3,206 research outputs found
The brainstem reticular formation is a small-world, not scale-free, network
Recently, it has been demonstrated that several complex systems may have simple graph-theoretic characterizations as so-called âsmall-worldâ and âscale-freeâ networks. These networks have also been applied to the gross neural connectivity between primate cortical areas and the nervous system of Caenorhabditis elegans. Here, we extend this work to a specific neural circuit of the vertebrate brainâthe medial reticular formation (RF) of the brainstemâand, in doing so, we have made three key contributions. First, this work constitutes the first model (and quantitative review) of this important brain structure for over three decades. Second, we have developed the first graph-theoretic analysis of vertebrate brain connectivity at the neural network level. Third, we propose simple metrics to quantitatively assess the extent to which the networks studied are small-world or scale-free. We conclude that the medial RF is configured to create small-world (implying coherent rapid-processing capabilities), but not scale-free, type networks under assumptions which are amenable to quantitative measurement
Studies towards combined chemo-biocatalytic reactions in water
In recent years green chemistry has been increasingly applied to industrial syntheses. One
key area of growth is the use of biocatalysts to perform reactions selectively in non-organic
media. However, there is currently no set development process for the discovery and evolution
of enzymes to be applied in these reactions. A process has been suggested by Hailes
et al, part of which is the development of chemical reactions that work in combination with
the biocatalysts.1 The interface between traditional chemistry and biocatalysis has yet to
be fully explored, particularly in relation to the potential degree of interaction between the
two synthetic techniques.
The development of a chemical reaction that can be used in one-pot with a biotransformation
is explored within this thesis. The synthesis of a standard to calibrate an assay of
the transketolase selectivity was performed first. This allowed the stereochemistry of the
starting material of the reductive amination being developed to be determined.
Next a reductive amination reaction that proceeded in water and in the presence of
transketolase was discovered and then optimized using cyclohexanone as a test substrate.
This reaction was developed so that it could offer an alternative to a similar transformation
performed by a transaminase enzyme, specifically with respect to substrate and stereoselectivity.
This optimized reaction was then applied to an intermediate (1,3-dihydroxy-pentan-2-
one), synthesized both using standard organocatalytic techniques and a biotransformation
using transketolase, to produce 2-benzylamino-pentane-1,3-diol. The reaction was seen to be diastereoselective and an alternative transfer hydrogenation reaction that displayed the
opposite selectivity was also investigated. This complimentary pair of reactions meant that
all four diastereoisomers of 2-benzylamino-pentane-1,3-diol could potentially be synthesized.
This work illustrated that the development of chemical reactions towards one-pot cascade
reactions with biocatalysts is possible
OC-0257: NTCP models for acute dysphagia resulting from (chemo)radiotherapy for head and neck cancer
âCATAStrophy,â a Genome-Informed Trophic Classification of Filamentous Plant Pathogens â How Many Different Types of Filamentous Plant Pathogens Are There?
