BackgroundSpiders are known for their predatory efficiency and for their high capacity of digesting relatively large prey. They do this by combining both extracorporeal and intracellular digestion. Whereas many high throughput (“-omics”) techniques focus on biomolecules in spider venom, so far this approach has not yet been applied to investigate the protein composition of spider midgut diverticula (MD) and digestive fluid (DF).ResultsWe here report on our investigations of both MD and DF of the spider Nephilingis (Nephilengys) cruentata through the use of next generation sequencing and shotgun proteomics. This shows that the DF is composed of a variety of hydrolases including peptidases, carbohydrases, lipases and nuclease, as well as of toxins and regulatory proteins. We detect 25 astacins in the DF. Phylogenetic analysis of the corresponding transcript(s) in Arachnida suggests that astacins have acquired an unprecedented role for extracorporeal digestion in Araneae, with different orthologs used by each family. The results of a comparative study of spiders in distinct physiological conditions allow us to propose some digestion mechanisms in this interesting animal taxon.ConclusionAll the high throughput data allowed the demonstration that DF is a secretion originating from the MD. We identified enzymes involved in the extracellular and intracellular phases of digestion. Besides that, data analyses show a large gene duplication event in Araneae digestive process evolution, mainly of astacin genes. We were also able to identify proteins expressed and translated in the digestive system, which until now had been exclusively associated to venom glands.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3048-9) contains supplementary material, which is available to authorized users.

Scorpions are among the oldest terrestrial arthropods and they have passed through small morphological changes during their evolutionary history on land. They are efficient predators capable of capturing and consuming large preys and due to envenomation these animals can become a human health challenge. Understanding the physiology of scorpions can not only lead to evolutionary insights but also is a crucial step in the development of control strategies. However, the digestive process in scorpions has been scarcely studied. In this work, we describe the combinatory use of next generation sequencing, proteomic analysis and biochemical assays in order to investigate the digestive process in the yellow scorpion Tityus serrulatus, mainly focusing in the initial protein digestion. The transcriptome generated database allowed the quantitative identification by mass spectrometry of different enzymes and proteins involved in digestion. All the results suggested that cysteine cathepsins play an important role in protein digestion. Two digestive cysteine cathepsins were isolated and characterized presenting acidic characteristics (pH optima and stability), zymogen conversion to the mature form after acidic activation and a cross-class inhibition by pepstatin. A more elucidative picture of the molecular mechanism of digestion in a scorpion was proposed based on our results from Tityus serrulatus. The midgut and midgut glands (MMG) are composed by secretory and digestive cells. In fasting animals, the secretory granules are ready for the next predation event, containing enzymes needed for alkaline extra-oral digestion which will compose the digestive fluid, such as trypsins, astacins and chitinase. The digestive vacuoles are filled with an acidic proteolytic cocktail to the intracellular digestion composed by cathepsins L, B, F, D and legumain. Other proteins as lipases, carbohydrases, ctenitoxins and a chitolectin with a perithrophin domain were also detected. Evolutionarily, a large gene duplication of cathepsin L occurred in Arachnida with the sequences from ticks being completely divergent from other arachnids probably due to the particular selective pressures over this group.

28Coccidioides posadasii is a pathogenic fungus that causes coccidioidomycosis in many arid regions of 29 the Americas. One of these regions is bordered by the Caribbean Sea, and the surrounding 30 landscape may play an important role in the dispersion of C. posadasii across South America 31 through southeastern Mexico, Honduras, Guatemala and Venezuela. Comparative phylogenomic 32 analyses of C. posadasii reveal that clinical strains from Venezuela are genetically distinct from the 33 North American populations found in Arizona (AZ), Texas, Mexico, and the rest of South America 34 (TX/MX/SA). We find evidence for admixture between the Venezuela and the North American 35 populations of C. posadasii in Central America. As expected, the proportion of Venezuelan alleles in 36 the admixed population decreases as latitude (and distance from Venezuela) increases. Our results 37 indicate that the population in Venezuela may have been subjected to a recent bottleneck, and 38shows strong population structure. This analysis provides insight into potential for Coccidioides 39 spp. to invade new regions. 40

Sporotrichosis is a subcutaneous infection caused by fungi from the genus Sporothrix. The disease is transmitted by inoculation of infective particles found in plant-contaminated material or diseased animals, characterizing the classic sapronotic and emerging zoonotic transmission, respectively. Since 1998, Brazil has experienced a zoonotic sporotrichosis epidemic due to S. brasiliensis, centered in the state of Rio de Janeiro. Our observation of feline sporotrichosis cases in Brasília (Midwestern Brazil), around 900 km away from Rio de Janeiro, led us to question whether the epidemic caused by S. brasiliensis has spread from the epicenter in Rio de Janeiro, emerged independently in the two locations, or whether the disease has been present and unrecognized in Midwestern Brazil. A retrospective analysis of 91 human and 4 animal cases from Brasília, ranging from 1993 to 2018, suggests the occurrence of both sapronotic and zoonotic transmission. Molecular typing identified S. schenckii as the agent in two animals and all seven human patients from which we were able to recover clinical isolates. However, in two animals, the disease was caused by S. brasiliensis. Whole-genome sequence typing of seven S. brasiliensis strains suggests that isolates from Brasília are genetically distinct from those obtained at the epicenter of the outbreak in Rio de Janeiro, both in phylogenomic and population genomic analyses. The two S. brasiliensis populations seem to have separated 2.24 - 3.09 million years ago, indicating independent outbreaks or that the zoonotic S. brasiliensis outbreak might have started earlier and be spread wider in South America than previously recognized.