bluuebunny/crossref_metadata_2025_split huggingface dataset:
How to build a fungal fruit body: from uniform cells to specialized tissue
Authors: Busch Silke , Braus Gerhard H. 
Published: May 2007

SummaryIt is a challenge in biology to explore the molecular and cellular mechanisms necessary to form a complex three‐dimensional structure composed of different cell types. Interesting models to study the underlying processes are fungi that can transform their wire‐like hyphal filaments into complex and sometimes container‐like fruit bodies. In the past, the role of developmental triggers and transcription factors was a major focus of research on fungal model organisms. In this issue of Molecular Microbiology, Nowrousian and collaborators report that fruit body development of the model organism Sordaria macrospora includes a novel player, a specific membrane protein of the endoplasmic reticulum that is not required for vegetative growth. This finding represents an important step towards connecting regulation of development with the co‐ordinated changes in cellular compartments.
Suicide prevention: disruption of apoptotic pathways by protozoan parasites
Authors: Carmen John C. , Sinai Anthony P. 
Published: May 2007

SummaryThe modulation of apoptosis has emerged as an important weapon in the pathogenic arsenal of multiple intracellular protozoan parasites. Cryptosporidium parvum, Leishmania spp., Trypanosoma cruzi, Theileria spp., Toxoplasma gondii and Plasmodium spp. have all been shown to inhibit the apoptotic response of their host cell. While the pathogen mediators responsible for this modulation are unknown, the parasites are interacting with multiple apoptotic regulatory systems to render their host cell refractory to apoptosis during critical phases of intracellular infection, including parasite invasion, establishment and replication. Additionally, emerging evidence suggests that the parasite life cycle stage impacts the modulation of apoptosis and possibly parasite differentiation. Dissection of the host–pathogen interactions involved in modulating apoptosis reveals a dynamic and complex interaction that recent studies are beginning to unravel.
Sequence features of substrates required for cleavage by GlpG, an Escherichia coli rhomboid protease
Authors: Akiyama Yoshinori , Maegawa Saki 
Published: May 2007

SummaryRhomboids are a family of serine proteases belonging to intramembrane cleaving proteases, which are supposed to catalyse proteolysis of a substrate protein within the membrane. It remains unclear whether substrates of the rhomboid proteases have a common sequence feature that allows specific cleavage by rhomboids. We showed previously that GlpG, the Escherichia coli rhomboid, can cleave a type I model membrane protein Bla‐LY2‐MBP having the second transmembrane region of lactose permease (LY2) at the extramembrane region in vivo and in vitro, and that determinants for proteolysis reside within the LY2 sequence. Here we characterized sequence features in LY2 that allow efficient cleavage by GlpG and identified two elements, a hydrophilic region encompassing the cleavage site and helix‐destabilizing residues in the downstream hydrophobic region. Importance of the positioning of helix‐destabilizers relative to the cleavage site was suggested. These two elements appear to co‐operatively promote proteolysis of substrates by GlpG. Finally, random mutagenesis of the cleavage site residues in combination with in vivo screening revealed that GlpG prefers residues with a small side chain and a negative charge at the P1 and P1′ sites respectively.
The RprY response regulator of Porphyromonas gingivalis
Authors: Duran‐Pinedo Ana E. , Nishikawa Kiyoshi , Duncan Margaret J. 
Published: May 2007

Summary Porphyromonas gingivalis is a Gram‐negative oral anaerobe associated with chronic adult periodontitis. Its ecological niche is the gingival crevice, where the organism adapts to the challenges of the infectious process such as host defence and bacterial products. Bacterial responses to environmental changes are partly regulated by two‐component signal transduction systems. Several intact systems were annotated in the genome of P. gingivalis, as well as an orphan regulator encoding a homologue of RprY, a response regulator from Bacteroides fragilis. With the goal of defining the environmental cues that activate RprY in P. gingivalis, we used several strategies to identify its regulon. Results from gene expression and DNA–protein binding assays identified target genes that were either involved in transport functions or associated with oxidative stress, and indicated that RprY can act as an activator and a repressor. RprY positively activated the primary sodium pump, NADH : ubiquinone oxidoreductase (NQR), and RprY protein also interacted with the promoter regions of nqrA genes from B. fragilis and Vibrio cholerae. Given that gingival bleeding and infiltration of host defence cells are symptoms of periodontal infection, iron products released from blood and reactive oxygen species from polymorphonuclear leucocytes may be potential inducers of the RprY regulon.
Chaperoning Anfinsen: the steric foldases
Authors: Pauwels Kris , Van Molle Inge , Tommassen Jan , Van Gelder Patrick 
Published: May 2007

