bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic signatures of intermediate divergence: population history of Old and New World Holarctic ravens (Corvus corax)
Authors: OMLAND KEVIN E. , BAKER JASON M. , PETERS JEFFREY L. 
Published: January 2006

AbstractMany studies of phylogeography, speciation, and species limits restrict their focus to a narrow issue: gene tree monophyly. However, reciprocal monophyly does not provide an ideal touchstone criterion of any aspect of evolutionary divergence. There is a continuum of divergence stages as isolated populations go from initial allele frequency differences to well‐differentiated species. Studying intermediate stages of divergence will increase our understanding of geographical speciation, species limits, and conservation priorities. We develop a conceptual framework and terminology for thinking about the stages of ‘intermediate polyphyly’. The Holarctic clade of common ravens (Corvus corax), found throughout much of Eurasia and North America, provides a case study of these stages of intermediate divergence. We used coalescent, phylogenetic, and population genetic methods to investigate the history and current status of this Old World–New World distribution using 107 mitochondrial control region sequences. Phylogenetically, New World and Old World samples are intermixed. However, most samples are grouped into small subclades that are restricted to either the New World or the Old World, and only one haplotype is shared between the hemispheres. Analysis of moleculalr variance (amova) results reflect this low haplotype sharing between hemispheres (ΦST = 0.13, P < 0.01). Isolation with Migration (im) coalescent results suggest a sustained period of divergence between the hemispheres and low levels of maternal gene flow. Although there has not been sufficient time to evolve reciprocal monophyly and some gene flow may occur, New World and Old World ravens are genetically quite distinct. We use this example to demonstrate these early stages of divergence as populations go from sharing only internal haplotypes, to sharing no haplotypes, to having population specific subclades. Studies of phylogeography, speciation and systematics will benefit from increased attention to these stages of intermediate polyphyly.
Specificity of the trypanothione‐dependent Leishmania major glyoxalase I: structure and biochemical comparison with the human enzyme
Authors: Ariza Antonio , Vickers Tim J. , Greig Neil , Armour Kirsten A. , Dixon Mark J. , Eggleston Ian M. , Fairlamb Alan H. , Bond Charles S. 
Published: January 2006

SummaryTrypanothione replaces glutathione in defence against cellular damage caused by oxidants, xenobiotics and methylglyoxal in the trypanosomatid parasites, which cause trypanosomiasis and leishmaniasis. In Leishmania major, the first step in methylglyoxal detoxification is performed by a trypanothione‐dependent glyoxalase I (GLO1) containing a nickel cofactor; all other characterized eukaryotic glyoxalases use zinc. In kinetic studies L. major and human enzymes were active with methylglyoxal derivatives of several thiols, but showed opposite substrate selectivities: N1‐glutathionylspermidine hemithioacetal is 40‐fold better with L. major GLO1, whereas glutathione hemithioacetal is 300‐fold better with human GLO1. Similarly, S‐4‐bromobenzylglutathionylspermidine is a 24‐fold more potent linear competitive inhibitor of L. major than human GLO1 (Kis of 0.54 µM and 12.6 µM, respectively), whereas S‐4‐bromobenzylglutathione is > 4000‐fold more active against human than L. major GLO1 (Kis of 0.13 µM and > 500 µM respectively). The crystal structure of L. major GLO1 reveals differences in active site architecture to both human GLO1 and the nickel‐dependent Escherichia coli GLO1, including increased negative charge and hydrophobic character and truncation of a loop that may regulate catalysis in the human enzyme. These differences correlate with the differential binding of glutathione and trypanothione‐based substrates, and thus offer a route to the rational design of L. major‐specific GLO1 inhibitors.
Mechanism of polarization of Listeria monocytogenes surface protein ActA
Authors: Rafelski Susanne M. , Theriot Julie A. 
Published: January 2006

