The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications

The extensive Late Cretaceous – Early Paleogene sedimentary succession of Seymour Island, N.E. Antarctic Peninsula offers an unparalleled opportunity to examine the evolutionary origins of a modern polar marine fauna. Some 38 modern Southern Ocean molluscan genera (26 gastropods and 12 bivalves), representing approximately 18% of the total modern benthic molluscan fauna, can now be traced back through at least part of this sequence. As noted elsewhere in the world, the balance of the molluscan fauna changes sharply across the Cretaceous – Paleogene (K/Pg) boundary, with gastropods subsequently becoming more diverse than bivalves. A major reason for this is a significant radiation of the Neogastropoda, which today forms one of the most diverse clades in the sea. Buccinoidea is the dominant neogastropod superfamily in both the Paleocene Sobral Formation (SF) (56% of neogastropod genera) and Early - Middle Eocene La Meseta Formation (LMF) (47%), with the Conoidea (25%) being prominent for the first time in the latter. This radiation of Neogastropoda is linked to a significant pulse of global warming that reached at least 65°S, and terminates abruptly in the upper LMF in an extinction event that most likely heralds the onset of global cooling. It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event. The radiation of this and other clades at ∼65°S indicates that Antarctica was not necessarily an evolutionary refugium, or sink, in the Early – Middle Eocene. Evolutionary source – sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds.     

Evidence for AT-Transversion Bias in Wasp (Hymenoptera: Symphyta) Mitochondrial Genes and Its Implications for the Origin of Parasitism

We inferred the incidence of nucleotide conversions in the COI and 16S rRNA mitochondrial genes of members of the Symphyta and basal Apocrita (Hymenoptera). Character-state reconstructions in both genes suggested that conversions between A and T (AT transversions) occurred much more frequently than any other type of change, although we cannot wholly discount an underlying transition bias. Parsimony analysis of COI nucleotide characters did not recover phylogeny; e.g., neither the Tenthredinoidea nor Apocrita were recovered as monophyletic. However, analysis of COI amino acid characters did recover these relationships, as well as others based on fossil and morphological evidence. Analysis of 16S rRNA characters also recovered these relationships providing conversions between A and T were down-weighted. Analysis of the combined data sets gave relatively strong support for various relationships, suggesting that both data sets supported similar topographies. These data sets, both separately and combined, suggested that the phytophagous Siricidae were more closely related to the predominantly parasitic Apocrita than were the ectoparasitic Orussoidea. This suggests that the wasp parasitic lifestyle did not have a single origin, unless the Siricidae have more recently reverted to phytophagy. Alternatively, parasitism evolved twice independently, once in the Orussoidea and again in the Apocrita. The latter scenario is supported by the observation that the evolution of parasitism was accompanied by a tendency for the larvae to develop inside plant tissues. Adaptations that accompanied the movement of wasps into a confined, wood-boring habitat may have preadapted them to becoming ectoparasitic. Received: 27 March 1996 / Accepted: 2 August 1996     

质体样细胞器APICOPLAST起源的分子证据评述

顶复合器门的原生动物(Apicomplexan protozoa)含有一个高度退化的质体样(pIastid-like)细胞器,定名为apicoplast.Apicoplast的进化起源是一个长期激烈争论的问题,尽管使用了多种分子技术,但尚未取得一致的结论,以致成为质体起源研究的典型案例.文章评述了apicoplast起源研究的分子证据,分析了新的分子证据的可能来源,为进一步研究提供线索.     

The Protein Invasion: A Broad Review on the Origin of the Translational System

Translation, coded peptide synthesis, arguably exists at the heart of modern cellular life. By orchestrating an incredibly complex interaction between tRNAs, mRNAs, aaRSs, the ribosome, and numerous other small molecules, the translational system allows the interpretation of data in the form of DNA to create massively complex proteins which control and enact almost every cellular function. A natural question then, is how did this system evolve? Here we present a broad review of the existing theories of the last two decades on the origin of the translational system. We attempt to synthesize the wide variety of ideas as well as organize them into modular components, addressing the evolution of the peptide-RNA interaction, tRNA, mRNA, the ribosome, and the first proteins separately. We hope to provide both a comprehensive overview of the literature as well as a framework for future discussions and novel theories.     

