Population genetic structure of North Atlantic, Mediterranean Sea and Sea of Cortez fin whales, Balaenoptera physalus (Linnaeus 1758): analysis of mitochondrial and nuclear loci

Samples were collected from 407 fin whales, Balaenoptera physalus , at four North Atlantic and one Mediterranean Sea summer feeding area as well as the Sea of Cortez in the Pacific Ocean. For each sample, the sex, the sequence of the first 288 nucleotides of the mitochondrial (mt) control region and the genotype at six microsatellite loci were determined. A significant degree of divergence was detected at all nuclear and mt loci between North Atlantic/Mediterranean Sea and the Sea of Cortez. However, the divergence time estimated from the mt sequences was substantially lower than the time elapsed since the rise of the Panama Isthmus, suggesting occasional gene flow between the North Pacific and North Atlantic ocean after the separation of the two oceans. Within the North Atlantic and Mediterranean Sea, significant levels of heterogeneity were observed in the mtDNA between the Mediterranean Sea, the eastern (Spain) and the western (the Gulf of Maine and the Gulf of St Lawrence) North Atlantic. Samples collected off West Greenland and Iceland could not be unequivocally assigned to either of the two areas. The homogeneity tests performed using the nuclear data revealed significant levels of divergence only between the Mediterranean Sea and the Gulf of St Lawrence or West Greenland. In conclusion, our results suggest the existence of several recently diverged populations in the North Atlantic and Mediterranean Sea, possibly with some limited gene flow between adjacent populations, a population structure which is consistent with earlier population models proposed by Kellogg, Ingebrigtsen, and Sergeant.     

Effect of inoculum rate on mycorrhizal growth responses in pot-grown onion and clover

Summary White clover and onion plants were grown from seed in pots of sandy loam above pads of mycorrhizal inoculum soil at 0.17–1.40 g/pot (equivalent to 250–2000 kg/ha) and harvested on four occasions. In sterilized soil increasing inoculum rates increased the onset and size of the mycorrhizal growth response of white clover. In unsterilized soil the indigenous mycorrhizal fungi greatly stimulated growth of both clover and onion. Nevertheless, all mycorrhizal inoculum rates further stimulated shoot growth in onion (92% increase over all harvests), while only the highest inoculum rate significantly stimulated clover growth (52% increase).     

Uncoupling action of amytal in membrane vesicles from Escherichia coli.

The barbiturate amytal (5-ethyl-5-isopentylbarbituric acid) has been shown to inhibit amino acid transport in membrane vesicles from anaerobically grown Escherichia coli. Amytal has no effect on the activity of the enzymes of the nitrate respiration system, nor on electron transfer in this system. However, addition of amytal to the membrane vesicles results in a decrease of the membrane potential from -90 mV to -72 mV, and to a decrease of the pH-gradient of -61 mV to undetectable values. Furthermore, amytal causes an increase in the rate of ferricyanide reduction in liposomes, indicating that amytal increases the proton permeability of phospholipid membranes. These results demonstrate that amytal acts as an uncoupler in membrane vesicles from anaerobically grown E. coli.     

Genome informatics: taming the avalanche of genomic data

A report on the fourth Cold Spring Harbor Laboratory/Wellcome Trust Conference on Genome Informatics, Hinxton, UK, 22-26 September 2004.