SummaryThe polar distribution of the ActA protein on the surface of the Gram‐positive intracellular bacterial pathogen, Listeria monocytogenes, is required for bacterial actin‐based motility and successful infection. ActA spans both the bacterial membrane and the peptidoglycan cell wall. We have directly examined the de novo ActA polarization process in vitro by using an ActA–RFP (red fluorescent protein) fusion. After induction of expression, ActA initially appeared at distinct sites along the sides of bacteria and was then redistributed over the entire cylindrical cell body through helical cell wall growth. The accumulation of ActA at the bacterial poles displayed slower kinetics, occurring over several bacterial generations. ActA accumulated more efficiently at younger, less inert poles, and proper polarization required an optimal balance between protein secretion and bacterial growth rates. Within infected host cells, younger generations of L. monocytogenes initiated motility more quickly than older ones, consistent with our in vitro observations of de novo ActA polarization. We propose a model in which the polarization of ActA, and possibly other Gram‐positive cell wall‐associated proteins, may be a direct consequence of the differential cell wall growth rates along the bacterium and dependent on the relative rates of protein secretion, protein degradation and bacterial growth.
The chromosomal relBE2 toxin–antitoxin locus of Streptococcus pneumoniae: characterization and use of a bioluminescence resonance energy transfer assay to detect toxin–antitoxin interaction
Authors: Nieto Concha , Pellicer Teresa , Balsa Dolors , Christensen Suzanne K. , Gerdes Kenn , Espinosa Manuel 
Published: January 2006

SummaryProteic toxin–antitoxin (TA) loci were first identified in bacterial plasmids, and they were regarded as involved in stable plasmid maintenance by a so‐called ‘addiction’ mechanism. Later, chromosomally encoded TA loci were identified and their function ascribed to survival mechanisms when bacteria were subjected to stress. In the search for chromosomally encoded TA loci in Gram‐positive bacteria, we identified various in the pathogen Streptococcus pneumoniae. Two of these cassettes, sharing homology with the Escherichia coli relBE locus were cloned and tested for their activity. The relBE2Spn locus resulted to be a bona fide TA locus. The toxin exhibited high toxicity towards E. coli and S. pneumoniae, although in the latter, the chromosomal copy of the antitoxin relB2Spn gene had to be inactivated to detect full toxicity. Cell growth arrest caused by expression of the relE2Spn toxin gene could be reverted by expression of the cognate antitoxin, relB2Spn, although prolonged exposition to the toxin led to cell death. The pneumococcal relBE2Spn locus is the first instance of a chromosomally encoded TA system from Gram‐positive bacteria characterized in its own host. We have developed a bioluminescence resonance energy transfer (BRET) assay to detect the interactions between the RelB2Spn antitoxin and the RelE2Spn toxin in vivo. This technique has shown to be amenable to a high‐throughput screening (HTS), opening new avenues in the search of molecules with potential antibacterial activity able to inhibit TA interactions.
Sedimentary response to a tectonically induced sea‐level fall in a shallow back‐arc basin: the Mulichinco Formation (Lower Cretaceous), Neuquén Basin, Argentina
Authors: SCHWARZ ERNESTO , SPALLETTI LUIS A. , HOWELL JOHN A. 
Published: January 2006

AbstractThis study examines the sedimentary response to a tectonically driven relative sea‐level fall that occurred in the Neuquén Basin, west‐central Argentina, during the late Early Valanginian (Early Cretaceous). At this time the basin lay behind the emergent Andean magmatic arc to the west. Following the relative sea‐level fall, sedimentation was limited to the central part of the Neuquén Basin, with the deposition of a predominantly clastic, continental to shallow marine wedge on top of basinal black shales. This lowstand wedge is called the Mulichinco Formation and consists of a third‐order sequence that lasted about 2 Myr and contains high frequency lowstand, transgressive, and highstand deposits. Significant variations in facies, depositional architecture, and internal organization of the sequence occur along depositional strike. These variations are attributed mainly to tectonic and topographic controls upon sediment flux, basin gradient, fault tilting, and shifting of the depocentre through time. These controls were ultimately related to asymmetrically distributed tectonic activity that was greater towards the magmatic arc in the west. The superposition of fluvial deposits directly upon offshore facies provides unequivocal evidence for a sequence boundary at the base of the Mulichinco Formation. However, the Mulichinco sequence boundary is marked by shallow, low erosional relief and widespread fluvial deposition. The surface lacks prominent valleys traditionally associated with sequence boundaries. This non‐erosive sequence boundary geometry is attributed to the ramp‐type geometry of the basin and/or rapid uplift that limited stratigraphic adjustment to base‐level fall. Significant along‐strike facies changes and a low‐relief sequence boundary are attributes that may be common in tectonically active, semi‐enclosed basins (e.g. shallow back‐arc basins, foreland basins).
An investigation of subglacial processes at the microscale from Briksdalsbreen, Norway
Authors: HART JANE K. 
Published: January 2006