Origin of Oligodendrocytes in the Vertebrate Optic Nerve: A Review

One of the unsolved problems in the research field of oligodendrocyte (OL) development has been the site(s) of origin of optic nerve OLs and its precursor cells (OPCs). It is generally accepted that OLs in the optic nerve are derived from the brain, and thus optic nerve OLs are immigrant cells. We previously demonstrated the brain origin of optic nerve OPCs in chick embryos. However, the site of optic nerve OPC origin has not been examined experimentally in developing rodents for the past two decades. We have recently reported that optic nerve OPCs in mice arise in the preoptic area by E12.5 and gradually migrate caudally and enter the optic nerve. These OPCs give rise to myelinating OLs in the optic nerve in the postnatal or adult stages. Surprisingly, there are species differences with respect to the origin of optic nerve OPCs between chicks and mice. Here, we summarize the site of OPC origin in the optic nerve based on our own previous and recent results, and discuss possible mechanisms underlying these species differences.     

The Adoption of Agriculture: Some Theoretical and Empirical Evidence

Using the standard cross-cultural sample, I show that the presence of agriculture in precapitalist societies is only weakly related to the richness of the environment and climate, but is more highly related to the population density. However, the density argument, which is based on the presence of diminishing returns in gathering and hunting, allows many exceptions. A series of other explanations for engaging in agriculture, particularly related to the reduction of risk occurring in the overreliance on other food production modes, are explored. Such an approach forces us to address a somewhat different question: Why haven't all societies adopted agriculture, at least to supply a small portion of their nourishment? Several societies are examined which, by any conventional theory including those proposed in this article, should be engaged in at least some agriculture; but they are not. If this puzzle of the absence of agriculture is solved, we will be considerably further in understanding the nature of the transition to agriculture.     

Fossil Evidence and the Origin of Bats

The phylogenetic and geographic origins of bats (Chiroptera) remain unknown. The earliest confirmed records of bats date from the early Eocene (approximately 51 Ma) in North America with other early Eocene bat taxa also being represented from Europe, Africa, and Australia. Where known, skeletons of these early taxa indicate that many of the anatomical specializations characteristic of bats had already been achieved by the early Eocene, including forelimb and manus elongation in conjunction with structural changes in the pectoral skeleton, hind limb reorientation, and the presence of rudimentary echolocating abilities. By the middle Eocene, the diversification of bats was well underway with many modern families being represented among fossil forms. A new phylogenetic analysis indicates that several early fossil bats are consecutive sister taxa to the extant crown group (including megabats), and suggests a single origin for the order, at least by the late Paleocene. Although morphological studies have long placed bats in the Grandorder Archonta, (along with primates dermopterans, and tree shrews), recent molecular studies have refuted this hypothesis, instead strongly supporting placement of bats in Laurasiatheria. Primitively, proto-bats were likely insectivorous, under-branch hangers and elementary gliders that exploited terminal branch habitats. Recent work has indicated that a number of other mammalian groups began to exploit similar arboreal, terminal branch habitats in the Paleocene, including multituberculates, eulipotyphlans, dermopterans, and plesiadapiforms. This may offer an ecological explanation for morphological convergences that led to the erroneous inclusion of bats within Archonta: ancestral archontan groups as well as proto-bats apparently were exploiting similar arboreal habitats, which may have led to concurrent development of homoplasic morphological attributes.     

A STRAND OF CARDIAC MUSCLE : Its Ultrastructure and the Electrophysiological Implications of Its Geometry

The structure of a small strand of rabbit heart muscle fibers (trabecula carnea), 30–80 µ in diameter, has been examined with light and electron microscopy. By establishing a correlation between the appearance of regions of close fiber contact in light and electron microscopy, the extent and distribution of regions of close apposition of fibers has been evaluated in approximately 200 µ length of a strand. The distribution of possible regions of resistive coupling between fibers has been approximated by a model system of cables. The theoretical linear electrical properties of such a system have been analyzed and the implications of the results of this analysis are discussed. Since this preparation is to be used for correlated studies of the electrical, mechanical, and cytochemical properties of cardiac muscle, a comprehensive study of the morphology of this preparation has been made. The muscle fibers in it are distinguished from those of the rabbit papillary muscle, in that they have no triads and have a kind of mitochondrion not found in papillary muscle. No evidence of a transverse tubular system was found, but junctions of cisternae of the sarcoplasmic reticulum and the sarcolemma, peripheral couplings, were present. The electrophysiological implications of the absence of transverse tubules are discussed. The cisternae of the couplings showed periodic tubular extensions toward the sarcolemma. A regularly spaced array of Z line-like material was observed, suggesting a possible mechanism for sarcomere growth.     

