The cytogenetic effect of products of cytosine radiolysis: Isobarbituric acid and dialuric acid

The cytogenetic effect of two radiolytic cytosine products, i.e. of isobarbituric acid and of dialuric acid has been studied on a system of resting meristem ofVicia faba L. on chromosomal level. Both compounds produced in a concentration 10^-3 and 10^-4 M chromosomal aberrations with a relatively low frequency, about 4 aberrations per 100 anaphases after 12 h of treatment. Among the aberration types chromosomal and chromatid breaks and minutes pre-dominated.     

Antagonistic effects of Satureja hortensis essential oil against AFB,on human lymphocytes in vitro

Satureja hortensis L. (Lamiaceae) has been used as a folk remedy to treat various such as cramps, muscle pains, nausea, indigestion, diarrhea, and infectious diseases. In this study, the antagonistic effects of essential oil of S. hortensis (SHE) were studied against aflatoxin B₁ (AFB₁) in human lymphocytes in vitro. The analysis of the essential oil was performed by using Gas chromatography-mass spectrometry (GC-MS). Anti-genotoxic effects of the SHEs was evaluated using sister chromatid exchange (SCE), micronuclei (MN) tests against AFB1. Also level of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities used to determine the anti-oxidative effects of the SHEs. This result showed AFB₁ (5 μM) increased the frequencies of SCE, MN and the level of MDA. AFB1 at the same concentration decreased the activities of SOD and GPx. However, different concentrations of SHE with AFB¹ decreased the frequency of SCE and MN and level of MDA and also increased the activities of SOD and GPx significantly. Especially, the 1.0, 1.5, 2.0 μL dose of SHE are more effective than other doses. The results of this experiment have clearly shown that SHE has strong antioxidative and antigenotoxic effects, these biological activities of SHEs can be due to its component.     

Comparison of the effects of radiation and deoxyribonucleic acids on the mitosis in roots ofVicia faba

Differences as well as similarities in the action of ionizing radiation and deoxyribonucleic acids from various sources on mitosis in root cells ofVicia faba were established. The time course of occurrence of aberrations were examined. Whereas in irradiated broad beant the maximum percentage of aberrations was observed immediately after irradiation, the aps plication of non-isologous DNA was followed by maximum aberrations after 8–16 hours. As all the time-intervals studied, an incraasad number of aberrations was found during metaphase-as compared with anaphases, both after irradiation and after application of DNA. A comparison of isologous, homologous and heterologous DNA as inductors of chromosomal aberrations supported our previous findings and showed that the efficiency of DNA depends on the genetic difference between donor and acceptor. During a study of distribution of aberrations between large and small chromosomes of meristematic cells ofVicia faba, at various time-intervals it was obsarved that after irradiation the distribution of aberrations between individual chromosomes is proportional to their total length, whereas the effect of heterologous DNA is mostly in the damage to small chromosomes. It was also found that aftar irradiation mostly chromatid aberrations are formed at shorter time-intervals and only later chromosomal aberrations will appear. On the other hand, heterologous DNA brings about in all time-intervals a predominance of chromatid aberrations.     

Catalytic Pyrolysis of Raw and Thermally Treated Cellulose Using Different Acidic Zeolites

Fast pyrolysis of biomass using zeolite catalyst has shown to be effective in improving aromatic production. This study focuses on aromatic production through catalytic pyrolysis of major biomass constituent i.e., cellulose. Furthermore, cellulose was torrefied to understand torrefaction’s effect on pyrolysis products. The influence of SiO₂/Al₂O₃ ratios of zeolite (ZSM-5) catalyst on aromatic production during pyrolysis of raw and torrefied cellulose was investigated. Results showed that the catalyst acidity played a pivotal role in eliminating anhydro sugars and other oxygenated compounds while producing more aromatics. The maximum aromatic yield (~25 wt%) was obtained when ZSM-5 with the highest acidity (SiO₂/Al₂O₃?=?30) was used, while the lowest yield (7.99 wt%) was obtained when the least acidic catalyst was used (SiO₂/Al₂O₃?=?280) for raw cellulose pyrolysis. Torrefaction process showed to have positive effect on the aromatic production from pyrolysis. There were no aromatics produced from pyrolysis of raw cellulose in the absence of catalyst, whereas significant amount of aromatic compounds were produced from both catalytic and noncatalytic pyrolyses of torrefied cellulose. The aromatic hydrocarbons produced from catalytic pyrolysis of torrefied cellulose were 5 % more than those produced from raw cellulose at the highest temperature and catalyst acidity (SiO₂/Al₂O₃?=?30).     

