625 research outputs found
Can invasions occur without change? A comparison of G-matrices and selection in the peach-potato aphid, Myzus persicae
Most evolutionary research on biological invasions has focused on changes seen between the native and invaded range for a particular species. However, it is likely that species that live in human-modified habitats in their native range might have evolved specific adaptations to those environments, which increase the likelihood of establishment and spread in similar human-altered environments. From a quantitative genetic perspective, this hypothesis suggests that both native and introduced populations should reside at or near the same adaptive peak. Therefore, we should observe no overall changes in the G (genetic variance–covariance) matrices between native and introduced ranges, and stabilizing selection on fitness-related traits in all populations. We tested these predictions comparing three populations of the worldwide pest Myzus persicae from the Middle East (native range) and the UK and Chile (separately introduced ranges). In general, our results provide mixed support for this idea, but further comparisons of other species are needed. In particular, we found that there has been some limited evolution in the studied traits, with the Middle East population differing from the UK and Chilean populations. This was reflected in the structure of the G-matrices, in which Chile differed from both UK and Middle East populations. Furthermore, the amount of genetic variation was massively reduced in Chile in comparison with UK and Middle East populations. Finally, we found no detectable selection on any trait in the three populations, but clones from the introduced ranges started to reproduce later, were smaller, had smaller offspring, and had lower reproductive fitness than clones from the native range
Clinical requirements for extracellular vesicle assays
The scientific and clinical interest in extracellular vesicles (EV) has grown exponentially during the past 15 years. As most research indicates that EVs can be utilised in diagnostics, prognostics and therapeutics, we may be on the brink of establishing the clinical utility of EV measurement, but how can we make this a reality? If we are to introduce EVs as biomarkers into clinical laboratories it will be necessary to offer fully validated, International Organization for Standardization (ISO) standard 15189 assays. ISO 15189 defines the quality management system requirements particular to medical laboratories and is used internationally to determine accreditation. In order for a clinical laboratory to offer an accredited test for EVs, this assay must have been subjected to a thorough assay validation process. This process requires the generation of data related to defined performance characteristics, to ensure that an assay is performing in accordance with the needs of its clinical users. Each of the defined performance characteristics will be discussed in this review, along with the issues that specifically affect EV analysis. Accreditation is increasingly important for all clinical laboratories and the standards required to achieve this are becoming more and more stringent. Therefore, as companies seek to develop the best assays to detect EVs and their molecular contents for clinical utility, and as we move rapidly towards our goal of offering EV analysis in the diagnosis and monitoring of disease, it is timely to highlight the requirements for the clinical accreditation of such assays. It is essential to consider these parameters to ensure that we develop the highest quality assays possible and ultimately the best outcomes for patients
Royal Society Scientific Meeting: Extracellular vesicles in the tumour microenvironment
Cancer cells do not grow as an isolated homogeneous mass; tumours are, in fact, complex and
heterogeneous collections of cancer and surrounding stromal cells, collectively termed the tumour
microenvironment. The interaction between cancer cells and stromal cells in the tumour
microenvironment has emerged as a key concept in the regulation of cancer progression.
Understanding the intercellular dialogue in the tumour microenvironment is therefore an important
goal. One aspect of this dialogue which has not been appreciated until recently is the role of
extracellular vesicles (EVs). EVs are small vesicles released by cells under both normal and
pathological conditions; they can transfer biological molecules between cells leading to changes in
phenotype. EVs have emerged as important regulators of biological processes and can be
dysregulated in diseases such as cancer; rapidly growing interest in their biology and therapeutic
potential led to the Royal Society hosting a Scientific Meeting to explore the roles of EVs in the
tumour microenvironment. This cross-disciplinary meeting explored examples of how aberrant
cross-talk between tumour and stromal cells can promote cancer progression, and how such
signalling can be targeted for diagnostic, prognostic and therapeutic benefit. In this review, and the special edition of Philosophical Transactions of the Royal Society B that follows, we will provide an overview of the content and outcomes of this exciting meeting
Barred Galaxies in the Coma Cluster
We use ACS data from the HST Treasury survey of the Coma cluster (z~0.02) to
study the properties of barred galaxies in the Coma core, the densest
environment in the nearby Universe. This study provides a complementary data
point for studies of barred galaxies as a function of redshift and environment.
