Regenerating plants from in vitro culture of Erigeron breviscapus leaves

A protocol to efficiently achieve plant regeneration from leaf explants of Erigeron breviscapus (Compositae) has been developed. Leaf explants produced calli on Murashige and Skoog’s (1962) basal medium (MS) supplemented with 6-benzylaminopurine (BAP) (0.4 mM) and 2,4-dichlorophenoxyacetic acid (2,4-D) (0.4-22.6 mM) under a 16-h photoperiod. Direct adventitious shoots were induced from leaf explants on MS medium containing BAP (22.2 mM) and IAA (5.7 mM) under the light treatment. The effect of the dark incubation on shoot regeneration from leaves indicated that 15 days of darkness permitted a higher regeneration frequency (82.6%) on the medium supplemented with BAP (4.4 mM) and indole-3- acetic acid (IAA) (0.6 mM). Regenerated shoots were rooted on MS medium with or without naphthaleneacetic acid (NAA). Plantlets were cultivatable in the greenhouse after acclimatization

Physical mapping of a powdery mildew resistance related gene Hv-S/TPK by FISH with a TAC clone in wheat

Dissertação de mestrado integrado em Medicina (Hematologia), apresentado á Faculdade de Medicina da Universidade de Coimbra.A Policitemia Vera (PV) é uma doença clonal de etiologia desconhecida, na maior parte dos casos, que envolve a célula estaminal progenitora hematopoiética multipotencial. É uma neoplasia mieloproliferativa crónica (NMP) que se caracteriza pela expansão das três linhas celulares hematopoiéticas: eritróide, granulocítica e megacariocítica, com predomínio da primeira, de modo independente dos mecanismos normais de regulação da eritropoiese. Além disso, as células têm aspecto morfológico normal, a fibrose medular é pouco significativa e os níveis de eritropoietina (Epo) são habitualmente normais a baixos. Além da hipercelularidade medular com sobreprodução de uma ou de todas as linhas celulares, a doença cursa com hematopoiese extramedular, hiperviscosidade, propensão para complicações como trombose ou hemorragia e risco de desenvolvimento de mielofibrose ou transformação em leucemia aguda. A descrição relativamente recente da associação de uma mutação no gene JAK2, localizado no cromosoma 9p24, com as doenças mieloproliferativas clássicas negativas para BCR-ABL, como a PV, veio permitir avanços significativos na compreensão da patofisiologia deste grupo de doenças hematológicas. A mutação provoca uma alteração do aminoácido V (valina) para F (fenilalanina) na posição 617 (JAK2V617F). De acordo com os dados publicados, a frequência da detecção da mutação JAK2V617F em doentes com PV é de cerca de 95%. A proteína JAK2 é uma tirosina cinase citoplasmática, que se encontra associada ao domínio intracelular dos receptores de citocinas (como a Epo e trombopoietina - Tpo), e de factores de crescimento, essenciais para a função destes receptores. A mutação da JAK2 conduz à activação constitutiva dos receptores, independente da ligação à respectiva citocina e/ou hipersensibilidade a factores de crescimento, com consequente activação de múltiplas vias de sinalização intracelulares como a JAK/STAT (Janus Kinase/Signal Transductor and activator of transcription), a PI3K (fosfatidilinositol 3 cinase) e a MAPK (proteína cinase activadora de mitose), envolvidas na transformação e proliferação dos progenitores hematopoiéticos. Por outro lado, as células evidenciam alteração na diferenciação terminal e resistência à apoptose in vitro que poderá estar relacionada com o aumento da expressão da proteína anti-apoptótica Bcl-XL. Além dos avanços no diagnóstico, a detecção da mutação JAK2V617F tem contribuido para melhorar a classificação e a terapêutica dos doentes com PV. Deste modo, o conhecimento dos mecanismos moleculares envolvidos na PV tem levado os investigadores à descoberta de novos fármacos dirigidos ao defeito molecular, permitindo novas abordagem terapêuticas mais eficazes e provavelmente de menor toxicidade. Este trabalho procura fazer uma revisão sobre o actual conhecimento da caracterização molecular e clínica da PV e quais as suas implicações no diagnóstico e abordagem terapêutica desta NMP.Polycythemia Vera (PV) is a clonal disease of unknown etiology, which often involves the pluripotential hematopoietic stem cell. This disease integrates the family of chronic myeloproliferative neoplasm (MPN) and is characterized by the growth of the three hematopoietic celular lineages: granulocytic, megakaryocytic and erythroid, with predominance of the last one and regardless the normal mechanisms of erythropoiesis regulation. Moreover, cells have normal morphological aspect, bone marrow shows slight fibrosis and the levels of erythropoietin (Epo) usually vary from normal to low. Besides marrow hypercellularity with overproduction of one or all the celular lineages, the disease courses with extramedullary hematopoiesis, hyperviscosity, leading to complications such as thrombosis or bleeding and risk of transformation to myelofibrosis or acute leukemia. Recently it has been described the association between the mutation in the JAK2 gene, located on chromosome 9p24, with the classic myeloproliferative disorders BCR-ABL negative, such as PV, which has brought significant advances in the understanding of the pathophysiology of this group of hematologic malignancies. The mutation causes a change of amino acid V (valine) to F (phenylalanine) at position 617 (JAK2V617F). According to published data, the frequency of JAK2V617F mutation detected in patients with PV is about 95%. JAK2 protein is a cytoplasmic tyrosine kinase, which is associated to the intracelular domain of cytokine receptors, such as Epo and thrombopoietin (Tpo), and growth factors which are essential to the function of these receptors. JAK2 mutation leads to the constitutive receptors activation, independent of connection to their cytokine and / or hypersensitivity to growth factors, with consequent activation of multiple intracellular signaling pathways such as JAK / STAT (Janus Kinase / Signal transducer and transcription activator), the PI3K (phosphatidylinositol 3 kinase) and MAPK (Mitogen-activated protein), involved in the transformation and proliferation of hematopoietic progenitors. Moreover, the cells show changes in terminal differentiation and resistance to in vitro apoptosis which is possibly related to the increasing expression of anti-apoptotic protein Bcl-XL. In addition to the advances in diagnosis, detection of JAK2V617F mutation has contributed to the improvement of classification and treatment in patients with PV. Thus, knowledge of the molecular mechanisms involved in PV has led investigators to the discovery of new drugs targeting molecular defects, allowing new therapeutic approach more efficient and probably less toxic. The aim of this article is to review the current knowledge of clinical and molecular characterization of PV, and its implications on the diagnosis and therapeutic approach of this myeloproliferative disorder

