Evolution and history of grapevine (Vitis vinifera) under domestication: new morphometric perspectives to understand seed domestication syndrome and reveal origins of ancient European cultivars

Background and Aims

In spite of the abundance of archaeological, bio-archaeological, historical and genetic data, the origins, historical biogeography, identity of ancient grapevine cultivars and mechanisms of domestication are still largely unknown. Here, analysis of variation in seed morphology aims to provide accurate criteria for the discrimination between wild grapes and modern cultivars and to understand changes in functional traits in relation to the domestication process. This approach is also used to quantify the phenotypic diversity in the wild and cultivated compartments and to provide a starting point for comparing well-preserved archaeological material, in order to elucidate the history of grapevine varieties.

Methods

Geometrical analysis (elliptic Fourier transform method) was applied to grapevine seed outlines from modern wild individuals, cultivars and well-preserved archaeological material from southern France, dating back to the first to second centuries.

Key Results and Conclusions

Significant relationships between seed shape and taxonomic status, geographical origin (country or region) of accessions and parentage of varieties are highlighted, as previously noted based on genetic approaches. The combination of the analysis of modern reference material and well-preserved archaeological seeds provides original data about the history of ancient cultivated forms, some of them morphologically close to the current ‘Clairette’ and ‘Mondeuse blanche’ cultivars. Archaeobiological records seem to confirm the complexity of human contact, exchanges and migrations which spread grapevine cultivation in Europe and in Mediterranean areas, and argue in favour of the existence of local domestication in the Languedoc (southern France) region during Antiquity.     

Multiunit activity of the inferior olive during a conditioned motor sequence]

Multinuit activity from the inferior olive was recorded in chronic cats during a learned motor task. The animals were trained to perform a succession of rapid flexion-extension arm movements alternating with two maintained postures. No significant differences were observed in the olivary activity during maintained postures. However an increase of activity occurred before the beginning of the flexion detected on the biceps EMG recordings. The first modifications of olivary activity occurred in synchrony with postural reorganization preceding the flexion. This latter involved primarily the triceps. The increase of activity took place during the execution of movement and ended after the reaching of the target.     

Yersinia enterocolitica type III secretion-translocation system: channel formation by secreted Yops

'Type III secretion' allows extracellular adherent bacteria to inject bacterial effector proteins into the cytosol of their animal or plant host cells. In the archetypal Yersinia system the secreted proteins are called Yops. Some of them are intracellular effectors, while YopB and YopD have been shown by genetic analyses to be dedicated to the translocation of these effectors. Here, the secretion of Yops by Y.enterocolitica was induced in the presence of liposomes, and some Yops, including YopB and YopD, were found to be inserted into liposomes. The proteoliposomes were fused to a planar lipid membrane to characterize the putative pore-forming properties of the lipid-bound Yops. Electrophysiological experiments revealed the presence of channels with a 105 pS conductance and no ionic selectivity. Channels with those properties were generated by mutants devoid of the effectors and by lcrG mutants, as well as by wild-type bacteria. In contrast, mutants devoid of YopB did not generate channels and mutants devoid of YopD led to current fluctuations that were different from those observed with wild-type bacteria. The observed channel could be responsible for the translocation of Yop effectors.     

Monocyte Adhesion to Activated Aortic Endothelium: Role of L-Selectin and Heparan Sulfate Proteoglycans

This study examines the role of L-selectin in monocyte adhesion to arterial endothelium, a key pathogenic event of atherosclerosis. Using a nonstatic (rotation) adhesion assay, we observed that monocyte binding to bovine aortic endothelium at 4°C increased four to nine times upon endothelium activation with tumor necrosis factor (TNF)-α. mAb-blocking experiments demonstrated that L-selectin mediates a major part (64 ± 18%) of monocyte attachment. Videomicroscopy experiments performed under flow indicated that monocytes abruptly halted on 8-h TNF-α–activated aortic endothelium, ~80% of monocyte attachment being mediated by L-selectin. Flow cytometric studies with a L-selectin/IgM heavy chain chimeric protein showed calcium-dependent L-selectin binding to cytokine-activated and, unexpectedly, unactivated aortic cells. Soluble L-selectin binding was completely inhibited by anti–L-selectin mAb or by aortic cell exposure to trypsin. Experiments with cycloheximide, chlorate, or neuraminidase showed that protein synthesis and sulfate groups, but not sialic acid residues, were essential for L-selectin counterreceptor function. Moreover, heparin lyases partially inhibited soluble L-selectin binding to cytokine-activated aortic cells, whereas a stronger inhibition was seen with unstimulated endothelial cells, suggesting that cytokine activation could induce the expression of additional ligand(s) for L-selectin, distinct from heparan sulfate proteoglycans. Under flow, endothelial cell treatment with heparinase inhibited by ~80% monocyte attachment to TNF-α–activated aortic endothelium, indicating a major role for heparan sulfate proteoglycans in monocyte–endothelial interactions. Thus, L-selectin mediates monocyte attachment to activated aortic endothelium, and heparan sulfate proteoglycans serve as arterial ligands for monocyte L-selectin.     

