bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suppressors of an Adenylate Cyclase Deletion in the Fission Yeast
Schizosaccharomyces pombe
Authors: Stiefel Jeffrey , Wang Lili , Kelly David A. , Janoo Rozmin T. K. , Seitz Jeffrey , Whitehall Simon K. , Hoffman Charles S. 
Published: June 2004

ABSTRACT

Schizosaccharomyces pombe
utilizes two opposing signaling pathways to sense and respond to its nutritional environment. Glucose detection triggers a cyclic AMP signal to activate protein kinase A (PKA), while glucose or nitrogen starvation activates the Spc1/Sty1 stress-activated protein kinase (SAPK). One process controlled by these pathways is
fbp1
+
transcription, which is glucose repressed. In this study, we isolated strains carrying mutations that reduce high-level
fbp1
+
transcription conferred by the loss of adenylate cyclase (
git2
Δ), including both
wis1
−
(SAPK kinase) and
spc1
−
(SAPK) mutants. While characterizing the
git2
Δ suppressor strains, we found that the
git2
Δ parental strains are KCl sensitive, though not osmotically sensitive. Of 102
git2
Δ suppressor strains, 17 strains display KCl-resistant growth and comprise a single linkage group, carrying mutations in the
cgs1
+
PKA regulatory subunit gene. Surprisingly, some of these mutants are mostly wild type for mating and stationary-phase viability, unlike the previously characterized
cgs1
-
1
mutant, while showing a significant defect in
fbp1-lacZ
expression. Thus, certain
cgs1
−
mutant alleles dramatically affect some PKA-regulated processes while having little effect on others. We demonstrate that the PKA and SAPK pathways regulate both
cgs1
+
and
pka1
+
transcription, providing a mechanism for cross talk between these two antagonistically acting pathways and feedback regulation of the PKA pathway. Finally, strains defective in both the PKA and SAPK pathways display transcriptional regulation of
cgs1
+
and
pka1
+
, suggesting the presence of a third glucose-responsive signaling pathway.
RasC Plays a Role in Transduction of Temporal Gradient Information in the Cyclic-AMP Wave ofDictyostelium discoideum
Authors: Wessels Deborah , Brincks Rebecca , Kuhl Spencer , Stepanovic Vesna , Daniels Karla J. , Weeks Gerald , Lim Chinten J. , Spiegelman George , Fuller Danny , Iranfar Negin , Loomis William F. , Soll David R. 
Published: June 2004

ABSTRACTTo define the role that RasC plays in motility and chemotaxis, the behavior of arasCnull mutant,rasC−, in buffer and in response to the individual spatial, temporal, and concentration components of a natural cyclic AMP (cAMP) wave was analyzed by using computer-assisted two-dimensional and three-dimensional motion analysis systems. These quantitative studies revealed thatrasC−cells translocate at the same velocity and exhibit chemotaxis up spatial gradients of cAMP with the same efficiency as control cells. However,rasC−cells exhibit defects in maintaining anterior-posterior polarity along the substratum and a single anterior pseudopod when translocating in buffer in the absence of an attractant.rasC−cells also exhibit defects in their responses to both the increasing and decreasing temporal gradients of cAMP in the front and the back of a wave. These defects result in the inability ofrasC−cells to exhibit chemotaxis in a natural wave of cAMP. The inability to respond normally to temporal gradients of cAMP results in defects in the organization of the cytoskeleton, most notably in the failure of both F actin and myosin II to exit the cortex in response to the decreasing temporal gradient of cAMP in the back of the wave. While the behavioral defect in the front of the wave is similar to that of themyoA−/myoF−myosin I double mutant, the behavioral and cytoskeletal defects in the back of the wave are similar to those of the S13A myosin II regulatory light-chain phosphorylation mutant. Expression array data support the premise that the behavioral defects exhibited by therasC−mutant are the immediate result of the absence of RasC function.
Genome-Wide Single-Nucleotide Polymorphism Map for
Candida albicans
Authors: Forche Anja , Magee P. T. , Magee B. B. , May Georgiana 
Published: June 2004

