Huntingtin-interacting protein HIP14 is a palmitoyl transferase involved in palmitoylation and trafficking of multiple neuronal proteins

In neurons, posttranslational modification by palmitate regulates the trafficking and function of signaling molecules, neurotransmitter receptors, and associated synaptic scaffolding proteins. However, the enzymatic machinery involved in protein palmitoylation has remained elusive. Here, using biochemical assays, we show that huntingtin (htt) interacting protein, HIP14, is a neuronal palmitoyl transferase (PAT). HIP14 shows remarkable substrate specificity for neuronal proteins, including SNAP-25, PSD-95, GAD65, synaptotagmin I, and htt. Conversely, HIP14 is catalytically invariant toward paralemmin and synaptotagmin VII. Exogenous HIP14 enhances palmitoylation-dependent vesicular trafficking of several acylated proteins in both heterologous cells and neurons. Moreover, interference with endogenous expression of HIP14 reduces clustering of PSD-95 and GAD65 in neurons. These findings define HIP14 as a mammalian palmitoyl transferase involved in the palmitoylation and trafficking of multiple neuronal proteins.     

Trichloroethylene Degradation by Toluene-Oxidizing Bacteria Grown on Non-aromatic Substrates

The potential of trichloroethylene (TCE) to induce and non-aromatic growth substrates to support TCE degradation in five strains (Pseudomonas mendocina KR1, Ralstonia pickettii PKO1, Pseudomonas putida F1, Burkholderia cepacia G4, B. cepacia PR1) of toluene-oxidizing bacteria was examined. LB broth and acetate did not support TCE degradation in any of the wild-type strains. In contrast, fructose supported the highest specific levels of TCE oxidation observed in each of the strains tested, except B. cepacia G4. We discuss the potential mechanisms and implications of this observation. In particular, cells of P. mendocina KR1 degraded significant amounts of TCE during cell growth on non-aromatic substrates. Apparently, TCE degradation was not completely constrained by any given factor in this microorganism, as was observed with P. putida F1 (TCE was an extremely poor substrate) or B. cepacia G4 (lack of oxygenase induction by TCE). Our results indicate that multiple physiological traits are required to enable useful TCE degradation by toluene-oxidizing bacteria in the absence of aromatic cosubstrates. These traits include oxygenase induction, effective TCE turnover, and some level of resistance to TCE mediated toxicity.     

Policy implications of human-accelerated nitrogen cycling

The human induced input of reactive N into the globalbiosphere has increased to approximately 150 Tg N eachyear and is expected to continue to increase for theforeseeable future. The need to feed (125 Tg N) andto provide energy (25 Tg N) for the growing worldpopulation drives this trend. This increase inreactive N comes at, in some instances, significantcosts to society through increased emissions of NO_x,NH₃, N₂O and NO₃ ^– and deposition of NO_y and NH_x.In the atmosphere, increases in tropospheric ozone andacid deposition (NO_y and NH_x) have led toacidification of aquatic and soil systems and toreductions in forest and crop system production. Changes in aquatic systems as a result of nitrateleaching have led to decreased drinking water quality,eutrophication, hypoxia and decreases in aquatic plantdiversity, for example. On the other hand, increaseddeposition of biologically available N may haveincreased forest biomass production and may havecontributed to increased storage of atmospheric CO₂ inplant and soils. Most importantly, syntheticproduction of fertilizer N has contributed greatly tothe remarkable increase in food production that hastaken place during the past 50 years.The development of policy to control unwanted reactiveN release is difficult because much of the reactive Nrelease is related to food and energy production andreactive N species can be transported great distancesin the atmosphere and in aquatic systems. There aremany possibilities for limiting reactive N emissionsfrom fuel combustion, and in fact, great strides havebeen made during the past decades. Reducing theintroduction of new reactive N and in curtailing themovement of this N in food production is even moredifficult. The particular problem comes from the factthat most of the N that is introduced into the globalfood production system is not converted into usableproduct, but rather reenters the biosphere as asurplus. Global policy on N in agriculture isdifficult because many countries need to increase foodproduction to raise nutritional levels or to keep upwith population growth, which may require increaseduse of N fertilizers. Although N cycling occurs atregional and global scales, policies are implementedand enforced at the national or provincial/statelevels. Multinational efforts to control N loss tothe environment are surely needed, but these effortswill require commitments from individual countries andthe policy-makers within those countries.     

