188 research outputs found
Reducing the data-deficiency of threatened European habitats: Spatial variation of sabellariid worm reefs and associated fauna in the Sicily Channel, Mediterranean Sea
Biogenic reefs, such as those produced by tube-dwelling polychaetes of the genus Sabellaria, are valuable
marine habitats which are a focus of protection according to European legislation. The achievement of
this goal is potentially hindered by the lack of essential empirical data, especially in the Mediterranean
Sea. This study addresses some of the current knowledge gaps by quantifying and comparing multi-scale
patterns of abundance and distribution of two habitat-forming species (Sabellaria alveolata and
S. spinulosa) and their associated fauna along 190 km of coast on the Italian side of the Sicily Channel.
While the abundance of the two sabellariids and the total number of associated taxa did not differ at any
of the examined scales (from tens of centimetres to tens-100 of kilometres), the structure (composition
in terms of both the identity and the relative abundance of constituting taxa) of the associated fauna and
the abundance of several taxa (the polychaetes Eulalia ornata, Syllis pulvinata, S. garciai, Nereis splendida
and Arabella iricolor, and the amphipods Apolochus neapolitanus, Tethylembos viguieri and Caprella
acanthifera) varied among locations established ~50e100 km apart. Syllis pulvinata also showed significant
variation between sites (hundreds of metres apart), analogously to the other syllid polychaetes
S. armillaris and S. gracilis, the nereidid polychaete Nereis rava, and the amphipod Gammaropsis ulrici. The
largest variance of S. spinulosa, of the structure of the whole associated fauna and of 56% of taxa analysed
individually occurred at the scale of replicates (metres apart), while that of the dominant bio-constructor
S. alveolata and of 25% of taxa occurred at the scale of sites. The remaining 19% and the total richness of
taxa showed the largest variance at the scale of locations. Present findings contribute to meet a crucial
requirement of any future effective protection strategy, i.e., identifying relevant scales of variation to be
included in protection schemes aiming at preserving representative samples not only of target habitats
and organisms, but also of the processes driving such variabilit
Regge Behavior of DIS Structure Functions
Building on previous works of the mid 1960's, we construct an integral
equation for forward elastic scattering (t=0) at arbitrary virtuality Q^2 and
large s=W^2. This equation sums the ladder production of massless intermediate
bosons to all orders, and the solution exhibits Regge behavior. The equation is
used to study scattering in a simple chi^2 phi scalar theory, where it is
solved appoximately and applied to the study of DIS at small x. We find that
the model can naturally describe the quark distribution in both the large x
region and the small x region dominated by Reggeon exchange.Comment: 13 pages with 5 figure
Stability of Satellite Planes in M31 II: Effects of the Dark Subhalo Population
The planar arrangement of nearly half the satellite galaxies of M31 has been
a source of mystery and speculation since it was discovered. With a growing
number of other host galaxies showing these satellite galaxy planes, their
stability and longevity have become central to the debate on whether the
presence of satellite planes are a natural consequence of prevailing
cosmological models, or represent a challenge. Given the dependence of their
stability on host halo shape, we look into how a galaxy plane's dark matter
environment influences its longevity. An increased number of dark matter
subhalos results in increased interactions that hasten the deterioration of an
already-formed plane of satellite galaxies in spherical dark halos. The role of
total dark matter mass fraction held in subhalos in dispersing a plane of
galaxies present non trivial effects on plane longevity as well. But any
misalignments of plane inclines to major axes of flattened dark matter halos
lead to their lifetimes being reduced to < 3 Gyrs. Distributing > 40% of total
dark mass in subhalos in the overall dark matter distribution results in a
plane of satellite galaxies that is prone to change through the 5 Gyr
integration time period.Comment: 11 pages, 9 figures, accepted to MNRAS September 22 201
Electrochemical noise and impedance of Au electrode/electrolyte interfaces enabling extracellular detection of glioma cell populations
Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 mu Vpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 mu Vpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations
Altered Hematopoiesis in Mice Lacking DNA Polymerase μ Is Due to Inefficient Double-Strand Break Repair
Polymerase mu (Polμ) is an error-prone, DNA-directed DNA polymerase that participates in non-homologous end-joining (NHEJ) repair. In vivo, Polμ deficiency results in impaired Vκ-Jκ recombination and altered somatic hypermutation and centroblast development. In Polμ−/− mice, hematopoietic development was defective in several peripheral and bone marrow (BM) cell populations, with about a 40% decrease in BM cell number that affected several hematopoietic lineages. Hematopoietic progenitors were reduced both in number and in expansion potential. The observed phenotype correlates with a reduced efficiency in DNA double-strand break (DSB) repair in hematopoietic tissue. Whole-body γ-irradiation revealed that Polμ also plays a role in DSB repair in non-hematopoietic tissues. Our results show that Polμ function is required for physiological hematopoietic development with an important role in maintaining early progenitor cell homeostasis and genetic stability in hematopoietic and non-hematopoietic tissues
