Cultivar and Rhizobium strain effect on nitrogen fixation and transport inPhaseolus vulgaris L.

The effects of Rhizobium strain and its interaction with plant cultivar were examined in glasshouse-grownPhaseolus vulgaris in two experiments where the physiological attributes defining the symbiotic efficiency were determined. Strains of Rhizobium significantly affected nodulation, rates of N accumulation, partitioning of N within the mature shoot and remobilizaton of the N stored in the vegetative organs to the seeds. The most efficient symbiosis (strain CO5 with Negro Argel), in comparison with the least efficient symbiosis (strain 127 K-17 with Venezuela-350) showed higher rates of C₂H₂ reduction from flowering to mid pod fill stage, evolved less hydrogen from nodules and showed higher rates of N transport as well as higher percentages of ureide-N in the xylem sap. At maturity, the best cultivar/strain association exceeded the total N accumulated in the seed and the harvest index of the poorest symbiosis in 88% and 20%, respectively. The other symbiotic combinations were intermediate in all characteristics. Nitrogen accumulation in plant shoot showed highly significant correlation with acetylene reduction rates, nodule relative efficiency, total N transport in the xylem sap and percentage of N transported as ureides.     

Recombinant Inbred Strain and Interspecific Backcross Analysis of Molecular Markers Flanking the Murine Agouti Coat Color Locus

Recombinant inbred strain and interspecific backcross mice were used to create a molecular genetic linkage map of the distal portion of mouse chromosome 2. The orientation and distance of the Ada, Emv-13, Emv-15, Hck-1, Il-1a, Pck-1, Psp, Src-1 and Svp-1 loci from the beta 2-microglobulin locus and the agouti locus were established. Our mapping results have provided the identification of molecular markers both proximal and distal to the agouti locus. The recombinants obtained provide valuable resources for determining the direction of chromosome walking experiments designed to clone sequences at the agouti locus. Comparisons between the mouse and human genome maps suggest that the human homolog of the agouti locus resides on human chromosome 20q. Three loci not present on mouse chromosome 2 were also identified and were provisionally named Psp-2, Hck-2 and Hck-3. The Psp-2 locus maps to mouse chromosome 14. The Hck-2 locus maps near the centromere of mouse chromosome 4 and may identify the Lyn locus. The Hck-3 locus maps near the distal end of mouse chromosome 4 and may identify the Lck locus.     

Metabolic coupling, cumulus expansion and meiotic resumption in mouse cumuli oophori cultured in vitro in the presence of FSH or dcAMP, or stimulated in vivo by hCG

The temporal changes of metabolic coupling between the mouse oocyte and the cumulus cells which follow hCG injection in vivo and FSH treatment in vitro were studied by measuring what fraction of [3H]uridine taken up by cumulus cells was transferred to the oocyte. Meiotic resumption and a partial coupling loss (to 35% of the initial value) spontaneously occurred in cumuli cultured in control medium. The addition of 1 microgram FSH/ml in vitro, or the injection of hCG in vivo caused a delay of about 3 h in both phenomena and a near total uncoupling, together with cumulus expansion. FSH caused uncoupling even if cumulus expansion was prevented by the addition of heparin. The presence of 2 mM-dcAMP prevented meiotic resumption in cumulus-enclosed oocytes and maintained a high level of co-operation for at least 6 h. The slow uncoupling observed at later times was due to cumulus expansion, because it was totally prevented by heparin. We suggest that metabolic co-operation with the cumulus oophorus and meiotic resumption are both regulated by FSH through variations of intracellular levels of cAMP.     

Of mice and Marfan: genetic linkage analyses of the fibrillin genes,Fbn1 and Fbn2, in the mouse genome

The fibrillin genes, FBN1 and FBN2, encode large extracellular matrix glycoproteins involved in the structure and function of microfibrils. Mutations in FBN1 are found in patients with Marfan syndrome, a heritable connective tissue disease that primarily affects the cardiovascular, ocular, and skeletal systems. We extended the studies of these genes by determining their chromosomal position in the mouse genome. Restriction fragment length polymorphisms (RFLPs) between the progenitors of an interspecific backcross involving AEJ/Gn and Mus spretus mice were used to establish the segregation patterns of the murine homologs, Fbn1 and Fbn2, in the backcross progeny. The results position Fbn1 between the B2m and Illa genes on mouse Chromosome (Chr) 2 and establish its candidacy for the Tight skin (Tsk) mutation. The results position Fbn2 between the D18Mit35 and Pdgfrb loci in the central region of mouse Chr 18. Fbn2 maps near three mutations [bouncy (bc), plucked (pk), and shaker with syndactyly (sy)] and may be a candidate for the pk mutation.     

