2,280 research outputs found
Rosmarinic acid production in cell suspension cultures of Ehretia asperula Zollinger & Moritz
Plant cell cultures provide an alternative means for producing secondary compounds in food, cosmetic and pharmaceutical industries. Ehretia asperula Zollinger & Moritzi is used as a traditional medicine for the treatment of liver detoxification, ulcers, tumors, inflammation and enhancing the body's resistance in Vietnam. The study was carried out to select suitable callus line for cell suspension cultures of E. asperula Zollinger & Moritzi and investigate the effects of inoculum size, rotation speed and naphthalene acetic acid (NAA) on the proliferation of cell suspension cultures. In addition, the influence of light intensity on the growth and rosmarinic acid (RA) biosynthesis of cell suspension was also surveyed. After 4 weeks of culture, the white to pale yellow friable callus expanded significantly with a fresh weight (FW) of 0.788 g and a high RA content of 2.062 mg/g FW. An appropriate medium for cell proliferation was the liquid B5 medium, which contained 30 g/l glucose, 0.1 mg/l benzyl adenine (BA) and 0.4 mg/l NAA. The results also demonstrated that a 1:20 ratio (w/v) inoculum size, darkness and rotation speed of 90 rpm were the optimal conditions for the proliferation and RA accumulation to 188.217 mg/l in 4 weeks of culture. These findings showed that E. asperula Zollinger & Moritzi cell suspension cultures could be a potential alternative approach for RA production in vitro
Acceleration of generalized hypergeometric functions through precise remainder asymptotics
We express the asymptotics of the remainders of the partial sums {s_n} of the
generalized hypergeometric function q+1_F_q through an inverse power series z^n
n^l \sum_k c_k/n^k, where the exponent l and the asymptotic coefficients {c_k}
may be recursively computed to any desired order from the hypergeometric
parameters and argument. From this we derive a new series acceleration
technique that can be applied to any such function, even with complex
parameters and at the branch point z=1. For moderate parameters (up to
approximately ten) a C implementation at fixed precision is very effective at
computing these functions; for larger parameters an implementation in higher
than machine precision would be needed. Even for larger parameters, however,
our C implementation is able to correctly determine whether or not it has
converged; and when it converges, its estimate of its error is accurate.Comment: 36 pages, 6 figures, LaTeX2e. Fixed sign error in Eq. (2.28), added
several references, added comparison to other methods, and added discussion
of recursion stabilit
Study to Fabricate the Large Scale Buckypaper Based on Carbon Nanotubes
Carbon nanotubes (CNTs) have attracted great attention because of their unique structural, electrical, mechanical and thermal properties. Then CNTs have potential application as electrode for batteries and supercapacitors, especially binder-free electrodes. The major challenge is to fabricate the large scale electrode with the uniform thickness, electrical property. The large scale CNTs buckypaper can be fabricated via vacuum filtration technique. The characteristics of CNT dispersion and buckypaper depend on variety of factor such as sonication power, sonication time, dispersantβ¦. In this study, we investigate the multiwall carbon nanotubes (MW CNTs) in Isopropanol (IPA) solvent with different sonication conditions, membrane filter size for paper with areal density of 3 mg/cm2 with different sizes such as 4, 10, 20 cm in diameter and large scale of 30x30 cm2. It is observed that the dispersion of CNTs are good and the thickness, conductivity are uniform over whole sample for above sizes. We also can get the highest conductivity of buckypaper was 3.9x103 S/m in 30 mins. It is found that the higher sonication power and higher sonication time are better for buckypaper
Effect of time and temperature on the survival rate of mouse sperm (Mus musculus var. Albino) in short-term preservation without cryoprotectant agents
In this study, we studied the use of physiological saline solution (NaCl 0,9%) or dulbeccoβs phosphatebuffered saline (D-PBS) for mature sperms short-term preservation. After being collected from epididymides, sperms were adjusted to desired concentration (2x106 sperms/ml) with NaCl 0.9% solution or D-PBS solution (the dishes containing sperms were covered by mineral oil) and stored at 4oC, iooC and room temperature (RT/26oC
Mutational signature dynamics indicate SARS-CoV-2's evolutionary capacity is driven by host antiviral molecules
The COVID-19 pandemic has been characterised by sequential variant-specific waves shaped by viral, individual human and population factors. SARS-CoV-2 variants are defined by their unique combinations of mutations and there has been a clear adaptation to more efficient human infection since the emergence of this new human coronavirus in late 2019. Here, we use machine learning models to identify shared signatures, i.e., common underlying mutational processes and link these to the subset of mutations that define the variants of concern (VOCs). First, we examined the global SARS-CoV-2 genomes and associated metadata to determine how viral properties and public health measures have influenced the magnitude of waves, as measured by the number of infection cases, in different geographic locations using regression models. This analysis showed that, as expected, both public health measures and virus properties were associated with the waves of regional SARS-CoV-2 reported infection numbers and this impact varies geographically. We attribute this to intrinsic differences such as vaccine coverage, testing and sequencing capacity and the effectiveness of government stringency. To assess underlying evolutionary change, we used non-negative matrix factorisation and observed three distinct mutational signatures, unique in their substitution patterns and exposures from the SARS-CoV-2 genomes. Signatures 1, 2 and 3 were biased to CβT, TβC/AβG and GβT point mutations. We hypothesise assignments of these mutational signatures to the host antiviral molecules APOBEC, ADAR and ROS respectively. We observe a shift amidst the pandemic in relative mutational signature activity from predominantly Signature 1 changes to an increasingly high proportion of changes consistent with Signature 2. This could represent changes in how the virus and the host immune response interact and indicates how SARS-CoV-2 may continue to generate variation in the future. Linkage of the detected mutational signatures to the VOC-defining amino acids substitutions indicates the majority of SARS-CoV-2's evolutionary capacity is likely to be associated with the action of host antiviral molecules rather than virus replication errors
Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity
Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana-exposed to more than a decade of regular ivermectin treatment-have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread.Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR.This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations
A pivotal role for starch in the reconfiguration of 14C-partitioning and allocation in Arabidopsis thaliana under short-term abiotic stress.
