International Journal of Molecular Sciences

815 KiB

Open AccessReview

The Metal-Dependent Regulators FurA and FurB from Mycobacterium Tuberculosis

by Debora Lucarelli, Michael L. Vasil, Wolfram Meyer-Klaucke and Ehmke Pohl

Int. J. Mol. Sci. 2008, 9(8), 1548-1560; https://doi.org/10.3390/ijms9081548 - 28 Aug 2008

Cited by 25 | Viewed by 12622

The ferric uptake regulators (Fur) form a large family of bacterial metalactivated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis, the causative agent of tuberculosis, expresses two members of the Fur family, designated FurA and [...] Read more.

The ferric uptake regulators (Fur) form a large family of bacterial metalactivated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis, the causative agent of tuberculosis, expresses two members of the Fur family, designated FurA and FurB. Although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions. FurA appears to be a specialized iron-dependent regulator that controls the katG gene, which encodes for a catalase-peroxidase involved in the response of M. tuberculosis to oxidative stress. KatG is also the key mycobacterial enzyme responsible for the activation of the first-line tuberculosis drug Isoniazid. FurB in contrast requires Zn²⁺ rather than Fe²⁺, to bind to its target sequence in regulated genes, which include those involved in Zn²⁺-homeostasis. Recent biochemical, crystallographic and spectroscopic data have now shed light on the activation and metal discrimination mechanisms in this protein family. Full article

(This article belongs to the Section Biochemistry)

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607 KiB

Open AccessReview

Phosphorescent Organic Light-Emitting Devices: Working Principle and Iridium Based Emitter Materials

by Stefan Kappaun, Christian Slugovc and Emil J. W. List

Int. J. Mol. Sci. 2008, 9(8), 1527-1547; https://doi.org/10.3390/ijms9081527 - 26 Aug 2008

Cited by 170 | Viewed by 18989

Abstract

Even though organic light-emitting device (OLED) technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs), further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this [...] Read more.

Even though organic light-emitting device (OLED) technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs), further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this technology. Along these lines, the present work reviews the essentials of OLED technology putting special focus on the general working principle of single and multilayer OLEDs, fluorescent and phosphorescent emitter materials as well as transfer processes in host materials doped with phosphorescent dyes. Moreover, as a prototypical example of phosphorescent emitter materials, a brief discussion of homo- and heteroleptic iridium(III) complexes is enclosed concentrating on their synthesis, photophysical properties and approaches for realizing iridium based phosphorescent polymers. Full article

(This article belongs to the Special Issue Functional Materials- From Functional Hybrid Materials to Functional Polymers)

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219 KiB

Open AccessArticle

The Use of Isolated Human Lymphocytes in Mycotoxin Cytotoxicity Testing

by Pholo W. Maenetje, Neil De Villiers and Mike F. Dutton

Int. J. Mol. Sci. 2008, 9(8), 1515-1526; https://doi.org/10.3390/ijms9081515 - 25 Aug 2008

Cited by 17 | Viewed by 11695

Abstract

The cytotoxicity of selected mycotoxins against isolated human lymphocytes was investigated, as a means of detecting mycotoxins in extracts derived from cereal samples. The methodology was based on the ability of viable cells to reduce methyl tetrazolium bromide to a purple formazan dye [...] Read more.

The cytotoxicity of selected mycotoxins against isolated human lymphocytes was investigated, as a means of detecting mycotoxins in extracts derived from cereal samples. The methodology was based on the ability of viable cells to reduce methyl tetrazolium bromide to a purple formazan dye that could be quantitated by spectrophometric means and hence give a measure of the cytotoxicity of added substances. The results showed that there was good correlation with the occurrence of identified mycotoxins with only a minimum of false positives. For example, of the 13 samples of barley or barley derivatives that were positive for the mycotoxins, fumonisin B1 (FB1) deoxynivalenol (DON) and ochratoxin A (OTA), all gave positive cytotoxicity responses. Two samples negative for mycotoxins gave no cytotoxicity responses. There was little variation between the results for lymphocytes drawn from the same healthy volunteer on three different occasions. Furthermore, for two of the mycotoxins tested (FB1 and DON) it was possible to correlate general levels of mycotoxins present to the cytotoxic response of the lymphocytes but not for OTA, where it was concluded that interfering substances prevented direct correlation. It was concluded that this method was suited for general application as it could handle relatively high number of samples in a short period of time. Full article

