Toxicity and repellency of patchouli oil and patchouli alcohol against Formosan subterranean termites Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae)

Patchouli oil obtained from Pogostemon cablin (Blanco) Benth and its main constituent, patchouli alcohol, were tested for their repellency and toxicity against Formosan subterranean termites (Coptotermes formosanus Shiraki). Both were found to be toxic and repellent. Unusual tissue destruction was noted inside the exoskeleton of the termite after patchouli alcohol was topically applied to the dorsum.     

Metabolism of polycyclic aromatic hydrocarbons by the wood-feeding termite Coptotermes formosanus (Shiraki)

Polycyclic aromatic hydrocarbons (PAHs) are among the most prevalent and persistent pollutants in the environment. In this study, the wood-feeding termite (WFT) Coptotermes formosanus (Shiraki) was studied regarding the potential ability to degrade two selected low-molecular-weight PAHs, phenanthrene and anthracene. Pyrolysis-gas chromatography/mass spectrometry was employed for analysis of in vivo PAH degradation by three gut segments (fore-, mid-, and hindgut) of the WFT. The results revealed the capability of lower termite for PAH metabolism, which started from the foregut and mainly occurred in the midgut region. Remediation of phenanthrene by the termite has been proposed to be initiated via hydroxylation at the C-10 position. Anthracene metabolism first occurred at the C-3, C-5, and C-12 positions with the addition of aldehyde and carbonyl groups. Ring hydroxylation, methoxylation, esterification, carboxylation, and methylation were detected on both the PAHs for ring fission, suggesting the existence of effective PAH modification activity in the alimentary canal of C. formosanus . This new PAH degradation system of the WFT provides new insights for potential technologies for bioremediation of PAH-contaminated soil and sediment based on the related lingolytic enzymes.     

Consistent effects of eastern subterranean termites (Reticulitermes flavipes) on properties of a temperate forest soil

Termites inhabit a large portion of land covered by temperate forests. Climate warming and urbanization will likely extend their range and increase their densities in these ecosystems but, compared to their tropical counterparts, little is known about their effects on soil properties and processes. If temperate termites have the strong ecosystem engineering effects of tropical termites, then knowledge of their ecology and impacts will be vital for predicting how temperate systems respond to environmental change. We investigated how feeding and tunneling by the eastern subterranean termite, Reticulitermes flavipes, affected wood decomposition and soil properties under decaying wood. Twelve laboratory microcosms filled with mineral soil and with wood blocks of four common temperate tree species, received R. flavipes soldiers and workers at field densities, with an additional five termite-free microcosms serving as controls. After 25 weeks, the effects of termites on wood mass loss, and on carbon and nitrogen dynamics, differed across tree species, yet their effects on soil properties were consistent regardless of wood type. Microbially-available carbon in soil was 20% higher with termites and soil moisture content 20% lower. Soil pH was more acid with termites and their effects on soil microbial biomass were positive but non-significant. These soil responses were consistent regardless of the wood species, suggesting that termite effects on soil are dictated largely by their activity within the soil matrix and not by their feeding rate on specific wood substrates. These results are among the first to quantify the effects of temperate forest termite activity on soil properties, demonstrating the potential for these termites to shape biogeochemical cycling and plant communities through their alteration of the soil environment.     

Impact of subterranean fungus-growing termites (Isoptera, Macrotermitiane) on chosen soil properties in a West African savanna

Fungus-growing termites (Isoptera, Macrotermitinae) play an important role in tropical ecosystems in modifying soil physical properties. Most of the literature regarding the impact of termites on soil properties refers to termite epigeous mounds. In spite of their abundance and activity in African savannas, few studies deal with the properties of underground nest structures (fungus-comb chambers) built by subterranean Macrotermitinae termites. We tested whether these termites significantly modify the soil physico-chemical properties within their nests in a humid tropical savanna and whether these effects are different for two termite species with differing building behaviour. Termite-worked soil material was collected from fungus-comb chamber walls of two widespread species: Ancistrotermes cavithorax, which builds diffuse and ephemeral nests and Odontotermes nr pauperans, which most often builds concentrated and permanent nests for a comparatively much longer period of time. Neither species influenced soil pH but both significantly modified soil texture and C-N content in their nest structures. A strong impact on clay-particle size was also detected but no significant differences in clay mineralogy. Thus Odontotermes has a greater effect on soil properties, that could be explained by its building behaviour and the concentration in space of its nest units. Therefore, spatial pattern and life-span of fungus-comb chambers should be an important parameter to be considered in the functional role of subterranean Macrotermitinae termites in the savanna.     

