Efficient synthesis of 3D ZnO nanostructures on ITO surfaces for enhanced photoelectrochemical water splitting

New photoactive materials with uniform and well-defined morphologies were developed for efficient and sustainable photoelectrochemical (PEC) water splitting and hydrogen production. The investigation is focused on hydrothermal deposition of zinc oxide (ZnO) onto indium tin oxide (ITO) conductive surfaces and optimization of hydrothermal temperature for growing uniform sized 3D ZnO morphologies. Fine-tuning of hydrothermal temperature enhanced the scalability, efficiency, and performance of ZnO-decorated ITO electrodes used in PEC water splitting. Under UV light irradiation and using eco-friendly low-cost hydrothermal process in the presence of stable ZnO offered uniform 3D ZnO, which exhibited a high photocurrent of 0.6 mA/cm2 having stability up to 5 h under light-on and light-off conditions. The impact of hydrothermal temperature on the morphological properties of the deposited ZnO and its subsequent performance in PEC water splitting was investigated. The work contributes to advancement of scalable and efficient fabrication technique for developing energy converting photoactive materials.

Sharp-edged pencil type ZnO flowers and BiOI flakes combined with carbon nanofibers as heterostructured hybrid photocatalysts for the removal of hazardous pollutants from contaminated water

The growth of advanced micro-and nanostructures with metal oxides has consistently generated extraordinary interest in energy and environmental applications. Cutting-edge nanostructures exhibit superior reactive sites and surface areas, thus improving the performance in crucial domains. In this study, sharp-edged pencil-type ZnO flowers and BiOI flakes as pristine materials, and their composition with carbon nanofibers (CNFs) (ZnO-BiOI@CNFs) as a hetero hybrid catalyst as well as binary compositions such as ZnO-BiOI, ZnO@CNFs, and BiOI@CNFs catalysts were fabricated using a simple and convenient hydrothermal synthesis process. The composition of newly produced innovative nanostructures was examined for azo dye degradation under solar simulator exposure. Dye degradation of ∼95% was achieved by the hybrid catalyst (ZnO-BiOI@CNFs) during 120 min of irradiation, which was ∼1.8 and 2.1-times higher than pristine ZnO and BiOI nanostructures, respectively. The improved hybrid catalysts were able to degrade methyl orange (MO) and rhodamine B (RhB) dyes. Importantly, mixed dyes RhB, MO, and azo dye demonstrated 47% dye degradation using a hybrid catalyst. These mixed dye-scalable hybrid catalyst performances offer additional insights into commercialization/industrialization. The outstanding performance of the hybrid catalyst is attributed to the unidirectional electron flow with pencil-like ZnO, a catalyst with a larger absorption zone, high surface area, and reactive sites, particularly ZnO and BiOI nanostructures, and decreased recombination rate with a heterojunction interface. In addition, CNFs can operate as electron traps and sinks, providing very quick redox reactions. To produce the sophisticated nanostructures with homogeneous morphologies, this work presents new insights into energy and environmental applications.

Novel rhombus Co3O4-nanocapsule CuO heterohybrids for efficient photocatalytic water splitting and electrochemical energy storage applications

The most appealing and prominent approach for improving energy storage and conversion performance is the development of heterojunction interfaces with efficient and unique metal oxide nanostructures. Rhombus Co₃O₄, nanocapsule CuO, and their heterojunction composites were synthesized using a single-step hydrothermal process. The resulting heterojunction Co₃O₄-CuO nanocomposite outperformed the pristine Co₃O₄ and CuO nanostructures for the electrochemical supercapacitor and water splitting performances. The composite showed 2.4 and 1.3 times higher specific capacitance than the associated pristine CuO and Co₃O₄ nanostructures, while its capacitance was 395 F g^-1 at a current density of 0.5 A g^-1. In addition, long-term GCD results with more than 90% stability and significant capacity retention at higher scan rates revealed the unaffected structures interfaced during the electrochemical reactions. The composite photoelectrode demonstrated more than 20% of photocurrent response with light illumination than the dark condition in water splitting. Co₃O₄-CuO heterostructured composite electrode showed a 0.16 mA/cm² photocurrent density, which is 3.2 and 1.7 times higher than the pristine CuO and Co₃O₄ electrodes, respectively. This performance was attributed to its unique structural composition, high reactive sites, strong ion diffusion, and fast electron accessibility. Electron microscopic and spectroscopic techniques confirmed the properties of the electrodes as well as their morphological properties. Overall, the heterojunction interface with novel rhombus and capsule structured architectures showed good electrochemical performance, suggesting their energy storage and conversion applications.

Synthesis of novel Co3O4 nanocubes-NiO octahedral hybrids for electrochemical energy storage supercapacitors

Fabrication of novel metal oxide nanostructured composites is a proficient approach to develop efficient energy storage devices and development of cost-free and eco-friendly metal oxide nanostructures for supercapacitor applications received considerable attention in recent years. The Co₃O₄ nanocubes-NiO octahedral structured composite was constructed using facile and one-step calcination process. Cyclic voltammetry, charge-discharge, and electrochemical impedance spectral techniques have been employed to analyze the specific capacitance of the synthesized nanostructures and the composites. Specific capacitance and cycling stability of the composites were evaluated with the pristine Co₃O₄ and NiO nanostructures. The composite showed a specific capacitance of 832 F g^-1 at a current density of 0.25 A g^-1, which was ~1.5 and ~1.9-times higher than pristine Co₃O₄ nanocubes and NiO octahedral structure, respectively. On the other hand, electrode showed approximately 50 % capacity retention at a higher current density (5 Ag^-1) because of the uniform morphology of Co₃O₄ and NiO. The charge-discharge stability measurements of the composite showed an admirable specific capacitance retention capability, which was 94.5 % after 2000 continuous charge-discharge cycles at a current density of 5 A g^-1. The superior electrochemical performance of the nano-composite was ascribed to synergistic effects and uniform morphology. Efficient nanostructure development using facile and one-step calcination process and electrochemical performance make the synthesized composite a promising device for supercapacitor applications.

Photocatalytic hydrogen production by ternary heterojunction composites of silver nanoparticles doped FCNT-TiO2

Silver nanoparticles doped with FCNT-TiO₂ heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV-Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g^-1 h^-1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO₂ nanoparticles and FCNT-TiO₂ nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO₂ photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production.

