bluuebunny/crossref_metadata_2025_split huggingface dataset:
A β-Tubulin Mutation Selectively Uncouples Nuclear Division and Cytokinesis in
Tetrahymena thermophila
Authors: Smith Joshua J. , Yakisich J. Sebastian , Kapler Geoffrey M. , Cole Eric S. , Romero Daniel P. 
Published: October 2004

ABSTRACT

The ciliated protozoan
Tetrahymena thermophila
contains two distinct nuclei within a single cell—the mitotic micronucleus and the amitotic macronucleus. Although microtubules are required for proper division of both nuclei, macronuclear chromosomes lack centromeres and the role of microtubules in macronuclear division has not been established. Here we describe nuclear division defects in cells expressing a mutant β-tubulin allele that confers hypersensitivity to the microtubule-stabilizing drug paclitaxel. Macronuclear division is profoundly affected by the
btu1
-
1
(K350M) mutation, producing cells with widely variable DNA contents, including cells that lack macronuclei entirely. Protein expressed by the
btu1
-
1
allele is dominant over wild-type protein expressed by the
BTU2
locus. Normal macronuclear division is restored when the
btu1
-
1
allele is inactivated by targeted disruption or expressed as a truncated protein. Immunofluorescence studies reveal elongated microtubular structures that surround macronuclei that fail to migrate to the cleavage furrows. In contrast, other cytoplasmic microtubule-dependent processes, such as cytokinesis, cortical patterning, and oral apparatus assembly, appear to be unaffected in the mutant. Micronuclear division is also perturbed in the K350M mutant, producing nuclei with elongated early-anaphase spindle configurations that persist well after the initiation of cytokinesis. The K350M mutation affects tubulin dynamics, as the macronuclear division defect is exacerbated by three treatments that promote microtubule polymerization: (i) elevated temperatures, (ii) sublethal concentrations of paclitaxel, and (iii) high concentrations of dimethyl sulfoxide. Inhibition of phosphatidylinositol 3-kinase (PI 3-kinase) with 3-methyladenine or wortmannin also induces amacronucleate cell formation in a
btu1
-
1
-dependent manner. Conversely, the myosin light chain kinase inhibitor ML-7 has no effect on nuclear division in the
btu1
-
1
mutant strain. These findings provide new insights into microtubule dynamics and link the evolutionarily conserved PI 3-kinase signaling pathway to nuclear migration and/or division in
Tetrahymena
.
Linkage between Mitochondrial Hypovirulence and Viral Hypovirulence in the Chestnut Blight Fungus Revealed by cDNA Microarray Analysis
Authors: Allen Todd D. , Nuss Donald L. 
Published: October 2004

ABSTRACT

The phenomenon of transmissible hypovirulence (virulence attenuation) associated with biological control of natural populations of the chestnut blight fungus
Cryphonectria parasitica
can be experimentally reproduced by infection with hypovirus cDNA clones (viral hypovirulence) or by mutation of mitochondrial DNA (mtDNA) in the absence of virus infection (mitochondrial hypovirulence). We now report the use of an established
C. parasitica
cDNA microarray to monitor nuclear transcriptional responses to an mtDNA mutation of
C. parasitica
strain EP155, designated EP155/
mit2
, which was previously shown to induce elevated alternative oxidase activity and hypovirulence (C. B. Monterio-Vitorello, J. A. Bell, D. W. Fulbright, and H. A. Bertrand, Proc. Natl. Acad. Sci. USA
92:
5935-5939, 1995). Approximately 10% of the 2,200 genes represented on the microarray exhibited altered transcript accumulation as a result of the
mit2
mtDNA mutation. While genes involved in mitochondrial function were clearly represented in the EP155/
mit2
-responsive gene list, direct parallels to the well-characterized
Saccharomyces cerevisiae
retrograde response to mitochondrial dysfunction were not observed. Remarkably, 47% of the genes that were differentially expressed following the infection of strain EP155 by the prototypic hypovirus CHV1-EP713 had similarly changed transcript accumulation in the virus-free EP155/
mit2
mutant. These results establish a linkage between viral and mitochondrial hypovirulence and raise questions regarding the relationship between hypovirus infection and mitochondrial dysfunction. The combined set of transcriptional profile data provides a foundation for future studies on mitochondrion-to-nucleus communications in the context of hypovirus infection and senescence associated with mitochondrial dysfunction in filamentous fungi.
Control of Cell Type Proportioning in
Dictyostelium discoideum
by Differentiation-Inducing Factor as Determined by In Situ Hybridization
Authors: Maruo Toshinari , Sakamoto Haruyo , Iranfar Negin , Fuller Danny , Morio Takahiro , Urushihara Hideko , Tanaka Yoshimasa , Maeda Mineko , Loomis William F. 
Published: October 2004

