bluuebunny/crossref_metadata_2025 huggingface dataset:
Age and biostratigraphy of Early Cambrian tuffs from SE Australia and southern China
Authors: Jenkins R.J.F. , Cooper J.A. , Compston W.
Published: May 2008

Reassessment of faunal discoveries in the Fleurieu Peninsula, South Australia, shows that the Sellick Hill tuff is late Atdabanian or early Botomian in age and is preceded by Tommotian to Atdabanian equivalents. Previous and new sensitive high-resolution ion microprobe (SHRIMP) zircon ages from the tuff have been adjusted for Pb loss in the reference zircon, and mixture-modelling has been applied to resolve inheritance and Pb loss. The revised tuff age is now 522.0 ± 2.0 Ma (
σ
), 0.7% younger than the original estimate. Undocumented SHRIMP ages for zircons from a middle to upper Botomian tuff near Cymbric Vale were cited in 1994 as a single 525 ± 4 Ma population, but reprocessing using the present approach shows instead that the correct age of volcanism is 517.8 ± 2.1 Ma (
σ
). Reprocessed and new SHRIMP ages for zircons from tuff within Bed 5 of the Lower Cambrian Meishucun section, South China, give a revised age for the earlier Tommotian of 538.2 ± 1.5 Ma (
σ
). We agree with US workers that the stratotypic lowest Cambrian sequence of Newfoundland correlates within the Nemakit–Daldynian of Siberia. These results agree broadly with the Early Cambrian time scale based on zircon U–Pb isotope dilution data, but differences remain that arise more from interpretations of biostratigraphy and from the preservation and origin of the sampled zircon grains than from instrumental accuracy. In particular, the increased duration for the Tommotian indicated by our results supports notions of a more gradualistic evolution attending the origins of animal skeletons.
Heterogeneous exhumation in the Inner Moray Firth, UK North Sea: constraints from new AFTA
®
and seismic data
Authors: Argent J.D. , Stewart S.A. , Green P.F. , Underhill J.R.
Published: May 2008

Integration of regional seismic interpretation, sonic velocity, vitrinite reflectance and apatite fission-track analysis (AFTA
®
) studies has demonstrated that the western region of the Moray Firth rift arm (UK North Sea) experienced pronounced exhumation during the Cenozoic. Although this basin is usually considered to have experienced regionally uniform exhumation, interpretation of new seismic data has revealed the presence of a major system of post-Jurassic normal faults, with throws commonly in the range of 10–300 m and locally exceeding 1 km. New, high-quality seismic data are used in combination with AFTA and vitrinite reflectance data to investigate the role of extensional faulting during exhumation of this basin. Results of this interpretation not only confirm the offsets across major faults, but also show that greater exhumation and erosion occurred on their footwalls than on their hanging walls. We conclude that the localized, differential exhumation is the result of superposition of local or short-spatial-wavelength extensional tectonics upon regional, long-spatial-wavelength exhumation. These results suggest that differential exhumation might be characteristic of unroofed rift basins where normal faults subcrop the exhumation-related unconformity and that, in such cases, thermal histories from footwall locations may yield inaccurate predictions of the burial history of hanging-wall depocentres. Inaccurate burial histories will lead to a misrepresentation of the thermal history, with an impact on the estimation of hydrocarbon source rock maturity for petroleum basins.
The Beyşehir–Hoyran–Hadim Nappes: genesis and emplacement of Mesozoic marginal and oceanic units of the northern Neotethys in southern Turkey
Authors: ANDREW THEO , ROBERTSON ALASTAIR H. F
Published: May 2008

The Beyşehir–Hoyran–Hadim Nappes crop out over 700 km from NW to SE. Above a regionally autochthonous Tauride carbonate platform the Beyşehir–Hoyran Nappes begin with a thrust sheet (
c
. 400 m) of mainly redeposited carbonates, quartzose sandstones and mudstones of Mid–Late Triassic age, interpreted as a proximal slope–base-of-slope succession. Above is a thrust sheet (
c
. 1 km) of Middle–Upper Triassic intermediate–acidic extrusive rocks, volcaniclastic rocks and minor pelagic carbonates, interpreted as a continental rift. Thin (<100 m) Upper Triassic–Upper Cretaceous pelagic carbonate and radiolarian chert lie depositionally above. The uppermost thrust sheet comprises broken formation and mélange, including Jurassic shallow-water carbonate, radiolarian chert and Upper Cretaceous pelagic limestone. Zones of tectonic–sedimentary mélange separate higher units. The Beyşehir–Hoyran Nappes document Triassic rifting and Jurassic–Cretaceous passive margin subsidence bordering the Northern Neotethys. A harzburgitic ophiolite probably formed above a north-dipping subduction zone within the ocean basin. The ophiolite was emplaced southwards onto the northern margin of the Tauride platform in latest Cretaceous time. The nappe pile and underlying platform (Hadim Nappe) were thrust further south in Late Eocene time. Assuming in-sequence thrusting, the Beyşehir–Hoyran Nappes restore to a location north of a Neotethyan spreading axis. More probably, they originated near the south margin of the Northern Neotethys, but reached their position by out-of-sequence thrusting. Formation within a southerly strand of the Northern Neotethys (Inner Tauride ocean) is more probable than within the main Northern Neotethys further north.
Fossil plants from the Eocene London Clay: the use of pyrite textures to determine the mechanism of pyritization
Authors: Grimes Stephen T. , Davies Kevin L. , Butler Ian B. , Brock Fiona , Edwards Dianne , Rickard David , Briggs Derek E. G. , Parkes R. John
Published: May 2008

