ABSTRACT
Herein we report on the synthesis and DNA recognition properties of a series of three N-phenyl carbazole-based light-up probes initially designed for two-photon absorption. The vinylic derivatives (Cbz-2Py, Cbz-3Py) display strong fluorescence enhancement when bound to various duplex- and quadruplex-forming oligonucleotides whereas the oxazole derivative is not fluorescent in DNA. Determination of affinity constants by fluorimetric titrations evidenced that Cbz-2Py has a clear preference for AT-rich duplex structures. Circular Dichroism (CD) measurements confirmed the sequence-dependent binding of this compound and suggest insertion in the minor groove as shown by a strong induced CD (ICD) signal and further supported by molecular modeling. Altogether the data indicate that duplex vs quadruplex selectivity of the dyes is strongly dependent on the sequence of the duplex. Finally, the dyes exhibit high two-photon absorption cross-sections (up to 540GM in glycerol) and allow a fine and bright staining of nuclear DNA with low background fluorescence as shown by one and two-photon confocal microscopy imaging of fixed cells.
Subject(s)
Carbazoles/chemistry , DNA/chemistry , Fluorescent Dyes/chemistry , Oligonucleotides/chemistry , Binding Sites , Circular Dichroism , DNA/metabolism , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/metabolism , Fluorometry , Glycerol/chemistry , Microscopy, Confocal , Models, Molecular , Oligonucleotides/metabolism , Optics and Photonics , Spectrometry, FluorescenceABSTRACT
A series of red emitting vinyl-triphenyamines (TP) have been synthesized and evaluated for their two photon absorption (2PA) properties. These compounds are virtually non fluorescent in the free state but exhibit a bright red fluorescence upon binding to double-stranded DNA, both in one- and two-photon absorption. This feature allows one- and two-photon confocal imaging in cells of nuclear DNA with an excellent contrast. Derivatizable analogues for covalent bioconjugation to oligonucleotides are described and variation on the structure is discussed.
Subject(s)
Aniline Compounds/chemistry , DNA/analysis , Fluorescent Dyes/chemistry , Pyridinium Compounds/chemistry , Animals , CHO Cells , Cricetinae , Cricetulus , Microscopy, Confocal , PhotonsABSTRACT
Aedes detritus in western Algeria oviposits in irregularly flooded salty environments. The highest density of Aedes caspius eggs was found in soils with a high organic content and a salinity:organic matter ratio of < 1. We studied the relationship between oviposition abundance by both species and a number of major ecological factors along a transect. Ecological factors examined were plant species associations, vegetative cover, and soil organic content and salinity. High vegetative growth was essential for oviposition by both species. Alternatively, eggs of Ae. detritus were found in soils that had high salinity and a salinity:organic matter ratio of > 1. Conditions in northern Africa differ from those found north of the Mediterranean Sea, where oviposition is associated with climate and seasonal conditions.
Subject(s)
Aedes/physiology , Oviposition/physiology , Algeria , Animals , Environment , FemaleABSTRACT
A case of myasthenia associated with Hodgkin's disease with probable invasion of the thymus is reported. Five cases of association between lymphomatous thymoma and myasthenia (2 Hodgkin's thymomas and 3 non-Hodgkin's lymphomatous thymomas) have previously been reported. Myasthenia healed after the lymphoma was treated. This association raises pathogenic problems in the 3 cases of non-Hodgkin's thymoma where invasion of the thymus erased all its normal structure.
