bluuebunny/crossref_metadata_2025_split huggingface dataset:
Late Triassic succession of North American halobiid bivalves and their circum-Pacific correlation
Authors: McRoberts Christopher A. 
Published: January 2018

The thin-shelled pteriid bivalve Halobia is widely distributed in Upper Triassic (Carnian-mid Norian) marine strata throughout the circum-Pacific region with significant occurrences along the western and arctic margin of North America, northeast Russia, China, Japan, Indochina, islands of the western Pacific, and New Zealand. Halobiids are commonly associated with deep water, black shale facies typically devoid of macrobenthos. This facies occurrence and a thin-shelled, flat-valved morphology suggests an autecology (possibly pseudoplanktic) in contrast to modern benthic pteriids. High speciation and extinction rates of halobiids not only provide an excellent means for dating rocks lacking ammonoids, but they give an independent view of rapidly evolving lineages during Carnian-Norian time.A composite halobiid succession with nearly complete coverage from the earliest Carnian through the late mid Norian is constructed from numerous North American sequences and localities with ammonoid control. Although differences in nomenclature rather then endemism make correlation of the North American succession with other circum-Pacific regions difficult, similar (and quite possibly homologous) morphologies allow limited correlation between these regions. The early Carnian is typified by H. zitteli, which occurs in predominantly boreal strata of Canada and Siberia. By later Carnian time, a variety of similar morphotypes (probably conspecific) belonging to subspecies of H. superba, H. radiata, and several other species are known throughout the circum-Pacific. The earliest Norian Kerri ammonoid zone is recognized by the first appearance of H. beyrichi in North America, and H. styriaca in Asia. In North America and the rest of the circum-Pacific, the latter part of the early Norian is marked by a rapid diversification of forms, including H. cordillerana and H. fallax. By late mid Norian time diversity reached a maximum 5 species. The mid Norian species H. fallax, H. halorica, and H. plicosa are particularly wide-spread; they occur throughout the circum-Pacific where they coexisted with the earliest Monotis. As in the Alpine-Mediterranean region, the remaining halobiids went extinct by the end of the mid Norian.Halobiid speciation and extinction rates exceed other Late Triassic macrofauna except ammonoids. The average North American species duration is fewer than three ammonoid zones (ca. 2.5 MY). The late early Norian is a period of pronounced diversification, whereas the middle early Norian and late middle Norian are times of accelerated extinctions. Instead of catastrophic extinction at the Carnian-Norian boundary, North American halobiids exhibit complex taxonomic turnover. Similar diversity patterns are recognizable in other circum-Pacific halobiid sequences.
Did shell layers negatively affect Ordovician soft-bodied infauna?
Authors: Miller Molly F. , Davies David J. 
Published: January 2018

What is the relationship, if any, between soft-bodied infaunal animals and shell accumulations? Do shell layers negatively affect infaunal animals and have they in the past? To determine whether this type of taphonomic inhibition may have operated in Ordovician infaunal communities, we evaluated extent of burrow penetration of shell-rich layers in shallow-water limestones of the Lebanon Formation, central Tennessee. Most of the analyzed shell layers, which are a few mm to 15 cm thick, are not cut by burrows. No burrows occur in shell layers in slabs containing 67% of the total area examined (5500 cm2), although burrows are common above and below the shell-rich layers.Most of the few shell-rich layers that are burrowed occur in wackestones in which skeletal fragements are arranged in a loose/dispersed fabric (Kidwell and Holland, 1991). Where burrow diameter is greater (1 cm) than maximum dimension of most shell fragments (2-4 mm), shells outline the burrow, suggesting that the animal pushed them aside during burrow construction. Where burrow diameter is less (2-3 mm) than length of shell fragments (0.5–2 cm), the burrows occur between the fragments, which show no signs of biogenic reorientation. In the single case where grainstone consisting of densely packed skeletal fragments (3–5 mm in longest dimension) is penetrated, burrow diameter (1 cm) exceeds fragment size.Shell layers penetrated by burrows originated variably as storm deposits, current winnowed accumulations, and dense shell pavements. No layers with vertically imbricated shells are burrowed; they probably were deposited in a high energy environment inimical to burrowers. With this exception there is little evidence that mode of origin of shell bed exerts strong control over subsequent penetration by burrowers.Although limited, these data suggest that Ordovician soft-bodied infaunal animals avoided burrowing through shell-rich layers. Those shell layers that were penetrated are loosely packed. Characteristically, in burrow-penetrated shell layers the ratio of fragment size: burrow size is either very low (animal pushed fragments aside) or very high (animal moved between shell fragments). Thus, abundance and character of shell-rich layers may have been an important factor controlling the composition and structure of Ordovician infaunal communities.
Origin and early evolution of Aves: dinosaurs, ancient birds, and mtDNA sequences
Authors: Sereno Paul C. 
Published: January 2018

