Polychaete Bioturbation Alters the Taxonomic Structure, Co-occurrence Network, and Functional Groups of Bacterial Communities in the Intertidal Flat.

Polychaetes are important benthic macrofauna that lives in sediments, usually in intertidal flats with high organic content and high sulfide. It has been suggested that polychaete bioturbation could perform environmental remediation. During the process, the microbial community plays important roles. Here, we used high-throughput sequencing technology to study the bioturbation effects on the bacterial community in the polychaete (Perinereis aibuhitensis) burrows at different tidal positions in intertidal flat. The results showed that the bacterial communities were dramatically influenced by the polychaete bioturbation. The ACE, Chao, and Shannon indices of the polychaete burrows increased in summer. Dominant phyla in the polychaete burrows were Proteobacteria, Campilobacterota, Desulfobacterota, Chloroflexi, and Bacteroidota, and the dominant bacterial families were Sulfurvaceae, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, Desulfobulbaceae, and Sulfurimonadaceae. Results of linear discriminant analysis effect size (LEfSe) showed that groups that include organic matter degraders, such as Bacteroidota, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, and groups that include sulfur oxidizers, such as Campilobacterota, Sulfurovaceae, Rhodobacteraceae, Desulfobulbaceae, and Sulfurimonadaceae, were significantly increased due to the polychaete bioturbation. The polychaete bioturbation reduced the complexity of the bacterial co-occurrence network while increased its modularity and homogeneity. The polychaete bioturbation also changed the functional groups, which significantly enhanced in functional groups of aerobic nitrite oxidation, nitration, dark thiosulfate oxidation, dark sulfur oxidation, and dark sulfite oxidation, while nitrogen respiration and nitrate respiration decreased. These results provide insight into the impact of bacterial communities under the intertidal polychaete bioturbation.

A novel calreticulin-related molecule that interacts with bacteria and enhances host resistance against bacterial infection in black rockfish, Sebastes schlegeli.

Calreticulin (CRT) is a highly conserved and multi-functional protein with diverse localizations. CRT has lectin-like properties and possesses important immunological activities in mammalian. In teleost, very limited studies on CRT immunologic function have been documented. In the present study, a CRT homologue (SsCRT) was cloned, identified and characterized from black rockfish, Sebastes schlegeli, an important aquaculture species in East Asia. The full length of SsCRT cDNA is 2180 bp and encoded a polypeptide of 425 amino acids. SsCRT contains a signal peptide, three distinct structural and functional domains (N-, P- and C-domains), and an endoplasmic reticulum (ER) retrieval signal sequence (KDEL). The deduced amino acid sequence of SsCRT shares 89-92% overall sequence identities with the CRT proteins of several fish species. SsCRT was distributed ubiquitously in all the detected tissues and was highly expressed in the spleen, muscle and liver. After the infection of fish extracellular bacterial pathogen Vibrio anguillarum and intracellular bacterial pathogen Edwardsiella tarda, the mRNA transcripts of SsCRT in spleen, liver, and head kidney were significantly up-regulated. The expression patterns were time-dependent and tissue-dependent. Recombinant SsCRT (rSsCRT) exhibited apparent binding activities against different bacteria and PAMPs. In vivo studies showed that the expressions of multiple immune-related genes such as TNF13B, IL-1ß, IL-8, SAA, Hsp70, and ISG15 in head kidney were significantly enhanced when black rockfish were treated with rSsCRT. Furthermore, rSsCRT reduced pathogen dissemination and replication in fish kidney and spleen. These results indicated that SsCRT served as an immune receptor to recognize and eliminate the invading pathogens, which played a vital role in the immune response of Sebastes schlegeli. These findings provide new insights into understanding the roles of CRT proteins in immune response and pathogen infection in teleost.

Highly Luminescent Carbon Dots Synthesized by Microwave-Assisted Pyrolysis and Evaluation of Their Toxicity to Physa acuta.