Growth requirements of blue-green algae under blue light conditions

1. Growth requirements of blue-green algae containing only the c-phycocyanin + chlorophyll a pigment system have been studied under blue light (380–540 nm) which approximates light conditions existing in subsurface waters in nature.
2. While a few species were capable of very slow photosynthetic growth on minimal medium with NO₃ ^- as nitrogen source, most species were dependent on organic compounds for comparable growth under this condition. Some organisms did quite well with only Casamino Acids as a supplement, others did well with only glucose. One species, Agmenellum quadruplicatum strain PR-6, grew only when glucose and Casamino Acids were supplied simultaneously.
3. Inhibitory effects of blue light on CO₂ fixation and nitrogen metabolism are noted as possible explanations of these responses.

     

Drosophila lactate dehydrogenase: Molecular and genetic aspects

(LDH) obtained from larvae of Drosophila melanogaster was purified to homogeneity by affinity chromatography on oxamate-Sepharose. The purification procedure is simple to operate and gives a homogeneous preparation in a good yield (34.86%) after only two steps. Utilizing the homogeneous LDH preparation, an attempt was made to characterize the LDH molecule. Thus, it was found that the N-terminal amino acid is isoleucine, and the enzyme is tetrameric and composed of four identical subunits of apparent molecular weight 38,000, suggesting that it is controlled by a single gene. Homogeneous LDH preparations exhibit one band on neutral acrylamide gels when the substrate is either dl-lactic acid or l-(+)-lactate. The optimum temperature is 45°C for the purified enzyme and 40°C for the crude homogenate. The K _m values for pyruvate and NADH are 0.154 and 0.027mm, respectively, while the K _m values for lactate and NAD are 29.4 and 1.33mm, respectively. A discontinuity in the E _a slope was observed at a transition temperature of 30°C. The E _a value between 20 and 30°C was calculated as 12.06 kcal/mol, while between 30 and 45°C the E _a value was 4.01 kcal/mol. This evidence, together with other observations reported in the literature, suggests that the LDHs of invertebrates and vertebrates have arisen by divergent evolution from a common ancestral gene.     

The complete primary structure of pilin fromHaemophilus influenzae type b strain Eagan

Adherence ofHaemophilus influenzae type b (Hib) to human oropharyngeal cells is mediated by pili which are proteinaceous filaments that extend outward from the bacterial cell surface. Pili from Hib strain Eagan were purified, and the primary structure of the major subunit, pilin, was determined. Sequencing of overlapping peptides showed the mature protein to be comprised of 196 amino acids and to have an M_r of 21,152. The amino terminal sequence was found to be homologous with the sequence previously reported for Hib strain M43 and also to have significant homology to pilins of other gram-negative pathogenic bacteria. Furthermore, Hib pilin had two cysteinyl residues in the amino terminal portion of the protein which were separated by 40 residues (positions 21 and 61); a motif found in other bacterial pilins. The data show that Hib pilin has structural features common to other bacterial pilins.     

Giemsa technique for the detection of sister chromatid exchanges

Sister chromatid exchanges are sharply demarcated in Giemsa stained metaphase preparations of Chinese hamster ovary cells and human peripheral leukocytes. Chromatids singly and doubly substituted with BrdU acquire differential Giemsa stain affinities after treatment at 88° C for 10 minutes in 1.0 M Na phosphate buffer (pH 8.0).     

