Antimicrobial study of essential oils of Ocimum gratissimum leaves and Zanthoxylum xanthoxyloides fruits from Cameroon

An investigation of antimicrobial activities of essential oils of fresh leaves of Ocimum gratissimum and the essential oil of the dried fruits of Zanthoxylum xanthoxyloides was carried out. The essential oils showed extensive inhibition zones and are, therefore, effective antimicrobial systems.     

Ulocladium chartarum as the causal agent of a leaf necrosis on Quercus pubescens

Summary A necrosis of leaves of Quercus pubescens caused by the fungus Ulocladium chartarum is reported. This fungus causes leaf spots both under natural conditions and following artificial inoculation of unwounded attached leaves. A high incidence of leaf spotting by U. chartarum seems to be associated with wet summers.     

Ent-trachyloban-19-oic acid isolated from Iostephane heterophylla as a promising antibacterial agent against Streptococcus mutans biofilms

From the roots of Iostephane heterophylla, six known compounds, namely, ent-trachyloban-19-oic acid (1), the mixture of ent-kaur-16-en-19-oic acid (2) and ent-beyer-15-en-19-oic acid (3), xanthorrhizol (4), 16α-hydroxy-ent-kaurane (5) and 16α-hydroxy-ent-kaur-11-en-19-oic acid (6) were isolated using a bioassay-guided fractionation method. The known compounds (1-6) were identified by comparison of their spectroscopic data with reported values in the literature. In an attempt to increase the resultant antimicrobial activity of 1 and 4, a series of reactions was performed on ent-trachyloban-19-oic acid (1) and xanthorrhizol (4), to obtain derivatives 1a, 1b, and 4a-4d. All the isolated compounds (1-6) and the derivatives 1a, 1b, and 4a-4d were evaluated for their antimicrobial activity against two oral pathogens, Streptococcus mutans and Porphyromonas gingivalis associated with caries and periodontal disease, respectively. Compounds 1, 1b, 2+3, 4 and 4d inhibited the growth of S. mutans with concentrations ranging from 4.1 μg/mL to 70.5 μg/mL. No significant activity was found on P. gingivalis except for 4 with an MIC of 6.8 μg/mL. The ability of 1, 1b, 2+3, 4 and 4d to inhibit biofilm formation by S. mutans was evaluated. It was found that 1, 1b, 4 and 4d interfered with the establishment of S. mutans biofilms, inhibiting their development at 32.5, 125.0, 14.1 and 24.4 μg/mL, respectively.     

Discula quercina as a possible causal agent of dieback on oak trees in Iran

During spring and summer of 2016, dieback symptoms including blights of leaves, twigs, and acorns were observed on current year shoots of Quercus infectoria in the Zagros oak forests of Iran. The fungus isolated from damaged tissues was identified as Discula quercina based on both morphological characteristics and ITS sequencing. To fulfil the Koch's postulates, a representative isolate was inoculated onto shoots of Q. infectoria and Quercus libani in both laboratory and forest conditions. Responses of the two oak species to inoculation with D. quercina were examined under laboratory and forest conditions in a completely randomized experiment. Discula quercina was clearly involved in oak dieback, and Q. infectoria was more susceptible than Q. libani to damage by the pathogen. This is the first record of the occurrence and pathogenicity of the fungus Discula quercina on Quercus infectoria. The fungus is considered as an emerging pathogen on oak trees in Zagros forests in Iran. Furthermore, the pathogenicity of the Discula quercina on Q. libani under laboratory and forest conditions increases the potential importance of this pathogen in Zagros forests.     

In vitro and in vivo immune stimulating effects of a new standardized Echinacea angustifolia root extract (Polinacea)

Polinacea is a new standardized hydroethanolic extract obtained from Echinacea angustifolia roots containing echinacoside (>4%), the high molecular weight polysaccharide IDN 5405 (>5%) and a isobutylamide fraction (<0.1%). For in vitro tests, a bacterial lipopolysaccharide-free (LPS-free) Polinacea has been prepared in order to avoid non-specific responses of immunocompetent cells. LPS-free Polinacea enhanced the immune functions as highlighted by the proliferation rate and gamma-interferon production in murine T-lymphocyte cell cultures stimulated by anti-CD3. LPS-free Polinacea did not have a direct role on macrophage response as measured in the nitric oxide production test using the J774 macrophage cells line. In vivo, Polinacea showed an immune stimulating activity by reducing the Candida albicans induced mortality both in normal and in cyclosporin A-treated mice.     

