Identification of a new repetitive element in the sex chromosomes of Leporinus elongatus (Teleostei : Characiformes : Anostomidae): new insights into the sex chromosomes of Leporinus

Leporinus elongatus represents an interesting model for studies on chromosome evolution since it possesses a conspicuous ZZ/ZW sex chromosome system that has been characterized mainly by basic cytogenetic techniques. In the present study we describe a dispersed repetitive element ( named Le SpeI) related to the sex chromosomes of L. elongatus. Females revealed clusters of Le SpeI on the long arm of the W chromosome and in the acrocentric NOR-bearing chromosome pair. In males, the signal was restricted to the pericentromeric region of the NOR-bearing chromosomes. Considering the results obtained in the present study using FISH, NOR and C-banding, together with findings from previous studies, it can be inferred that the sex chromosome system of L. elongatus is still undergoing an evolutionary process. The data suggest novelties in relation to the sex chromosomes of the genus Leporinus with the description of a multiple sex chromosome system involving the NOR-bearing chromosomes. Therefore, it is hypothesized that the simple ZW chromosome system previously described for L. elongatus rather is a multiple Z(1)Z(1)Z(2)Z(2)/Z(1)W(1)Z(2)W(2) system. Copyright (c) 2007 S. Karger AG, Basel

Interspecific chromosomal divergences in the genus Characidium (Teleostei: Characiformes: Crenuchidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosomal diversification in populations of Characidium cf. gomesi (Teleostei, Crenuchidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conventional and ultrastructural analyses of the chromosomes of Discocyrtus pectinifemur (Opiliones, Laniatores, Gonyleptidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anomalous quartic gauge boson couplings at hadron colliders

We analyze the potential of the Fermilab Tevatron and CERN Large Hadron Collider (LHC) to study anomalous quartic vector-boson interactions gamma gamma ZZ and gammaW(+)W(-). Working in the framework of SU(2)(L) circle times U(1)(Y) chiral Lagrangians, we study the production of photon pairs accompanied by l(+) l(-), l(+/-) v, and jet pairs to impose bounds on these new couplings, taking into account the unitarity constraints. We compare our findings with the indirect limits coming from precision electroweak measurements as well as with presently available direct searches at CERN LEPII. We show that the Tevatron run II can provide limits on these quartic limits which are of the same order of magnitude as the existing bounds from LEPII searches. LHC will be able to tighten considerably the direct constraints on these possible new interactions, leading to more stringent limits than the presently available indirect ones.

Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of W gamma and Z gamma production in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Combined results of searches for the standard model Higgs boson in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Is the LHC observing the pseudoscalar state of a two-Higgs-doublet model?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for a fermiophobic Higgs boson in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Observation of Z decays to four leptons with the CMS detector at the LHC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Extensive polymorphism and chromosomal characteristics of ribosomal DNA in the characid fish Triportheus venezuelensis (Characiformes, Characidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

IDENTIFYING THE HIGGS-BOSON IN ELECTRON-PHOTON COLLISIONS

We analyze the production and detection of the Higgs boson in the next generation of linear e+e-colliders operating in the egamma mode. In particular, we study the production mechanism e+gamma --> egammagamma --> e + H, where one photon is generated via the laser backscattering mechanism, while the other is radiated via the usual bremsstrahlung process. We show that this is the most important mechanism for Higgs boson production in a 500 GeV egamma collider for M(H) greater than or similar to 140 GeV. We also study the signals and backgrounds for detection of the Higgs boson in the different decay channels bbBAR, W+W-, and ZZ, and suggest kinematical cuts to improve the signature of an intermediate-mass Higgs boson.

CYTOGENETIC STUDIES ON THE SUBFAMILY HYPOPTOPOMATINAE (PISCES, SILURIFORMES, LORICARIIDAE) .3. ANALYSIS OF 7 SPECIES

Cytogenetic studies carried out on nine species belonging to five genera of the subfamily Hypoptopomatinae showed that this group has a relatively constant diploid number, 2n = 54, with only one species having 2n = 72 chromosomes. Nevertheless, the karyotypic formulae, NOR position and C-band pattern are very different among species and sometimes among local populations, with species having undifferentiated sex chromosomes and species having the XX/XY or the ZZ/ZW mechanisms. The population structure of species belonging to the subfamily Hypoptopomatinae suggests that many chromosome rearrangements have been fixed in the different species and populations due to their geographic isolation and these karyotypic differences may be very important today for species definition.

Chromosomal evolution in Gekkonidae. I. Chromosome painting between Gekko and Hemidactylus species reveals phylogenetic relationships within the group

Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6.