Genetic structure and genetic relatedness of a hatchery stock of Senegal sole (Solea senegalensis) inferred by microsatellites

Solea senegalensis is a fish species in an early stage of domestication. A commercial hatchery in southern Spain experienced a dramatic failure in spawning and embryo survival, after incorporation into the broodstock of fish reared in their hatchery. To assess the impact of management on the stock quality, a population genetics study was made of adult broodstock present at this hatchery in 2000. The broodstock was composed of a group of fish of wild origin and two more groups from F₁ progeny. A set of eight microsatellite loci was used to compare genetic variability among the three groups and to establish the relationships between pairs of individuals within each group.Individuals from F₁ origin showed a substantial reduction in genetic variability when compared to those from the wild. There was a greater than 50% decrease in the number of alleles per locus corrected by sample size and 16% and 26% reductions in H_e values in the two F₁ groups, respectively. The degree of genetic relationship between individuals, evaluated by the relatedness estimator, rxy, and by graphical approaches, revealed a high proportion, almost 75%, of full-sibs and half-sibs in both F₁ groups, which might account for the reduction in overall variability. The high proportion of siblings also suggests a reproductive pattern in this stock in which few individuals breed successfully. This mating behaviour, along with factors inherent to selection and management systems, might be responsible for the negative effects on the reproductive capacity of the stock.     

Biosynthetic Modularity Rules in the Bisintercalator Family of Antitumor Compounds

Diverse actinomycetes produce a family of structurally and biosynthetically related non-ribosomal peptide compounds which belong to the chromodepsipeptide family. These compounds act as bisintercalators into the DNA helix. They give rise to antitumor, antiparasitic, antibacterial and antiviral bioactivities. These compounds show a high degree of conserved modularity (chromophores, number and type of amino acids). This modularity and their high sequence similarities at the genetic level imply a common biosynthetic origin for these pathways. Here, we describe insights about rules governing this modular biosynthesis, taking advantage of the fact that nowadays five of these gene clusters have been made public (thiocoraline, triostin, SW-163 and echinomycin/quinomycin). This modularity has potential application for designing and producing novel genetic engineered derivatives, as well as for developing new chemical synthesis strategies. These would facilitate their clinical development.     

How well does a botanical garden collection of a rare palm capture the genetic variation in a wild population?

Conservation is increasingly central to the botanic garden mission. Living plant collections are important components of conservation. Critical evaluation of living conservation collections with population genetic analysis can directly inform ex situ conservation strategy. Here, we quantify the degree of genetic variation captured through a population-based collection protocol, and explore optimal sampling for ex situ conservation. An extensive living collection derived from one population of Leucothrinax morrisii (Arecaceae) provided a model system. We compared 58 specimens from the ex situ collection with 100 individuals from throughout the parent population via 6 ISSR loci. Random bootstrapped resamples of the data were made to model differently structured ex situ collections. Mean diversity (He) differed little between the collection (0.204) and the population (0.216), and genetic distance (D) was very close (0.036). Very few private alleles were found between the collection and the population. Allelic capture, as measured by percent of private alleles, was greater than 94%. Resampled collections of different sizes captured from 48% to 94% of alleles. Pairwise comparison of bootstrapped resamples suggests that increasing the representation of half-sibling groups does not significantly increase allele capture. Increase in allele capture with increasing sample size is greatest at low resample sizes, and showed diminishing returns as resample size increased. No appreciable increase in allele capture was gained through maintaining different half-sibling groups. These data inform sampling for ex situ conservation purposes, and recommend sample sizes of at least 15 individuals, with the upper limit based on resources.     

Effects of Waterlogging Followed by a Salinity Peak on Rapeseed (Brassica napus L.)

