Can the invasive earthworm,Amynthas agrestis,be controlled with prescribed fire?

Biological invasions are one of the most significant global-scale problems caused by human activities. Earthworms function as ecosystem engineers in soil ecosystems because their feeding and burrowing activities fundamentally change the physical and biological characteristics of the soils they inhabit. As a result of this “engineering,” earthworm invasions can have significant effects on soil physical, chemical and biological properties. The species Amynthas agrestis (family Megascolecidae) was introduced to the United States from Asia, and has expanded its distribution range to include relatively undisturbed forests. Here, to clarify life history traits, we reared individuals under seven different conditions of food provision using litter, fragmented litter and soil, and also analyzed the stable isotope ratios of field-collected specimens to investigate their food resources in the field. Second, we examined whether prescribed fire can be used to manage invasive earthworms. We constructed eight experimental plots, each with 100 individuals of A. agrestis each, and burned half of the plots. The feeding experiment showed that the earthworms in units containing soil and some form of organic matter (litter and/or fragmented litter) produced many cocoons, indicating that litter and fragmented litter are important food resources for them. Stable isotope analyses also supported this result. During the experimental fires, average soil temperature at 5 cm depth increased by only 7.7 °C (average maximum of 32.2 °C). Litter mass was significantly reduced by the fires. Although numbers of A. agrestis and cocoons recovered from burned and unburned plots were not different, the viability of cocoons was significantly lower in burned plots. Fire may also reduce the survival rate of juveniles in the next year by depriving them of their preferred food resource. Most native earthworms in the United States live in the soil, while many invasive ones live in the litter layer and soil surface. Therefore, prescribed fire could be a viable tool for control of invasive earthworms without negatively impacting native earthworm populations.     

Can the Activities of Acetylcholinesterase and Glutathione S-Transferases of Crangon crangon (L.) be Used as Biomarkers of Fuel Oil Exposure?

This work aimed to determine the sensitivity of acetylcholinesterase (AChE) and glutathione S-transferases (GST) activities of Crangon crangon (L.) to the water-accommodated fraction (WAF) of the fuel oil spilled by the oil tanker Prestige, in order to assess their usefulness as markers for this kind of pollution. Laboratory exposure of shrimps to WAF of weathered Prestige fuel oil showed no significant interference with AChE activity. Significant induction of GST activity was observed, potentially as a result of high concentrations of polycyclic aromatic hydrocarbons. However, these results were only obtained with the higher WAF concentrations tested. It was concluded that AChE and GST activities of C. crangon were not useful biomarkers for short-term exposure to the WAF of fuel oil spilled by the tanker Prestige and carried to the beaches of Galicia (NW Spain).     

Can the thermodynamic melting temperature of sucrose, glucose, and fructose be measured using rapid-scanning differential scanning calorimetry (DSC)?

The loss of crystalline structure in sucrose, glucose, and fructose has been shown to be due to the kinetic process of thermal decomposition (termed apparent melting), rather than thermodynamic melting. The purpose of this research was to investigate whether or not it is possible to scan quickly enough to suppress the kinetic process of thermal decomposition and reach the thermodynamic melting temperature of these sugars using a new rapid-scanning DSC. Indium, a thermodynamic melting material, and sucrose, glucose, and fructose were analyzed at three heating rates from 1 to 25 °C/min using standard DSC and at seven heating rates from 50 to 2000 °C/min using rapid-scanning DSC. Thermodynamic melting was achieved when the onset temperature (T(m onset)) of the endothermic peak leveled off to a constant value independent of heating rate. The T(m onset) for indium was constant (156.74 ± 0.42 °C) at all heating rates. In the case of fructose, the T(m onset) increased considerably until a heating rate of approximately 698 °C/min, after which the average T(m onset) for the remaining three heating rates was constant at 135.83 ± 1.14 °C. Thus, 135.83 °C is proposed to be the thermodynamic melting temperature of fructose. It is important to note that the heating rate at which this thermodynamic melting temperature is achieved is most likely influenced by the type and amount of trace components (e.g., water and salts) contained in the fructose, which are known to vary widely in sugars. In the case of sucrose and glucose, thermodynamic melting temperatures were not able to be obtained, because the upper limit heating rate used was not fast enough to suppress thermal decomposition and achieve thermodynamic melting, perhaps due to the higher apparent T(m onset) for sucrose and glucose compared to that for fructose.     

Are survival and reproduction of Enchytraeus albidus (Annelida: Enchytraeidae) at risk by feeding on Bt-maize litter?

