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Many aquatic invertebrates undergo an indirect development, a biphasic life cycle which encompasses the transformation of free-swimming larvae into benthic juveniles via settlement and metamorphosis. During this transition, metamorphic competence is a crucial developmental stage that allows larvae to swim and feed in the planktonic realm while retaining the ability to settle and metamorphose in response to environmental cues. Although there have been substantial efforts to decipher the molecular mechanisms underlying this event in several molluscan species, the conserved biological pathways that are crucial to enable this transition across species are not well understood. Here, we performed a comparative analysis of the developmental transcriptomes between bivalve Crassostrea gigas and gastropod Rapana venosa. We particularly explored the common gene expression signatures that may underlie their larval competence. We showed that, although the developmental transcriptomes differed remarkably between C. gigas and R. venosa, they likely shared a plethora of genes (n = 690) that exhibited similar expression signatures during their larval competence. Gene Ontology enrichment and expression analyses further indicated that competent larvae of both species exhibited up-regulation of pathways associated with response to stimuli, metal ion binding and transport, and neuronal development, but showed down-regulation of pathways that were mainly involved in cilium assembly and organ development. Using oyster and whelk as models, our study suggests that regulation of these conserved pathways is crucial for their subsequent settlement and metamorphosis and may represent a universal mechanism that enables the pelagic-to-benthic transition in a broader range of marine invertebrates.

The Fujian oyster, Crassostrea angulata, accounts for approximately 50% of the total oyster production in China and is one of the most economically important marine products. In this study, we investigated differential gene expression profiles between diploid (n = 2) and triploid (n = 3) oysters that may indicate the specific adaptation associated with ploidy. A total of 14,626,126 and 15,492,551 reads were generated from diploid and triploid oyster muscle transcriptomes using Illumina RNA‐Seq respectively. Gene expression analysis revealed a total of 2,045 differentially expressed genes between 2n and 3n individuals, from which 814 genes were significantly up‐regulated in the 2n transcriptome while 1,231 were down‐regulated. In addition, 24 differentially expressed genes (DEGs) were uniquely expressed in 2n individuals while 28 DEGs were uniquely expressed in 3n individuals. Furthermore, our pathway analysis suggested that the DEGs up‐regulated in 2n oysters were enriched in the pathways related to normal growth, development and reproduction, whereas DEGs up‐regulated in 3n individuals may be involved in faster growth and metabolism. Finally, we validated the expression levels of 15 genes using quantitative real‐time PCR (qRT‐PCR), and 14 out of 15 genes showed consistent expression patterns with RNA‐Seq data. This study provides an important foundation for further investigations on distinct gene expression patterns and signalling pathways that differ between diploid and triploid oysters.

With the ability to cross placental barriers in their hosts, strains of Gram-positive Enterococcus faecalis can exhibit either beneficial or harmful properties. However, the mechanisms underlying these effects have yet to be determined. A comparative transcriptomic analysis of human placental trophoblasts in response to pathogenic or probiotic E. faecalis was performed in order to investigate the molecular basis of different traits. Results indicated that both E. faecalis Symbioflor 1 and V583 could pass through the placental barrier in vitro with similar levels of invasion ability. In total, 2353 (1369 upregulated and 984 downregulated) and 2351 (1233 upregulated and 1118 downregulated) DEGs were identified in Symbioflor 1 and V583, respectively. Furthermore, 1074 (671 upregulated and 403 downregulated) and 1072 (535 upregulated and 537 downregulated) DEGs were only identified in Symbioflor 1 and V583 treatment groups, respectively. KEGG analysis showed that 6 and 9 signaling pathways were associated with interactions between Symbioflor 1 and V583. GO analysis revealed that these DEGs were mainly related to cellular and metabolic processes and biological regulation. However, 28 and 44 DEGs were classified into terms associated with placental and embryonic development in Symbioflor 1 and V583 treatment groups, respectively. Notably, 9 and 25 unique DEGs were identified only in Symbioflor 1 and V583 treatment groups, respectively. A large proportion of transcriptional responses differed when compared between pathogenic and probiotic E. faecalis interaction, and several unique DEGs and signal pathways were identified in the two different groups. These data enhance our understanding of how different traits can be affected by pathogenic and probiotic E. faecalis and the mechanisms underlying these effects.

