C A Shoemaker results 36
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Efficacy of an Inactivated Bacterin Vaccine Against Emerging Streptococcus dysgalactiae in Channel Catfish ( Ictalurus punctatus )NARA Subscribed
Lancefield Group C Streptococcus dysgalactiae recently emerged as a catfish pathogen in the US. Reports from hatcheries suggest S. dysgalactiae causes substantial broodfish loss. We aimed to develop a challenge model and evaluate vaccine efficacy against S. dysgalactiae in juvenile channel catfish ( Ictalurus punctatus ). Three S. dysgalactiae (14–1, 14–24 and 14–25) isolates were tested for virulence. Intracoelomic (IC) injec...
Streptococcus dysgalactiae From Farm‐Raised Channel Catfish in Mississippi, USA, With Notes on Fish‐Associated Group C S. dysgalactiaeNARA Subscribed
Lancefield serological group C Streptococcus dysgalactiae (GCSD) is an emerging cause of fish disease worldwide, largely associated with mariculture in Asia. In the United States (US), GCSD had been a pathogen of minimal concern for fish, but recent cases indicate a putative emergence in wild and cultured freshwater fish populations in the Americas. The current study discusses three novel cases of GCSD‐associated streptococcos...
The long and the short of it: Mechanisms of synchronous and compensatory dynamics across temporal scalesNARA Subscribed
Synchronous dynamics (fluctuations that occur in unison) are universal phenomena with widespread implications for ecological stability. Synchronous dynamics can amplify the destabilizing effect of environmental variability on ecosystem functions such as productivity, whereas the inverse, compensatory dynamics, can stabilize function. Here we combine simulation and empirical analyses to elucidate mechanisms that underlie patter...
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Process‐explicit models reveal pathway to extinction for woolly mammoth using pattern‐oriented validationNARA Subscribed
Pathways to extinction start long before the death of the last individual. However, causes of early stage population declines and the susceptibility of small residual populations to extirpation are typically studied in isolation. Using validated process‐explicit models, we disentangle the ecological mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth. We show that reconci...
The spatial synchrony of species richness and its relationship to ecosystem stabilityNARA Subscribed
Synchrony is broadly important to population and community dynamics due to its ubiquity and implications for extinction dynamics, system stability, and species diversity. Investigations of synchrony in community ecology have tended to focus on covariance in the abundances of multiple species in a single location. Yet, the importance of regional environmental variation and spatial processes in community dynamics suggests that c...
Spatial rarity is often used to predict extinction risk, but rarity can also occur temporally. Perhaps more relevant in the context of global change is whether a species is core to a community (persistent) or transient (intermittently present), with transient species often susceptible to human activities that reduce niche space. Using 5–12 yr of data on 1,447 plant species from 49 grasslands on five continents, we show that lo...
High rates of land conversion and land use change have vastly increased the proportion of secondary forest in the lowland tropics relative to mature forest. As secondary forests recover following abandonment, nitrogen (N) and phosphorus (P) must be present in sufficient quantities to sustain high rates of net primary production and to replenish the nutrients lost during land use prior to secondary forest establishment. Biogeoc...
Columnaris disease can be problematic in tilapia ( O reochromis spp.) production. An understanding of the pathogenesis and virulence of F lavobacterium columnare is needed to develop prevention strategies. The objective of this study was to determine the virulence of genetically defined isolates of F . columnare in sex‐reversed hybrid tilapia, O reochromis niloticus ( L .) × O . aureus ( S teindachner). A series of immersion c...
Intragenomic heterogeneity in the 16 S r RNA genes of F lavobacterium columnare and standard protocol for genomovar assignmentNARA Subscribed
Genetic variability in 16 S r RNA gene sequences has been demonstrated among isolates of F lavobacterium columnare, and a restriction fragment length polymorphism ( RFLP ) assay is available for genetic typing of this important fish pathogen. Interpretation of restriction patterns can be difficult due to the lack of a formal description of the expected number and sizes of DNA fragments generated for each of the described genom...
Streptococcus iniae is a significant pathogen impacting aquaculture production worldwide. The objectives of this study were to determine whether a developed modified S. iniae (ARS‐98‐60) bacterin vaccine is efficacious in Nile tilapia, Oreochromis niloticus (L.), against challenge with heterologous isolates from diverse geographical locations and to evaluate protein and antigenic variability among the isolates tested. Two grou...
Using quantitative PCR (QPCR), the relative transcriptional levels of five toll‐like receptors (TLR2, TLR3, TLR5, TLR20a and TLR21) were studied in the channel catfish, Ictalurus punctatus (Rafinesque), under uninfected and acutely infected conditions [1‐, 2‐, 4‐, 6‐, 12‐, 24‐, 36‐ and 48‐h post‐injection (hpi)]. Under uninfected conditions, the transcriptional levels of the five TLRs were significantly lower than that of 18S...
Lactococcus garvieae infection in cultured Nile tilapia, Oreochromis niloticus (L.), and pintado, Pseudoplathystoma corruscans (Spix & Agassiz), from Brazil is reported. The commercial bacterial identification system, Biolog Microlog ® , confirmed the identity of L. garvieae . Infectivity trials conducted in Nile tilapia using Brazilian Nile tilapia L. garvieae isolates resulted in a median lethal dose‐50 of 1.4 × 10 5 colony‐...
The chemoattractant capabilities of Edwardsiella tarda extracellular products (ECP) were investigated from two isolates, the virulent FL6‐60 parent and less virulent RET‐04 mutant. Chemotaxis and chemokinesis were assayed in vitro using blind well chambers with peritoneal macrophages obtained from Nile tilapia, Oreochromis niloticus , 5 days following squalene injection. Non‐purified ECP derived from both isolates stimulated p...
Evaluation of the link between gyrodactylosis and streptococcosis of Nile tilapia, Oreochromis niloticus (L.)NARA Subscribed
Streptococcus iniae and Gyrodactylus niloticus are two common pathogens of cultured Nile tilapia, Oreochromis niloticus . We studied concurrent infection of tilapia by G. niloticus and S. iniae and evaluated whether parasitism in tilapia with Gyrodactylus increased susceptibility and mortality following immersion infection with S. iniae . Results showed that death mainly occurred in fish with G. niloticus and challenged with S...
Comparison of lipopolysaccharide and protein profiles between Flavobacterium columnare strains from different genomovarsNARA Subscribed
Lipopolysaccharide (LPS) and total protein profiles from four Flavobacterium columnare isolates were compar. These strains belonged to genetically different groups and/or presented distinct virulence properties. Flavobacterium columnare isolates ALG‐00‐530 and ARS‐1 are highly virulent strains that belong to different genomovars while F. columnare FC‐RR is an attenuated mutant used as a live vaccine against F. columnare . Stra...