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Bayesian genetic analysis of milk yield in Tunisian Holstein dairy cattle population

Open Journal of Genetics 2012年第2期2卷 103-108页

作者： Houcine Ilahi Mohamed Ben Hammouda Mohamed Houcine Othmane centre régional des recherches agricoles de sidi bouzid Sidi Bouzid Tunisia Institution de recherche et de l’Enseignement Supérieur agricoles (IrESA) Ministère de l’Agriculture et de l’environnement Tunis Tunisia Université de Carthage Institut Préparatoire aux Etudes d’Ingénieurs de Bizerte Zarzouna Tunisia

The genetic determinism of 305-d milk yield and its genetic parameters were investigated in Tunisian Holstein dairy cattle population through Bayesian segregation analyses using a Monte Carlo Markov Chains (MCMC) method. Data included 49,709 records of 305-d milk yield collected between 1996 and 2003 from 114 dairy herds. The postulated major gene was assumed to be additive biallelic locus with Mendelian transmission probabilities and priors used for variance components were uniform. Gibbs sampling was used to generate a chain of 500,000 samples, which were used to obtain posterior means of genetic parameters. Estimated marginal posterior means ± posterior standard deviations of variance components of milk yield were 402866.28 ± 23629.97, 271256.66 ± 34477.83, 68276.83 ± 233027.62 and 1098855.75 ± 10009.52 for polygenic variance (σ2u), permanent environmental variance (σ2ne), major gene variance (σ2G) and error variance (σ2e), respectively. The main finding of this paper showed the postulated major locus was not significant, since the 95% highest posterior density regions (HPDs95%) of most major gene parameters included 0, and particularly for the major gene variance. Estimated transmission probabilities for the 95% highest posterior density regions (HPDs95%) were overlapped. Genetic parameters of 305-d milk yield were very similar under both mixed inheritance and polygenic models. These results indicated that the genetic determinism of milk yield in Tunisian Holstein dairy cattle population is purely polygenic. Based on 50,000 Gibbs samples, heritability and repeatability estimates using polygenic model were h2 = 0.22 ± 0.012 and r = 0.38 ± 0.006, respectively.

关键词： Bayesian Analysis Segregation Major Gene Genetic Parameters Milk Yield Holstein Dairy Cattle

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Fungal diversity in adult date palm(Phoenix dactylifera L.) revealed by culture-dependent and culture-independent approaches

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第12期14卷 1084-1099页

作者： Ines BEN CHOBBA Amine ELLEUCH Imen AYADI Lamia KHANNOUS Ahmed NAMSI Frederique CErQUEIrA Noureddine DrIrA Néji GHArSALLAH Tatiana VALLAEYS Laboratoire de Biotechnologies Végétales Appliquées à l'Amélioration des Cultures LBVAAC Faculté des Sciences de SfaxB.P. 1171 3000 Sfax Tunisia UMr 5119 Université de Montpellier 2 Sciences et Techniques pl E. BataillonCC093 34095 Montpellier France Laboratoire de Microorganismes et de Biomolécules Centre de Biotechnologie de Sfax Université de Sfax Route Sidi MansourB.P. 1177 3018 Sfax Tunisia Laboratoire de Phytopathologie Oasienne Centre Régional de Recherches en Agriculture Oasienne à DegacheDegache 2260 Tunisia Plateforme Séquen age-Génotypage SFr "Montpellier Environnement Biodiversité" ISEM Université de Montpellier 234095 Montpellier France

Endophytic flora plays a vital role in the colonization and survival of host plants, especially in harsh environments, such as arid regions. This flora may, however, contain pathogenic species responsible for various troublesome host diseases. The present study is aimed at investigating the diversity of both cultivable and non-cultivable endophytic fungal floras in the internal tissues(roots and leaves) of Tunisian date palm trees(Phoenix dactylifera). Accordingly, 13 isolates from both root and leaf samples, exhibiting distinct colony morphology, were selected from potato dextrose agar(PDA) medium and identified by a sequence match search wherein their 18S–28S internal transcribed spacer(ITS) sequences were compared to those available in public databases. These findings revealed that the cultivable root and leaf isolates fell into two groups, namely Nectriaceae and Pleosporaceae. Additionally, total DNA from palm roots and leaves was further extracted and ITS fragments were amplified. restriction fragment length polymorphism(rFLP) analysis of the ITS from 200 fungal clones(leaves: 100; roots: 100) using HaeIII restriction enzyme revealed 13 distinct patterns that were further sequenced and led to the identification of Alternaria, Cladosporium, Davidiella(Cladosporium teleomorph), Pythium, Curvularia, and uncharacterized fungal endophytes. Both approaches confirmed that while the roots were predominantly colonized by Fusaria(members of the Nectriaceae family), the leaves were essentially colonized by Alternaria(members of the Pleosporaceae family). Overall, the findings of the present study constitute, to the authors' knowledge, the first extensive report on the diversity of endophytic fungal flora associated with date palm trees(P. dactylifera).

关键词： Date palm tree(Phoenix dactylifera) Endophytic cultivable fungi rDNA internal transcribed spacer(ITS) Phylogenetic analysis Total DNA diversity analysis

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radiolarian and Planktic Foraminifera Biostratigraphy of the Early Albian Organic rich Beds of Fahdene Formation,Northern Tunisia

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Journal of Earth Science 2014年第1期25卷 45-63页

作者： M Ben Fadhel T Zouaghi A Amri M Ben Youssef Département de Géologie Faculté des Sciences de Gafsa-Campus Universitaire Sidi Ahmed Zarrouk–2112 Département des Géoressources CERTE–Technopole de Borj Cédria

The lower part of Fahdene Formation outcropping in northeastern Tunisia is repre- sented by pelagic sequences and characterized by an important siliciclastic fraction that includes ra- diolarian and organic-rich beds of Allam Member. Litho-biostratigraphic analysis based on planktic foraminifera and radiolaria shows that deposition of organic-rich beds of Allam Member is confined to the Microhedbergella rischi Zone through the lower part of Ticinella primula Zone. Age diagnostic radiolaria recovered from these beds has been identified to constrain a direct age of black shale depo- sition. The assemblages can be correlated with the radiolarian biochronozone U.A.10-11 indicating an Early Albian to early Middle Albian in age. radiolarian assemblages composed of species characteris- tic of U.A.10 biochronozone （A. montisserei, D. gracilis） are associated with radiolarian taxa belonging to Costata Zone （U.A.9 Pseudoeucyrtis hanni and Thanarla pseudodecora）, which can be correlated with dercourt Member in the Ionian Zone and Paquier level of the Vocontian Basin （southeast of France）. Biostratigraphic and abundance curves analysis has demonstrated significant diversification of cryptocephalic Nassellaria and Archaeodictyomitrae, probably adapted to eutrophic conditions that characterized the Aptian-Albian transition. Ecological conditions may have governed the stratigraphic range of many cosmopolitan taxa （i.e., Pseudodictyomitrae lodogaensis） compared with stratigraphic distributions schemes reported from other domains. The timing of black shales deposition was dia- chronic due to local geodynamic conditions and upwelling currents distribution. The Allam black shales are correlative with the oceanic anoxic event OAElb which is characterized by the widespread of supraregionnally organic-rich beds in the Mediterranean Tethys basins across the Aptian-Albian transition.

关键词： northeastern Tunisia Albian Allam Member black shale radiolaria planktic foraminifera.

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