Controlling cytokinesis in the fission yeast Schizosaccharomyces pombe : the role of dma1; and ubc8

ABSTRACT The fission yeast Schizosaccharomyces pombe is a single celled eukaryote that has proved to be an excellent model system for the study of cell cycle control. S. pombe cells are rod shaped and grow mainly by elongation at their tips. They divide by formation of medially-placed cell wall, or septum, which cleaves the cell in two. Once the cell commits itself to mitosis the site of division is determined by formation of an acto-myosin based contractile ring at the cell cortex. The ring is assembled in stages throughout mitosis and contracts at the end of anaphase, coincident with spindle disassembly. The contraction, but not the assembly, of the ring requires the signal transduction network called the septation initiation network or SIN. The core components of the SIN are three protein kinases (cdc7p, sidl p and sid2p) and their regulatory subunits (spg1 p, cdcl4p and moblp, respectively). Signalling is dependent upon the nucleotide status of the GTPase spgl p, which is regulated by a two-component GAP protein, cdc16p-byr4p. Signalling is thought to emanate from the spindle pole body, where core SIN components are anchored to a scaffold comprised of sid4p and cdc11p. Activation of the SIN requires the protein kinase plolp, which also has additional roles in mitosis. SIN signalling is tightly regulated to assure the proper co-ordination of mitosis and cytokinesis. Ectopic activation of the SIN in interphase can uncouple septum formation from mitosis, while deregulated SIN signalling leads to formation of cells with multiple septa that do not cleave. Regulators of SIN activity are therefore of considerable interest. This study has concentrated upon two of these, dma1 and ubc8. I have demonstrated that dmal becomes essential when SIN signalling is activated. This leads me to propose a tripartite model for regulation of the SIN during the mitotic cell cycle. Increased expression of dma1 inhibits SIN signalling and prevents cell division. To identify potential targets and mediators of this, multicopy suppressors of dma1 toxicity were identified. One of these, ubc8, is the subject of this thesis. Genetic and molecular analyses are consistent with the view that ubc8p acts as an inhibitor of the SIN Localisation of ubc8p indicates that it is a nuclear protein. The ubc8 gene is not essential, but in its absence cells are unable to prevent septum formation if progression through mitosis is impaired. These data suggest that it may be an effector of the spindle assembly checkpoint. Together, these data shed new light upon the mechanisms by which cytokinesis is regulated in S. pombe. RESUME La levure Schizosaccharomyces pombe est un eucaryote unicellulaire qui est un bon système d'étude du cycle cellulaire. Les cellules de S. pombe sont en forme de bâtonnets et poussent par allongement aux deux bouts. Elles se divisent en formant une paroi au milieu de la cellule, qui s'appelle un septum et qui sépare la cellule en deux. Une fois que la cellule est engagée dans la mitose, le site de clivage est déterminé par la formation d'un anneau contractile d'acto-myosine au niveau du cortex cellulaire. Cet anneau est séquentiellement assemblé au cours de la mitose et se contacte à la fin de l'anaphase, au moment où le fuseau mitotique et désassemblé. La contraction, mais non pas l'assemblage, de l'anneau dépend d'un réseau de signalisation appelé septation initiation netvvork' ou SIN. Les composants centraux du SIN sont trois kinases (cdc7, sidi et sid2) ainsi que leurs sous-unités régulatrices (spgl, cdc14 et mob1, respectivement). La signalisation dépend du nucléotide rattaché à la GTPase spgl qui est régulée par une GAP comprenant deux sous-unités cdc16 et byr4. La signalisation est présumée provenir du pôle du fuseau où les composants centraux du SIN sont ancrés grâce à un échafaudage comprenant sid4 et cdcl 1. La signalisation est étroitement régulée pour assurer une bonne coordination entre mitose et cytokinèse. Une activation ectopique du SIN en interphase peut découpler la formation du septum de la mitose, engendrant des cellules à multiples septa qui ne sont pas clivés. C'est pourquoi les régulateurs du SIN sont d'un intérêt considérable. Cette étude se concentre autour de deux ces régulateurs, dma1 et ubc8. J'ai montré que dma1 devient essentiel quand la signalisation du SIN est activée. Ceci m'amène à proposer un modèle en trois parties pour la régulation du SIN durant la mitose. Une expression élevée de dma1 inhibe la signalisation du SIN et empêche la division cellulaire. Afin d'identifier des substrats ou médiateurs potentiels de la toxicité de dma1, des supresseurs en copies multiples ont été identifiés. Un de ces supresseurs, ubc8, constitue le deuxième sujet de cette thèse. Les études génétiques et moléculaires suggèrent un rôle inhibiteur du SIN par ubc8. Ubc8p est une protéine nucléaire, non essentielle, mais en son absence les cellules ne peuvent pas restreindre la fomation du septum, lorsque la progression de la mitose est perturbée. Les données suggèrent que ubc8 pourrait être un effecteur de point de contrôle de l'assemblage du fuseau mitotique. Prises dans leur ensemble, ces données apportent un nouvel éclairage sur les mécanismes de régulation de la cytokinèse dans S. pombe.