The GABAA Antagonist DPP-4-PIOL Selectively Antagonises Tonic over Phasic GABAergic Currents in Dentate Gyrus Granule Cells

GABA_A receptors mediate two different types of inhibitory currents: phasic inhibitory currents when rapid and brief presynaptic GABA release activates postsynaptic GABA_A receptors and tonic inhibitory currents generated by low extrasynaptic GABA levels, persistently activating extrasynaptic GABA_A receptors. The two inhibitory current types are mediated by different subpopulations of GABA_A receptors with diverse pharmacological profiles. Selective antagonism of tonic currents is of special interest as excessive tonic inhibition post-stroke has severe pathological consequences. Here we demonstrate that phasic and tonic GABA_A receptor currents can be selectively inhibited by the antagonists SR 95531 and the 4-PIOL derivative, 4-(3,3-diphenylpropyl)-5-(4-piperidyl)-3-isoxazolol hydrobromide (DPP-4-PIOL), respectively. In dentate gyrus granule cells, SR 95531 was found approximately 4 times as potent inhibiting phasic currents compared to tonic currents (IC₅₀ values: 101 vs. 427 nM). Conversely, DPP-4-PIOL was estimated to be more than 20 times as potent inhibiting tonic current compared to phasic current (IC₅₀ values: 0.87 vs. 21.3 nM). Consequently, we were able to impose a pronounced reduction in tonic GABA mediated current (>70 %) by concentrations of DPP-4-PIOL, at which no significant effect on the phasic current was seen. Our findings demonstrate that selective inhibition of GABA mediated tonic current is possible, when targeting a subpopulation of GABA_A receptors located extrasynaptically using the antagonist, DPP-4-PIOL.     

Kinetic and stoichiometric characterization for efficient enhanced biological phosphorus removal (EBPR) process at high temperatures

A recently reported stable and efficient EBPR system at high temperatures around 30 °C has led to characterization of kinetic and stoichiometric parameters of the Activated Sludge Model no. 2d (ASM2d). Firstly, suitable model parameters were selected by identifiability analysis. Next, the model was calibrated and validated. ASM2d was found to represent the processes well at 28 and 32 °C except in polyhyroxyalkanoate (PHA) accumulation of the latter. The values of the kinetic parameters for PHA storage (q _PHA), polyphosphate storage (q _PP) and growth (μ _PAO) of polyphosphate-accumulating organisms (PAOs) at 28 and 32 °C were found to be much higher than those reported by previous studies. Besides, the value of the stoichiometric parameter for the requirement of polyphosphate for PHA storage (Y _PO4) was found to decrease as temperature rose from 28 to 32 °C. Values of two other stoichiometric parameters, i.e. the growth yield of heterotrophic organisms (Y _H) and PAOs (Y _PAO), were high at both temperatures. These calibrated parameters imply that the extremely active PAOs of the study were able to store PHA, store polyphosphate and even utilize PHA for cell growth. Besides, the parameters do not follow the Arrhenius correlation due to the previously reported unique microbial clade at 28 and 32 °C, which actively performs EBPR at high temperatures.     

Pharmacological Identification of a Guanidine-Containing β-Alanine Analogue with Low Micromolar Potency and Selectivity for the Betaine/GABA Transporter 1 (BGT1)

