bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of nitrate uptake and nitrite efflux in the cyanobacterium Nostoc MAC
Authors: Singh B. B. , Pandey P. K. , Singh S. , Bisen P. S. 
Published: February 2007

AbstractNitrate uptake, nitrite efflux and their regulation have been studied in the cyanobacterium Nostoc MAC. Nitrate uptake as well as nitrite‐assimilation‐dependent nitrite efflux systems consisted of two distinct phases comprising an initial rapid phase followed by a slower one. Whereas, 3‐(3,4‐dichlorophenyl)‐1‐1 dimethyl urea (DCMU), an inhibitor of photosystem II inhibited both nitrate uptake and nitrite efflux significantly, exogenous supply of ATP, however, stimulated both the processes, suggesting that PS II‐mediated energy generation plays vital role in regulating both nitrate uptake as well as nitrite efflux. The inhibition of both the processes by p‐chloromercuribenzoate (pCMB)1, N,N dicyclohexylcarbodiimide (DCCD) and carbonyl cyanide‐m‐chlorophenyl hydrazone (CCCP) indicated the involvement of ‐SH groups and ATP hydrolysis in the regulation of both the processes. Tungstate‐treated cells having nonfunctional nitrate reductase although had a significant level of nitrate uptake, yet nitrite efflux by these cells was found to be negligible. These results suggest that (i) nitrate uptake and nitrite efflux processes in Nostoc MAC are energy‐dependent; (ii) assimilation of nitrate via nitrate reductase is necessarily required for nitrite efflux to occur; (iii) nitrate uptake and nitrite efflux processes are regulated at different levels by different metabolic inhibitors; and (iv) cations of larger ionic radius facilitate the nitrate uptake and nitrite efflux processes.
Different restriction profiles of χ prophage in Serratia marcescens K and HY
Authors: Steiger H. , Kimpel E. , Mohasseb‐Karimlou B. 
Published: February 2007

AbstractTemperate phage χ originated from the defectively lysogenic Serratia marcescens strain K, from where it was liberated after uv irradiation with low efficiency. The phage is usually indicated on strain HY that can be easily lysogenized by it and rather efficiently uv‐induced. Comparing the Eco RI restriction profiles of the χ prophage in HY revealed a DNA rearrangement, by which the precursor structure in K is converted into the non‐defective form. Apparently the fragment containing the pac sequence is concerned since a phage DNA probe prepared from the assumed initiation fragments of the first particles of the packaging series gave two signals instead of one with genomic K DNA. Since several independent new χ isolates showed the same Eco RI restriction pattern as the original phage of ELLMAUER and KAPLAN (1959), the generation of χ is a reproducible event.
Characterization of two epiphytic bacteria from soybean leaves with antagonistic activities against Pseudomonas syringae pv. glycinea
Authors: Völksch Beate , Nüske Jörg , May Rudolf 
Published: February 2007

AbstractThe strains 48b/90 and 22d/93 are naturally occurring ephiphytes which were isolated from soybean leaves. On the basis of pheno‐ and genotypic characteristics 48b/90 was identified as Erwinia herbicola and 22d/93 as Pseudomonas syringae. These two isolates produced biological active substances against different indicator organisms. The E. herbicola strain showed clear antagonistic properties against Escherichia coli and Pseudomonas syringae pv. glycinea, but not against Geotrichum candidum. 22d/93 was active against P. glycinea and G. candidum, but not against E. coli. Strain 48b/90 produced at least two different inhibitors: an antibiotic substance and an inhibitor of the alginate synthesis. Strain 22d/93 produced at least three different compounds inhibitory to P. glycinea and one to G. candidum. Their activities against the bacterial blight pathogen, P. glycinea, can be observed in planta, too. Under the influences of the antagonists the pathogen multiplied at lower rates and to lower stationary phase population levels. The development of bacterial blight symptoms was suppressed.
Control of the Myc‐Max mediated transactivation in yeast by natural promoter elements
Authors: Hänel Frank , Peukert Karen , Munder Thomas 
Published: February 2007

