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Significance and Impact of the Study: This is the first report of a loop-mediated isothermal amplification (LAMP) assay for simple and cost-effective detection of E. rhusiopathiae from swine samples. The LAMP assay provided more rapid detection of the bacterium than conventional PCR and biochemicalbased assays, and it may potentially facilitate surveillance and early diagnosis of swine erysipelas in the field. AbstractErysipelothrix rhusiopathiae is a causative agent of swine erysipelas. We developed a novel and highly specific loop-mediated isothermal amplification (LAMP) assay for sensitive and rapid detection of E. rhusiopathiae. The LAMP assay correctly detected 39 E. rhusiopathiae strains. No LAMP products were detected from 14 non-rhusiopathiae Erysipelothrix and 16 non-Erysipelothrix strains, including E. tonsillarum serovar 10 strains, which are difficult to be discriminated from E. rhusiopathiae strains. These results were consistent with those obtained by a conventional E. rhusiopathiae-specific PCR assay. Starting with DNA extraction from a single colony, the gel-based PCR assay took 4 h to provide a result, but the LAMP assay was faster, requiring only 37-80 min. The conventional culture test required more than 3-4 days to isolate and identify E. rhusiopathiae in the enrichment cultures. In contrast, the LAMP assay required less than 22 h from the beginning of the enrichment culture to final determination. These results suggest that the LAMP assay is useful as an adjunct to facilitate early diagnosis of swine erysipelas.

The quantification of histidine-containing dipeptides (anserine, carnosine, and balenine) in serum might be a diagnostic tool to assess the health condition of animals. In this study, an existing reversed-phase ion-pair high-performance liquid chromatography (HPLC)–ultraviolet detection method was improved and validated to quantify serum anserine, carnosine, and balenine levels in the dolphin. The serum was deproteinized with trichloroacetic acid and directly injected into the HPLC system. Chromatographic separation of the three histidine-containing dipeptides was achieved on a TSK–gel ODS-80Ts (4.6 mm × 150 mm, 5 µm) analytical column using a mobile phase of 50 mmol/L potassium dihydrogen phosphate (pH 3.4) containing 6 mmol/L 1-heptanesulfonic acid and acetonitrile (96:4). The standard curve ranged from 0.1 µmol/L to 250 µmol/L. The average accuracy of the intra- and inter-analysis of anserine, carnosine, and balenine was 97–106%. The relative standard deviations of total precision (RSDr) of anserine, carnosine, and balenine in dolphin serum were 5.9%, 4.1%, and 2.6%, respectively. The lower limit of quantification of these compounds was 0.11–0.21 µmol/L. These results indicate that the improved method is reliable and concise for the simultaneous determination of anserine, carnosine, and balenine in dolphin serum, and may be useful for evaluation of health conditions in dolphins. Furthermore, this method can also be applied to other biological samples.

Lobomycosis is a chronic fungal disease caused by the etiologic agent, Lacazia loboi, in the skin and subcutaneous tissues in humans and dolphins in tropical and transitional tropical climates. An Indo-Pacific bottlenose dolphin (Tursiops aduncus) stranded in Kagoshima, Japan, had severe skin lesions characterized by granulomatous reactions and hyperkeratosis that were similar to those of the lobomycosis, but no fungal organism was observed in the skin lesion. In this paper, we report a stranded Indo-Pacific bottlenose dolphin with lobomycosis-like lesions based on pathological examinations in Japan.

In comparison with terrestrial animals, such as primates, there is limited empirical evidence for cooperative behavior in marine mammals under experimental conditions. In this study, we used a cooperative rope-pulling task to investigate how bottlenose dolphins (Tursiops truncatus) coordinate their behavior with a partner. Dolphins successfully learned and were able to perform the task, even when one subject started after the other. In the no-delay condition (i.e., both subjects sent at the same time), one pair of dolphins showed coordinated behaviors. When pairs were successful in solving the task in the delay condition (i.e., one individual sent later than the other), the initiators (i.e., first individual sent) were likely to wait for the follower to arrive, and the follower was likely to swim faster when the initiator did not wait and started pulling the rope alone. These coordinated behaviors might help resolve the given cooperative task. Our results suggest that bottlenose dolphins learn to coordinate their behaviors via trial and error and recognize the necessity of performing simultaneous actions with a partner to successfully accomplish cooperative tasks. In addition, both partners showed behavioral changes over many trials of no-delay and delay conditions, suggesting that bidirectional coordination occurred in the cooperative task.