The traditional classification of fungal and oomycete phytopathogens into three classes â biotrophs, hemibiotrophs, or necrotrophs â is unsustainable. This study highlights multiple phytopathogen species for which these labels have been inappropriately applied. We propose a novel and reproducible classification based solely on genome-derived analysis of carbohydrate-active enzyme (CAZyme) gene content called CAZyme-Assisted Training And Sorting of -trophy (CATAStrophy). CATAStrophy defines four major divisions for species associated with living plants. These are monomertrophs (Mo) (corresponding to biotrophs), polymertrophs (P) (corresponding to necrotrophs), mesotrophs (Me) (corresponding to hemibiotrophs), and vasculartrophs (including species commonly described as wilts, rots, or anthracnoses). The Mo class encompasses symbiont, haustorial, and non-haustorial species. Me are divided into the subclasses intracellular and extracellular Me, and the P into broad and narrow host sub-classes. This gives a total of seven discrete plant-pathogenic classes. The classification provides insight into the properties of these species and offers a facile route to develop control measures for newly recognized diseases. Software for CATAStrophy is available online at https://github.com/ccdmb/catastrophy. We present the CATAStrophy method for the prediction of trophic phenotypes based on CAZyme gene content, as a complementary method to the traditional tripartite âbiotrophâhemibiotrophânecrotrophâ classifications that may encourage renewed investigation and revision within the fungal biology community.</p
Towards the Non-Chiral Extension of SM and MSSM
We show that in some SU(N) type GUTs with the complementary pairs of the
conjugated fermion multiplets there naturally appear the relatively light
() vectorlike fermions which considerably modify the desert
physics. In the non-SUSY case they can provide for the unification of the
standard coupling constant , and whereas in the
SUSY case they can increase the unification point up to the string unification
limit and decrease down to the value predicted from the low
energy physics.Comment: LaTeX, 1 figur
Geology of the Llanidloes district : British Geological Survey Sheet 164
This Sheet Explanation provides a summary of the geology of the district covered by Geological 1:50 000 Series
Map Sheet 164 (Llanidloes), published in 2010 as a Bedrock and Superficial Deposits edition. The district mostly
lies within the county of Powys, but includes small parts of Ceredigion in the extreme west and south-west. Much of
the western part of the district is occupied by the deeply dissected uplands of the Cambrian Mountains, a designated
Area of Outstanding Natural Beauty. In this area the land rises to 740 m on the flanks of Plynlimon (Pumlumon
Fawr), the highest summit in the range. It falls away towards the eastern part of the district into rolling countryside
that includes the important catchment of the River Severn (Afon Hafren) and its tributaries, the largest of which are
the rivers Carno, Trannon, Cerist, Clywedog and Dulas. A major reservoir (Llyn Clywedog) occupies the upper
reaches of the Clywedog valley, its purpose being to regulate river discharge and groundwater levels within the
catchment. The south-western part of the district is drained by the River Wye (Afon Gwy) and its tributaries, that
flow south-eastwards via Llangurig. The sources of both the Severn and Wye are situated on the eastern flanks of
Plynlimon within the western part of the district.
The town of Llanidloes is the main centre of population, with smaller settlements at Llangurig, Carno, Trefeglwys,
Caersws and Staylittle; the Newtown conurbation impinges on the eastern part of the district. Much of the district is
given over to beef and dairy farming, although sheep are reared in the remote upland areas in the west and extensive
forestry plantations have been developed in places. The Ordovician and Silurian rocks of the district have been
exploited locally, in the past, as a source of building material and, recently, commercial quantities of sandstone
aggregate have been excavated at Penstrowed Quarry [SO 0680 9100]. The district includes part of the Central
Wales Mining Field from which substantial volumes of lead and zinc ore were extracted during the 19th and early
20th centuries. A number of former mine sites are still visible, notably along the Van, Nant-y-ricket, Dylife,
Dyfngwm and Llanerchyraur lodes (Jones, 1922[1]; IGS, 1974), and the historic Bryntail Mine, below the Clywedog
Dam has been restored as a site of industrial archaeological interest.