AbstractTranscriptional activation studies involving the human oncoprotein and transcription factor Myc and its helix‐loop‐helix partner protein Max in mammalian cells are critical due to the presence of endogenous Myc and Max proteins. Here we show that co‐expression of the human c‐myc and max genes from 2μ circle derived high copy number vectors in yeast cells stimulate the transcriptional activation of a LacZ reporter gene fused to the yeast cytochrome‐c1, oxidase minimal promoter containing the adenovirus major late promoter element (AMLPE). The exchange of the single Myc binding site in the AMLPE by the two E‐box DNA motifs (CACGTG) present in the Myc responsive element of a human Myc target gene (ornithine decarboxylase) in front of a promoter‐reporter gene cassette results in a two‐fold enhanced ß‐galactosidase expression. Low expression of max and high level expression of c‐myc at the same time led to a further enhancement of transcriptional activation from this promoter‐reporter gene cassette.
The metabolism of gluconate in Escherichia coli. The subsidiary system and the nature of the gntS gene
Authors: Istúriz Tomás , Celaya Joseba 
Published: February 2007

AbstractThe transport and phosphorylation of gluconate in E. coli occurs through two systems (GntI and GntII) which duplicate activities. bioH‐asddeletion mutants do not grow on media with gluconate as sole carbon source because they lack the GntI system and do not express GntII. Although E. coli C177 is a Δ(bioH‐asd) mutant, it carries the pyrB linked mutation gnt177 that enables it to metabolize this substrate through inducible expression of the GntII system. Several gntS derivatives which are unable to grow on gluconate were isolated from E. coli C177 by spontaneous curing of the transposon Tn10 previously inserted at the gntS locus (zjf::Tn10, min 95.3). A representative gntS mutant, E. coli TI141A retained the ability to take up gluconate but had lost the thermosensitive gluconokinase activity (gene gntV, min 96.9). Furthermore, it could be demonstrated that gntV is repressed in E. coli TI141A. The results indicate that gntS might specify a trans‐acting positive regulator involved in the control of at least the expression of the thermosensitive gluconokinase (GntII), instead of a gluconate uptake system as it was previously postulated. Likewise, these results can be used to reconsider whether the locus altered by the gnt177 lesion is allelic with that of the GntII permease instead of a regulator, as it was originally postulated.
Localization of alanyl aminopeptidase and leucyl aminopeptidase in cells of Pseudomonas aeruginosa by application of different methods for periplasm release
Authors: Jensch Torsten , Fricke Beate 
Published: February 2007

AbstractVarious methods for the isolation of periplasm were examined and compared with regard to the complete release of known periplasmic marker enzymes and the contamination of the periplasm by cytosol for Pseudomonas aeruginosa PAO1 as a significant Gram‐negative test strain. The aim of the investigations was to clarify the exact localization of alanyl aminopeptidase (AAP) and leucyl aminopeptidase (LAP) of this microorganism and to evaluate these methods.The osmotic shock of NOSSAL and HEPPEL (1996) was the most effective method with the lowest contamination by the cytosolic marker enzyme malic enzyme, but some proteins, which are located near the inner side of the cytoplasmic membrane, can be released additionally into the periplasm. All other procedures like chloroform or polymyxin treatment, the magnesium chloride washing of intact bacteria and spheroblasting by lysozyme in the presence of EDTA or magnesium chloride resulted only in a partial, sometimes only very low release of periplasm. The periplasmic enzymes are bound either more by hydrophobic or more by ionic interactions to the cell envelope and show a different behaviour with the different releasing agents. These methods are useful for a further differentiation between really periplasmic proteins and those proteins, which were false positive found in periplasm as a result of the osmotic shock. Our results show that AAP from Pseudomonas aeruginosa is a periplasmic enzyme with hydrophobic interactions to the cytoplasmic membrane, corresponding to the early results of LAZDUNSKI and MURGIER for Escherichia coli (LAZDUNSKI et al. 1975a and b, MURGIER et al. 1977), and LAP is cytosolic, but located near the cytoplasmic membrane. The AAP is not a real amphipatic membrane protein, as could be demonstrated by phase separation experiments with Triton X‐114.
The response of three strains of Anacystis nidulans (cyanobacteria) to ultraviolet‐B radiation
Authors: Pandey U. , Chatterjee C. 
Published: February 2007

AbstractThe influnce of UV‐B irradiance was examined on three strains of a cyanobacterium, Anacystis nidulans. These include wild type A. nidulans (An) and strains resistant to cadmium (Cdr) and cyanophage As‐1 (As‐1r). The results indicated that although, the UV‐B radiation considered in the present study was damaging to all the three strains, As‐1r offered some degree of protection from UV‐B as far as changes in chlorophyll, phycocyanin, 14CO2 uptake and photosynthetic O2 evolution were concerned. Cadmium resistant strain appeared to be most sensitive to UV‐B among the three. The observations form the first report of UV‐B effects on a metal resistant and a cyanophage resistant strain of cyanobacterium.
Effect of certain nutrients on the production of dextransucrase from Leuconostoc mesenteroides NRRL B‐512F
Authors: Goyal Arun , Katiyar Sarvagya S. 
Published: February 2007

