Comparative Analysis of Nucleotide Fluorescent Analogs for Registration of DNA Conformational Changes Induced by Interaction with Formamidopyrimidine-DNA Glycosylase Fpg

Russian Journal of Bioorganic Chemistry - DNA-substrates containing fluorescent DNA base analogs are widely used to study protein–nucleic acid interactions. In the case of DNA-recognizing...     

Interspecific chromosomal rearrangements in monosomic addition lines of Allium.

Monosomic alien addition lines (MAALs) are useful for assigning linkage groups to chromosomes. We examined whether the chromosomal rearrangements following the introduction of a single onion (Allium cepa) chromosome into the Allium fistulosum genome were produced by homeologous crossing over or by a nonreciprocal conversion event. Among the monosomic lines available, 17 were studied by fluorescent genomic in situ hybridisation, using total A. cepa genomic DNA as the probe and total A. fistulosum genomic DNA as the competitor. In this way, rearrangements such as chromosomal translocations between A. cepa and A. fistulosum were identified as terminal regions consisting of tandem DNA repeats. Homeologous crossing over between the two closely related genomes occurred in 4 of the 17 lines, suggesting that such events are not rare. On the basis of a detailed molecular cytogenetic characterisation, we identified true monosomic alien addition lines for A. cepa chromosomes 3, 4, 5, 7, and 8 that can reliably be used in genetic studies.     

Colour-scent associations in a tropical orchid: three colours but two odours

Colour and scent are the major pollinator attractants to flowers, and their production may be linked by shared biosynthetic pathways. Species with polymorphic floral traits are particularly relevant to study the joint evolution of floral traits. We used in this study the tropical orchid Calanthe sylvatica from Réunion Island. Three distinct colour varieties are observed, presenting lilac, white or purple flowers, and named respectively C. sylvaticavar.lilacina (hereafter referred as var. lilacina), C. sylvaticavar. alba (var. alba) and C. sylvatica var. purpurea (var. purpurea). We investigated the composition of the floral scent produced by these colour varieties using the non-invasive SPME technique in the wild. Scent emissions are dominated by aromatic compounds. Nevertheless, the presence of the terpenoid (E)-4,8-dimethylnona-1,3,7-triène (DMNT) is diagnostic of var. purpurea, with the volatile organic compounds (VOC) produced by some individuals containing up to 60% of DMNT. We evidence specific colour-scent associations in C. sylvatica, with two distinct scent profiles in the three colour varieties: the lilacina-like profile containing no or very little DMNT (<2%) and the purpurea-like profile containing DMNT (>2%). Calanthe sylvatica var. alba individuals group with one or the other scent profile independently of their population of origin. We suggest that white-flowered individuals have evolved at least twice, once from var. lilacina and at least once from var. purpurea after the colonisation of la Réunion. White-flowered individuals may have been favoured by the particular pollinator fauna characterising the island. These flowering varieties of C. sylvatica, which display three colours but two scents profiles prove that colour is not always a good indicator of odour and that colour-scent associations may be complex, depending on pollination ecology of the populations concerned.     

Xylem exudation is related to nitrate assimilation pathway in detopped maize seedlings: use of nitrate reductase and glutamine synthetase inhibitors as tools

The xylem exudation of detopped 7-d-old seedlings of Zea maysL. doubled when KCI was present in the root medium comparedto seedlings maintained on water. It was further enhanced whenKCI was replaced by nitrogen compounds such as nitrate, ammoniumand glutamine. The role of the nitrate assimilation pathwayon the enhancement of xylem exudation rate was investigatedusing tungstate, an inhibitor of nitrate reductase (NR) activity,and phosphinothricin or methionine sulphoximine, inhibitorsof glutamine synthetase (GS) activity. The sap levels of NO₃^–,NH₄⁺, glutamine, and asparagine was used to ascertain the invivo inhibition of both enzymes. The tungstate effects werealso checked by measuring leaf in vitro NA activity and NR proteincontent. Xylem exudation rate of detopped seedlings fed withKNO₃ decreased when the nitrate assimilation pathway was blockedeither at the NR or at GS sites. This decrease was preventedwhen urea (acting as NH₄⁺ supply) was given simultaneously withtungstate. KNO₃ does not act directly on exudation, but throughthe involvement of NH₄⁺. The involvement of glutamine was alsoshown since GS inhibition resulted in a cancellation of theenhancing effect of KNO₃ on exudation. As change of exudationrate was not linked to change in sap osmolarity, it is assumedthat the assimilation chain could modify root water conductance.The role of glutamine was discussed. Key words: Exudation, maize, nitrate, conductance, NR, GS     

New Fluorescent Analogs of Nucleotides Based on 3-Hydroxychromone for Recording Conformational Changes of DNA

Russian Journal of Bioorganic Chemistry - It has recently been found that derivatives of nucleotides containing а 3-hydroxychromone fluorescent dye can be used as sensitive markers of...     

