Citromicrobium bathyomarinum, a novel aerobic bacterium isolated from deep-sea hydrothermal vent plume waters that contains photosynthetic pigment-protein complexes.

We have taxonomically and phylogenetically characterized a new aerobic bacterial strain (JF-1) that contains photosynthetic pigment-protein complexes and which was recently isolated from black smoker plume waters of the Juan de Fuca Ridge. Strain JF-1 is a gram-negative, yellow-pigmented, motile bacterium that is salt-, pH-, and thermotolerant. These properties are consistent with an oligotrophic adaptation to varied environmental conditions thought to exist around deep-sea hydrothermal vents. The analysis of 16S rDNA sequences revealed that strain JF-1 forms a separate phylogenetic branch between the genus Erythromonas and the Erythromicrobium-Porphyrobacter-Erythrobacter cluster within the alpha subclass of the Proteobacteria. The taxonomic name Citromicrobium bathyomarinum (gen. nov., sp. nov.) is proposed for strain JF-1.     

Solvent cage effects: the influence of radical mass and volume on the recombination dynamics of radical cage pairs generated by photolysis of [CpCH2CH2N(CH3)C(O)(CH2)nCH3Mo(CO)3]2 (n = 3, 8, 13, 18) (Cp = eta 5-C5H4) complexes

The photochemistry of the [(CpR)Mo(CO)(3)](2) molecules, where CpR = eta(5)-C(5)H(4)(CH(2))(2)C(O)NCH(3)(CH(2))(n)CH(3) (n = 3, 8, 13, and 18), was examined using femtosecond pump-probe transient absorption spectroscopy. The goal of this study was to investigate the importance of radical size and mass on the dynamics and efficiency of geminate radical-radical recombination. The femtosecond results demonstrated the lack of any size/mass dependence of the recombination efficiency. This finding contrasts with results from a prior study that did find a size/mass dependence using a steady-state photochemical technique. To explain these conflicting results, it is proposed that the femtosecond pump-probe results are a measurement of the efficiency of primary geminate recombination whereas the steady-state method results are a measurement of the sum of primary and secondary geminate recombination efficiencies. The size/mass dependence is evident in the latter because secondary geminate recombination is a slower diffusive recombination process and therefore depends on the steric properties of the radicals. Although the existence of primary and secondary recombination channels is often taken for granted, experimental differentiation of primary and secondary caging has proven to be difficult because it is not possible for a single experimental technique to span the entire timescale for recombination of a radical cage pair and adequately resolve these recombination pathways.     

Ciliary receptors associated with the mouth and pharynx of Acoela (Acoelomorpha): a comparative ultrastructural study

The ultrastructure and distribution of receptor cells near the mouth and (where present) the pharynx of Hofstenia miamia, Proporus bermudensis, Conaperta thela, and Convoluta convoluta (Acoela) were investigated by transmission electron microscopy and confocal laser scanning microscopy of specimens stained with a fluorescence marker for actin. Five types of monociliary receptors were identified: (1) non‐collared receptors with a single long and narrow ciliary rootlet; (2) non‐collared receptors with a wide main ciliary rootlet and a smaller posterior rootlet; (3) non‐collared receptors with a single wide and hollow ciliary rootlet with a granulated core; (4) Collar (?) receptors with obliquely radial filament bundles in the cell apex and with a single hollow ciliary rootlet composed of numerous strand‐like elements; and (5) Collar receptors lacking a striated rootlet but with a granular body (swallow's nest rootlet). While H. miamia bears the first two receptor types, P. bermudensis has receptors of type 1, 3 and 5, and Cona. thela and Conv. convoluta have receptors of type 3, 4 and 5. The density of receptors is generally highest at the anterior body tip, regardless of where the mouth is located. Most receptor types occur scattered over the whole body but type 2 receptors of H. miamia are restricted to the pharynx and mouth region. The lack of a common receptor type specific for the mouth and pharynx of the investigated species points to an independent origin of the pharynges in Hofsteniidae and in Proporidae and of the mouth tube in Convolutidae. Moreover, the homology of the so‐called collar receptors in Acoela with typical collar receptors in other invertebrates is questioned.     

Detection of large cDNA inserts within crude lambda gt11 lysates: a rapid and sensitive method

A method is presented for the isolation of bacteriophage lambda DNA and the rapid identification of large cDNA inserts within crude phage lysates. The primary screening of a lambda gt11 cDNA library with a 32P-radiolabeled cDNA probe yielded 21 putative positive clones. A phage "spot-blot" analysis was employed to quickly screen these potential recombinants. This eliminated 9 of the 21 clones as the result of false positive signals. The remaining 12 recombinant phage were amplified on agarose-based media, and phage DNA was isolated using a modified plate lysate procedure. The DNA thus obtained from these crude lysates could be easily digested with EcoRI and examined by Southern blot analysis. The resulting blot was hybridized with the same cDNA probe used in the initial screening of the library. Thus, two clones harboring the longest cDNA insert were identified from a mixed phage population and were subsequently plaque purified. The procedure is rapid, sensitive, reproducible, inexpensive and allows the processing of several clones at once without sacrificing the quality or yields of the DNA preparation. Furthermore, the method obviates the need for plaque purifying all the positives obtained from the initial screening of a cDNA library.     

Breakage of the T cell receptor α chain locus in non malignant clones from patients with ataxia telangiectasia

Summary Patients with ataxia telangiectasia (A-T) develop specific chromosome translocations, which may confer a proliferative advantage, resulting in the appearance of large clones in the peripheral blood lymphocytes. These lymphocytes are not malignant. Using in situ hybridisation techniques we have investigated a consistent 14q11 translocation break-point observed in a t(X;14)(q28;q11) translocation clone from each of two different patients and a t(14;14)(q11;q32) clone from a third patient. In all cases the chromosome translocation involved breakage within the chain locus of the T cell receptor (TCR), between the variable and constant regions, at 14q11. Chromosome rearrangement involving breakage within TCR can therefore precede the development of malignancy. Further chromosomal rearrangement may be required in these patients, for progression to the leukaemic state.