bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosynthesis and Regulation of Grisemycin, a New Member of the Linaridin Family of Ribosomally Synthesized Peptides Produced by Streptomyces griseus IFO 13350
Authors: Claesen Jan , Bibb Mervyn J.
Published: March 2011

Our recent identification and genetic analysis of the biosynthetic gene cluster for production of the ribosomally synthesized and posttranslationally modified peptide cypemycin revealed a new class of peptide natural products, the linaridins. Here we describe the identification and characterization of grisemycin, a linaridin produced by a previously unidentified gene cluster in
Streptomyces griseus
IFO 13350. Mass spectrometric analysis revealed that grisemycin possesses at least three of the modifications found in cypemycin, as well as an analogous leader peptidase cleavage site. Expression of putative grisemycin biosynthetic genes in a
Streptomyces coelicolor
A3(2) derivative, combined with deletion of the gene encoding the grisemycin precursor peptide, confirmed the identity of the grisemycin gene cluster. Both grisemycin and cypemycin depend on the transcriptional activator AdpA for wild-type levels of production.
Draft Genome Sequence of Caloramator australicus Strain RC3
T
, a Thermoanaerobe from the Great Artesian Basin of Australia
Authors: Ogg Christopher D. , Patel Bharat K. C.
Published: March 2011

Caloramator australicus
strain RC3
T
(JCM 15081
T
= KCTC 5601
T
) is the type strain of a newly identified thermophilic species, which was isolated from red microbial mats that thrive at 66°C in the runoff channel of a Great Artesian Basin bore (New Lorne bore, registered number 17263) in outback Queensland, Australia. The ability of the
C. australicus
strain to use metals as terminal electron acceptors has led to concerns that it could colonize and enhance corrosion of the metal casing of Great Artesian Basin bore well pipes and that this could subsequently lead to bore failure and loss of water availability for the community which is so reliant on it. The genome of the
C. australicus
strain has been sequenced, and annotation of the ∼2.65-Mb sequence indicates that the attributes are consistent with physiological and phenotypic traits.
Involvement of CarA/LitR and CRP/FNR Family Transcriptional Regulators in Light-Induced Carotenoid Production in Thermus thermophilus
Authors: Takano Hideaki , Kondo Masato , Usui Noriyoshi , Usui Toshimitsu , Ohzeki Hiromichi , Yamazaki Ryuta , Washioka Misato , Nakamura Akira , Hoshino Takayuki , Hakamata Wataru , Beppu Teruhiko , Ueda Kenji
Published: March 2011

Members of the CarA/LitR family are MerR-type transcriptional regulators that contain a C-terminal cobalamin-binding domain. They are thought to be involved in light-induced transcriptional regulation in a wide variety of nonphototrophic bacteria. Based on the distribution of this kind of regulator, the current study examined carotenoid production in
Thermus thermophilus
, and it was found to occur in a light-induced manner.
litR
and carotenoid and cobalamin biosynthesis genes were all located on the large plasmid of this organism.
litR
or cobalamin biosynthesis gene knockout mutants were unable to switch off carotenoid production under dark conditions, while a mutant with a mutation in the downstream gene adjacent to
litR
(TT_P0055), which encodes a CRP/FNR family transcriptional regulator, was unable to produce carotenoids, irrespective of light conditions. Overall, genetic and biochemical evidence indicates that LitR is bound by cobalamin and associates with the intergenic promoter region between
litR
and
crtB
(phytoene synthase gene), repressing the bidirectional transcription of
litR
and
crtB
. It is probable that derepression of LitR caused by some photodependent mechanism induces the expression of TT_P0055 protein, which serves as a transcriptional activator for the
crtB
operon and hence causes the expression of carotenoid biosynthesis and the DNA repair system under light condition.
Role of Maltose Enzymes in Glycogen Synthesis by Escherichia coli
Authors: Park Jong-Tae , Shim Jae-Hoon , Tran Phuong Lan , Hong In-Hee , Yong Hwan-Ung , Oktavina Ershita Fitria , Nguyen Hai Dang , Kim Jung-Wan , Lee Tae Soo , Park Sung-Hoon , Boos Winfried , Park Kwan-Hwa
Published: March 2011

Mutants with deletion mutations in the
glg
and
mal
gene clusters of
Escherichia coli
MC4100 were used to gain insight into glycogen and maltodextrin metabolism. Glycogen content, molecular mass, and branch chain distribution were analyzed in the wild type and in Δ
malP
(encoding maltodextrin phosphorylase), Δ
malQ
(encoding amylomaltase), Δ
glgA
(encoding glycogen synthase), and Δ
glgA
Δ
malP
derivatives. The wild type showed increasing amounts of glycogen when grown on glucose, maltose, or maltodextrin. When strains were grown on maltose, the glycogen content was 20 times higher in the Δ
malP
strain (0.97 mg/mg protein) than in the wild type (0.05 mg/mg protein). When strains were grown on glucose, the Δ
malP
strain and the wild type had similar glycogen contents (0.04 mg/mg and 0.03 mg/mg protein, respectively). The Δ
malQ
mutant did not grow on maltose but showed wild-type amounts of glycogen when grown on glucose, demonstrating the exclusive function of GlgA for glycogen synthesis in the absence of maltose metabolism. No glycogen was found in the Δ
glgA
and Δ
glgA
Δ
malP
strains grown on glucose, but substantial amounts (0.18 and 1.0 mg/mg protein, respectively) were found when they were grown on maltodextrin. This demonstrates that the action of MalQ on maltose or maltodextrin can lead to the formation of glycogen and that MalP controls (inhibits) this pathway.
In vitro
, MalQ in the presence of GlgB (a branching enzyme) was able to form glycogen from maltose or linear maltodextrins. We propose a model of maltodextrin utilization for the formation of glycogen in the absence of glycogen synthase.
CRISPR Distribution within the Escherichia coli Species Is Not Suggestive of Immunity-Associated Diversifying Selection
Authors: Touchon Marie , Charpentier Sophie , Clermont Olivier , Rocha Eduardo P. C. , Denamur Erick , Branger Catherine
Published: March 2011

