Role of VEGFR2 in Mediating Endoplasmic Reticulum Stress Under Glucose Deprivation and Determining Cell Death, Oxidative Stress, and Inflammatory Factor Expression

Retinal pigment epithelium (RPE), a postmitotic monolayer located between the neuroretina and choroid, supports the retina and is closely associated with vision loss diseases such as age-related macular degeneration (AMD) upon dysfunction. Although environmental stresses are known to play critical roles in AMD pathogenesis and the roles of other stresses have been well investigated, glucose deprivation, which can arise from choriocapillary flow voids, has yet to be fully explored. In this study, we examined the involvement of VEGFR2 in glucose deprivation-mediated cell death and the underlying mechanisms. We found that VEGFR2 levels are a determinant for RPE cell death, a critical factor for dry AMD, under glucose deprivation. RNA sequencing analysis showed that upon VEGFR2 knockdown under glucose starvation, endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are reduced. Consistently, VEGFR2 overexpression increased ER stress under the same condition. Although VEGFR2 was less expressed compared to EGFR1 and c-Met in RPE cells, it could elicit a higher level of ER stress induced by glucose starvation. Finally, downregulated VEGFR2 attenuated the oxidative stress and inflammatory factor expression, two downstream targets of ER stress. Our study, for the first time, has demonstrated a novel role of VEGFR2 in RPE cells under glucose deprivation, thus providing valuable insights into the mechanisms of AMD pathogenesis and suggesting that VEGFR2 might be a potential therapeutic target for AMD prevention, which may impede its progression

Effects of Queen Cell Size and Caging Days of Mother Queen on Rearing Young Honey Bee Queens Apis mellifera L.

This study aims to investigate the effect of queen cell size (9.4 mm, 9.6 mm, 9.8 mm and 10.0 mm) and mother queen caged time (0 day, 2 days and 4 days) on rearing young queens without grafting larvae. The birth weight, ovarian tubes, thorax length and width were significantly increased with the increasing diameter of queen cell size. The expression level of Vitellogenin (Vg) in young queen ovaries was also up-regulated with the increased queen cell size diameter. These results indicate that the queen cell size can strongly affect the rearing queen quality and reproductive ability. Moreover, the weight, length and width of laying eggs rose with the mother queen caging time, and young queens reared with the hatched larvae from these eggs were also increased in terms of birth weight, ovarian tubes, thorax length and width. Furthermore, the expression level of Vg in reared queen ovaries was also up-regulated with the caged time. These results reveal that the caged time of queens could significantly influence egg size and their relative queen quality

Dissolved and particulate barium concentrations and isotopes in the Rainbow non-buoyant hydrothermal plume during METEOR cruise M176/2

In order to understand the hydrothermal input of barium (Ba) to the ocean interior and the changes of Ba in the hydrothermal plume, we measured dissolved (0.2 μm) Ba concentrations, as well as stable isotopes, in the non-buoyant hydrothermal plume at the Rainbow hydrothermal vent field on the Mid-Atlantic Ridge. Samples were taken during a GEOTRACES compliant cruise (M176/2) onboard the German R/V Meteor from September to October 2021. Particulate samples were first leached to measure labile components and then digested to measure refractory components. Our investigation covered the plume with a high spatial resolution, extending from a distance of 200 m to 60 km away from the Rainbow hydrothermal vent field

