Implications of the genetic epidemiology of globin haplotypes linked to the sickle cell gene in southern Iran

To determine the origin of sickle cell mutation in different ethnic groups living in southern Iran, we studied the haplotype background of the betaS and betaA genes in subjects from the provinces of Fars, Khuzestan, Bushehr, Hormozgan, and Kerman and from the islands of Khark and Qeshm. beta-globin gene cluster haplotypes were determined using the PCR-RFLP technique. Detection of -alpha 3.7 deletion and beta-thalassemia mutations were defined by PCR and reverse dot blot techniques, respectively. The framework of the beta-globin gene was determined using denaturing gradient gel electrophoresis. We found that the betaS mutation in southern Iran is associated with multiple mutational events. Most of the patients were from two ethnic groups: Farsi speakers (presumably Persian in origin) from Fars province and patients of Arab origin from Khuzestan province. In both ethnic groups the Arab-Indian haplotype was the most prevalent. The frequencies of the Arab-Indian and African haplotypes in sickle cell anemia patients from the provinces of Fars and Khuzestan were similar. Among betaA chromosomes the Bantu A2 haplotype was the most prevalent. The decrease in alpha-globin production in SS patients and AS individuals appeared to be related to the reduction in mean cell volume and mean cell hemoglobin. The Arab-Indian haplotype gene flow into this region of Iran can be traced to the Sassanian Empire. It is likely that the influx of betaS genes linked to the Benin and Bantu haplotypes, of African origin, must have occurred during the Arab slave trade.     

MtDNA haplogroup analysis of black Brazilian and sub-Saharan populations: implications for the Atlantic slave trade

Seventy individuals from two African and four black Brazilian populations were studied for the first hypervariable segment of mtDNA. To delineate a more complete phylogeographic scenario of the African mtDNA haplogroups in Brazil and to provide additional information on the nature of the Atlantic slave trade, we analyzed our data together with previously published data. The results indicate different sources of African slaves for the four major Brazilian regions. In addition, the data revealed patterns that differ from those expected on the basis of historical registers, thus suggesting the role of ethnic sex differences in the slave trade.     

Oxidative damage to DNA constituents by iron-mediated Fenton reactions: the deoxyadenosine family

The effect of exposing 2'-deoxyadenosine (dA), 5'-dAMP, 3'-dAMP, dApA, dA(pdA)(19,) and poly(dA): oligo(dT) to iron/H(2)O(2) in the presence and absence of ethanol or NADH has been studied. HPLC retention times, enzyme treatments, radio-labeled substrates, UV absorption spectra, and fast atom bombardment mass spectrometry (FABMS) have been used to distinguish 20 products arising from the reaction, of which 16 have been identified and four anomers proposed by comparison with earlier gamma radiation studies. The radical responsible for the reactions seems to be analogous to radiation-derived [Formula: see text], has many products in common, but has some novel ones probably specific for Fenton-induced damage. Two new dimeric adducts arising from the generation of hydroxylamine at N7 and its subsequent condensation with two known sugar damage products, dR-adenine-N1-oxide, and two isomers of dR-FAPy arising from radical attacks at C4 and C5, may be considered novel in the present study. Unlike radiation-derived [Formula: see text], the radical under study is difficult to eliminate due to its generation in the proximity of the substrate molecules. It is proposed that the iron binds to the phosphate group and generates the radical in its vicinity. Strand breaks in dA(pdA)(11) resulting from the Fenton reaction are of two types, spontaneous and alkali-labile. Duplex DNA is less sensitive to attack by this radical, as its various degradation products are a subset of those obtained with monomer substrates and only dR-FAPy production is relatively enhanced for poly (dA): oligo (dT) as compared to those from other substrates.     

A comparative study of byssogenesis on zebra and quagga mussels: the effects of water temperature, salinity and light-dark cycle

The quagga mussel (Dreissena rostriformis bugensis) and zebra mussel (Dreissena polymorpha) are invasive freshwater bivalves in Europe and North America. The distribution range of both Dreissena species is still expanding and both species cause major biofouling and ecological effects, in particular when they invade new areas. In order to assess the effect of temperature, salinity and light on the initial byssogenesis of both species, 24 h re-attachment experiments in standing water were conducted. At a water temperature of 25°C and a salinity of 0.2 psu, the rate of byssogenesis of D. polymorpha was significantly higher than that of D. rostriformis bugensis. In addition, byssal thread production by the latter levelled out between 15°C and 25°C. The rate of byssogenesis at temperatures<25°C was similar for both species. Neither species produced any byssal threads at salinities of 4 psu or higher. At a salinity of 1 psu and a water temperature of 15°C, D. polymorpha produced significantly more byssal threads than D. rostriformis bugensis. There was no significant effect of the length of illumination on the byssogenesis of either species. Overall, D. polymorpha produced slightly more byssal threads than D. rostriformis bugensis at almost all experimental conditions in 24 h re-attachment experiments, but both species had essentially similar initial re-attachment abilities. The data imply that D. rostriformis bugensis causes biofouling problems identical to those of D. polymorpha.     

Solvent-induced tuning of internal structure in a protein amyloid protofibril

An important goal in studies of protein aggregation is to obtain an understanding of the structural diversity that is characteristic of amyloid fibril and protofibril structures at the molecular level. In this study, what to our knowledge are novel assays based on time-resolved fluorescence anisotropy decay and dynamic quenching measurements of a fluorophore placed at different specific locations in the primary structure of a small protein, barstar, have been used to determine the extent to which the protein sequence participates in the structural core of protofibrils. The fluorescence measurements reveal the structural basis of how modulating solvent polarity results in the tuning of the protofibril conformation from a pair of parallel β-sheets in heat-induced protofibrils to a single parallel β-sheet in trifluorethanol-induced protofibrils. In trifluorethanol-induced protofibrils, the single β-sheet is shown to be built up from in-register β-strands formed by nearly the entire protein sequence, while in heat-induced protofibrils, the pair of β-sheets motif is built up from β-strands formed by only the last two-third of the protein sequence.     