In order to get further insights into the role of the clustered, regularly interspaced, short palindromic repeats (CRISPRs) inEscherichia coli, we analyzed the CRISPR diversity in a collection of 290 strains, in the phylogenetic framework of the strains represented by multilocus sequence typing (MLST). The set included 263 naturalE. coliisolates exposed to various environments and isolated over a 20-year period from humans and animals, as well as 27 fully sequenced strains. Our analyses confirm that there are two largely independent pairs of CRISPR loci (CRISPR1 and -2 and CRISPR3 and -4), each associated with a different type ofcasgenes (Ecoli and Ypest, respectively), but that each pair of CRISPRs has similar dynamics. Strikingly, the major phylogenetic group B2 is almost devoid of CRISPRs. The majority of genomes analyzed lack Ypestcasgenes and contain CRISPR3 with spacers matching Ypestcasgenes. The analysis of relatedness between strains in terms of spacer repertoire and the MLST tree shows a pattern where closely related strains (MLST phylogenetic distance of <0.005 corresponding to at least hundreds of thousands of years) often exhibit identical CRISPRs while more distantly related strains (MLST distance of >0.01) exhibit completely different CRISPRs. This suggests rare but radical turnover of spacers in CRISPRs rather than CRISPR gradual change. We found no link between the presence, size, or content of CRISPRs and the lifestyle of the strains. Our data suggest that, within theE. colispecies, CRISPRs do not have the expected characteristics of a classical immune system.
A MotN Mutant of Ralstonia solanacearum Is Hypermotile and Has Reduced Virulence
Authors: Meng Fanhong , Yao Jian , Allen Caitilyn
Published: March 2011

Ralstonia solanacearum
is a soil-borne plant pathogen that causes bacterial wilt disease on many plant species. We previously showed that swimming motility contributes to virulence of this bacterium in the early stages of host invasion and colonization. In this study we identified a new negative regulator of motility, named
motN
, that is located in a cluster of motility-related genes. A
motN
mutant was hypermotile both on 0.3% agar motility plates and in rich and minimal medium broth. However, like its wild-type parent, it was largely nonmotile inside plants. The
motN
mutant cells appeared hyperflagellated, and sheared cell protein preparations from
motN
contained more flagellin than preparations from wild-type cells. The
motN
strain was significantly reduced in virulence in a naturalistic soil soak assay on tomato plants. However, the
motN
mutant had wild-type virulence when it was inoculated directly into the plant vascular system. This suggests that
motN
makes its contribution to virulence early in disease development. The
motN
mutant formed weaker biofilms than the wild type, but it attached normally to tomato roots and colonized tomato stems as well as its wild-type parent. Phenotypic analysis and gene expression studies indicated that MotN directly or indirectly represses transcription of the major motility regulator FlhDC. MotN was also connected with other known motility and virulence regulators, PehSR, VsrBC, and VsrAD, via uncertain mechanisms. Together, these results demonstrate the importance of precise regulation of flagellum-mediated motility in
R. solanacearum
.
Role of the Biofilm Master Regulator CsgD in Cross-Regulation between Biofilm Formation and Flagellar Synthesis
Authors: Ogasawara Hiroshi , Yamamoto Kaneyoshi , Ishihama Akira
Published: March 2011

CsgD, the master regulator of biofilm formation, activates the synthesis of curli fimbriae and extracellular polysaccharides in
Escherichia coli
. To obtain insights into its regulatory role, we have identified a total of 20 novel regulation target genes on the
E. coli
genome by using chromatin immunoprecipitation (ChIP)-on-chip analysis with a high-density DNA microarray. By DNase I footprinting, the consensus CsgD-binding sequence predicted from a total of 18 target sites was found to include AAAAGNG(N
2
)AAAWW. After a promoter-
lacZ
fusion assay, the CsgD targets were classified into two groups: group I genes, such as
fliE
and
yhbT
, are repressed by CsgD, while group II genes, including
yccT
and
adrA
, are activated by CsgD. The
fliE
and
fliEFGH
operons for flagellum formation are directly repressed by CsgD, while CsgD activates the
adrA
gene, which encodes an enzyme for synthesis of cyclic di-GMP, a bacterial second messenger, which in turn inhibits flagellum production and rotation. Taking these findings together, we propose that the cell motility for planktonic growth is repressed by CsgD, thereby promoting the switch to biofilm formation.
Staphylococcus aureus CidA and LrgA Proteins Exhibit Holin-Like Properties
Authors: Ranjit Dev K. , Endres Jennifer L. , Bayles Kenneth W.
Published: March 2011

