Asymmetric tethering of flat and curved lipid membranes by a golgin

Golgins, long stringlike proteins, tether cisternae and transport vesicles at the Golgi apparatus. We examined the attachment of golgin GMAP-210 to lipid membranes. GMAP-210 connected highly curved liposomes to flatter ones. This asymmetric tethering relied on motifs that sensed membrane curvature both in the N terminus of GMAP-210 and in ArfGAP1, which controlled the interaction of the C terminus of GMAP-210 with the small guanine nucleotide-binding protein Arf1. Because membrane curvature constantly changes during vesicular trafficking, this mode of tethering suggests a way to maintain the Golgi architecture without compromising membrane flow.     

Variations of Fatty Acids During the Sulphidization Process in the Authie Bay Sediments (8 pp)

Background, Aim and Scope   The sulphidization process in relatively clean sediments sampled in a mudflat of the Authie estuary (located in Northern France) has been studied by coupling geochemical expertise and the use of fatty acids (FAs) as biochemical markers. Materials and Methods: Three sediment cores have been sampled in September 2003, November 2003 and May 2004, and cut every 2 cm in the field under nitrogen atmosphere so as to prevent any oxidation of reduced species. In the solid phase, reduced sulphur compounds, e.g. AVS (Acid Volatile Sulphides) and CRS (Chromium Reducible Sulphur) [including also the calculation of the degree of sulphidization (DOS) and the degree of pyritization (DOP)], and fatty acids have been carried out. Eh, pH, metal species (mostly iron and manganese), dissolved S(-II) and sulphate have also been determined in the porewaters. Results: The sediment cores display a lot of differences due to the high sedimentation rate and the seasonal evolution as well. The presence of Mn2+, Fe2+, S(-II) and the decrease of the redox potential and the concentration of sulphates clearly indicate early diagenetic transformations promoted by the bacterial activity. Acid Volatile Sulphides are produced in the first cm and are stabilized with depth. A rapid decrease of FAs concentrations in September and May has also been pointed out owing to a rapid consumption of the labile organic matter. Several categories of FAs have been separated and most of them belong here to the saturated and monounsaturated groups. In the saturated group, branched chain FAs, iso and anteiso C15:0 are predominant and represent the bacterial imprint in the sediments. Maximum proportions are observed between 5 and 10 cm in September, and between 13 and 17 cm in November and May. Discussion: As sulphate concentrations remain high in the porewater, the limitation of the sulphidization process in our sediments must be due to a lack of labile organic matter input. The presence of pyrite in our sediment is bound to its formation at the water-sediment interface, where partial reoxidation may take place. However, at deeper depths, pyritization processes does not continue any more. Presence of maximum, dissolved S(-II) concentrations have been observed, simultaneously with maximum proportion relative to total FAs of iso and anteiso C15:0, and, in September, with an increase in proportions of C18:1ω7. This indicates the presence of sulphate-reducing bacterial activity at the time when the sediments were sampled. However, no close correspondence between bacterial FAs concentrations and S(-II) concentrations has been found. Conclusions: In each core, the sulphidization process is not complete, and this is probably due to the lack of biodegradable organic matter, which appears as the limiting factor from a qualitative point of view. S(-II) production in porewaters is linked with the activity of sulphate-reducing bacteria. Seasonal effects have also been pointed out and, especially, a more important input of diatom organic matter in May when compared to September and November. Recommendations and Perspectives: Fatty acid analyses represent an original and a useful tool for a better understanding of an early diagenetic process in the first cm of the sediments. More studies should be carried out associating inorganic chemical parameters and chemical biomarkers for pointing out stronger and more reproducible relations. Moreover, the use of microcosms in our group is on the way to take into account the kinetics of the organic matter degradation during the early diagenesis.     

Inhibition of apple polyphenol oxidase activity by procyanidins and polyphenol oxidation products

The rate of consumption of dissolved oxygen by apple polyphenol oxidase in cider apple juices did not correlate with polyphenol oxidase activity in the fruits and decreased faster than could be explained by the decrease of its polyphenolic substrates. The kinetics parameters of a crude polyphenol oxidase extract, prepared from apple (Braeburn cultivar), were determined using caffeoylquinic acid as a substrate. Three apple procyanidin fractions of n 80, 10.5, and 4 were purified from the parenchyma of cider apples of various cultivars. Procyanidins, caffeoylquinic acid, (-)-epicatechin, and a mixture of caffeoylquinic acid and (-)-epicatechin were oxidized by reaction with caffeoylquinic acid o-quinone in order to form oxidation products. All the fractions were evaluated for their inhibitory effect on PPO activity. Native procyanidins inhibited polyphenol oxidase activity, the inhibition intensity increasing with n. The polyphenol oxidase activity decreased by 50% for 0.026 g/L of the fraction of n 80, 0.17 g/L of the fraction of n 10.5, and 1 g/L of the fraction of n 4. The inhibitory effect of oxidized procyanidins was twice that of native procyanidins. Oxidation products of caffeoylquinic acid and (-)-epicatechin also inhibited polyphenol oxidase.     

