Hamartoma affecting ampullary electroreceptors and epitheliotropic lymphoma in a captive electric eel Electrophorus varii

Few reports are available describing lesions in captive electric eels Electrophorus spp. This report describes 2 types of cutaneous proliferative lesions (i.e. hamartoma and neoplasm) in a captive electric eel. Ampullary electroreceptor hamartomas appeared grossly as 2 discrete, smooth, pink, spherical, cutaneous masses measuring 6 and 18 mm in diameter. Histologically, hamartomas were composed of predominately spindle cells that were separated into lobules by a peripheral rim of polygonal cells. Spindle cells were arranged in vague streams and occasionally whorls within a myxomatous matrix. Polygonal cells arranged in variably sized trabeculae and cords within a pre-existing fibrovascular stroma surrounded the streams of spindle cells. Admixed with the polygonal cell population were multiple mucous glands and alarm cells, similar to those seen in normal regions of epidermis. Histochemical stains confirmed similar components in the normal ampullary electroreceptor as in the hamartomas. Lymphoma was also present, appearing grossly as patchy pitting, erythematous, and thickened areas of the skin affecting the entire animal. Lymphoma was diffusely infiltrating and expanding the epidermis, oral mucosa, and branchial mucosa up to 1.5 mm in thickness. It was composed of an unencapsulated, well-demarcated, moderately cellular neoplasm composed of lymphocytes arranged in small dense sheets and clusters that separated and effaced epidermal cells. This is the first report of lymphoma in an electric eel, and the first report of ampullary electroreceptor hamartoma in any animal species.

Electric organ discharge from electric eel facilitates DNA transformation into teleost larvae in laboratory conditions

Background

Electric eels (Electrophorus sp.) are known for their ability to produce electric organ discharge (EOD) reaching voltages of up to 860 V. Given that gene transfer via intense electrical pulses is a well-established technique in genetic engineering, we hypothesized that electric eels could potentially function as a gene transfer mechanism in their aquatic environment.

Methods

To investigate this hypothesis, we immersed zebrafish larvae in water containing DNA encoding the green fluorescent protein (GFP) and exposed them to electric eel's EOD.

Results and Discussion

Some embryos exhibited a mosaic expression of green fluorescence, in contrast to the control group without electrical stimulation, which showed little distinct fluorescence. This suggests that electric eel EOD has the potential to function as an electroporator for the transfer of DNA into eukaryotic cells. While electric eel EOD is primarily associated with behaviors related to sensing, predation, and defense, it may incidentally serve as a possible mechanism for gene transfer in natural environment. This investigation represents the initial exploration of the uncharted impact of electric eel EOD, but it does not directly establish its significance within the natural environment. Further research is required to understand the ecological implications of this phenomenon.

Eponymous plot of Richard J. Kitz and Irwin B. Wilson in biochemistry

Irwin B. Wilson and anesthesiologist Richard J. Kitz found the enzyme acetylcholinesterase to be inactivated in two steps by covalently acting molecules resembling acetylcholine in structure. Such molecules rapidly and reversibly bind to the active site of the enzyme. Next, the reversible complex undergoes covalent fixation at a characteristic rate. The Kitz-Wilson phenomenon applies to many cases of time-dependent enzyme inhibition. Experimental data are commonly graphed in linear fashion on "Kitz-Wilson plots". Kitz also contributed to a gas chromatography-mass spectrometry assay for acetylcholine that was suitable for the nonbiological detection of that neurotransmitter in mammalian brain.