In vitro synthesis of thyroxine in a low molecular weight polypeptide fragment from human thyroglobulin

A peptide fragment of Mr 16 K was purified from the cyanogen bromide digest of human thyroglobulin either normally iodinated in vivo (0.21 % I) or highly iodinated in vitro (1.40 % I). This peptide segment represents in the native molecule a zone in which tyrosine residues are not or poorly accessible to iodination and consequently do not produce thyroxine. In contrast, after isolation from thyroglobulin and iodination in vitro, the peptide is capable of synthesizing thyroxine with a high efficiency. It is concluded that the peptide described which probably represents a potential hormone forming site in the whole thyroglobulin molecule should constitute a valuable model to study the mechanism of thyroxine formation in vitro.     

Normal Human Fibroblasts Immortalized by Introduction of Human Papillomavirus Type 16 (HPV-16) E6-E7 Genes

This report demonstrates that normal human fibroblasts can be immortalized by the introduction of HPV-16 E6-E7 genes. We designed zinc-inducible expression plasmids with HPV-16 E6, E7 or both. Each plasmid was introduced into normal human fibroblasts (TIG-3 cells) using lipofection methods. Only trans-fectants with the HPV-16 E6-E7 zinc-inducible expression plasmid, which were cultured in medium supplemented with 100 μM ZnSO₄, overcame crisis and could be cultured over 200 population doubling levels (PDLs). These cell lines showed the reactivation of telomerase after crisis, and morphological alterations were also observed.     

Analysis of the collapsibility of the upper airway in a spectrum of sleep-disordered breathing: a modelling approach

Using a simplified model of the upper airways with two independent collapsible elements (nostrils and hypo-pharynx), we calculated the cross-sectional area of these two elements, taking into account pressure drops. We experimentally measured flow and pressure in the fossa and hypo-pharynx in various syndromes. This allowed us to compare the behaviour of the area supplied by our model with the aerodynamic resistance that is often used to analyse upper airway flow limitation events. We showed that nostril and hypo-pharyngeal areas are better correlated than the resistance values and thus concluded that the pressure divided by the square of the flow is a better parameter for analysing flow limitation in upper airways than resistance. Owing to its simplicity, our model is able to supply the area of the collapsible element in real time, which is impossible with more sophisticated models.     

Epipaleolithic human appendicular remains from Ein Gev I,Israel

The Upper Paleolithic (Early Epipaleolithic/Kebaran; ∼ 19,000 cal BP) human skeleton, from Layer 3 of Ein Gev I on the western flanks of the Golan Heights adjacent to the Sea of Galilee, retains sufficient limb remains to permit assessment of its body size and proportions, as well as diaphyseal reflections of skeletal hypertrophy. The individual was of modest stature but average mass for a later Upper Paleolithic individual, providing it with the body mass-to-stature body proportions characteristic of later Upper Paleolithic and more recent circum-Mediterranean humans. The humeri exhibit unexceptional diaphyseal asymmetry and robustness for an Upper Paleolithic human, and the femur exhibits similar relative diaphyseal hypertrophy. The humeral midshafts are relatively round, but the femoral and tibial midshafts are pronounced anteroposteriorly. As such, Ein Gev 1 provides additional paleobiological data on the appendicular remains of these Southwest Asian humans prior to the increasing sedentism of the terminal Pleistocene.     

