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Global warming can inhibit chlorophyll-based solar energy capturing of phytoplankton by decreasing nutrient supply through upwelling. However, species with proton-pump rhodopsin (PPR) can independently convert solar energy to cope with nutrient limitation. Besides prokaryotes, PPR has been documented in dinoflagellates and some species of other algal lineages, and its potential role in compensating for the deficiency of phosphorus has been demonstrated in dinoflagellates. However, PPR has not been studied in the coral reef endosymbiotic Symbiodiniaceae. Here, we report a PPR in Breviolum minutum (BmR). Both phylogenetic analysis and structure prediction results indicate that BmR resembles eukaryotic proton-pump rhodopsins, phylogenetically affiliated with the subgroup xanthorhodopsins. BmR contains the critical residues for proton pumping, retinal binding, and spectrum tuning for green absorption. To explore BmR's potential roles in responding to phosphorus limitation, we cultured B. minutum under different phosphorus conditions, and monitored physiological and BmR's transcriptional responses. Phosphorus limitation caused decreases in B. minutum population growth and photosynthesis efficiency. Meanwhile, our quantitative PCR showed that BmR expression was strongly upregulated under phosphorus limitation, showing a strong positive correlation with alkaline phosphatase activity and a negative correlation with photosynthetic efficiency. Our findings demonstrate that proton-pump rhodopsin occurs in Symbiodiniaceae and BmR has the potential to provide supplementary energy to support cell basal metabolisms when photosynthesis of B. minutum is impaired by phosphorus limitation, thereby enabling corals to better weather climate change. [ABSTRACT FROM AUTHOR]

The local resonance phononic crystals have advantages in obtaining low frequency band gaps, while the local resonance band gap obtained by traditional structures is inconvenient for engineering applications due to its narrow width. In this manuscript, a theoretical framework for the design and analysis of the Outward Hierarchical Local Resonance Euler Beam (OHLREB) structure has been introduced, which considers the foundational constraints, non-rigid interfaces, and the damping characteristics of the coating layer, leading to a significant enhancement in the low-frequency band gap properties. To analyze the band gap properties of OHLREB, the improved transfer matrix method is derived to obtain the band structure, and the spectral element method is applied to calculate the frequency response function. Furthermore, the band gap mechanism is investigated based on modal analysis of primitive cell and the time domain analysis and energy period analysis of OHLREB structure. The results indicate that improved transfer matrix method can offer a more streamlined and transparent process for solving eigenvalues and determining attenuation intervals, which can be used for the theoretical analysis of band gap regulation. It overcomes the constraints of traditional approaches by reducing the computational burden associated with matrix inversions and multiplications, thereby enhancing the efficiency of band gap analysis. The band gap mechanism investigation demonstrates that the energy conversion period is considerably longer than the load period in band gap frequency, leading to multiple conversions of the kinetic energy of the scatterer and the elastic strain energy of the coating layer within a single energy cycle, which leads to the strong local resonance and results in the attenuation of elastic waves in the band gap range. The parameter analysis is carried out to reveal the regulation laws of band gap, the results reveal that band gap intervals and attenuation efficiency can be optimized to obtain low frequency and broadband by configurating properly the control parameters, such as the matrix reaction modulus, interface stiffness, the coating layer damping, and the scatterer combination. Based on the analysis results, the design and control directions for obtaining the wider and lower frequency band gaps are given. The conclusions obtained in this manuscript can provide theoretical support and practical design perspectives for multi-frequency vibration control field. [ABSTRACT FROM AUTHOR]