Characterization and Prebiotic Activity of Aqueous Extract and Indigestible Polysaccharide from Anoectochilus formosanus

Anoectochilus formosanus (Orchidaceae) is a folk medicine in Asia. This study investigated the in vivo and in vitro prebiotic effects of an aqueous extract of A. formosanus (SAEAF) and of an indigestible polysaccharide (AFP) isolated from SAEAF. Chemical analyses showed AFP was mainly composed of arabinogalactan type II (AG-II), with an average molecular weight of 29 kDa. Following 4 weeks of oral administration to rats, SAEAF exhibited prebiotic effects including a decrease in cecum pH and increases of calcium absorption and fecal bifidobacteria. Furthermore, through a bioactivity-guided separation strategy, AFP was proven to be a bifidogenic component in vitro fecal strains fermentation and in vivo administration to mice. In RT-PCR analysis of Bifidobacterium , AFP increased the expression of ABC transporter related to nutrient uptake. Thus, AFP, a polysaccharide from A. formosanus, was demonstrated to be a prebiotic that has a positive health effect on gut microbiota.     

Activity of meadowfoam (Limnanthes alba) seed meal glucolimnanthin degradation products against soilborne pathogens

Meadowfoam (Limnanthes alba L.) is a herbaceous winter-spring annual grown as a commercial oilseed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products, and therefore the meal may have potential in the management of soilborne pathogens. To maximize the pest-suppressive potential of meadowfoam seed meal, it would be beneficial to know the toxicity of individual glucolimnanthin degradation products against specific soilborne pathogens. Meloidogyne hapla second-stage juveniles (J2) and Pythium irregulare and Verticillium dahliae mycelial cultures were exposed to glucolimnanthin as well as its degradation products. Glucolimnanthin and its degradation product, 2-(3-methoxyphenyl)acetamide, were not toxic to any of the soilborne pathogens at concentrations up to 1.0 mg/mL. Two other degradation products, 2-(3-methoxymethyl)ethanethioamide and 3-methoxyphenylacetonitrile, were toxic to M. hapla and P. irregulare but not V. dahliae. The predominant enzyme degradation product, 3-methoxybenzyl isothiocyanate, was the most toxic compound against all of the soilborne pathogens, with M. hapla being the most sensitive with EC(50) values (0.0025 ± 0.0001 to 0.0027 ± 0.0001 mg/mL) 20-40 times lower than estimated EC(50) mortality values generated for P. irregulare and V. dahliae (0.05 and 0.1 mg/mL, respectively). The potential exists to manipulate meadowfoam seed meal to promote the production of specific degradation products. The conversion of glucolimnanthin into its corresponding isothiocyanate should optimize the biopesticidal properties of meadowfoam seed meal against M. hapla, P. irregulare, and V. dahliae.     

Selection criteria for grain yield and stability in bambara groundnut (Vigna subterranean (L) Verdc) landraces

The potential of bambara groundnut as a crop-based approach for the sustainable reduction of protein–energy malnutrition prevalent in Nigeria is still being explored. However, one of the limitations to sustainable production of this adapted species is low and unstable yield. Here, we employed multiple statistical analyses to determine traits that could be useful in predicting grain yield. Furthermore, additive main effect and multiplicative interaction and genotype × genotype × environment models were used to identify high yielding and stable landraces. Twenty-four bambara landraces were evaluated in two contrasting dry land growing seasons at four environments. Based on the results of correlation, path coefficient values and stepwise multiple regression analysis, it is reasonable to assume that seed growth rate would be effective as indirect selection criteria for grain yield improvement in this set of breeding materials under early and late planting environment. However, optimizing biomass growth rate, pod fill period, 100-seed weight, number of pods per plant and time to flowering may have important role in the improvement of grain yield in bambara groundnut. Due consideration should be given to 100-seed weight and time to flowering in the early dry and late planting environment. The possibility of successful cultivation of bambara groundnut in forest–savannah transition agricultural zone of Nigeria, particularly when planting is done around early August has been established in this study. However, based on the strong association between seed yield and its related characters in early and late planting environments, selection for higher seed growth rate combined with large number of pods appears to be the best indirect traits when selecting bambara groundnut plants to enhance grain yield under early and late planting environments. While landraces TVSu 1520 and 1578 were considered the best adapted landraces, TVSu 1670 and 1518 are promising landraces that could contribute to increasing grain yield stability.     

