Sur l'origine du genre Microceratina Swanson, 1980 (Ostracoda, Eucytherurinae) et sa présence téthysienne dès le Jurassique supérieur

The discovery in the uppermost Jurassic of Lebanon of a species of the ostracod genus Microceratina Swanson, 1980 (Eucytherurinae), of which the oldest known species was until now of Maastrichtian age, confirms the Tethyan origin of this genus. Two new species are created: Microceratina bhannesensis nov. sp. from the Upper Jurassic (Kimmeridgian) of Lebanon, and Microceratina azazoulensis nov. sp. from the Cenomanian of Morocco. The genera Chapmanicytherura Weaver, 1982 and Erratacytheridea Herrig et al., 1997, are considered as probable junior synonyms of Microceratina. An exhaustive bibliographical analysis allowed to identifying several other Cretaceous species susceptible to be assigned to the genus Microceratina.     

Purification and enzymological characterization of murine neurotrypsin

An increasing number of studies indicate that serine proteases play an important role in structural plasticity associated with learning and memory formation. Neurotrypsin is a multidomain serine protease located at the presynaptic terminal of neurons. It is thought to be crucial for cognitive brain functions. A deletion in the neurotrypsin gene causes severe mental retardation in humans. For a biochemical characterization, we produced murine neurotrypsin recombinantly in a eukaryotic expression system using myeloma cells. From the culture medium we purified neurotrypsin using heparin-, hydrophobic interaction- and immobilized metal affinity chromatography. For an enzymological characterization two fragments of agrin containing the natural cleavages sites of neurotrypsin were used as substrates. The highest catalytic activity of neurotrypsin was observed in the pH range between 7.0 and 8.5. Calcium ions were required for neurotrypsin activity and an ionic strength exceeding 500 mM decreased substrate cleavage. Site-specific mutations of the amino acids flanking the scissile bonds showed that cleavage is highly specific and requires a basic amino acid preceded by a glutamate residue on the N-terminal side of the scissile bond. This sequence requirement argues for a unique substrate binding pocket of neurotrypsin. This observation was further substantiated by the fact that almost all tested serine protease inhibitors except dichloroisocoumarin and PMSF did not affect neurotrypsin activity.     

A pipeline for the production of antibody fragments for structural studies using transient expression in HEK 293T cells

We describe a pipeline for the rapid production of recombinant Fabs derived from mouse monoclonal antibodies suitable for use in structural studies. The pipeline is exemplified by the production of three Fabs derived from the monoclonal antibodies OX108 (anti-CD200 receptor), OX117 and OX119 (anti-SIRPgamma). Heavy and light chain variable domains were inserted into separate expression vectors containing resident constant regions using In-Fusion PCR cloning. Following transient co-expression in HEK 293T cells, secreted Fab fragments were purified by metal chelate chromatography and gel filtration using an automated procedure with yields of up to 4mg/L of cell culture. Following crystallization trials, diffracting crystals were obtained for the recombinant Fabs of OX108 and OX117, and their structures solved to 2.3A and 2.4A, respectively.     

Can body mass index predict percent body fat and changes in percent body fat with weight loss in bariatric surgery patients?

The primary objective of this study was to assess the validity of body mass index (BMI) in predicting percent body fat and changes in percent body fat with weight loss in bariatric surgery patients. Twenty-two bariatric patients (17 female, five male) began the study designed to include 12 months of testing, including data collection within 1 week presurgery and 1 month, 3 months, 6 months, and 1 year postsurgery. Five female subjects were lost to the study between 6 months and 12 months postsurgery, resulting in 17 subjects (12 female, five male) completing the 12 months of testing. Variables measured in the study included height, weight, percent fat (% fat) by hydrostatic weighing, lean mass, fat mass, and basal metabolic rate. Regression analyses predicting % fat from BMI yielded the following results: presurgery r = 0.173, p = 0.479, standard error of estimate (SEE) = 3.86; 1 month r = 0.468, p = 0.043, SEE = 4.70; 3 months r = 0.553, p = 0.014, SEE = 6.2; 6 months r = 0.611, p = 0.005, SEE = 5.88; 12 months r = 0.596, p = 0.007, SEE = 7.13. Regression analyses predicting change in % fat from change in BMI produced the following results: presurgery to 1 month r = -0.134, p = 0.583, SEE = 2.44%; 1-3 months r = 0.265, p = 0.272, SEE = 2.36%; 3-6 months r = 0.206, p = 0.398, SEE = 3.75%; 6-12 months r = 0.784, p = 0.000, SEE = 3.20. Although some analyses resulted in significant correlation coefficients (p < 0.05), the relatively large SEE values would preclude the use of BMI in predicting % fat or change in % fat with weight loss in bariatric surgery patients.     

