<Emphasis Type="Italic">HMG1A</Emphasis> and <Emphasis Type="Italic">PPARG</Emphasis> are differently expressed in the liver of fat and lean broilers

The expression of nine functional candidates for QT abdominal fat weight and relative abdominal fat content was investigated by real-time polymerase chain reaction (PCR) in the liver, adipose tissue, colon, muscle, pituitary gland and brain of broilers. The high mobility group AT-hook 1 (HMG1A) gene was up-regulated in liver with a ratio of means of 2.90 (P?≤?0.01) in the «fatty» group (relative abdominal fat content 3.5?±?0.18%, abdominal fat weight 35.4?±?6.09 g) relative to the «lean» group (relative abdominal fat content 1.9?±?0.56%, abdominal fat weight 19.2?±?5.06 g). Expression of this gene was highly correlated with the relative abdominal fat content (0.70, P?≤?0.01) and abdominal fat weight (0.70, P?≤?0.01). The peroxisome proliferator-activated receptor gamma (PPARG) gene was also up-regulated in the liver with a ratio of means of 3.34 (P?≤?0.01) in the «fatty» group relative to the «lean» group. Correlation of its expression was significant with both the relative abdominal fat content (0.55, P?≤?0.05) and the abdominal fat weight (0.57, P?≤?0.01). These data suggest that the HMG1A and PPARG genes were candidate genes for abdominal fat deposition in chickens. Searching of rSNPs in regulatory regions of the HMG1A and PPARG genes could provide a tool for gene-assisted selection.     

Evolution of respiratory complex I: "supernumerary" subunits are present in the alpha-proteobacterial enzyme

Modern α-proteobacteria are thought to be closely related to the ancient symbiont of eukaryotes, an ancestor of mitochondria. Respiratory complex I from α-proteobacteria and mitochondria is well conserved at the level of the 14 "core" subunits, consistent with that notion. Mitochondrial complex I contains the core subunits, present in all species, and up to 31 "supernumerary" subunits, generally thought to have originated only within eukaryotic lineages. However, the full protein composition of an α-proteobacterial complex I has not been established previously. Here, we report the first purification and characterization of complex I from the α-proteobacterium Paracoccus denitrificans. Single particle electron microscopy shows that the complex has a well defined L-shape. Unexpectedly, in addition to the 14 core subunits, the enzyme also contains homologues of three supernumerary mitochondrial subunits as follows: B17.2, AQDQ/18, and 13 kDa (bovine nomenclature). This finding suggests that evolution of complex I via addition of supernumerary or "accessory" subunits started before the original endosymbiotic event that led to the creation of the eukaryotic cell. It also provides further confirmation that α-proteobacteria are the closest extant relatives of mitochondria.     

Structure of Escherichia coli OmpF porin from lipidic mesophase

Outer membrane protein F, a major component of the Escherichia coli outer membrane, was crystallized for the first time in lipidic mesophase of monoolein in novel space groups, P1 and H32. Due to ease of its purification and crystallization OmpF can be used as a benchmark protein for establishing membrane protein crystallization in meso, as a "membrane lyzozyme". The packing of porin trimers in the crystals of space group H32 is similar to natural outer membranes, providing the first high-resolution insight into the close to native packing of OmpF. Surprisingly, interaction between trimers is mediated exclusively by lipids, without direct protein-protein contacts. Multiple ordered lipids are observed and many of them occupy identical positions independently of the space group, identifying preferential interaction sites of lipid acyl chains. Presence of ordered aliphatic chains close to a positively charged area on the porin surface suggests a position for a lipopolysaccharide binding site on the surface of the major E. coli porins.     

Comparative compositional mapping of chicken and quail chromosomes

The distribution of various isochore families on mitotic chromosomes of domestic chicken and Japanese quail was studied by the method of fluorescence in situ DNA--DNA hybridization (FISH). DNA of various isochore families was shown to be distributed irregularly and similarly on chromosomes of domestic chicken and Japanese quail. The GC-rich isochore families (H2, H3, and H4) hybridized mainly to microchromosomes and a majority of macrochromosome telomeric regions. In chicken, an intense fluorescence was also in a structural heterochromatin region of the Z chromosome long arm. In some regions of the quail macrochromosome arms, hybridization was also with isochore families H3 and H4. On macrochromosomes of both species, the pattern of hybridization with isochores of the H2 and H3 families resembled R-banding. The light isochores (L1 and L2 families) are mostly detected within macrochromosome internal regions corresponding to G bands, whereas microchromosomes lack light isochores. Although mammalian and avian karyotypes differ significantly in organization, the isochore distribution in genomes of these two lineages of the warm-blooded animals is similar in principle. On macrochromosomes of the two avian species studied, a pattern of isochore distribution resembled that of mammalian chromosomes. The main specific feature of the avian genome, a great number of microchromosomes (about 30% of the genome), determines a compositional specialization of the latter. This suggests the existence of not only structural but also functional compartmentalization of the avian genome.     

