MAX1and MAX2 control shoot lateral branching in Arabidopsis

Plant shoots elaborate their adult form by selective control over the growth of both their primary shoot apical meristem and their axillary shoot meristems. We describe recessive mutations at two loci in Arabidopsis, MAX1 and MAX2, that affect the selective repression of axillary shoots. All the first order (but not higher order) axillary shoots initiated by mutant plants remain active, resulting in bushier shoots than those of wild type. In vegetative plants where axillary shoots develop in a basal to apical sequence, the mutations do not clearly alter node distance, from the shoot apex, at which axillary shoot meristems initiate but shorten the distance at which the first axillary leaf primordium is produced by the axillary shoot meristem. A small number of mutant axillary shoot meristems is enlarged and, later in development, a low proportion of mutant lateral shoots is fasciated. Together, this suggests that MAX1 and MAX2 do not control the timing of axillary meristem initiation but repress primordia formation by the axillary meristem. In addition to shoot branching, mutations at both loci affect leaf shape. The mutations at MAX2 cause increased hypocotyl and petiole elongation in light-grown seedlings. Positional cloning identifies MAX2 as a member of the F-box leucine-rich repeat family of proteins. MAX2 is identical to ORE9, a proposed regulator of leaf senescence (Woo, H. R., Chung, K. M., Park, J.-H., Oh, S. A., Ahn, T., Hong, S. H., Jang, S. K. and Nam, H. G. (2001) Plant Cell 13, 1779-1790). Our results suggest that selective repression of axillary shoots involves ubiquitinmediated degradation of as yet unidentified proteins that activate axillary growth

Convergence of Discretized Light Cone Quantization in the small mass limit

I discuss the slow convergence of Discretized Light Cone Quantization (DLCQ) in the small mass limit and suggest a solution.Comment: 8 pages, 5 Postscript figures, uses boxedeps.te

ENOD40 encodes a peptide growth factor

Rhizobium bacteria induce the formation of nodules on the roots of leguminous plants. The nodules create the right biological niche for the rhizobia to carry out biological nitrogen fixation by which atmospheric nitrogen is reduced to ammonia. The nodule is a new organ that provides the plant with a nitrogen source for its growth and development. The formation of a nitrogen fixing root nodule is the final result of an extensive collaboration between the plant and the bacterium, which starts with the exchange of signals. The plant roots secrete flavonoids, which attract rhizobia and induce the expression of nodulation (nod) genes in the rhizobia. Due to the nod gene expression, specific lipochitooligosaccharide signals are produced, the so-called Nod factors, that induce several responses in the roots as a result of which nodule formation can start. The first plant responses are root hair deformation, expression of several plant genes and the mitotic reactivation of root cortical cells which leads to the formation of a nodule primordium. In chapter I a general overview is given of the signal exchange leading to the formation of a functional root nodule.The aim of the research, described in this thesis, was to analyse the role of the early nodulin gene ENOD40 in nodule development. To adress this issue, ENOD40 expression was determined in nodules and its actvity was studied in an in vitro model system. First an ENOD40 clone was isolated from pea using the available soybean ENOD40 cDNA as a probe. This made it possible to compare the expression pattern of ENOD40 in a determinate (soybean) and indeterminate (pea) nodule by in situ hybridisation. using the soybean and pea ENOD40 clones, respectively, as probes (chapter 2). Chapter 3 describes the isolation and characterisation of the soybean ENOD40-2 gene. A transcriptional fusion between the ENOD40-2 promoter and the β-glucuronidase reporter gene was used in Agrobacterium rhizogenes mediated transformation of Vicia hirsuta. Root nodules were induced on the transgenic hairy roots by infection with Rhizobium leguminosarum bv. viciae and activity of the ENOD40 promoter was analysed using GUS assay.Expression of the ENOD40 gene is detectable early after infection in the pericycle of the root, before cortical cell divisions take place. It was assumed that ENOD40 expression might be required for the induction of cortical cell division, and might function by influencing auxin and/or cytokinin levels which play a role in the induction of cell division. This hypothesis was tested in a model system, the tobacco protoplast cell division assay. With this assay, the interaction of ENOD40 with auxin and cytokinin was studied, and ENOD40 was shown to induce tolerance of high auxin and cytokinin concentrations in tobacco protoplasts (chapter 4, 6). Using the tobacco protoplast cell division assay it was demonstrated that an oligopeptide of 10 to 13 amino acids encoded by ENOD40 is the compound responsible for this effect. In addition, a conserved region in the 3' UTR of ENOD40 also has an effect (chapter 4).Tobacco cells are able to respond to a soybean ENOD40 cDNA clone and to the soybean ENOD40 peptide. This indicates in tobacco homologous genes might be present. The cloning of these genes by PCR based methods is described in chapter 4 and 5. The presence and activity of ENOD40 in legumes and a non legume indicates ENOD40 might play a general role in plant development. Therefore, in the concluding remarks (chapter 7) it is discussed whether peptides can play a more common role in plant development and whether and how the 3' UTR of ENOD40 mRNA might function

Selective involvement of ERK and JNK mitogen-activated protein kinases in early rheumatoid arthritis (1987 ACR criteria compared to 2010 ACR/EULAR criteria): a prospective study aimed at identification of diagnostic and prognostic biomarkers as well as therapeutic targets

