bluuebunny/crossref_metadata_2025 huggingface dataset:
PKCβ modulates ischemia-reperfusion injury in the heart
Authors: Kong Linghua , Andrassy Martin , Chang Jong Sun , Huang Chun , Asai Tomohiro , Szabolcs Matthias J. , Homma Shunichi , Liu Rui , Zou Yu Shan , Leitges Michael , Yan Shi Du , Ramasamy Ravichandran , Schmidt Ann Marie , Yan Shi-Fang
Published: February 2008

Protein kinase C-βII (PKCβII) is an important modulator of cellular stress responses. To test the hypothesis that PKCβII modulates the response to myocardial ischemia-reperfusion (I/R) injury, we subjected mice to occlusion and reperfusion of the left anterior descending coronary artery. Homozygous PKCβ-null (PKCβ−/−) and wild-type mice fed the PKCβ inhibitor ruboxistaurin displayed significantly decreased infarct size and enhanced recovery of left ventricular (LV) function and reduced markers of cellular necrosis and serum creatine phosphokinase and lactate dehydrogenase levels compared with wild-type or vehicle-treated animals after 30 min of ischemia followed by 48 h of reperfusion. Our studies revealed that membrane translocation of PKCβII in LV tissue was sustained after I/R and that gene deletion or pharmacological blockade of PKCβ protected ischemic myocardium. Homozygous deletion of PKCβ significantly diminished phosphorylation of c-Jun NH2-terminal mitogen-activated protein kinase and expression of activated caspase-3 in LV tissue of mice subjected to I/R. These data implicate PKCβ in I/R-mediated myocardial injury, at least in part via phosphorylation of JNK, and suggest that blockade of PKCβ may represent a potent strategy to protect the vulnerable myocardium.
Regulation of sarcoplasmic reticulum Ca2+reuptake in porcine airway smooth muscle
Authors: Sathish Venkatachalem , Leblebici Figen , Kip Sertac N. , Thompson Michael A. , Pabelick Christina M. , Prakash Y. S. , Sieck Gary C.
Published: February 2008

Regulation of intracellular Ca2+concentration ([Ca2+]i) in airway smooth muscle (ASM) during agonist stimulation involves sarcoplasmic reticulum (SR) Ca2+release and reuptake. The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is key to replenishment of SR Ca2+stores. We examined regulation of SERCA in porcine ASM: our hypothesis was that the regulatory protein phospholamban (PLN) and the calmodulin (CaM)-CaM kinase (CaMKII) pathway (both of which are known to regulate SERCA in cardiac muscle) play a role. In porcine ASM microsomes, we examined the expression and extent of PLN phosphorylation after pharmacological inhibition of CaM (with W-7) vs. CaMKII (with KN-62/KN-93) and found that PLN is phosphorylated by CaMKII. In parallel experiments using enzymatically dissociated single ASM cells loaded with the Ca2+indicator fluo 3 and imaged using fluorescence microscopy, we measured the effects of PLN small interfering RNA, W-7, and KN-62 on [Ca2+]iresponses to ACh and direct SR stimulation. PLN small interfering RNA slowed the rate of fall of [Ca2+]itransients to 1 μM ACh, as did W-7 and KN-62. The two inhibitors additionally slowed reuptake in the absence of PLN. In other cells, preexposure to W-7 or KN-62 did not prevent initiation of ACh-induced [Ca2+]ioscillations (which were previously shown to result from repetitive SR Ca2+release/reuptake). However, when ACh-induced [Ca2+]ioscillations reached steady state, subsequent exposure to W7 or KN-62 decreased oscillation frequency and amplitude and slowed the fall time of [Ca2+]itransients, suggesting SERCA inhibition. Exposure to W-7 completely abolished ongoing ACh-induced [Ca2+]ioscillations in some cells. Preexposure to W-7 or KN-62 did not affect caffeine-induced SR Ca2+release, indicating that ryanodine receptor channels were not directly inhibited. These data indicate that, in porcine ASM, the CaM-CaMKII pathway regulates SR Ca2+reuptake, potentially through altered PLN phosphorylation.
Mesothelin Promotes Anchorage-Independent Growth and Prevents Anoikis via Extracellular Signal-Regulated Kinase Signaling Pathway in Human Breast Cancer Cells
Authors: Uehara Norihisa , Matsuoka Yoichiro , Tsubura Airo
Published: February 2008

