A genome-wide screen for genes affecting eisosomes reveals Nce102 function in sphingolipid signaling

The protein and lipid composition of eukaryotic plasma membranes is highly dynamic and regulated according to need. The sphingolipid-responsive Pkh kinases are candidates for mediating parts of this regulation, as they affect a diverse set of plasma membrane functions, such as cortical actin patch organization, efficient endocytosis, and eisosome assembly. Eisosomes are large protein complexes underlying the plasma membrane and help to sort a group of membrane proteins into distinct domains. In this study, we identify Nce102 in a genome-wide screen for genes involved in eisosome organization and Pkh kinase signaling. Nce102 accumulates in membrane domains at eisosomes where Pkh kinases also localize. The relative abundance of Nce102 in these domains compared with the rest of the plasma membrane is dynamically regulated by sphingolipids. Furthermore, Nce102 inhibits Pkh kinase signaling and is required for plasma membrane organization. Therefore, Nce102 might act as a sensor of sphingolipids that regulates plasma membrane function.     

Differentiated ZZ/ZW sex chromosomes in Apareiodon ibitiensis (Teleostei,Parodontidae): cytotaxonomy and biogeography

Conventional and molecular chromosomal analyses were carried out on three populations of Apareiodon ibitiensis sampled from the hydrographic basins of the São Francisco River and Upper Paraná River (Brazil). The results reveal a conserved diploid number (2n = 54 chromosomes), a karyotype formula consisting of 50 m‐sm + 4st and a ZZ/ZW sex chromosome system that has not been previously identified for the species. C‐banding analysis with propidium iodide staining revealed centromeric and terminal bands located in the chromosomes of the specimens from the three populations and allowed the identification of heteromorphism of heterochromatin regions in the Z and W chromosomes. The number of 18S sites located through fluorescent in situ hybridization (FISH) varied between the populations of the São Francisco and Upper Paraná Rivers. The location of 5S rDNA sites proved comparable in one pair of metacentric chromosomes. Thus, the present study proposes a ZZ/ZW sex chromosome system for A. ibitiensis among the Parodontidae, and a hypothesis is presented regarding possible W chromosome differentiation stages in this species through DNA accumulation, showing geographical variations for this characteristic, possibly as a consequence of geographical reproductive isolation.     

A case study in converting disposable process scouting devices into disposable bioreactors as a future bioprocessing tool

In this study, we perform mass transfer characterization (k_La) on a novel mechanically driven/stirred Process Scouting Device, PSD, (SuperSpinner D 1000®, SSD) and demonstrate that this novel device can be viewed as disposable bioreactor. Using patch‐based optical sensors, we were able to monitor critical cell culture environmental conditions such as dissolved oxygen (DO) and pH in SSD for comparison to a 1 L standard spinner (SS) flask. We also coupled these mass transfer studies with mixing time studies where we observed relative high mixing times (5.2 min) that are typically observed in production scale bioreactors. Decreasing the mixing time 3.5‐fold resulted in 30% increase in k_La (from 2.3 to 3.0 h^?1) and minimum DO level increased from 0% to 20% for our model hybridoma cell line. Finally, maximum viable cell density and protein titer stayed within ±20% of historical data, from our standard 5 L stirred bioreactor (Biostat®) operated under active DO control. Biotechnol. Bioeng. 2012; 109: 2790–2797. © 2012 Wiley Periodicals, Inc.     

How does a Psittacanthus robustus Mart. population structure relate to a Vochysia thyrsoidea Pohl. host population?

Distribution of parasitic plants is directly linked with the distribution of host species and behavioral patterns of seed dispersers. Psittacanthus robustus (Loranthaceae) is a neotropical hemiparasite that mainly colonizes species of the family Vochysiaceae. Vochysia thyrsoidea is the main host of P. robustus and is commonly found in areas of cerrado rupestre (rocky savanna), an abundant vegetation in our study site. We conducted the study in the ecological park Parque Ecológico Quedas do Rio Bonito (PEQRB), over an area of 2.82 ha of cerrado rupestre. The objective of this work was to investigate population structure, parasitic behavior (mistletoe grip height and circumference of host branch), and spatial distribution of Psittacanthus robustus on a population of Vochysia thyrsoidea. We sampled 267 V. thyrsoidea individuals and found that the population had a random distribution pattern. Seventy-nine individuals (29.6% of the sample population) hosted the hemiparasite, to a total of 193 P. robustus individuals. The number of mistletoe individuals per host plant ranged between 1 and 12. The V. thyrsoidea individuals most infested with mistletoes were those reaching greater heights. The correlation between height of host plant and preferred grip height was highly significant, with the preferred grip height being the uppermost portions of host plants. The crown size of P. robustus individuals ranged between 10 and 230 cm. The main disperser of P. robustus fruit was found to be swallow-tanager Tersina viridis viridis. Its activities led to a clumped pattern of spatial distribution of the hemiparasite along with higher infestation in larger trees.     

Mitochondrial dysfunction is a trigger of Alzheimer's disease pathophysiology

Mitochondria are uniquely poised to play a pivotal role in neuronal cell survival or death because they are regulators of both energy metabolism and cell death pathways. Extensive literature exists supporting a role for mitochondrial dysfunction and oxidative damage in the pathogenesis of Alzheimer's disease. This review discusses evidence indicating that mitochondrial dysfunction has an early and preponderant role in Alzheimer's disease. Furthermore, the link between mitochondrial dysfunction and autophagy in Alzheimer's disease is also discussed. As a result of insufficient digestion of oxidatively damaged macromolecules and organelles by autophagy, neurons progressively accumulate lipofuscin that could exacerbate neuronal dysfunction. Since autophagy is the major pathway involved in the degradation of protein aggregates and defective organelles, an intense interest in developing autophagy-related therapies is growing among the scientific community. The final part of this review is devoted to discuss autophagy as a potential target of therapeutic interventions in Alzheimer's disease pathophysiology.     