The γ-aminobutyric acid (GABA) transporters (GATs) are key membrane transporter proteins involved in the termination of GABAergic signaling at synapses in the mammalian brain and proposed drug targets in neurological disorders such as epilepsy. To date, four different GAT subtypes have been identified: GAT1, GAT2, GAT3 and the betaine/GABA transporter 1 (BGT1). Owing to the lack of potent and subtype selective inhibitors of the non-GAT1 GABA transporters, the physiological role and therapeutic potential of these transporters remain to be fully understood. Based on bioisosteric replacement of the amino group in β-alanine or GABA, a series of compounds was generated, and their pharmacological activity assessed at human GAT subtypes. Using a cell-based [³H]GABA uptake assay, several selective inhibitors at human BGT1 were identified. The guanidine-containing compound 9 (2-amino-1,4,5,6-tetrahydropyrimidine-5-carboxylic acid hydrochloride) displayed more than 250 times greater potency than the parent compound β-alanine at BGT1 and is thus the most potent inhibitor reported to date for this subtype (IC₅₀ value of 2.5 µM). In addition, compound 9 displayed about 400, 16 and 40 times lower inhibitory potency at GAT1, GAT2 and GAT3, respectively. Compound 9 was shown to be a substrate for BGT1 and to have an overall similar pharmacological profile at the mouse orthologue. Compound 9 constitutes an interesting pharmacological tool for specifically investigating the cellular pharmacology of BGT1 and is the first small-molecule substrate identified with such a high selectivity for BGT1 over the three other GAT subtypes.     

Broadband Reflection Minimization Using Silver Ultra Thin Film Sandwiched Between Silicon Nitride Layers for c-Si Solar Cell Application

Wafer thickness reduction is the main trend for cost reduction of crystalline silicon (c-Si) solar cells. For better light trapping in lower thickness wafers where traditional texturization method may not be promising, alternative techniques are being explored. Here, reflection minimization using silver ultra thin film sandwiched between silicon nitride (SiN_x) antireflection coating (ARC) layers on c-Si substrate is reported. SiN_x ARC layers were deposited by plasma-enhanced chemical vapor deposition (PECVD) and silver ultra thin film by e-beam evaporation; 41 % reflection reduction for silver ultra thin film sandwiched in SiN_x ARC layers as compared to standard 80 nm thin SiN_x ARC on c-Si substrate is shown. The sandwiched structure gives 8.1 % weighted total reflectance for wavelength range of 300–1,200 nm as compared to standard 80-nm SiN_x-based ARC which gives 13.8 %. Also, comparison of this Ag ultra thin film-based sandwiched geometry is done with randomly distributed nanoparticle (NP)-based ARC geometry. It is shown that optically, the sandwiched Ag ultra thin film-based device geometry is more promising than Ag NP-based device geometry and standard 80-nm SiN_x-based geometry for broad wavelength range of 300–1,200 nm.     

Comparisons of procedures for determining ribosomal ribonucleic acid similarities

Ribosomal ribonucleic acid (rRNA) cistron similarities were determined forClostridium species with labeled preparations of 16S, 23S, or 16S plus 23S rRNA. Similarities were measured by membrane competition and by thermal stability experiments, and the results were correlated. Correlations were also made between 16S rRNA membrane competition homology values and similarities of 16S rRNA oligonucleotides. Very similar results were obtained whether 16S-or 23S-labeled rRNA was used. Clustering patterns were similar for homology values from hybridization experiments incubated at 50° or 60°C, as were the clustering patterns comparing homology values and rRNA hybrid thermal stability values. There was a linear correlation between rRNA homology values and 16S oligonucleotide S_AB values (Tanner et al. [22]) for homology values above 20%, and S_AB values above 0.45.     

Genetic basis for the polymorphism of rat liver cytosolic aldehyde dehydrogenase

Liver aldehyde dehydrogenase (ALDH), the enzyme involved in the oxidation of aldehydes such as acetaldehyde derived from ethanol, exists in multiple forms in most mammals. Up to five separable forms have been identified from the cytosolic fraction of Wistar rat liver. We investigated the genetic basis of a particular set of three enzyme forms by selective breeding and analysis of electrophoretic patterns of liver ALDH by isoelectric focusing. The forms of liver ALDH investigated were at pI 5.8 or 6.2, or a triple form with enzymes at pI 5.8, 6.0, and 6.2. There are two alleles found at the ALDH locus which encode in homozygotes for one of two electrophoretically separable ALDH forms. A rat heterozygous at the locus forms both ALDH types plus a hybrid. The alleles are expressed codominantly, found at an autosomal locus, and remain constant postpartum. The activities associated with the triplet enzyme form were statistically indistinguishable from a 1:2:1 ratio. This suggests that the enzymes hybridize to form a set of dimers or tetramers of the form A₂, AB, B₂ or A₄, A₂B₂, B₄, respectively.     