Recently a general cladistic framework for early avian evolution has emerged. Postcranial modifications in the wrist joint and elsewhere firmly establish birds as a diversified subgroup of maniraptoran theropods. And the best known Mesozoic avians–Archaeopteryx and Late Cretaceous Hesperornis and Ichthyornis –have been positioned as successive sister taxa to living birds. Within this framework, however, several basic phylogenetic questions need to be addressed: (1) Which maniraptorans are most closely related to birds? (2) How was the modern avian skeleton built during the first third of avian history, between Archaeopteryx and Late Cretaceous Hesperornis and Ichthyornis? (3) And what are the relationships between the major groups of living birds?Avian origins. Synapomorphies listed by Ostrom and others to unite birds and other theropods typically apply to all maniraptorans or higher-level theropod clades, leaving unsettled the question of which maniraptorans constitute the immediate outgroups to birds. Deinonychosauria is confirmed as the sister-group to Aves, based principally on synapomorphies of the pectoral and pelvic girdles. In contrast to some previous suggestions, this study supports monophyly of Deinonychosauria (uniting dromaeosaurids and troodontids), with a single origin of the hyper-extendable, raptorial digit II of the pes.Sinornis and the evolution of powered flight and perching. Archaeopteryx lacks the profound modifications of the avian skeleton that characterize Ichthyornis and modern birds. Recent discovery of Lower Cretaceous birds has brought to light important intermediate stages in the transformation of the avian skeleton. Sparrow-sized Sinornis, discovered in Lower Cretaceous lake deposits in China, exhibits features that are associated with sustained powered flight; the laterally directed glenoid and V-shaped ulnare suggest that the wing was capable of tight flexion during flight. Features unrelated to the flight apparatus, in contrast, have not been altered; the skull is toothed, the manal digits are flexible and clawed, and gastralia are present beneath the rib cage.Higher-level relationships among living birds. The deep branching history of living birds occurred before the end of the Cretaceous and can be reconstructed from anatomical and genetic evidence in living birds. DNA sequences have been obtained from the mitochondrial cytochrome b gene in a variety of living birds. These data are consistent with a basal split between palaeognaths and neognaths and support the basal position of galliforms and anseriforms among neognaths. Piciforms appear to be closely related to passeriforms, and Corvida does not appear to be monophyletic, in contrast to recent DNA-DNA hybridization results.
Preservation of bone proteins and DNA in an ancient fish called ‘Wanda’
Authors: Stathoplos Linda , Tuross Noreen 
Published: January 2018