SummarySome proteins are so much resistant to proteolysis and unfolding that they violate folding rules shared by the vast majority of proteins. These unusual proteins manage to fold into an active native conformation that is thermodynamically at best marginally, but often even less stable than the unfolded state. A huge energetic barrier traps these proteins kinetically in the folded state. The drawback of this situation is the need for a specialized chaperone that adds steric information to the proteins to cross this barrier on the folding pathway. Until now, our knowledge of these intriguing chaperones was restricted to the prodomains of secreted proteases, which function intramolecularly. Recent research has added more examples, which now include the membrane‐anchored lipase‐specific foldase and the pilus subunit specific chaperone, both acting intermolecularly. The case of the pilin chaperone is somewhat deviant in that steric information is definitely provided, but the pilus subunit adopts a thermodynamically favourable stable conformation.
A haem cofactor is required for redox and light signalling by the AppA protein of Rhodobacter sphaeroides
Authors: Han Yuchen , Meyer Martin H. F. , Keusgen Michael , Klug Gabriele 
Published: May 2007

SummaryThe AppA protein of Rhodobacter sphaeroides is unique in its ability to sense and transmit redox signals as well as light signals. By functioning as antagonist to the PpsR transcriptional repressor, it regulates the expression of photosynthesis genes in response to these environmental stimuli. Here we show binding of the cofactor haem to a domain in the C‐terminal part of AppA and redox activity of bound haem. This is supported by the findings that: (i) the C‐terminal domain of AppA (AppAΔN) binds to haemin agarose, (ii) AppAΔN isolated from Escherichia coli shows absorbance at 411 nm and absorbances at 424 nm and 556 nm after reduction with dithionite and (iii) AppAΔN can be reconstituted with haem in vitro. Expression of AppA variants in R. sphaeroides reveals that the haem binding domain is important for normal expression levels of photosynthesis genes and for normal light regulation in the presence of oxygen. The haem cofactor affects the interaction of the C‐terminal part of AppA to PpsR but also its interaction to the N‐terminal light sensing AppA‐BLUF domain. Based on this we present a model for the transmission of light and redox signals by AppA.
Identification of a region of FtsA required for interaction with FtsZ
Authors: Pichoff Sebastien , Lutkenhaus Joe 
Published: May 2007

SummaryThe assembly of the Z ring is the earliest step in bacterial cell division. In Escherichia coli this assembly requires either FtsA or ZipA which bind to a conserved, C‐terminal 17 amino acid motif in FtsZ and to the membrane. The FtsZ–ZipA interaction is well characterized; however, nothing is known about the region of FtsA involved in the interaction with FtsZ even though the FtsA–FtsZ interaction is nearly ubiquitous in Eubacteria. FtsA is proposed to bind to the membrane through its conserved C‐terminal amphiphatic helix before efficiently interacting with FtsZ. Based upon this model we designed a genetic screen to identify mutants specifically impaired for the FtsA–FtsZ interaction. The mutants obtained retain the ability to be targeted to the membrane but fail to be recruited to the Z ring or interact with FtsZ in the yeast two‐hybrid system. These mutants do not complement an ftsA‐depletion strain. Through this approach we have identified a region of FtsA containing some invariant residues which is required for binding to FtsZ. The results support our model that FtsA is targeted to the membrane before it interacts with FtsZ and demonstrates that this interaction plays an essential role in E. coli cell division.
Interaction of nitrogen nutrition and salinity in Grey poplar (Populus tremula × alba)
Authors: EHLTING B. , DLUZNIEWSKA P. , DIETRICH H. , SELLE A. , TEUBER M. , HÄNSCH R. , NEHLS U. , POLLE A. , SCHNITZLER J.‐P. , RENNENBERG H. , GESSLER A. 
Published: May 2007

