Ser Gene Research Articles

Combined effects of pentachlorophenol and nano-TiO2 with different sizes on antioxidant, digestive, and immune responses of the swimming crab Portunus trituberculatus

Marine nano-titanium dioxide (nano-TiO2) and pentachlorophenol (PCP) pollution are escalating concerns in coastal areas. This study investigated the combined effects of continuous exposure to nano-TiO2 (25 nm, 100 nm) and PCP (0, 1, 10 μg/L) for 28 days on the antioxidant, digestive, and immune abilities of the swimming crab Portunus trituberculatus. Compared with the control group, the interaction between nano-TiO2 and PCP was significantly higher than exposure to a single stressor, with a pronounced decrease in amylase activity observed due to the reducing nano-TiO2 particle sizes. Resulting in increased MDA and SOD activity. The expression levels of Toll4, CSP3, and SER genes in crab hemolymph showed perturbations following exposure to nano-TiO2 and PCP. In summary, according to the results of CAT, GPX, PES and AMS enzyme activities, it was concluded that compared to the larger particle size (100 nm), the single stress of nano-TiO2 at a smaller particle size (25 nm) and co-stress with PCP have more significant impacts on P. trituberculatus. However, the potential physiological regulation mechanism of the interaction between these pollutants remains elusive and requires further study.

Identifications of three novel alleles of Serrate in Drosophila

The Notch signaling pathway, an evolutionarily highly conserved pathway, participates in various essential physiological processes in organisms. Activation of Notch signaling in the canonical manner requires the combination of ligand and receptor. There are two ligands of Notch in Drosophila: Delta (Dl) and Serrate (Ser). A mutation mf157 is identified for causing nicks of fly wings in genetic analysis from a mutant library (unpublished) that was established previously. Immunofluorescent staining illustrates that mf157 represses the expression of Cut and Wingless (Wg), the targets of Notch signaling. MARCM cloning analysis reveals that mf157 functions at the same level or the upstream of ligands of Notch in signaling sending cells. Sequencing demonstrates that mf157 is a novel allele of the Ser gene. Subsequently, mf553 and mf167 are also identified as new alleles of Ser from our library. Furthermore, the complementary assays and the examination of transcripts confirm the sequencing results. Besides, the repressed phenotypes of Notch signaling were reverted by transposon excision experiments of mf157. In conclusion, we identify three fresh alleles of Ser. Our works supply additional genetic resources for further study of functions of Ser and Notch signaling regulation.

Detection of New Staphylococcal Enterotoxin Encoding Genes in Staphylococcus aureus Isolated from Animals and Humans in Yogyakarta

Staphylococcal enterotoxins (SE) are essential in human and animal infection and food poisoning. This study analyzed ten genes (sek, sel, sem, sen, seo, sep, seq, ser, ses, and set) encoding new staphylococcal enterotoxin isolated from animals and humans by multiplex polymerase chain reaction (PCR). In Yogyakarta, Indonesia, samples from human infection cases (174 isolates), samples from cattle (5 isolates), and samples from goats (5 isolates) resulted in a total of 183 Staphylococcus aureus isolates.. All isolates were confirmed to be Staphylococcus aureus based on bacterial culture and biochemistry as well as identification of 23S rRNA. The sel gene was most often observed in Staphylococcus aureus isolates from goats (4 isolates, 80%), followed by the 20% sek gene. Isolates Staphylococcus aureus from cattle, the sel gene was most often found 44% (4 isolates), followed by sek gene 22%, sep gene 22% and ser gene 11%. Staphylococcus aureus isolates from humans were found with the most sem genes 22% (38 isolates), followed by 21% sel genes, 14% sek genes, 13% sep genes, 8% sen genes, and 2% ser genes. Staphylococcus aureus isolates from goats and cattle most frequently included the sel gene, whereas those from humans contained the sem gene. Detecting a new type of SE among animals and humans indicates a public health threat due to SE infection. The occurrence of this new type of SE might be used as an approach for controlling infections and food poisoning diseases.

Diversity and Evolution of DNA Transposons Targeting Multicopy Small RNA Genes from Actinopterygian Fish.

