Binding of the Lactococcal Drug Dependent Transcriptional Regulator LmrR to Its Ligands and Responsive Promoter Regions

The heterodimeric ABC transporter LmrCD from Lactococcus lactis is able to extrude several different toxic compounds from the cell, fulfilling a role in the intrinsic and induced drug resistance. The expression of the lmrCD genes is regulated by the multi-drug binding repressor LmrR, which also binds to its own promoter to autoregulate its own expression. Previously, we reported the crystal structure of LmrR in the presence and absence of the drugs Hoechst 33342 and daunomycin. Analysis of the mechanism how drugs control the repressor activity of LmrR is impeded by the fact that these drugs also bind to DNA. Here we identified, using X-ray crystallography and fluorescence, that riboflavin binds into the drug binding cavity of LmrR, adopting a similar binding mode as Hoechst 33342 and daunomycin. Microscale thermophoresis was employed to quantify the binding affinity of LmrR to its responsive promoter regions and to evaluate the cognate site of LmrR in the lmrCD promoter region. Riboflavin reduces the binding affinity of LmrR for the promoter regions. Our results support a model wherein drug binding to LmrR relieves the LmrR dependent repression of the lmrCD genes.     

Fatty acid composition indicating diverse habitat use in coral reef fishes in the Malaysian South China Sea

Background

In order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea.

Results

Proportions of saturated fatty acids (SAFA) ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA) ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA) was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes’ life history in the coral reef habitats.

Conclusions

Diets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.     

Optoacoustic mesoscopy analysis and quantitative estimation of specific imaging metrics in Fitzpatrick skin phototypes II to V

Raster Scanning Optoacoustic Mesoscopy (RSOM) is a novel optoacoustic imaging modality that offers non‐invasive, label‐free, high resolution (~7 μm axial, ~30 μm lateral) imaging up to 1 to 2 mm below the skin, providing novel quantitative insights into skin pathophysiology. As the RSOM image contrast mechanism is based on light absorption, it is expected that the amount of melanin present in the skin will affect RSOM images. However, the effect of skin tone in the performance of RSOM has not been addressed so far. Herein, we present the efficiency of RSOM for in vivo skin imaging of human subjects with Fitzpatrick (FP) skin types between II to V. RSOM images acquired from the volar forearms of the subjects were used to derive metrics used in RSOM studies, such as total blood volume, vessel diameter and melanin signal intensity. Our study shows that the melanin signal intensity derived from the RSOM images exhibited an excellent correlation with that obtained from a clinical colorimeter for the subjects of varying FP skin types. We could successfully estimate the vessel diameter at different depths of the dermis. Furthermore, our study shows that there is a need to compensate for total blood volume calculated for subjects with higher FP skin types due to the lower signal‐to‐noise ratio in dermis, owing to strong absorption of light by melanin. This study sheds light into how RSOM can be used for studying various skin conditions in populations with different skin phenotypes.     

Rapid bioremediation of Alizarin Red S and Quinizarine Green SS dyes using <Emphasis Type="Italic">Trichoderma lixii</Emphasis> F21 mediated by biosorption and enzymatic processes

In this study, a newly isolated ascomycete fungus Trichoderma lixii F21 was explored to bioremediate the polar [Alizarin Red S (ARS)] and non-polar [Quinizarine Green SS (QGSS)] anthraquinone dyes. The bioremediation of ARS and QGSS by T. lixii F21 was found to be 77.78 and 98.31 %, respectively, via biosorption and enzymatic processes within 7 days of incubation. The maximum biosorption (ARS = 33.7 % and QGSS = 74.7 %) and enzymatic biodegradation (ARS = 44.1 % and QGSS = 23.6 %) were observed at pH 4 and 27 °C in the presence of glucose and yeast extract. The laccase and catechol 1,2-dioxygenase produced by T. lixii F21 were involved in the molecular conversions of ARS and QGSS to phenolic and carboxylic acid compounds, without the formation of toxic aromatic amines. This study suggests that T. lixii F21 may be a good candidate for the bioremediation of industrial effluents contaminated with anthraquinone dyes.     

Noninvasive Anatomical and Functional Imaging of Orthotopic Glioblastoma Development and Therapy using Multispectral Optoacoustic Tomography

PURPOSE: Here we demonstrate the potential of multispectral optoacoustic tomography (MSOT), a new non-invasive structural and functional imaging modality, to track the growth and changes in blood oxygen saturation (sO₂) in orthotopic glioblastoma (GBMs) and the surrounding brain tissues upon administration of a vascular disruptive agent (VDA). METHODS: Nude mice injected with U87MG tumor cells were longitudinally monitored for the development of orthotopic GBMs up to 15 days and observed for changes in sO₂ upon administration of combretastatin A4 phosphate (CA4P, 30 mg/kg), an FDA approved VDA for treating solid tumors. We employed a newly-developed non-negative constrained approach for combined MSOT image reconstruction and unmixing in order to quantitatively map sO₂ in whole mouse brains. RESULTS: Upon longitudinal monitoring, tumors could be detected in mouse brains using single-wavelength data as early as 6 days post tumor cell inoculation. Fifteen days post-inoculation, tumors had higher sO₂ of 63 ± 11% (n = 5, P < .05) against 48 ± 7% in the corresponding contralateral brain, indicating their hyperoxic status. In a different set of animals, 42 days post-inoculation, tumors had lower sO₂ of 42 ± 5% against 49 ± 4% (n = 3, P < .05) in the contralateral side, indicating their hypoxic status. Upon CA4P administration, sO₂ in 15 days post-inoculation tumors dropped from 61 ± 9% to 36 ± 1% (n = 4, P < .01) within one hour, then reverted to pre CA4P treatment values (63 ± 6%) and remained constant until the last observation time point of 6 hours. CONCLUSION: With the help of advanced post processing algorithms, MSOT was capable of monitoring the tumor growth and assessing hemodynamic changes upon administration of VDAs in orthotopic GBMs.     

Anadromy and heterogenous population of a tropical shad Tenualosa ilisha in Malaysia,as revealed by otolith microchemistry and molecular evidence

Tenualosa ilisha was found recently in the Perak River in western Peninsular Malaysia. Molecular phylogenetic and haplotype network analyses suggest that T. ilisha has two genetically distinct populations/groups: (i) Peninsular Malaysia (Malaysia population), and (ii) Peninsular Malaysia, Thailand, India and Bangladesh (Indian Ocean population). The results also suggest that the T ilisha population in Peninsular Malaysia is genetically heterogeneous with a typical anadromous migration pattern.     

A Fatal Case of <Emphasis Type="Italic">Candida auris</Emphasis> and <Emphasis Type="Italic">Candida tropicalis</Emphasis> Candidemia in Neutropenic Patient

We report a fatal case of Candida auris that was involved in mixed candidemia with Candida tropicalis, isolated from the blood of a neutropenic patient. Identification of both isolates was confirmed by amplification and sequencing of internal transcribed spacer and D1/D2 domain of large subunit in rRNA gene. Antifungal susceptibility test by E-test method revealed that C. auris was resistant to amphotericin B, anidulafungin, caspofungin, fluconazole, itraconazole and voriconazole. On the other hand, C. tropicalis was sensitive to all antifungal tested. The use of chromogenic agar as isolation media is vital in detecting mixed candidemia.