Performing Department
Microbiology
Non Technical Summary
On 19th June, 2017, steers on a ranch 10 miles west of Lakeview, OR, began dying on the margins of Junipers Reservoir, an impoundment of 175 acres on the ranch. Most deaths accumulated rapidly, but additional cattle died over the following two days. An intense algal bloom had accumulated at the south end of the reservoir (X in Fig. 1), concentrated by persistent northerly wind. Cattle had been using the reservoir for drinking water and some were seen to have accumulated blue-green scum on their legs. In the end, thirty-one 14-month-old steers, worth some $50,000, had died.The recent event is significant because of the large number of animals lost and the involvement of Anabaena as the putative toxin-producing cyanobacterium. Although some Anabaena strains are known to be capable of microcystin production, this genus is not usually considered as a lethal source (high level production) of this toxin. Information gathered from this project will better inform our understanding of the potential of this particular cyanobacteria to produce toxins and potentially harm livestock and fish and wildlife.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
100%
Goals / Objectives
Death in farm animals from the above cyanobacterial toxins is reported on a recurring basis, and farm animal health bulletins in many states and overseas countries warn of such occurrences. Fortunately, the numbers ofaffected stock are usually small and infrequent, although there is likely under-reporting among rangelandstock. Deaths in cattle from microcystin have been described in the literature, including the death of 4 animalsin Georgia (Frazier et al., 1998), 9 dairy cows in Illinois (Galey et al., 1987) and 24 heifers in Colorado(Puschner et al., 1998), all due to a Microcystis blooms. The recent event is significant because of the largenumber of animals lost and the involvement of Anabaena as the putative toxin-producing cyanobacterium.Although some Anabaena strains are known to be capable of microcystin production, this genus is not usuallyconsidered as a lethal source (high level production) of this toxin. In order for farmers (and public healthagencies) to be aware of this potential danger of Anabaena, it is important for this event to be documentedand a report published in the scientific literature.To establish the genetic identity of the producing organism of the microcystin toxin responsible for killing 31 steers drinking water from Junipers Reservoir.To publish the genetic identification of the producer and the observations surrounding the deaths in at least one peer reviewed journal.
Project Methods
Establishing the identity of a toxin producer has traditionally involved culturing the organism and demonstrating toxin production from pure culture. That can be a lengthy procedure that is sometimes made difficult by inabilty to culture some organisms. We have recently shown (Brown et al., 2016; Otten et al., 2015) that genetic approaches are powerful in identifying the presence of genes associated with toxin production by cyanobacteria, and associating those genes with the producing organism. Advantages of this approach include (i) avoiding the need for time-consuming culture establishment, (ii) determining whether there is only one (or more than one) toxin-producing cyanobacterium present, (iii) determining whether any other cyanotoxin genes are present, (iv) identifying genome sequences that allow genetic assays and monitoring to be conducted in tracking future blooms, and (v) learning about the physiological and biochemcial properties of the toxin producer from its gene content. Two Junipers Reservoir bloom samples are available for genetic analysis. One sample was accidentally held warm over a weekend because of a shipping problem, and was partially degraded. Nevertheless, large amounts of Anabaena colonies are present (Fig. 2), with no indication of Microcystis, although some cyanobacteria that were initially present may have been lost. The second sample is a split of the reservoir water tested by UC-Davis to contain 3000 ppb microcystin. It has been frozen, which had led to the rupture of all cells except the very resistant spore-like akinetes (prominent in Fig. 2), but should have better preserved DNA becusse the sample was always cold. Because of these problems, both samples will need to be analyzed genetically as a check that no cyanotoxin producers are missed.DNA will be extracted from the samples and processed for metagenome analysis, with high-throughput DNA sequencing conducted by the Central Services Laboratory of the Oregon State University Center for Genome Research and Biocomputing. We are familiar with this methodology (Brown et al., 2016; Otten et al., 2015). Metagenome analysis refers to the recovery of essentially all DNA sequences that are present in a sampleabove a background threshold. More abundant genomes are more highly represented. This is a better approach than using polymerase chain reaction (PCR) targetting known genes because it is an open-minded approach that avoids the reliance on previously identified precise sequences that is a pre-requisite of PCR.