Interactions with lectins indicate differences in the carbohydrate composition of the membrane-bound enzymes acetylcholinesterase and 5′-nucleotidase in different cell types

We have examined the interactions of the membrane-bound enzymes, 5′-nucleotidase and acetylcholinesterase from bovine tissues with lectins and shown that glycosylation contributes significantly to the polymorphism of these enzymes, in a tissue-specific manner.Lectins which bind 5′-nucleotidase also inhibit its catalytic activity to various degrees. We found different specificities with 5′-nucleotidases from various cell types: for example lymphocyte 5′-nucleotidase did not interact with wheat germ agglutinin, in contrast with 5′-nucleotidases from hepatocyte and caudate nucleus membranes. Treatment with glycohydrolases, α-d-mannosidase     

Electron microprobe analysis into interactions of a resin-modified glass-ionomer cement and a modified composite with human dentin in vitro

When materials used in restorative dentistry, such as a glass-ionomer cement or a compomer, were applied to dentin, ion exchanges occur between the material and the dentin. This work is based on an assessment in vitro of the ion exchanges occurring over time between (i) a glass-ionomer cement and dentin and (ii) a compomer and dentin. An electron microprobe analysis, technique not previously used for such a study, permitted qualitative and quantitative analysis of the interface and of the peripheral dentin. Analysis of the distribution of the elements in the interface and nearby showed continuous, progressive exchanges between the glass-ionomer cement and the dentin and absence of diffusion between the compomer and the dentin.     

Crisis discussions in psychology--New historical and philosophical perspectives

In this introductory article, we provide a historical and philosophical framework for studying crisis discussions in psychology. We first trace the various meanings of crisis talk outside and inside of the sciences. We then turn to Kuhn’s concept of crisis, which is mainly an analyst’s category referring to severe clashes between theory and data. His view has also dominated many discussions on the status of psychology: Can it be considered a “mature” science, or are we dealing here with a pre- or multi-paradigmatic discipline? Against these Kuhnian perspectives, we point out that especially, but not only in psychology distinctive crisis declarations and debates have taken place since at least the late 19th century. In these, quite different usages of crisis talk have emerged, which can be determined by looking at (a) the content and (b) the dimensions of the declarations, as well as (c) the functions these declarations had for their authors. Thus, in psychology at least, ‘crisis’ has been a vigorous actor’s category, occasionally having actual effects on the future course of research. While such crisis declarations need not be taken at face value, they nevertheless help to break the spell of Kuhnian analyses of psychology’s history. They should inform ways in which the history and philosophy of psychology is studied further.     

Sur quelques flores du Carbonifère des Pyrénées béarnaises

The fossil Carboniferous flora of various localitiesof the «zone primaire axiale in Pyrénées Mountains, which was mainly known only by lists of determinations, is described and figured for the first time, due to the recent discovery of a very nice fossiliferous locality. The plant association comprises Lepidophyta, Arthrophyta, Filicophyta, Pteridospermaphyta and Cordaitophyta, with the following dominant species: Neuralethopteris schelehanii (Stur), Karinopteris acuta (Brongniart), Eusphenopteris hollandica (Gothan & Jongmans), Paripteris gigantea (Sternberg), Calamites cf. cistiiformis (Stur) and Corynepteris sp.Such an association is typical for an Upper Namurian B-Lower Namurian C age in Western Europe. The biostratigraphic results are compared with the data obtained by Goniatites found also in these localities.The identity of such plant-assemblages from WesternEurope as well as South and North-East China is in favour of a continental continuity between these provinces during the Namurian.     

Heterozygosity and selective value: the case of the marine fish,Diplodus sargus (Linné, 1758)

A total of 842 white sea bream (Diplodus sargus), sampled in Banyuls-sur-Mer, were analysed to test 'genotype-phenotype' relationship for various characters related to the fitness. The results show significant differences (MLH and FIS) for the age according to the sex between females carrying out and not carrying out sexual inversion. This suggests an overdominance for old females and a genetic sex determination. The individuals laying very early during the period of reproduction are also differentiated from the individuals reproducing later in the season. These results suggest either a stable calendar of laying in time separating the individuals genetically reproducing precociously from the others and this by differential selection and/or genetic drift either a Wahlund effect among cohorts.     