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona

MMagnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s−1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying coron

A rapid method for detection of five known mutations associated with aminoglycoside-induced deafness

<p>Abstract</p> <p>Background</p> <p>South Africa has one of the highest incidences of multidrug-resistant tuberculosis (MDR-TB) in the world. Concomitantly, aminoglycosides are commonly used in this country as a treatment against MDR-TB. To date, at least five mutations are known to confer susceptibility to aminoglycoside-induced hearing loss. The aim of the present study was to develop a rapid screening method to determine whether these mutations are present in the South African population.</p> <p>Methods</p> <p>A multiplex method using the SNaPshot technique was used to screen for five mutations in the <it>MT-RNR1 </it>gene: A1555G, C1494T, T1095C, 961delT+C(n) and A827G. A total of 204 South African control samples, comprising 98 Mixed ancestry and 106 Black individuals were screened for the presence of the five mutations.</p> <p>Results</p> <p>A robust, cost-effective method was developed that detected the presence of all five sequence variants simultaneously. In this pilot study, the A1555G mutation was identified at a frequency of 0.9% in the Black control samples. The 961delT+C(n) variant was present in 6.6% of the Black controls and 2% of the Mixed ancestry controls. The T1095C, C1494T and A827G variants were not identified in any of the study participants.</p> <p>Conclusion</p> <p>The frequency of 0.9% for the A1555G mutation in the Black population in South Africa is of concern given the high incidence of MDR-TB in this particular ethnic group. Future larger studies are warranted to determine the true frequencies of the aminoglycoside deafness mutations in the general South African population. The high frequencies of the 961delT+C(n) variant observed in the controls suggest that this change is a common non-pathogenic polymorphism. This genetic method facilitates the identification of individuals at high risk of developing hearing loss prior to the start of aminoglycoside therapy. This is important in a low-resource country like South Africa where, despite their adverse side-effects, aminoglycosides will continue to be used routinely and are accompanied with very limited or no audiological monitoring.</p

