Multiple stages of plant root calcification deciphered by chemical and micromorphological analyses

Rhizoliths, that is, roots fossilized by secondary carbonates, have been known for ages and are increasingly used for paleoenvironmental reconstructions. However, knowledge about their formation mechanisms remains limited. This study reports the mineralogical and chemical characterization of rhizoliths at different stages of mineralization and fossilization in the Late Pleistocene loess–paleosol sequence of Nussloch (SW Germany). Scanning electron microscopy coupled with elemental mapping and ¹³C solid‐state nuclear magnetic resonance were used to concomitantly characterize the mineral and organic matter of the rhizoliths. These joint analyses showed for the first time that large rhizoliths are not necessarily remains of single large roots but consist of numerous microrhizoliths as remains of fine roots, formed mainly by calcium carbonates with only low amounts of Mg and Si. They further revealed that the precipitation of secondary carbonates occurs not only around, but also within the plant root and that fossilization leads to the selective preservation of recalcitrant root biopolymers—lignin and suberin. The precipitation of secondary carbonates was observed to occur first around fine roots, the epidermis acting as a first barrier, and then within the root, within the cortex cells, and even sometimes around the phloem and within the xylem. This study suggests that the calcification of plant roots starts during the lifetime of the plant and continues after its death. This has to be systematically investigated to understand the stratigraphic context before using (micro)rhizoliths for paleoenvironmental reconstructions in terrestrial sediments.     

Activation of Notch Signaling Is Required for Cholangiocarcinoma Progression and Is Enhanced by Inactivation of p53 In Vivo

Cholangiocacinoma (CC) is a cancer disease with rising incidence. Notch signaling has been shown to be deregulated in many cancers. However, the role of this signaling pathway in the carcinogenesis of CC is still not fully explored. In this study, we investigated the effects of Notch inhibition by γ-secretase inhibitor IX (GSI IX) in cultured human CC cell lines and we established a transgenic mouse model with liver specific expression of the intracellular domain of Notch (Notch-ICD) and inactivation of tumor suppressor p53. GSI IX treatment effectively impaired cell proliferation, migration, invasion, epithelial to mesenchymal transition and growth of softagar colonies. In vivo overexpression of Notch-ICD together with an inactivation of p53 significantly increased tumor burden and showed CC characteristics. Conclusion: Our study highlights the importance of Notch signaling in the tumorigenesis of CC and demonstrates that additional inactivation of p53 in vivo.     

The effects and mechanism of flavonoid–rePON1 interactions. Structure–activity relationship study

Flavonoids are plant phenolic secondary metabolites that are widely distributed in the human diet. These antioxidants have received much attention because of their neuroprotective, cardioprotective, and chemopreventive actions. While a major focus has been on the flavonoids’ antioxidant properties, there is an emerging view that many of the potential health benefits of flavonoids and their in vivo metabolites are due to modulatory actions in cells through direct interactions with proteins, and not necessarily due to their antioxidant function. This view relies on the observations that flavonoids are present in the circulation at very low concentrations, which are not sufficient to exert effective antioxidant effects. The enzyme paraoxonase 1 (PON1) is associated with high-density lipoprotein (HDL), and is responsible for many of HDLs’ antiatherogenic properties. We previously showed that the flavonoid glabridin binds to rePON1 and affects the enzyme’s 3D structure. This interaction protects the enzyme from inhibition by an atherogenic component of the human carotid plaque. Here, we broadened our study to an investigation of the structure–activity relationships (SARs) of 12 flavonoids from different subclasses with rePON1 using Trp-fluorescence quenching, modeling calculations and Cu²⁺-induced low-density lipoprotein (LDL) oxidation methods. Our findings emphasize the ‘protein-binding’ mechanism by which flavonoids exert their beneficial biological role toward rePON1. Flavonoids’ capacity to interact with the enzyme’s rePON1 hydrophobic groove mostly dictates their pro/antioxidant behavior.     

