High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

The role of nocturnal vision in mate choice: females prefer conspicuous males in the European tree frog (Hyla arborea)

Nocturnal frog species rely extensively on vocalization for reproduction. But recent studies provide evidence for an important, though long overlooked, role of visual communication. In many species, calling males exhibit a conspicuous pulsing vocal sac, a signal bearing visually important dynamic components. Here, we investigate female preference for male vocal sac coloration—a question hitherto unexplored—and male colour pattern in the European tree frog (Hyla arborea). Under nocturnal conditions, we conducted two-choice experiments involving video playbacks of calling males with identical calls and showing various naturally encountered colour signals, differing in their chromatic and brightness components. We adjusted video colours to match the frogs'' visual perception, a crucial aspect not considered in previous experiments. Females prefer males with a colourful sac and a pronounced flank stripe. Both signals probably enhance male conspicuousness and facilitate detection and localization by females. This study provides the first experimental evidence of a preference for specific vocal sac spectral properties in a nocturnal anuran species. Vocal sac coloration is based on carotenoids and may convey information about male quality worthwhile for females to assess. The informative content of the flank stripe remains to be demonstrated.     

Multiparametric comparison of mesenchymal stromal cells obtained from trabecular bone by using a novel isolation method with those obtained by iliac crest aspiration from the same subjects

Trabecular bone fragments from femoral heads are sometimes used as bone grafts and have been described as a source of mesenchymal progenitor cells. Nevertheless, mesenchymal stromal cells (MSC) from trabecular bone have not been directly compared with MSC obtained under standard conditions from iliac crest aspiration of the same patients. This is the ideal control to avoid inter-individual variation. We have obtained MSC by a novel method (grinding bone fragments with a bone mill without enzymatic digestion) from the femoral heads of 11 patients undergoing hip replacement surgery and compared them with MSC obtained by standard iliac crest aspiration of bone marrow from the same patients. We have shown that trabecular bone MSC obtained by mechanically fragmented femoral heads fulfil the immunophenotypic and multilineage (adipogenic, osteogenic and chondrogenic) differentiation criteria used to define MSC. We have also differentially compared cellular yields, growth kinetics, cell cycle assessment, and colony-forming unit-fibroblast content of MSC from both sources and conclude that these parameters do not significantly differ. Nevertheless, the finding of slight differences, such as a higher expression of the immature marker CD90, a lower expansion time through the different passages, and a higher percentage of cycling cells in the trabecular bone MSC, warrants further studies with the isolation method proposed here in order to gain further knowledge of the status of MSC in this setting. The present study was partially supported by grant HUS01B07 from the Consejería de Educación and by grant SAN196/SA13/07 from the Consejería de Sanidad, Junta de Castilla y León, Spain.     

A SURVEY FOR 1,3,6,7-TETRAHYDROXY-C-GLYCOSYLXANTHONES EMPHASIZING THE “PRIMITIVE” LEPTOSPORANGIATE FERNS AND THEIR ALLIES

A survey for 1,3,6,7-tetrahydroxy-C-glycosylxanthones of representative species within the primitive vascular plants, emphasizing the leptosporangiate ferns, has indicated a limited distribution of these compounds within three leptosporangiate families: Hymenophyllaceae, Aspleniaceae and Marsileaceae. In the Hymenophyllaceae the distribution of these compounds appears to be a useful criterion for segregating species of Mecodium from other species of Hymenophyllum (sensu lato) and suggests that the tubulate vs. the valvate indusial condition may not be an ideal character for separating all species of Hymenophyllum (s.l.) from those of Trichomanes (s.l.). These compounds appear useful for delimiting several species of Elaphoglossum section Pachyglossa and support a relationship among the Aspleniaceae, Athyriaceae, and Elaphoglossaceae. Their presence in Marsilea also raises questions as to the origin of this group of plants.     

