Nitric oxide signaling: classical, less classical, and nonclassical mechanisms

Although nitric oxide (NO) was identified more than 150 years ago and its effects were clinically tested in the form of nitroglycerine, it was not until the decades of 1970-1990 that it was described as a gaseous signal transducer. Since then, a canonical pathway linked to cyclic GMP (cGMP) as its quintessential effector has been established, but other modes of action have emerged and are now part of the common body of knowledge within the field. Classical (or canonical) signaling involves the selective activation of soluble guanylate cyclase, the generation of cGMP, and the activation of specific kinases (cGMP-dependent protein kinases) by this cyclic nucleotide. Nonclassical signaling alludes to the formation of NO-induced posttranslational modifications (PTMs), especially S-nitrosylation, S-glutathionylation, and tyrosine nitration. These PTMs are governed by specific biochemical mechanisms as well as by enzymatic systems. In addition, a less classical but equally important pathway is related to the interaction between NO and mitochondrial cytochrome c oxidase, which might have important implications for cell respiration and intermediary metabolism. Cross talk trespassing these necessarily artificial conceptual boundaries is progressively being identified and hence an integrated systems biology approach to the comprehension of NO function will probably emerge in the near future.     

Methods for large-scale production of AM fungi: past, present, and future

Many different cultivation techniques and inoculum products of the plant-beneficial arbuscular mycorrhizal (AM) fungi have been developed in the last decades. Soil- and substrate-based production techniques as well as substrate-free culture techniques (hydroponics and aeroponics) and in vitro cultivation methods have all been attempted for the large-scale production of AM fungi. In this review, we describe the principal in vivo and in vitro production methods that have been developed so far. We present the parameters that are critical for optimal production, discuss the advantages and disadvantages of the methods, and highlight their most probable sectors of application.     

Fenpropimorph and fenhexamid impact phosphorus translocation by arbuscular mycorrhizal fungi

Fenpropimorph and fenhexamid are sterol biosynthesis inhibitor (SBI) molecules widely used to control diseases in agriculture. Both molecules, at increasing concentrations, have been shown to impact on the non-target arbuscular mycorrhizal (AM) fungi. Root colonization, spore production and mycelium architecture, including the branched absorbing structures which are thought to be involved in phosphorus (P) uptake, were affected. In the present study, we investigated the capacity of Glomus sp. MUCL 43204 to take up, transfer and translocate labelled P to Medicago truncatula in the presence of these SBI molecules. We used a strict in vitro cultivation system associating an autotrophic plant of M. truncatula with the AM fungus. In addition, the effects of both SBI molecules on the proportion of hyphae with alkaline phosphatases (ALP), succinate dehydrogenase (SDH) activity and on the expression of the mycorrhiza-specific plant phosphate transporter MtPT4 gene were examined. We demonstrated that the two SBI molecules impacted the AM fungus. This was particularly evidenced for fenpropimorph. A decrease in P transport and ALP and SDH activities associated with the extraradical mycelium and MtPT4 expression level was noted. These three factors were closely related to the development of the AM fungus, suggesting a direct impact not only on the AM fungal growth but also on the physiology and metabolic activities of the AM fungus. These results further emphasized the interest on the autotrophic in vitro culture system as an alternative to pot experiments to investigate the mechanisms behind the impact of disease control molecules on the non-target AM fungal symbionts.     

Differentially expressed cDNAs in Alternaria alternata treated with 2-propenyl isothiocyanate

The molecular mechanism of the fungal tolerance phenotype to fungicides is not completely understood. This knowledge would allow for the development of environmentally friendly strategies for the control of fungal infection. With the goal of determining genes induced by 2p-ITC, a forward suppressive subtractive hybridization was performed using cDNAs from ITC-treated Alternaria alternata as a “tester” and from untreated fungus as a “driver.” Using this approach, a library containing 102 ESTs was generated that resulted in 50 sequences after sequence assembly (17 contigs and 33 singletons). Blastx analysis revealed that 38% and 40% of the sequences showed significant similarity with known and hypothetical proteins, respectively, whereas 18% were not similar to known genes. These last sequences could represent novel genes that play an unknown role in the molecular responses of fungi during adaptation to 2p-ITC. Clones similar to opsins, ABC transporters, calmodulin, ATPases and SNOG proteins were identified. Using real-time RT-PCR analysis, significant inductions of an ABC transporter and a Ca⁺⁺ ATPase during 2p-ITC treatment were discovered. These results suggest that the fungal resistance phenotype to 2p-ITC involves calcium ions and 2p-ITC efflux via an ABC transporter.     

