Biosynthesis and use of coproporphyrins and uroporphyrins and their metal complexes in immune analysis and diagnostic methods]

Methods of synthesis of coproporphyrin and uroporphyrin by using bacteria of the genus Arthrobacter are proposed. Metal complexes of coproporphyrin and uroporphyrin with Pt, Pd, and Zn were synthesized. Their structures were identified by spectrophotometry, IR spectrometry, 1H-NMR, mass spectrometry, and HPLC. Data showing the possibility to use coproporphyrin III-metal complexes as luminophores for fluorescence detection of tumors. The current and prospective uses of metal complexes of water-soluble natural porphyrins in advanced immunofluorescence assays are discussed.     

Selective constraint in intergenic regions of human and mouse genomes.

We aligned and analyzed 100 pairs of complete, orthologous intergenic regions from the human and mouse genomes (average length approximately 12 000 nucleotides). The alignments alternate between highly similar segments and dissimilar segments, indicating a wide variation of selective constraint. The average number of selectively constrained nucleotides within a mammalian intergenic region is at least 2000. This is threefold higher than within a nematode intergenic region and at least twofold higher than the number of selectively constrained nucleotides coding for an average protein. Because mammals possess only two- to threefold more proteins than Caenorhabditis elegans, the higher complexity of mammals might be primarily because of the functioning of intergenic DNA.     

1-X-3 motif in inter-protein recognition: structures, widespreading and possible practical application.

Similarities in the discrete mode and size of contact areas of a wide range of protein complexes allows us to suggest the existence of a limited number of types of inter-protein interactions. Comparison of structures of bound determinants indicates that the double-module, 1-X-3 type of motif is widespread in recognition processes. Thus, in many cases, the sites of ligand recognition are formed by two significant amino acids and separated by insignificant ones. Typical examples of such motifs are the RGD sequence of some adhesive and haemostatic proteins, the primary sites for plasminogen sorption on the fibrin network, the reactive sites of protein inhibitors of serine proteinases, and the sites for activation of the hydrolysis of protein pro-forms and receptors. It is assumed that there is widespread double-module determinants in many inter-protein interactions.     

Visual cues during the alarm reaction of Gymnocharacinus bergi (Pisces, Characidae)

Gymnocharacinus bergi (Pisces, Characidae), an endemic fish in the headwaters of the Valcheta stream in northern Patagonia, displays a fright reaction. As this species inhabits a rapid stream, we hypothesized that the alarm reaction might be socially transmitted through visual information, because the detection of alarm pheromone would be restricted to those fish located downstream from the releaser. Alarm substances elicited a decrease in the swimming activity and a tendency to remain at the bottom of the aquarium. Individuals that observed the fright reaction, but were not exposed to the pheromone, spent significantly more time at the bottom of the aquarium imitating the alarm response, and tended to approach the others. Gregarious behaviour was observed; however, interactions (number of approaches) were stronger between those fish held prior to testing in the same aquarium; smaller fish in particular tended to get closer to bigger ones. Greater group cohesion was found between individuals that were exposed to the alarm pheromone.     

GISHGenomic in situ hybridization reveals cryptic genetic differences between maize and its putative wild progenitor Zea mays subsp. parviglumis.

The aim of this paper is to test with genomic in situ hybridization the genomic affinities between maize and its putative progenitor Zea mays subsp. parviglumis. Blocking procedures were applied for the purpose of improving discrimination among chromosome regions. Unlabeled genomic DNA from Z. mays subsp. parviglumis as a blocking agent and labeled genomic DNA from maize were hybridized on maize chromosomes. On the other hand, mitotic metaphases from Z. mays subsp. parviglumis were blocked with unlabeled genomic DNA of maize and hybridized with labeled genomic DNA from Z. mays subsp. parviglumis. Both experiments showed that either maize or Z. mays subsp. parviglumis chromosomes have their own unique sequences. This means an unexpected degree of divergence if Z. mays subsp. parviglumis is the only progenitor of maize, a result that is discussed in relation to our previous genomic in situ hybridization observations and to the different scenarios proposed about the origin of maize.     

The promoters of Arabidopsis thaliana genes AtCOX17-1 and -2, encoding a copper chaperone involved in cytochrome c oxidase biogenesis, are preferentially active in roots and anthers and induced by biotic and abiotic stress

AtCOX17 genes encode Arabidopsis thaliana homologs of the yeast metallochaperone Cox17p, involved in the delivery of copper for cytochrome c oxidase (COX) assembly. Two different AtCOX17 genes, located in chromosomes 1 and 3, are present in the Arabidopsis genome. Sequences available in data banks indicate that the presence of two genes is a common feature in monocots, but not in dicots, suggesting that Arabidopsis genes may be the result of a recent duplication. Sequences upstream from the translation start sites of AtCOX17 genes, which include an intron located in the 5' leader region, were introduced into plants in front of the gus gene. For both genes, expression was localized preferentially in young roots and anthers, but almost 10-fold higher β-glucuronidase activity levels were observed in plants transformed with AtCOX17-1 upstream regions. Both promoters were induced to different extents by wounding, treatment of leaves with the bacterial pathogen Pseudomonas syringae and incubation with agents that produce oxidative stress and metals. AtCOX17-2 showed similar responses to these factors, while AtCOX17-1 was more strongly induced by relatively low (10–100 μ M ) copper. The results indicate that both AtCOX17 genes have similar, though not identical, expression characteristics and suggest the existence in their promoters of elements involved in tissue-specific expression and in responses to factors that may produce mitochondrial or cell damage. It can be speculated that Arabidopsis COX17 accumulates under stress conditions to actively replace damaged or inactive cytochrome c oxidase to sustain cyanide-sensitive respiration in plant cells.