Simple SummaryDNA transposons are parasitic DNA segments that can move or duplicate themselves from one site to another in the genome. Dada is a unique group of DNA transposons, which specifically insert themselves into multicopy RNA genes such as transfer RNA (tRNA) genes or small nuclear RNA (snRNA) genes to avoid the disruption of single-copy functional genes. However, only a few Dada families have been characterized along with their target sequences. Here, vertebrate genomes were surveyed to characterize new Dada transposons, and over 120 Dada families were characterized from diverse fishes. They were classified into 12 groups with confirmed target specificities. Various tRNA genes, as well as 5S ribosomal RNA (rRNA) genes were inserted by Dada transposons. Phylogenetic analysis revealed that Dada transposons inserted in the same RNA genes are closely related. Phylogenetically related Dada transposons inserted in different RNA genes show the sequence similarity around their insertion sites, indicating Dada proteins recognize DNA nucleotide sequences to find their targets. Understanding how Dada discovers the targets would help develop target-specific insertions of foreign DNA segments.Dada is a unique superfamily of DNA transposons, inserted specifically in multicopy RNA genes. The zebrafish genome harbors five families of Dada transposons, whose targets are U6 and U1 snRNA genes, and tRNA-Ala and tRNA-Leu genes. Dada-U6, which is inserted specifically in U6 snRNA genes, is found in four animal phyla, but other target-specific lineages have been reported only from one or two species. Here, vertebrate genomes and transcriptomes were surveyed to characterize Dada families with new target specificities, and over 120 Dada families were characterized from the genomes of actinopterygian fish. They were classified into 12 groups with confirmed target specificities. Newly characterized Dada families target tRNA genes for Asp, Asn, Arg, Gly, Lys, Ser, Tyr, and Val, and 5S rRNA genes. Targeted positions inside of tRNA genes are concentrated in two regions: around the anticodon and the A box of RNA polymerase III promoter. Phylogenetic analysis revealed the relationships among actinopterygian Dada families, and one domestication event in the common ancestor of carps and minnows belonging to Cyprinoidei, Cypriniformes. Sequences targeted by phylogenetically related Dada families show sequence similarities, indicating that the target specificity of Dada is accomplished through the recognition of primary nucleotide sequences.

Experimental co‐infection by Aeromonas hydrophila and Aeromonas jandaei in pirarucu Arapaima gigas (Pisces: Arapaimidae)

In fish, bacteriosis has been widely linked with Aeromonas species, but co-infection by these bacteria has been little addressed. The aims of this study were to report on an outbreak of disease in pirarucu Arapaima gigas caused by Aeromonas and to investigate experimental co-infection and characterize resistance profile, virulence factors and phenotypic and molecular differentiation. Fish samples with clinical signs of bacteriosis were collected and used to study experimental co-infection. The bacterial isolates were characterized phenotypically as Aeromonas hydrophila and Aeromonas jandaei. Virulence genes aerA, gcat, lip, dnase and hlyA were detected using the polymerase chain reaction, while the alt, act and ser genes were not found. Resistance to imipenem and ceftriaxone was observed; however, all isolates were susceptible to most of the antibiotics assayed. Phenotypic tests to determine the presence of metallo-β-lactamases showed positivity only for A. jandaei strains. Assays for the resistance genes kpc, ndm, imp, oxa-48 and vim showed negative results. The co-infection and pathogenicity of A. hydrophila in association with A. jandaei in A. gigas, established in accordance with Koch's postulate, provided experimental support for the existence of synergism between these bacteria. This has several implications relating to occurrences of this co-infection and determinants of virulence.