Pyritized twigs and roots from the Eocene London Clay of SE England were studied to gain a better understanding of the process of pyritization by investigating pyrite textures in relation to cell type and quality of preservation. Highly polished sections and fractured surfaces taken from 124 specimens were examined using optical microscope and SEM, the latter equipped to map pyrite and carbon. Pyrite textures include microcrystalline, framboidal, massive polycrystalline, and subhedral or euhedral forms. The highest fidelity of preservation is always associated with microcrystalline pyrite precipitation on wall surfaces with subsequent infilling of cells with framboids or polyhedra preventing compression during burial but contributing nothing to actual ultrastructural preservation. Ultrastructurally, parenchymatous cell walls are coalified, whereas microcrystalline pyrite plus coalified material were observed within lignified cell walls. In all, four stages of pyritization are documented. Observations are interpreted in the light of recent experiments on pyritization of living material and the chemistry of pyrite formation in anoxic environments involving an aqueous, and hence mobile, FeS cluster complex as a precursor. The complexity of the fossilization process is reflected in the presence of different textures in adjacent cells of the same tissue. This demonstrates the development of isolated chemical microenvironments as pH and Eh vary in response to decay, and mineralization and pyrite overgrowths within a cell indicate local microenvironmental changes through time.
Anticlockwise and clockwise rotations of the Eastern Variscides accommodated by dextral lithospheric wrenching: palaeomagnetic and structural evidence
Authors: Edel J.B. , Schulmann K. , Holub F.V.
Published: May 2008

New palaeomagnetic data from Lower Carboniferous granitoids of the orogenic root of the eastern Variscan belt (Moldanubian domain) show a polyphase palaeomagnetic record. Comparison of the data with existing palaeomagnetic measurements from Lower Palaeozoic sequences of the Bohemian Massif demonstrates a Carboniferous remagnetization of these latter units. All the data presented suggest that the Saxothuringian basement, the Moldanubian orogenic root system as well as the eastern Neoproterozoic Brunovistulian basement were already assembled during the Early Carboniferous. The whole Variscan belt subsequently rotated in a clockwise direction during Mid–Late Carboniferous times. Structural and geochronological data indicate that this rotation was accompanied by large-scale dextral wrenching along NW–SE-trending lithospheric faults. In a first stage, the blocks limited by wrench-faults rotated anticlockwise in bookshelf manner. The data presented rule out the existing model of oroclinal bending of the Rhenohercynian zone at the eastern termination of the Variscan belt.
Offshore debris avalanches at Somma–Vesuvius volcano (Italy): implications for hazard evaluation
Authors: Milia Alfonsa , Torrente Maurizio M. , Zuppetta Agostino
Published: May 2008

Somma–Vesuvius is an active volcano with a breached crater close to the continental shelf of Naples Bay, Italy. The interpretation of high-resolution seismic profiles offshore of Somma–Vesuvius shows interlayered volcanic and marine units in the Late Quaternary succession. In particular, the detailed seismo-stratigraphic analysis permitted, for the first time, the identification and mapping of two thick debris avalanche deposits located on the continental shelf. With a volume of 2.9 km
3
, the older debris avalanche, linked to the 18 ka Pomici di Base plinian eruption, was emplaced in a subaerial environment and then overlain by the sedimentary deposits of the lowstand prograding wedge. The younger debris avalanche, linked to the 3.4 ka Avellino plinian eruption, has a volume of
c
. 1 km
3
and is interlayered within the marine sediments deposited during the sea-level highstand. The identification of two debris avalanches originating from Somma–Vesuvius has two important implications: (1) the occurrence of two sector collapses in the history of Somma–Vesuvius volcano; (2) a potential volcano slope failure and consequent tsunamis produced by the entry of a debris avalanche into Naples Bay should be considered in the volcanic hazard evaluation of this densely populated area.
Dating diagenetic monazite in mudrocks: constraining the oil window?
Authors: EVANS J.A. , ZALASIEWICZ J.A. , FLETCHER I. , RASMUSSEN B. , PEARCE N.J.G.
Published: May 2008

Authigenic monazite nodules, increasingly recognized in Pre-Mesozoic mudrock successions, provide a means for dating diagenesis by exploiting trace uranium within the monazite structure. But, dating is difficult in practice because of zonation and abundant host rock inclusions. We report here a refined technique that has yielded a date of 419 ± 14 Ma 2
σ
MSWD = 1.2 for a 17-point Pb–Pb regression age from a Telychian (Silurian: late Llandovery) mudrock from central Wales. SHRIMP analyses of monazite nodules from the same horizon are consistent with this, and additionally demonstrate concordance of the U–Pb and Th–Pb systems. These results open the door to providing robust dates for a phase of burial-related diagenesis which, in Wales, seems approximately coincident with, and perhaps was related to, hydrocarbon expulsion.
Race, Immigration, and the Identity-to-Politics Link
Authors: Lee Taeku
Published: May 2008

Little controversy remains about how the United States has changed demographically since the mid-1960s. Far more controversial is whether this change is bringing about a new politics of race. This article argues that a key to settling this debate is a clearer specification of the identity-to-politics link—the nexus from a population defined by shared racial and ethnic labels to a collective group politics based on those definitions. The article articulates some potential pitfalls in how this nexus is commonly specified in empirical research. It then proposes that researchers should be mindful of five processes that are typically lumped together in linking shared demographic categories to common political destinies: definition, identification, consciousness, venue selection, and choice. The article concludes with a discussion of the potential utility and limitations of unpacking these five processes in our analysis of the identity-to-politics link.
The Judicialization of Mega-Politics and the Rise of Political Courts
Authors: Hirschl Ran
Published: May 2008

