Antibodies are important tools for experimental research and medical applications. Most antibodies are composed of two heavy and two light chains. Both chains contribute to the antigen-binding site which is usually Xat or concave. In addition to these conventional antibodies, llamas, other camelids, and sharks also produce antibodies composed only of heavy chains. The antigen-binding site of these unusual heavy chain antibodies (hcAbs) is formed only by a single domain, designated VHH in camelid hcAbs and VNAR in shark hcAbs. VHH and VNAR are easily produced as recombinant proteins, designated single domain antibodies (sdAbs) or nanobodies. The CDR3 region of these sdAbs possesses the extraordinary capacity to form long Wngerlike extensions that can extend into cavities on antigens, e.g., the active site crevice of enzymes. Other advantageous features of nanobodies include their small size, high solubility, thermal stability, refolding capacity, and good tissue penetration in vivo. Here we review the results of several recent proofof-principle studies that open the exciting perspective of using sdAbs for modulating immune functions and for targeting toxins and microbes.

Metagenomics research has recently thrived due to DNA sequencing technologies improvement, driving the emergence of new analysis tools and the growth of taxonomic databases. However, there is no all-purpose strategy that can guarantee the best result for a given project and there are several combinations of software, parameters and databases that can be tested. Therefore, we performed an impartial comparison, using statistical measures of classification for eight bioinformatic tools and four taxonomic databases, defining a benchmark framework to evaluate each tool in a standardized context. Using in silico simulated data for 16S rRNA amplicons and whole metagenome shotgun data, we compared the results from different software and database combinations to detect biases related to algorithms or database annotation. Using our benchmark framework, researchers can define cut-off values to evaluate the expected error rate and coverage for their results, regardless the score used by each software. A quick guide to select the best tool, all datasets and scripts to reproduce our results and benchmark any new method are available at https://github.com/Ales-ibt/Metagenomic-benchmark. Finally, we stress out the importance of gold standards, database curation and manual inspection of taxonomic profiling results, for a better and more accurate microbial diversity description.

Conus species are characterized by their hyperdiverse toxins, encoded by a few gene superfamilies. Our phylogenies of the genus, based on mitochondrial genes, confirm previous results that C. californicus is highly divergent from all other species. Genetic and biochemical analysis of their venom peptides comprise the fifteen most abundant conopeptides and over 50 mature cDNA transcripts from the venom duct. Although C. californicus venom retains many of the general properties of other Conus species, they share only half of the toxin gene superfamilies found in other Conus species. Thus, in these two lineages, approximately half of the rapidly diversifying gene superfamilies originated after an early Tertiary split. Such results demonstrate that, unlike endogenously acting gene families, these genes are likely to be significantly more restricted in their phylogenetic distribution. In concordance with the evolutionary duistance of C. californicus from other species, there are aspects of prey-capture behavior and prey preferences of this species that diverges significantly from all other Conus.

The e¡ects of dietary astaxanthin supplemented at 0, 40, 80 or 150 mg astaxanthin kg À1 on growth, survival, moult frequency, osmoregulatory capacity (OC) and selected metabolic and haematological variables in Litopenaeus vannamei acclimated to low-salinity water (3 g L À 1 ) were evaluated. Supplemented astaxanthin at 80 mg kg À1 improved growth, survival and moult frequency in shrimp. The lowest OC was also exhibited in shrimp fed with dietary astaxanthin at 80 mg kg À1 . Shrimp haemolymph concentrations of glucose, lactate, haemocyanin and total haemocyte count were all signi¢cantly enhanced by feeding the diet supplemented with 80 mg astaxanthin kg À1 compared with shrimp fed with the other diets. On the basis of these results, dietary astaxanthin supplementation of 80 mg kg À1 is recommended for juvenile L. vannamei cultured in low-salinity water. Physiological, metabolic and haematological responses in L. vannamei M Flores et al. r 2007 The Authors Journal Compilation r 2007 Blackwell Publishing Ltd, Aquaculture Research, 38, 740^747 Median values and con¢dence interval (95%) in parenthesis. Di¡erent letters indicate a signi¢cant di¡erence on responses (Po0.05). DGC, daily growth coe⁄cient; OC, osmoregulatory capacity; THC, total haemocyte count. Aquaculture Research, 2007, 38, 740^747 Physiological, metabolic and haematological responses in L. vannamei M Flores et al.