Pest management in Otago

Abstract

The Otago Regional Council could perhaps be renamed the Otago Rabbit Council. Some 35% of our budget—$8 million—goes annually towards dealing with rabbits, which certainly meet the definition of a pest (an animal which “disrupts management objectives” and lives at a population density exceeding “what society considers to be an acceptable level”). We can only hope that the day will come when we can, with confidence, say that the problem is being solved and when public and private financial inputs into rabbit control can be set at a far more reasonable level.     

Biofouling communities on test panels coated with TBT and TBT-free copper based antifouling paints

Abstract

Formation of biofouling communities on the surfaces of steel panels coated with two different TBT-free copper-based and one TBT-based antifouling paint was examined following submersion for periods of 3, 6, 9 and 12 months in Kastela Bay, Croatia. Test panels coated with Shopprimer and anticorrosive paint were used as control panels. Thirty five taxa of benthic algae and 32 taxa of benthic animals were found. Diatomeae dominated by frequency and abundance on test panels coated with antifouling paints, while the animal species Serpula vermicularis, Mytilus galloprovincialis and Balanus amphitrite amphitrite dominated the fouling communities on control panels. On panels protected by antifouling paints, low values of biomass were found compared to the very high values associated with control panels.     

A methodology for evaluating biocide release rate,surface roughness and leach layer formation in a TBT-free,self-polishing antifouling coating

Abstract

Due to the forthcoming IMO ban on the use of tributyltin (TBT) antifouling paints, a new generation of TBT-free coatings has been developed that typically contain cuprous oxide and an organic co-biocide. Accurate and reproducible test methods are needed to evaluate the performance and environmental impact of these new coatings. This study investigated a methodology for evaluating TBT-free, AF coatings containing cuprous oxide. A commercially available AF coating underwent rotary immersion testing at 0, 0.51 and 2.05 m s^?1. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis were used to assess leach layer formation, percentage cuprous oxide by weight and particle size distribution (PSD). Biocide release rates and surface roughness were also measured. An increase in rotary speed caused a spike in Cu²⁺ release rate after which the release rate stabilised to previous levels. An increase in leach layer thickness was also observed after the rotary speed increase. A model is suggested to account for the observations.     

The influence of antifouling practices on marine invasions

Vessel hull-fouling is increasingly recognised as one of the major vectors for the transfer of marine non-indigenous species. For hundreds of years, copper (Cu) has been used as a primary biocide to prevent the establishment of fouling assemblages on ships' hulls. Some non-indigenous fouling taxa continue to be transferred via hull-fouling despite the presence of Cu antifouling biocides. In addition, several of these species appear to enjoy a competitive advantage over similar native taxa within metal-polluted environments. This metal tolerance may further assist their establishment and spread in new habitats. This review synthesises existing research on the links between Cu and the invasion of fouling species, and shows that, with respect to the vector of hull-fouling, tolerance to Cu has the potential to play a role in the transfer of non-indigenous fouling organisms. Also highlighted are the future directions for research into this important nexus between industry, ecology and environmental management.     

In silico and in vitro studies to elucidate the role of Cu2+ and galanthamine as the limiting step in the amyloid beta (1–42) fibrillation process

The formation of fibrils and oligomers of amyloid beta (Aβ) with 42 amino acid residues (Aβ_1–42) is the most important pathophysiological event associated with Alzheimer''s disease (AD). The formation of Aβ fibrils and oligomers requires a conformational change from an α-helix to a β-sheet conformation, which is encouraged by the formation of a salt bridge between Asp 23 or Glu 22 and Lys 28. Recently, Cu²⁺ and various drugs used for AD treatment, such as galanthamine (Reminyl®), have been reported to inhibit the formation of Aβ fibrils. However, the mechanism of this inhibition remains unclear. Therefore, the aim of this work was to explore how Cu²⁺ and galanthamine prevent the formation of Aβ_1–42 fibrils using molecular dynamics (MD) simulations (20 ns) and in vitro studies using fluorescence and circular dichroism (CD) spectroscopies. The MD simulations revealed that Aβ_1–42 acquires a characteristic U-shape before the α-helix to β-sheet conformational change. The formation of a salt bridge between Asp 23 and Lys 28 was also observed beginning at 5 ns. However, the MD simulations of Aβ₁₋₄₂ in the presence of Cu²⁺ or galanthamine demonstrated that both ligands prevent the formation of the salt bridge by either binding to Glu 22 and Asp 23 (Cu²⁺) or to Lys 28 (galanthamine), which prevents Aβ₁₋₄₂ from adopting the U-characteristic conformation that allows the amino acids to transition to a β-sheet conformation. The docking results revealed that the conformation obtained by the MD simulation of a monomer from the 1Z0Q structure can form similar interactions to those obtained from the 2BGE structure in the oligomers. The in vitro studies demonstrated that Aβ remains in an unfolded conformation when Cu²⁺ and galanthamine are used. Then, ligands that bind Asp 23 or Glu 22 and Lys 28 could therefore be used to prevent β turn formation and, consequently, the formation of Aβ fibrils.     