Family-level covariation between parasite resistance and mating system in a hermaphroditic freshwater snail

Genetic compatibility, nonspecific defenses, and environmental effects determine parasite resistance. Host mating system (selfing vs. outcrossing) should be important for parasite resistance because it determines the segregation of alleles at the resistance loci and because inbreeding depression may hamper immune defenses. Individuals of a mixed mating hermaphroditic freshwater snail, Lymnaea ovata, are commonly infected by a digenetic trematode parasite, Echinoparyphium recurvatum. We examined covariation between quantitative resistance to novel parasites and mating system by exposing snail families from four populations that differed by their inbreeding coefficients. We found that resistance was unrelated to inbreeding coefficient of the population, suggesting that the more inbred populations did not carry higher susceptibility load than the less inbred populations. Most of the variation in resistance was expressed among the families within the populations. In the population with the lowest inbreeding coefficient, resistance increased with outcrossing rate of the family, as predicted if selfing had led to inbreeding depression. In the other three populations with higher inbreeding coefficients, resistance was unrelated to outcrossing rate. The results suggest that in populations with higher inbreeding some of the genetic load has been purged, uncoupling the predicted relationship between outcrossing rate and resistance. Snail families also displayed crossing reaction norms for resistance when tested in two environments that presented low and high immune challenge, suggesting that genotype-by-environment interactions are important for parasite resistance.     

Functional Imaging of Mitochondria in Saponin-permeabilized Mice Muscle Fibers

Confocal laser-scanning and digital fluorescence imaging microscopy were used to quantify the mitochondrial autofluorescence changes of NAD(P)H and flavoproteins in unfixed saponin-permeabilized myofibers from mice quadriceps muscle tissue. Addition of mitochondrial substrates, ADP, or cyanide led to redox state changes of the mitochondrial NAD system. These changes were detected by ratio imaging of the autofluorescence intensities of fluorescent flavoproteins and NAD(P)H, showing inverse fluorescence behavior. The flavoprotein signal was colocalized with the potentiometric mitochondria-specific dye dimethylaminostyryl pyridyl methyl iodide (DASPMI), or with MitoTracker™ Green FM, a constitutive marker for mitochondria. Within individual myofibers we detected topological mitochondrial subsets with distinct flavoprotein autofluorescence levels, equally responding to induced rate changes of the oxidative phosphorylation. The flavoprotein autofluorescence levels of these subsets differed by a factor of four. This heterogeneity was substantiated by flow-cytometric analysis of flavoprotein and DASPMI fluorescence changes of individual mitochondria isolated from mice skeletal muscle. Our data provide direct evidence that mitochondria in single myofibers are distinct subsets at the level of an intrinsic fluorescent marker of the mitochondrial NAD–redox system. Under the present experimental conditions these subsets show similar functional responses.     

EVIDENCE FOR METHYL JASMONATE-INDUCED PHLOROTANNIN PRODUCTION IN FUCUS VESICULOSUS (PHAEOPHYCEAE)

The plant growth regulators jasmonic acid and methyl jasmonate (MeJA) have recently been identified in a variety of marine algae; however, their role in these organisms is currently unknown. Here we report that exposure to MeJA, during periods of tidal emergence causes the induction of polyphenolic chemical defenses (the phlorotannins) in two populations of the common rockweed Fucus vesiculosus (Linnaeus). Phlorotannin concentrations were up to 1.6 times higher in the growing apices of F. vesiculosus from both Avery Point (Connecticut, USA) and Roosevelt Inlet (Delaware, USA) within 10–14 days after a single brief exposure to airborne MeJA at concentrations ranging from 5.42 to 542 nM. The timing and magnitude of this induced increase in phlorotannin concentration are similar to that caused by real and simulated herbivory, raising the question of whether jasmonates, or their oxylipin relatives, are natural elements of antiherbivore responses in Fucus , as they are in vascular plants.     