AbstractThe effects of certain nutrients on dextransucrase (sucrose: 1,6‐α‐D‐glucan 6‐α‐D‐glucosyltransferase EC 2.4.1.5) production from Leuconostoc mesenteroides NRRL B‐512F were studied. An increase in concentration of sucrose to 4% in the enzyme production medium resulted in the increase of activity of dextransucrase. Higher enzyme yields were obtained at low yeast extract and high phosphate concentrations. The presence of peptone and beef extract in the medium in addition to 2% yeast extract resulted in an enhanced production of dextranscucrase. The enzyme activity increased by 30% by both peptone and beef extract. Addition of Tween 80 to the medium enhanced the production of enzyme and the activity was increased by 25%. Magnesium ions stimulated the acitivity marginally. Sodium fluoride enhanced the activity of dextransucrase by 25%.
Surface‐active properties of rhamnolipids from Pseudomonas aeruginosa GS3
Authors: Patel Reena M. , Desai Anjana J. 
Published: February 2007

AbstractPseudomonas aeruginosa GS3 produced rhamnolipid biosurfactants during growth on carbohydrates, higher chain length n‐alkanes and l‐alkenes, petroleum crude oil and vegetable oils. With glucose as the substrate, maximum surfactant production (0.44 g/l) was observed during the stationary phase of growth. Partially purified rhamnolipids showed excellent surface‐active properties in terms of reduction in the interfacial tension between them and a variety of hydrocarbons, hydrocarbon mixtures and vegetable oils and formation of stable emulsion.
Genome instability and chromosomal rearrangements in a heterothallic wine yeast
Authors: Miklos Ida , Varga Tamás , Nagy Ágnes , Sipiczki Matthias 
Published: February 2007

AbstractWine strains of Saccharomyces cerevisiae are usually homothallic diploids and show chromosome length polymorphism. We describe the analysis of a heterothallic strain heterozygous for the mating types a and α. Surveying cultures of the strain, we found a remarkable degree of heterogeneity in ploidy and in electrophoretic karyotype. The CHEF analysis of tetrads and dyads revealed an enormous variability of band patterns hampering the analysis of chromosome segregation. We propose that the instability of ploidy and chromosome polymorphism might be due to heterothallism that precludes the process ‘genome renewal’ (MORTIMER et al. 1994) by selfdiploidization of spore clones.
Cu2+ efflux and its regulation in Cu‐resistant (Cur) cyanobacterium Nostoc calcicola BRÉB
Authors: Pandey P. K. , Singh S. P. , Bisen P. S. 
Published: February 2007

AbstractCu2+‐tolerant/resistant (Cur) strain of the cyanobacterium Nostoc calcicola BRÉB., developed in the laboratory, showed remarkable growth in ambient medium containing 40 μM Cu2+ (5 μM Cu2+ being lethal for wild type strain). It showed 22% less Cu2+ uptake compared to Cus (Cu‐sensitive) cells. Cur cyanobacterial cells were characterized by a time‐dependent Cu2+ efflux in contrast to no cation efflux by Cus cells. Cu2+ efflux pattern in Cur cells consisted of two distinct phases: First rapid efflux (10 min) followed by slower second one at least up to 1 h. Cu2+ efflux depended to a major extent on light generated ATP1), as the dark exposed Cur cells showed 87% reduction in Cu2+ efflux. The lowering in Cu2+ efflux in presence of various metabolic inhibitors/uncouplers like carbonyl cyanide‐m‐chloro phenyl hydrazone (CCCP)1), N,N'‐dicyclohexycarbodiimide (DCCD), azide (NaN3) and p‐chloromercuribenzoate (pCMB) indicated the involvement of ‐SH group, membrane potential and ATP hydrolysis in the regulation of this process. Cu2+ efflux was also initiated in such a medium containing 100‐fold lower Cu2+ concentration (0.4 μM) compared to 40 μM Cu2+ (saturing concentration for metal uptake) and not before. It is suggested that Cu2+ efflux in N. calcicola cells may be the predominant mechanism of Cu2+ resistance/tolerance in this organism and are regulated at different levels by different modifying factors.
The effect of heparin on the activity of Trichosporon cutaneum casein kinase I
Authors: Wojda Iwona , Frajnt Magdalena , Jakubowicz Teresa 
Published: February 2007