Gibberellic-acid-regulated expression of α-amylase and six other genes in wheat aleurone layers

The effect of gibberellic acid (GA₃) on gene expression in wheat aleurone cells has been characterised. In-vitro translation of polyadenylated RNA indicated that α-amylase and other messenger-RNA (mRNA) species increase in relative concentration in GA₃-treated tissue. At least one mRNA species declines in relative level in response to GA₃. There is also a GA₃-dependent, four-fold increase in the level of polyadenylated RNA. This effect is largely the result of increased levels of many mRNA species which are also present in untreated tissue. Seven GA₃-induced polyadenylated RNA species including the Amyl α-amylase gene product have been cloned as complementary DNA in the plasmid pBR322. These cloned DNAs have been used as hybridisation probes to show that the GA₃-induced increase in α-amylase mRNA is more prolonged than the accumulation of the other GA₃-regulated mRNA species. A polyadenylated-RNA sequence showing reduced concentration in GA₃-treated tissue has also been cloned.     

Plasmonic Property and Stability of Core-Shell Au@SiO2 Nanostructures

Au nanorod (Au NR) is one of the most studied colloidal nanostructures for its tunable longitudinal surface plasmon resonance (SPR_L) property in the near infrared region. And surface coating Au NRs into core-shell nanostructures is particularly important for further investigation and possible applications. In this paper, Au NRs colloids were synthesized using an improved seed method. Then as-prepared Au NRs were coated with SiO₂ to form a core-shell nanostructure (Au@SiO₂) with different shell thickness. And the influence of SiO₂ shell on the SPR_L of Au NRs was investigated based on the experimental results and FDTD simulations. Under the 808 nm laser irradiating, the stability of Au@SiO₂ was studied. Compared with Au NRs, the Au@SiO₂ is stable with increasing laser power (up to 8 W), whereas Au NRs undergo a shape deformation from rod to spherical nanoparticle when the laser power is 5 W. The high stability and tunable optical properties of core-shell structured Au@SiO₂, along with advantages of SiO₂, show that Au@SiO₂ composites are promising in designing plasmonic photothermal properties or further applications in nanomedicine.     

Clusters of nonsolvent water in partially destroyed Saccharomyces cerevisiae yeast cells

The state of water in partially destroyed dry yeast cells has been studied using low-temperature ¹H NMR spectroscopy. It has been shown that the residual water is in the form of clusters of strongly and weakly associated water (SAW and WAW, respectively). Three or more types of SAW different in the chemical shift values have been found. It has been established that the interfacial water poorly dissolves hydrochloric and trifluoroacetic acids as well as DMSO and CD₃CN. Hydrochloric acid on a surface of biomaterials can be separated into HCl and water. This process is stabilized by polar co-solvents (DMSO and CD₃CN) added to the CDCl₃ dispersion medium.     

Influence of the shear stress and salinity on Anammox biofilms formation: modelling results

Anammox biomass has a long duplication time and low yield, thus the process must be operated in reactors with good sludge retention, such as biofilm systems. Therefore, it would be important to research the ability of Anammox biomass to form biofilms under different conditions. The effects of shear stress and salinity (NaCl and CaCl₂) on Anammox biofilm formation were studied. Anammox bacteria showed good attachment capacity, with an initial adhesion phase lasting for 5–7 days at the different flow rates tested (Reynolds numbers 54, 63, 188 and 400). A four-parameter model was developed and the experimental data fitted well into the model. The presence of 5 g/L of each of the two salts favoured the formation of Anammox biofilm. The effects of CaCl₂ were stronger than those caused by NaCl. 15 g/L of NaCl was detrimental for the biofilm, probably due to an inhibitory effect.