The Prevalence of Marine Lipophilic Phycotoxins Causes Potential Risks in a Tropical Small Island Developing State.

Tropical small island developing states (SIDS), with their geographical isolation and limited resources, heavily rely on the fisheries industry for food and revenue. The presence of marine lipophilic phycotoxins (MLPs) poses risks to their economy and human health. To understand the contamination status and potential risks, the Republic of Kiribati was selected as the representative tropical SIDS and 55 species of 256 coral reef fish encompassing multiple trophic levels and feeding strategies were collected to analyze 17 typical MLPs. Our results showed that the potential risks of ciguatoxins were the highest and approximately 62% of fish species may pose risks for consumers. Biomagnification of ciguatoxins was observed in the food web with a trophic magnification factor of 2.90. Brevetoxin-3, okadaic acid, and dinophysistoxin-1 and -2 were first reported, but the risks posed by okadaic acid and dinophysistoxins were found to be negligible. The correlation analysis revealed that fish body size and trophic position are unreliable metrics to indicate the associated risks and prevent the consumption of contaminated fish. The potential risks of MLPs in Kiribati are of concern, and our findings can serve as valuable inputs for developing food safety policies and fisheries management strategies specific to tropical SIDS contexts.

Tumor-specific enhanced NIR-II photoacoustic imaging via photothermal and low-pH coactivated AuNR@PNIPAM-VAA nanogel.

BACKGROUND: Properly designed second near-infrared (NIR-II) nanoplatform that is responsive tumor microenvironment can intelligently distinguish between normal and cancerous tissues to achieve better targeting efficiency. Conventional photoacoustic nanoprobes are always "on", and tumor microenvironment-responsive nanoprobe can minimize the influence of endogenous chromophore background signals. Therefore, the development of nanoprobe that can respond to internal tumor microenvironment and external stimulus shows great application potential for the photoacoustic diagnosis of tumor. RESULTS: In this work, a low-pH-triggered thermal-responsive volume phase transition nanogel gold nanorod@poly(n-isopropylacrylamide)-vinyl acetic acid (AuNR@PNIPAM-VAA) was constructed for photoacoustic detection of tumor. Via an external near-infrared photothermal switch, the absorption of AuNR@PNIPAM-VAA nanogel in the tumor microenvironment can be dynamically regulated, so that AuNR@PNIPAM-VAA nanogel produces switchable photoacoustic signals in the NIR-II window for tumor-specific enhanced photoacoustic imaging. In vitro results show that at pH 5.8, the absorption and photoacoustic signal amplitude of AuNR@PNIPAM-VAA nanogel in NIR-II increases up obviously after photothermal modulating, while they remain slightly change at pH 7.4. Quantitative calculation presents that photoacoustic signal amplitude of AuNR@PNIPAM-VAA nanogel at 1064 nm has ~ 1.6 folds enhancement as temperature increases from 37.5 °C to 45 °C in simulative tumor microenvironment. In vivo results show that the prepared AuNR@PNIPAM-VAA nanogel can achieve enhanced NIR-II photoacoustic imaging for selective tumor detection through dynamically responding to thermal field, which can be precisely controlled by external light. CONCLUSIONS: This work will offer a viable strategy for the tumor-specific photoacoustic imaging using NIR light to regulate the thermal field and target the low pH tumor microenvironment, which is expected to realize accurate and dynamic monitoring of tumor diagnosis and treatment.

The electrochemical mechanism of biochar for mediating the product ratio of N2O/(N2O + N2) in the denitrification process.

The biochar electrochemical properties and surface functional groups significantly impact N2O production and reduction during denitrification process. However, its effects on N2O emissions during the denitrification process and its electrochemical mechanisms remain unclear. The study examined the impact of pristine and oxidized biochar combined with two types of nitrogen fertilizers on the N2O/(N2O + N2) ratio and N2O emissions in an incubation experiment with seven treatments: (1) CK (no application of chemical fertilizer); (2) N1 (applying (NH4)2SO4); (3) N1B ((NH4)2SO4 + pristine biochar); (4) N1BO ((NH4)2SO4 + oxidized biochar); (5) N2 (applying KNO3); (6) N2B (KNO3 + pristine biochar); (7) N2BO (KNO3 + oxidized biochar). The study found that in comparison with applying nitrogen fertilizer alone, combining pristine biochar decreased soil N2O concentration by 7.1 %-85.8 %, while combining oxidized biochar increased it by 15.7 %-125.6 %. Applying pristine biochar reduced N2O/(N2O + N2) ratio by 10.4 %-86.2 %, whereas applying oxidized biochar increased it by 12.9 %-121.6 %. The application of pristine biochar increased the nosZ gene abundance and decreased the (nirS + nirK)/nosZ ratio, which contributed to reducing N2O to N2. Compared with oxidized biochar, the oxygen-containing functional groups of pristine biochar decreased by 46.6 %, and it possessed a higher specific surface area (23.01 m2 g-1) and electrical conductivity (0.003 mS cm-1). The correlation analysis showed that DOC and inorganic nitrogen were the key environmental factors affecting N2O emissions. Additionally, the electrical conductivity, specific capacitance, and oxygen-containing functional groups of the biochar were identified as the main factors driving N2O emissions. The SEM analysis suggested that the indirect influence of biochar electrochemical properties on N2O emissions was greater than its direct influence. Our work provides fresh perspectives on reducing soil N2O emissions and establishes a theoretical foundation for the subsequent preparation of biochar materials with enhanced N2O reduction capabilities.

Corrigendum: The utility of high-frequency 18 MHz ultrasonography for preoperative evaluation of acral melanoma thickness in Chinese patients.

[This corrects the article DOI: 10.3389/fonc.2023.1185389.].