ß-glucan regulates the intestinal immunity of pearl gentian grouper via the nuclear factor kappa B signaling pathway.

The preceding study observed that yeast ß-glucan supplementation enhanced intestinal health and augmented disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀), which occurred concurrently with the activation of the nuclear factor kappa B (NFκB) signaling pathway. Thus, we hypothesized that ß-glucan improves intestinal health in grouper by modulating the NFκB pathway. Accordingly, the present study examined the effects of NFκB pathway disruption using a specific inhibitor on the intestinal health of pearl gentian grouper that had been injected with ß-glucan. The experimental groups were as follows, (1) CD group: PBS injected; (2) ßG group: ß-glucan injected at a dose of 80 mg/kg; (3) PDTC group: NFκB inhibitor PDTC injected at a dose of 30 mg/kg; (4) ßG + PDTC group: a combination of ß-glucan (80 mg/kg) and PDTC (30 mg/kg) injected together. The results demonstrated that ß-glucan-induced increases in mRNA expression levels of NFκB inhibitor α (iκbα) and p65, the degradation and phosphorylation of IκBα, and the phosphorylation of NFκB p65 were significantly inhibited following NFκB inhibition using PDTC in the intestine of grouper. The PDTC injection resulted in a significant reduction in the ß-glucan-induced increase in mucin levels. The ß-glucan-induced elevation of alkaline phosphatase (AKP) activity, component 3 (C3) content, and inflammatory factors were significantly suppressed following NFκB inhibition. The ßG + PDTC treatment resulted in a restoration of catalase (CAT) enzyme activity to the level observed in the CD treatment, while total antioxidant capacity (T-AOC) was decreased to the level of the ßG treatment. The ß-glucan-induced downregulation of caspase8 (casp8) was reversed following NFκB inhibition, as well as the mRNA levels of casp3 and casp9 being elevated to a greater extent. In conclusion, the ß-glucan-regulated intestinal immunity in grouper may be mediated by the NFκB pathway. Furthermore, the inhibitory effect of ß-glucan on apoptosis and oxidative stress may not be related to the NFκB signaling pathway.

ß-glucan improves intestinal health of pearl gentian grouper via activation of the p38 mitogen-activated protein kinase signaling pathway.

Our previous study has demonstrated that supplementation of yeast ß-glucan improves intestinal health in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀), accompanied by the activation of the mitogen-activated protein kinase (MAPK) signaling pathway. In this study, we investigated the effects of perturbing p38 MAPK activity using an inhibitor on the intestinal health of ß-glucan-injected pearl gentian grouper to elucidate the potential molecular mechanism underlying the protective effects of ß-glucan on the fish gut. The pearl gentian grouper was categorized into four groups: PBS injected (CD group), ß-glucan injected at a dose of 80 mg/kg (ßG group), p38 MAPK inhibitor SB203580 injected at a dose of 1 mg/kg (SB203580 group), and a combination of ß-glucan (80 mg/kg) and SB203580 (1 mg/kg) injected together (ßG + SB203580 group). The results revealed that the introduction of SB203580 significantly suppressed the ß-glucan-induced increase in p38α and p38ß mRNA expression, as well as the phosphorylation of p38 MAPK. Both the ßG group and SB203580 group exhibited reduced plica height and muscularis thickness. The ßG + SB203580 group displayed a significant reduction in mucin cell level; interleukin 1ß (il1ß) mRNA expression; induced nitric oxide synthase, tumor necrosis factor α, and IL1ß concentration; catalase and total antioxidant capacity activities. Additionally, there was a significant increase in the levels of intestinal malondialdehyde in the ßG + SB203580 group compared to the ßG group. The inhibition of the p38 MAPK signaling halted the trend of apoptosis-related caspase molecular expression induced by ß-glucan. In conclusion, ß-glucan injection resulted in elevated levels of mucous cells, nonspecific immunity, antioxidant capacity, and anti-apoptosis in grouper by modulating the p38 MAPK pathway. This study offers insights into the potential molecular mechanism underlying the protective effects of ß-glucan on intestinal health in pearl gentian grouper.

Parvularcula maris sp. nov., an algicidal bacterium isolated from seawater.

A taxonomic study was carried out on strain BGMRC 0090T, which was isolated from seawater. The isolate was a Gram-negative, aerobic, flagellated, rod-shaped bacterium with algicidal activity. Optimal growth was observed at 30 °C, pH 6.0 and with 2 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BGMRC 0090T belonged to the genus Parvularcula, with highest sequence similarity to Parvularcula lutaonensis CC-MMS-1T (98.4 %). Average nucleotide identity, amino acid identity and digital DNA-DNA hybridization values between strain BGMRC 0090T and five strains of the genus Parvularcula with publicly available genomes were below 84.0, 69.2 and 21.4 %, respectively. The genome of strain BGMRC 0090T was 3.2 Mb with 64.8 mol% DNA G+C content and encoded 2905 predicted proteins, three rRNA, 42 tRNA and four ncRNA genes. Some algicidal biosynthesis-associated genes were detected in the genome. Strain BGMRC 0090T contained Q-10 as the major quinone. The predominant fatty acids were identified as summed feature 8 (C18 : 1ω7c/ω6c) and C16 : 0. Based on the polyphasic evidence presented in this paper, strain BGMRC 0090T is concluded to represent a novel species of the genus Parvularcula, for which the name Parvularcula maris sp. nov. is proposed. The type strain is BGMRC 0090T (= KCTC 92591T=MCCC 1K08100T).