ABSTRACT

We have determined the proportions of the prespore and prestalk regions in
Dictyostelium discoideum
slugs by in situ hybridization with a large number of prespore- and prestalk-specific genes. Microarrays were used to discover genes expressed in a cell type-specific manner. Fifty-four prespore-specific genes were verified by in situ hybridization, including 18 that had been previously shown to be cell type specific. The 36 new genes more than doubles the number of available prespore markers. At the slug stage, the prespore genes hybridized to cells uniformly in the posterior 80% of wild-type slugs but hybridized to the posterior 90% of slugs lacking the secreted alkylphenone differentiation-inducing factor 1 (DIF-1). There was a compensatory twofold decrease in prestalk cells in DIF-less slugs. Removal of prespore cells resulted in cell type conversion in both wild-type and DIF-less anterior fragments. Thus, DIF-1 appears to act in concert with other processes to establish cell type proportions.
Identification of
Cryptococcus neoformans
Temperature-Regulated Genes with a Genomic-DNA Microarray
Authors: Kraus Peter R. , Boily Marie-Josée , Giles Steven S. , Stajich Jason E. , Allen Andria , Cox Gary M. , Dietrich Fred S. , Perfect John R. , Heitman Joseph 
Published: October 2004

ABSTRACT

The
ability to survive and proliferate at 37°C is an essential
virulence attribute of pathogenic microorganisms. A partial-genome
microarray was used to profile gene expression in the human-pathogenic
fungus
Cryptococcus neoformans
during growth at
37°C. Genes with orthologs involved in stress responses were
induced during growth at 37°C, suggesting that a conserved
transcriptional program is used by
C. neoformans
to
alter gene expression during stressful conditions. A gene encoding the
transcription factor homolog Mga2 was induced at 37°C and found
to be important for high-temperature growth. Genes encoding fatty acid
biosynthetic enzymes were identified as potential targets of Mga2,
suggesting that membrane remodeling is an important component of
adaptation to high growth temperatures.
mga2Δ
mutants
were extremely sensitive to the ergosterol synthesis inhibitor
fluconazole, indicating a coordination of the synthesis of membrane
component precursors. Unexpectedly, genes involved in amino acid and
pyrimidine biosynthesis were repressed at 37°C, but components
of these pathways were found to be required for high-temperature
growth. Our findings demonstrate the utility of even partial-genome
microarrays for delineating regulatory cascades that contribute to
microbial
pathogenesis.
PP2A Phosphatase Activity Is Required for Stress and Tor Kinase Regulation of Yeast Stress Response Factor Msn2p
Authors: Santhanam Arti , Hartley Alan , Düvel Katrin , Broach James R. , Garrett Stephen 
Published: October 2004

ABSTRACT

In response to stress and nutrient starvation, the
Saccharomyces cerevisiae
transcription factor Msn2p accumulates in the nucleus and activates expression of a broad array of genes. Here, we analyze the role of the Tor (target of rapamycin) signaling pathway in mediating these responses. Inactivation of the Tor pathway component Tap42p using
tap42
(Ts) alleles causes a sustained nuclear localization similar to that after the addition of the Tor kinase inhibitor rapamycin. Effects of Tap42p inactivation and rapamycin addition could be suppressed by deletion of
TIP41
, which encodes a Tap42p-interacting protein. These results support the notion that rapamycin affects Msn2p by inactivating Tap42p function. Tap42p interacts with the catalytic subunit of PP2A (protein phosphatase 2A) and PP2A-like phosphatases. Deletion of either the catalytic or regulatory subunit that forms the PP2A phosphatase complex prevents nuclear accumulation of Msn2p in the
tap42
(Ts) strain and in wild-type strains treated with rapamycin. These results suggest that Tap42p is an inhibitor of PP2A phosphatase, which in turn inhibits nuclear export of Msn2p. Interestingly, PP2A function is also required for nuclear accumulation of Msn2p in response to stresses, such as heat and osmotic shock, as well as nitrogen (but not glucose) starvation. Thus, PP2A and the Tor kinase pathway transduce stress and nitrogen starvation signals to Msn2p. Finally, Msn2p localization is unaffected by conditional loss of 14-3-3 protein function, ruling out the possibility that 14-3-3 proteins act as a scaffold to sequester Msn2p in the cytoplasm.
Regulation of Flagellar Assembly by Glycogen Synthase Kinase 3 in
Chlamydomonas reinhardtii
Authors: Wilson Nedra F. , Lefebvre Paul A. 
Published: October 2004

