An efficient algorithm for supertrees

Givenk rooted binary treesA ₁, A₂, ..., A_k, with labeled leaves, we generateC, a unique system of lineage constraints on common ancestors. We then present an algorithm for constructing the set of rooted binary treesB, compatible with all ofA ₁, A₂, ..., A_k. The running time to obtain one such supertree isO(k ² n²), wheren is the number of distinct leaves in all of the treesA ₁, A₂, ..., A_k.     

Oncogenic mechanisms in myeloproliferative disorders

Myeloproliferative disorders (MPDs) are clonal haematopoietic malignancies involving the abnormal proliferation of myeloid lineages. The World Health Organisation (WHO) classification of haematopoietic malignancies distinguishes MPDs from myelodysplastic/ myeloproliferative disorders and systemic mastocytosis. These malignancies frequently involve constitutive tyrosine kinase activity, resulting from either oncogenic fusion protein production or from point mutations. Chronic myelogenous leukaemia is the model used for studies of the consequences of such molecular defects. However, the heterogeneity of the clinical course of MPDs should be seen in a more rationale conceptual framework, including the many molecular events associated with these diseases. This review focuses on the various tyrosine kinase-related molecular mechanisms underlying both MPDs and rare diseases with myeloproliferative features. We pay particular attention to the newly identified JAK2 V617F mutation in polycythaemia vera, essential thrombocythaemia and idiopathic myelofibrosis and deal with disease heterogeneity and putative additional molecular mechanisms. Received 9 June 2006; received after revision 28 July 2006; accepted 11 September 2006     

A unique clonal JAK2 mutation leading to constitutive signalling causes polycythaemia vera

Myeloproliferative disorders are clonal haematopoietic stem cell malignancies characterized by independency or hypersensitivity of haematopoietic progenitors to numerous cytokines. The molecular basis of most myeloproliferative disorders is unknown. On the basis of the model of chronic myeloid leukaemia, it is expected that a constitutive tyrosine kinase activity could be at the origin of these diseases. Polycythaemia vera is an acquired myeloproliferative disorder, characterized by the presence of polycythaemia diversely associated with thrombocytosis, leukocytosis and splenomegaly. Polycythaemia vera progenitors are hypersensitive to erythropoietin and other cytokines. Here, we describe a clonal and recurrent mutation in the JH2 pseudo-kinase domain of the Janus kinase 2 (JAK2) gene in most (> 80%) polycythaemia vera patients. The mutation, a valine-to-phenylalanine substitution at amino acid position 617, leads to constitutive tyrosine phosphorylation activity that promotes cytokine hypersensitivity and induces erythrocytosis in a mouse model. As this mutation is also found in other myeloproliferative disorders, this unique mutation will permit a new molecular classification of these disorders and novel therapeutical approaches.     

Tree enumeration modulo a consensus

The number of trees withn labeled terminal vertices grows too rapidly withn to permit exhaustive searches for Steiner trees or other kinds of optima in cladistics and related areas Often, however, structured constraints are known and may be imposed on the set of trees to be scanned These constraints may be formulated in terms of a consensus among the trees to be searched We calculate the reduction in the number of trees to be enumerated as a function of properties of the imposed consensusThis work was supported in part by the Natural Sciences and Engineering Research Council of Canada through operating grant A8867 to D Sankoff and infrastructure grant A3092 to D Sankoff, R J Cedergren and G Lapalme We are grateful to William H E Day for much encouragement and many helpful suggestions     

The effect of thyroid state on monophasic action potential in human heart

Résumé L'enregistrment du potentiel monophasique d'action de l'auricule droite a été effectué à l'aide des électrodes de succion, chez 9 patients. On constate un allongement notable du potentiel monophasique chez les hypothyroïdiens, il se raccourcit après traitement thyroïdien, tandis que chez les hyperthyooïdiens sa durée est diminuée.     

Two new species of feather mites (Acarina: Psoroptidia) from the blue-throated blue flycatcher,Cyornis rubeculoides (Passeriformes: Muscicapidae)

The paper describes two new species of feather mites collected from the blue-throated blue flycatcher Cyornis rubeculoides (Vigors) (Passeriformes: Muscicapidae) in India (Meghalaya): Trouessartia kharkhanensis Constantinescu et al. sp. nov. (Trouessartiidae) and Proterothrix cyornissimilis Constantinescu et al. sp. nov. (Proctophyllodidae: Pterodectinae). Both sexes of T. kharkhanensis differ from the closest species, T. rubecula Jablonska, 1968 by having setae si and c2 lanceolate and setae c3 and sRIII with acute apex. In males of the new species, the adanal apodemes have a hook-like retroverse apophysis and the internal margins of terminal lamellae have a shallow invagination at the level of setae h3. Both sexes of P. cyornissimilis differ from the closest species, P. cyornis Mironov and Tolstenkov, 2013, mainly by the ornamentation of the dorsal shields: it is absent on the prodorsal shield and poorly expressed on the hysteronothal shield. In males of the new species, the supranal concavity is triangular and the genital arch has a pair of small ovoid sclerites at its tips.

http:/zoobank.org/urn:lsid:zoobank.org:pub:1671D6D4-8895-467B-A124-05EDBB0DF406     

Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability.     

The birth of a quasiparticle in silicon observed in time-frequency space

The concept of quasiparticles in solid-state physics is an extremely powerful tool for describing complex many-body phenomena in terms of single-particle excitations. Introducing a simple particle, such as an electron, hole or phonon, deforms a many-body system through its interactions with other particles. In this way, the added particle is 'dressed' or 'renormalized' by a self-energy cloud that describes the response of the many-body system, so forming a new entity--the quasiparticle. Using ultrafast laser techniques, it is possible to impulsively generate bare particles and observe their subsequent dressing by the many-body interactions (that is, quasiparticle formation) on the time and energy scales governed by the Heisenberg uncertainty principle. Here we describe the coherent response of silicon to excitation with a 10-femtosecond (10(-14) s) laser pulse. The optical pulse interacts with the sample by way of the complex second-order nonlinear susceptibility to generate a force on the lattice driving coherent phonon excitation. Transforming the transient reflectivity signal into frequency-time space reveals interference effects leading to the coherent phonon generation and subsequent dressing of the phonon by electron-hole pair excitations.