In recent years, the judicialization of politics worldwide has expanded its scope to encompass what we may term “mega-politics”—matters of outright and utmost political significance that often define and divide whole polities. In this article, I explore the scope and nature of judicialization of this kind. I begin by identifying the characteristics of the judicialization of mega-politics and by surveying the main explanations for its emergence. I then illustrate the various forms and manifestations of the judicialization of mega-politics through recent examples drawn from jurisprudence of courts and tribunals worldwide. Next, I explore recent studies that advance a strategic “judicialization-from-above” account, which emphasizes support from the political sphere as a necessary precondition for judicialization of pure politics. To further illustrate this point, I survey patterns of political reaction to recurrent manifestations of unsolicited judicial intervention in the political sphere in general, and unwelcome judgments concerning contentious political issues in particular.
Work and Power: The Connection Between Female Labor Force Participation and Female Political Representation
Authors: Iversen Torben , Rosenbluth Frances
Published: May 2008

Low levels of female labor force participation contribute to female underrepresentation in democratic polities, both by reinforcing traditional voter attitudes toward women (a demand-side feature) and by constraining the supply of women with professional experience and resources who are capable of mounting credible electoral campaigns. Female labor force participation, however, is only part of the story. Comparative analysis suggests that electoral systems have a strong, systematic effect on the extent to which women's workforce participation boosts female political representation. In candidate-centered political systems, where seniority is an important factor in legislative effectiveness, career interruptions for the sake of childcare and other family work hurts female aspiring politicians more seriously than in proportional representation (PR) systems, where political parties control the policy platform and constituency service is a minor consideration in the careers of candidates. In countries with mixed electoral systems, women do better in seats elected by PR than by single-member plurality. Within countries, women are more likely to get elected to offices characterized by shorter tenure and higher average levels of turnover.
Discursive Institutionalism: The Explanatory Power of Ideas and Discourse
Authors: Schmidt Vivien A.
Published: May 2008

The newest “new institutionalism,” discursive institutionalism, lends insight into the role of ideas and discourse in politics while providing a more dynamic approach to institutional change than the older three new institutionalisms. Ideas are the substantive content of discourse. They exist at three levels—policies, programs, and philosophies—and can be categorized into two types, cognitive and normative. Discourse is the interactive process of conveying ideas. It comes in two forms: the coordinative discourse among policy actors and the communicative discourse between political actors and the public. These forms differ in two formal institutional contexts; simple polities have a stronger communicative discourse and compound polities a stronger coordinative discourse. The institutions of discursive institutionalism, moreover, are not external-rule-following structures but rather are simultaneously structures and constructs internal to agents whose “background ideational abilities” within a given “meaning context” explain how institutions are created and exist and whose “foreground discursive abilities,” following a “logic of communication,” explain how institutions change or persist. Interests are subjective ideas, which, though real, are neither objective nor material. Norms are dynamic, intersubjective constructs rather than static structures.
Pitfalls and Prospects in the Peacekeeping Literature
Authors: Fortna Virginia Page , Howard Lise Morjé
Published: May 2008

Following closely the practice of peacekeeping, the literature on the subject has come in one small wave and then two larger ones. The first wave, during the Cold War, includes classic works focusing mainly on peacekeeping in wars between states. The second wave, at first inspired by the boom in peacekeeping shortly after the end of the Cold War, soon reflected disillusionment and focuses largely on failure and dysfunction, despite significant cases of success. The third and most recent wave also reflects a resurgence in peacekeeping but is newly concerned with systematic and methodologically rigorous analysis (both quantitative and qualitative) of basic empirical questions about the effects of peacekeeping and the sources of peacekeeping outcomes. Recent empirical studies have demonstrated peacekeeping's effectiveness in maintaining peace, but related questions persist concerning the use of force, transitional administrations, which organizations most effectively keep peace, perspectives of the “peacekept,” and effects on democratization.
Relaxin-3 stimulates the hypothalamic-pituitary-gonadal axis
Authors: McGowan B. M. , Stanley S. A. , Donovan J. , Thompson E. L. , Patterson M. , Semjonous N. M. , Gardiner J. V. , Murphy K. G. , Ghatei M. A. , Bloom S. R.
Published: May 2008

The hypothalamus plays a key role in the regulation of both energy homeostasis and reproduction. Evidence suggests that relaxin-3, a recently discovered member of the insulin superfamily, is an orexigenic hypothalamic neuropeptide. Relaxin-3 is thought to act in the brain via the RXFP3 receptor, although the RXFP1 receptor may also play a role. Relaxin-3, RXFP3, and RXFP1 are present in the hypothalamic paraventricular nucleus, an area with a well-characterized role in the regulation of energy balance that also modulates reproductive function by providing inputs to hypothalamic gonadotropin-releasing hormone (GnRH) neurons. Other members of the relaxin family are known to play a role in the regulation of reproduction. However, the effects of relaxin-3 on reproductive function are unknown. We studied the role of relaxin-3 in the regulation of the hypothalamo-pituitary-gonadal (HPG) axis. Intracerebroventricular (5 nmol) and intraparaventricular (540–1,620 pmol) administration of human relaxin-3 (H3) in adult male Wistar rats significantly increased plasma luteinizing hormone (LH) 30 min postinjection. This effect was blocked by pretreatment with a peripheral GnRH antagonist. Central administration of human relaxin-2 showed no significant effect on plasma LH. H3 dose-dependently stimulated the release of GnRH from hypothalamic explants and GT1-7 cells, which express RXFP1 and RXFP3, but did not influence LH or follicle-stimulating hormone release from pituitary fragments in vitro. We have demonstrated a novel role for relaxin-3 in the stimulation of the HPG axis, putatively via hypothalamic GnRH neurons. Relaxin-3 may act as a central signal linking nutritional status and reproductive function.
Repeated betamethasone treatment of pregnant sheep programs persistent reductions in circulating IGF-I and IGF-binding proteins in progeny
Authors: Gatford Kathryn L. , Owens Julie A. , Li Shaofu , Moss Timothy J. M. , Newnham John P. , Challis John R. G. , Sloboda Deborah M.
Published: May 2008