Diabetes is a complex and heterogeneous disorder disease with elevated blood glucose, which is one of the most serious global public health problems. Cereals and pseudocereals, as staple food, are major sources of dietary protein. Cereal and pseudocereal proteins are potential sources of food-derived bioactive peptides and proposed to prevent and ameliorate diabetes. According to recent researches, this review summaries the isolation, purification and analysis of anti-diabetic protein hydrolysates and peptides from cereals and pseudocereals. In addition, their anti-diabetic activities and mechanisms were reviewed by in vitro inhibition of carbohydrate digestive enzyme and dipeptidyl peptidase-IV, in vivo hypoglycaemic effects, and glucose homeostasis in cell model.

Increasing evidence suggests that Enterococcus faecalis strains can pass through placental barriers and cause adverse outcomes during pregnancy. However, the underlying molecular mechanism of the interaction between E. faecalis and the host placental barrier has yet to be fully elucidated. In this study, we have used DNA microarray analysis to investigate the response of human placental trophoblast-like BeWo cells to infection with E. faecalis OG1RF. These results indicate that a total of 2191 genes in BeWo cells are differentially expressed in the presence of E. faecalis OG1RF, with 1357 genes being upregulated and 834 genes being downregulated. These differentially expressed genes (DEGs) are involved in apoptosis, stress and stimulus response, placental and embryonic development, immune response, and cell adhesion. Therefore, these results provide information on the molecular mechanisms that E. faecalis invasion can trigger to cause adverse pregnancy outcomes.

This study focuses on the impact of actin on adhesion and translocation of Enterococcus (E.) faecalis OG1RF, E. faecalis Symbioflor(®), and E. faecalis V583. Insight into the role of actin aggregation in the mediation of bacterial adhesion and translocation was provided by a two-chamber translocation assay, which employed Ptk6 cells. Determination of translocation rates, cytochalasin D treatment, and laser scanning confocal microscopic observation revealed actin as a predominant brace for enterococci to pass through the epithelial cell layer. As the three enterococci had moderate adhesion ability to actin, actin-binding proteins were isolated and characterized by LC-MS/MS. The isolated proteins were identified as pyruvate formate lyase, enolase, glyceraldehyde-3-phosphate dehydrogenase, and GroEL. All these proteins belong to two major groups of moonlighting proteins, i.e., proteins, which display additional functions other than their described major biochemical catalysis. Both groups of moonlight proteins were determined to be associated with epithelial cell binding.

BACKGROUND Probiotics are widely used in the food industry and medicine fields in China, but few studies have been conducted to evaluate the actual microbial amounts and species in probiotic products, which may conflict with the labels and mislead consumers to choose inappropriate foods or medicines. RESULTS Twenty commercial dairy products and eight commercial ‘healthcare’ samples were collected from markets in China and tested using culture-dependent and culture-independent methods. The results suggested that the total bacterial counts of most commercial products met the minimum quantitative requirement of the Chinese national standard (6.00 log colony-forming units g−1). However, the bacterial counts of specific species were inconsistent with the labelling. In parallel, denaturing gradient gel electrophoresis analysis indicated that some probiotic-containing products were wrongly labelled; no Bifidobacterium species were detected in the products claiming to contain bifidobacteria, and the probiotic characteristics (antimicrobial activity, acid resistance and bile resistance) of some isolates had degraded. Moreover, some contaminating bacteria, e.g. Enterobacter sp., Klebsiella sp. and Serratia sp., were also detected in these products. CONCLUSION The combination of culture-dependent and culture-independent methods was proven to quickly and conveniently detect the microbial diversity in probiotic products, and more effort is required to regulate the probiotic market in China. © 2013 Society of Chemical Industry