(This article belongs to the Special Issue Mycotoxins: Mechanisms of Toxicological Activity - Treatment and Prevention)

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Open AccessArticle

TFIP11, CCNL1 and EWSR1 Protein-protein Interactions, and Their Nuclear Localization

by Sissada Tannukit, Xin Wen, HongJun Wang and Michael L. Paine

Int. J. Mol. Sci. 2008, 9(8), 1504-1514; https://doi.org/10.3390/ijms9081504 - 25 Aug 2008

Cited by 14 | Viewed by 9181

Abstract

Previous studies using the yeast two-hybrid assay (Y2H) have identified cyclin L1 (CCNL1) and Ewing sarcoma breakpoint region 1 protein (EWSR1) as being interacting partners of tuftelin-interacting protein 11 (TFIP11). All three proteins are functionally related to the spliceosome and involved in pre-mRNA [...] Read more.

Previous studies using the yeast two-hybrid assay (Y2H) have identified cyclin L1 (CCNL1) and Ewing sarcoma breakpoint region 1 protein (EWSR1) as being interacting partners of tuftelin-interacting protein 11 (TFIP11). All three proteins are functionally related to the spliceosome and involved in pre-mRNA splicing activities. The spliceosome is a dynamic ribonucleoprotein complex responsible for pre-mRNA splicing of intronic regions, and is composed of five small nuclear RNAs (snRNAs) and ~140 proteins. TFIP11 appears to play a role in spliceosome disassembly allowing for the release of the bound lariat-intron. The roles of CCNL1 and EWSR1 in the spliceosome are poorly understood. Using fluorescently-tagged proteins and confocal microscopy we show that TFIP11, CCNL1 and EWSR1 frequently co-localize to speckled nuclear domains. These data would suggest that all three proteins participate in a common cellular activity related to RNA splicing events. Full article

(This article belongs to the Section Biochemistry)

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174 KiB

Open AccessArticle

Aflatoxin B1 Degradation by Stenotrophomonas Maltophilia and Other Microbes Selected Using Coumarin Medium

by Shu Guan, Cheng Ji, Ting Zhou, Junxia Li, Qiugang Ma and Tiangui Niu

Int. J. Mol. Sci. 2008, 9(8), 1489-1503; https://doi.org/10.3390/ijms9081489 - 22 Aug 2008

Cited by 175 | Viewed by 16688

Abstract

Aflatoxin B1 (AFB1) is one of the most harmful mycotoxins in animal production and food industry. A safe, effective and environmentally sound detoxification method is needed for controlling this toxin. In this study, 65 samples were screened from various sources with vast microbial [...] Read more.

Aflatoxin B1 (AFB1) is one of the most harmful mycotoxins in animal production and food industry. A safe, effective and environmentally sound detoxification method is needed for controlling this toxin. In this study, 65 samples were screened from various sources with vast microbial populations using a newly developed medium containing coumarin as the sole carbon source. Twenty five single-colony bacterial isolates showing AFB1 reduction activity in a liquid culture medium were selected from the screen. Isolate 35-3, obtained from tapir feces and identified to be Stenotrophomonas maltophilia, reduced AFB1 by 82.5% after incubation in the liquid medium at 37 °C for 72 h. The culture supernatant of isolate 35-3 was able to degrade AFB1 effectively, whereas the viable cells and cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Activity was reduced to 60.8% and 63.5% at 20 °C and 30 °C, respectively, from 78.7% at 37 °C. The highest degradation rate was 84.8% at pH 8 and the lowest was only 14.3% at pH 4.0. Ions Mg²+ and Cu²⁺ were activators for AFB1 degradation, however，ion Zn²⁺ was a strong inhibitor. Treatments with proteinase K, proteinase K plus SDS and heating significantly reduced or eradicated the degradation activity of the culture supernatant. The results indicated that the degradation of AFB1 by S. maltophilia 35-3 was enzymatic and could have a great potential in industrial applications. Full article

(This article belongs to the Special Issue Mycotoxins: Mechanisms of Toxicological Activity - Treatment and Prevention)

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291 KiB

Open AccessArticle

Muscle Contraction and Force: the Importance of an Ancillary Network, Nutrient Supply and Waste Removal

by Dagmar A. Brüggemann, Jens Risbo, Stefan G. Pierzynowski and Adrian P. Harrison

Int. J. Mol. Sci. 2008, 9(8), 1472-1488; https://doi.org/10.3390/ijms9081472 - 20 Aug 2008

Cited by 3 | Viewed by 10036

Abstract

Muscle contraction studies often focus solely on myofibres and the proteins known to be involved in the processes of sarcomere shortening and cross-bridge cycling, but skeletal muscle also comprises a very elaborate ancillary network of capillaries, which not only play a vital role [...] Read more.