Mass Spectrometry in Microbial Forensics

Mass spectrometry (MS) has become a powerful tool to identify microbial biomarkers. Rapid and reliable identification of microorganisms by MS without extensive sample pretreatment is now possible. An effective microbial forensics program requires accurate characterization of pathogens to indicate their presence. MS methods provide such capabilities for forensic analysis. MS methods currently utilized for microbial analyses are reviewed. Techniques including capillary electrophoresis, liquid chromatography, gas chromatography, and pyrolysis that are coupled to MS analysis are described. A brief introduction to the two advanced ionization techniques, electrospray ionization and matrix-assisted laser desorption/ionization, for MS is provided in this review. Methods based on characterization of biomarkers including proteins, DNA molecules, lipids, and other small molecules are reviewed.

Short, strong hydrogen bonds at the active site of human acetylcholinesterase: proton NMR studies

Cholinesterases use a Glu-His-Ser catalytic triad to enhance the nucleophilicity of the catalytic serine. We have previously shown by proton NMR that horse serum butyryl cholinesterase, like serine proteases, forms a short, strong hydrogen bond (SSHB) between the Glu-His pair upon binding mechanism-based inhibitors, which form tetrahedral adducts, analogous to the tetrahedral intermediates in catalysis [Viragh, C., et al. (2000) Biochemistry 39, 16200-16205]. We now extend these studies to human acetylcholinesterase, a 136 kDa homodimer. The free enzyme at pH 7.5 shows a proton resonance at 14.4 ppm assigned to an imidazole NH of the active-site histidine, but no deshielded proton resonances between 15 and 21 ppm. Addition of a 3-fold excess of the mechanism-based inhibitor m-(N,N,N-trimethylammonio)trifluoroacetophenone (TMTFA) induced the complete loss of the 14.4 ppm signal and the appearance of a broad, deshielded resonance of equal intensity with a chemical shift delta of 17.8 ppm and a D/H fractionation factor phi of 0.76 +/- 0.10, consistent with a SSHB between Glu and His of the catalytic triad. From an empirical correlation of delta with hydrogen bond lengths in small crystalline compounds, the length of this SSHB is 2.62 +/- 0.02 A, in agreement with the length of 2.63 +/- 0.03 A, independently obtained from phi. Upon addition of a 3-fold excess of the mechanism-based inhibitor 4-nitrophenyl diethyl phosphate (paraoxon) to the free enzyme at pH 7.5, and subsequent deethylation, two deshielded resonances of unequal intensity appeared at 16.6 and 15.5 ppm, consistent with SSHBs with lengths of 2.63 +/- 0.02 and 2.65 +/- 0.02 A, respectively, suggesting conformational heterogeneity of the active-site histidine as a hydrogen bond donor to either Glu-327 of the catalytic triad or to Glu-199, also in the active site. Conformational heterogeneity was confirmed with the methylphosphonate ester anion adduct of the active-site serine, which showed two deshielded resonances of equal intensity at 16.5 and 15.8 ppm with phi values of 0.47 +/- 0.10 and 0.49 +/- 0.10 corresponding to average hydrogen bond lengths of 2.59 +/- 0.04 and 2.61 +/- 0.04 A, respectively. Similarly, lowering the pH of the free enzyme to 5.1 to protonate the active-site histidine (pK(a) = 6.0 +/- 0.4) resulted in the appearance of two deshielded resonances, at 17.7 and 16.4 ppm, consistent with SSHBs with lengths of 2.62 +/- 0.02 and 2.63 +/- 0.02 A, respectively. The NMR-derived distances agree with those found in the X-ray structures of the homologous acetylcholinesterase from Torpedo californica complexed with TMTFA (2.66 +/- 0.28 A) and sarin (2.53 +/- 0.26 A) and at low pH (2.52 +/- 0.25 A). However, the order of magnitude greater precision of the NMR-derived distances establishes the presence of SSHBs at the active site of acetylcholinesterase, and detect conformational heterogeneity of the active-site histidine. We suggest that the high catalytic power of cholinesterases results in part from the formation of a SSHB between Glu and His of the catalytic triad.

Effect of ATP sensitive potassium channel modifiers on antinociceptive effect of metoclopramide

Metoclopramide, a prokinetic drug, has been documented to produce antinociceptive response in animal models through opioid pathways. Morphine has been shown to act through ATP sensitive potassium channels (KATP) to produce antinociceptive response. However, such a possibility has not been examined for metoclopramide. The present study investigated this using pharmacological tools. Acetic acid induced abdominal constriction assay procedure was utilized to assess antinociception. The results confirmed that metoclopramide has antinociceptive response. Glibenclamide, a KATP channel blocker, pretreatment antagonized this response. Where as, in minoxidil pretreated animals, metoclopramide elicited an enhanced antinociceptive response. Glibenclamide and minoxidil, which are known KATP channel blocker and opener respectively, interfered with metoclopramide antinociception. These finding are suggestive of a role for KATP channels in metoclopramide antinociception in mice.

Endophytic colonization of rice by a diazotrophic strain of Serratia marcescens

Six closely related N2-fixing bacterial strains were isolated from surface-sterilized roots and stems of four different rice varieties. The strains were identified as Serratia marcescens by 16S rRNA gene analysis. One strain, IRBG500, chosen for further analysis showed acetylene reduction activity (ARA) only when inoculated into media containing low levels of fixed nitrogen (yeast extract). Diazotrophy of IRBG500 was confirmed by measurement of 15N2 incorporation and by sequence analysis of the PCR-amplified fragment of nifH. To examine its interaction with rice, strain IRBG500 was marked with gusA fused to a constitutive promoter, and the marked strain was inoculated onto rice seedlings under axenic conditions. At 3 days after inoculation, the roots showed blue staining, which was most intense at the points of lateral root emergence and at the root tip. At 6 days, the blue precipitate also appeared in the leaves and stems. More detailed studies using light and transmission electron microscopy combined with immunogold labeling confirmed that IRBG500 was endophytically established within roots, stems, and leaves. Large numbers of bacteria were observed within intercellular spaces, senescing root cortical cells, aerenchyma, and xylem vessels. They were not observed within intact host cells. Inoculation of IRBG500 resulted in a significant increase in root length and root dry weight but not in total N content of rice variety IR72. The inoculated plants showed ARA, but only when external carbon (e.g., malate, succinate, or sucrose) was added to the rooting medium.