The district is underlain by a succession of Late Ordovician (Ashgill) to Silurian sedimentary rocks, over 5 km thick,
deposited between 450 and 420 million years ago in the Early Palaeozoic Welsh Basin (Figure P930911). The basin
developed on a fragment of the ancient supercontinent of Gondwana, known as Eastern Avalonia (e.g. Pickering et
al., 1988[2]), that drifted northwards to collide with the continents of Baltica and Laurentia during the Late
Ordovician and Silurian (Soper and Hutton, 1984[3]; Soper and Woodcock, 1990[4]; Woodcock and Strachan,
2000[5]). To the east and the south of the basin lay the Midland Platform, a relatively stable shallow marine shelf that
was subject to periodic emergence. The basinal sediments are predominantly deep marine turbiditic facies that were
introduced into the district by density currents from southerly, south-easterly and north-westerly quadrants. Coeval
shallower-water âshelfalâ sediments were deposited north and east of the district, and locally impinge on its northern
margins. Thickness variations within the major sedimentary units suggest that, at times, syndepositional fault
movements were an important control on their distribution. During late Silurian (Ludlow) times, shallowing of the
basin occurred, and sandstones, variably interpreted as a turbiditic (Cave and Hains, 2001[6]) or storm-generated
facies (Tyler and Woodcock, 1987[7]), were laid down over the eastern part of the district and adjacent areas. The
shallowing was a result of tectonic reconfiguration of the basin, a precursor to the late Caledonian (Acadian)
Orogeny that affected the region during the late Early Devonian, around 400 million years ag
Baryon Decuplet to Octet Electromagnetic Transitions in Quenched and Partially Quenched Chiral Perturbation Theory
We calculate baryon decuplet to octet electromagnetic transition form factors
in quenched and partially quenched chiral perturbation theory. We work in the
isospin limit of SU(3) flavor, up to next-to-leading order in the chiral
expansion, and to leading order in the heavy baryon expansion. Our results are
necessary for proper extrapolation of lattice calculations of these
transitions. We also derive expressions for the case of SU(2) flavor away from
the isospin limit.Comment: 16 pages, 3 figures, revtex
Demonstration of immune responses against devil facial tumour disease in wild Tasmanian devils
Devil facial tumour disease (DFTD) is a recently emerged fatal transmissible cancer decimating the wild population of Tasmanian devils (Sarcophilus harrisii). Biting transmits the cancer cells and the tumour develops in the new host as an allograft. The literature reports that immune escape mechanisms employed by DFTD inevitably result in host death. Here we present the first evidence that DFTD regression can occur and that wild devils can mount an immune response against the disease. Of the 52 devils tested, six had serum antibodies against DFTD cells and, in one case, prominent T lymphocyte infiltration in its tumour. Notably, four of the six devils with serum antibody had histories of DFTD regression. The novel demonstration of an immune response against DFTD in wild Tasmanian devils suggests that a proportion of wild devils can produce a protective immune response against naturally acquired DFTD. This has implications for tumour-host coevolution and vaccine development.Ruth Pye, Rodrigo Hamede, Hannah V. Siddle, Alison Caldwell, Graeme W. Knowles, Kate Swift, Alexandre Kreiss, Menna E. Jones, A. Bruce Lyons, Gregory M. Wood
Telomere length heterogeneity in placenta revealed with high-resolution telomere length analysis
Introduction
Telomeres, are composed of tandem repeat sequences located at the ends of chromosomes and are required to maintain genomic stability. Telomeres can become shorter due to cell division and specific lifestyle factors. Critically shortened telomeres are linked to cellular dysfunction, senescence and aging. A number of studies have used low resolution techniques to assess telomere length in the placenta. In this study, we applied Single Telomere Length Analysis (STELA) which provides high-resolution chromosome specific telomere length profiles to ask whether we could obtain more detailed information on the length of individual telomeres in the placenta.
Methods
Term placentas (37â42 weeks) were collected from women delivering at University Hospital of Wales or Royal Gwent Hospital within 2 h of delivery. Multiple telomere-length distributions were determined using STELA. Intraplacental variation of telomere length was analysed (N = 5). Telomere length distributions were compared between labouring (N = 10) and non-labouring (N = 11) participants. Finally, telomere length was compared between female (N = 17) and male (N = 20) placenta.
Results
There were no significant influences of sampling site, mode of delivery or foetal sex on the telomere-length distributions obtained. The mean telomere length was 7.7 kb ranging from 5.0 kb to 11.7 kb across all samples (N = 42) and longer compared with other human tissues at birth. STELA also revealed considerable telomere length heterogeneity within samples.
Conclusions
We have shown that STELA can be used to study telomere length homeostasis in the placenta regardless of sampling site, mode of delivery and foetal sex. Moreover, as each amplicon is derived from a single telomeric molecule, from a single cell, STELA can reveal the full detail of telomere-length distributions, including telomeres within the length ranges observed in senescent cells. STELA thus provides a new tool to interrogate the relationship between telomere length and pregnancy complications linked to placental dysfunction
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