A glycogen synthase 1 mutation associated with equine polysaccharide storage myopathy and exertional rhabdomyolysis occurs in a variety of UK breeds

Reasons for performing study: A glycogen synthase (GYS1) mutation has been described in horses with histopathological evidence of polysaccharide storage myopathy (PSSM) in the USA. It is unknown whether the same mutation is present in horses from the UK. Objectives: To determine whether the GYS1 mutation occurs in UK horses with histopathological evidence of PSSM and exertional rhabdomyolysis. Hypothesis: The R309H GYS1 mutation is present in a variety of UK horse breeds and that the mutation is commonly associated with exertional rhabdomyolysis. Methods: DNA was extracted from 47 muscle or blood samples from UK horses with histories of exertional rhabdomyolysis in which muscle biopsy diagnosis had been pursued. The proportions of GYS1 mutation positive cases were compared among histopathologically defined groups. In addition, breeds that carried the GYS1 mutation were identified from a total of 37 grade 2 (amylase‐resistant) PSSM cases. Results: Of 47 horses with exertional rhabdomyolysis in which a muscle biopsy diagnosis was pursued, 10 (21%) carried the GYS1 mutation. The mutation was only found in horses with grade 2 PSSM (i.e. not in horses with normal, idiopathic myopathy or grade 1 PSSM biopsy samples). In total, the GYS1 mutation was found in 24/37 (65%) of grade 2 PSSM cases. A variety of breeds, including Quarter Horse, Appaloosa, Warmblood, Connemara‐cross, Cob, Polo Pony and Thoroughbred cross carried the mutation. Conclusions: The GYS1 mutation is an important cause of exertional rhabdomyolysis of UK horse breeds but does not account for all forms of PSSM. Potential relevance: Genotyping is recommended in cases of exertional rhabdomyolysis, prior to or in combination with, muscle biopsy. However a significant proportion of horses with histopathological evidence of PSSM and/or exertional rhabdomyolysis have different diseases.     

Inorganic nitrogen removal from wastewater: effect on phytoplankton growth in coastal marine waters

Algal bioassays were used to demonstrate the high efficiency of a comnbined tertiary wastewater treatment and marine aquaculture system in removing inorganic nitrogen, and to show that the coastal waters off Woods Hole, Massachusetts, are limited in nitrogen for marine phytoplankton growth. When nutrients were removed from secondarily treated domestic wastewater through assimilation by phytoplankton in an outdoor growth pond, the pond effluent, in varying dilutions with seawater, could not support more phytoplankton growth than the seawater alone. However, when nitrogen was added back to the mixtures of pond effluent and seawater, the phytoplankton growth response was similar to that with a mixture of wastewater and seawater. This is similar to the findings of other researchers, and suggests that nitrogen may be the key growth-limiting nutrient in many coastal marine waters. The combined tertiary treatment-marine aquaculture system appears to be an effective means of removing nitrogen from secondarily treated wastewater and controlling eutrophication of coastal marine waters.     

Catalase and ascorbate peroxidase activities are not directly involveded in the silicon‐mediated alleviation of ferrous iron toxicity in rice

Silicon (Si) is the second most abundant element in the soil and can alleviate several abiotic stresses in many plant species. However, the mechanisms involved in alleviating ferrous iron (Fe²⁺) toxicity by Si are still largely unknown, and no study has investigated the role of Si on the Fe²⁺‐induced oxidative stress and antioxidant system in rice. Four cultivars of Asian and African rice (Oryza sativa L. and Oryza glaberrima Steud) were grown for 4 weeks under hydroponic conditions with or without Fe²⁺ (250 mg Fe²⁺ L^?1) and with or without Si (250 mg SiO₂ L^?1). The plants that were treated with Fe²⁺ suffered Fe²⁺ toxicity, and Si helped to alleviate the toxicity symptoms. The bronzing index and the Fe concentration in the foliar tissue increased in the presence of Fe²⁺ but decreased significantly with the application of 250 mg SiO₂ L^?1. The concentration of malonyldialdehyde, that is commonly used as an indicator of oxidative stress, increased in the foliar tissue in the presence of 250 mg Fe²⁺ L^?1 in the nutrient solution. The application of 250 mg SiO₂ L^?1 in the plant nutrient solution treated with Fe²⁺ considerably limited the increase of malonyldialdehyde. However, no significant effect of Si application on the activities of antioxidant enzymes (catalase and ascorbate peroxidase) and non‐enzymatic antioxidants (total ascorbate, reduced ascorbate, oxidized ascorbate, and the ratio of the reduced to oxidized forms) was observed in the rice plants that were grown in the presence of Fe²⁺. These results suggest that Si does not act directly on the antioxidant defense system of rice but reduces the plant Fe²⁺ concentration, which reduces the oxidative stress.     

INFLUENCE OF NEONICOTINOID INSECTICIDES ON THE PLANT GROWTH ATTRIBUTES OF COTTON AND OKRA

Neonicotinoids are crop protection agents used against sucking pests acting on receptor proteins of insect nervous system. Although many reports detail their insecticidal properties, reports on the effect on plant growth are minimal. We investigated the effect of neonicotinoids viz. imidacloprid, thiamethoxam, acetamiprid and thiacloprid on plant height, chlorophyll, and soluble protein of cotton and okra. Thiamethoxam was found to exert an influence on the plant height of cotton and okra. There was no marked influences of neonicotinoids on the total chlorophyll content of cotton leaves, whereas acetamiprid recorded a gradual increase in the total chlorophyll content of okra leaves at 7, 14 and 21 days after treatment. All the neonicotinoid insecticides under study showed an increase in the soluble protein content of cotton and okra. An increase in soluble protein content is reported to increase the ability of plants to fix carbon dioxide (CO₂) effectively and thus increase photosynthesis.     

Impact of sludge residence time on the relative biodegradation and biosorption of sulfonamide antibiotics in activated sludge

Four sequencing batch reactors (SBR) are operated with sludge residence time （SRT）of 2, 8, 14, and 20 days to analyze the impact of SRT on removal of sulfanomide (5 μg/L). In batch experiments, three treatments (active biomass, inhibited biomass, and controls of no biomass) are performed in 100 mL batch reactors in triplicate that simulated one SBR cycle, and are investigated to distinguish biodegradation, biosorption, and volatilization losses, respectively. The results show that biomass removed an average 2.14±0.60 μg/g SS of sulfamethoxazole, 1.14±0.63 μg/g SS of sulfadiazine, 2.33±0.67 μg/g SS of sulfadimethoxine, 2.45±0.85 μg/gSS of sulfamerazine, with 63%, 83%, 35%, 55% of the removal respectively due to sorption. When SBRs (3 L total volume) are spiked continuously with 5 μg/L sulfamethoxazole for 60 days, 10%, 41%, 51%, 58% is removed with SRTs of 2d, 8d, 14d, 20d, respectively. Removal increased significantly with SRT, but the normalized mass removed per gram of biomass decreases. Growth of filamentous organisms with a 2-d SRT increases the sorption capacity of this sludge, although biodegradation is the dominant mechanism for removal. Higher biomass concentrations established by longer SRTs are more significant for biodegradation than species diversity, which do not vary with SRT. As wastewater treatment plants implement longer SRTs for nutrient removal, they will also achieve improved removal of some pharmaceuticals.