Fine needle aspiration diagnosis of extraadrenal myelolipoma presenting as a pleural mass. A case report

BACKGROUND: Myelolipoma is a benign tumor composed of mature adipose tissue and hematopoietic cells. Although they are commonly found in adrenal glands, extraadrenal myelolipomas (EMLs) are rare but well documented. They have been found in various sites, including mediastinum, liver, stomach, lungs, pelvis, spleen, retroperitoneum, presacral region and mesentery. EMLs must be distinguished from extramedullary hematopoieses, which are also composed of hematopoietic elements but may lack adipose tissue and are associated with anemia and marked bone marrow hyperplasia. CASE: We describe a case of a pleura-based, extraadrenal myelolipoma in a 53-year-old female with unremarkable bone marrow findings that were initially encountered on fluoroscopy-guided fine needle aspiration (FNA). One year later the mass was removed via open thoracotomy. It showed typical EML features histologically. CONCLUSION: EML manifests on aspiration cytology as a cellular specimen with numerous trilineage hematopoietic cells and a variable proportion of mature adipose cells. To our knowledge, FNA cytology of EML has not been found in this location before. Aspiration biopsy offers a simple and reliable method for the diagnosis of EML in the presence of appropriate clinical settings.     

A biomarker for the identification of cattle fecal pollution in water using the LTIIa toxin gene from enterotoxigenic Escherichia coli

This research describes a method based on PCR to identify cattle fecal pollution in water using a portion of the heat labile toxin IIA (LTIIa) gene from enterotoxigenic Escherichia coli (ETEC). We describe the development of the primers and target. DNA extracts (221) from different animal fecal and human sewage samples were screened and showed no cross-reactivity. Minimum detection limits using centrifugation and filtration methods to concentrate E. coli seeded into stream, ocean, and secondary effluent waters were found to be at femtogram and attogram levels, respectively. Stability of the biomarker in stream, ocean, and secondary effluent waters was 2-4 weeks for all water types. Finally, 33 farm lagoon and waste samples were collected and 31 tested to validate the method; 93% were positive for the LTIIa trait when >1,000 E. coli were screened and 100% positive when >10(5) E. coli were screened. Prevalence of the toxin gene in the E. coli population affected the outcome of the analyses. The cow biomarker can be used in watershed studies to identify cattle waste with great accuracy if the appropriate numbers of E. coli are screened.     

Études stratigraphique,sédimentologique et paléomagnétique des travertins de Kocabaş, Bassin de Denizli,Anatolie, Turquie,contenant des restes fossiles quaternaires

Stratigraphic, sedimentological and paleomagnetic studies were conducted on the travertine from Denizli Basin, near Kocabas village, in the Denizli region in Turkey, following the paleontological discovery in 2002. The stratigraphic and sedimentological studies show at least two main cycles of mass travertine, separated by a fluvial deposit and overlain by a fluvio-lacustrine deposit. These travertines must have formed in environments with strong hydrodynamics (streams or waterfalls) and are preferentially located at breaks of slopes. The paleomagnetic study shows that all the quarry travertine presents reverse magnetic polarity. On the other hand, the detrital fluvio-lacustrine deposit above the travertine presents normal geomagnetic polarity, except at the top, where it is reversed. Given the presence of an archaic Homo erectus skull and Villafranchian paleontological remains in the upper travertine unit, the whole travertine dates from the upper Matuyama, and is more recent than the Olduvai event (1.78 Ma). The normal polarity recorded in the upper fluvio-lacustrine deposit could correspond to the Cobb Mountain excursion, dated to 1.22 Ma.     

