Found 295 result(s)
Found 30 page(s)

Patterns of population structure and environmental associations to aridity across the range of loblolly pine (Pinus taeda L.;Pinaceae)

  • Eckert, A. J.
  • Van Heerwaarden, J.
  • Wegrzyn, J. L.
  • Nelson, C. D.
  • Ross-Ibarra, J.
  • González-Martínez, S. C.
  • Neale, D. B.
Natural populations of forest trees exhibit striking phenotypic adaptations to diverse environmental gradients, thereby making them appealing subjects for the study of genes underlying ecologically relevant phenotypes. Here, we use a genome-wide data set of single nucleotide polymorphisms genotyped across 3059 functional genes to study patterns of population structure and identify loci associated with aridity across the natural range of loblolly pine (Pinus taeda L.). Overall patterns of population structure, as inferred using principal components and Bayesian cluster analyses, were consistent with three genetic clusters likely resulting from expansions out of Pleistocene refugia located in Mexico and Florida. A novel application of association analysis, which removes the confounding effects of shared ancestry on correlations between genetic and environmental variation, identified five loci correlated with aridity. These loci were primarily involved with abiotic stress response to temperature and drought. A unique set of 24 loci was identified as FST outliers on the basis of the genetic clusters identified previously and after accounting for expansions out of Pleistocene refugia. These loci were involved with a diversity of physiological processes. Identification of nonoverlapping sets of loci highlights the fundamental differences implicit in the use of either method and suggests a pluralistic, yet complementary, approach to the identification of genes underlying ecologically relevant phenotypes. Copyright © 2010 by the Genetics Society of America.

Applying phylogenetic analysis to viral livestock diseases Moving beyond molecular typing

  • Olvera, A.
  • Busquets, N.
  • Cortey, M.
  • Deus, N. d, Ganges, L.
  • Núñez, J. I.
  • Peralta, B.
  • Toskano, J.
  • Dolz, R.
Changes in livestock production systems in recent years have altered the presentation of many diseases resulting in the need for more sophisticated control measures. At the same time, new molecular assays have been developed to support the diagnosis of animal viral disease. Nucleotide sequences generated by these diagnostic techniques can be used in phylogenetic analysis to infer phenotypes by sequence homology and to perform molecular epidemiology studies. In this review, some key elements of phylogenetic analysis are highlighted, such as the selection of the appropriate neutral phylogenetic marker, the proper phylogenetic method and different techniques to test the reliability of the resulting tree. Examples are given of current and future applications of phylogenetic reconstructions in viral livestock diseases. © 2009 Elsevier Ltd. All rights reserved.

The effect of bovine embryo culture without proteins supplements until day 4 on transcription level of hyaluronan synthases, receptors and mtDNA content

  • Palasz, A. T.
  • Beltrán Breña, P.
  • De la Fuente, J.
  • Gutiérrez-Adán, A.
The effect of bovine embryo culture on a flat surface, (without a surface-active compound) on the level of mRNA expression of hyaluronan (HA) synthases (Has1, Has2 and Has3), Ha receptors RHAMM and C44 receptors was evaluated by mitochondrial DNA concentration and in vitro development. Cultures were evaluated up to 96 h post-insemination (hpi) using SOFaa medium. Of the three Has isoforms, Has2 expression only increased in the bovine serum albumin (BSA)-only supplemented groups regardless of time of BSA addition. Expression of RHAMM receptors was highly dependent on the addition of HA, irrespective of the presence of BSA in the medium. In contrast, expression of the CD44 receptor gene was not affected by any treatment. The cleavage rates and number of embryos that developed to 8-cell stage by day 4 were not affected by lack of BSA in the medium, but increased numbers of blastocysts developed in medium supplemented with BSA from days 1 or 4 with or without HA than in medium that had HA only. Addition of both HA and BSA at day 4 increased mtDNA copy numbers at the blastocyst stage. Data suggest that the addition of BSA and/or HA at 96 hpi increased expression of RHAMM and Has2 genes, but not CD44, Has1 or Has3 genes. Higher expression levels of Has2 than Has1 and the three isoforms indicate that high- rather than low-molecular-weight HA should be used for preimplantation bovine embryo culture. Copyright © 2009 Cambridge University Press.

