109 research outputs found
Budding of an Adhesive Elastic Particle out of a Lipid Vesicle
The
problem of particle budding out of a lipid vesicle is of fundamental
importance to our understanding of the biophysical mechanisms involved
in viral budding and exocytosis. Here, we present a theoretical study
on the outward budding of an adhesive elastic particle out of a lipid
vesicle of different spontaneous curvatures. It is shown that a discontinuous
shape transformation can occur for budding out of a vesicle with positive
spontaneous curvature but not for a vesicle with zero or negative
spontaneous curvature, and that softer particles require stronger
adhesion energy to achieve full release from the vesicle. Calculations
also indicate that the adhesion energy required for full release increases
as the spontaneous curvature of the vesicle decreases. A rich variety
of budding phase diagrams accounting for the stable or metastable
states of no budding, partial budding, and full release are determined.
Endocytosis, exocytosis, intracellular budding of elastic particles
and related biological implications are discussed. Our results provide
physical insights into the biophysical mechanisms of viral budding
and exocytosis, and may also provide rational design guidelines for
controlled drug delivery systems
Incorporation of Soft Particles into Lipid Vesicles: Effects of Particle Size and Elasticity
The interaction between
particles and lipid biomembranes plays
an essential role in many fields such as endocytosis, drug delivery,
and intracellular traffic. Here we conduct a theoretical study on
the incorporation of elastic particles of different sizes and rigidities
into a lipid vesicle through adhesive wrapping. It is shown that while
the incorporation of relatively small particles involves smooth shape
evolution, the vesicle wrapping of large particles exhibits a discontinuous
shape transition, followed by a protrusion of the vesicle membrane
at infinitesimal cost of elastic deformation energy. Moreover, softer
particles require stronger adhesion energy to achieve successful internalization
and delay the onset of discontinuous shape transition to a higher
wrapping degree. Depending on the adhesion energy, particle-vesicle
size, and rigidity ratios, and the spontaneous curvature of the vesicle,
a rich variety of wrapping phase diagrams consisting of stable and
metastable states of no-wrapping, partial-wrapping, and full-wrapping
are established. The underlying mechanism of the discontinuous shape
transformation of the vesicle and the relation between the uptake
proneness and uptake efficiency are discussed. These results shed
further light on the elasticity effects in cellular uptake of elastic
particles and may provide rational design guidelines for controlled
endocytosis and diagnostics delivery
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Josephson Effect in NbS<sub>2</sub> van der Waals Junctions
van
der Waals (vdW) Josephson junctions can possibly
accelerate
the development of an advanced superconducting device that utilizes
the unique properties of two-dimensional (2D) transition metal dichalcogenide
(TMD) superconductors such as spin–orbit coupling and spin–valley
locking. Here, we fabricate vertically stacked NbS2/NbS2 Josephson junctions using a modified all-dry transfer technique
and characterize the device performance via systematic low-temperature
transport measurements. The experimental results show that the superconducting
transition temperature of the NbS2/NbS2 Josephson
junction is 5.84 K, and the critical current density reaches 3975
A/cm2 at 2 K. Moreover, we extract a superconducting energy
gap Δ = 0.58 meV, which is considerably smaller than that expected
from the single band s-wave Bardeen–Cooper–Schrieffer
(BCS) model (Δ = 0.89 meV)
Differential deposition of H2A.Z in rice seedling tissue during the day-night cycle
<p>Chromatin structure has an important role in modulating gene expression. The incorporation of histone variants into the nucleosome leads to important changes in the chromatin structure. The histone variant H2A.Z is highly conserved between different species of fungi, animals, and plants. However, dynamic changes to H2A.Z in rice have not been reported during the day-night cycle. In this study, we generated genome wide maps of H2A.Z for day and night time in harvested seedling tissues by combining chromatin immunoprecipitation and high-throughput sequencing. The analysis results for the H2A.Z data sets detected 7099 genes with higher depositions of H2A.Z in seedling tissues harvested at night compared with seedling tissues harvested during the day, whereas 4597 genes had higher H2A.Z depositions in seedlings harvested during the day. The gene expression profiles data suggested that H2A.Z probably negatively regulated gene expression during the day-night cycle and was involved in many important biologic processes. In general, our results indicated that H2A.Z may play an important role in plant responses to the diurnal oscillation process.</p
Image1.TIF
<p>The sterile insect technique (SIT) may reduce pest populations by allowing sufficient amount of irradiation-induced sterile males to mate with wild females whilst maintaining mating ability comparable to wild males. Although the SIT methods are well understood, the optimal sterilizing dose and processing development stage for application vary among species. To ensure effective pest control programs, effects of irradiation on physiology, behavior, and gene function in the target species should be defined, however, little is known about irradiation effects in Bactrocera tau. Here, the effects of irradiation on rates of fecundity, egg hatch, eclosion, mating competitiveness, flight capability, morphology of reproductive organs, and yolk protein (YP) gene expression were studied. The results showed that rates of female fecundity and egg hatch decreased significantly (51 ± 19 to 0.06 ± 0.06 and 98.90 ± 1.01 to 0, respectively) when pupae were treated with >150 Gy irradiation. Flight capability and mating competitiveness were not significantly influenced at doses <250 Gy. Ovaries and fallopian tubes became smaller after irradiation, but there was no change in testes size. Finally, we found that expression of the YP gene was up-regulated by irradiation at 30 and 45 days post-emergence, but the mechanisms were unclear. Our study provides information on the determination of the optimal irradiation sterilizing dose in B. tau, and the effects of irradiation on physiology, morphology and gene expression that will facilitate an understanding of sub-lethal impacts of the SIT and expand its use to the control of other species.</p
