Immunoaffinity columns for isolation of abscisic acid in conifer seedlings

Spleen cells of mice immunized with cis, trans (±) abscisic acid (ABA) conjugated to bovine serum albumin (BSA) were fused with myeloma cells to produce hybridomas. Hybridomas secreting antibodies to cis, trans (+) ABA were detected by enzyme-linked immunoassay and injected into the peritoneal cavity of mice to produce ascites fluid. Antibodies purified by size-exclusion chromatography were linked to cyanogen bromide-activated Sepharose beads and used to prepare immunoaffinity columns (IAC). Semi-purified conifer seedling (Douglas-fir [ Pseudotsuga menziesii (Mirb) Franco] lodgepole pine ( Pinus contorta Dougl), cedar ( Thuja plicata D. Don), and spruce [ Picea glauca (Moench) Voss)]) extracts were passed through IAC, washed thoroughly with water and then eluted with methanol. ABA in the methanol eluate was analysed by high performance liquid chromatography with UV detection. UV absorption of extracts before and after purification through IAC indicated an excellent purification of extract by IAC. The identity of the ABA peak was confirmed by gas chromatography-mass spectrometry.     

Avian top predator and the landscape of fear: responses of mammalian mesopredators to risk imposed by the golden eagle

Top predators may induce extensive cascading effects on lower trophic levels, for example, through intraguild predation (IGP). The impacts of both mammalian and avian top predators on species of the same class have been extensively studied, but the effects of the latter upon mammalian mesopredators are not yet as well known. We examined the impact of the predation risk imposed by a large avian predator, the golden eagle (Aquila chrysaetos, L.), on its potential mammalian mesopredator prey, the red fox (Vulpes vulpes, L.), and the pine marten (Martes martes, L.). The study combined 23 years of countrywide data from nesting records of eagles and wildlife track counts of mesopredators in Finland, northern Europe. The predation risk of the golden eagle was modeled as a function of territory density, density of fledglings produced, and distance to nearest active eagle territory, with the expectation that a high predation risk would reduce the abundances of smaller sized pine martens in particular. Red foxes appeared not to suffer from eagle predation, being in fact most numerous close to eagle nests and in areas with more eagle territories. This is likely due to similar prey preferences of the two predators and the larger size of foxes enabling them to escape eagle predation risk. Somewhat contrary to our prediction, the abundance of pine martens increased from low to intermediate territory density and at close proximity to eagle nests, possibly because of similar habitat preferences of martens and eagles. We found a slightly decreasing trend of marten abundance at high territory density, which could indicate that the response in marten populations is dependent on eagle density. However, more research is needed to better establish whether mesopredators are intimidated or predated by golden eagles, and whether such effects could in turn cascade to lower trophic levels, benefitting herbivorous species.     

Effects of pine wilt disease invasion on soil properties and Masson pine forest communities in the Three Gorges reservoir region,China

Pine wilt disease (PWD) has caused significant Masson pine mortality in the Three Gorges reservoir region in central China. In this study, five uniform Masson pine stand types infected by PWD were selected and surveyed on slopes and aspects with similar environmental conditions. In sites that had been infected, soil bulk density was reduced, and the difference among the groups was statistically significant (P < 0.05) at the 0–10 cm and 10–20 cm soil layers, but not at 20–40 cm. Other soil water‐related physical properties, excluding noncapillary porosity, significantly differed among the groups in all soil layers. Additionally, the values of available phosphorus, sodium, potassium, calcium, and magnesium were higher in the invaded stands, but the total nitrogen and organic matter contents were lower. Masson pine does not become reestablished following PWD‐induced mortality but is instead replaced by broad‐leaved tree species. Among the 19 examined environmental variables, five were found to be significantly related with the ordination of plant community structure: Masson pine stumps (MPS), K⁺, capillary water holding capacity (CWHC), capillary porosity (CP), and soil water content (SWC). Among these factors, the plant community structure was principally related to MPS and K⁺. The findings of this study show that the outbreak of PWD has impacted Masson pine forest soil properties and altered forest community composition. The disease is negatively related with the presence of Masson pine and positively associated with that of broad‐leaved tree species.     