Mesothelin (MSLN) is a glycoprotein that is overexpressed in various tumors. MSLN is present on the cell surface and is also released into body fluids or culture supernatants from MSLN-positive tumor cells. Despite intensive study of MSLN as a diagnostic marker or target for immunotherapy, its biological function is largely unknown. In the present study, we examined the effects of ectopic expression of MSLN in human breast cancer cell lines (MCF-7, T47D, and MDA-MB-231). We found that overexpression of MSLN promoted anchorage-independent growth in soft agar. In addition, MDA-MB-231 cells expressing high levels of MSLN exhibited resistance to anoikis (a type of apoptosis induced by detachment from substratum), as indicated by decreased DNA fragmentation and down-regulation of the proapoptotic protein Bim. Incubating MSLN-expressing MDA-MB-231 cells in the presence of U0126, an inhibitor of mitogen-activated protein/extracellular-signal-regulated kinase kinase, induced accumulation of Bim and restored susceptibility to anoikis. Western blot analysis also revealed that overexpression of MSLN resulted in sustained activation of extracellular signal-regulated kinase 1/2 and suppression of Bim. The present results constitute novel evidence that MSLN enables cells to survive under anchorage-independent conditions by suppressing Bim induction via the extracellular signal-regulated kinase signaling pathway. (Mol Cancer Res 2008;6(2):186–93)
Sterol Regulatory Element–Binding Protein-1c Represses the Transactivation of Androgen Receptor and Androgen-Dependent Growth of Prostatic Cells
Authors: Suh Ji Ho , Gong Eun-Yeung , Kim Jae Bum , Lee In-Kyu , Choi Hueng-Sik , Lee Keesook
Published: February 2008

Sterol regulatory element-binding protein-1c (SREBP-1c) is a basic helix-loop-helix transcription factor that plays an important role in lipid homeostasis. Here, we show that SREBP-1c regulates androgen receptor (AR) transactivation through direct interaction with AR and represses androgen-dependent growth of prostatic cells. Transient transfection studies show that SREBP-1c specifically inhibits the transactivation of AR. Chromatin immunoprecipitation assays reveal that SREBP-1c is recruited with AR onto the endogenous AR target promoter. Moreover, adenovirus-mediated overexpression of SREBP-1c decreases the mRNA level of the prostate-specific antigen gene, an endogenous target gene of AR, supporting SREBP-1c modulation of AR transactivation. In vivo and in vitro protein interaction assays show that SREBP-1c directly interacts with AR through the activation function-1 domain of AR. In addition, transfection studies and glutathione S-transferase pull-down competition experiments reveal that the SREBP-1c–mediated repression of AR transactivation is accomplished through competition with certain AR coactivators for AR interaction. The SREBP-1c–mediated inhibition of AR transactivation also involves the recruitment of histone deacetylase 1. Finally, adenovirus-mediated overexpression of SREBP-1c inhibits androgen-induced proliferation of prostatic cells in vitro and in vivo, and small interfering RNA–mediated down-regulation of SREBP-1 enhances androgen-induced proliferation of prostatic cells as well as the transactivation of AR. Taken together, these results suggest that SREBP-1c acts as an AR corepressor and may play an important role in the regulation of AR-dependent prostatic cell growth. (Mol Cancer Res 2008;6(2):314–24)
Latent Mean and Covariance Differences With Measurement Equivalence in College Students With Developmental Difficulties Versus the Wechsler Adult Intelligence Scale–III/Wechsler Memory Scale–III Normative Sample
Authors: Bowden Stephen C. , Gregg Noel , Bandalos Deborah , Davis Mark , Coleman Chris , Holdnack James A. , Weiss Larry G.
Published: February 2008

Intelligence tests are usually part of the assessment battery for the diagnosis of adults with learning disabilities (LD) and attention deficit hyperactivity disorder (ADHD). Professionals must ensure that inferences drawn from such test scores are equivalent across populations with and without disabilities. Examination of measurement equivalence provides a direct test of the hypothesis that the same set of latent variables underlies a set of test scores in different groups and metric relationships between observed scores and the corresponding latent variables are the same. The hypothesis of measurement equivalence was examined in two samples of college students: one sample with LD and one sample with ADHD. Scores on the third editions of the Wechsler Adult Intelligence and Memory Scales were compared with an age-matched subset of the conorming sample. Results supported the assumption of measurement equivalence but revealed marked differences across samples in latent variable variances and covariances and latent variable means.
Standard Errors of Estimated Latent Variable Scores With Estimated Structural Parameters
Authors: Hoshino Takahiro , Shigemasu Kazuo
Published: February 2008

The authors propose a concise formula to evaluate the standard error of the estimated latent variable score when the true values of the structural parameters are not known and must be estimated. The formula can be applied to factor scores in factor analysis or ability parameters in item response theory, without bootstrap or Markov chain Monte Carlo methods. The proposed method is valid when both the number of items and the number of subjects are large. However, simulation results suggest that the proposed method provides valid estimates for standard errors of latent abilities even when the numbers of items and subjects are not large.
The Everyday World of Simulation Modeling
Authors: Sundberg Mikaela
Published: February 2008

This article explores the practice of simulation modeling by investigating how parameterizations are constructed and integrated into existing frameworks. Parameterizations are simplified process descriptions adapted for simulation models. On the basis of a study of meteorological research, the article presents predictive and representative construction as two different ways of developing parameterizations and the trade-offs involved in this work. Because the overall aim in predictive construction is to improve weather forecasts, the most practical solutions are chosen over the best theoretical solutions. In representative construction, the situation is reversed, but while discourse focuses on theory and models, the everyday work is often tied to computer programs. These different ways of construction work are closely related to the role of the simulation models as epistemic or technical objects, and this characterization is also used to compare the results with previous research.
Reconceptualizing the Competition— Cooperation Relationship
Authors: Chen Ming-Jer
Published: February 2008