Leaf size variation in subterranean clover (Trifolium subterraneum L. sensu lato)

In subterranean clover, leaf size contributes to plant competitivity; besides, this trait is attributed a diagnostic relevance. The study assessed leaf size variation at two growth stages (60 days after sowing and flowering date) on genotypes belonging to the three main subspecies of the complex, viz. subsp. subterraneum, brachycalycinum, and yanninicum. After 60 days, brachycalycinum showed the largest leaflet area while subterraneum and yanninicum did not differ. Leaf size increase between the two measurements, remarkable in all subspecies, was significantly highest in yanninicum, which showed the largest area at flowering date. The leaflet length/breadth ratio was similar in the three subspecies at both stages. In subterraneum and brachycalycinum this ratio decreased significantly from the first to the second measurement; leaflet area increase seemed depending more on breadth than length increase. Yanninicum showed the longest petiole at flowering, and subspecies ranking for this character paralleled that of leaflet area. Particularly in subterraneum, there was a noticeable genotype variation for all characters. Earlier genotypes tended to have larger leaves after 60 days, and shorter petioles and smaller leaves at flowering date. In subterraneum, the genotype leaflet size decreased on increasing altitude and rainfall, and decreasing temperature of the collection sites. The leaf characters examined fairly confirmed to bear a taxonomic basis. Further assessing the physiological behaviour, particularly the response to defoliation and its agronomic implications, of genotypes characterised by different leaf size is envisageable.     

Incidence of fungus-growing termites (Isoptera, Macrotermitinae) on the structure of soil microbial communities

The aim of this study was to investigate the impact of subterranean fungus-growing termites on the structure of soil microorganism communities. We tested whether termites significantly modify the abundance and structure of microbial communities within their below-ground nests (fungus-comb chambers) and whether these effects are species-specific.The investigations were carried out in a humid savanna reserve with material collected from the fungus-comb chamber walls of two widespread species differing in the mode of nest construction. Ancistrotermes builds diffuse and ephemeral nests while chambers of Odontotermes are mostly concentrated and occupy the same area for a comparatively much longer period of time then creating lenticular mounds. The soil properties (pH, texture and C, N content) and the microbial biomass were analysed and automated rRNA intergenic spacer analysis (ARISA) was used to characterise bacterial (B-ARISA) and fungal (F-ARISA) communities. Our results illustrate that the nest structures created by termites offer a diverse range of physical and chemical environments that differ strongly from those present in the general soil mass. Odontotermes had strong effects on microbial properties at the scale of the fungus-comb chamber and at the scale of the lenticular mound. In the fungus-comb chambers, the microbial biomass is not affected by termites but the structure of microbial community is different from that in the control open savanna soil. In the lenticular mound, the microbial biomass is higher and the structure of bacterial community is distinct than that in the fungus-comb chambers. Ancistrotermes also strongly influenced the structure of soil bacterial and fungal communities in the open savanna. However, we did not find any significant modification of bacterial and fungal community structures in the lenticular mound. The impact of fungus-growing termites is, therefore, species-specific and varies depending on the study site (open savanna vs. lenticular mound).     

玉米内生芽胞杆菌的抗菌活性物质及其拮抗玉米大斑病菌机理的初步研究

为了研究生防菌株对玉米大斑病菌的抑菌作用,深化对生防菌抗菌机制的认识,本研究从玉米(Zea mays)植株体内分离拮抗玉米大斑病菌(Setosphaeria turcica)的内生细菌,对其抗菌物质及其抑菌机理进行初步研究。结果表明,所分离的内生菌株YY1经形态学观察、生理生化测定及16SrDNA序列分析,鉴定为枯草芽胞杆菌(Bacillus subtilis)。菌株YY1发酵液的硫酸铵沉淀物具有抑菌活性,且在硫酸铵50%饱和度时抑菌活性最强,说明YY1菌株产生的抗菌活性物质可能是蛋白类物质。该菌株及其蛋白粗提液均对禾谷镰刀菌(Fusarium graminearum)、苹果轮纹病菌(Botryosphaeria dothidea)、灰霉病菌(Botrytis cinerea)、玉米弯孢霉叶斑病菌(Curvularia lunata)等7种植物病原真菌有较强的拮抗作用。用蛋白粗提液处理菌丝、分生孢子、原生质体后经显微观察发现,大斑病菌的基内菌丝由丝状畸变为串珠状,当蛋白粗提液浓度为0.78μg/μL时,可完全抑制分生孢子萌发,并导致原生质体裂解。通过抑制孢子萌发过程中信号途径相关基因的半定量RT-PCR分析和玉米大斑病菌不同信号途径相关基因突变体的抑制率统计,初步判定该抑菌过程主要通过cAMP信号转导途径发挥作用。本研究为寻找玉米大斑病菌新的防治方法和途径提供基础资料。     

