Structural analysis of Tris binding in β-glucosidases

β-glucosidases (Bgls) are glycosyl hydrolases that catalyze the conversion of cellobiose or glucosyl-polysaccharide into glucose. Bgls are widely used in industry to produce bioethanol, wine and juice, and feed. Tris (tris(hydroxymethyl)aminomethane) is an organic compound that can inhibit the hydrolase activity of some Bgls, but the inhibition state and selectivity have not been fully elucidated. Here, three crystal structures of Thermoanaerobacterium saccharolyticum Bgl complexed with the Tris molecule were determined at 1.55-1.95 Å. The configuration of Tris binding to TsaBgl remained consistent across three crystal structures, and the amino acids interacting with the Tris molecule were conserved across Bgl enzymes. The positions O1 and O3 atoms of Tris exhibit the same binding moiety as the hydroxyl group of the glucose molecule. Tris molecules are stably positioned at the glycone site and coordinate with surrounding water molecules. The Tris-binding configuration of TsaBgl is similar to that of HjeBgl, HgaBgl, ManBgl, and KflBgl, but the arrangement of the water molecule coordinating Tris at the aglycone site differs. Meanwhile, both the arrangement of Tris and the water molecules in ubBgl, NkoBgl, and SfrBgl differ from those in TsaBgl. The binding configuration and affinity of the Tris molecule for Bgl may be affected by the residues on the aglycone and gatekeeper regions. This result will extend our knowledge of the inhibitory effect of Tris molecules on TsaBgl.

Heat-induced antigen retrieval utilizing modified Tris-EDTA buffer for reprobing of Western blots on nitrocellulose paper

The development of heat-induced antigen retrieval technologies with Tris-EDTA buffer has dramatically improved immunostaining of specific antigens for routine immunohistochemical detection (Krenacs et al., 2010) [1]. However, little evidence exists on whether heat-Induced antigen retrieval utilizing Tris-EDTA buffer can strip western blot (WB) membranes and allow sequential reprobing. Here, we serendipitously discover that ∼95 °C Tris-EDTA buffer with 0.01% Tween 20 could repeatedly strip the Nitrocellulose membranes (NC). After electroblotting, NC blots were soaked into Tris-EDTA stripping buffer (∼95 °C, 10-25min) and we could perform at least five rounds (the following antibodies used: Vinculin, Atg7, Caspase-3, UBA5, JNK and ERK1/2) stripping in sequential chemiluminescent detections. The NC membranes also show clear western signals and background without losing transferred proteins during the reprobing process of WB. Hence, this study report additional new roles of the heat-Induced antigen retrieval Tris-EDTA buffer with 0.01% Tween 20. The method is simpler, more affordable and harmless for the nitrocellulose paper, which will be helpful for effective reprobing in western blotting applications.

Is the Novel Slot Blot a Useful Method for Quantification of Intracellular Advanced Glycation End-Products?

Various types of advanced glycation end-products (AGEs) have been identified and studied. I have reported a novel slot blot analysis to quantify two types of AGEs, glyceraldehyde-derived AGEs, also called toxic AGEs (TAGE), and 1,5-anhydro-D-fructose AGEs. The traditional slot blot method has been used for the detection and quantification of RNA, DNA, and proteins since around 1980 and is one of the more commonly used analog technologies to date. However, the novel slot blot analysis has been used to quantify AGEs from 2017 to 2022. Its characteristics include (i) use of a lysis buffer containing tris-(hydroxymethyl)-aminomethane, urea, thiourea, and 3-[3-(cholamidopropyl)-dimetyl-ammonio]-1-propane sulfonate (a lysis buffer with a composition similar to that used in two-dimensional gel electrophoresis-based proteomics analysis); (ii) probing of AGE-modified bovine serum albumin (e.g., standard AGE aliquots); and (iii) use of polyvinylidene difluoride membranes. In this review, the previously used quantification methods of slot blot, western blot, immunostaining, enzyme-linked immunosorbent assay, gas chromatography-mass spectrometry (MS), matrix-associated laser desorption/ionization-MS, and liquid chromatography-electrospray ionization-MS are described. Lastly, the advantages and disadvantages of the novel slot blot compared to the above methods are discussed.

