The genetic basis of anoxygenic photosynthetic arsenite oxidation

‘Photoarsenotrophy’, the use of arsenite as an electron donor for anoxygenic photosynthesis, is thought to be an ancient form of phototrophy along with the photosynthetic oxidation of Fe(II), H₂S, H₂ and . Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic‐rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster, arxB2AB1CD, where arxA is predicted to encode for the sole arsenite oxidase. The role of arxA in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light‐dependent arsenite oxidation. In situ evidence of active photoarsenotrophic microbes was supported by arxA mRNA detection for the first time, in red‐pigmented microbial mats within the hot springs of Paoha Island. This work expands on the genetics for photosynthesis coupled to new electron donors and elaborates on known mechanisms for arsenic metabolism, thereby highlighting the complexities of arsenic biogeochemical cycling.     

Behavioral effects of phencyclidine (PCP) in the dog: A possible animal model of PCP toxicity in humans

The acute behavioral effects of PCP, given intravenously in doses of .25, .50, 1.00, 2.50 and 5.00 mg/kg, were examined in 8 male mongrel dogs tested in an open field arena. All doses produced an initial “eyes open” coma accompanied by tremors, rigidity, jerky limb movements, nystagmus, excessive salivation, head weaving, stiff tail, and stereotyped sniffing. In addition, doses of 1.0 mg/kg and above produced jaw snapping, opisthothonus and clonic/tonic seizures. Following recovery from coma, animals evinced pronounced hyperactivity and stereotyped circling. In contrast to other laboratory animal species, the behavioral effects produced by PCP in the dog are strikingly similar to those reported to occur in humans after PCP administration, suggesting that this species may provide an excellent laboratory animal model for studying PCP toxicity.     

Amplitude of peroneal compound motor action potential increases in type 2 diabetes with thyroid autoimmunity

正Dear Editor,Diabetic peripheral neuropathy(DPN)is a frequently occurring complication of diabetes.DPN is diagnosed on the basis of findings of neural electrophysiological study,such as the nerve conduction study(NCS).The most common NCS manifestations of DPN include slow velocity,prolonged latency,and decreased amplitude.Risk factors for DPN include age,hyperglycemia,dyslipidemia,smoking,atherosclerotic cardiovascular disease,peripheral arterial disease,diabetic nephropathy,and diabetic retinopathy.     

Stock differences in the susceptibility of rats to learned helplessness training

Learned helplessness (LH) consists of shock escape deficits evidenced by animals previously exposed to inescapable shock. This phenomenon has shown promise as a behavioral screen for new antidepressant drugs. Unfortunately, some stocks of rats evidence low susceptibility to LH training. Accordingly, male rats from 8 different stocks were tested for susceptibility to LH training. The outbred stocks consisted of Harlan SD, Sasco Holtzman, and Charles River Holtzman. The inbred stocks (i.e. strains) tested were Lewis, Wistar Kyoto, Brown Norway, Fischer F-344, and Buffalo. The Lewis, Brown Norway, Fischer and Sasco Holtzman rats were found to be virtually non-susceptible to LH training. Harlan SD and Buffalo rats evidenced intermediate susceptibilities of 28% and 33%, respectively. Kyoto and Charles River Holtzman rats were the most susceptible at 53% and 55%, respectively. No stock differences between control animals were observed. These results indicate that wide differences in susceptibility to LH training exist in rats from different stocks or suppliers and researchers should be careful to choose subjects from a susceptible stock. Charles River Holtzman and Wistar Kyoto rats appear to be very susceptible to LH training.