Developmental changes in lateralized inhibition of symmetric movements in children with and without Developmental Coordination Disorder.

The present study investigates developmental changes in selective inhibition of symmetric movements with a lateralized switching task from bimanual to unimanual tapping in typically developing (TD) children and with Developmental Coordination Disorder (DCD) from 7 to 10 years old. Twelve right-handed TD children and twelve gender-matched children with DCD and probable DCD produce a motor switching task in which they have (1) to synchronize with the beat of an auditory metronome to produce bimanual symmetrical tapping and (2) to selectively inhibit their left finger's tapping while continuing their right finger's tapping and conversely. We assess (1) the development of the capacity to inhibit the stopping finger (number of supplementary taps after the stopping instruction) and (2) the development of the capacity to maintain the continuing finger (changes in the mean tempo and its variability for the continuing finger's tapping) and (3) the evolution of performance through trials. Results indicate that (1) TD children present an age-related increase in the capacity to inhibit and to maintain the left finger's tapping, (2) DCD exhibits persistent difficulties to inhibit the left finger's tapping, and (3) both groups improve their capacity to inhibit the left finger's movements through trials. In conclusion, the lateralized switching task provides a simple and fine tool to reveal differences in selective inhibition of symmetric movements in TD children and children with DCD. More theoretically, the specific improvement in selective inhibition of the left finger suggests a progressive development of inter-hemispheric communication during typical development that is absent or delayed in children with DCD.

Interrogation of related clinical pan-azole-resistant Aspergillus fumigatus strains: G138C, Y431C, and G434C single nucleotide polymorphisms in cyp51A, upregulation of cyp51A, and integration and activation of transposon Atf1 in the cyp51A promoter.

Multiple Aspergillus fumigatus isolates from a patient with two aspergillomas complicating chronic pulmonary aspergillosis were pan-azole resistant. Microsatellite typing was identical for all isolates despite major phenotypic and some growth rate differences. Three different cyp51A mutations were found (G138C, Y431C, and G434C), of which the first two were demonstrated by heterologous expression in a hypersusceptible Saccharomyces cerevisiae strain to be at least partly responsible for elevated MICs. cyp51A and cyp51B gene duplication was excluded, but increased expression of cyp51A was demonstrated in three isolates selected for additional study (7-to 13-fold increases). In the isolate with the greatest cyp51A expression, an Aft1 transposon was found inserted 370 bp upstream of the start codon of the cyp51A gene, an integration location never previously demonstrated in Aspergillus. Two transcription start sites were identified at 49 and 136 bp upstream of the start codon. The role of the Aft1 transposon, if any, in modulating cyp51A expression remains to be established. Increased mRNA expression of the transporters AfuMDR1 and AfuMDR4 also was demonstrated in some isolates, which could contribute to azole resistance or simply represent a stress response. The diversity of confirmed and possible azole resistance mechanisms demonstrated in a single series of isogenic isolates is remarkable, indicating the ability of A. fumigatus to adapt in the clinical setting.

The combination of social and personal contexts affects dominance hierarchy development in shore crabs, Carcinus maenas

Many animals that live in groups maintain competitive relationships, yet avoid continual fighting, by forming dominance hierarchies. We compare predictions of stochastic, individual-based models with empirical experimental evidence using shore crabs to test competing hypotheses regarding hierarchy development. The models test (1) what information individuals use when deciding to fight or retreat, (2) how past experience affects current resource-holding potential, and (3) how individuals deal with changes to the social environment. First, we conclude that crabs assess only their own state and not their opponent's when deciding to fight or retreat. Second, willingness to enter, and performance in, aggressive contests are influenced by previous contest outcomes. Winning increases the likelihood of both fighting and winning future interactions, while losing has the opposite effect. Third, when groups with established dominance hierarchies dissolve and new groups form, individuals reassess their ranks, showing no memory of previous rank or group affiliation. With every change in group composition, individuals fight for their new ranks. This iterative process carries over as groups dissolve and form, which has important implications for the relationship between ability and hierarchy rank. We conclude that dominance hierarchies emerge through an interaction of individual and social factors, and discuss these findings in terms of an underlying mechanism. Overall, our results are consistent with crabs using a cumulative assessment strategy iterated across changes in group composition, in which aggression is constrained by an absolute threshold in energy spent and damage received while fighting.

