Dietary fish oils modify adipocyte structure and function.

Dietary fish oils, enriched with omega-3 fatty acids (e.g., MaxEPA fish oil), inhibit lipogenesis and have a marked hypotriglyceridemic effect in man and experimental animals. Dietary omega-3 fatty acids also reduce adipose tissue trophic growth in rats. To understand the metabolic basis for this, we measured the effect of fish oil feeding upon rat plasma triglyceride concentration, fat pad mass, fat cell size, fat cell lipolysis, as well as lipoprotein binding to adipocyte plasma membranes. In adolescent (250 g) male Wistar rats fed 20% (w/w) fish oil supplemented diets for 3 weeks, plasma triglyceride levels and epididymal and perirenal fat pad mass were significantly (P less than 0.005) reduced compared to pair-fed controls given 20% lard diets. These differences in fat pad mass between the diets were greater than differences in whole animal mass or in the mass of livers, testes, kidneys, spleens, or hearts. Isoproterenol-stimulated lipolysis was significantly (P less than 0.005) higher in fish oil fed rats than in pair-fed controls. In young (100 g) rats plasma triglyceride levels were 10 times lower in the fish oil fed group after 5 weeks as compared to the lard-fed controls. This was accompanied by a reduction in epididymal and perirenal fat pad mass as well as a 2-3-fold decrease in adipocyte volumes; there was no significant difference between the two groups in fat cell number in each region. Plasma membranes of epididymal adipocytes from fish oil fed rats bound significantly (P less than 0.001) less HDL1 than the lard-fed rats, possibly as a result of a reduction in fat cell size and/or alteration of plasma membrane structure. Thus in both young and old rats, the reduction in plasma triglyceride concentration in conjunction with increased hormone-stimulated lipolysis may explain in part the selective reduction in adipose tissue trophic growth accompanying fish oil consumption.     

Molecular analysis of overlapping chromosomal deletions in patients with Langer-Giedion syndrome.

We have obtained lymphoblastoid cell lines from three patients with Langer-Giedion syndrome who have overlapping deletions in 8q24.1. To isolate the deletion chromosomes from their normal homologs, patient cell lines were fused with hamster cells and hybrid cells were selected for retention of human chromosome 8. These hybrid cell lines were screened for the presence of chromosome 8 by fluorescence in situ hybridization and by Southern blot hybridization. We have hybridized 31 recombinant DNA clones derived from the 8q22-qter region to Southern blots of the hybrid cell lines; 8 were found to lie within the deletion of at least one patient. One clone identified sequences that were missing from one copy of chromosome 8 in all three patients. These clones help to further define the deletions in these patients and will serve as starting points for detailed characterization of the region.     

Effects of increasing salinity on a cyanobacteria bloom in the Potomac River estuary

From June through August, 1985, a bloom of the cyanobacteriumMicrocyslis aeruginosa was observed in the upper Potomac Riverreaching densities of 193 x 10⁶ cells 1^–1 and 83% of totalcells in the surface mixed layer. However, in regions typifiedby salinities of 1–2 p.p.t. immediately down-river, thealga disappeared from the phytoplankton assemblage, never contributing>17% of total phytoplankton numbers. In an attempt to determinethe effect of increasing salinity on limiting horizontal distributionsof cyanobacteria blooms in the Potomac River estuary, threelaboratory experiments were conducted. Bloom samples collectedfrom the river were exposed to daily salinity increases of 1–2p.p.t. through the addition of NaCl or a complement of fullsea salts. Relative to samples receiving no salt supplement,densities of Microcyslis spp. declined in salinity-stressedsamples. However, total cyanobacteria remained constant or increaseddue to rapid growth of Aphanizomenon. The addition of a mixtureof full sea salts favored aggregation of cyanobacteria, yieldingan average of 132 cells colony^–1; 36 cells colony^–1were observed in populations maintained in river water and NaCl-supplementedsamples. Chlorophyll concentrations declined slightly relativeto assemblages receiving no salt additions while carbon fixationwas reduced in salinity-stressed assemblages. These resultssuggest that salinities from 0.5 to 7 p.p.t., typical of theoligohaline region of the Potomac River, could limit the distributionof Microcystis-dominated blooms down-estuary. In addition, increasingsalinities should result in the aggregation of photosyntheticallyinhibited cells and, through prolonged exposure to increasingosmotic stress, produce large, rapidly sinking detrital particlessupporting microbial decomposition in oligohaline and mesohalineregions of the lower Potomac River estuary, perhaps perpetuatinghigh microbial oxygen demand and anoxia in this portion of theriver/estuary.     