Somaclonal variation in growth, leaf phenotype and gas exchange characteristics of poplar: utilization of leaf morphotype analysis as a basis for selection

Populus hybrid TT32 lines produced from 15 treatment tissue culture regimes exhibited somaclonal variation in morphological and gas exchange parameters. Within four years of regeneration, discrete lines showing statistically validated superior, or inferior, growth performance relative to the parental reference clone were identified. Significant differences in the ratio of leaf length/width between treatment lines provided the earliest reliable indicator of the divergence in overall growth performance. Despite discernible variation in leaf phenotype among primary regenerants and secondary propagules within individual lines, the leaf length/width ratio was identified as a potential parameter for predicting growth performance. Its subsequent use led to the recognition of four distinct leaf morphotypes; cordate, ovate, reniform and oval. Two or more of these morphotypes were distributed within each of the original 15 treatment lines. Regrouping the data on the basis of leaf morphotype resulted in a clear segregation of the morphological traits, and revealed differences that were not readily apparent by statistical analysis based on treatment groups. The demonstration of similar relative performances by individual morphotypes with respect to a range of growth and gas exchange parameters confirmed that variation in leaf morphology was indicative of differential photosynthetic performance. Somaclonal variants with a leaf morphology was indicative of differential photosynthetic performance. Somaclonal variants with a leaf morphotype closest to that of the parental line showed the highest overall potential for selection, suggesting that the greatest benefits accrue from a minimal disturbance of the parental leaf phenotype.     

Comparing the use of leaf and soil analysis as N and P availability indices in a wildfire chronosequence

Two types of measures have traditionally been used to monitor changes after disturbances in the nutrient availability of forest ecosystems: (1) soil nutrient pools and transformation rates and (2) foliar nutrient content. We used a wildfire chronosequence in natural and unmanaged Pinus canariensis forests to determine which kind of measure is more effective in discriminating between disturbed and undisturbed plots and to determine whether the different availability indices provide comparable and consistent results within the chronosequence and between different sampling dates. The results showed that (1) foliar N and P concentrations were the variables that best discriminated between the plots of the chronosequence, (2) the various soil N availability indices neither showed steady relationships nor predicted the plant nutrient availability, and (3) P availability indices showed steady relationships and predicted plant nutrient availability. Due to the changing nature of the soil N pools, repeated sampling over a long period of time could yield results different from those presented here. However, the large sampling effort required would favor the use of foliar nutrient concentrations as the most desirable first approach to the community’s nutritional status, especially when time or budget constraints are relevant.     

Stomatal responses to drought at a Mediterranean site: a comparative study of co-occurring woody species differing in leaf longevity

We studied stomatal responses to decreasing predawn water potential (Psipd) and increasing leaf-to-air water vapor pressure difference (VPD) of co-occurring woody Mediterranean species with contrasting leaf habits and growth form. The species included two evergreen oaks (Quercus ilex subsp. ballota (Desf.) Samp. and Q. suber L.), two deciduous oaks (Q. faginea Lam. and Q. pyrenaica Willd.) and two deciduous shrubs (Pyrus bourgaeana Decne. and Crataegus monogyna Jacq.). Our main objective was to determine if stomatal sensitivity is related to differences in leaf life span and leaf habit. The deciduous shrubs had the least conservative water-use characteristics, with relatively high stomatal conductance and low stomatal sensitivity to soil and atmospheric drought. As a result, Psipd decreased greatly in both species during the growing season, resulting in early leaf abscission in the summer. The deciduous oaks showed intermediate water-use characteristics, having maximum stomatal conductances and CO2 assimilation rates similar to or even higher than those of the deciduous shrubs. However, they had greater stomatal sensitivity to soil drying and showed less negative Psipd values than the deciduous shrubs. The evergreen oaks, and especially the species with the greatest leaf longevity, Q. ilex, exhibited the most conservative water-use behavior, having lower maximum stomatal conductances and greater sensitivity to VPD than the deciduous species. As a result, Psipd decreased less during the growing season in the evergreens than in the deciduous species, which may contribute to greater leaf longevity by avoiding irreversible damage during the summer drought. However, the combination of low maximum CO2 assimilation rates and high stomatal sensitivity to drought must have a negative impact on the final carbon budget of leaves with a long life span.     

