Elongation of the First Internode of the Pea Seedling during Etiolation : Interaction of Environment and Genotype

In the present study, 40 lines of peas, Pisum sativum L., from the Weibullsholm collection were examined for elongation response of the first internode to growth in soil, sand, or in darkness in air. The results obtained establish that appearance of the first (lowest) node of the epicotyl at the surface of soil was usual in only a few of the lines tested (L25, L1088, L1570). By contrast, appearance of the first node at the surface of sand as a result of enhancement of first internode extension occurred in 80% of the lines tested. In many lines, extension in sand or soil was more than in darkness in air, a surprising observation given that the known response of the pea epicotyl to pressure is to produce the extension inhibitor, ethylene. Results of two crosses, one of tall×dwarf and one of tall×tall, point to the conclusion that the Le/le locus exercises only partial control over first internode extension and that other, as yet unknown, loci are implicated.     

Erythroid and granulocytic colony growth in cultures supplemented with human serum lipoproteins.

The ability of human serum to support erythroid and granulocytic colony formation has been investigated. It was found that normal human serum could replace fetal calf serum in the cultures and was able to support the growth of these hemopoietic colonies. Serum fractions enriched for low density lipoproteins, either by precipitation with Heparin-Mn++ or by ultracentrifugation, was found to contain this growth supporting activity of human serum.     

Existence of Three Subtypes of Bradykinin B2 Receptors in Guinea Pig

We describe the binding of [3H]bradykinin to homogenates of guinea pig brain, lung, and ileum. Analysis of [3H]bradykinin binding kinetics in guinea pig brain, lung, and ileum suggests the existence of two binding sites in each tissue. The finding of two binding sites for [3H]bradykinin in ileum, lung, and brain was further supported by Scatchard analysis of equilibrium binding in each tissue. [3H]Bradykinin binds to a high-affinity site in brain, lung, and ileum (KD = 70-200 pM), which constitutes approximately 20% of the bradykinin binding, and to a second, lower-affinity site (0.63-0.95 nM), which constitutes the remaining 80% of binding. Displacement studies with various bradykinin analogues led us to subdivide the high- and lower-affinity sites in each tissue and to suggest the existence of three subtypes of B2 receptors in the guinea pig, which we classify as B2a, B2b, and B2c. Binding of [3H]bradykinin is largely to a B2b receptor subtype, which constitutes the majority of binding in brain, lung, and ileum and represents the lower-affinity site in our binding studies. Receptor subtype B2c constitutes approximately 20% of binding sites in the brain and lung and is equivalent to the high-affinity site in brain and lung. We suggest that a third subtype of B2 receptor (high-affinity site in ileum), B2a, is found only in the ileum. All three subtypes of B2 receptors display a high affinity for bradykinin, whereas they show different affinities for various bradykinin analogues displaying agonist or antagonist activities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Retinoic acid and host-pathogen interactions: effects on inducible nitric oxide synthase in vivo

Vitamin A and its metabolite retinoic acid modulate the host response to pathogens through poorly characterized mechanisms. In vitro studies have suggested that retinoic acid decreases inducible NO synthase (NOS2, or iNOS) expression, a component of innate immunity, in several cell types stimulated with lipopolysaccharide (LPS) or cytokines. This study investigated the effect of retinoic acid on LPS-stimulated NOS2 expression in vivo. Wistar-Kyoto rats received all-trans retinoic acid (RA, 10 mg/kg) or vehicle intraperitoneally daily for 5 days followed by LPS (4 mg/kg) or saline intraperitoneally and were killed 6 h later. NOS2 activation was estimated by mRNA (RT-PCR) and protein (Western-blot) expression and plasma nitrate/nitrite accumulation. In sharp contrast to previous in vitro study reports, RA significantly enhanced NOS2 mRNA, protein expression, and plasma nitrate/nitrite concentration in LPS-injected rats but not in saline-injected rats. This was associated with increased expression of interleukin-2, interferon (IFN)-gamma and IFN regulatory factor-1 mRNAs in several organs and increased IFN-gamma plasma concentration. RA significantly increased mortality in LPS-injected rats. The NOS inhibitor aminoguanidine (50 mg/kg before LPS injection) significantly attenuated the RA-mediated increase in mortality. These results demonstrate for the first time that RA supplementation in vivo enhances activation of the LPS-triggered NOS2 pathway.     

