Striped catfish (Pangasianodon hypophthalmus) exploit food sources across anaerobic decomposition- and primary photosynthetic production-based food chains.

Dietary information from aquatic organisms is instrumental in predicting biological interactions and understanding ecosystem functionality. In freshwater habitats, generalist fish species can access a diverse array of food sources from multiple food chains. These may include primary photosynthetic production and detritus derived from both oxic and anoxic decomposition. However, the exploitation of anoxic decomposition products by fish remains insufficiently explored. This study examines feeding habits of striped catfish (Pangasianodon hypophthalmus) at both adult and juvenile stages within a tropical reservoir, using stable carbon, nitrogen, and sulfur isotope ratios (δ13C, δ15N, and δ34S, respectively) and fatty acid (FA) analyses. The adult catfish exhibited higher δ15N values compared to primary consumers that feed on primary photosynthetic producers, which suggests ingestion of food sources originating from primary photosynthetic production-based food chains. On the other hand, juvenile catfish demonstrated lower δ15N values than primary consumers, correlating with low δ34S value and large proportions of bacterial FA but contained small proportions of polyunsaturated FA. This implies that juveniles utilize food sources from both anoxic decomposition and primary photosynthetic production-based food chains. Our results indicate that food chains based on anoxic decomposition can indeed contribute to the dietary sources of tropical fish species.

Major contribution of sulfide-derived sulfur to the benthic food web in a large freshwater lake.

In freshwater systems, contributions of chemosynthetic products by sulfur-oxidizing bacteria in sediments as nutritional resources in benthic food webs remain unclear, even though chemosynthetic products might be an important nutritional resource for benthic food webs in deep-sea hydrothermal vents and shallow marine systems. To study geochemical aspects of this trophic pathway, we sampled sediment cores and benthic animals at two sites (90 and 50 m water depths) in the largest freshwater (mesotrophic) lake in Japan: Lake Biwa. Stable carbon, nitrogen, and sulfur isotopes of the sediments and animals were measured to elucidate the sulfur nutritional resources for the benthic food web precisely by calculating the contributions of the incorporation of sulfide-derived sulfur to the biomass and of the biogeochemical sulfur cycle supporting the sulfur nutritional resource. The recovered sediment cores showed increases in 34 S-depleted sulfide at 5 cm sediment depth and showed low sulfide concentration with high δ34 S in deeper layers, suggesting an association of microbial activities with sulfate reduction and sulfide oxidation in the sediments. The sulfur-oxidizing bacteria may contribute to benthic animal biomass. Calculations based on the biomass, sulfur content, and contribution to sulfide-derived sulfur of each animal comprising the benthic food web revealed that 58%-67% of the total biomass sulfur in the benthic food web of Lake Biwa is occupied by sulfide-derived sulfur. Such a large contribution implies that the chemosynthetic products of sulfur-oxidizing bacteria are important nutritional resources supporting benthic food webs in the lake ecosystems, at least in terms of sulfur. The results present a new trophic pathway for sulfur that has been overlooked in lake ecosystems with low-sulfate concentrations.

Fetal cardiac capillary hemangioma resulting in tachyarrhythmia.

We present the case of a fetus with cardiac capillary hemangioma in the right atrial cavity. The tumor showed dramatic growth between the 28th and 32nd week of gestation and resulted in tachyarrhythmia. The patient was born at the 33 weeks of gestation weighing 2430 g via urgent cesarean section because the rapidly growing cardiac tumor caused incessant tachyarrhythmia, pericardial effusion, and fetal circulatory incompetence. Coronary angiography revealed that the right coronary artery drained into the tumor. Due to hemodynamic deterioration, the patient underwent subtotal resection of the tumor on the 2nd day after birth. Histopathological examination revealed an undifferentiated capillary hemangioma. The patient was discharged at the age of 86 days, as the tachyarrhythmia and hemodynamic incompetence had subsided; however, bradycardia and intermittent atrioventricular conduction disturbance gradually developed. Capillary hemangioma, a rare primary cardiac space-occupying tumor in children, can invade the conduction system.

