Elevated Phosphorus Impedes Manganese Acquisition by Barley Plants

The occurrence of manganese (Mn) deficiency in cereal crops has increased in recent years. This coincides with increasing phosphorus (P) status of many soils due to application of high levels of animal manure and P-fertilizers. In order to test the hypothesis that elevated P my lead to Mn deficiency we have here conducted a series of hydroponics and soil experiments examining how the P supply affects the Mn nutrition of barley. Evidence for a direct negative interaction between P and Mn during root uptake was obtained by on-line inductively coupled plasma mass spectrometry (ICP-MS). Addition of a pulse of KH2PO4 rapidly and significantly reduced root Mn uptake, while a similar concentration of KCl had no effect. Addition of a P pulse to the same nutrient solution without plants did not affect the concentration of Mn, revealing that no precipitation of Mn–P species was occurring. Barley plants growing at a high P supply in hydroponics with continuous replenishment of Mn2+ had up to 50% lower Mn concentration in the youngest leaves than P limited plants. This P-induced depression of foliar Mn accelerated the development of Mn deficiency as evidenced by a marked change in the fluorescence induction kinetics of chlorophyll a. Also plants growing in soil exhibited lower leaf Mn concentrations in response to elevated P. In contrast, leaf concentrations of Fe, Cu, and N increased with the P supply, supporting that the negative effect of P on Mn acquisition was specific rather than due to a general dilution effect. It is concluded that elevated P supply directly interferes with Mn uptake in barley roots and that this negative interaction can induce Mn deficiency in the shoot. This finding has major implications in commercial plant production where many soils have high P levels

SPECT/CT imaging reveals CNS-wide modulation of glymphatic cerebrospinal fluid flow by systemic hypertonic saline

Intrathecal administration enables central nervous system delivery of drugs that do not bypass the blood-brain barrier. Systemic administration of hypertonic saline (HTS) enhances delivery of intrathecal therapeutics into the neuropil, but its effect on solute clearance from the brain remains unknown. Here, we developed a dynamic in vivo single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging platform to study the effects of HTS on whole-body distribution of the radiolabeled tracer (99)mTc-diethylenetriaminepen-taacetic acid (DTPA) administered through intracisternal, intrastriatal, or intravenous route in anesthetized rats. Co-administration of systemic HTS increased intracranial exposure to intracisternal (99)mTc-DTPA by similar to 80% during imaging. In contrast, HTS had minimal effects on brain clearance of intrastriatal (99)mTc-DTPA. In sum, SPECT/CT imaging presents a valuable approach to study glymphatic drug delivery. Using this methodology, we show that systemic HTS increases intracranial availability of cerebrospinal fluid-administered tracer, but has marginal effects on brain clearance, thus substantiating a simple, yet effective strategy for enhancing intrathecal drug delivery to the brain.Peer reviewe

Climate-friendly but socially rejected energy-transition pathways: the integration of techno-economic and socio-technical approaches in the Nordic-Baltic region

A framework to account for social acceptance in the modelling of energy-transition pathways is outlined. The geographical focus is on the Nordic-Baltic energy region and the technological focus is on onshore wind power and power transmission, which are considered key technologies in achieving carbon-neutral energy systems in northern Europe. We combine qualitative analysis of social acceptance with quantitative assessments of scenarios using techno-economic energy-system modelling. Key factors in and consequences of social acceptance are identified, especially environmental, health, and distributional factors, as well as costs for developers and society. The energy system analysis includes four scenarios illustrating the system effects and costs of low social acceptance. The results indicate that if low social acceptance were to restrict investments in onshore wind power, costlier solar photovoltaics and offshore wind power would step in. Greater social acceptance cost for onshore wind and transmission lines favours local solutions and a more balanced renewable energy mix. There are important distributional effects: no restrictions on transmission line investments benefit power producers while raising consumer prices in the Nordic-Baltic energy region, while very low social acceptance of onshore wind power would lead to 12% higher consumer costs. The results imply that socio-technical and political factors such as social acceptance may significantly affect transition pathway scenarios based on techno-economic variables alone. Therefore, the techno-economic, socio-technical and political layers of co-evolution of energy systems should be considered when analysing long-term energy transitions. It is important to link energy-system models with a consideration of the dynamics of socio-technical factors.Peer reviewe