Enchytraeids are saprophagous soil organisms, appearing in high abundances and contributing to ecological processes within the soil. For decades they have been used as model species for biological research. In the framework of research on genetically modified plants, however, they have not been considered to date. Following the ISO/DIS guideline, survival and reproduction of Enchytraeus albidus, fed with diets containing Bt-maize (N4640Bt Cry1Ab, DKC5143Bt Cry3Bb1) leaf material were analysed. For comparison, diets with the corresponding untransformed near-isolines (N4640, DKC5143) were examined. Additionally a high quality control diet (oat flakes) was included. Survival and reproduction showed no significant differences between the Cry3Bb1 treatment and the treatment with the untransformed counterpart. For the Cry1Ab treatment survival was significantly higher than for the treatment with the corresponding near-isoline. In contrast, reproduction was significantly lower for the Cry1Ab treatment compared to that for the isoline. For the Cry3Bb1 treatment, no effect was shown on survival or reproduction. For the Cry1Ab variety and its untransformed counterpart, a contrasting result was detected, which is unlikely to be caused by the Bt-protein but rather by differences in other plant components. Overall survival and reproduction were highest for the control.     

Molecular diversity of restriction enzyme sites, Indels and upstream open reading frames (uORFs) of 5′ untransalted regions (UTRs) of Waxy genes in Triticum L. and Aegilops L. species

5′ Untransalted regions (UTR) sequences of Waxy genes were amplified from all 81 Triticum L. and Aegilops L. species by PCR with specific primers. It was found that the sequence length at 7D loci was longer than that 7B and 7A. These sequences contained 170 singleton variable sites and 484 polymorphic sites and that the average length of Indels was 8.5?bp. There were abundant regions of restriction enzyme sites and two regions of simple sequence repeat, “GAA” and “CTGA”, in all sequences. A total of 65 uORFs were detected and classed into 37 types, with the variation in uORFs mainly due to single nucleotide polymorphisms (SNPs), and also to the presence of Indels. All sequences in tetraploids and hexaploids could be grouped into Types A, B, I, II, GI and GII based on sequence variation. Restriction enzyme sites, Indel polymorphisms and the classes of uORFs present together indicated that Type I was more similar to Ae. tauschii whereas Type II was more similar to Type B, and both more similar to Ae. longissima; Type A was more similar to Ae. speltoides. Population analysis was performed and Neighbour-joining trees derived from different species, types and accessions further confirmed that the ancestors of T. urartu, Ae. speltoides, Ae. longissima and Ae. tauschii were involved to the evolution of common wheat, and also implied that Ae. longissima might have participated later than Ae. speltoides. 5′ UTRs of Waxy genes in tetraploid and hexaploid species conserved characters from their respective progenitors when compared with diploid. For the first time, we are able to conclude there is abundant variation in SNPs, Indels and uORFs between 5′ UTRs of Waxy genes from different species related to common wheat, and suggest that further research could help to understand Waxy gene function more deeply and hence improve wheat breeding. Our results also show that three hexaploid species in China have unique diversity in the 5′ UTR of their Waxy gene.     

Mycorrhiza‐soil fertility effects on regrowth,nodulation and Nitrogenase activity of siratro (Macroptilium atropurpureum (DC) Urb.)

Siratro (Macroptilium atropurpureum (DC) Urb.) is a vigorous perennial forage legume with good potential for improving pastures in the extensive neotropical regions of the world. It is well adapted to a wide range of soil and climatic conditions. The objective of these studies was to determine effects of Glomus fasciculatum colonization, rigorous defoliation, and soil fertility treatments to a Psammentic Paleustalf (Eufaula) soil on growth, regrowth, nodulation, and nitrogenase activity (C₂H₂ red.) of Siratro inoculated with Rhizobium leguminosarum Frank. Top growth increased significantly with soil K and P amendment and with mycorrhiza colonization. Nodulation and nitrogenase activity were correlated with highly significant increases from G. fasciculatum, P treatments and K additions to 300 mg K kg^‐1 soil. Growth and peduncles of nonclipped plants increased about 4 fold from 90 to 225 day age with mature seed yield increasing about 10 fold; nodule mass and nitrogenase activity levels approximately doubled. Regrowth response of plants defoliated at 45 day intervals, following their initial 90 day age, was somewhat constant between clippings for magnitude of regrowth 12.3–13.8g, development in number of peduncles 4.0–6.8, seed yield 1.4–2.6g, nodulation 2.9–3.7g, and nitrogenase activity 73.9–95.8μ mol C₂H₄g^‐1 nodule. Multiple regression for nitrogenase = 0.55 g top wt. + 0.63 g nodule wt. + 1.91 day age ‐ 0.07 peduncle no., R² = 0.85 and C.V. = 14.3%. Favorable tripartite symbiosis with both effective Rhizobium and endophyte mycorrhiza were essential for high levels of symbiotic nitrogen fixation.     