Protective effect of Piper longum fruit ethanolic extract on radiation induced damages in mice: a preliminary study

The radioprotective property of an ethanolic extract of Piper longum fruits (EEPLF) was investigated in Swiss mice. The white blood cell (WBC) count in irradiated control mice was drastically reduced to 1900 cells/mm3 on third day but in treated animals the count was 2783.3 cells/mm3. The number of bone marrow cells and alpha-esterase positive cells was also enhanced by the EEPLF administration (16.7 x 10(6) cells/femur and 946.5/4000 cells, respectively) when compared to the radiation exposed control animals (12.2 x 10(6) cells/femur and 693.5/4000 cells, respectively). EEPLF reduced the elevated levels of glutathione pyruvate transaminase (GPT), alkaline phosphatase (ALP), and lipid peroxidation (LPO) in liver and serum of radiation treated animals. The extract administration also increased the reduced glutathione (GSH) production to offer the radioprotection.     

Effect of a propolis extract and caffeic acid phenethyl ester on formation of aberrant crypt foci and tumors in the rat colon

We have studied the effect of propolis and its main active ingredient caffeic acid phenetyl ester (CAPE) on formation of aberrant crypt foci (ACF) and tumors in the rat colon in vivo. CAPE (50 mg/kg i.p.) reduced the formation of ACF and tumor induced by azoxymethane, while propolis ethanolic extract was without effect. These results suggest a potential anti-carcinogenesis of CAPE but not propolis.     

Importance of woody materials for seasonal variation in leaf area index from optical methods in a deciduous needleleaf forest

Woody materials (woody area index, WAI) is a key error source in estimating leaf area index (LAI) by optical methods, but how to correct the error caused by WAI during different seasons has not reached consensus. In this study, effective plant area index (PAI_e) was first estimated using two indirect optical methods (digital hemispherical photography, DHP, and LAI-2000) in a deciduous needleleaf forest, and then four different schemes for correcting the contribution of WAI to PAI_e were tested here. We also directly estimated the seasonality of LAI by a litter collection method and an allometric method. Directly subtracting WAI from PAI resulted in a greater degree of uncertainty in correcting seasonal changes of PAI_e from both DHP and LAI-2000. Therefore, we introduced a new correction factor, the stem-to-total area ratio, which was reasonable and useful for quantifying seasonal changes in the contribution of WAI to PAI_e. We finally recommend a practical scheme for correcting PAI_e from both DHP and LAI-2000, with accuracies as high as 88% and 87% during most growing seasons, respectively. Additionally, LAI values estimated from allometry were concordant with those estimated from litter collection, indicating that the allometry method is useful for tracking seasonal changes in LAI.     

Application of cationic polymer prepared from sulfuric acid lignin as a retention aid for usual rosin sizes to neutral papermaking

Cationic polymers that acted as the retention aids for usual rosin sizes in neutral papermaking were prepared from sulfuric acid lignin (SAL), one type of acid lignin. To convert SAL to the cationic polymer (MP-SAL), SAL was phenolated and then treated by the Mannich reaction to introduce the amino groups. In the MP-SAL single system, MP-SAL exhibited high sizing effectiveness in neutral papermaking with the rosin emulsion size. However, MP-SAL showed no sizing effectiveness when soap rosin size was used. MP-SAL showed increased sizing effectiveness as the pK _a of the introduced amino group increased. From this and comparison of the sizing degrees of MP-SAL and polyethylenimine, which possesses a linear structure, it was suggested that the sizing effectiveness was not only affected by the charge density and molecular weight, but also by the basicity of the introduced amino groups and the molecular structure of the retention aid. In the alum–MP-SAL dual system, alum and MP-SAL synergistically enhanced the sizing effectiveness in the rosin emulsion sizing at neutral pH. In turn, this allowed a decrease in the MP-SAL dosage and resulted in a small decrease in brightness.Part of this report was presented at the 48th Lignin Symposium, October 2003, Fukui     

