Barrier-to-autointegration factor (BAF) is potentially a DNA-bridging protein, which directly associates with inner nuclear membrane proteins carrying LEM domains. These features point to a key role in regulation of nuclear function and organization, dependent on interactions between the nuclear envelope and chromatin. To understand the functions of BAF in vivo, Drosophila baf null mutants generated by P-element-mediated imprecise excision were analyzed. Homozygous null mutants showed a typical mitotic mutant phenotype: lethality at the larval-pupal transition with small brains and missing imaginal discs. Mitotic figures were decreased but a defined anaphase defect as reported for C. elegans RNAi experiments was not observed in these small brains, suggesting a different phase or phases of cell cycle arrest. Specific abnormalities in interphase nuclear structure were frequently found upon electron microscopic examination of baf null mutants, with partial clumping of chromatin and convolution of nuclear shape. At the light microscopic level, grossly aberrant nuclear lamina structure and B-type lamin distribution correlated well with the loss of detectable amounts of BAF protein from nuclei. Together, these data represent evidence of BAF's anticipated function in mediating interactions between the nuclear envelope and interphase chromosomes. We thus conclude that BAF plays essential roles in nuclear organization and that these BAF functions are required in both M phase and interphase of the cell cycle.

MATCH provides an overview of segmentation methodologies for IAs and highlights the variability of surface reconstruction. Further, the study emphasizes the need for careful processing of initial segmentation results for a realistic assessment of clinically relevant morphological parameters.

We report the identification and characterization of Dnrk (Drosophila neurospecific receptor kinase), a Drosophila gene encoding a putative receptor tyrosine kinase (RTK) highly related to the Trk and Ror families of RTKs. During Drosophila embryogenesis, the Dnrk gene is expressed specifically in the developing nervous system. The Dnrk protein possesses two conserved cysteine-containing domains and a kringle domain within its extracellular domain, resembling those observed in Ror family RTKs (Ror1, Ror2, and a Drosophila Ror, Dror). This protein contains the catalytic tyrosine kinase (TK) domain with two putative ATP-binding motifs, resembling those observed in another Drosophila RTK (Dtrk) that mediates homophilic cell adhesion. The TK domain of Dnrk, expressed in bacteria or mammalian cells, exhibits apparent autophosphorylation activities in vitro. The TK domain lacking the distal ATP-binding motif also exhibits autophosphorylation activity, yet to a lesser extent. In addition to its TK activity, there are several putative tyrosine-containing motifs that upon phosphorylation may interact with Src homology 2 regions of other signaling molecules. Collectively, these results suggest that Dnrk may play an important role in neural development during Drosophila embryogenesis.

To elucidate the function of metazoan B-type lamins during development, new null mutations of the Drosophila B-type lamin gene, lamDm(0), were analyzed in parallel with the misg(sz18) mutation, a lamDm(0) allele reported previously. Although in all these mutants, lamin Dm(0) protein was undetectable in neuroblasts and imaginal disc cells from the second instar larval stage onward, cells continued to proliferate. In contrast to the embryonic lethality of another Drosophila lamDm(0) allele, lam(PM15), reported previously, lethality did not occur until late pupal stages. Chromosomal structure and the overall nuclear shape remained normal even at these late pupal stages, although obviously abnormal nuclear pore complex distribution was observed concomitant with the loss of lamin Dm(0) protein. Compensating expression of lamin C was not induced in the absence of lamin Dm(0). Thus, no lamin-containing nuclear structures were found in proliferating larval neuroblasts. We did find that developmental abnormalities appeared in specific organs during the late pupal stage, preceding lethality. Surprisingly, coordinated size increase (hypertrophy) of the ventriculus was observed accompanied by cell division and muscle layer formation. Hypertrophy of the ventriculus correlated with a decrease in ecdysteroid hormone receptor B1 (EcRB1) protein, and furthermore could be suppressed by a heat-inducible EcRB1 transgene. In contrast, both gonadal and CNS tissues exhibited underdevelopment.

