The effects of silicone fluid additives and silicone elastomer matrices on barnacle adhesion strength

Barnacle adhesion strength was used to screen seventy-seven polydimethylsiloxane elastomeric coatings for fouling-release properties. The test coatings were designed to investigate the effect on barnacle adhesion strength of silicone fluid additive type, additive location, additive molecular weight, additive loading level, mixtures of additives, coating matrix type and coating fillers. The type of silicone fluid additive was the primary controlling factor in barnacle fouling-release. The type of silicone matrix in which the fluid resided was found to alter the effect on fouling-release. Two PDMS fluids, DMSC15 and DBE224, significantly reduced the adhesion strength of barnacles compared to unmodified elastomers. Optimum fouling-release performance was dependent on the interaction of fluid type and elastomeric matrix.     

Functional expression and cellular localization of the Na+/H+ exchanger Sod2 of the fission yeast Schizosaccharomyces pombe

In the fission yeast Schizosaccharomyces pombe, the Na+/H+ exchanger, Sod2, plays a major role in the removal of excess intracellular sodium, and its disruption results in a sodium-sensitive phenotype. We examined the subcellular distribution and dynamics of Sod2 expression in S. pombe using a sod2-GFP fusion protein under the control of an attenuated version of the inducible nmt promoter. Sod2 was localized throughout the plasma membrane, the nuclear envelope, and some internal membrane systems. In exponentially growing cells, in which sod2-GFP was expressed and then the promoter turned-off, previously synthesized sod2-GFP was stable for long periods and found localized to the plasma membrane in the medial regions of the cell. It was not present at the actively growing cell ends. This suggests that these regions of the cell contain old plasma membrane protein vs. newly synthesized plasma membrane without Sod2 at the growing ends. Sod2 localization was not affected by salt stress. The results suggest that Sod2 is both a plasma membrane protein and is present in intracellular membranes. It is likely tethered within discrete regions of the plasma membrane and is not free to diffuse throughout the bilayer.     

Evidence for a complex demographic history of chimpanzees

To characterize patterns of genomic variation in central chimpanzees(Pan troglodytes troglodytes) and gain insight into their evolution,we sequenced nine unlinked, intergenic regions, representinga total of 19,000 base pairs, in 14 individuals. When theseDNA sequences are compared with homologous sequences previouslycollected in humans and in western chimpanzees (Pan troglodytesverus), nucleotide diversity is higher in central chimpanzeesthan in western chimpanzees or in humans. Consistent with alarger effective population size of central chimpanzees, levelsof linkage disequilibrium are lower than in humans. Patternsof linkage disequilibrium further suggest that homologous geneconversion may be an important contributor to genetic exchangeat short distances, in agreement with a previous study of thesame DNA sequences in humans. In central chimpanzees, but notin western chimpanzees, the allele frequency spectrum is significantlyskewed towards rare alleles, pointing to population size changesor fine-scale population structure. Strikingly, the extent ofgenetic differentiation between western and central chimpanzeesis much stronger than what is seen between human populations.This suggests that careful attention should be paid to geographicsampling in studies of chimpanzee genetic variation.     

Synthesis of unnatural 7-substituted-1-(2-deoxy-beta-D-ribofuranosyl)isocarbostyrils: "thymine replacement" analogs of deoxythymidine for evaluation as antiviral and anticancer agents

A group of unnatural 1-(2-deoxy-beta-D-ribofuranosyl)isocarbostyrils having a variety of C-7 substituents [H, 4,7-(NO2)2, I, CF3, CN, (E)-CH=CH-I, -C triple bond CH, -C triple bond C-I, -C triple bond C-Br, -C=C-Me], designed as nucleoside mimics, were synthesized for evaluation as anticancer and antiviral agents. This class of compounds exhibited weak cytotoxicity in a MTT assay (CC50 = 10(-3) to 10(-5) M range) with the 4,7-dinitro derivative being the most cytotoxic, relative to thymidine (CC50 = 10(-3) to 10(-5) M range), against a variety of cancer cell lines. The 4,7-dinitro, 7-I and 7-C triple bond CH compounds exhibited similar cytotoxicity against non-transfected (KBALB, 143B), and HSV-1 TK+ gene transfected (KBALB-STK, 143B-LTK) cancer cell lines possessing the herpes simplex virus type 1 (HSV-1) thymidine kinase gene (TK+). This observation indicates that these compounds are not substrates for HSV type-1 TK, and are therefore unlikely to be useful in gene therapy based on the HSV gene therapy paradigm.     