Application of a novel poly(SMAm)-Tris-Fe3O4 nanocomposite for selective extraction and enrichment of Cu(I) /Cu(II) from beer, soft drinks and wine samples, and speciation analysis by micro-volume UV-Vis spectrophotometry

In this study, a novel functional nanocomposite was synthesized, characterized and selectively used in pH-controlled separation, pre-concentration and speciation analysis of Cu(I) and Cu(II) from sample matrices where extraction is assisted, facilitated and greatly enhanced by ultrasound energy. The hydrophilic composite material functionalized with tris(2-hydroxymethyl)aminomethane (Tris) and Fe₃O₄ NPs was characterized in detail by ATR-FT-IR, ¹H NMR, XRD, EDX peaks and SEM images. After optimization of the main variables influencing extraction efficiency such as pH, volumes of buffer, modified copolymer in acetone, CTAB and Triton X-114 at fixed concentrations including sonication conditions, the Cu(I) and Cu(II) were monitored against a blank at 347 nm by micro-volume UV-vis spectrophotometer. A good linearity was obtained in the range of 2-140 and 5-150 μg L^-1 for Cu(II) and Cu(I) with r² ≥ 0.993. The limits of detection (LODs) of 0.66 and 1.60 μg L^-1 for each analyte, were obtained from a pre-concentration of 70-fold. After validation, the method was applied to speciation of Cu(I), Cu(II), and total Cu in the pre-treated and diluted beverage samples before and after pre-oxidation of Cu(I) to Cu(II) due to be more sensitive of extraction process to Cu(II) at pH 6.0. The results were also compared with those obtained by FAAS analysis to ensure the reliability of the results. It was observed that there was a statistically good agreement between the results of both methods.

Efficiency of Tris-Based Extender Steridyl for Semen Cryopreservation in Stallions

Simple Summary

The cryopreservation and long-term storage of semen is one of the methods for accelerated improvement of the genetic qualities of animals. However, horse breeders prefer to use fresh or chilled semen, as the fertilizing capacity of frozen equine semen is much lower. It is important to find extenders, or a combination of extenders, that will improve semen survival after freezing. It is also important that the extender can be easily and simply prepared for use. Steridyl is a concentrate to which you just need to add sterilized water. This extender was developed for ruminants. In this study we tested Steridyl for freezing stallion semen. The motility, morphology, energy metabolism, DNA damage, and fertility of sperm frozen in Steridyl were evaluated. As a result, Steridyl was shown to be a good extender for equine semen freezing.

Abstract

The fertilizing ability of stallion sperm after freezing is lower than in other species. The search for the optimal extender, combination of extenders, and the freezing protocol is relevant. The aim of this study was to compare lactose-chelate-citrate-yolk (LCCY) extender, usually used in Russia, and Steridyl^® (Minitube) for freezing sperm of stallions. Steridyl is a concentrated extender medium for freezing ruminant semen. It already contains sterilized egg yolk. Semen was collected from nine stallions, aged from 7 to 12 years old. The total and progressive motility of sperm frozen in Steridyl was significantly higher than in semen frozen in LCCY. The number of spermatozoa with normal morphology in samples frozen in LCCY was 60.4 ± 1.72%, and with Steridyl, 72.4 ± 2.10% (p < 0.01). Semen frozen in Steridyl showed good stimulation of respiration by 2.4-DNP, which indicates that oxidative phosphorylation was retained after freezing–thawing. No differences among the extenders were seen with the DNA integrity of spermatozoa. Six out of ten (60%) mares were pregnant after artificial insemination (AI) by LCCY frozen semen, and 9/12 (75%) by Steridyl frozen semen. No differences among extenders were seen in pregnancy rate. In conclusion, Steridyl was proven to be a good diluent for freezing stallion semen, even though it was developed for ruminants.

Effects of Tris (hydroxymethyl) aminomethane on the quality of frozen-thawed boar spermatozoa

Tris (hydroxymethyl) aminomethane (Tris) has been used as a pH regulator for buffering the pH of dilution extenders for boar semen, such as the Modena extender. The purpose of the present study was to assess the effects of Tris supplementation at different concentrations (0, 8, 24 and 72 μM) into the freezing extender on the quality and fertilising capacity of frozen-thawed boar spermatozoa. The results showed that the supplementation of 24 μM of Tris gave significantly higher percentages of sperm viability and plasma membrane integrity than those of the control group at any time point of assessment (0 h and 3 h post-thawing) (P < 0.05). However, there were no significant differences in the acrosome integrity parameter among the groups. Higher percentages of sperm motility were observed in the spermatozoa cryopreserved with 24 μM of Tris compared to the control groups when the samples were analysed 0 h after thawing (P < 0.05). However, an increase of the Tris concentration to 72 μM did not enhance the sperm motility parameters. The total numbers of fertilised oocytes and blastocysts obtained with spermatozoa frozen with 24 μM Tris were significantly higher than those of the control group without Tris (P < 0.05). In conclusion, the supplementation of 24 μM Tris into the freezing extender contributes to a better boar sperm quality and fertilising capacity after the process of freezing and thawing.

Cross-sectional study of social behaviors in preschool children and exposure to flame retardants

BACKGROUND

Children are exposed to flame retardants from the built environment. Brominated diphenyl ethers (BDE) and organophosphate-based flame retardants (OPFRs) are associated with poorer neurocognitive functioning in children. Less is known, however, about the association between these classes of compounds and children's emotional and social behaviors. The objective of this study was to determine if flame retardant exposure was associated with measurable differences in social behaviors among children ages 3-5 years.