Articular chondrocyte aging and endothelin-1

OBJECTIVE: To compare in cell culture endothelin-1 (ET-1) production, receptor density, and effect on macromolecular synthesis by articular chondrocytes (AC). METHODS: AC were isolated from 1-month and 18-month old rats and cultured as monolayers. They were incubated with ET-1 without or with iNOS inhibitors, nitro-L-arginine methyl ester (L-NAME) or guanylate cyclase inhibitor, LY83583 and then [3H]thymidine, 35SO4 and [3H]proline incorporations were measured. The density and affinity for 125I-ET-1 of binding sites, and receptor isotypes were determined. The cells were also treated with interleukin-1beta (IL-1beta) or tumor necrosis factor-alpha (TNF-alpha), and then ET-1 productions measured. As well, the cells were challenged with NOC-5 (nitric oxide donor) or ET-1 and then ET-1 and NO respectively were measured. RESULTS: A concentration-dependent stimulation of DNA, PG, collagen and NO synthesis was obtained when cells were incubated with ET-1 for 24-h. Eighteen-month old chondrocytes incorporated per microg DNA more [3H]thymidine, 35SO4 and [3H]proline but less NO when challenged with ET-1 than the 1-month old cells. However, strong inhibition of this initial stimulation was seen after 48-h. L-NAME and LY83583 enhanced basal-, and ET-1-induced initial stimulation and completely suppressed late (at 48-h to 72-h) ET-1-induced inhibition, suggesting NO was responsible for this inhibitory effect. Eighteen-month old chondrocytes expressed per mug DNA more high affinity receptors of predominantly ET(A) subtype. They also produced more ET-1 but less NO under basal conditions and more ET-1 when challenged with IL-1beta and TNF-alpha. NOC-5 inhibited the production of ET-1. CONCLUSIONS: Eighteen-month old chondrocytes produce more ET-1, possess more ET-1-specific receptors, and increase more DNA, PG and collagen synthesis when challenged during 24-h with ET-1. NO, which suppresses ET-1 production and the production of which is increased by ET-1, seems to account for the late ET-1-induced inhibition of macromolecular synthesis. The possible implication of ET-1 in aging as related to osteoarthritis is discussed.     

Human carotid lesion linoleic acid hydroperoxide inhibits paraoxonase 1 (PON1) activity via reaction with PON1 free sulfhydryl cysteine 284

Paraoxonase 1 (PON1) is an HDL-associated lactonase with antiatherogenic properties. These include dampening the oxidation properties of human carotid lesion lipid extract (LLE), which in turn inactivates the enzyme. The aims of this study were to identify the PON1 inhibitor in LLE and explore the mechanism of inhibition. LLE inhibited both recombinant PON1 and HDL-PON1 lactonase activity in a dose- and time-dependent manner. Addition of antioxidants or electrophiles to LLE did not prevent PON1 inhibition. LLE was unable to inhibit a PON1 mutant lacking Cys284, whereas it did inhibit all other PON1 mutants tested. The inhibitor in the LLE was identified as linoleic acid hydroperoxide (LA-OOH) and inhibition was specific to this hydroperoxide. During its inhibition, PON1 acted like a peroxidase enzyme, reducing LA-OOH to LA-hydroxide via its Cys284. A similar reaction occurred with external thiols, such as DDT or cysteine, which also prevented PON1 inhibition and restored enzyme activity after inhibition. Thus, the antiatherogenic properties of HDL could be, at least in part, related to the sulfhydryl-reducing characteristics of its associated PON1, which are further protected and recycled by the sulfhydryl amino acid cysteine.     

Optical studies of the interaction of 4′-6-diamidino-2-phenylindole with DNA and metaphase chromosomes

The optical absorption and fluorescence characteristics of 4-6-diamidino-2-phenylindole (DAPI) with DNA and chromosomes were studied. There is a decrease in extinction coefficient and shift in the absorption spectra to a higher wavelength when the dye binds to DNA. The fluorescence of DAPI is enhanced by both A-T and G-C base-pairs. The enhancement by A-T rich is significantly greater than by G-C rich DNA. The dye produces a localized bright fluorescence in centromeric regions of mouse chromosomes and the constrictions of human chromosomes 1 and 16; these regions are known to contain A-T rich DNA and show dull fluorescence when treated with quinacrine. This dye may be useful for identifying A-T rich region in chromosomes. The fluorescence of DAPI bound to polynucleotides or chromosomes is partially quenched by the introduction of BrdU. This suppression of dye fluorescence allows optical detection of sister chromatid exchanges and chromosome region containing DNA with an unequal distribution of thymidine between polynucleotide chains after BrdU incorporation.