Jurassic PARK2: You eat your mitochondria,and you are what your mitochondria eat

Park2/Parkin is a central mediator of selective mitochondrial autophagy for mitochondrial quality control. We showed in mouse hearts that PINK1/Mfn2/Park2 mediated generalized mitophagy is essential to the normal perinatal transition from fetal mitochondria that prefer carbohydrates as metabolic substrates to adult fatty-acid metabolizing mitochondria. Our findings demonstrate how functional interactions between mitophagic mitochondrial removal and biogenic mitochondrial replacement facilitate metabolic maturation of the heart.     

High-pressure treatment of polytene chromosomes improves structural resolution

The exceptional cytology provided by polytene chromosomes has made Drosophila melanogaster a premier model for chromosome studies, but full exploitation of polytene cytology is impeded by the difficulty in preparing high-quality chromosome spreads. Here we describe use of high pressure to produce formaldehyde-fixed chromosome spreads, which upon light-microscopy examination reveal structural detail previously observed only in electron microscopy preparations. We demonstrate applications to immunofluorescence and in situ hybridization.     

Selective Removal of Nitrogen from Quinoline and Petroleum by Pseudomonas ayucida IGTN9m

Enrichment culture experiments employing soil and water samples obtained from petroleum-contaminated environments succeeded in the isolation of a pure culture possessing the ability to utilize quinoline as a sole nitrogen source but did not utilize quinoline as a carbon source. This culture was identified as Pseudomonas ayucida based on a partial 16S rRNA gene sequence, and the strain was given the designation IGTN9m. Examination of metabolites using thin-layer chromatography and gas chromatography-mass spectrometry suggests that P. ayucida IGTN9m converts quinoline to 2-quinolinone and subsequently to 8-hydroxycoumarin. Resting cells of P. ayucida IGTN9m were shown to be capable of selectively removing about 68% of quinoline from shale oil in a 16-h treatment time. These results suggest that P. ayucida IGTN9m may be useful in petroleum biorefining for the selective removal of organically bound nitrogen from petroleum.     

Aggregation of amphipathic peptides at an aqueous–organic interface using coarse-grained simulations

The effect of an aqueous/organic interface on the folding and aggregation of amphipathic peptides is examined by applying discontinuous molecular dynamics (DMD) simulations combined with an intermediate resolution protein model, PRIME20, to a peptide/interface system. The systems contain 48 (KLLK)₄ peptides in random coil or α-helical conformations interacting with both strong and weak interfaces. In the absence of an interface, most of the oligomers form helical bundles, a small fraction of which convert to β-sheets when the temperature is above the folding transition. Adding a weak interface decreases oligomer formation above the folding temperature and increases it below. Little monolayer formation is observed at the weak interface; instead reversible adsorption increases the local peptide concentration near the interface, promoting helical bundle formation in the aqueous phase below the folding temperature and β-sheet formation above the folding temperature. Introducing a strong interface leads to irreversible adsorption, promoting formation of helical monolayers below the folding temperature and mixed β-sheet/amorphous monolayers above the folding temperature. The (KLLK)₄ peptide is more likely to adsorb to the interface when it is in an α-helical conformation, as opposed to a random coil, because of its larger hydrophobic moment.     

Contrasting adaptive immune defenses and blood parasite prevalence in closely related Passer sparrows

Immune system components differ in their functions and costs, and immune defense profiles are likely to vary among species with differing ecologies. We compared adaptive immune defenses in two closely related species that have contrasting inflammatory immune responses, the widespread and abundant house sparrow (Passer domesticus) and the less abundant tree sparrow (Passer montanus). We found that the house sparrow, which we have previously shown mounts weaker inflammatory responses, exhibits stronger adaptive immune defenses, including antibody responses, natural antibody titers, and specific T-cell memory, than the tree sparrow. Conversely, tree sparrows, which mount strong inflammatory responses, also mount stronger nonspecific inflammatory T-cell responses but weaker specific adaptive responses. Prevalence of avian malaria parasite infections, which are controlled by adaptive immune defenses, was higher in the geographically restricted tree sparrow than in the ubiquitous house sparrow. Together these data describe distinct immune defense profiles between two closely related species that differ greatly in numbers and distributions. We suggest that these immunological differences could affect fitness in ways that contribute to the contrasting abundances of the two species in North American and Western Europe.     