Role of active site rigidity in activity: MD simulation and fluorescence study on a lipase mutant

Relationship between stability and activity of enzymes is maintained by underlying conformational flexibility. In thermophilic enzymes, a decrease in flexibility causes low enzyme activity while in less stable proteins such as mesophiles and psychrophiles, an increase in flexibility is associated with enhanced enzyme activity. Recently, we identified a mutant of a lipase whose stability and activity were enhanced simultaneously. In this work, we probed the conformational dynamics of the mutant and the wild type lipase, particularly flexibility of their active site using molecular dynamic simulations and time-resolved fluorescence techniques. In contrast to the earlier observations, our data show that active site of the mutant is more rigid than wild type enzyme. Further investigation suggests that this lipase needs minimal reorganization/flexibility of active site residues during its catalytic cycle. Molecular dynamic simulations suggest that catalytically competent active site geometry of the mutant is relatively more preserved than wild type lipase, which might have led to its higher enzyme activity. Our study implies that widely accepted positive correlation between conformation flexibility and enzyme activity need not be stringent and draws attention to the possibility that high enzyme activity can still be accomplished in a rigid active site and stable protein structures. This finding has a significant implication towards better understanding of involvement of dynamic motions in enzyme catalysis and enzyme engineering through mutations in active site.     

Synthesis of novel heterobimetallic copper(I) hydrazone Schiff base complexes: a comparative study on the effect of heterocyclic hydrazides towards interaction with DNA/protein, free radical scavenging and cytotoxicity

Two new copper(I) hydrazone complexes have been synthesised from bivalent copper precursor [CuCl(2)(PPh(3))(2)] and ferrocene containing bidentate hydrazone ligands HL(1) (1) or HL(2) (2). Based on the elemental analyses and spectroscopic data, the complexes are best formulated as [CuL(1)(PPh(3))(2)] (3) and [CuL(2)(PPh(3))(2)] (4) of the monovalent copper ion. Solid state structures of ligand 2 and its corresponding complex 4 were also determined. The DNA/albumin interactions of all the synthesised compounds were investigated using absorption, emission and synchronous fluorescence studies. Further, antioxidant properties of all the compounds have also been checked against ABTS, O(2)(-) and OH radicals. Additionally, the in vitro cytotoxic activity of compounds 1-4 was assessed using tumour (HeLa, A431) and non-tumour (NIH 3T3) cell lines.     

The feruloyl esterase gene family of Fusarium graminearum is differentially regulated by aromatic compounds and hosts

Feruloyl esterases can liberate ferulic acid (FA) from plant cell wall polymers. They are expressed by plant pathogenic fungi and could play a role in pathogenicity, although this question has not been addressed yet. The fungus Fusarium graminearum is the principal causal agent of fusarium head blight (FHB) and gibberella ear rot (GER), major diseases of wheat, barley, and maize in all temperate regions of the world. The F. graminearum genome contains seven genes with strong homology to feruloyl esterase (FAE) sequences. Phylogenetic analysis showed that these included three type B, three type C, and one type D FAE genes. Expression profiling of the seven FAE genes showed complex regulation patterns unique to each gene. In F. graminearum-infected plant tissues, the FAE genes exhibited host-specific gene expression. On wheat, FAEB1 and FAED1 were strongly expressed while FAEB2, FAEB3, and FAEC1 were expressed at more modest levels. On maize, only FAEB3, FAEC1, and FAED1 were expressed and at low levels. When growing F. graminearum in liquid culture, only FAEB1 and FAEC1 were expressed. Both genes were induced by a small group of related aromatic compounds including FA, caffeic acid, and p-coumaric acid. FAEB1 was induced by xylose, while repressed by glucose and galactose. FAEC1 was constitutively expressed at low levels in the presence of those sugars. Expression of the other five FAE genes was not detected in the culture conditions used. To determine if FAE genes were important for pathogenicity of F. graminearum, mutant strains inactivated for faeB1?, faeD1? or both genes were constructed and tested on wheat plants. No statistically significant change in pathogenicity and no compensatory expression of the other FAE genes were observed in the fae gene mutants. Our results show that FAEB1 and FAED1 are not required for pathogenicity of F. graminearum on wheat.     

Studies on collagen-tannic acid-collagenase ternary system: Inhibition of collagenase against collagenolytic degradation of extracellular matrix component of collagen

We report the detailed studies on the inhibitory effect of tannic acid (TA) on Clostridium histolyticum collagenase (ChC) activity against degradation of extracellular matrix component of collagen. The TA treated collagen exhibited 64% resistance against collagenolytic hydrolysis by ChC, whereas direct interaction of TA with ChC exhibited 99% inhibition against degradation of collagen and the inhibition was found to be concentration dependant. The kinetic inhibition of ChC has been deduced from the extent of hydrolysis of N-[3-(2-furyl) acryloyl]-Leu-Gly-Pro-Ala (FALGPA). This data provides a selective competitive mode of inhibition on ChC activity seems to be influenced strongly by the nature and structure of TA. TA showed inhibitor activity against the ChC by molecular docking method. This result demonstrated that TA containing digalloyl radical possess the ability to inhibit the ChC. The inhibition of ChC in gaining new insight into the mechanism of stabilization of collagen by TA is discussed.