Resource aromaticity affects bacterial community successions in response to different sources of dissolved organic matter

Microbe-mediated transformation of dissolved organic matter (DOM) contributes substantially to the carbon dynamics and energy flow of aquatic ecosystems; yet, the temporal dynamics of bacterial communities in response to diverse DOM sources are scarcely known. Here, we supplied four distinct sources of DOM (algae-derived, macrophyte-derived, sewage-derived, and soil-derived) to the same bacterial community to track the effects of these DOM sources on the carbon processing and successional dynamics of bacterial communities. Although by the end of the incubation the proportion of bio-degraded DOM was significantly lower in the soil-derived DOM treatment than for the other sources, rapid initial metabolism of protein-like and aliphatic compounds and increasing aromaticity and humification degree of DOM during the incubation period were observed for all sources. The role of stochastic processes in governing the community assembly decreased substantially from 61.4% on the first day to 16.7% at the end of the incubation. Moreover, stronger deterministic selection and lower temporal turnover rate were observed for the soil-derived than the other DOM sources, indicating stronger environmental filtering by the more aromatic DOM. Significant correlations were also observed between the humification index (HIX) of DOM and bacterial community diversities, co-occurrence patterns, habitat niche breadths, and the contribution of deterministic ecological processes. In addition, we demonstrated that taxa with different abundance patterns all play crucial but different roles in the response to DOM variation. Our results indicate the importance of DOM aromaticity as a predictor of the outcome of different DOM sources on bacterial community dynamics.

Enumerating Antibiotic Susceptibility Patterns of Pseudomonas aeruginosa Isolated from Different Sources in Dhaka City

Background:

Pseudomonas aeruginosa is a ubiquitous free-living bacterium and is responsible for severe nosocomial infections, life-threatening infections in immune compromised persons. The bacterium, along with its natural resistance, can acquire resistance to many antibiotics by a variety of methods.

Method:

Therefore, to compare the antibiotic sensitivity pattern of Pseudomonas aeruginosa, a total of seventeen isolates of P. aeruginosa were isolated from different sources; for example environmental sources, frozen food sources, clinical sources and medical waste materials. Isolates were confirmed to be P. aeruginosa by cultural and biochemical properties.

Result:

The isolates were tested against seventeen commercially available antibiotics to observe the antibiotic susceptibility patterns. Imipenem and meropenem were the most potent antibiotics (100% sensitivity) followed by amikacin and piperacillin with maximum sensitivity. Among others, gentamicin, ciprofloxacin, levofloxacin and aztreonam were found to be fairly active. A good number of isolates were intermediately resistant to ceftriaxone. The rates of resistance to aztreonam, cefotaxime and ceftazidime were 11.76%, 82.35% and 5.88% respectively. Complete resistance was observed against penicillin, ampicillin, cefixime and cefpodoxime.

Conclusion:

It can be concluded that the clinical isolates including isolate from medical waste, were multi-drug resistant than environmental and food isolates indicating the risk of transmission of resistance to the environmental isolates of P. aeruginosa.

Imidazole-triggered in situ fluorescence reaction system for quantitatively determination of dopamine from multiple sources

Highly selective and sensitive determination of dopamine (DA) from multiple sources remains a persistent and significant challenge. Here, we develop an imidazole-triggered in situ fluorescence reaction system for highly selective and sensitive determination of DA from various sources (human, horse, dog, rabbit, and mouse). The system operates by catalyzing the oxidation of DA with 1,5-Dihydroxynaphthalene (1,5-DHA) through a Lewis base formed by imidazole, leading to the rapid generation of yellow azamonardine fluorescent compounds (AFC). Notably, the system demonstrates minimal background noise and a high signal-to-noise ratio of up to 300-fold with a determination limit of 33.33 pM, making it 10-100 times more sensitive than conventional enzyme-linked immunosorbent assay (ELISA) methods. Moreover, selectivity tests reveal that our system can effectively distinguish between several common interfering substances, even at concentrations as low as 10 nM. The developed system shows promising results in detecting DA from diverse sources (humans, horses, dogs, rabbits, and mice), including urine samples from clinical patients, exhibiting good agreement with traditional ELISA kits. Therefore, the established in situ fluorescence reaction system holds great potential for the determination of DA-related disorders due to its impressive analytical capabilities.

Exploring critical quality indicators and developing a non-destructive detection method using near-infrared spectroscopy for sea bass (Lateolabrax japonicus) quality evaluation

In this study, chemometrics were employed to explore the relationship between sensory evaluation and physicochemical indicators of sea bass (Lateolabrax japonicus). Through principal component analysis, cluster analysis, and Pearson correlation analysis, three pivotal indicators were identified: protein content, b* value, and condition factor. Leveraging the grey relational analysis, weights were assigned to these three core quality indicators, resulting in a comprehensive sea bass quality evaluation model: Y = 0.911 × protein (g/100 g) + 0.742 × b* + 0.747 × condition factor. Moreover, near-infrared spectroscopy combined with chemometrics were employed to evaluate the quality of sea bass. The different origins of sea bass were accurately distinguished using orthogonal partial least squares discriminant analysis. The partial least squares regression model was constructed for predicting the critical quality indicator, protein content, with R2P of 0.926. This study offers new insights for developing rapid, economical, and reliable methods for assessing aquatic product quality.

Update on the roles and applications of extracellular vesicles in depression

Depression is a prevalent mental disorder that affects numerous individuals, manifesting as persistent anhedonia, sadness, and hopelessness. Despite extensive research, the exact causes and optimal treatment approaches for depression remain unclear. Extracellular vesicles (EVs), which carry biological molecules such as proteins, lipids, nucleic acids, and metabolites, have emerged as crucial players in both pathological and physiological processes. EVs derived from various sources exert distinct effects on depression. Specifically, EVs released by neurons, astrocytes, microglia, oligodendrocytes, immune cells, stem cells, and even bacteria contribute to the pathogenesis of depression. Moreover, there is growing interest in potential of EVs as diagnostic and therapeutic tools for depression. This review provides a comprehensive overview of recent research on EVs from different sources, their roles in depression, and their potential clinical applications.