AbstractCasein kinase I from Trichosporon cutaneum ribosome‐free extracts was purified. Its molecular mass was calculated for 33 kDa. It was shown that casein, phosvitin and Trichosporon cutaneum ribosomal protein of 15 kDa were preferable substrates for the enzyme. It was found that heparin can stimulate or inhibit CKI activity depending on the substrate used. Stimulation of casein and inhibition of phosvitin phosphorylation was observed. In addition it was shown that ribosomal proteins of 19 kDa and 38 kDa were phosphorylated by CKI only in the presence of heparin.
Nucleotide sequence of the Staphylococcus aureus transposon, Tn5405, carrying aminoglycosides resistance genes
Authors: Derbise Anne , de Cespedes Gilda , Solh Nevine El 
Published: February 2007

AbstractTn5405 is a 12 kb staphylococcal composite transposon delimited by two inverted copies of the insertion sequence IS1182. This transposon carries two aminoglycosides resistance genes, aphA‐3 and aadE, an altered gene similar to sat4 from Campylobacter coli BE/G4, and three open reading frames of unknown functions.
Monthly variability of satellite‐derived cyclonic activity for the southern hemisphere winter
Authors: Carleton Andrew M. 
Published: February 2007

AbstractA satellite‐derived climatology of cloud vortices for the Southern Hemisphere winter (June to September) indicates that significant within‐season changes occur in the areal frequencies of extratropical depressions. This variability is found to be most strongly associated with the climatic frontal zones, while on a zonally‐averaged basis, the semi‐annual oscillation of the circumpolar vortex appears to dominate the latitudinal changes in cyclonic activity between June and September. Surface‐atmosphere interactions evidently play a key role in the wintertime circulation at middle and high latitudes. Cyclogenesis over the Southern Oceans is observed to be linked closely to the baroclinity associated with the Oceanic Polar Front, while on a regional scale, the presence of a time‐averaged zone of in situ cyclogenesis over sub‐antarctic latitudes of the South Pacific is found to be augmented by the influence of the unique winter season sea ice regime in that sector.
Sea breezes along the Canterbury coast in the vicinity of Christchurch, New Zealand
Authors: Sturman A. P. , Tyson P. D. 
Published: February 2007

AbstractObservations are presented suggesting the significance of sea breezes in producing distinctive diurnal boundary layer oscillations over Christchurch. Sea breeze effects are shown to be an all‐year phenomenon reaching their maxima in summer. The interaction of onshore wind components with south‐westerly gradient winds (even under cloudy conditions) appears to produce a distinctive all‐seasons diurnal rhythm in the gradient wind. The development of shallow north‐easterlies blowing into an orographically‐induced lee trough, preceding the onset of ground north‐westerlies, is shown to produce a complicated system of onshore airflow when combined with the sea breeze. Under such conditions it is argued that a sea breeze return current may be discerned.Canterbury sea breezes are an important feature of the local climate and correspond in many respects to classical sea breeze models. Notwithstanding, it is their site‐specific characteristics that render them of particular interest.
Net incoming radiation estimated from hourly global radiation and/or cloud observations
Authors: Nielsen L. B. , Prahm L. P. , Berkowicz R. , Conradsen K. 
Published: February 2007

AbstractFrom routine hourly observations reported during 5 years at one site in Denmark, empirical relations for net radiation over green grass are found. These relations give an estimate of the net radiation for the measuring site from the geographical position, local time, representative surface albedo, measured global radiation and/or total cloud cover in oktas. Cloud types are taken into account, if the reported clouds are mainly cirrus forms. This is a result of a classification of the net radiation according to cloud cover and type, i.e. a total of 90 classes. Different relations are found for different cloud covers.The derived procedure is used on another site in Denmark with another representative surface albedo. From 10 years of data, consistency is found for net radiation measurements at the two sites, allowing extrapolation of the derived net radiation procedure to other sites in Denmark. Data from the Wangara experiment (Clarke, 1971), covering 40 days, showed a similar relation for clear sky conditions, but revealed another general dependency of net radtation upon cloud cover than that found in Denmark. Therefore, relations of the kind found in this study are related to the weather and climate of the measuring site. Comparisons between net radiation estimated from the models and measurements from different sites is r2 ⋍ 0.9.
A principal component and spectral analysis of European rainfall
Authors: Tabony R. C. 
Published: February 2007