High frequency of extended-spectrum beta-lactamase-producing Enterobacteriaceae carriers at a Japanese long-term care hospital.

INTRODUCTION: Long-term care hospitals (LTCHs) are at a high risk for the inflow and spread of antimicrobial resistance (AMR) pathogens. However, owing to limited laboratory resources, little is known about the extent to which AMR organisms are endemic. METHODS: We performed active surveillance for carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) in newly admitted patients at Marugame Medical Center, a nearly 200-bedded LTCH located in Kagawa, Japan. From August to December 2021, we tested stool samples from patients wearing diapers and confirmed the genetic variants using specific PCR assays. We also collected clinical variables and compared them between AMR carriers and non-carriers. RESULTS: Stool samples were collected from 75 patients, with a median age of 84 years. CRE strain was not detected, but 37 strains of ESBL-E were isolated from 32 patients (42.7%). During the study period, 4.9% of in-hospital patients (37 per 756 patients) were identified to be ESBL-E carriers in the routine microbiological processing, suggesting that active surveillance detected approximately 9-fold more ESBL-E carriers. The blaCTX-M-9 group was the most common (38.5%), followed by the blaTEM (26.9%). The clinical backgrounds of the ESBL-E non-carriers and carriers were not significantly different. CONCLUSION: Our active screening demonstrated that nearly half of the patients hospitalized or transferred to a Japanese LTCH were colonized with ESBL-E. We highlight the enforcement of universal basic infection prevention techniques at LTCHs where patients carrying AMR pathogens gather.

Digestion Efficiency during Alkaline Persulfate Oxidation for Determination of Total Phosphorus Content of Biological Samples.

Quantifying total phosphorus contents of organisms can elucidate their physiological condition and the nutrient cycles of ecosystems. Simple, brief, and safe persulfate oxidation methods have been used for total P determination, but oxidizing solutions of different compositions and volumes have been used. Two certified reference materials were used to evaluate digestion efficiencies of different solutions for this study. Although the phosphorus recoveries were low (<90%) without NaOH, phosphorus recoveries using the solution with 4% K2S2O8 and 0.15 M NaOH were complete. Results demonstrated that digestion efficiency depends on the K2S2O8 concentration and on the pH condition. Moreover, the phosphorus recoveries were achieved at >4 mL/mg solution/material ratios for both standard materials. Therefore, the author recommends using >4 mL of the 4% K2S2O8 solution with 0.15 M NaOH for sample materials of <1 mg to quantify the total phosphorus of biological samples.

Influence of δ18 O of water on measurements of δ18 O of nitrite and nitrate.

RATIONALE: Oxygen isotope ratio measurements of NO2 - and NO3 - by the azide method and denitrifier method are sensitive to the δ18 O value of the sample water. However, the influence of δ18 OH2O on those measurements has not been quantitatively evaluated and documented so far. Therefore, we investigated the influence of δ18 OH2O of a sample on the δ18 O analysis of NO2 - and NO3 - . METHODS: We prepared NO2 - and NO3 - standards (with known δ18 ONO2- and δ18 ONO3- values) dissolved in waters having different δ18 OH2O values (δ18 OH2O = -12.6, 25.9, 56.7, and 110.1‰). Nitrite and nitrate were converted into N2 O using the azide method and the denitrifier method, respectively. The isotope ratios of the generated N2 O were measured with a Sercon purge-and-trap gas chromatography/isotope ratio mass spectrometry (PT-GC/IRMS) system. The measured δ18 O values of the produced N2 O were plotted against known δ18 ONO2- and δ18 ONO3- values to evaluate the influence of exchange of an oxygen atom with H2 O during the conversion of NO2 - into N2 O and NO3 - into N2 O, respectively. RESULTS: The degree of oxygen isotope exchange was 10.8 ± 0.3% in the azide method and 5.5 ± 1.0% in the denitrifier method, indicating that the azide method is more susceptible to artifacts arising from differences in the δ18 OH2O value of water than the denitrifier method. Thus, the intercept of the standard calibration curve must be corrected to account for differences in δ18 OH2O . Abiotic NO2 -H2 O equilibrium isotope effect experiments yielded a rate constant of (1.13 ± 007) × 10-2 (h-1 ) and an equilibrium isotope effect of 11.9 ± 0.1‰ under the condition of pH = 7.5, 30°C, and 2.5% salinity. CONCLUSIONS: Oxygen isotope ratio measurements of NO2 - by the azide method are highly sensitive to δ18 OH2O as a result of significant oxygen isotope exchange between NO2 - and H2 O. Therefore, to obtain the most accurate measurements water with the same δ18 OH2O value as that of the sample must be used to make the NO2 - and NO3 - standards.

