The Evolution of Organismal Complexity in Angiosperms as Measured by the Information Content of Taxonomic Descriptions

We describe an information theoretic method for measuring relative organismal complexity. The complexity measure is based on the amount of information contained in formal taxonomic descriptions of organisms. We examine the utility of this measure for quantifying the complexity of plant families. The descriptions are subjective by nature, but we find a significant correlation in the complexity values of plant families from two independently authored sets of formal taxonomic descriptions. An analysis of the evolution of complexity across angiosperms found evidence of a pattern of increasing complexity. Our measure of complexity provides an operational definition of complexity that may be applied to any group of organisms and will enable further empirical studies of the evolution of complexity

How anthocyanin mutants respond to stress: the need to distinguish between stress tolerance and maximal vigour

Background: Anthocyanins are produced by plants in response to diverse stresses. Mutants that block the anthocyanin biosynthetic pathway (ABP) at various steps can easily be compared across numerous abiotic stresses. Hypothesis: Anthocyanins or their precursors are required for stress tolerance. Thus, ABP loss-of-function mutants should have proportionately lower fitness than wildtype plants under stress, compared with benign conditions. In contrast, a decrease in maximal vigour - the general capacity for growth and fecundity - should be most pronounced under benign conditions that allow luxuriant growth by the most vigorous genotypes. Tests: Determine whether, under stressful conditions, ABP loss-of-function mutants have relatively lower fitness than wildtype plants. Also, test for reduced maximal vigour by determining whether ABP mutants have comparatively decreased fitness under optimal (\u27benign\u27) growing conditions. Organism: Arabidopsis thaliana loss-of-function mutants (representing all steps in the ABP), as well as wildtype plants, in two genetic backgrounds. Methods: We grew plants under near-optimal conditions and five stress treatments (UV-B, drought, cold, low Ca:Mg, high Ni). We estimated relative fitness as an individual\u27s lifetime fertility, relative to the mean wildtype fertility in a given treatment. Results: Stress treatments significantly reduced lifetime fertility of wildtype and mutant lines. Wildtypes outperformed anthocyanin-deficient mutants under benign conditions, but as the stress increased, the difference between wildtype and mutant fitness diminished. Fitness did not increase with a mutation\u27s sequential position in the ABP, nor was there an effect of the ability to produce flavonols on fertility. Conclusions: Mutations in the ABP did not reduce stress tolerance. Rather, the loss of ABP function reduced maximal vigour, most evidently in near-optimal growth conditions. © 2010 Eric J. von Wettberg

Topology of Streptococcus pneumoniae CpsC, a Polysaccharide Copolymerase and Bacterial Protein Tyrosine Kinase Adaptor Protein

In Gram-positive bacteria, tyrosine kinases are split into two proteins, the cytoplasmic tyrosine kinase and a transmembrane adaptor protein. In Streptococcus pneumoniae this transmembrane adaptor is CpsC, with the C-terminus of CpsC critical for interaction and subsequent tyrosine kinase activity of CpsD. Topology predictions suggest CpsC has two transmembrane domains, with the N and C-termini present in the cytoplasm. In order to investigate CpsC topology, we used a chromosomal HA-tagged Cps2C protein in D39. Incubation of both protoplasts and membranes with the CP-B resulted in complete degradation of HA-Cps2C in all cases, indicating that the C-terminus of Cps2C was likely extra-cytoplasmic, and hence the protein's topology was not as predicted. Similar results were seen with membranes from TIGR4, indicating Cps4C also showed similar topology. A chromosomally encoded fusion of HA-Cps2C and Cps2D was not degraded by CP-B, suggesting that the fusion fixed the C-terminus within the cytoplasm. However, capsule synthesis was unaltered by this fusion. Detection of the CpsC C-terminus by flow cytometry indicated that it was extra-cytoplasmic in approximately 30% of cells. Interestingly, a mutant in the protein tyrosine phosphatase CpsB had a significantly greater proportion of positive cells, although this affect was independent of its phosphatase activity. Our data indicate that CpsC possesses a varied topology, with the C-terminus flipping across the cytoplasmic membrane where it interacts with CpsD in order to regulate tyrosine kinase activity.Jonathan J. Whittall, Renato Morona, Alistair J. Standis

Tyrosine phosphorylation enhances activity of pneumococcal autolysin LytA

For a long time tyrosine phosphorylation has been recognized as a crucial post translational regulatory mechanism in eukaryotes. However, only in the past decade has recognition been given to the crucial importance of bacterial tyrosine phosphorylation as an important regulatory feature of pathogenesis. This study describes the effect of tyrosine phosphorylation on the activity of a major virulence factor of the pneumococcus, the autolysin LytA, and a possible connection to the Streptococcus pneumoniae capsule synthesis regulatory proteins (CpsB, CpsC & CpsD). We show that in vitro pneumococcal tyrosine kinase, CpsD, and the protein tyrosine phosphatase, CpsB, act to phosphorylate and dephosphorylate LytA. Furthermore, this modulates LytA function in vitro with phosphorylated LytA binding more strongly to the choline analogue DEAE. A phospho-mimetic (Y264E) mutation of the LytA phosphorylation site displayed similar phenotypes as well as an enhanced dimerization capacity. Similarly, tyrosine phosphorylation increased LytA amidase activity, as evidenced by a turbidometric amidase activity assay. Similarly, when the phospho-mimetic mutation was introduced in the chromosomal lytA of S. pneumoniae, autolysis occurred earlier and at an enhanced rate. This study thus describes to our knowledge the first functional regulatory effect of tyrosine phosphorylation on a non-capsule related protein in the pneumococcus, and suggests a link between the regulation of LytA-dependent autolysis of the cell, and the biosynthesis of capsular polysaccharide.Alistair J. Standish, Jonathan J. Whittall and Renato Moron