Seasonal changes in the physiological activity of regeneration under a natural light gradient in a Pinus pinea regular stand

  • Pardos, M.
  • Puértolas, J.
  • Madriga, G.
  • Garriga, E.
  • de Blas, S.
  • Calama, R.
Seasonal courses of chlorophyll a fluorescence, gas exchange parameters and water status, joined to environmental variables, were measured in four age classes of stone pine (Pinus pinea L.) natural regeneration, selected within a natural light gradient in order to cover the whole range of incident light detected within a stone pine regular stand throughout 2007 and 2008. Selection of light conditions was based a priori on the distance of seedlings to the parent trees, expressed by crown radius distances. One-year old seedlings were worse acclimated to the extreme drought conditions recorded in summer (especially in 2008), showing lower predawn and midday Fv/Fm values, slightly lower photosynthetic rates at midday, lower ΦPSII values, lower water potentials (Ψ pd and Ψ min), and high mortality (90%). The oldest seedlings (class 4, 51-200 cm high), although they do not experience the lowest Ψ min in July 2008, were not able to maintain a positive carbon gain at midday, even showing the lowest photosynthetic rates. However, they rapidly recovered once the climatic conditions were softened in early autumn. During late autumn low Fv/Fm values were found especially in one-year old seedlings, indicating that maximal photochemical efficiency of PSII is sensitive to the autumn temperatures below cero recorded during both years. Thus, stone pine regeneration acclimates its physiology to the seasonal course of temperature and water availability, and this acclimation depended on age class. However, seedling physiology is only slightly affected by differences in light environment, probably related to the low variability recorded in GSF values (0.55 ± 0.01), due to the low density of the stand. We suggest that such low stand densities cannot assure one-year old seedlings' survival, but are sufficient for older seedlings.

Contribution of the female reproductive tract to low fertility in postpartum lactating dairy cows

  • Rizos, D.
  • Carter, F.
  • Besenfelder, U.
  • Havlicek, V.
  • Lonergan, P.
Infertility in dairy cattle is a multifactorial problem that may be linked to follicle development and the quality of the ovulated oocyte, to sperm transport and fertilization, to the reproductive tract environment, or to a combination of these factors. Using a state-of-the-art endoscopic embryo transfer technique, the aim of this study was to compare the ability of the reproductive tract of postpartum dairy cows and nulliparous heifers to support the development of early embryos to the blastocyst stage. Bovine embryos of 2 to 4 cells (n=1,800) were produced by in vitro maturation and fertilization of oocytes derived from the ovaries of slaughtered cattle. The estrus cycles of nulliparous Holstein heifers (n=10) and postpartum Holstein cows (n=8, approximately 60 d postpartum) were synchronized using an 8-d controlled internal drug release device coupled with prostaglandin injection. On d 2, one hundred 2- to 4-cell embryos were endoscopically transferred to the oviduct ipsilateral to the corpus luteum. Five days later, on d 7, the oviduct and uterus were flushed nonsurgically to recover the embryos. The number of embryos developing to the blastocyst stage was recorded immediately at recovery and following overnight culture in vitro. A representative number of blastocysts from heifers and cows were stained to assess cell number. Progesterone concentrations were lower in cows than in heifers on d 5, 6, and 7 (d 7=2.39±0.33 vs. 5.34±0.77. ng/mL, respectively). More embryos were recovered from heifers than cows (79.0±7.0 vs. 57.2±11.4%). Of the embryos recovered, 33.9±3.6% had developed to the blastocyst stage in the heifer oviduct compared with 18.3±7.9% in the postpartum cow oviduct. There was no evidence of a difference in blastocyst quality as evidenced by total cell number in the blastocysts (71.2±5.7 vs. 67.0±5.3, respectively). In conclusion, the reproductive tract of the postpartum lactating dairy cow may be less capable of supporting early embryo development than that of the nonlactating heifer, and this may contribute to the lower conception rates observed in such animals. © 2010 American Dairy Science Association.