Phytoplankton responses to aluminum enrichment in the South China Sea

Compared to extensive studies reporting the aluminum (Al) toxicity to terrestrial plants and freshwater organisms, very little is known about how marine phytoplankton responds to Al in the field. Here we report the marine phytoplankton responses to Al enrichment in the South China Sea (SCS) using on-deck bottle incubation experiments during eight cruises from May 2010 to November 2013. Generally, Al addition alone enhanced the growth of diatom and Trichodesmium, and nitrogen fixation, but it inhibited the growth of dinoflagellates and Synechococcus. Nevertheless, Al addition alone did not influence the chlorophyll a concentration of the entire phytoplankton assemblages. By adding nitrate and phosphate simultaneously, Al enrichment led to substantial increases in chlorophyll a concentration (especially that of the picophytoplankton < 3 mu m), and cell abundances of diatom and photosynthetic picoeukaryotes. These results indicate varied responses of phytoplankton in different size fractions and taxonomic groups to Al enrichment. Further, by simultaneously adding different macronutrients and/or sufficient trace metals including iron, we found that the phytoplankton responses to Al enrichment were relevant to nutrients coexisting in the environment. Al enrichment may give some phytoplankton a competitive edge over using nutrients, especially the limited ones. The possible influences of Al on the competitors and grazers (predators) of some phytoplankton might indirectly contribute to the positive responses of the phytoplankton to Al enrichment. Our results indicate that Al may influence marine carbon cycle by impacting phytoplankton growth and structure in natural seawater

Aluminum effects on marine phytoplankton: implications for a revised Iron Hypothesis (Iron-Aluminum Hypothesis)

In contrast to substantial studies and established knowledge of aluminum (Al) effects (mainly toxicity) on freshwater organisms and terrestrial plants, and even on human health, only a few studies of Al effects on marine organisms have been reported, and our understanding of the role of Al in marine biogeochemistry is limited. In this paper, we review the results of both field and laboratory experiments on the effects of Al on marine organisms, including Al toxicity to marine phytoplankton and the beneficial effects of Al on marine phytoplankton growth, and we discuss possible links of Al to the biological pump and the global carbon cycle. We propose a revised Iron (Fe) Hypothesis, i.e., the Fe-Al Hypothesis that introduces the idea that Al as well as Fe play an important role in the glacial-interglacial change in atmospheric CO2 concentrations and climate change. We propose that Al could not only facilitate Fe utilization, dissolved organic phosphorus utilization and nitrogen fixation by marine phytoplankton, enhancing phytoplankton biomass and carbon fixation in the upper oceans, but also reduce the decomposition and decay of biogenic matter. As a result, Al allows potentially more carbon to be exported and sequestered in the ocean depths through the biological pump. We also propose that Al binds to superoxide to form an Al-superoxide complex, which could catalyze the reduction of Fe(III) to Fe(II) and thus facilitate Fe utilization by marine phytoplankton and other microbes. Further ocean fertilization experiments with Fe and Al are suggested, to clarify the role of Al in the stimulation of phytoplankton growth and carbon sequestration in the ocean depths

Support vector machine based online coal identification through advanced flame monitoring

This paper presents a new on-line coal identification system based on support vector machine (SVM) to achieve on-line coal identification under variable combustion conditions. Four different coals were burnt in a 0.3 MW coal combustion furnace with different coal feed rates, total air flow rates and flow rate ratios of primary air and secondary air. The flame monitoring system was installed at the exit of the burner to acquire the coal flame images and light intensity signals. Spatial and temporal flame features were extracted for coal identification. The averaged prediction accuracy is 99.1%. The mean value of the infrared signal has the most significant influence on prediction accuracy. For “unstudied” operation cases, the prediction accuracy is 94.7%

Uptake and subcellular distribution of aluminum in a marine diatom

Aluminum (Al) is widespread in the environment including the ocean. The effects of Al on marine organisms have attracted more and more attention in recent years. However, the mechanisms of uptake of Al by marine organisms and the subcellular distribution of Al once assimilated are unknown. Here we report the uptake and subcellular distribution of Al in a marine diatom Thalassiosira weissflogii. Short-term ( debris (17 +/- 4%) > organelles (12 +/- 2%) > heat-stable peptides (HSP) (similar to 2%) > heat-denaturable proteins (HDP) (< 1%), indicating that the majority of intracellular Al was detoxified and stored in inorganic forms. The subcellular distribution of Al in the diatom is different from that of Al in freshwater green algae, in which most of the internalized Al is partitioned to organelles. We also evaluated an artificial seawater-based EDTA rinse solution to remove Al adsorbed on the diatom cell surface. Overall, our study provides new information to understand the mechanisms of uptake of Al by marine diatoms, and the mechanisms responsible for the biological effects (both toxic and beneficial) of Al on the growth of marine phytoplankton, especially diatoms