Results of a combination of bleomycin and triamcinolone acetonide in the treatment of keloids and hypertrophic scars.

While treatment of keloids and hypertrophic scars normally shows modest results, we found that treatment with bleomycin was more promising. The present study was divided into two parts. In the first part the aim was to show the results using a combination of bleomycin and triamcinolone acetonide per cm2 (BTA). In the second part the objective was to determine the response to both drugs in large keloids that were divided into 1 cm2 squares, treating each square with the dose previously used. In the first part of the study, the clinical response of 37 keloids ranging from 0.3 to 1.8 cm2 treated with BTA were followed up over a period of 1- 2 years. 0.375 IU bleomycin and 4 mg triamcinolone acetonide were injected every 3 months. In the second part of the study we reviewed the clinical response in six patients with large keloids. The monthly dose administered never exceeded 3 IU of bleomycin. The first study showed 36 keloids (97.29%) softening after the first dose. In the second study, 5 showed different responses (the response was complete in the four smaller keloids). The largest keloid needed 9 doses to achieve an improvement of 70%. In conclusion, combined treatment with 0.375 IU of bleomycin and 4mg of triamcinolone acetonide to 1 cm2 was considered to be an acceptable procedure for the treatment of keloids. The best results were obtained in keloids over 1 cm2 or when divided into 1 cm2 square areas. Larger series need to be performed in order to confirm these results..

Metabolomic insights into the intricate gut microbial-host interaction in the development of obesity and type 2 diabetes.

Gut microbiota has recently been proposed as a crucial environmental factor in the development of metabolic diseases such as obesity and type 2 diabetes, mainly due to its contribution in the modulation of several processes including host energy metabolism, gut epithelial permeability, gut peptide hormone secretion, and host inflammatory state. Since the symbiotic interaction between the gut microbiota and the host is essentially reflected in specific metabolic signatures, much expectation is placed on the application of metabolomic approaches to unveil the key mechanisms linking the gut microbiota composition and activity with disease development. The present review aims to summarize the gut microbial-host co-metabolites identified so far by targeted and untargeted metabolomic studies in humans, in association with impaired glucose homeostasis and/or obesity. An alteration of the co-metabolism of bile acids, branched fatty acids, choline, vitamins (i.e., niacin), purines, and phenolic compounds has been associated so far with the obese or diabese phenotype, in respect to healthy controls. Furthermore, anti-diabetic treatments such as metformin and sulfonylurea have been observed to modulate the gut microbiota or at least their metabolic profiles, thereby potentially affecting insulin resistance through indirect mechanisms still unknown. Despite the scarcity of the metabolomic studies currently available on the microbial-host crosstalk, the data-driven results largely confirmed findings independently obtained from in vitro and animal model studies, putting forward the mechanisms underlying the implication of a dysfunctional gut microbiota in the development of metabolic disorders.

From Translation to Rewriting : the Interplay of Text and Image in The Fairy Tales of Charles Perrault and The Bloody Chamber and Other Stories

Abstract :This article examines the interplay of text and image in The Fairy Tales of Charles Perrault (1977), translated by Angela Carter and illustrated by Martin Ware, as a form of intersemiotic dialogue that sheds new light on Carter's work. It argues that Ware's highly original artwork based on the translation not only calls into question the association of fairy tales with children's literature (which still characterizes Carter's translation), but also captures an essential if heretofore neglected aspect of Carter's creative process, namely the dynamics between translating, illustrating and rewriting classic tales. Several elements from Ware's illustrations are indeed taken up and elaborated on in The Bloody Chamber and Other Stories (1979), the collection of "stories about fairy stories" that made Carter famous. These include visual details and strategies that she transposed to the realm of writing, giving rise to reflections on the relation between visuality and textuality.RésuméCet article considère l'interaction du texte et de l'image dans les contes de Perrault traduits par Angela Carter et illustrés par Martin Ware (The Fairy Tales of Charles Perrault, 1977) comme une forme de dialogue intersémiotique particulièrement productif. Il démontre que les illustrations originales de Ware ne mettent pas seulement en question l'assimilation des contes à la littérature de jeunesse (qui est encore la perspective adoptée par la traductrice dans ce livre), mais permettent aussi de saisir un aspect essentiel bien que jusque là ignoré du procession de création dans l'oeuvre de Carter, à savoir la dynamique qui lie la traduction, l'illustration et la réécriture des contes classiques. Plusieurs éléments des illustrations de Ware sont ainsi repris et élaborés dans The Bloody Chamber and Other Stories (1979), la collection de "stories about fairy stories" qui rendit Carter célèbre. La transposition de détails et de stratégies visuelles dans l'écriture donnent ainsi l'occasion de réflexions sur les rapports entre la visualité et la textualité.

