Quantification of algal biofilms colonising building materials: chlorophyll a measured by PAM-fluorometry as a biomass parameter

The aim of this study was to quantify algal colonisation on anthropogenic surfaces (viz. building facades and roof tiles) using chlorophyll a (chl a) as a specific biomarker. Chl a was estimated as the initial fluorescence F0 of 'dark adapted' algae using a pulse-modulated fluorometer (PAM-2000). Four isolates of aeroterrestrial green algae and one aquatic isolate were included in this study. The chl a concentration and F0 showed an exponential relationship in the tested range between 0 and 400 mg chl a m(-2). The relationship was linear at chl a concentrations <20 mg m(-2). Exponential and linear models are presented for the single isolates with large coefficients of determination (exponential: r2 > 0.94, linear: r2 > 0.92). The specific power of this fluorometric method is the detection of initial algal colonisation on surfaces in thin or young biofilms down to 3.5 mg chl a m(-2), which corresponds to an abundances of the investigated isolates between 0.2 and 1.5 million cells cm(-2).     

Polymorphic microsatellite loci for studies of the Ozark hellbender (Cryptobranchus alleganiensis bishopi)

The hellbender is the only North American member of the aquatic salamander family Cryptobranchidae and is a species of conservation concern across its range. We developed eight polymorphic microsatellite loci for hellbenders using a magnetic bead enrichment protocol and a PCR-based detection technique. Allelic diversity averaged 4.0 (±1.8 SD) per locus and heterozygosity averaged 0.56 (±0.30 SD). The hellbender is rare and difficult to study due to its cryptic life history. These loci will provide a valuable resource for population studies, which could inform future conservation and management decisions.     

Small molecules in an RNAi world

In this Opinion, we compare and contrast small molecules and RNAi. We discuss the advantages and disadvantages of both technologies focusing on timing, specificity, dose and therapeutic use.     

Novel biocatalysts for white biotechnology

White Biotechnology uses microorganisms and enzymes to manufacture a large variety of chemical products. Therefore, the demand for new and useful biocatalysts is steadily and rapidly increasing. We have developed methods for the isolation of new enzyme genes, constructed novel expression systems, and optimized existing enzymes for biotechnological applications by methods of directed evolution. Furthermore, we have isolated and characterized biocatalysts relevant for the preparation of enantiopure compounds.     

The declining Spadefoot toad, Pelobates fuscus (Pelobatidae): paleo and recent environmental changes as a major influence on current population structure and status

Populations of the European Spadefoot toad (Pelobates fuscus) have experienced recent declines all over Europe, but these appear to be more intense in north and western Europe. Due to the toad’s fossorial nature and specific habitat requirements, environmental conditions have played a major role in structuring current populations. We examined the phylogeographic structure in P. fuscus from 16 localities throughout Europe using mitochondrial cytochrome b gene sequence analysis. Sequence divergence among haplotypes was low (0.54±0.15%). Three very closely related haplotypes occupy northern and western parts of Europe whereas 12 others were observed among samples from south-eastern Europe, including the Balkans. Our results suggest that toads only recently colonized the northern and western parts of Europe following glacial retreat. This expansion probably took place in steppic-like areas during the younger Dryas cold interval, about 12,900–11,500 years ago. Restricted gene flow with an isolation-by-distance population structure characterises a major part of its distribution range. Based on our results we suggest that the northern and western lineages should be considered as distinct conservation units, while the south-eastern populations from the refugial areas, where nearly all genetic polymorphism occurs and populations appear less vulnerable, should receive special attention.     

The lid is a structural and functional determinant of lipase activity and selectivity

In several lipases access to the enzyme active site is regulated by the position of a mobile structure named the lid. The role of this region in modulating lipase function is reviewed in this paper analysing the results obtained with three different recombinant lipases modified in the lid sequence: Candida rugosa lipase isoform 1 (CRL1), Pseudomonas fragi lipase (PFL) and Bacillus subtilis lipase A (BSLA). A CRL chimera enzyme obtained by replacing its lid with that of another C. rugosa lipase isoform (CRL1LID3) was found to be affected in both activity and enantioselectivity in organic solvent. Variants of the PFL protein in which three polar lid residues were replaced with amino acids strictly conserved in homologous lipases displayed altered chain length preference profile and increased thermostability. On the other hand, insertion of lid structures from structurally homologous enzymes into BSLA, a lipase that naturally does not possess such a lid structure, caused a reduction in the enzyme activity and an altered substrate specificity. These results strongly support the concept that the lid plays an important role in modulating not only activity but also specifity, enantioselectivity and stability of lipase enzymes.     

Small molecule screening by imaging

Useful small molecule tools can be discovered in imaging screens that measure phenotype in single cells or small organisms. Recent examples include identification of small molecule inhibitors of processes such as cell migration, cytokinesis, mitotic spindle length determination, melanogenesis, aggresome formation, membrane transport and nuclear export. Imaging screens are currently limited by challenges in the areas of image analysis and target identification. We discuss the use of model organisms such as zebrafish in screens and review different methods of target identification. The emerging field of automated image analysis is also introduced.