Reading related white matter structures in adolescents are influenced more by dysregulation of emotion than behavior
Mood disorders and behavioral are broad psychiatric diagnostic categories that have different symptoms and neurobiological mechanisms, but share some neurocognitive similarities, one of which is an elevated risk for reading deficit. Our aim was to determine the influence of mood versus behavioral dysregulation on reading ability and neural correlates supporting these skills in youth, using diffusion tensor imaging in 11- to 17-year-old children and youths with mood disorders or behavioral disorders and age-matched healthy controls. The three groups differed only in phonological processing and passage comprehension. Youth with mood disorders scored higher on the phonological test but had lower comprehension scores than children with behavioral disorders and controls; control participants scored the highest. Correlations between fractional anisotropy and phonological processing in the left Arcuate Fasciculus showed a significant difference between groups and were strongest in behavioral disorders, intermediate in mood disorders, and lowest in controls. Correlations between these measures in the left Inferior Longitudinal Fasciculus were significantly greater than in controls for mood but not for behavioral disorders. Youth with mood disorders share a deficit in the executive-limbic pathway (Arcuate Fasciculus) with behavioral-disordered youth, suggesting reduced capacity for engaging frontal regions for phonological processing or passage comprehension tasks and increased reliance on the ventral tract (e.g., the Inferior Longitudinal Fasciculus). The low passage comprehension scores in mood disorder may result from engaging the left hemisphere. Neural pathways for reading differ mainly in executive-limbic circuitry. This new insight may aid clinicians in providing appropriate intervention for each disorder
Essential Factors for Incompatible DNA End Joining at Chromosomal DNA Double Strand Breaks In Vivo
Non-homologous end joining (NHEJ) is a major pathway for the repair of DNA double strand break (DSBs) with incompatible DNA ends, which are often generated by ionizing irradiation. In vitro reconstitution studies have indicated that NHEJ of incompatible DNA ends requires not only the core steps of synapsis and ligation, employing KU80/DNA-PKcs and LIG4, but also additional DNA end processing steps, such as DNA end resection by Artemis and gap-filling by POLλ and POLμ. It seems that DNA end processing steps are important for joining of incompatible DNA ends rather than compatible ends. Despite the fact that DNA end processing is important for incompatible DNA end joining in vitro, the role of DNA processing in NHEJ of incompatible DSBs in vivo has not yet been demonstrated. Here we investigated the in vivo roles of proteins implicated in each step of NHEJ using an assay in which NHEJ of incompatible DNA ends on chromosomal DNA can be assessed in living human cells. siRNA- or inhibitor-mediated impairment of factors in each NHEJ step resulted in a reduction in joining efficiency. Strikingly, stronger effects were observed when DNA end resection and ligation protein functions were impaired. Disruption of synapsis by KU80 and DNA-PKcs impairment, or the disruption of gap filling by POLλ and POLμ depletion, resulted in higher levels of microhomology-mediated joining. The present study indicates that DNA end resection and ligation factors are critical for the efficient joining of incompatible ends in vivo, further emphasizing the importance of synapsis and gap-filling factors in preventing illegitimate joining
Can Emotional and Behavioral Dysregulation in Youth Be Decoded from Functional Neuroimaging?
High comorbidity among pediatric disorders characterized by behavioral and emotional dysregulation poses problems for diagnosis and treatment, and suggests that these disorders may be better conceptualized as dimensions of abnormal behaviors. Furthermore, identifying neuroimaging biomarkers related to dimensional measures of behavior may provide targets to guide individualized treatment. We aimed to use functional neuroimaging and pattern regression techniques to determine whether patterns of brain activity could accurately decode individual-level severity on a dimensional scale measuring behavioural and emotional dysregulation at two different time points
Polymorphism of the catechol-O-methyltransferase gene in Han Chinese patients with psoriasis vulgaris
Psoriasis vulgaris is defined by a series of linked cellular changes in the skin: hyperplasia of epidermal keratinocytes, vascular hyperplasia and ectasia, and infiltration of T lymphocytes, neutrophils and other types of leukocytes in the affected skin. Catechol-O-methyltransferase (COMT) 158 polymorphism can reduce the activity of the COMT enzyme that may trigger defective differentiation of keratinocytes in psoriasis. Immunocytes can degrade and inactivate catecholamines via monamine oxidase (MAO) and COMT in the cells. We hypothesized that the COMT-158G > A polymorphism was associated with the risk of psoriasis vulgaris in Han Chinese people. In a hospital-based case-control study, 524 patients with psoriasis vulgaris and 549 psoriasis-free controls were studied. COMT-158 G > A polymorphism was genotyped using the PCR sequence-specific primer (PCR-SSP) technique. We found no statistically significant association between the COMT-158 allele A and the risk of psoriasis vulgaris (p = 0.739 adjusted OR = 1.03; 95% CI = 0.81-1.31). This suggests that the COMT-158 G > A polymorphism may not contribute to the etiology of psoriasis vulgaris in the Han Chinese population
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