The
Staphylococcus aureus
cid
and
lrg
operons are known to be involved in biofilm formation by controlling cell lysis and the release of genomic DNA, which ultimately becomes a structural component of the biofilm matrix. Although the molecular mechanisms controlling cell death and lysis are unknown, it has been hypothesized that the
cidA
and
lrgA
genes encode holin- and antiholin-like proteins and function to regulate these processes similarly to bacteriophage-induced death and lysis. In this study, we focused on the biochemical and molecular characterization of CidA and LrgA with the goal of testing the holin model. First, membrane fractionation and fluorescent protein fusion studies revealed that CidA and LrgA are membrane-associated proteins. Furthermore, similarly to holins, CidA and LrgA were found to oligomerize into high-molecular-mass complexes whose formation was dependent on disulfide bonds formed between cysteine residues. To determine the function of disulfide bond-dependent oligomerization of CidA, an
S. aureus
mutant in which the wild-type copy of the
cidA
gene was replaced with the cysteine mutant allele was generated. As determined by β-galactosidase release assays, this mutant exhibited increased cell lysis during stationary phase, suggesting that oligomerization has a negative impact on this process. When analyzed for biofilm development and maturation, this mutant displayed increased biofilm adhesion in a static assay and a greater amount of dead-cell accumulation during biofilm maturation. These studies support the model that CidA and LrgA proteins are bacterial holin-/antiholin-like proteins that function to control cell death and lysis during biofilm development.
Patient-reported fasting status for glucose-tolerance testing compared with fasting status identified by total bile-acid concentrations
Authors: Sargazi Mansour , Neithercut William D
Published: March 2011

Aim

To investigate whether patients follow advice regarding the duration of a fast, prior to blood tests which require an overnight fast for their correct interpretation.

Method

Patients referred for a glucose-tolerance test gave informed consent. They were asked to complete a questionnaire regarding the duration of their fast, and an additional blood sample was collected for fasting total bile-acid measurement.

Results

184 patients were recruited. The median duration of fast self reported by patients was 14 h (range 12–26 h). Total bile-acid concentrations were within the fasting reference range except for six individuals. The median total bile-acid concentration found was 2.1 μmol/l (range 0.1–19.5 μmol/l).

Conclusion

All patients who self-reported a duration of fast reported a fast recognised as being adequate for fasting blood tests. This was confirmed in almost all by low normal total bile-acid measurements, which were well within the fasting range.
STUDIES ON OPTOELECTRONIC PROPERTIES OF Eu3+ ACTIVATED LaOCl NANOPHOSPHOR
Authors: CHOUBEY A. , SOM S. , KUMARI R. , SHARMA S. K.
Published: March 2011

The 0.1 mol% europium ( Eu 3+) activated lanthanum oxychloride nanophosphor was prepared by the liquid-phase method. The X-ray diffraction analysis of the prepared compound exhibits the tetragonal structure having the particles size in the range of 18–21 nm. The band gap of Eu 3+ doped LaOCl phosphor was found to be around 5.2 eV using absorption and diffuse reflectance measurements. The photoluminescence (PL) emission spectra show the bright emission in orange–red region from 580 nm to 630 nm. The most intense emission peak at 621 nm was due to transition in energy levels 5 D 0 → 7 F 2 of Eu 3+ ions. The absorption and stimulated emission cross-section of the intense peak were found to be 4.135 × 10-20 cm2 and 8.9 × 10-20 cm2 respectively. The wide band gap and high stimulated emission cross-section of prepared nanophosphor makes its possible applications as red emitting phosphor in display devices and laser system.
GLOBAL EXISTENCE OF PERIODIC SOLUTIONS IN THE LINEARLY COUPLED MACKEY–GLASS SYSTEM
Authors: LI YANQIU , JIANG WEIHUA
Published: March 2011

The dynamics of a linearly coupled Mackey–Glass system with delay are investigated. Based on the distribution of eigenvalues, we prove that a sequence of Hopf bifurcation occurs at the positive equilibrium as the delay increases and obtain the bifurcation set in the parameter plane. The explicit algorithm for determining the direction of Hopf bifurcation and the stability of the bifurcating periodic solutions are derived, using the theories of normal form and center manifold. The global existence of periodic solutions is established using a global Hopf bifurcation result due to Wu [1998] and a Bendixson's criterion for higher dimensional ordinary differential equations due to [Li & Muldowney, 1993].
ENTREPRENEURIAL EXIT AND REENTRY: AN EXPLORATORY STUDY OF TURKISH ENTREPRENEURS
Authors: KOÇAK AKIN , MORRIS MICHAEL H. , BUTTAR HAROON MUZAFFER , CIFCI SERTAÇ
Published: March 2011

This study attempts to develop a better understanding in an emerging economy of the exit and reentry processes of entrepreneurs. Twelve case studies were conducted in Turkey with entrepreneurs who, following entrepreneurial exit, re-entered with new ventures. Human and social capital perspectives are used to gain insights into the reentry process. The study indicates that reasons for and modes of exit influence the entrepreneur's decisions surrounding reentry. Results further reveal that experiential and educational dimensions of human capital are instrumental in the reentry process. The study finds that structural and relational dimensions of social capital are cardinal factors that influence the reentry process.
ENTREPRENEURSHIP AMONG RUSSIAN IMMIGRANTS IN NORWAY AND THEIR STAY-AT-HOME PEERS
Authors: VINOGRADOV EVGUENI , GABELKO MARIA
Published: March 2011

The level of self-employment among immigrants is often higher than among natives. The purpose of this paper was to test empirically whether selective migration with respect to entrepreneurial characteristics may explain this difference. The relevant hypotheses were tested comparing representative samples of Russian immigrants in Norway and their stay-at-home counterparts. Data from the Russian population came from the 2008 GEM study, while data on Russian immigrants in Norway were collected through a specially designed postal survey. The analysis revealed some demographic dissimilarity between the two groups, as well as a presence of selective migration with respect to entrepreneurial characteristics. This study demonstrates that immigrants (as compared to non-migrants) are more likely to report intentions to start a business. Moreover, they possess relatively large amount of specific human capital, social capital and self-confidence relevant for entrepreneurship. The paper concludes with proposed practical implications and suggestions for further research.
Low-temperature aqueous mobility of the rare-earth elements during sandstone diagenesis
Authors: Bouch Jon E. , Hole Malcolm J. , Trewin Nigel H. , Morton Andrew C.
Published: March 2011