Associated links among mtDNA glycation, oxidative stress and colony sectorization in Metarhizium anisopliae

Mycelial colonies of filamentous fungi often deteriorate when maintained on artificial media, and this can take the form of sterile sectors. We previously established that sectorization by the entomopathogenic fungus Metarhizium anisopliae correlates with intracellular accumulation of reactive oxygen species (ROS). In this study we demonstrate that: (1) H(2)O(2) increases rates of sectorization; (2) a stable strain of M. anisopliae eliminates intracellular ROS more rapidly than an unstable strain; (3) mitochondrial DNA from sectors undergoes a non-enzymatic glycation of deoxyguanosine that is not shown by genomic DNA; (4) the membrane potential of mitochondria in sector cells is decreased in comparison to wild type cells indicating loss of function; (5) DNA glycation changes the properties of DNA and (6) treating wild type mycelia with H(2)O(2) reproduced the glycation pattern shown in sectors. H(2)O(2) also reproduced the morphological changes in mitochondria and lipid droplets that occur in sector cells. Fungal sectorization thus displays aging related developmental impairments resulting from oxidative stress, suggesting a new research direction for studies on fungal colony deterioration. Mitochondrial DNA has a very high AT bias. We speculate that reducing the consequences of glycation could provide an adaptive reason for this.     

Emergency relocation of a Purple Copper Butterfly colony during roadworks: Successes and lessons learned

Summary  In 2004, the Roads and Traffic Authority (RTA) undertook a road realignment project near Lidsdale in the Central Tablelands of New South Wales. However, the RTA had not detected a population of the threatened Purple Copper Butterfly within the footprint of the project. The RTA responded promptly when notified of the butterflies' presence by stopping works, and preparing and implementing a butterfly management programme. This programme included modifying the realignment (and reducing the development footprint), supplementary planting of habitat, habitat rehabilitation and translocation of individual caterpillars from within the final footprint area. These actions seem to have safeguarded the population at least in the short term; however, further active management of the site will be needed to ensure its long-term viability. The project reinforces the importance of thorough predisturbance assessment of a site at the early planning stages, and the results and observations could be particularly informative in planning for introduction, reintroduction and translocation proposals involving the Purple Copper Butterfly.     

A structural basis for the allosteric regulation of non-hydrolysing UDP-GlcNAc 2-epimerases

The non-hydrolysing bacterial UDP-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase) catalyses the conversion of UDP-GlcNAc into UDP-N-acetylmannosamine, an intermediate in the biosynthesis of several cell-surface polysaccharides. This enzyme is allosterically regulated by its substrate UDP-GlcNAc. The structure of the ternary complex between the Bacillus anthracis UDP-GlcNAc 2-epimerase, its substrate UDP-GlcNAc and the reaction intermediate UDP, showed direct interactions between UDP and its substrate, and between the complex and highly conserved enzyme residues, identifying the allosteric site of the enzyme. The binding of UDP-GlcNAc is associated with conformational changes in the active site of the enzyme. Kinetic data and mutagenesis of the highly conserved UDP-GlcNAc-interacting residues confirm their importance in the substrate binding and catalysis of the enzyme. This constitutes the first example to our knowledge, of an enzymatic allosteric activation by direct interaction between the substrate and the allosteric activator.     

Bart's familiar quotations: the enduring biological wisdom of George A. Bartholomew

George A. Bartholomew was one of the most influential organismal biologists of the twentieth century. His insights and research were fundamental to the establishment and growth of physiological ecology and evolutionary physiology. In the process of fostering that area of science, he created a body of literature that is striking in the clarity of its thought and presentation. Here we present some of his most insightful and important quotations, group them thematically, and comment on their original context and their continuing relevance.