ABSTRACT

Chlamydomonas reinhardtii
controls flagellar assembly such that flagella are of an equal and predetermined length. Previous studies demonstrated that lithium, an inhibitor of glycogen synthase kinase 3 (GSK3), induced flagellar elongation, suggesting that a lithium-sensitive signal transduction pathway regulated flagellar length (S. Nakamura, H. Takino, and M. K. Kojima, Cell Struct. Funct.
12:
369-374, 1987). Here, we demonstrate that lithium treatment depletes the pool of flagellar proteins from the cell body and that the heterotrimeric kinesin Fla10p accumulates in flagella. We identify GSK3 in
Chlamydomonas
and demonstrate that its kinase activity is inhibited by lithium in vitro. The tyrosine-phosphorylated, active form of GSK3 was enriched in flagella and GSK3 associated with the axoneme in a phosphorylation-dependent manner. The level of active GSK3 correlated with flagellar length; early during flagellar regeneration, active GSK3 increased over basal levels. This increase in active GSK3 was rapidly lost within 30 min of regeneration as the level of active GSK3 decreased relative to the predeflagellation level. Taken together, these results suggest a possible role for GSK3 in regulating the assembly and length of flagella.
TheToxoplasma gondiiRhoptry Protein ROP4 Is Secreted into the Parasitophorous Vacuole and Becomes Phosphorylated in Infected Cells
Authors: Carey Kimberly L. , Jongco Artemio M. , Kim Kami , Ward Gary E. 
Published: October 2004

ABSTRACTMany intracellular pathogens are separated from the cytosol of their host cells by a vacuole membrane. This membrane serves as a critical interface between the pathogen and the host cell, across which nutrients are imported, wastes are excreted, and communication between the two cells takes place. Very little is known about the vacuole membrane proteins mediating these processes in any host-pathogen interaction. During a screen for monoclonal antibodies against novel surface or secreted proteins ofToxoplasma gondii, we identified ROP4, a previously uncharacterized member of the ROP2 family of proteins. We report here on the sequence, posttranslational processing, and subcellular localization of ROP4, a type I transmembrane protein. Mature, processed ROP4 is localized to the rhoptries, secretory organelles at the apical end of the parasite, and is secreted from the parasite during host cell invasion. Released ROP4 associates with the vacuole membrane and becomes phosphorylated in the infected cell. Similar results are seen with ROP2. Further analysis of ROP4 showed it to be phosphorylated on multiple sites, a subset of which result from the action of either host cell protein kinase(s) or parasite kinase(s) activated by host cell factors. The localization and posttranslational modification of ROP4 and other members of the ROP2 family of proteins within the infected cell make them well situated to play important roles in vacuole membrane function.
CbfA, the C-Module DNA-Binding Factor, Plays an Essential Role in the Initiation of
Dictyostelium discoideum
Development
Authors: Winckler Thomas , Iranfar Negin , Beck Peter , Jennes Ingo , Siol Oliver , Baik Unha , Loomis William F. , Dingermann Theodor 
Published: October 2004