Diagenetic francolite (carbonate fluor-apatite) occurs as overgrowths on detrital apatite grains in sandstones from the Lower Jurassic Statfjord Formation of the North Sea. The francolite overgrowths are considerably more enriched in the rare-earth elements (up to 1 wt % Ce
2
O
3
), Sr and F than the detrital cores. These elements were carried in aqueous solution, probably in the form of complex ligands involving organically sourced carbon and halogens. It is possible that reported aberrant neodymium isotope model ages within the Statfjord Formation are the result of mobilization and relative fractionation of Sm and Nd during diagenesis, rather than a result of changes in provenance.
Late Ordovician extinctions and sea-level change
Authors: Wyatt A. R.
Published: March 2011

If Ordovician continental blocks had similar hypsometries to modern continental blocks, glacially-induced regressions would have increased shallow water areas. Thus species/area effects cannot be invoked to explain extinctions during these regressions. Because late Ordovician sea level was so high, glacially-induced regressions of similar magnitudes to Quaternary regressions would have dramatically increased the input of dissolved load into the shallow sea. This ‘pollution’ effect may have been one cause of the extinctions.
Dyke domains in the Mitsero graben, Troodos ophiolite, Cyprus: an off-axis model for graben formation at a spreading centre
Authors: van Everdingen D. A. , Cawood P. A. , van Everdingen D. A. , Cawood P. A.
Published: March 2011

Graben at oceanic spreading centres may form at on-axis or off-axis positions. Their formation is dependent on the tectonic processes active in the oceanic crust. Evidence for the position of formation of graben in oceanic analogues (ophiolites) can be obtained from the orientation of dykes within sheeted dyke complexes. Dyke orientation data and dyke relations from the Mitsero graben and environs, Troodos ophiolite, Cyprus, have been used to determine the tectonic setting of graben formation. Five major dyke domains were delineated on the basis of orientation of dykes in the Sheeted Dyke Complex in the Mitsero graben. Between domains, the mean strike rotates counter-clockwise by 25°. In the easternmost domain, dyke strikes are roughly 070°, and progressively westward, the mean strikes of dykes within domains are roughly 045°, 026°, 000°, and 324°. Within domains the dyke trends show no systematic changes in strike toward the domain edges. Dyke cross-cutting relations, the degree of their rotation, and relations to other features such as hydrothermal alteration leads to the suggestion that the Mitsero graben formed late in the history of the area, possibly in an off-axis position.
Lithostratigraphy of the volcanic sequences at Hole 917A, Leg 152, SE Greenland margin
Authors: Demant A. , Cambray H. , Vandamme D. ,   The ODP Leg 152 Scientific Party
Published: March 2011

An overall high recovery rate (up to 52%) and 450 m of continuous logging data of good quality at ODP hole 917A, Leg 152, SE Greenland margin, allow us to refine the petrological descriptions made onboard and to establish a precise lithostratigraphy of the Palaeocene volcanic succession. Changes in the dips of the flow banding between the Upper Series and the Middle and Lower Series coincide with the transition from continental magmatism to post-breakup volcanism established by the geochemistry.
The Edoras Bank margin; continental break-up in the presence of a mantle plume
Authors: Barton A. J. , White R. S.
Published: March 2011

Edoras Bank lies on the eastern continental margin of the North Atlantic about 900 km south of the present-day Iceland plume. We studied the continent-ocean transition of the rifted margin using normal-incidence and wide-angle seismic reflection data. Seaward dipping reflectors are well-developed over much of the margin and are underlain by a high velocity (7.3–7.5 km s
−1
) lower crust. This is interpreted as either igneous underplating or as existing crust heavily intruded at the time of break-up by melts with high MgO contents and suggests that the thermal anomaly associated with the Iceland plume was well-developed in this area at the time of break-up.
The melting processes and composition of the North Atlantic (Iceland) plume: geochemical evidence from the Early Tertiary basalts
Authors: Kerr Andrew C.
Published: March 2011

Three successive geochemical magma types, which result from the decompression melting of the Iceland plume, can be identified throughout the North Atlantic Tertiary Igneous Province. Compared with Type 1, the geochemical signature of Type 2 can be interpreted in terms of shallower, more extensive melting, in response to lithospheric thinning. The chemistry of the youngest lavas and dykes (Type 3) suggests small degree melting at greater mantle depths than Type 2, perhaps below a lithospheric lid which had been re-thickened by underplating. The depleted (relative to Bulk Earth) geochemical signatures of Types 1 and 2 appear not to be derived from entrained upper MORB-source mantle, nor an immature HIMU plume. Rather, it is proposed that they are the melting products of an intrinsically depleted plume.
Magnesian basalts from the Hebrides, Scotland: chemical composition and relationship to the Iceland plume
Authors: Kent Ray W.
Published: March 2011