Although competition and cooperation individually have received much consideration in the strategy field, researchers have given little attention to the fundamental issue of interplay between the two concepts. Nor has a framework been proposed for examining how competition and cooperation interrelate. Given the notion that competition and cooperation exist in a paradoxical, either/or relationship, reexamination of the idea of paradox itself is imperative. This paper converges Western and Eastern ideas to address the need to transcend conventional perspectives of paradox. It proposes a new concept, transparadox, a hybrid of the either/or and both/and perspectives that characterize, respectively, Western and Eastern thought. The transparadox perspective provides an expansive framework within which the range of competition—cooperation interrelationships may be examined. The introduction of three conceptions of competition—cooperation relationships (independent, or binary, opposites; interconnected opposites; and interdependent opposites) provides researchers with platforms for future theoretical development and empirical study.
Toward a Further Understanding of the Relationships Between Perceptions of Support and Work Attitudes
Authors: Ng Thomas W. H. , Sorensen Kelly L.
Published: February 2008

This study (a) compared the effect of perceived supervisor support (PSS) and perceived coworker support (PCS) on work attitudes; (b) examined the moderating role of gender, tenure, and job type in the support—attitude relationship; and (c) tested a theoretical model hypothesizing relationships among PCS, PSS, perceived organizational support, and work attitudes. In a meta-analysis, PSS was found to be more strongly related to job satisfaction (.52 vs. .37), affective commitment (.48 vs. .28), and turnover intention (—.36 vs. —.19) than was PCS. Further, job type (customer-contact vs. non-customer-contact jobs) was found to be a significant moderator. Finally, the proposed model received empirical support. Different forms of support were closely related to work attitudes and to each other. Implications for research on social support are discussed.
Validation of the Treatment Motivation Scales for Forensic Outpatient Treatment (TMS-F)
Authors: Drieschner Klaus H. , Boomsma Anne
Published: February 2008

The validity of the Treatment Motivation Scales for outpatient offender treatment (TMS-F), a self-report questionnaire with scales for the motivation of patients to engage in the treatment and six cognitive and emotional determinants of this motivation, is evaluated in two studies. In Study 1 (N = 620), the construct validity of the TMS-F is investigated applying a multitrait-multimethod design with a therapist-rating instrument as the criterion method. All scales were found to have adequate convergent validity and acceptable discriminant validity. In Study 2 (N = 328), the criterion validity of the TMS-F is addressed. Applying covariance structure analysis, the instrument is found to predict therapist ratings of the treatment engagement of patients to a substantial degree. Treatment engagement is best predicted by the scales for Motivation to Engage in the Treatment and Perception of the Suitability of the Treatment and not by the scales for Distress and the Perceived Legal Pressure.
PLUNC is a secreted product of neutrophil granules
Authors: Bartlett Jennifer A , Hicks Benjamin J , Schlomann Jamie M , Ramachandran Shyam , Nauseef William M , McCray Paul B
Published: February 2008

Airway epithelia and neutrophils are frequently recruited to release host defense factors in response to a variety of pulmonary pathogens. One abundant product of airway epithelia is palate, lung, nasal epithelium clone (PLUNC), a proposed innate immune protein expressed in submucosal glands and surface airway epithelia. In this study, we report the expression of PLUNC in human neutrophils, a previously unrecognized source of this protein. Immunoblots performed on polymorphonuclear cell (PMN) lysates and PMN subcellular fractions indicated that PLUNC was present in the specific granules of the neutrophil. Furthermore, secretion assays demonstrated that PLUNC protein was released by neutrophils upon stimulation with secretogogues, including formyl methionyl leucyl phenylalanine and the calcium ionophore A23187. Although recombinant PLUNC protein failed to exhibit antibacterial activity in our studies, its storage and secretion by a professional phagocytic cell support the hypothesis that PLUNC participates in an aspect of the inflammatory response that contributes to host defense. These studies suggest that PLUNC expression is less restricted than previously believed, and highlight new avenues of research for the study of PLUNC function.
Using Imperfect Advance Demand Information in Production-Inventory Systems with Multiple Customer Classes
Authors: Gayon Jean-Philippe , Benjaafar Saif , de Véricourt Francis
Published: February 2008

We consider a make-to-stock supplier that operates a production facility with limited capacity. The supplier receives orders from customers belonging to several demand classes. Some of the customer classes share advance demand information with the supplier by announcing their orders ahead of their due date. However, this advance demand information is not perfect because the customer may decide to order prior to or later than the expected due date or may decide to cancel the order altogether. Customer classes vary in their demand rates, expected due dates, cancellation probabilities, and shortage costs. The supplier must decide when to produce and, whenever an order becomes due, whether or not to satisfy it from on-hand inventory. Hence, the supplier is faced with a joint production-control and inventory-allocation problem. We formulate the problem as a Markov decision process and characterize the structure of the optimal policy. We show that the optimal production policy is a state-dependent base-stock policy with a base-stock level that is nondecreasing in the number of announced orders. We show that the optimal inventory-allocation policy is a state-dependent multilevel rationing policy, with the rationing level for each class nondecreasing in the number of announced orders (regardless of whether the class provides advance information). From numerical results, we obtain several insights into the value of advance demand information for both supplier and customers.
Do Children Differentiate Worry From Fear?
Authors: Szabó Marianna
Published: February 2008