ABSTRACTSalinity represents an increasing environmental problem in managed ecosystems. Populus spp. is widely used for wood production by short‐rotation forestry in fertilized plantations and can be grown on saline soil. Because N fertilization plays an important role in salt tolerance, we analysed Grey poplar (Populus tremula × alba, syn. Populus canescens) grown with either 1 mM nitrate or ammonium subjected to moderate 75 mM NaCl. The impact of N nutrition on amelioration of salt tolerance was analysed on different levels of N metabolism such as N uptake, assimilation and N (total N, proteins and amino compounds) accumulation. Na concentration increased in all tissues over time of salt exposure. The N nutrition‐dependent effects of salt exposure were more intensive in roots than in leaves. Application of salt reduced root increment as well as stem height increase and, at the same time, increased the concentration of total amino compounds more intensively in roots of ammonium‐fed plants. In leaves, salt treatment increased concentrations of total N more intensively in nitrate‐fed plants and concentrations of amino compounds independently of N nutrition. The major changes in N metabolism of Grey poplar exposed to moderate salt concentrations were detected in the significant increase of amino acid concentrations. The present results indicate that N metabolism of Grey poplar exposed to salt performed better when the plants were fed with nitrate instead of ammonium as sole N source. Therefore, nitrate fertilization of poplar plantations grown on saline soil should be preferred.
During measurements of root hydraulics with pressure probes, the contribution of unstirred layers is minimized in the pressure relaxation mode: comparison with pressure clamp and high‐pressure flowmeter
Authors: KNIPFER THORSTEN , DAS DEBASISH , STEUDLE ERNST 
Published: May 2007

ABSTRACTThe effects of unstirred layers (USLs) at the endodermis of roots of young maize plants (Zea mays L.) were quantified, when measuring the water permeability of roots using a root pressure probe (RPP) in the pressure relaxation (PR) and pressure clamp (PC) modes. Different from PRs, PCs were performed by applying a constant pressure for certain periods of time. Experimental data were compared with results from simulations based on a convection versus diffusion (C/D) model, with the endodermis being the main barrier for solutes and water. Solute profiles in the stele were calculated as they occurred during rapid water flows across the root. The model quantitatively predicted the experimental finding of two distinct phases during PRs, in terms of a build‐up of concentration profiles in the stele between endodermis and xylem vessels. It also predicted that, following a PC, half‐times (T1/2) of PRs increased as the time used for clamping (and the build‐up of USLs) increased. Following PCs of durations of 15, 30 and 60 s, T1/2 increased by factors of between 2.5 and 7.0, and water permeability of roots (root hydraulic conductivity, Lpr) was reduced by the same factors. When root pressure was immediately taken back to the original equilibrium root pressure following a PC, there was a transient uptake of water into the root stele (transient increase of root pressure), and the size of transients rose with time of clamping, as predicted by the model. The results indicated that the ‘real’ hydraulic conductivity of roots should be measured during initial water flows, such as during the rapid phase of PRs, when the effect of USLs was minimized. It was discussed that ‘pressure‐propagation effects’ could not explain the finding of two phases during PRs. The results of USL effects threw some doubt on the use of PC and high‐pressure flowmeter (HPFM) techniques with roots, where rigorous estimates of USLs were still missing despite the fact that large quantities of water were forced across the root.
Timing of cotyledon damage affects growth and flowering in mature plants
Authors: HANLEY M. E. , FEGAN E. L. 
Published: May 2007