The Hebridean Tertiary igneous province lay 700–900 km south of a presumed plume centre, and >500 km landward of a rifted continental margin prior to opening of the northeast Atlantic. The Province includes a small number of magnesian basalts containing olivine phenocrysts with core compositions equal to, or in excess of, Fo
89
. Olivine-liquid equilibrium calculations suggest that these phenocrysts formed from liquids with MgO contents of 14–15 wt%, and in rare instances, 18–20 wt%. The liquidus temperatures of these magmas imply mantle potential temperatures of 1350–1460°C at distances up to 900 km from the axis of the Iceland plume. Their emplacement at
c.
60 Ma implies either a long-established hotspot, or active channeling of plume material along the base of the plate towards a region undergoing considerable lower crustal extension.
Sea-floor spreading in the presence of the Iceland plume: the structure of the Reykjanes Ridge at 61°40′N
Authors: Smallwood J. R. , White R. S. , Minshull T. A.
Published: March 2011

We present results from a combined normal incidence and wide-angle seismic survey of the Reykjanes Ridge at 61°40′N in the North Atlantic. The seismic data show that the crust is 8.4–10.0 km thick on the ridge axis. We attribute this thicker than normal oceanic crust to a high degree of melting caused by hot mantle from the Iceland plume beneath the speading centre. Layer 2A of the oceanic crust is significantly thicker at 0 Ma than in crust of age 4 Ma. Our results, combined with other seismic data from the North Atlantic, show that the crustal thickness decreases away from the plume centre to normal oceanic crustal thickness at a distance of approximately 1000 km.
Petrographic and geochemical variation along the Reykjanes Ridge, 57°N–59°N
Authors: Taylor Rex N. , Murton B. J. , Thirwall M. F.
Published: March 2011

High-density sampling of the neo-volcanic zone along the Reykjanes Ridge has been used to test the relationship between bathymetric features and geochemistry. The axial region has short wavelength features which correspond to elongate, en-echelon volcanic ridges. These ridges sit atop intermediate wavelength features, termed swells and troughs. A broad correspondence is found between the sections containing more fractionated samples and the intermediate wavelength swells. Conversely, the troughs are dominated by more primitive lavas. This suggests that swells represent areas of greater melt flux, resulting in thicker crust and hence generally more fractionation. Progressively higher concentrations of incompatible elements are found northwards along the ridge, with increases occurring as a series of steps that do not correlate with short or intermediate wavelength bathymetric features. The northward increase in ratios such as Nb/Zr suggests that sections of the ridge are fed by similar aggregate melt fractions, and that melt fractions become slightly smaller northwards. Changes or consistency in ratio, particularly Rb/Nb, cannot be explained by progressively greater northward incorporation of a component from the Icelandic plume mantle.
The temperature of the Iceland plume and origin of outward-propagating V-shaped ridges
Authors: White R. S. , Bown J. W. , Smallwood J. R.
Published: March 2011

Decompression melting of hot mantle rising in the convectively driven core of the Iceland plume generates igneous crust beneath Iceland that is
c.
25 km thick. Passive decompression of mantle beneath the adjacent Reykjanes Ridge spreading centre produces crust 7–10 km thick. The decrease between Iceland and the adjacent oceanic spreading centre in crustal thickness, in basement elevation and in melting column thickness deduced from rare earth element inversions of basaltic igneous rocks, suggests that the mantle beneath the spreading centre is markedly cooler (potential temperature less than 1400°C) than in the core of the plume under Iceland (potential temperature
c.
1500 °C). We suggest that the spreading centre is fed by mantle from a cooler sheath surrounding the narrow central core of the plume under Iceland, and that the mantle cools to the south until it reaches a normal potential temperature of 1300°C about 1350 km away from the centre of the plume. Prominent V-shaped topography and gravity anomalies on the Reykjanes Ridge record variations of up to 30°C in the temperature of the underlying asthenospheric mantle supplied by the plume, over timescales of 5–10 Ma.
Discussion on palaeostresses associated with thrust sheet emplacement and related folding in the southern central Pyrenees, Huesca, Spain Journal, Vol. 152, 1995, 353–356
Authors: Turner J. P. , Hancock P. L. , Martínez-Peña M. B. , Casas-Sainz A. M. , Millán-Garrido H.
Published: March 2011

J. P. Turner & P. L. Hancock
write: We congratulate Martínez-Peña, Casas-Sainz and Millán-Garrido (1995) on their palaeostress analysis of a complex suite of mesostructures contained in several south Pyrenean thrust sheets. We agree that, in spite of the difficulty in interpreting the multi-phase deformation of thrust belts, analysis of structures from which palaeostress may be inferred yields useful information not apparent from a macro-structural study.

Like Martínez-Peña et al. (1995), we also found that the folded Oligo-Miocene molassic sedimentary rocks of the Jaca thrust-top basin contain remarkably few faults. Indeed, explaining how a near-surface structural unit has travelled 30 km or more over such an irregular tectonic topography yet without being faulted is a challenging structural question. However we are suprised that Martínez-Peña et al. (1995) found in their palaeostress results from the Cretaceous and Palaeocene carbonates to the north of the molasse basin, that: There are no great differences between stress tensors found in the hanging wall and the footwall of thrusts’. Our experience (Turner & Hancock 1989) in that part of the Jaca basin contiguous with and immediately to the west of their study area is that the assemblages of small-scale brittle structures in the immediate (within 1-3 km) hanging walls and footwalls of thrusts are distinctively different, recording locally contrasting stress regimes. In particular, our study showed that the immediate footwalls of thrusts experienced extension parallel to the strike of thrusts before they underwent extension normal to the strike of thrusts.
A redescription of
Plesiosaurus propinquus
Tate & Blake, 1876 (Reptilia, Plesiosauria), from the Lower Jurassic (Toarcian) of Yorkshire, England
Authors: Vincent P. , Smith A. S.
Published: March 2011