Preparation of no-carrier-added technetium-99m complexes via metal-assisted cleavage from a solid phase

A novel method for the preparation of no-carrier-added (nca) complexes [99mTc(CO)3L] (L = diethylenetriamine or picolylamine-N-acetic acid) is described. The ligands were covalently bound to a solid support of organic polymers via formation of a tertiary amine from the chelating unit. This C-N bond to the solid phase is selectively cleaved during the formation of the technetium complexes by intramolecular nucleophilic attack of a remaining hydroxy ligand to the alpha-carbon. The complex [99mTc(CO)3L] is released into solution while uncomplexed ligand and uncleaved complex remain solid-phase bound. High specific activity technetium complexes can then be isolated by simple filtration. Cleavage yield depends on temperature, pH, and ligand. Up to 50% release from the solid phase could be achieved under optimized conditions. Corresponding to the 99mTc concentration, free ligand is present in concentrations lower than 10(-7) M. If a targeting vector is conjugated to these ligands, no-carrier-added radiopharmaceuticals can be prepared in that way.     

Redox-functionalised ligands: a 1,10-phenanthroline carrying two ferrocenyl groups

The redox-functionalised diimine ligand 3,8-di-n-pentyl-4,7-di(ferrocenylethinyl)-1,10-phenanthroline (3) was synthesised and used for the preparation of the homoleptic zinc complex [Zn(3)₂][PF₆]₂, whose cyclic voltammogram shows non-interacting ferrocenyl units, affording the hexacationic [Zn(3)₂]⁶⁺ in a four-electron oxidation.     

Catarrhine primate divergence dates estimated from complete mitochondrial genomes: concordance with fossil and nuclear DNA evidence

Accurate divergence date estimates improve scenarios of primate evolutionary history and aid in interpretation of the natural history of disease-causing agents. While molecule-based estimates of divergence dates of taxa within the superfamily Hominoidea (apes and humans) are common in the literature, few such estimates are available for the Cercopithecoidea (Old World monkeys), the sister taxon of the hominoids in the primate infraorder Catarrhini. To help fill this gap, we have sequenced the entire mitochondrial DNA (mtDNA) genomes from a representative of three cercopithecoid tribes, Cercopithecini (Chlorocebus aethiops), Colobini (Colobus guereza), and Presbytini (Trachypithecus obscurus), and analyzed these new data together with other catarrhine mtDNA genomes available in public databases. Molecular divergence date estimates are dependent on calibration points gleaned from the paleontological record. We defined criteria for the selection of good calibration points and identified three points meeting these criteria: Homo-Pan, 6.0 Ma; Pongo-hominines, 14.0 Ma; hominoid/cercopithecoid, 23.0 Ma. Because a uniform molecular clock does not fit the catarrhine mtDNA data, we estimated divergence dates using a penalized likelihood and a Bayesian method, both of which take into account the effects of rate differences on lineages, phylogenetic tree structure, and multiple calibration points. The penalized likelihood method applied to the coding regions of the mtDNA genome yielded the following divergence date estimates, with approximate 95% confidence intervals: cercopithecine-colobine, 16.2 (14.4-17.9) Ma; colobin-presbytin, 10.9 (9.6-12.3) Ma; cercopithecin-papionin, 11.6 (10.3-12.9) Ma; and Macaca-Papio, 9.8 (8.6-10.9) Ma. Within the hominoids, the following dates were inferred: hylobatid-hominid, 16.8 (15.0-18.5) Ma; Gorilla-Homo+Pan, 8.1 (7.1-9.0) Ma; Pongo pygmaeus pygmaeus-P. p. abelii, 4.1 (3.5-4.7) Ma; and Pan troglodytes-P. paniscus, 2.4 (2.0-2.7) Ma. These dates were similar to those found using penalized likelihood on other subsets of the data, but slightly younger than several of the Bayesian estimates.