AbstractThe subglacial processes at Briksdalsbreen, Norway, are examined by a combination of sedimentology, thin section and scanning electron microscope (SEM) analysis of till samples from an exposed subglacial surface and from beneath the glacier. Studies of a fluted surface indicate that subglacial deformation is occurring on a field scale with flutes forming behind most clasts 0·6 m high. At the thin section scale (0·014–2·0 mm) it is seen that deformation is by rotation and attenuation and is dependent on till texture. At the SEM scale (0·1–0·4 mm) it is seen that erosion is controlled by abrasion and percussion which produces distinct grain ‘styles’ as part of an erosional continuum. Overall it is shown that rotation and attenuation is a dominant process at all scales and that the clast interactions associated with different scale perturbations within the shear zone control erosion and deposition, as well as landform and fabric production.
Oligocene to Present kilometres scale subsidence and exhumation of the Ligurian Alps and the Tertiary Piedmont Basin (NW Italy) revealed by apatite (U–Th)/He thermochronology: correlation with regional tectonics
Authors: Bertotti Giovanni , Mosca Pietro , Juez Joaquim , Polino Riccardo , Dunai Tibor 
Published: January 2006

AbstractThe Ligurian Alps segment of the Alpine–Apennine orogen in NW Italy is unconformably covered by Upper Eocene to Holocene sediments in the Tertiary Piedmont Basin (TPB) and Po Plain. These sediments dip towards the north demonstrating the erosional nature of the southern border of the succession and implying that the adjacent orogenic belt formed the substratum rather than the margin of the sedimentary basin. Apatite (U–Th)/He and fission track thermochronology shows that the orogen first subsided and was buried at >4 km from 30 to 26 Ma and began its exhumation thereafter. From 26 Ma to present, this upward movement was contemporaneous with subsidence in the northern TPB. The couple exhumation in the S and subsidence in the N migrated northwards through time. Vertical movements in the area are similar to those reconstructed in Corsica. In both cases, the onset of exhumation becomes younger away from the Ligurian‐Provençal basin and has little correlation with the opening of the surrounding oceanic basins.
Gravitational spreading and formation of new rift zones on overlapping volcanoes
Authors: Walter Thomas R. , Klügel Andreas , Münn Sebastian 
Published: January 2006

AbstractLarge volcanic edifices are often shaped by the coalescence of adjacent volcanoes as well as intrusive rift zones and gravitational spreading. To better understand the structure of such volcanoes we designed analogue experiments simulating gravitational spreading of an edifice made by overlapping cones of different age, and examined the formation of rift zones. The results allow distinction of two main rift geometries. (i) Spreading edifices of similar age that partly overlap, tend to develop a rift zone approximately perpendicular to the boundary of both volcanoes. Such a rift zone causes two volcanoes to grow together and form an elongated topographic ridge. (ii) Partly overlapping volcanoes of different age are spreading at different rates and thus form a rift zone parallel to the boundary of both volcanoes. Such a rift zone causes two volcanoes to structurally separate. The results are widely applicable for large volcanoes subject to rifting and flank spreading, which we demonstrate for Réunion Island and for southern Hawaii.
Two unknown M > 6 historical earthquakes revealed by palaeoseismological and archival researches in eastern Calabria (southern Italy). Seismotectonic implications
Authors: Galli P. , Scionti V. 
Published: January 2006

AbstractThe seismicity of Calabria is among the strongest in the whole of the Mediterranean, but is now well known on its Ionian side. Palaeoseismological investigations in eastern Calabria and archival research have tried to shed light on earthquake recurrence and seismogenetic source geometry. Trench investigation across the Lakes fault (Sila massif) shows this fault to be definitively responsible for the Mw = 6.7, 1638 earthquake, and provides a well‐constrained age range for its penultimate event (early 7th century AD). On the other hand, after research in local and national archives, another previously unknown relevant historical earthquake has been discovered (1744, Mw = 6.2), which struck an area conterminous to the SE tip of the Lakes fault. We hypothesize a NW–SE active Sila fault system that accommodates regional ∼N–S extension through normal‐to‐sinistral segments, each one capable of generating earthquakes with magnitude in the range of 6.2–6.7. Since 1638, this system ruptured almost entirely from NW towards SE (1638–1744–1832), with the exception of the northwestern segment, the ‘silent’ Cecita fault.
A Seminoma in a Monorchid Guinea Fowl (Numida meleagris)
Authors: Kurkure N. V. , Pande V. V. , Thomas F. , Bhandarkar A. G. 
Published: January 2006

