Introduction The fruits of Areca catechu, also called areca nuts, are widely used as popular masticatory and traditional herbal medicine in Asia. Besides arecoline and related alkaloids, limited information is available about further primary and secondary metabolites and their potential biological activities. Objective Here we aimed to further enhance our knowledge on phytochemical profiles of A. catechu and Areca triandra fruits. We intended to comprehensively identify metabolites in A. catechu and A. triandra fruits. Methodology Metabolites were identified by ultra‐performance liquid chromatography triple‐quadrupole tandem mass spectrometry (UPLC–MS/MS). The occurrence of 12 selected bioactive compounds in 4 different developmental stages of A. catechu and A. triandra was quantified by LC–MS/MS. Results A total of 791 metabolites was identified. Of these, 115 metabolites could successfully be mapped to 44 Kyoto Encyclopedia of Genes and Genomes metabolic pathways, and 154 metabolites occurred at significantly different levels in A. catechu compared to A. triandra. Several components with known biological activities were identified for the first time in A. catechu and A. triandra. The abundance of many of these new components was similar in A. catechu and A. triandra, but significantly different between the pericarp and the seeds of A. catechu fruits. Conclusions Metabolic profiles indicate that fruits of the Areca species compared here have similar primary and secondary metabolites. Our findings provide new insights into A. catechu and A. triandra as valuable sources for traditional medicine and they pave the way for further studies to potentially improve the underlying pharmaceutical and physiological effects.

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Iron (Fe) and Zinc (Zn) are essential nutrient elements for plant growth and development. Here, we observed the effects of Fe and Zn deficiency in seedlings of Areca catechu L. (areca palm), one of the most cultured palm trees in tropic regions. Results revealed that Fe deficiency causes strong chlorosis with the significantly decreased chlorophyll biosynthesis level and photosynthetic activities in the top third young leaf (L3) of seedlings. Zn deficiency caused light chlorosis in all three young leaves which slightly decreased chlorophyll biosynthesis and photosynthetic activities. Analysis of the Fe and Zn concentration in leaves and roots indicated that absorption and distribution of these two ions share cooperative pathways, since Zn deficiency caused Fe increasing, and vice versa. Therefore, we focused on the ZINC-IRON PERMEASE (ZIP) genes in areca trees. From the whole-genome data set we obtained, 6 ZIP genes were classified, and a phylogenetic tree was constructed with other 38 ZIP genes from model plants to find their potential functions. We also analyzed the expression pattern of AcZIP1-6 genes under Zn and Fe deficiency by transcriptomic approaches. With these results, we constructed an expression atlas of AcZIP1-6 genes in leaves and roots of areca seedlings with the dynamic expression levels under Fe and Zn deficient conditions. In conclusion, we provide evidence to understand the absorption and transport of nutrient elements, Fe and Zn, in the tropic agricultural plant A. catechu.

The apoptosis of hemocytes plays an essential function in shrimp immune defense against pathogen invasions. In order to further elucidate the differential apoptotic responses of the granulocytes and the hyalinocytes in Fenneropenaeus chinensis post WSSV infection, the characteristics of apoptotic dynamics and viral proliferation in total hemocytes and hemocyte subpopulations were respectively investigated in the present work. The results showed that the apoptotic rate of hemocytes changed significantly, and the apoptosis-related genes also showed significantly differential expression responses during WSSV infection. Interestingly, we found that the apoptotic rate of virus-negative hemocytes was significantly higher than that of virus-positive hemocytes in the early stage of WSSV infection, while it was significantly lower than that of virus-positive cells in the middle and late infection stages. The difference of apoptosis between virus-positive and virus-negative hemocytes seems to be an important way for the WSSV to destroy the host’s immune system and facilitate the virus spread at different infection stages. It was further found that the apoptosis rate of granulocytes was always significantly higher than that of hyalinocytes during WSSV infection, indicating that granulocytes have a stronger apoptotic response to WSSV infection. Moreover, a higher viral load was detected in granulocytes, and the density of granulocytes decreased more rapidly post WSSV infection, indicating that the granulocytes are more susceptible and vulnerable to WSSV infection compared with the hyalinocytes. These results collectively demonstrated that the apoptotic response in shrimp hemocytes was significantly influenced by the WSSV infection, and the differential apoptotic response of granulocytes and hyalinocytes to WSSV indicated the differences of antiviral mechanisms between the two hemocyte subpopulations.

Hemocytes play central roles in shrimp immune system, whereas whose subclasses have not yet been completely defined. At present, the morphological classification of hemocytes is inadequate to classify the complete hemocyte repertoire and elucidate the functions and differentiation and maturation processes. Based on single-cell RNA sequencing (scRNA-seq) of hemocytes in healthy Litopenaeus vannamei, combined with RNA-FISH and flow cytometric sorting, we identified three hemocyte clusters including TGase+ cells, CTL+ cells and Crustin+ cells, and further determined their functional properties, potential differentiation trajectory and correspondence with morphological subpopulations. The TGase+ cells were mainly responsible for the coagulation, exhibiting distinguishable characteristics of hyalinocyte, and appeared to be developmentally arrested at an early stage of hemocyte differentiation. The CTL+ cells and Crustin+ cells arrested at terminal stages of differentiation mainly participated in recognizing foreign pathogens and initiating immune defense responses, owning distinctive features of granule-containing hemocytes. Furthermore, we have revealed the functional sub-clusters of three hemocyte clusters and their potential differentiation pathways according to the expression of genes involved in cell cycle, cell differentiation and immune response, and the successive differentiation and maturation of hyalinocytes to granule-containing hemocytes have also mapped. The results revealed the diversity of shrimp hemocytes and provide new theoretical rationale for hemocyte classification, which also facilitate systematic research on crustacean immunity.