Origin of the Mckean Complex:Evidence from Timberline

Abstract

The Fourth of July valley site (5BL 120), a singlecomponent hunting camp at timberline in the Colorado Front Range, was occupied approximately 6000 radiocarbon years ago. Projectile points from the occupation area are typologically intermediate between James Allen and McKean Lanceolate points, and between Pryor Stemmed and Duncan points. The age and timberline location of the site, together with the transitional nature of the projectile points, support Husted’s (1968) hypothesis that the McKean complex developed from Plano progenitors in high-mountain Altithermal refuge areas.     

Bisphosphonates and Connexin 43: A Critical Review of Evidence

Abstract

Bisphosphonates (BPs) are drugs commonly used in the treatment of various disease arising or affecting bone tissue. There is a standard use in bone neoplasia and metastasis, hormonal and developmental disorders as well as for compensation of adverse effects in several medical therapies. Many in-vivo and in-vitro studies have assessed the efficacy of this drug and its function in cellular scale. In this concern, BPs are described to inhibit the resorptive function of osteoclasts and to prevent apoptosis of osteoblasts and osteocytes. They can preserve the osteocytic network, reduce fracture rate, and increase the bone mineral content, which is therapeutically used. Connexin 43 (Cx43) is a crucial molecule for basal regulation of bone homeostasis, development, and differentiation. It is described for signal transduction in many physiological and pathological stimuli and recently to be involved in BP action.     

Maize and the Origin of Highland Chavín Civilization: An Isotopic Perspective

Scholars frequently posit maize as the staple food of Chavín civilization and some even argue that this crop provided the critical stimulus for its development. Stable carbon isotope analysis permits an evaluation of these hypotheses because maize, the only C₄ cultigen consumed in pre-Hispanic Peru, leaves an unambiguous imprint on the bone chemistry of its consumers that allows the calculation of its relative importance in the diet. Analysis of osteological samples from Chavín de Huántar and Huaricoto indicates that although maize was eaten, C₃ foods like potatoes and quinoa constituted the bulk of the dietary intake during the development and climax of highland Chavín civilization (ca. 850-200 B.C.). The authors briefly explore possible reasons for the secondary importance of maize in the Initial Period/Early Horizon subsistence systems of this region, a pattern already established by the late Preceramic period (ca. 2000 B.C.).     

The Circadian Rhythm of Core Temperature: Origin and some Implications for Exercise Performance

This review first examines reliable and convenient ways of measuring core temperature for studying the circadian rhythm, concluding that measurements of rectal and gut temperature fulfil these requirements, but that insulated axilla temperature does not. The origin of the circadian rhythm of core temperature is mainly due to circadian changes in the rate of loss of heat through the extremities, mediated by vasodilatation of the cutaneous vasculature. Difficulties arise when the rhythm of core temperature is used as a marker of the body clock, since it is also affected by the sleep‐wake cycle. This masking effect can be overcome directly by constant routines and indirectly by “purification” methods, several of which are described. Evidence supports the value of purification methods to act as a substitute when constant routines cannot be performed. Since many of the mechanisms that rise to the circadian rhythm of core temperature are the same as those that occur during thermoregulation in exercise, there is an interaction between the two. This interaction is manifest in the initial response to spontaneous activity and to mild exercise, body temperature rising more quickly and thermoregulatory reflexes being recruited less quickly around the trough and rising phase of the resting temperature rhythm, in comparison with the peak and falling phase. There are also implications for athletes, who need to exercise maximally and with minimal risk of muscle injury or heat exhaustion in a variety of ambient temperatures and at different times of the day. Understanding the circadian rhythm of core temperature may reduce potential hazards due to the time of day when exercise is performed.     

