MARTIJANEC-GAMULICA - ANALYSIS OF FINDS FROM 1950

Godine 1950. na tada još neistraženom tumulu Gamulica kod Martijanca ukopan je stup dalekovoda. Tom je prilikom mještanin Martijanca, Martin Štanglin, u tumulu prokopao jamu te otkrio tragove grobne konstrukcije i priloga. Lokalitet je nakon toga obišao prof. Stjepan Vuković, tadašnji kustos Odjela za arheologiju Gradskog muzeja Varaždin, te je pokretne nalaze prikupio, a iskop sanirao. Istraživanje pod vodstvom dr. sc. Zdenka Vinskog kao i detaljna analiza tada prikupljenih arheoloških nalaza, potvrdili su izniman značaj lokaliteta Martijanec-Gamulica, međutim, tom prilikom nisu uzeti u obzir i predmeti koje je 1950. god. prikupio S. Vuković. Dvadeset i sedam keramičkih te jedan brončani predmet čine malu, ali vrijednu skupinu nalaza čija će analiza i konačna objava zaokružiti spoznaje o ukopu u tumulu Gamulica te pridonijeti boljem poznavanju stariježeljeznodobne grupe Martijanec-Kaptol.In 1950, on the then unexcavated tumulus of Gamulica near Martijanec, a transmission line pole was set up. On that occasion Martin Štanglin, a resident of Matrijanec, found a pit in the tumulus which contained traces of a tomb with grave goods. The site was then visited by professor Stjepan Vuković who worked as a curator at the Department of Archaeology of the Varaždin City Museum and who collected movable finds and protected the tomb. Research led by Zdenko Vinski, PhD, as well as a detailed analysis of the finds, confirmed the exceptional status of the Martijanec-Gamulica site. However, the study did not include finds collected in 1950 by S. Vuković. Twenty seven ceramic and one bronze find make up a small but valuable group of finds the analysis of which will unite our knowledge of the tomb inside the Gamulica tumulus and contribute to our understanding of the Iron Age Martijanec-Kaptol group

A re-evaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean

We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition, and compare this to fluvial inputs and di-nitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate about 75% of this fluvial nitrogen escapes from the shelf to the open ocean. Biological di-nitrogen fixation is the main external source of nitrogen to the open ocean, i.e. beyond the continental shelf. Atmospheric deposition is the primary mechanism by which land based nitrogen inputs, and hence human perturbations of the nitrogen cycle, reach the open ocean. We estimate that anthropogenic inputs are currently leading to an increase in overall ocean carbon sequestration of ~0.4% (equivalent to an uptake of 0.15 Pg C yr-1 and less than the Duce et al., 2008 estimate). The resulting reduction in climate change forcing from this ocean CO2 uptake is offset to a small extent by an increase in ocean N2O emissions. We identify four important feedbacks in the ocean atmosphere nitrogen system that need to be better quantified to improve our understanding of the perturbation of ocean biogeochemistry by atmospheric nitrogen inputs. These feedbacks are recycling of (1) ammonia and (2) organic nitrogen from the ocean to the atmosphere and back, (3) the suppression of nitrogen fixation by increased nitrogen concentrations in surface waters from atmospheric deposition, and (4) increased loss of nitrogen from the ocean by denitrification due to increased productivity stimulated by atmospheric inputs

Widespread Distribution and Expression of Gamma A (UMB), an Uncultured, Diazotrophic, γ-Proteobacterial nifH Phylotype