Concentrations of the enantiomers of fluoxetine and norfluoxetine after multiple doses of fluoxetine in cytochrome P4502D6 poor and extensive metabolizers.

Plasma concentrations of the enantiomers of fluoxetine (FLX) and norfluoxetine (NFLX) were measured at days 7, 14, and 23 of oral administration of 20 mg of racemic fluoxetine in 11 patients who were comedicated with risperidone. Eight patients were genotyped as being cytochrome P4502D6 extensive metabolizers (EMs) and three as cytochrome P4502D6 poor metabolizers (PMs). No statistically significant differences were calculated between EMs and PMs in the concentrations of (R)-FLX and (R)-NFLX for all days examined (day 23, mean +/- SD for (R)-FLX and (R)-NFLX in EMs, 16 +/- 5 and 29 +/- 20 ng/mL, respectively; in PMs, 16 +/- 1 and 20 +/- 2 ng/mL, respectively). However, concentrations of (S)-FLX and (S)-NFLX were higher and lower, respectively, in PMs as compared with EMs (day 7, p = 0.037 and p = 0.036; day 14, p = 0.014 and p = 0.014; day 23, p = 0.068 and p = 0.038). On day 23, mean (S)-FLX and (S)-NFLX in EMs were (mean +/- SD) 39 +/- 26 and 63 +/- 26 ng/mL, and in PMs they were 88 +/- 7 and 19 +/- 2 ng/mL. This study confirms the results of the single-dose studies showing that CYP2D6 is involved in the demethylation of FLX to NFLX, with a stereoselectivity toward the (S)-enantiomer. The data also clearly show that the CYP2D6 genotype has an important influence on the concentrations of the (S)- but not of the (R)-enantiomer of FLX and NFLX after multiple doses.

Division of labour and worker size polymorphism in ant colonies: the impact of social and genetic factors

Division of labour among workers is central to the organisation and ecological success of insect societies. If there is a genetic component to worker size, morphology or task preference, an increase in colony genetic diversity arising from the presence of multiple breeders per colony might improve division of labour. We studied the genetic basis of worker size and task preference in Formica selysi, an ant species that shows natural variation in the number of mates per queen and the number of queens per colony. Worker size had a heritable component in colonies headed by a doubly mated queen (h(2)=0.26) and differed significantly among matrilines in multiple-queen colonies. However, higher levels of genetic diversity did not result in more polymorphic workers across single- or multiple-queen colonies. In addition, workers from multiple-queen colonies were consistently smaller and less polymorphic than workers from single-queen colonies. The relationship between task, body size and genetic lineage appeared to be complex. Foragers were significantly larger than brood-tenders, which may provide energetic or ergonomic advantages to the colony. Task specialisation was also often associated with genetic lineage. However, genetic lineage and body size were often correlated with task independently of each other, suggesting that the allocation of workers to tasks is modulated by multiple factors. Overall, these results indicate that an increase in colony genetic diversity does not increase worker size polymorphism but might improve colony homeostasis.

Steady state plasma levels of the enantiomers of trimipramine and of its metabolites in CYP2D6-, CYP2C19- and CYP3A4/5-phenotyped patients.