NMR evidence for a short, strong hydrogen bond at the active site of a cholinesterase

Cholinesterases (ChE), use a Glu-His-Ser catalytic triad to enhance the nucleophilicity of the catalytic serine. It has been shown that serine proteases, which employ an Asp-His-Ser catalytic triad for optimal catalytic efficiency, decrease the hydrogen bonding distance between the Asp-His pair to form a short, strong hydrogen bond (SSHB) upon binding mechanism-based inhibitors, which form tetrahedral Ser-adducts, analogous to the tetrahedral intermediates in catalysis, or at low pH when the histidine is protonated [Cassidy, C. S., Lin, J., Frey, P. A. (1997) Biochemistry 36, 4576-4584]. Two types of mechanism-based inhibitors were bound to pure equine butyrylcholinesterase (BChE), a 364 kDa homotetramer, and the complexes were studied by (1)H NMR at 600 MHz and 25-37 degrees C. The downfield region of the (1)H NMR spectrum of free BChE at pH 7.5 showed a broad, weak, deshielded resonance with a chemical shift, delta = 16.1 ppm, ascribed to a small amount of the histidine-protonated form. Upon addition of a 3-fold excess of diethyl 4-nitrophenyl phosphate (paraoxon) and subsequent dealkylation, the broad 16.1 ppm resonance increased in intensity 4.7-fold, and yielded a D/H fractionation factor phi = 0.72+/-0.10 consistent with a SSHB between Glu and His of the catalytic triad. From an empirical correlation of delta with hydrogen-bond length in small crystalline compounds, the length of this SSBH is 2.64+/-0.04 A, in agreement with the length of 2.62+/-0.02 A independently obtained from phi. The addition of a 3-fold excess of m-(N,N, N-trimethylammonio)trifluoroacetophenone to BChE yielded no signal at 16.1 ppm, and a 640 Hz broad, highly deshielded proton resonance with a chemical shift delta = 18.1 ppm and a D/H fractionation factor phi = 0.63+/-0.10, also consistent with a SSHB. The length of this SSHB is calculated to be 2.62+/-0.04 A from delta and 2.59+/-0.03 A from phi. These NMR-derived distances agree with those found in the X-ray structures of the homologous acetylcholinesterase complexed with the same mechanism-based inhibitors, 2.60+/-0.22 and 2.66+/-0.28 A. However, the order of magnitude greater precision of the NMR-derived distances establish the presence of SSHBs. We suggest that ChEs achieve their remarkable catalytic power in ester hydrolysis, in part, due to the formation of a SSHB between Glu and His of the catalytic triad.

Pharmaco-economic analysis of psychotropic drugs

OBJECTIVES

To analyse cost and adverse reactions of psychotropic drugs for their cost-effective use.

METHODS

Four hundred and sixty nine psychotropic formulations from CIMS, June 1998 were evaluated for (a) extent of variation in retail price for same strength and dosage form, (b) role of number of companies manufacturing the same formulation and (c) companies pricing their product at price less than average of maximum and minimum price in relation to number of products marketed by them. The side effects of antipsychotic and antidepressant drugs were graded for their severity and cumulative side effects score. Side effect index and cost index were calculated on relative basis and their product was used as cost benefit index.

RESULTS

Fifty per cent of psychotropic drugs had less than 100% price variation with highest of 2049% for risperidone 4 mg tablets. A direct relationship existed between the drug cost and price variation wherever the variation crossed 200%. Similar trend was noticed between the minimum price variations and the number of companies marketing the product. There was no appreciable relationship between number of products marketed and pricing by the manufacturer. Cumulative side effect score was lowest (10) for trifluoperazine and pimozide and highest (15) for risperidone amongst antipsychotic drugs, whereas amongst antidepressants fluoxetine had lowest (1.75) and amitryptyline had highest (28.5) cumulative side effect score.

CONCLUSION

One has to be more careful while selecting a brand of a drug when price variation is more (200-2049%). Trifluoperazine (1.0) and fluoxetine (1.7) were found to be most economical with better cost benefit index compared to thioridazine (494.2) and clomipramine (113.0) in their respective groups. Thus our analysis provides basic information regarding cost effective therapy with psychotropic drugs.

Widespread occurrence of the homologues of the early nodulin (ENOD) genes in Oryza species and related grasses

Eighty accessions representing 23 species from the genus Oryza were examined for the presence of homologues of early nodulin (ENOD) genes. Southern analyses indicated a widespread distribution of homologues of ENOD genes across all the genomes of rice as well as other monocots. The degree of cross-hybridization of the legume ENOD genes with sequences in the genomes of various species, as revealed by hybridization differentials measured in terms of signal intensities, however, suggests that the homologues of ENOD genes are conserved to varied extents in different Oryza species. The presence of homologues of ENOD genes in a wide variety of plant species denotes that the biological functions of early nodulins may be diverse, and not restricted to nodule organogenesis alone. The fact that ENOD gene homologues exist widely both in dicots and monocots provides evidence that these homologues have arisen from a common ancestral plant.

Rice ENOD40: isolation and expression analysis in rice and transgenic soybean root nodules

The early nodulin ENOD40 has been proposed as playing a pivotal role in the organogenesis of legume root nodules. We have isolated the ENOD40 gene homologues ObENOD40 and OsENOD40 from the wild and cultivated rice genotypes Oryza brachyantha and Oryza sativa, respectively. Rice ENOD40s contain a sequence at the 5' end (region I) for encoding an oligopeptide that is highly conserved in all legume ENOD40s. Furthermore, at the 3' end (region II), the nucleotide sequence of rice ENOD40s exhibited a considerable homology to the corresponding region in legume ENOD40s. Among various organs of the rice plant, expression of OsENOD40 was detected only in stems. In situ hybridization studies revealed that, within the stem, transcription of OsENOD40 is confined to parenchyma cells surrounding the protoxylem during the early stages of development of lateral vascular bundles that conjoin an emerging leaf. Expression pattern of OsENOD40 promoter-GUS fusion in nodules developed on transgenic hairy roots of soybean was also found to be restricted to peripheral cells of nodule vascular bundles, thus evidencing that rice ENOD40 promoter activity is essentially the same as that of soybean ENOD40. Taken together, these results strongly suggest that OsENOD40 and legume ENOD40s share common, if not identical, functions in differentiation and/or function of vascular bundles.