The type specimen (WM 851.S, skull and post-cranial skeleton) of
Plesiosaurus propinquus
Tate & Blake, 1876, from the Toarcian (Upper Lias, Lower Jurassic) of Yorkshire, is re-examined. New observations permit a detailed understanding of the cranial anatomy of this specimen and hence its taxonomic affinity. The few differences between
Plesiosaurus propinquus
and
Rhomaleosaurus zetlandicus
cannot be considered diagnostic. Consequently,
Plesiosaurus propinquus
is here assigned to and considered a junior synonym of
Rhomaleosaurus zetlandicus
. Currently only three valid species of the genus
Rhomaleosaurus
are known; a complete revision of the specimens formerly attributed to
Rhomaleosaurus
must now be carried out.
Pisocrinus
from the type Ludlow Series
Authors: Holland C. H.
Published: March 2011

A unique specimen of
Pisocrinus
?
pilula
is recorded and described from the Middle Elton Formation (Ludlow Series, Gorstian Stage) in the Ludlow district.
Landforms and the geological evolution of the Vale of York during the Late Devensian
Authors: Fairburn W. A.
Published: March 2011

Preliminary landform mapping over the York terminal moraine showed that persistent terraces on the sides of the moraine are strandlines that must have formed during regression of pro-glacial Lake Humber. Of widespread significance is a conspicuous shoreline between 30 and 35 m above OD that lasted for sufficient time to develop both erosional and depositional lacustrine terraces. This surface is contemporaneous with the 100 Foot Strandline mapped on the western side of the Vale of York, on the Permian escarpment. Between the Escrick and York moraines there are two additional major strandlines, with associated littoral and lacustrine deposits, that effectively subdivide the fluvioglacial sediments of the Vale of York into three offlapping planar landforms, with lateral erosional contacts independent of lithology. Above the 100 Foot Strandline, mounds and ridges of till form prominent landmarks, such as Severs Howe near York. The North Sea ice could not have plugged the Humber mouth until the Vale of York glacier had formed the York Moraine, and must have remained long enough for a prolonged stillstand of Lake Humber at
c.
33 m above OD. Subsequent stillstands, recorded on the southern face of the York Moraine at
c.
20 m and
c.
14 m above OD (lowering to
c.
15 m and
c.
10 m above OD at Escrick), mark stages in the unplugging of the Humber mouth from either ice or till. The mapping also suggests that the Crockey Hill ‘esker’ consists of erosional remnants, preserved on interfluves, of a fluvial gravel sheet.
John Phillips and the British Silurian Crinoidea: 170 years of monographic endeavour
Authors: Donovan S. K.
Published: March 2011

John Samuel Miller’s
A Natural History of the Crinoidea or Lily-Shaped Animals
… (1821), the first monograph of the fossil crinoids, included only three species from what we would now call the British Silurian. The first monographic study devoted to the British Silurian crinoids was by John Phillips (
in
Murchison’s
The Silurian System
, 1839), who described 14 species (eleven new), all from the Wenlock Series of the area around Dudley. These were conservatively placed in five genera,
Cyathocrinites
Miller,
Marsupiocrinites
Phillips,
Hypanthocrinites
Phillips,
Actinocrinites
Miller and
Dimerocrinites
Phillips; the same species are now divided between eleven genera. Eight of these taxa are type species, but none is now classified as either
Cyathocrinites
or
Actinocrinites. Hypanthocrinites
is a junior synonym of
Eucalyptocrinites
Goldfuss. The illustrations in Phillips, drawn by J. de C. Sowerby, were much superior to Miller’s plates, but lacked his innovative ‘exploded’ diagrams.
Carbonate facies and biostromal distribution in a tectonically controlled platform in northwest Ireland during the late Viséan (Mississippian)
Authors: Somerville Ian D. , Cózar Pedro , Aretz Markus , Herbig Hans-Georg , Mitchell W. Ian , Medina-Varea Paula
Published: March 2011

The North–West Carboniferous Basin (NWCB) contains a
c.
3 km-thick succession of Mississippian (Courceyan to Arnsbergian) limestone, mudstone and sandstone, mostly of marine origin. The litho- and biostratigraphy of some sections in the basin are revised and new logged sections described in upper Viséan, limestone-dominated platform successions. In the O’Donnell’s Rock area, a precise correlation of the Glencar Limestone Formation with the lower part of the Bricklieve Limestone Formation, and the Dartry Limestone Formation with the upper part of the Bricklieve Limestone Formation is confirmed. Consequently, in late Viséan (Asbian) times the NWCB developed as an extensive (>12,000 km
2
) carbonate platform, in which sediments of the facies typical of outer, middle and inner parts of the platform were deposited. The Asbian rocks of this platform contain abundant solitary and fasciculate rugose corals, with laterally persistent biostromes dominated by different species of
Siphonodendron
. Evidence of regional uplift and subaerial exposure occurs at the top of the Dartry Limestone/Bricklieve Limestone formations, especially in the northern half of the platform. The base of the succeeding Meenymore Formation is defined by a change from marine limestone below an erosional disconformity surface, to sediments deposited on a sabkha and in supra-tidal–peritidal facies. Evolution of the platform was controlled, in part, by syn-sedimentary faults, which allowed different thicknesses of sediment to accumulate. Between the margins of the NWCB there existed a turbid carbonate platform with relatively shallow to moderately deep water characterized by impoverished microfaunal assemblages. The platform margin extended SE into deeper water facies of the Dublin Basin.
The geology of the Corallian ridge (Upper Jurassic) between Gilling East and North Grimston, Howardian Hills, North Yorkshire
Authors: Wright J. K.
Published: March 2011