Characteristics of Staphylococcus aureus Isolated from a Case of Foodborne Outbreak in Bulgaria

Abstract This paper presents an outbreak provoked by methicillin-resistant strains of coagulase-positive S. aureus (CPS), produced staphylococcal enterotoxins (se) in pig meatballs and potato salad consumed from 70 people in the village Mamarchevo, Bulgaria. Eighteen women aged 50 to 70 years, and two children aged 4 and 5 years have demonstrated a severe malaise with vomiting and indigestion. Two food samples and isolates of CPS were received in the laboratory of Bulgarian Food Safety Agency. Both samples were found to have a high level of CPS. The level of S. aureus contamination in the potato salad was 8.3 logs CFU/g and 7.7 logs CFU/g in roasted meatballs, which was a significant reason to doubt the production of the toxin. The samples were analyzed according to the European Screening Method v5 using mini VIDAS SET2. The results showed a presence of staphylococcal enterotoxin (TV 2.67 for meatballs and TV 3.27 for potato salad), which was the reason for the ensuing food intoxication. EURL CPS applying quantitative indirect sandwich-type ELISA confirmed the presence of sea, sec and sed in the potato salad and sea and sed in the roasted meatballs. Two CPS isolates were confirmed as S. aureus by a species-specific 23S rRNA targeted PCR test. Real-time PCR method detected sea, sed, seg, sei, sej, and ser genes in S. aureus strains, found in both matrixes. Multiplex PCR method proved the existence of the mecA gene in both S. aureus strains. Resistance to cefoxitin (>16 mg/L), penicillin (>2 mg/L), kanamycin (64 mg/L) and sulfamethoxazole (>512 mg/L) was found.

Low penetrance of hearing loss in two Chinese families carrying the mitochondrial tRNASer(UCN) mutations.

Mutations in mitochondrial DNA (mtDNA), especially in mitochondrial 12S rRNA and transfer RNA(tRNA)Ser(UCN) genes, are important causes of non-syndromic hearing loss. However, the molecular mechanism underlying mt-tRNA mutations in clinical hearing impairment are not fully understood. The present study assessed the molecular characterization of two Chinese families with non-syndromic hearing loss, who both exhibited very low penetrance of deafness (9.1 and 12.5% for Family 1 and 2, respectively). Mutational analysis of the complete mtDNA genes identified the presence of cytochrome c oxidase 1/tRNASer(UCN) G7444A and tRNASer(UCN) C7492T mutations, together with polymorphisms belonging to human mitochondrial haplogroup D4 and G2b, respectively. Moreover, the G7444A and C7492T mutations occurred at highly conserved tRNASer(UCN) nucleotides and may cause tRNA metabolism failure, which is involved in mitochondrial translation defects. Therefore, the G7444A and C7492T mutations may lead to the mitochondrial dysfunction that responsible for deafness. However, the absence of any functional variants in Gap junction β-2, Solute Carrier Family 26 Member 4 and TRNA 5-methylaminomethyl-2-thiouridylate methyltransferase suggested that nuclear genes may not play active roles in the occurrence of deafness. In the present study, the observed incomplete penetrance of hearing loss and mild mitochondrial dysfunction indicated that mtDNA G7444A and C7492T mutations are insufficient to produce the deafness phenotype. Therefore, other risk factors such as environmental factors and epigenetic regulation may be involved in the pathogenesis of hearing loss in the families recruited in the present study.

Novel insights into the enterotoxigenic potential and genomic background of Staphylococcus aureus isolated from raw milk

In this study, 53 Staphylococcus (S.) aureus strains were typed by 16S–23S rDNA intergenic spacer region (ISR) typing and staphylococcal enterotoxin gene (SEg) typing for all the staphylococcal enterotoxin (se) and staphylococcal enterotoxin-like toxin (sel) genes known to date, revealing a higher discriminatory power than that of multi locus sequence typing. Six strains, one of each ISR- and SEg-type, were genome sequenced and the ability to produce some classical and new SEs when growing in milk was investigated.The manual analysis of the six genomes allowed us to confirm, correct and expand the results of common available genomic data pipelines such as VirulenceFinder. Moreover, it enabled us to (i) investigate the actual location of se and sel genes, even for genes such as selY, whose location (in the core genome) was so far unknown, (ii) find novel allelic variants of se and sel genes and pseudogenes, (iii) correctly annotate se and sel genes and pseudogenes, and (iv) discover a novel type of enterotoxin gene cluster (egc), i.e. the egc type 5 in strains 356P and 364P, while S. argenteus MSHR1132 harbored the egc type 6.Four of the six S. aureus strains produced sufficient amounts of SEA, SEC, SED and SEH in milk to cause staphylococcal food poisoning (SFP), with S. aureus 372 P being the highest producer of SED in milk found to date, producing as much as ca. 47,300 ng/mL and 49,200 ng/mL of SED, after 24 and 48 h of incubation in milk at 37 °C, respectively. S. aureus 372 P released a low amount of SER in milk, most likely because the seR gene was present as a pseudogene, putatively encoding only 51 amino acids. These findings confirm that not only the classical SEs, but also the new ones can represent a potential hazard for the consumers’ health if produced in foods in sufficient amounts. Therefore, the detection of SEs in foods, especially if involved in SFP cases, should focus not only on classical, but also on all the new SEs and SEls known to date. Where reference methods are unavailable, the presence of the relevant genes, by using the conventional and real time PCR protocols we exhaustively provided herein, and their nucleotide sequences, should be investigated.