Studies of O,O-dimethyl α-(2,4-dichlorophenoxyacetoxy)ethylphosphonate (HW02) as a new herbicide. 1. Synthesis and herbicidal activity of HW02 and analogues as novel inhibitors of pyruvate dehydrogenase complex

On the basis of the previous work for optimization of O,O-diethyl α-(substituted phenoxyacetoxy)alkylphosphonates, further extensive synthetic modifications were made to the substituents in alkylphosphonate and phenoxy moieties of the title compounds. New O,O-dimethyl α-(substituted phenoxyacetoxy)alkylphosphonates were synthesized as potential inhibitors of pyruvate dehydorogenase complex (PDHc). Their herbicidal activity and efficacy in vitro against PDHc were examined. Some of these compounds exhibited significant herbicidal activity and were demonstrated to be effective inhibitors of PDHc from three different plants. The structure-activity relationships of these compounds including previously reported analogous compounds were studied by examining their herbicidal activities. Both inhibitory potency against PDHc and herbicidal activity of title compounds could be increased greatly by optimizing substituent groups of the title compounds. O,O-Dimethyl α-(2,4-dichlorophenoxyacetoxy)ethylphosphonate (I-5), which acted as a competitive inhibitor of PDHc with much higher inhibitory potency against PDHc from Pisum sativum and Phaseolus radiatus than from Oryza sativa , was found to be the most effective compound against broadleaf weeds and showed potential utility as herbicide.     

The role of stromatolites in explaining patterns of carbon, nitrogen, phosphorus, and silicon in the Se?ovlje saltern evaporation ponds (northern Adriatic Sea)

Purpose

In summer 2007, biweekly benthic fluxes of the biogenic elements carbon (C), nitrogen (N), silicon (Si), and phosphorus (P) were studied in the Se?ovlje saltern (salt-making facility) in the northern Adriatic Sea, Slovenia in order to determine the impact of stromatolite (??petola??) on the geochemical properties of saltern sediments.

Materials and methods

The brine and pore waters were analyzed for salinity, NH ₄ ⁺ , NO ₃ ^? , PO ₄ ^3? , SiO ₄ ^4? , total dissolved nitrogen, total dissolved phosphorus, and fluorescent dissolved organic matter. The sediment was analyzed for organic carbon (OC), total nitrogen (TN), total and organic phosphorus (OP), and biogenic Si concentrations, as well as values of ?? ¹³C_OC and ?? ¹⁵N_TN.

Results and discussion

Nutrient concentrations in brine water increased along the salinity gradient due to different processes, such as the evaporative concentrations of seawater, bacterial activity, more pronounced transformation and degradation of organic matter, and regeneration of nutrients. The petola from the Se?ovlje saltern, which is predominately composed of cyanobacterial and diatom communities, develops during the early evaporation stage and survives during high salinity and halite crystallization. Nitrogen fixation and P removal were the principal biogeochemical processes controlling dissolved inorganic N and P concentrations. At higher salinities, N limitation was more important. Microbes decomposed at higher salinities, and the remineralized N and P nutrients were released from surface pore waters to the brine. OP remineralization was also an important process influencing the distribution of PO ₄ ^3? concentrations in pore waters deeper in the sediments. The increasing SiO ₄ ^4? concentrations with increasing salinity in the brine waters were due to dissolution of diatom frustules, while the decrease in pore water SiO ₄ ^4? was probably the consequence of microbial uptake.

Conclusions

This study provides a better understanding of nutrient cycling and the geochemical processes in the Se?ovlje saltern.     

Genetic identity and relationships of Iranian apple (Malus?×?domestica Borkh.) cultivars and landraces, wild Malus species and representative old apple cultivars based on simple sequence repeat (SSR) marker analysis

In order to shed light on the role of Iran in apple evolution and domestication, we chose to investigate the relationships of a collection of 159 accessions of wild and domesticated apples including Iranian indigenous apple cultivars and landraces, selected wild species, and old apple scion and rootstock cultivars from different parts of the world. The majority of the wild species belonged to M. sieversii, which is widely believed to be the main maternal wild ancestor of domestic apples, from Kazakhstan and M. orientalis, which is one of the probable minor ancestors of domestic apples, from Turkey and Russia located on the east and west of Iran, respectively. The accessions were assigned into six arbitrary populations for the purpose of generating information on genetic parameters. Nine simple sequence repeat (SSR) loci selected from previous studies in apple were screened over DNA extracted from all the accessions. Results showed that all SSR loci displayed a very high degree of polymorphism with 11–25 alleles per locus. In total, there were 153 alleles across all loci with an average of 17 alleles per locus. The SSR allelic data were then used for estimation of population genetic parameters, including genetic variation statistics, F-statistics, gene flow, genetic identity, genetic distance and then cluster analysis using POPGENE 1.32 software. The F-statistics and gene flow in particular, showed that there was more intra-population than between population variation. The genetic identity and genetic distance estimates, and the dendrogram generated from the un-weighted pair group arithmetic average (UPGMA) method of cluster analysis showed that the Iranian cultivars and landraces were more closely related to M. sieversii from Central Asia (east of Iran) and M. orientalis native to Turkey and Russia than to other accessions of Malus species. Also, the old apple cultivars from different parts of the world have a closer genetic relationship to M. sieversii, M. orientalis and the Iranian apples, than to other wild species. Based on these results, we suggest that the Iranian apples may occupy an intermediate position between the domesticated varieties and wild species. We propose that Iran could be one of the major players in apples’ domestication and transfer from Central Asia to the western countries.