SummaryA case of seminoma in a monorchid adult guinea fowl (Numida meleagris) is described. Grossly, a right enlarged testis, which was soft in consistency, and white to pale in colour with few spots of haemorrhages was observed. Histologically, the testicle revealed diffusely spread sheets of tumour cells. The cells were large pleomorphic with eccentrically placed hyperchromic nuclei. Mitotic figures were evident. A scanty fibrous stroma, containing lymphocytes and histiocytes, separating the groups of tumour cells, along with few areas of haemorrhages were observed. Occurrence of seminoma in guinea fowl is unusual and hence reported.
Equine Culicoides Hypersensitivity: Evaluation of a Skin Test and of Humoral Response
Authors: Ferroglio E. , Pregel P. , Accossato A. , Taricco I. , Bollo E. , Rossi L. , Trisciuoglio A. 
Published: January 2006

SummaryIntradermal tests were carried out on 18 horses with clinical signs of Culicoides hypersensitivity (CHS) and 23 horses without clinical signs of CHS, and sera from these horses were analysed by SDS‐PAGE and Western blotting (W‐B). Intradermal injections of 0.1 ml of 25 μg/μl sterile Culicoides extract, 0.1 ml of 1 : 10 000 histamine (positive control) and 0.1 ml of physiological saline (negative control) were made in the dermis of the middle region of the neck. Analysis of reactions indicated that a 1 cm wheal and a skinfold thickness >10% at 24 h represented a valid cut‐off between horses with and without CHS. In these conditions the test, even in winter when clinical signs were absent, had 100% sensitivity and specificity. The W‐B was performed after running Culicoides extract on a 12% polyacrylamide gel. The test revealed the presence of several bands with molecular weight ranging from 6 to 200 kDa. In particular, a band of 65 kDa was predominantly found in hypersensitive horses by using an anti‐IgE antibody while in normal horses the same band was mainly detected by using an anti‐IgG antibody. Our results demonstrated that the skin test is a valid diagnostic test, with high sensitivity and specificity and that the band of about 65 kDa probably corresponds to the allergen involved in the pathogenesis of CHS.
Transgenic rice lines expressing maize C1 and R‐S regulatory genes produce various flavonoids in the endosperm
Authors: Shin Young‐Mi , Park Hee‐Jin , Yim Sun‐Duck , Baek Nam‐In , Lee Choong‐Hwan , An Gynheung , Woo Young‐Min 
Published: January 2006

SummaryFlavonoids, compounds that possess diverse health‐promoting benefits, are lacking in the endosperm of rice. Therefore, to develop transgenic lines that produce flavonoids, we transformed a white rice cultivar, Oryza sativa japonica cv. Hwa‐Young, with maize C1 and R‐S regulatory genes. Expression of these transgenes was restricted to the endosperm using the promoter of a rice prolamin gene. The pericarp of the C1/R‐S homozygous lines became dark brown in accordance with their maternal genotype, whereas the endosperm turned chalky, similar to the opaque kernel phenotype. Analysis via high‐performance liquid chromatography (HPLC) revealed that numerous kinds of flavonoids were produced in these transgenic kernels. To identify individual flavonoids, the number of HPLC peaks was reduced through moderate acid hydrolysis, followed by ethyl acetate partitioning. Amongst the major flavonoids, dihydroquercetin (taxifolin), dihydroisorhamnetin (3′‐O‐methyl taxifolin) and 3′‐O‐methyl quercetin were identified through liquid chromatography/mass spectrometry/mass spectrometry and nuclear magnetic resonance analyses. Fluorescence labelling with diphenylboric acid showed that the flavonoids were highly concentrated in the cells of four to five outer endosperm layers. More importantly, a high fluorescence signal was present in the cytosol of the inner endosperm layers. However, the overall signal in the inner layers was significantly lower because starch granules and protein bodies occupied most of the cytosolic space. Our estimate of the total flavonoid content in the transgenic kernels suggests that C1/R‐S rice has the potential to be developed further as a novel variety that can produce various flavonoids in its endosperm.
PRODUCTIVE GOVERNMENT EXPENDITURE IN MONETARY BUSINESS CYCLE MODELS
Authors: Linnemann Ludger , Schabert Andreas 
Published: January 2006