Phytoplankton community response to episodic wet and dry aerosol deposition in the subtropical North Atlantic

Atmospheric aerosol deposition into the low latitude oligotrophic ocean is an important source of new nutrients for primary production. However, the resultant phytoplankton responses to aerosol deposition events, both in magnitude and changes in community composition, are poorly constrained. Here, we investigated this with 19 d of field and satellite observations for a site in the subtropical North Atlantic. During the observation period, surface dissolved aluminum concentrations alongside satellite-derived aerosol and precipitation data demonstrated the occurrence of both a dry deposition event associated with a dust storm and a wet deposition event associated with strong rainfall. The dry deposition event did not lead to any observable phytoplankton response, whereas the wet deposition event led to an approximate doubling of chlorophyll a, with Prochlorococcus becoming more dominant at the expense of Synechococcus. Bioassay experiments showed that phytoplankton were nitrogen limited, suggesting that the wet deposition event likely provided substantial aerosol-derived nitrogen, thereby alleviating the prevalent nutrient limitation and leading to the rapid observed phytoplankton response. These findings highlight the important role of wet deposition in driving rapid responses in both ocean productivity and phytoplankton community composition

Promoting effects of aluminum addition on chlorophyll biosynthesis and growth of two cultured iron‐limited marine diatoms

Promoting effects of aluminum addition on chlorophyll biosynthesis and growth of two cultured iron‐limited marine diatoms Linbin Zhou CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany University of Chinese Academy of Sciences Beijing China https://orcid.org/0000-0001-7230-4116 Fengjie Liu Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany Grantham Institute—Climate Change and the Environment, Department of Life Sciences Imperial College London London UK Eric P. Achterberg Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany Anja Engel Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany https://orcid.org/0000-0002-1042-1955 Peter G.C. Campbell Institut National de la Recherche Scientifique Centre Eau Terre Environnement Quebec Canada https://orcid.org/0000-0001-7160-4571 Claude Fortin Institut National de la Recherche Scientifique Centre Eau Terre Environnement Quebec Canada https://orcid.org/0000-0002-2479-1869 Liangmin Huang CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China University of Chinese Academy of Sciences Beijing China Yehui Tan CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China University of Chinese Academy of Sciences Beijing China Abstract Aluminum (Al) may play a role in the ocean's capacity for absorbing atmospheric CO 2 via influencing carbon fixation, export, and sequestration. Aluminum fertilization, especially in iron (Fe)‐limited high‐nutrient, low‐chlorophyll ocean regions, has been proposed as a potential CO 2 removal strategy to mitigate global warming. However, how Al addition would influence the solubility and bioavailability of Fe as well as the physiology of Fe‐limited phytoplankton has not yet been examined. Here, we show that Al addition (20 and 100 nM) had little influence on the Fe solubility in surface seawater and decreased the Fe bio‐uptake by 11–22% in Fe‐limited diatom Thalassiosira weissflogii in Fe‐buffered media. On the other hand, the Al addition significantly increased the rate of chlorophyll biosynthesis by 45–60% for Fe‐limited T. weissflogii and 81–102% for Fe‐limited Thalassiosira pseudonana , as well as their cell size, cellular chlorophyll content, photosynthetic quantum efficiency ( F v / F m ) and growth rate. Under Fe‐sufficient conditions, the Al addition still led to an increased growth rate, though the beneficial effects of Al addition on chlorophyll biosynthesis were no longer apparent. These results suggest that Al may facilitate chlorophyll biosynthesis and benefit the photosynthetic efficiency and growth of Fe‐limited diatoms. We speculate that Al addition may enhance intracellular Fe use efficiency for chlorophyll biosynthesis by facilitating the superoxide‐mediated intracellular reduction of Fe(III) to Fe(II). Our study provides new evidence and support for the iron–aluminum hypothesis