ALTERNATE FOOD-CHAIN TRANSFER OF THE TOXIN LINKED TO AVIAN VACUOLAR MYELINOPATHY AND IMPLICATIONS FOR THE ENDANGERED FLORIDA SNAIL KITE (ROSTRHAMUS SOCIABILIS)

Gross and histopathological findings in hindlimb paralysis syndrome in wild Carnaby's black cockatoos (Zanda laitirostris)

The aim of this study was to describe the gross and histopathological features of a neurological syndrome in endangered Western Australian Carnaby's black cockatoos (Zanda laitirostris) that was first observed in 2012. The syndrome, named hindlimb paralysis syndrome in Carnaby's cockatoos (CHiPS), is characterized by annual outbreaks of hindlimb paralysis with occasional loss of deep pain and cloacal tone, typically occurring between January and March. Previous limited investigations suggested a possible toxic aetiology. Full gross necropsy and histopathology examinations were performed on 17 CHiPS cases and on 11 control birds for reference. Histopathological examination was carried out on all major organs including brain, spinal cord, brachial plexus, sciatic nerve and wing and hindlimb muscles. Gross and histopathological examinations did not elucidate a definitive cause of the clinical signs seen in CHiPS cases. There were no substantial gross or histopathological changes within the brain, spinal cord, sciatic nerve or brachial plexus that could explain the hindlimb paralysis. The most noteworthy changes were seen in the hindlimb and wing muscles, with a monophasic to polyphasic myopathy present in the hindlimb muscles of 15 of the 17 CHiPS cases and in the wing muscles in 11 of those cases. The cause and significance of the myopathy is unclear and requires further investigation. Based on the above findings, the most likely differential diagnoses include neurotoxicoses (eg, organophosphate, organochlorine and carbamate) and, less likely, myotoxicosis (eg, ionophore toxicosis), nutritional myopathy (eg, vitamin E/selenium deficiency) or botulism.

Occurrence of aetokthonotoxin producer in natural samples - A PCR protocol for easy detection

Cyanobacteria are well known producers of bioactive metabolites, including harmful substances. The recently discovered "eagle killer" neurotoxin aetokthonotoxin (AETX) is produced by the epiphytic cyanobacterium Aetokthonos hydrillicola growing on invasive water thyme (Hydrilla verticillata). The biosynthetic gene cluster of AETX was previously identified from an Aetokthonos strain isolated from the J. Strom Thurmond Reservoir, Georgia, USA. Here, a PCR protocol for easy detection of AETX-producers in environmental samples of plant-cyanobacterium consortia was designed and tested. Three different loci of the AETX gene cluster were amplified to confirm the genetic potential for AETX production, along with two variable types of rRNA ITS regions to confirm the homogeneity of the producer´s taxonomic identity. In samples of Hydrilla from three Aetokthonos-positive reservoirs and one Aetokthonos-negative lake, the PCR of all four loci provided results congruent with the Aetokthonos presence/absence detected by light and fluorescence microscopy. The production of AETX in the Aetokthonos-positive samples was confirmed using LC-MS. Intriguingly, in J. Strom Thurmond Reservoir, recently Hydrilla free, an Aetokthonos-like cyanobacterium was found growing on American water-willow (Justicia americana). Those specimens were positive for all three aet markers but contained only minute amounts of AETX. The obtained genetic information (ITS rRNA sequence) and morphology of the novel Aetokthonos distinguished it from all the Hydrilla-hosted A. hydrillicola, likely at the species level. Our results suggest that the toxigenic Aetokthonos spp. can colonize a broader array of aquatic plants, however the level of accumulation of the toxin may be driven by host-specific interactions such as the locally hyper-accumulated bromide in Hydrilla.

Comparative Assessment of Cadmium and Copper Toxicity to Physa acuta (Draparnaud, 1805)

Cadmium and copper toxicity was investigated using bioassays with neonates of a freshwater gastropod Physa acuta. Mortality, lethal time, and effects on shell length were studied during 28-day chronic exposure experiments. Relative toxicity was assessed from acute and chronic LC values. Copper showed significantly more toxicity at lower concentrations than cadmium ([Formula: see text] < 0.001), causing mortality at the same response levels. Conversely, cadmium affected shell length at lower concentrations than copper, although no significant differences ([Formula: see text] > 0.05) were found in affected shell length between copper and cadmium at the end of the assays. Lethal time (LT[Formula: see text]) was significantly affected by metal concentration ([Formula: see text] < 0.001), with a reduction of 8.28% and 5.90% in time per 0.001 mg/L increase of copper and cadmium, respectively. Physa acuta neonates showed medium to high sensitivity to cadmium and copper compared to other freshwater gastropod species, showing it is a suitable test organism, particularly for chronic ecotoxicological assessment.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors-especially bromide availability-that promote toxin production.

Satellite monitoring of cyanobacterial harmful algal bloom frequency in recreational waters and drinking source waters

Cyanobacterial harmful algal blooms (cyanoHAB) cause extensive problems in lakes worldwide, including human and ecological health risks, anoxia and fish kills, and taste and odor problems. CyanoHABs are a particular concern in both recreational waters and drinking source waters because of their dense biomass and the risk of exposure to toxins. Successful cyanoHAB assessment using satellites may provide an indicator for human and ecological health protection, In this study, methods were developed to assess the utility of satellite technology for detecting cyanoHAB frequency of occurrence at locations of potential management interest. The European Space Agency's MEdium Resolution Imaging Spectrometer (MERIS) was evaluated to prepare for the equivalent series of Sentine1-3 Ocean and Land Colour Imagers (OLCI) launched in 2016 as part of the Copernicus program. Based on the 2012 National Lakes Assessment site evaluation guidelines and National Hydrography Dataset, the continental United States contains 275,897 lakes and reservoirs >1 hectare in area. Results from this study show that 5.6 % of waterbodies were resolvable by satellites with 300 m single-pixel resolution and 0.7 % of waterbodies were resolvable when a three by three pixel (3×3-pixel) array was applied based on minimum Euclidian distance from shore. Satellite data were spatially joined to U.S. public water surface intake (PWSI) locations, where single-pixel resolution resolved 57% of the PWSI locations and a 3×3-pixel array resolved 33% of the PWSI locations. Recreational and drinking water sources in Florida and Ohio were ranked from 2008 through 2011 by cyanoHAB frequency above the World Health Organization's (WHO) high threshold for risk of 100,000 cells mL-1. The ranking identified waterbodies with values above the WHO high threshold, where Lake Apopka, FL (99.1 %) and Grand Lake St. Marys, OH (83 %) had the highest observed bloom frequencies per region. The method presented here may indicate locations with high exposure to cyanoHABs and therefore can be used to assist in prioritizing management resources and actions for recreational and drinking water sources.