Investigation of the protein profile of silkworm (Bombyx mori) pupae reared on a well-calibrated artificial diet compared to mulberry leaf diet.

BACKGROUND: Silkworm pupae is the main by-product of the sericulture industry with an interesting nutritional profile, especially in terms of proteins. In consideration of its possible use as a food or food ingredient in Western countries, a comparative proteomic experiment has been performed to investigate the differences of the protein profile of male and female silkworm pupae reared on mulberry leaves or on an artificial diet. METHODS: The nutritional profile of lyophilized silkworm pupae in terms of dry matter and ash was evaluated according to the AOAC procedures, the total nitrogen content was determined by a nitrogen analyzer and the silkworm pupae gross energy value was measured using an adiabatic calorimetric bomb. The comparative proteomic analysis was performed on male and female silkworm pupae reared on mulberry leaves or on the artificial diet. Proteins were separated by two-dimensional electrophoresis and, after a multivariate statistical analysis, the differentially expressed proteins were identified by LC-MS/MS. RESULTS: The comparative proteomic approach highlighted 47 silkworm pupae proteins differentially expressed comparing diet and gender. PCA analysis showed that seven proteins were more effective in discriminating the sex and five were more effective in discriminating the diet type. In spite of the above-mentioned differences in the silkworm pupae protein profile, no strong alteration of the pupa physiological traits have been demonstrated, suggesting a general silkworm pupae flexibility to adapt to a well-balanced artificial diet. Differences in lipid transport and metabolism were found among the experimental groups, that might have a relevant effect on the timing and on hormone secretion. This aspect may also affect silk production, as univoltine strains are the most productive. The proteomic data provided in this work, may offer a contribution in understanding also the influence of gender and farming strategy on the allergen profile of Bombyx mori, when used as food or as a food ingredient. Female silkworm pupae reared on mulberry leaves seemed to contain lower levels of known allergens than those reared in the other experimental conditions; these findings will have to be taken into account when farming B. mori for food production purposes. However, our results need to be supported by further characterization of the allergenic potential of B. mori.

A multidisciplinary study on the effects of phloem-limited viruses on the agronomical performance and berry quality of Vitis vinifera cv. Nebbiolo.

Viral infections are known to have a detrimental effect on grapevine yield and performance, but there is still a lack of knowledge about their effect on the quality and safety of end products. Vines of Vitis vinifera cv. Nebbiolo clone 308, affected simultaneously by Grapevine leafroll-associated virus 1 (GLRaV-1), Grapevine virus A (GVA), and Rupestris stem pitting associated virus (RSPaV), were subjected to integrated analyses of agronomical performance, grape berry characteristics, instrumental texture profile, and proteome profiling. The comparison of performance and grape quality of healthy and infected vines cultivated in a commercial vineyard revealed similar shoot fertility, number of clusters, total yield, with significant differences in titratable acidity, and resveratrol content. Also some texture parameters such as cohesiveness and resilience were altered in berries of infected plants. The proteomic analysis of skin and pulp visualized about 400 spots. The ANOVA analysis on 2D gels revealed significant differences among healthy and virus-infected grape berries for 12 pulp spots and 7 skin spots. Virus infection mainly influenced proteins involved in the response to oxidative stress in the berry skin, and proteins involved in cell structure metabolism in the pulp.

ADI pathway and histidine decarboxylation are reciprocally regulated in Lactobacillus hilgardii ISE 5211: proteomic evidence.

Amine production by amino acid decarboxylation is a common feature that is used by lactic acid bacteria (LAB) to complement lactic fermentation, since it is coupled with a proton-extruding antiport system which leads to both metabolic energy production and the attenuation of intracellular acidity. Analogous roles are played in LAB by both malolactic fermentation (MLF) and the arginine deiminase (ADI) pathway. The present investigation was aimed at establishing reciprocal interactions between amino acid decarboxylation and the two above mentioned routes. The analyses were carried out on a Lactobacillus hilgardii strain (ISE 5211) that is able to decarboxylate histidine to histamine, which had previously been isolated from wine and whose complete genome is still unknown. The 2DE proteomic approach, followed by MALDI TOF-TOF and De Novo Sequencing, was used to study the protein expression levels. The experimental evidence has indicated that malate does not influence histidine decarboxylase (HDC) biosynthesis and that histidine does not affect the malolactic enzyme level. However, the expression of the ADI route enzymes, arginine deiminase and ornithine transcarbamylase, is down-regulated by histidine: this biosynthetic repression is more important (4-fold) in cultures that are not supplemented with arginine, but is also significant (2-fold) in an arginine supplemented medium that normally induces the ADI pathway. On the other hand, arginine partially represses HDC expression, but only when histidine and arginine are both present in the culture medium. This proteomic study has also pointed out a down-regulation exerted by histidine over sugar metabolism enzymes and a GroEL stress protein. These data, together with the reciprocal antagonism between arginine deimination and histidine decarboxylation, offer clue keys to the understanding of the accumulation of lactate, amine, ammonia and ethylcarbamate in wine, with consequent implications on different health risk controls.