We report our investigation of the functions of PagN in Salmonella pathogenesis and its potential as a vaccine candidate. Further investigation conducted in this study indicates that the outer membrane protein PagN is important for Salmonella adhesion/invasion of epithelial cells as well as bacterial virulence. When pagN was deleted from Salmonella enterica serovar Typhimurium (S. Typhimurium), the adhesion and invasion of HT-29 epithelial cells was significantly decreased compared with the wild type strain. Mice infected with the pagN mutant strain exhibited less pathological signs in the intestine and survived longer than the wild-type-infected mice. PagN is widely distributed and conserved among clinical isolates of different Salmonella serovars, making PagN a potential vaccine candidate for Salmonella infection. To elucidate the potential of PagN as a vaccine, we expressed and purified recombinant PagN (rPagN). When rPagN was tested in mice, it provided significant protection against Salmonella infection in vivo. In vitro, anti-PagN serum enhanced clearance of Salmonella, indicating a contribution of PagN-specific antibodies to the killing process. This correlates well with the observed protection of mice immunized with rPagN. Our preliminary results indicate more functions of PagN in S. Typhimurium virulence as well as its potential as a protective vaccine.

Enterococcus faecium YF5, a strain previously isolated from sourdough, was assessed for safety and probiotic potential. Its virulence and antibiotic resistant phenotypes (cytolysin and gelatinase production, antibiotic susceptibility) and genes (cylA, gelE, ace, agg, esp, and vanA) were surveyed. Results indicated that the tested virulence determinants were nontoxic. In addition, E. faecium YF5 was sensitive to 3 antibiotics such as amoxicillin, vancomycin, and chloramphenicol. Furthermore, results of in vivo animal acute oral toxicity of E. faecium YF5 studies were similar to the control group that indicated no abnormalities. In addition, E. faecium YF5 stably survived in low pH, bile salts, gastric, and intestinal fluids in vitro. Moreover, E. faecium YF5 was found to adhere to human colon cancer cell line HT-29 at 3.39 (±0.67) × 10(5) CFU/mL. When cocultured with pathogenic organisms (Enterobacter sakazakii CMCC45402, Escherichia coli CMCC44102, enterohemorrhage Escherichia coli O157: H7 CMCC44828, Salmonella Typhimurium CMCC50071, Shigella flexneri 301, and Shigella sonnei ATCC 29930) and 2 gram-positive strains (Listeria monocytogenes CMCC54001 and Staphylococcus aureus CMCC 26003), it inhibited these foodborne pathogens with exception of S. aureus. Therefore, E. faecium YF5 can be regarded as a safe strain and it may be used as a probiotic preparation or for microecologics.

Bifidobacterium is well known to have an inhibitory effect on the survival, growth, and proliferation of various foodborne pathogens, but the mechanism of the molecular action of B. longum in blocking the invasion of Listeria monocytogenes is not yet well defined. In the present study, following RNA extraction and cDNA synthesis, differential expression of virulence and stress fitness genes in L. monocytogenes and B. longum was determined by real-time PCR. The results indicate that L. monocytogenes virulence factors, including actA, hly, inlA, and plcA, showed significantly downregulated expression during co-incubation of B. longum and L. monocytogenes in phosphate-buffered saline. The relative mRNA levels of oppA and serpin, two stress fitness genes in B. longum, were significantly higher than for the control group. These results indicate that downregulation of L. monocytogenes virulence factors during co-incubation with B. longum might be responsible for the inhibitory effects.

Pregnant mothers are susceptible to bacterial infections, which may compromise the health of mothers and offspring. Enterococcus faecalis is a ubiquitous species found in food, restaurants, and hospitals where pregnant woman frequently become exposed to this bacterium. However, the survival, distribution, translocation, and corresponding influence of E. faecalis have not been investigated during the pregnancy period, when the mother and fetus are susceptible to bacterial infection. In this study, a fluorescing E. faecalis strain was used to track the fate of the bacterium in pregnant mice. Orally administered E. faecalis were found to survive and disseminate to all regions of the intestinal tract. It also altered the bacterial community structure by significantly decreasing the diversity of Lactobacillus species, impairing the normal structure and function of the intestinal barrier, which may contribute to the bacterial translocation into the blood, spleen, placenta, and fetus. This may affect fetal and placental growth and development.