METHODS

We examined teacher-rated social behaviors measured using the Social Skills Improvement Rating Scale (SSIS) and personal exposure to flame retardants in children aged 3-5 years who attended preschool (n = 72). Silicone passive samplers worn for 7 days were used to assess personal exposure to 41 compounds using gas chromatography-mass spectrophotometer. These concentrations were then summed into total BDE and total OPFR exposure prior to natural log transformation. Separate generalized additive models were used to evaluate the relationship between seven subscales of the SSIS and lnΣBDE or lnΣOPFR adjusting for other age, sex, adverse social experiences, and family context.

RESULTS

All children were exposed to a mixture of flame retardant compounds. We observed a dose dependent relationship between lnΣOPFR and two subscales where children with higher exposures were rated by their preschool teachers as having less responsible behavior (p = 0.07) and more externalizing behavior problems (p = 0.03). Additionally, children with higher lnΣBDE exposure were rated by teachers as less assertive (p = 0.007).

CONCLUSIONS

We observed a cross-sectional association between children's exposure to flame retardant compounds and teacher-rated social behaviors among preschool-aged children. Children with higher flame retardant exposures exhibited poorer social skills in three domains that play an important role in a child's ability to succeed academically and socially.

Parkinsonism-associated protein DJ-1 is a bona fide deglycase

We discovered recently that Parkinsonism-associated DJ-1 and its bacterial homologs function as protein deglycases that repair glyoxal- and methylglyoxal-glycated proteins. Protein glycation levels are 2- to 10-fold increased in deglycase-depleted cells, and deglycase mutants display up to 500-fold loss of viability in methylglyoxal or glucose-containing media, suggesting that these deglycases play important roles in protecting cells against electrophile and carbonyl stress. Although the deglycase activity of DJ-1 is well supported by extensive biochemical work, Pfaff et al. (J. Biol. Chem. in presshttp://dx.doi.org/10.1074/jbc.M116.743823) claimed in a recent study that deglycation of the hemithioacetal formed upon cysteine glycation by methylglyoxal results from a Tris buffer artefact. Here, we show that this is not the case, and that DJ-1 and its homologs are the bona fide deglycases awaited since the Maillard discovery.

Effect of Tris, MOPS, and phosphate buffers on the hydrolysis of polyethylene terephthalate films by polyester hydrolases

The enzymatic degradation of polyethylene terephthalate (PET) occurs at mild reaction conditions and may find applications in environmentally friendly plastic waste recycling processes. The hydrolytic activity of the homologous polyester hydrolases LC cutinase (LCC) from a compost metagenome and TfCut2 from Thermobifida fusca KW3 against PET films was strongly influenced by the reaction medium buffers tris(hydroxymethyl)aminomethane (Tris), 3-(N-morpholino)propanesulfonic acid (MOPS), and sodium phosphate. LCC showed the highest initial hydrolysis rate of PET films in 0.2 m Tris, while the rate of TfCut2 was 2.1-fold lower at this buffer concentration. At a Tris concentration of 1 m, the hydrolysis rate of LCC decreased by more than 90% and of TfCut2 by about 80%. In 0.2 m MOPS or sodium phosphate buffer, no significant differences in the maximum initial hydrolysis rates of PET films by both enzymes were detected. When the concentration of MOPS was increased to 1 m, the hydrolysis rate of LCC decreased by about 90%. The activity of TfCut2 remained low compared to the increasing hydrolysis rates observed at higher concentrations of sodium phosphate buffer. In contrast, the activity of LCC did not change at different concentrations of this buffer. An inhibition study suggested a competitive inhibition of TfCut2 and LCC by Tris and MOPS. Molecular docking showed that Tris and MOPS interfered with the binding of the polymeric substrate in a groove located at the protein surface. A comparison of the K i values and the average binding energies indicated MOPS as the stronger inhibitor of the both enzymes.

Monitoring the chemical and physical stability for tromethamine excipient in a lipid based formulation by HPLC coupled with ELSD

Tromethamine, a UV-transparent amine base excipient, was used in the liquid phase of a self-emulsifying drug delivery system-soft gelatin capsule (SEDDS-SGC) formulation as an emulsification agent and to improve solubilization of the active drug. The level of this excipient was found to be decreasing in aged and stressed drug product capsules. The decrease could potentially affect oral bioavailability of the drug; should the amount of solubilizer decrease enough to lead to precipitation of the active drug from the formulation. Therefore, further investigation was warranted. HPLC coupled with evaporative light scattering detection (ELSD) was used to monitor the physical and chemical stability of tromethamine in the SEDDS-SGC formulation. Confirmation of the tromethamine interaction products was done by LC-MS.