Activity of (-)-epigallocatechin 3-O-gallate against oxidative stress in rats with adenine-induced renal failure

Methylguanidine (MG) is widely recognized as a strong uremic toxin. The hydroxyl radical (*OH) specifically plays an important role in the pathway of MG production from creatinine (Cr). In this study, we investigated whether oral administration of (-)-epigallocatechin 3-O-gallate (EGCg) suppresses MG production in rats with chronic renal failure after intraperitoneal Cr injection. MG production from Cr was significantly increased in rats with adenine-induced renal failure, which was more vulnerable to oxidative stress, compared with that in normal rats. However, oral administration of EGCg 30 min before and after Cr injection effectively inhibited MG production. Our findings suggest that EGCg, an excellent antioxidant from green tea, exerts protective activity in rats with chronic renal failure, resulting in suppression of Cr oxidation influenced by *OH.     

Variation of morphological and adaptive traits in subterranean clover populations from Sardinia (Italy)

Variation was studied in subterranean clover for two morphological and four adaptive characters on genetically complex populations from Sardinia. The aim was to assess the population genetic structure in this almost completely inbred species, and to verify whether or not similar levels of diversity occurred at distinct sites of origin. Differences were found among populations for the class frequencies of the two morphological characters and for the subsequent level of intrinsic diversity measured by the Shannon-Weaver index. The variation among and within populations found for the other four characters suggested thatpopulations adjust in the long term their adaptive features to the environmental conditions but maintain contextually high levels of intra-population variation, which, in turn, is a primary factor of adaptation in environments that are seldom uniformspatially and temporally. A principal component analysis executed on the important traits for adaptation showed that these features could be combined, on the average, in different ways in the genetically complex populations here examined. Similarities or differences among populations were not necessarily related to geographic distances ofthe respective collection sites.     

Enhanced root nodulation of subterranean clover (Trifolium subterraneum) byRhizobium leguminosarium biovartrifolii in the presence of the earthwormAporrectodea trapezoides (Lumbricidae)

In a greenhouse study, the effect of the earthwormAporrectodea trapezoides on root nodulation in seedlings of subterranean clover (Trifolium subterraneum) was examined in the presence and absence of addedRhizobium leguminosarium biovartrifolii (strain NA 30). WhenR. trifolii NA 30 was inoculated into dung and placed on the soil surface, the total number of root nodules was five times greater (P<0.001) in the presence of earthworms than without earthworms and the number of nodules on the primary root of the plants 2–8 cm below the soil surface was 4 to 6 times greater (P<0.001) in the presence of earthworms. The additional nodulation did not affect plant growth or foliar N. When NA30 was dispersed through the soil at the beginning of the experiment, the presence of earthworms did not influence the level of root nodulation. The presence of earthworms increased root dry weight by 20–30%, plant top weight by up to 125% (P<0.001), and foliar N by 5–25% (P<0.001). Surface-applied dung increased the dry weight of plant tops (2-to 3-fold,P<0.001) but did not affect the concentration of foliar N (P<0.005).     

Possible influence of termites (Macrotermes bellicosus) on forms and composition of free sesquioxides in tropical soils

There has been less concern about soil mineralogical alteration than about soil physical, chemical and biological changes induced by termite nest-building activity. Furthermore, much less attention has been paid to free sesquioxides than to phyllosilicate minerals. In the present study, we conducted field morphological observations and selective dissolution analysis to characterize free sesquioxides in termite (Macrotermes bellicosus) mounds as compared with surrounding pedons in different toposequence positions, i.e., seasonally flooded valley bottom, hydromorphic fringe and well-drained upland sites. Distinctive redoximorphic features, such as surface yellowish layers on mound structures from the fringe site, indicate possible alteration of iron sesquioxide forms in the mounds due to the transportation of soil from reductive (aquic subsoil) to oxidative (epigeal mound) environments by the nest-building activity of M. bellicosus. On the other hand, the iron-soluble content in the dithionite-citrate-bicarbonate (DCB) system (Fe_d) was generally higher in the mound structures than at the adjacent sub-surface (Ap2) horizon at each toposequence position, while there was less difference in the content of acid ammonium oxalate (AAO) extractable iron (Fe_o) as compared to Fe_d. As a consequence, the iron activity index (Fe_d/Fe_o ratio) was found for the most part to be lower in the mound structures than in the neighboring Ap2 horizon. In addition, the content of Fe_d, AAO-soluble Al (Al_o) and DCB-extractable Al (Al_d) was significantly correlated with clay content in these soils. These findings suggest that M. bellicosus preferentially collects clay particles, probably from the clay-rich subsoils, such as the argillic horizon, which has been formed by the co-migration of phyllosilicate minerals and relatively crystalline sesquioxides. The species then likely incorporates them into the mounds, which induces an increase in the Fe_d content relative to that of Fe_o, resulting in a decreased iron activity index in the mound structures.     

