bluuebunny/crossref_metadata_2025_split huggingface dataset:
Posttranslational Modifications Required for Cell Surface Localization and Function of the Fungal Adhesin Aga1p
Authors: Huang Guohong , Zhang Mingliang , Erdman Scott E. 
Published: October 2003

ABSTRACT

Adherence of fungal cells to host substrates and each other affects their access to nutrients, sexual conjugation, and survival in hosts. Adhesins are cell surface proteins that mediate these different cell adhesion interactions. In this study, we examine the in vivo functional requirements for specific posttranslational modifications to these proteins, including glycophosphatidylinositol (GPI) anchor addition and O-linked glycosylation. The processing of some fungal GPI anchors, creating links to cell wall β-1,6 glucans, is postulated to facilitate postsecretory traffic of proteins to cell wall domains conducive to their functions. By studying the yeast sexual adhesin subunit Aga1p, we found that deletion of its signal sequence for GPI addition eliminated its activity, while deletions of different internal domains had various effects on function. Substitution of the Aga1p GPI signal domain with those of other GPI-anchored proteins, a single transmembrane domain, or a cysteine capable of forming a disulfide all produced functional adhesins. A portion of the cellular pool of Aga1p was determined to be cell wall resident. Aga1p and the α-agglutinin Agα1p were shown to be under glycosylated in cells lacking the protein mannosyltransferase genes
PMT1
and
PMT2
, with phenotypes manifested only in MATα cells for single mutants but in both cell types when both genes are absent. We conclude that posttranslational modifications to Aga1p are necessary for its biogenesis and activity. Our studies also suggest that in addition to GPI-glucan linkages, other cell surface anchorage mechanisms, such as transmembrane domains or disulfides, may be employed by fungal species to localize adhesins.
Sulfonated human immunoglobulin enhances CD16‐linked CD11b expression on human neutrophils
Authors: Kimura Hirokazu , Kato Masahiko , Ikeda Miyuki , Nagai Akira , Okada Yasunori , Naito Shigeto , Oshima Shigeru , Taniguchi Koichi , Kozawa Kunihisa , Morikawa Akihiro 
Published: October 2003

AbstractIntravenous human immunoglobulin therapy infrequently results in excessive inflammatory responses in vivo; these effects are not fully understood. We assessed whether sulfonated human immunoglobulin (SHIG) or polyethylene glycol‐treated human immunoglobulin (PHIG) enhanced expression of inflammatory receptors on peripheral blood neutrophils in vitro, such as αMβ2 (CD11b/CD18) and Fc gamma receptor type III (FcγRIII). CD11b and CD16 expression on neutrophils was measured by fluorescence flow cytometry. Various cytokines were assessed using a highly sensitive fluorescence microsphere system. SHIG enhanced/induced CD11b expression and partial aggregations on neutrophils, but PHIG did not. No detection of aggregation IgG was observed in SHIG and PHIG. SHIG‐induced CD11b expression was inhibited by treatment of corticosteroid (dexamethasone) and by anti‐CD16 monoclonal antibody. Concentrations of various cytokines such as interleukin (IL)‐1β, IL‐2, IL‐4, IL‐5, IL‐6, IL‐8, IL‐10, RANTES, tumor necrosis factor (TNF)‐α, and interferon (INF)‐γ in culture supernatant were not significantly changed by SHIG or PHIG. SHIG and PHIG did not enhance CD16 on neutrophils. SHIG enhanced CD16‐linked CD11b expression on neutrophils in vitro. CD11b induction was inhibited by dexamethasone and by anti‐CD16 antibody. These in vitro results suggest that aggregations and enhancement of CD11b on neutrophils by SHIG may induce excessive inflammatory responses in vivo.
Loss of hepatocyte co‐operative activity after inhibition of ganglioside GM1 synthesis and shedding
Authors: Brodsky Vsevolod , Zvezdina Natalia , Nechaeva Natalia , Novikova Tatjana , Gvasava Inessa , Fateeva Valentina , Gracheva Helena 
Published: October 2003

