146 research outputs found
Optimization of embryogenic-callus induction and embryogenesis of Glycyrrhiza glabra
Glabridin is a major biologically active flavonoid isolated specifically from the root of Glycyrrhiza glabra, which has many pharmacological activities. The production of the wild G. glabra was sharply decreased due to immoderate and ruinous utilization. In vitro regeneration via somatic embryogenesis is important for clonal propagation and genetic transformation. In this paper, factors affecting the embryogenic calli and embryo induction, maintenance and multiplication of G. glabra are assessed. The results showed that the explants of hypocotyl give the highest calli formation frequency of 93.3% on Murashige and Skoog (MS) medium containing 2.0 mg/L 6-benzylaminopurine (6-BA) and 0.5 mg/L 2,4- dichlorophenoxyacetic acid (2,4-D). The maximum efficiency of embryo were obtained on MS medium with 0.5 mg/L 6-BA + 0.5 mg/L kinetin zeatin (KT) + 0.1 mg/L indole-3-butyric acid (IBA); the embryos could develop further on medium with 1000 mg/L malt extract (ME). The occurrence of the embryogenic calli and proglobular embryo were studied by histological section, indicating the single cell origin of the embryogensis of G. glabra. With the protocol reported herein, some green embryo-like cultures were obtained, from which shoots were successfully regenerated in the germinated medium after 10 months of subculture.Keywords: Glycyrrhiza glabra L., callus induction, embryogenesis, cell culture, histological sectionAfrican Journal of Biotechnology Vol. 9(36), pp. 5823-5829, 6 September, 201
Characterization of Small Interfering RNAs Derived from the Geminivirus/Betasatellite Complex Using Deep Sequencing
BACKGROUND: Small RNA (sRNA)-guided RNA silencing is a critical antiviral defense mechanism employed by a variety of eukaryotic organisms. Although the induction of RNA silencing by bipartite and monopartite begomoviruses has been described in plants, the nature of begomovirus/betasatellite complexes remains undefined. METHODOLOGY/PRINCIPAL FINDINGS: Solanum lycopersicum plant leaves systemically infected with Tomato yellow leaf curl China virus (TYLCCNV) alone or together with its associated betasatellite (TYLCCNB), and Nicotiana benthamiana plant leaves systemically infected with TYLCCNV alone, or together with TYLCCNB or with mutant TYLCCNB were harvested for RNA extraction; sRNA cDNA libraries were then constructed and submitted to Solexa-based deep sequencing. Both sense and anti-sense TYLCCNV and TYLCCNB-derived sRNAs (V-sRNAs and S-sRNAs) accumulated preferentially as 22 nucleotide species in infected S. lycopersicum and N. benthamiana plants. High resolution mapping of V-sRNAs and S-sRNAs revealed heterogeneous distribution of V-sRNA and S-sRNA sequences across the TYLCCNV and TYLCCNB genomes. In TYLCCNV-infected S. lycopersicum or N. benthamiana and TYLCCNV and Ξ²C1-mutant TYLCCNB co-infected N. benthamiana plants, the primary TYLCCNV targets were AV2 and the 5' terminus of AV1. In TYLCCNV and betasatellite-infected plants, the number of V-sRNAs targeting this region decreased and the production of V-sRNAs increased corresponding to the overlapping regions of AC2 and AC3, as well as the 3' terminal of AC1. Ξ²C1 is the primary determinant mediating symptom induction and also the primary silencing target of the TYLCCNB genome even in its mutated form. CONCLUSIONS/SIGNIFICANCE: We report the first high-resolution sRNA map for a monopartite begomovirus and its associated betasatellite using Solexa-based deep sequencing. Our results suggest that viral transcript might act as RDR substrates resulting in dsRNA and secondary siRNA production. In addition, the betasatellite affected the amount of V-sRNAs detected in S. lycopersicum and N. benthamiana plants
Amorphous photonic topological insulator
Photonic topological insulators (PTIs) exhibit robust photonic edge states
protected by band topology, similar to electronic edge states in topological
band insulators. Standard band theory does not apply to amorphous phases of
matter, which are formed by non-crystalline lattices with no long-range
positional order but only short-range order. Among other interesting
properties, amorphous media exhibit transitions between glassy and liquid
phases, accompanied by dramatic changes in short-range order. Here, we
experimentally investigate amorphous variants of a Chern-number-based PTI. By
tuning the disorder strength in the lattice, we demonstrate that photonic
topological edge states can persist into the amorphous regime, prior to the
glass-to-liquid transition. After the transition to a liquid-like lattice
configuration, the signatures of topological edge states disappear. This
interplay between topology and short-range order in amorphous lattices paves
the way for new classes of non-crystalline topological photonic materials.Comment: 13 pages, 4 figure
Observation of photonic antichiral edge states
Chiral edge states are a hallmark feature of two-dimensional topological
materials. Such states must propagate along the edges of the bulk either
clockwise or counterclockwise, and thus produce oppositely propagating edge
states along the two parallel edges of a strip sample. However, recent theories
have predicted a counterintuitive picture, where the two edge states at the two
parallel strip edges can propagate in the same direction; these anomalous
topological edge states are named as antichiral edge states. Here we report the
experimental observation of antichiral edge states in a gyromagnetic photonic
crystal. The crystal consists of gyromagnetic cylinders in a honeycomb lattice,
with the two triangular sublattices magnetically biased in opposite directions.