Stimulation of Myofibrillar Protein Synthesis in Hindlimb Suspended Rats by Resistance Exercise and Growth Hormone

The objective of this study was to determine the ability of a single bout of resistance exercise alone or in combination with recombinant human growth hormone (rhGH) to stimulate myofibrillar protein synthesis (Ks) in hindlimb suspended (HLS) adult female rats. Plantar flexor muscles were stimulated with resistance exercise, consisting of 10 repetitions of ladder climbing on a 1 m grid (85 deg.), carrying an additional 50% of their body weight attached to their tails. Saline or rhGH (1 mg/kg) was administered 30' prior to exercise, and Ks was determined with a constant infusion of H-3-Leucine at 15', 60', 180', and 360' following exercise. Three days of HLS depressed Ks is approx. equal to 65% and 30-40% in the soleus and gastrocnemius muscles, respectively (p is less than or equal to 0.05). Exercise increased soleus Ks in saline-treated rats 149% 60' following exercise (p less than or equal to 0.05), decaying to that of non-exercised animals during the next 5 hours. Relative to suspended, non-exercised rats rhGH + exercise increased soleus Ks 84%, 108%, and 72% at 15', 60' and 360' following exercise (p is less than or equal to 0.05). Gastrocnemius Ks was not significantly increased by exercise or the combination of rhGH and exercise up to 360' post-exercise. Results from this study indicate that resistance exercise stimulated Ks 60' post-exercise in the soleus of HLS rats, with no apparent effect of rhGH to enhance or prolong exercise-induced stimulation. Results suggests that exercise frequency may be important to maintenance of the slow-twitch soleus during non-weightbearing, but that the ability of resistance exercise to maintain myofibrillar protein content in the gastrocnemius of hindlimb suspended rats cannot be explained by acute stimulation of synthesis

Public understanding of sustainable diets and changes towards sustainability: A qualitative study in a UK population sample.

Dietary consumption contributes significantly to the environmental impacts of daily life. Changes to consumption are required, but limited work investigates the reasoning underlying relevant dietary choices. This study aimed to explore public understanding of sustainable diets and any willingness or attempts to make changes towards sustainability in a sample of the UK population. A qualitative approach was used. Twenty-one participants (10 males; predominantly young adults; with a range of living circumstances and cooking responsibilities) were interviewed. Interviews were analysed using inductive thematic analysis. Four themes were identified that related to understanding sustainable diets: 'Consistent with the definition by the FAO', 'Multiple benefits', 'Unsure' and 'Competing Interests'. Four themes related to making changes: 'Willing, but unsure', 'Small easy changes', 'Enablers' and 'Barriers'. An additional theme 'COVID-19 pandemic' reflected the period when the work was done (February-May 2021). Within these themes, participants were able to define sustainable eating in a manner that was consistent with and incorporated aspects of the definition by the FAO, could identify sustainable actions that they were undertaking or could undertake, and considered these to be beneficial, but there was a lot of uncertainty, and alternative or competing definitions and actions were also given. Participants were also willing to make changes to make their diet more sustainable, and preferences were expressed for small easy changes of high impact, but there was again considerable uncertainty as to what changes to make. Caution due to the small and select sample is required, but suggestions from this work include increasing awareness and knowledge of the environmental impacts of dietary choices, focusing on small easy changes of likely impact and personal benefit, and increasing availability and accessibility to sustainable diets

Arachidonic acid stress impacts pneumococcal fatty acid homeostasis

Published: 11 May 2018Free fatty acids hold dual roles during infection, serving to modulate the host immune response while also functioning directly as antimicrobials. Of particular importance are the long chain polyunsaturated fatty acids, which are not commonly found in bacterial organisms, that have been proposed to have antibacterial roles. Arachidonic acid (AA) is a highly abundant long chain polyunsaturated fatty acid and we examined its effect upon Streptococcus pneumoniae. Here, we observed that in a murine model of S. pneumoniae infection the concentration of AA significantly increases in the blood. The impact of AA stress upon the pathogen was then assessed by a combination of biochemical, biophysical and microbiological assays. In vitro bacterial growth and intra-macrophage survival assays revealed that AA has detrimental effects on pneumococcal fitness. Subsequent analyses demonstrated that AA exerts antimicrobial activity via insertion into the pneumococcal membrane, although this did not increase the susceptibility of the bacterium to antibiotic, oxidative or metal ion stress. Transcriptomic profiling showed that AA treatment also resulted in a dramatic down-regulation of the genes involved in fatty acid biosynthesis, in addition to impacts on other metabolic processes, such as carbon-source utilization. Hence, these data reveal that AA has two distinct mechanisms of perturbing the pneumococcal membrane composition. Collectively, this work provides a molecular basis for the antimicrobial contribution of AA to combat pneumococcal infections.Bart A. Eijkelkamp, Stephanie L. Begg, Victoria G. Pederick, Claudia Trapetti, Melissa K. Gregory, Jonathan J. Whittall, James C. Paton and Christopher A. McDevit