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Proton-pump rhodopsin (PPR) in marine microbes can convert solar energy to bioavailable chemical energy. Whereas bacterial PPR has been extensively studied, counterparts in microeukaryotes are less explored, and the relative importance of the two groups is poorly understood. Here, we sequenced whole-assemblage metatranscriptomes and investigated the diversity and expression dynamics of PPR in microbial eukaryotes and prokaryotes at a continental shelf and a slope site in the northern South China Sea. Data showed the whole PPRs transcript pool was dominated by Proteorhodopsins and Xanthorhodopsins, followed by Bacteriorhodopsin-like proteins, dominantly contributed by prokaryotes both in the number and expression levels of PPR unigenes, although at the continental slope station, microeukaryotes and prokaryotes contributed similarly in transcript abundance. Furthermore, eukaryotic PPRs are mainly contributed by dinoflagellates and showed significant correlation with nutrient concentrations. Green light-absorbing PPRs were mainly distributed in >3 μm organisms (including microeukaryotes and their associated bacteria), especially at surface layer at the shelf station, whereas blue light-absorbing PPRs dominated the <3 μm (mainly bacterial) communities at both study sites, especially at deeper layers at the slope station. Our study portrays a comparative PPR genotype and expression landscape for prokaryotes and eukaryotes in a subtropical marginal sea, suggesting PPR's role in niche differentiation and adaptation among marine microbes. [ABSTRACT FROM AUTHOR]

Trypsin is best known as a digestive enzyme in animals, but remains unexplored in phytoplankton, the major primary producers in the ocean. Here we report the prevalence of trypsin genes in global ocean phytoplankton and significant influences of environmental nitrogen (N) and phosphorus (P) on their expression. Using CRISPR/Cas9 mediated-knockout and overexpression analyses, we further reveal that a trypsin in Phaeodactylum tricornutum (PtTryp2) functions to repress N acquisition, but its expression decreases under N-deficiency to promote N acquisition. On the contrary, PtTryp2 promotes phosphate uptake per se, and its expression increases under P-deficiency to further reinforce P acquisition. Furthermore, PtTryp2 knockout led to amplitude magnification of the nitrate and phosphate uptake 'seesaw', whereas PtTryp2 overexpression dampened it, linking PtTryp2 to stabilizing N:P stoichiometry. Our data demonstrate that PtTryp2 is a coordinate regulator of N:P stoichiometric homeostasis. The study opens a window for deciphering how phytoplankton adapt to nutrient-variable marine environments. Using CRISPR-Cas9 mediated-knockout and overexpression analyses, this study shows that a trypsin in the diatom Phaeodactylum tricornutum promotes phosphorus uptake and inhibits nitrogen uptake but its expression is downregulated under nitrogen stress and upregulated under phosphorus stress. Together, the findings suggest this trypsin is a coordinate regulator of nutrient homeostasis. [ABSTRACT FROM AUTHOR]

Object: Methylmalonic acidemia (MMA) with early-onset severe hydrocephalus is rare. In this paper, we described two cases of MMA with hydrocephalus and review the literature to elucidate the clinical features of the disease, treatment options, and follow-up results.Methods: The PubMed and Embase databases were searched for clinical reports on MMA with severe hydrocephalus, and two unreported cases were presented to illustrate the clinical spectrum.Results: Six cases of MMA with severe hydrocephalus were observed in the previous literature. Our two patients with severe hydrocephalus but not bulging fontanelle received a ventriculo-peritoneal shunt, and intracranial hypertension was confirmed in both cases during the operation. These patients’ clinical symptoms significantly improved after the operation.Conclusions: Intracranial hypertension can exist in early-onset severe hydrocephalus in MMA, even if the bulging anterior fontanelle is not apparent. These patients could benefit from a ventriculo-peritoneal shunt. [ABSTRACT FROM AUTHOR]

This paper reviews the work done by researchers at INRS and UBC in the field of integrated microwave photonics (IMWPs) using silicon based waveguide Bragg gratings (WBGs). The grating design methodology is discussed in detail, including practical device fabrication considerations. On-chip implementations of various fundamental photonic signal processing units, including Fourier transformers, Hilbert transformers, ultrafast pulse shapers etc., are reviewed. Recent progress on WBGs-based IMWP subsystems, such as true time delay elements, phase shifters, real time frequency identification systems, is also discussed. [ABSTRACT FROM AUTHOR]