization, led to the inhibition of cell division, but cells expanded in spherical form to become giant cells; structures with several cells attached together in the form of a cloverleaf could be seen frequently. These results may indicate that the relative amounts of FtsZ and MinC affect not only cell division but also the placement of the cell division planes and the cell morphology. MinC overexpression blocked heterocyst differentiation, consistent with the requirement of cell division in the control of heterocyst development.

A large amount of research has been devoted to the cognitive processes elicited by the description of spatial environments or configurations of objects, attesting to the cognitive value of the [...], The dual-task paradigm was used to determine whether the spatial, visual and verbal components of working memory are engaged in the processing of spatial descriptions. Participants listened to route or survey descriptions of urban-like spatial environments and then drew corresponding maps. The position of each new landmark was described either in terms of the direction to move toward this landmark (route descriptions) or its relative location with regard to the previously mentioned landmark (survey descriptions). Route and survey descriptions resulted in similar recall performance in the absence of an interfering task and landmarks were consistently less well recalled than their associated moves/locations. The pattern of interference resulting from the secondary tasks indicated that the processing of landmarks called upon both the visual and spatial components of working memory in the route perspective, whereas the processing of moves/locations essentially relied on the spatial component in both the route and the survey perspectives. The verbal component of working memory was only involved in the processing of landmarks in the survey perspective. The results suggest that distinct cognitive processes support memory for route and survey descriptions, and that distinct working memory resources support the processing of landmarks and landmark positions.

The behaviour of Aeromonas hydrophila in nutrient-poor filter-sterilized seawater was investigated at 23 and 5 [degrees]C with respect to its growth phase. At both temperatures, the culturable A. hydrophila population declined below the detection level (0*1 c.f.u, [ml.sup.-1]) after 3-5 weeks, depending on the initial physiological state of the cells. During the first week, starved A. hydrophila cells appeared more resistant to the seawater stress at 5 [degrees]C than cells initially in the exponential growth phase. This difference was not observed at 23 [degrees]C, where de novo protein synthesis seemed to be required for long-term adaptation of cells from the exponential growth phase. Over the duration of the experiments, intact and total cell concentrations were not significantly affected, indicating that bacteria had entered a so-called viable but nonculturable state (VBNC). However, the incubated bacteria rapidly became heterogeneous with respect to their nucleic acid content, and their cell size decreased faster at 23 than at 5 [degrees]C. Resuscitation of VBNC cells was attempted by a temperature shift from 5 to 23 [degrees]C without exogenous nutrient addition. Comparison of the growth rates of the stressed population and of the untreated bacteria growing in the same autoclaved initial cell suspension showed significantly faster growth for the stressed cells, suggesting that in addition to growth of the few culturable stressed cells, a proportion of injured cells became culturable.

Researchers describe a system that can distinguish viable bacterial cells from damaged bacterial cells by using permeant and impermeant fluorescent probes. A full or partial quenching of the permeant probe by the impermeant probe will occur if the cell is damaged and no quenching will occur if it is intact and viable.

Data on the presence of iron and chlorophyll-alpha are provided for the Antarctic water tongue and coastal zone of the Antarctic Ocean. Both regions were found to be iron-rich, but the low level of chlorophyll-alpha suggests either heavy copepod grazing pressure and/or an inadequate light-mixing regime; offshore waters, however, supported greater phytoplankton growth due to an improved light-mixing regime.