Characterization of A Staphylococcal Food Poisoning Outbreak in A Workplace Canteen during the Post-Earthquake Reconstruction of Central Italy.

In summer 2017, a foodborne outbreak occurred in Central Italy, involving 26 workers employed in the post-earthquake reconstruction. After eating a meal provided by a catering service, they manifested gastrointestinal symptoms; 23 of them were hospitalized. The retrospective cohort study indicated the pasta salad as the most likely vehicle of poisoning. Foods, environmental samples, and food handlers’ nasal swabs were collected. Bacillus cereus (Bc) and coagulase-positive staphylococci (CPS) including S. aureus, together with their toxins, were the targets of the analysis. CPS, detected in all the leftovers, exceeded 105 CFU/g in the pasta salad, in which we found Staphylococcal Enterotoxins (SEs) (0.033 ng SEA/g; 0.052 ng SED/g). None of the environmental and human swabs showed contamination. We characterized 23 S. aureus from foods. They all belonged to the human biotype, showed the same toxigenic profile (sea, sed, sej, and ser genes), and had the same Pulsed Field Gel Electrophoresis (PFGE) pattern; none of them harbored mecA or mupA genes. We also detected Bc contamination in the pasta salad but none of the isolates harbored the ces gene for the emetic toxin cereulide. The EU Reference Laboratory for CPS confirmed the case as a strong-evidence outbreak caused by the ingestion of SEs produced by a single strain of S. aureus carried by the same human source. This outbreak was successfully investigated despite the emergency situation in which it occurred.

Prevalence and Characterization of Staphylococcus aureus Isolated From Retail Vegetables in China.

Staphylococcus aureus is a pathogen associated with serious community and hospital-acquired diseases. The aim of this study was to investigate the prevalence of S. aureus from retail vegetables in China and then characterized S. aureus isolates by antibiotic resistance, staphylococcal enterotoxin genes, spa-typing and multi-locus sequence typing. Of 419 retail vegetable samples from 39 cities in China during 2011–2016, 24 (5.73%) samples were positive for S. aureus and the geometric mean was 3.85 MPN/g. The prevalence of S. aureus was highest in lettuce (13/84, 15.48%) followed by tomato (7/110, 6.36%), caraway (2/87, 2.30%), and cucumber (2/128, 1.56%), whereas other vegetables were free of S. aureus. A total of 30 isolates were analyzed. For antibiotics susceptibility test, most isolates (93.3%) were resistant to ampicillin and penicillin, whereas all isolates were susceptible to linezolid, trimethoprim/sulphamethoxazole 1:19, nitrofurantoin, rifampicin, and teicoplanin. All isolates (30/30, 100%) were resistant or intermediate resistant to more than three tested antibiotics, including 9 isolates (30%) were resisted more than 10 antibiotics. Five isolates were resistant to cefoxitin and carried mecA genes which confirmed as MRSA. Of the 18 investigated SE genes, the sem gene was the most frequently detected (86.7%) followed by the sec (83.3%), sep (70.0%), seg (56.7%), sel (53.3%), seh (50.0%), seq (50.0%), sej (46.7%), seb (36.7%), sen (36.7%), and ser (33.3%) genes were harbored by more than one third of the isolates, whereas the seo and seu were detected in only 6.75% of the isolates. MLST and spa typing observed high genetic diversity in S. aureus isolated from retail vegetable in China. ST59-t437 was the predominant types (3/5, 60%) of MRSA isolates, whereas ST188-t189 was the predominant types (7/25, 28%) of MSSA isolates. Our study reflects that the retail vegetable in China could be contaminated with S. aureus but the levels of S. aureus were not very excessive. In addition, these isolates had virulence potential, most of them were enterotoxigenic and multiple antimicrobial resistance, should be draw public attention. These data have signification implications for epidemiological and public health studies of this pathogen.