Techniques de détection du VIH dans les milieux biologiques: Application à la recherche du virus dans le sperme

Growing numbers of HIV seronegative women want to have children with HIV infected partners by artificial insemination. The most sensitive assays for showing the presence of the virus are the coculture method and the DNA-PCR that are able to detect proviral load. HIV is detected from non spermatozoal mononuclear cells, seminal fluid but it was not found in spermatozoa fraction. But we know, by in vitro studies, that HIV can bound to and enter spermatozoa. Thus artificial insemination between HIV seropositive man and seronegative woman lead to a risk of contamination even with purified spermatozoa. Today, any virological assay is able to affirm that specimen is not infectious.     

Photosynthetic light-harvesting function of carotenoids in higher-plant leaves exposed to high light irradiances

Exposure of barley (Hordeum vulgare L.) leaves to strong white light (1500 μmol photons · m⁻² · s⁻¹) decreased the quantum yield of photosynthetic oxygen evolution in green light preferentially absorbed by carotenoids (Φ-510) but not in red light exclusively absorbed by chlorophylls (Φ-650). This phenomenon was observed to be (i) rapidly induced (within a few minutes), (ii) slowly reversible in darkness (within about 1 h), (iii) insensitive to dithiothreitol and (iv) maximally induced by photon flux densities higher than about 1000 μmol · m⁻² · s⁻¹. Determination of the carotenoid composition of the major light-harvesting complex of PSII (LHCII) and analysis of the thylakoid membrane lipid fluidity before and after strong illumination of barley leaves in the presence or the absence of dithiothreitol showed that the light-induced decrease in the Φ-510/Φ-650 ratio did not require the physical detachment of carotenoids from the pigment antennae. Compared to barley plants grown under moderate light and temperature conditions, plants grown in sustained high irradiance at elevated temperature exhibited (i) a lower Φ-510/Φ-650 ratio, (ii) a reduced size of the functional PSII pigment antenna in green light (but not in red light) and (iii) a marked increase in the amount of free carotenoids found in non-denaturing Deriphat-containing electrophoretic gels of thylakoid membranes. Similarly, the Φ-510/Φ-650 ratio of the LHCII-deficient chlorina-f2 barley mutant was very low compared to the wild type. Separation and quantification of the cis/trans carotenoid isomers of barley leaves revealed that strong illumination did not induce pronounced cis-trans isomerization of xanthophylls. Taken together, the data suggest that the efficiency of energy transfer from carotenoids to chlorophylls varies with the light environment both in the short term and in the long term, with excess light energy noticeably inhibiting the photosynthetic light-harvesting function of carotenoids. The photoprotective significance of this carotenoid decoupling from the chlorophyll antennae is discussed. Received: 28 July 1997 / Accepted: 25 October 1997     

Characterization of 25 new microsatellite markers for the fin whale (Balaenoptera physalus) and cross-species amplification in other cetaceans

Molecular Biology Reports - Cetaceans are large mammals widely distributed on Earth. The fin whale, Balaenoptera physalus, is the second largest living animal. In the 20th century, commercial...     

Alterations in the Quinolone Resistance-Determining Regions and Fluoroquinolone Resistance in Clinical Isolates and Laboratory-Derived Mutants of Mycoplasma bovis: Not All Genotypes May Be Equal

Mycoplasma bovis is considered a major contributor to respiratory diseases in young cattle. Resistant M. bovis isolates have increasingly been reported worldwide due to extensive use of antimicrobials to treat bovine pneumonia. The frequency of isolates resistant to fluoroquinolones varies considerably from one country to another. The MICs of isolates collected in France have only increased from “very low” to “low.” The present study was conducted to investigate whether alterations in the quinolone resistance-determining regions (QRDRs) could account for this slight modification in susceptibility. No correlation between QRDR alterations and increased MICs was evidenced in clinical isolates. In addition, all clinical isolates were subtyped, and the tendencies of the different sequence types to develop resistance through mutations in QRDRs under selective pressure in vitro were examined. In vitro, 3 hot spots for mutations in QRDRs (position 83 in GyrA and positions 80 and 84 in ParC) were associated with a high level of resistance when cumulated. We showed that the point mutations in the QRDRs observed in vitro were different (in location and selection rapidity) between the different subtypes. Our in vitro observations were corroborated by the recent detection of a clinical isolate highly resistant to fluoroquinolones (MIC ≥ 16 μg/ml) and belonging to the subtype which easily accumulates QRDR alterations in vitro. The current increased prevalence of this subtype in clinical isolates highlights the urgent need to control fluoroquinolone usage in veterinary medicine.     

