Bacterial coldwater disease of fishes caused by Flavobacterium psychrophilum

AbstractColdwater disease (CWD) is a bacterial disease that affects a broad host-species range of fishes that inhabit cold, fresh waters. This disease occurs predominately at water temperatures of 16°C and below, and is most prevalent and severe at 10°C and below. Coldwater disease occurs in cultured and free-ranging populations, with hatchery-reared young trout and salmon species especially vulnerable to infections. Flavobacterium psychrophilum is the etiological agent of CWD. This Gram-negative bacterium may be recovered from affected host tissues and characterized using standard biochemical techniques, providing that reduced nutrient media are used. There are numerous reports that describe sensitive and specific serologic and genomic diagnostic techniques for CWD. The entire genome of a virulent isolate of F. psychrophilum has been sequenced and described. Rainbow trout (Oncorhynchus mykiss) fry syndrome is also caused by F. psychrophilum with mortalities >50% possible among affected fish lots. Evidence suggests that pathogen transmission occurs both horizontally and vertically. Analogous to many diseases to other animals, prevention and control are essential to avoid losses to CWD, particularly since there is currently no commercially available vaccine and a limited number of antimicrobials have been approved for treating food fish worldwide. This review provides current host and geographic ranges of the pathogen, and covers epizootiology, transmission, pathogenicity, diagnostics, and prevention and treatment

THE IMPACT OF MATERIAL WEAKNESS PRESENTATION STRUCTURE AND INTERNAL CONTROL TERMINOLOGY ON INVESTOR PERCEPTIONS

Management is required to disclose any material weaknesses discovered during its evaluation to prepare the company’s financial statements in their internal control over financial reporting (ICFR) report. Across two experiments, I examine the impact of two presentation characteristics of a material weakness made up of multiple, smaller problems— (1) the structure of the presentation of the material weakness, which is whether the material weakness is identified first, followed by descriptions of its individual parts (Top Down structure) or vice versa (Bottom Up structure) and (2) whether or not the parts of the weakness are labeled with ICFR terminology (“significant deficiencies” vs. “issues”). In my first experiment I find evidence that presenting the material weakness last, in comparison to presenting the material weakness first, increases the perceived number of distinct problems that investors perceive in a company’s ICFR, but I ultimately do not find that this structure significantly impacts investors’ perceptions of investment desirability. In my second experiment, I specifically examine how using (versus not using) ICFR terminology to identify the parts of the material weakness impact investors’ perceptions of the severity of the material weakness and how the presentation structure moderates that relationship. I find that using ICFR terminology increases the perceived overall severity of the weakness, although the effect of presentation structure is insignificant. I also find that using ICFR terminology negatively affects the investment desirability of a company through two separate paths—ICFR terminology increases (1) the perceived number of distinct problems in ICFR and (2) the perceived severity of the individual parts of the material weakness. Both of these paths increase the perceived severity of the material weakness, which then decreases investment desirability. Lastly, providing a definition for the ICFR terminology (i.e., an explanation that “significant deficiencies” are relatively less severe deficiencies than material weaknesses) does not impact the effect of ICFR terminology on perceptions of weakness severity

Chess with Pigeons

In a time of Global Pandemic, massive social justice demonstrations, and concerning political shifts, reality feels inaccessible and at times even unreal. With quarantine and social distance as the new norm, our human connections are abstract and digitized. My thesis will be a collection of short fiction that seeks to employ methods of the speculative genre and alternative narrative structure to explore our shifting understanding of humanity and connectedness. The introduction to this collection will lay out the process through which speculative realities better define our own

Bactericidal efficacy of elevated pH on fish pathogenic and environmental bacteria

Ship ballast water is a recognized medium for transfer and introductions of nonindigenous species. There is a need for new ballast water treatment methods that effectively and safely eliminate or greatly minimize movements of these species. The present study employed laboratory methods to evaluate the bactericidal efficacy of increased pH (pH 10.0–12.0) for exposure durations of up to 72 h to kill a variety of Gram-negative and Gram-positive bacteria including fish pathogens (Aeromonas spp., Yersinia ruckeri, Edwardsiella ictaluri, Serratia liquefaciens, Carnobacterium sp.), other common aquatic-inhabitant bacteria (Serratia marcescens, Pseudomonas fluorescens, Staphylococcus sp., Bacillus sp.) and indicators listed in International Maritime Organization D2 Standards; namely, Vibrio cholera (an environmental isolate from fish), Escherichia coli and Enterococcus faecalis. Volumes of 5 N NaOH were added to tryptic soy broth to obtain desired pH adjustments. Viable cells were determined after 0, 4, 12, 24, 48, and 72 h. Initial (0 h) cell numbers ranged from 3.40 × 104 cfu/mL for Bacillus sp. to 2.44 × 107 cfu/mL for E. faecalis. The effective endpoints of pH and treatment duration necessary to realize 100% bactericidal effect varied; however, all bacteria tested were killed within 72 h at pH 12.0 or lower. The lowest parameters examined, 4 h at pH 10.0, were bactericidal to V. cholera, E. ictaluri, three of four isolates of E. coli, and (three of four) Aeromonas salmonicida subsp. salmonicida. Bactericidal effect was attained at pH 10.0 within 12 h for the other A. salmonicida subsp. salmonicida, and within 24 h for P. fluorescens, and the remaining E. coli

Recovery of lead and sulfur by combined chlorination and electrolysis of galena /

Bibliography: p. 29.Mode of access: Internet

Sequence comparison of sulphonamide resistance genes from Aeromonas salmonicida, Edwardsiella ictaluri, and Escherichia coli

Isolates of Aeromonas salmonicida, Edwardsiella ictaluri, and Escherichia coli 1898, from different hosts and geographical locations, displayed resistance to Romet, a potentiated sulphonamide. This resistance is encoded on a plasmid (∼55 kb) containing sulphonamide resistance genes, sul I or sul II as demonstrated by polymerase chain reaction (PCR) analysis. PCR products from either sul I (∼900 bp) or sul II (∼400 bp) were sequenced and compared with the National Institutes of Health GenBank database sequences for these genes. The results suggest common environmental sources of this resistance factor related to various bacterial species and geographical areas. Sul I PCR fragments from various species were identical. This consensus sequence was 99.8% similar to the GenBank sul I sequence. Sul II PCR fragments from various species were 95-100% similar, which was 98.5% similar to the GenBank sul II sequence. The above bacterial species possess nearly identical sul I and sul II gene fragments (\u3e95% homology) to GenBank sul I and sul II sequences from a variety of bacterial species representing hosts and geographical locations other than those in the present study