Staphylococcal Enterotoxin Type R Pseudogene Presence in Staphylococcus aureus Reference and Outbreak Strains.

Novel staphylococcal enterotoxins (SEs) expressed by Staphylococcus aureus strains have been described throughout the years, among these being the SE protein SER. To further characterize this toxin, this research used 13 S. aureus strains previously determined to contain the SE type R (ser) gene. These S. aureus isolates were evaluated using serological assays for identification of SEA-SEE and PCR for the detection of newly described SE and SE-like enterotoxin genes seg-seu. PCR-based cloning was performed such that the ser gene could be ligated into the pTrc99A plasmid expression vector. Ligation products were used to transform Escherichia coli (DH10Br) strains so that the ser open reading frame (ORF) could be sequenced and expressed for further characterization. Four of the 13 S. aureus strains tested harbored a ser ORF that yielded a PCR-positive result, but contained a frameshift mutation that subsequently introduced a premature stop codon abrogating expression of a full-sized functional protein. In this study, 30% of the PCR-positive ser strains tested were found to carry genes that coded for a nonfunctional SER protein, a finding that clearly illustrates the limited effectiveness of PCR for reliably evaluating enterotoxin potential for ser and, perhaps, other enterotoxin types.

Полиморфизм тРНКLeu и тРНКSer митохондриальной ДНК свиней различных пород

Analysis of the sequence of mitochondrial DNA (mtDNA), which has a maternal nature of inheritance, is an effective way of assessing the individual characteristics of commercial lines. The analysis of the sequence variability of the mtDNA tRNA Ser and tRNA Leu genes in different pig breeds was carried out. The mtDNA tRNA Leu1 , tRNA Leu2 , tRNA Ser1 , tRNA Ser2 genes were chosen as the study objects. For the study of the sequences, data on pigs of different breeds were selected from the National Center for Biotechnological Information (NCBI). The sample group included 20 animals. Alignment of nucleotide sequences was performed using the BioEdit program. Sequence analysis showed the presence of polymorphisms in all studied genes. A total of six polymorphic sites are established, which are represented by transitions. Analysis of the gene tRNA eu showed the presence of A3892G substitution. The polymorphism A3892G in the Wuzhishan and Luchuan pigs was determined in the tRNA Leu1 gene, and polymorphism C3907T was determined in the Swedish wild boar. Many of the pigs studied had a simultaneous presence of two A12879G and C12883T transitions in the tRNA Leu2 gene. One transition of A8103G in the tRNA Ser1 gene was established in Large White pigs of Korean breeding. The polymorphism of the tRNA Ser2 gene is represented by the translation of T12838C into the Italian wild boar. The highest number of polymorphisms was determined in Large White of Korean and Chinese breeding, as well as in the Italian wild boar. The study of mtDNA polymorphism will allow to establish associative links and develop mtDNA markers that can be used in programs for improving and creating breeding resources in pig breeding.