Exposure to synthetic glucocorticoids in utero markedly improves survival after preterm birth, but repeated exposures impair fetal and postnatal growth and are associated with evidence of insulin resistance in later life. The insulin-like growth factor (IGF) axis is an important regulator of growth and metabolism before and after birth. We have therefore investigated the effects of repeated maternal betamethasone injections on plasma IGF-I, IGF-II, and IGF-binding proteins (IGFBP) in fetal and postnatal progeny in the sheep. Pregnant sheep carrying male fetuses were injected with saline or betamethasone at 104, 111, and 118 days of gestation (dG, term ∼150 dG). Plasma samples were collected postmortem from fetuses before (75, 84, 101 dG) or after one (109 dG), two (116 dG), or three (121–122, 132–133, 145–147 dG) doses of saline or betamethasone and from progeny at 42 and 84 days of age. Fetal weight was reduced after two or more maternal betamethasone injections, and this effect persisted to term. Repeated betamethasone exposures reduced plasma IGF-I and total IGFBP in fetuses at 133 dG and progeny at 84 days, and reduced plasma IGFBP-3 at 84 days. Fetal plasma IGF-II tended to increase transiently at 109 dG following the first betamethasone injection. Fetal, placental, and/or postnatal weights correlated positively with concomitant plasma IGF-I, IGF-II, and total IGFBP. We conclude that repeated exposure to synthetic glucocorticoids in utero programs the IGF axis before and after birth, which may contribute to the adverse effects of betamethasone exposure on growth and metabolism.
The relationship between fasting hyperglycemia and insulin secretion in subjects with normal or impaired glucose tolerance
Authors: Abdul-Ghani Muhammad A. , Matsuda Masafumi , Jani Rucha , Jenkinson Christopher P. , Coletta Dawn K. , Kaku Kohei , DeFronzo Ralph A.
Published: May 2008

To assess the relationship between the fasting plasma glucose (FPG) concentration and insulin secretion in normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) subjects, 531 nondiabetic subjects with NGT ( n = 293) and IGT ( n = 238; 310 Japanese and 232 Mexican Americans) received an oral glucose tolerance test (OGTT) with measurement of plasma glucose, insulin, and C-peptide every 30 min. The insulin secretion rate was determined by plasma C-peptide deconvolution. Insulin sensitivity (Matsuda index) was measured from plasma insulin and glucose concentrations. The insulin secretion/insulin resistance (IS/IR) or disposition index was calculated as ΔISR/ΔG ÷ IR. As FPG increased in NGT subjects, the IS/IR index declined exponentially over the range of FPG from 70 to 125 mg/dl. The relationship between the IS/IR index and FPG was best fit with the equation: 28.8 exp(−0.036 FPG). For every 28 mg/dl increase in FPG, the IS/IR index declined by 63%. A similar relationship between IS/IR index and FPG was observed in IGT. However, the decay constant was lower than in NGT. The IS/IR index for early-phase insulin secretion (0–30 min) was correlated with the increase in FPG in both NGT and IGT ( r = −0.43, P < 0.0001 and r = −0.20, P = 0.001, respectively). However, the correlation between late-phase insulin secretion (60–120 min) and FPG was not significant. In conclusion, small increments in FPG, within the “normal” range, are associated with a marked decline in glucose-stimulated insulin secretion and the decrease in insulin secretion with increasing FPG is greater in subjects with NGT than IGT and primarily is due to a decline in early-phase insulin secretion.
Exenatide can reduce glucose independent of islet hormones or gastric emptying
Authors: Ionut Viorica , Zheng Dan , Stefanovski Darko , Bergman Richard N.
Published: May 2008

Exenatide is a long-acting glucagon-like peptide-1 (GLP-1) mimetic used in the treatment of type 2 diabetes. There is increasing evidence that GLP-1 can influence glycemia not only via pancreatic (insulinotropic and glucagon suppression) and gastric-emptying effects, but also via an independent mechanism mediated by portal vein receptors. The aim of our study was to investigate whether exenatide has an islet- and gastric-independent glycemia-reducing effect, similar to GLP-1. First, we administered mixed meals, with or without exenatide (20 μg sc) to dogs. Second, to determine whether exenatide-induced reduction in glycemia is independent of slower gastric emptying, in the same animals we infused glucose intraportally (to simulate meal test glucose appearance) with exenatide, exenatide + the intraportal GLP-1 receptor antagonist exendin-(9-39), or saline. Exenatide markedly decreased postprandial glucose: net 0- to 135-min area under the curve = +526 ± 315 and −536 ± 197 mg·dl−1·min−1with saline and exenatide, respectively ( P < 0.05). Importantly, the decrease in plasma glucose occurred without a corresponding increase in postprandial insulin but was accompanied by delayed gastric emptying and lower glucagon. Significantly lower glycemia was induced by intraportal glucose infusion with exenatide than with saline (92 ± 1 vs. 97 ± 1 mg/dl, P < 0.001) in the absence of hyperinsulinemia or glucagon suppression. The exenatide-induced lower glycemia was partly reversed by intraportal exendin-(9-39): 95 ± 3 and 92 ± 3 mg/dl with exenatide + antagonist and exenatide, respectively ( P < 0.01). Our results suggest that, similar to GLP-1, exenatide lowers glycemia via a novel mechanism independent of islet hormones and slowing of gastric emptying. We hypothesize that receptors in the portal vein, via a neural mechanism, increase glucose clearance independent of islet hormones.
Insulin-like stimulation of cardiac fuel metabolism by physiological levels of glucagon: involvement of PI3K but not cAMP
Authors: Harney Julie A. , Rodgers Robert L.
Published: May 2008