Experimental infection of young adult European breed sheep with Rift Valley fever virus field isolates

  • Busquets, N.
  • Xavier, F.
  • Martín-Folgar, R.
  • Lorenzo, G.
  • Galindo-Cardiel, I.
  • Pérez Del Val, B.
  • Rivas, R.
  • Iglesias, J.
  • Rodríguez, F.
  • Solanes, D.
  • Domingo, M.
  • Brun, A.
The increasing interest in Rift Valley fever virus (RVFV) and its potential impact on naive animal populations deserve revisiting experimental reproduction of RVFV infection, particularly in those animal breeds for which no data about their susceptibility to RVFV infection have ever been recorded. In this study we show the susceptibility of 9-10 weeks old European sheep (Ripollesa breed) to RVFV infection, showing a mild, subacute form of disease. Four different viral isolates efficiently replicated in vivo after subcutaneous experimental inoculation, and consistent viral loads in blood and virus shedding (variable in length depending on the RVFV isolate used) were detected, showing horizontal transmission to a noninfected, sentinel lamb. RVFV infection caused transient pyrexia in adult lambs and no other clinical symptoms were observed, with the exception of corneal opacity ("blue eye") found in 3 out of 16 subcutaneously inoculated sheep. In conclusion, adult sheep from this European breed are readily infected with RVFV without apparent clinical manifestations. Copyright 2010, Mary Ann Liebert, Inc.

Influence of hormonal and nonhormonal estrus synchronization methods on follicular and oocyte quality in primiparous lactating does at early postpartum period

  • Arias-Álvarez, M.
  • García-García, R. M.
  • Torres-Rovira, L.
  • González-Bulnes, A.
  • Rebollar, P. G.
  • Lorenzo, P. L.
High-yield lactating does need effective estrus synchronization methods to improve their reproductive outcome by enhancing ovarian function. The aim of the current work was to analyze ovarian follicular and oocyte characteristics of hormonal and nonhormonal estrus synchronization regimes in primiparous lactating rabbit does (Oryctolagus cuniculus) in the early postpartum period (Day 11). Females were randomly treated with either (1) a hormonal standard treatment with 25 IU equine chorionic gonadotropin (eCG) 48 h before artificial insemination (eCG group) or (2) an alternative nonhormonal treatment consisting of doe-litter separation 24 h before artificial insemination (Bio group). No significant differences were found in serum estradiol and progesterone concentrations between experimental groups. During the histologic study, the Bio group presented a higher number of primordial (P < 0.05) and primary follicles (P = 0.07) compared with that of the eCG group, whereas secondary and antral follicular populations were similar. Rates of late atretic follicles assessed by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling technique were not different between treatments, but the eCG group showed a significantly higher number of mid-atretic follicles compared with that of the Bio group. Nuclear in vitro oocyte maturation (IVM), measured as metaphase II rate, and in vitro steroidogenic response of cumulus-oocyte complexes, measured by ELISA, did not show significant differences between treatments. However, confocal study showed that cytoplasmic maturation of oocytes, in terms of cortical granule migration rate, was significantly higher in the Bio group compared with that after the eCG treatment. In conclusion, transient doe-litter separation seems to improve ovarian response in terms of follicular health and oocyte competence compared with that after the eCG treatment. Therefore, a 24-h-long transient weaning could be an alternative nonhormonal method for synchronizing estrus in primiparous lactating rabbit does inseminated in the early postpartum period. © 2010 Elsevier Inc. All rights reserved.

Breadmaking properties of wheat flour supplemented with thermally processed hypoallergenic lupine flour

  • Guillamón, E.
  • Cuadrado, C.
  • Pedrosa, M. M.
  • Varela, A.
  • Cabellos, B.
  • Muzquiz, M.
  • Burbano, C.
In recent years there has been increased interest in using lupine for human nutrition due to its nutritional properties and health benefits. Moreover, lupine is used as an ingredient in breadmaking because of its functional and technological properties. However, a higher number of allergic reactions to this legume have recently been reported as a consequence of a more widespread consumption of lupine-based foods. In a previous study, several thermal treatments were applied to lupine seeds and flours resulting in reduced allergenicity. In order to study how this thermal processing (autoclaving and boiling) affects the breadmaking properties, raw and thermally processed lupine flours were used to replace 10% of wheat flour. The effect of supplementing wheat flour with lupine flour on physical dough properties, bread structure and sensory characteristics were analysed. The results indicated that thermally-treated lupine flours, had similar breadmaking and sensorial properties as untreated lupine flour. These thermal treatments could increase the potential use of lupine flour as a food ingredient while reducing the risk to provoke allergic reactions.