铜尾矿废弃地土壤动物多样性特征

土壤动物的恢复、群落演替及其多样性对于铜尾矿废弃地的生态重建具有重要意义.为了解铜尾矿废弃地土壤动物群落多样性特征,在铜陵市铜尾矿区设置4个样地23采样点,共捕获土壤动物4622只个体,隶属5门10纲18目29类.结果表明,铜尾矿自然废弃地与其对照组土壤动物多样性差异明显,自然废弃地土壤动物丰富度指数d、大型土壤动物密度、中小型土壤动物密度、多样性指数H'和D·G指数均小于其对照组且存在显著差异.而复垦废弃地中小型土壤动物密度和D·G指数小于其对照组且存在显著差异,多样性指数H'大于其对照组且差异极显著,其他土壤动物群落指标与其对照组均无显著差异.相似系数q表明,外围林地间土壤动物群落相似性最大,其次是复垦废弃地与外围林地间,自然废弃地与其它3个样地间相似性最小.从垂直分层来看,复垦废弃地土壤动物表聚性强于自然废弃地,尾矿废弃地表聚性强于外围林地.灰色关联分析表明,铜尾矿区土壤理化性质与土壤动物群落结构指标关系密切,其中最重要的因素是土壤含水量和总钾含量,重金属全镉含量也不容忽视,植被因素和土壤全铜含量对土壤动物的影响相对较小.由此可见,土壤含水量、土壤基质的优劣、土壤有机质与营养元素的含量等因素限制了铜尾矿废弃地土壤动物的恢复与重建,而这些因素的改善主要归功于尾矿废弃地的土地复垦和作物种植.所以,尾矿废弃地的复垦与利用有利于土壤动物的恢复与重建.     

外源NO对2+胁迫下小桐子幼苗抗氧化能力的影响

为探讨外源一氧化氮(NO)供体硝普钠(SNP)对铜(Cu2+)胁迫的缓解效应,该试验以小桐子幼苗为材料,先通过小桐子幼苗根茎生长指标的变化筛选出后续实验适宜的SNP(0.2mmol/L)和Cu2+浓度(90mmol/L),再进一步考察SNP预处理对Cu2+胁迫下幼苗脯氨酸(Pro)和丙二醛(MDA)的含量及抗氧化酶活性的影响。结果显示:(1)Cu2+处理能诱导小桐子幼苗叶片中Pro和MDA含量显著升高,且过氧化氢酶(CAT)、超氧物歧化酶(SOD)、愈创木酚过氧化物酶(POD)及抗坏血酸专一性过氧化物酶(APX)的活性增强。(2)用SNP预处理能显著提高Cu2+胁迫下幼苗叶片Pro的含量,进一步增强叶片中CAT、SOD、POD和APX活性,降低MDA的含量。研究表明,0.2mmol/L的SNP能够通过提高小桐子幼苗的抗氧化酶活性和游离脯氨酸含量来增强其抗氧化胁迫能力,从而显著缓解Cu2+胁迫对幼苗造成的氧化伤害,维持其正常生长发育。     

Switching from blue to yellow: altering the spectral properties of a high redox potential laccase by directed evolution

Abstract

During directed evolution to functionally express the high redox potential laccase from the PM1 basidiomycete in Saccharomyces cerevisiae, the characteristic maximum absorption at the T1 copper site (Abs₆₁₀T1Cu) was quenched, switching the typical blue colour of the enzyme to yellow. To determine the molecular basis of this colour change, we characterized the original wild-type laccase and its evolved mutant. Peptide printing and MALDI-TOF analysis confirmed the absence of contaminating protein traces that could mask the Abs₆₁₀T1Cu, while conservation of the redox potential at the T1 site was demonstrated by spectroelectrochemical redox titrations. Both wild-type and evolved laccases were capable of oxidizing a broad range of substrates (ABTS, guaiacol, DMP, synapic acid) and they displayed similar catalytic efficiencies. The laccase mutant could only oxidize high redox potential dyes (Poly R-478, Reactive Black 5, Azure B) in the presence of exogenous mediators, indicating that the yellow enzyme behaves like a blue laccase. The main consequence of over-expressing the mutant laccase was the generation of a six-residue N-terminal acidic extension, which was associated with the failure of the STE13 protease in the Golgi compartment giving rise to alternative processing. Removal of the N-terminal tail had a negative effect on laccase stability, secretion and its kinetics, although the truncated mutant remained yellow. The results of CD spectra analysis suggested that polyproline helixes were formed during the directed evolution altering spectral properties. Moreover, introducing the A461T and S426N mutations in the T1 environment during the first cycles of laboratory evolution appeared to mediate the alterations to Abs₆₁₀T1Cu by affecting its coordinating sphere. This laccase mutant is a valuable departure point for further protein engineering towards different fates.     

Copper exposure and the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss)

Abstract

Sublethal concentrations of copper in water cause the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss). Receptor cell loss has been correlated to the loss of olfaction in fish and may cause difficulties in olfactory mediated behaviors such as migration. This study investigated the effects of three levels of copper (100, 75 and 50 mg L^?1) on the olfactory epithelium of rainbow trout. Twenty fish randomly allocated between three exposure groups and one control were exposed for 24 hours under static renewal conditions. Light and scanning electron microscopic observations of olfactory tissue were taken to determine the extent of degeneration of receptors. In addition, levels of copper and zinc in the brain tissues were analyzed to determine if the olfactory route was a significant route of copper exposure and transfer to fish brain tissue. Results indicate that degeneration of receptors is related to the concentration of copper. Levels of copper in brain were found to be below detection of the instrument. Levels of zinc were extremely variable ranging from 52 to 132 ng zinc g^?1 brain tissue.