A strategy for emergency treatment of Schistosoma japonicum-infested water

<p>Abstract</p> <p>Background</p> <p>Schistosomiasis japonica, caused by contact with <it>Schistosoma japonicum </it>cercaria-infested water when washing, bathing or production, remains a major public-health concern in China. The purpose of the present study was to investigate the effect of a suspension concentrate of niclosamide (SCN) on killing cercaria of <it>S. japonicum </it>that float on the water surface, and its toxicity to fish, so as to establish an emergency-treatment intervention for rapidly killing cercaria and eliminating water infectivity.</p> <p>Results</p> <p>At 30 min after spraying 100 mg/L SCN, with niclosamide dosages of 0.01, 0.02, 0.03, 0.04 g/m², the water infectivity reduced significantly and no infectivity was found at 60 min after spraying SCN. The surface of static water was sprayed with 100 mg/L SCN, the peak concentration was found at 0 min, and the solution diffused to site with a water depth of 10 cm after 10 min. 30 min later, SCN diffused to the whole water body, and distributed evenly. After spraying 100 mg/L SCN onto the surface of the water with a volume of(3.14 × 20²×50)cm³, with niclosamide dosages of 0.02 g/m², 96 h later, no death of zebra fish was observed.</p> <p>Conclusions</p> <p>By spraying 100 mg/L SCN, with a niclosamide dosage of 0.02 g/m²onto the surface of <it>S. japonicum</it>-infested water, infectivity of the water can be eliminated after 30-60 min, and there is no evident toxicity to fish. This cercaria-killing method, as an emergency-treatment intervention for infested water, can be applied in those forecasting and early warning systems for schistosomiasis.</p

Multiple Independent Genetic Factors at NOS1AP Modulate the QT Interval in a Multi-Ethnic Population

Extremes of electrocardiographic QT interval are associated with increased risk for sudden cardiac death (SCD); thus, identification and characterization of genetic variants that modulate QT interval may elucidate the underlying etiology of SCD. Previous studies have revealed an association between a common genetic variant in NOS1AP and QT interval in populations of European ancestry, but this finding has not been extended to other ethnic populations. We sought to characterize the effects of NOS1AP genetic variants on QT interval in the multi-ethnic population-based Dallas Heart Study (DHS, n = 3,072). The SNP most strongly associated with QT interval in previous samples of European ancestry, rs16847548, was the most strongly associated in White (P = 0.005) and Black (P = 3.6×10−5) participants, with the same direction of effect in Hispanics (P = 0.17), and further showed a significant SNP × sex-interaction (P = 0.03). A second SNP, rs16856785, uncorrelated with rs16847548, was also associated with QT interval in Blacks (P = 0.01), with qualitatively similar results in Whites and Hispanics. In a previously genotyped cohort of 14,107 White individuals drawn from the combined Atherosclerotic Risk in Communities (ARIC) and Cardiovascular Health Study (CHS) cohorts, we validated both the second locus at rs16856785 (P = 7.63×10−8), as well as the sex-interaction with rs16847548 (P = 8.68×10−6). These data extend the association of genetic variants in NOS1AP with QT interval to a Black population, with similar trends, though not statistically significant at P<0.05, in Hispanics. In addition, we identify a strong sex-interaction and the presence of a second independent site within NOS1AP associated with the QT interval. These results highlight the consistent and complex role of NOS1AP genetic variants in modulating QT interval

Improved Measurement of the Pseudoscalar Decay Constant fDsf_{D_{s}}

We present a new determination of the Ds decay constant, f_{Ds} using 5 million continuum charm events obtained with the CLEO II detector. Our value is derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of 0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6 +/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

First Observation of τ→3πηντ\tau\to 3\pi\eta\nu_{\tau} and τ→f1πντ\tau\to f_{1}\pi\nu_{\tau} Decays

We have observed new channels for $\tau$ decays with an $\eta$ in the final state. We study 3-prong tau decays, using the $\eta\to\gamma\gamma$ and \eta\to 3\piz decay modes and 1-prong decays with two \piz's using the $\eta\to\gamma\gamma$ channel. The measured branching fractions are \B(\tau^{-}\to \pi^{-}\pi^{-}\pi^{+}\eta\nu_{\tau}) =(3.4^{+0.6}_{-0.5}\pm0.6)\times10^{-4} and \B(\tau^{-}\to \pi^{-}2\piz\eta\nu_{\tau} =(1.4\pm0.6\pm0.3)\times10^{-4}. We observe clear evidence for $f_1\to\eta\pi\pi$ substructure and measure \B(\tau^{-}\to f_1\pi^{-}\nu_{\tau})=(5.8^{+1.4}_{-1.3}\pm1.8)\times10^{-4}. We have also searched for $\eta'(958)$ production and obtain 90% CL upper limits \B(\tau^{-}\to \pi^{-}\eta'\nu_\tau)<7.4\times10^{-5} and \B(\tau^{-}\to \pi^{-}\piz\eta'\nu_\tau)<8.0\times10^{-5}.Comment: 11 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN