Heavy metals in the lichen Ramalina duriaei transplanted in biomonitoring stations

The amounts of six heavy metals, Cu, Cr, Cd, Pb, Zn, and Ni in the transplanted fruticose lichen Ramalina duriaei, have been determined. The contents of these metals in the material exposed for 1 yr at the site which served as a source for the transplantation were found to be much lower than in the lichen transplanted close to busy roads and to places with other intensive human activities. Correlation coefficients between some pairs of the heavy metals found in the transplanted R. duriaei are closer to those previously found in Caloplaca aurantia from rural and suburban sites than to those from industrial sites in Tel-Aviv. All these heavy metals are expected in the emission from a coal-fired electric generating station to be located at the sea shore in the near future. We recommend that a program of monitoring for a power station at the proposed coastal site include routine determination of (a) the amounts of these metals in transplanted lichens, (b) the correlation between the amounts and the distance from the sea, and (c) the correlation between pairs of these metals at various locations.     

A 3-hydroxypropionate/4-hydroxybutyrate autotrophic carbon dioxide assimilation pathway in Archaea

The assimilation of carbon dioxide (CO2) into organic material is quantitatively the most important biosynthetic process. We discovered that an autotrophic member of the archaeal order Sulfolobales, Metallosphaera sedula, fixed CO2 with acetyl-coenzyme A (acetyl-CoA)/propionyl-CoA carboxylase as the key carboxylating enzyme. In this system, one acetyl-CoA and two bicarbonate molecules were reductively converted via 3-hydroxypropionate to succinyl-CoA. This intermediate was reduced to 4-hydroxybutyrate and converted into two acetyl-CoA molecules via 4-hydroxybutyryl-CoA dehydratase. The key genes of this pathway were found not only in Metallosphaera but also in Sulfolobus, Archaeoglobus, and Cenarchaeum species. Moreover, the Global Ocean Sampling database contains half as many 4-hydroxybutyryl-CoA dehydratase sequences as compared with those found for another key photosynthetic CO2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase-oxygenase. This indicates the importance of this enzyme in global carbon cycling.     

Discovery of very high energy gamma rays associated with an x-ray binary

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.     

Successful hybridization between Lolium and Dactylis

In order to test crossability of Lolium and Dactylis, a total of 4126 florets of six different varieties and ploidy levels of Lolium multiflorum Lam. and L. perenne L. were pollinated using a blend of pollen from two cultivars and three ecotypes of Dactylis glomerata L. Additionally, reciprocal pollinations were carried out on 363 florets of two D. glomerata cultivars with pollen of L. multiflorum. Both pre- and post-zygotic cross barriers were strong. Auxin application was effective in overcoming post-zygotic barriers. One viable hybrid plant arose from 16 embryos. The hybrid between L. multiflorum and D. glomerata showed characteristics of both parents. The symmetric character of the hybrid was confirmed by genomic in situ hybridization. Backcross pollinations with pollen of both parents yielded two plants from five embryos with L. multiflorum only. Both the production of allopolyploid hybrids having characters of both species and the transfer of useful characters of D. glomerata into L. multiflorum should be possible.