Insectivorous songbirds as early indicators of future defoliation by spruce budworm

Landscape Ecology - Although the spatiotemporal dynamics of spruce budworm outbreaks have been intensively studied, forecasting outbreaks remains challenging. During outbreaks, budworm-linked...     

Assessing the fertility of two mares cloned from the same founder animal

Two cloned mares, produced from the same sample of skin fibroblasts, were bred during four breeding seasons from their second year of age, as embryo donors, in exactly the same conditions, using the same stallions for both cloned mares. The aim of this study was to test the embryo donor potential of cloned mares and to compare the results obtained from two cloned mares of the same mare with other embryo donor mares (n = 31–39 per breeding season) at the same stud. For both cloned mares, 19 embryos were recovered by 43 collection attempts (44%) (7/22 for one; 12/21 for the other), 16 (84%) pregnancies (5/7 for one, 11/12 for the other) were obtained at day 14 post-ovulation (D₁₄), and 12 (3/7 for one; 9/12 for the other) foals were born. One cloned mare was a less efficient donor mare than the other (p < .05), In control donor mares, 623 embryo collections were performed, with a recovery rate (80%—496/623) significantly higher than for cloned mares. The recovery rate in the subpopulation of 2–5-year-old control donor mares (same age of cloned mares) (89%—127/143) and The recovery rate in the subpopulation of 12 control mares bred with the seven same stallions as clones (55%—17/31), were both higher than for cloned mare (p < .05). The success rate of transfer was not different between embryos produced by cloned mares (84%—16/19) and those produced by control donor mares (79%—392/496). However, the foaling rate per embryo collection was significantly lower for cloned mares (28%—12/43) than for control donor mares (52% - 325/623) (p < .05).     

Detection of Coxiella burnetii, the agent of Q fever, in oviducts and uterine flushing media and in genital tract tissues of the non pregnant goat

The aim of the present study was the detection and quantification of Coxiella burnetii DNA in the flushing media (oviducts and uterine horns) and genital tract tissues of non pregnant goats from 20 goats chosen at random from 86 goats originating from 56 different breeding herds in south-west France. The serological prevalence rate of C. burnetii in the study population was 70.3%.The DNA of C. burnetii was identified using conventional PCR in the flushing media from the oviducts and uterus in 8/20 goats (40%) and in genital tract tissues (oviduct, uterus and ovary) in 5/20 goats (25%). This study clearly shows for the first time that the media used to flush the oviducts or uterine horns, collected using the standard embryo harvesting technique in goats, are susceptible to infection with C. burnetii. The 16 conventional PCR-positive samples were also analyzed using real-time PCR. The bacterial load of the oviduct and uterine flushing media varied from 2.9 × 10⁴ to 7.5 × 10⁶ bacteria per flushing medium, while the bacterial load of the tissue samples varied from 1.0 × 10² to 1.5 × 10⁵ bacteria per mg of tissue. The infection of genital tract flushing media and tissues is a risk factor for the transmission of C. burnetii from donor to recipient during embryo transfer or to the embryo and fetus when gestation is pursued to term.     

Modeling invasive species spread in complex landscapes: the case of potato moth in Ecuador