Investigation of trophic ecology in Newfoundland cold-water deep-sea corals using lipid class and fatty acid analyses

Coral Reefs - The trophic behavior of some deep-sea Newfoundland cold-water corals was explored using fatty acid (FA) and lipid profiles. No significant effect of geographic location and/or depth...     

ATP-competitive inhibitors of the mitotic kinesin KSP that function via an allosteric mechanism

The mitotic kinesin KSP (kinesin spindle protein, or Eg5) has an essential role in centrosome separation and formation of the bipolar mitotic spindle. Its exclusive involvement in the mitotic spindle of proliferating cells presents an opportunity for developing new anticancer agents with reduced side effects relative to antimitotics that target tubulin. Ispinesib is an allosteric small-molecule KSP inhibitor in phase 2 clinical trials. Mutations that attenuate ispinesib binding to KSP have been identified, which highlights the need for inhibitors that target different binding sites. We describe a new class of selective KSP inhibitors that are active against ispinesib-resistant forms of KSP. These ATP-competitive KSP inhibitors do not bind in the nucleotide binding pocket. Cumulative data from generation of resistant cells, site-directed mutagenesis and photo-affinity labeling suggest that they compete with ATP binding via a novel allosteric mechanism.     

Cytogeographic Distribution and Genome Size Variation in Prairie Cordgrass (Spartina pectinata Bosc ex Link)

Prairie cordgrass plants (Spartina pectinata Bosc ex Link) were examined from 61 locations representing the geographic distribution of prairie cordgrass in the U.S. Using flow cytometry, the genome size of 183 individual plants of prairie cordgrass was determined, and the chromosome counts were obtained. Three distinct ploidy levels were observed: tetraploid ( $ \overline x = {1}.{56} {\text{pg}},{2}n = {4} \times = {4}0 $ ), hexaploid ( $ \overline x { = 2}.{33} {\text{pg}},{2}n = {6} \times = {6}0 $ ), and octoploid ( $ \overline {\text{x}} { = 3}.0{6} {\text{pg}},{2}n = {8} \times { = 8}0 $ ). In the sampled areas, the tetraploid populations extended from the East North Central to the New England regions of the U.S., while the octoploid cytotypes were mostly distributed in the West North Central regions. Populations of the tetraploids and octoploids were found in close proximity in the West North Central (Iowa and Kansas) and the West South Central (Oklahoma) regions. The hexaploid cytotype was found in one mixed population (4x?+?6x) occurring in Illinois. No statistically significant intraploidy genome size variation was found in the tetraploid populations, while significant intraploidy genome size variation was found in the octoploid populations. This study precisely defined the geographic distribution of cytotypes in prairie cordgrass throughout the different regions of the U.S. These results provide critical genome size and ploidy distribution information needed to design efficient breeding schemes for high yielding cultivars of prairie cordgrass with local adaption.     

Learning to smell the roses: experience-dependent neural plasticity in human piriform and orbitofrontal cortices

It is widely presumed that odor quality is a direct outcome of odorant structure, but human studies indicate that molecular knowledge of an odorant is not always sufficient to predict odor quality. Indeed, the same olfactory input may generate different odor percepts depending on prior learning and experience. Combining functional magnetic resonance imaging with an olfactory paradigm of perceptual learning, we examined how sensory experience modifies odor perception and odor quality coding in the human brain. Prolonged exposure to a target odorant enhanced perceptual differentiation for odorants related in odor quality or functional group, an effect that was paralleled by learning-induced response increases in piriform cortex and orbitofrontal cortex (OFC). Critically, the magnitude of OFC activation predicted subsequent improvement in behavioral differentiation. Our findings suggest that neural representations of odor quality can be rapidly updated through mere perceptual experience, a mechanism that may underlie the development of odor perception.