ABSTRACTThis paper assesses the transmission of fiscal policy shocks in a New Keynesian framework where government expenditures contribute to aggregate production. It is shown that even if the impact of government expenditures on production is small, this assumption helps to reconcile the models' predictions about fiscal policy effects with recent empirical evidence. In particular, it is shown that government expenditures can lead to a rise in private consumption, real wages, and employment if the government share is not too large and public finance does not solely rely on distortionary taxation. When government expenditures are partially financed by public debt, unit labor costs fall in response to a fiscal expansion, such that inflation tends to decline. Households are willing to raise consumption if monetary policy is active, i.e. ensures that the real interest rate rises with inflation. Otherwise, private consumption can also be crowded out, as in the conventional case where government expenditures are not productive.
Manorial economy and corvée labour in southern Sweden 1650–1850*
Authors: OLSSON MATS 
Published: January 2006

SUMMARYThis essay is an inquiry into manorial production in Scania. Its growth was dependent on the long‐term development of European grain prices. When prices increased landlords were encouraged to put more land under the plough. The estates’ main income came, to an increasing extent, from demesne production, which finally dominated the income profile. The peasants’ most important contribution to the landlords became, in most cases, their corvée labour, and their uncertain tenure rights were illustrated with great clarity in the continuing evictions, which were accelerated in the nineteenth century with the aim of expanding the demesne.
Apolipoprotein E polymorphism and lipoprotein compositions in normolipidaemic xanthelasma patients
Authors: Tursen U , Eskandari G , Kaya Ti , Tamer L , Ikizoglu G , Atik U 
Published: January 2006

AbstractBackground  Apolipoprotein E (apoE) phenotypes and lipoprotein compositions in xanthelasma patients have been reported in different series.Objective  To investigate the apoE polymorphism and lipoprotein compositions in xanthelasma patients by using rapid polymerase chain reaction, and searched for an association between apoE polymorphism and the lipoprotein levels in xanthelasma patients.Design  ApoE polymorphism and the different types of serum lipoproteins were studied in 25 patients with xanthelasma and compared with 27 normal subjects.Results  All of patients were found to be normolipidaemic. The patients had significantly higher concentrations of total cholesterol and apolipoprotein B, and lower concentrations of apolipoprotein A. There was no difference in serum triglyceride, low‐density lipoprotein (LDL) and high‐density lipoprotein (HDL) cholesterol concentrations. The distribution of apoE genotypes and alleles was the same in both groups.Conclusions  The apoB, apoA and cholesterol levels did show statistically significant differences in the direction of an increased risk of atherosclerosis. Patients with xanthelasma demonstrated slight differentiations in the apoE polymorphism and metabolism of lipoproteins that require further clarifications.
Carbohydrate storage in five resprouting Florida scrub plants across a fire chronosequence
Authors: Olano J. M. , Menges E. S. , Martínez E. 
Published: January 2006

Summary

Most research analyzing nonstructural carbohydrate (NSC) concentrations on resprouter species in fire‐controlled ecosystems has concentrated on how NSC concentrations recover immediately after fire. However, we know little of the effect of long periods without fire on NSC concentrations.
In order to assess the effect of different periods of time‐since‐fire on resprouter species, we studied carbohydrate concentrations (total [NSC], soluble sugars [SS] and nonsoluble sugars [NSS]) in five resprouting species with contrasting trends of abundance across a chronosequence of time‐since‐fire (0.5–40 yr) in Florida.
Carbohydrate concentrations were highest in species with specialized reserve organs. [SS] was mainly explained by factors related to plant size, whereas time‐since‐fire was the main factor explaining [NSS]. Changes in [NSS] and [NSC] were correlated with the time‐since‐fire abundance patterns.
Variation in [NSS] carbohydrates can be related to the structural development of vegetation, with only those species capable of accessing full light able to accumulate carbohydrates, whereas subordinate plants show reductions in the [NSS] carbohydrate fractions. In areas with long intervals between fires, this carbohydrate reduction could affect subsequent postfire resprouting vigour, although this remains to be confirmed.