Exchange of energy,nitrogen and phosphorus between water,bottom and ice in a near-shore ecosystem of the Sea of Japan

The processes taking place at the partioning boundaries of a marine ecosystem are still rather obscure. At a permanent research station, water (in winter, ice) samples were taken throughout the year from 6 different depths, and 16 variables related to productivity and hydrochemistry were determined. Transparent and black-walled bell jars were installed on the sea bottom at depths ranging from 0 to 10 m in order to record rates of photosynthesis, respiration and chemical metabolism. In the region studied, two peaks of phytoplankton development occurred: one in winter and one in summer. The winter one coincided with a rise in orthophosphate and nitrate concentrations; the summer peak, with a rise in water temperature and increase of bottom regeneration. Photosynthesis of bottom diatoms was evidenced for all depths investigated. Ammonia and orthophosphate excretion were recorded in all experiments conducted on soft substrata. The measured rates of regeneration corresponded with the values expected in accordance with seasonal changes in nitrogen and phosphorus concentrations. Turnover rates of nitrogen and phosphorus between water and sediment were about 2 to 4 months. Higher production of coastal sea regions may be partly explained by the proximity of the photic layer to sediments and by the increased regeneration rates of biogenous elements.     

Potent inhibition of microRNA in vivo without degradation

Chemically modified antisense oligonucleotides (ASOs) are widely used as a tool to functionalize microRNAs (miRNAs). Reduction of miRNA level after ASO inhibition is commonly reported to show efficacy. Whether this is the most relevant endpoint for measuring miRNA inhibition has not been adequately addressed in the field although it has important implications for evaluating miRNA targeting studies. Using a novel approach to quantitate miRNA levels in the presence of excess ASO, we have discovered that the outcome of miRNA inhibition can vary depending on the chemical modification of the ASO. Although some miRNA inhibitors cause a decrease in mature miRNA levels, we have identified a novel 2′-fluoro/2′-methoxyethyl modified ASO motif with dramatically improved in vivo potency which does not. These studies show there are multiple mechanisms of miRNA inhibition by ASOs and that evaluation of secondary endpoints is crucial for interpreting miRNA inhibition studies.     

Advective Mixing of Pore Waters and Ecology of Sandy Sediments of the Ocean Shelf

Sand sediments are widely distributed in the shelf zone of the World Ocean. The main physical and ecological peculiarity of marine sands is the mobility of pore waters and their mixing with the near-bottom waters of the sea. The mixing is closely related to turbulent processes in the water column; the most important of these processes is wave mixing. This causes filtration of seawater through the sand, ensuring therefore, perhaps, the most large-scale filtration process on the Earth. Advective mixing redistributes dissolved oxygen and nutrients between the pore waters of the sand and the bulk of the seawater column and determines redox conditions in the sediment column, which usually are either oxidative or suboxic; the metals with variable valence, mostly iron, serve as a redox buffer. The regeneration of nutrients and nitrification of ammonia also take place in the sand column. The instability of advective mixing is considered as the major difficulty for qualitative assessment of energetic metabolism and regeneration of nutrients in sands as well as for revealing the ecological role of marine sands in coastal ecosystems.     

Metal accumulation in two contiguous eutrophic peri-urban lakes,Chivero and Manyame,Zimbabwe

Concentrations of aluminium, cadmium, chromium, cobalt, copper, iron, lead, nickel and zinc were determined in surface water, benthic sediments, and the gills, liver and stomach muscle tissues of Oreochromis niloticus and Clarias gariepinus in peri-urban lakes Chivero and Manyame, Zimbabwe. Five sites were sampled in each lake once per month in November 2015, February, May, August and November 2016. Pollution load index detected no metal contamination, whereas the geo-accumulation index reflected heavy to extreme sediment pollution, with Fe, Cd, Zn, Cr, Ni and Cu present in both lakes. Significant spatial temporal variations were detected for Al, Cr, Cu and Pb across sites within and between the two lakes. High Fe, Al and Cr concentrations in water and sediments in lakes Chivero and Manyame derive from geogenic background sources in addition to anthropogenic loads and intensity. Elevated concentrations of Al, Pb, Cu, Cd, Fe and Zn detected in gills, liver and stomach tissue of catfish corroborate concentrations in water and sediments, and pose the highest ecological and health risk for hydrobionts in lakes Chivero and Manyame. Contiguity of peri-urban lakes exposes them to similar threats, necessitating creative water management strategies, which ensure ecological continuity.     

The antidepressant-like effect of Ocimum basilicum in an animal model of depression

We investigated the efficacy of Ocimum basilicum (OB) essential oils for treating depression related behavioral, biochemical and histopathological changes caused by exposure to chronic unpredictable mild stress (CUMS) in mice and to explore the mechanism underlying the pathology. Male albino mice were divided into four groups: controls; CUMS; CUMS plus fluoxetine, the antidepressant administered for pharmacological validation of OB; and CUMS plus OB. Behavioral tests included the forced swim test (FST), elevated plus-maze (EPM) and the open ?eld test (OFT); these tests were performed at the end of the experiment. We assessed serum corticosterone level, protein, gene and immunoexpression of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) as well as immunoexpression of glial fibrillary acidic protein (GFAP), Ki67, caspase-3 in the hippocampus. CUMS caused depression in the mice as evidenced by prolonged immobility in the FST, prolonged time spent in the open arms during the EPM test and reduction of open field activity in the OFT. OB ameliorated the CUMS induced depressive status. OB significantly reduced the corticosterone level and up-regulated protein and gene expressions of BDNF and GR. OB reduced CUMS induced hippocampal neuron atrophy and apoptosis, and increased the number of the astrocytes and new nerve cells. OB significantly increased GFAP-positive cells as well as BDNF and GR immunoexpression in the hippocampus.     

The denitrification potential and density of denitrifying bacteria in the bottom sediments of Matupi Harbor (Papua New Guinea)

The denitrification potential and density of denitrifying bacteria were determined in suboxidized sediments of Matupi Harbor (Papua New Guinea). The sediments were characterized by low denitrification potentials, not exceeding 0.8 nM/(g h). The maximum density of denitrifying bacteria was recorded in the upper sediment horizons and was 10⁴ cells/g of wet ground.