As a newly emerging class of nanomaterials, carbon dots have increasingly attracted researchers' attention. However, their potentially adverse environmental effects are yet largely unknown. In this work, the highly luminescent carbon dots were synthesized by microwave-assisted pyrolysis of tris(hydroxymethyl)aminomethane (Tris) and citric acid. Then acute and chronic toxicities of carbon dots to Physa acuta (P. acuta), as well as their effect on reproduction, were evaluated using the as-synthesized dots as an example. The quantum yield of the as-synthesized carbon dots was up to 53.5% excited at 360 nm with the most fluorescent fraction of 82.6% after simple purification by gel column. The results showed that no acute but chronic toxicities to P. acuta exposed to different treatment concentrations of the as-synthesized carbon dots were observed with dose- dependence. In addition, the fecundity of P. acuta was promoted significantly by the carbon dots at the concentrations of 0.5 and 1.0 mg/mL, yet inhibited at the concentration of 3.0 mg/mL after 12-day exposure. Mainly distributing in the visceral mass might be responsible for the effects of the carbon dots on the survival and fecundity of P. acuta. And there was no further evidence to confirm that the carbon dots can cause malformation in developing embryos.

Inhibition potential of UDP-glucuronosyltransferases (Ugts) 1A isoforms by the analogue of resveratrol, bakuchiol.

Bakuchiol is a promising anti-tumor candidate with resveratrol-like structure. The present study aims to evaluate the inhibition potential of bakuchiol towards UDP-glucuronosyltransferases (UGT) 1A isoforms. An in vitro incubation system using 4-methylumbelliferone (4-MU) glucuronidation was used to evaluate the inhibition capability of bakuchiol towards UGT1A1, 1A3, 1A6, 1A7, 1A8, 1A9 and 1A10. The glucuronidation of trifluoperazine (TFP) was employed as the probe reaction to determine bakuchiol's inhibition towards UGT1A4. At 1 microM and 10 microM of bakuchiol, no or weak inhibition was observed for all the tested UGT1A isoforms. At 100 microM of bakuchiol, the activity of UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9 and 1A10 was inhibited by -46.2%, 74.7%, 17.8%, 98.7%, 70.4%, 99.2%, 75.8%, and 93.3%, respectively. Further inhibition kinetic behaviour was determined for UGT1A6, 1A8, and 1A10. Both Dixon plot and Lineweaver-Burk plot showed the noncompetitive inhibition of bakuchiol towards all these three UGT isoforms. The inhibition kinetic parameters (Ki) were calculated to be 5.3, 1.8, and 92.6 microM for UGT1A6, 1A8, and 1A10, respectively. In combination with the in vivo exposure of bakuchiol, the high possibility of in vivo inhibition of UGT1A6 and 1A8 was predicted. However, relatively low possibility of in vivo inhibition towards UGT1A10 was predicted due to lower in vivo concentration of bakuchiol than its inhibition parameter (Ki). All these information will be helpful for the R&D of bakuchiol as a promising anti-tumor drug.

Genetic variation and population structure of swimming crab (Portunus trituberculatus) inferred from mitochondrial control region.

Genetic variation and population structure in Portunus trituberculatus along the coast of China were revealed according to 617 bp of mitochondrial DNA control region. 90 polymorphic sites defined 53 distinct haplotypes, showing a moderately high diversity among 72 individuals sampled from eight localities. Neighbor-joining tree, statistics analyses of gene flow and genetic differentiation index indicated two populations from Beihai and Laizhou had differentiated. The population from Yingkou, Dandong, Laizhou and Beihai had smaller genetic diversity compared to that from Ningbo, Lianyungang, Qingdao and Japan according to the genetic distance. And mantel test showed significant positive correlation between genetic distance and geographic distance for P. trituberculatus. TCS parsimony network suggested that all the animals sampled were probably the result of recent divergence from a common ancestral haplotype but for Laizhou population. Moreover, the haplotype distribution appeared to correlate with a recent colonization followed by localized genetic differentiation. Mismatch distribution results suggested that Ningbo, Yingkou, Qingdao, Lianyungang and Japan populations, particularly Dandong population had experienced a sudden demographic or spatial expansion. The Pleistocene glaciations might contribute to this process.