Nuclear protein kinases are believed to play important roles in regulating gene expression. We report here the identification and developmental expression of Dmnk (Drosophila maternal nuclear kinase), a Drosophila gene encoding a putative nuclear protein serine/threonine kinase with no apparent homology to previously identified protein kinases and located at 38B on the second chromosome. Dmnk mRNAs are transcribed in nurse cells and are subsequently localized in the anterior of oocytes during oogenesis, in a manner similar to several maternal transcripts regulating oogenesis and early embryogenesis. At early cleavage-stages Dmnk transcripts are transiently present throughout the embryo, but become restricted to the posterior pole and then to the newly-formed primordial germ cells (pole cells) by the blastoderm stage. The transcripts are sustained in the pole cells during gastrulation until they pass through the midgut pocket wall into the body cavity. Immunostaining with specific antibodies revealed that Dmnk proteins are localized to the nuclei in a speckled pattern. Dmnk proteins become detectable in both somatic and germ line cell nuclei upon their arrival at the periplasm of the syncytial embryo, but then disappear from the somatic cell nuclei. Consistent with mRNA expression, Dmnk proteins in pole cell nuclei are sustained during gastrulation. Taken together, Dmnk represents a novel class of nuclear protein kinases and the dynamic expression of Dmnk suggests a role in germ line establishment. The results are discussed in the light of recent findings concerning germ line establishment in Caenorhabditis and Drosophila.

BACKGROUND AND PURPOSE:The incidence of wall enhancement of cerebral aneurysms on vessel wall MR imaging has been described as higher in ruptured intracranial aneurysms than in unruptured intracranial aneurysms, but the difference in the degree of enhancement between ruptured and unruptured aneurysms is unknown. We compared the degree of enhancement between ruptured and unruptured intracranial aneurysms by using quantitative MR imaging measures.

The area with prolonged RRT colocalized with atherosclerotic change on the aneurysm wall. Male sex and maximum RRT were independent risk factors for atherogenesis in intracranial aneurysms.

With the increased availability of computational resources, the past decade has seen a rise in the use of computational fluid dynamics (CFD) for medical applications. There has been an increase in the application of CFD to attempt to predict the rupture of intracranial aneurysms, however, while many hemodynamic parameters can be obtained from these computations, to date, no consistent methodology for the prediction of the rupture has been identified. One particular challenge to CFD is that many factors contribute to its accuracy; the mesh resolution and spatial/temporal discretization can alone contribute to a variation in accuracy. This failure to identify the importance of these factors and identify a methodology for the prediction of ruptures has limited the acceptance of CFD among physicians for rupture prediction. The International CFD Rupture Challenge 2013 seeks to comment on the sensitivity of these various CFD assumptions to predict the rupture by undertaking a comparison of the rupture and blood-flow predictions from a wide range of independent participants utilizing a range of CFD approaches. Twenty-six groups from 15 countries took part in the challenge. Participants were provided with surface models of two intracranial aneurysms and asked to carry out the corresponding hemodynamics simulations, free to choose their own mesh, solver, and temporal discretization. They were requested to submit velocity and pressure predictions along the centerline and on specified planes. The first phase of the challenge, described in a separate paper, was aimed at predicting which of the two aneurysms had previously ruptured and where the rupture site was located. The second phase, described in this paper, aims to assess the variability of the solutions and the sensitivity to the modeling assumptions. Participants were free to choose boundary conditions in the first phase, whereas they were prescribed in the second phase but all other CFD modeling parameters were not prescribed. In order to compare the computational results of one representative group with experimental results, steady-flow measurements using particle image velocimetry (PIV) were carried out in a silicone model of one of the provided aneurysms. Approximately 80% of the participating groups generated similar results. Both velocity and pressure computations were in good agreement with each other for cycle-averaged and peak-systolic predictions. Most apparent "outliers" (results that stand out of the collective) were observed to have underestimated velocity levels compared to the majority of solutions, but nevertheless identified comparable flow structures. In only two cases, the results deviate by over 35% from the mean solution of all the participants. Results of steady CFD simulations of the representative group and PIV experiments were in good agreement. The study demonstrated that while a range of numerical schemes, mesh resolution, and solvers was used, similar flow predictions were observed in the majority of cases. To further validate the computati...