Image_5_Silencing of Rieske Iron-Sulfur Protein Impacts Upon the Development and Reproduction of Spodoptera exigua by Regulating ATP Synthesis.TIF
<p>Rieske iron-sulfur protein (RISP) is a key protein subunit of mitochondrial complex III which plays an important role in the respiratory electron transport chain. The complete cDNA of RISP was cloned from Spodoptera exigua by real time quantitative PCR and rapid-amplification of cDNA ends (RACE) technology and named as SeRISP (GenBank Accession Number: JN992290). Multiple alignments and the creation of a phylogenetic tree revealed that RISPs are highly conserved among different insects, and the highly conserved region of RISPs is mainly located at the C-terminal which serves as the functional domain. Expression pattern analysis demonstrated that SeRISP is expressed in all developmental stages of S. exigua; the expression levels increased during larval growth, remained stable during development from fourth instar to pupa and reached a peak in the adult. In addition, SeRISP was significantly suppressed at both the mRNA and protein levels by feeding the instar stage with dsRNA; levels of suppression increased with increasing dsRNA concentration and continuous treatment time. The silencing of SeRISP in larvae led to the significant inhibition of ATP synthesis and larval growth, which could result in energy reserve deficiency in pupae and the suppression of fecundity and hatchability in adults. Our findings confirmed that it is possible to silence target genes in S. exigua by simple dsRNA feeding, and provided evidence of the essential role of RISP in the process of ATP synthesis, growth and reproduction.</p
Table_1_Silencing of Rieske Iron-Sulfur Protein Impacts Upon the Development and Reproduction of Spodoptera exigua by Regulating ATP Synthesis.docx
<p>Rieske iron-sulfur protein (RISP) is a key protein subunit of mitochondrial complex III which plays an important role in the respiratory electron transport chain. The complete cDNA of RISP was cloned from Spodoptera exigua by real time quantitative PCR and rapid-amplification of cDNA ends (RACE) technology and named as SeRISP (GenBank Accession Number: JN992290). Multiple alignments and the creation of a phylogenetic tree revealed that RISPs are highly conserved among different insects, and the highly conserved region of RISPs is mainly located at the C-terminal which serves as the functional domain. Expression pattern analysis demonstrated that SeRISP is expressed in all developmental stages of S. exigua; the expression levels increased during larval growth, remained stable during development from fourth instar to pupa and reached a peak in the adult. In addition, SeRISP was significantly suppressed at both the mRNA and protein levels by feeding the instar stage with dsRNA; levels of suppression increased with increasing dsRNA concentration and continuous treatment time. The silencing of SeRISP in larvae led to the significant inhibition of ATP synthesis and larval growth, which could result in energy reserve deficiency in pupae and the suppression of fecundity and hatchability in adults. Our findings confirmed that it is possible to silence target genes in S. exigua by simple dsRNA feeding, and provided evidence of the essential role of RISP in the process of ATP synthesis, growth and reproduction.</p
Image_4_Silencing of Rieske Iron-Sulfur Protein Impacts Upon the Development and Reproduction of Spodoptera exigua by Regulating ATP Synthesis.TIF
<p>Rieske iron-sulfur protein (RISP) is a key protein subunit of mitochondrial complex III which plays an important role in the respiratory electron transport chain. The complete cDNA of RISP was cloned from Spodoptera exigua by real time quantitative PCR and rapid-amplification of cDNA ends (RACE) technology and named as SeRISP (GenBank Accession Number: JN992290). Multiple alignments and the creation of a phylogenetic tree revealed that RISPs are highly conserved among different insects, and the highly conserved region of RISPs is mainly located at the C-terminal which serves as the functional domain. Expression pattern analysis demonstrated that SeRISP is expressed in all developmental stages of S. exigua; the expression levels increased during larval growth, remained stable during development from fourth instar to pupa and reached a peak in the adult. In addition, SeRISP was significantly suppressed at both the mRNA and protein levels by feeding the instar stage with dsRNA; levels of suppression increased with increasing dsRNA concentration and continuous treatment time. The silencing of SeRISP in larvae led to the significant inhibition of ATP synthesis and larval growth, which could result in energy reserve deficiency in pupae and the suppression of fecundity and hatchability in adults. Our findings confirmed that it is possible to silence target genes in S. exigua by simple dsRNA feeding, and provided evidence of the essential role of RISP in the process of ATP synthesis, growth and reproduction.</p
Image_1_Silencing of Rieske Iron-Sulfur Protein Impacts Upon the Development and Reproduction of Spodoptera exigua by Regulating ATP Synthesis.TIF
<p>Rieske iron-sulfur protein (RISP) is a key protein subunit of mitochondrial complex III which plays an important role in the respiratory electron transport chain. The complete cDNA of RISP was cloned from Spodoptera exigua by real time quantitative PCR and rapid-amplification of cDNA ends (RACE) technology and named as SeRISP (GenBank Accession Number: JN992290). Multiple alignments and the creation of a phylogenetic tree revealed that RISPs are highly conserved among different insects, and the highly conserved region of RISPs is mainly located at the C-terminal which serves as the functional domain. Expression pattern analysis demonstrated that SeRISP is expressed in all developmental stages of S. exigua; the expression levels increased during larval growth, remained stable during development from fourth instar to pupa and reached a peak in the adult. In addition, SeRISP was significantly suppressed at both the mRNA and protein levels by feeding the instar stage with dsRNA; levels of suppression increased with increasing dsRNA concentration and continuous treatment time. The silencing of SeRISP in larvae led to the significant inhibition of ATP synthesis and larval growth, which could result in energy reserve deficiency in pupae and the suppression of fecundity and hatchability in adults. Our findings confirmed that it is possible to silence target genes in S. exigua by simple dsRNA feeding, and provided evidence of the essential role of RISP in the process of ATP synthesis, growth and reproduction.</p
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