Genotypic Variations of Mutans Streptococci Isolated from Dental Caries by REP-PCR

Mutans streptococci (MS) are a group of oral bacteria considered as the main cariogenic organisms. MS consists of several species of genus Streptococcus which are sharing similar phenotypes and genotypes. The aim of this study is to determine the genetic diversity of the core species of clinical strains of Streptococcus mutans, Streptococcus sobrinus and Streptococcus downei by using repitative extragenic palindromic (REP) primer. The DNA of the clinical strains of S. mutans (n=10), S. sobrinus (n=05) and S. downei (n=04) have been employed in the present study, which have been previously isolated from caries active subjects. The DNA of the clinical and reference strains was subjected to PCR amplification using REP primer. The phylogenetic dendrogram is constructed from the REP PCR banding profile by neighbour-joining method using PyElph 1.4 software. The size of the DNA amplicons generated by using REP primer were S. mutans (1500 bp to 250 bp), S. sobrinus (6000 bp to 250 bp) and S. downei (5000 bp to 400 bp). The results present common band at 480 bp in all the clinical strains of S. sobrinus. The current study is the first to demonstrate the genetic variety of S. sobrinus and S. downei by using REP primer. REP-PCR have been found to be a powerful method to study the molecular diversity of S. mutans, S. sobrinus and S. downei. Additionally, further studies are suggested to analyze the species specific bands and also to find the possibility to produce a new specific primer for S. sobrinus.

Parity-time phase transition in photonic crystals with $$C_{6v}$$ symmetry

We investigate the parity-time (PT) phase transition in photonic crystals with $$C_{6v}$$ C 6 v symmetry, with balanced gain and loss on dielectric rods in the triangular lattice. A two-level non-Hermitian model that incorporates the gain and loss in the tight-binding approximation was employed to describe the dispersion of the PT symmetric system. In the unbroken PT phase, the double Dirac cone feature associated with the $$C_{6v}$$ C 6 v symmetry is preserved, with a frequency shift of second order due to the presence of gain and loss. The helical edge states with real eigenfrequencies can exist in the common band gap for two topologically distinct lattices. In the broken PT phase, the non-Hermitian perturbation deforms the dispersion by merging the frequency bands into complex conjugate pairs and forming the exceptional contours that feature the PT phase transition. In this situation, the band gap closes and the edge states are mixed with the bulk states.

Antibiotic resistance and distribution of SodCI, sopE, sefA genes among Salmonella enteric serotype Enteritidis isolates from poultry

Present work aimed to examine the antibiotic resistance of the Salmonella enterica serotype Enteritidis (SE) isolates from poultry, to study the plasmid-mediated ampicillin resistance and to detect and determine the distribution of sodCI, sopE and sefA genes. Thirty-five SE isolates from one-day chicks, layers and broilers were studied for susceptibility/resistance to sixteen antimicrobial agents; 23 (65.7%) of them showed resistance to ampicillin, 5 (14.3%) to ampicillin and tetracycline, 4 (11.45%) to tetracycline and 1 (2.9%) isolate showed multi-drug resistance. Ampicillin (AmpR) and ampicillin/tetracycline (AmpRTeR) resistance was easily transferred by conjugation, and all isolates except two possessed a common band. The molecular mass of the plasmid carrying ampicillin resistance was approximately determined at 41kb after DNA digestion with BamHI, HindIII, EcoRI, EcoRV and PstI restriction enzymes and ligation of EcoRI fragments to pET29c. For the detection of TEM-1 or/and TEM-2 ß-lactamases, two pairs of primers were used in a polymerase chain reaction (PCR). The PCR products showed the presence of blaTEM-1 gene in all isolates. The presence of SodCI, sopE, sefA genes was also examined by PCR. Twenty-two (62,8%) isolates carried the sodCI gene, thirty-four (97,2%) isolates carried the sopE gene and all isolates carried the sefA fimbrial locus.

Biochemical changes of the cereal cyst nematode, Heterodera avenae, at low temperatures