At concentrations around 10−9M or higher, glucagon increases cardiac contractility by activating adenylate cyclase/cyclic adenosine monophosphate (AC/cAMP). However, blood levels in vivo, in rats or humans, rarely exceed 10−10M. We investigated whether physiological concentrations of glucagon, not sufficient to increase contractility or ventricular cAMP levels, can influence fuel metabolism in perfused working rat hearts. Two distinct glucagon dose-response curves emerged. One was an expected increase in left ventricular pressure (LVP) occurring between 10−9.5and 10−8M. The elevations in both LVP and ventricular cAMP levels produced by the maximal concentration (10−8M) were blocked by the AC inhibitor NKY80 (20 μM). The other curve, generated at much lower glucagon concentrations and overlapping normal blood levels (10−11to 10−10M), consisted of a dose-dependent and marked stimulation of glycolysis with no change in LVP. In addition to stimulating glycolysis, glucagon (10−10M) also increased glucose oxidation and suppressed palmitate oxidation, mimicking known effects of insulin, without altering ventricular cAMP levels. Elevations in glycolytic flux produced by either glucagon (10−10M) or insulin (4 × 10−10M) were abolished by the phosphoinositide 3-kinase (PI3K) inhibitor LY-294002 (10 μM) but not significantly affected by NKY80. Glucagon also, like insulin, enhanced the phosphorylation of Akt/PKB, a downstream target of PI3K, and these effects were also abolished by LY-294002. The results are consistent with the hypothesis that physiological levels of glucagon produce insulin-like increases in cardiac glucose utilization in vivo through activation of PI3K and not AC/cAMP.
Induction of muscle thermogenesis by high-fat diet in mice: association with obesity-resistance
Authors: Kus Vladimir , Prazak Tomas , Brauner Petr , Hensler Michal , Kuda Ondrej , Flachs Pavel , Janovska Petra , Medrikova Dasa , Rossmeisl Martin , Jilkova Zuzana , Stefl Bohumir , Pastalkova Eva , Drahota Zdenek , Houstek Josef , Kopecky Jan
Published: May 2008

The obesogenic effect of a high-fat (HF) diet is counterbalanced by stimulation of energy expenditure and lipid oxidation in response to a meal. The aim of this study was to reveal whether muscle nonshivering thermogenesis could be stimulated by a HF diet, especially in obesity-resistant A/J compared with obesity-prone C57BL/6J (B/6J) mice. Experiments were performed on male mice born and maintained at 30°C. Four-week-old mice were randomly weaned onto a low-fat (LF) or HF diet for 2 wk. In the A/J LF mice, cold exposure (4°C) resulted in hypothermia, whereas the A/J HF, B/6J LF, and B/6J HF mice were cold tolerant. Cold sensitivity of the A/J LF mice was associated with a relatively low whole body energy expenditure under resting conditions, which was normalized by the HF diet. In both strains, the HF diet induced uncoupling protein-1-mediated thermogenesis, with a stronger induction in A/J mice. Only in A/J mice: 1) the HF diet augmented activation of whole body lipid oxidation by cold; and 2) at 30°C, oxygen consumption, total content, and phosphorylation of AMP-activated protein kinase (AMPK), and AICAR-stimulated palmitate oxidation in soleus muscle was increased by the HF diet in parallel with significantly increased leptinemia. Gene expression data in soleus muscle of the A/J HF mice indicated a shift from carbohydrate to fatty acid oxidation. Our results suggest a role for muscle nonshivering thermogenesis and lipid oxidation in the obesity-resistant phenotype of A/J mice and indicate that a HF diet could induce thermogenesis in oxidative muscle, possibly via the leptin-AMPK axis.
Long-term fasting decreases mitochondrial avian UCP-mediated oxygen consumption in hypometabolic king penguins
Authors: Rey Benjamin , Halsey Lewis G. , Dolmazon Virginie , Rouanet Jean-Louis , Roussel Damien , Handrich Yves , Butler Patrick J. , Duchamp Claude
Published: May 2008