Monitoring Landscape‐Scale Ponderosa Pine Restoration Treatment Implementation and Effectiveness

We evaluated landscape‐scale forest restoration treatment implementation and effectiveness in meeting objectives in a ponderosa pine forest at Mt. Trumbull, Arizona, U.S.A. The goal of the project was to alter forest structure by thinning and burning to more closely resemble forest conditions prior to Euro‐American settlement in 1870. We measured 117 permanent plots before (1996/1997) and after (2003) treatments. The plots were evenly distributed across the landscape (approximately 1,200 ha), about half of which was an untreated control. We evaluated treatment implementation and effectiveness based on 1870 structure and/or goals outlined by managers. The success of treatment implementation varied: about 94% of the area originally planned for restoration was treated in some manner by 2003, but only 70% received the full planned treatment (thin and burn). Although density of ponderosa pines >2.5 cm was reduced significantly by 66% from approximately 429 pines/ha to approximately 146 pines/ha in the treated area, the targeted residual density was exceeded by 111–256% (all plots) or 10–85% (thinned and burned plots). Thirteen percent of the pre‐settlement pines died in the treated area by 2003, but 9% percent also died in the control, indicating that pre‐settlement pines in untreated areas were nearly as vulnerable as those exposed to restoration treatments. Large snags increased 45%, and 65% of logs >50 cm were retained, achieving implementation goals. Although restoration treatments were not implemented totally to specifications, they were effective in attaining the overall project goal of restoring more open forest structure while preserving more than 75% of the pre‐settlement pines. Canopy fuel loads were substantially reduced, allowing for the reintroduction of surface fires.     

微红梢斑螟蛀道节肢动物种群结构及生态位

选择我国江苏、安徽和广东7个不同林型的松树林地,对微红梢斑螟(Dioryctria rubella)蛀道节肢动物种群结构及生态位进行调查研究。结果表明:微红梢斑螟蛀道节肢动物种群隶属2纲9目13科,分别为蛛形纲蜘蛛目、蜱螨目,昆虫纲弹尾目、革翅目、啮虫目、半翅目、缨翅目、鞘翅目、膜翅目;利用相对优势指标判别微红梢斑螟蛀道节肢动物优势种有螨科和隐翅虫科,丰盛种有跳虫科,常见种有啮虫科、蠼螋科、蚁科、锯谷盗科、象甲科、蓟马科和茧蜂科,偶见种有小蠹科、蝽科和微蛛科;利用Levins生态位宽度和Pianka生态位重叠对各种群生态位计算表明,隐翅虫科与微红梢斑螟的时间和空间生态位重叠值最大,说明在各种群中隐翅虫科与微红梢斑螟的跟随关系最为紧密;利用聚集度指标法判别优势种群隐翅虫的空间分布属于聚集型分布,用零频率方法计算隐翅虫种群的空间格局为聚集型,种群类型为聚集度逆零频率制约型。     

Influence of extraction solvent (buffer, methanol, acetone) and time on the quantification of indoIe-3-acetic acid in plants

The effect of extraction solvent and time on the measured indole-3-acetic acid (IAA) level was investigated in plant materials having different contents of lAA-conjugates, Tissues from pine ( Pinus sylvestris L.). tobacco ( Nicotiana tabacum L.), and maize ( Zea mays L.) were extracted for 1–9 h with Na-phosphate buffer (pH 7.5). 80% methanol and 70% acetone. IAA was measured by combined gas chromatography-selected ion minitoring-mass spectromctry (GC-SIM-MS) with [¹³C₆]-IAA as an internal standard.
Extraction of maize seedlings with buffer gave a higher estimate of free IAA than did extraction with methanol or acetone, which produced similar values. The increase in free IAA after buffer extraction was paralleled by a stoichiometric decrease in lAA-ester conjugates, indicating that free IAA was formed during buffer extraction by hydrolysis of these conjugates, which are abundant in maize seedlings. The amount of hydrolysis during a 1-h extraction period was estimated to be ca 3% of the total lAA-ester pool. However, in the pine extraxylary tissues and tobacco in-ternodes which lack a significant lAA-ester pool, buffer extraction resulted in the same IAA estimate as extraction with the organic solvents, but produced a cleaner extract. For all the plant materials investigated, a 1-h extraction period was sufficient for equilibrating the internal standard with the endogenous IAA pool.     

Purification and properties of glutamate dehydrogenase in Scots pine (Pinus sylvestris) needles

NADH-dependent glutamate dehydrogenase (GDH. EC 1. 4. 1.2) was isolated from the needles of Scots pine (Pinus sylverstris L.) grown on a rural and on a heavily polluted industrial area, and it was purified about 500 fold. The purification procedure included salt I'ractionation, ion exchange and affinity chromatography. Miehaelis constants for 2-oxoglularale (1.7 mM). for ammonium sultate (19 mM ) and for NADH (42.5 resp. 53 μM) the pH optimum (8.5) the requirements for Ca²⁺ ions, the temperature dependence ofl the enzyme activity (incubation from 0 to 82°C). and the relation between forest region and electrophoretie isoenzyme pattern were determined. The possible role of GDH in the adaptation of plants to ammonia assimilation (detoxification) under stress conditions, particularly with respect to air pollution, is discussed.