29 research outputs found
The photometric observation of the quasi-simultaneous mutual eclipse and occultation between Europa and Ganymede on 22 August 2021
Mutual events (MEs) are eclipses and occultations among planetary natural
satellites. Most of the time, eclipses and occultations occur separately.
However, the same satellite pair will exhibit an eclipse and an occultation
quasi-simultaneously under particular orbital configurations. This kind of rare
event is termed as a quasi-simultaneous mutual event (QSME). During the 2021
campaign of mutual events of jovian satellites, we observed a QSME between
Europa and Ganymede. The present study aims to describe and study the event in
detail. We observed the QSME with a CCD camera attached to a 300-mm telescope
at the Hong Kong Space Museum Sai Kung iObservatory. We obtained the combined
flux of Europa and Ganymede from aperture photometry. A geometric model was
developed to explain the light curve observed. Our results are compared with
theoretical predictions (O-C). We found that our simple geometric model can
explain the QSME fairly accurately, and the QSME light curve is a superposition
of the light curves of an eclipse and an occultation. Notably, the observed
flux drops are within 2.6% of the theoretical predictions. The size of the
event central time O-Cs ranges from -14.4 to 43.2 s. Both O-Cs of flux drop and
timing are comparable to other studies adopting more complicated models. Given
the event rarity, model simplicity and accuracy, we encourage more observations
and analysis on QSMEs to improve Solar System ephemerides.Comment: 23 pages, 5 appendixes, 16 figures, 7 table
Emerging role of fatty acid binding proteins in cancer pathogenesis
Fatty acid binding proteins (FABPs) are 15-
kDa proteins responsible for the transport of fatty acids
both intracellularly and extracellularly. Consisting of 12
different isoforms, some of the proteins have been found
to be released in the serum and to be correlated with
various diseases including cancer. Differential
expression of these proteins has been reported to result
in cancer pathogenesis by modulating various cancer
signaling pathways; hence, in this review, we present the
recent studies that have investigated the roles of different
kinds of FABPs in different types of cancer and any
possible underlying mechanisms to better understand the
role of FABPs in cancer progression
Transformation and Characterization of Δ12-Fatty Acid Acetylenase and Δ12-Oleate Desaturase Potentially Involved in the Polyacetylene Biosynthetic Pathway from Bidens pilosa
Bidens pilosa is commonly used as an herbal tea component or traditional medicine for treating several diseases, including diabetes. Polyacetylenes have two or more carbon–carbon triple bonds or alkynyl functional groups and are mainly derived from fatty acid and polyketide precursors. Here, we report the cloning of full-length cDNAs that encode Δ12-fatty acid acetylenase (designated BPFAA) and Δ12-oleate desaturase (designated BPOD) from B. pilosa, which we predicted to play a role in the polyacetylene biosynthetic pathway. Subsequently, expression vectors carrying BPFAA or BPOD were constructed and transformed into B. pilosa via the Agrobacterium-mediated method. Genomic PCR analysis confirmed the presence of transgenes and selection marker genes in the obtained transgenic lines. The copy numbers of transgenes in transgenic lines were determined by Southern blot analysis. Furthermore, 4–5 FAA genes and 2–3 OD genes were detected in wild-type (WT) plants. Quantitative real time-PCR revealed that some transgenic lines had higher expression levels than WT. Western blot analysis revealed OD protein expression in the selected transformants. High-performance liquid chromatography profiling was used to analyze the seven index polyacetylenic compounds, and fluctuation patterns were found
Induction of Angiogenesis in Zebrafish Embryos and Proliferation of Endothelial Cells by an Active Fraction Isolated from the Root of Astragalus membranaceus using Bioassay-guided Fractionation
The objective of the study was to identify the active fraction(s) from AR aqueous extract responsible for promoting angiogenesis using bioassay-guided fractionation. The angiogenic activity was screened by monitoring the increase of sprout number in sub-intestinal vessel (SIV) of the transgenic zebrafish embryos after they were treated with 0.06-0.25 mg/ml of AR aqueous extract or its fraction(s) for 96 h. Furthermore, the angiogenic effect was evaluated in treated zebrafish embryos by measuring the gene expression of angiogenic markers (VEGFA, KDR, and Flt-1) using real-time polymerase chain reaction (RT-PCR), and in human microvascular endothelial cell (HMEC-1) by measuring cell proliferation using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 3H-thymidine uptake assay, and cell cycle analysis. A major active fraction (P1-1-1), which was identified as glycoproteins, was found to significantly stimulate sprout formation (2.03±0.27) at 0.125 mg/ml (P<0.001) and up-regulate the gene expression of VEGFA, KDR, and Flt-1 by 2.6-fold to 8.2-fold. Additionally, 0.031-0.125 mg/ml of P1-1-1 was demonstrated to significantly stimulate cell proliferation by increasing cell viability (from 180% to 205%), 3H-thymidine incorporation (from 126% to 133%) during DNA synthesis, and the shift of cell population to S phase of cell cycle. A major AR active fraction consisting of glycoproteins was identified, and shown to promote angiogenesis in zebrafish embryos and proliferation of endothelial cells in vitro