Climate-Relevant Ocean Transport Measurements in the Atlantic and Arctic Oceans

Ocean circulation redistributes heat, freshwater, carbon, and nutrients all around the globe. Because of their importance in regulating climate, weather, extreme events, sea level, fisheries, and ecosystems, large-scale ocean currents should be monitored continuously. The Atlantic is unique as the only ocean basin where heat is, on average, transported northward in both hemispheres as part of the Atlantic Meridional Overturning Circulation (AMOC). The largely unrestricted connection with the Arctic and Southern Oceans allows ocean currents to exchange heat, freshwater, and other properties with polar latitudes

Status for miljøet i norske havområder - Rapport fra Overvåkingsgruppen 2023

I denne rapporten gir Overvåkingsgruppen, for første gang, en felles vurdering av miljøtilstanden i Barentshavet og havområdene utenfor Lofoten, Norskehavet og Nordsjøen med Skagerrak. Det er også første rapport som bruker resultater fra det nylig utviklede fagsystemet for vurdering av økologisk tilstand. I denne rapporten dekkes to hovedtemaer: (1) Dominerende trekk i status og utvikling i økosystemet i alle tre havområdene, basert på vurderingene av økologisk tilstand, Overvåkingsgruppens rapport om forurensning fra 2022, indikatorer fra Overvåkingsgruppen som ikke er dekket under vurdering av økologisk tilstand, samt rapporter og annen relevant informasjon fra forskning, og (2) en vurdering av karbonbinding i marint plankton, marine vegetasjonstyper og marine sedimenter. I tillegg er det gitt en oppsummering for endringer i ytre påvirkning, vurdering av kunnskapsbehov samt en vurdering av indikatorverdier i forhold til referanseverdier og tiltaksgrenser. Vurderingen av dominerende trekk i utvikling og tilstand av miljøet som er gitt i kapittel 2, utgjør Overvåkingsgruppens bidrag til Faglig forums samlerapport om det faglige grunnlaget for revisjon og oppdatering av de helhetlige forvaltningsplanene for norske havområder.Status for miljøet i norske havområder - Rapport fra Overvåkingsgruppen 2023publishedVersio

His224 Alters the R2 Drug Binding Site and Phe218 Influences the Catalytic Efficiency of the Metallo beta Lactamase VIM 7

Metallo-β-lactamases (MBLs) are the causative mechanism for resistance to β-lactams, including carbapenems, in many Gram-negative pathogenic bacteria. One important family of MBLs is the Verona integron-encoded MBLs (VIM). In this study, the importance of residues Asp120, Phe218, and His224 in the most divergent VIM variant, VIM-7, was investigated to better understand the roles of these residues in VIM enzymes through mutations, enzyme kinetics, crystal structures, thermostability, and docking experiments. The tVIM-7-D120A mutant with a tobacco etch virus (TEV) cleavage site was enzymatically inactive, and its structure showed the presence of only the Zn1 ion. The mutant was less thermostable, with a melting temperature (T(m)) of 48.5°C, compared to 55.3°C for the wild-type tVIM-7. In the F218Y mutant, a hydrogen bonding cluster was established involving residues Asn70, Asp84, and Arg121. The tVIM-7-F218Y mutant had enhanced activity compared to wild-type tVIM-7, and a slightly higher T(m) (57.1°C) was observed, most likely due to the hydrogen bonding cluster. Furthermore, the introduction of two additional hydrogen bonds adjacent to the active site in the tVIM-7-H224Y mutant gave a higher thermostability (T(m), 62.9°C) and increased enzymatic activity compared to those of the wild-type tVIM-7. Docking of ceftazidime in to the active site of tVIM-7, tVIM-7-H224Y, and VIM-7-F218Y revealed that the side-chain conformations of residue 224 and Arg228 in the L3 loop and Tyr67 in the L1 loop all influence possible substrate binding conformations. In conclusion, the residue composition of the L3 loop, as shown with the single H224Y mutation, is important for activity particularly toward the positively charged cephalosporins like cefepime and ceftazidime

Computational design of the temperature optimum of an enzyme reaction

Cold-adapted enzymes are characterized both by a higher catalytic activity at low temperatures and by having their temperature optimum down-shifted, compared to mesophilic orthologs. In several cases, the optimum does not coincide with the onset of protein melting but reflects some other type of inactivation. In the psychrophilic a-amylase from an Antarctic bacterium, the inactivation is thought to originate from a specific enzyme-substrate interaction that breaks around room temperature. Here, we report a computational redesign of this enzyme aimed at shifting its temperature optimum upward. A set of mutations designed to stabilize the enzyme-substrate interaction were predicted by computer simulations of the catalytic reaction at different temperatures. The predictions were verified by kinetic experiments and crystal structures of the redesigned a-amylase, showing that the temperature optimum is indeed markedly shifted upward and that the critical surface loop controlling the temperature dependence approaches the target conformation observed in a mesophilic ortholog

Toward Improved Estimation of the Dynamic Topography and Ocean Circulation in the High Latitude and Arctic Ocean: The Importance of GOCE

The Norwegian Sea circulation plays a key role in maintaining the mild climate of the northwestern Europe via the transport of warm Atlantic Water pole-ward. The first paper addresses the advective currents connecting the two branches of the Norwegian Atlantic Current and shows the general spin up of the Norwegian Sea circulation during winter with the exception of the flow over the Mohn Ridge. The variability in the surface velocities in the Norwegian Sea is found to be deep reaching, which supports the use of altimetry to monitor the variability of the poleward transport of Atlantic Water. A strengthening and weakening of the Atlantic inflow east of the Faroe Islands has a consistent response along the entire slope current. However, a stronger western inflow, observed north of the Faroe Islands, is associated with more flow of Atlantic Water into the slope current. This finding suggest that a substantial fraction of Atlantic Water that eventually enters the Barents Sea or the Arctic through the Fram Strait, may originate from the western inflowing branch of Atlantic Water to the Nordic Seas, and that the two branches of northward flowing Atlantic Water cannot be considered as separate flows. Paper 2 examines the influence of the surface circulation, eddy activity and local heat loss on the spatial distribution and temporal evolution of dense water formation in the Lofoten Basin. Evidence of intrusion of Atlantic Water into the central Lofoten Basin due to buoyant waters in the eastern part of the basin is found. With the support of hydrographic and satellite datasets, the concept of separate western and eastern regions of the Lofoten Basin is introduced and a link between the western Lofoten Basin and Faroe Shetland overflow waters is identified. Paper 3 addresses an anomalous anticyclonic vortex in the Nordic Seas, which is situated in the western Lofoten Basin. The vortex’ surface and vertical characteristics on seasonal, inter-annual, and climatological time-scales are quantified, relevant forcing mechanisms are addressed, and its uniqueness in the Nordic Seas is documented. In the final paper, a new mean dynamic topography (MDT) is estimated for the North Atlantic and the Arctic from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite gravity anomaly data. The new GOCE-based MDT is assessed and compared to independent steric height observations, other state-of-the-art MDTs and three coupled sea-ice-ocean models, showing its usefulness in studies of high latitude ocean circulation