Mitochondria: A therapeutic target in neurodegeneration

Mitochondrial dysfunction has long been associated with neurodegenerative disease. Therefore, mitochondrial protective agents represent a unique direction for the development of drug candidates that can modify the pathogenesis of neurodegeneration. This review discusses evidence showing that mitochondrial dysfunction has a central role in the pathogenesis of Alzheimer's, Parkinson's and Huntington's diseases and amyotrophic lateral sclerosis. We also debate the potential therapeutic efficacy of metabolic antioxidants, mitochondria-directed antioxidants and Szeto–Schiller (SS) peptides. Since these compounds preferentially target mitochondria, a major source of oxidative damage, they are promising therapeutic candidates for neurodegenerative diseases. Furthermore, we will briefly discuss the novel action of the antihistamine drug Dimebon on mitochondria.     

Studies toward the structural optimization of novel thiazolylhydrazone-based potent antitrypanosomal agents

In previous studies, we identified promising anti-Trypanosoma cruzi cruzain inhibitors based on thiazolylhydrazones. To optimize this series, a number of medicinal chemistry directions were explored and new thiazolylhydrazones and thiosemicarbazones were thus synthesized. Potent cruzain inhibitors were identified, such as thiazolylhydrazones 3b and 3j, which exhibited IC(50) of 200-400nM. Furthermore, molecular docking studies showed concordance with experimentally derived structure-activity relationships (SAR) data. In the course of this work, lead compounds exhibiting in vitro activity against both the epimastigote and trypomastigote forms of T. cruzi were identified and in vivo general toxicity analysis was subsequently performed. Novel SAR were documented, including the importance of the thiocarbonyl carbon attached to the thiazolyl ring and the direct comparison between thiosemicarbazones and thiazolylhydrazones.     

Structure–activity relationships of mononuclear metal–thiosemicarbazone complexes endowed with potent antiplasmodial and antiamoebic activities

A useful concept for the rational design of antiparasitic drug candidates is the complexation of bioactive ligands with transition metals. In view of this, an investigation was conducted into a new set of metal complexes as potential antiplasmodium and antiamoebic agents, in order to examine the importance of metallic atoms, as well as the kind of sphere of co-ordination, in these biological properties. Four functionalized furyl-thiosemicarbazones (NT1–4) treated with divalent metals (Cu, Co, Pt, and Pd) to form the mononuclear metallic complexes of formula [M(L)₂Cl₂] or [M(L)Cl₂] were examined. The pharmacological characterization, including assays against Plasmodium falciparum and Entamoeba histolytica, cytotoxicity to mammalian cells, and interaction with pBR 322 plasmid DNA was performed. Structure–activity relationship data revealed that the metallic complexation plays an essential role in antiprotozoal activity, rather than the simple presence of the ligand or metal alone. Important steps towards identification of novel antiplasmodium (NT1Cu, IC₅₀ of 4.6 μM) and antiamoebic (NT2Pd, IC₅₀ of 0.6 μM) drug prototypes were achieved. Of particular relevance to this work, these prototypes were able to reduce the proliferation of these parasites at concentrations that are not cytotoxic to mammalian cells.     

Nitric oxide inhibits neutrophil migration by a mechanism dependent on ICAM-1: role of soluble guanylate cyclase.

In the present study, we addressed the role of intercellular adhesion molecule type 1 (ICAM-1/CD54) in neutrophil migration to inflammatory site and whether the inhibitory effect of nitric oxide (NO) upon the neutrophil rolling, adhesion and migration involves down-modulation of ICAM-1 expression through a cyclic GMP (cGMP) dependent mechanism. It was observed that neutrophil migration induced by intraperitoneal administration of endotoxin (LPS), carrageenan (Cg) or N-formyl peptide (fMLP) in ICAM-1 deficient (ICAM-1-/-) is similar to that observed in wild type (WT) mice. The treatment of mice with NO synthase (NOS) inhibitors, NG-nitro-l-arginine, aminoguanidine or with a soluble guanylate cyclase (sGC) inhibitor, ODQ enhanced LPS- or Cg-induced neutrophil migration, rolling and adhesion on venular endothelium. These parameters induced by LPS were also enhanced by 1400 W, a specific iNOS inhibitor, treatment. On the other hand, the treatment of the mice with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, reduced these parameters induced by LPS or Cg by a mechanism sensitive to ODQ pretreatment. The NOS inhibitors did not enhance LPS-, Cg- or fMLP-induced migration and adhesion in ICAM-1-/- mice. Moreover, genetic (iNOS-/- mice) or pharmacological inhibition of NOS or of sGC enhanced LPS-induced ICAM-1 expression on mesenteric microcirculation vessels of WT mice. By contrast, SNAP reduced the ICAM-1 expression by a mechanism dependent on cGMP. In conclusion, the results suggest that although during inflammation, ICAM-1 does not contribute to neutrophil migration, it is necessary for the down-modulatory effect of inflammation-released NO on the adhesion and transmigration of neutrophils. Moreover, these NO effects are mediated via cGMP.