Plant carbon status is optimized for normal growth but is affected by abiotic stress. Here, we used 14C-labeling to provide the first holistic picture of carbon use changes during short-term osmotic, salinity, and cold stress in Arabidopsis thaliana. This could inform on the early mechanisms plants use to survive adverse environment, which is important for efficient agricultural production. We found that carbon allocation from source to sinks, and partitioning into major metabolite pools in the source leaf, sink leaves and roots showed both conserved and divergent responses to the stresses examined. Carbohydrates changed under all abiotic stresses applied; plants re-partitioned 14C to maintain sugar levels under stress, primarily by reducing 14C into the storage compounds in the source leaf, and decreasing 14C into the pools used for growth processes in the roots. Salinity and cold increased 14C-flux into protein, but as the stress progressed, protein degradation increased to produce amino acids, presumably for osmoprotection. Our work also emphasized that stress regulated the carbon channeled into starch, and its metabolic turnover. These stress-induced changes in starch metabolism and sugar export in the source were partly accompanied by transcriptional alteration in the T6P/SnRK1 regulatory pathway that are normally activated by carbon starvation
Balancing Selection at the Tomato RCR3 Guardee Gene Family Maintains Variation in Strength of Pathogen Defense
Coevolution between hosts and pathogens is thought to occur between interacting molecules of both species. This results in the maintenance of genetic diversity at pathogen antigens (or so-called effectors) and host resistance genes such as the major histocompatibility complex (MHC) in mammals or resistance (R) genes in plants. In plant-pathogen interactions, the current paradigm posits that a specific defense response is activated upon recognition of pathogen effectors via interaction with their corresponding R proteins. According to the''Guard-Hypothesis,'' R proteins (the ``guards'') can sense modification of target molecules in the host (the ``guardees'') by pathogen effectors and subsequently trigger the defense response. Multiple studies have reported high genetic diversity at R genes maintained by balancing selection. In contrast, little is known about the evolutionary mechanisms shaping the guardee, which may be subject to contrasting evolutionary forces. Here we show that the evolution of the guardee RCR3 is characterized by gene duplication, frequent gene conversion, and balancing selection in the wild tomato species Solanum peruvianum. Investigating the functional characteristics of 54 natural variants through in vitro and in planta assays, we detected differences in recognition of the pathogen effector through interaction with the guardee, as well as substantial variation in the strength of the defense response. This variation is maintained by balancing selection at each copy of the RCR3 gene. Our analyses pinpoint three amino acid polymorphisms with key functional consequences for the coevolution between the guardee (RCR3) and its guard (Cf-2). We conclude that, in addition to coevolution at the ``guardee-effector'' interface for pathogen recognition, natural selection acts on the ``guard-guardee'' interface. Guardee evolution may be governed by a counterbalance between improved activation in the presence and prevention of auto-immune responses in the absence of the corresponding pathogen
Ateriovenous subclavia-shunt for head and neck reconstruction
Reconstruction of the facial hard- and soft tissues is of special concern for the rehabilitation of patients especially after ablative tumor surgery has been performed. Impaired soft and hard tissue conditions as a sequelae of extensive surgical resection and/or radiotherapy may impede common reconstruction methodes. Even free flaps may not be used without interposition of a vein graft as recipient vessels are not available as a consequence of radical neck dissection
Determining the neurotransmitter concentration profile at active synapses
Establishing the temporal and concentration profiles of neurotransmitters during synaptic release is an essential step towards understanding the basic properties of inter-neuronal communication in the central nervous system. A variety of ingenious attempts has been made to gain insights into this process, but the general inaccessibility of central synapses, intrinsic limitations of the techniques used, and natural variety of different synaptic environments have hindered a comprehensive description of this fundamental phenomenon. Here, we describe a number of experimental and theoretical findings that has been instrumental for advancing our knowledge of various features of neurotransmitter release, as well as newly developed tools that could overcome some limits of traditional pharmacological approaches and bring new impetus to the description of the complex mechanisms of synaptic transmission
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