Linking multiple aspects of thermal performance to explore the potential for thermal resource partitioning between a native and an invasive crayfish.

Ecologists require standardized, ecologically relevant information on the thermal ecology of aquatic ectotherms to address growing concerns related to changing climates, altered habitats, and introduced species. We measured multiple thermal endpoints to investigate potential for establishment of the invasive Ringed Crayfish (Faxonius neglectus) in thermally heterogeneous habitat of the narrowly distributed endemic Coldwater Crayfish (Faxonius eupunctus). For each species, we examined the relationships between thermal endpoints at the cellular and organismal levels. We then compared results between the two species to gain insight as to the generality of linkages between cellular and organismal-level endpoints, as well as the potential for thermal niche separation between the native and potential invader. At the cellular level, we found no differences in the temperature for maximum activity of electron transport system enzymes (ETSmax) between species. At the organismal level, F. neglectus preferred significantly warmer temperatures than F. eupunctus, but this difference was small (1.3 °C) and likely to have only limited biological significance. The critical thermal maximum (CTM) did not differ between species. For both species, the thermal performance curve for ETS enzyme activity served as a useful framework to link thermal endpoints and estimate the transition from optimal to stressful temperatures - organismal thermal preference and optimal temperature estimates consistently fell below ETSmax whereas CTM estimates fell above ETSmax. Taken together, the strong similarities in thermal endpoint patterns between the two species suggest habitats thermally suitable for the native F. eupunctus will also be thermally available to expanding populations of F. neglectus, thereby increasing the opportunity for negative interactions and population effects if F. neglectus invades one of the few remaining, uninvaded, critical habitats of F. eupunctus.

The effect of sucrose addition at dosage stage on the foam attributes of a bottle-fermented English sparkling wine.

BACKGROUND: Approximately two-thirds of wine produced in the UK is bottle-fermented sparkling wine. Effervescence and foamability are key features used to assess English sparkling wine (ESW) quality. A critical, yet understudied, area of research is the potential for dosage to influence foam behaviour via associated changes in wine viscosity. RESULTS: In this study, dosage treatments of five increasing levels of sucrose (from 0 to 31 g L-1 ) were added to an ESW. After storage, the foamability attributes of the wines were analysed via an adapted Mosalux method and a novel image analysis method combined with free pour of the wine. Results indicate that increasing sucrose concentration improved foam formation, but reduced foam stability, likely due to the sucrose added causing a modification in wine viscosity. CONCLUSIONS: These results highlight the impact that dosage treatments can have on the quality of foam produced upon pouring, and therefore have the potential to inform future sparkling winemaking practices. © 2017 Society of Chemical Industry.

Gluten-Free Sources of Fermentable Extract: Effect of Temperature and Germination Time on Quality Attributes of Teff [Eragrostis tef (zucc.) Trotter] Malt and Wort.

This study was conducted to evaluate the behavior of a white teff variety called Witkop during malting by using different parameters (germination temperature and duration) and to identify the best malting program. Samples were evaluated for standard quality malt and wort attributes, pasting characteristics, ß-glucan and arabinoxylan content, and sugar profile. It was concluded that malting teff at 24 °C for 6 days produced acceptable malt in terms of quality attributes and sugar profile for brewing. The main attributes were 80.4% extract, 80.9% fermentability, 1.53 mPa s viscosity, 7.4 EBC-U color, 129 mg/L FAN, and 72.1 g/L of total fermentable sugars. Statistical analysis showed that pasting characteristics of teff malt were negatively correlated with some malt quality attributes, such as extract and fermentability. Witkop teff appeared to be a promising raw material for malting and brewing. However, the small grain size may lead to difficulties in handling malting process, and a bespoke brewhouse plant should be developed for the production at industrial scale.

Transcriptional and Post-Transcriptional Modulation of SPI1 and SPI2 Expression by ppGpp, RpoS and DksA in Salmonella enterica sv Typhimurium.

The expression of genes within Salmonella Pathogenicity Islands 1 and 2 (SPI1, SPI2) is required to facilitate invasion and intracellular replication respectively of S. Typhimurium in host cell lines. Control of their expression is complex and occurs via a variety of factors operating at transcriptional and post-transcriptional levels in response to the environmental stimuli found within the host. Several of the factors that modulate SPI1 and SPI2 expression are involved in the redistribution or modification of RNA polymerase (RNAP) specificity. These factors include the bacterial alarmone, ppGpp, the alternative sigma factor, RpoS, and the RNAP accessory protein, DksA. In this report we show not only how these three factors modulate SPI1 and SPI2 expression but also how they contribute to the 'phased' expression of SPI1 and SPI2 during progress through late-log and stationary phase in aerobic rich broth culture conditions. In addition, we demonstrate that the expression of at least one SPI1-encoded protein, SipC is subject to DksA-dependent post-transcriptional control.

Nutritional and metabolic requirements for the infection of HeLa cells by Salmonella enterica serovar Typhimurium.

Salmonella is the causative agent of a spectrum of human and animal diseases ranging from gastroenteritis to typhoid fever. It is a food--and water--borne pathogen and infects via ingestion followed by invasion of intestinal epithelial cells and phagocytic cells. In this study we employed a mutational approach to define the nutrients and metabolic pathways required by Salmonella enterica serovar Typhimurium during infection of a human epithelial cell line (HeLa). We deleted the key glycolytic genes, pfkA and pfkB to show that S. Typhimurium utilizes glycolysis for replication within HeLa cells; however, glycolysis was not absolutely essential for intracellular replication. Using S. Typhimurium strains deleted for genes encoding components of the phosphotransferase system and glucose transport, we show that glucose is a major substrate required for the intracellular replication of S. Typhimurium in HeLa cells. We also deleted genes encoding enzymes involved in the utilization of gluconeogenic substrates and the glyoxylate shunt and show that neither of these pathways were required for intracellular replication of S. Typhimurium within HeLa cells.

Lag phase is a distinct growth phase that prepares bacteria for exponential growth and involves transient metal accumulation.

Lag phase represents the earliest and most poorly understood stage of the bacterial growth cycle. We developed a reproducible experimental system and conducted functional genomic and physiological analyses of a 2-h lag phase in Salmonella enterica serovar Typhimurium. Adaptation began within 4 min of inoculation into fresh LB medium with the transient expression of genes involved in phosphate uptake. The main lag-phase transcriptional program initiated at 20 min with the upregulation of 945 genes encoding processes such as transcription, translation, iron-sulfur protein assembly, nucleotide metabolism, LPS biosynthesis, and aerobic respiration. ChIP-chip revealed that RNA polymerase was not "poised" upstream of the bacterial genes that are rapidly induced at the beginning of lag phase, suggesting a mechanism that involves de novo partitioning of RNA polymerase to transcribe 522 bacterial genes within 4 min of leaving stationary phase. We used inductively coupled plasma mass spectrometry (ICP-MS) to discover that iron, calcium, and manganese are accumulated by S. Typhimurium during lag phase, while levels of cobalt, nickel, and sodium showed distinct growth-phase-specific patterns. The high concentration of iron during lag phase was associated with transient sensitivity to oxidative stress. The study of lag phase promises to identify the physiological and regulatory processes responsible for adaptation to new environments.