Novel fimbriae were isolated and purified from the human enteropathogen SalmoneUa enteritidis 27655. These fimbriae were thin (measuring 3 to 4 nm in diameter), were extremely aggregative, and remained cell associated despite attempts to separate them from blended cells by centrifugation. The thin fimbriae were not solubilized in 5 M NaOH or in boiling 0.5% deoxycholate, 8 M urea, or 1 to 2% sodium dodecyl sulfate (SDS) with or without 5% 13-mercaptoethanol. Therefore, an unconventional purification procedure based on the removal of contaminating cell macromolecules in sonicated cell extracts by enzymatic digestion and preparative SDS-polyacrylamide gel electrophoresis (PAGE) was used. The insoluble fimbriae recovered from the well of the gel required depolymerization in formic acid prior to analysis by SDS-PAGE. Acid depolymerization revealed that the fimbriae were composed of fimbrin subunits, each with an apparent molecular mass of 17 kDa. Although their biochemical characteristics and amino acid composition were typical of fimbriae in general, these thin fimbriae were clearly distinct from other previously characterized fimbriae. Moreover, their fimbrin subunits had a unique N-terminal amino acid sequence. Native fimbriae on whole cells were specifically labeled with immune serum raised to the purified fimbriae. This immune serum also reacted with the denatured 17-kDa fimbrin protein in Western blots. The polyclonal immune serum did not cross-react with the other two native fimbrial types produced by this strain or with their respective fimbrins on Western blots (immunoblots). Therefore, these fimbriae represent the third fimbrial type produced by the enteropathogen S. enteritidis.

The gene encoding the major outer sheath protein (Msp) of the oral spirochete Treponema denticola ATCC 35405 was cloned, sequenced, and expressed in Escherichia coli. Preliminary sequence analysis showed that the 5 end of the msp gene was not present on the 5.5-kb cloned fragment described in a recent study ( showing the msp transcript to be approximately 1.7 kb was consistent with the identification of a promoter consensus sequence located optimally upstream of msp and a transcription termination signal found downstream of the stop codon. The entire msp sequence was amplified from T. denticola genomic DNA and cloned in E. coli by using a tightly regulated T7 RNA polymerase vector system. Expression of Msp was toxic to E. coli when the entire msp gene was present. High levels of Msp were produced as inclusion bodies when the putative signal peptide sequence was deleted and replaced by a vector-encoded T7 peptide sequence. Recombinant Msp purified to homogeneity from a clone containing the full-length msp gene adhered to immobilized laminin and fibronectin but not to bovine serum albumin. Attachment of recombinant Msp was decreased in the presence of soluble substrate. Attachment of T. denticola to immobilized laminin and fibronectin was increased by pretreatment of the substrate with recombinant Msp. These studies lend further support to the hypothesis that Msp mediates the extracellular matrix binding activity of T. denticola.