High‐Throughput DNA sequencing of ancient wood

Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high‐throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long‐term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human‐induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro‐evolutionary response of trees to climate change and human forest management.     

Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). I. Gross anatomical distribution

A morphological study of the intracranial vessels of the Black bear (Ursus americanus) was undertaken. The object was to provide basic information related to the vascular pattern in these animals as compared with other carnivores and with the human. Vascular casts were prepared from 6 animals. The vasculature of the brain disclosed patterns comparable to other species previously studied.     

Snx3 Regulates Recycling of the Transferrin Receptor and Iron Assimilation

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Highlights? Snx3 is highly expressed in vertebrate hematopoietic tissues ? Silencing of Snx3 results in anemia and hemoglobin defects in vertebrates ? Snx3 and Vps35 physically interact with Tfrc ? Snx3 is required for endosomal recycling of Tf-Tfrc complex     

Ciprofloxacin is an inhibitor of the Mcm2-7 replicative helicase

Most currently available small molecule inhibitors of DNA replication lack enzymatic specificity, resulting in deleterious side effects during use in cancer chemotherapy and limited experimental usefulness as mechanistic tools to study DNA replication. Towards development of targeted replication inhibitors, we have focused on Mcm2-7 (minichromosome maintenance protein 2–7), a highly conserved helicase and key regulatory component of eukaryotic DNA replication. Unexpectedly we found that the fluoroquinolone antibiotic ciprofloxacin preferentially inhibits Mcm2-7. Ciprofloxacin blocks the DNA helicase activity of Mcm2-7 at concentrations that have little effect on other tested helicases and prevents the proliferation of both yeast and human cells at concentrations similar to those that inhibit DNA unwinding. Moreover, a previously characterized mcm mutant (mcm4chaos3) exhibits increased ciprofloxacin resistance. To identify more potent Mcm2-7 inhibitors, we screened molecules that are structurally related to ciprofloxacin and identified several that compromise the Mcm2-7 helicase activity at lower concentrations. Our results indicate that ciprofloxacin targets Mcm2-7 in vitro, and support the feasibility of developing specific quinolone-based inhibitors of Mcm2-7 for therapeutic and experimental applications.     

Early energy deficit in Huntington disease: identification of a plasma biomarker traceable during disease progression

Huntington disease (HD) is a fatal neurodegenerative disorder, with no effective treatment. The pathogenic mechanisms underlying HD has not been elucidated, but weight loss, associated with chorea and cognitive decline, is a characteristic feature of the disease that is accessible to investigation. We, therefore, performed a multiparametric study exploring body weight and the mechanisms of its loss in 32 presymptomatic carriers and HD patients in the early stages of the disease, compared to 21 controls. We combined this study with a multivariate statistical analysis of plasma components quantified by proton nuclear magnetic resonance ((1)H NMR) spectroscopy. We report evidence of an early hypermetabolic state in HD. Weight loss was observed in the HD group even in presymptomatic carriers, although their caloric intake was higher than that of controls. Inflammatory processes and primary hormonal dysfunction were excluded. (1)H NMR spectroscopy on plasma did, however, distinguish HD patients at different stages of the disease and presymptomatic carriers from controls. This distinction was attributable to low levels of the branched chain amino acids (BCAA), valine, leucine and isoleucine. BCAA levels were correlated with weight loss and, importantly, with disease progression and abnormal triplet repeat expansion size in the HD1 gene. Levels of IGF1, which is regulated by BCAA, were also significantly lower in the HD group. Therefore, early weight loss in HD is associated with a systemic metabolic defect, and BCAA levels may be used as a biomarker, indicative of disease onset and early progression. The decreased plasma levels of BCAA may correspond to a critical need for Krebs cycle energy substrates in the brain that increased metabolism in the periphery is trying to provide.