The northern edge of the Howardian Hills, running for 25 km from Gilling East to North Grimston, North Yorkshire, comprises a near-continuous ridge of Oxfordian limestones and calcareous sandstones, here termed the Corallian ridge. These strata rise gently from the Vale of Pickering up to a steep scarp face which overlooks underlying Oxford Clay to the south. The limestones and sandstones belong to the Corallian Group, which in the Howardian Hills includes the Lower Calcareous Grit, Coralline Oolite and Upper Calcareous Grit formations. The Lower Calcareous Grit Formation comprises a succession of fine-grained, calcareous or spicular, siliceous sandstones, and forms a prominent feature. The Coralline Oolite Formation underlies gently rolling hills leading down to the Vale of Pickering, and is composed of a series of oolitic and fine-grained limestones with subordinate calcareous sandstones and sandy limestones. The Upper Calcareous Grit is represented here largely by calcareous strata, the North Grimston Cementstone, and is only exposed in faulted inliers to the south. The sequence was laid down in a tectonically active area, and movement of faults during deposition of the strata in the Mid Oxfordian led to marked changes in thickness and lithology across the area. Complications caused by these penecontemporaneous movements have meant that, though the outcrop has been investigated by numerous geologists over the last 150 years, the exact sequence of strata present and its correlation with the Corallian sequence on the north side of the Vale of Pickering have long presented problems. Much that was uncertain about the geology of the area has been resolved through detailed mapping of the area west of Malton.
Chadian (Tournaisian – Viséan, Carboniferous) ammonoids from the Milldale Limestone Formation of the southern Peak District, England
Authors: Tilsley J. W. , Korn D.
Published: March 2011

Ammonoids from the Chadian Waulsortian mud-mounds of the Peak District (Derbyshire and Staffordshire) have been examined utilizing new collections and additional museum material. The genera
Fascipericyclus
,
Ammonellipsites
,
Helicocyclus
,
Dzhaprakoceras
,
Eonomismoceras
,
Polaricyclus
and
Merocanites
are present. One new species,
Eonomismoceras wettonense
sp. nov., is described. The independent status of
Fascipericyclus fasciculatus
and
F. furcatus
is confirmed.
Hyperbaric hyperoxia reduces exercising forearm blood flow in humans
Authors: Casey Darren P. , Joyner Michael J. , Claus Paul L. , Curry Timothy B.
Published: March 2011

Hypoxia during exercise augments blood flow in active muscles to maintain the delivery of O2 at normoxic levels. However, the impact of hyperoxia on skeletal muscle blood flow during exercise is not completely understood. Therefore, we tested the hypothesis that the hyperemic response to forearm exercise during hyperbaric hyperoxia would be blunted compared with exercise during normoxia. Seven subjects (6 men/1 woman; 25 ± 1 yr) performed forearm exercise (20% of maximum) under normoxic and hyperoxic conditions. Forearm blood flow (FBF; in ml/min) was measured using Doppler ultrasound. Forearm vascular conductance (FVC; in ml·min−1·100 mmHg−1) was calculated from FBF and blood pressure (in mmHg; brachial arterial catheter). Studies were performed in a hyperbaric chamber with the subjects supine at 1 atmospheres absolute (ATA) (sea level) while breathing normoxic gas [21% O2, 1 ATA; inspired Po2 (PiO2) ≈ 150 mmHg] and at 2.82 ATA while breathing hyperbaric normoxic (7.4% O2, 2.82 ATA, PiO2 ≈ 150 mmHg) and hyperoxic (100% O2, 2.82 ATA, PiO2 ≈ 2,100 mmHg) gas. Resting FBF and FVC were less during hyperbaric hyperoxia compared with hyperbaric normoxia ( P < 0.05). The change in FBF and FVC (Δ from rest) during exercise under normoxia (204 ± 29 ml/min and 229 ± 37 ml·min−1·100 mmHg−1, respectively) and hyperbaric normoxia (203 ± 28 ml/min and 217 ± 35 ml·min−1·100 mmHg−1, respectively) did not differ ( P = 0.66–0.99). However, the ΔFBF (166 ± 21 ml/min) and ΔFVC (163 ± 23 ml·min−1·100 mmHg−1) during hyperbaric hyperoxia were substantially attenuated compared with other conditions ( P < 0.01). Our data suggest that exercise hyperemia in skeletal muscle is highly dependent on oxygen availability during hyperoxia.
Myostatin from the heart: local and systemic actions in cardiac failure and muscle wasting
Authors: Breitbart Astrid , Auger-Messier Mannix , Molkentin Jeffery D. , Heineke Joerg
Published: March 2011

A significant proportion of heart failure patients develop skeletal muscle wasting and cardiac cachexia, which is associated with a very poor prognosis. Recently, myostatin, a cytokine from the transforming growth factor-β (TGF-β) family and a known strong inhibitor of skeletal muscle growth, has been identified as a direct mediator of skeletal muscle atrophy in mice with heart failure. Myostatin is mainly expressed in skeletal muscle, although basal expression is also detectable in heart and adipose tissue. During pathological loading of the heart, the myocardium produces and secretes myostatin into the circulation where it inhibits skeletal muscle growth. Thus, genetic elimination of myostatin from the heart reduces skeletal muscle atrophy in mice with heart failure, whereas transgenic overexpression of myostatin in the heart is capable of inducing muscle wasting. In addition to its endocrine action on skeletal muscle, cardiac myostatin production also modestly inhibits cardiomyocyte growth under certain circumstances, as well as induces cardiac fibrosis and alterations in ventricular function. Interestingly, heart failure patients show elevated myostatin levels in their serum. To therapeutically influence skeletal muscle wasting, direct inhibition of myostatin was shown to positively impact skeletal muscle mass in heart failure, suggesting a promising strategy for the treatment of cardiac cachexia in the future.
Cardioprotective effect of the PPAR ligand tetradecylthioacetic acid in type 2 diabetic mice
Authors: Khalid Ahmed M. , Hafstad Anne Dragøy , Larsen Terje S. , Severson David L. , Boardman Neoma , Hagve Martin , Berge Rolf K. , Aasum Ellen
Published: March 2011