Synthesis of phenoxyphenyl pyridine and pyrazine carboxamides. Activity against Cydia pomonella (L.) eggs

Several N-(4-phenoxyphenyl)pyridinecarboxamides and N-(4-phenoxyphenyl)pyrazinecarboxamides were synthesized from commercially available material, and their ovicidal activities against Cydia pomonella (L.) were tested. Some of the tested products showed a moderate activity when <24-h-old eggs were sprayed using a Potter tower. A significant increase in the length of the development period of the eggs was also observed in many cases. A clear correlation between both effects was noticed: the products that produced higher mortality also produced higher increase of the length of the development. These results seem to confirm our hypothesis that these compounds could be defined as a juvenile hormone analogues.     

堆肥微生物的培养与磷酸酶活性的研究(Ⅰ)——曲霉的产磷酸酶活性的研究

对培养过程中丝状真菌的产磷酸酶活性进行了比较,筛选了一株产磷酸酶活性较高的曲霉菌株HQ,对其产酶特性及对不同难溶性磷底物的磷释放量进行了研究.液体培养结果表明,该菌株在以植酸钠为底物时,中性磷酸酶活性为0.54mg ml-1,磷释放量46.65μg ml-1.固体培养结果表明,以畜禽废弃物为培养基的磷酸酶活性最高,其中性磷酸酶活性为37.4mg g-1.该菌株有潜力作为堆肥微生物的候选菌株.     

堆肥微生物的培养与磷酸酶活性的研究(I)——曲霉的产磷酸酶活性的研究

对培养过程中丝状真菌的产磷酸酶活性进行了比较,筛选了一株产磷酸酶活性较高的曲霉菌株HQ,对其产酶特性及对不同难溶性磷底物的磷释放量进行了研究。液体培养结果表明,该菌株在以植酸钠为底物时,中性磷酸酶活性为0.54mg m l-1,磷释放量46.65μg m l-1。固体培养结果表明,以畜禽废弃物为培养基的磷酸酶活性最高,其中性磷酸酶活性为37.4mg g-1。该菌株有潜力作为堆肥微生物的候选菌株。     

短小芽孢杆菌β-1,4-木聚糖酶基因在大肠杆菌中的高效表达

从短小芽孢杆菌(Bacillus purnilus)BP51中克隆得到木聚糖酶基因xynA。将其构建在大肠杆菌(Escherichia coli)表达载体pET21a上，转化Ecoli BL21，获得重组工程菌BLX5。经IPTG诱导，xynA基因的表达产物以胞内可溶性蛋白和包涵体形式存在。重组表达木聚糖酶的活力可达165．511U／mL培养物。重组表达的木聚糖酶最适温度为55℃，最适pH值为6．5，在碱性条件下具有良好的稳定性，降解产物以三糖、四糖和五糖为主。     

Activity of carbohydrases in the gut of Bibionidae (Diptera) larvae

Dipteran larvae play an important role in the soil of some deciduous forests. They can consume a considerable part of the annual litter fall and produce a large amount of faecal pellets, which are forming an important part of the fermentation horizon of forest soils. We measured the pH changes and assayed the activities and pH optima of saccharolytic enzymes in the digestive tracts of the larvae of Bibio pomonae and Penthetria holosericea (Bibionidae). The pH of the litter offered as a food was about 5. The gut content became highly alkaline (pH about 10) in the anterior part of the midgut and the pH decreased posteriorly and in the hindgut. Excrements were neutral or had slightly alkaline pH (7.5–8.0) in both species. The alkaline pH optima of amylase (9.5–10.0) and maltase (8.0), trehalase and cellobiase (7.0) were the same in both species. Saccharolytic activity showed an optimum at pH 7 in B. pomonae and at pH 8 in P. holosericea. Though there are previously published reports of high assimilation efficiency of bibionid larvae fed in litter (46–76% in B. pomonae), activities of both exo and endocellulases were below the detection limit of saccharolytic and chromolytic assays along a wide pH range (5–10). Possible explanations are discussed.