Relationships among superantigen toxin gene profiles, genotypes, and pathogenic characteristics of Staphylococcus aureus isolates from bovine mastitis

Staphylococcus aureus is one of the major etiological agents of bovine mastitis, harboring a wide variety of staphylococcal superantigen (SAg) toxin genes. The SAg toxin genes are reported to be closely associated with the pathogenicity of the Staph. aureus causing the bovine mastitis. This study was conducted to investigate SAg toxin gene profiles and to assess the relationships among SAg toxin genes, genotypes of Staph. aureus, and their pathogenic properties. A total of 327 quarter milk samples were collected from bovine mastitis cases for isolation and identification of pathogens. In total, 35 isolates were identified as Staph. aureus, and the prevalence of Staph. aureus in milk samples was 13.6% (35/256). Polymerase chain reaction (PCR) and randomly amplified polymorphic DNA (RAPD) assays were used to detect the SAg toxin genes and to genotype Staph. aureus strains isolated from milk samples of bovine mastitis in 10 dairy herds located in Ningxia, China, respectively. The results showed that among the Staph. aureus isolates (n = 35), 71.4% (n = 25) of isolates carried at least one SAg toxin gene. In total, 18 SAg genes and 21 different gene combination patterns were detected among these isolates. The most common SAg genes in Staph. aureus isolates were sei, sen, and seu (44.0% each), followed by seo, tst, and etB (28.0% each), etA (24.0%), sem and sep (16.0% each), seb, sec, sed, and sek (12.0% each), and sea and seh genes (8.0% each); the seg, sej, and ser genes were present in 4.0% of the isolates. Three gene combinations were found to be related to mobile genetic elements that carried 2 or more genes. The egc-cluster of the seg-sei-sem-sen-seo genes, located on the pathogenicity island Type I υSaβ, was detected in 16% of isolates. Interestingly, we observed 6 RAPD genotypes (I to VI) in Staph. aureus isolates, and 2 of these genotypes were strongly associated with the severity of bovine mastitis; there was a close relationship between the RAPD genotypes and SAg genes. Isolates of RAPD type III were more frequently associated with clinical and subclinical mastitis, whereas strains of type VI were mostly related to subclinical mastitis. In addition, SAg genes were related to severity of bovine mastitis. We conclude that an obvious relationship exists among RAPD genotypes, SAg toxin genes, and severity of bovine mastitis.

The Effect of Polymorphisms on the Ala 119 Ser Gene Cytochrome P450 1B1*2 on the Susceptibility of Iranian Women to Develop Breast Cancer

Background: Cytochrome P450 IBI (CYP1B1) is involved in the metabolism of a wide range of internal and external substrates and also plays a key role in the metabolism of oestrogen. This enzyme is a factor that could potentially affect the likelihood of a person developing breast cancer. The aim of this study was to evaluate the correlation between polymorphism (RS1056827) and the occurrence of breast cancer in Iranian women. Methods: We used a case-control study design. After an initial evaluation, 79 women with breast cancer (the patient group) and 79 women without breast cancer (the control group) were selected to participate in the study. Their blood samples were then obtained, and a sample of their DNA was extracted. PCR-RELP was used to determine the genotypes of the participants. The data were subjected to statistical tests using the SPSS software package. Results: The results demonstrated that the frequency of the G allele in the patient and the control group were 34% and 69%, respectively. In addition, the frequency of the T allele in the patient and control group were 66% and 31%, respectively. The genotype frequency of TT, GG and TG in patients with breast cancer were 26.59%, 20.25% and 53.16%, respectively, and 22.79%, 60.76% and 16.45%, respectively, in the control group. There was a statistically meaningful correlation between the results of the genotypes in the patient and control groups. Conclusions: The results demonstrated that patients with the TT genotype are 3.85 times more likely to develop breast cancer. Therefore, the presence of this polymorphism could be one of the factors that lead to the development of breast cancer.

Response Mechanisms in Serratia marcescens IBBPo15 During Organic Solvents Exposure.

Serratia marcescens strain IBBPo15 (KT315653) which possesses serratiopeptidase (ser) gene (KT894207) exhibited good solvent tolerance. During the exposure of S. marcescens IBBPo15 cells to 5% organic solvents, n-decane was less toxic for this bacterium, compared with n-hexane, cyclohexane, ethylbenzene, toluene, and styrene. The exposure of the S. marcescens IBBPo15 cells to n-hexane, cyclohexane, ethylbenzene, toluene, and styrene induced the formation of large clusters, while in control and n-decane-exposed cells, only organization into small clusters was observed. The data obtained suggested that S. marcescens IBBPo15 cells produced some secondary metabolites (i.e., surfactant serrawettin, red pigment prodigiosin) which are well known as valuable molecules due to their large applications. The exposure of the bacterial cells to organic solvents induced secondary metabolites profile modifications. However, S. marcescens IBBPo15 possesses only alkB1, todM, rhlAB, pswP, mpr, and ser genes, the unspecific amplification of other fragments being acquired also when the primers for alkM1, xylM, ndoM, and C23DO genes were used. Modifications of DNA patterns were not depicted in S. marcescens IBBPo15 cells exposed to organic solvents.

