Effects of metals on enzyme activity in plants

Abstract. Uptake of phytotoxic amounts of metal by higher plants or algae can result in inhibition of several enzymes, and in increase in activity (= induction) of others. Two mechanisms of enzyme inhibition predominate: (1) binding of the metal to sulphydryl groups, involved in the catalytic actionor structural integrity of enzymes, and (2) deficiency of an essential metal in metalloproteins or metal-protein complexes, eventually combined with substitution of the toxic metal for the deficient element. Metal accumulation in the cellular compartment of the enzyme is a prerequisite for enzyme inhibition in vivo. The induction of some enzymes is considered to play a significant role in the stress metabolism, induced by metal phytotoxicity. Peroxidase induction is likely to be related to oxidative reactions at the biomembrane; several enzymes of the intermediary metabolism might be stimulated to compensate for metal-sensitive photosynthetic reactions. The induction of enzymes and metal-specific changes in isoperoxidase pattern can be used as diagnostic criteria to evaluate the phytotoxicity of soils, contaminated by several metals. Lines for future research on metal phytotoxicity are proposed, involving the study of inhibition and induction of enzymes at the different cell membranes (especially the plasmamembrane) in vivo.     

Factors affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): I. THE EFFECT OF DIFFERENT PATTERNS OF FLOWER REMOVAL

1. The effect of various patterns of flower removal on pod settingwas investigated in Lupinus luteus L. Four-fifths, three-fifths,or two-fifths of the flowers of the main inflorescence wereremoved according to ten different patterns. 2. All flowers could produce pods but later ones were less efficientin doing so. Developing pods had an abscission-inducing effecton later flowers, which became increasingly effective towardsthe apical part of the inflorescence. More pods were retained when flowers on each consecutive whorlwere arranged in a spiral than when the same number was arrangedvertically. Pod setting was incomplete when the number of flowers per inflorescencewas reduced well below the total number of pods normally present. 3. The number of ovules in consecutive flowers gradually decreasedfrom an average of 5.7 at the base to 4.3 at the top of theinflorescence. The ratio of seeds to ovules fluctuated irregularlybetween 65 and 94 per cent, and did not indicate a general trendin embryo abortion. 4. The growth-rate of pods at the top of the inflorescence wasmuch slower than at the bottom. Vascular differentiation wasalmost absent at the top of the inflorescence when the flowerswere fertilized, and further vascular tissue was produced onlywhen flowers produced pods.     

Possible aversion learning in the Pacific Coast wireworm

The effects of carbon dioxide and the induction of morbidity on aversion learning in larvae of the Pacific Coast wireworm Limonius canus LeConte (Coleoptera: Elateridae) are discussed. Wireworms preconditioned by exposing them one or four times to odour of Tefluthrin 20SC and Dividend XLRTA [Syngenta Crop Protection (Canada), Inc., Canada] during the induction of temporary morbidity subsequently contact tefluthrin‐treated wheat seeds in soil bioassays for as long as naïve (i.e. not preconditioned) larvae but are repelled four to five‐fold more frequently by Dividend‐treated seeds in soil bioassays than naïve wireworms, suggesting that wireworms are capable of associating a novel odour (i.e. Dividend) with morbidity but require a minimum of 10–15 min subsequent contact time with treated seeds before being repelled. Wireworms preconditioned by exposure to peppermint odour during the induction of morbidity are not subsequently repelled by peppermint odour in soil bioassays, suggesting that wireworms are either not capable of aversion learning or that the presence of a CO₂ source and/or a suitable host plant may override a negative cue (i.e. peppermint odour). In studies conducted in the absence of soil, a host plant and CO₂ production, wireworms are repelled slightly by droplets of 1.0% but not 0.1% peppermint oil. Previous exposure to peppermint odour or contact with peppermint oil‐treated filter paper during one induction of morbidity does not increase the repellency of wireworms to 1.0% peppermint oil significantly. Repellency to 1.0% peppermint oil is almost eliminated when morbidity is induced five times in the absence of peppermint odour but is restored when peppermint odour is present during preconditioning. These findings suggest that wireworm sensitivity to repellent compounds decreases when repeatedly made moribund, although the results are not sufficient to conclude that wireworms are capable of associative learning.     

Isolation and characterization of microsatellite markers for paternity assessment in the golden whistler (Pachycephala pectoralis: Aves)

We isolated and characterized six novel microsatellite markers for paternity analysis in the golden whistler Pachycephala pectoralis, by screening an enriched genomic library using nonradioactive PCR techniques. The six loci exhibited little or no evidence of null alleles and showed high levels of polymorphism (mean H_E = 0.85, mean number of alleles = 15.2), making them suitable for paternity assessment in this species (exclusion probability of six unlinked loci = 0.9997).     

Testing Reliability of Body Size Measurements Using Hind Foot Length in Roe Deer

Abstract: We quantified the repeatability of >900 individual measures of hind foot length from 2 French populations of roe deer (Capreolus capreolus) monitored by capture-recapture. We found a high repeatability (i.e., high intra-class correlation, 0.76, 95% CI = 0.72–0.83 and 0.92, 95% CI = 0.91–0.95) in both populations. We also found that inexperienced observers reached a high level of intra- (1.00, 95% CI = 0.96–1.00) and inter-observer repeatability (0.99, 95% CI = 0.98–1.00) when measuring hind foot length of harvested animals with a tool specifically designed for this task. Managers should pay particular attention to limit measurement errors because unreliable measurements require an increased sample size to assess individual variation and can mask biological patterns.     

