Global biodiversity and the ancient carbon cycle

Paleontological data for the diversity of marine animals and land plants are shown to correlate significantly with a concurrent measure of stable carbon isotope fractionation for approximately the last 400 million years. The correlations can be deduced from the assumption that increasing plant diversity led to increasing chemical weathering of rocks and therefore an increasing flux of carbon from the atmosphere to rocks, and nutrients from the continents to the oceans. The CO2 concentration dependence of photosynthetic carbon isotope fractionation then indicates that the diversification of land plants led to decreasing CO2 levels, while the diversification of marine animals derived from increasing nutrient availability. Under the explicit assumption that global biodiversity grows with global biomass, the conservation of carbon shows that the long-term fluctuations of CO2 levels were dominated by complementary changes in the biological and fluid reservoirs of carbon, while the much larger geological reservoir remained relatively constant in size. As a consequence, the paleontological record of biodiversity provides an indirect estimate of the fluctuations of ancient CO2 levels.

Fish and mammals in the economy of an ancient Peruvian kingdom

Fish and mammal bones from the coastal site of Cerro Azul, Peru shed light on economic specialization just before the Inca conquest of A.D. 1470. The site devoted itself to procuring anchovies and sardines in quantity for shipment to agricultural communities. These small fish were dried, stored, and eventually transported inland via caravans of pack llamas. Cerro Azul itself did not raise llamas but obtained charqui (or dried meat) as well as occasional whole adult animals from the caravans. Guinea pigs were locally raised. Some 20 species of larger fish were caught by using nets; the more prestigious varieties of these show up mainly in residential compounds occupied by elite families.

Isoprenoid biosynthesis: The evolution of two ancient and distinct pathways across genomes

Isopentenyl diphosphate (IPP) is the central intermediate in the biosynthesis of isoprenoids, the most ancient and diverse class of natural products. Two distinct routes of IPP biosynthesis occur in nature: the mevalonate pathway and the recently discovered deoxyxylulose 5-phosphate (DXP) pathway. The evolutionary history of the enzymes involved in both routes and the phylogenetic distribution of their genes across genomes suggest that the mevalonate pathway is germane to archaebacteria, that the DXP pathway is germane to eubacteria, and that eukaryotes have inherited their genes for IPP biosynthesis from prokaryotes. The occurrence of genes specific to the DXP pathway is restricted to plastid-bearing eukaryotes, indicating that these genes were acquired from the cyanobacterial ancestor of plastids. However, the individual phylogenies of these genes, with only one exception, do not provide evidence for a specific affinity between the plant genes and their cyanobacterial homologues. The results suggest that lateral gene transfer between eubacteria subsequent to the origin of plastids has played a major role in the evolution of this pathway.

Isolation and molecular characterization of a human T-cell lymphotropic virus type II (HTLV-II), subtype B, from a healthy Pygmy living in a remote area of Cameroon: an ancient origin for HTLV-II in Africa.

We report characterization of a human T-cell lymphotropic virus type II (HTLV-II) isolated from an interleukin 2-dependent CD8 T-cell line derived from peripheral blood mononuclear cells of a healthy, HTLV-II-seropositive female Bakola Pygmy, aged 59, living in a remote equatorial forest area in south Cameroon. This HTLLV-II isolate, designated PYGCAM-1, reacted in an indirect immunofluorescence assay with HTLV-II and HTLV-I polyclonal antibodies and with an HTLV-I/II gp46 monoclonal antibody but not with HTLV-I gag p19 or p24 monoclonal antibodies. The cell line produced HTLV-I/II p24 core antigen and retroviral particles. The entire env gene (1462 bp) and most of the long terminal repeat (715 bp) of the PYGCAM-1 provirus were amplified by the polymerase chain reaction using HTLV-II-specific primers. Comparison with the long terminal repeat and envelope sequences of prototype HTLV-II strains indicated that PYGCAM-1 belongs to the subtype B group, as it has only 0.5-2% nucleotide divergence from HTLV-II B strains. The finding of antibodies to HTLV-II in sera taken from the father of the woman in 1984 and from three unrelated members of the same population strongly suggests that PYGCAM-1 is a genuine HTLV-II that has been present in this isolated population for a long time. The low genetic divergence of this African isolate from American isolates raises questions about the genetic variability over time and the origin and dissemination of HTLV-II, hitherto considered to be predominantly a New World virus.