Effectiveness of a detached‐leaf assay as a proxy for stem inoculations in backcrossed chestnut (Castanea) blight resistance breeding populations

A recently developed detached‐leaf blight resistance assay has generated interest because it could reduce the amount of time needed to evaluate backcrossed hybrid trees in the American chestnut blight resistance breeding programme. We evaluated the leaf inoculation technique on a sample of advanced progeny from the Indiana state chapter American Chestnut Foundation breeding programme, along with susceptible American chestnut (Castanea dentata), the recurrent parent, and resistant Chinese chestnut (Castanea mollissima), the donor parent for blight resistance. In experiments over 2 years using two pathogen isolates, we found no biologically meaningful relationship between leaf lesion size and the size (length and width) or severity (1–5 canker severity rating) of stem cankers on 5‐year‐old trees. Chinese chestnuts did develop significantly smaller leaf lesions than American or backcrossed chestnuts. We conclude that while the detached‐leaf assay may have utility in some chestnut breeding applications, it is not a suitable proxy for the established practice of stem inoculations.     

Identification of defect position in a wooden beam from the power spectrum of longitudinal vibration

The inverse solution procedure that enables the identification of the defect position in a beam from the resonance frequency was exploited. Resonance frequency shifts of a power spectrum due to defects in a longitudinally vibrating beam when both ends are free were investigated by both numerical and experimental analysis. Calculation by a transfer matrix method showed that the frequency shift was large when the defect position coincides with a node of vibration and that no shift occurs when it coincides with a loop of vibration. The frequency shift could be approximated by a sinusoidal curve. Calculation results agreed well with those of the experiment in which artificial round holes were drilled as the defect model. Experimental equations predicting the amount of the frequency shift in function of the defect position were obtained. In the inverse procedure, the defect position was determined by comparing the resonance frequencies between the experimental and estimated power spectra so that the coincidence factor S(x) became a minimum. The results showed the validity of the proposed method to identify the defect positions of fewer than two predominant defects.     

山西平陆枯死油松线虫分离物鉴定

对山西平陆县28年生枯死油松进行了取样、分离、镜检,发现13个样品中有4个样品分离到线虫。通过对分离物的形态测量与比对,鉴定为拟松材线虫,且样品中分离线虫的数量较少。所分离的拟松材线虫株系为东亚型拟松材线虫。     

Potential use of hydroxytyrosol-rich extract from olive mill wastewater as a biological fungicide against <Emphasis Type="Italic">Botrytis cinerea</Emphasis> in tomato

Olive mill wastewater (OMW) is a rich source of antifungal agents and has a merit as alternative to synthetic fungicides. To develop disease control agents against Botrytis cinerea, a hydroxytyrosol-rich (29.27% weight:dry weight) olive mill wastewater (HROMW) and a hydroxytyrosol-rich (52.67% weight:dry weight) extract (HRE) were prepared from fresh OMW using hydrolysis and post-hydrolysis purification processes. The HROMW and HRE showed strong fungicidal activity against B. cinerea with minimal fungicidal concentrations (MFCs) of 14.36–28.72 and 28.72–57.44 mg l⁻¹ (dry weight), respectively. According to EN 1275: 1997 standard method, HROMW and HRE at 1.25% (dry weight:volume) showed powerful disinfectant properties resulting in a reduction in the viability of B. cinerea spores by >4 log units after 30 min of contact time. The HROMW or HRE foliar spray treatments, of the B. cinerea inoculated tomato plants, resulted in disease control percentage of 95 and 91%, respectively, whereas 70% was conferred by benomyl treatment. Although, HRE possessed a similar disease severity reduction than HROMW, it showed great advantage by fortifying plants and by improving their growth and healthy aspect. Indeed, HRE-treated plants showed significantly better: (i) plant height (146.2 and 130.5%), (ii) average stem diameter (135% and 110%), (iii) leaf number (163.6 and 128.5%), and (iv) leaf colour (chlorophyll a content) (144.4 and 103%) than benomyl-treated and non-treated plants, respectively. This study revealed that HRE offers a natural and effective extract to control grey mould.     

