The role of floral biology and breeding system on the reproductive success of the narrow endemic Petrocoptis viscosa rothm. (Caryophyllaceae)

Morphological and functional characteristics of flowers may have major effects on their reproductive success. Here, we report a study on the characteristics of flowers of Petrocoptis viscosa, a herb species endemic to the northwest Iberian Peninsula, restricted to crevices in limestone outcrops, and currently occurring in only three populations within an area of less than 30 km². We also investigated the effects of pollen source on indicators of reproductive success. The results show that Petrocoptis viscosa flowers are well adapted to autogamy. Inbreeding depression (as determined by comparison of results obtained after selfing and outcrossing) was negligible for fruit production (δ=−0.05) and mean seed number (δ=−0.11), low for seed germination percentage (δ=0.08), but relatively high for mean seed weight (δ=0.23). The spatial structure and small size of population of Petrocoptis viscosa may mean that inbreeding is frequent in natural habitats. Adaptation of plants to autogamy may therefore be energetically beneficial (i.e. less wasted expenditure on rewards and flowers).     

New method of DNA isolation from two food additives suitable for authentication in polymerase chain reaction assays

Locust bean gum and guar gum are galactomannans used as additives (E 410 and E 412, respectively) in the food industry as stabilizing agents. Analytical discrimination between the two additives in gums and foods is now feasible by molecular techniques. However, only complex and time-consuming DNA isolation protocols are available to date. We have developed simple improved protocols to obtain enough DNA suitable for PCR amplification from a few milligrams of commercial E 410 and E 412 additives (containing more than 75% polysaccharides). The suspension of additives in water or 10 mM Tris-HCl, pH 8.5, efficiently recovers DNA suitable for authentication in PCR assays. However, the Tris method was much more efficient for the extraction of DNA from E 410 than for E 412 additives. Conversely, the water method was the most suitable for detecting DNA extracted from E 412 or from E 410/E 412 mixtures. Combined with the use of the two specific ribosomal primer pairs previously designed, our methods are well-suited for a fast and simple high-throughput sample treatment of commercial gums for molecular certification.     

Selenium content and distribution in cow's milk supplemented with two dietary selenium sources

The effect of two sources of Se, selenized yeast (Se-Y) and sodium selenite, added to total mixed rations (TMR) fed to cows on Se milk content and distribution in milk components was studied on three farms for 6 weeks. The maximal increase in milk Se was attained with Se-Y supplemented at 0.3 microg g(-1). The effect was immediate, with an increase of 9 microg L(-1) being observed after only 5 days, and remained steady until the last sample at day 40 of Se supplementation. Se distribution in milk components was constant, 53.6, 42.6, and 9.3% in whey, casein, and fat, respectively, and was unaffected by the form of supplementation. The effect of the level of Se-Y supplementation on milk Se was studied on two farms. Increasing dietary Se-Y from 0 to 0.5 microg g(-1) elevated milk Se content from 20 to 39 microg L(-1). Se-enriched cow's milk at different levels can be produced by varying dietary Se supplementation in the form of selenized yeast.     

Application of a DNA analysis method for the cultivar identification of grape musts and experimental and commercial wines of Vitis vinifera L. using microsatellite markers

A DNA-based method has been applied to the identification of several musts and wines using microsatellite markers. DNA was extracted from the solid phases of sixteen monovarietal and five multivarietal musts (mixtures of two musts down to a 4:1 proportion) and they were genotyped at seven microsatellites through a multiplex PCR reaction and automated fluorescent detection. PCR multiplexing was successful in monovarietal musts, but should be used with caution with at least some markers and in multivarietal musts. The same extraction and detection methods were unsuccessfully applied to the solid and liquid phases of five monovarietal commercial wines, even after using different concentration procedures. Nucleic acids presence was then studied in a recent must, during the fermentation process, and during the subsequent steps of winemaking. Genotyping was possible in the resulting experimental wine until decanting, when the particles in suspension were removed. These results suggest that wine authentication through DNA analysis is not possible in commercial wines, in the tested conditions.     

Performance of new and commercial xylanases for ECF and TCF bleaching of eucalyptus kraft pulp

Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences. The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10% after the D stage. The two commercial xylanases behaved in a different way, being one of them (X_C) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage (15%). All xylanases produced morphological changes in the fibre surfaces, but only with X_C cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained with the XD sequence and therefore, a complete bleaching sequence XDEopD₁ (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme.     

Use of stump diameter to estimate diameter at breast height and tree volume for major pine species in El Salto, Durango (Mexico)

Foresters may require to estimate the diameter at breast height(d.b.h.) and the volume of trees that have been cut, and mayonly have available the stumps as an indicator of the size ofthe trees. In the present study, equations for predicting bothd.b.h. and volume from stump diameter inside bark were developedfor major pine species in the forest region of El Salto, Durango(Mexico). The d.b.h. was estimated with relatively high accuracywith a simple linear model. The tree volume was also estimatedwith high precision by use of an allometric equation. Weightedlinear and non-linear least squares methods were used to takeinto account the problem of heteroscedasticity observed in thevolume–stump diameter relationships. The results of thenon-linear extra sum of squares method and of the F tests indicatedthat species-based equations for estimating both d.b.h. andvolume from stump diameter are required.     

Determination of deforestation rates of the world's humid tropical forests

A recently completed research program (TREES) employing the global imaging capabilities of Earth-observing satellites provides updated information on the status of the world's humid tropical forest cover. Between 1990 and 1997, 5.8 +/- 1.4 million hectares of humid tropical forest were lost each year, with a further 2.3 +/- 0.7 million hectares of forest visibly degraded. These figures indicate that the global net rate of change in forest cover for the humid tropics is 23% lower than the generally accepted rate. This result affects the calculation of carbon fluxes in the global budget and means that the terrestrial sink is smaller than previously inferred.     

Genome sequence of Aedes aegypti, a major arbovirus vector

We present a draft sequence of the genome of Aedes aegypti, the primary vector for yellow fever and dengue fever, which at approximately 1376 million base pairs is about 5 times the size of the genome of the malaria vector Anopheles gambiae. Nearly 50% of the Ae. aegypti genome consists of transposable elements. These contribute to a factor of approximately 4 to 6 increase in average gene length and in sizes of intergenic regions relative to An. gambiae and Drosophila melanogaster. Nonetheless, chromosomal synteny is generally maintained among all three insects, although conservation of orthologous gene order is higher (by a factor of approximately 2) between the mosquito species than between either of them and the fruit fly. An increase in genes encoding odorant binding, cytochrome P450, and cuticle domains relative to An. gambiae suggests that members of these protein families underpin some of the biological differences between the two mosquito species.