Skeletal fish remains, including several vertebrae (Teleostei incertae sedis), were recovered from the core catcher section (subbottom depth, 10.5 m) of a piston core taken in the Gulf of California (28° 00.34’ N, 111° 31.32’ W; 460 m water depth). Bottom water temperatures in this area are typically less than 10°. Bone material retained original crystal morphology as well as a chemical composition consistent with hydroxyapatite. Insoluble collagen from one small bone fragment, extracted by decalcification in EDTA, was AMS radiocarbon dated at 28,070 ± 310 years b.p. (TO#2190).Proteins from ancient fish bone fragments were partitioned by sequential extraction into two soluble fractions, non-mineral-associated and mineral-associated, and an insoluble fraction. The amino acid compositions of these extracts were compared to modern fish bone extracts. Soluble fossil fish bone extracts were enriched in collagen, consistent with peptide bond cleavage in this molecule and retention of degradation products by the mineral matrix, as observed previously in other ancient bones.Three non-collagenous bone cell-produced proteins, osteocalcin, osteonectin, and bone sialoprotein, were identified immunochemically by ELISA (enzyme-linked immunosorbent assay) in the mineral-associated fraction from these ancient fish bones. The serum protein albumin was also identified immunochemically, suggesting that hydroxyapatite binding may enhance preservation of biomolecules in the fossil record. DNA, another molecule that binds to hydroxyapatite, was also observed in the mineral-associated ancient fish extract. The DNA showed signs of both in situ cleavage and complexing to an autofluorescent component that has been observed in other ancient specimens. Thus, the continuous presence of water does not by itself preclude preservation of non-collagenous proteins, insoluble collagen, or DNA in bone for tens of thousands of years. Anoxia and low temperatures afforded by burial in this basin slow molecular decay.Small animals are underrepresented in the vertebrate terrestrial fossil record primarily due to differential preservation of skeletal material. Oceanic sediments provide an underexploited source of small vertebrate remains containing molecular as well as morphological information with chronometric and systematic utility.
Late cenozoic land mammals and interamerican environments
Authors: Webb S. David , Rancy Alceu 
Published: January 2018

Because Late Cenozoic land life in the Americas is best represented in temperate latitudes, it has long been standard practice for paleontologists to infer the history of the Great American Interchange from the classic mammalian sequences in western United States and in Argentina. In this record it is also clear that interchange genera in South America (ultimately of northern origin) make up about half of the modern land-mammal fauna, in contrast with a very limited success on the part of the reciprocal cohort of interchange genera.On the other hand, tropical biologists at least since the days of A. R. Wallace have known that the Amazon Basin was a very rich center of tropical diversity and that this Neotropical richness had spread northward at least to the latitude of Oaxaca and Veracruz in Mexico. Thus, mammalian paleontologists claim a victory for north temperate forces spreading south, whereas much of the modern biota seems to register a countervailing victory for south tropical forces spreading north.Current paleontological research in tropical latitudes, especially in the western Amazon Basin, indicates the manner in which these two different views of interamerican biotic movements can be reconciled. In effect both views are true, because they represent alternating modes of interamerican interchange. Perhaps simplistically, we recognize a “glacial arid phase” and an “interglacial humid phase”. During the former phases savanna habitats predominated even at tropical latitudes, as the western Amazonian records of the late Pleistocene strongly indicate. Because the source area in the temperate north was six times as large as that in the south, the great success of northern land mammal groups is explained. On the other hand, during interglacial humid phases, the principal biotic movement was from the vast Amazonian rainforest reservoir through the tropical latitudes of Mesoamerica. We review some of the new evidence of land mammals from tropical America in the late Pleistocene.
Characteristic taphanomic morphologies in fossil soft-tissues and their reproduction in actualistic necrolytic experiments
Authors: Wilby Phil R. 
Published: January 2018

Soft-tissues replaced by hydroxyapatite are exceedingly abundant in fossil fish from the Santana Formation (Lower Cretaceous) of Ceara, NE Brasil. A number of tissues are often phosphatized within an individual specimen and may include portions of the alimentary tract, skeletal muscle, dermis, gill apparatus and ovaries. The level of structural detail displayed by these tissues varies considerably between individual fish but is relatively constant within any single specimen. In some, sub-cellular resolution is the norm, whilst in others only gross morphological detail is preserved.Frequently, certain tissues such as gill filaments and their secondary lamellae; epithelial cells of the gut wall; and, striated muscle fibres, preserve a number of different morphologies. In the latter for example, a continuum exists between homogeneously mineralized fibres which are almost indistinguishable from living muscle, and muscle which is disrupted by exceptionally well developed and irregularly spaced banding. In the same specimens, both the sarcolema and cell nucleii may display varying degrees of distortion. These characteristic morphologies reflect the gradual loss of structural integrity accompanying a period of post-mortem decay prior to and/or during permineralization.High resolution TEM and SEM studies of structures produced at progressive stages of soft-tissue decay in modern fish, confirm the necrolytic origin of these morphologies. The timing of their appearance under specified conditions is remarkably reproducible. Certain parameters such as the ambient water temperature and salinity appear to have considerable influence over the rapidity of decay, whereas others, including the levels of oxygen and the presence of an established bacterial community have less, especially over short periods.By cross-referencing certain taphanomically produced structures, estimates of both the timing of phosphatization and the likely bottom water conditions of the Santana Formation “lagoon” may be made.
Evolutionary trends and facial control of Chitinozoa
Authors: Zaslavskaya N. 
Published: January 2018