AbstractPretreatment of hepatocyte cultures with 1 μM d‐l‐threo‐1‐phenyl‐2‐hexadecanoylamino‐3‐pyrrolidino‐1‐propanol‐HCL (PPPP) for 24 h decreased the ganglioside GM1 content of the cells by ∼50% and that of the conditioned medium by 90%. No rhythm in the rate of protein synthesis was detected in dense cultures pretreated with PPPP, but was observed in control dense cultures. Conditioned medium from control dense cultures induced synchrony in sparse cultures, which were non‐synchronous in their own medium. In contrast, conditioned medium from dense cultures pretreated with PPPP did not synchronize sparse cultures. Since protein synthesis rhythm is a marker of cell synchronization, i.e. their co‐operative activity, then non‐oscillatory behavior means loss of cell co‐operation. The protein synthesis rhythm was restored 24 h after hepatocytes were transferred to PPPP‐free medium. Restoration was more rapid when 0.9 μM gangliosides (standard mixture from bovine brain) were added to the medium just after the withdrawal of PPPP. These novel results concerning the loss of rhythm of protein synthesis in low GM1 ganglioside medium support the conclusion that ganglioside is implicated in the regulation of cell co‐operative activity.
A large-mesh salmon trap: a way of mitigating seal impact on a coastal fishery
Authors: Lunneryd Sven Gunnar , Fjälling Arne , Westerberg Håkan 
Published: October 2003

Abstract
A new design for a salmon trap aimed at minimizing damage to catch and gear caused by grey seals was tested. The traditional trap design used in the northern Baltic permits an efficient hunting strategy by seals, whereby chased fish entangle themselves in the side panels and can then easily be taken, with associated damage to the net. The side panels of the test trap (excluding the fish chamber) are made of large-mesh (400 mm) netting compared to ≤200 mm in traditional traps. This should allow seal-chased and panicking salmon to pass through, while less stressed individuals should still be guided efficiently towards the fish chamber. Trials with the two trap types were performed at the mouth of the river Indal (northern Sweden) in a comparative test programme. Catches of salmon and trout in the test trap were larger than in the standard trap. We estimated that 65% of the potential catch was lost in the standard trap owing to seal predation, while escape rate through the large meshes in the test trap was 52%. The standard trap had a total of 269 holes owing to seal damage, while only six holes were found in the test trap. Seal activity in and around the standard trap was up to 16 times higher compared with the test trap and decreased considerably during the following year when only large-meshed traps were used in the area. We suggest that seals are difficult to deter from fishing gear as long as they get a reward in terms of food and propose that a strategy that deprives seals of a reward will make the gear uninteresting to them and may have long-term mitigation effects.
Isolation of a Gene Encoding a Copper Chaperone for the Copper/Zinc Superoxide Dismutase and Characterization of Its Promoter in Potato
Authors: Trindade Luisa M. , Horvath Beatrix M. , Bergervoet Marjan J.E. , Visser Richard G.F. 
Published: October 2003

Abstract
Gene expression during the potato (Solanum tuberosum) tuber lifecycle was monitored by cDNA-amplified fragment-length polymorphism, and several differentially expressed transcript-derived fragments were isolated. One fragment, named TDFL431, showed high homology to a copper (Cu) chaperone for Cu/zinc superoxide dismutase (CCS). The Ccs protein is responsible for the delivery of Cu to the Cu/zinc superoxide dismutase enzyme. The potato CCS (StCCS) full-length gene was isolated, and its sequence was compared with CCSs from other species. The promoter region of this gene was isolated, fused to the firefly luciferase coding sequence, and used for transformation of potato plants. The highest level of StCCS-luciferase expression was detected in the cortex of stem (like) tissues, such as stem nodes, stolons, and tubers; lower levels were detected in roots and flowers. The StCCS promoter contains regions highly homologous to several plant cis-acting elements. Three of them are related to auxin response, whereas four others are related to response to various stresses. Induction of the StCCS promoter was analyzed on 18 media, differing in hormone, sugar, and Cu content. StCCS expression was induced by auxin, gibberellins (GA4 + 7), fructose, sucrose, and glucose and was inhibited by relatively high concentrations of Cu.
Candida albicansResponse Regulator GeneSSK1Regulates a Subset of Genes Whose Functions Are Associated with Cell Wall Biosynthesis and Adaptation to Oxidative Stress
Authors: Chauhan Neeraj , Inglis Diane , Roman Elvira , Pla Jesus , Li Dongmei , Calera Jose A. , Calderone Richard 
Published: October 2003