Genomic DNA methylation of juvenile and mature Acacia mangium micropropagated in vitro with reference to leaf morphology as a phase change marker

Genomic DNA methylation was analyzed in Acacia mangium Willd. microshoots micropropagated in vitro from juvenile and mature explants, and in relation to leaf morphology of the microshoots, which is considered a phase change indicator. Based on high performance liquid chromatography (HPLC) analyses, we found more DNA methylation in microshoots exhibiting juvenile leaf morphology (22.4%) than in microshoots of the mature phyllode morphological type (20.7%), irrespective of the age of the source material. Overall, the degree of DNA methylation in A. mangium microshoots was consistent with values reported for other angiosperms. Complementary investigations based on methylation sensitive amplification polymorphism (MSAP) techniques established that, of 1204 fragments revealed by the different primer pairs used, 49 (i.e., 4.08%) were derived from C(5m)CGG methylated sites. Three of these C(5m)CGG sites were exclusive to the juvenile plant material, and three sites were exclusive to the mature source. No fragments were associated specifically with leaf morphology, rather than with plant age. Thus, although the two age classes could not be distinguished based on a quantitative HPLC measure of DNA methylation, qualitative differences existed, as demonstrated by the six age-specific markers identified by MSAP. The reliability of the MSAP data was confirmed on a larger sample of juvenile plant material, which suggested that the total of six methylation markers detected is probably an underestimation of the age-related differences in DNA methylation that may exist between juvenile and mature plant materials.     

Identification of selected internal wood characteristics in computed tomography images of black spruce: a comparison study

The feasibility of identifying internal wood characteristics in computed tomography (CT) images of black spruce was investigated using two promising classifiers: the maximum likelihood classifier (MLC) and the back propagation (BP) artificial neural network (ANN) classifier. Nine image features including one spectral feature (gray level values), a distance feature, and seven textural features were employed to develop the classifiers. The selected internal wood characteristics to be identified included heartwood, sapwood, bark, and knots. Twenty cross-sectional CT images of a black spruce log were randomly selected to develop the two classifiers. The results suggest that both classifiers produced high classification accuracy. Compared with the MLC classifier (80.9% overall accuracy), the BP ANN classifier had better classification performance (97.6% overall accuracy). Moreover, statistical analysis reveals that the heartwood of the black spruce log used in this study is the easiest to identify by either classifier compared with the other three log features. The results also suggest that the separability of one wood characteristic from the other wood characteristics in black spruce CT images is mainly related to moisture content.     

Evaluation of the effectiveness ofBacillus thuringiensis var.entomocidus as a pest control agent to replace chemical pesticides in alfalfa fields in Israel

The Egyptian cotton leafworm,Spodoptera littoralis Boisd., is the main important pest of alfalfa in Israel. Population levels of other pests usually do not reach the economic threshold. Nine chemical insecticide applications (7 spray applications and 2 granular fluorosilicate baits) were required to controlS. littoralis during the season of 1984 (in which infestation level was high) whereas only 5 applications of aBacillus thuringiensis var.entomocidus (Bte) preparation (3 sprays and 2 baits) produced the same effect. During 1983 and 1985 pest populations were moderate and only 6 chemical pesticide applications were required. A bait ofBte on wheat bran, Coax^®, developed in the present study was effective in the control of large larvae (instars 4–6). Hay yields of fields treated withBte were similar to the yields of a conventionally treated field. The best control of large larvae was obtained by applying the bait preparation under the wind row during the alfalfa cutting.