In endotherms, regulation of the degree of mitochondrial coupling affects cell metabolic efficiency. Thus it may be a key contributor to minimizing metabolic rate during long periods of fasting. The aim of the present study was to investigate whether variation in mitochondrial avian uncoupling proteins (avUCP), as putative regulators of mitochondrial oxidative phosphorylation, may contribute to the ability of king penguins ( Aptenodytes patagonicus) to withstand fasting for several weeks. After 20 days of fasting, king penguins showed a reduced rate of whole animal oxygen consumption (V̇o2; −33%) at rest, together with a reduced abundance of avUCP and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1-α) mRNA in pectoralis muscle (−54%, −36%, respectively). These parameters were restored after the birds had been refed for 3 days. Furthermore, in recently fed, but not in fasted penguins, isolated muscle mitochondria showed a guanosine diphosphate-inhibited, fatty acid plus superoxide-activated respiration, indicating the presence of a functional UCP. It was calculated that variation in mitochondrial UCP-dependent respiration in vitro may contribute to nearly 20% of the difference in resting V̇o2 between fed or refed penguins and fasted penguins measured in vivo. These results suggest that the lowering of avUCP activity during periods of long-term energetic restriction may contribute to the reduction in metabolic rate and hence the ability of king penguins to face prolonged periods of fasting.
Phase I dynamics of cardiac output, systemic O2 delivery, and lung O2 uptake at exercise onset in men in acute normobaric hypoxia
Authors: Lador Frédéric , Tam Enrico , Azabji Kenfack Marcel , Cautero Michela , Moia Christian , Morel Denis R. , Capelli Carlo , Ferretti Guido
Published: May 2008

We tested the hypothesis that vagal withdrawal plays a role in the rapid (phase I) cardiopulmonary response to exercise. To this aim, in five men (24.6 ± 3.4 yr, 82.1 ± 13.7 kg, maximal aerobic power 330 ± 67 W), we determined beat-by-beat cardiac output (Q̇), oxygen delivery (Q̇aO2), and breath-by-breath lung oxygen uptake (V̇o2) at light exercise (50 and 100 W) in normoxia and acute hypoxia (fraction of inspired O2 = 0.11), because the latter reduces resting vagal activity. We computed Q̇ from stroke volume (Qst, by model flow) and heart rate ( fH, electrocardiography), and Q̇aO2 from Q̇ and arterial O2 concentration. Double exponentials were fitted to the data. In hypoxia compared with normoxia, steady-state fH and Q̇ were higher, and Qst and V̇o2 were unchanged. Q̇aO2 was unchanged at rest and lower at exercise. During transients, amplitude of phase I (A1) for V̇o2 was unchanged. For fH, Q̇ and Q̇aO2, A1 was lower. Phase I time constant (τ1) for Q̇aO2 and V̇o2 was unchanged. The same was the case for Q̇ at 100 W and for fH at 50 W. Qst kinetics were unaffected. In conclusion, the results do not fully support the hypothesis that vagal withdrawal determines phase I, because it was not completely suppressed. Although we can attribute the decrease in A1 of fH to a diminished degree of vagal withdrawal in hypoxia, this is not so for Qst. Thus the dual origin of the phase I of Q̇ and Q̇aO2, neural (vagal) and mechanical (venous return increase by muscle pump action), would rather be confirmed.
Lower urogenital tract anatomical and functional phenotype in lysyl oxidase like-1 knockout mice resembles female pelvic floor dysfunction in humans
Authors: Lee Una J. , Gustilo-Ashby A. Marcus , Daneshgari Firouz , Kuang Mei , Vurbic Drina , Lin Dan Li , Flask Chris A. , Li Tiansen , Damaser Margot S.
Published: May 2008

Female pelvic floor dysfunction (FPFD) is a complex group of conditions that include urinary incontinence and pelvic organ prolapse (POP). In humans, elastin homeostasis has been implicated in the pathophysiology of FPFD. Lysyl oxidase-like 1 knockout (LOXL1-KO) mice demonstrate abnormal elastic fiber homeostasis and develop FPFD after parturition. We compared the lower urogenital tract (LUT) anatomy and function in LOXL1-KO mice with and without POP. LUT anatomy was assessed in LOXL1-KO mice over 28 wk. Pelvic visceral anatomy in LOXL1-KO was evaluated with a 7-Tesla magnetic resonance imaging (MRI) scanner. LUT function was assessed using conscious cystometry and leak point pressure (LPP) testing. Quantitative histological analysis of elastic fibers was performed on external urethral sphincter (EUS) cross sections. By 25 wk of age, 50% of parous LOXL1-KO mice developed POP. LOXL1-KO mice with POP had greater variability in the size and location of the bladder on MRI compared with mice without POP. Parity and POP were associated with lower LPP. Elastin clusters were significantly increased in the EUS of LOXL1-KO mice with POP. Because parity triggers POP in LOXL1-KO mice, LOXL1-KO mice with POP have variable internal pelvic anatomy, and both parity and POP are associated with a decrease in LPP, we conclude that LOXL1 LUT anatomical and functional phenotype resembles FPFD in humans. The increase in elastin clusters in the urethra of LOXL1-KO mice with POP suggests that elastin disorganization may lead to functional abnormalities. We conclude that LOXL1 warrants further investigation in the pathphysiology of FPFD.
Detecting the Unique Representation of Motor-Unit Action Potentials in the Surface Electromyogram
Authors: Farina Dario , Negro Francesco , Gazzoni Marco , Enoka Roger M.
Published: May 2008

