Révision systématique du genre Microthrissa Boulenger, 1902 des eaux douces africaines (Pisces, Clupeidae)

Le genre #Microthrissa a été révisé à partir de caractères morphologiques et ostéologiques de 461 exemplaires, y compris les spécimens types de toutes les espèces nominales. Le genre #Poecilothrissa est synonyme du genre #Microthrissa, au sein duquel il a été reconnu comme un sous-genre distinct. Cinq espèces valides ont été retenues. Deux espèces nominales ont été mises en synonymie. Enfin, #Microthrissa normanae a été rapporté au genre #Pellonula, et mis en synonymie avec #P. leonensis. (Résumé d'auteur

Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 56

A neotype for Clarias gariepinus (Burchell, 1822) is designated and described. Data from 41 specimens from the type locality are also presented. The geographical distribution of the species is discussed.Rhodes University Libraries (Digitisation

Manuel pratique d'identification des poissons du lac d'Ayamé (Rivière Bia, Côte d'Ivoire)

A taxonomic assessment of fish species was carried out in the Lake Ayamé as a preliminary evaluation within the framework of a project to appraise the biodiversity changes occurred in fish after the construction of a dam at Ayamé in 1959

A Grassmann integral equation

The present study introduces and investigates a new type of equation which is called Grassmann integral equation in analogy to integral equations studied in real analysis. A Grassmann integral equation is an equation which involves Grassmann integrations and which is to be obeyed by an unknown function over a (finite-dimensional) Grassmann algebra G_m. A particular type of Grassmann integral equations is explicitly studied for certain low-dimensional Grassmann algebras. The choice of the equation under investigation is motivated by the effective action formalism of (lattice) quantum field theory. In a very general setting, for the Grassmann algebras G_2n, n = 2,3,4, the finite-dimensional analogues of the generating functionals of the Green functions are worked out explicitly by solving a coupled system of nonlinear matrix equations. Finally, by imposing the condition G[{\bar\Psi},{\Psi}] = G_0[{\lambda\bar\Psi}, {\lambda\Psi}] + const., 0<\lambda\in R (\bar\Psi_k, \Psi_k, k=1,...,n, are the generators of the Grassmann algebra G_2n), between the finite-dimensional analogues G_0 and G of the (``classical'') action and effective action functionals, respectively, a special Grassmann integral equation is being established and solved which also is equivalent to a coupled system of nonlinear matrix equations. If \lambda \not= 1, solutions to this Grassmann integral equation exist for n=2 (and consequently, also for any even value of n, specifically, for n=4) but not for n=3. If \lambda=1, the considered Grassmann integral equation has always a solution which corresponds to a Gaussian integral, but remarkably in the case n=4 a further solution is found which corresponds to a non-Gaussian integral. The investigation sheds light on the structures to be met for Grassmann algebras G_2n with arbitrarily chosen n.Comment: 58 pages LaTeX (v2: mainly, minor updates and corrections to the reference section; v3: references [4], [17]-[21], [39], [46], [49]-[54], [61], [64], [139] added

Alu distribution and mutation types of cancer genes

Background: Alu elements are the most abundant retrotransposable elements comprising ~11% of the human genome. Many studies have highlighted the role that Alu elements have in genetic instability and how their contribution to the assortment of mutagenic events can lead to cancer. As of yet, little has been done to quantitatively assess the association between Alu distribution and genes that are causally implicated in oncogenesis.Results: We have investigated the effect of various Alu densities on the mutation type based classifications of cancer genes. In order to establish the direct relationship between Alus and the cancer genes of interest, genome wide Alu-related densities were measured using genes rather than the sliding windows of fixed length as the units. Several novel genomic features, such as the density of the adjacent Alu pairs and the number of Alu-Exon-Alu triplets, were developed in order to extend the investigation via the multivariate statistical analysis toward more advanced biological insight. In addition, we characterized the genome-wide intron Alu distribution with a mixture model that distinguished genes containing Alu elements from those with no Alus, and evaluated the gene-level effect of the 5\u27-TTAAAA motif associated with Alu insertion sites using a two-step regression analysis method.Conclusions: The study resulted in several novel findings worthy of further investigation. They include: (1) Recessive cancer genes (tumor suppressor genes) are enriched with Alu elements (p \u3c 0.01) compared to dominant cancer genes (oncogenes) and the entire set of genes in the human genome; (2) Alu-related genomic features can be used to cluster cancer genes into biological meaningful groups; (3) The retention of exon Alus has been restricted in the human genome development, and an upper limit to the chromosome-level exon Alu densities is suggested by the distribution profile; (4) For the genes with at least one intron Alu repeat in individual chromosomes, the intron Alu densities can be well fitted by a Gamma distribution; (5) The effect of the 5\u27-TTAAAA motif on Alu densities varies across different chromosomes

The occurrence of germline BRCA1 and BRCA2 sequence alterations in Slovenian population

<p>Abstract</p> <p>Background</p> <p>The <it>BRCA1 </it>and <it>BRCA2 </it>mutation spectrum and mutation detection rates according to different family histories were investigated in 521 subjects from 322 unrelated Slovenian cancer families with breast and/or ovarian cancer.</p> <p>Methods</p> <p>The <it>BRCA1 </it>and <it>BRCA2 </it>genes were screened using DGGE, PTT, HRM, MLPA and direct sequencing.</p> <p>Results</p> <p>Eighteen different mutations were found in <it>BRCA1 </it>and 13 in <it>BRCA2 </it>gene. Mutations in one or other gene were found in 96 unrelated families. The mutation detection rates were the highest in the families with at least one breast and at least one ovarian cancer - 42% for <it>BRCA1 </it>and 8% for <it>BRCA2</it>. The mutation detection rate observed in the families with at least two breast cancers with disease onset before the age of 50 years and no ovarian cancer was 23% for <it>BRCA1 </it>and 13% for <it>BRCA2</it>. The mutation detection rate in the families with at least two breast cancers and only one with the disease onset before the age of 50 years was 11% for <it>BRCA1 </it>and 8% for <it>BRCA2</it>. In the families with at least two breast cancers, all of them with disease onset over the age of 50 years, the detection rate was 5% for <it>BRCA2 </it>and 0% for <it>BRCA1</it>.</p> <p>Conclusion</p> <p>Among the mutations detected in Slovenian population, 5 mutations in <it>BRCA1 </it>and 4 mutations in <it>BRCA2 </it>have not been described in other populations until now. The most frequent mutations in our population were c.181T > G, c.1687C > T, c.5266dupC and c.844_850dupTCATTAC in <it>BRCA1 </it>gene and c.7806-2A > G, c.5291C > G and c.3978insTGCT in <it>BRCA2 </it>gene (detected in 69% of <it>BRCA1 </it>and <it>BRCA2 </it>positive families).</p