Enterococcus faecium YF5, a strain previously isolated from sourdough, was assessed for safety and probiotic potential. Its virulence and antibiotic resistant phenotypes (cytolysin and gelatinase production, antibiotic susceptibility) and genes (cylA, gelE, ace, agg, esp, and vanA) were surveyed. Results indicated that the tested virulence determinants were nontoxic. In addition, E. faecium YF5 was sensitive to 3 antibiotics such as amoxicillin, vancomycin, and chloramphenicol. Furthermore, results of in vivo animal acute oral toxicity of E. faecium YF5 studies were similar to the control group that indicated no abnormalities. In addition, E. faecium YF5 stably survived in low pH, bile salts, gastric, and intestinal fluids in vitro. Moreover, E. faecium YF5 was found to adhere to human colon cancer cell line HT-29 at 3.39 (±0.67) × 10(5) CFU/mL. When cocultured with pathogenic organisms (Enterobacter sakazakii CMCC45402, Escherichia coli CMCC44102, enterohemorrhage Escherichia coli O157: H7 CMCC44828, Salmonella Typhimurium CMCC50071, Shigella flexneri 301, and Shigella sonnei ATCC 29930) and 2 gram-positive strains (Listeria monocytogenes CMCC54001 and Staphylococcus aureus CMCC 26003), it inhibited these foodborne pathogens with exception of S. aureus. Therefore, E. faecium YF5 can be regarded as a safe strain and it may be used as a probiotic preparation or for microecologics.

Probiotics are widely used in the food industry and medicine fields in China, but few studies have been conducted to evaluate the actual microbial amounts and species in probiotic products, which may conflict with the labels and mislead consumers to choose inappropriate foods or medicines.Twenty commercial dairy products and eight commercial 'healthcare' samples were collected from markets in China and tested using culture-dependent and culture-independent methods. The results suggested that the total bacterial counts of most commercial products met the minimum quantitative requirement of the Chinese national standard (6.00 log colony-forming units g(-1) ). However, the bacterial counts of specific species were inconsistent with the labelling. In parallel, denaturing gradient gel electrophoresis analysis indicated that some probiotic-containing products were wrongly labelled; no Bifidobacterium species were detected in the products claiming to contain bifidobacteria, and the probiotic characteristics (antimicrobial activity, acid resistance and bile resistance) of some isolates had degraded. Moreover, some contaminating bacteria, e.g. Enterobacter sp., Klebsiella sp. and Serratia sp., were also detected in these products.The combination of culture-dependent and culture-independent methods was proven to quickly and conveniently detect the microbial diversity in probiotic products, and more effort is required to regulate the probiotic market in China.

Viili, also known as viilia, is a traditional fermented dairy product, which is popular in Finland. However, little research has been conducted on organisms’ isolation and their interaction during milk fermentation. In this study, culture-dependent and independent methods had been used to identify isolates. Also, their synergistic effects on milk curd and exopolysaccharides (EPSs) yield was evaluated. When Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus paracasei, Bacillus cereus and Lactobacillus delbrueckii were successfully separated and screened from viili by using the combination of conventional microbiological cultivation with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), they were individually inoculated into sterilized skimmed milk or combined as co-cultures to determine the curd time and the yield of EPSs. Results show that L. delbrueckii presented the strongest curding capability at 5 h and combination of L. paracasei, B. cereus and L. plantarum brought the highest yields of EPSs (186.71 mg/L). Moreover, it suggested that the synergistic effects among the isolates had shortened the curding time and increased the production of EPSs. Key words : Viili, PCR-DGGE, exopolysaccharides, lactic acid bacteria.