Occurrence of Staphylococcus aureus on Farms with Small Scale Production of Raw Milk Cheeses in Poland.

This paper describes the results of a 3-year study on the prevalence, enterotoxinogenicity and resistance to antimicrobials of S. aureus isolated on dairy farms with small scale production of raw cow milk cheeses. The samples of raw milk, semi-finished products and the final products as well as swabs were collected between 2011 and 2013 from nine dairy farms in Poland. A total of 244 samples were examined, of which 122 (50.0%) were contaminated with S. aureus including 18 of 26 (69.2%) mature cheese samples with log10 CFU g−1 between <1- and 7.41. In swabs collected from the staff and production environment the highest contamination rate with coagulase positive staphylococci (CPS) was detected on hands of cheese makers (4.34 log10 CFU/swab). None of the cheese samples contaminated with CPS contained staphylococcal enterotoxins (SEs). However, 55 of 122 (45.1%) S. aureus isolates possessed SEs genes, mainly (26 of 55; 47.3%) a combination of the sed, sej and ser genes. Furthermore, the sep (15 of 55; 27.3%) as well as seg and sei (9 of 55; 16.4%) genes were also identified. The remaining S. aureus isolates possessed the sea gene (one isolate), the combination of sec, seg and sei (three isolates) as well as the sed, sej, sep and ser markers together (one CPS). Resistance to penicillin (62 of 122 isolates; 50.8%) was the most common among the tested isolates. Some CPS were also resistant to chloramphenicol (7; 5.7%) and tetracycline (5; 4.1%). The obtained results indicated that the analyzed cheeses were safe for consumers. To improve the microbiological quality of traditional cheese products more attention should be paid to animal welfare and hygiene practices during the process of cheese manufacturing in some dairy farms.

Distribution of food-borne Staphylococcus aureus enterotoxin genes.

We identified and analyzed 5 new-type enterotoxin genes, including SEj, SEl, SEq, SEm, and SEr, to explore the distribution of 5 enterotoxin genes in Staphylococcus aureus of different origins as well as their correlations and differences. We examined the distribution of the S. aureus enterotoxin genes and their pathogenic mechanisms. A total of 660 specimens were collected from January 2011 to December 2014, and 217 strains of S. aureus were isolated. The template DNA of S. aureus was extracted. The Primer6.0 and Oligo7 software were used to design and synthesize polymerase chain reaction primers. Amplification results were analyzed by electrophoresis, and the amplification products were recovered and sequenced. Thirty-six bacterial strains contained the SEj gene (16.6%), including 15, 8, 8, 4, and 1 strains in fresh meat, quick-frozen food, raw milk, human purulent tissue, and living environment, respectively. Thirty-one bacterial strains contained the SEr gene (14.3%), including 16, 9, and 6 strains in fresh meat, quick-frozen food, and raw milk, respectively. Twenty-one bacterial strains contained the enterotoxin SEq gene (9.7%), including 8, 6, 6, and 1 strains in fresh meat, quick-frozen food, raw milk, and human purulent tissue, respectively. No SEm and SEl genes were detected. Different types of foods carry different types of enterotoxins, providing a basis for quick tracing for food poisoning. Three enterotoxin genes, SEj, SEr, and SEq, showed the highest carrier rate in quick-frozen food. It is imperative to improve their detection in quick-frozen food.

