Symbiodiniaceae are the source of essential coral symbionts of reef building corals. The growth and density of endosymbiotic Symbodiniaceae within the coral host is highly dependent on nutrient availability, yet little is known about how Symbiodiniaceae respond to the dynamics of the nutrients, including switch between different chemical forms and changes in abundance.In this study, we investigated physiological, cytometric, and transcriptomic responses in Fugacium kawagutii to nitrogen (N)-nutrient deficiency and different chemical N forms (nitrate and ammonium) in batch culture conditions. We mainly found that ammonium was consumed faster than nitrate when provided separately, and was preferentially utilized over nitrate when both nitrogen compounds were supplied at 1:2, 1:1 and 2:1 molarity ratios. Besides, Ndeficiency caused decreases in growth, energy production, antioxidative capacity and investment in photosynthate transport but increased energy consumption. Growing on ammonium produced a similar cell yield as nitrate, but with a decreased investment in nutrient transport and assimilation. These all have important implications of N nutrient to support symbiosis in coral ecosystem, especially regarding ammonium. In addition, by integrating our current results with previous data, we identified ten highly and stably expressed genes as candidate reference genes, which will be potentially useful for gene expression studies in the future.

18Symbiodiniaceae are the source of essential coral symbionts of reef building corals. The growth 19 and density of endosymbiotic Symbodiniaceae within the coral host is highly dependent on 20 nutrient availability, yet little is known about how Symbiodiniaceae respond to the dynamics 21 of the nutrients, including switch between different chemical forms and changes in abundance. 22In this study, we investigated physiological, cytometric, and transcriptomic responses in 23 Fugacium kawagutii to nitrogen (N)-nutrient deficiency and different chemical N forms (nitrate 24 and ammonium) in batch culture conditions. We mainly found that ammonium was consumed 25 faster than nitrate when provided separately, and was preferentially utilized over nitrate when 26 both nitrogen compounds were supplied at 1:2, 1:1 and 2:1 molarity ratios. Besides, N-27 deficiency caused decreases in growth, energy production, antioxidative capacity and 28 investment in photosynthate transport but increased energy consumption. Growing on 29 ammonium produced a similar cell yield as nitrate, but with a decreased investment in nutrient 30 transport and assimilation. These all have important implications of N nutrient to support 31 symbiosis in coral ecosystem, especially regarding ammonium. In addition, by integrating our 32 current results with previous data, we identified ten highly and stably expressed genes as 33 candidate reference genes, which will be potentially useful for gene expression studies in the 34 future. 35

Global Navigation Satellite System (GNSS) attitude determination and positioning play an important role in many navigation applications. However, the two GNSS-based problems are usually treated separately. This ignores the constraint information of the GNSS antenna array and the accuracy is limited. To improve the performance of navigation, an integrated attitude and position determination method based on an affine constraint model is presented. In the first part, the GNSS array model and affine constrained attitude determination method are compared with the unconstrained methods. Then the integrated attitude and position determination method is presented. The performance of the proposed method is tested with a series of static data and dynamic experimental GNSS data. The results show that the proposed method can improve the success rate of ambiguity resolution to further improve the accuracy of attitude determination and relative positioning compared to the unconstrained methods.

Dinoflagellates are ubiquitous protists playing several major roles in marine ecosystems: carbon fixers, essential endosymbionts of reef building corals, active micrograzers, culprits of harmful algal blooms, and sources of various bioactive agents, e.g., eicosapentaenoic acid and docosahexaenoic acid (Hallegraeff, 1993;Jang et al., 2017;Lin, 2011). The family Symbiodiniaceae is the sole source of phytosymbionts of corals Abstract Nitrogen (N) controls the growth of phytoplankton and the phytosymbionts of corals, but little is known about N nutrition in free-living planktonic species of the Symbiodiniaceae family. Here, with physiological and transcriptomic analyses, we investigated how Effrenium voratum responded to N deficiency or a nitrate (NO 3 − ) to ammonium (NH 4 + ) switch. The results from batch cultures showed that E. voratum grew well on both NH 4 + and NO 3 − , but NH 4 + supported higher yield. Furthermore, when provided with both NH 4 + and NO 3 − , E. voratum preferentially utilized NH 4 + and consumed it faster than NO 3 − . Inhibitory effects of NH 4 + on cell growth and photochemical efficiency were detected at ≥ 440 μM in a dose-dependent manner. When NH 4 + and NO 3 − were compared, only 582 genes were differentially expressed; NH 4+ promoted expression of genes related to N transport, carbon fixation, chlorophyll synthesis, and cell division. In contrast, N deficiency inhibited cell division, decreased Chl a content, and changed expression of a large number (4,553) of genes involved in a wide range of metabolic processes from N acquisition, carbon fixation, photosynthate translocation, glycolysis, ROS production, to the cell cycle. This study provides baseline information about N nutrition in a free-living symbiodiniacean dinoflagellate, which will be useful for comparative research with symbiotic counterparts. The findings also underscore the need to consider differences among phytoplankton groups in responding to forms (NH 4 + versus NO 3 − ) and availability (N repletion versus deficiency) of N-nutrient in modeling N effects on phytoplankton dynamics.Plain Language Summary Like global warming and ocean acidification, the anthropogenic changes in nutrient input to the ocean have profound impacts on the ecology of dinoflagellates, including symbiosis with corals. Potential differences in responding to variable nitrogen (N) nutrient forms and abundances between symbiotic and free-living species are poorly understood. The main goal of this study was to document the effects of N-nutrients on the free-living symbiodiniacean species Effrenium voratum, and examine its differences from the putative mutualistic species Fugacium kawagutii. Results show that N-nutrient deficiency significantly impacts the cell growth, photosynthesis, and a wide range of metabolic processes in E. voratum. Furthermore, E. voratum prefers ammonium over nitrate as N-nutrient, but high concentrations of ammonium (≥ 440 μM) are inhibitory to E. voratum growth. In comparison, E. voratum growth is more tolerant, but nitrate u...