Plasma membrane receptors for the cancer-regulating progesterone metabolites, 5alpha-pregnane-3,20-dione and 3alpha-hydroxy-4-pregnen-20-one in MCF-7 breast cancer cells

Recent observations indicate that the progesterone metabolite, 5alpha-pregnane-3,20-dione (5alphaP), which is produced at higher levels in tumorous breast tissue, promotes cell proliferation and detachment, whereas 3alpha-hydroxy-4-pregnen-20-one (3alphaHP), which is produced at higher levels in nontumorous breast tissue, suppresses proliferation and detachment of MCF-7 breast cancer cells. The objective of the current study was to determine the presence and characteristics of binding sites for these endogenous putative cancer-regulating steroid hormones. Radiolabeled 5alphaP and 3alphaHP were used in radioligand binding assays on MCF-7 cell (membrane, cytosolic, and nuclear) fractions. Binding of [(3)H]5alphaP and [(3)H]3alphaHP was observed only in the plasma membrane fraction, whereas estradiol binding sites were confirmed in the cytosolic and nuclear fractions. The respective membrane binding sites exhibited specificity for the 5alphaP and 3alphaHP ligands with no appreciable displacement at 200- to 500-fold excess by other steroids. The association rate constants were calculated as 0. 107/min and 0.0089/min and the dissociation rate constants were 0. 049 9 and 0.011 for 5alphaP and 3alphaHP, respectively. Saturation analyses indicated single classes of molecules with dissociation constants of 4.5 and 4.87 nM and receptor densities of 486 and 629 fmol/mg protein, respectively, for 5alphaP and 3alphaHP. Exposure of MCF-7 cells to estradiol for 1, 24, 48, and 72 h resulted in 2.3, 4. 2-, 2.99-, and 1.7-fold increases, respectively, in 5alphaP receptor density. 3alphaHP resulted in partial suppression of the estradiol-mediated increase in 5alphaP receptor density. This is the first report of receptors for the progesterone metabolites, 5alphaP and 3alphaHP, of their occurrence in breast cancer cell membranes, and of the induction of 5alphaP receptors by estradiol. The results provide further support for the potential importance of progesterone metabolites in breast cancer.     

The dreams of women with and without severe emotional behavioral premenstrual symptoms.

Women with severe premenstrual symptoms, who tend to have more mood changes during the late luteal phase of their cycle than do women with few or no symptoms, often complain of having unpleasant dreams. This study examined whether these women experienced more intense negative dream emotions during the late luteal phase of their cycle compared with women with minimal symptoms. It also examined whether there was a relationship between presleep mood and dream affect. Seventeen women participated in the study (9 with severe symptoms, 8 with minimal symptoms). Analyses of variance revealed an increase in negative dream affect and misfortunes during the late luteal phase (p     

MOLECULAR AND MORPHOMETRIC DATA PINPOINT SPECIES BOUNDARIES IN HALIMEDA SECTION RHIPSALIS (BRYOPSIDALES,CHLOROPHYTA)1

Molecular systematic studies have changed the face of algal taxonomy. Particularly at the species level, molecular phylogenetic research has revealed the inaccuracy of morphology‐based taxonomy: Cryptic and pseudo‐cryptic species were shown to exist within many morphologically conceived species. This study focused on section Rhipsalis of the green algal genus Halimeda. This section was known to contain cryptic diversity and to comprise species with overlapping morphological boundaries. In the present study, species diversity within the section and identity of individual specimens were assessed using ITS1–5.8S–ITS2 (nrDNA) and rps3 (cpDNA) sequence data. The sequences grouped in a number of clear‐cut genotypic clusters that were considered species. The same specimens were subjected to morphometric analysis of external morphological and anatomical structures. Morphological differences between the genotypic cluster species were assessed using discriminant analysis. It was shown that significant morphological differences exist between genetically delineated species and that allocation of specimens to species on the basis of morphometric variables is nearly perfect. Anatomical characters yielded better results than external morphological characters. Two approaches were offered to allow future morphological identifications: a probabilistic approach based on classification functions of discriminant analyses and the classical approach of an identification key.     

DIVERSITY IN THE GENUS SKELETONEMA (BACILLARIOPHYCEAE). II. AN ASSESSMENT OF THE TAXONOMY OF S. COSTATUM‐LIKE SPECIES WITH THE DESCRIPTION OF FOUR NEW SPECIES1

The morphology of strains of Skeletonema Greville emend Sarno et Zingone was examined in LM, TEM, and SEM and compared with sequence data from nuclear small subunit rDNA and partial large subunit rDNA. Eight distinct entities were identified, of which four were known: S. menzelii Guillard, Carpenter et Reimann; S. pseudocostatum Medlin emend. Zingone et Sarno; S. subsalsum (Cleve) Bethge; and S. tropicum Cleve. The other four species were new: S. dohrnii Sarno et Kooistra sp. nov., S. grethae Zingone et Sarno sp. nov., S. japonicum Zingone et Sarno sp. nov., and S. marinoi Sarno et Zingone sp. nov. Skeletonema species fell into four morphologically distinct groups corresponding to four lineages in the small subunit and large subunit trees. Lineage I included S. pseudocostatum, S. tropicum, S. grethae, and S. japonicum. All have external processes of the fultoportulae with narrow tips that connect with those of sibling cells via fork‐, knot‐, or knuckle‐ like junctions. Lineage II included only the solitary species S. menzelii. Lineage III comprised S. dohrnii and S. marinoi. This latter pair have flattened and flared extremities of the processes of the fultoportulae, which interdigitate with those of contiguous valves without forming knots or knuckles. Lineage IV only contained the brackish water species S. subsalsum. Some species also differ in their distribution and seasonal occurrence. These findings challenge the concept of S. costatum as a single cosmopolitan and opportunistic species and calls for reinterpretation of the vast body of research data based on this species.