Molecular Genetic Characterization of Six Recessive Viable Alleles of the Mouse Agouti Locus

The agouti locus on mouse chromosome 2 encodes a secreted cysteine-rich protein of 131 amino acids that acts as a molecular switch to instruct the melanocyte to make either yellow pigment (phaeomelanin) or black pigment (eumelanin). Mutations that up-regulate agouti expression are dominant to those causing decreased expression and result in yellow coat color. Other associated effects are obesity, diabetes, and increased susceptibility to tumors. To try to define important functional domains of the agouti protein, we have analyzed the molecular defects present in a series of recessive viable agouti mutations. In total, six alleles (a(mJ), a(u), a(da), a(16H), a(18H), a(e)) were examined at both the RNA and DNA level. Two of the alleles, a(16H) and a(e), result from mutations in the agouti coding region. Four alleles (a(mJ), a(u), a(18H), and a(da)) appear to represent regulatory mutations that down-regulate agouti expression. Interestingly, one of these mutations, a(18H), also appears to cause an immunological defect in the homozygous condition. This immunological defect is somewhat analogous to that observed in motheaten (me) mutant mice. Short and long-range restriction enzyme analyses of homozygous a(18H) DNA are consistent with the hypothesis that a(18H) results from a paracentric inversion where one end of the inversion maps in the 5' regulatory region of agouti and the other end in or near a gene that is required for normal immunological function. Cloning the breakpoints of this putative inversion should allow us to identify the gene that confers this interesting immunological disorder.     

Genome Sequences of Burkholderia sp. Strains CCGE1002 and H160, Isolated from Legume Nodules in Mexico and Brazil

The genome sequences of Burkholderia sp. strains CCGE1002 from Mexico and H160 from Brazil, isolated from legume nodules, are reported. Their gene contents in relation to plant-microbe interactions and xenobiotic degradation are discussed.     

New Tricks for Old Guys: Recent Developments in the Chemistry,Biochemistry, Applications and Exploitation of Selected Species from the Lamiaceae Family

Lamiaceae is one of the largest families of flowering plants comprising about 250 genera and over 7,000 species. Most of the plants of this family are aromatic and therefore important source of essential oils. Lamiaceae are widely used as culinary herbs and reported as medicinal plants in several folk traditions. In the Mediterranean area oregano, sage, rosemary, thyme and lavender stand out for geographical diffusion and variety of uses. The aim of this review is to provide recent data dealing with the phytochemical and pharmacological studies, and the more recent applications of the essential oils and the non‐volatile phytocomplexes. This literature survey suggests how the deeper understanding of biomolecular processes in the health and food sectors as per as pest control bioremediation of cultural heritage, or interaction with human microbiome, fields, leads to the rediscovery and new potential applications of well‐known plants.     

Mitonuclear Coevolution,but not Nuclear Compensation,Drives Evolution of OXPHOS Complexes in Bivalves

In Metazoa, four out of five complexes involved in oxidative phosphorylation (OXPHOS) are formed by subunits encoded by both the mitochondrial (mtDNA) and nuclear (nuDNA) genomes, leading to the expectation of mitonuclear coevolution. Previous studies have supported coadaptation of mitochondria-encoded (mtOXPHOS) and nuclear-encoded OXPHOS (nuOXPHOS) subunits, often specifically interpreted with regard to the “nuclear compensation hypothesis,” a specific form of mitonuclear coevolution where nuclear genes compensate for deleterious mitochondrial mutations due to less efficient mitochondrial selection. In this study, we analyzed patterns of sequence evolution of 79 OXPHOS subunits in 31 bivalve species, a taxon showing extraordinary mtDNA variability and including species with “doubly uniparental” mtDNA inheritance. Our data showed strong and clear signals of mitonuclear coevolution. NuOXPHOS subunits had concordant topologies with mtOXPHOS subunits, contrary to previous phylogenies based on nuclear genes lacking mt interactions. Evolutionary rates between mt and nuOXPHOS subunits were also highly correlated compared with non-OXPHO-interacting nuclear genes. Nuclear subunits of chimeric OXPHOS complexes (I, III, IV, and V) also had higher dN/dS ratios than Complex II, which is formed exclusively by nuDNA-encoded subunits. However, we did not find evidence of nuclear compensation: mitochondria-encoded subunits showed similar dN/dS ratios compared with nuclear-encoded subunits, contrary to most previously studied bilaterian animals. Moreover, no site-specific signals of compensatory positive selection were detected in nuOXPHOS genes. Our analyses extend the evidence for mitonuclear coevolution to a new taxonomic group, but we propose a reconsideration of the nuclear compensation hypothesis.     

Changes of nitric oxide,carbon monoxide and oxidative stress in term infants at birth

The higher risk of respiratory problem in infants delivered by elective caesarean section in comparison with vaginally born infants may be favoured by lower level of nitric oxide (NO) and carbon monoxide (CO) and higher oxidative stress in infants born by caesarean section. We studied healthy term infants born by vaginal delivery or by elective caesarean section. Nitric oxide, CO, guanosine 3–5 cyclic monophosphate, total hydroperoxide and advanced oxidation protein products (AOPP) were measured at birth and 48–72 h of life. Nitric oxide, CO and cGMP were lower at birth and at 48–72 h of life in infants born by elective caesarean delivery. Total hydroperoxide and AOPP levels were similar in the two groups and increased from birth to 48–72 h of life. In conclusion, nitric oxide and CO concentrations were higher in term infants vaginally born than in infants born by elective caesarean section and decreased from birth to 48–72 h of life. The mode of delivery did not affect the oxidative stress which increases from birth to 48–72 h of life.