Determination of the functional role of Rab-GGT in Physcomitrium patens.

Protein prenylation, a common lipid post-translational modification, is required for growth and development in eukaryotes. Rab geranylgeranylation involves the addition of one or two 20-carbon geranylgeranyl moieties to Rab-GTPase target proteins, which regulate intracellular vesicle trafficking. The reaction is carried out by heterodimeric Rab geranylgeranyltransferase (Rab-GGT), which is composed of two associated α- and β-subunits, with the assistance of an additional protein called Rab escort protein (REP). Loss of function of the Rab-GGT α subunit RGTA1 has not been reported in any plant. While knockout of either of the two β subunits RGTB1 or RGTB2 results in no phenotype in the moss Physcomitrium patens (P. patens, formerly Physcomitrella patens), in the flowering plant Arabidopsis thaliana, knockout of RGTB1 results in loss of apical dominance and photomorphogenic and gravitropic defects, and knockout of RGTB2 results in a subtle growth defect in certain cells. These results showed that both Rab-GGT β subunits in P. patens are redundant, but RGTB2 in Arabidopsis could not fully compensate for the loss of function of RGTB1 and vice versa. Previous studies in our lab showed that complete knockout of any P. patens Rab-GGT components (RGTA1, RGTB1 & RGTB2, REP) appears to be lethal, since no viable single mutant plants of RGTA1 or REP and double mutant plants of RGTB1 and RGTB2 were recovered. Therefore, the biological function of Rab-GGT remains largely unknown. Here we have generated P. patens transgenic plants containing artificial miRNA constructs targeting each Rab-GGT component by an inducible knockdown system, and systematically analyzed the phenotypes upon induction. The results showed that knockdown of either RGTA1 or REP, or knockdown of RGTB1 in a rgtb2 knockout background (or vice versa) resulted in defects in tip growth (polar cell elongation), reduced or incomplete caulonema differentiation, and an altered response towards exogenous phytohormones. This dissertation may help to elucidate the functional role of Rab-GGT in P. patens, as well as provide fundamental insights into key P. patens developmental processes and environmental responses

Current-Induced Resonant Motion of a Magnetic Vortex Core: Effect of Nonadiabatic Spin Torque

The current-induced resonant excitation of a magnetic vortex core is investigated by means of analytical and micromagnetic calculations. We find that the radius and the phase shift of the resonant motion are not correctly described by the analytical equations because of the dynamic distortion of a vortex core. In contrast, the initial tilting angle of a vortex core is free from the distortion and determined by the nonadiabaticity of the spin torque. It is insensitive to experimentally uncontrollable current-induced in-plane Oersted field. We propose that a time-resolved imaging of the very initial trajectory of a core is essential to experimentally estimate the nonadiabaticity.Comment: 4 pages, 4 figure

Quantitative Screening of Cervical Cancers for Low-Resource Settings: Pilot Study of Smartphone-Based Endoscopic Visual Inspection After Acetic Acid Using Machine Learning Techniques

Background: Approximately 90% of global cervical cancer (CC) is mostly found in low- and middle-income countries. In most cases, CC can be detected early through routine screening programs, including a cytology-based test. However, it is logistically difficult to offer this program in low-resource settings due to limited resources and infrastructure, and few trained experts. A visual inspection following the application of acetic acid (VIA) has been widely promoted and is routinely recommended as a viable form of CC screening in resource-constrained countries. Digital images of the cervix have been acquired during VIA procedure with better quality assurance and visualization, leading to higher diagnostic accuracy and reduction of the variability of detection rate. However, a colposcope is bulky, expensive, electricity-dependent, and needs routine maintenance, and to confirm the grade of abnormality through its images, a specialist must be present. Recently, smartphone-based imaging systems have made a significant impact on the practice of medicine by offering a cost-effective, rapid, and noninvasive method of evaluation. Furthermore, computer-aided analyses, including image processing-based methods and machine learning techniques, have also shown great potential for a high impact on medicinal evaluations

Anti-aging activities of Pyrus pyrifolia var culta plant callus extract

Purpose: To investigate the anti-aging properties of callus extract from Pyrus pyrifolia var. culta with skin regeneration and lightening activities.Methods: Callus extract of P. pyrifolia var. culta was produced on Murashige and Skoog (MS) medium supplemented with picloram, followed by extraction of the callus biomass in phosphate-buffered saline. The anti-oxidant activity of the extract was assessed using the DPPH free radical-scavenging assay. Inhibition of skin pigmentation by callus extract was evaluated by measuring the melanogenesis of melanoma cells. The skin-regenerating efficacy of the extract was evaluated in terms of its ability to promote procollagen synthesis and fibroblast cell proliferation.Results: The callus extract, at 10 mg/mL, exhibited 78.7 % free radical-scavenging activity, equivalent to that exhibited by 500 μM ascorbic acid. The 1 mg/mL extract solution afforded a 1.4-fold greater reduction in melanocyte melanin than did a 1 mg/mL arbutin solution. Fibroblast cells treated with 5 mg/mL callus extract exhibited 127 % higher levels of proliferation and 2.0-fold higher levels of procollagen type I C-peptide synthesis, respectively, compared with the untreated controls.Conclusion: These findings suggest that the callus extract of P. pyrifolia var. culta may be useful as a source of anti-aging cosmetic components with skin lightening and regenerating activities.Keywords: P. pyrifolia var. culta, Anti-aging, Callus extract, Skin lightening, Anti-tyrosinase activity, Melanogenesis, Wound recovery, Procollagen type I C-peptide synthesi

Leptogenesis driven by majoron

We propose a leptogenesis scenario where baryon asymmetry generation is assisted by the kinetic motion of the majoron, $J$, in the process of lepton-number violating inverse decays of a right-handed neutrino, $N$. We investigate two distinct scenarios depending on the sources of majoron kinetic motion: 1) the misalignment mechanism, and 2) the kinetic misalignment mechanism. The former case can naturally generate the observed baryon asymmetry for the majoron mass $m_J \gtrsim \,{\rm TeV}$ and the right-handed neutrino's mass $M_{N} \gtrsim 10^{11}\,{\rm GeV}$. However, an additional decay channel of the majoron is required to avoid the overclosure problem of the majoron oscillation. The later scenario works successfully for $m_J \lesssim 100\,{\rm keV}$, and $M_{N} \lesssim 10^9\,{\rm GeV}$ while $M_N$ can be even far below the temperature of the electroweak phase transition as long as sufficiently large kinetic misalignment is provided. We also find that a sub-$100\,{\rm keV}$ majoron is a viable candidate for dark matter.Comment: 10 pages, 4 figure

Bootstrap-based Support of HGT Inferred by Maximum Parsimony

Background: Maximum parsimony is one of the most commonly used criteria for reconstructing phylogenetic trees. Recently, Nakhleh and co-workers extended this criterion to enable reconstruction of phylogenetic networks, and demonstrated its application to detecting reticulate evolutionary relationships. However, one of the major problems with this extension has been that it favors more complex evolutionary relationships over simpler ones, thus having the potential for overestimating the amount of reticulation in the data. An ad hoc solution to this problem that has been used entails inspecting the improvement in the parsimony length as more reticulation events are added to the model, and stopping when the improvement is below a certain threshold. Results: In this paper, we address this problem in a more systematic way, by proposing a nonparametric bootstrapbased measure of support of inferred reticulation events, and using it to determine the number of those events, as well as their placements. A number of samples is generated from the given sequence alignment, and reticulation events are inferred based on each sample. Finally, the support of each reticulation event is quantified based on the inferences made over all samples. Conclusions: We have implemented our method in the NEPAL software tool (available publicly a