Search

The market of specialty eggs, such as omega-3-enriched eggs, organic eggs, and free-range eggs, is continuously growing. The nutritional composition of egg yolk can be manipulated by feed diet; however, it is not known if there is any difference in the composition of egg white proteins among different egg varieties. The purpose of the study was to compare the egg white proteins among six different egg varieties using proteomics analysis. Egg white proteins were analyzed using two-dimensional gel electrophoresis (2-DE), and 89 protein spots were subjected to LC-MS/MS. A total of 23 proteins, belonging to Gallus gallus , were identified from 72 detected protein spots. A quiescence-specific protein precursor in egg white was identified for the first time in this study. Significant differences in the abundant levels of 19 proteins (from 65 protein spots) were observed among six egg varieties. Four proteins, ovalbumin-related protein Y, cystatin, avidin, and albumin precursor, were not different among these six egg varieties. These findings suggest that the abundance, but not the composition, of egg white proteins varied among the egg varieties.

Sclerotinia sclerotiorum (Lib.) is a necrotrophic plant pathogen that is capable of infecting more than 400 plant species worldwide. The sclerotium plays important roles in the disease and fungal life cycles. The exudation of liquid droplets is a common feature during sclerotial development, but little is known regarding the nature of these exudates. A proteome-level study was performed in order to gain a better understanding of the types of proteins present in the exudates. Fifty-six proteins were identified and classified into several functional categories, including amino acid metabolism, carbohydrate metabolism, lipid and secondary metabolism, as well as energy, signal transduction, and those with unknown functions. The roles of the identified proteins are discussed within the context of sclerotial development and fungal virulence. Our results may facilitate additional studies aimed at characterizing the function of these proteins in the formation of sclerotia and the life cycle of S. sclerotiorum.

To better understand the pathogen-stress response of Brassica species against the ubiquitous hemi-biotroph fungus Leptosphaeria maculans, we conducted a comparative proteomic analysis between blackleg-susceptible Brassica napus and blackleg-resistant Brassica carinata following pathogen inoculation. We examined temporal changes (6, 12, 24, 48 and 72 h) in protein profiles of both species subjected to pathogen-challenge using two-dimensional gel electrophoresis. A total of 64 proteins were found to be significantly affected by the pathogen in the two species, out of which 51 protein spots were identified using tandem mass spectrometry. The proteins identified included antioxidant enzymes, photosynthetic and metabolic enzymes, and those involved in protein processing and signaling. Specifically, we observed that in the tolerant B. carinata, enzymes involved in the detoxification of free radicals increased in response to the pathogen whereas no such increase was observed in the susceptible B. napus. The expression of genes encoding four selected proteins was validated using quantitative real-time PCR and an additional one by Western blotting. Our findings are discussed with respect to tolerance or susceptibility of these species to the pathogen.

In order to gain a more thorough understanding of the phytopathogenic fungus, Sclerotinia sclerotiorum, we initiated a proteome-level study of the fungal mycelia and secretome. To our knowledge, this is the first comprehensive proteome-level study of this fungus. Extracted mycelial proteins and secreted proteins collected from liquid culture were separated using 2-DE and annotated following ESI-q-TOF MS/MS. Fifty-two secreted proteins were reproducibly present in three biological replicates and 18 of them were identified by MS/MS while over 200 mycelial proteins were reproducibly present in three independent extractions and approximately half of them were identified. Many of the annotated secreted proteins were cell wall degrading enzymes that had been previously identified as pathogenicity or virulence factors of S. sclerotiorum; however, the contribution to the virulence of S. sclerotiorum of one of the identified proteins, alpha-L-arabinofuranosidase, is yet to be analyzed. Furthermore, previous comprehensive EST studies did not detect the presence of the alpha-L-arabinofuranosidase transcript, which demonstrates the merit of performing proteome-level research. All of the secreted and mycelial proteins identified were functionally classified, and the known and proposed roles in disease initiation or progression for many of them are discussed.

The proteome of a salinity-tolerant Arachis hypogaea L. callus cell line was compared with its sensitive counterpart. Several low molecular weight proteins were detected by two-dimensional electrophoresis as being unique or significantly elevated in the tolerant line. The identities of several of these proteins were established as PR 10 proteins using tandem Mass Spectrometry and are shown to be phosphorylated on the basis of staining with the phosphorylation-specific stain, Pro-Q Diamond. Our results suggest that these differentially phosphorylated PR 10 proteins may play an important role in mediating salinity stress responses.