Evaluation of nutrient and energy sources of the deepest known serpentinite-hosted ecosystem using stable carbon, nitrogen, and sulfur isotopes.

The Shinkai Seep Field (SSF) in the southern Mariana forearc discovered in 2010 is the deepest (~5,700 m in depth) known serpentinite-hosted ecosystem dominated by a vesicomyid clam, Calyptogena (Abyssogena) mariana. The pioneering study presumed that the animal communities are primary sustained by reducing fluid originated from the serpentinization of mantle peridotite. For understanding the nutrient and energy sources for the SSF community, this study conducted four expeditions to the SSF and collected additional animal samples such as polychaetes and crustaceans as well as sediments, fragments of chimneys developing on fissures of serpentinized peridotite, seeping fluid on the chimneys, and pore water within the chimneys. Geochemical analyses of seeping fluids on the chimneys and pore water of the chimneys revealed significantly high pH (~10) that suggest subseafloor serpentinization controlling fluid chemistry. Stable isotope systematics (carbon, nitrogen, and sulfur) among animals, inorganic molecules, and environmental organic matter suggest that the SSF animal community mostly relies on the chemosynthetic production while some organisms appear to partly benefit from photosynthetic production despite the great depth of SSF.

Characteristic odor components of Citrus reticulata Blanco (ponkan) cold-pressed oil.

Citrus reticulata Blanco (ponkan) cold-pressed oil and its oxygenated fraction were studied by analytical (GC and GC/MS) and sensory analyses. The monoterpene group was predominant, accounting for more than 89.6% (w/w), of which limonene was the most abundant (80.3%). Among the oxygenated compounds, octanal and decanal were the major ones among 12 aldehydes accounting for >1.5%; six alcohols were identified with a total concentration of >0.7%, while oxides, ketones and esters did not quantitatively or qualitatively contribute to the oil. Sniffing the ponkan cold-pressed oil and its oxygenated fraction demonstrated that octanal and decanal were the characteristic odor components of ponkan. Reconstruction of the ponkan aroma model and its sensory evaluation by a hedonic test were performed, showing that, in addition to octanal and decanal which played important roles, (R)-(+)-limonene contributed to the aroma model as a background component, making the aroma model very similar to that of the original.

Characteristic odor components of Citrus sphaerocarpa Tanaka (Kabosu) cold-pressed peel oil.

The volatile components of Citrus sphaerocarpa Tanaka (Kabosu) cold-pressed peel oil were investigated by chemical and sensory analyses. Monoterpene hydrocarbons (more than 94.6%) were predominant in Kabosu peel oil, with limonene and myrcene accounting for the major proportions (70.5% and 20.2%, respectively). The Kabosu oxygenated fraction was characterized by quantitative abundance in aldehydes and a relatively wide variety of alcohols. The weight percentages of aldehydes, alcohols, and esters in Kabosu cold-pressed oil were 1.3%, 0.1%, and 0.1%, respectively. Aroma extract dilution analysis was employed for determination of the odors of Kabosu volatile components, flavor dilution factors, and relative flavor activities. Gas chromatography/olfactometry using Kabosu cold-pressed oil and its oxygenated fraction completed by a chiral analysis revealed that (R)-(+)-citronellal is a characteristic element of Kabosu peel oil odor. Careful sniff testing demonstrated that aqueous solutions of both 0.25% and 0.016% (R)-(+)-citronellal gave an odor similar to that of Kabosu.