AbstractThe main patterns of European rainfall anomalies were obtained from a principal component analysis of 182 homogeneous rainfall series from 1861 to 1970. The most important component corresponded to an anomaly of the same sign and magnitude covering most of the area examined. The principal components were essentially the same for all seasons and limited networks of stations back to 1786 showed that they were stable with lime. Spectral analysis of the patterns revealed cycles in European rainfall at periods of 2.4 years in summer and 2.1 and 5 years in the winter half year. The first of these is the most likely to represent a permanent feature of the atmosphere.
Spatial analysis of secular temperature fluctuations
Authors: Lawson Merlin P. , Balling Robert C. , Peters Albert J. , Rundquist Donald C. 
Published: February 2007

AbstractThe identification of global trends in secular temperature has resulted in various theories explaining temporal climatic fluctuations. Few investigators have attempted to regionalize these trends as derived from climatic statistics. This study attempts to: (1) review methodological problems inherent in the study of climatic fluctuations; (2) suggest a methodology to overcome some of the difficulties; and (3) develop discrete regions of temperature variation. The results presented in this study significantly complement the information derived by depicting large areal units by climatic summary statistics. Nine discrete regions of temperature trend are developed for the United States, and the contiguity of the resulting regions suggests that climatic fluctuations display distinct spatial patterns.
Evidence of an 11‐year periodicity in tree‐ring series from formosa related to the sunspot cycle
Authors: Mori Yukihiro 
Published: February 2007

AbstractIt has been pointed out previously that tree‐ring series from Formosa show an 11‐year periodicity related to the sunspot cycle. However, significance tests of this finding have not been made and therefore the statistical reliability has not been known. Spectra of tree‐ring series from other sites reported before show no evidence that the 11‐year sunspot cycle appears in tree‐ring series. Spectral analyses have been made of published tree‐ring data from Formosa and previous studies have been re‐examined. Tree‐ring series from two different sites in Formosa show an 11‐year spectral peak at the level of confidence higher than 90%. Cross spectral analysis between the tree‐ring series and the Zurich annual sunspot number shows that the 11‐year fluctuations in the tree‐ring series are related to the sunspot cycle with a time lag of 1/4 phase at the 99% confidence level. Using a band‐pass filter technique, it is found that the 11‐year fluctuations in tree‐ring series correspond to almost each cycle of the sunspot number except for periods of low solar activity. Significant 11 ‐year fluctuations in the tree‐ring series appear during most of the periods of an ‘active’ sun as estimated by carbon 14 abundance in tree‐rings.
Empirical orthogonal analysis of 700 mb geopotentials during the summer monsoon over Asia
Authors: Sikka D. R. , Prasad K. D. 
Published: February 2007

AbstractMean monthly 700 mb geopotential anomaly fields over the Asiatic region for the four summer monsoon months June to September based on 15 years data (1964 to 1978) have been analysed through an empirical orthogonal functions technique. The analysis shows that the first five dominant functions explain about 80 per cent of the total original variance, thereby affording a method by which 93 per cent of the data reduction is possible in each of the months considered. Correlations have been derived for the first three dominant functions of a month with the corresponding functions of the other months. Similarly, the time amplitudes of the first three functions of a month have been correlated with the corresponding time amplitudes of the other three months. The correlation analyses show that the first function and its associated amplitude for June are significantly correlated with the corresponding functions and amplitudes of the other three months. The time amplitudes of the first and the second functions have been used to determine analogous mean monthly anomaly patterns among different years of the data under study.
The effect of weather conditions on the public demand for meteorological information
Authors: Smith Keith 
Published: February 2007

AbstractThis paper describes how regional Weather Centres in Britain supply meteorological information to the community. With reference to the public enquiries directed to the Glasgow Weather Centre, it is shown how the demand for such information is likely to reflect a mix of socio‐economic and atmospheric factors. Spontaneous daily enquiries recorded over a 2‐year period in Glasgow are analysed through a regression model to demonstrate wide differences in weather sensitivity between demand categories. The most numerous enquiry types are shown to be those most dependent on weather conditions. Finally, it is suggested that any future work should incorporate a measure of behavioural influences in order to provide the best delineation of enquiry demand characteristics.