Isolation, analysis and expression of homologues of the soybean early nodulin gene GmENOD93 (GmN93) from rice

Rice (Oryza sativa var. Nipponbare) possesses two different homologues of the soybean early nodulin gene GmENOD93 (GmN93). Analysis of the cDNA clones of rice homologues showed that OsENOD93a has an open reading frame (ORF) with a coding sequence homology of 58.2% to GmENOD93, whereas the ORF of OsENOD93b has displayed a homology of 42.3%. OsENOD93a and OsENOD93b genes are differentially expressed in different parts of the rice plant, as well as in cultured cells induced or non-induced with chitin oligomer. In intact rice tissues, OsENOD93b was most abundantly expressed in roots and at much lower levels in etiolated and green leaves, whereas the expression of OsENOD93a was very low in roots and etiolated leaves, and was not detected in green leaves. The level of OsENOD93a expression was enhanced markedly in suspension-cultured cells, whereas that of OsENOD93b did not increase. The application of chitin oligomer, an elicitor which induces a defence response in plants, did not significantly alter the expression of both these homologues in suspension cultures.

Chloride transport in primary cultures of rabbit colonocytes at different stages of development

BACKGROUND & AIMS

Ontogeny of colonic Cl- transport and its regulation has been characterized inadequately. The aim of this report was to study developmental changes in Cl- transport in primary cultures of rabbit distal colonocytes.

METHODS

Colonocytes from newborn (7-9 days old), weanling (25-28 days old), and adult (6 months old) rabbits were cultured for 24 hours on a collagen IV matrix, and Cl- transport was measured using the fluoroprobe 6-methoxyquinolyl acetoethyl ester.

RESULTS

Cl- permeabilities were dependent on [Cl-]o with maximal rates (in millimoles per liter per second) at [Cl-]o = 75 mmol/L (newborns; 0.15 +/- 0.04; weanlings; 0.2 +/- 0.02; and adults, 0.32 +/- 0.06). Influx was inhibited significantly by the Cl- channel (50 mumol/L diphenylamine-2-carboxylate) and the Na(+)-K(+)- 2Cl- cotransport (10 mumol/L furosemide) inhibitors. The adenosine 3',5'-cyclic monophosphate (cAMP)-dependent secretagogues, prostaglandin E1 (1 mumol/L), forskolin (1 mumol/L), and 8-bromo-cAMP (100 mumol/L), and the protein kinase C activator, phorbol 12-13 dibutyrate (1 mumol/L), increased Cl- influx significantly in all groups with adults showing greatest stimulation. However, taurodeoxycholate (0.025-1 mmol/L) had an effect only in the adult and the guanosine 3',5'-cyclic monophosphate (cGMP) activators STa and 8-bromo-cGMP had no effect.

CONCLUSIONS

Rabbit distal colonocytes possess inhibitor-sensitive Cl- permeabilities even in neonates. However, the ontogeny of their regulation depends on the secretagogue-signaling pathway.

Isolation and characterization of nucleolin gene as one of the vitamin A-responsive genes in airway epithelium by a palindromic primer-based mRNA differential display method

A palindromic primer-based mRNA differential display method has been used to isolate various vitamin A-responsive genes from primary cultures of monkey tracheobronchial epithelial cells. This method, as compared with the original mRNA differential display (mDD) method described by Liang and Pardee, used only one arbitrarily designed primer instead of two in the polymerase chain reaction. The single-primer mDD method has several advantages over the two-primer mDD system, especially in the reamplification and the selection of 5'-end cDNA clone. To verify the usefulness of this approach, one of these differential display bands, M34, was initially chosen for further amplification and cloning. The clone derived from the M34 band has a DNA sequence with > 90% homology to the human nucleolin gene. Furthermore, DNA sequencing confirms that both 5' and 3' ends of the insert of M34 contain the invertly repetitive nucleotide sequence that was used to direct this cloning. Nucleolin is a multifunctional phosphoprotein that plays an important role in ribosome biogenesis and mRNA stability. Northern blot analysis demonstrated that in addition to the elevation by vitamin A, the level of nucleolin message is significantly higher in fetal than in adult tracheobronchial epithelial cultures. Furthermore, in situ hybridization demonstrated that the amount of nucleolin message is significantly higher in both basal and ciliated cell types than in mucous and intermediary cell types. These results support the feasibility that the single-primer mDD technique can be used to isolate vitamin A-responsive genes with a palindromic nature.

Photodissimilation of Fructose to H(inf2) and CO(inf2) by a Dinitrogen-Fixing Cyanobacterium, Anabaena variabilis

The ability of cyanobacteria to serve as biocatalysts in the production of H(inf2) as a fuel and chemical feedstock was investigated with Anabaena variabilis. The results show that A. variabilis, when incubated under argon, dissimilated fructose to H(inf2) and CO(inf2) in a light-dependent reaction. The H(inf2) production had an obligate requirement for fructose and was heterocyst dependent, since NH(inf4)(sup+)-grown cultures lacking heterocysts failed to produce H(inf2). Differential inhibition studies with CO showed that nitrogenase is the main enzyme catalyzing the H(inf2) production. Net H(inf2) yield increased with increasing concentrations of fructose up to 10 mM in the medium. The average apparent conversion efficiency of fructose to H(inf2) (net H(inf2) produced/fructose removed from the medium) was about 10, although higher conversion efficiencies of 15 to 17 could be obtained during shorter periods and at optimum fructose concentrations. Under the same conditions, the ratio of CO(inf2) released to fructose removed from the medium was about 3.5, suggesting that only a fraction of the fructose carbon was completely oxidized to CO(inf2). Under conditions of carbon excess, which prevents H(inf2) uptake, the maximum ratio of H(inf2) to CO(inf2) was found to be 3.0. This is higher than the expected value of 2.0, indicating that water was also a source of reductant in this fructose-mediated H(inf2) production. Inhibition of H(inf2) evolution by 3-(3,4-dichlorophenyl)-1,1-dimethylurea confirmed a role for photosystem II in this process. The rate of H(inf2) production by A. variabilis SA1 was 46 ml h(sup-1) g (dry weight)(sup-1). This high rate was maintained for over 15 days. About 30% of this H(inf2) was derived from water (10 ml of H(inf2) h(sup-1) g [dry weight](sup-1)). These results show that filamentous, heterocystous cyanobacteria can serve as biocatalysts in the high-efficiency conversion of biomass-derived sugars to H(inf2) as a fuel source while simultaneously dissimilating water to H(inf2).