From ~470 cluster members brighter than M_I = -11 mag, we select a sample of
46 disk galaxies (S0--Im) based on visual classification. The sample is
dominated by S0s for which we find an optical bar fraction of 47+/-11% through
ellipse fitting and visual inspection. Among the bars in the core of the Coma
cluster, we do not find any very large (a_bar > 2 kpc) bars. Comparison to
other studies reveals that while the optical bar fraction for S0s shows only a
modest variation across low-to-intermediate density environments (field to
intermediate-density clusters), it can be higher by up to a factor of ~2 in the
very high-density environment of the rich Coma cluster core.Comment: Proceedings of the Bash symposium, to appear in the Astronomical
Society of the Pacific Conference Series, eds. L. Stanford, L. Hao, Y. Mao,
J. Gree
Detecting ovarian cancer using extracellular vesicles: Progress and possibilities
Ovarian cancer (OC) is the deadliest gynecological malignancy. Most patients are diagnosed when they are already in the later stages of the disease. Earlier detection of OC dramatically improves the overall survival, but this is rarely achieved as there is a lack of clinically implemented biomarkers of early disease. Extracellular vesicles (EVs) are small cell-derived vesicles that have been extensively studied in recent years. They contribute to various aspects of cancer pathology, including tumour growth, angiogenesis and metastasis. EVs are released from all cell types and the macromolecular cargo they carry reflects the content of the cells from which they were derived. Cancer cells release EVs with altered cargo into biofluids, and so they represent an excellent potential source of novel biomarkers for the disease. In this review we describe the latest developments in EVs as potential biomarkers for earlier detection of OC. The field is still relatively young, but a number of studies have shown that EVs and the cargo they carry, including miRNAs and proteins, can be used to detect OC. They could also give insight into the stage of the disease and predict the likely therapeutic outcome. There remain a number of challenges to the use of EVs as biomarkers, but through ongoing research and innovation in this exciting field there is great potential for the development of diagnostic assays in the clinic that could improve patient outcome
Real-time gauge/gravity duality: Prescription, Renormalization and Examples
We present a comprehensive analysis of the prescription we recently put
forward for the computation of real-time correlation functions using
gauge/gravity duality. The prescription is valid for any holographic
supergravity background and it naturally maps initial and final data in the
bulk to initial and final states or density matrices in the field theory. We
show in detail how the technique of holographic renormalization can be applied
in this setting and we provide numerous illustrative examples, including the
computation of time-ordered, Wightman and retarded 2-point functions in
Poincare and global coordinates, thermal correlators and higher-point
functions.Comment: 85 pages, 13 figures; v2: added comments and reference
Modifying glycosylation for plant produced therapeutics
Modifying glycosylation for plant produced therapeutic
Monitoring the electroactive cargo of extracellular vesicles can differentiate various cancer cell lines
Extracellular vesicles (EVs) are pivotal in cell-to-cell communication due to the array of cargo contained within these vesicles. EVs are considered important biomarkers for identification of disease, however most measurement approaches have focused on monitoring specific surface macromolecular targets. Our study focuses on exploring the electroactive component present within cargo from EVs obtained from various cancer and non-cancer cell lines using a disk carbon fiber microelectrode. Variations in the presence of oxidizable components were observed when the total cargo from EVs were measured, with the highest current detected in EVs from MCF7 cells. There were differences observed in the types of oxidizable species present within EVs from MCF7 and A549 cells. Single entity measurements showed clear spikes due to the detection of oxidizable cargo within EVs from MCF7 and A549 cells. These studies highlight the promise of monitoring EVs through the presence of varying electroactive components within the cargo and can drive a wave of new strategies towards specific detection of EVs for diagnosis and prognosis of various diseases
About Bianchi I with VSL
In this paper we study how to attack, through different techniques, a perfect
fluid Bianchi I model with variable G,c and Lambda, but taking into account the
effects of a -variable into the curvature tensor. We study the model under
the assumption,div(T)=0. These tactics are: Lie groups method (LM), imposing a
particular symmetry, self-similarity (SS), matter collineations (MC) and
kinematical self-similarity (KSS). We compare both tactics since they are quite
similar (symmetry principles). We arrive to the conclusion that the LM is too
restrictive and brings us to get only the flat FRW solution. The SS, MC and KSS
approaches bring us to obtain all the quantities depending on \int c(t)dt.
Therefore, in order to study their behavior we impose some physical
restrictions like for example the condition q<0 (accelerating universe). In
this way we find that is a growing time function and Lambda is a decreasing
time function whose sing depends on the equation of state, w, while the
exponents of the scale factor must satisfy the conditions
and
, i.e. for all equation of state relaxing in this way the
Kasner conditions. The behavior of depends on two parameters, the equation
of state and a parameter that controls the behavior of
therefore may be growing or decreasing.We also show that through
the Lie method, there is no difference between to study the field equations
under the assumption of a var affecting to the curvature tensor which the
other one where it is not considered such effects.Nevertheless, it is essential
to consider such effects in the cases studied under the SS, MC, and KSS
hypotheses.Comment: 29 pages, Revtex4, Accepted for publication in Astrophysics & Space
Scienc
Cisplatin induces the release of extracellular vesicles from ovarian cancer cells that can induce invasiveness and drug resistance in bystander cells
Ovarian cancer has a poor overall survival which is partly caused by resistance to drugs such as cisplatin. Resistance can be acquired as a result of changes to the tumour or due to altered interactions within the tumour microenvironment. Extracellular vesicles (EVs), small lipid-bound vesicles that are loaded with macromolecular cargo and released by cells, are emerging as mediators of communication in the tumour microenvironment. We previously showed that EVs mediate the bystander effect, a phenomenon in which stressed cells can communicate with neighbouring naïve cells leading to various effects including DNA damage; however, the role of EVs released following cisplatin treatment has not been tested. Here we show that treatment of cells with cisplatin led to the release of EVs that could induce invasion and increased resistance when taken up by bystander cells. This coincided with changes in p38 and JNK signalling, suggesting that these pathways may be involved in mediating the effects. We also show that EV uptake inhibitors could prevent this EV-mediated adaptive response and thus sensitise cells in vitro to the effects of cisplatin. Our results suggest that preventing pro-tumourigenic EV crosstalk during chemotherapy is a potential therapeutic target for improving outcome in ovarian cancer patients
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