Tracking a genetic signal of extinction-recolonization events in a neotropical tree species: Vouacapoua americana Aublet in French Guiana

Drier periods from the late Pleistocene and early Holocene have been hypothesized to have caused the disappearance of various rainforest species over large geographical areas in South America and restricted the extant populations to mesic sites. Subsequent improvement in climatic conditions has been associated with recolonization. Changes in population size associated with these extinction-recolonization events should have affected genetic diversity within species. However, these historical hypotheses and their genetic consequences have rarely been tested in South America. Here, we examine the diversity of the chloroplast and nuclear genomes in a Neotropical rainforest tree species, Vouacapoua americana (Leguminosae, Caesalpinioideae) in French Guiana. The chloroplast diversity was analyzed using a polymerase chain reaction-restriction fragment length polymorphism method (six pairs of primers) in 29 populations distributed over most of French Guiana, and a subset of 17 populations was also analyzed at nine polymorphic microsatellite loci. To determine whether this species has experienced extinction-recolonization, we sampled populations in areas supposedly not or only slightly affected by climatic changes, where the populations would not have experienced frequent extinction, and in areas that appear to have been recently recolonized. In the putatively recolonized areas, we found patches of several thousands of hectares homogeneous for chloroplast variation that can be interpreted as the effect of recolonization processes from several geographical origins. In addition, we observed that, for both chloroplast and nuclear genomes, the populations in newly recolonized areas exhibited a significantly smaller allelic richness than others. Controlling for geographic distance, we also detected a significant correlation between chloroplast and nuclear population differentiation. This result indicates a cytonuclear disequilibrium that can be interpreted as a historical signal of a genetic divergence between fragmented populations. In conclusion, the spatial genetic structure of contemporary V. americana populations shows evidence that this species has experienced large extinction-recolonization events, which were possibly caused by past climatic change.     

Temperature-dependent adjustment of the thermal stability of photosystem II in vivo: possible involvement of xanthophyll-cycle pigments

Moderately elevated temperatures induce a rapid increase in the heat and light resistance of photosystem II (PSII) in higher-plant leaves. This phenomenon was studied in intact potato leaves exposed to 35 °C for 2 h, using chlorophyll fluorometry, kinetic and difference spectrophotometry and photoacoustics. The 35 °C treatment was observed to cause energetic uncoupling between carotenoids and chlorophylls: (i) the steady-state chlorophyll fluorescence emission excited by a blue light beam (490 nm) was noticeably reduced as compared to fluorescence elicited by orange light (590 nm) and (ii) the quantum yield for photosynthetic oxygen evolution in blue light (400–500 nm) was preferentially reduced relative to the quantum yield measured in red light (590–710 nm). Analysis of the chlorophyll-fluorescence and light-absorption characteristics of the heated leaves showed numerous analogies with the fluorescence and absorption changes associated with the light-induced xanthophyll cycle activity, indicating that the carotenoid species involved in the heat-induced pigment uncoupling could be the xanthophyll violaxanthin. More precisely, the 35 °C treatment was observed to accelerate and amplify the non-photochemical quenching of chlorophyll fluorescence (in both moderate red light and strong white light) and to cause an increase in leaf absorbance in the blue-green spectral region near 520 nm, as do strong light treatments which induce the massive conversion of violaxanthin to zeaxanthin. Interestingly, short exposure of potato leaves to strong light also provoked a significant increase in the stability of PSII to heat stress. It was also observed that photosynthetic electron transport was considerably more inhibited by chilling temperatures in 35 °C-treated leaves than in untreated leaves. Further, pre-exposure of potato leaves to 35 °C markedly increased the amplitude and the rate of light-induced changes in leaf absorbance at 505 nm (indicative of xanthophyll cycle activity), suggesting the possibility that moderately elevated temperature increased the accessibility of violaxanthin to the membrane-located de-epoxidase. This was supported by the quantitative analysis of the xanthophyll-cycle pigments before and after the 35 °C treatment, showing light-independent accumulation of zeaxanthin during mild heat stress. Based on these results, we propose that the rapid adjustment of the heat resistance of PSII may involve a modification of the interaction between violaxanthin and the light-harvesting complexes of PSII. As a consequence, the thermoresistance of PSII could be enhanced either directly through a conformational change of PSII or indirectly via a carotenoid-dependent modulation of membrane lipid fluidity.Abbreviations and Symbols Fo and Fm initial and maximal level of chlorophyll fluorescence, respectively - Fv = Fm — Fo variable chlorophyll fluorescence - LHC(II) light-harvesting chlorophylla/b-protein complexes (of PSII) - photoacoustically measured quantum yield of photosynthetic oxygen evolution (in relative values) - _P fluorimetrically measured quantum yield of PSII photochemistry in the light - PFD photon flux density - q_E pH dependent quenching of chlorophyll fluorescence We thank Dr. J-L Montillet (CEA-Cadarache) for the use of his HPLC apparatus and Professor Y. Lemoine (University of Lille, France) for technical advice on HPLC.