Comparison of rat hepatocyte and differentiated hepatoma cell line cultures as bio indicators of CYP 1A1 inducers in urban air

Cytochrome P450 1A1 CYP1A1 enzymatic activity was evaluated in cultured liver cells, and taken as a biological indicator of the presence of inducers of this isoform in urban airborne particulate matter fraction samples. It is known that CYP1A1 inducers can play an important role in the risk of mutagenesis and carcinogenesis by environmental pollution. A romatic polycyclic hydrocarbons PAH from urban air were collected in the city of Genoa Italy at two sites on two different days of the year. The objective of the study was to compare the inducibility of cultured rat hepatocytes with that of MH1C1 and FaO rat hepatoma cell lines after exposure to a PAH mixture and to a standard compound, such as benzo b fluoranthene B b F . Cytotoxic effects of the tested concentrations were evaluated by means of 3 4,5, dimenthylthyazol 2 yl 2,5 diphenyltetrazolium bromide MTT and lactate dehydrogenase release LDH tests, the potency of inducers by ethoxyresorufin O deethylase EROD assay. The results were in agreement in the three cellular systems: after exposure to the PAH mixture, an induction at low concentrations was observed; whereas no induction, but rather a decrease in activity was shown at higher concentrations; instead, the exposure to pure B b F showed a dose-response relationship in all cells, even at the highest doses. Such a difference between the toxicity of the complex mixture and that of the pure compound could be ascribed to the presence of drug metabolism inhibitors in the mixture, or to interactions between the original components and their metabolites. The finding that the cell lines responded to the CYP1A1 induction in a very efficient way gives further proof of the applicability of this system to environmental biomonitoring.     

Boron,copper, iron,manganese and zinc contents in leaves of flowering sunflower plants (Helianthus annuus,L.), grown with different boron supplies

Summary Boron, copper, iron, manganese and zinc concentrations were measured in sunflower leaves from plants grown hydroponically in a closed continuous flow system and with boron concentrations ranging from deficient to toxic. Leaves were analyzed at the stage of flower development. There was a highly significant inverse correlation between B concentration in solution and Mn concentration in leaves. Cu, Fe and Zn concentrations in the leaves were not changed by the different B levels, although the B concentration in leaves increased with an increasing concentration in solution, showing a close correlation each other.     

Antibacterial activity of ethanolic and aqueous extracts of Acacia aroma Gill. ex Hook et Arn

The purpose of the present study was to investigate the antibacterial activity of seven ethanolic extracts and three aqueous extracts from various parts (leaves, stems and flowers) of A. aroma against 163 strains of antibiotic multi-resistant bacteria. The disc diffusion assay was performed to evaluate antibacterial activity of the A. aroma crude extracts, against several Gram-positive bacteria (E. faecalis, S. aureus, coagulase-negative stahylococci, S. pyogenes, S. agalactiae, S. aureus ATCC 29213, E. faecalis ATCC 29212) and Gram-negative bacteria (E. coli., K. pneumoniae, P. mirabilis, E. cloacae, S. marcescens, M morganii, A. baumannii, P. aeruginosa, S. maltophilia, E. coli ATCC 35218, P. aeruginosa ATCC 27853, E. coli ATCC 25922). All ethanolic extracts showed activity against gram-positive bacteria. Among all obtained extracts, only leaf and flower fluid extracts showed activity against Gram-negative bacteria. Based on this bioassay, leaf fluid extracts tended to be the most potent, followed by flower fluid extracts. Minimal inhibitory concentration (MIC) values of extracts and antibiotics were comparatively determined by agar and broth dilution methods. Both extracts were active against S. aureus, coagulase-negative stahylococci, E. faecalis and E. faecium and all tested Gram-negative bacteria with MIC values from 0.067 to 0.308 mg/ml. In this study the minimal bactericidal concentration (MBC) values were identical or twice as high than the corresponding MIC for leaf extracts and four or eight times higher than MIC values for flower extracts. This may indicate a bactericidal effect. Stored extracts have similar antibacterial activity as recently obtained extracts. The A. aroma extracts of leaves and flowers may be useful as antibacterial agents against Gram- negative and Gram-positive antibiotic multi-resistant microorganisms.     