With microwave measurement, unique properties of antichiral edge states have
been observed directly, which include the titled dispersion, the chiral-like
robust propagation in samples with certain shapes, and the scattering into
backward bulk states at certain terminations. These results extend and
supplement the current understanding of chiral edge states
Epitaxial growth of high quality thin films by pulsed laser deposition
Non-collinear antiferromagnet Weyl semimetal have attracted great
research interest recently. Although large anomalous Hall effect, anomalous
Nernst effect and magneto-optical effect have been observed in , most
studies are based on single crystals. So far, it is still challenging to grow
high quality epitaxial thin films with transport and optical
properties comparable to their single crystal counterparts. Here, we report the
structure, magneto-optical and transport properties of epitaxial thin
films fabricated by pulsed laser deposition (PLD). Highly oriented
(0001) and (110) epitaxial films are successfully
growth on single crystalline and MgO substrates. Large anomalous Hall
effect (AHE) up to =3.02 , and
longitudinal magneto-optical Kerr effect (LMOKE) with = 38.1 mdeg at
633 nm wavelength are measured at 300 K temperature, which are comparable to
single crystals. Our work demonstrates that high quality
epitaxial thin films can be fabricated by PLD, paving the way for future device
applications
Arctic-Wide Sea Ice Thickness Estimates From Combining Satellite Remote Sensing Data and a Dynamic Ice-Ocean Model with Data Assimilation During the CryoSat-2 Period
Exploiting the complementary character of CryoSat-2 and Soil Moisture and Ocean Salinity
satellite sea ice thickness products, daily Arctic sea ice thickness estimates from October 2010 to December
2016 are generated by an Arctic regional ice-ocean model with satellite thickness assimilated. The
assimilation is performed by a Local Error Subspace Transform Kalman filter coded in the Parallel Data
Assimilation Framework. The new estimates can be generally thought of as combined model and satellite
thickness (CMST). It combines the skill of satellite thickness assimilation in the freezing season with the
model skill in the melting season, when neither CryoSat-2 nor Soil Moisture and Ocean Salinity sea ice
thickness is available. Comparisons with in situ observations from the Beaufort Gyre Exploration Project,
Ice Mass Balance Buoys, and the NASA Operation IceBridge demonstrate that CMST reproduces most of the
observed temporal and spatial variations. Results also show that CMST compares favorably to the Pan-Arctic
Ice-Ocean Modeling and Assimilation System product and even appears to correct known thickness biases
in the Pan-Arctic Ice-Ocean Modeling and Assimilation System. Due to imperfect parameterizations in the
sea ice model and satellite thickness retrievals, CMST does not reproduce the heavily deformed and ridged
sea ice along the northern coast of the Canadian Arctic Archipelago and Greenland. With the new Arctic sea
ice thickness estimates sea ice volume changes in recent years can be further assessed
Unprecedented Arctic sea ice thickness loss and multiyear-ice volume export through Fram Strait during 2010-2011
The satellite-observed sea ice thickness records from 2003 to 2020 identify an extreme sea ice thickness loss during 2010β2011. Ice thickness budget analysis demonstrates that the thickness loss was associated with an extraordinarily large multiyear ice volume export through the Fram Strait during the season of sea ice advance. High cloudiness led to positive anomalies of net longwave radiation, and positive net surface energy flux anomalies supported enhanced sea ice melt from June to August. Due to the multiyear ice loss, the Arctic sea ice became more sensitive to subsequent atmospheric anomalies. The reduced surface albedo triggering a positive ice-albedo amplifying feedback and contributed to the accelerating loss of ice thickness. These tightly coupled events highlight that the increasingly younger and thinner Arctic sea ice is becoming more vulnerable to external forcing and created the precondition for the rapid reduction in sea ice extent in 2012
A diverse set of miRNAs responsive to begomovirus-associated betasatellite in Nicotiana benthamiana
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