ABSTRACTSsk1p ofCandida albicansis a putative response regulator protein of the Hog1 two-component signal transduction system. InSaccharomyces cerevisiae, the phosphorylation state of Ssk1p determines whether genes that promote the adaptation of cells to osmotic stress are activated. We have previously shown thatC. albicans SSK1does not complement thessk1mutant ofS. cerevisiaeand that thessk1mutant ofC. albicansis not sensitive to sorbitol. In this study, we show that theC. albicans ssk1mutant is sensitive to several oxidants, including hydrogen peroxide,t-butyl hydroperoxide, menadione, and potassium superoxide when each is incorporated in yeast extract-peptone-dextrose (YPD) agar medium. We used DNA microarrays to identify genes whose regulation is affected by thessk1mutation. RNA from mutant cells (strain CSSK21) grown in YPD medium for 3 h at 30°C was reverse transcribed and then compared with similarly prepared RNA from wild-type cells (CAF2). We observed seven genes from mutant cells that were consistently up regulated (three-fold or greater compared to CAF2). InS. cerevisiae, three (AHP1,HSP12, andPYC2) of the seven genes that were up regulated provide cells with an adaptation function in response to oxidative stress; another gene (GPH1) is regulated under stress conditions by Hog1p. Three other genes that are up regulated encode a cell surface protein (FLO1), a mannosyl transferase (MNN4-4), and a putative two-component histidine kinase (CHK1) that regulates cell wall biosynthesis inC. albicans. Of the down-regulated genes,ALS1is a known cell adhesin inC. albicans. Verification of the microarray data was obtained by reverse transcription-PCR forHSP12,AHP1,CHK1,PYC2,GPH1,ALS1,MNN4-4, andFLO1. To further determine the function of Ssk1p in the Hog1p signal transduction pathway inC. albicans, we used Western blot analysis to measure phosphorylation of Hog1p in thessk1mutant ofC. albicanswhen grown under either osmotic or oxidative stress. We observed that Hog1p was phosphorylated in thessk1mutant ofC. albicanswhen grown in a hyperosmotic medium but was not phosphorylated in thessk1mutant when the latter was grown in the presence of hydrogen peroxide. These data indicate thatC. albicansutilizes the Ssk1p response regulator protein to adapt cells to oxidative stress, while its role in the adaptation to osmotic stress is less certain. Further,SSK1appears to have a regulatory function in some aspects of cell wall biosynthesis. Thus, the functions ofC. albicans SSK1differ from those ofS. cerevisiae SSK1.
Role of Second-Largest RNA Polymerase I Subunit Zn-Binding Domain in Enzyme Assembly
Authors: Naryshkina Tatyana , Bruning Adrian , Gadal Olivier , Severinov Konstantin 
Published: October 2003

ABSTRACT

The second-largest subunits of eukaryal RNA polymerases are similar to the β subunits of prokaryal RNA polymerases throughout much of their lengths. The second-largest subunits from eukaryal RNA polymerases contain a four-cysteine Zn-binding domain at their C termini. The domain is also present in archaeal homologs but is absent from prokaryal homologs. Here, we investigated the role of the C-terminal Zn-binding domain of Rpa135, the second-largest subunit of yeast RNA polymerase I. Analysis of nonfunctional Rpa135 mutants indicated that the Zn-binding domain is required for recruitment of the largest subunit, Rpa190, into the RNA polymerase I complex. Curiously, the essential function of the Rpa135 Zn-binding domain is not related to Zn
2+
binding per se, since replacement of only one of the four cysteine residues with alanine led to the loss of Rpa135 function. Even more strikingly, replacement of all four cysteines with alanines resulted in functional Rpa135.
EngineeredControl of Cell Morphology In Vivo Reveals Distinct Roles for Yeast andFilamentous Forms of
Candida albicans
duringInfection
Authors: Saville Stephen P. , Lazzell Anna L. , Monteagudo Carlos , Lopez-Ribot Jose L. 
Published: October 2003

ABSTRACT

It
is widely assumed that the ability of
Candida albicans
to
switch between different morphologies is required for pathogenesis.
However, most virulence studies have used mutants that are permanently
locked into either the yeast or filamentous forms which are avirulent
but unsuitable for discerning the role of morphogenetic conversions at
the various stages of the infectious process. We have constructed a
strain in which this developmental transition can be externally
modulated both in vitro and in vivo. This was achieved by placing one
copy of the
NRG1
gene (a negative regulator of filamentation)
under the control of a tetracycline-regulatable promoter. This modified
strain was then tested in an animal model of hematogenously
disseminated candidiasis. Mice injected with this strain under
conditions permitting hyphal development succumbed to the infection,
whereas all of the animals injected under conditions that inhibited
this transition survived. Importantly, fungal burdens were almost
identical in both sets of animals, indicating that, whereas filament
formation appears to be required for the mortality resulting from a
deep-seated infection, yeast cells play an important role early in the
infectious process by extravasating and disseminating to the target
organs. Moreover, these infecting
Candida
yeast cells still
retained their pathogenic potential, as demonstrated by allowing this
developmental transition to occur at various time points postinfection.
We demonstrate here the importance of morphogenetic conversions in
C. albicans
pathogenesis. This engineered strain should
provide a useful tool in unraveling the individual contributions of the
yeast and filamentous forms at various stages of the infectious
process.
Chitin Synthesis in
Saccharomyces cerevisiae
in Response to Supplementation of Growth Medium withGlucosamine and Cell WallStress
Authors: Bulik Dorota A. , Olczak Mariusz , Lucero Hector A. , Osmond Barbara C. , Robbins Phillips W. , Specht Charles A. 
Published: October 2003