Worry has been defined as a primarily cognitive process closely related to fear or anxiety. This definition is widely accepted by clinicians and researchers investigating worry and is often provided to research participants, especially to children. The present study aimed to empirically test the proposition that both adults and children conceptualise worry as a cognitive process, and that they differentiate it from fear on the basis of worry's relatively stronger association with thinking. Groups of 45 adults and 70 children completed three versions of a worry list questionnaire, reporting on the extent to which they worry about, are afraid of, and think about a list of negative outcomes. Regression analyses showed that in adults, thinking about a negative outcome had a significant unique association with worrying. In children, however, worrying was more strongly associated with fear ratings, especially in the case of physical outcomes. The data suggest that adults and children report on different concepts when they rate their worries via questionnaires. This difference may reflect developmental changes in the worry process itself, or developmental changes in the way individuals interpret and respond to worry list questionnaires. Follow-up studies using alternative methodologies are now needed to further clarify the results.
The Efficacy and Acceptability of the Triple P-Positive Parenting Program With Japanese Parents
Authors: Matsumoto Yuki , Sofronoff Kate , Sanders Matthew R.
Published: February 2008

This study examined the efficacy of the Group Triple P-Positive Parenting Program with a Japanese population to evaluate the feasibility and acceptability of the program and the parenting skills taught in a crosscultural context. The study involved 50 Japanese parents living in Australia and used a randomised group comparison design with two conditions, Triple P group and a waitlist control group. The results revealed significant reductions in parent reported child behaviour problems, parental overreactivity and laxness, and parental conflict as well as increasing parental competence. The acceptability of the program was found to be high. Intervention effects and program acceptability in a Japanese context as well as limitations and future research are discussed.
Long-Term Accommodation and Support for People With Higher Levels of Challenging Behaviour
Authors: Kelly Glenn , Winkler Dianne
Published: February 2008

The purpose of the present article is to describe the issues associated with providing lifelong accommodation and support to people with severe brain injury, neurobehavioural disability, and overt challenging behaviours. In particular, the article focuses on two groups of people within an Australian context: (a) those who live in community settings but whose behaviour is not adequately managed even by specialist outreach behaviour management services, and (b) those who are confined to aged care residential facilities and who show challenging behaviour. These groups bring to the fore different lifelong behaviour management issues. At present, if community-based clients seriously offend or have an adequate psychiatric diagnosis, they may be placed in heavily secured psychiatric units or prison. Otherwise, by default, they will reside in less restrictive options such as family homes and shared supported accommodation. We will argue that the current service system lacks the ability to apply appropriate structure and control to many clients with serious challenging behaviours, and propose that specialised facilities would make an important addition to the service system. Conversely, young clients confined to residential aged care facilities live in impoverished environments that often contribute to challenging behaviour that can be enormously disruptive, distressing, and unsafe. We will review the recent Australian State and Federal Government initiative aimed at transitioning some young people out of nursing homes, and we raise considerations for future service development. There are many individuals with the potential to make significant gains in a tightly structured setting before returning to the community, while others will manage well with long-term placement in a setting designed for residents with neurobehavioural disability. Case studies and service data are used to support these arguments, and key elements of accommodation and rehabilitation models for those in need of long-term neurobehavioural support are described.
The Process of Care Management Following Brain Injury: A Grounded Theory Study
Authors: McCluskey Annie , Johnson Maree , Tate Robyn
Published: February 2008

Establishing a viable program of care and support for people with severe brain injury is challenging for professionals and family members. The aims of this grounded theory study were to explore how decisions about care were made following brain injury when an individual had received third party compensation, and factors or conditions that influenced care. The sample (n = 51) included 14 people with traumatic brain injury (mean age 36.5 years, range 19–56; mean time post-injury 9.9 years, range 2.5–37), and 37 ‘others’, who either provided or coordinated care (12 family members, 14 paid carers, 6 case managers, 4 directors of care agencies and 1 estate manager). Data were collected using single interviews with each participant. All 14 people with brain injury had received 24-hour support at the time of hospital discharge; at follow-up, only 8 received 24-hour support. Care decision-making and care maintenance occurred as an iterative process. Participants made decisions about the best living situation, configuration of carers and level of care, and then strived to maintain stable care. Care decision-making involved three key strategies (gathering information, appraising alternatives, and enacting a decision). Care maintenance also involved three key strategies (monitoring, managing conflict and supporting carers). Mutual risk tolerance and the presence of a case manager were necessary conditions for good care management, and enabled a person with brain injury to spend time alone, take low-level risks and experience autonomy. Professionals and family carers can use the findings of this study to actively increase risk taking and autonomy.
Council of Australian Governments' (COAG) Initiative for Young People With Disability in Residential Aged Care: What Are the Issues for Acquired Brain Injury?
Authors: Foster Michele , Fleming Jennifer , Tilse Cheryl
Published: February 2008