Tetradecylthioacetic acid (TTA) is a novel peroxisome proliferator-activated receptor (PPAR) ligand with marked hypolipidemic and insulin-sensitizing effects in obese models. TTA has recently been shown to attenuate dyslipidemia in patients with type 2 diabetes, corroborating the potential for TTA in antidiabetic therapy. In a recent study on normal mice, we showed that TTA increased myocardial fatty acid (FA) oxidation, which was associated with decreased cardiac efficiency and impaired postischemic functional recovery. The aim of the present study was, therefore, to elucidate the effects of TTA treatment (0.5%, 8 days) on cardiac metabolism and function in a hyperlipidemic type 2 diabetic model. We found that TTA treatment increased myocardial FA oxidation, not only in nondiabetic ( db/+) mice but also in diabetic ( db/db) mice, despite a clear lipid-lowering effect. Although TTA had deleterious effects in hearts from nondiabetic mice (decreased efficiency and impaired mitochondrial respiratory capacity), these effects were not observed in db/db hearts. In db/db hearts, TTA improved ischemic tolerance, an effect that is most likely related to the antioxidant property of TTA. The present study strongly advocates the need for investigation of the cardiac effects of PPAR ligands used in antidiabetic/hypolipidemic therapy, because of their pleiotropic properties.
Transient hypercapnic stress causes exaggerated and prolonged elevation of cardiac and renal interstitial norepinephrine levels in conscious hypertensive rats
Authors: Sobajima Mitsuo , Nozawa Takashi , Nakadate Teruo , Shida Takuya , Ohori Takashi , Suzuki Takayuki , Matsuki Akira , Hirai Tadakazu , Inoue Hiroshi
Published: March 2011

The responses of sympathetic nerve activity to transient stress can be exaggerated in salt-sensitive (SS), hypertensive subjects. Cardiac and renal interstitial norepinephrine (iNE) levels during and after transient hypercapnia were investigated in conscious SS rats. Dahl SS and salt-resistant (SR) 6-wk-old rats were fed a high-salt diet, and at 12 wk iNE levels in the heart and kidney were determined using microdialysis with probes inserted in the left ventricular (LV) wall and kidney. A telemetry system determined blood pressure and heart rate (HR) in separate animals. After recovery from the operation, data were collected before, during, and after exposure to normoxic 10% CO2 for 25 min under unanesthetized conditions. The plasma NE concentrations at baseline did not differ between the two strains. Both cardiac and renal iNE levels were much higher in SS rats than in SR rats at baseline as well as during hypercapnic stress. After stress, the markedly increased iNE levels of SS rats were prolonged in the LV as well as in the kidney. During hypercapnic stress, HR decreased in both SS and SR rats, while sudden increases in HR immediately after the withdrawal from stress were followed by its slower reduction in SS rats compared with SR rats. In conclusion, transient hypercapnic stress causes exaggerated and prolonged elevation of iNE levels in the heart as well as in kidneys of SS animals.
Enhancing AMPK activation during ischemia protects the diabetic heart against reperfusion injury
Authors: Paiva Marta A. , Rutter-Locher Zoe , Gonçalves Lino M. , Providência Luís A. , Davidson Sean M. , Yellon Derek M. , Mocanu Mihaela M.
Published: March 2011

AMPK activation during ischemia helps the myocardium to cope with the deficit of energy production. As AMPK activity is considered to be impaired in diabetes, we hypothesized that enhancing AMPK activation during ischemia above physiological levels would protect the ischemic diabetic heart through AMPK activation and subsequent inhibition of mitochondrial permeability transition pore (mPTP) opening. Isolated perfused hearts from normoglycemic Wistar or diabetic Goto-Kakizaki (GK) rats ( n ≥ 6/group) were subjected to 35 min of ischemia in the presence of 10, 20, and 40 μM of A-769662, a known activator of AMPK, followed by 120 min of reperfusion with normal buffer. Myocardial infarction and AMPK phosphorylation were assessed. The effect of A-769662 on mPTP opening in adult cardiomyocytes isolated from both strains was also determined. A-769662 at 20 μM reduced infarct size in both Wistar (30.5 ± 2.7 vs. 51.8 ± 3.9% vehicle; P < 0.001) and GK hearts (22.7 ± 3.0 vs. 48.5 ± 4.7% vehicle; P < 0.001). This protection was accompanied by a significant increase in AMPK and GSK-3β phosphorylation. In addition, A-769662 significantly inhibited mPTP opening in both Wistar and GK cardiomyocytes subjected to oxidative stress. We demonstrate that AMPK activation during ischemia via A-769662 reduces myocardial infarct size in both the nondiabetic and diabetic rat heart. Furthermore, this cardioprotective effect appears to be mediated through inhibition of mPTP opening. Our findings suggest that improving AMPK activation during ischemia can be another mechanism for protecting the ischemic heart.