N α -Dimethylcoprogens Three novel trihydroxamate siderophores from pathogenic fungi

Summary Three novel siderophores have been isolated from a highly pathogenic strain ofAlternaria longipes (ATCC 26293). The compounds are N -dimethylated analogs of coprogen, neocoprogen I and isoneocoprogen I. Structures of the compounds have been determined by¹H- and¹³C-NMR, fast-atom-bombardment (FAB) mass spectroscopy and partial hydrolysis. One of the new compounds, N -dimethylcoprogen, is also produced, as the major siderophore, in another fungus,Fusarium dimerum.     

Carbonic anhydrase II-based metal ion sensing: Advances and new perspectives

Carbonic anhydrases are archetypical zinc metalloenzymes and as such, they have been developed as the recognition element of a family of fluorescent indicators (sensors) to detect metal ions, particularly Zn²⁺ and Cu²⁺. Subtle modification of the structure of human carbonic anhydrase II isozyme (CAII) alters the selectivity, sensitivity, and response time for these sensors. Sensors using CAII variants coupled with zinc-dependent fluorescent ligands demonstrate picomolar sensitivity, unmatched selectivity, ratiometric fluorescence signal, and near diffusion-controlled response times. Recently, these sensors have been applied to measuring the readily exchangeable concentrations of zinc in the cytosol and nucleus of mammalian tissue culture cells and concentrations of free Cu²⁺ in seawater.     

Late Pliocene dinoflagellate cyst and diatom analysis from a high resolution sequence in DSDP Site 594, Chatham Rise, south west Pacific

A high resolution mixed carbonate and siliciclastic sequence from DSDP Site 594 contains a detailed record of climate change in the late Pliocene. The sequence can be accurately dated by the LAD of Nitzschia weaveri, the LAD of Thalassiosira insigna, the LAD of T. vulnifica and the LAD of T. kolbei diatom datums. Carbonate content and δ¹⁸O signatures provide added resolution and place the sequence between isotope stages 100 and 92.The sequence contains well-preserved and diverse dinoflagellate cyst floras. Use of principal component (PCA) and canonical correspondence analyses (CCA) identifies changes in the assemblages that principally reflect warming and cooling trends. Species associated with warmer climates included Impagidinium patulum, I. paradoxum and I. sp. cf. paradoxum while those from cooler climates include Invertecysta tabulata and I. velorum. CCA is shown to be a valuable method of determining the past environmental preferences of extinct species such as I. tabulata.     

The association of the <Emphasis Type="Italic">TP53</Emphasis> polymorphisms Pro72Arg and C(−594)CC with diabetic polyneuropathy in Russian Muscovites with type 1 diabetes mellitus

The allele and genotype frequency distributions of the Pro72Arg and C(?594)CC polymorphisms of the TP53 gene were studied in type 1 diabetes mellitus (T1DM) patients, ethnic Russians from Moscow, with a T1DM record of no more than 5 years and diabetic polyneuropathy (DPN) or a T1DM record of more than 10 years but without DPN. The Pro72Arg polymorphism was associated with DPN, a higher risk of DPN being determined by allele Arg (OR = 1.96, CI 1.32?2.90) and genotype Arg/Arg (OR = 2.14, CI 1.23?3.73). Allele Pro was associated with a lower risk of DPN (OR = 0.51, CI 0.34?0.76). No association with DPN was observed for the C(?594)CC polymorphism.     

A fluorescence polarization assay to quantify biotin and biotin-binding proteins in whole plant extracts using Alexa-Fluor 594 biocytin

A high-throughput fluorescence polarization assay has been developed for the detection of biotin and biotin-binding proteins in whole leaf extracts. Various groups are investigating the insecticidal properties of avidin and other biotin-binding proteins expressed in leaves of transgenic plants. The methods commonly used to quantify biotin and avidin in leaf extracts are enzyme-linked immunosorbent assay (ELISA) and Western blotting. Here we describe a homogeneous fluorescence polarization (FP) method that quantifies transgenic avidin in whole leaf extract by the simple addition of the fluorescent avidin ligand Alexa-Fluor 594 biocytin (AFB). The FP assay exploits the fact that AFB excites and emits in regions of the spectrum that are relatively free of background fluorescence in leaf extract. Transgenic leaf avidin can be quantified within 1-2 h by the FP method, in comparison with 1-2 days for ELISA and Western blotting. The FP method can also measure the amount of biotin in control leaves, not expressing avidin. Functional avidin levels of 1.54 μM (26.1 μg/g leaf tissue) were detected in tobacco leaves expressing vacuole-targeted avidin. Control leaves had biotin levels of around 0.74 μM (∼0.18 μg/g leaf tissue). Reagent costs are minimal: typically AFB is used at concentrations of 1-10 nM, avidin is used at 1-100 nM, and sample volumes are 20 μL in 384-well microplates.