Mutation in PCDH15 may modify the phenotypic expression of the 7511T>C mutation in MT-TS1 in a Chinese Han family with maternally inherited nonsyndromic hearing loss

ObjectivesMutations in MT-TS1 have been found to be associated with nonsyndromic sensorineural hearing loss (SNHL). PCDH15 codes for protocadherin-15, a member of the cadherin superfamily of calcium-dependent cell-cell adhesion molecules. In this study, we analyzed the correlation of both MT-TS1 and PCDH15 mutations in a Chinese Han family segregating maternally inherited nonsyndromic SNHL. MethodsWe ascertained a Chinese Han family segregating maternally inherited nonsyndromic sensorineural hearing loss. Eight of 10 maternal members in this family exhibited late-onset, progressive hearing impairment. Mutation screening of 79 known deafness genes was performed for the proband by targeted next-generation sequencing. ResultsA total of 651 variants were detected in this individual. Among them, a homoplasmic 7511T>C variant in MT-TS1, the mitochondrial tRNA Ser(UCN) gene, and a heterozygous p.Asp1010Gly variant in PCDH15 were more likely to be pathogenic. Consistent with the matrilineal inheritance with reduced penetrance, the 7511T>C variant in MT-TS1 was found in all 10 maternal members and an additional heterozygous p.Asp1010Gly variant in PCDH15 cosegregated with the hearing loss in this family. ConclusionOur results suggested that the PCDH15 p.Asp1010Gly variant probably modified the phenotypic expression of the 7511T>C mutation in MT-TS1.

Genome-wide prediction of the polymorphic Ser gene family in Tetrahymena thermophila based on motif analysis.

Even though antigenic variation is employed among parasitic protozoa for host immune evasion, Tetrahymena thermophila, a free-living ciliate, can also change its surface protein antigens. These cysteine-rich glycosylphosphatidylinositol (GPI)-linked surface proteins are encoded by a family of polymorphic Ser genes. Despite the availability of T. thermophila genome, a comprehensive analysis of the Ser family is limited by its high degree of polymorphism. In order to overcome this problem, a new approach was adopted by searching for Ser candidates with common motif sequences, namely length-specific repetitive cysteine pattern and GPI anchor site. The candidate genes were phylogenetically compared with the previously identified Ser genes and classified into subtypes. Ser candidates were often found to be located as tandem arrays of the same subtypes on several chromosomal scaffolds. Certain Ser candidates located in the same chromosomal arrays were transcriptionally expressed at specific T. thermophila developmental stages. These Ser candidates selected by the motif analysis approach can form the foundation for a systematic identification of the entire Ser gene family, which will contribute to the understanding of their function and the basis of T. thermophila antigenic variation.

Incidence and characterization of Staphylococcus aureus strains isolated from food markets

Staphylococcus aureus is a major foodborne pathogen. The primary purpose of this research was to evaluate S. aureus contamination levels and distribution characteristics in various kinds of food. A total of 121 samples of 11 kinds of food were collected from different food markets in the summer season according to their availability and popularity, and 103 (85.1 %) samples were found to be contaminated with S. aureus. Raw meat, meat products, soybean products, and pickled vegetables are highly contaminated food. For enterotoxin genes analysis, among all the isolates, 20 (19.4 %) possessed sea gene, 2 (1.9 %) with sed gene, 8 (7.8 %) with seg gene, 4 (3.8 %) with seh gene, 24 (23.3 %) with sei gene, 5 (4.8 %) with selj gene, 24 (23.3 %) with selk gene, 44 (42.7 %) with seln gene, and 8 (7.8 %) with ser gene. The seb, sec, see, selm, and selu genes were not found in any of the isolates. For the antibiotic resistance genes tests, most isolates from the food samples were positive for at least 1 of 6 antibiotic resistance genes. The most prevalent resistance genes in samples were ermA (85/103, 82.5 %), followed by tetA (61/103, 59.2 %), chlA (60/103, 58.2 %), norA (56/103, 54.3 %), mecA (10/103, 9.7 %), and blaZ (7/103, 6.8 %). Our results showed that most isolates harbored enterotoxins-producing genes and antibiotic resistance genes, indicating the risk of foodborne S. aureus outbreaks, which drew urgent attention to the great need to improve hygienic conditions in food processing, in order to enhance the safety of food products.