Efficacy and transcriptome analysis of golden pompano (Trachinotus ovatus) immunized with a formalin-inactived vaccine against Streptococcus iniae.

Streptococcus iniae is a worldwide fish pathogen that cause tremendous economic losses to the global aquaculture industry. Vaccination is regarded as the most effective and safe way to control fish diseases. In our study, we developed a formalin-inactivated vaccine against S. iniae and evaluated its effect in golden pompano (Trachinotus ovatus). In addition, in order to clarify the molecular mechanisms underlying the vaccine protection, we compared the spleen transcriptomes of vaccinated and unvaccinated golden pompano at 1, 2 and 7 d post vaccination using the RNA-seq technology. The relative percentage survival (RPS) reached 71.1% at 28 days post-vaccination which suggested that the vaccine provided highly protection against S. iniae. KEGG pathway analysis revealed that phagosome, cytokine-cytokine receptor interaction, MAPK signaling pathway, and CAMs were activated by the vaccine. The most of strongly up-regulated genes in golden pompano spleen are involving in innate immunity. For adaptive immunity, the vaccine evoked a CD8+ CTL-mediated response by MHC Ⅰ pathway to achieve immune protection.

Characterization of a new selenoprotein methionine sulfoxide reductase from Haematococcus pluvialis and its antioxidant activity in response to high light intensity, hydrogen peroxide, glyphosate, and cadmium exposure.

Selenium incorporates into selenocysteine (Sec) which is a key component of selenoproteins implicated in antioxidant defense and redox homeostasis. Methionine sulfoxide reductases (Msr) play crucial roles in cellular defense against environmental stress. Whereas mammals have the MsrB selenoprotein form, unicellular organisms have MsrA. The Sec residue at the conserved catalytic sites of selenoprotein MsrA confers a metabolic advantage over the non-selenoprotein type MsrA. In the present study, the novel selenoprotein HpMsrA from Haematococcus pluvialis was cloned by the rapid amplification of cDNA ends and transformed into the model green alga Chlamydomonas reinhardtii. Alignment of homologs revealed the presence of the conserved catalytic domain GUFW and showed that the HpMsrA protein comprises Sec (U) at the N-terminus but no recycled Cys at the C-terminus. We studied the response of HpMsrA expression to selenite, high light intensity, hydrogen peroxide, cadmium nitrate, and glyphosate exposure via real-time quantitative PCR and enzyme activity analysis. The results demonstrated that HpMsrA protects cellular proteins against oxidative and environmental stressors. Compared with wild type C. reinhardtii, the transformant exhibited a superior antioxidant ability. The discoveries made herein shed light on the antioxidant physiology and environmental stress resistance mechanisms of the selenoproteins in microalgae. This information may aid in conducting environmental risk assessments of aquatic ecosystems involving microalgae known to respond rapidly and quantitatively to abiotic stress factors promoting excessive reactive oxygen species generation.

Roseomonas coralli sp. nov., a heavy metal resistant bacterium isolated from coral.

A Gram-stain-negative, aerobic, mesophilic, non-motile bacterium, designated M0104T, was isolated from a gorgonian coral collected from Xieyang island, Guangxi Province, PR China. Colonies of the strain were non-motile cocci and pink. The strain grew at 15-34 °C (optimum, 28 °C), pH 4.5-8.0 (optimum, pH 7.0) and with 0-4% (w/v) NaCl (optimum, 0-2 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain M0104T was closely related to Roseomonas deserti JCM 31275T (96.2 %), Roseomonas vastitatis KCTC 62043T (96.0 %), Roseomonas aerofrigidensis JCM 31878T (95.9 %) and Roseomonas oryzae KCTC 42542T (95.7 %). The strain had an assembly size of 5.0 Mb and a G+C content of 71.0mol%. Genes involved in copper, cadmium, lead, arsenic and zinc resistance were identified in the genome of strain M0104T. The digital DNA-DNA hybridization and average nucleotide identity values between the genome sequence of strain M0104T and those of closely related type strains were 19.4-24.9 % and 74.3-81.8 %, respectively. Strain M0104T contained C18:1 ω7c, C18:3 ω3c, anteiso C11:0 and C16:0 as the major fatty acids (>7 %) and ubiquinone Q-10 as the sole isoprenoid quinone. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine were its major polar lipids. Based on its phenotypic, phylogenetic and chemotaxonomic properties, strain M0104T is proposed to represent a novel species within the genus Roseomonas, for which the name Roseomonas coralli sp. nov. is proposed. The type strain is M0104T (=KCTC 62359T=MCCC 1K03632T).

Temporal variability of free-living microbial culturability and community composition after an Akashiwo sanguinea bloom in Shenzhen, China.