Muscle contraction studies often focus solely on myofibres and the proteins known to be involved in the processes of sarcomere shortening and cross-bridge cycling, but skeletal muscle also comprises a very elaborate ancillary network of capillaries, which not only play a vital role in terms of nutrient delivery and waste product removal, but are also tethered to surrounding fibres by collagen ”wires”. This paper therefore addresses aspects of the ancillary network of skeletal muscle at both a microscopic and functional level in order to better understand its role holistically as a considerable contributor to force transfer within muscular tissue. Full article

(This article belongs to the Special Issue Muscle Contraction Mechanism, Motor Proteins Function and Molecular Aspects of Water)

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263 KiB

Open AccessReview

RNA:DNA Ratio and Other Nucleic Acid Derived Indices in Marine Ecology

by Maria Alexandra Chícharo and Luis Chícharo

Int. J. Mol. Sci. 2008, 9(8), 1453-1471; https://doi.org/10.3390/ijms9081453 - 20 Aug 2008

Cited by 155 | Viewed by 15904

Abstract

Some of most used indicators in marine ecology are nucleic acid-derived indices. They can be divided by target levels in three groups: 1) at the organism level as ecophysiologic indicators, indicators such as RNA:DNA ratios, DNA:dry weight and RNA:protein, 2) at the population [...] Read more.

Some of most used indicators in marine ecology are nucleic acid-derived indices. They can be divided by target levels in three groups: 1) at the organism level as ecophysiologic indicators, indicators such as RNA:DNA ratios, DNA:dry weight and RNA:protein, 2) at the population level, indicators such as growth rate, starvation incidence or fisheries impact indicators, and 3) at the community level, indicators such as trophic interactions, exergy indices and prey identification. The nucleic acids derived indices, especially RNA:DNA ratio, have been applied with success as indicators of nutritional condition, well been and growth in marine organisms. They are also useful as indicators of natural or anthropogenic impacts in marine population and communities, such as upwelling or dredge fisheries, respectively. They can help in understanding important issues of marine ecology such as trophic interactions in marine environment, fish and invertebrate recruitment failure and biodiversity changes, without laborious work of counting, measuring and identification of small marine organisms. Besides the objective of integrate nucleic acid derived indices across levels of organization, the paper will also include a general characterization of most used nucleic acid derived indices in marine ecology and also advantages and limitations of them. We can conclude that using indicators, such RNA:DNA ratios and other nucleic acids derived indices concomitantly with organism and ecosystems measures of responses to climate change (distribution, abundance, activity, metabolic rate, survival) will allow for the development of more rigorous and realistic predictions of the effects of anthropogenic climate change on marine systems. Full article

(This article belongs to the Special Issue Nucleic Acid Derivatives in Emerging Technologies)

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155 KiB

Open AccessReview

Water and Muscle Contraction

by Enrico Grazi

Int. J. Mol. Sci. 2008, 9(8), 1435-1452; https://doi.org/10.3390/ijms9081435 - 18 Aug 2008

Cited by 6 | Viewed by 9489

Abstract

The interaction between water and the protein of the contractile machinery as well as the tendency of these proteins to form geometrically ordered structures provide a link between water and muscle contraction. Protein osmotic pressure is strictly related to the chemical potential of [...] Read more.

The interaction between water and the protein of the contractile machinery as well as the tendency of these proteins to form geometrically ordered structures provide a link between water and muscle contraction. Protein osmotic pressure is strictly related to the chemical potential of the contractile proteins, to the stiffness of muscle structures and to the viscosity of the sliding of the thin over the thick filaments. Muscle power output and the steady rate of contraction are linked by modulating a single parameter, a viscosity coefficient. Muscle operation is characterized by working strokes of much shorter length and much quicker than in the classical model. As a consequence the force delivered and the stiffness attained by attached cross-bridges is much larger than usually believed. Full article

(This article belongs to the Special Issue Muscle Contraction Mechanism, Motor Proteins Function and Molecular Aspects of Water)

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207 KiB

Open AccessArticle

Redox Behavior of Anticancer Chalcone on a Glassy Carbon Electrode and Evaluation of its Interaction Parameters with DNA

by Afzal Shah, Asad M. Khan, Rumana Qureshi, Farzana L. Ansari, Muhammad F. Nazar and Syed S. Shah