Anthropogenic indicators in pollen diagrams in eastern France: a critical review

The focus of palaeoenvironmental sciences on past human activities and their impact on the environment necessitates a precise understanding of the history and functioning of past and present anthropogenic ecosystems. A process is outlined which uses palaeoenvironmental and historical documentation as well as present-day observations of vegetational changes from two different plant communities, which are characterised by a very specific anthropogenic flora: arable weeds and ruderals. This study is coupled with modern pollen deposition data to deduce a set of pollen types characteristic of the range of human activities practised in eastern France, a region rich in pollen data. First, phytogeographical analysis of the evolution of these plant communities since the Neolithic enables the comparison to be validated. By distinguishing between native plants and aliens introduced long ago (archaeophytes), or more recently (neophytes), and by refining their ecological characteristics, the method also enables identification of species that are strong indicators of human activities. Next, local pollen deposition in these vegetation types is examined with a number of statistical analyses (PCIA, Davis indices), confirming the relationships between a given vegetation community, its theoretical pollen rain and its actual pollen rain, thus distinguishing local and regional pollen indicators. Lastly, comparison of the results obtained by these two approaches leads to a critical synthesis of the traditional anthropogenic pollen indicators (Behre’s “indicator species”) in the study area and to the establishment of more specific local pollen indicators.     

Anti-inflammatory and cytotoxic activities of chichipegenin, peniocerol, and macdougallin isolated from Myrtillocactus geometrizans (Mart. ex Pfeiff.) Con

The oleanane-type triterpene chichipegenin and the sterols peniocerol and macdougallin, isolated from Myrtillocactus geometrizans, showed anti-inflammatory activities in both the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema model and the carrageenan-induced rat paw edema model. All tested compounds inhibited the TPA-induced edema in a dose-dependent manner, with ED50 values less than or equal to that shown by indomethacin. Among them, peniocerol was the most active compound. However, only peniocerol and macdougallin reduced carrageenan-induced rat paw edema. On the other hand, peniocerol and macdougallin showed cytotoxicity against several human cancer cell lines. These results indicate that compounds isolated from M. geometrizans possess antiinflammatory and cytotoxic properties, and the presence of chichipegenin in the aerial parts could justify the medicinal uses attributed to the plant.     

Cotton cultivation and textile production in the Arabian Peninsula during antiquity; the evidence from Mada��in Salih (Saudi Arabia) and Qal��at al-Bahrain (Bahrain)

The discovery of seeds and textiles from Gossypium (cotton) in Achaemenian levels of the mid-6th–late 4th century b.c. at Qal’at al-Bahrain, Bahrain and in early 1st millennium a.d. at Mada’in Salih, Saudi Arabia, reveals the role played by the Arabian Peninsula as a textile production centre during the centuries before and after the beginning of the Christian era. Both these sites were situated on important trade routes, overseas (Qal’at al-Bahrain) and overland (Mada’in Salih), and it is likely that at least part of the cotton production was intended for trade, complementing and perhaps competing with other sources of cotton textiles in the contemporary Middle East. In the arid climate of the Arabian Peninsula, cotton was probably grown in association with irrigated date palm gardens where a wide array of other crops was grown, as is shown by the analysis of charred seeds and wood from occupation levels at both sites. The present article places these particular finds in the larger context of cotton cultivation in the Middle East and India.     

Antileishmanial and antitrypanosomal activity of triterpene derivatives from latex of two Euphorbia species

The in vitro activity on Leishmania infantum promastigotes and Trypanosoma cruzi epimastigotes of 25 semisynthetic terpenoid derivatives has been evaluated. These compounds were obtained through chemical modifications of the major components of Euphorbia resinifera (alpha-euphol and alpha-euphorbol) and Euphorbia officinarum (obtusifoliol and 31-norlanosterol). Leishmaniasis and Chagas' disease are major worldwide health problems. The drugs of choice for their treatment are still problematic in both cases, and therefore there is an urgent need to discover new drugs with high activity and low side effects. Natural products have become a key source of new drugs in the last years. The genus Euphorbia has been the subject of abundant phytochemical and pharmacological research because of its potential medical applications, but the antiparasitic effects of derivatives from plants of this genus are still unknown. Our results showed that 76% and 64% of the test compounds had antiparasitic effects on L. infantum and T cruzi, respectively. The different activities on both parasites, especially their moderate effects on mammalian cells, indicate an interesting selective toxicity.     

Pig transgenesis by Sleeping Beauty DNA transposition

Modelling of human disease in genetically engineered pigs provides unique possibilities in biomedical research and in studies of disease intervention. Establishment of methodologies that allow efficient gene insertion by non-viral gene carriers is an important step towards development of new disease models. In this report, we present transgenic pigs created by Sleeping Beauty DNA transposition in primary porcine fibroblasts in combination with somatic cell nuclear transfer by handmade cloning. Göttingen minipigs expressing green fluorescent protein are produced by transgenesis with DNA transposon vectors carrying the transgene driven by the human ubiquitin C promoter. These animals carry multiple copies (from 8 to 13) of the transgene and show systemic transgene expression. Transgene-expressing pigs carry both transposase-catalyzed insertions and at least one copy of randomly inserted plasmid DNA. Our findings illustrate critical issues related to DNA transposon-directed transgenesis, including coincidental plasmid insertion and relatively low Sleeping Beauty transposition activity in porcine fibroblasts, but also provide a platform for future development of porcine disease models using the Sleeping Beauty gene insertion technology.