A comparison investigation of DNP-binding effects to HSA and HTF by spectroscopic and molecular modeling techniques

This paper describes the interaction between 2,4-dinitrophenol (DNP) with the two drug carrier proteins – human serum albumin (HSA) and human holo transferrin (HTF). Hence, binding characteristics of DNP to HSA and HTF were analyzed by spectroscopic and molecular modeling techniques. Based on results obtained from fluorescence spectroscopy, DNP had a strong ability to quench the intrinsic fluorescence of HSA and HTF through a static quenching procedure. The binding constant and the number of binding sites were calculated as 2.3?×?10¹¹?M^?1 and .98 for HSA, and 1.7?×?10¹¹?M^?1 and 1.06 for HTF, respectively. In addition, synchronous fluorescence results showed that the microenvironment of Trp had a slight tendency of increasing its hydrophobicity, whereas the microenvironment of the Tyr residues of HSA did not change and that of HTF showed a significant trend (red shift of about 4?nm) of an increase in polarity. The distance between donor and acceptor was obtained by the Förster energy according to fluorescence resonance energy transfer, and was found to be 3.99 and 3.72?nm for HSA and HTF, respectively. The critical induced aggregation concentration (C_CIAC) of the drug on both proteins was determined and confirmed by an inflection point of the zeta potential behavior. Circular dichroism data revealed that the presence of DNP caused a decrease of the α-helical content of HSA and HTF, and induced a remarkable mild denaturation of both proteins. The molecular modeling data confirmed our experimental results. This study is deemed useful for determining drug dosage.     

Maintenance of cellular ATP level by caloric restriction correlates chronological survival of budding yeast

The free radical theory of aging emphasizes cumulative oxidative damage in the genome and intracellular proteins due to reactive oxygen species (ROS), which is a major cause for aging. Caloric restriction (CR) has been known as a representative treatment that prevents aging; however, its mechanism of action remains elusive. Here, we show that CR extends the chronological lifespan (CLS) of budding yeast by maintaining cellular energy levels. CR reduced the generation of total ROS and mitochondrial superoxide; however, CR did not reduce the oxidative damage in proteins and DNA. Subsequently, calorie-restricted yeast had higher mitochondrial membrane potential (MMP), and it sustained consistent ATP levels during the process of chronological aging. Our results suggest that CR extends the survival of the chronologically aged cells by improving the efficiency of energy metabolism for the maintenance of the ATP level rather than reducing the global oxidative damage of proteins and DNA.     

Chronological and replicative lifespan in yeast

Comment on: Murakami C, et al. Cell Cycle 2012; 11:3087-96.     

Isolation and characterization of lipids strictly associated to PSII complexes: Focus on cardiolipin structural and functional role

In this work, lipid extracts from spinach membrane fragments enriched in Photosystem II (PSII) and from spinach PSII dimers were analyzed, by means of Thin Layer Chromatography (TLC) and Electro-Spray Ionization Mass Spectrometry. Cardiolipin found in association with PSII was isolated and purified by preparative TLC, then characterized by mass and mass-mass analyses. Cardiolipin structures with four unsaturated C18 acyl chains and variable saturation degrees were evidenced. Structural and functional effects of different phospholipids on PSII complexes were investigated by Fluorescence, Resonance Light Scattering and Oxygen Evolution Rate measurements. An increment of PSII thermal stability was observed in the presence of cardiolipin and phosphatidylglycerol.     

Serum albumin biosynthesis and secretion by resting and lectin stimulated human lymphocytes

Normal human peripheral lymphocytes, cultured in serum-deprived medium, synthetized and released serum albumin and some glycoproteins into the culture supernatant. With the use of [3H]leucine, it was shown that this biosynthetic activity was increased about 2-3 times when the mitogenic lectin from Robinia pseudo acacia was added to the lymphocyte culture medium.     

RLS3, a protein with AAA+ domain localized in chloroplast,sustains leaf longevity in rice

Leaf senescence plays an important role in crop developmental processes that dramatically affect crop yield and grain quality. The genetic regulation of leaf senescence is complex, involving many metabolic and signaling pathways.Here, we identified a rapid leaf senescence 3(rls3) mutant that displayed accelerated leaf senescence, shorter plant height and panicle length, and lower seed set rate than the wild type. Map-based cloning revealed that RLS3 encodes a protein with AAA+ domain, localizing it to chloroplasts. Sequence analysis found that the rls3 gene had a single-nucleotide substitution(G→A) at the splice site of the 10~(th)intron/11~(th) exon, resulting in the cleavage of the first nucleotide in 11 ~(th) exon and premature termination of RLS3 protein translation.Using transmission electron microscope, the chloroplasts of the rls3 mutant were observed to degrade much faster than those of the wild type. The investigation of the leaf senescence process under dark incubation conditions furtherrevealed that the rls3 mutant displayed rapid leaf senescence.Thus, the RLS3 gene plays key roles in sustaining the normal growth of rice, while loss of function in RLS3 leads to rapid leaf senescence. The identification of RLS3 will be helpful to elucidate the mechanisms involved in leaf senescence in rice.     