Synthesis and biological evaluation of novel mono- and bivalent ASGP-R-targeted drug-conjugates

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatile synthetic approach to novel mono- and multivalent drug-conjugates containing N-acetyl-2-deoxy-2-aminogalactopyranose and anticancer drug – paclitaxel (PTX). Several molecules have demonstrated high affinity towards ASGP-R and good stability under physiological conditions, significant in vitro anticancer activity comparable to PTX, as well as good internalization via ASGP-R-mediated endocytosis. Therefore, the conjugates with the highest potency can be regarded as a promising therapeutic option against HCC.     

Influence of oligomerization state on the structural properties of invasion plasmid antigen B from Shigella flexneri in the presence and absence of phospholipid membranes

Shigella flexneri causes bacillary dysentery, an important cause of mortality among children in the developing world. Shigella secretes effector proteins via its type III secretion system (T3SS) to promote bacterial uptake into human colonic epithelial cells. The T3SS basal body spans the bacterial cell envelope anchoring a surface‐exposed needle. A pentamer of invasion plasmid antigen D lies at the nascent needle tip and invasion plasmid antigen B (IpaB) is recruited into the needle tip complex on exposure to bile salts. From here, IpaB forms a translocon pore in the host cell membrane. Although the mechanism by which IpaB inserts into the membrane is unknown, it was recently shown that recombinant IpaB can exist as either a monomer or tetramer. Both of these forms of IpaB associate with membranes, however, only the tetramer forms pores in liposomes. To reveal differences between these membrane‐binding events, Cys mutations were introduced throughout IpaB, allowing site‐specific fluorescence labeling. Fluorescence quenching was used to determine the influence of oligomerization and/or membrane association on the accessibility of different IpaB regions to small solutes. The data show that the hydrophobic region of tetrameric IpaB is more accessible to solvent relative to the monomer. The hydrophobic region appears to promote membrane interaction for both forms of IpaB, however, more of the hydrophobic region is protected from solvent for the tetramer after membrane association. Limited proteolysis demonstrated that changes in IpaB's oligomeric state may determine the manner by which it associates with phospholipid membranes and the subsequent outcome of this association. Proteins 2014; 82:3013–3022. © 2014 Wiley Periodicals, Inc.     

LUMBAR SYMPATHECTOMY IN OLDER PATIENTS

Of 43 older patients (aged 65 to 83 years) with arteriosclerosis obliterans treated by lumbar sympathectomy for one or both limbs, 19 had excellent result, 13 had fair result and four had poor result. One died postoperatively and six later. Results were better than prognosticated from response to sympathetic block. Thirty-four patients considered the operation worth while and twelve, after unilateral sympathectomy, requested operation for the other limb also. Twenty-four after operation could walk farther without claudication.     

Periplasmic Acid Stress Increases Cell Division Asymmetry (Polar Aging) of Escherichia coli

Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed polar aging or cell division asymmetry. It is unknown whether cell division asymmetry can arise from a periplasmic stress, such as the stress of extracellular acid, which is mediated by the periplasm. We tested the effect of periplasmic acid stress on growth and division of adherent single cells. We tracked individual cell lineages over five or more generations, using fluorescence microscopy with ratiometric pHluorin to measure cytoplasmic pH. Adherent colonies were perfused continually with LBK medium buffered at pH 6.00 or at pH 7.50; the external pH determines periplasmic pH. In each experiment, cell lineages were mapped to correlate division time, pole age and cell generation number. In colonies perfused at pH 6.0, the cells inheriting the oldest pole divided significantly more slowly than the cells inheriting the newest pole. In colonies perfused at pH 7.50 (near or above cytoplasmic pH), no significant cell division asymmetry was observed. Under both conditions (periplasmic pH 6.0 or pH 7.5) the cells maintained cytoplasmic pH values at 7.2–7.3. No evidence of cytoplasmic protein aggregation was seen. Thus, periplasmic acid stress leads to cell division asymmetry with minimal cytoplasmic stress.