ABSTRACT

Single-nucleotide polymorphisms (SNPs) are essential tools for studying a variety of organismal properties and processes, such as recombination, chromosomal dynamics, and genome rearrangement. This paper describes the development of a genome-wide SNP map for
Candida albicans
to study mitotic recombination and chromosome loss.
C. albicans
is a diploid yeast which propagates primarily by clonal mitotic division. It is the leading fungal pathogen that causes infections in humans, ranging from mild superficial lesions in healthy individuals to severe, life-threatening diseases in patients with suppressed immune systems. The SNP map contains 150 marker sequences comprising 561 SNPs and 9 insertions-deletions. Of the 561 SNPs, 437 were transition events while 126 were transversion events, yielding a transition-to-transversion ratio of 3:1, as expected for a neutral accumulation of mutations. The average SNP frequency for our data set was 1 SNP per 83 bp. The map has one marker placed every 111 kb, on average, across the 16-Mb genome. For marker sequences located partially or completely within coding regions, most contained one or more nonsynonymous substitutions. Using the SNP markers, we identified a loss of heterozygosity over large chromosomal fragments in strains of
C. albicans
that are frequently used for gene manipulation experiments. The SNP map will be useful for understanding the role of heterozygosity and genome rearrangement in the response of
C. albicans
to host environments.
Candida albicans
Rim13p, a Protease Required for Rim101p Processing at Acidic and Alkaline pHs
Authors: Li Mingchun , Martin Samuel J. , Bruno Vincent M. , Mitchell Aaron P. , Davis Dana A. 
Published: June 2004

ABSTRACT

Candida albicans
is an important commensal of mucosal surfaces that is also an opportunistic pathogen. This organism colonizes a wide range of host sites that differ in pH; thus, it must respond appropriately to this environmental stress to survive. The ability to respond to neutral-to-alkaline pHs is governed in part by the
RIM101
signal transduction pathway. Here we describe the analysis of
C. albicans
Rim13p, a homolog of the Rim13p/PalB calpain-like protease member of the
RIM101
/
pacC
pathway from
Saccharomyces cerevisiae
and
Aspergillus nidulans
, respectively.
RIM13
, like other members of the
RIM101
pathway, is required for alkaline pH-induced filamentation and growth under extreme alkaline conditions. Further, our studies suggest that the
RIM101
pathway promotes pH-independent responses, including resistance to high concentrations of lithium and to the drug hygromycin B.
RIM13
encodes a calpain-like protease, and we found that Rim101p undergoes a Rim13p-dependent C-terminal proteolytic processing event at neutral-to-alkaline pHs, similar to that reported for
S. cerevisiae
Rim101p and
A. nidulans
PacC. However, we present evidence that suggests that
C. albicans
Rim101p undergoes a novel processing event at acidic pHs that has not been reported in either
S. cerevisiae
or
A. nidulans
. Thus, our results provide a framework to understand how the
C. albicans
Rim101p processing pathway promotes alkaline pH-independent processes.
RBR1
, a Novel pH-Regulated Cell Wall Gene of
Candida albicans
, Is Repressed by
RIM101
and Activated by
NRG1
Authors: Lotz Henrike , Sohn Kai , Brunner Herwig , Mühlschlegel Fritz A. , Rupp Steffen 
Published: June 2004