This study investigated the relative proportion of motor-unit action potentials that are uniquely represented in the simulated and experimental surface electromyogram (EMG). Two hundred motor units were simulated in a cylindrical anatomical system. Action potentials for each motor unit were generated with a model and then compared with those of other motor units. Pairs of motor units were considered indistinguishable and the motor units not uniquely represented in the surface EMG, when the difference in the mean energy for the pair of potentials was <5%. The anatomical conditions and recording configurations had a substantial influence on the percentage of motor units that could be uniquely identified in the simulated EMG. For example, a single monopolar channel could discriminate only 3.4% of motor units in the simulated population, whereas a system with 81 Laplacian channels arranged in a grid could discriminate 83.8% of the motor units under the same conditions. The simulation results were confirmed with populations of motor units recorded experimentally from the abductor digiti minimi muscle of eight healthy men. Furthermore, the relative proportion of uniquely identified motor units in the simulated signal was only moderately related to motor-unit size and distance from the electrodes. These results indicate the upper limit for detection of individual motor units from the surface EMG and show that a few channels of surface EMG recordings are not sufficient to study single motor units. The noninvasive identification of motor units from the surface EMG requires the use of multiple channels of information.
The Italian External Quality Assessment Scheme in Classical Cytogenetics: Four Years of Activity
Authors: Floridia G. , Falbo V. , Censi F. , Tosto F. , Salvatore M. , Baroncini A. , Battaglia P. , Conti A. , Donti E. , La Starza R. , Nitsch L. , Pierluigi M. , Piombo G. , Susca F. , Mancini M. , Mecucci C. , Calzolari E. , Dagna Bricarelli F. , Guanti G. , Taruscio D.
Published: May 2008

Background: The Italian external quality assessment scheme in classical cytogenetics was started in 2001 as an activity funded by the National Health System and coordinated by the Italian Public Institute of Health. Objectives: The aim of our work is to present data from the first 4 years of activity, 2001–2004. Methods: Italian cytogenetics public laboratories were enrolled on a voluntary basis, and this nationwide program covered prenatal, postnatal and oncological diagnosis. The scheme is annual and retrospective; a panel of experts reviewed the quality of images and reports in order to assess technical, analytical and interpretative performance. Results: Over the 4-year period, the number of participating laboratories increased: from 36 in 2001, 46 in 2002, 49 in 2003 to 51 in 2004. The overall technical performance was satisfactory. Inadequacy or lack of information in reporting was the most frequent analytical inaccuracy identified in all parts of the scheme. However, the percentage of complete reports increased significantly during the period: by 36% in postnatal diagnosis between 2001 and 2004 (p < 0.001) and by 42% in oncological diagnosis between 2002 and 2004 (p = 0.003). Conclusions: Our experience reveals that participation in external quality assessment programs has significant advantages, helping to standardize and to assure quality in cytogenetic testing.
Hematological Manifestations of Nephropathic Cystinosis
Authors: Emadi Ashkan , Burns Kathleen H. , Confer Bradley , Borowitz Michael J. , Streiff Michael B.
Published: May 2008

Pancytopenia is an uncommon manifestation of cystinosis, a congenital lysosomal storage disease. We describe a 34-year-old patient with nephropathic cystinosis with multisystem involvement who developed progressive bone marrow failure after renal transplantation. Bone marrow examination demonstrated widespread deposition of cystine crystals in histiocytes and in the background. We review the literature on the hematologic manifestations of cystinosis and discuss the available treatment options for patients with bone marrow failure secondary to cystine accumulation. The availability of effective oral therapy and the limited activity of hematopoietic growth factors in these patients highlight the importance of bone marrow examination early in the evaluation of cystinosis patients with abnormal blood counts.
Isolation and mapping of a human gene (RPD3L1) that is homologous to RPD3, a transcription factor in Saccharomyces cerevisiae
Authors: Furukawa Y. , Kawakami T. , Sudo K. , Inazawa J. , Matsumine A. , Akiyama T. , Nakamura Y.
Published: May 2008

We have isolated a novel human gene RPD3L1, that is highly homologous to a transcription factor in Saccharomyces cerevisiae, RPD3 (reduced potassium dependency 3), from a human fetal lung cDNA library. The cDNA clone, hRPD3, consists of 2,100 nucleotides that contain an open reading frame of 1446 nucleotides encoding 482 amino acids. It shares 62% identity in nucleotide sequence and 52% identity in amino acid sequence to RPD3. This gene is expressed at various levels in all tissues examined. Furthermore, we were able to map it to chromosome band 1p34.1 by FISH.
Isolation and characterization of a human cDNA clone (GCN5L1) homologous to GCN5, a yeast transcription activator
Authors: lnoue M. , Isomura M. , lkegawa S. , Fujiwara T. , Shin S. , Moriya H. , Nakamura Y.
Published: May 2008

We have isolated a novel human cDNA with a predicted amino acid sequence homologous to GCN5, a protein considered to be a regulator of transcriptional activation in yeast. This cDNA, termed GCN5L1 (GCN5-like 1), consists of 545 nucleotides including an open reading frame of 378 bp that encodes a 126-amino-acid peptide having 23.5% identity to yeast GCN5. Northern-blot analysis revealed transcription of this gene in all human tissues examined. We isolated a genomic clone corresponding to this cDNA from a human cosmid library and mapped it to chromosome 12q13→q14 by fluorescent in situ hybridization (FISH).
Assignment of the human gene for receptor-type protein tyrosine phosphatase IA-2 (PTPRN) to chromosome region 2q35→q36.1 and identification of an intragenic genetic marker
Authors: van den Maagdenberg A.M.J.M. , Olde Weghuis D. , Rijss J. , van de Wetering R.A.C. , Wieringa B. , Geurts van Kessel A. , Hendriks W.J.A.J.
Published: May 2008

Using a mouse protein tyrosine phosphatase cDNA fragment as a probe, cosmid clones containing segments of the human IA-2 PTPase gene (PTPRN) were isolated. The gene was assigned to chromosome region 2q35→q36.1 by fluorescence in situ hybridization. In an intronic region of the IA-2 gene a polymorphic microsatellite sequence was found, which will be useful as a genetic marker for the 2q35→q36 region.
Cloning, expression, and mapping of TCTEL1 a putative human homologue of murine Tcte1, to 6q
Authors: Watanabe T.K. , Fujiwara T. , Shimizu F. , Okuno S. , Suzuki M. , Takahashi E. , Nakamura Y. , Hirai Y.
Published: May 2008