ABSTRACTAlthough the effects of herbivory on plant fitness are strongly linked to age, we understand little about how the timing of herbivory at the seedling stage affects growth and reproduction for plants that survive attack. In this study, we subjected six north‐western European, dicotyledonous grassland species (Leontodon autumnalis, Leontodon hispidus, Plantago lanceolata, Plantago major, Trifolium pratense and Trifolium repens) to cotyledon removal at 7, 14 and 21 d old. We monitored subsequent growth and flowering (number of inflorescences recorded, and time taken for first flowers to open) over a 107 d period. Cotyledon removal reduced growth during establishment (35 d) for all species, and a further three exhibited reduced growth at maturity. Four species developed fewer inflorescences, or had delayed flowering after cotyledon removal. Although early damage (7 d old) had the greatest long‐term effect on plant performance, responses varied according to the age at which the damage occurred and the species involved. Our results illustrate how growth and flowering into the mature phase is affected by cotyledon damage during different stages of seedling ontogeny, and we highlight the ways in which ontogenetic variation in seedling tolerance of tissue loss might impact upon plant fitness in mature plant communities.
Orthologous comparison in a gene‐rich region among grasses reveals stability in the sugarcane polyploid genome
Authors: Jannoo Nazeema , Grivet Laurent , Chantret Nathalie , Garsmeur Olivier , Glaszmann Jean Christophe , Arruda Paulo , D’Hont Angélique 
Published: May 2007

SummaryModern sugarcane (Saccharum spp.) is an important grass that contributes 60% of the raw sugar produced worldwide and has a high biofuel production potential. It was created about a century ago through hybridization of two highly polyploid species, namely S. officinarum and S. spontaneum. We investigated genome dynamics in this highly polyploid context by analyzing two homoeologous sequences (97 and 126 kb) in a region that has already been studied in several cereals. Our findings indicate that the two Saccharum species diverged 1.5–2 million years ago from one another and 8–9 million years ago from sorghum. The two sugarcane homoeologous haplotypes show perfect colinearity as well as high gene structure conservation. Apart from the insertion of a few retrotransposable elements, high homology was also observed for the non‐transcribed regions. Relative to sorghum, the sugarcane sequences displayed colinearity, with the exception of two genes present only in sorghum, and striking homology in most non‐coding parts of the genome. The gene distribution highlighted high synteny and colinearity with rice, and partial colinearity with each homoeologous maize region, which became perfect when the sequences were combined. The haplotypes observed in sugarcane may thus closely represent the ancestral Andropogoneae haplotype. This analysis of sugarcane haplotype organization at the sequence level suggests that the high ploidy in sugarcane did not induce generalized reshaping of its genome, thus challenging the idea that polyploidy quickly induces generalized rearrangement of genomes. These results also confirm the view that sorghum is the model of choice for sugarcane.
TECHNICAL NOTES ON CPP: Amygdala cannulation alters expression of cocaine conditioned place preference and locomotion in rats
Authors: Herzig Volker , Schmidt Werner J. 
Published: May 2007

ABSTRACTThe effect of transient inactivation of the amygdala on expression of cocaine conditioned place preference (CPP) and locomotion was studied. We found that rats with bilateral but not unilateral amygdala cannula placement exhibited increased CPP expression during a vehicle and a cocaine test as well as increased cocaine‐induced hyper‐locomotion. We discuss the observed effects as being caused by the cannulation per se and we conclude that the applied cannulation produced an increased responsiveness of the amygdala by a yet undetermined mechanism.
ORIGINAL INVESTIGATIONS ON CPP: Effects of scopolamine on morphine‐induced conditioned place preference in mice
Authors: Tan Hua , Liu Ning , Wilson Fraser A. W. , Ma Yuanye 
Published: May 2007

ABSTRACTIt is well known that the cholinergic system plays a crucial role in learning and memory. Psychopharmacological studies in humans and animals have shown that a systemic cholinergic blockade may induce deficits in learning and memory. Accumulated studies have indicated that learning and memory play an important role in drug addition. In the present study, in order to get a further understanding about the functions of the cholinergic system in drug‐related learning and memory, we examined the effects of scopolamine (0.5, 1.0 and 2.0 mg/kg) on morphine‐induced conditioned place preference (CPP). Two kinds of morphine exposure durations (4 days and 12 days) were used. The main finding was that all doses of scopolamine enhanced the extinction of morphine‐induced CPP in mice treated with morphine for 12 days. However, in mice treated with morphine for 4 days, all doses of scopolamine did not inhibit morphine‐induced CPP. The highest dose (2.0 mg/kg) of scopolamine even significantly delayed the extinction of morphine‐induced CPP. Our results suggest that the effects of a systemic cholinergic blockade on morphine‐induced CPP depend on the morphine exposure time.
Traumatic life events in bipolar disorder: impact on BDNF levels and psychopathology
Authors: Kauer‐Sant'Anna Marcia , Tramontina Juliana , Andreazza Ana Cristina , Cereser Keila , Costa Sabrina da , Santin Aida , Yatham Lakshmi N , Kapczinski Flavio 
Published: May 2007