Tropical mountains have a long history of human occupation, and although vulnerable to biological invasions, have received minimal attention in the literature. Understanding invasive pest dynamics in socio-ecological, agricultural landscapes, like the tropical Andes, is a challenging but timely issue for ecologists as it may provide developing countries with new tools to face increasing threats posed by these organisms. In this work, road rehabilitation into a remote valley of the Ecuadorian Andes constituted a natural experiment to study the spatial propagation of an invasive potato tuber moth into a previously non-infested agricultural landscape. We used a cellular automaton to model moth spatio-temporal dynamics. Integrating real-world variables in the model allowed us to examine the relative influence of environmental versus social landscape heterogeneity on moth propagation. We focused on two types of anthropogenic activities: (1) the presence and spatial distribution of traditional crop storage structures that modify local microclimate, and (2) long-distance dispersal (LDD) of moths by human-induced transportation. Data from participatory monitoring of pest invasion into the valley and from a larger-scale field survey on the Ecuadorian Andes allowed us to validate our model against actual presence/absence records. Our simulations revealed that high density and a clumped distribution of storage structures had a positive effect on moth invasion by modifying the temperature of the landscape, and that passive, LDD enhanced moth invasion. Model validation showed that including human influence produced more precise and realistic simulations. We provide a powerful and widely applicable methodological framework that stresses the crucial importance of integrating the social landscape to develop accurate invasion models of pest dynamics in complex, agricultural systems.     

Use of high spatial resolution satellite imagery to characterize landscapes at risk for bluetongue

The recent and rapid spread in the Mediterranean Basin of bluetongue, a viral disease of ruminants transmitted by some species of Culicoides (biting midges), highlights the necessity of determining the conditions of its emergence. This study uses high spatial resolution satellite imagery and methods from landscape ecology science to identify environmental parameters related to bluetongue occurrence in Corsica, a French Mediterranean island where the disease occurred for the first time in 2000. A set of environmental variables recorded in the neighborhood of 80 sheep farms were related to case occurrence through a logistic regression model computed within three subsequent buffer distances of 0.5, 1 and 2 km. The results reveal the role of landscape metrics, particularly those characterizing land-use units such as prairies and woodlands, as well as farm type, latitude and sunshine to explain the presence of bluetongue. Internal and external validation both indicate that the best results are obtained with the 1 km buffer size model (area under Receiver Operating Characteristic curve = 0.9 for internal validation and 0.81 for external validation). The results show that high spatial resolution remote sensing (i.e. 10 m pixels) and landscape ecology approaches contribute to improving the understanding of bluetongue epidemiology.     

Soil fauna abundance and diversity in a secondary semi-evergreen forest in Guadeloupe (Lesser Antilles): influence of soil type and dominant tree species

The importance of secondary tropical forests regarding the maintenance of soil fauna abundance and diversity is poorly known. The aims of this study were (1) to describe soil fauna abundance and diversity and (2) to assess the determinants of soil fauna abundance and diversity in two stands of a tropical semi-evergreen secondary forest. Soil macrofauna and microarthropod abundance and soil macrofauna diversity were described at two sites developed on different soils and with different site histories: (1) a natural secondary stand (natural forest) under two dominant tree species, Pisonia subcordata and Bursera simaruba, and (2) a planted secondary forest (planted forest) under three tree species, B. simaruba, Swietenia macrophylla, and Tabebuia heterophylla. The effects of both soil and main tree species’ litter quality were assessed to explain soil fauna abundance and diversity. The abundance of soil macrofauna was significantly higher in the soil under the planted forest, and soil fauna communities were contrasted between the two sites. In the planted forest, a soil-dwelling macrofauna community developed (mainly consisting of the anecic earthworm Polypheretima elongata). In the natural forest, soil macrofauna and microarthropod communities were located at the soil surface. The effect of plant litter quality varied according to each dominant tree species and was superimposed to soil effect. The lowest macrofauna abundance was associated with B. simaruba in the natural forest. T. heterophylla supported a much greater macrofauna community than the two other tree species studied at the same soil, and it appears likely that this is due to the palatability of its leaves compared with the other trees (low lignin, tannins, soluble phenols).     

Influence of the spatial organization of the perimysium on beef tenderness

The spatial distribution of the intramuscular connective tissue (IMCT) in four types of beef muscle (Biceps femoris, Infraspinatus, Longissimus thoracis, and Pectoralis profundus) was examined using histology and magnetic resonance imaging (MRI). The surface and the length of the IMCT and the surface of the myofiber bundles were evaluated by image analysis. The texture of the cooked meat from these muscles was measured both instrumentally by a compression test and by sensory analysis. The relationship between muscle structure and meat texture was studied by general discriminant analysis. The models obtained could assign correctly up to 87% of the samples to two tenderness classes. Histology and MRI provided complementary information about the microscopic and macroscopic IMCT structures, respectively. Both were necessary to predict sensory tenderness whereas only the MRI measurements were necessary to predict instrumental toughness. Tough muscles had smaller MRI myofiber bundles (0.7-1 mm radius) than tender muscles.