ABSTRACT

The transcription factor Rim101p of
Candida albicans
has been shown to play a major role in pH-dependent gene regulation. Rim101p is involved in cell wall biosynthesis, since it regulates
PHR1
and
PHR2
, two almost functionally redundant cell wall glycosidases important for adaptation to either neutral or acidic habitats within the human host. To identify additional cell wall components regulated by Rim101p, we performed transcriptional profiling with a cell wall-specific DNA microarray. We showed that Rim101p contributes to the activation of known hypha-specific genes such as
HWP1
and
RBT1
but is also required for repression of the previously uncharacterized potential cell wall genes
RBR1
,
RBR2
, and
RBR3
. Further characterization of
RBR1
revealed that it encodes a small glycosylphosphatidyl inositol protein that is expressed under acidic conditions predominantly at low temperature. Deletion of the gene resulted in a filamentation defect at low pH. Most interestingly,
NRG1
, a transcriptional repressor of hyphal growth in
C. albicans
, was required for
RBR1
expression. The apparently activating effect of
NRG1
observed in this study has not been described before. In addition, we showed that expression of
NRG1
is not only temperature but also pH dependent.
Sequence Elements Necessary for Transcriptional Activation ofBAD1in the Yeast Phase ofBlastomyces dermatitidis
Authors: Rooney Peggy J. , Klein Bruce S. 
Published: June 2004

ABSTRACTBlastomyces dermatitidisis a dimorphic fungal pathogen that converts from mycelia or conidia to a host-adapted yeast morphotype upon infection. Conversion to the yeast form is accompanied by the production of the virulence factor BAD1. Yeast-phase-specific expression of BAD1 is transcriptionally regulated, and its promoter shares homology with that of the yeast-phase-specific geneYPS3ofHistoplasma capsulatum. Serial truncations of theBAD1upstream region were fused to thelacZreporter to define functional areas in the promoter. Examination of PBAD1-lacZfusions inB. dermatitidisindicated thatBAD1transcription is upregulated in the yeast phase. The 63-nucleotide box A region conserved in theYPS3upstream region was shown to be an essential component of the minimalBAD1promoter. A matched PYPS3-lacZconstruct indicated that this same region was needed for minimalYPS3promoter activity inB. dermatitidistransformants. Reporter activity inH. capsulatumtransformants similarly showed a requirement for box A in the minimalBAD1promoter. Several putative transcription factor binding sites were identified within box A ofBAD1. Replacement of two of these predicted sites within box A—a cAMP responsive element and a Myb binding site—sharply reduced transcriptional activity, indicating that these regions are critical in dictating the yeast-phase-specific expression of this crucial virulence determinant ofB. dermatitidis.
Subpressor Dose Asymmetric Dimethylarginine Modulates Renal Function in Humans through Nitric Oxide Synthase Inhibition
Authors: Kielstein J.T. , Simmel S. , Bode-Böger S.M. , Roth H.J. , Schmidt-Gayk H. , Haller H. , Fliser D. 
Published: June 2004

Increased blood concentrations of the endogenous nitric oxide (NO) synthase inhibitor asymmetric dimethylarginine (ADMA) have been linked to high blood pressure and to cardiovascular mortality. We evaluated the effects of a subpressor ADMA dose on NO production, renal hemodynamics, sodium handling and active renin and noradrenalin plasma concentrations in 12 healthy subjects (age 26 ± 1 year) using a double-blind placebo-controlled study design. Infusion of ADMA caused a significant decrease in plasma cyclic guanosine monophosphate (cGMP) levels, i.e. the second messenger of NO (from 6.1 ± 0.4 to 4.3 ± 0.3 pmol/l; p < 0.05). In parallel, effective renal plasma flow (ERPF) decreased while renovascular resistance (RVR) increased significantly (ERPF from 667 ± 9 to 603 ± 10 ml/min/1.73 m²; RVR from 79 ± 2 to 91 ± 2 ml/min/mm Hg; both p < 0.05 vs. baseline). Infusion of placebo did not cause significant changes in plasma cGMP levels, ERPF and RVR (cGMP from 5.7 ± 0.5 to 5.9 ± 0.6 pmol/l; ERPF from 665 ± 12 to 662 ± 11 ml/min/1.73 m²; RVR from 79 ± 2 to 78 ± 2 ml/min/mm Hg; all non-significant). Moreover, urinary sodium excretion was significantly lower with infusion of ADMA as compared with placebo infusion (128 ± 8 vs. 152 ± 7 µmol/min; p < 0.05). In contrast, blood pressure, active renin and noradrenalin plasma concentrations did not change significantly with either infusion protocol. Acute infusion of a subpressor ADMA dose modulates several aspects of renal function in humans without affecting the activity of the renin-angiotensin and sympathetic system. Whether chronic (intrarenal) NO synthase inhibition in individuals with increased ADMA blood levels may cause persistent renal vasoconstriction and sodium retention must be evaluated.
Discovery and Development of Asymmetric Autocatalysis
Authors: Soai Kenso , Shibata Takanori , Sato Itaru 
Published: June 2004