We report that the ͑Ba, K͒Fe 2 As 2 crystal with T c = 32 K shows a pinning potential, U 0 , as high as 10 4 K, with U 0 showing very little field dependence. The ͑Ba, K͒Fe 2 As 2 single crystals become isotropic at low temperatures and high magnetic fields, resulting in a very rigid vortex lattice, even in fields very close to H c2 . The isotropic rigid vortices observed in the two-dimensional ͑2D͒ ͑Ba, K͒Fe 2 As 2 distinguish this compound from 2D high-T c cuprate superconductors with 2D vortices. The vortex avalanches were also observed at low temperatures in the ͑Ba, K͒Fe 2 As 2 crystal. It is proposed that it is the K substitution that induces both almost isotropic superconductivity and the very strong intrinsic pinning in the ͑Ba, K͒Fe 2 As 2 crystal.A high critical current density, J c , upper critical field, B c2 , and irreversibility field, B irr , a high superconducting transition temperature, T c , strong magnetic-flux pinning, good grain connectivity, and isotropic superconductivity are the major physical requirements for superconducting materials used in practical applications operating at low and, in particular, high magnetic fields. The conventional low-T c superconductors, where H c2 is also small, can only carry large J c at very low temperatures. The cuprate high-T c superconductors suffer from poor grain connectivity and easy melting of the vortex lattice, leading to small J c in high magnetic fields at relatively high temperatures. For MgB 2 superconductor with T c of 39 K, B irr is far below H c2 , and J c drops quickly with both field and temperature, preventing its use above 20 K. The newly discovered Fe-based superconductors 1-7 show T c as high as 55 K and B c2 above 200 T, in combination with a small anisotropy for REFeAsO 1−x F x ͑RE-1111 phase, with RE a rare-earth element͒ 8 and an almost isotropic superconductivity for ͑Ba, K͒Fe 2 As 2 ͑122 phase͒. 9 These properties make the Fe-based superconductors extremely promising candidates for high magnetic field applications at relatively high temperatures. The current carrying ability of these superconductors at high fields and temperatures is largely determined by the flux-pinning strength and the behavior of the vortex matter. Therefore, the determination of their intrinsic vortex pinning strength is a central issue from both an applied and a fundamental perspective. Both 1111 and 122 phase compounds have typical two-dimensional ͑2D͒ crystal structures. In RE-1111 phase, where RE is a rare-earth element, the FeAs superconducting layers are separated by insulating LaO layers 10 while in Ba͑K͒-122 phase, the FeAs layer is sandwiched between conductive Ba layers. 5 It is expected that the 122 phase containing two FeAs layers would have small anisotropy and thus higher intrinsic pinning compared to the single layer 1111 phase. Co-doped BaFe 2 As 2 single crystal shows an anisotropy of 1-3 and upper criticalfield values of B c2 ͑B ʈ ab͒ = 20 T and B c2 ͑B ʈ c͒ = 10 T at 20 K, with dB c2 / dT Ϸ 5 T/ K. 11 For single crystals of the optimally do...

The major surface protein (Msp) of Treponema denticola has been implicated as a mediator of the interaction between the spirochete and the gingival epithelium in periodontal diseases. Previous studies showed that the Msp of T. denticola ATCC 35405 had porin activity, depolarized epithelial cell membranes, bound to extracellular matrix components of epithelial cells, and formed a regular hexagonal surface array in the treponemal outer membrane.

Treponema denticola surface proteins were studied for their biochemical and biological characteristics.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of detergent extracts of whole cells revealed a major protein of 53 kDa and a number of minor proteins. Antiserum raised against whole cells of T. denticola ATCC 35405 reacted with the 53-kDa protein and a 72-kDa protein but not with the other proteins. Immunoelectron microscopy with anti-53-kDa-protein antibodies showed that the 53-kDa protein is located on the surface of the cell. SDS-PAGE analysis of unheated samples indicated that the 53-kDa protein is the major component of oligomers with molecular masses ranging from 130 to 300 kDa. Western blot (immunoblot) analysis showed that the high-molecular-mass oligomers reacted with whole-cell antiserum and anti-53-kDa-protein antibody. The aggregates dissociated into their subunits after heating to 70°C. Isoelectric focusing followed by SDS-PAGE indicated that the 53-kDa protein was separated into several forms with apparent pl values ranging from 8.0 to 5.5. The oligomeric forms were highly resistant to proteolysis by trypsin and proteinase K, whereas the monomeric proteins were readily digested. A clone expressing a 53-kDa antigen in Escherichuz coli was isolated from a lambda ZAP II DNA library of T. denticola ATCC 35405. The recombinant protein had exactly the same molecular mass as the major 53-kDa T. denticola surface protein and reacted with antisera raised against this protein. The role of T. denticola ATCC 35405 surface proteins in attachment to laminin, fibronectin, gelatin, fibrinogen, and bovine serum albumin (BSA) was studied by a modified Western blot binding assay. Fibronectin, laminin, and fibrinogen attached to the 53-kDa surface protein of T. denticola as well as to a 72-kDa protein, whereas no attachment to gelatin or BSA was observed. Attachment could be inhibited by pretreating the blots with fibrinogen but not with gelatin or BSA. Our results suggest that the 53-kDa major surface protein of T. denticola may play a role in the attachment to host proteins and may thus be an important virulence determinant of this species.