Altered growth and attachment of rabbit crypt colonocytes isolated from different developmental stages

The rabbit colon was used to establish an in vitro model for examining development-related cellular changes in colonocyte function. Colonic epithelia from newborn, weanling, and adult animals were separated from the muscle and subjected to enzymatic digestion. A mixture of 0.05% Pronase, 0.015% collagenase IV, and 0.023% DTT was determined to be optimal for the isolation of newborn and weanling colonocytes. This solution yielded significantly more cells and of greater viability than a 0.1% Pronase, 0.03% collagenase IV, 0.07% DTT mixture that is optimal for adult colonocytes. The epithelial origin of the colonocytes was confirmed by immunofluorescent staining of cytokeratins. The isolation procedure resulted in a crypt-enriched population and the cell yield/g of mucosa increased with age as did the crypt depth. Colonocyte viability of adults but not of newborns and weanlings, declined from 24 to 72 h. When grown on plastic, the newborn and weanling colonocytes show a approximately 2-fold increase in number, DNA and protein content over 48 h. In contrast, for all three parameters the adult colonocytes revealed only a approximately 10% increase. The colonocytes also showed an age-related decline in attachment to extracellular matrices. Colonocytes showed maximal attachment to Matrigel and collagen IV; newborn and weanling colonocytes show > 80% attachment, whereas adult colonocytes showed only a 45% attachment. The efficacy of attachment to Matrigel compared with that on plastic also differed with age, representing 9.3-, 5.5-, and 4.4-fold increase in adult, weanling, and newborn colonocytes, respectively. Newborn and weanling colonocytes grown on Matrigel for 48 h, showed a significant, 15% increase in cell number, DNA, and protein content compared with those grown on plastic. There was no difference in these parameters when adult colonocytes grown on Matrigel were compared with those grown on plastic. In summary, we have established an in vitro model for studying colonic epithelial cells at different stages of development.

Glutathione S-transferases in tracheobronchial epithelium

The purpose of this study is to characterize glutathione S-transferase (GST) gene expression in airway epithelium both in vivo and in vitro. Immunohistochemical staining of nonhuman primate lungs of well-controlled healthy animals reveals the presence of alpha- and pi-class GST isoenzymes in ciliated bronchial epithelium. The stain of mu-GST antibody is either very low or absent in some of these monkey lungs. We observed that primary tracheobronchial epithelial (TBE) cells isolated from human and monkey pulmonary tissues maintain a relatively high level of GST enzymatic activity in culture, compared with various immortalized human TBE cell lines and other nonpulmonary cell lines. Northern blot analysis demonstrated the presence of mu-, pi-, and microsomal-GST messages but not the alpha-class message in cultures of primary TBE cells as well as in various human TBE cell lines. The expression of mu- and pi-class GST genes can be further regulated in culture by various environmental factors; however, most of these regulating factors are associated with TBE cell differentiation in culture. For instance, vitamin A treatment, which was shown to enhance mucous cell differentiation in vitro, stimulated the message levels of mu- and pi-class GST. Furthermore, plating cells on collagen gel substrata, which also enhanced mucous cell differentiation in culture, instead of plastic culture surface, enhanced total GST enzymatic activity by eightfold, and this enhancement is related to an increase in the expression of the pi-class GST gene. These results demonstrated that GST genes are differentially expressed and regulated by various environmental factors in primary TBE cells and various cell lines, and the regulation is correlated to the mucous cell differentiation in culture.

Cypermethrin-induced in vivo alterations in the carbohydrate metabolism of freshwater fish, Labeo rohita

Aspects of carbohydrate metabolism under in vivo conditions were analyzed in functionally different tissues of the freshwater fish, Labeo rohita, exposed to a lethal (LC50/96 hr = 5.24 micrograms liter-1) and sublethal concentration (0.52 micrograms liter-1) of cypermethrin for 4 days. All exposed fish exhibited a hyperglycemic condition. An increase in tissue lactate with a decrease in pyruvate, total carbohydrates, and glycogen contents was noted. Activity of lactate dehydrogenase was elevated, indicating a shift toward anaerobiosis. TCA cycle enzymes, namely succinate dehydrogenase and malate dehydrogenase, were inhibited. In most cases changes were more pronounced during a lethal exposure compared to sublethal exposure period. The data indicate that the fish has adopted a compensatory mechanism to derive energy during pyrethroid toxicosis.

Alterations in protein metabolism in selected tissues of fish, Cyprinus carpio, during sublethal concentration of cypermethrin

Freshwater fish, Cyprinus carpio, were exposed to sublethal concentration of cypermethrin (20 µg/l) for 6, 12, 24 and 48 h to determine the protein fractions, amino acids, protease, alanine aminotransferase, aspartate aminotransferase, ammonia, urea and glutamine levels in gill, brain, liver and muscle tissues. Total, structural and soluble proteins showed decrement; whereas free amino acids and the activities of protease, aspartate aminotransferase and alanine aminotransferase significantly increased at all exposure periods in cypermethrin-exposed fish. Interestingly, ammonia content decreased but urea and glutamine levels increased in all the tissues during cypermethrin stress. It was observed that the changes steadily increased with an increase in the period of exposure and exhibited tissue specificity.

