Molecular phylogeny of the apterygotan insects based on nuclear and mitochondrial genes

Basal hexapodan orders (Apterygota) are traditionally divided in two well defined taxonomic groups, Entognatha and Ectognatha. Entognathy (the enclosed mouthparts condition) is considered the most distinctive character joining the Ellipura (Protura+ Collembola) with the order Diplura, whereas the presence of exposed mouthparts (ectognathy) is the feature shared by Microcoryphia and Zygentoma with the pterygote insects. In spite of the growing interest for the evolutionary history of the Apterygota, there is no complete agreement among the general phylogenetic hypotheses based on the study of morphological characters. In this study we analyzed the DNA sequence of segments of the nuclear Elongation Factor-1α(EF-1α) and of the mitochondrial 12S rRNA genes, and used different methods of phylogenetic reconstruction. The 12S gene seems to be more suited than the EF-1α to resolve some of the most outstanding systematic disputes, whereas the lack of resolution at the deeper nodes does not allow to assess the phylogenetic relationships within Microcoryphia and between ectognathan orders. We have obtained a fairly high support for the monophyly of the orders Diplura and Zygentoma. In the 12S analysis, the Ellipura and the Entognatha form monophyletic assemblages. In addition, the study of the distribution of introns in the EF-1α suggests a relationship between Collembola and Diplura.     

Citrantifidiene and citrantifidiol: bioactive metabolites produced by Trichoderma citrinoviride with potential antifeedant activity toward aphids

Two novel metabolites with potential antifeedant activity were isolated from cultures of the fungus Trichoderma citrinoviride strain ITEM 4484 grown in solid-state fermentation on sterile rice kernels. The producing strain was identified at species level by sequence analysis of the internal transcribed spacer regions ITS-1 and ITS-2 of the nuclear rDNA and a fragment of the translation elongation factor gene TEF-1alpha. Fractionation by column chromatography and TLC of the culture organic extract, followed by feeding preference tests on the aphid pest Schizaphis graminum (Rondani), allowed the purification of 5.8 and 8.9 mg/kg of culture of two bioactive metabolites, which were named citrantifidiene and citrantifidiol ( 1 and 2). Citrantifidiene and citrantifidiol, whose structures were determined by spectroscopic methods (NMR and MS) are a symmetrical disubstituted hexa-1,3-dienyl ester of acetic acid and a tetrasubstituted cyclohexane-1,3-diol, respectively. The pure metabolites influenced the feeding preference of S. graminum restraining individuals from feeding on wheat leaves dipped in 5% aqueous methanol solution containing 0.57 mg/mL of citrantifidiene or 0.91 mg/mL of citrantifidiol.     

Does Biochar Improve Establishment of Tree Seedlings in Saline Sodic Soils?

Reforestation of saline sodic soil is increasingly undertaken as a means of reclaiming otherwise unproductive agricultural land. Currently, restoration of degraded land is limited to species with high tolerances of salinity. Biochar application has the potential to improve physical, biological and chemical properties of these soils to allow establishment of a wider range of plants. In a glasshouse trial, we applied biochar made from Acacia pycnantha (5 Mg ha⁻¹) or no biochar to either a low (EC_e 4·75 dS m⁻¹, ESP 6·9), a moderate (EC_e 27·6 dS m⁻¹, ESP 29·3) or a high (EC_e 49·4 dS m⁻¹, ESP 45·1) saline sodic soil. The regional common reforestation species Eucalyptus viminalis and Acacia mearnsii were planted as tubestock in to the soils. Early establishment indicators, including growth, plant condition and nutrition, were assessed at the end of a simulated growing season, 108 days after biochar application. Application of biochar increased height, and decreased root : shoot and the concentration of Mn, N and S in plants of E. viminalis when grown in the highly saline sodic soil. Biochar application increased the concentration of B in leaves of E. viminalis and increased the concentration of P, K and S in leaves of A. mearnsii when grown in the low saline sodic soil. The results confirm that there is potential for biochar to assist in reforestation of saline sodic soils. Copyright © 2015 John Wiley & Sons, Ltd.     

Maguey (<Emphasis Type="Italic">Agave salmiana</Emphasis>) infructescence morphology and its relationship to yield components

Agaves are long-lived semelparous plants that produce a high number of seeds, in dehiscent capsules, on the apical section of a stalk, up to 5 m long, after 8–25 years. These and other characteristics such as yield and yield components are scarcely evaluated in the plants of the Agave genus. The objective of this study was to quantify the capsules and seeds yield of A. salmiana Otto ex Salm-Dyck plants simultaneously maturing and growing in the same region. Infructescences of three plants simultaneously growing at San Luis Potosí, Mexico, were harvested. On them we evaluated the number of umbels, capsules and seeds (normal and sterile) and their mass per plant. The study was developed on a completely randomized design with each infructescence as an experimental unit. Also, the type distribution of the number and mass of these yield components along the stalk was evaluated with the Chi square test for goodness of fit, the Shapiro–Wilks for normality tests, asymmetry and kurtosis. Data were analyzed with the ANOVA and multiple comparisons by the Tukey test (p?≤?0.05). The number of umbels per plant (17–25), capsule per umbel (2–179) and per plant (554–1990), normal seed per capsule (0–297), normal seeds per plant (30,610–186,209) and sterile seeds per plant (211,059–619,251) widely and significantly varied among infructescences. Biomass of capsules per plant umbel (3–795 g), biomass of sterile and normal seeds per capsule (0.071–1.449 and 0–3.320 g), per umbel (0.34–97.76 and 0.21–185.26 g) and per plant (182–1052 and 334–2069 g) also varied widely. Seed yield was statistically different between plants simultaneously growing and maturing at the same site.     