ABSTRACT

In
Saccharomyces cerevisiae
most chitin is synthesized by Chs3p,
which deposits chitin in the lateral cell wall and in the bud-neck
region during cell division. We have recently found that addition of
glucosamine (GlcN) to the growth medium leads to a three- to fourfold
increase in cell wall chitin levels. We compared this result to the
increases in cellular chitin levels associated with cell wall stress
and with treatment of yeast with mating pheromone. Since all three
phenomena lead to increases in precursors of chitin, we hypothesized
that chitin synthesis is at least in part directly regulated by the
size of this pool. This hypothesis was strengthened by our finding that
addition of GlcN to the growth medium causes a rapid increase in chitin
synthesis without any pronounced change in the expression of more than
6,000 genes monitored with Affymetrix gene expression chips. In other
studies we found that the specific activity of Chs3p is higher in the
total membrane fractions from cells grown in GlcN and from mutants with
weakened cell walls. Sucrose gradient analysis shows that Chs3p is
present in an inactive form in what may be Golgi compartments but as an
active enzyme in other intracellular membrane-bound vesicles, as well
as in the plasma membrane. We conclude that Chs3p-dependent chitin
synthesis in
S. cerevisiae
is regulated both by the levels of
intermediates of the UDP-GlcNAc biosynthetic pathway and by an increase
in the activity of the enzyme in the plasma
membrane.
A
Phytophthora infestans
G-Protein β Subunit Is Involved in Sporangium Formation
Authors: Latijnhouwers Maita , Govers Francine 
Published: October 2003

ABSTRACT

The heterotrimeric G-protein pathway regulates cellular responses to a wide range of extracellular signals in virtually all eukaryotes. It also controls various developmental processes in the oomycete plant pathogen
Phytophthora infestans
, as was concluded from previous studies on the role of the G-protein α-subunit PiGPA1 in this organism. The expression of the
P. infestans
G-protein β-subunit gene
Pigpb1
was induced in nutrient-starved mycelium before the onset of sporangium formation. The gene was hardly expressed in mycelium incubated in rich growth medium. The introduction of additional copies of
Pigpb1
into the genome led to silencing of the gene and resulted in transformants deficient in PiGPB1. These
Pigpb1
-silenced mutants formed very few asexual spores (sporangia) when cultured in rye sucrose medium and produced a denser mat of aerial mycelium than the wild type. Partially
Pigpb1
-silenced mutants showed intermediate phenotypes with regard to sporulation, and a relatively large number of their sporangia were malformed. The results show that PiGPB1 is important for vegetative growth and sporulation and, therefore, for the pathogenicity of this organism.
Sierra Leone – investing in nutrition to reduce poverty: a call for action
Authors: Aguayo Victor M , Scott Sylvetta , Ross Jay 
Published: October 2003

AbstractBackground:Malnutrition rates in Sierra Leone are among the highest in the world. However, policy-makers do not always recognise the fight against malnutrition as a policy priority to ensure the healthy human capital needed to fight poverty and achieve sustained positive economic growth.Objective:The analysis presented here was conducted by an intersectoral and inter-agency group of Sierra Leonean senior policy advisors to quantify some of the potential human and economic benefits of improved policies and programmes to reduce malnutrition.Findings:The analysis revealed that 46% of child deaths in Sierra Leone are attributable to malnutrition, the single greatest cause of child mortality in the country. In the absence of adequate policy and programme action, malnutrition will be the underlying cause of an estimated 74000 child deaths over the next five years. The analysis also revealed that if current levels of iodine deficiency remain unchanged over the next five years, 252000 children could be born with varying degrees of mental retardation as a result of intrauterine iodine deficiency. Finally, the analysis showed that, in the absence of adequate policy and programme action to reduce the unacceptable rates of anaemia in women, the monetary value of agricultural productivity losses associated with anaemia in the female labour force over the next five years will exceed $94.5 million.Conclusion:Sustained investment in nutrition in Sierra Leone could bring about enormous human and economic benefits to develop the social sector, revitalise the economy, and attain the poverty reduction goals that Sierra Leone has set forth.
De Novo Amino Acid Biosynthesis in Potato Tubers Is Regulated by Sucrose Levels
Authors: Roessner-Tunali Ute , Urbanczyk-Wochniak Ewa , Czechowski Tomasz , Kolbe Anna , Willmitzer Lothar , Fernie Alisdair R. 
Published: October 2003