Int. J. Mol. Sci. 2008, 9(8), 1424-1434; https://doi.org/10.3390/ijms9081424 - 13 Aug 2008

Cited by 82 | Viewed by 11103

Abstract

The interaction of anticancer chalcone [AMC, 1-(4'-aminophenyl)-3-(4-N,Ndimethylphenyl)- 2-propen-1-one] with DNA has been explored using electrochemical, spectroscopic and viscometric techniques. A shift in peak potential and decrease in peak current were observed in cyclic voltammetry and hypochromism accompanied with bathochromic shift were noticed in [...] Read more.

The interaction of anticancer chalcone [AMC, 1-(4'-aminophenyl)-3-(4-N,Ndimethylphenyl)- 2-propen-1-one] with DNA has been explored using electrochemical, spectroscopic and viscometric techniques. A shift in peak potential and decrease in peak current were observed in cyclic voltammetry and hypochromism accompanied with bathochromic shift were noticed in UV-Vis absorption spectroscopy. These findings were taken as evidence for AMC –DNA intercalation. A binding constant (K) with a value of 6.15 × 10⁵ M^-1 was obtained from CV data, which was also confirmed by UV-Vis absorption titration. Moreover, the diffusion coefficient of the drug with and without DNA (D_b and D_u), heterogeneous electron transfer rate constant (k^_o) and electron affinity (A) were also calculated from electrochemical data. Full article

(This article belongs to the Section Biochemistry)

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349 KiB

Open AccessArticle

Measurement of Electrical Conductivity for a Biomass Fire

by Kgakgamatso Mphale and Mal Heron

Int. J. Mol. Sci. 2008, 9(8), 1416-1423; https://doi.org/10.3390/ijms9081416 - 13 Aug 2008

Cited by 19 | Viewed by 9390

Abstract

A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2- port vector network analyzer [...] Read more.

A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2- port vector network analyzer to determine electrical conductivity from S-parameters. Electrical conductivity for vegetation material flames is important for numerical prediction of flashover in high voltage power transmission faults research. Vegetation fires that burn under high voltage transmission lines reduce flashover voltage by increasing air electrical conductivity and temperature. Analyzer determined electrical conductivity ranged from 0.0058 - 0.0079 mho/m for a fire with a maximum temperature of 1240 K. Full article

(This article belongs to the Special Issue Biofuels R&D: Securing the Planet's Future Energy Needs)

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321 KiB

Open AccessArticle

Synthesis and Biological Evaluation of New Imidazolium and Piperazinium Salts of Pyropheophorbide-a for Photodynamic Cancer Therapy

by Gerelt-Ireedui Sengee, Narangerel Badraa and Young Key Shim

Int. J. Mol. Sci. 2008, 9(8), 1407-1415; https://doi.org/10.3390/ijms9081407 - 13 Aug 2008

Cited by 14 | Viewed by 8764

Abstract

We have designed imidazolium and piperazinium salts of pyropheophorbide-a in order to develop effective photosensitizers which have good solubility in polar and non polar media and to reveal the possible influences of the piperazine and imidazole moieties on the biological activities of pyropheophorbide-a. [...] Read more.

We have designed imidazolium and piperazinium salts of pyropheophorbide-a in order to develop effective photosensitizers which have good solubility in polar and non polar media and to reveal the possible influences of the piperazine and imidazole moieties on the biological activities of pyropheophorbide-a. The phototoxicity of those pyropheophorbide-a salts against A549 cells was studied in vitro and compared with that of pyropheophorbide-a. The result showed that complexing piperazine and imidazole into pyropheophorbide-a decreases its dark toxicity without greatly decreasing phototoxicity and, enhances its phototoxicity without greatly increasing dark toxicity, respectively. This work not only describes novel amphiphilic salt complexes of pyropheophobide-a which retain the biological activities of the parent compound pyropheophorbide-a and could be effective candidate for PDT, but also reveals the possibility of developing effective photosensitizers by complexing imidazole and piperazine into other hydrophobic photosensitizers. Full article

(This article belongs to the Special Issue Natural Compounds for Cancer Treatment and Prevention)

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167 KiB

Open AccessReview

Sunflower-based Feedstocks in Nonfood Applications: Perspectives from Olefin Metathesis

by Bassie B. Marvey

Int. J. Mol. Sci. 2008, 9(8), 1393-1406; https://doi.org/10.3390/ijms9081393 - 13 Aug 2008

Cited by 43 | Viewed by 11445

Abstract

Sunflower (Helianthus annuus L.) oil remains under-utilised albeit one of the major seed oils produced world-wide. Moreover, the high oleic sunflower varieties make the oil attractive for applications requiring high temperature processes and those targeting the C=C double bond functionality. Herein [...] Read more.