3-D modelling of chloroplast structure under (Mg) magnesium ion treatment. Relationship between thylakoid membrane arrangement and stacking

We performed for the first time three-dimensional (3D) modelling of the entire chloroplast structure. Stacks of optical slices obtained by confocal laser scanning microscope (CLSM) provided a basis for construction of 3D images of individual chloroplasts. We selected pea (Pisum sativum) and bean (Phaseolus vulgaris) chloroplasts since we found that they differ in thylakoid organization. Pea chloroplasts contain large distinctly separated appressed domains while less distinguished appressed regions are present in bean chloroplasts. Different magnesium ion treatments were used to study thylakoid membrane stacking and arrangement. In pea chloroplasts, as demonstrated by 3D modelling, the increase of magnesium ion concentration changed the degree of membrane appression from wrinkled continuous surface to many distinguished stacked areas and significant increase of the inter-grana area. On the other hand 3D models of bean chloroplasts exhibited similar but less pronounced tendencies towards formation of appressed regions. Additionally, we studied arrangements of thylakoid membranes and chlorophyll-protein complexes by various spectroscopic methods, Fourier-transform infrared spectroscopy (FTIR) among others. Based on microscopic and spectroscopic data we suggested that the range of chloroplast structure alterations under magnesium ions treatment is a consequence of the arrangement of supercomplexes. Moreover, we showed that stacking processes always affect the structural changes of chloroplast as a whole.     

Segmentation of left ventricle in short-axis echocardiographic sequences by weighted radial edge filtering and adaptive recovery of dropout regions

In this paper, we present a weighted radial edge filtering algorithm with adaptive recovery of dropout regions for the semi-automatic delineation of endocardial contours in short-axis echocardiographic image sequences. The proposed algorithm requires minimal user intervention at the end diastolic frame of the image sequence for specifying the candidate points of the contour. The region of interest is identified by fitting an ellipse in the region defined by the specified points. Subsequently, the ellipse centre is used for originating the radial lines for filtering. A weighted radial edge filter is employed for the detection of edge points. The outliers are corrected by global as well as local statistics. Dropout regions are recovered by incorporating the important temporal information from the previous frame by means of recursive least squares adaptive filter. This ensures fairly accurate segmentation of the cardiac structures for further determination of the functional cardiac parameters. The proposed algorithm was applied to 10 data-sets over a full cardiac cycle and the results were validated by comparing computer-generated boundaries to those manually outlined by two experts using Hausdorff distance (HD) measure, radial mean square error (rmse) and contour similarity index. The rmse was 1.83 mm with a HD of 5.12 ± 1.21 mm. We have also compared our results with two existing approaches, level set and optical flow. The results indicate an improvement when compared with ground truth due to incorporation of temporal clues. The weighted radial edge filtering algorithm in conjunction with adaptive dropout recovery offers semi-automatic segmentation of heart chambers in 2D echocardiography sequences for accurate assessment of global left ventricular function to guide therapy and staging of the cardiovascular diseases.     

Systems genetics analysis of iron regulation in the brain

Iron imbalances in the brain, including excess accumulation and deficiency, are associated with neurological disease and dysfunction; yet, their origins are poorly understood. Using systems genetics analysis, we have learned that large individual differences exist in brain iron concentrations, even in the absence of neurological disease. Much of the individual differences can be tied to the genetic makeup of the individual. This genetic-based differential regulation can be modeled in genetic reference populations of rodents. The work in our laboratory centers on iron regulation in the brain and our animal model consists of 25 BXD/Ty recombinant inbred mouse strains. By studying naturally occurring variation in iron phenotypes, such as tissue iron concentration, we can tie that variability to one or more genes by way of quantitative trait loci (QTL) analysis. Moreover, we can conduct genetic correlation analyses between our phenotypes and others previously measured in the BXD/Ty strains. We have observed several suggestive QTL related to ventral midbrain iron content, including one on chromosome 17 that contains btbd9, a gene that in humans has been associated with restless legs syndrome and serum ferritin. We have also observed gene expression correlations with ventral midbrain iron, including btbd9 expression and dopamine receptor expression. In addition, we have observed significant correlations between ventral midbrain iron content and dopamine-related phenotypes. The following is a discussion of iron regulation in the brain and the contributions a systems genetics approach can make toward understanding the genetic underpinnings and relation to neurological disease.     

Comparative proteomic analysis of seedling leaves of different salt tolerant soybean genotypes

Salinity is one of the major environmental constraints limiting yield of crop plants in many semi-arid and arid regions around the world. To understand responses in soybean seedling to salt stress at proteomic level, the extracted proteins from seedling leaves of salt-sensitive genotype Jackson and salt-tolerant genotype Lee 68 under 150 mM NaCl stress for 1, 12, 72 and 144 h, respectively, were analyzed by 2-DE. Approximately 800 protein spots were detected on 2-DE gels. Among them, 91 were found to be differently expressed, with 78 being successfully identified by MALDI-TOF-TOF. The identified proteins were involved in 14 metabolic pathways and cellular processes. Based on most of the 78 salt-responsive proteins, a salt stress-responsive protein network was proposed. This network consisted of several functional components, including balancing between ROS production and scavenging, accelerated proteolysis and reduced biosynthesis of proteins, impaired photosynthesis, abundant energy supply and enhanced biosynthesis of ethylene. Salt-tolerant genotype Lee 68 possessed the ability of higher ROS scavenging, more abundant energy supply and ethylene production, and stronger photosynthesis than salt-sensitive genotype Jackson under salt stress, which may be the major reasons why it is more salt-tolerant than Jackson.