Application of bioassays for the ecotoxicity assessment of contaminated soils

  • Fernández, M. D.
  • Babín, M.
  • Tarazona, J. V.
The use of bioassays for soil characterization is receiving significant attention as a complementary tool to chemical analysis. Bioassays consist of direct toxicity assays of environmental samples that are transferred to the laboratory and analyzed for toxicity against selected organisms. Such soil samples contain the combination of the different pollutants present in situ and enable factors such as the bioavailability of contaminants or the interactions (synergic and antagonic) between them to be simultaneously studied.In this chapter, methods for soil toxicity assessment based in the guidelines developed by OECD for single substances are described. These methods have been adapted for their application to the assessment of complex matrices such as soils. The field sample can be tested undiluted and/or diluted with "uncontaminated" soil to create a pollution gradient. In the diluted samples, concentration/response relationships may be obtained. Toxicity assays to soil organisms include earthworms, plants, and microorganisms tests. In addition, toxicity assays with soil extracts are recommended. Assays of extracts with algae, daphnia, and fish (in vitro test using fish cell lines) are also described.

Effect of the feeding system on the fatty acid composition, expression of the Δ9-desaturase, Peroxisome Proliferator-Activated Receptor Alpha, Gamma, and Sterol Regulatory Element Binding Protein 1 genes in the semitendinous muscle of light lambs of the Rasa Aragonesa breed

  • Dervishi, E.
  • Serrano, C.
  • Joy, M.
  • Serrano, M.
  • Rodellar, C.
  • Calvo, J. H.
Background Conjugated linoleic acids (CLAs) are receiving increasing attention because of their beneficial effects on human health, with milk and meat products derived from ruminants as important sources of CLA in the human diet. SCD gene is responsible for some of the variation in CLA concentration in adipose tissues, and PPARγ, PPARα and SREBP1 genes are regulator of SCD gene. The aim of this work was to evaluate the effect of the feeding system on fatty acid composition, CLA content and relative gene expression of Δ9-desaturase (SCD), Peroxisome Proliferator-Activated Receptor Gamma (PPARγ), Peroxisome Proliferator-Activated Receptor Alpha, (PPARα) and Sterol Regulatory Element Binding Protein (SREBP1) in Rasa Aragonesa light lambs in semitendinous muscle. Forty-four single-born male lambs were used to evaluate the effect of the feeding system, varying on an intensity gradient according to the use of concentrates 1. grazing alfalfa, 2. grazing alfalfa with a supplement for lambs, 3. indoor lambs with grazing ewes and 4. drylot.Results Both grazing systems resulted in a higher concentration of vaccenic acid (VA), CLA, CLA/VA acid ratio, and a lower oleic content, oleic acid (C181)/stearic acid (C180) ratio, PUFA n-6/n-3 ratio and SCD expression compared to other diets. In addition feeding system affected the fatty acid composition and SCD expression, possibly due to CLA concentration or the PUFA n-6/n-3 ratio. Both expression of the SCD gene and the feeding system were important factors affecting CLA concentration in the animal's semitendinous muscle. PPARγ, PPARα and SREBP1 expression seemed to be unaffected by the feeding system. Although no significant results were found, PPARγ, PPARα and SREBP1 showed similar expression pattern as SCD. Moreover, the correlation results between SCD expression and PPARγ (p &lt; 0.01), as well as SREBP1 (p &lt; 0.01) expression, may suggest that these genes were affecting SCD expression in a different way.Conclusions The data indicated that the feeding system is the main factor affecting the fatty acid composition and SCD gene expression, which is also affected by CLA and possibly by n-6/n-3 PUFAs. © 2010 Dervishi et al; licensee BioMed Central Ltd.

Advanced search