A new antlion from Dominican amber (Neuroptera: Myrmeleontidae)

A new fossil species of antlion,Porrerus dominicanus is described from Dominican amber. Extant species ofPorrerus are found only in South America and Panama.A review of the current knowledge of fossil Myrmeleontidae is provided,     

Hymenaea protera sp.n. (Leguminosae,Caesalpinioideae) from Dominican amber has African affinities

Hymenaea protera is described from amber originating from La Toca mine in the Dominican Republic. The fossil species is characterized by the presence of reduced petals as well as distinctly clawed showy petals with cordate to reniform bases and a glabrous, verrucose ovary with long hirsute hairs at its base and along one margin. The fossil species most closely resembles the extantH. verrucosa Gaertner which occurs in East Africa and adjacent islands. These findings are interpreted as supporting a hypothesis that the genusHymenaea arose in the late Cretaceous on the combined South American-African continents and that Cretaceous and early Tertiary landmass movements were significant in determining the present amphi-Atlantic distribution of the genus. It is proposed that at least the majority, if not all, of the amber recovered from La Toca mine and other mines in the vicinity with similar-aged deposits originated fromH. protera.     

Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity

Recently discovered representatives of the Class Bdelloidea from Tertiary amber from the Dominican Republic represent the oldest known fossils of the Phylum Rotifera. Assuming that the fossil bdelloids had a similar mode of reproduction as present day members of the Class (apomictic thelytoky), then contrary to current thought, some lines of parthenogenetic organisms are not doomed to an early extinction and have evolved built-in mechanisms for genetic diversity.     

Hair in Dominican amber: Evidence for tertiary land mammals in the Antilles

Summary A piece of amber from the Dominican Republic contained approximately 50 strands of mammalian hair. Based on its characteristics and the identification of two species of fossilized ectoparasites that were also present, it is probable that the hair belonged to a rodent. This find represents the earliest fossil remains of land mammals in the Antilles and lends support to the vicariance model of West Indian biogeography.     

Adhesive grass spikelet with mammalian hair in Dominican amber: First fossil evidence of epizoochory

Discovery of a female spikelet of the grass genusPharus (Gramineae: Bambusoideae: Phareae) in association with mammalian hair in Dominican Republic amber provides the first fossil evidence of epizoochory. Hooked macrohairs on the lemma of the spikelet show that morphological modifications in grasses for dispersal by attachment to the surface of animals were present in the Late Eocene. The fossil also represents 1) the second-oldest undoubted macrofossil record of the Gramineae, 2) the earliest record of a fossil grass that can be assigned to an extant genus, 3) the earliest undoubted record of a member of the bamboo subfamily and 4) the only known fossil ofPharus.     

Ultrastructure of 30–40 million year old leaflets from Dominican amber (Hymenaea protera,Fabaceae: Angiospermae)

Hymenaea protera leaflet fossils entombed in amber, dated at 30 to 40 million years (mine strata and exomethylene dating) were observed by both light and transmission electron microscopy. Ultrastructure preservation in these leaflets shows the presence of chloroplasts with thylakoid membranes, cell walls, mitochondria with associated endoplasmic reticulum, nuclei, and xylem tissue. Tissues show varying degrees of degradation; however, natural resin, which has perfused the cells, seems to maintain the structural integrity of the membranes and walls. We conclude that preservation of amber entombed organisms results from dehydration and slow fixative properties leaving the ultrastructure in excellent condition. These findings parallel reports on the exceptional preservation of amino acids and of DNA in amber-entombed organisms.     

Mite parasitism of moths: Examples of paleosymbiosis in Dominican amber

Summary Two adult moths (families Gracillariidae and Tineidae) in Dominican amber each contained a pair of larval parasitic mites attached to their bodies. The larval mites were identified as belonging to the family Erythraeidae and represent the first fossil evidence of moths parasitized by mites. Phylogenic and evolutionary implications of this find are discussed in light of similar extant associations.     

A fossil entomogenous fungus from Dominican amber

Summary A worker ant (Formicidae: Hymenoptera) embedded in amber (25 million years old) from the Dominican Republic was covered with an entomogenous fungus containing characters very similar to present day strains ofBeauveria bassiana. This represents the first report of a fossil insect-pathogenic fungus belonging to the class Deuteromycetes.     

