Impact of rainwater hydrogen peroxide on chlorophyll a content of surface Gulf Stream seawater off North Carolina, USA

Bioassays indicate addition of hydrogen peroxide in concentrations similar to rain sometimes decreases chlorophyll a (chl a) production in surface Gulf Stream seawater. Bioassays were conducted on shipboard in the spring and autumn of 1993, 1994, and 1995, using surface Gulf Stream seawater collected off the coast of North Carolina. Chl a increases were observed after addition of FeCl3(in 1 of 5 bioassays), iron (III) EDTA (6 of 6 bioassays), or EDTA alone (4 of 4 bioassays). The chl a increases were suppressed significantly in 7 of 1 1 of these bioassays when the bioassay seawater was initially diluted by 1% with a 30 or 40 μM solution of hydrogen peroxide (a concentration similar to rainwater). Hydrogen peroxide induced inhibition of chl a production was not observed in bioassays in which chl a increased in response to addition of nitrate or ammonium, hence the growth inhibition was associated with added metal or complexing agent. Rainwater therefore plays a complex role in primary productivity in surface seawater, with the specific effect dependent upon rainwater concentrations of nitrate, ammonium, trace metals and hydrogen peroxide, as well as on the extent of nitrogen limitation and the oxidant concentration in the surface seawater

Rainfall Stimulation of Primary Production in Western Atlantic Ocean Waters: Roles of Different Nitrogen Sources and Co-Limiting Nutrients

Using shipboard bioassays, we examined the roles rainfall, individual and combined nutrients play in accelerating primary production in coastal, Gulf Stream and pelagic (Sargasso Sea) locations in the North Atlantic Ocean off North Carolina, USA, from 1993 to 1995. Photosynthetic CO2 fixation and net chlorophyll a (chl a) production were measured In replicated bioassays to assess individual and combined impacts of different constituents of atmospheric deposition, including natural rainfall, a synthetic rain mix, dissolved inorganic nitrogen (DIN; NH4+ ,NO3-), dissolved organic nitrogen (DON; urea),phosphorus (PO43-) and iron (as EDTA-chelated and unchelated FeCl3).Natural rainfall and DIN additions most often stimulated CO2 fixation and chl a production, but frequencies and magnitudes of biostimulation, relative to controls, varied between these indicators. Spatial differences in the types and magnitudes of stimulation were also observed. When added in equimolar amounts, NH4+ was, at times, more stimulatory than NO3-. The NO3- stimulation was significantly enhanced by Fe-EDTA. Urea was marginally stimulatory at the coastal location. PO43- was never stimulatory. Fe-EDTA and EDTA by themselves stimulated production only at the offshore locations, suggesting increased Fe limitation with increasing distance from land. Synthetic rain, which contained both sources of DIN, but not Fe, generally proved less stimulatory per unit N than natural rainfall. Results indicate a broad sensitivity of these waters to N additions, which in the case of NO3- are enhanced by Fe-EDTA. At all locations, the high level of stimulation of primary production attributable to natural rain may be due to the supply of both DIN and CO-limiting nutrients (e.g. Fe), contributing to the eutrophication potential of waters downwind of urban, industrial and agricultural emissions

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Lung cancer in ever- and never-smokers: findings from multi-population GWAS studies.

BackgroundClinical, molecular, and genetic epidemiology studies displayed remarkable differences between ever- and never-smoking lung cancer.MethodsWe conducted a stratified multi-population (European, East Asian, and African descent) association study on 44,823 ever-smokers and 20,074 never-smokers to identify novel variants that were missed in the non-stratified analysis. Functional analysis including eQTL colocalization and DNA damage assays, and annotation studies were conducted to evaluate the functional roles of the variants. We further evaluated the impact of smoking quantity on lung cancer risk for the variants associated with ever-smoking lung cancer.ResultsFive novel independent loci, GABRA4, inter-genic region 12q24.33, LRRC4C, LINC01088, and LCNL1 were identified with the association at two or three populations (P 20). Different risk patterns were observed for the variants among the different groups by smoking behavior.ConclusionsWe identified novel variants associated with lung cancer in only ever- or never-smoking groups that were missed by prior main-effect association studies.ImpactOur study highlights the genetic heterogeneity between ever- and never-smoking lung cancer and provides etiological insights into the complicated genetic architecture of this deadly cancer