Abstract
Asymmetric autocatalysis occurs when a chiral product operates as an asymmetric catalyst for its own production. We have discovered an asymmetric autocatalytic reaction in the enantioselective addition of dialkylzinc to pyridine-3-carbaldehyde, where the product, 3-pyridyl alkanol, acts as an asymmetric autocatalyst. A diol, ferrocenyl alkanol, 5-pyrimidyl alkanol, and 3-quinolyl alkanol were also found to be asymmetric autocatalysts for the enantioselective isopropylation of the corresponding aldehydes. Of these compounds, 5-(2-alkynyl)pyrimidyl alkanol was the best asymmetric autocatalyst, and the asymmetric autocatalytic isopropylation of the corresponding pyrimidine-5-carbaldehyde proceeded quantitatively ( &gt;99%), affording itself as a near enantiomerically pure ( &gt;99.5% ee) chiral product. When an asymmetric autocatalyst with an extremely low ee was used, the asymmetric autocatalytic reaction proceeded along with amplification of the ee, and a highly enantiomerically enriched product was obtained. When the enantioselective isopropylation of pyrimidine-5-carbaldehydes was examined in the presence of chiral organic compounds with a very low ee acting as chiral initiators, then highly enantiomerically enriched 5-pyrimidyl alkanols were obtained. Their absolute configurations were dependent upon the slight excess of enantiomer in the chiral initiators. Chiral inorganic crystals, such as quartz and sodium chlorate, also act as chiral initiators. In conjunction with asymmetric autocatalysis, the chirality of organic compounds with a high enantiomeric excess has been correlated for the first time with the circularly polarized light and chiral inorganic crystals. Moreover, when an enantioselective isopropylation was examined in the absence of a chiral initiator, asymmetric induction above the detection level was observed in the product, with the ratio of the resulting predominant S- and R-isomers being almost equal. This result fulfills one of the conditions necessary for spontaneous absolute asymmetric synthesis.
Enhancement of the Antisense Effect of Polysaccharide–Polynucleotide Complexes by Preventing the Antisense Oligonucleotide from Binding to Proteins in the Culture Medium
Authors: Mizu Masami , Koumoto Kazuya , Anada Takahisa , Karinaga Ryouji , Kimura Taro , Nagasaki Takeshi , Shinkai Seiji , Sakurai Kazuo 
Published: June 2004

Abstract
Schizophyllan is a β-(1→3)-d-glucan existing as a triple helix in water and as a single chain in dimethyl sulfoxide (DMSO), respectively. As we already reported, when a homo-phosphodiester-polynucleotide is added to the schizophyllan/DMSO solution and, subsequently, DMSO is exchanged for water, the single chain of schizophyllan (s-SPG) forms a complex with the polynucleotide. In this paper, we report that phosphorothioate oligonucleotides can form a complex with s-SPG in the same manner as phosphodiester oligonucleotides. We carried out an in vitro antisense assay combining melanoma cell lines and a phosphorothioate antisense oligonucleotide (AS ODN) to depress c-myb mRNA. We found that the AS ODN bound to the complex reduces cell growth more efficiently than that of naked AS ODN by preventing the AS ODN from binding to albumin in the culture medium and being hydrolyzed.
The Interactions of a Homologous Series of Cationic Surfactants with Bovine Serum Albumin (BSA) Studied Using Surfactant Membrane Selective Electrodes
Authors: Rafati Amir Abbas , Bordbar Abdol-Khalegh , Gharibi Husein , Amini Mohamad-Kazem , Safarpour Mohamad-Ali 
Published: June 2004