People surviving severe acquired brain injury (ABI) may potentially benefit from the Council of Australian Governments' (COAG) 5-year initiative for young people with disability in residential aged-care facilities. Yet critical examination of this policy initiative for ABI population is warranted for 2 reasons. First, reliance on the disability sector to resolve the complexities of long-term care for people with ABI detracts attention from systemic failures at the health/disability sector interface, and notably, debate concerning the role of, and right to rehabilitation. Second, the COAG initiative is being pursued within an extraordinarily complex and variable contemporary care environment, involving multiple services and sectors, and historically, high unmet need. This raises questions as to the adequacy and sustainability of care provided under the responsibility of state-based disability services. In this article, it is argued that long-term care for young people with severe ABI is better served by incorporating a health and rehabilitation perspective alongside a disability support approach. Although the effectiveness of rehabilitation may be contested in some instances of very severe ABI, nevertheless the role of rehabilitation in seeking to reduce the number of young people at risk of entering residential aged care needs to be addressed in policy solutions. It is also suggested that provision of long time care in the contemporary care environment involves a number of challenges due to the complex and changing patterns of need, diverse funding arrangements and mix of government and nongovernment services, and the increasing demand for care.
The Importance of Reflexive Practice Within the Context of Life-Long Career Development for Rehabilitation Counsellors
Authors: Parks Richard
Published: February 2008

Where reflexivity is the process of ‘being aware in the moment of what is influencing our internal and external responses’ (Etherington, 2004), this literature review was aimed at exploring the extent to which rehabilitation counsellors could use the core competencies outlined by the Australian Society of Rehabilitation Counsellors (ASORC) for their own career development. Reference was given to two specific competencies: (1) Vocational counselling, and (2) Counselling and interpersonal skills to not only determine whether the espoused skills in these areas could be used to advance career development but to also address the issue of compassion fatigue. In addition to these competencies, the role of the organisation was also brought into question regarding its influences on the career development for rehabilitation counsellors and the extent it to which it can minimise burnout.
The Leuven Longitudinal Twin Study (LLTS): Major Findings
Authors: Beunen Gaston P. , Peeters Maarten W. , Maes Hermine H. , Loos Ruth J. F. , Claessens Albrecht L. , Derom Catherine , Vlietinck Robert , Thomis Martine A.
Published: February 2008

Alongitudinal study of growth and physical fitness of twins and their parents was designed in 1985. The major aims of this Leuven Longitudinal Twin Study were to quantify the genetic and environmental determination of (1) somatic characteristics, biological maturation and physical performance characteristics during the growth process, (2) the growth and developmental patterns, and (3) the covariation in somatic and performance characteristics.
Depression: Too Much Negative Affect or Too Little Positive Affect?
Authors: Wichers Marieke , Jacobs Nele , Derom Catherine , Thiery Evert , van Os Jim
Published: February 2008

The focus of research in depression is on negative affect. However, positive affect is under-investigated and plays an important role in resilience against depression by neutralizing the effects of genetic vulnerability to depression.
Characteristics of Spontaneously Conceived Twins Versus Twins After Assisted Conception
Authors: Delbaere Ilse , Verstraelen Hans , Temmerman Marleen
Published: February 2008

The East Flanders Prospective Twin Survey comprises data concerning placentation, mode of conception and perinatal outcome. As such, this database is convenient to study differences between spontaneous twins and twins resulting from assisted reproductive technologies (ART). Papers based on this survey demonstrated higher incidences of velamentous cord insertion, single umbilical artery and preterm birth in twins after ART.
Timing of Twinning, X-Inactivation and Sex Proportion at Birth
Authors: Derom Catherine , Vlietinck Robert , Derom Robert
Published: February 2008

Twins are not a homogeneous group. According to zygosity and chorionicity essential differences exist. The lower sex proportion at birth is due to the monozygotic twins, especially the monoamnionic variety. X-inactivation patterns in monozygotic twin girls are totally symmetrical in monoamnionic pairs, almost symmetrical in monochorionic diamnionic pairs and can be very asymmetrical in the dichorionic variety.
Clustering of Genetically Defined Allele Classes in the Caenorhabditis elegans DAF-2 Insulin/IGF-1 Receptor
Authors: Patel Dhaval S , Garza-Garcia Acely , Nanji Manoj , McElwee Joshua J , Ackerman Daniel , Driscoll Paul C , Gems David
Published: February 2008

The DAF-2 insulin/IGF-1 receptor regulates development, metabolism, and aging in the nematode Caenorhabditis elegans. However, complex differences among daf-2 alleles complicate analysis of this gene. We have employed epistasis analysis, transcript profile analysis, mutant sequence analysis, and homology modeling of mutant receptors to understand this complexity. We define an allelic series of nonconditional daf-2 mutants, including nonsense and deletion alleles, and a putative null allele, m65. The most severe daf-2 alleles show incomplete suppression by daf-18(0) and daf-16(0) and have a range of effects on early development. Among weaker daf-2 alleles there exist distinct mutant classes that differ in epistatic interactions with mutations in other genes. Mutant sequence analysis (including 11 newly sequenced alleles) reveals that class 1 mutant lesions lie only in certain extracellular regions of the receptor, while class 2 (pleiotropic) and nonconditional missense mutants have lesions only in the ligand-binding pocket of the receptor ectodomain or the tyrosine kinase domain. Effects of equivalent mutations on the human insulin receptor suggest an altered balance of intracellular signaling in class 2 alleles. These studies consolidate and extend our understanding of the complex genetics of daf-2 and its underlying molecular biology.
Comparative Genetics of Sex Determination: Masculinizing Mutations in Caenorhabditis briggsae
Authors: Kelleher Danielle F , de Carvalho Carlos Egydio , Doty Alana V , Layton Marnie , Cheng Andy T , Mathies Laura D , Pilgrim Dave , Haag Eric S
Published: February 2008