From a human fetal-brain cDNA library we isolated a putative human homologue of the murine Tctel gene. The cDNA, designated TCTELl, contained an open reading frame of 339 nucleotides encoding 113 amino acids. The predicted peptides of TCTELl showed 94% and 55% identity (100% and 94% similarity) with those of murine Tctel and human RP3. Northern-blot analysis revealed a 0.9-kb transcript in all tissues examined. This gene was mapped by FISH to chromosome bands 6q25.2→q25.3, the syntenic region of the murine t-complex locus of chromosome 17.
Mapping of type I loci from human chromosome 7 reveals segments of conserved synteny on pig chromosomes 3, 9, and 18
Authors: Bruch J. , Rettenberger G. , Leeb T. , Meier-Ewert S. , Klett C. , Brenig B. , Hameister H.
Published: May 2008

We have mapped in the pig (Sus scrofa) the genes for zona pellucida glycoprotein 3 (ZP3), erythropoietin (EPO), and malate dehydrogenase 2 (MDH2) by somatic cell hybrid analysis in the pig genome. Previously, the gene for the T-cell receptor β cluster (TCRB) was assigned to SSC 18 and that for interleukin 6 (IL6) to SSC 9. However, statistical analysis of mapping data for ZP3, EPO, and MDH2 did not discriminate between SSC 9 and SSC 3. Porcine-specific PCR primers for ZP3 and IL6 were used to isolate probes from porcine YAC libraries. These two genes were mapped by FISH to porcine chromosome regions 3pter→p15 (ZP3) and 9q14→q15 (IL6). Comparative mapping considerations permit the tentative assignment of porcine EPO and MDH2 to 3pter→p15.
Karyotype and nuclear DNA content of the Australian lungfish, Neoceratodus forsteri (Ceratodidae: Dipnoi)
Authors: Rock J. , Eldridge M. , Champion A. , Johnston P. , Joss J.
Published: May 2008

The karyotype of the lungfish, Neoceratodus forsteri, is described as 2n = 54, comprising 3 pairs of very large metacentrics, 1 pair of large submetacentrics, 13 pairs of smaller acrocentrics, and 10 pairs of microchromosomes. In addition to centromeric constitutive heterochromatin, C-bands were located on the arms of almost all of the macrochromosomes. The nuclear DNA content of N. forsteri was confirmed as being high (98.6–111.9 pg/nucleus).
The chromosomes of Nectomys (Rodentia, Cricetidae) with 2n = 52, 2n = 56, and interspecific hybrids (2n = 54)
Authors: Bonvicino C.R. , D’Andrea P.S. , Cerqueira R. , Seuánez H.N.
Published: May 2008

Karyologic comparisons of Nectomys with 2n = 52 and 2n = 56, captured in different regions of Brazil, revealed the existence of two presumptive tandem fusions. These differences proved to represent drastic reproductive barriers between these two karyologic groups, based on an analysis of spermatogenesis in captive-bred hybrids (2n = 54). In these hybrid specimens, cytologic and histologic analyses indicated severe meiotic arrest and the presence of two trivalents in the first meiotic division, in which 26 elements were frequently observed. These findings and the sterility of crosses between F1 males and females as well as backcrosses indicated that Nectomys populations with 2n = 52 and 2n = 56 should be considered different species and that the present taxonomic arrangement of this genus must be reviewed.
Recent fusion events during evolution of pig chromosomes 3 and 6 identified by comparison with the babirusa karyotype
Authors: Thomsen P.D. , Høyheim B. , Christensen K.
Published: May 2008

The chromosomes of the babirusa, a species considered to have diverged from an ancestor of the pig during the Miocene epoch, about 12–26 million years ago, were studied to determine the sites of recent rearrangements during evolution of the domestic pig. It is shown that there is a pericentric inversion of the entire short arm on pig chromosome 1, compared to its counterpart in the babirusa (chromosome 15). We also present evidence suggesting that pig chromosome 3 was derived by a telomere-centromere fusion of two ancestral chromosomes homoeologous to babirusa chromosomes 12 and 17. Likewise, we conclude that pig chromosome 6 was most likely derived by a telomere-telomere fusion of ancestral chromosomes homoeologous to babirusa chromosomes 6 and 14. The detection of interstitial hybridization signals from presumptive subtelomeric repeats in the same chromosome region as the evolutionary fusion points on pig chromosomes 3 and 6 indicates that the fusion sites may still contain elements that are otherwise restricted to the telomere regions of pig chromosomes.
Isolation and mapping of a human gene (SEC14L), partially homologous to yeast SEC14, that contains a variable number of tandem repeats (VNTR) site in its 3’ untranslated region
Authors: Chinen K. , Takahashi E. , Nakamura Y.
Published: May 2008

We have isolated a novel human gene, designated SEC14L, that contains tandemly-repeated sequences in the 3’ untranslated region. This gene includes an open reading frame of 2,145 bp encoding a 715-amino-acid protein. Partial homologies to yeast SEC14 and to retinal-binding protein (RALBP) of the Japanese flying squid suggest a possible role of the gene product in an intracellular transport system. As the predicted protein is also highly homologous to hypothetical proteins of C. elegans, evolutionary conservation is indicated. SEC14L, which was expressed in all human tissues examined, was localized to chromosome bands 17q25.1→q25.2 by fluorescence in situ hybridization.