Genomic footprinting and sequencing of human beta-globin locus. Tissue specificity and cell line artifact

In order to gain further insights of the regulatory mechanisms of human beta-like globin gene switch during erythroid development, we have studied protein-DNA interaction in vivo at the human adult beta and fetal gamma globin promoters and their upstream enhancer, 5'HS-2, in purified human adult erythroblasts, in which the beta, but not gamma or epsilon, globin gene is actively transcribing. This genomic footprinting analysis of adult erythroblasts was carried out in conjunction with those of different non-erythroid human tissues, an embryonic/fetal erythroid cell line K562, and several non-erythroid human cell lines. Protein-DNA binding in the beta globin promoter, in particular at the two CACC promoter boxes and the CCAAT box, is detectable only in the adult erythroblasts. As expected, the gamma globin promoters were bound with specific nuclear factors in the expressing K562 cells, but not in non-erythroid tissues or cell lines. Relatively weak protein binding could also be detected in the vicinities of the two CCAAT boxes of the inactive gamma globin promoters in the adult erythroblasts. Although the patterns of nuclear factor-DNA interaction in vivo at the NF-E2/AP1, GATA-1, and GT-I motifs of 5'HS-2 enhancer in adult erythroblasts are similar to those in K562 cells, we have identified a previously undetected factor-binding motif of 5'HS-2 that is protected only in the adult erythroblasts. This motif is identical in sequence to the 3'-CACC box of the human beta globin promoter, and it is well conserved at the same location among all mammalian 5'HS-2 enhancers, suggesting an important regulatory role of this element in human beta globin gene transcription in adult erythroblasts. All of the above four motifs of 5'HS-2 are free of nuclear factor binding in non-erythroid tissues, but two of them, NF-E2/AP1 and GT-I, are bound with factors in some non-erythroid cell lines but not in others. The functional implications of these genomic footprinting data and the tissue-specific CpG methylation patterns of the beta-like globin promoters we obtained by genomic sequencing are discussed in terms of positive and negative regulation of the human beta-like globin switch during erythroid development.

Effect of thyroxine on DNA methyltransferase activity in cerebellum of rat

DNA methyltransferase activity increased significantly in cerebellum from day 4 to day 8 and decreased in 30 day old rats. It was maintained at lower levels in the adult rats. Thyroxine administration markedly stimulated DNA methyl- transferase activity in the newly born pups. However, it did not cause any effect on this enzyme activity in 8 day old rat cerebellum. These results show that thyroxine has a role in the regulation of DNA methyltransferase activity in cerebellum of rat during early stages of development.

Transcriptional activation of human zeta 2 globin promoter by the alpha globin regulatory element (HS-40): functional role of specific nuclear factor-DNA complexes

We studied the functional interaction between human embryonic zeta 2 globin promoter and the alpha globin regulatory element (HS-40) located 40 kb upstream of the zeta 2 globin gene. It was shown by transient expression assay that HS-40 behaved as an authentic enhancer for high-level zeta 2 globin promoter activity in K562 cells, an erythroid cell line of embryonic and/or fetal origin. Although sequences located between -559 and -88 of the zeta 2 globin gene were dispensable for its expression on enhancerless plasmids, they were required for the HS-40 enhancer-mediated activity of the zeta 2 globin promoter. Site-directed mutagenesis demonstrated that this HS-40 enhancer-zeta 2 globin promoter interaction is mediated by the two GATA-1 factor binding motifs located at -230 and -104, respectively. The functional domains of HS-40 were also mapped. Bal 31 deletion mapping data suggested that one GATA-1 motif, one GT motif, and two NF-E2/AP1 motifs together formed the functional core of HS-40 in the erythroid-specific activation of the zeta 2 globin promoter. Site-directed mutagenesis further demonstrated that the enhancer function of one of the two NF-E2/AP1 motifs of HS-40 is mediated through its binding to NF-E2 but not AP1 transcription factor. Finally, we did genomic footprinting of the HS-40 enhancer region in K562 cells, adult nucleated erythroblasts, and different nonerythroid cells. All sequence motifs within the functional core of HS-40, as mapped by transient expression analysis, appeared to bind a nuclear factor(s) in living K562 cells but not in nonerythroid cells. On the other hand, only one of the apparently nonfunctional sequence motifs was bound with factors in vivo. In comparison to K562, nucleated erythroblasts from adult human bone marrow exhibited a similar but nonidentical pattern of nuclear factor binding in vivo at the HS-40 region. These data suggest that transcriptional activation of human embryonic zeta 2 globin gene and the fetal/adult alpha globin genes is mediated by erythroid cell-specific and developmental stage-specific nuclear factor-DNA complexes which form at the enhancer (HS-40) and the globin promoters.

Erythroid differentiation of mouse erythroleukemia cells results in reorganization of protein-DNA complexes in the mouse beta maj globin promoter but not its distal enhancer

Dimethyl sulfoxide (DMSO) induction of mouse erythroleukemia (MEL) cells represents a well-defined in vitro system of terminal erythroid differentiation. We have studied the molecular mechanisms of transcriptional activation of the mouse beta maj globin gene during MEL cell differentiation by analyzing nuclear factor-DNA interactions in vivo at the gene's upstream promoter and a distal enhancer, 5'HS-2. Genomic footprinting data indicate that three motifs, CAC, NF-E2/AP1, and GATA-1, of the 5'HS-2 enhancer are bound with nuclear factors in MEL cells both prior to and after DMSO induction. No obvious conformational change of these nuclear factor-DNA complexes could be detected upon terminal differentiation of MEL cells. On the other hand, DMSO induction of MEL cells leads to the formation of specific nuclear factor-DNA complexes at several transcriptional regulatory elements of the mouse beta maj globin upstream promoter. Our genomic footprinting data have interesting implications with respect to the molecular mechanisms of transcriptional regulation and chromatin change of the mouse beta maj globin gene during erythroid differentiation.

Perturbations in nitrogen metabolic profiles in the tissues of fish, Labeo rohita exposed to fenvalerate

Changes in the levels of nitrogen metabolic profiles in gill, brain, liver and muscle tissues of fish, Labeo rohita exposed to sublethal concentration (10 micrograms/L) of fenvalerate for 6, 12, 24 and 48 hours were studied. Ammonia content was decreased, whereas urea and glutamine levels were increased in the tissues of fenvalerate exposed fish. Changes were more pronounced with an increase in the period of exposure. Within the tissues, the alterations in excretory products were in the following order: liver greater than muscle greater than brain greater than gill. The survivability of fish in the polluted habitats might be due to the operation of compensatory mechanism in the metabolic profiles such as detoxification and transamination of more toxic ammonia by conversion to less toxic compounds like urea and glutamine.

