Acoustic detection and satellite-tracking leads to discovery of rare concentration of endangered North Pacific right whales

The North Pacific right whale, Eubalaena japonica, is one of the most endangered species of whale in the world. On 10 August 2004, two right whales were located in the Bering Sea using headings to right whale calls provided by directional sonobuoys. A satellite-monitored radio tag attached to one of these whales functioned for 40 days. Over the 40-day period, this whale moved throughout a large part of the southeast Bering Sea shelf, including areas of the outer-shelf where right whales have not been seen in decades. In September, multiple right whales were acoustically located and subsequently sighted by another survey vessel approaching a near-real-time position from the tag. An analysis of photographs confirmed at least 17 individual whales (not including the tagged whales). Genetic analysis of biopsy samples identified 17 individuals: 10 males and 7 females. The discovery of seven females was significant, as only one female had been identified in the past. Genetics also confirmed the presence of at least two calves. Although the future of this population is highly uncertain, the discovery of additional females and calves gives some hope that this most critically endangered of all whale populations may still possess the capacity to recover.     

Structural basis for ubiquitin recognition and autoubiquitination by Rabex-5

Rabex-5 is an exchange factor for Rab5, a master regulator of endosomal trafficking. Rabex-5 binds monoubiquitin, undergoes covalent ubiquitination and contains an intrinsic ubiquitin ligase activity, all of which require an N-terminal A20 zinc finger followed immediately by a helix. The structure of the N-terminal portion of Rabex-5 bound to ubiquitin at 2.5-A resolution shows that Rabex-5-ubiquitin interactions occur at two sites. The first site is a new type of ubiquitin-binding domain, an inverted ubiquitin-interacting motif, which binds with approximately 29-microM affinity to the canonical Ile44 hydrophobic patch on ubiquitin. The second is a diaromatic patch on the A20 zinc finger, which binds with approximately 22-microM affinity to a polar region centered on Asp58 of ubiquitin. The A20 zinc-finger diaromatic patch mediates ubiquitin-ligase activity by directly recruiting a ubiquitin-loaded ubiquitin-conjugating enzyme.     

Co‐encapsulation of anti‐BCR‐ABL siRNA and imatinib mesylate in transferrin receptor‐targeted sterically stabilized liposomes for chronic myeloid leukemia treatment

Chronic myeloid leukemia (CML) is triggered by the BCR‐ABL oncogene. Imatinib is the first‐line treatment of CML; however imatinib resistance and intolerance have been detected in many patients. Therefore, new therapeutic approaches are required. The present work aimed at the development and application of transferrin receptor (TrfR) targeted liposomes co‐encapsulating anti‐BCR‐ABL siRNA and imatinib at different molar ratios. The encapsulation yields and drug loading of each molecule was evaluated. Anti‐leukemia activity of the developed formulations co‐encapsulating siRNA and imatinib and of the combination of Trf‐liposomes carrying siRNA and free imatinib under two different treatment schedules of pre‐sensitization was assessed. The results obtained demonstrate that the presence of imatinib significantly decreases the encapsulation yields of siRNA, whereas imatinib encapsulation yields are increased by the presence of siRNA. Cytotoxicity assays demonstrate that the formulations co‐encapsulating siRNA and imatinib promote a 3.84‐fold reduction on the imatinib IC₅₀ (from 3.49 to 0.91 µM), whereas a 8.71‐fold reduction was observed for the pre‐sensitization protocols (from 42.7 to 4.9 nM). It was also observed that the formulations with higher siRNA to imatinib molar ratios promote higher cell toxicity. Thus, the present work describes a novel triple targeting strategy with one single system: cellular targeting (through the targeting ligand, transferrin) and molecular targeting at the BCR‐ABL mRNA and Bcr‐Abl protein level. Biotechnol. Bioeng. 2010;107: 884–893. © 2010 Wiley Periodicals, Inc.     

Senkyunolides reduce hydrogen peroxide-induced oxidative damage in human liver HepG2 cells via induction of heme oxygenase-1

Rhizoma Chuanxiong is widely used as folk medicine to treat the diseases caused by oxidative stress and inflammation. To delineate the underlying molecular mechanisms, we recently found that Rhizoma Chuanxiong extract significantly induced heme oxygenase-1 (HO-1), an enzyme that degrades intracellular heme into three bioactive products: biliverdin, carbon monoxide and free iron. The anti-inflammatory, antiapoptotic and antiproliferative actions of these products highlight HO-1 as a key endogenous antioxidant and cytoprotective gene. This study was designed to further characterize HO-1 induction of Rhizoma Chuanxiong through bioactivity-guided fractionation. All isolated fractions were assayed for HO-1 induction in human HepG2 cell line at mRNA and protein levels. Based on chromatographic profiling, nuclear magnetic resonance (NMR) and mass spectrometric analysis, the active compounds were identified as senkyunolide-H and its stereoisomer senkyunolide-I. Both senkyunolide isomers inhibited the formation of reactive oxygen species and lipid peroxidation and enhanced the cellular resistance to hydrogen peroxide-induced oxidative damage. Notably, heme oxygenase inhibitor tin protoporphyrin IX (SnPP) significantly suppressed the antioxidant activity of senkyunolide stereoisomers. Thus, this study demonstrated that senkyunolide-H and -I attenuated oxidative damage via activation of HO-1 pathway.     