ABSTRACT

We recently isolated from
Dictyostelium discoideum
cells a DNA-binding protein, CbfA, that interacts in vitro with a regulatory element in retrotransposon TRE5-A. We have generated a mutant strain that expresses CbfA at <5% of the wild-type level to characterize the consequences for
D. discoideum
cell physiology. We found that the multicellular development program leading to fruiting body formation is highly compromised in the mutant. The cells cannot aggregate and stay as a monolayer almost indefinitely. The cells respond properly to prestarvation conditions by expressing discoidin in a cell density-dependent manner. A genomewide microarray-assisted expression analysis combined with Northern blot analyses revealed a failure of CbfA-depleted cells to induce the gene encoding aggregation-specific adenylyl cyclase ACA and other genes required for cyclic AMP (cAMP) signal relay, which is necessary for aggregation and subsequent multicellular development. However, the
cbfA
mutant aggregated efficiently when mixed with as few as 5% wild-type cells. Moreover, pulsing
cbfA
mutant cells developing in suspension with nanomolar levels of cAMP resulted in induction of
acaA
and other early developmental genes. Although the response was less efficient and slower than in wild-type cells, it showed that cells depleted of CbfA are able to initiate development if given exogenous cAMP signals. Ectopic expression of the gene encoding the catalytic subunit of protein kinase A restored multicellular development of the mutant. We conclude that sensing of cell density and starvation are independent of CbfA, whereas CbfA is essential for the pattern of gene expression which establishes the genetic network leading to aggregation and multicellular development of
D. discoideum
.
Firearm related deaths: the impact of regulatory reform
Authors: Ozanne-Smith J , Ashby K , Newstead S , Stathakis V Z , Clapperton A 
Published: October 2004

Objectives:To examine trends in rates of firearm related deaths in Victoria, Australia, over 22 years in the context of legislative reform and describe and investigate impact measures to explain trends.Design:Mortality data were extracted from vital statistics for 1979–2000. Data on firearm related deaths that were unintentional deaths, assaults, suicides, and of undetermined intent were analyzed. Rates were calculated with population data derived from estimates by the Australian Bureau of Statistics. A quasi-experimental design that used a Poisson regression model was adopted to compare relative rates of firearm related deaths for Victoria and the rest of Australia over three critical periods of legislative reform. The Wilcoxon signed ranks test was used to assess changes in the types of firearm related deaths before and after 1998.Results:In Victoria, two periods of legislative reform related to firearms followed mass shooting events in 1988 and 1996. A national firearm amnesty and buyback scheme followed the latter. Victorian and Australian rates of firearm related deaths before reforms (1979–86) were steady. After initial Victorian reforms, a significant downward trend was seen for numbers of all firearm related deaths between 1988 and 1995 (17.3% in Victoria compared with the rest of Australia, p<0.0001). A further significant decline between 1997 and 2000 followed the later reforms. After the later all state legislation, similar strong declines occurred in the rest of Australia from 1997 (14.0% reduction compared with Victoria, p = 0.0372). Victorian reductions were observed in frequencies of firearm related suicides, assaults, and unintentional deaths before and after the 1988 reforms, but statistical significance was reached only for suicide.Conclusion:Dramatic reductions in overall firearm related deaths and particularly suicides by firearms were achieved in the context of the implementation of strong regulatory reform.
What makes community based injury prevention work? In search of evidence of effectiveness
Authors: Nilsen P 
Published: October 2004

Community based injury prevention work has become a widely accepted strategy among safety promotion specialists. Hundreds of community based injury prevention programs have been implemented since the mid-1970s, but relatively few have been evaluated rigorously, resulting in a lack of consensus regarding the effectiveness of this approach. This study sought to identify key components that contribute to the effectiveness of these programs. The objective was to gain a better understanding of the community based model for injury prevention. The study was performed as a structured review of existing evaluations of injury prevention programs that employed multiple strategies to target different age groups, environments, and situations.The results of this study suggested that there are complex relationships between the outcome and the context, structure, and process of community-wide injury prevention programs. The interconnectedness of these variables made it difficult to provide solid evidence to prioritise in terms of program effectiveness. The evaluations of multifaceted community oriented injury prevention programs were found to have many shortcomings. Meagre descriptions of community characteristics and conditions, insufficient assessment of structural program components, and failure to establish process-outcome relationships contributed to the difficulty of identifying key success factors of the programs.
Internists’ attitudes towards terminal sedation in end of life care
Authors: Kaldjian L C , Jekel J F , Bernene J L , Rosenthal G E , Vaughan-Sarrazin M , Duffy T P 
Published: October 2004