Fossil habrotrochid rotifers in Dominican amber

Flask-shaped microfossils are reported from bracts of a moss in Eocene-Oligocene amber from the northern Dominican Republic. These microfossils are identical with the thecae of certain living moss-dwelling rotifers in the genusHabrotrocha (Bdelloidea), which have previously been reported as fossils only from Holocene peat. What may be an egg and a rotifer body fossil are associated with these thecae and further support the identification of these fossils withHabrotrocha; the fossils are almost identical to extantH. angusticollis. The parthenogenetic bdelloid rotifers have a longer evolutionary history than was previously thought; habrotrochid rotifers seem to have persisted for 35 million years with very little change in morphology or ecological role.     

Adhesive grass spikelet with mammalian hair in Dominican amber: first fossil evidence of epizoochory.

Discovery of a female spikelet of the grass genus Pharus (Gramineae: Bambusoideae: Phareae) in association with mammalian hair in Dominican Republic amber provides the first fossil evidence of epizoochory. Hooked macrohairs on the lemma of the spikelet show that morphological modifications in grasses for dispersal by attachment to the surface of animals were present in the Late Eocene. The fossil also represents 1) the second-oldest undoubted macrofossil record of the Gramineae, 2) the earliest record of a fossil grass that can be assigned to an extant genus, 3) the earliest undoubted record of a member of the bamboo subfamily and 4) the only known fossil of Pharus.     

Scientific heritage in Brazil

This work presents an overview of Brazil’s scientific heritage, especially the collections and sets of artefacts related to the exact sciences and engineering. The information provided is the outcome of a survey being undertaken on a national level under the coordination of Museu de Astronomia e Ciências Afins (Museum of Astronomy and Related Sciences, or MAST), which is leading teams from five Brazilian universities. Sets of objects have been identified at museums, universities, military establishments, and some secondary schools. The best preserved collections are at a few museums, but the universities hold most of the artefacts. The overwhelming majority of the objects were made in the twentieth century, primarily the second half. After the general results of the survey are presented, details about a few sets of objects and collections are given, including information about their current state, the provenance of the objects and the history of the institutions. The objective of this initiative is to raise the awareness of the Brazilian state so that a policy is created for preserving this heritage and financing mechanisms to assure it can be researched, conserved, and ultimately fulfil its mission in society.     

PCR jumping in clones of 30-million-year-old DNA fragments from amber preserved termites (Mastotermes electrodominicus)

DNA from 30-million-year-old amber preserved termites (Mastotermes electrodominicus) was PCR amplified with nuclear ribosomal RNA small subunit primers and cloned into the TA vector (INVITROGEN). We obtained several classes of recombinant clones as a result. AuthenticMastotermes electrodominicus clones were identified. The source of other classes of clones was identified as contaminants of the ancient DNA template. Several of the clones appeared to be chimeric in structure with half of the clone identical to the termite sequence and the other half identical to contaminant sequences. The phenomenon of PCR jumping was identified as a possible source for the chimeric clones.     

How to halve ploidy: lessons from budding yeast meiosis

Maintenance of ploidy in sexually reproducing organisms requires a specialized form of cell division called meiosis that generates genetically diverse haploid gametes from diploid germ cells. Meiotic cells halve their ploidy by undergoing two rounds of nuclear division (meiosis I and II) after a single round of DNA replication. Research in Saccharomyces cerevisiae (budding yeast) has shown that four major deviations from the mitotic cell cycle during meiosis are essential for halving ploidy. The deviations are (1) formation of a link between homologous chromosomes by crossover, (2) monopolar attachment of sister kinetochores during meiosis I, (3) protection of centromeric cohesion during meiosis I, and (4) suppression of DNA replication following exit from meiosis I. In this review we present the current understanding of the above four processes in budding yeast and examine the possible conservation of molecular mechanisms from yeast to humans.     

5-Thio-d-glucose:o-diphenoloxidase inhibition as its mechanism of action

Summary 5-Thio-d-glucose completely inhibitedo-diphenoloxidase from animal as well as plant sources. It has been reported that thioglucose suppresses spermatogenesis in mice and also insect metamorphosis, probably through inhibition of glucose transport. Inhibition ofo-diphenoloxidase (which is active in spermatozoa and insect larvae) is suggested as an alternative mechanism of action of thioglucose.     