Steady state plasma concentrations of the (L)- and (D)-enantiomers of trimipramine (TRI), desmethyltrimipramine (DTRI), 2-hydroxytrimipramine (TRIOH) and 2-hydroxydesmethyl-trimipramine (DTRIOH) were measured in 27 patients receiving between 300 and 400 mg/day racemic TRI. The patients were phenotyped with dextromethorphan and mephenytoin, and the 8-hour urinary ratios of dextromethorphan/dextrorphan, dextromethorphan/3-methoxymorphinan, and (S)-mephenytoin/(R)mephenytoin were used as markers of cytochrome P-450IID6 (CYP2D6), CYP3A4/5 and CYP2C19 activities, respectively. One patient was a CYP2D6 and one was a CYP2C19 poor metabolizer. A stereoselectivity in the metabolism of TRI has been found, with a preferential N-demethylation of (D)-TRI and a preferential hydroxylation of (L)-TRI. CYP2D6 appears to be involved in the 2-hydroxylation of (L)-TRI, (L)DTRI and (D)-DTRI, but not of (D)-TRI, as significant correlations were measured between the dextromethorphan/dextrorphan ratios and the (L)-TRI/(L)-TRIOH (r = 0.45, p = 0.019), the (L)-DTRI/(L)-DTRIOH (r = 0.47, p = 0.014), and the (D)-DTRI/(D)-DTRIOH (r = 0.51, p = 0.006), but not with the (D)-TRI/(D)-TRIOH ratios (r = 0.29, NS). CYP2C19, but not CYP2D6, appears to be involved in the demethylation pathway, with a stereoselectivity toward the (D)-enantiomer of TRI, as a significant positive correlation was calculated between the mephenytoin (S)/(R) ratios and the concentrations to dose-to-weight ratios of (D)-TRI (r = 0.69, p = 0.00006). CYP3A4/5 appears to be involved in the metabolism of (L)-TRI to a presently not determined metabolite. The CYP2D6 poor metabolizer had the highest (L)-DTRI and (D)-DTRI concentrations to dose-to-weight ratios, and the CYP2C19 poor metabolizer had the highest (L)-TRI and (D)-TRI concentrations to dose-to-weight ratios of the group.

The relevance of the Laplacian of intracule and extracule density distributions for analyzing electron-electron interactions in molecules

A topological analysis of intracule and extracule densities and their Laplacians computed within the Hartree-Fock approximation is presented. The analysis of the density distributions reveals that among all possible electron-electron interactions in atoms and between atoms in molecules only very few are located rigorously as local maxima. In contrast, they are clearly identified as local minima in the topology of Laplacian maps. The conceptually different interpretation of intracule and extracule maps is also discussed in detail. An application example to the C2H2, C2H4, and C2H6 series of molecules is presented

Redox dysregulation in the pathophysiology of schizophrenia and bipolar disorder: insights from animal models.

Abstract Significance: Schizophrenia (SZ) and bipolar disorder (BD) are classified as two distinct diseases. However, accumulating evidence shows that both disorders share genetic, pathological, and epidemiological characteristics. Based on genetic and functional findings, redox dysregulation due to an imbalance between pro-oxidants and antioxidant defense mechanisms has been proposed as a risk factor contributing to their pathophysiology. Recent Advances: Altered antioxidant systems and signs of increased oxidative stress are observed in peripheral tissues and brains of SZ and BD patients, including abnormal prefrontal levels of glutathione (GSH), the major cellular redox regulator and antioxidant. Here we review experimental data from rodent models demonstrating that permanent as well as transient GSH deficit results in behavioral, morphological, electrophysiological, and neurochemical alterations analogous to pathologies observed in patients. Mice with GSH deficit display increased stress reactivity, altered social behavior, impaired prepulse inhibition, and exaggerated locomotor responses to psychostimulant injection. These behavioral changes are accompanied by N-methyl-D-aspartate receptor hypofunction, elevated glutamate levels, impairment of parvalbumin GABA interneurons, abnormal neuronal synchronization, altered dopamine neurotransmission, and deficient myelination. Critical Issues: Treatment with the GSH precursor and antioxidant N-acetylcysteine normalizes some of those deficits in mice, but also improves SZ and BD symptoms when given as adjunct to antipsychotic medication. Future Directions: These data demonstrate the usefulness of GSH-deficient rodent models to identify the mechanisms by which a redox imbalance could contribute to the development of SZ and BD pathophysiologies, and to develop novel therapeutic approaches based on antioxidant and redox regulator compounds. Antioxid. Redox Signal. 18, 1428-1443.

Special Investigation of Certain Grants Administered by The Department of Curriculum and Instruction, College of Education, Iowa State University of Science and Technology, For the Period September 1, 1999 through November 30, 2003

State University Audit Report - Special Investigation

Special Investigation of Certain Grants Administered by The Department of Curriculum and Instruction, College of Education, Iowa State University of Science and Technology, For the Period September 1, 1999 through November 30, 2003

State University Audit Report - Special Investigation