Comparative gene expression analysis of Dtg, a novel target gene of Dpp signaling pathway in the early Drosophila melanogaster embryo

In the early Drosophila melanogaster embryo, Dpp, a secreted molecule that belongs to the TGF-β superfamily of growth factors, activates a set of downstream genes to subdivide the dorsal region into amnioserosa and dorsal epidermis. Here, we examined the expression pattern and transcriptional regulation of Dtg, a new target gene of Dpp signaling pathway that is required for proper amnioserosa differentiation. We showed that the expression of Dtg was controlled by Dpp and characterized a 524-bp enhancer that mediated expression in the dorsal midline, as well as, in the differentiated amnioserosa in transgenic reporter embryos. This enhancer contained a highly conserved region of 48-bp in which bioinformatic predictions and in vitro assays identified three Mad binding motifs. Mutational analysis revealed that these three motifs were necessary for proper expression of a reporter gene in transgenic embryos, suggesting that short and highly conserved genomic sequences may be indicative of functional regulatory regions in D. melanogaster genes. Dtg orthologs were not detected in basal lineages of Dipterans, which unlike D. melanogaster develop two extra-embryonic membranes, amnion and serosa, nevertheless Dtg orthologs were identified in the transcriptome of Musca domestica, in which dorsal ectoderm patterning leads to the formation of a single extra-embryonic membrane. These results suggest that Dtg was recruited as a new component of the network that controls dorsal ectoderm patterning in the lineage leading to higher Cyclorrhaphan flies, such as D. melanogaster and M. domestica.

Using a Caesalpinia echinata Lam. protease inhibitor as a tool for studying the roles of neutrophil elastase, cathepsin G and proteinase 3 in pulmonary edema

Acute lung injury (ALI) is characterized by neutrophil infiltration and the release of proteases, mainly elastase (NE), cathepsin G (Cat G) and proteinase 3 (PR3), which can be controlled by specific endogenous inhibitors. However, inhibitors of these proteases have been isolated from different sources, including plants. For this study, CeEI, or Caesalpinia echinata elastase inhibitor, was purified from C. echinata (Brazil-wood) seeds after acetone fractionation, followed by ion exchange and reversed phase chromatographic steps. Characterization with SDS-PAGE, stability assays, amino acid sequencing and alignment with other protein sequences confirmed that CeEI is a member of the soybean Kunitz trypsin inhibitor family. Like other members of this family, CeEI is a 20 kDa monomeric protein; it is stable within a large pH and temperature range, with four cysteine residues forming two disulfide bridges, conserved amino acid residues and leucine-isoleucine residues in the reactive site. CeEI was able to inhibit NE and Cat G at a nanomolar range (with K(i)s of 1.9 and 3.6 nM, respectively) and inhibited PR3 within a micromolar range (K(i) 3.7 μM), leading to hydrolysis of specific synthetic substrates. In a lung edema model, CeEI reduced the lung weight and pulmonary artery pressure until 180 min after the injection of zymosan-activated polymorphonuclear neutrophils. In experiments performed in the presence of a Cat G and PR3, but not an NE inhibitor, lung edema was reduced only until 150 min and pulmonary artery pressure was similar to that of the control. These results confirm that NE action is crucial to edema establishment and progression. Additionally, CeEI appears to be a useful tool for studying the physiology of pulmonary edema and provides a template for molecular engineering and drug design for ALI therapy.

Identification, expression and bioactivity of hexokinase in amphioxus: insights into evolution of vertebrate hexokinase genes

Hexokinase family includes hexokinases I, II, III and IV, that catalyze the phosphorylation of glucose to produce glucose 6-phosphate. Hexokinase IV, also known as glucokinase, is only half size of the other types of hexokinases that contain two hexokinase domains. Despite the enormous progress in the study of hexokinases, the evolutionary relationship between glucokinase and other hexokinases is still uncertain, and the molecular processes leading to the emergence of hexokinases in vertebrates remain controversial. Here we clearly demonstrated the presence of a single hexokinase-like gene in the amphioxus Branchiostoma japonicum, Bjhk, which shows a tissue-specific expression pattern, with the most abundant expression in the hepatic caecum, testis and ovary. The phylogenetic and synteny analyses both reveal that BjHK is the archetype of vertebrate hexokinases IV, i.e. glucokinases. We also found for the first time that recombinant BjHK showed functional enzyme activity resembling vertebrate hexokinases I, II, III and IV. In addition, a native glucokinase activity was detected in the hepatic caecum. Finally, glucokinase activity in the hepatic caecum was markedly reduced by fasting, whereas it was considerably increased by feeding. Altogether, these suggest that Bjhk represents the archetype of glucokinases, from which vertebrate hexokinase gene family was evolved by gene duplication, and that the hepatic caecum plays a role in the control of glucose homeostasis in amphioxus, in favor of the notion that the hepatic caecum is a tissue homologous to liver.