Abstract
Plant growth and development are strongly dependent on sink-source interactions. In the majority of plants, sucrose (Suc) is the dominant form in which photo-assimilate is transported from source to sinks. Although the effects of Suc on photosynthetic metabolism have been intensively studied, the effect of Suc supply on metabolism in sink organs has received relatively little attention. For this reason, we performed a detailed characterization of the metabolism of potato (Solanum tuberosum) plants in which the Suc supply to the tuber was restricted by genetic or environmental perturbation. These characterizations revealed a clear inverse relationship between the levels of Suc and free amino acids. When data obtained from this study were considered alongside our previous work, a negative correlation between tuber Suc and amino acid content became apparent. Analysis of the transcript levels of key enzymes involved in amino acid biosynthesis revealed that several of these were increased under these conditions. Taken together, these data strongly suggest that Suc regulates amino acid biosynthesis in storage tissues such as potato tubers, most probably at the level of transcription.
The G-Protein-Coupled Receptor GCR1 Regulates DNA Synthesis through Activation of Phosphatidylinositol-Specific Phospholipase C
Authors: Apone Fabio , Alyeshmerni Nicole , Wiens Kathryn , Chalmers Derek , Chrispeels Maarten J. , Colucci Gabriella 
Published: October 2003

Abstract
Different lines of evidence suggest that specific events during the cell cycle may be mediated by a heterotrimeric G-protein activated by a cognate G-protein coupled receptor. However, coupling between the only known Gα-subunit of the heterotrimeric G-protein (GPA1) and the only putative G-protein coupled receptor (GCR1) of plants has never been shown. Using a variety of approaches, we show here that GCR1-enhanced thymidine incorporation into DNA depends on an increase in phosphatidylinositol-specific phospholipase C activity and an elevation of inositol 1,4,5-trisphosphate levels in the cells. Tobacco (Nicotiana tabacum) cells that overexpress either Arabidopsis GCR1 or GPA1 display this phenomenon. We suggest on the basis of these results that GCR1-controlled events during the cell cycle involve phosphatidylinositol-specific phospholipase C as an effector of GCR1 and inositol 1,4,5-trisphosphate as a second messenger, and that GCR1 and GPA1 are both involved in this particular signaling pathway.
Proton Transport in Maize Tonoplasts Supported by Fructose-1,6-Bisphosphate Cleavage. Pyrophosphate-Dependent Phosphofructokinase as a Pyrophosphate-Regenerating System
Authors: Costa dos Santos Anelise , Seixas da-Silva Wagner , de Meis Leopoldo , Galina Antonio 
Published: October 2003

Abstract
The energy derived from pyrophosphate (PPi) hydrolysis is used to pump protons across the tonoplast membrane, thus forming a proton gradient. In a plant's cytosol, the concentration of PPi varies between 10 and 800 μm, and the PPi concentration needed for one-half maximal activity of the maize (Zea mays) root tonoplast H+-pyrophosphatase is 30 μm. In this report, we show that the H+-pyrophosphatase of maize root vacuoles is able to hydrolyze PPi (Reaction 2) formed by Reaction 1, which is catalyzed by PPi-dependent phosphofructokinase (PFP):&#x2028; Fructose-1,6-bisphosphate (F1,6BP) + Pi ↔ PPi +Fructose-6-phosphate (F6 P)(reaction 1)PPi → 2 Pi(reaction 2)H+ cyt → H+ vac (reaction 3) F1,6BP + H+ cyt ↔ H+ vac + F6P + Pi(reaction 4) During the steady state, one-half of the inorganic phosphate released (Reaction 4) is ultimately derived from F1,6BP, whereas PFP continuously regenerates the pyrophosphate (PPi) hydrolyzed. A proton gradient (ΔpH) can be built up in tonoplast vesicles using PFP as a PPi-regenerating system. The Δ pH formed by the H+-pyrophosphatase can be dissipated by addition of 20 mm F6P, which drives Reaction 1 to the left and decreases the PPi available for the H+-pyrophosphatase. The maximal Δ pH attained by the pyrophosphatase coupled to the PFP reaction can be maintained by PFP activities far below those found in higher plants tissues.