Un modèle d'ontogenèse: La croissancede Toxaster granosus kiliani (Lambert)), échinide spatangoide du Valanginien

A complete study of the ontogeny of the irregular urchin Toxaster granosus kiliani (Lambert)) was achieved from an important lower cretaceous sample. In a first time, ontogenic variations of each character were analysed versus length chosen as size reference. This first step had shown that very important changes in shape take place during the development of the young urchin: increase in height, downward migration of the periproct, forward movement of the peristome… In a second time, a growth crisis was proved and described. Such a crisis occurs, from 12 mm to 16 mm length, as a momentary acceleration of the growth (i.e. the rate of growth increases during a short time). The reality of this crisis was demonstrated by both mathematical and biological ways and also by comparing with other actual and fossil populations. The whole of these results leads to a synthetical pattern of growth divided into three main stages which are successively a juvenile, a preadult and an adult stage. This division was proved also by a principal components analysis.     

Adipose tissue as a secretory organ: from adipogenesis to the metabolic syndrome

Adipose tissue contains various types of cells that include preadipocytes and adipocytes. Studies have emphasized that (i) preadipocytes secrete factors involved in their own differentiation and (ii) adipocytes acquire the ability to communicate systemically with other organs (brain, liver, skeletal muscle) and locally with other cells (preadipocytes, endothelial cells and monocytes/macrophages). Adipocytes secrete proteins exhibiting either beneficial (leptin, adiponectin) or deleterious effects (angiotensinogen). Associated to the effect of secretory products from macrophages (cytokines), a disturbance in the balance between these various secreted factors leads to the development of a metabolic syndrome.     

Global Positioning System (GPS) location accuracy improvement due to selective availability removal

Global Positioning System (GPS) is an important new technology for spatio-temporal behaviour studies of animals. Differential correction improves location accuracy. Previously, it mostly removed partially the influence of Selective Availability (SA). SA was deactivated in May 2000. The aim of this study was to quantify the influence of SA cancellation on location accuracy of various GPS receivers. We tested the accuracy of locations obtained from non-differential and differential GPS animal collars before and after SA removal. We found a significant improvement in accuracy for both types of GPS collars. However, differential GPS still provides more accurate locations.     

Stabilité du polymorphisme enzymatique dans les populations d''un Lépidoptère migrant,Agrotis ipsilon

Homogeneous population structure in a migrant Lepidoptera, Agrotis ipsilon. Light trapping of Agrotis ipsilon (Lepidoptera, Noctuidae) on various passes of the Alps and Pyrénées exhibited wide range movements between overwintering and aestivation areas. Electrophoretic analysis of samples taken in the Cantons of Vaud and Tessin (Switzerland), in the Rhône Delta (Southern France), and on passes of the Alps and Pyrénées, showed a great temporal and spatial homogeneity of allele frequencies (Fst values ranging from 0.002 to 0.013, and genetic distances from 0 to 0.004). These results support the hypothesis of a high level of gene flow. However, the occurrence during some years of high Fis values, might be explained by mixtures of populations that had undergone selection or went through a bottle-neck.     

An agent-based model of sleeping sickness: simulation trials of a forest focus in southern Cameroon

An agent-based model (AMB) used to simulate the spread of Human African Trypanosomiasis is presented together with the results of simulations of a focus of the disease. This model is a completely spatialized approach taking into account a series of often overlooked parameters such as human behaviour (activity-related movements), the density and mobility of the disease vectors--tsetse flies (Glossina spp.)--and the influence of other tsetse feeding hosts (livestock and wild animal populations). The agents that represent humans and tsetse flies move in a spatially structured environment managed by specialized location agents. Existing compartmental mathematical models governed by differential equations fail to incorporate the spatial dimension of the disease transmission. Furthermore, on a small scale, transmission is unrealistically represented by entities less than one. This ABM was tested with data from one village of the Bipindi sleeping sickness focus (southern Cameroon) and with obtained realistic simulations of stable transmission involving an animal reservoir. In varying different spatial configurations, we observe that the stability of spread is linked to the spatial complexity (number of heterogeneous locations). The prevalence is very sensitive to the human densities and to the number of tsetse flies initially infected in a given location. A relatively low and durable prevalence is obtained with shortening the phase I. In addition, we discuss some upgrading possibilities, in particular the linkage to a Geographical Information System (GIS). The agent-based approach offers new ways to understanding the spread of the disease and a tool to evaluate risk and test control strategies.     