Marine dinitrogen (N2) fixation studies have focused nearly exclusively on cyanobacterial diazotrophs; however γ-proteobacteria are an abundant component of the marine community and have been largely overlooked until recently. Here we present a phylogenetic analysis of all nifH γ-proteobacterial sequences available in public databases and qPCR data of a γ-proteobacterial phylotype, Gamma A (UMB), obtained during several research cruises. Our analysis revealed a complex diversity of diazotrophic γ-proteobacteria. One phylotype in particular, Gamma A, was described in several traditional and quantitative PCR studies. Though several γ-proteobacterial nifH sequences have been described as laboratory contaminants, Gamma A is part of a large cluster of sequences isolated from marine environments and distantly related to the clade of contaminants. Using a TaqMan probe and primer set, Gamma A nifH DNA abundance and expression were analyzed in nearly 1000 samples collected during 15 cruises to the Atlantic and Pacific Oceans. The data showed that Gamma A is an active, cosmopolitan diazotroph found throughout oxygenated, oligotrophic waters reaching maximum abundances of 8 × 104 nifH DNA copies l-1 and 5 × 105 nifH transcript copies l-1. Gamma A nifH transcript abundances were on average 3 fold higher than nifH DNA abundances. The widespread distribution and activity of Gamma A indicate that it has potential to be a globally important N2 fixing organism

On the origin of oxygenic photosynthesis and Cyanobacteria

Oxygenic phototrophs have played a fundamental role in Earth's history by enabling the rise of atmospheric oxygen (O2) and paving the way for animal evolution. Understanding the origin of oxygenic photosynthesis and Cyanobacteria are key when piecing together the events around Earth's oxygenation. It is likely that photosynthesis evolved within bacterial lineages that are not extant, so it can be challenging when studying the early history of photosynthesis. Recent genomic and molecular evolution studies have transformed our understanding about the evolution of photosynthetic reaction centres and the evolution of Cyanobacteria. The evidence reviewed here highlights some of the most recent advances on the origin of photosynthesis both at the genomic and gene family level

Measurements of nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre using a free-drifting submersible incubation device

One challenge in field-based marine microbial ecology is to achieve sufficient spatial resolution to obtain representative information about microbial distributions and biogeochemical processes. The challenges are exacerbated when conducting rate measurements of biological processes due to potential perturbations during sampling and incubation. Here we present the first application of a robotic microlaboratory, the 4 L-submersible incubation device (SID), for conducting in situ measurements of the rates of biological nitrogen (N2) fixation (BNF). The free-drifting autonomous instrument obtains samples from the water column that are incubated in situ after the addition of 15N2 tracer. After each of up to four consecutive incubation experiments, the 4-L sample is filtered and chemically preserved. Measured BNF rates from two deployments of the SID in the oligotrophic North Pacific ranged from 0.8 to 2.8 nmol N L-1 day-1, values comparable with simultaneous rate measurements obtained using traditional conductivity-temperature-depth (CTD)-rosette sampling followed by on-deck or in situ incubation. Future deployments of the SID will help to better resolve spatial variability of oceanic BNF, particularly in areas where recovery of seawater samples by CTD compromises their integrity, e.g. anoxic habitats

Measurements of nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre using a free-drifting submersible incubation device

One challenge in field-based marine microbial ecology is to achieve sufficient spatial resolution to obtain representative information about microbial distributions and biogeochemical processes. The challenges are exacerbated when conducting rate measurements of biological processes due to potential perturbations during sampling and incubation. Here we present the first application of a robotic microlaboratory, the 4 L-submersible incubation device (SID), for conducting in situ measurements of the rates of biological nitrogen (N2) fixation (BNF). The free-drifting autonomous instrument obtains samples from the water column that are incubated in situ after the addition of 15N2 tracer. After each of up to four consecutive incubation experiments, the 4-L sample is filtered and chemically preserved. Measured BNF rates from two deployments of the SID in the oligotrophic North Pacific ranged from 0.8 to 2.8 nmol N L-1 day-1, values comparable with simultaneous rate measurements obtained using traditional conductivity-temperature-depth (CTD)-rosette sampling followed by on-deck or in situ incubation. Future deployments of the SID will help to better resolve spatial variability of oceanic BNF, particularly in areas where recovery of seawater samples by CTD compromises their integrity, e.g. anoxic habitats