Aromatic Halogenation by Using Bifunctional Flavin Reductase–Halogenase Fusion Enzymes

The remarkable site selectivity and broad substrate scope of flavin-dependent halogenases (FDHs) has led to much interest in their potential as biocatalysts. Multiple engineering efforts have demonstrated that FDHs can be tuned for non-native substrate scope and site selectivity. FDHs have also proven useful as in vivo biocatalysts and have been successfully incorporated into biosynthetic pathways to build new chlorinated aromatic compounds in several heterologous organisms. In both cases, reduced flavin cofactor, usually supplied by a separate flavin reductase (FR), is required. Herein, we report functional synthetic, fused FDH-FR proteins containing various FDHs and FRs joined by different linkers. We show that FDH-FR fusion proteins can increase product titers compared to the individual components for in vivo biocatalysis in Escherichia coli.     

Categorically defined targets trigger spatiotemporal visual attention.

Transient attention to a visually salient cue enhances processing of a subsequent target in the same spatial location between 50 to 150 ms after cue onset (K. Nakayama & M. Mackeben, 1989). Do stimuli from a categorically defined target set, such as letters or digits, also generate transient attention? Participants reported digit targets among keyboard symbols in a changing array of 8 items. When 1 target preceded a second target in the same location at a stimulus onset asynchrony of 107 ms (but not 213 ms), the second target was reported more often than in a condition in which there was no leading target. When the 2 targets were at different locations, report of the second target was impaired. With both letters and digits as targets, the enhancement effect was shown not to be due to category priming. Critically, the attentional benefit was present whether or not participants reported the leading target. Transient attention, contingent attentional capture, popout, and Lag 1 sparing in the attentional blink may involve a common mechanism for orienting processing resources towards salient and task relevant stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

15‐Methylene‐Eburnamonine Kills Leukemic Stem Cells and Reduces Engraftment in a Humanized Bone Marrow Xenograft Mouse Model of Leukemia

Recent studies suggest that leukemia stem cells (LSCs) play a critical role in the initiation, propagation, and relapse of leukemia. Herein we show that (?)‐15‐methylene‐eburnamonine, a derivative of the alkaloid (?)‐eburnamonine, is cytotoxic against acute and chronic lymphocytic leukemias (ALL and CLL) and acute myelogenous leukemia (AML). The agent also decreases primary LSC frequency in vitro. The cytotoxic effects appear to be mediated via the oxidative stress pathways. Furthermore, we show that the compound kills AML, ALL, and CLL stem cells. By the use of a novel humanized bone marrow murine model of leukemia (huBM/NSG), it was found to decrease progenitor cell engraftment.     

Advances in the biological treatment of coal for synthetic natural gas and chemicals

Coal, the most primitive fossil fuel, has been exploited for ages, and reserves dictate the economies of many countries. Presently, most energy is generated by direct combustion, raising concerns over global warming. Biological pretreatment of fossil resources and generation of alternative green energy can address the environmental issues associated with global coal utilization. Biological coal treatment can produce industrially important chemicals and bio-methane by employing microorganisms able to depolymerize/degrade coal. This review discusses current advances in microbial coal conversion, such as the efforts made to comprehend microbial processes, significant outputs of coal conversion, principle components responsible for coal conversion, and factors affecting the biological processes to convert coal. Development of these biological processes can be a stepping stone for greener coal; however, integration of multidisciplinary technologies is needed to increase the efficiency of economic coal utilization and production of economically and industrially feasible biomethane.     

Melanocytes Affect Nodal Expression and Signaling in Melanoma Cells: A Lesson from Pediatric Large Congenital Melanocytic Nevi

Expression of Nodal, a Transforming Growth Factor-beta (TGF-β) related growth factor, is associated with aggressive melanoma. Nodal expression in adult dysplastic nevi may predict the development of aggressive melanoma in some patients. A subset of pediatric patients diagnosed with giant or large congenital melanocytic nevi (LCMN) has shown increased risk for development of melanoma. Here, we investigate whether Nodal expression can help identify the rare cases of LCMN that develop melanoma and shed light on why the majority of these patients do not. Immunohistochemistry (IHC) staining results show varying degree of Nodal expression in pediatric dysplastic nevi and LCMN. Moreover, median scores from Nodal IHC expression analysis were not significantly different between these two groups. Additionally, none of the LCMN patients in this study developed melanoma, regardless of Nodal IHC levels. Co-culture experiments revealed reduced tumor growth and lower levels of Nodal and its signaling molecules P-SMAD2 and P-ERK1/2 when melanoma cells were grown in vivo or in vitro with normal melanocytes. The same was observed in melanoma cells cultured with melanocyte conditioned media containing pigmented melanocyte derived melanosomes (MDM). Since MDM contain molecules capable of inactivating radical oxygen species, to investigate potential anti-oxidant effect of MDM on Nodal expression and signaling in melanoma, melanoma cells were treated with either N-acetyl-l-cysteine (NAC), a component of the anti-oxidant glutathione or synthetic melanin, which in addition to providing pigmentation can also exert free radical scavenging activity. Melanoma cells treated with NAC or synthetic melanin showed reduced levels of Nodal, P-SMAD2 and P-ERK1/2 compared to untreated melanoma cells. Thus, the potential role for Nodal in melanoma development in LCMN is less evident than in adult dysplastic nevi possibly due to melanocyte cross-talk in LCMN capable of offsetting or delaying the pro-melanoma effects of Nodal via anti-oxidant effects of MDM.     

The Effects of Isolation and Acid Mine Drainage on Fish and Macroinvertebrate Communities of Monday Creek, Ohio, USA

Isolated headwater streams in mined watersheds may have good water quality and fish habitat, yet be disconnected from immigration sources by stream segments impaired by acid mine drainage (AMD). Studies of fish and macroinvertebrate communities, habitat, and a number of hydrochemical parameters in Monday Creek, Ohio, show that AMD eliminates fish communities and severely limits macroinvertebrate communities in directly affected tributaries. Isolated headwaters in the heavily mined Monday Creek watershed have relatively good water quality and habitat, but poor fish communities. Comparison of isolated Monday Creek headwaters with non-isolated reaches in unmined watersheds indicates that differences in fish communities are attributable to isolation. Fish communities in isolated headwaters have lower Indices of Biotic Integrity (IBI) than comparable non-isolated communities, reduced species numbers, and lower numbers of individuals, despite suitable habitat as measured by the Qualitative Habitat Evaluation Index (QHEI). Comparison of macroinvertebrate communities shows higher Invertebrate Community Indices (ICI), and no apparent species loss, which can be attributed to the obligate flight stage in the life cycle of many macroinvertebrates, which enables them to overcome aquatic barriers. The implication of this research is that there is an opportunity for recovery of depleted fish communities in large AMD-isolated areas with good water quality, suitable habitat, and intact macroinvertebrate communities, by downstream treatment or source control of AMD to create aquatic corridors for fish immigration.     

Electrolytic Behaviour of Some Chlorothallate(III) Compounds in ethanol solution

Raman spectroscopic and conductivity studies show that pyridinium derivatives of the TlCl₅^2⊖, TlCl₆^3⊖ and Tl₂Cl₉^3⊖ species dissociate in ethanol solution to yield the TlCl₄^⊖ ion, but the [(C₂H₅)₄N]₂TlCl₅ salt does not dissociate further and behaves like a 2:1 electrolyte.