Plant respiration proportional to N content

In a report published in the Jan. 26 issue of the journal Nature, biologist Peter Reich of the University of Minnesota and his colleagues found that the rate of plant metabolism, or respiration--and its related emissions of carbon dioxide--can be deduced from the nitrogen content of any plant.
Plants carry out respiration during the dark hours when they, like animals, take in oxygen and give off carbon dioxide. During daylight, plants carry out photosynthesis, in which the process is reversed.
Researchers have estimated that plant respiration releases five to 10 times as much carbon dioxide as fossil fuel burning. It's crucial, they say, to know the amount of plant emissions more accurately. Yet, "the amount of carbon dioxide given off by plants is one of the weak spots in models of global carbon cycling," Reich said.

Understanding The Ocean's Microbes Is Key To The Earth's Future

Understanding The Oceans Microbes Is Key To The Earth's Future: "Early marine microorganisms also helped create the conditions under which subsequent life developed. More than two billion years ago, the generation of oxygen by photosynthetic marine microorganisms helped shape the chemical environment in which plants, animals, and all other life forms have evolved."

ScienceWeek

ScienceWeek: "Plastids (chloroplasts) are endosymbiotic organelles derived from previously free-living Cyanobacteria. They are dependent on their host cell to the degree that the majority of the proteins expressed in the plastid are encoded in the nuclear genome of the host cell, and it is this genetic dependency that distinguishes organelles from obligate endosymbionts. Reduction in the size of the plastid genome has occurred via gene loss, substitution of nuclear genes, and gene transfer.

The plastids of Chlorophyta and plants, Rhodophyta, and Glaucocystophyta are primary plastids (i.e., derived directly from a Cyanobacterium). These three lineages may or may not be descended from a single endosymbiotic event. All other lineages of plastids have acquired their plastids by secondary (or tertiary) endosymbiosis, in which a eukaryote already equipped with plastids is preyed upon by a second eukaryote. Considerable gene transfer has occurred among genomes and, at times, between organisms. The eukaryotic crown group Alveolata has a particularly complex history of plastid acquisition. [diagram]
C.F. Delwiche: Am Nat 1999 154:S164."