10Boron Is Mobile in Cowpea Plants

Cowpea [Vigna unguiculata (L.) Walp] is cultivated in tropical and subtropical regions worldwide, but its production is usually limited by boron (B) deficiency, which can be mitigated by applying B via foliar spraying. In plants with nutrient mobility, the residual effect of foliar fertilization increases, which might improve its efficiency. An experiment was carried out to evaluate the concentration and mobility of the B isotopic tracer (10B) in different organs of cowpea plants, after the application of this micronutrient in the growing media and also to leaves. Treatments were designed based on B fertilization as follows: without B in the growth media, with 10B applied via foliar spraying (10B-L), with B in the growth media (substrate) and 10B via foliar spraying (10B-L + B-S), and with 10B in the growth media (substrate) without foliar spraying (10B-S), and a control without fertilization. A redistribution of 10B was observed in new leaves when the element was supplied via foliar spraying, resulting in greater leaf area, dry mass and dry matter production of aerial parts, and also the whole plant. 10Boron was redistributed when applied via foliar spraying in cowpea plants, regardless of the plant's nutritional status, which in turn might increase internal B cycling.

Stable Isotopic Tracer Phospholipidomics Reveals Contributions of Key Phospholipid Biosynthetic Pathways to Low Hepatocyte Phosphatidylcholine to Phosphatidylethanolamine Ratio Induced by Free Fatty Acids

There is a strong association between hepatocyte phospholipid homeostasis and non-alcoholic fatty liver disease (NAFLD). The phosphatidylcholine to phosphatidylethanolamine ratio (PC/PE) often draws special attention as genetic and dietary disruptions to this ratio can provoke steatohepatitis and other signs of NAFLD. Here we demonstrated that excessive free fatty acid (1:2 mixture of palmitic and oleic acid) alone was able to significantly lower the phosphatidylcholine to phosphatidylethanolamine ratio, along with substantial alterations to phospholipid composition in rat hepatocytes. This involved both a decrease in hepatocyte phosphatidylcholine (less prominent) and an increase in phosphatidylethanolamine, with the latter contributing more to the lowered ratio. Stable isotopic tracer phospholipidomic analysis revealed several previously unidentified changes that were triggered by excessive free fatty acid. Importantly, the enhanced cytidine diphosphate (CDP)-ethanolamine pathway activity appeared to be driven by the increased supply of preferred fatty acid substrates. By contrast, the phosphatidylethanolamine N-methyl transferase (PEMT) pathway was restricted by low endogenous methionine and consequently low S-adenosylmethionine, which resulted in a concomitant decrease in phosphatidylcholine and accumulation of phosphatidylethanolamine. Overall, our study identified several previously unreported links in the relationship between hepatocyte free fatty acid overload, phospholipid homeostasis, and the development of NAFLD.

Impact of antecedent wetness and precipitation intensity on catchment travel and response times

<p>The time a molecule of rain takes to reach the stream is normally substantially longer than the time for discharge to respond to rainfall. This difference arises because hydraulic potentials propagate through landscapes much faster than water itself does; in other words, the celerity of wave propagation is faster than the velocity of water flow. Although these concepts are well established, most catchment studies are restricted to the calculation of the celerity or response time from hydrometric information. However, to understand the storage, release, and transport of water, as well as identify flow paths through the catchment, one needs to estimate both response and travel times, requiring both hydrometric and tracer data.</p><p>We analyzed hydrometric and tracer data from two contrasting sites, the pre-Alpine Erlenbach catchment in Switzerland and the Upper Hafren catchment at Plynlimon in Wales. For both sites, hydrometric data and sub-daily isotopic tracer time series are available, enabling the calculation of response times as well as travel time distributions and new water fractions. To gain a deeper understanding of the functioning of the two catchments, we quantified these metrics and distributions for different ranges of antecedent wetness and precipitation intensity. Generally, wetter catchment conditions and higher precipitation intensities yielded faster runoff responses and shorter travel times.  Contrasts between travel and response time distributions under varying catchment conditions also facilitated more nuanced insights into catchment functioning and the effects of catchment wetness and precipitation intensity on water storage and release.</p>