Sunflower (Helianthus annuus L.) oil remains under-utilised albeit one of the major seed oils produced world-wide. Moreover, the high oleic sunflower varieties make the oil attractive for applications requiring high temperature processes and those targeting the C=C double bond functionality. Herein an overview of the recent developments in olefin metathesis of sunflower-based feedstocks is presented. The improved performance of olefin metathesis catalysts leading to high turnover numbers, high selectivity and catalyst recyclability, opens new opportunities for tailoring sunflower-based feedstocks into products required for possible new niche market applications. Promising results in biofuel, biopolymers, fragrances and fine chemicals applications have been reported. Full article

(This article belongs to the Section Green Chemistry)

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625 KiB

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Enhanced Inhibitory Effect of Ultra-Fine Granules of Red Ginseng on LPS-induced Cytokine Expression in the Monocyte-Derived Macrophage THP-1 Cells

by Hyoung-Cheol Lee, Radhakrishnan Vinodhkumar, Jang W. Yoon, Seong-Kyu Park, Chang-Won Lee and Hong-Yeoul Kim

Int. J. Mol. Sci. 2008, 9(8), 1379-1392; https://doi.org/10.3390/ijms9081379 - 7 Aug 2008

Cited by 19 | Viewed by 11835

Abstract

Red ginseng is one of the most popular traditional medicines in Korea because its soluble hot-water extract is known to be very effective on enhancing immunity as well as inhibiting inflammation. Recently, we developed a new technique, called the HACgearshift system, which can [...] Read more.

Red ginseng is one of the most popular traditional medicines in Korea because its soluble hot-water extract is known to be very effective on enhancing immunity as well as inhibiting inflammation. Recently, we developed a new technique, called the HACgearshift system, which can pulverize red ginseng into the ultra-fine granules ranging from 0.2 to 7.0 μm in size. In this study, the soluble hot-water extract of those ultra-fine granules of red ginseng (URG) was investigated and compared to that of the normal-sized granules of red ginseng (RG). The high pressure liquid chromatographic analyses of the soluble hot-water extracts of both URG and RG revealed that URG had about 2-fold higher amounts of the ginsenosides, the biologically active components in red ginseng, than RG did. Using quantitative RT-PCR, cytokine profiling against the Escherichia coli lipopolysaccharide (LPS) in the monocyte-derived macrophage THP-1 cells demonstrated that the URG-treated cells showed a significant reduction in cytokine expression than the RG-treated ones. Transcription expression of the LPS-induced cytokines such as TNF-α, IL-1β, IL-6, IL-8, IL-10, and TGF-β was significantly inhibited by URG compared to RG. These results suggest that some biologically active and soluble components in red ginseng can be more effectively extracted from URG than RG by standard hot-water extraction. Full article

(This article belongs to the Section Biochemistry)

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365 KiB

Open AccessArticle

Energy Product Options for Eucalyptus Species Grown as Short Rotation Woody Crops

by Donald L. Rockwood, Alan W. Rudie, Sally A. Ralph, J. Y. Zhu and Jerrold E. Winandy

Int. J. Mol. Sci. 2008, 9(8), 1361-1378; https://doi.org/10.3390/ijms9081361 - 30 Jul 2008

Cited by 135 | Viewed by 12446

Abstract

Eucalyptus species are native to Australia but grown extensively worldwide as short rotation hardwoods for a variety of products and as ornamentals. We describe their general importance with specific emphasis on existing and emerging markets as energy products and the potential to maximize [...] Read more.

Eucalyptus species are native to Australia but grown extensively worldwide as short rotation hardwoods for a variety of products and as ornamentals. We describe their general importance with specific emphasis on existing and emerging markets as energy products and the potential to maximize their productivity as short rotation woody crops. Using experience in Florida USA and similar locations, we document their current energy applications and assess their productivity as short-term and likely long-term energy and related products. Full article

(This article belongs to the Special Issue Biofuels R&D: Securing the Planet's Future Energy Needs)

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Int. J. Mol. Sci., Volume 9, Issue 8 (August 2008) – 14 articles , Pages 1361-1560

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