Comparative proteomic profiling represents an inhibition of protein synthesis to regulate osmotic stress in Nile tilapia (Oreochromis niloticus) embryos.

Seawater (SW)-acclimated Nile tilapia, Oreochromis niloticus, can tolerate up to 30 g.L-1 SW but rarely produce offspring. The embryos of SW-acclimated O. niloticus survived equally well from 0- to 10-g.L-1 environment but not under 20-g. L-1. However, when the embryos were incubated under 10 g.L-1 during days 0-3, and then the salinity was suddenly shifted to and maintained at 20 g.L-1 during days 4-6, their survival rate was comparable to those incubated under 0 and 10 g.L-1. To elucidate a molecular adaptation of the embryos that survived different salinity environments, the proteomic profiles of the newly hatched embryos, or early larvae, hatched under 0 g.L-1, 10 g.L-1, and those being incubated at 10 g.L-1 during days 0-3 followed at 20 g.L-1 during days 4-6 were compared. Total proteins extracted from the samples were identified with a gel-free shot-gun proteomics approach using the Nile tilapia protein database. The early larvae from the three groups expressed 2295 proteins, and 279 proteins showed statistically different expressions among groups. Downregulation of the 182 proteins in the larvae hatched under 10 and 20 g.L-1 was found to include 22 proteins that are responsible for cellular responses to osmotic stress. This adaptation may be a crucial factor in reducing cellular metabolism and ion transport between the intra- and extra-cellular environment to stabilize cellular osmolality. In addition, some of these proteins suppress cellular damage from oxygen free radicals generated from the osmotic stress. Eighty-seven proteins significantly changed in the larvae hatched under 20 g.L-1 were clustered. Nineteen of the cellular stress response proteins, which were considered to be mortality induction, were described.

Biomarker discovery in the biofilm-forming process of Burkholderia pseudomallei by mass-spectrometry.

A serious human infectious disease called Melioidosis is a result of Burkholderia pseudomallei infection. Treatment for infected individuals is difficult due to a wide range of ineffective antibiotics including a high level of antibiotic tolerance which has been known to be caused by biofilm production. However, biofilm forming processes of this bacterium are not well documented despite multiple-methodologies being applied. In this study, we utilized a proteomics strategy called whole cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (whole cell MALDI-TOF MS) to discover a potential biomarker relating biofilm forming in B. pseudomallei. The results presented a novel specific type of enzyme amylo-alpha-1, 6-glucosidase, which was demonstrated by a higher level of gene expression during the biofilm development. Our results also suggested a list of candidate markers that might be involved in this scenario. Eventually, this knowledge may expand valuable data to the biofilm study that may increase effective treatments for people infected with B. pseudomallei and possibly other antibiotic tolerant bacteria.