Effects of streamline complexity on the relationships between urban land use and ecological communities in streams

Urban land use can adversely affect the water quality of adjacent streams through interactions at the edges of the two ecosystems. From a landscape ecological perspective, edges control the flow rate of materials between two adjacent systems. Based on the rationale that the streamline complexity formed between land uses and water bodies may function in this manner, we investigated the potential role of streamline complexity in the relationship between stream ecological communities and urban land use in Korea. Various indices of biological indicators including the diatom assemblage index for organic pollution, the trophic diatom index, the Korean saprobic index, and the index of biotic integrity were applied at 80 sampling sites in the Nakdong River system. We computed the fractal dimensions of the streamlines within 1-km buffers and the proportion of urban land use in the watershed within 5-km buffers around the sampling sites. A moderation model was adopted to investigate the role of streamline complexity in the relationship between urban land use and the biological indices of ecological communities. A comparison between a simple geometry regression model and complex geometry models indicated that streamline complexity may moderate the adverse impacts of urban land use on ecological communities in streams. The moderating effect of streamline complexity was particularly significant for assemblages of macroinvertebrates and fishes. Therefore, to enhance the ecological integrity of streams, we strongly recommend considering streamline complexity when restoring channelized streams in developed areas.     

Histamine formation in flying fish contaminated with <Emphasis Type="Italic">Staphylococcus xylosus</Emphasis>

Histamine is the main causative agent of scombroid poisoning. However, unlike scombroid fish, histamine poisoning due to consumption of flying fish has never been reported. In this study, the white muscle of flying fish had high levels of free histidine at approximately 423.9 mg/100 g, and was inoculated with Staphylococcus xylosus Q2 isolated from dried flying fish at 5.0 log CFU/g and stored at ?20 to 35°C to investigate histamine-related quality. The histamine contents quickly increased to higher than 50 mg/100 g in samples stored at 25 and 35°C within 12 h as well as stored at 15°C within 48 h. However, bacterial growth and histamine formation were controlled by cold storage of the samples at 4°C or below. Once the frozen flying fish samples stored at ?20°C for 2 months were thawed and stored at 25°C after 24 h, histamine started to accumulate rapidly (>50 mg/100 g of fish). Therefore, flying fish muscle was a good substrate for histamine formation by bacterial histidine decarboxylation at elevated temperatures (>15°C) when it is contaminated with S. xylosus. In conclusion, since the improperly contaminated flying fish muscle with S. xylosus could lead to production of hazardous levels of histamine over time when stored at temperatures >15°C, the flying fish should be stored below 4 °C or below to control proliferation of S. xylosus, and TVBN and histamine production.     

Glucose and weight control in mice with a designed ghrelin O-acyltransferase inhibitor

Ghrelin is a gastric peptide hormone that stimulates weight gain in vertebrates. The biological activities of ghrelin require octanoylation of the peptide on Ser(3), an unusual posttranslational modification that is catalyzed by the enzyme ghrelin O-acyltransferase (GOAT). Here, we describe the design, synthesis, and characterization of GO-CoA-Tat, a peptide-based bisubstrate analog that antagonizes GOAT. GO-CoA-Tat potently inhibits GOAT in vitro, in cultured cells, and in mice. Intraperitoneal administration of GO-CoA-Tat improves glucose tolerance and reduces weight gain in wild-type mice but not in ghrelin-deficient mice, supporting the concept that its beneficial metabolic effects are due specifically to GOAT inhibition. In addition to serving as a research tool for mapping ghrelin actions, GO-CoA-Tat may help pave the way for clinical targeting of GOAT in metabolic diseases.     