Siwalik synopsis: A long stratigraphic sequence for the Later Cenozoic of South Asia

The Tertiary sediments of northern Pakistan are an exceptional record of terrestrial sedimentation and represent most of Neogene time. Foremost is the Siwalik Group of the Potwar Plateau, for which multiple, superposed fossil levels span ∼18–6 Ma. Well-developed magnetostratigraphic control provides secure dating so that Siwalik fossil horizons may be interpolated into a time scale with resolution to 100,000 years. We describe the geographic setting of the Potwar, give an overview of the temporal distribution of faunas, and discuss changes in paleohabitat and paleoecology with coinciding faunal change, as seen from the Siwalik viewpoint. The long Siwalik biostratigraphy of many successive assemblages with its resolved time scale may be compared directly with other well-dated sequences. Immigrant arrival and timing of faunal change may be traced. The basins of the Iberian Peninsula show somewhat different timing of introduction of hipparionine horses, and faunal turnover in the Siwaliks clearly precedes the Vallesian crisis in Spain. In contrast to the increasingly seasonal precipitation of the late Miocene Potwar, the paleohabitat of coeval North China appears to have been moist and equable, with high diversity faunas. Continued development and comparison of resolved Neogene records allow increasing resolution of the patterns of faunal change on regional to global levels.     

The mineral composition of the tests of ‘testate amoebae’ (Amoebozoa,Arcellinida): The relative importance of grain availability and grain selection

Nine peatlands were selected according to their various geological setting in the eastern part of France. The diversity of mineral particles, including xenosomes (agglutinated particles) and idiosomes (secreted particles), were analysed, together with associated morphological characteristics, for 7 species of ‘testate amoeba’ (order Arcellinida). The combined use of an Environmental Scanning Electron Microscope equipped with an EDS device and microprobe analyses is suitable for conducting an elemental analysis and subsequently enabled the determination of 24 different minerals. Such mineral diversity has never been recorded before. We conclude that the testate amoebae select grains according to their size from those available within their immediate environment. Availability in turn reflects the geological surroundings and the stability of the different kinds of grains, while their size seems to be a function of the distance from the source.     

Genetics of human obesity

We present the knowledge acquired in the field of the genetics of human obesity. The molecular approach proved to be powerful to define new syndromes associated to obesity. The pivotal role of leptin and melanocortin pathways were recognized but in rare obesity cases. In the commoner form of obesities, a multitude of polymorphisms located in genes and candidate regions participate in an individual susceptibility to weight gain in a permissive environment. The effects are often uncertain and the results not always confirmed. It is now necessary to integrate data of various origins (environment, genotype, expression) to clarify the domain.     

Exquisite preservation of a widespread filamentous microorganism in French Cretaceous ambers: Crucial for revising a controversial fossil

Cretaceous ambers from different localities often contain abundant filamentous microorganisms that extend from the surface of the lumps of amber towards their center. These microfossils have been interpreted in the past as sheathed bacteria, cyanobacteria, and fungal hyphae, respectively. Here, we applied various techniques such as optical microscopy, confocal microscopy, and SEM to constrain the actual nature of these microorganisms. We evaluate published views and new evidence and conclude that the observed morphological and ultrastructural features correspond to sheathed bacteria. We propose a scenario explaining the observed differential preservations as various stages of the sheath construction around the bacterial filaments growing in the resin and the consequences of the transformation of the resin to amber. We suggest an abundant occurrence of at least one extinct resinicolous Leptothrix-like taxon in the Cretaceous Period.