Chitinozoa is an organic world group, the nature of which is not yet known. However, Chitinozoa is a uniform natural group of the organic world with a definite stratigraphical position (O-D). I suggest to use solely peridermal structures to specify evolutional trends of Chitinozoa.1. The change of carinae that forms the morphological succession Cyathochitina calix-C. campanulaeformis-C. kuckersiana. This succession of species encompasses the early-middle Ordovician interval.2. The change in the structure of longitudinal ridges that features the evolutionary succession Hercochitina repsinata-H. lindsaensis-H. crickmay at the middle-late Ordovician interval of the south part of Ontario.3. The change in the ultrastructure of peridermal tissue. It shows well through the structure of appendices in the succession Ancyrochitina ancyrea-A. alveolata-A. siberica, llandovery-wenlock of the Siberian platform and ludlowpridoli of Europe and North America.The points of peridermal appendix structure might be used for facial analysis. So, basal appendices change from simple branchwise up to complex anastomosis and loop-like during the change of the surrounding from shallow-water shelf up to a deep-water one, forming the morphology succession Ancyrochitina-Clathrochitina. Thus, evolutional trends of Chitinozoa and facial analysis might be based on a detailed study of peridermal structure morphology.
Influence of c-Src on hypoxic resistance to paclitaxel in human ovarian cancer cells and reversal of FV-429
Authors: Guo Qinglong , Lu Lu , Liao Yan , Wang Xiaoping , Zhang Yi , Liu Yicheng , Huang Shaoliang , Sun Haopeng , Li Zhiyu , Zhao Li 
Published: January 2018

AbstractSRC family kinase was documented to have vital roles in adjusting cancer cell malignant behaviors. To date, the role of c-Src, a member of SRC family kinase, in resistance to paclitaxel in human ovarian cancer cells under hypoxia has not been investigated. In the present study, we discovered that hypoxic environment suppressed paclitaxel-induced G2/M phase arrest and blockade of c-Src improved ovarian cancer cells’ sensitivity to paclitaxel. FV-429, a derivative of natural flavonoid wogonin, could suppress gene expression and activation of c-Src, followed by deteriorated Stat3 nuclear translocation and its binding to HIF-1α, resulting in paclitaxel resistance reversal through G2/M arrest potentiation. Our study demonstrated that c-Src contributed to hypoxic microenvironment-rendered paclitaxel resistance in human epithelial ovarian cancer cells by G2/M phase arrest deterioration, and through c-Src suppression, FV-429 was capable of reversing the resistance by blocking c-Src/Stat3/HIF-1α pathway.
Zika virus infection in pregnant rhesus macaques causes placental dysfunction and immunopathology
Authors: Hirsch Alec J. , Roberts Victoria H. J. , Grigsby Peta L. , Haese Nicole , Schabel Matthias C. , Wang Xiaojie , Lo Jamie O. , Liu Zheng , Kroenke Christopher D. , Smith Jessica L. , Kelleher Meredith , Broeckel Rebecca , Kreklywich Craig N. , Parkins Christopher J. , Denton Michael , Smith Patricia , DeFilippis Victor , Messer William , Nelson Jay A. , Hennebold Jon D. , Grafe Marjorie , Colgin Lois , Lewis Anne , Ducore Rebecca , Swanson Tonya , Legasse Alfred W. , Axthelm Michael K. , MacAllister Rhonda , Moses Ashlee V. , Morgan Terry K. , Frias Antonio E. , Streblow Daniel N. 
Published: January 2018

