Environmental and Genetic Determinants of Colony Morphology in Yeast

Nutrient stresses trigger a variety of developmental switches in the budding yeast Saccharomyces cerevisiae. One of the least understood of such responses is the development of complex colony morphology, characterized by intricate, organized, and strain-specific patterns of colony growth and architecture. The genetic bases of this phenotype and the key environmental signals involved in its induction have heretofore remained poorly understood. By surveying multiple strain backgrounds and a large number of growth conditions, we show that limitation for fermentable carbon sources coupled with a rich nitrogen source is the primary trigger for the colony morphology response in budding yeast. Using knockout mutants and transposon-mediated mutagenesis, we demonstrate that two key signaling networks regulating this response are the filamentous growth MAP kinase cascade and the Ras-cAMP-PKA pathway. We further show synergistic epistasis between Rim15, a kinase involved in integration of nutrient signals, and other genes in these pathways. Ploidy, mating-type, and genotype-by-environment interactions also appear to play a role in the controlling colony morphology. Our study highlights the high degree of network reuse in this model eukaryote; yeast use the same core signaling pathways in multiple contexts to integrate information about environmental and physiological states and generate diverse developmental outputs

Iconic dishes, culture and identity: the Christmas pudding and its hundred years’ journey in the USA, Australia, New Zealand and India

Asserting that recipes are textual evidences reflecting the society that produced them, this article explores the evolution of the recipes of the iconic Christmas pudding in the United States, Australia, New Zealand and India between the mid-nineteenth and the mid-twentieth centuries. Combining a micro-analysis of the recipes and the cookbook that provided them with contemporary testimonies, the article observes the dynamics revealed by the preparation and consumption of the pudding in these different societies. The findings demonstrate the relevance of national iconic dishes to the study of notions of home, migration and colonization, as well as the development of a new society and identity. They reveal how the preservation, transformation and even rejection of a traditional dish can be representative of the complex and sometimes conflicting relationships between colonists, migrants or new citizens and the places they live in

Dem investigation of horizontal high shear mixer flow behaviour and implications for scale-up

In high shear granulation, various dimensionless or dimensioned parameter groups such as constant Froude number, tip speed, relative swept volume and specific energy input are commonly used as scale-up criteria, in order to maintain the powder bed internal flow or stress field across scales. One major challenge is obtaining the internal flow and stress field through experimentation given the lack of precise measurement techniques. Hence, this work employs DEM (discrete element method) simulations to study the internal flow patterns and behaviour of different scale batch, horizontal high shear mixers. The simulations provide a deeper understanding of the interaction of scale, impeller speed and fill level on the flow field, and show that the particle velocity is correlated with the relative swept volume in these mixers. It shows that the relative particle velocity is correlated, independent of scale, to the relative swept volume per rotation and highlights its values as a parameter for understanding and comparing mixer behaviour. The work also demonstrates the importance of the particle size chosen for the simulation as well as the tool-wall gap in the mixer, and highlights its importance as we interpret DEM results

Whole-Exome Capture and Sequencing Identifies HEATR2 Mutation as a Cause of Primary Ciliary Dyskinesia

Motile cilia are essential components of the mucociliary escalator and are central to respiratory-tract host defenses. Abnormalities in these evolutionarily conserved organelles cause primary ciliary dyskinesia (PCD). Despite recent strides characterizing the ciliome and sensory ciliopathies through exploration of the phenotype-genotype associations in model organisms, the genetic bases of most cases of PCD remain elusive. We identified nine related subjects with PCD from geographically dispersed Amish communities and performed exome sequencing of two affected individuals and their unaffected parents. A single autosomal-recessive nonsynonymous missense mutation was identified in HEATR2, an uncharacterized gene that belongs to a family not previously associated with ciliary assembly or function. Airway epithelial cells isolated from PCD-affected individuals had markedly reduced HEATR2 levels, absent dynein arms, and loss of ciliary beating. MicroRNA-mediated silencing of the orthologous gene in Chlamydomonas reinhardtii resulted in absent outer dynein arms, reduced flagellar beat frequency, and decreased cell velocity. These findings were recapitulated by small hairpin RNA-mediated knockdown of HEATR2 in airway epithelial cells from unaffected donors. Moreover, immunohistochemistry studies in human airway epithelial cells showed that HEATR2 was localized to the cytoplasm and not in cilia, which suggests a role in either dynein arm transport or assembly. The identification of HEATR2 contributes to the growing number of genes associated with PCD identified in both individuals and model organisms and shows that exome sequencing in family studies facilitates the discovery of novel disease-causing gene mutations

A cladistic and biogeographic analysis of Philotheca (Rutaceae) and allied genera

