Salmonella Strains Isolated from Galápagos Iguanas Show Spatial Structuring of Serovar and Genomic Diversity

It is thought that dispersal limitation primarily structures host-associated bacterial populations because host distributions inherently limit transmission opportunities. However, enteric bacteria may disperse great distances during food-borne outbreaks. It is unclear if such rapid long-distance dispersal events happen regularly in natural systems or if these events represent an anthropogenic exception. We characterized Salmonella enterica isolates from the feces of free-living Galápagos land and marine iguanas from five sites on four islands using serotyping and genomic fingerprinting. Each site hosted unique and nearly exclusive serovar assemblages. Genomic fingerprint analysis offered a more complex model of S. enterica biogeography, with evidence of both unique strain pools and of spatial population structuring along a geographic gradient. These findings suggest that even relatively generalist enteric bacteria may be strongly dispersal limited in a natural system with strong barriers, such as oceanic divides. Yet, these differing results seen on two typing methods also suggests that genomic variation is less dispersal limited, allowing for different ecological processes to shape biogeographical patterns of the core and flexible portions of this bacterial species' genome

Cutaneous leishmaniasis in the Libyan Arab Jamahiriya: a study of the Yafran area

We studied 445 cases of cutaneous leishmaniasis in the Yafran area during the period February 1991 to December 1992. The highest incidence rates were recorded at the end of the transmission seasons in two peaks, one in November 1991 and the second in December 1992. The ratio of infected males to females was 1.85: 1.00. The highest rate of infection was found among people 11-20 years of age. This indicates that the disease is not new in the Yafran area.</jats:p

Case study of marine pollution in Teluk Bahang, Penang, Malaysia

Abstract Teluk Bahang is a small fishing village located in the north-western of Penang Island, Malaysia. It has several attractions which include forest reserved park, ecotourism sites, theme parks and famous for its aquaculture activities. On 18th April 2019, fish farmers in Teluk Bahang experienced mass mortality of cultured fishes, namely groupers, barramundi, golden and red snappers due to a sudden change in water quality. Hence, this study was conducted to discuss marine pollution that occurred in Teluk Bahang that had caused the death of tonnes cultured fishes. Water samples were collected at the fish cage to investigate the water quality (physical and chemical parameters), heavy metals content, cell density and phytoplankton composition for determination of algal bloom that might be the cause of this crisis. Water samples were collected three times on 19th April 2019, 8th May 2019 and 26th May 2019. The results for physical and chemical parameters (pH, salinity, surface temperature, nitrate and phosphate) were all within the permissible limit according to Malaysia Marine Water Quality Class 2 (for aquaculture and recreation). Almost no harmful dinoflagellate species were detected in the water samples which indicated that phytoplankton did not cause a direct effect on the fish mortality. The concentration of heavy metals namely Cu, Cd, Ni, Fe, As and Hg in water samples were measured by atomic absorption spectroscopy (AAS). Results showed no detection of As and Hg concentration. The concentration of Cd, Cu and Fe in water ranged from 0.058-0.065ppm, 0.057-0.077ppm and Fe 0.326-0.389ppm respectively. These levels exceeded 20-100 times from the permissible limit. Ni concentration detected at 0.472-0.513ppm which was 990 times exceeded the permissible levels. These results indicated that metal pollution occurred in the marine water of Teluk Bahang and the possibility that the area may no longer be suitable for aquaculture or recreational purposes.</jats:p

Recursive Least-Squares in Feature Space for System Identification

International audienc

Adhesion of type A Pasteurella mulocida to rabbit pharyngeal cells and its possible role in rabbit respiratory tract infections

Pasteurella multocida serotype A was found in association with the mucosal epithelium of the nasopharynges of rabbits with respiratory tract infections. The bacteria specifically attached to squamous epithelial cells of the pharyngeal mucosa both in vivo and in vitro and to some tissue culture cell lines such as HeLa. All strains with serotype A capsules were adhesive. With the exception of one serotype D strain, strains with capsular serotypes B, D, and E were at least 10-fold less adhesive. Bacterial adhesiveness was much reduced after pronase digestion, heat treatment, and homogenization, but removal of the hyaluronic acid capsule increased adhesion. Electron microscopy revealed that fimbriae were produced by an adhesive pasteurella strain, but not by two nonadherent strains. The attachment of the former strain to pharyngeal and HeLa cells was inhibited by N-acetyl-D-glucosamine. Together, these findings suggest that this amino sugar may be a component of the receptor on both animal cell surfaces and that the fimbriae may be the adhesions. It is proposed that bacterial attachment has a role in colonization and infection of rabbit upper respiratory mucosae.</jats:p