Light-Induced Hg Volatilization and O2 Evolution in Chlorella and the Effect of DCMU and Methylamine

The rate of volatilization of Hg²⁺ as metallic Hg is accelerated by illumination of Chlorella cells. In the presence of the uncoupler methylamine the rate of volatilization in the light is greatly but transiently increased. DCMU (3-(3,4-dichlorophenyl)-1,1-dimethyl urea) prevented the light response. In the presence of Hg²⁺, O₂ evolution by the cells was not completely inhibited by DCMU. Hg²⁺ appears to prevent DCMU reaching its binding site. Light seems to increase the amount of or leakage from the cells of a metabolite capable of reducing Hg²⁺ to Hg°.     

Electrophysiological and biochemical responses of mouse vomeronasal receptor cells to urine-derived compounds: possible mechanism of action

Receptor cells of the vomeronasal organ (VNO) are thought to detect pheromone-like molecules important for reproductive physiology. Several compounds derived from male mouse urine have been demonstrated to affect endocrine events in female mice. In the present study, the ability of these compounds to affect VNO activity was tested. In dissociated VNO cells held under voltage clamp conditions, application of dehydro-exo-brevicomin (DHB) evoked an outward current at negative holding potentials and an inward current at positive holding potentials. Under current clamp, DHB reduced action potential firing. Since DHB application caused a decrease in membrane conductance, this compound appeared to act by reducing inward current through closing an ion channel. Biochemical experiments tested the effects of DHB and 2- (sec-butyl)-4,5-dihydrothiazole (SBT) on cAMP levels in the VNO. A mixture of DHB and SBT decreased cAMP levels in VNO sensory tissue and had no effect on VNO non-sensory tissue. The results suggest that pheromones have an inhibitory influence on action potential generation and on cAMP levels in receptor cells of the VNO.      

Trends in lizard translocations in New Zealand between 1988 and 2013

There is growing concern about mitigation-driven translocations that move animals from anthropogenic threats at donor sites because of their failure rate and lack of application of scientific principles and best practice. We reviewed all known lizard translocations in New Zealand between 1988 and 2013 and identified 85 translocations of 30 lizard taxa to 46 release sites. Most translocations (62%) were motivated by conservation goals for the species or the release site, and one-third were mitigation-driven translocations, typically motivated by habitat loss due to development. Mitigation-driven translocations began in 2003, and since that time have equalled the number of conservation-motivated translocations. Conservation-motivated translocations usually released lizards on islands without mammalian predators, whereas mitigation-driven translocations usually relocated lizards to mainland sites with introduced predators. Long-term monitoring has been sparse and often rudimentary. Eight lizard translocations have recorded population growth, including one mitigation-driven translocation that was into a fenced reserve. Research on commonly used management techniques to mitigate human-related impacts is recommended to establish whether these techniques benefit lizards in the long term.     

The Effect of PCIB on the Germination and Growth of Lettuce in the Presence of Thiourea

The joint action of the anti-auxin parachlorophenoxy isobutyricacid (PCIB) and thiourea on germination and growth of lettuceseed was investigated. PCIB alone did not affect germinationor hypocotyl growth of lettuce. Root growth was stimulated byPCIB. In germination PCIB showed interaction at all the thioureaconcentrations. All thiourea concentrations reversed the stimulationof root growth caused by PCIB, except the lowest thiourea concentrationwith the highest PCIB one. In hypocotyl growth the two substances showed no interaction.These results are discussed in relation to the auxin and anti-auxineffects in germination and growth.     

The Activity of Organic Acids as Germination Inhibitors and its Relation to pH

The germination inhibitory activity of organic acids relatedto coumarin was investigated. The activity was found to be unrelatedto the nature of the side chain carrying the carboxyl group.Little or no relation between structure and activity existed.pH was found to be of secondary importance on the activity ofthe acids. Synergism between buffers and the acids exists insome cases. Moreover, the use of buffers in studying germinationinhibition was found to be unnecessary, due to the powerfulbuffering action of the seeds, and impermissible due to verymarked secondary effects of the buffers themselves and theireffect on germination.