Objective:To describe the frequency of support for terminal sedation among internists, determine whether support for terminal sedation is accompanied by support for physician assisted suicide (PAS), and explore characteristics of internists who support terminal sedation but not assisted suicide.Design:A statewide, anonymous postal survey.Setting:Connecticut, USA.Participants:677 Connecticut members of the American College of Physicians.Measurements:Attitudes toward terminal sedation and assisted suicide; experience providing primary care to terminally ill patients; demographic and religious characteristics.Results:78% of respondents believed that if a terminally ill patient has intractable pain despite aggressive analgesia, it is ethically appropriate to provide terminal sedation (diminish consciousness to halt the experience of pain). Of those who favoured terminal sedation, 38% also agreed that PAS is ethically appropriate in some circumstances. Along a three point spectrum of aggressiveness in end of life care, the plurality of respondents (47%) were in the middle, agreeing with terminal sedation but not with PAS. Compared with respondents who werelessaggressive ormoreaggressive, physicians in this middle group were more likely to report having more experience providing primary care to terminally ill patients (p = 0.02) and attending religious services more frequently (p<0.001).Conclusions:Support for terminal sedation was widespread in this population of physicians, and most who agreed with terminal sedation did not support PAS. Most internists who support aggressive palliation appear likely to draw an ethical line between terminal sedation and assisted suicide.
Non-attendance at clinic: cycles of audit of a consultant based gastroenterology outpatient department
Authors: Bateson M C 
Published: October 2004

Abstract
Attempts were made to reduce defaulting rates for new appointments to see a consultant in a general medical and gastroenterology clinic. Despite optimising the operation of the clinic, the non-attendance rate remained unsatisfactory, and comparable to the average for the NHS. There were short term improvements in defaulting rates, which appeared to result from extraneous factors such as a general election and moving to new buildings. Though efforts to improve attendance rates seem appropriate to conserve resources, no definite recommendations can be made on the results of this study.
Paediatric liver transplantation: the surgical view
Authors: Vilca-Melendez H , Heaton N D 
Published: October 2004

Abstract
Liver transplantation is the accepted treatment for a wide variety of liver diseases in children. Over the past 10 years a number of innovative surgical techniques have been developed to overcome the shortage of size matched donors particularly in children less than 5 years of age. Graft and patient survival at one year after liver transplantation has continued to improve, and is now over 85% and higher for good risk cases. Complications are relatively common, but provided graft function is satisfactory, long term survival for these children is to be expected. The need for retransplantation has fallen significantly. Causes of early mortality include graft dysfunction and sepsis. Late mortality is due to sepsis, post-transplant lymphoproliferative disease, and non-compliance. Long term survival with good graft function and excellent quality of life is possible for the majority of children undergoing liver transplantation.
New drugs for the treatment of epilepsy: a practical approach
Authors: Beyenburg S , Bauer J , Reuber M 
Published: October 2004

AbstractThe availability of new antiepileptic drugs has broadened the spectrum of medical treatment options in epilepsy. The new agents, together with established drugs, offer substantial choice for doctors treating patients with focal or generalised epilepsy. The newer antiepileptic drugs are not necessarily more effective but usually better tolerated than the traditional agents, mainly because of favourable pharmacokinetic profiles and fewer interactions. Because treatment options have increased, drug therapy can now be tailored to the requirements of individual patients. Nevertheless, significant safety and efficacy issues continue to exist and there is a need for the development of even better agents. This review describes the clinical use of the new antiepileptic drugs, but focuses in particular on monotherapy, the treatment of generalised seizures, teratogenicity, and the cognitive side effect profile of the newer compounds.
ON ADAPTIVE SYNCHRONIZATION AND CONTROL OF NONLINEAR DYNAMICAL SYSTEMS
Authors: WU CHAI WAH , YANG TAO , CHUA LEON O. 
Published: October 2004

In this paper, we study the synchronization of two coupled nonlinear, in particular chaotic, systems which are not identical. We show how adaptive controllers can be used to adjust the parameters of the systems such that the two systems will synchronize. We use a Lyapunov function approach to prove a global result which shows that our choice of controllers will synchronize the two systems. We show how it is related to Huberman-Lumer adaptive control and the LMS adaptive algorithm. We illustrate the applicability of this method using Chua's oscillators as the chaotic systems. We choose parameters for the two systems which are orders of magnitude apart to illustrate the effectiveness of the adaptive controllers. Finally, we discuss the role of adaptive synchronization in the context of secure and spread spectrum communication systems. In particular, we show how several signals can be encoded onto a single scalar chaotic carrier signal.