Ammonia stress was detrimental to shrimp, but how water ammonia nitrogen (ammonia-N) influences the shrimp’s health remains unclear. Thus, this study was designed to investigate the effects of water ammonia-N on hemolymph ammonia-N concentration, hepatopancreas structure, and the intestinal microbiota of Litopenaeus vannamei with four experiments. We found that the concentration of ammonia-N in shrimp hemolymph was significantly higher than that in pond water, indicating that water ammonia-N stimulates the accumulation of hemolymph ammonia-N. Results also indicated that the hemolymph ammonia-N accumulation would disrupt the hepatopancreas structure and alter the intestinal microbial composition. The concentration of hemolymph ammonia-N and severity of hepatopancreas damage positively correlated with water ammonia-N concentration. However, though the diversity of intestinal microbiota was varied by ammonia-N, there were no significant differences between groups, suggesting that the variation was relatively minimal. Furthermore, returning shrimp to pristine water after ammonia-N exposure could reduce the hemolymph ammonia-N concentration and the mortality rate. This study provides evidence of temporal variations in hemolymph ammonia-N concentration, hepatopancreatic structure, and intestinal microbiota under different water ammonia-N levels, which might shed insights into ecological cognition on scientific management of shrimp culture and microecological prevention of shrimp health.
SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) Variants of Concern (VOCs), such as the Omicron sub-variants, present significant challenges in pandemic control due to their capacity to escape antibodies and breach vaccine protections. Discovering antibodies that can tolerate mutations in VOCs and understanding their underlying mechanisms is crucial for developing therapeutics for COVID-19 patients, particularly those for whom other therapies may be unsuitable. Here, we report the neutralization of the Omicron variant by FD20, a broadly active human monoclonal antibody. In contrast to a clinically approved control antibody, FD20 neutralizes Omicron with comparable IC50 values to those observed for previously circulating VOCs and the original strain reported in Wuhan. Leveraging structural information, we provide insights into its resilience against mutations in Omicron. The results encourage the prospective development of FD20 as a therapeutic option for COVID-19 caused by current and potentially future VOCs.
• High-level secretion expression (~250 mg L-1) of divalent nanobodies in Pichia.
• Detergent washing effectively removes yellow pigment from secreted nanobodies.
• Nanobodies after pigment removal remain biologically active.
Porcine epidemic diarrhea virus (PEDV), Transmissible gastroenteritis virus (TGEV), Porcine deltacoronavirus (PDCoV) and Swine acute diarrhea syndrome coronavirus (SADS-CoV) rank among the most frequently encountered swine enteric coronaviruses (SECoVs), leading to substantial economic losses to the swine industry. The availability of a rapid and highly sensitive detection method proves beneficial for the monitoring and surveillance of SECoVs. Based on the N genes of four distinct SECoVs, a novel detection method was developed in this study by combining recombinant enzyme polymerase isothermal amplification (RPA) with clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins (Cas) 12a. Results showed that the cut-off value of CRISPR-Cas12a assay for SADS-CoV, PEDV, PDCoV and TGEV was 2.19 × 104 Relative Fluorescence Units (RFU), 1.57 × 104 RFU, 3.07 × 104 RFU and 1.64 × 104 RFU, respectively. The coefficient of variation (CV) of within and between runs by CRISPR-Cas12a assay for 6 clinical diarrhea samples were both less than 10%. The CRISPR-Cas12a assay demonstrated high specificity for TGEV, PEDV, PDCoV, and SADS-CoV with no cross-reactivity to other common swine viruses. This method also exhibited a low limit of detection of 2 copies for each virus. Additionally, the results demonstrated a perfect agreement (100%) between the CRISPR-Cas12a assay and the RT-qPCR assay. Finally, a total of 494 pig samples from the field tested by CRISPR-Cas12a assay showed that positive rate for SADS-CoV, TGEV, PDCoV and PEDV was 0, 0, 1.2% and 48.6%, respectively. The results suggested the great potential of CRISPR-Cas12a assay to detect SECoVs in the field.
While biotechnologies offer eco-friendly solutions for eliminating air contaminants, there is a scarcity of research examining the impacts of microbial purification of air pollutants on the structure and function of air microbial communities. In this study, we explored a Lactobacillus paracasei B1 (LAB) agent for removing ammoniacal odour. The impacts of LAB on air bacterial community were revealed. by analyzing the air samples before (BT) and after (AT) LAB bioagent treatment. Remarkably, the LAB bioagent significantly reduced the air ammonia concentration by 96.8%. This reduction was associated with a notable decline in bacterial diversity and a significant shift in community composition. The relative abundance of Staphylococcus, a common pathogen, plummeted from 1.91% to 0.03%. Moreover, other potential pathogens decreased by over 87%, signifying the bioagent's impactful role in diminishing health risks. The dominance of OTU-4 (Lactobacillus) highlighted its crucial role not only in competitive interactions but also potentially in shaping the metabolic pathways or community dynamics within the treated air microbial ecosystem. This shift towards deterministic assembly processes post-treatment, as highlighted by the normalized stochasticity ratio (NST), sheds light on the underlying mechanisms dictating the microbial community's response to bioagent interventions. The bioagent-purified air microbial community showed a strong preference for variable selection (88.9%), likely due to the acidity generated by the LAB. In conclusion, our findings emphasized the positive impact of LAB bioagent in enhancing air quality, which associated with the changes in microbial community.