Few investigations on guided bone regeneration (GBR) focus on the behaviour of tissues adjacent to barrier membranes. This study was conducted to (1) evaluate the barrier function potential of different resorbable and nonresorbable membranes for GBR, (2) investigate their structural changes after different intervals, and (3) characterize tissue composition and reaction adjacent to the barrier by qualitative histologic evaluation. Seven barriers for GBR were used per animal (made of dense or expanded polytetrafluoroethylene (d/ePTFE), titanium, polyetherurethane, collagen and two polylactide-polyglycolide-/-trimethylenecarbonate-co-polymers (PLPG, LPGTC) in standardized defects not exceeding the critical size) without using bone substitution material or autogenous bone at the right inferior margin of the mandibles of six domestic pigs. Samples of the defect areas with membranes were harvested after 2 days (one animal), 4 and 8 (two animals, each) and 12 weeks (one animal), respectively. The healing of bone defects was completed in all animals after 12 weeks. Nonresorbable barriers prevented the soft tissue in-growth into standardized defects. Thinner layers of fibrous tissue were seen underneath the dense and rigid barriers (dPTFE, titanium) when compared with collagen and PLPG/LPGTC, in which soft-tissue plugs occupied the crestal defect portion. PLPG-/LPGTC-barriers underwent structural changes after 4 weeks and revealed blistered central layers, whereas structural changes were not evident in nonresorbable barriers. The degradation of PLPG-/LPGTC-membranes was present with in-growth of fibres, vessels, and cells. Using collagen or synthetic polymer barriers for GBR, the application of bone or bone substitutes to prevent membrane prolapse into the defect is suggested.

Edwardsiella tarda is a pathogen that causes edwardsiellosis in aquatic animals. The emergence of multiple antibiotic‐resistant strains makes antibiotic treatment difficult. This study aimed to investigate the antibiotic susceptibility patterns and the genotypic characterization of E. tarda isolated from cage‐cultured red tilapia in Thailand. A total of 30 isolates were identified as E. tarda using biochemical and molecular analysis. The disc diffusion method for testing antibiotic susceptibility showed all the isolates were resistant to colistin sulphate and oxolinic acid. High levels of resistance to amoxicillin, ampicillin, ceftazidime, oxytetracycline and sulphamethoxazole/trimethoprim were observed as well. The multiple antibiotic resistance index ranged from 0.25 to 0.92, indicating that these isolates had been exposed to high risk sources of contamination where antibiotics were commonly used. All the isolates carried the blaTEM gene based on polymerase chain reaction (PCR). The tetA and sul3 genes were detected in 90% (27/30) and 26.7% (8/30) of the isolates respectively. Nine different genetic groups of isolates were obtained using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC‐PCR). A correlation between genetic types and multiple antibiotic‐resistant patterns was found. These results highlight the potential risks of multiple antibiotic‐resistant isolates for humans and the environment.

Streptococcus spp. are major pathogenic bacteria associated with massive mortality in tilapia. This study investigated the phenotypic and genotypic characterization of Streptococcus agalactiae (GBS) and Streptococcus iniae (S. iniae) isolated from tilapia in river-based floating cage and earthen pond farms in northern Thailand. Isolates were identified by biochemical and molecular analyses. Capsular typing, enterobacterial repetitive intergenic consensus polymerase chain reaction and multilocus sequence typing were performed to investigate the genetic relatedness. Six and one isolates were confirmed as GBS and S. iniae, respectively. All Streptococcus spp. isolates were obtained from 4 river-based cage farms (4/33), while samples collected from earthen pond farms (N = 28) were negative for streptococcosis. All GBS with serotype Ⅲ and sequence type (ST) 283 was observed. The β-haemolytic GBS isolates were resistant to five antimicrobials, while the S. iniae was susceptible to all antimicrobials. This study indicates both GBS and S. iniae are the major bacterial pathogens responsible for streptococcosis infection in farmed tilapia of northern Thailand with GBS as dominant species. This survey highlights that the river-based cage farms seriously impact on the healthy development of the tilapia industry. K E Y W O R D Searthen pond farm, northern Thailand, river-based cage farm, Streptococcus spp., tilapia ACK N OWLED G EM ENTS

A cDNA of Japanese flounder (Paralichthys olivaceus) CC chemokine designated as Paol-SCYA104 was cloned and sequenced. The cDNA contains an opening reading frame of 315 nucleotides encoding 104 amino acid residues. The full gene was cloned and sequenced from a BAC library. It has a length of approximately 750 bp from the start codon to the stop codon and is composed of four exons and three introns. Four cysteine residues are conserved in the same positions as those of mammalian and fish CC chemokines. Paol-SCYA104 gene was expressed in several organs, including peripheral blood leukocytes (PBLs), head kidney, trunk kidney, and spleen. The recombinant Paol-SCYA104 was expressed in Escherichia coli and the expressed protein was partially purified. The recombinant Paol-SCYA104 was able to attract Japanese flounder PBLs in a microchemotaxis chamber. On the other hand, a negative control, the fraction of the control cells carrying an expression vector lacking the Paol-SCYA104 cDNA, did not show chemotactic activity. These results indicate that Paol-SCYA104 probably acts as a CC chemokine.

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