Syntheses and characterization of non-bisphosphonate quinoline derivatives as new FPPS inhibitors

BACKGROUND

Farnesyl pyrophosphate synthase (FPPS) is a key regulatory enzyme in the biosynthesis of cholesterol and in the post-translational modification of signaling proteins. It has been reported that non-bisphosphonate FPPS inhibitors targeting its allosteric binding pocket are potentially important for the development of promising anti-cancer drugs.

METHODS

The following methods were used: organic syntheses of non-bisphosphonate quinoline derivatives, enzyme inhibition studies, fluorescence titration assays, synergistic effect studies of quinoline derivatives with zoledronate, ITC studies for the binding of FPPS with quinoline derivatives, NMR-based HAP binding assays, molecular modeling studies, fluorescence imaging assay and MTT assays.

RESULTS

We report our syntheses of a series of quinoline derivatives as new FPPS inhibitors possibly targeting the allosteric site of the enzyme. Compound 6b showed potent inhibition to FPPS without significant hydroxyapatite binding affinity. The compound showed synergistic inhibitory effect with active-site inhibitor zoledronate. ITC experiment confirmed the good binding effect of compound 6b to FPPS, and further indicated the binding ratio of 1:1. Molecular modeling studies showed that 6b could possibly bind to the allosteric binding pocket of the enzyme. The fluorescence microscopy indicated that these compounds could get into cancer cells.

CONCLUSIONS

Our results showed that quinoline derivative 6b could become a new lead compound for further optimization for cancer treatment.

GENERAL SIGNIFICANCE

The traditional FPPS active-site inhibitors bisphosphonates show poor membrane permeability to tumor cells, due to their strong polarity. The development of new non-bisphosphonate FPPS inhibitors with good cell membrane permeability is potentially important.

Three isozymes of peptidylarginine deiminase in the chicken: molecular cloning, characterization, and tissue distribution

Peptidylarginine deiminase (PAD; EC 3.5.3.15) is a post-translational modification enzyme that catalyzes the conversion of protein-bound arginine to citrulline (deimination) in a calcium ion dependent manner. Although PADI genes are widely conserved among vertebrates, their function in the chicken is poorly understood. Here, we cloned and sequenced three chicken PADI cDNAs and analyzed the expression of their proteins in various tissues. Immunoblotting analysis showed that chicken PAD1 and PAD3 were present in cells of several central neuron system tissues including the retina; the chicken PAD2 protein was not detected in any tissue. We expressed recombinant chicken PADs in insect cells and characterized their enzymatic properties. The chicken PAD1 and PAD3 recombinant proteins required calcium ions as an essential cofactor for their catalytic activity. The two recombinant proteins showed similar substrate specificities toward synthetic arginine derivatives. By contrast to them, chicken PAD2 did not show any activity. We found that one of the conserved active centers in mammalian PADs had been altered in chicken PAD2; we prepared a reverse mutant but we did not detect an activity. We conclude that chicken PAD1 and PAD3 might play specific roles in the nervous system, but that chicken PAD2 might not be functional under normal physiological conditions.

A new hydrothermal refluxing route to strong fluorescent carbon dots and its application as fluorescent imaging agent

Due to their unique optical and biochemical properties, the water-soluble fluorescent carbon dots (CDs) have attracted a lot of attention recently. Here, strong fluorescent carbon dots with excellent quality have been synthesized by the hydrothermal refluxing method using lactose as carbon source and tris(hydroxymethyl) aminomethane (i.e. Tris) as surface passivation reagent. This facile approach was simple, efficient, economical, green without pollution, and allows large-scale production of CDs without any post-treatment. TEM measurements showed that the resulting particles exhibited an average diameter of 1.5 nm. The obtained CDs possess small particle sizes, good stability in a wide range of pH values (pH 3.5-9.5), high tolerance of salt concentration, strong resistibility to photobleaching, and a fluorescent quantum yield up to 12.5%. The CDs were applied to optical bioimaging of HeLa cells, showing low cytotoxicity and excellent biocompatibility.

Cytoprotective and antioxidant effects of the edible halophyte Sarcocornia perennis L. (swampfire) against lead-induced toxicity in renal cells

Lead (Pb) exposure is considered as a risk factor responsible for renal impairment in humans. On the other hand, the halophyte Sarcocornia perennis is a fresh vegetable crop suitable for leafy vegetable production. This study was designed to evaluate the in vitro protective activity of S. perennis against lead-induced damages in HEK293 kidney cells. Morphological and biochemical indicators were used to assess cytotoxicity and oxidative damages caused by Pb treatment on the cells. Our results showed that lead induced (1) a decrease in cell viability (MTT), (2) cell distortion and cohesion loss, (3) superoxide anion production and lipid peroxidation. Conversely, addition of S. perennis extract to the lead-containing medium alleviated every above syndrome. Thus, cell survival was increased and the production of reactive oxygen species caused by Pb treatment was inhibited. Taken together, our study revealed that S. perennis has potent cytoprotective effect against Pb-induced toxicity in HEK 293 cell. Such action would proceed through the decrease in ROS levels and resulting oxidative stress, which suggests a potential interest of this halophyte in the treatment of oxidative-stress related diseases.

