Structure and vibrational dynamics of model compounds of the [FeFe]-hydrogenase enzyme system via ultrafast two-dimensional infrared spectroscopy.

Ultrafast two-dimensional infrared (2D) spectroscopy has been applied to study the structure and vibrational dynamics of (mu-S(CH2)3S)Fe2(CO)6, a model compound of the active site of the [FeFe]-hydrogenase enzyme system. Comparison of 2D-IR spectra of (mu-S(CH2)3S)Fe2(CO)6 with density functional theory calculations has determined that the solution-phase structure of this molecule is similar to that observed in the crystalline phase and in good agreement with gas-phase simulations. In addition, vibrational coupling and rapid (<5 ps) solvent-mediated equilibration of energy between vibrationally excited states of the carbonyl ligands of the di-iron-based active site model are observed prior to slower (approximately 100 ps) relaxation to the ground state. These dynamics are shown to be solvent-dependent and form a basis for the future determination of the vibrational interactions between active site and protein.

Evaluation of PCR, IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales.

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4-6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given.

Polyferredoxin-based electrode materials.

Electrochemical oxidation of the hydrosulfide cluster [Fe4S4(SH)4]2- on gold, platinum or vitreous carbon in a methyl cyanide electrolyte leads to the growth of a conducting film. Spectroscopic and other evidence suggests that the film has cubane centres, predominately in the [4Fe4S]3+ oxidation state, which are linked by disulfide ligands to give an anionic array of [Fe4S4(S approximately)4]n- units. X-ray data suggests some long-range order in the electrode material. The polyferredoxin binds redox active cations consistent with an anionic array.

Cadusafos Inhibits Hatching, Invasion, and Movement of the Potato Cyst Nematode Globodera pallida.

The effect of the nematicide cadusafos on the hatching of the potato cyst nematode Globodera pallida in potato root diffusate, soil leachate, and distilled water was investigated. Cadusafos had a significant effect on the hatching, migration, movement, and root invasion by the second-stage juveniles. Hatching was completely inhibited at low concentrations of cadusafos (0.002-0.004 microg/ml), but hatching resumed a week after removing the nematicide. At concentrations of 0.05 microg/ml and higher of analytical-grade cadusafos, the inhibition of hatching was permanent.

Genetic Variation in Nacobbus aberrans: An Approach toward Taxonomic Resolution.

Biochemical and molecular analyses of genetic variation were evaluated to address the taxonomic status of Nacobbus aberrans. Isolates from Mexico, Peru, and Argentina, cultured on tomato in the greenhouse, were analyzed with respect to isozyme and DNA marker variation. Although acid phosphatase and malate dehydrogenase revealed distinct profiles for each isolate, non-specific esterases revealed possible affinities between the Peruvian isolates and between the isolates from Mexico and Peru. Two of l 0 RAPD primers revealed affinities suggested by esterase profiles. RFLP analysis of the rDNA repeating unit with six restriction enzymes revealed identical cleavage patterns between the Peru isolates and a distinct profile shared by isolates from Mexico and Argentina. Nucleotide sequence analysis of the 5.8S rRNA coding region revealed differences among the four isolates at eight of 157 positions; sequences of the Peruvian isolates differed from each other at only one position, whereas the Mexican and Argentine isolates were identical and could be distinguished from the Peruvian isolates. A distance matrix from unweighted pairwise comparisons of the 5.8S rDNA revealed apparent elevated intraspecific divergence in N. aberrans comparable to intergeneric divergence between Heterodera and Globodera. Analysis of additional N. aberrans isolates from throughout the distribution range should help determine the full extent of intraspecific genetic variation that underlies the phenotypic and morphologic diversity of the genus.

Differentiation of Species and Populations of Aphelenchoides and of Ditylenchus angustus Using a Fragment of Ribosomal DNA.

The polymerase chain reaction (PCR) was used to amplify a fragment of the ribosomal DNA (rDNA) from species and undescribed populations of Aphelenchoides and Ditylenchus angustus. The PCR primers used were based on conserved sequences in the 18S and 26S ribosomal RNA genes of Caenorhabditis elegans. In C. elegans, these primers amplify a 1,292 base pair (bp) fragment, which consists of the two internal transcribed spacers and the entire 5.8S gene. Amplification products from crude DNA preparations of 12 species and populations of Aphelenchoides and from D. angustus ranged in size from approximately 860-1,100bp. Southern blots probed with a cloned ribosomal repeat from C. elegans confirmed the identity of these amplified bands as ribosomal fragments. In addition to the differing sizes of the amplified rDNA fragments, the relative intensity of hybridization with the C. elegans probe indicated varying degrees of sequence divergence between species and populations. In some cases, amplified rDNA from the fungal host was evident. Storage of A. composticola at - 45 C for 2 years did not affect the ability to obtain appropriate amplified products from crude DNA preparations. Amplified rDNA fragments were cut with six restriction enzymes, and the restriction fragments produced revealed useful diagnostic differences between species and some undescribed populations. These results were consistent with previous studies based on morphology and isoenzymes. Three undescribed populations of Aphelenchoides were found to be different from all the species examined and from each other.

Peptic ulceration in a lingual sinus.

Heterotopic gastric mucosa is reported in a sinus present since birth in the midline of the anterior two thirds of the tongue. Current theories concerning the presence of heterotopic mucosa in the oral cavity are presented and discussed.

Condensing osteitis of the clavicle: does it exist?

Condensing osteitis of the clavicle was first described as a disease entity in 1974. There is painful localised swelling of the clavicle of undetermined origin, with increased radio-density, but an infective aetiology has not been excluded by previous authors. We report three children with the clinical and radiological findings of 'condensing osteitis'. Two of them had raised levels of antistaphylolysin titres and all responded to antibiotic therapy. We conclude that condensing osteitis is due to low-grade staphylococcal osteomyelitis; biopsy and treatment by antibiotics is recommended.

Potential value of antisera to epithelial membrane antigen in detecting early invasion in transitional cell carcinoma.

The distribution of epithelial membrane antigen in human transitional epithelium using immunocytochemical techniques was investigated. In normal urothelium the antigen is restricted to the luminal surface and superficial cell cytoplasm. During neoplastic progression cytoplasmic staining of intermediate and basal cells is seen. In certain circumstances staining is seen at the interface between the stroma and tumour. The latter appearance correlates with the presence of invasion as assessed by conventional histology and may help to identify early invasion in difficult cases.

Prognostic factors in non-infiltrating carcinoma of the bladder: a preliminary report.

We have reviewed 111 patients with papillary transitional cell carcinoma of the bladder, category Ta and T1, admitted between 1975 and 1980. Histological grade and the presence of multiple tumours at presentation were the most useful prognostic features in terms of recurrence and mortality from either locally invasive or metastatic disease.