Molecular dynamics simulation of water condensation with nucleus under electromagnetic wave irradiation.

The condensation process of water with different nuclei under electromagnetic wave irradiation was studied by molecular dynamics simulation. It was found that there is a different electric-field effect when the condensation nucleus was a small (NH4)2SO4 cluster than a CaCO3 nucleus. Through the analysis of the hydrogen-bond number, energy change, and dynamic behavior, we found that the effect of external electric field on the condensation process mainly comes from the change of potential energy caused by the dielectric response and there is a competition effect between the dielectric response and the dissolution in the system with (NH4)2SO4.

16S rRNA gene sequencing reveals the relationship between gut microbiota and ovarian development in the swimming crab Portunus trituberculatus.

Gut microbiota executes many beneficial functions. In this study, the relationship between gut microbiota and ovarian development in the swimming crab P. trituberculatus was explored for the first time. A total of 28 phyla and 422 genera were identified across all samples. However, 105 differential operational taxonomic units, and four differential phyla (Gemmatimonadetes, Actinobacteria, Firmicutes, Marinimicrobia_(SAR406_clade)) were identified. At the genus level, 42 differential genera were identified and 144 bacterial indicators were identified. A key finding was that the relative abundance of 139 indicator bacteria detected in the anisomycin-2 mg/kg group (AK group) was higher than that of blank group (BK group), control group (CK group), SP600125-15 mg/kg group (SK group). In addition, the relative abundance of three indicator bacteria (OTU_236, OTU_1395, OTU_552) detected in the SK group was higher than that of the BK, CK and AK groups. It was also found that the relative abundance of 20 differential genera (Methyloversatilis, Coprococcus_1, Erysipelotrichaceae_UCG_003, Rikenella, Corynebacterium, Ruminiclostridium, Fusicatenibacter, [Eubacterium]_ruminantium_group, Rikenellaceae_RC9_gut_group, Bifidobacterium, Lachnospiraceae_NK4A136_group, Ruminococcaceae_UCG_014, Christensenellaceae_R_7_group, uncultured_Bacteroidales_bacterium, Coprococcus_2, Desulfovibrio, Aggregatibacter, Ambiguous_taxa, Alloprevotella and Ruminococcaceae_NK4A214_group) in the SK, BK, CK, and AK group samples were increasing. These differential genera may reveal the relationship between gut microbial communities and ovarian development in P. trituberculatus after injection with the JNK pathway inhibitor SP600125 or the activator anisomycin. In summary, this study provides a new understanding into the relationship between gut microbiota and ovarian development in response to stimulation with inhibitor or activator.

Temperature potentially induced distinctive flavor of mud crab Scylla paramamosain mediated by gut microbiota.

Many factors affect the flavor of crabs. However, impact of temperature on flavor has not been reported. Here, we examined Scylla paramamosain collected within the main four producing areas in China from north sampling point (NP) and south sampling point (SP), respectively. The contents of flavouring-related substances in hepatopancreas, muscles and gonads were determined by high-performance liquid chromatography (HPLC). Meanwhile, high-throughput sequencing of 16S RNA gene was used to reveal the diversity distribution of gut microbiota at each sample collection point. Comparisons among flavor substances of edible parts, the implied higher temperature in SP may be beneficial to the accumulation of flavor substances in gonads, while lower temperature in NP may be beneficial to the accumulation of flavor substances in muscles and hepatopancreas. The gut microbiota of crabs, was analyzed via 16S rRNA gene sequencing. The results of gut microbiota showed that there were significant differences in the distribution of gut microbiota in NP and SP. The microbiota composition of SP has a high distribution richness and no absolute dominant bacteria, while NP has absolute dominant bacteria and its microbiota richness was lower than SP. The results of redundancy analysis (RDA) showed that there was a significant correlation between temperature and the relative abundance of gut microbiota, and a significant correlation between gut microbiota and the content of flavor substances. This study indicates that temperature may be one of the main factors for the differences of flavor substances between SP and NP, which was most probably mediated by gut microbiota. Further exploration is needed with laboratory experiments in which the environment is more precisely controlled if these views are to be determined.

JNK signaling pathway regulates the development of ovaries and synthesis of vitellogenin (Vg) in the swimming crab Portunus trituberculatus.

The development of Portunus trituberculatus egg cells is directly related to the nutritional status of the fertilized egg, which affects the key production stages of offspring hatching. Vitellogenin plays a key role in the nutrient supply required for the development of the egg cells. The c-Jun N-terminal kinase (JNK) is an important member of the mitogen-activated protein kinase (MAPK) superfamily and plays an important role in cell proliferation, transformation, differentiation, and apoptosis. At present, there are no reports on the involvement of the JNK signaling pathway in the reproductive regulation of P. trituberculatus. In this study, rapid amplification of complementary DNA ends amplification technology was used to clone the full length of JNK complementary DNA, which has a length of 2094 bp, including an open reading frame (ORF) of 1266 bp encoding a 421-amino acid protein. The protein includes the S_TKC conserved domain with a TPY phosphorylation site, which is a typical feature of the JNK gene family. Observing tissue sections found the oocytes in the inhibitor group developed slowly, while the oocytes in the activated group showed accelerated development. Meanwhile, Portunus trituberculatus JNK and vitellogenin (Vg) genes exhibited the same trend in the hepatopancreas and ovaries, and the expression of the SP600125 group was downregulated (P < 0.05), while the anisomycin group was upregulated (P < 0.05). In addition, JNK enzyme activity and vitellin (Vn) content in the ovarian tissue showed that the JNK activity of the SP600125 group decreased, while activity increased in the anisomycin group. The accumulation of Vn content in the SP600125 group decreased, and that in the anisomycin group increased. In summary, after injection with inhibitor or activator, the JNK signaling pathway of P. trituberculatus was inhibited or activated, the accumulation of Vn in the ovary was reduced or increased, and ovarian development was inhibited or accelerated, respectively. These results indicated that the JNK signaling pathway is involved in the regulation of Vg synthesis and ovarian development in P. trituberculatus. The results of this study further add to the knowledge of the breeding biology of P. trituberculatus and provide a theoretical reference for the optimization of breeding techniques in aquaculture production systems.

The antiproliferative effect of spectinabilins from Streptomyces spectabilis on hepatocellular carcinoma cells in vitro and in vivo.

Spectinabilin (1), spectinabilin derivative (2), and a new analogue, 2-demethyl-spectinabilin (3) were isolated from the fermentation broth of a soil-borne Streptomyces spectabilis strain. The structure of the new compound was elucidated by a detailed spectroscopic data analysis including data from CD spectra. Spectinabilin (1) demonstrated cytotoxicity against five human cancer cell lines, with IC50 values ranging from 18.7 ±â€¯3.1 to 34.6 ±â€¯4.7 µM, while derivatives 2 and 3 showed weak cytotoxicities. Notably, 1 inhibited the growth and proliferation of the hepatocellular carcinoma cell lines SMMC7721 and HepG2 in a time- and dose-dependent manner. Further study demonstrated that 1 caused G2/M phase cell cycle arrest in SMMC7721 and HepG2 cells through decreasing the protein levels of cyclin B1 and cdc2 as well as increasing that of p21. Compound 1 downregulated the protein expression of Bcl-2, upregulated Bax, and activated the cleavage of caspase-9 and -3 as a result of inducing apoptosis in SMMC7721 and HepG2 cells. Furthermore, the antitumor effect of 1 in SMMC7721 and HepG2 cells was mediated by the PI3K/AKT signaling pathway. In addition, 1 also suppressed tumor growth in vivo though inducing cell cycle arrest and apoptosis.