Rhodomonas sp. Hf-1 strain (cryptophyte) has been known as an excellent feed for some marine animals in aquaculture. In this study, the Hf-1 strain was cultured under different nitrogen ...concentrations to evaluate the effect of N-starved conditions on its growth and biochemical profile. Two nitrate concentrations of 0.9 mM (Low-N) and 3.5 mM (High-N) were supplemented to the media. The cell suspensions were sampled on day 3 and 7 and analyzed for photosynthesis pigments, protein and relative fatty acids contents. The nitrate in Low-N and High-N cultures was exhausted by day 3 and 7, respectively, and growth in Low-N culture was significantly lower than in High-N culture. Phycoerythrin (PE) content decreased in both cultures compared to chlorophyll (Chl) a and c, and a cell-color change was only observed in Low-N culture, indicating that PE was preferentially degraded compared with Chl a and c when nitrogen in the medium was limiting. The intercellular carbon and hydrogen content in the Hf-1 cells cultured in both media showed similar changes throughout the experiment, hence C/H ratios did not differ in between. On the other hand, the intercellular nitrogen content in the Hf-1 cells cultured with High-N medium increased from 5.6 to 10.3% from day 3–7. However, Low-N culture showed a decrease in nitrogen content from 8.1 to 4.1%. Consequently, C/N ratio in Low-N and High-N culture showed entirely different tendency. Similarly, the protein content in the Hf-1 cell cultured with High-N medium increased during 4 days. In contrast, Low-N culture showed a decrease by 30% in protein content. Relative fatty acids content in the Hf-1 cell was lower in Low-N culture than High-N culture through the experiment. The dominant fatty acids in Low-N culture were poly-unsaturated fatty acids (PUFA) on day 3, which accounted for 37.4% of total fatty acid. However, the relative content of PUFA reduced to 24.7% of total fatty acid by the end of the experiment, and the dominant fatty acids shifted to saturated fatty acids (SFA). These data indicate that nitrogen starvation in the medium induced a simultaneous decrease in protein and relative fatty acids contents with the cell-color change for the Hf-1 cell, suggesting the possibility that this behavior on the cell-color change can be used as a valid indicator to determine the harvest timing of Rhodomonas species visually.
•Effects of nitrogen starvation on growth and biochemical profile of Rhodomonas sp. Hf-1 strain were examined.•Nitrogen starvation induced low growth performance and negatively affected the biochemical profile with a distinct cell-color change.•Our results indicated the possibility that the cell-color change can be used as a valid indicator to timely harvest.
Diffraction-limited two-photon microscopy permits minimally invasive optical monitoring of neuronal activity. However, most conventional two-photon microscopes impose significant constraints on the ...size of the imaging field-of-view and the specific shape of the effective excitation volume, thus limiting the scope of biological questions that can be addressed and the information obtainable. Here, employing a non-telecentric optical design, we present a low-cost, easily implemented and flexible solution to address these limitations, offering a several-fold expanded three-dimensional field of view. Moreover, rapid laser-focus control via an electrically tunable lens allows near-simultaneous imaging of remote regions separated in three dimensions and permits the bending of imaging planes to follow natural curvatures in biological structures. Crucially, our core design is readily implemented (and reversed) within a matter of hours, making it highly suitable as a base platform for further development. We demonstrate the application of our system for imaging neuronal activity in a variety of examples in zebrafish, mice and fruit flies.
The dietary requirement of calcium (Ca) has been well established in terrestrial animals. However, investigations for dietary Ca requirement in fish are complicated and reports limited as fish can ...use waterborne Ca in addition to dietary Ca. Ca absorption in fishes from environmental water is species specific and depends on concentration of Ca in rearing environment and availability of dietary Ca. Ca and phosphorus are generally combined together in fish body therefore maintaining a dietary calcium: phosphorus ratio is important. Ca exists in a complex form in fish meal, which is not available to fishes; hence, although fish meal contains an appreciable amount of calcium, dietary Ca supplementation in fish meal‐based diets for some species is necessary. This review article summarizes and discusses pertinent information on absorption of Ca from water, essentiality of dietary Ca, bioavailability of Ca from different sources, optimum calcium:phosphorus ratio and dietary Ca requirement in fishes.
Resonant slot-antenna-integrated uni-travelling-carrier photodiodes were developed for enhancing terahertz (THz)-wave output powers while maintaining relatively broad bandwidths. Their output powers ...were two to three times larger at their peaks than those of a non-resonant bowtie-antenna-integrated device. The output powers were enhanced at frequencies from 900 GHz to 1.6 THz for a narrow-slot device and from 350 to 850 GHz for a wide-slot device. Typical output powers were 3.5 μW at 1.25 THz and 28 μW at 700 GHz for a photocurrent of 10 mA with a bias voltage of only −0.4 V.
A polarisation-sensitive sub-terahertz-wave detector has been developed by integrating an InP/InGaAsP Schottky barrier diode and a modified bowtie antenna. The fabricated quasi-optical module could ...detect signals at frequencies ranging from 30 GHz to 1 THz. The measured sensitivities were 1080 V/W at 250 GHz, 250 V/W at 400 GHz and 86 V/W at 600 GHz for a zero-bias condition. The principal polarisation axis angle for signal detection was confirmed to be stable within ±1.5° in a frequency ranging from 80 to 600 GHz, while the degree of polarisation was more than 95%.
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