Protein-DNA interactions in vivo of an erythroid-specific, human beta-globin locus enhancer

The 5' DNase I-hypersensitive site 2 (5' HS-2) is an erythroid-specific enhancer located 11 kilobases (kb) upstream of the human beta-globin gene cluster. Presence in cis of 5' HS-2 confers a high level of erythroid cell-specific and developmentally regulated promoter activities of human globin genes in transfected cell cultures and in transgenic mice. Combining the use of the methylation protection assay and polymerase chain reaction, we have studied nuclear factor-DNA interactions of the 5' HS-2 enhancer in vitro and in vivo. The data from analyses of three different sequence motifs within 5' HS-2 represent three different modes of protein-DNA interaction with respect to cell-type specificities and in vivo vs. in vitro differences. First, a GATA-1 motif was found to bind nuclear factor(s), presumably the GATA-1 factor, present in K-562 cell extracts and in living K-562 cells. No such binding was seen in nonerythroid HeLa cells or extract. A second motif, NF-E2/AP1 (nuclear factor-erythroid 2/activator protein 1), consists of tandemly arranged dimers of AP1 binding consensus. The presence of either HeLa extract or K-562 extract protects the NF-E2/AP1 motif from methylation, but the footprints are different. This is most likely due to different protein-DNA contacts of the AP1-DNA complex formed in HeLa extract and the NF-E2-DNA complex in K-562 extract. In vivo methylation protection patterns of this motif parallel those observed in vitro, suggesting that it is also bound by NF-E2 in K-562 cells and by AP1 in HeLa cells. Finally, a GT-I motif binds apparently to one or more similar factors in both types of nuclear extracts, but the in vivo methylation protection patterns are not identical between living HeLa and K-562 cells. These data provide direct evidence that specific nuclear factor-DNA complexes form in vivo at functionally important sequence motifs of the 5' HS-2 enhancer in erythroid cells. The detection of conformationally different nuclear factor-DNA complexes at the same sequence motifs in HeLa and Raji cell lines also raises interesting questions regarding the origin and function of these complexes in nonerythroid cells.

Changes in the carbohydrate metabolism in the selected tissues of Mus booduga gray after BHC treatment

Adult mice, Mus booduga were fed orally with bennzenehexachloride (BHC) at a dose of 50 mg/kg body weight every day for 1, 5 and 15 days. Significant decrease in the pyruvate content was observed at all periods of treatment. In support of this increase in lactate content and lactate dehydrogenase (LDH) activity was noticed in all the three tissues. Enzymes of TCA cycle namely isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) were inhibited suggesting abnormality in mitochondrial oxidative metabolism as a consequence of BHC toxicity.

Fenvalerate induced biochemical changes in the selected tissues of freshwater fish, Cyprinus carpio

Alterations in the levels of some biochemical and enzymological parameters in brain, liver and muscle tissues of Cyprinus carpio exposed to sublethal concentration (10 micrograms/liter) of fenvalerate for 6, 12, 24 and 48 hr were studied. Total, structural and soluble proteins were decreased, whereas the free amino acids and the activities of protease, aspartate aminotransferase and alanine aminotransferase significantly increased in fenvalerate exposed fish. It is also observed that the changes were more pronounced with an increase in the period of exposure. Within the tissues, the alterations in biochemical and enzymological parameters was in the following order: liver greater than brain greater than muscle. The possible roles of fenvalerate induced changes in the fish are discussed.

Inhibition of Mg2+ and Na(+)-K+ ATPases in selected tissues of fish, Cyprinus carpio under fenvalerate toxicity

The changes in the magnesium adenosine triphosphatase (Mg2+ ATPase) and sodium-potassium adenosine triphosphatase (Na(+)-K+ ATPase) in gill, brain, liver and muscle tissues of freshwater fish, Cyprinus carpio at 6, 12, 24 and 48 hr exposure periods were studied after subjecting to sublethal concentration (10 micrograms/lit) of fenvalerate. Mg2+ ATPase and Na(+)-K+ ATPase activities were inhibited in all the tissues of fenvalerate exposed fish. The per cent inhibition increased with increase in the period of exposure and the possible reasons for the inhibition patterns are discussed.

Effect of prolactin on DNA methylation in the liver and kidney of rat

Prolactin is an important growth modulatory hormone in fetal and adult tissues. It stimulates DNA synthesis and enzymatic markers of the G1 phase of cell cycle in rat liver and other tissues. In this study the effects of prolactin on 5-methyl cytosine content in liver and kidney of rats was studied using HPLC. Prolactin treatment caused hypomethylation of DNA in the liver and kidney of immature rats at 48 h after treatment and the effect remained even at 72 h. Prolactin also caused hypomethylation of DNA in the kidney and liver of adult rats at 48 h after treatment. These results indicate that prolactin probably regulates DNA methylation in the liver and kidney of immature and adult rats.

Differential regulation of DNA methylation in rat testis and its regulation by gonadotropic hormones

Eukaryotic DNA methylation occurs exclusively at the 5'-position of cytosine and has been implicated in the regulation of gene expression. Using high-performance liquid chromatography, the methylation of testis DNA during its development, in different cell populations and during regulation by gonadotropic hormones, were studied. The 5-mC content of testis DNA increased significantly from days 30 to days 150, while in 2-yr-old testis 5-mC content decreased significantly. Among various populations of testicular cells, pachytene spermatocyte DNA contained a significantly high amount of 5-mC when compared to spermatogonia, spermatids and mature sperm DNA. However, the 5-mC content of elongated spermatids was significantly less when compared to the above four fractions. Administration of follicle stimulating hormone to immature rats caused hypomethylation of seminiferous tubular DNA while luteinizing hormone caused similar effects in Leydig cells. These results indicate that in testis, DNA methylation is differentially regulated during development and is controlled by gonadotropic hormones.