Due mainly to alterations in plant metabolism, lack of oxygen and excess salts are disturbances that affect crop yields. In different parts of the world crops are subjected t o those disttirbances, simultaneously or successively. Our objective was to determine the effects of a winter waterlogging followed by a spring salt peak on rapeseed yield, A pot experiment, combining waterlogging and salinization was carried out. The waterlogging duration was: 0 (control), 3, 7 and 14 days and the sahnity treatments were peaks of Electrical Conductivity of 5 and 8 dSm⁻¹ and the control. The yield started decreasingfrotn 3 days during waterlogging, mainly due to the lower number of seeds per plant. The salt peak from 5 dSm⁻¹ affected the yield only in plants which had suffered a waterlogging lower than 7 days, showing interaction between salinity and waterlogging, Only salinity reduced oil content. The saline peak affected the K, Ca and Na concentration in plant tissues, but the effect of salinity on rapeseed could be more related to soil water potential than specific ion toxicities or imbalance.     

Location-Specific and Across-Location Selections for Seed Yield in Populations of Common Bean, Phaseolus vulgaris L.

Two populations of common bean, Phaseolus vulgaris L., were used to make three independent location-specific selections at Palmira, Quilichao, and Popayán, Colombia. Also, three across-location selections were made by alternating generations between Palmira and Popayan, between Quilichao and Popayán, and among Palmira, Quilichao, and Popayán. The seven highest yielding lines selected from each environment and population along with 14 parents and two checks were evaluated for seed yield, seed weight, maturity, and reaction to an-thracnose, angular leaf spot, and common bacterial blight. Mean squares due to evaluation and selection environments, selected lines, and their interactions were significant for all traits. Mean yields of selected lines were higher than the mean of parents in both populations. Among location-specific selections, lines yielded higher at their respective selection site. Moreover, selections made at Popayán were higher yielding than those made at Quilichao or Palmira when tested across locations and years. Use of Popayán, a relatively wetter and cooler site, either alone or in combination with other locations resulted in higher yield, higher seed weight, and higher resistance to anthracnose. On the average, location-specific selections were lower yielding than the across-location selections. Among across-location selections, those selected between Palmira and Popayán were the highest yielding in both populations. Selections at Palmira and across all three locations resulted in greater stability.     

Embolism induced by winter drought may be critical for the survival of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. near its southern distribution limit

Introduction   

Scots pine populations in the SE “Sistema Ibérico” range suffered a severe defoliation in the S face of the crown in isolated trees of thinned stands. This process was detected at the end of the winter 2001–2002.     

Estimating balanced structure areas in multi-species forests on the Sierra Madre Occidental,Mexico

• Introduction   

This study presents a method for estimating the minimum area which exhibits a balanced diameter distribution, and the corresponding number of trees, for different tree species and forest types in the Santiago Papasquiaro region in the State of Durango, Mexico. The balanced structure area is defined as the minimum contiguous area that is required for sustainable management of a multi-sized selection forest. A multi-sized forest represents a balanced structure unit if the relationship between harvest and growth can be maintained, using a defined target diameter distribution and disregarding major natural disturbances. The study is based on 17,577 sample plots in uneven-aged forests, which are selectively harvested by local communities.     

Volatile components and key odorants of fennel (Foeniculum vulgare Mill.) and thyme (Thymus vulgaris L.) oil extracts obtained by simultaneous distillation-extraction and supercritical fluid extraction

Volatile oil extracts of fennel seeds (Foeniculum vulgare Mill.) and thyme leaves (Thymus vulgaris L.) were obtained by simultaneous distillation-extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). In general, fennel oil extracted by SDE and SFE showed similar compositions, with trans-anethole, estragole, and fenchone as the main components. In contrast, thymol and p-cymene, the most abundant compounds in thyme leaves, showed big differences, with generally higher amounts of monoterpenes obtained by SDE. However, in this case, the differences between the extracts were higher. Key odorants of fennel seeds determined by gas chromatography-olfactometry (GC-O) showed similar patterns when applying SDE and SFE. trans-Anethole (anise, licorice), estragole (anise, licorice, sweet), fenchone (mint, camphor, warm), and 1-octen-3-ol (mushroom) were the most intense odor compounds detected in fennel extracts. Thymol and carvacrol, with oregano, thyme, and spicy notes, were identified as key compounds contributing to the aroma of thyme leaves.     