© 2001 Dr. Michael J. BaylyThis thesis considers the relationships, classification and historical biogeography of the related Australian endemic flowering plant genera Philotheca, Eriostemon and Crowea (family Rutaceae, tribe Boronieae). It focuses mostly on relationships within and between these genera, but also considers the relationships of these groups to other members of the tribe Boronieae, particularly the small genera Geleznowia and Drummondita. It includes a brief appraisal of the species-level taxonomy of Philotheca, Eriostemon and Crowea, a survey of morphological characters, a survey of leaf phenolic compounds, and a series of cladistic and biogeographic analyses. The appraisal of species-level taxonomy identified terminal taxa suitable for use in cladistic analyses, and has resulted in the recognition of one new species (Philotheca sporadica) and three new subspecies (P. myoporoides subsp. brevipedunculata, subsp. euroensis, and subsp. obovatifolia, as well as a recommendation to reinstate one species (Eriostemon banksii, which was previously reduced to subspecific status under E. australasius). The survey of morphological variation identified 108 morphological characters, 99 of which are potentially useful in the assessment of relationships, and nine that are unique to single terminal taxa. The survey of leaf phenolics was based on two-dimensional paper chromatography, and the chromatographic properties and distributions of 26 compounds are reported. Twenty-three of these compounds are potentially useful in the assessment of relationships, and three are unique to single terminal taxa. Assessment of the higher-level relationships of Philotheca, Eriostemon and Crowea (to each other and to other taxa of Boronieae) was based on reappraisal, and re-analysis, of a previous phylogenetic analysis (Armstrong 1991). This reappraisal was based on a limited set of morphological characters, and used genera, sections within genera, and some species as terminal taxa. In general higher-level relationships of the three genera were either poorly resolved or poorly supported. A close relationship of Drummondita to Philotheca sect. Philotheca was supported, but a close relationship of Geleznowia to this group (as has recently been proposed) was not. A series of subsequent analyses of relationships within Philotheca, Drummondita, Eriostemon and Crowea employed a larger set of morphological and phenolic characters (in various combinations), and used species, subspecies and varieties as terminal taxa. Character state transformations were polarised using Crowea as an outgroup to Philotheca, Drummondita and Eriostemon, and vice versa. This assignment of ingroup/outgroup relationships was based on an a posteriori decision, given the lack of a well-supported higher-level phylogeny for the group. These subsequent analyses provided good support for the monophyly of each of Crowea, Philotheca sect. Erionema, P. sect. Corynonema, P. sect. Cyanochlamys, Eriostemon, Drummondita, and a group comprising both Drummondita and P. sect. Philotheca. Philotheca sect. Philotheca was only supported as monophyletic in some analyses. Relationships among these groups were not unequivocally resolved, but the monophyly of Philotheca, as currently circumscribed, was not supported. The biogeographic analyses used the method of subtree analysis and considered the historical relationships of areas in south-western and eastern Australia. The pattern or area relationships was not unequivocally resolved, with some areas showing multiple relationships. The results of these analyses are compared with those from other studies on Australian biogeography. A general historical scenario for the differentiation of taxa and areas is discussed

Notes on the Eriostemon myoporoides (Rutaceae) species complex, including new names and new generic placement in Philotheca

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Alarm calling best predicts mating and reproductive success in ornamented male fowl, Gallus gallus

Studies of female mate choice in fowl typically invoke ornament size as the best predictor of male reproductive success. The strongest evidence comes from experiments in which a hen is presented with two unfamiliar and physically separated males that she can evaluate and mate with for up to 120 min. This design controls for prior experience and maleemale competition, but deprives females of information available only from longer sampling periods and a more natural context. In the wild, fowl spend their lives in stable social groups. We observed birds under naturalistic conditions to evaluate the biological significance of ornament size and to explore other potential predictors of male mating and reproductive success. For each male, we measured morphology and several behaviours related to food, predators, dominance and courtship. Using principal components analysis and multiple regression, we show that behaviour is the best predictor of male mating and reproductive success under natural conditions, and that the most salient behaviours are dominance and the rate of antipredator signalling. Dominance probably affects an individual’s reproductive success by determining access to receptive females, but the mechanism responsible for the role of alarm calling is less clear. Costly alarm signals may advertise male quality, or they may reflect judicious risk-taking by males that have achieved mating success

Data from: The roles of ecological and evolutionary processes in plant community assembly: the environment, hybridization and introgression influence co-occurrence of Eucalyptus

Introgressive hybridization is increasingly recognized as having influenced the gene pools of large genera of plants, yet it is rarely invoked as an explanation for why closely related plant species do not co-occur. Here, we asked how the environment and tendency to interbreed relate to neighborhood co-occurrence patterns for Eucalyptus species in the Grampians National Park, Victoria, Australia. We identified species pairs that have experienced ongoing hybridization and introgression on the basis of the extent of incongruence between chloroplast DNA (JLA+ region) and nuclear ribosomal DNA (internal transcribed spacer region) phylogenies, geographic patterns of gene sharing, and field observation of intermediate morphologies. Co-occurrence, trait data (specific leaf area [SLA], maximum height, and seed mass), and environmental data were measured in plots distributed along environmental gradients. Trait and habitat similarity influenced species co-occurrence the most overall (e.g., co-occurring species had similar SLA). Reproductively compatible species were an exception; they rarely co-occurred despite being functionally similar. The negative effect of reproductive compatibility was stronger than the positive effect of SLA on co-occurrence. Our results emphasize the dominant roles of the environment and the importance of evolution in structuring local assemblages. We argue that the mechanism responsible for preventing closely related species from co-occurring in this system is reproductive interference rather than competitive exclusion. Reproductive interference should be considered more generally as a potential cause of phylogenetic overdispersion