AbstractZika virus (ZIKV) infection during pregnancy leads to an increased risk of fetal growth restriction and fetal central nervous system malformations, which are outcomes broadly referred to as the Congenital Zika Syndrome (CZS). Here we infect pregnant rhesus macaques and investigate the impact of persistent ZIKV infection on uteroplacental pathology, blood flow, and fetal growth and development. Despite seemingly normal fetal growth and persistent fetal-placenta-maternal infection, advanced non-invasive in vivo imaging studies reveal dramatic effects on placental oxygen reserve accompanied by significantly decreased oxygen permeability of the placental villi. The observation of abnormal oxygen transport within the placenta appears to be a consequence of uterine vasculitis and placental villous damage in ZIKV cases. In addition, we demonstrate a robust maternal-placental-fetal inflammatory response following ZIKV infection. This animal model reveals a potential relationship between ZIKV infection and uteroplacental pathology that appears to affect oxygen delivery to the fetus during development.
Oxidation of SQSTM1/p62 mediates the link between redox state and protein homeostasis
Authors: Carroll Bernadette , Otten Elsje G. , Manni Diego , Stefanatos Rhoda , Menzies Fiona M. , Smith Graham R. , Jurk Diana , Kenneth Niall , Wilkinson Simon , Passos Joao F. , Attems Johannes , Veal Elizabeth A. , Teyssou Elisa , Seilhean Danielle , Millecamps Stéphanie , Eskelinen Eeva-Liisa , Bronowska Agnieszka K. , Rubinsztein David C. , Sanz Alberto , Korolchuk Viktor I. 
Published: January 2018

AbstractCellular homoeostatic pathways such as macroautophagy (hereinafter autophagy) are regulated by basic mechanisms that are conserved throughout the eukaryotic kingdom. However, it remains poorly understood how these mechanisms further evolved in higher organisms. Here we describe a modification in the autophagy pathway in vertebrates, which promotes its activity in response to oxidative stress. We have identified two oxidation-sensitive cysteine residues in a prototypic autophagy receptor SQSTM1/p62, which allow activation of pro-survival autophagy in stress conditions. The Drosophila p62 homologue, Ref(2)P, lacks these oxidation-sensitive cysteine residues and their introduction into the protein increases protein turnover and stress resistance of flies, whereas perturbation of p62 oxidation in humans may result in age-related pathology. We propose that the redox-sensitivity of p62 may have evolved in vertebrates as a mechanism that allows activation of autophagy in response to oxidative stress to maintain cellular homoeostasis and increase cell survival.
Theoretical potential for low energy consumption phase change memory utilizing electrostatically-induced structural phase transitions in 2D materials
Authors: Rehn Daniel A. , Li Yao , Pop Eric , Reed Evan J. 
Published: January 2018

AbstractStructural phase-change materials are of great importance for applications in information storage devices. Thermally driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory technologies. However, the waste heat generated by such thermal mechanisms is often not optimized, and could present a limiting factor to widespread use. The potential for electrostatically driven structural phase transitions has recently been predicted and subsequently reported in some two-dimensional materials, providing an athermal mechanism to dynamically control properties of these materials in a nonvolatile fashion while achieving potentially lower energy consumption. In this work, we employ DFT-based calculations to make theoretical comparisons of the energy required to drive electrostatically-induced and thermally-induced phase transitions. Determining theoretical limits in monolayer MoTe2 and thin films of Ge2Sb2Te5, we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is 9% of the adiabatic lower limit of the thermally driven phase transition in Ge2Sb2Te5. Furthermore, experimentally reported phase change energy consumption of Ge2Sb2Te5 is 100–10,000 times larger than the adiabatic lower limit due to waste heat flow out of the material, leaving the possibility for energy consumption in monolayer MoTe2-based devices to be orders of magnitude smaller than Ge2Sb2Te5-based devices.