Influence of colored plastic mulch on soil temperature,growth, nutrimental status,and yield of bell pepper under shade house conditions

The aim of this study was to determine if plastic mulch films may have positive effects on bell pepper plants grown under shade house conditions. The experimental design was split-plot, where large plots contained four plastic mulch films (black, aluminum, silver, and white) compared to bare soil and small plots contained two bell pepper cultivars. Plant shoot dry weight was higher in plastic mulch treatments than in bare soil. The net photosynthesis rate in the cultivar SWG-46 exceeded in net photosynthesis with respect to the cultivar SWG-42 in one of three sampling dates. Nutrients in leaf showed a similar behavior in plastic mulch treatments than the control but the total content of nitrogen (N), potassium (K), and sulfur (S) was increased. The total yield was higher in black plastic mulch than in the other plastic mulch colors and lowest in the control.     

Rapid determination of diphenylamine residues in apples and pears with a single multicommuted fluorometric optosensor

In this work, a single flow injection multicommuted system using solid-surface fluorescence spectroscopy has been explored for the determination of diphenylamine in apples and pears. The native fluorescence signal of diphenylamine retained on the solid support (C18 silica gel) was used for its determination (lambda(exc)/lambda(em) 291/372 nm). The sample treatment consists of a liquid-liquid extraction with acetonitrile followed by a cleanup step using primary-secondary amines. The use of a continuous flow assembly implementing multicommutation, based on a set of three-way solenoid valves controlled by appropriate software, provides the automatic control of sample, carrier, and eluting solution with remarkable advantages in relation to conventional flow injection approaches. Using an optimized sampling time, the proposed method was linear in the range 0.25-5 mg kg(-1) with a detection limit of 0.06 mg kg(-1) and RSD (percent) values better than 3%. The proposed method was successfully applied to the analysis of diphenylamine in different apple and pear samples fortified at different concentrations, and recoveries between 78 and 104% were found. The results obtained illustrate the usefulness of the proposed method for the screening and evaluation of postharvest treatment of crops possibly containing diphenylamine.     

Effect of colored plastic mulch on growth,yield and nutrient status in cucumber under shade house and open field conditions

The aim of this study was to realize whether soil mulching, with different plastic mulch colors, is a suitable practice under shade house (SH) conditions for the culture of cucumber. To do so, cucumber was cultured mulched or not with black, blue, red or white-on-black plastic films under SH, and contrasted against mulched cucumber in open field (OF). Red mulch produced the highest shoot dry weight per plant and bare soil the lowest. However, it was the white mulch which produced the highest commercial yield per plant. Contrastingly, bare soil plants produced the lowest commercial yield. SH plants two folded photosynthetic rates compared to OF plants. Mulch color mainly impacted leaf phosphorus (P) and magnesium (Mg) content while the SH affected nitrogen (K), calcium (Ca) and magnesium (Mg). Our results confirm that soil mulching, and shading positively impact the cucumber yield and quality but also show that soil mulching under SH enhances cucumber crop.     

Heavy metal and PCB spatial distribution pattern in sediments within an urban catchment—contribution of historical pollution sources

Purpose

This work analyzes polychlorinated biphenyl (PCB) and heavy metal contamination in fluvial sediments and soils in an urban catchment, according to the geo-accumulation index and to soil and sediment quality guidelines. The catchment is located in Coimbra, Portugal, being affected by frequent flooding, and its main stream is a tributary to one of the major rivers in Portugal (Mondego). Given the presence of industrial activities over time, some inputs of pollutants are expected, but so far, the legacy of historic pollution in this catchment has not yet been investigated.

Materials and methods

Twenty-five samples were collected from nine sampling sites at the depths of 0–20, 20–40 and 40–60 cm (to provide a historic perspective) along longitudinal profiles (streamlines) and in soils downstream of pollution sources. These samples were analyzed for six heavy metals (Cu, Cr, Pb, Cd, Zn, Ni), organic carbon, pH and ten PCBs (IUPAC numbers 28, 30, 52, 101, 138, 153, 166, 180, 204, 209).

Results and discussion

Total PCB concentrations ranged 0.47–5.3 ng g^?1 dry weight (dw), and levels increase from the bottom to the top layers, suggesting an increased input over the last 100 years. PCB congener distribution shows the dominance of hexachlorobiphenyls, especially PCB138, suggesting the existence of local sources. PCB levels did not exceed sediment quality levels, placing sediments/soil under class 1 (not contaminated) or class 2 (trace contamination) with respect to PCB. All six metals exceeded the lowest effect level for sediment quality criteria, and three (Cd, Pb and Zn) largely exceeded the clean levels for dredged materials, placing sediments in class 5 (heavily contaminated). Sampling site S1 presented the highest concentrations of Zn, Pb and Cd, and historic vehicle traffic was identified as the most likely source, given the vertical and horizontal profiles.

Conclusions

High levels of Pb, Cd and Zn were found in fluvial sediments at some locations of the Loreto catchment, likely from historic traffic sources. This urban area is frequently affected by flooding events and is currently being subject to urban redevelopment. During these events/actions, historic pollutants in the sediments might surface and be redistributed, impacting the downstream ecosystem of the major Mondego River or increasing the risk of exposure of the urban population.