Metarhizium anisopliae, a fungal pathogen of terrestrial arthropods, kills the aquatic larvae of Aedes aegypti, the vector of dengue and yellow fever. The fungus kills without adhering to the host cuticle. Ingested conidia also fail to germinate and are expelled in fecal pellets. This study investigates the mechanism by which this fungus adapted to terrestrial hosts kills aquatic mosquito larvae. Genes associated with the M. anisopliae early pathogenic response (proteinases Pr1 and Pr2, and adhesins, Mad1 and Mad2) are upregulated in the presence of larvae, but the established infection process observed in terrestrial hosts does not progress and insecticidal destruxins were not detected. Protease inhibitors reduce larval mortality indicating the importance of proteases in the host interaction. The Ae. aegypti immune response to M. anisopliae appears limited, whilst the oxidative stress response gene encoding for thiol peroxidase is upregulated. Cecropin and Hsp70 genes are downregulated as larval death occurs, and insect mortality appears to be linked to autolysis through caspase activity regulated by Hsp70 and inhibited, in infected larvae, by protease inhibitors. Evidence is presented that a traditional host-pathogen response does not occur as the species have not evolved to interact. M. anisopliae retains pre-formed pathogenic determinants which mediate host mortality, but unlike true aquatic fungal pathogens, does not recognise and colonise the larval host.

Quorum sensing involving acyl homoserine lactones (AHLs) is a density-dependent form of intercellular communication that occurs in many different members of the group Proteobacteria. However, to date, there have been few investigations of its occurrence in cyanobacteria. Here, using both a bioreporter Agrobacterium tumefaciens NTL4 (PZLR4) and mass spectrometry, we provide evidence of N-octanoyl homoserine lactone (C8-AHL) production in axenic cultures of the cyanobacterium Gloeothece PCC6909 and its sheathless mutant PCC6909/1. Accumulation of C8-AHL in the culture medium of laboratory cultures of Gloeothece followed a pattern characteristic of the phenomenon of autoinduction, a common feature of functional AHL-based quorum-sensing systems. Analysis by two-dimensional gel electrophoresis showed that, in response to treatment with C8-AHL, early growth-stage cells of PCC6909/1 showed changes in expression of 43 proteins compared with untreated cells. Among the 15 proteins that showed more than a twofold change in expression were RuBisCo, glutamate synthase, chorismate synthase, a member of the LysR family of transcriptional regulators (all upregulated), and enolase and aldolase, both of which were downregulated. The significance of such changes in response to C8-AHL is discussed in relation to carbohydrate and amino-acid metabolism and involvement of Gloeothece in biofilms.

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In this study, the frequency of BRAF mutation was investigated in a series of 67 cases of papillary thyroid cancer (PTC) in patients from Ukraine. Thirty-two patients were aged 30 years or older at the time of diagnosis and 35 were under 16. Tumour was microdissected from paraffin wax-embedded sections, DNA extracted, and the presence of the BRAF T1796A mutation demonstrated by two different methods: PCR followed by restriction enzyme digestion or primer extension assay and detection using MALDI-TOF mass spectrometry. Eighteen (58%) of the adult cases, but only one of the 35 cases aged less than 16 harboured a BRAF T1796A mutation. There was complete agreement between the two methods used, suggesting that the MALDI-TOF assay is a robust alternative to conventional mutation analysis. RET rearrangement was also examined in the young cohort. The overall frequency of RET rearrangement was 45.7%. Eight of the younger group of patients were born after 1 December 1986 and were therefore not exposed to radioiodine in fallout from Chernobyl. None of the PTCs from these eight patients were positive for BRAF mutation. The frequency of RET rearrangement was 44% in the 27 cases exposed to radiation and 50% in the eight not exposed. These results suggest that the different molecular biological profiles observed are associated with the age of the patient at diagnosis with PTC, rather than being associated with radiation exposure.