Effects of Na2SO4, K2SO4 and KCl on Growth and Ion Uptake of Callus Cultures of Vaccinium corymbosum L. cv. Blue Crop

Non-selected and Na₂SO-, K₂SO₄- or KCl-selected callus culturesof Vaccinium corymbosum L. cv. Blue Crop were grown on mediasupplemented with 0, 25 and 50 mM Na₂SO₄ (non-selected and Na₂SO(-selectedonly), 0, 25 and 50mMK₂SO₄ (non-selected and K₂SO₄-selectedonly) or 0, 50 and 100 mM KCl (non-selected and KCl-selectedonly). On all media, growth of selected callus (on a fresh-weightor dry-weight basis) was greater than that of non-selected callus,and selected callus grew optimally on the level and type ofsalt on which it was selected. Selected callus was friable andmaintained a higher f. wt:d. wt ratio. Tissue water potentialin selected callus was more negative than in non-selected callus. Flame photometry and chloridometry showed Na⁺, K⁺ and Cl^–accumulated in callus to concentrations equal to or greaterthan the initial concentration in the medium. Turbidometry showedthat tissue SO₄^2- concentration was lower than the concentrationin the medium. In most cases selected callus accumulated moreNa⁺, K^sup, SO₄^2– or Cl^– than non-selected callus.Vacuolar ion concentration was measured by electronprobe X-raymicroanalysis, and on most media selected callus had highervacuolar ion concentrations than non-selected callus. SO₄^2–and Cl^– were accumulated in the vacuoles at concentrationshigher than the external medium, but vacuolar Na⁺ concentrationdid not reach external concentration on Na₂SO₄ and on potassiumsalts was maintained between 12 and 17 mM. Vacuolar K⁺ concentration(approx. 142–191 mM on no salt) decreased on Na₂SO₄ andincreased on K₂SO₄ and KCl. There was no precise correlation between total or specific ionaccumulation (Na⁺, K⁺, SO₄^2– and Cl^– and fresh-weightyield. Results suggest that selection results in adaptationin response to decreased water potential of the medium. Vaccinium corymbosum, blueberry, electronprobe X-ray microanalysis, callus, in vitro selection, salt tolerance, KCl, K₂SO₄, Na₂SO₄     

抗欧亚活血丹凝集素特异性多克隆抗体的制备

欧亚活血丹外源凝集素(Gleheda)是分离自欧亚活血丹 (Glechoma hederacea) 叶片中的一种糖基化植物新蛋白. 如同其他糖基化蛋白,通过免疫学方法探测 Gleheda 的过程中通常受到一些不相干糖蛋白的妨碍,为此制定了抗 Gleheda 特异性多克隆抗体的纯化方案. 免疫血清蛋白经硫酸铵选择性沉淀后,分别以 Gleheda 和刺槐外源凝集蛋白 (RPA) 结合在 Sepharose 4B作为亲和配体,采用亲和层析法连续纯化 2 次,然后进一步采用离子交换层析 Q Fast Flow 提纯. 经每一步骤提纯得到的抗体组分对 Gleheda 的特异性,均同时采用双向免疫扩散检验和 Western blot 分析. 结果表明,以 Gleheda 为配体,亲和纯化制备得到的抗体组分对叶片粗提物中的许多植物 (糖) 蛋白仍然表现交叉反应. 为除去由植物糖蛋白中的聚糖所引起这些非特异性交叉反应抗体,接着以 RPA 为配体再次进行亲和纯化,Western blot 分析显示,抗体的特异性得到提高但并非除去了所有非特异性交叉反应的抗体. 最后进一步采用离子交换层析制备得到仅抗 Gleheda 蛋白的特异性抗体组分,此抗体组分适用于免疫探测研究. 该抗体纯化制备程序简易而高效,而且不需要昂贵的设备.     

Natal Dispersal and Philopatry of Red Foxes in Urban and Agricultural Areas of Illinois

Abstract: Dispersal and philopatry may be influenced by habitat, intraspecific and interspecific interactions, and resource quality. Dispersal may vary substantially between urban and rural wildlife populations due to differences in urban-rural habitat and trophic relationships. We examined effects of environmental, body condition, and social influences on dispersal and philopatry of urban and rural red foxes (Vulpes vulpes) in east-central Illinois and western Indiana, USA. We recorded 96 dispersal events and 66 cases of philopatry in juvenile foxes. We used Akaike's Information Criterion to evaluate regression models of dispersal probability, initiation date, distance, and days spent dispersing. Habitat (i.e., urban-rural), sex, row-crop percentage in natal home ranges, family home-range overlap, and social interactions with family members all influenced dispersal probability. Juvenile foxes with fewer row crops in their home ranges, individuals with high intra-familial overlap of summer range, females, and urban foxes were associated with philopatry. Dispersals began mid-September and ended in March. Rural juveniles dispersed 23 days earlier than did urban conspecifics. Heavier foxes (capture wt) and those with heavily row-cropped home ranges dispersed earlier. Littermates dispersed at similar times, although in different directions. Dispersal distances averaged 44.8 km for all foxes (range = 1–478 km). Male and urban foxes dispersed farther than female and rural foxes, respectively. Time between dispersal and settlement averaged 41.2 days (range = 2–114 days), with urban foxes dispersing over longer time periods. Dispersal direction between the sexes had different directional distributions, though mean vectors for both were oriented north. Dispersing foxes selected cropland in proportion to availability, whereas grassland was selected preferentially. We demonstrate influences of habitat, resource availability, familial social interactions, and interspecific interactions on dispersal and philopatry of juvenile red foxes in an intensively row-cropped region of the Midwest. Our findings demonstrate red fox dispersal ecology differences in urban and rural environments. In intensively row-cropped regions of the Midwest where landscape crop harvest alters dispersal timing, minimizing seasonal habitat changes with permanent vegetative structure (e.g., crop food plots, native grass fields) would likely delay dispersal activity, and increase survival.