Climate‐driven winter variations of Calanus sinicus abundance in the East China Sea

Global environmental changes threaten the sustainable use of resources and raise uncertainties regarding marine populations' responses in a changing Ocean. The pelagic copepods of the genus Calanus play a central role in shelf ecosystems transferring phytoplankton carbon to harvested populations, from boreal to temperate regions. Here we examined a 15‐yr time series of Calanus sinicus abundance in regards to climate forcing in the East China Sea. We identified a compound effect of the Pacific Decadal Oscillation (PDO) and the East Asian Winter Monsoon (EAWM) on environmental conditions in the East China Sea. Such climate influences not only a southward transport of C. sinicus from its population centres into the Taiwan area, but favours advantageous thermal conditions for the species as well. On the interannual scale, our results show that the population size of C. sinicus echoes climate‐driven temperature changes. Hence, the possibility of using the PDO and EAWM variability for assessing and predicting interannual abundance changes of C. sinicus in the East China Sea is considered. The observed close relationship between climate and C. sinicus may promote bottom‐up controls in the pelagic food web, further influencing the southern edge of the species' geographic distribution. Owing to the prominent role this species plays in food web dynamics these results might help integrative fisheries management policies in the heavily exploited East China Sea.     

Prevalence of Bartonella henselae and Bartonella clarridgeiae in cats and dogs in Korea

Blood, saliva, and nail samples were collected from 54 dogs and 151 cats and analyzed for the presence of Bartonella henselae with a novel nested polymerase chain reaction (PCR) method. Bartonella (B.) henselae was detected in feral cat blood (41.8%), saliva (44.1%), and nail (42.7%) samples. B. henselae was also detected in pet cat blood (33.3%), saliva (43.5%), and nail (29.5%) samples and in pet dog blood (16.6%), saliva (18.5%), and nail (29.6%) samples. Nine samples were infected with B. clarridgeiae and 2 were co-infected with B. henselae and B. clarridgeiae of blood samples of dogs. This report is the first to investigate the prevalence of B. henselae and B. clarridgeiae in dogs and cats in Korea, and suggests that dogs and cats may serve as potential Bartonella reservoirs.     

A molecular marker for the specific detection of new pathotype 5‐like strains of Plasmodiophora brassicae in canola

Clubroot of crucifers, caused by Plasmodiophora brassicae, is managed in canola (Brassica napus) by the deployment of resistant cultivars. Recently, however, new strains of P. brassicae have been detected in Alberta, Canada, that can overcome this resistance. Some of these strains are classified as pathotype 5 on the differential system of Williams, but are distinguished by their ability to overcome host resistance. In order to expedite the identification of these new pathotype 5‐like strains, three primer sets were developed based on the 18S‐ITS region of the pathogen. With primers P5XF3 and P5XR3, a 127 bp product was amplified from all new pathotype 5‐like strains following optimized PCR analysis. A TaqMan probe‐based quantitative assay was also developed. These protocols could be used to detect as little as 0.5 pg P. brassicae DNA, and as few as 10⁴ mL^?1 pathogen resting spores; infection of host tissues could be detected as soon as 4 days after inoculation. The PCR and qPCR assays described in this study represent useful tools for the rapid and reliable diagnosis and quantification of new pathotype 5‐like strains of P. brassicae.     

A model for demonstrating the adhesion of Actinobacillus seminis to epithelial cells.

The objective of this study was to demonstrate that a field isolate of Actinobacillus seminis (As8C) will adhere to epithelial cells and that this adhesion can be inhibited by pretreating the bacteria with mouse serum containing polyclonal antibodies (PoAbs) prepared against this isolate. An indirect fluorescent antibody test, transmission electron microscopy, and phase-contrast microscopy confirmed the adhesion of As8C to an established culture of bovine kidney epithelial cells (BKECs). In a bacterial adhesion assay, 40 As8C were estimated to adhere to each BKEC after 60 min. Using a bacterial inhibition assay, PoAbs diluted 10(-2) or 10(-3) inhibited the adhesion of As8C to BKECs by approximately 90%. Bacterial inhibition decreased to about 50% when the PoAbs were diluted to 10(-4). There was less than 10% inhibition of adhesion of As8C to BKECs when higher dilutions of PoAbs were used. The inhibition of As8C adhesion to BKECs was less than 20% following pretreatment of BKECs with 10(-2) to 10(-5) dilutions of PoAbs. Moreover, pretreatment of As8C with a 10(-2) dilution of PoAbs did not appear to adversely affect bacterial growth on agar. It is likely that the PoAbs interrupted the adhesion of As8C to BKECs by sterically interfering with a bacterial adhesin-epithelial cell receptor interaction.