265 research outputs found
Differences in MAT gene distribution and expression between Rhynchosporium species on grasses
Leaf blotch is a globally important disease of barley crops and other grasses that is caused by at least five host-specialized species in the fungal genus Rhynchosporium. The pathogen R. commune (specialized to barley, brome-grass and Italian ryegrass) has long been considered to reproduce only by asexual means, but there has been accumulating evidence for recombination and gene flow from population genetic studies and the detection of complementary MAT1-1 and MAT1-2 isolates in a c. 1:1 ratio in the field. Here, it is demonstrated that 28 isolates of the closely related species R. agropyri (on couch-grass) and R. secalis (on rye and triticale), collected from Europe, were also either of MAT1-1 or MAT1-2 genotype and that the distribution of mating types did not deviate significantly from a 1:1 ratio. Evidence is then provided for MAT1-1-1 and MAT1-2-1 gene expression during mycelial growth for all three species. By contrast, 27 isolates of the more distantly related R. orthosporum (on cocksfoot) and R. lolii (on Italian and perennial ryegrasses) from Europe were exclusively of the MAT1-1 genotype, and expression of the MAT1-1-1 gene could not be detected during mycelial growth. These data suggest that cryptic sexual cycles are more likely to exist for R. commune, R. agropyri and R. secalis than for either R. orthosporum or R. lolii. A phylogenetic analysis of partial MAT1-1 idiomorph sequences resolved these five species into two distinct groups (R. commune, R. agropyri and R. secalis versus R. orthosporum and R. lolii) but provided only limited resolution within each group
Differences in MAT gene distribution and expression between Rhynchosporium species on grasses
Leaf blotch is a globally important disease of barley crops and other grasses that is caused by at least five host-specialized species in the fungal genus Rhynchosporium. The pathogen R. commune (specialized to barley, brome-grass and Italian ryegrass) has long been considered to reproduce only by asexual means, but there has been accumulating evidence for recombination and gene flow from population genetic studies and the detection of complementary MAT1-1 and MAT1-2 isolates in a c. 1:1 ratio in the field. Here, it is demonstrated that 28 isolates of the closely related species R. agropyri (on couch-grass) and R. secalis (on rye and triticale), collected from Europe, were also either of MAT1-1 or MAT1-2 genotype and that the distribution of mating types did not deviate significantly from a 1:1 ratio. Evidence is then provided for MAT1-1-1 and MAT1-2-1 gene expression during mycelial growth for all three species. By contrast, 27 isolates of the more distantly related R. orthosporum (on cocksfoot) and R. lolii (on Italian and perennial ryegrasses) from Europe were exclusively of the MAT1-1 genotype, and expression of the MAT1-1-1 gene could not be detected during mycelial growth. These data suggest that cryptic sexual cycles are more likely to exist for R. commune, R. agropyri and R. secalis than for either R. orthosporum or R. lolii. A phylogenetic analysis of partial MAT1-1 idiomorph sequences resolved these five species into two distinct groups (R. commune, R. agropyri and R. secalis versus R. orthosporum and R. lolii) but provided only limited resolution within each group
Sturmian morphisms, the braid group B_4, Christoffel words and bases of F_2
We give a presentation by generators and relations of a certain monoid
generating a subgroup of index two in the group Aut(F_2) of automorphisms of
the rank two free group F_2 and show that it can be realized as a monoid in the
group B_4 of braids on four strings. In the second part we use Christoffel
words to construct an explicit basis of F_2 lifting any given basis of the free
abelian group Z^2. We further give an algorithm allowing to decide whether two
elements of F_2 form a basis or not. We also show that, under suitable
conditions, a basis has a unique conjugate consisting of two palindromes.Comment: 25 pages, 4 figure
The nil Hecke ring and singularity of Schubert varieties
We give a criterion for smoothness of a point in any Schubert variety in any
G/B in terms of the nil Hecke ring.Comment: AMSTE
Hsp72 and Nek6 cooperate to cluster amplified centrosomes in cancer cells
Cancer cells frequently possess extra amplified centrosomes clustered into two poles whose pseudo-bipolar spindles exhibit reduced fidelity of chromosome segregation and promote genetic instability. Inhibition of centrosome clustering triggers multipolar spindle formation and mitotic catastrophe, offering an attractive therapeutic approach to selectively kill cells with amplified centrosomes. However, mechanisms of centrosome clustering remain poorly understood. Here, we identify a new pathway that acts through NIMA-related kinase 6 (Nek6) and Hsp72 to promote centrosome clustering. Nek6, as well as its upstream activators polo-like kinase 1 (Plk1) and Aurora-A, targeted Hsp72 to the poles of cells with amplified centrosomes. Unlike some centrosome de-clustering agents, blocking Hsp72 or Nek6 function did not induce formation of acentrosomal poles, meaning that multipolar spindles were observable only in cells with amplified centrosomes. Inhibition of Hsp72 in acute lymphoblastic leukaemia cells resulted in increased multipolar spindle frequency that correlated with centrosome amplification, while loss of Hsp72 or Nek6 function in non-cancer derived cells disturb neither spindle formation nor mitotic progression. Hence, the Nek6-Hsp72 module represents a novel actionable pathway for selective targeting of cancer cells with amplified centrosomes
Enhanced Activation of an Amino-Terminally Truncated Isoform of Voltage-Gated Proton Channel HVCN1 Enriched in Malignant B cells
Learedius learedi Price 1934 (Digenea, Spirorchiidae) in Chelonia mydas Linnaeus 1758 (Testudines, Chelonidae) in Brazil: case report
A multi-centre phase I trial of the PARP inhibitor olaparib in patients with relapsed chronic lymphocytic leukaemia, T-prolymphocytic leukaemia or mantle cell lymphoma
Particle Motion Around Tachyon Monopole
Recently, Li and Liu have studied global monoole of tachyon in a four
dimensional static space-time. We analyze the motion of massless and massive
particles around tachyon monopole. Interestingly, for the bending of light rays
due to tachyon monopole instead of getting angle of deficit we find angle of
surplus. Also we find that the tachyon monopole exerts an attractive
gravitational force towards matter.Comment: 14 pages, 7 figure
Identification of the gene encoding cyclin E1 (CCNE1) as a novel IGH translocation partner in t(14;19)(q32;q12) in diffuse large B-cell lymphoma
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