Dinoflagellate blooms currently caused serious environmental problems in different areas of the world. Recent studies revealed close relationship between dinoflagellate blooms and microbial community dynamics, while less attention has been paid on the bacterial culturability change associated with the bloom. Here, we investigated the temporal variation of microbial community composition and culturability during the decline stage of an Akashiwo sanguinea bloom occurred in Shenzhen, China. The daily microbial community phylogenetic structures in water samples collected during a four-day period after the bloom peak were assessed through 16S rRNA gene amplicons sequencing on the MiSeq (Illumina) platform. The environmental parameters, Chlorophyll a concentrations, and total viable and culturable bacterial densities were also measured. Our results showed that Gamma-proteobacteria comprising mostly of Pseudoalteromonadaceae and Vibrionaceae was the predominant microbial class in the post-bloom samples, except for the second day. During that day, the represented groups switched to Alpha-proteobacteria (Rhizobiales) and Beta-proteobacteria (Comamonadaceae), with the microbial culturability decreased. Total viable bacterial densities reached the maximum value on the third day, with Gamma-proteobacteria regained the dominance till the fourth day. The dramatic microbial community succession and culturability variation observed in this study indicated the complication of algae-bacteria interactions during dinoflagellate bloom.

Proteome analysis provides insights into sex differences in Holothuria Scabra.

Sex-determining mechanism is still ambiguous for sea cucumber Holothuria scabra which only manifests gonochorism in gonad. In this study, proteomic analysis was employed to delineate sex-related proteins and genes in gonads of H. scabra, subsequently validated through Quantitative real-time polymerase chain reaction (qRT-PCR). A total of 5,313 proteins were identified via proteome sequencing. Among these, 817 proteins exhibited expression in both the ovary and testis, with 445 proteins displaying up-regulation and 372 proteins showing down-regulation (ovary vs testis). Furthermore, 136 and 69 proteins were identified as ovary-specific and testis-specific Differentially Abundant Proteins (DAPs), respectively. And 9 DAP coding genes which play crucial role in ovary and testis were verified by qRT-PCR. Notably, 24 ovary-bias proteins enriched in ribosome pathway strongly indicated the crucial role of ribosome in ovary. This study serves to furnish novel evidence pertaining to sex differences in H. scabra.

Applications of Environmental DNA (eDNA) in Monitoring the Endangered Status and Evaluating the Stock Enhancement Effect of Tropical Sea Cucumber Holothuria Scabra.

The tropical sea cucumber Holothuria scabra is naturally found in the Indo-West Pacific. However, due to their commercial value, natural H. scabra populations have declined significantly in recent years, resulting in its status as an endangered species. Surveys of H. scabra resource pose a challenge due to its specific characteristics, such as sand-burrowing behavior. To overcome this problem, our study established a convenient and feasible method for assessing H. scabra resources using environmental DNA (eDNA) monitoring technology. First, H. scabra-specific TaqMan primers and probe were designed based on its cox1 gene, followed by the development of an eDNA monitoring method for H. scabra in two separate sea areas (Xuwen and Daya Bay). The method was subsequently employed to investigate the distribution of H. scabra and assess the effects of aquaculture stock enhancement through juvenile releasing in the Weizhou Island sea area. The H. scabra eDNA monitoring approach was found to be more appropriate and credible than traditional methods, and a positive impact of stocking on H. scabra populations was observed. In summary, this is the first report to quantify eDNA concentration in a Holothuroidea species, and it provides a convenient and accurate method for surveying H. scabra resources. This study introduces novel concepts for eDNA-based detection of endangered marine benthic animals and monitoring their population distribution and abundance.

Occurrence and Succession of Bacterial Community in O3/BAC Process of Drinking Water Treatment.

In the drinking water industry, a common advanced treatment process is comprised of treatment with ozone, followed by biological-activated carbon (O3/BAC). However, the bacterial community formation and succession procedures associated with activated carbon have rarely been reported. In this study, the dynamics of bacterial communities at three different depths were investigated using a pilot-scale O3/BAC filter. The average chemical oxygen demand (CODMn), turbidity removal and dissolved oxygen (DO) consumption rate of the filter were 26.43%, 16.57% and 16.4% during the operation period, respectively. Bacterial communities dominated by proteobacteria and Bacteroidetes attached on activated carbon were determined by polymerase chain reaction-density gradient gel electrophoresis (PCR-DGGE). Principal component analysis (PCA) revealed that the compositions and structures of bacterial communities in different layers clustered after fluctuation. A redundancy analysis (RDA) indicated that Ramlibacter henchirensis was positively correlated to chemical oxygen demand (CODMn) removal and nitrate-N removal, and Georgfuchsia toluolica also showed a positive correlation with CODMn removal. Aquabacterium parvum and Phaeobacterium nitratireducens were positively-correlated with turbidity removal. Pedobacter glucosidilyticus and Pseudomonas sp. were associated with high dissolved oxygen (DO) consumption. These results provide insight into the succession characteristics of the bacterial community of O3/BAC treatment and the interactions of the bacterial community with filter operation performance.