Phospholipid interactions protect the milk allergen alpha-lactalbumin from proteolysis during in vitro digestion

Interactions with food components may alter the resistance of food proteins to digestion, a property thought to play an important role in determining allergenic properties. The kinetics of breakdown of the bovine milk allergen alpha-lactalbumin during in vitro gastrointestinal digestion was found to be altered by interactions with physiologically relevant levels of phosphatidylcholine (PC), a surfactant that is abundant both in milk and is actively secreted by the stomach. Breakdown during gastric digestion was slowed in the presence of PC and accompanied by small alterations in the profile of resulting peptides, with little effect being observed during subsequent duodenal digestion. alpha-Lactalbumin was found to unfold at gastric (acid) pH, giving a CD spectrum similar to that obtained for the partially folded state it is known to adopt at pH values below its isoelectric point. Fluorescence polarization studies performed at low pH indicated that this partially unfolded form of the protein was able to penetrate into the PC vesicles. These interactions are probably responsible for the slowing of gastric digestion by reducing the accessibility of the protein to pepsin. These findings show that interactions with other food components, such as lipids, may alter the rate of breakdown of food proteins in the gastrointestinal tract. It underlines the importance of the food matrix in affecting patterns of food allergen digestion and hence presentation to the immune system and that in vitro digestion systems used for assessing digestibility of allergens must take account of surfactants.     

Metallomics approach to trace element analysis in ustilago maydis using cellular fractionation, atomic absorption spectrometry, and size exclusion chromatography with ICP-MS detection

Huitlacoche is the ethnic name of the young fruiting bodies of Ustilago maydis, a common parasite of maize. In Mexico and other Latin American countries, this fungus has been traditionally appreciated as a local delicacy. In this work a metallomics approach was used with the determination of eight elements in huitlacoche by electrothermal atomic absorption spectrometry as one facet of this approach. The results obtained indicated relatively lower concentrations of commonly analyzed metals, as referred to the data reported for other mushroom types. This effect was ascribed to different accessibilities of elements, depending on fungus substrate (lower from plant than from soil). Subcellular fractionation was accomplished by centrifugation of cell homogenates suspended in Tris-HCl buffer. Recoveries of the fractionation procedure were in the range of 71-103%. For six elements (Cr, Cu, Fe, Mn, Ni, and Pb), the mean relative contributions in cytosol, cell walls, and mixed membrane fraction were 50.7, 48.2, and 1.1% respectively. To attain the molecular weight distribution of compounds containing target elements as an additional aspect of the metallomics approach, the fungus extract (1% sodium dodecyl sulfate in Tris-HCl, 30 mmol L(-)(1), pH 7.0) was analyzed by size exclusion chromatography with UV and ICP-MS detection. With spectrophotometric detection (280 nm), the elution of high molecular weight compounds was observed in the form of one peak (MW > 10 kDa), and several lower peaks appeared at higher retention times (MW < 10 kDa). On ICP-MS chromatograms, a coelution of (59)Co, (63)Cu, (57)Fe, (202)Hg, (60)Ni, and (80)Se with the first peak on the UV chromatogram was clearly observed, indicating that a fraction of each element incorporated with high molecular weight compounds (12.7, 19.8, 33.7, 100, 19.4, and 45.8%, respectively, based on the peak area measurements). From a comparison of (80)Se and (33)S chromatograms (for sulfur analysis, the extract was obtained in the absence of SDS), both elements coeluted with the first UV peak, but their lower molecular weight compounds were apparently different. These findings may contribute to a better understanding of the accumulation of elements in mushrooms.