Aluminum-induced programmed cell death promoted by AhSAG, a senescence-associated gene in Arachis hypoganea L

Programmed cell death (PCD) is a foundational cellular process in plant development and elimination of damaged cells under environmental stresses. In this study, Al induced PCD in two peanut (Arachis hypoganea L.) cultivars Zhonghua 2 (Al-sensitive) and 99-1507 (Al-tolerant) using DNA ladder, TUNEL detection and electron microscopy. The concentration of Al-induced PCD was lower in Zhonghua 2 than in 99-1507. AhSAG, a senescence-associated gene was isolated from cDNA library of Al-stressed peanut with PCD. Open reading frame (ORF) of AhSAG was 474bp, encoding a SAG protein composed of 157 amino acids. Compared to the control and the antisense transgenic tobacco plants, the fast development and blossom of the sense transgenic plants happened to promote senescence. The ability of Al tolerance in sense transgenic tobacco was lower than in antisense transgenic tobacco according to root elongation and Al content analysis. The expression of AhSAG-GFP was higher in sense transgenic tobacco than in antisense transgenic tobacco. Altogether, these results indicated that there was a negative relationship between Al-induced PCD and Al-resistance in peanut, and the AhSAG could induce or promote the occurrence of PCD in plants.

Isolated noncatalytic and catalytic subunits of F1-ATPase exhibit similar, albeit not identical, energetic strategies for recognizing adenosine nucleotides

The function of F1-ATPase relies critically on the intrinsic ability of its catalytic and noncatalytic subunits to interact with nucleotides. Therefore, the study of isolated subunits represents an opportunity to dissect elementary energetic contributions that drive the enzyme's rotary mechanism. In this study we have calorimetrically characterized the association of adenosine nucleotides to the isolated noncatalytic α-subunit. The resulting recognition behavior was compared with that previously reported for the isolated catalytic β-subunit (N.O. Pulido, G. Salcedo, G. Pérez-Hernández, C. José-Núñez, A. Velázquez-Campoy, E. García-Hernández, Energetic effects of magnesium in the recognition of adenosine nucleotides by the F1-ATPase β subunit, Biochemistry 49 (2010) 5258-5268). The two subunits exhibit nucleotide-binding thermodynamic signatures similar to each other, characterized by enthalpically-driven affinities in the μM range. Nevertheless, contrary to the catalytic subunit that recognizes MgATP and MgADP with comparable strength, the noncatalytic subunit much prefers the triphosphate nucleotide. Besides, the α-subunit depends more on Mg(II) for stabilizing the interaction with ATP, while both subunits are rather metal-independent for ADP recognition. These binding behaviors are discussed in terms of the properties that the two subunits exhibit in the whole enzyme.

CCL5-glutamate interaction in central nervous system: Early and acute presynaptic defects in EAE mice

We investigated the CCL5-glutamate interaction in the cortex and in the spinal cord from mice with Experimental Autoimmune Encephalomyelitis (EAE) at 13 and 21/30 days post immunization (d.p.i.), representing the onset and the peak of the disease, respectively. An early reduction of the KCl-evoked glutamate release was observed in cortical terminals from EAE mice at 13 d.p.i., persisting until 21/30 d.p.i. A concomitant reduction of the depolarization-evoked cyclic adenosine monophosphate (cAMP), but not of the inositol 1,4,5-trisphosphate (IP3) cortical production also occurred at 13 d.p.i, that still was detectable at the acute stage of disease (21 dp.i.). Inasmuch, the CCL5-mediated inhibition of glutamate exocytosis observed in control mice turned to facilitation in EAE mouse cortex at 13 d.p.i., then becoming undetectable at 21/30 d.p.i. Differently, glutamate exocytosis, as well as IP3 and cAMP productions were unaltered in spinal cord synaptosomes from EAE mice at 13 d.p.i., but significantly increased at 21/30 d.p.i., while the presynaptic CCL5-mediated facilitation of glutamate exocytosis observed in control mice remained unchanged. In both CNS regions, the presynaptic defects were parallelled by increased CCL5 availability. Inasmuch, the presynaptic defects so far described in EAE mice were reminiscent of the effects acute CCL5 exerts in control conditions. Based on these observations we propose that increased CCL5 bioavailability could have a role in determining the abovedescribed impaired presynaptic impairments in both CNS regions. These presynaptic defects could be relevant to the onset of early cognitive impairments and acute neuroinflammation and demyelinating processes observed in multiple sclerosis patients.

