The Arabidopsis thaliana F-Box Protein FBL17 Is Essential for Progression through the Second Mitosis during Pollen Development

In fungi and metazoans, the SCF-type Ubiquitin protein ligases (E3s) play a critical role in cell cycle regulation by degrading negative regulators, such as cell cycle-dependent kinase inhibitors (CKIs) at the G1-to-S-phase checkpoint. Here we report that FBL17, an Arabidopsis thaliana F-box protein, is involved in cell cycle regulation during male gametogenesis. FBL17 expression is strongly enhanced in plants co-expressing E2Fa and DPa, transcription factors that promote S-phase entry. FBL17 loss-of-function mutants fail to undergo pollen mitosis II, which generates the two sperm cells in mature A. thaliana pollen. Nonetheless, the single sperm cell-like cell in fbl17 mutants is functional but will exclusively fertilize the egg cell of the female gametophyte, giving rise to an embryo that will later abort, most likely due to the lack of functional endosperm. Seed abortion can, however, be overcome by mutations in FIE, a component of the Polycomb group complex, overall resembling loss-of-function mutations in the A. thaliana cyclin-dependent kinase CDKA;1. Finally we identified ASK11, as an SKP1-like partner protein of FBL17 and discuss a possible mechanism how SCFFBL17 may regulate cell division during male gametogenesis

Hubble, trouble, toil and space rubble: The management history of an object in space

This article tells the saga of the Hubble Space Telescope, and how the attempt to overcome the restrictions Earths atmosphere imposes upon astronomy, came to dominate the existence of NASA in the later part of the 20th century.This biography of an object is told over four stages fundamental to the order of management; development, failure, recovery and completion.With a failed mirror, what became hidden and forgotten, was once more revealed.With the wild and uncertain dimension of Hubble’s assemblage disclosing itself through malfunction, management was able to rescue through repair its prior unavailability. Eventually management has contended with Hubble’s demise as it fades out of view during the process of completion. Running in counterpart to the four stages of Hubble’s life will be an explication of the events using the work of Martin Heidegger, particularly his work and concepts of Being and Time (Heidegger, 1962)

Aperçu de la pathologie animale en région Pacifique Sud. Applications à la Nouvelle-Calédonie

Energy absorption capability of structures with embedded pores depends upon the amount of voids present and their configurations/distributions. In this study, the energy absorption of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) structures with varying pore shapes and sizes are investigated. The research was performed by two teams comprised of High School/Middle School teachers and undergraduate students as part of National Science Foundation (NSF) sponsored Research Experience for Teacher (RET)/Research Experience for Undergraduates (REU) teams. ABS samples were fabricated by Team 1 and utilized cubic unit cells with octahedral pores while Team 2 fabricated PLA samples that utilized unit cells with spherical pores. Eight sets of samples with dimensions 25mm × 25mm × 20mm were fabricated using a Makerbot Replicator 2X for ABS samples and a Lulzbot TAZ 5 for PLA samples. Each sample incorporated a 5 × 5 × 4 array of pores. All the samples were tested in compression and energy absorption per unit material volume of all the samples up to a particular maximum load was calculated from load-deflection curves. It is observed that the specific energy absorption of PLA and ABS porous structures greatly increases with increased porosity. Copyright © 2017 by ASM

The NSF REU/RET Research on Energy Absorbing 3D Printed Polymer Structures

Energy absorption capability of structures with embedded pores depends upon the amount of voids present and their configurations/distributions. In this study, the energy absorption of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) structures with varying pore shapes and sizes are investigated. The research was performed by two teams comprised of High School/Middle School teachers and undergraduate students as part of National Science Foundation (NSF) sponsored Research Experience for Teacher (RET)/Research Experience for Undergraduates (REU) teams. ABS samples were fabricated by Team 1 and utilized cubic unit cells with octahedral pores while Team 2 fabricated PLA samples that utilized unit cells with spherical pores. Eight sets of samples with dimensions 25mm × 25mm × 20mm were fabricated using a Makerbot Replicator 2X for ABS samples and a Lulzbot TAZ 5 for PLA samples. Each sample incorporated a 5 × 5 × 4 array of pores. All the samples were tested in compression and energy absorption per unit material volume of all the samples up to a particular maximum load was calculated from load-deflection curves. It is observed that the specific energy absorption of PLA and ABS porous structures greatly increases with increased porosity. Copyright © 2017 by ASM

Cue1p Is an Activator of Ubc7p E2 Activity in Vitro and in Vivo*

Ubc7p is a ubiquitin-conjugating enzyme (E2) that functions with endoplasmic reticulum (ER)-resident ubiquitin ligases (E3s) to promote endoplasmic reticulum-associated degradation (ERAD). Ubc7p only functions in ERAD if bound to the ER surface by Cue1p, a membrane-anchored ER protein. The role of Cue1p was thought to involve passive concentration of Ubc7p at the surface of the ER. However, our biochemical studies of Ubc7p suggested that Cue1p may, in addition, stimulate Ubc7p E2 activity. We have tested this idea and found it to be true both in vitro and in vivo. Ubc7p bound to the soluble domain of Cue1p showed strongly enhanced in vitro ubiquitination activity, both in the presence and absence of E3. Cue1p also enhanced Ubc7p function in vivo, and this activation was separable from the established ER-anchoring role of Cue1p. Finally, we tested in vivo activation of Ubc7p by Cue1p in an assay independent of the ER membrane and ERAD. A chimeric E2 linking Ubc7p to the Cdc34p/Ubc3p localization domain complemented the cdc34-2 TS phenotype, and co-expression of the soluble Cue1p domain enhanced complementation by this chimeric Ubc7p E2. These studies reveal a previously unobserved stimulation of Ubc7p E2 activity by Cue1p that is critical for full ERAD and that functions independently of the well known Cue1p anchoring function. Moreover, it suggests a previously unappreciated mode for regulation of E2s by Cue1p-like interacting partners