Mutational spectrum of dihydropyrimidine dehydrogenase gene (DPYD) in the Tunisian population

Dihydropyrimidine dehydrogenase enzyme (DPD) deficiency is a pharmacogenetic syndrome leading to severe side-effects in patients receiving therapies containing the anticancer drug 5-fluorouracil (5-FU). The aim of this population study is to evaluate gene variations in the coding region of the dihydropyrimidine dehydrogenase gene (DPYD) in the Tunisian population. One hundred and six unrelated healthy Tunisian volunteers were genotyped by denaturing HPLC (DHPLC). Twelve variants in the coding region of the DPYD were detected. Allele frequencies of DPYD*5 (A1627G), DPYD*6 (G2194A), DPYD*9A (T85C), A496G, and G1218A were 12.7%, 7.1%, 13.7%, 5.7%, and 0.5%, respectively. The DPYD alleles DPYD*2A (IVS 14+1g>1), DPYD*3 (1897 del C) and DPYD*4 (G1601A) associated with DPD deficiency were absent from the examined subjects. We describe for the first time a new intronic polymorphism IVS 6-29 g>t, found in an allelic frequency of 4.7% in the Tunisian population. Comparing our data with that obtained in Caucasian, Egyptian, Japanese and African-American populations, we found that the Tunisian population resembles Egyptian and Caucasian populations with regard to their allelic frequencies of DPYD polymorphisms. This study describes for the first time the spectrum of DPYD sequence variations in the Tunisian population.     

Habitat use by the Grey Heron (Ardea cinerea) in eastern France

We analyzed the spatial relationship between the location and the size of the 69 Grey Heron colonies existing in 1994 in refuge areas in eastern France after recolonisation following the decline of the species in the 19(th) century. We used five variables describing the hydrographical network, which are known to play a part in the location of the colonies in this area. The results showed that the distribution of the breeding colonies was not governed by the same elements of the hydrographical network. Three local strategies of spatial utilization were observed: the first one privileged the large but not dense rivers; the second, the dense network of small rivers; and the third, the ponds that were more restricted geographically. The spatial organization of the hydrographical elements is thus very important in the distribution and the size of the Grey Heron colonies.     

Characterization of reemerging chikungunya virus

An unprecedented epidemic of chikungunya virus (CHIKV) infection recently started in countries of the Indian Ocean area, causing an acute and painful syndrome with strong fever, asthenia, skin rash, polyarthritis, and lethal cases of encephalitis. The basis for chikungunya disease and the tropism of CHIKV remain unknown. Here, we describe the replication characteristics of recent clinical CHIKV strains. Human epithelial and endothelial cells, primary fibroblasts and, to a lesser extent, monocyte-derived macrophages, were susceptible to infection and allowed viral production. In contrast, CHIKV did not replicate in lymphoid and monocytoid cell lines, primary lymphocytes and monocytes, or monocyte-derived dendritic cells. CHIKV replication was cytopathic and associated with an induction of apoptosis in infected cells. Chloroquine, bafilomycin-A1, and short hairpin RNAs against dynamin-2 inhibited viral production, indicating that viral entry occurs through pH-dependent endocytosis. CHIKV was highly sensitive to the antiviral activity of type I and II interferons. These results provide a general insight into the interaction between CHIKV and its mammalian host.     

Chromatographic approach to study the configurational stability of Ni(II) complexes of amino‐acid Schiff bases possessing stereogenic nitrogen

Herein, we disclose the design of a model Ni(II) complex of glycine Schiff base possessing single‐nitrogen stereogenic center, which was successfully used for high‐performance liquid chromatography (HPLC)‐assisted assessment of its configurational stability. The major finding is that the configurational stability of the Ni(II)‐coordinated nitrogen is profoundly dependent on the reaction conditions used, in particular the solvent, and can range from inconsequential (t_½ less than 5 min) to virtually completely stable (t_½ 90 y). The discovery reported in this study most likely to be of certain theoretical and synthetic value.     