Libraries of large-insert genomic clones as a tool for molecular cytogenetic analysis of avian genome

Integration of molecular and cytegenetic levels of investigation results in complex understanding of structural and functional genome organization. Gridded libraries of large-insert genomic clones represent a powerful tool of the genome analysis. Their utilization provides coordination of data on molecular organization of nucleic acids with cytogenetic data on the chromosome structure. These libraries played an important role in sequencing of genomes of human, mouse, and other organisms as an instrument linking molecular biological and cytogenetic data via construction of contigs and their localization on the chromosomes. They also enabled analysis of orthology between the mammalian genomes. The existing avian libraries fit molecular cytogenetic analysis of the class Aves genome, and can be successfully used for the isolation and characterization of large genomic fragments. This provides utilization of these libraries not only for the chromosome mapping, but also for positional cloning and search for candidate genes for quantitative traits.     

Cryo-electron crystallography of two sub-complexes of bovine complex I reveals the relationship between the membrane and peripheral arms

NADH:ubiquinone oxidoreductase (complex I) is the first and largest enzyme of the mitochondrial respiratory chain. The low-resolution structure of the complex is known from electron microscopy studies. The general shape of the complex is in the form of an L, with one arm in the membrane and the other peripheral. We have purified complex I from beef heart mitochondria and reconstituted the enzyme into lipid bilayers. Under different conditions, several two-dimensional crystal forms were obtained. Crystals belonging to space groups p222(1) and c12 (unit cell 488 Ax79 A) were obtained at 22 degrees C and contained only the membrane fragment of complex I similar to hydrophobic subcomplex Ibeta but lacking the ND5 subunit. A crystal form with larger unit cell (534 Ax81 A, space group c12) produced at 4 degrees C contained both the peripheral and membrane arms of the enzyme, except that ND5 was missing. Projection maps from frozen hydrated samples were calculated for all crystal forms. By comparing two different c12 crystal forms, extra electron density in the projection map of large crystal form was assigned to the peripheral arm of the enzyme. One of the features of the map is a deep, channel-like, cleft next to peripheral arm. Comparison with available structures of the intact enzyme indicates that large hydrophobic subunit ND5 is situated at the distal end of the membrane domain. Possible locations of subunit ND4 and of other subunits in the membrane domain are proposed. Implications of our findings for the mechanism of proton pumping by complex I are discussed.     

Effect of the long-term exposure of the isolated myometrium from nonpregnant rats to serum from pregnant women on its contractile activity and the beta-adrenergic reactivity

Pregnant women's blood serum (the whole as well as 50- and 100-diluted) did not alter parameters of spontaneous motility, i.e. it did not affect the uterus myocytes' spontaneous motility, whereas the whole or 50-diluted serum raised considerable the rat myometrium's beta-adrenoreaction. The data obtained suggest that the beta-adrenoreaction of the rat uterus' myocytes increases after a prolonged contact with pregnant women's blood serum which may be due to the beta-adrenoreceptor synthesis activation and to an increase in their concentration because of diffusion from the blood serum. This suggests existence of humoral mechanisms of the myometrium beta-adrenoreaction regulation, the mechanisms creating the optimum uterus' contractile activity.     

Identification of a novel subunit of respiratory complex I from Thermus thermophilus

The hydrophilic domain (peripheral arm) of the proton-translocating NADH:quinone oxidoreductase (complex I) from the thermophilic organism Thermus thermophilus HB8 has been purified and characterized. The subcomplex is stable in sodium dodecyl sulfate up to 80 degrees C. Of nine iron-sulfur clusters, four to five (one or two binuclear and three tetranuclear) could be detected by EPR in the NADH-reduced enzyme. The preparation consists of eight different polypeptides. Seven of them have been positively identified by peptide mass mapping and N-terminal sequencing as known hydrophilic subunits of T. thermophilus complex I. The eighth polypeptide copurified with the subcomplex at all stages, is strongly associated with the other subunits, and is present in crystals of the subcomplex, used for X-ray data collection. Therefore, it has been identified as a novel complex I subunit and named Nqo15. It is encoded in a locus separate from the nqo operon, containing the 14 other known complex I genes. ORFs encoding Nqo15 homologues are present in the genomes of the closest relatives of T. thermophilus. Our data show that, contrary to previous assumptions, bacterial complex I can contain proteins in addition to a "core" complement of 14 subunits.