Serine Residues in the Cytosolic Tail of the T-cell Antigen Receptor α-Chain Mediate Ubiquitination and Endoplasmic Reticulum-associated Degradation of the Unassembled Protein

The T-cell antigen receptor (TCR) α-chain (TCRα) is a type I integral membrane protein that becomes ubiquitinated and targeted to the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway when it fails to assemble into the heteromeric TCR complex. Remarkably, TCRα has a cytosolic tail of only five amino acid residues (i.e. RLWSS), none of which is the conventional ubiquitin acceptor, lysine. Herein we report that substitution of two conserved serine residues in the cytosolic tail of TCRα to alanine decreased ubiquitination, whereas placement of additional serine residues enhanced it. Moreover, replacement of the cytosolic serine residues by other ubiquitinatable residues (i.e. cysteine, threonine, or lysine) allowed ubiquitination to take place. Serine-dependent ubiquitination perfectly correlated with targeting of TCRα for ERAD. We also found that this ubiquitination was mediated by the ER-localized ubiquitin ligase, HRD1. These findings indicate that serine-dependent, HRD1-mediated ubiquitination targets TCRα to the ERAD pathway.     

Comparative antibacterial potential of selected aldehyde-based biocides and surfactants against planktonic Pseudomonas fluorescens

The antimicrobial efficacy of two aldehyde-based biocides (glutaraldehyde, GTA, and ortho-phthalaldehyde, OPA) and two surfactants (cetyltrimethyl ammonium bromide, CTAB, and sodium dodecyl sulphate, SDS) was tested against planktonic Pseudomonas fluorescens. The antimicrobial effects were evaluated by respiratory activity as a measure of the oxygen uptake rate, adenosine triphosphate (ATP) release, outer membrane proteins (OMP) expression and cellular colour changes. The results were compared with the bacterial characteristics without chemical treatment. Tests in the presence of bovine serum albumin (BSA), in order to mimic a disinfection process in the real situation under dirty conditions, were performed according to the European Standard EN-1276. P. fluorescens was completely inactivated with OPA (minimum bactericidal concentration, MBC = 0.5 mM) and CTAB (MBC = 5 mM) and was resistant to GTA and SDS. Only CTAB promoted cellular disruption and consequent ATP release. The antimicrobial action of the chemicals tested was significantly reduced when BSA was introduced into the bacterial cultures, increasing markedly the MBC values. Additionally, the presence of BSA acted as a disruption protective agent when CTAB was applied and stimulated the bacterial respiratory activity when lower concentrations of SDS were tested. The OMP of the bacterial cells was affected by the application of both surfactants. OMP expression remained unaltered after biocide treatment. Bacterial colour change was noticed after treatment with biocides and surfactants. In summary, P. fluorescens was extremely resistant to GTA and SDS, with antimicrobial action being quenched markedly by the reaction with BSA.     

Optimization of MALDI-TOF MS for strain level differentiation of Arthrobacter isolates

Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be a rapid and sensitive method for characterization of bacteria, but it has not yet become a routine microbiological procedure. Currently there are no standardized protocols that would allow development of large libraries of reproducible protein profiles from a broad range of microorganisms to use for identification purposes. Important variables that may affect spectrum quality are MALDI matrices, solvents, cell growth condition, and culture age. In the present study our aim was to: (1) to determine optimal sample preparation and MALDI conditions for discrimination at the strain level; (2) to determine if changes in growth cycle correlated with MALDI spectrum changes; and (3) to compare level of isolate discrimination based on their MALDI spectra versus their 16S rRNA gene sequence. Using 16 strains of the Gram positive bacterium Arthrobacter, optimal spectra were obtained using two-layer sample application of intact cells grown on solid surface overlaid with a matrix consisting of sinapinic acid (SA) or alpha-cyano-hydroxy-cinnaminic acid (CHCA) in 50:50 acetonitrile:water solvent with 2% trifluoroacetic acid. Spectrum changes paralleled the coccus-rod-coccus growth cycle indicative of Arthrobacter. Strain differences based on their MALDI profiles (using Pearson coefficient and UPGMA) corresponded with their 16S rRNA gene phylogeny but it had greater discrimination.