The nematodes Caenorhabditis elegans and C. briggsae independently evolved self-fertile hermaphroditism from gonochoristic ancestors. C. briggsae has variably divergent orthologs of nearly all genes in the C. elegans sex determination pathway. Their functional characterization has generally relied on reverse genetic approaches, such as RNA interference and cross-species transgene rescue and more recently on deletion mutations. We have taken an unbiased forward mutagenesis approach to isolating zygotic mutations that masculinize all tissues of C. briggsae hermaphrodites. The screens identified loss-of-function mutations in the C. briggsae orthologs of tra-1, tra-2, and tra-3. The somatic and germline phenotypes of these mutations are largely identical to those of their C. elegans homologs, including the poorly understood germline feminization of tra-1(lf) males. This overall conservation of Cb-tra phenotypes is in contrast to the fem genes, with which they directly interact and which are significantly divergent in germline function. In addition, we show that in both C. briggsae and C. elegans large C-terminal truncations of TRA-1 that retain the DNA-binding domain affect sex determination more strongly than somatic gonad development. Beyond these immediate results, this collection of mutations provides an essential foundation for further comparative genetic analysis of the Caenorhabditis sex determination pathway.
Recombination Map of the Common Shrew,Sorex araneus(Eulipotyphla, Mammalia)
Authors: Borodin Pavel M , Karamysheva Tatyana V , Belonogova Nadezhda M , Torgasheva Anna A , Rubtsov Nikolai B , Searle Jeremy B
Published: February 2008

The Eurasian common shrew (Sorex araneus L.) is characterized by spectacular chromosomal variation, both autosomal variation of the Robertsonian type and an XX/XY1Y2 system of sex determination. It is an important mammalian model of chromosomal and genome evolution as it is one of the few species with a complete genome sequence. Here we generate a high-precision cytological recombination map for the species, the third such map produced in mammals, following those for humans and house mice. We prepared synaptonemal complex (SC) spreads of meiotic chromosomes from 638 spermatocytes of 22 males of nine different Robertsonian karyotypes, identifying each autosome arm by differential DAPI staining. Altogether we mapped 13,983 recombination sites along 7095 individual autosomes, using immunolocalization of MLH1, a mismatch repair protein marking recombination sites. We estimated the total recombination length of the shrew genome as 1145 cM. The majority of bivalents showed a high recombination frequency near the telomeres and a low frequency near the centromeres. The distances between MLH1 foci were consistent with crossover interference both within chromosome arms and across the centromere in metacentric bivalents. The pattern of recombination along a chromosome arm was a function of its length, interference, and centromere and telomere effects. The specific DNA sequence must also be important because chromosome arms of the same length differed substantially in their recombination pattern. These features of recombination show great similarity with humans and mice and suggest generality among mammals. However, contrary to a widespread perception, the metacentric bivalent tu usually lacked an MLH1 focus on one of its chromosome arms, arguing against a minimum requirement of one chiasma per chromosome arm for correct segregation. With regard to autosomal chromosomal variation, the chromosomes showing Robertsonian polymorphism display MLH1 foci that become increasingly distal when comparing acrocentric homozygotes, heterozygotes, and metacentric homozygotes. Within the sex trivalent XY1Y2, the autosomal part of the complex behaves similarly to other autosomes.
Identification of Motifs That Are Conserved in 12 Drosophila Species and Regulate Midline Glia vs. Neuron Expression
Authors: Estes Patricia , Fulkerson Eric , Zhang Yi
Published: February 2008

Functional complexity of the central nervous system (CNS) is reflected by the large number and diversity of genes expressed in its many different cell types. Understanding the control of gene expression within cells of the CNS will help reveal how various neurons and glia develop and function. Midline cells of Drosophila differentiate into glial cells and several types of neurons and also serve as a signaling center for surrounding tissues. Here, we examine regulation of the midline gene, wrapper, required for both neuron–glia interactions and viability of midline glia. We identify a region upstream of wrapper required for midline expression that is highly conserved (87%) between 12 Drosophila species. Site-directed mutagenesis identifies four motifs necessary for midline glial expression: (1) a Single-minded/Tango binding site, (2) a motif resembling a pointed binding site, (3) a motif resembling a Sox binding site, and (4) a novel motif. An additional highly conserved 27 bp are required to restrict expression to midline glia and exclude it from midline neurons. These results suggest short, highly conserved genomic sequences flanking Drosophila midline genes are indicative of functional regulatory regions and that small changes within these sequences can alter the expression pattern of a gene.
Genetic Interactions of the Aspergillus nidulans atmAATM Homolog With Different Components of the DNA Damage Response Pathway
Authors: Malavazi Iran , Lima Joel Fernandes , de Castro Patrícia Alves , Savoldi Marcela , de Souza Goldman Maria Helena , Goldman Gustavo Henrique
Published: February 2008