Synthesis and antibacterial activity of novel enolphosphate derivatives

A new class of enolphosphates derivatives, the 1-alkenyldiphosphates, was designed and a rapid and efficient synthesis for these compounds was developed. These new molecules showed interesting in vitro antibacterial activities (MIC) against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative pathogens including Pseudomonas aeruginosa and Escherichia coli.     

Utilisation des spectres polliniques recueillis sur Agrotis (Scotia) Ipsilon Hufnagel (Noctuidae) comme indicateur des migrations

Dans le but de préciser Ies désplacements migratoires de Agrotis ipsilon, des analyses polliniques ont été réalisées a partir de lavage de têtes entières (surface, trompes et antennes) de papillons mâles sur neuf échantillons correspondant à neuf piégeages effectués en Camargue (France) entre le 28.III et le 05.V.1989 et sur un piégeage d'individus mâles et femelles le 20.IX.1989 au Col du Glandon (2000 m, Savoie, France). Les traitements chimiques classiques de la palynologie ont été appliqués à des groupes de 10 têtes par piégeage donnant une image pollinique de la population.

Les résultats obtenus mettent en éevidence des quantités de pollens recueillies et une richesse taxonomique largement suffisantes pour l'établissement de spectres polliniques. Elles attestent la présence de pollens de plantes à pollinisation entomophile mais aussi anémophile (35%). Les taxons rencontrés appartiennent à la flore locale (Tamarix, Matthiola, type Genista, Brassicaceae, Gentianaceae, Rosaceae et Saxifragaceae) et lointaine (Citrus, Eucalyptus, Ostrya, Castanea, Betula, Alnus et Hedera). La reconnaissance dans les spectres polliniques des genres appartenant au citronnier, clémentinier, charme-houblon ou à l'eucalyptus suggère une migration sud-est/est a partir de la Corse ou de la région Alpes-Cote-d'Azur. Une migration sud (Afrique du Nord) est suspectée par la présence de pollens en dehors de leur période de pollinisation (Olea et Castanea). Dans l'état actuel de nos observations, il n'a pas encore été possible de mettre en évidence des taxons nord-africains. Les ressources nectarifères ont pu être précisées: Salix, Citrus, Eucalyptus, Ligustrum, Castanea et Brassicaceae.

Pollen analysis were carried out on moths [Agrotis (Scotia) ipsilon] collected on two sites in south-east France, one near the Mediterranean sea (Camargue), the other in the Alps, at 2000 m altitude. A spring migration from east and south-east (Corsica and the French Riviera) was found at the Camargue site, while a possible fall migration from the North (Lyon area) appeared in the Alps. In addition, the analyses indicate that moths visit certain nectariferous floral sources.     

First general methods toward aldehyde enolphosphates

We herein report two innovative methods toward aldehyde enolphosphates and the first saccharidic aldehyde enolphosphates. Aldehyde enolphosphate function is worthwhile to be considered as a good phosphoenolpyruvate analogue.     

Responses of Fraxinus excelsior seedlings to grass-induced above- and below-ground competition

The competitive interactions between woody seedlings and herbaceous vegetation have received increasing interest in recent years. However, little is known about the relative contributions and underlying mechanisms of above- and below-ground competition between species. We used a novel experimental approach to assess the responses of Fraxinus excelsior seedlings to different combinations of root and shoot competition imposed by the grass Dactylis glomerata under greenhouse conditions. Seedling growth was significantly reduced by competition for soil resources, but neither biomass nor height were significantly affected by shoot competition for light. Competitive response indices based on biomass confirmed that below-ground competition was more important than above-ground competition, and indicated that root and shoot competition did not interact to influence plant growth. Fraxinus biomass allocation and seedling traits were almost all significantly affected by root competition; these responses varied depending on the trait examined. In contrast, morphological responses to shoot competition were limited. In the absence of root competition, seedlings showed a significant increase in the biomass allocated to leaves and a greater leaf area ratio in response to shoot competition. Our findings suggest that morphological modifications help to mitigate the negative effects of competition, but the expression of plasticity may be suboptimal due to resource constraints. The present study also highlights the importance of appropriate experimental controls and analysis to avoid confounding effects of experimental design and ontogeny on the interpretation of competitive responses.     

Fatal Pulmonary Mucormycosis due to <Emphasis Type="Italic">Rhizopus homothallicus</Emphasis>

We report here a case of cavitary pneumonia due to Rhizopus homothallicus in a diabetic patient. This is the first proven case of R. homothallicus infection in Western countries and the third case described worldwide. The organism was isolated from lung biopsy and identified after amplification and sequencing of the internal transcribed spacer region.