Molecular cloning of HSP70 in Mycoplasma ovipneumoniae and comparison with that of other mycoplasmas.

Mycoplasma ovipneumoniae, a bacterial species that specifically affects ovine and goat, is the cause of ovine infectious pleuropneumonia. We cloned, sequenced and analyzed heat shock protein 70 (HSP70) (dnaK) gene of M. ovipneumoniae. The full length open reading frame of the M. ovipneumoniae HSP70 gene consists of 1812 nucleotides, with a G+C content of 34.16%, encoding 604 amino acids. Comparative analysis with the HSP70 sequences of 15 Mycoplasma species revealed 59 to 87% DNA sequence identity, with an amino acid sequence identity range of 58 to 94%. M. ovipneumoniae and M. hyopneumoniae shared the highest DNA and amino acid sequence identity (87 and 94%, respectively). Based on phylogenetic analysis, both the DNA and amino acid identities of M. ovipneumoniae with other mycoplasmal HSP70 were correlated with the degree of relationship between the species. The C-terminus of the HSP70 was cloned into a bacterial expression vector and expressed in Escherichia coli cells. The recombinant C-terminal portion of HSP70 protein strongly reacted with convalescent sera from M. ovipneumoniae-infected sheep, based on an immunoblotting assay. This indicates that HSP70 is immunogenic in a natural M. ovipneumoniae infection and may be a relevant antigen for vaccine development.

[Synthesis of tyrosine-related peptide and their effect on progesterone production].

Twenty peptides containing hydroxy-amino acids have been synthesized manually by stepwise solid-phase procedure. The chloromethyl resin and MBHA resin were used as solid supports. A new reagent of 0.5 mol.L-1 DDSi/1.5 mol.L-1 phenol/DCM was applied for the removal of N alpha-Boc group. TFMSA was the cleaving reagent. After purification by C-18 column; all products were assayed according to amino acid analysis. The bioactivity of synthetic peptides was tested for the effect on progesterone production in vitro. Eight peptides, GlyTyrAlaLys, (SarSer)2Lys and its methyl ester, TyrLys, HisTyr-NH2, ThrProTyrLys-NH2 TyrThrProArgLys and AspHisProThrPheLys showed significant effect on inhibiting hCG-induced progesterone production, and first three of them could also inhibit basal progesterone secretion. However, peptide GlySerTyr exhibited stimulative activity on basal progesterone secretion. So far, no reasonable relationship between structure and bioactivity was found.

Piezoelectric composites with high sensitivity and high capacitance for use at high pressures.

A type of piezoelectric composite has been developed for oceanographic applications. The composites have a large figure of merit (d(h)xg(h) or d(h )xg(h)/tan delta, where d(h ) is the hydrostatic piezoelectric voltage coefficient), a large dielectric constant (K) and low dielectric loss, and great mechanical strength. A shallow cavity between the PZT ceramics and thick metallic electrode is designed to convert a portion of the z-direction stress into a large radial and tangential stress of opposite sign. thereby causing the d(33) and d(31) contributions to d(h) to add rather than subtract, and raising the figure of merit. Theoretical stress analysis was carried out using an axisymmetric finite element method. Experimental results show that the d(h)x g(h), K, and withstandable pressure are extremely high.

A modified thickness extensional disk transducer.

Photolithography and chemical etching were investigated as a means of patterning miniature piezoelectric devices. Using a processing procedure analogous to that utilized in the production of integrated circuitry, concentrated hydrochloric acid and a commercially available photoresist were used to fabricate a number of complex structures from soft lead zirconate titanate (PZT) substrates. Among the devices produced in this manner was a modified thickness-mode resonator etched to destroy the simple geometry responsible for radial vibrations. The resultant transducer demonstrated significantly smaller amplitudes for lateral resonances and a marked reduction in the effective planar coupling coefficient over the unaltered disk. The results indicate that photolithographic patterning is useful both for eliminating spurious resonances from transducers for medical imaging or nondestructive evaluation and for engineering low planar coupling coefficients into a variety of substrate materials.