Abstract
The binding of a homologous series of n-alkyltrimethylammonium bromides to bovine serum albumin were measured in 2.7 mM phosphate buffer, pH 7.0, and at various temperatures using surfactant membrane selective electrodes as a fast and accurate method. The obtained binding isotherms have been analyzed and interpreted using the binding capacity concept, Hill equation and Wyman binding potential. The system behaved as a system with two sets of binding sites in all studied situations. The results represent the essential role of hydrophobic interactions in the first binding set. At high cationic surfactant concentrations, the occupation of the second binding set occurred, with an accompanying unfolding and exposure of numerous hydrophobic binding sites. However, this unfolding process occurred for the cationic surfactant at much higher concentrations than was required for sodium dodecyl sulfate. The Gibbs free energy change calculated on the basis of the Wyman binding potential concept decreases in the initial stages of binding and passes through a minimum, followed by occupation of the second binding set. The affinity of binding increased with increasing temperature, indicating an endothermic and essentially entropy driven process.
Separation of Flavonoids by Semi-Micro High-Performance Liquid Chromatography with Electrochemical Detection
Authors: Jin Dongri , Hakamata Hideki , Takahashi Kouji , Kotani Akira , Kusu Fumiyo 
Published: June 2004

Abstract
A highly sensitive and selective method was developed for the determination of 15 flavonoids by high-performance liquid chromatography with electrochemical detection (HPLC–ECD) using a microbore column. The 15 flavonoids were divided into two groups according to their hydrophobicity and were resolved by two isocratic systems, namely, methanol–water (1:1 and 3:7, v/v) containing 0.5% phosphoric acid. The retention factor (k) of each flavonoid linearly correlated with the logarithmic partition of coefficients between 1-octanol–water (log P) values. The detection limits (S/N = 3) of the flavonoids tested were in the range of 2–25 fmol; that is 600 times more sensitive than conventional HPLC with UV detection. The relative standard deviations (RSD, n = 5) were less than 5% at 1 pmol for the flavonoids tested. By the present method, only 100 μL of bottled Japanese green tea were enough to determine the flavonoid contents.
p-Phenylenediammonium-Smectites as Adsorbents with Colorimetric Detection Ability for Phenols in Water
Authors: Okada Tomohiko , Ogawa Makoto 
Published: June 2004

Abstract
The ion exchange of p-phenylenediammonium and sodium-smectites (montmorillonite and synthetic saponite) resulted in the formation of p-phenylenediammonium radical cation and its dimer by the electron transfer from p-phenylenediammonium to smectites, as revealed by the color change (from colorless to green) as well as the visible absorption spectra. The p-phenylenediammonium-saponite thus obtained adsorbed phenols from aqueous solutions. The basal spacing of the p-phenylenediammonium-saponite increased upon the uptake of phenols, indicating a change in the microstructure. The uptake of phenols into the p-phenylenediammonium-saponite from aqueous solutions occurred through the formation of indoaniline dyes, as revealed by the color change from green to purple (for phenol) or purple-blue (for 2,4-dichlorophenol) as well as the absorption spectra. On the contrary, phenols were not intercalated into the interlayer space of the p-phenylenediammonium-montmorillonite.
The Synthesis and Crystal Structure of β-Substituted Thiaporphyrins with Novel Cyclic Substituents
Authors: Agarwal Neeraj , Mishra Sarada Prasad , Hung Chen-Hsiung , Kumar Anil , Ravikanth Mangalampalli 
Published: June 2004

