The effect of predation on native fish by introduced species in the San Francisco Estuary-Delta (SFE) has not been thoroughly studied despite its potential to impact species abundances. Species-specific quantitative PCR (qPCR) is an accurate method for identifying species from exogenous DNA samples. Quantitative PCR assays can be used for detecting prey in gut contents or faeces, discriminating between cryptic species, or detecting rare aquatic species. We designed ten TaqMan qPCR assays for fish species from the SFE watershed most likely to be affected by non-native piscivores. The assays designed are highly specific, producing no signal from co-occurring or related species, and sensitive, with a limit of detection between 3.2 and 0.013 pg/μL of target DNA. These assays will be used in conjunction with a high-throughput qPCR platform to compare predation rates between native and non-native piscivores and assess the impacts of predation in the system.

Several factors affect the probability of genetic analyses to detect prey in predator gut contents, including biological differences in the prey and predator species as well as differences in sampling and laboratory methodologies. Understanding these biases allows researchers to more appropriately put genetic prey detections in an ecological context. In this study, we determined the detectability half‐lives of DNA from two prey species in the guts of two predators. The half‐life detectability of juvenile Chinook Salmon Oncorhynchus tshawytscha in Striped Bass Morone saxatilis was 66.2 h, and that of larval Delta Smelt Hypomesus transpacificus in Mississippi Silverside Menidia audens was 26.4 h. Additionally, we performed a series of laboratory trials to examine the effects of variables in sample collection and preservation methodologies on the detectability of prey. Differences between methodologies were minimal, providing confidence that laboratory analyses will not be greatly affected by inconsistencies in field sampling procedures. Injecting a 95% solution of ethanol into the stomach via the esophagus immediately following collection and placing the fish on ice in the field prior to freezing at −20°C in the laboratory is a protocol readily applied in the field that will provide consistent results. Received August 19, 2015; accepted December 3, 2015 Published online April 11, 2016

The establishment of non-native predator fish is a worldwide phenomenon often having adverse effects on native species. Trophic interactions are complex, and uncertainty is a common theme in discussions of non-native predator management. Several fishes of the San Francisco Estuary have experienced significant declines in recent decades due to multiple factors, including habitat alteration and predation. The role of predation as a direct cause of mortality remains an open question, as does whether habitat conditions play a role in promoting predation on species of concern. Recent studies using visual identification of prey have found little to no evidence of predation on ESA-listed species such as Delta Smelt Hypomesus transpacificus and juvenile Chinook Salmon Oncorhynchus tshawytscha. To increase the likelihood of detecting predation, this study employed a genetic approach. We combined this technique with habitat and water quality data to investigate the role habitat may be playing on incidence of predation. This study focused on detection of predation on Chinook Salmon and Delta Smelt, as well as 6 other native fishes, and 6 non-native fishes by Striped Bass Morone saxatilis, and other piscivores. Unlike previous studies in the region, the proportion of predators with no prey detected in their gut contents was high (47-81%). The study detected Delta Smelt in 1.3% of Striped Bassconsiderably higher than other contemporary predation studies in the Delta. In the month of April 2014, 6.6% of Striped Bass were positive for Chinook Salmon-substantially higher than recent visual diet studies in the Delta. Interestingly, native species comprised a relatively high proportion of Striped Bass prey (60%). Water temperature and conductivity were identified as significant predictors of Chinook Salmon presence in Striped Bass gut contents. This research

Canine transmissible venereal tumor (CTVT) is a transmissible cancer that affects the external genitalia of dogs. In this study, a female canine with CTVT in the vagina was treated with vincristine (0.75 mg/m 2 ; intravenous (IV); weekly for eight cycles), the currently preferred drug for CTVT, but without any progress. Therefore, this case was considered resistant to vincristine, and the preferred alternative chemotherapy, doxorubicin, was suggested. However, based on echocardiographic evidence, the patient could not be administered doxorubicin. Thus, the administration of lomustine was proposed. Although there are no studies to support this decision, the authors based their decision on the fact that lomustine is effective for round cell tumors, and that CTVT belongs to this tumor group. After three doses (60 mg/m 2 ; every 3 weeks) complete remission was achieved. The use of lomustine at a dose of 60 mg/m 2 every 3 weeks for vincristine-resistant CTVT proved to be effective, without any harmful side effects. The treatment is cost-effective and simple to manage.

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