Practical Murine Hematopathology: A Comparative Review and Implications for Research

Hematologic parameters are important markers of disease in human and veterinary medicine. Biomedical research has benefited from mouse models that recapitulate such disease, thus expanding knowledge of pathogenetic mechanisms and investigative therapies that translate across species. Mice in health have many notable hematologic differences from humans and other veterinary species, including smaller erythrocytes, higher percentage of circulating reticulocytes or polychromasia, lower peripheral blood neutrophil and higher peripheral blood and bone marrow lymphocyte percentages, variable leukocyte morphologies, physiologic splenic hematopoiesis and iron storage, and more numerous and shorter-lived erythrocytes and platelets. For accurate and complete hematologic analyses of disease and response to investigative therapeutic interventions, these differences and the unique features of murine hematopathology must be understood. Here we review murine hematology and hematopathology for practical application to translational investigation.Abbreviations: GEM, genetically engineered mouse; NMB, new methylene blue; nRBC, nucleated RBC; RDW, RBC distribution width; TNCC, total nucleated cell countHematology is an important adjunct to both clinical medicine and biomedical research, with more than 1700 currently funded NIH projects¹⁰⁹ and more than 3400 research articles published over the past 5 years using mouse models.¹²⁰ There are now more than 6000 genetically engineered mouse (GEM) models of disease, with 500 new GEM created each year at the Jackson Laboratory alone, and several large projects are underway to thoroughly phenotype each new mutant mouse strain (https://www.komp.org/).^13,176 A mouse tumor database (http://tumor.informatics.jax.org/mtbwi/index.do) is available to provide information regarding mouse models of human cancer, and the Mouse Phenome Database at the Jackson Laboratory provides links to phenotypic data for many GEM models (http://phenome.jax.org/).⁸ The defined components to complete the phenotyping of GEM models have been recently reviewed.^13,157,176 In addition, 21 inbred strains of mice are commonly used for investigations into such topics as response to infectious and genetically induced disease and dietary and pharmacologic therapies. These commonly used laboratory mouse strains have, for example, inherent differences in immunology or iron trafficking, which can affect research outcomes.^16,47,137 These interstrain differences are important to recognize and understand as a component of effective study design and prior to strain selection for laboratory investigations, especially when hematologic responses to disease need to be considered.^13,16,137For any appropriately designed experiment, concurrent age-, sex-, and strain-matched control mice must be included to accurately compare the effects of a disease, genetic manipulation or therapeutic intervention;^13,155 alternatively, individual mice can be used as their own controls in some studies. Several important guidelines exist to ensure that appropriate numbers of experimental and control mice are incorporated into a study design to maximize statistical power yet minimize waste.^{13,40-42,71,72,176} During and between studies, consistent blood collection methods are essential for accurate comparative analyses. Species-appropriate hematologic instrumentation and timely analysis of fresh blood are necessary to minimize preanalytic hematologic errors.^3,37,71 Especially important for mice and their restricted available blood volume are the use of practical, accurate, species-specific, and up-to-date hematologic methods.Here we comprehensively review murine hematology and hematopathologic responses to disease in the context of biomedical research, discovery, and phenotyping studies. To maximize the opportunity for detecting phenotypes, disease, and responses to therapeutic interventions in mice, we focus on providing a practical summary of methods and analysis for accurate hematologic studies and on describing the morphologic assessment of mouse hematopathology in peripheral blood and bone marrow in ways that will be useful to those—veterinarians and researchers alike—who work with murine species.     

Prehistoric Transpacific Contact and the Theory of Culture Change

Employing genetic theory as an analog, the paper argues that when the concept of culture is separated from the concept of society, anthropology can be shown to have depended for culture-change theory on a genetic model, which predicts pre-Columbian contact between the Old and New World, a prediction which is supported by a growing list of cultural parallels . [prehistoric transpacific contact, culture, society, culture change, scientific explanation]     

The Cold Origin of Life: A. Implications Based On The Hydrolytic Stabilities Of Hydrogen Cyanide And Formamide

It has been suggested that hydrogen cyanide(HCN) would not have been present in sufficient concentrationto polymerize in the primitive ocean to produce nucleic acidbases and amino acids. We have measured the hydrolysis ratesof HCN and formamide over the range of 30–150 °C and pH 0–14,and estimated the steady state concentrations in theprimitive ocean. At 100 °C and pH 8, the steady stateconcentration of HCN and formamide were calculated to be7 × 10^-13 M and 1 × 10^-15 M, respectively. Thus, itseems unlikely that HCN could have polymerized in a warmprimitive ocean. It is suggested that eutectic freezing mighthave been required to have concentrated HCN sufficiantly forit to polymerize. If the HCN polymerization was important forthe origin of life, some regions of the primitive earth mighthave been frozen.