Novel insecticidal toxins from nematode-symbiotic bacteria

The current strategy of using transgenic crops expressing insecticidal protein toxins is placing increasing emphasis on the discovery of novel toxins, beyond those already derived from the bacterium Bacillus thuringiensis. Here we review the cloning of four insecticidal toxin complex (tc) encoding genes from a different bacterium Photorhabdus luminescens and of similar gene sequences from Xenorhabdus nematophilus. Both these bacteria occupy the gut of entomopathogenic nematodes and are released into the insect upon invasion by the nematode. In the insect the bacteria presumably secrete these insecticidal toxins, as well as a range of other antimicrobials, to establish the insect cadaver as a monocultural breeding ground for both bacteria and nematodes. In this review, the protein biochemistry and structure of the tc encoding loci are discussed in relation to their observed toxicity and histopathology. These toxins may prove useful as alternatives to those derived from B. thuringiensis for deployment in insect-resistant transgenic plants.     

Body size regulation and insulin-like growth factor signaling

How animals achieve their specific body size is a fundamental, but still largely unresolved, biological question. Over the past decades, studies on the insect model system have provided some important insights into the process of body size determination and highlighted the importance of insulin/insulin-like growth factor signaling. Fat body, the Drosophila counterpart of liver and adipose tissue, senses nutrient availability and controls larval growth rate by modulating peripheral insulin signaling. Similarly, insulin-like growth factor I produced from liver and muscle promotes postnatal body growth in mammals. Organismal growth is tightly coupled with the process of sexual maturation wherein the sex steroid hormone attenuates body growth. This review summarizes some important findings from Drosophila and mammalian studies that shed light on the general mechanism of animal size determination.     

Protecting DNA from errors and damage: an overview of DNA repair mechanisms in plants compared to mammals

The genome integrity of all organisms is constantly threatened by replication errors and DNA damage arising from endogenous and exogenous sources. Such base pair anomalies must be accurately repaired to prevent mutagenesis and/or lethality. Thus, it is not surprising that cells have evolved multiple and partially overlapping DNA repair pathways to correct specific types of DNA errors and lesions. Great progress in unraveling these repair mechanisms at the molecular level has been made by several talented researchers, among them Tomas Lindahl, Aziz Sancar, and Paul Modrich, all three Nobel laureates in Chemistry for 2015. Much of this knowledge comes from studies performed in bacteria, yeast, and mammals and has impacted research in plant systems. Two plant features should be mentioned. Plants differ from higher eukaryotes in that they lack a reserve germline and cannot avoid environmental stresses. Therefore, plants have evolved different strategies to sustain genome fidelity through generations and continuous exposure to genotoxic stresses. These strategies include the presence of unique or multiple paralogous genes with partially overlapping DNA repair activities. Yet, in spite (or because) of these differences, plants, especially Arabidopsis thaliana, can be used as a model organism for functional studies. Some advantages of this model system are worth mentioning: short life cycle, availability of both homozygous and heterozygous lines for many genes, plant transformation techniques, tissue culture methods and reporter systems for gene expression and function studies. Here, I provide a current understanding of DNA repair genes in plants, with a special focus on A. thaliana. It is expected that this review will be a valuable resource for future functional studies in the DNA repair field, both in plants and animals.     

How to make a university history of science museum: Lessons from Leeds

The historic scientific collections of well-established University Museums—the Whipple at Cambridge and the Museum of the History of Science at Oxford, for example—have long served in university teaching and as objects of research for historians. But what is involved in starting such a museum from scratch? This paper offers some reflections based on recent experiences at the University of Leeds. In a relatively short period, the Leeds project has grown from a small volunteer initiative, aimed at salvaging disparate scientific collections from all over the campus, to a centrally supported and long-term scheme to provide collections care, exhibitions, and public events, as well as material for teaching and research within history and philosophy of science. Recent work undertaken on a range of Leeds objects and collections, including a camera reportedly used to take the first X-ray diffraction photographs of DNA in the 1930s and the Mark 1 prototype of the MONIAC (Monetary National Income Automatic Computer), built and designed at Leeds in 1949 to model the flow of money through the economy, highlights the national and international significance of the University’s scientific heritage as well as the project’s ambition of providing students with on-going collections care responsibilities and object-research experience. Sketching possible futures for the Leeds project, the paper considers challenges confronting the heritage sector more broadly, and how those involved with historic scientific collections can make use of new opportunities for teaching, research, and public engagement.