Many species are threatened with extinction and efforts are underway worldwide to restore imperilled species to their native ranges. Restoration requires knowledge of species' historical diversity and distribution. For some species, many populations were extirpated or individuals moved beyond their native range before native diversity and distribution were documented, resulting in a lack of accurate information for establishing restoration goals. Moreover, traditional taxonomic assessments often failed to accurately capture phylogenetic diversity. We illustrate a general approach for estimating regional native diversity and distribution for cutthroat trout in the Southern Rocky Mountains. We assembled a large archive of historical records documenting human-mediated change in the distribution of cutthroat trout (Oncorhynchus clarkii) and combined these data with phylogenetic analysis of 19th century samples from museums collected prior to trout stocking activities and contemporary DNA samples. Our study of the trout in the Southern Rocky Mountains uncovered six divergent lineages, two of which went extinct, probably in the early 20th century. A third lineage, previously declared extinct, was discovered surviving in a single stream outside of its native range. Comparison of the historical and modern distributions with stocking records revealed that the current distribution of trout largely reflects intensive stocking early in the late 19th and early 20th century from two phylogenetically and geographically distinct sources. Our documentation of recent extinctions, undescribed lineages, errors in taxonomy and dramatic range changes induced by human movement of fish underscores the importance of the historical record when developing and implementing conservation plans for threatened and endangered species.

The autoradiographic identification of unscheduled DNA synthesis (UDS) in primary cultures of adult rat hepatocytes (HPC) has been proposed as a predictive test for mutagens/carcinogens. To assess the predictive value of this test, results in the hepatocyte UDS assay were compared with data for bacterial mutagenicity using a modified Ames test. Over 200 compounds representing a variety of chemical classes consisting of procarcinogens, ultimate carcinogens, and noncarcinogens were tested in each system. The accurate discrimination of many carcinogens/noncarcinogens was demonstrated by both systems. The induction of UDS in hepatocytes showed an excellent correlation with bacterial mutagenesis in response to polycyclic aromatic hydrocarbons, aromatic amines, biphenyls, nitrosamines, carbamates, azo-compounds, acridines, halogenated compounds, nitrosureas, quinolines, pyridines, purines, pyrimidines, esters and carbamates. Nitrocompounds, although active in bacteria, were poor inducers of UDS. The results support the complementary and confirmatory nature of these tests for genotoxic chemicals and indicate the usefulness of the hepatocyte UDS system as a component in a battery of short-term predictive tests for mutagens/carcinogens.

Single-round polymerase chain reaction (PCR) and pepsin-trypsin digest (PTD) methods were compared for the detection of Myxobolus cerebralis. Parallel tests were conducted on a total of 1743 free-ranging and 400 hatchery-reared salmonids. Concurrent results were found in 84.6% of the free-ranging fish samples, and 83.5% of the hatchery samples. PCR identified M. cerebralis more frequently than did PTD, and did so in many geographic locations previously considered free of the parasite. Average myxospore count by PTD among both free-ranging and hatchery fish increased significantly (p < 0.001) with a subjective evaluation of amplicon staining intensity. KEY WORDS: Whirling disease · Myxobolus cerebralis · Pepsin-trypsin digest (PTD) · Polymerase chain reaction (PCR) · Testing methods Resale or republication not permitted without written consent of the publisherDis Aquat Org 45: [109][110][111][112][113][114] 2001 the parasite in all life stages, thus eliminating reliance on isolation of mature myxospores. The procedure is also much less labor-intensive and more efficient than traditional methods.The single-round PCR method is a modification of the nested PCR procedure published by Andree et al. (1998) that is reported to have the advantages of decreased likelihood of contamination and reduced expenses associated with time, reagents, materials and labor (Epp & Wood 1998). This method relies on the use of a modified Tr 5-16 primer (Tr 5-16m) and the Tr 3-17 primer from the nested procedure. Tr 5-16 is used as the forward primer in the first round of the nested PCR procedure, while the Tr 5-16m primer is used as the sole forward primer in the single-round PCR procedure. Tr 3-17 is used as the reverse primer in the second round of the nested PCR procedure, and as the sole reverse primer in the single-round PCR procedure.PCR testing has not been benchmarked as a standard diagnostic technique for detecting Myxobolus cerebralis, and its practicality and reliability is the subject of much debate (United States Animal Health Association 1998). Much of the controversy surrounding PCR techniques is the ability of the procedure to detect genomic material of the target organism that may or may not have been derived from a living pathogen. Many people have argued that genomic evidence is not biologically significant. The extreme sensitivity of the technique also makes it prone to contamination resulting in false positive results. Further concern over the use of the technique is the possibility that DNA fragments from related organisms could be amplified and falsely identified as the target organism. Free-ranging fish stocks are often, and many times needlessly, considered at risk of collapse once identified as M. cerebralis positive. Fish rearing units producing fish thought to be infected with the parasite are considered tainted, and even a suggestion of M. cerebralis infection greatly reduces the value and marketability of these fish. PCR is being used for detection of many bacterial fish pathogens, including A...

Elucidating the dynamics of a parasitic infection requiring two hosts in a natural ecosystem can be a daunting task. Myxobolus cerebralis (Mc), the myxozoan parasite that causes whirling disease in some salmonids, was detected in the Colorado River upstream of Windy Gap Reservoir (WGR) in 1988. Subsequently, whirling disease was implicated in the decline of wild Rainbow Trout Oncorhynchus mykiss in the river when WGR was identified as a point source of Mc triactinomyxons (TAMs). Between 1997 and 2004, numerous investigations began to elucidate the etiology of Mc in WGR. During this period, Mc TAM production in WGR declined more than 90%. Explanations for the decline have included differences in stream discharge between years, changes in the thermal regime of the lake, severe drought, changes in the fish population structure in WGR, and reductions in the prevalence and severity of Mc infection in salmonids in the Colorado and Fraser rivers upstream of WGR. All of these have been discredited as explanations for the reduced TAM production. In 2005, a new study was conducted to replicate the studies completed in 1998. In this paper, the results of a new real-time polymerase chain reaction assay utilized to quantify the mitochondrial 16S rDNA specific to each of four lineages of Tubifex tubifex in pooled samples of 50 oligochaetes are presented. These results suggest that compared with 1998, the densities of aquatic oligochaetes and T. tubifex have increased, TAM production has been greatly reduced, and the decline is congruent with the dominance of lineages I, V, and VI of T. tubifex-three lineages that are refractory or highly resistant to Mc infection-in the oligochaete population. While it is possible that the resistant lineages function as biofilters that deactivate Mc myxospores, the reason for the decline in TAM production in WGR remains an enigma.

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