Genome Sequence of Staphylococcus epidermidis Strain AU12-03, Isolated from an Intravascular Catheter

In recent years, Staphylococcus epidermidis has become a major nosocomial pathogen and the most common cause of intravascular catheter-related bacteremia, which can increase morbidity and mortality and significantly affect patient recovery. We report a draft genome sequence of Staphylococcus epidermidis AU12-03, isolated from an intravascular catheter tip.     

Peptide N-alkylamides by solid phase synthesis

Three new resins have been developed that allow for the solid phase synthesis of C-terminal peptide N-alkylamides using Boc amino acids, usual side chain protecting groups and hydrogen fluoride cleavage and deprotection. These resins were prepared by reacting the appropriate alkylamine (NH2CH3, NH2CH2CH3, NH2CH2CF3) to Merrifield's 1% divinylbenzene cross-linked chloromethylated polystyrene resin. The application of these resins to the synthesis of C-terminal GnRH N-alkylamides illustrates the versatility of this approach. GnRH analogs were tested for their ability to release LH from cultured rat anterior pituitary cells. [DGlu6, Pro9-NHCH2CH3]-GnRH was synthesized for the first time using the solid phase approach and found to be three times more potent than [DGlu6]-GnRH. Other analogs including [DTrp6, Pro9-NHCH2CH3]-GnRH, [DAla6, Pro9-NHCH2CF3]-GnRH and related peptides were found to be equipotent and to have the same properties (HPLC retention times, amino acid analysis and specific rotation) as the corresponding peptides synthesized using less amenable strategies; yields were equivalent or better than those reported earlier.     

Phagocytosis is coupled to the formation of phagosome-associated podosomes and a transient disruption of podosomes in human macrophages

Phagocytosis consists in ingestion and digestion of large particles, a process strictly dependent on actin re-organization. Using synchronized phagocytosis of IgG-coated latex beads (IgG-LB), zymosan or serum opsonized-zymosan, we report the formation of actin structures on both phagocytic cups and closed phagosomes in human macrophages. Their lifespan, size, protein composition and organization are similar to podosomes. Thus, we called these actin structures phagosome-associated podosomes (PAPs). Concomitantly to the formation of PAPs, a transient disruption of podosomes occurred at the ventral face of macrophages. Similarly to podosomes, which are targeted by vesicles containing proteases, the presence of PAPs correlated with the maturation of phagosomes into phagolysosomes. The ingestion of LB without IgG did not trigger PAPs formation, did not lead to podosome disruption and maturation to phagolysosomes, suggesting that these events are linked together. Although similar to podosomes, we found that PAPs differed by being resistant to the Arp2/3 inhibitor CK666. Thus, we describe a podosome subtype which forms on phagosomes where it probably serves several tasks of this multifunctional structure.     

Characterization of the microtubule movement produced by sea urchin egg kinesin

We have used an in vitro assay to characterize some of the motile properties of sea urchin egg kinesin. Egg kinesin is purified via 5'-adenylyl imidodiphosphate-induced binding to taxol-assembled microtubules, extraction from the microtubules in ATP, and gel filtration chromatography (Scholey, J. M., Porter, M. E., Grissom, P. M., and McIntosh, J. R. (1985) Nature 318, 483-486). This partially purified kinesin is then adsorbed to a glass coverslip, mixed with microtubules and ATP, and viewed by video-enhanced differential interference contrast microscopy. The microtubule translocating activity of the purified egg kinesin is qualitatively similar to the analogous activity observed in crude extracts of sea urchin eggs and resembles the activity of neuronal kinesin with respect to both the maximal rate (greater than 0.5 micron/s) and the direction of movement. Axonemes glide on a kinesin-coated coverslip toward their minus ends, and kinesin-coated beads translocate toward the plus ends of centrosome microtubules. Sea urchin egg kinesin is inhibited by high concentrations of SH reagents ([N-ethylmaleimide] greater than 3-5 mM), vanadate greater than 50 microM, and [nonhydrolyzable nucleotides] greater than or equal to [MgATP]. The nucleotide requirement of sea urchin egg kinesin is fairly broad (ATP greater than GTP greater than ITP), and the rate of microtubule movement increases in a saturable fashion with the [ATP]. We conclude that the motile activity of egg kinesin is indistinguishable from that of neuronal kinesin. We propose that egg kinesin may be associated with microtubule-based motility in vivo.     

Predator detection and avoidance by starlings under differing scenarios of predation risk

Practically all animals must find food while avoiding predators.An individual's perception of predation risk may depend on manyfactors, such as distance to refuge and group size, but it isunclear whether individuals respond to different factors ina similar manner. We tested whether flocks of foraging starlingsresponded in the same way to an increased perception of predationrisk by assessing three factors: (1) neighbor distances, (2)habitat obstruction, and (3) recent exposure to a predator.We found that in all three scenarios of increased risk, starlingsreduced their interscan intervals (food-searching bouts), whichincreased the frequency of their vigilance periods. We thenexamined how one of these factors, habitat obstruction, affectedescape speed by simulating an attack with a model predator.Starlings were slower to respond in visually obstructed habitats(long grass swards) and slower when they had their head downin obstructed habitats than when they had their head down inopen habitats. In addition, reaction times were quicker whenstarlings could employ their peripheral fields of vision. Ourresults demonstrate that different sources of increased riskcan generate similar behavioral responses within a species.The degree of visibility in the physical and social environmentaffects both the actual and perceived risk of predation.     

Abortion is incommensurable with fetal alcohol syndrome

A recent article argued for the immorality of abortion regardless of personhood status by comparing the impairment caused by fetal alcohol syndrome to the impairment caused by abortion. I argue that two of the premises in this argument fail and that, as such, one cannot reasonably attribute moral harms to abortion on the basis of the moral harms caused by fetal alcohol syndrome. The impairment argument relies on an inconsistent instantiation, which undermines the claim that personhood is irrelevant, and it does not fulfill its own ceteris paribus clause, which demands that no additional benefit be gained from abortion that would not be gained from causing fetal alcohol syndrome.     

RECENT APPEARANCE OF CYLINDROSPEMOPSIS (CYANOBACTEIUA) IN FIVE HYPEREUTROPHIC FLORIDA LAKES1

Observations of historical and recent phytoplankton samples from five hypereutrophic Florida lakes indicate that nitrogen-fixing cyanobacteria in the genus Cylindrospermopsis Seenayya et Subba Raju have entered these water-bodies sometime in the last 30 years. Cylindrospermopsis forms a year-round bloom in one of the five lakes, dominates seasonally in another, and is at least at times an important component of the phytoplankton community in the remaining three. The increase in abundance of Cylindrospermopsis in Florida lakes could have implications for water management.     

Growth Phase-Dependent Regulation of Vsr Endonuclease May Contribute to 5-Methylcytosine Mutational Hot Spots in Escherichia coli

Using rabbit polyclonal antibodies, we have shown that the Dcm cytosine methylase of Escherichia coli is maintained at a constant level during cell growth, while Vsr endonuclease levels are growth phase dependent. Decreased production of Vsr relative to Dcm during the log phase may contribute substantially to the mutability of 5-methylcytosine.