A novel method to produce Anabaena-free Azolla by in vitro fertilization of micromanipulated megasporocarps

In the Azolla-Anabaena azollae symbiotic system, Anabaena akinetes get entrapped between the indusium and the apical cap of the megaspore apparatus during megasporocarp development, thus maintaining the continuity of the cyanobacterial association throughout the life cycle of the fern. The entrapped akinetes serve as the source of inoculum for infecting the new sporophyte when it is emerging from the megaspore apparatus. A procedure to generate Anabaena-free Azolla was developed by fertilizing the germinating megasporocarps in which the indusium along with the akinetes were removed by micromanipulation. This method has the advantage of not requiring drastic treatments of Azolla with antibiotics to eliminate the endosymbiotic cyanobacterial cells. Details of this new method and its usefulness in studies aimed at recombination of Azolla with Anabaena azollae are discussed.

Funding group benefit programs

These authors examine various ways to fund group benefit plans. They devote special attention to self-funding of health care coverage.

Regulation of DNA methyltransferase in the testis of rat

In mammalian DNA, the base 5-methylcytosine is generated by post-replicational methylation of cytosine residue by DNA methyltransferase. In this study the levels of DNA methyltransferase of testis during various ages and the effects of gonadotropic hormones on immature rat testis were studied. It was observed that the specific activity of DNA methyltransferase was high in the testis at the age of 20 and 30 days. After this age, the activity of DNA methyltransferase declined significantly and was maintained at lower level from days 120 to 240. Treatment with follicle stimulating hormone significantly decreased the enzyme activity in the testis while luteinizing hormone did not cause any effect. These results indicate that DNA methyltransferase of certain cells in the testis is under the influence of follicle stimulating hormone.

Preparation of oligodeoxyribonucleoside methylphosphonates on a polystyrene support

An efficient procedure is described for synthesizing deoxyribonucleoside methylphosphonates on polystyrene polymer supports which involves condensing 5'-dimethoxytrityldeoxynucleoside 3'-methylphosphonates. The oligomers are removed from the support and the base protecting groups hydrolyzed by treatment with ethylenediamine in ethanol, which avoids hydrolysis of the methylphosphonate linkages. Two types of oligomers were synthesized: those containing only methylphosphonate linkages, d-Np(Np)nN, and those which terminate with a 5' nucleotide residue, dNp (Np)nN. The latter oligomers can be phosphorylated by polynucleotide kinase, and are separated by polyacrylamide gel electrophoresis according to their chain length. Piperdine randomly cleaves the oligomer methylphosphonate linkages and generates a series of shorter oligomers whose number corresponds to the length of the original oligomer. Apurinic sites introduced by acid treatment spontaneously hydrolyze to give oligomers which terminate with free 3' and 5' OH groups. These reactions may be used to characterize the oligomers.

Use of methylphosphonic dichloride for the synthesis of oligonucleoside methylphosphonates

Methylphosphonic dichloride was used to prepare protected deoxyribonucleoside 3'-methylphosphonate beta-cyanoethyl esters, d-[(MeO)2Tr]NpCNEt, and protected oligonucleoside methylphosphonates in solution. Reaction of d-[(MeO)2Tr]N with methylphosphonic dichloride gives d-[(MeO)2Tr]NpCl. The phosphonylation and subsequent esterification or condensation reactions are each complete within 60 min. The products are readily purified by "flash chromatography" on silica gel columns. d-[(MeO)2Tr]NpCl, or its tetrazole derivative, d-[(MeO)2Tr]Nptet, were tested as intermediates for the synthesis of oligothymidine methylphosphonates on a silica gel polymer support. The average yield per coupling step was 76% and did not increase with addition of more d-[(MeO)2Tr]TpCl. The formation of (5'-5') linked thymidine dimers indicated that the thymidine monomers are clustered closely together on the support. When N is ibuG, the yield for the coupling step on the support is very low. This may be due to steric hindrance of the 3'-phosphonate group by the N-2 isobutryl protecting group.

Reappraisal of intracutaneous tests in the diagnosis of reaginic allergy

In an attempt to determine the clinical relevance of positive intracutaneous tests when epicutaneous tests are negative, 34 patients with symptoms of perennial rhinitis who had negative epicutaneous but positive intracutaneous tests were evaluated by radioallergosorbent (RAST) test, nasal provocation (NP) tests and leukocyte histamine release (LHR) assay. Nineteen patients with perennial rhinitis who had positive epicutaneous tests and 13 normal healthy volunteers were also studied as positive and negative controls, respectively. None of the 34 patients with negative epicutaneous but positive intracutaneous tests had positive RASTs or LHR assays, but 1 patient had a positive NP test. In contrast, of the 19 patients with positive epicutaneous tests, 12 patients had positive RASTs, 17 had positive LHR assays, and 17 had positive NP tests. In the negative control group of 13 subjects, none had positive RAST, LHR assays, or NP tests, although 3 subjects showed positive intracutaneous tests. These results indicate that when epicutaneous tests are negative in patients with perennial rhinitis, positive intracutaneous tests are not likely to indicate the presence of reaginic allergy.

Agreement between radioallergosorbent test and skin test

A total of 4,260 RAST results were compared with the same number of prick and intracutaneous skin test results. Intracutaneous test was done only when the prick test was negative. The mean agreement between positive RAST and positive prick test was 81.3% for five grasses, 45.1% for seven weeds, 42.2% for two trees, 42.6% for two molds, and 45.8% for two environmental antigens. The mean agreement between positive RAST and positive intracutaneous test ranged from 0 to 4.9% for the same antigens.

Lymphocyte response to grass pollen antigens: a correlation with radioallergosorbent test and effect of immunotherapy

The deoxyribonucleic acid (DNA) synthetic response of cultured lymphocytes to grass pollen antigens was significantly higher in 66 untreated atopic patients than in 15 non-atopic subjects (p less than 0.05). There was no correlation between the DNA synthetic response and the specific IgE antibody level as measured by radioallergosorbent test in the 81 subjects (r= 0.13; p greater than 0.2). The effect of immunotherapy on proliferative lymphocyte response and specific IgE antibody response to grass pollen antigens was evaluated prospectively in 22 atopic patients. The DNA synthetic response to grass pollen antigens was significantly reduced after immunotherapy (p less than 0.01) but the specific IgE antibody level did not change significantly.

Tropical splenomegaly, sickle-cell trait, and P. falciparum infection

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