Formation and characterization of iron-binding phosphorylated human-like collagen as a potential iron supplement

Iron incorporated into food can induce precipitation and unwanted interaction with other components in food. Iron-binding proteins represent a possibility to avoid these problems and other side effects, as the iron is protected. However, there are several technical problems associated with protein-iron complex formation. In this paper, the iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared under physiological conditions through phosphorylated modification. One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. Spectroscopy analysis, differential scanning calorimetry (DSC) and equilibrium dialysis techniques were employed to investigate the characteristics of the Fe-G6P-HLC. The binding sites (nb) and apparent association constant (Kapp) between iron and phosphorylated HLC were measured at nb=23.7 and log Kapp=4.57, respectively. The amount of iron (Fe(2+) sulfate) binding to phosphorylated HLC was found to be a function of pH and phosphate content. In addition, the solubility and thermal stability of HLC were not significantly affected. The results should facilitate the utilization of HLC as a bioactive iron supplement in the food and medical industry and provide an important theoretical evidence for the application of HLC chelates.

An HPLC-tandem mass spectrometry method for simultaneous detection of alkylated base excision repair products

DNA glycosylases excise a broad spectrum of alkylated, oxidized, and deaminated nucleobases from DNA as the initial step in base excision repair. Substrate specificity and base excision activity are typically characterized by monitoring the release of modified nucleobases either from a genomic DNA substrate that has been treated with a modifying agent or from a synthetic oligonucleotide containing a defined lesion of interest. Detection of nucleobases from genomic DNA has traditionally involved HPLC separation and scintillation detection of radiolabeled nucleobases, which in the case of alkylation adducts can be laborious and costly. Here, we describe a mass spectrometry method to simultaneously detect and quantify multiple alkylpurine adducts released from genomic DNA that has been treated with N-methyl-N-nitrosourea (MNU). We illustrate the utility of this method by monitoring the excision of N3-methyladenine (3 mA) and N7-methylguanine (7 mG) by a panel of previously characterized prokaryotic and eukaryotic alkylpurine DNA glycosylases, enabling a comparison of substrate specificity and enzyme activity by various methods. Detailed protocols for these methods, along with preparation of genomic and oligonucleotide alkyl-DNA substrates, are also described.

Characterization of the human mitochondrial thiamine pyrophosphate transporter SLC25A19 minimal promoter: a role for NF-Y in regulating basal transcription

Transcriptional regulation of expression of the human mitochondrial thiamine pyrophosphate transporter (the product of the SLC25A19 gene) is unknown. To understand this regulation, we cloned and characterized the 5'-regulatory region of the SLC25A19 gene (1,080 bp). The cloned fragment was found to possess promoter activity in transiently transfected human-derived liver HepG2 cells. 5'- and 3'-deletion analysis has identified the minimal region required for basal SLC25A19 promoter activity to be between -131 and +20 (using the distal transcriptional start site as +1). The minimal promoter lacks typical TATA motif and contains two inverted CCAAT boxes (binding sites for NF-Y transcriptional factor). By means of mutational analysis, the critical role of both the upstream and downstream CCAAT boxes in basal SLC25A19 promoter activity was established; however, each of these boxes alone was found to be unable to support promoter activity. EMSA and supershift EMSA (with the use of specific antibodies against NF-Y subunits) studies, as well as chromatin immunoprecipitation assay, demonstrated the binding of NF-Y to both CCAAT boxes in vitro and in vivo, respectively. The requirement for NF-Y in SLC25A19 promoter activity in vivo was directly confirmed by the use of a dominant negative NF-YA mutant in transiently transfected HepG2 cells. These studies report for the first time the characterization of the SLC25A19 promoter and demonstrate an essential role for NF-Y in its basal activity.

Presynaptic TRPV1 vanilloid receptor function is age- but not CB1 cannabinoid receptor-dependent in the rodent forebrain

Neocortical and striatal TRPV1 (vanilloid or capsaicin) receptors (TRPV1Rs) are excitatory ligand-gated ion channels, and are implicated in psychiatric disorders. However, the purported presynaptic neuromodulator role of TRPV1Rs in glutamatergic, serotonergic or dopaminergic terminals of the rodent forebrain remains little understood. With the help of patch-clamp electrophysiology and neurochemical approaches, we mapped the age-dependence of presynaptic TRPV1R function, and furthermore, we aimed at exploring whether the presence of CB1 cannabinoid receptors (CB1Rs) influences the function of the TRPV1Rs, as both receptor types share endogenous ligands. We found that the major factor which affects presynaptic TRPV1R function is age: by post-natal day 13, the amplitude of capsaicin-induced release of dopamine and glutamate is halved in the rat striatum, and two weeks later, capsaicin already loses its effect. However, TRPV1R receptor function is not enhanced by chemical or genetic ablation of the CB1Rs in dopaminergic, glutamatergic and serotonergic terminals of the mouse brain. Altogether, our data indicate a possible neurodevelopmental role for presynaptic TRPV1Rs in the rodent brain, but we found no cross-talk between TRPV1Rs and CB1Rs in the same nerve terminal.