Ataxia telangiectasia mutated (ATM) is a phosphatidyl-3-kinase-related protein kinase that functions as a central regulator of the DNA damage response in eukaryotic cells. In humans, mutations in ATM cause the devastating neurodegenerative disease ataxia telangiectasia. Previously, we characterized the homolog of ATM (AtmA) in the filamentous fungus Aspergillus nidulans. In addition to its expected role in the DNA damage response, we found that AtmA is also required for polarized hyphal growth. Here, we extended these studies by investigating which components of the DNA damage response pathway are interacting with AtmA. The AtmAATM loss of function caused synthetic lethality when combined with mutation in UvsBATR. Our results suggest that AtmA and UvsB are interacting and they are probably partially redundant in terms of DNA damage sensing and/or repairing and polar growth. We identified and inactivated A. nidulans chkACHK1 and chkBCHK2 genes. These genes are also redundantly involved in A. nidulans DNA damage response. We constructed several combinations of double mutants for ΔatmA, ΔuvsB, ΔchkA, and ΔchkB. We observed a complex genetic relationship with these mutations during the DNA replication checkpoint and DNA damage response. Finally, we observed epistatic and synergistic interactions between AtmA, and bimEAPC1, ankAWEE1 and the cdc2-related kinase npkA, at S-phase checkpoint and in response to DNA-damaging agents.
Dynamic Regulation of Single-Stranded Telomeres in Saccharomyces cerevisiae
Authors: Smith Stephanie , Banerjee Soma , Rilo Regina , Myung Kyungjae
Published: February 2008

The temperature-sensitive phenotypes of yku70Δ and yku80Δ have provided a useful tool for understanding telomere homeostasis. Mutating the helicase domain of the telomerase inhibitor Pif1 resulted in the inactivation of cell cycle checkpoints and the subsequent rescue of temperature sensitivity of the yku70Δ strain. The inactivation of Pif1 in yku70Δ increased overall telomere length. However, the long G-rich, single-stranded overhangs at the telomeres, which are the major cause of temperature sensitivity, were slightly increased. Interestingly, the rescue of temperature sensitivity in strains having both pif1-m2 and yku70Δ mutations depended on the homologous recombination pathway. Furthermore, the BLM/WRN helicase yeast homolog Sgs1 exacerbated the temperature sensitivity of the yku70Δ strain. Therefore, the yKu70-80 heterodimer and telomerase maintain telomere size, and the helicase activity of Pif1 likely also helps to balance the overall size of telomeres and G-rich, single-stranded overhangs in wild-type cells by regulating telomere protein homeostasis. However, the absence of yKu70 may provide other proteins such as those involved in homologous recombination, Sgs1, or Pif1 additional access to G-rich, single-stranded DNA and may determine telomere size, cell cycle checkpoint activation, and, ultimately, temperature sensitivity.
The mob as tumor suppressor Gene Is Essential for Early Development and Regulates Tissue Growth in Drosophila
Authors: Shimizu Takeshi , Ho Li-Lun , Lai Zhi-Chun
Published: February 2008

Studies in Drosophila have defined a new growth inhibitory pathway mediated by Fat (Ft), Merlin (Mer), Expanded (Ex), Hippo (Hpo), Salvador (Sav)/Shar-pei, Warts (Wts)/Large tumor suppressor (Lats), and Mob as tumor suppressor (Mats), which are all evolutionarily conserved in vertebrate animals. We previously found that the Mob family protein Mats functions as a coactivator of Wts kinase. Here we show that mats is essential for early development and is required for proper chromosomal segregation in developing embryos. Mats is expressed at low levels ubiquitously, which is consistent with the role of Mats as a general growth regulator. Like mammalian Mats, Drosophila Mats colocalizes with Wts/Lats kinase and cyclin E proteins at the centrosome. This raises the possibility that Mats may function together with Wts/Lats to regulate cyclin E activity in the centrosome for mitotic control. While Hpo/Wts signaling has been implicated in the control of cyclin E and diap1 expression, we found that it also modulates the expression of cyclin A and cyclin B. Although mats depletion leads to aberrant mitoses, this does not seem to be due to compromised mitotic spindle checkpoint function.
Active Miniature Transposons From a Plant Genome and Its Nonrecombining Y Chromosome
Authors: Bergero R , Forrest A , Charlesworth D
Published: February 2008