Background:  There is evidence that vulnerability to depression and anxiety disorders is markedly increased by traumatic life events. While childhood abuse has been reported to be associated with poorer outcomes in bipolar disorder, little is known about the neurobiological basis underlying this association. The aim of this study was to ascertain whether bipolar patients who were exposed to a traumatic event or events (TE) have lower brain‐derived neurotrophic factor (BDNF) levels and more severe psychopathology as indicated by increased comorbidity and other clinical features when compared to those who were not exposed to TE.Methods:  One‐hundred and sixty‐three consecutively recruited bipolar outpatients were assessed by Structured Clinical Interview for DSM‐IV (SCID) and standard protocol in order to evaluation psychopathology and clinical features. The reported TE was assessed using DSM‐IV stem criteria for trauma (as defined by A1 and A2 criteria for trauma for post‐traumatic stress disorder). Subjects were divided into 2 groups according to presence or absence of lifetime TE. The levels of BDNF, comorbidity and other clinical features were compared between groups.Results:  After adjusting for confounders, results indicated that bipolar patients with a history of TE have alcohol abuse/dependence (p < 0.001), anxiety comorbidity, and lower levels of serum BDNF (p < 0.01) compared to those without a history of TE. There was no difference between the 2 groups in age of onset, presence of psychosis, other substance abuse and dependence, rapid cycling or suicide attempts.Conclusions:  Our findings suggest that TE are associated with significantly increased prevalence of alcohol and anxiety comorbidity as well as lower BDNF levels in bipolar patients. It is possible that a decrease in BDNF levels may account for increased comorbidity, but further prospective studies are required to confirm this.
Impaired verbal memory and otherwise spared cognition in remitted bipolar patients on monotherapy with lithium or valproate
Authors: Senturk Vesile , Goker Ceren , Bilgic Ayhan , Olmez Senay , Tugcu Handan , Oncu Bedriye , Cem Atbasoglu E 
Published: May 2007

Objectives:  Patients with bipolar disorder have been reported to have neurocognitive deficits; however, it is not known whether the cognitive dysfunctions are state‐dependent or a stable trait. Lithium and valproate, 2 of the most widely used mood stabilizers in the treatment of bipolar disorder, have also been associated with cognitive impairment. However, the degree and pattern of neurocognitive impairment in euthymic bipolar patients on either monotherapy with lithium or valproate have not been compared before in depth.Methods:  We compared 17 euthymic outpatients with bipolar disorder (BD) on lithium monotherapy to 11 euthymic outpatients with BD on valproate monotherapy and 29 comparison subjects using tests measuring immediate verbal memory and executive functions in addition to 3 subtests of the Wechsler Adult Intelligence Scale Revised. The groups were similar in terms of level of education, duration and severity of illness, and gender distribution. Patients on lithium monotherapy were older than patients on valproate and healthy controls. Mood symptoms as assessed by standardized scales were mild to non‐existent in both patient groups.Results:  Immediate verbal memory was impaired in both patient groups compared to controls, where the main effect of age was not significant. No significant differences could be found on the other cognitive measures.Conclusions:  Both lithium and valproate may be associated with immediate verbal memory impairment, sparing other cognitive functions. Presence of a similar verbal memory deficit in the lithium and valproate groups suggests that this deficit might be intrinsic to BD or that the 2 medications influence immediate verbal memory similarly. Larger samples of remitted bipolar patients on monotherapy should be studied for more precise conclusions.