Synthesis,resolution, and chiroptical properties of hemicryptophane cage controlling the chirality of propeller arrangement of a C3 triamide unit

The five‐steps synthesis of a hemicryptophane cage combining a benzene‐1,3,5‐tricarboxamide unit and a cyclotriveratrylene (CTV) moiety is described. Chiral high‐performance liquid chromatography (HPLC) was used to resolve the racemic mixture. The absolute configuration of the isolated enantiomers was assigned by comparison of the experimental electronic circular dichroism (ECD) spectra with the calculated ones. X‐ray molecular structures reveal that the capped benzene‐1,3,5‐tricarboxamide unit adopts a structurally chiral conformation in solid state: the chirality of CTV moiety controls the Λ or Δ orientation of the three amides.     

Transplacental Zika virus transmission in ex vivo perfused human placentas

A Zika virus (ZIKV) infection during pregnancy can result in severe birth defects such as microcephaly. To date, it is incompletely understood how ZIKV can cross the human placenta. Furthermore, results from studies in pregnant mice and non-human primates are conflicting regarding the role of cross-reactive dengue virus (DENV) antibodies on transplacental ZIKV transmission. Elucidating how ZIKV can cross the placenta and which risk factors contribute to this is important for risk assessment and for potential intervention strategies for transplacental ZIKV transmission. In this study we use an ex vivo human placental perfusion model to study transplacental ZIKV transmission and the effect that cross-reactive DENV antibodies have on this transmission. By using this model, we demonstrate that DENV antibodies significantly increase ZIKV uptake in perfused human placentas and that this increased uptake is neonatal Fc-receptor-dependent. Furthermore, we show that cross-reactive DENV antibodies enhance ZIKV infection in term human placental explants and in primary fetal macrophages but not in primary trophoblasts. Our data supports the hypothesis that presence of cross-reactive DENV antibodies could be an important risk factor for transplacental ZIKV transmission. Furthermore, we demonstrate that the ex vivo placental perfusion model is a relevant and animal friendly model to study transplacental pathogen transmission.     

Immunolocalization of the neural cell adhesion molecule L1 in epithelia of rodents

The expression of the neural cell adhesion molecule L1 was analyzed in several non-neural tissues of the mouse using immunohistochemical and immunochemical techniques. In the adult mouse, L1 immunoreactivity was detectable in the basal and intermediate layers of epidermal and lingual epithelia, in the outer sheath of hair roots and in the single-layered endodermal epithelia of lung, small intestine, and colon. Epithelia of salivary glands also showed L1 immunoreactivity, while endothelial cells of blood vessels did not express detectable levels of L1. The epithelia of the kidney showed expression only in the collecting tubule system. In single-layered kidney epithelia and stratified epithelia, L1 expression was confined to lateral cell contacts and basal infoldings of the epithelial cells but was absent from apical and basal cell surface membranes. Also, in cultured keratinocytes L1 was confined to cell-cell contacts. During development of the epidermis, L1 immunoreactivity was first detectable at the onset of keratinization around embryonic day 16. At this age LI was detectable in the kidney on branching tubules of the ureter. Western blot analysis showed that L1 immunoreactivity in epidermis and kidney appeared as two bands of 190-210 and 210-230 kDa. Northern blot analysis of mRNA from the L1-immunopositive HEL-30 keratinocyte cell line revealed a single band with the expected size of 6 kb. The presence of L1 in epithelia indicates that this molecule may be involved in interactions between epithelial cells and thereby may affect differentiation and maintenance of epithelial tissues.     

Development of definitive endoderm from embryonic stem cells in culture

The cellular and molecular events regulating the induction and tissue-specific differentiation of endoderm are central to our understanding of the development and function of many organ systems. To define and characterize key components in this process, we have investigated the potential of embryonic stem (ES) cells to generate endoderm following their differentiation to embryoid bodies (EBs) in culture. We found that endoderm can be induced in EBs, either by limited exposure to serum or by culturing in the presence of activin A (activin) under serum-free conditions. By using an ES cell line with the green fluorescent protein (GFP) cDNA targeted to the brachyury locus, we demonstrate that endoderm develops from a brachyury(+) population that also displays mesoderm potential. Transplantation of cells generated from activin-induced brachyury(+) cells to the kidney capsule of recipient mice resulted in the development of endoderm-derived structures. These findings demonstrate that ES cells can generate endoderm in culture and, as such, establish this differentiation system as a unique murine model for studying the development and specification of this germ layer.