Mechanisms involved in eroding fitness of evolving Y chromosomes have been the focus of much theoretical and empirical work. Evolving Y chromosomes are expected to accumulate transposable elements (TEs), but it is not known whether such accumulation contributes to their genetic degeneration. Among TEs, miniature inverted-repeat transposable elements are nonautonomous DNA transposons, often inserted in introns and untranslated regions of genes. Thus, if they invade Y-linked genes and selection against their insertion is ineffective, they could contribute to genetic degeneration of evolving Y chromosomes. Here, we examine the population dynamics of active MITEs in the young Y chromosomes of the plant Silene latifolia and compare their distribution with those in recombining genomic regions. To isolate active MITEs, we developed a straightforward approach on the basis of the assumption that recent transposon insertions or excisions create singleton or low-frequency size polymorphisms that can be detected in alleles from natural populations. Transposon display was then used to infer the distribution of MITE insertion frequencies. The overall frequency spectrum showed an excess of singleton and low-frequency insertions, which suggests that these elements are readily removed from recombining chromosomes. In contrast, insertions on the Y chromosomes were present at high frequencies. Their potential contribution to Y degeneration is discussed.
Metabolic Changes Associated With Adaptive Diversification in Escherichia coli
Authors: Le Gac Mickaël , Brazas Michelle D , Bertrand Melanie , Tyerman Jabus G , Spencer Christine C , Hancock Robert E W , Doebeli Michael
Published: February 2008

During a 1000-generation evolution experiment, two types of morphologically and kinetically distinct bacteria repeatedly diverged from a common ancestor in a fully sympatric seasonal environment containing glucose and acetate. To investigate the metabolic modifications associated with this adaptive diversification, we compared transcription profiles of the two derived types and the common ancestor. Both derived types share a suite of common metabolic changes that may represent adaptation to the environment preceding the diversification event. These include improved translation efficiency, glucose uptake capacity via the mal/lamB genes, upregulation of various transporters during stationary phase, and likely the disruption of the rbs operon. The diversification event is associated with the overexpression of genes involved in the TCA cycle, glyoxylate shunt, acetate consumption, and anaerobic respiration in one type and in acetate excretion in the other. These results reveal that competition for both carbon and oxygen have likely played an important role in the adaptation of Escherichia coli during this adaptive diversification event, where one derived type mainly consumes glucose at a fast rate when oxygen is not limiting, and the other derived type consumes glucose and acetate at a slower rate, even when oxygen is limiting.
The Conserved Proteins CHE-12 and DYF-11 Are Required for Sensory Cilium Function in Caenorhabditis elegans
Authors: Bacaj Taulant , Lu Yun , Shaham Shai
Published: February 2008

Sensory neuron cilia are evolutionarily conserved dendritic appendages that convert environmental stimuli into neuronal activity. Although several cilia components are known, the functions of many remain uncharacterized. Furthermore, the basis of morphological and functional differences between cilia remains largely unexplored. To understand the molecular basis of cilia morphogenesis and function, we studied the Caenorhabditis elegans mutants che-12 and dyf-11. These mutants fail to concentrate lipophilic dyes from their surroundings in sensory neurons and are chemotaxis defective. In che-12 mutants, sensory neuron cilia lack distal segments, while in dyf-11 animals, medial and distal segments are absent. CHE-12 and DYF-11 are conserved ciliary proteins that function cell-autonomously and are continuously required for maintenance of cilium morphology and function. CHE-12, composed primarily of HEAT repeats, may not be part of the intraflagellar transport (IFT) complex and is not required for the localization of some IFT components. DYF-11 undergoes IFT-like movement and may function at an early stage of IFT-B particle assembly. Intriguingly, while DYF-11 is expressed in all C. elegans ciliated neurons, CHE-12 expression is restricted to some amphid sensory neurons, suggesting a specific role in these neurons. Our results provide insight into general and neuron-specific aspects of cilium development and function.
Dpb2p, a Noncatalytic Subunit of DNA Polymerase ε, Contributes to the Fidelity of DNA Replication in Saccharomyces cerevisiae
Authors: Jaszczur Malgorzata , Flis Krzysztof , Rudzka Justyna , Kraszewska Joanna , Budd Martin E , Polaczek Piotr , Campbell Judith L , Jonczyk Piotr , Fijalkowska Iwona J
Published: February 2008

Most replicases are multi-subunit complexes. DNA polymerase epsilon from Saccharomyces cerevisiae is composed of four subunits: Pol2p, Dpb2p, Dpb3p, and Dpb4p. Pol2p and Dpb2p are essential. To investigate a possible role for the Dpb2p subunit in maintaining the fidelity of DNA replication, we isolated temperature-sensitive mutants in the DPB2 gene. Several of the newly isolated dpb2 alleles are strong mutators, exhibiting mutation rates equivalent to pol2 mutants defective in the 3′ → 5′ proofreading exonuclease (pol2-4) or to mutants defective in mismatch repair (msh6). The dpb2 pol2-4 and dpb2 msh6 double mutants show a synergistic increase in mutation rate, indicating that the mutations arising in the dpb2 mutants are due to DNA replication errors normally corrected by mismatch repair. The dpb2 mutations decrease the affinity of Dpb2p for the Pol2p subunit as measured by two-hybrid analysis, providing a possible mechanistic explanation for the loss of high-fidelity synthesis. Our results show that DNA polymerase subunits other than those housing the DNA polymerase and 3′ → 5′ exonuclease are essential in controlling the level of spontaneous mutagenesis and genetic stability in yeast cells.