Dietary topoisomerase II-poisons

DNA topoisomerases are nuclear enzymes inducing transient breaks in the DNA allowing DNA strands or double helices to pass through each other. The clinically used DNA topoisomerase II-poison etoposide is known to induce DNA double strand breaks leading to chromosomal aberrations and leukemias. Recently, some alarming studies have been published, suggesting that maternal exposure to low doses of dietary topoisomerase II-poisons, including bioflavonoids such as genistein or quercetin, may contribute to the development of infant leukemia: approximately 80% of infants with acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) have chromosome translocations involving the MLL (mixed lineage leukemia) gene. It has been shown that antineoplastic chemotherapy with the leukemogenic topoisomerase II-poison etoposide induced identical chromosomal aberrations involving the MLL gene compared to children with infant leukemia. Interestingly, the MLL cleavage sites induced by etoposide colocalized with the cleavage sites observed in infant leukemia. In addition, an almost 10-fold higher risk of infant AML has been reported for mothers consuming relatively high levels of topoisomerase II-poison containing foods. These observations are relevant, since many foods contain topoisomerase II-poisons, predominantly soy and soy products, but also coffee, wine, tea, cocao, as well as some fruits and vegetables. Further studies on the role of dietary topoisomerase II-poisons are urgently required. If the causal relationship between dietary exposure to topoisomerase II-poisons and infant leukemia will be confirmed, care should be taken to reduce exposure to critical foods during pregnancy

Symplasmic transport and phloem loading in gymnosperm leaves

Despite more than 130 years of research, phloem loading is far from being understood in gymnosperms. In part this is due to the special architecture of their leaves. They differ from angiosperm leaves among others by having a transfusion tissue between bundle sheath and the axial vascular elements. This article reviews the somewhat inaccessible and/or neglected literature and identifies the key points for pre-phloem transport and loading of photoassimilates. The pre-phloem pathway of assimilates is structurally characterized by a high number of plasmodesmata between all cell types starting in the mesophyll and continuing via bundle sheath, transfusion parenchyma, Strasburger cells up to the sieve elements. Occurrence of median cavities and branching indicates that primary plasmodesmata get secondarily modified and multiplied during expansion growth. Only functional tests can elucidate whether this symplasmic pathway is indeed continuous for assimilates, and if phloem loading in gymnosperms is comparable with the symplasmic loading mode in many angiosperm trees. In contrast to angiosperms, the bundle sheath has properties of an endodermis and is equipped with Casparian strips or other wall modifications that form a domain border for any apoplasmic transport. It constitutes a key point of control for nutrient transport, where the opposing flow of mineral nutrients and photoassimilates has to be accommodated in each single cell, bringing to mind the principle of a revolving door. The review lists a number of experiments needed to elucidate the mode of phloem loading in gymnosperms

The contribution of discourse analysis to textual criticism : a study of the Bezan text of acts.

This study of the Greek text of Acts in Codex Bezae seeks to demonstrate how the practice of textual criticism can be helped by the application of discourse analysis to internal linguistic criticism. In so doing, it aims to throw light on the origin and purpose of the Bezan text. The text of Codex Bezae is compared with that of Codices Sinaiticus and Vaticanus. After an initial section explaining the method used and outlining the principles of discourse analysis, a selection of the types of variant readings is examined exhaustivelyi connectives, word order, prepositions, divine names and the spelling of Jerusalem. Grammatical and pragmatic features (particularly the context and the writer/recipient relationship) are considered. In the final section, consecutive variants in extended portions of text (1: 15-26; 12: 1-12,18-25; 113: 1-18) are the object of exegetical study. The findings of the analyses challenge the traditional view of the Bezan text as a late and wayward text, the work of a slipshod and fanciful scribe. It emerges, on the contrary, as a careful and deliberate work, displaying a high degree of inner coherence and remarkably close to the linguistic patterns which can be discerned in the text which is common to all three manuscripts. The results further suggest that the text peculiar to Codex Bezae was the work of an early Christian editor familiar with the Jewish background of the Church. Its purpose seems to have been to amplify and enhance the first text of Acts for the benefit of Jewish recipients in order to demonstrate the continuity between Judaism and Christianity and especially the divine endorsement of the openness of the new movement to the Gentiles. The Bezan revision of the original is, thus, a valuable witness to the life of the early Church and a demonstration of the acceptable fluidity of the pre-canonical text

The contribution of discourse analysis to textual criticism : a study of the Bezan text of acts.

This study of the Greek text of Acts in Codex Bezae seeks to demonstrate how the practice of textual criticism can be helped by the application of discourse analysis to internal linguistic criticism. In so doing, it aims to throw light on the origin and purpose of the Bezan text. The text of Codex Bezae is compared with that of Codices Sinaiticus and Vaticanus. After an initial section explaining the method used and outlining the principles of discourse analysis, a selection of the types of variant readings is examined exhaustivelyi connectives, word order, prepositions, divine names and the spelling of Jerusalem. Grammatical and pragmatic features (particularly the context and the writer/recipient relationship) are considered. In the final section, consecutive variants in extended portions of text (1: 15-26; 12: 1-12,18-25; 113: 1-18) are the object of exegetical study. The findings of the analyses challenge the traditional view of the Bezan text as a late and wayward text, the work of a slipshod and fanciful scribe. It emerges, on the contrary, as a careful and deliberate work, displaying a high degree of inner coherence and remarkably close to the linguistic patterns which can be discerned in the text which is common to all three manuscripts. The results further suggest that the text peculiar to Codex Bezae was the work of an early Christian editor familiar with the Jewish background of the Church. Its purpose seems to have been to amplify and enhance the first text of Acts for the benefit of Jewish recipients in order to demonstrate the continuity between Judaism and Christianity and especially the divine endorsement of the openness of the new movement to the Gentiles. The Bezan revision of the original is, thus, a valuable witness to the life of the early Church and a demonstration of the acceptable fluidity of the pre-canonical text