Objectives To investigate the expression and activation of mitogen-activated protein kinases in patients with early arthritis who are disease-modifying antirheumatic drug (DMARD) naive. Methods A total of 50 patients with early arthritis who were DMARD naive (disease duration <1 year) were prospectively followed and diagnosed at baseline and after 2 years for undifferentiated arthritis (UA), rheumatoid arthritis (RA) (1987 American College of Rheumatology (ACR) and 2010 ACR/European League Against Rheumatism (EULAR) criteria), or spondyloarthritis (SpA). Synovial biopsies obtained at baseline were examined for expression and phosphorylation of p38, extracellular signal regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) by immunohistochemistry and digital analysis. Synovial tissue mRNA expression was measured by quantitative PCR (qPCR). Results ERK and JNK activation was enhanced at inclusion in patients meeting RA criteria compared to other diagnoses. JNK activation was enhanced in patients diagnosed as having UA at baseline who eventually fulfilled 1987 ACR RA criteria compared to those who remained UA, and in patients with RA fulfilling 2010 ACR/EULAR criteria at baseline. ERK and JNK activation was enhanced in patients with RA developing progressive joint destruction. JNK activation in UA predicted 1987 ACR RA classification criteria fulfilment (R-2=0.59, p=0.02) after follow-up, and disease progression in early arthritis (R-2=0.16, p <0.05). Enhanced JNK activation in patients with persistent disease was associated with altered synovial expression of extracellular matrix components and CD44. Conclusions JNK activation is elevated in RA before 1987 ACR RA classification criteria are met and predicts development of erosive disease in early arthritis, suggesting JNK may represent an attractive target in treating RA early in the disease proces

Malignant Transformation of Giant Cell Tumor of Bone and the Association with Denosumab Treatment:A Radiology and Pathology Perspective

Objective. Malignancy in giant cell tumor of bone (mGCTB) is categorized as primary (concomitantly with conventional GCTB) or secondary (after radiotherapy or other treatment). Denosumab therapy has been suggested to play a role in the etiology of secondary mGCTB. In this case series from a tertiary referral sarcoma center, we aimed to find distinctive features for malignant transformation in GCTB on different imaging modalities. Furthermore, we assessed the duration of denosumab treatment and lag time to the development of malignancy. Methods. From a histopathology database search, 6 patients were pathologically confirmed as having initial conventional GCTB and subsequently with secondary mGCTB. Results. At the time of mGCTB diagnosis, 2 cases were treated with denosumab only, 2 with denosumab and surgery, 1 with multiple curettages and radiotherapy, and 1 with surgery only. In the 4 denosumab treated patients, the mean lag time to malignant transformation was 7 months (range 2-11 months). Imaging findings suspicious of malignant transformation related to denosumab therapy are the absence of fibro-osseous matrix formation and absent neocortex formation on CT, and stable or even increased size of the soft tissue component. Conclusion. In 4 patients treated with denosumab, secondary mGCTB occurred within the first year after initiation of treatment. Radiotherapy-associated mGCTB has a longer lag time than denosumab-associated mGCTB. Close clinical and imaging follow-up during the first months of denosumab therapy is key, as mGCTB tends to have rapid aggressive behavior, similar to other high-grade sarcomas. Nonresponders should be (re) evaluated for their primary diagnosis of conventional GCTB

Renormalization of Tamm-Dancoff Integral Equations

During the last few years, interest has arisen in using light-front Tamm-Dancoff field theory to describe relativistic bound states for theories such as QCD. Unfortunately, difficult renormalization problems stand in the way. We introduce a general, non-perturbative approach to renormalization that is well suited for the ultraviolet and, presumably, the infrared divergences found in these systems. We reexpress the renormalization problem in terms of a set of coupled inhomogeneous integral equations, the ``counterterm equation.'' The solution of this equation provides a kernel for the Tamm-Dancoff integral equations which generates states that are independent of any cutoffs. We also introduce a Rayleigh-Ritz approach to numerical solution of the counterterm equation. Using our approach to renormalization, we examine several ultraviolet divergent models. Finally, we use the Rayleigh-Ritz approach to find the counterterms in terms of allowed operators of a theory.Comment: 19 pages, OHSTPY-HEP-T-92-01

ImageNet Large Scale Visual Recognition Challenge

The ImageNet Large Scale Visual Recognition Challenge is a benchmark in object category classification and detection on hundreds of object categories and millions of images. The challenge has been run annually from 2010 to present, attracting participation from more than fifty institutions. This paper describes the creation of this benchmark dataset and the advances in object recognition that have been possible as a result. We discuss the challenges of collecting large-scale ground truth annotation, highlight key breakthroughs in categorical object recognition, provide a detailed analysis of the current state of the field of large-scale image classification and object detection, and compare the state-of-the-art computer vision accuracy with human accuracy. We conclude with lessons learned in the five years of the challenge, and propose future directions and improvements.Comment: 43 pages, 16 figures. v3 includes additional comparisons with PASCAL VOC (per-category comparisons in Table 3, distribution of localization difficulty in Fig 16), a list of queries used for obtaining object detection images (Appendix C), and some additional reference

Glueball calculations in large-N_c gauge theory

We use the light-front Hamiltonian of transverse lattice gauge theory to compute from first principles the glueball spectrum and light-front wavefunctions in the leading order of the 1/N_c colour expansion. We find 0^{++}, 2^{++}, and 1^{+-} glueballs having masses consistent with N_c=3 data available from Euclidean lattice path integral methods. The wavefunctions exhibit a light-front constituent gluon structure.Comment: 4 pages, 2 figures, uses macro boxedeps.tex, minor corrections in revised versio