Medicago truncatula mtpt4 mutants reveal a role for nitrogen in the regulation of arbuscule degeneration in arbuscular mycorrhizal symbiosis

Plants acquire essential mineral nutrients such as phosphorus (P) and nitrogen (N) directly from the soil, but the majority of the vascular plants also gain access to these mineral nutrients through endosymbiotic associations with arbuscular mycorrhizal (AM) fungi. In AM symbiosis, the fungi deliver P and N to the root through branched hyphae called arbuscules. Previously we identified MtPT4, a Medicago truncatula phosphate transporter located in the periarbuscular membrane that is essential for symbiotic phosphate transport and for maintenance of the symbiosis. In mtpt4 mutants arbuscule degeneration occurs prematurely and symbiosis fails. Here, we show that premature arbuscule degeneration occurs in mtpt4 mutants even when the fungus has access to carbon from a nurse plant. Thus, carbon limitation is unlikely to be the primary cause of fungal death. Surprisingly, premature arbuscule degeneration is suppressed if mtpt4 mutants are deprived of nitrogen. In mtpt4 mutants with a low N status, arbuscule lifespan does not differ from that of the wild type, colonization of the mtpt4 root system occurs as in the wild type and the fungus completes its life cycle. Sulphur is another essential macronutrient delivered to the plant by the AM fungus; however, suppression of premature arbuscule degeneration does not occur in sulphur-deprived mtpt4 plants. The mtpt4 arbuscule phenotype is strongly correlated with shoot N levels. Analyses of an mtpt4-2 sunn-1 double mutant indicates that SUNN, required for N-mediated autoregulation of nodulation, is not involved. Together, the data reveal an unexpected role for N in the regulation of arbuscule lifespan in AM symbiosis.     

Heat stress screening of peanut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.) seedlings for acquired thermotolerance

Heat can be one of the major abiotic stresses that adversely affect crop production worldwide at different stages of development. As field screening for heat tolerance can be inconsistent and seasonally-limited, it is important to develop a reliable protocol under controlled conditions that allows simultaneous screening of multiple genotypes. The objective of this research was to develop a straightforward laboratory protocol using acquired thermotolerance (ATT) in peanut seedlings as a measure of one mechanism of heat stress tolerance. Sixteen genotypes, including selected accessions of the US peanut minicore collection along with standard checks, were evaluated for acquired themotolerance in two independent experiments. A change in the temperature sensitivity of chlorophyll accumulation was used as an indicator of acquired thermotolerance. Pre-incubation at 38°C for 4 h before the 30-min 50°C challenge triggered the acquired thermotolerance system of the leaf disks, resulting in chlorophyll accumulation upon exposure to light. There was considerable variation among genotypes for ATT in both experiments. Genotypic ranking for mean ATT values were highly correlated (0.949) in both experiments. The effect of seed weight on ATT was not significant. This method is relatively simple and inexpensive and can be used to screen a large number of genotypes.     

Trisomy 17 in a baboon (Papio hamadryas) with polydactyly, patent foramen ovale and pyelectasis

Trisomy 13 in humans is the third most common autosomal abnormality at birth, after trisomy 21 and trisomy 18. It has a reported incidence of between 1:5,000 and 1:30,000 live births. It is associated with multiple abnormalities, many of which shorten lifespan. We describe here the first reported case of a baboon (Papio hamadryas) with trisomy of chromosome 17, which is homologous to human chromosome 13. The trisomic infant was born to a consanguineous pair of baboons and had morphological characteristics similar to those observed in human trisomy 13, including bilateral polydactyly in the upper limbs, a patent foramen ovale, and pyelectasis. Molecular DNA analysis using human chromosome 13 markers was consistent with the affected infant inheriting two copies of chromosome 17 derived from the same parental chromosome. This trisomy was, therefore, due to either an error in meiosis II or the result of postzygotic nondisjunction. The parental origin, however, could not be determined.