A highly uniform UV transillumination imaging system for quantitative analysis of nucleic acids and proteins

The digital fluorescent imaging for documentation and analysis of gel electrophoretic separations of nucleic acids and proteins is widely used in quantitative biology. Most fluorescent stains used in postelectrophoretic analysis of proteins and nucleic acids have significant excitation peaks with UV light (300-365 nm), making midrange UV (UV-B) as the excitation source of choice. However, coupling quantitative CCD imaging with UV is difficult due to lack of uniformity found in typical UV transilluminators. The apparent amount of those macromolecules depends on the position of the gel band on the imaging surface of the transilluminator. Here, we report the development and validation of a highly uniform UV transillumination system. Using a novel high density lighting system containing a single lamp formed into a high density grid, an electronic ballast, a phosphor coating, and a bandpass filter to convert 254 nm light produced to 300-340 nm, uniformity of 80% CV observed in typical UV transilluminators. This system has been used for the quantitative analysis of electrophoretically separated nucleic acids and proteins (CV相似文献   

Evolutionary relationships among the permease proteins of the bacterial phosphoenolpyruvate: Sugar phosphotransferase system. Construction of phylogenetic trees and possible relatedness to proteins of eukaryotic mitochondria

Summary The amino acid sequences of 15 sugar permeases of the bacterial phosphoenolpyruvatedependent phosphotransferase system (PTS) were divided into four homologous segments, and these segments were analyzed to give phylogenetic trees. The permease segments fell into four clusters: the lactose-cellobiose cluster, the fructose-mannitol cluster, the glucose-N-acetylglucosamine cluster, and the sucrose--glucoside cluster. Sequences of the glucitol and mannose permeases (clusters 5 and 6, respectively) were too dissimilar to establish homology with the other permeases, but short regions of statistically significant sequence similarities were noted. The functional and structural relationships of these permease segments are discussed.Some of the homologous PTS permeases were found to exhibit sufficient sequence similarity to subunits 4 and 5 of the eukaryotic mitochondrial NADH dehydrogenase complex to suggest homology. Moreover, subunits 4 and 5 of this complex appeared to be homologous to each other, suggesting that these PTS and mitochondrial proteins comprise a superfamily. The integral membrane subunits of the evolutionarily divergent mannose PTS permease, the P and M subunits, exhibited limited sequence similarity to subunit 6 of the mitochondrial F₁F₀-ATPase and subunit 5b of cytochrome oxidase, respectively. These results suggest that PTS sugar permeases and mitochondrial proton-translocating proteins may be related, although the possibility of convergent evolution cannot be ruled out.     

A wide-range phylogenetic analysis of Zic proteins: implications for correlations between protein structure conservation and body plan complexity

We compared Zic homologues from a wide range of animals. Striking conservation was found in the zinc finger domains, in which an exon-intron boundary has been kept in all bilateralians but not cnidarians, suggesting that all of the bilateralian Zic genes are derived from a single gene in a bilateralian ancestor. There were additional conserved amino acid sequences, ZOC and ZF-NC. Combined analysis of the zinc finger, ZOC, and ZF-NC revealed the presence of two classes of Zic, based on the degree of protein structure conservation. The "conserved" class includes Zic proteins from the Arthropoda, Mollusca, Annelida, Echinodermata, and Chordata (vertebrates and cephalochordates), whereas the "diverged" class contains those from the Platyhelminthes, Cnidaria, Nematoda, and Chordata (urochordates). The result indicates that the ancestral bilateralian Zic protein had already acquired an entire set of conserved domains, but that this was lost and diverged in the platyhelminthes, nematodes, and urochordates.