Cereal cyst nematode (Heterodera avenae) diapause is induced by high temperatures and is broken by low temperatures. In this study, metabolic responses were monitored in diapause and non-diapause H. avenae during exposure to 4°C for 10 weeks. The results showed that there was no difference in total carbohydrate content. The content of glycogen and glycerol at 0 week was relatively high but decreased with increased storage time at 4°C. The content of trehalose of the nematode at 10 weeks was significant lower than that at 5 weeks at 4°C. Protein content increased significantly after incubation for 5 and 10 weeks. Esterase and trehalase activity increased with the increasing period at 4°C and showed a significant difference between treatments for esterase activity but there was no significant difference between 5 and 10 weeks for trehalase activity. The SDS-PAGE pattern indicated that a 15.5 kDa protein was absent at 10 weeks and present at 0 and 5 weeks. Esterase isoenzyme patterns of H. avenae showed that at 10 weeks there were four bands: EST 0.21, EST 0.24, EST 0.30 and EST 0.34 (Rf values). EST 0.24 was the common band in the three treatments. Biochemical tests were conducted to correlate with hatching experiments using the same treatments. 2-DE patterns of H. avenae showed that diapause and non-diapause nematodes had 409 and 412 protein spots, respectively, and 19 protein spots were unique: 11 distinct proteins in non-diapause and eight distinct proteins in diapause. This information could be helpful in understanding the diapause mechanism of the cereal cyst nematode.

Class B trichothecene chemotyping in Fusarium species by PCR assay

Fusarium isolates are divided into three chemotypes according to produce of class B trichothecenes; 3-acetyldeoxynivalenol (3ADON) 15-acetyldeoxynivalenol (15ADON) and nivalenol (NIV) and 4- acetyldeoxynivalenol (NIV) chemotypes. In this study, chemotyping of seventeen isolates from Turkey and Iran belonging to F. graminearum, F. culmorum, F. poae and F. pseudograminearum species were carried out by polymerase chain reaction (PCR) analysis. While all F. culmorum and F. poae isolates determined as 3ADON, remaining F. graminearum and F. pseudograminearum isolates were either 3ADON or 15ADON chemotypes. A common band of 583 bp long DNA fragment was amplified in all of F. culmorum and F. poae, one F. pseudograminearum (21F) and four F. graminearum (14F, sh14, sh15, sh7) isolates with 3ADON chemotype. However, remaining two F. pseudograminearum and four F. graminearum isolates with 15ADON chemotype, yielded amplicons that of 863 bp. It was shown that 3ADON was more predominant chemotype from other class B trichothecenes. This is the first report on chemotyping of F. poae and F. pseudograminearum isolates and also to show presence of 3ADON chemotype in F. graminearum isolate from Turkey.

Evaluation Method for Band Selection Algorithms of Hyperspectral Image

Band selection algorithm is most important in data dimension reduction of hyperspectral image. There are many algorithms of band selection, but there are only few methods to do algorithm evaluation. A method is put forward in this paper to evaluate the band selection algorithm of hyperspectral image. The amount of information, brightness, image contrast and definition are defined as 4 indexes to measure deferent data fusion based on various band selection results. Based on the measurement, the evaluation of band selection algorithm is realized. In the paper, the evaluation method is used in the compare of 4 common band selection algorithms, the result of measurement is analyzed and the feasibility is verified.

Modification of photonic crystals for obtaining common band gaps for TE and TM waves

The band gaps of the two-dimensional photonic crystals, created by inhomogeneous triangular photonic crystal of variable central hexagonal holes are derived. The structure is made of air holes in GaAs. We present the best absolute photonic band gap for this structure by changing the holes’ radii. The photonic band gaps are calculated by the plane wave expansion method. The results indicate 95% overlap in the band gaps of both polarizations of TE and TM in triangular lattice.

ENTANGLEMENT TRAPPING AND SUDDEN DEATH IN A COMMON BAND GAP

Using the pseudomode method, we study the exact entanglement dynamics of two atoms in a common band gap. In order to understand the role played by the common band gap we compare our results with the case of two independent band gap model. We demonstrate that the parameter region at which the entanglement sudden death occurs is smaller than the independent band gap model. Moreover, the atomic entanglement trapping can also be achieved in the common band gap model, and the value of entanglement trapping is larger in the common band gap case than in the independent band gap case.

Identification of Sphingomonads on the Basis of Polymerase Chain Reaction Amplified 16S rRNA Gene

Sphingomonas is a genus that is basically of environmental origin but can also be associated with health hazards, especially in the hospital environment where there is a great need to properly monitor water sources. The abundance and frequent isolation of derivatives of yellow pigmented colonies from drinking water samples in Lebanon—where an intermittent mode of supply is employed, and which induces frequent biofilm sloughing—necessitated the establishment of a rapid and feasible assay to screen specifically for sphingomonads. In this study, 50 isolates recovered from drinking water with yellow- to orange-pigmented colonies were used to establish a polymerase chain reaction-based (PCR-based) screening assay. The use of sphingomonad specific modified primers gave one common band with a size of 320 bp in all resumptive and sequence confirmed sphingomonads. However, no amplification was observed with Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Applying the PCR-based assay described in this paper increased both the efficiency and the reliability of screening for sphingomonads in water samples, thereby minimizing related risk factors.