The influence of iron on the proteomic profile of Chromobacterium violaceum.

BACKGROUND: Chromobacterium violaceum is a bacterium commonly found in tropical and subtropical regions and is associated with important pharmacological and industrial attributes such as producing substances with therapeutic properties and synthesizing biodegradable polymers. Its genome was sequenced, however, approximately 40% of its genes still remain with unknown functions. Although C. violaceum is known by its versatile capacity of living in a wide range of environments, little is known on how it achieves such success. Here, we investigated the proteomic profile of C. violaceum cultivated in the absence and presence of high iron concentration, describing some proteins of unknown function that might play an important role in iron homeostasis, amongst others. RESULTS: Briefly, C. violaceum was cultivated in the absence and in the presence of 9 mM of iron during four hours. Total proteins were identified by LC-MS and through the PatternLab pipeline. Our proteomic analysis indicates major changes in the energetic metabolism, and alterations in the synthesis of key transport and stress proteins. In addition, it may suggest the presence of a yet unidentified operon that could be related to oxidative stress, together with a set of other proteins with unknown function. The protein-protein interaction network also pinpointed the importance of energetic metabolism proteins to the acclimatation of C. violaceum in high concentration of iron. CONCLUSIONS: This is the first proteomic analysis of the opportunistic pathogen C. violaceum in the presence of high iron concentration. Our data allowed us to identify a yet undescribed operon that might have a role in oxidative stress defense. Our work provides new data that will contribute to understand how this bacterium achieve its capacity of surviving in harsh conditions as well as to open a way to explore the yet little availed biotechnological characteristics of this bacterium with the further exploring of the proteins of unknown function that we showed to be up-regulated in high iron concentration.

Chromosomal characterization of cryopreserved mesenchymal stem cells from the human subendothelium umbilical cord vein.

AIMS: To conduct a morphological, functional and chromosomal characterization of mesenchymal stem cell populations from the human subendothelium umbilical cord vein after cryopreservation. MATERIAL & METHODS: Five human umbilical cords were processed in order to obtain mesenchymal stem cells. Flow cytometry, differentiation assays and cytogenetic analysis were carried out before and after the cryopreservation process. RESULTS: Flow cytometry revealed that CD105, CD73 and CD90 markers were expressed by the cells, which lacked the expression of hematopoietic lineage markers, such as CD14, CD34 and CD45. The mesenchymal stem cells demonstrated capacity for osteogenic, adipogenic and chondrogenic differentiation. Chromosome analysis showed no clonal chromosome changes in the cells in either situation. However, a significant number of nonclonal chromosomal aberrations were apparent after cryopreservation, including monosomies and structural changes. Cells isolated from one umbilical cord exhibited a rare balanced paracentric inversion, likely a cytogenetic constitutional alteration. This was present both before and after experimental procedures. CONCLUSION: These findings show that using mesenchymal stem cells for clinical approaches requires careful investigation and sensitive tests in order to ensure cellular therapy biosafety.