Identification and characterisation of anti - Pseudomonas aeruginosa proteins in mucus of the brown garden snail, Cornu aspersum

Background: Novel antimicrobial treatments are urgently needed. Previous work has shown that the mucus of the brown garden snail (Cornu aspersum) has antimicrobial properties, in particular against type culture collection strains of Pseudomonas aeruginosa. We hypothesised that it would also be effective against clinical isolates of the bacterium and that investigation of fractions of the mucus would identify one or more proteins with anti-pseudomonal properties, which could be further characterised. Materials and methods: Mucus was extracted from snails collected from the wild. Antimicrobial activity against laboratory and clinical isolates of Ps. aeruginosa was determined in disc diffusion assays. Mucus was purified using size exclusion chromatography and fractions containing anti-pseudomonal activity identified. Mass spectroscopy and high performance liquid chromatography analysis of these fractions yielded partial peptide sequences. These were used to interrogate an RNA transcriptome generated from whole snails. Results: Mucus from C. aspersum inhibited growth of type collection strains and clinical isolates of Ps. aeruginosa. Four novel C. aspersum proteins were identified; at least three are likely to have antimicrobial properties. The most interesting is a 37.4 kDa protein whilst smaller proteins, one 17.5 kDa and one 18.6 kDa also appear to have activity against Ps. aeruginosa. Conclusions: The study has identified novel proteins with antimicrobial properties which could be used to develop treatments for use in human medicine.

Regulation of α-amylase formation and gene expression in the developing wheat embryo : Role of abscisic acid, the osmotic environment and gibberellin

Embryos in developing wheat (Triticum aestivum L., cv. Sappo) grains (15-40 d post anthesis, dpa) contain no detectable α-amylase. When isolated from the grain they produce the enzyme even though they do not germinate. Younger (15 dpa) and older (45 dpa) embryos produce only a group of isozymes of low isoelectric point (pI): at intermediate ages low-pI and high-pI groups appear. The low-pI group is formed first, about 6 h after isolation, followed by the high-pI group at 16h. The formation of high-pI isoenzymes is prevented by abscisic acid and osmoticum, which also suppress the accumulation of high-pI mRNA. Almost all of the low-pI isoenzymes are unaffected by these two factors. Low-pI mRNA transcripts are present in embryos in situ but are not translated. Translation occurs when embryos are isolated, though there appears to be no further accumulation of low-pI mRNA. Addition of gibberellic acid to isolated embryos causes a great increase in accumulated high-pI mRNA, but only a small increase in low-pI message. Added gibberellic acid enables younger and older embryos to produce high-pI isoenzymes. The regulation of α-amylase gene expression and enzyme formation in developing embryos in situ is discussed in the light of these findings.