Unique monoclonal antibodies specifically bind surface structures on human fetal erythroid blood cells

BACKGROUND

Continuing efforts in development of non-invasive prenatal genetic tests have focused on the isolation of fetal nucleated red blood cells (NRBCs) from maternal blood for decades. Because no fetal cell-specific antibody has been described so far, the present study focused on the development of monoclonal antibodies (mAbs) to antigens that are expressed exclusively on fetal NRBCs.

METHODS

Mice were immunized with fetal erythroid cell membranes and hybridomas screened for Abs using a multi-parameter fluorescence-activated cell sorting (FACS). Selected mAbs were evaluated by comparative FACS analysis involving Abs known to bind erythroid cell surface markers (CD71, CD36, CD34), antigen-i, galactose, or glycophorin-A (GPA). Specificity was further confirmed by extensive immunohistological and immunocytological analyses of NRBCs from umbilical cord blood and fetal and adult cells from liver, bone marrow, peripheral blood, and lymphoid tissues.

RESULTS

Screening of 690 hybridomas yielded three clones of which Abs from 4B8 and 4B9 clones demonstrated the desired specificity for a novel antigenic structure expressed on fetal erythroblast cell membranes. The antigenic structure identified is different from known surface markers (CD36, CD71, GPA, antigen-i, and galactose), and is not present on circulating adult erythroid cells, except for occasional detectability in adult bone marrow cells.

CONCLUSIONS

The new mAbs specifically bind the same or highly overlapping epitopes of a surface antigen that is almost exclusively expressed on fetal erythroid cells. The high specificity of the mAbs should facilitate development of simple methods for reliable isolation of fetal NRBCs and their use in non-invasive prenatal diagnosis of fetal genetic status.

Discovered triethylamine as impurity in synthetic DNAs for and by electrochemiluminescence techniques

The purity of the synthetic oligonucleotides is very important because it is crucial for the accuracy of the established biological assays. Herein, it was discovered that one impurity in synthetic DNAs might affect the experiment results of electrochemiluminescence (ECL) detection techniques, which was never reported before. According to a series of experiments using ECL detection methods combined with capillary electrophoresis (CE) (CE-ECL), the impurity was identified as triethylamine (TEA), which came from incomplete removal after HPLC purification of synthetic DNAs. Moreover, CE-ECL technique was for the first time to be proposed for discovering, identifying and sensitive determining the possible impurity such as TEA in various DNA samples, which was usually neglected by other detection techniques for purification quality control of synthetic oligonucleotides. A detection range from 5.00×10(-10) to 2.00×10(-5) M with a detection limit as low as 50 nM (S/N=3) was reached for TEA. Through further designed ECL methods and data analysis, situations which would be really affected by the impurity of TEA were studied. To avoid or eliminate the impact of the TEA impurity on ECL applications, judgment basis for choosing purification ways was discussed according to individual requirements.

Effect of vitamins C or E supplementation to Tris diluent on the semen quality of Awassi rams preserved at 5 ˚C

The present study was aimed to test the efficacy of adding vitamins C or E to Tris-fructose-egg yolk diluent to increase Awassi ram sperm storage period at 5 ˚C. Semen samples from six mature Awassi rams were used in this study. The semen samples were diluted by Tris-glucose-egg yolk. Diluted semen sample was divided into three parts. The first part was added with 0.9 mg mL(-1) vitamin C, the second part was added with 1 mg mL(-1) vitamin E and the third part was considered as a control without any addition. The diluted semen samples were cooled gradually and preserved at 5 ˚C for five days. Sperms in cooled diluted semen samples were examined for motility, vitality, abnormalities and acrosomal defects every 24 hr for five days. Results of the present study showed an increase in the viability of spermatozoa diluted in the Tris diluent containing vitamins C or E stored at 5 ˚C for 120 hr compared with the control group. There were significant (p < 0.05) effects of vitamins C and E addition to semen diluents on sperm motility as well as the sperm viability in different times of preservation at 5 ˚C. Significant (p < 0.05) higher sperm abnormalities and acrosomal defects values (37.6 ± 1.3% and 71.5 ± 1.1%, respectively) were found after 120 hr incubation in Tris free vitamin C (Control) at 5 ˚C compared with those of containing vitamin C (18.8 ± 1.8% and 52.8 ± 4.3%, respectively). From the results of the present study, it could be concluded, that the addition of antioxidants such as vitamins C and vitamin E to semen preservation media could improve longevity and quality of cooled sperm in Awassi ram semen.