Abstract
21,23-Dithiaporphyrins and 21-monothiaporphyrins with propane-1,3-diyldioxy and its derivatives at the β-thiophene carbons were synthesized and characterized. The cyclic substituents introduced at the β-thiophene carbons altered the electronic properties of the porphyrins. The X-ray structure for 2,3-bis(2,2-dibenzylpropane-1,3-diyldioxy) substituted 21-monothiaporphyrin showed a more planar structure compared to the saddle shaped structure reported for β-unsubstituted 21-monothiaporphyrins.
Relationship between the Hydrophobicity of Dipeptides and the Michaelis–Menten Constant Km of Their Hydrolysis by Carboxypeptidase-Y and Carboxypeptidase-A
Authors: Kanosue Yoshifumi , Kojima Satoshi , Hiraga Yoshikazu , Ohkata Katsuo 
Published: June 2004

Abstract
The enzymatic hydrolysis of dipeptides by carboxypeptidase-Y and carboxypeptidase-A was investigated. In the enzymatic hydrolysis of the dipeptides, a good linear relationship (r = 0.997 and 0.999) was found between the Michaelis–Menten constant (Km) and the hydrophobicity of the substrates evaluated from relative elution volume in reversed-phase HPLC. The correlation suggests that the hydrophobicity of the C-terminal amino acid is a major factor in governing the stability of the enzyme–substrate complex. The difference in the slope of the linear-regression lines seems to reflect the degree of relative hydrophobicity of the binding pockets in carboxypeptidase-Y and carboxypeptidase-A.
The Photochemical Specific Isomerization of Dendritic Stilbenes
Authors: Momotake Atsuya , Hayakawa Junpei , Nagahata Ritsuko , Arai Tatsuo 
Published: June 2004

Abstract
The photochemical properties of stilbene dendrimers 1–3 in THF, as well as the corresponding potassium salts (water-soluble stilbene dendrimers = WSDs) 4–6 in aqueous solution were studied. Unlike the stilbene dendrimers 1–3, the environment of the core moiety in WSDs 4–6 depended on the generation. The first generation WSD 4 suffers from the water atmosphere around the stilbene core, as can be understood by the molecular structure. The largest Stokes shift observed in 4 among WSDs indicated that the dipole moment changed considerably upon photoexcitation. The Stokes shift tended to become smaller in higher generations. This means that the surrounding dendron should block the water molecule from reaching the stilbene core. The core stilbene in G3 WSD 6 may have an environment almost free of water, based on the observation of a similar Stokes shift of that of stilbene dendrimer 3, only soluble in organic solvents in which the core stilbene has a hydrophobic environment. These findings can be extended to the preparation of water soluble organic molecules with hydrophobic interiors with a photoresponsive chromophore at the core as a single molecule. Most interestingly, 6 underwent a photochemical one-way trans-to-cis isomerization. In addition to the photochemical studies of 1–6, the fluorescence properties of G3 dendrimer 3 were compared to those of the other series of stilbene dendrimer 7, which have no carboxylate groups at the periphery.
Textural and Catalytic Properties of MCM-22 Zeolite Crystallized by the Vapor-Phase Transport Method
Authors: Inagaki Satoshi , Kamino Kohei , Hoshino Masahiro , Kikuchi Eiichi , Matsukata Masahiko 
Published: June 2004

Abstract
MCM-22 zeolite crystallized by the vapor-phase transport (VPT) method showed a higher shape-selectivity to p-xylene in the alkylation of toluene with methanol, compared with MCM-22 crystallized by the hydrothermally synthetic (HTS) method, because VPT-MCM-22 has a smaller external surface area and a smaller number of acid sites thereon than HTS-MCM-22. Such textural properties of VPT-MCM-22 are caused by the fact that the spherical particles of VPT-MCM-22 are composed of hexagonal plates as thin as 55 nm; they are larger than those of HTS-MCM-22, which are 30 nm thick. The acidic properties, characterized by NH3-TPD and FT-IR using a pyridine adsorption technique, showed no significant difference between VPT- and HTS-MCM-22, except for the acidity on the external surface.