Crystallization and preliminary X-ray investigation of a sarcoplasmic calcium-binding protein from amphioxus

Crystals of a sarcoplasmic Ca(2+)-binding protein from the protochordate amphioxus have been grown from solutions of ammonium sulfate. The crystals are orthorhombic, space group C222(1), with unit cell axes a = 59.6(1) A, b = 81.3(1) A and c = 82.4(1) A. There is one molecule in the asymmetric unit. The crystals diffract beyond 2.5 A and show less than 20% decline in diffraction intensities after a three day exposure to X-rays from a laboratory rotating anode source.     

Development of an enzyme immunoassay for the detection of Clostridium novyi type B alpha toxin

Clostridium novyi type B alpha toxin was purified to homogeneity and shown to have a molecular weight of 200 kD by SDS polyacrylamide gel electrophoresis. The toxin was toxoided and used to produce a pair of non-interfering monoclonal antibodies. Their specificity was confirmed by immunoblotting and bioassay. The monoclonal antibodies were used to develop an enzyme immunoassay which was more sensitive than bioassay, and permitted less than 1 ng/ml toxin to be detected in a rapid 10 min assay format. Use of the assay can eliminate the requirement for in vivo testing of novyi toxin and toxoid, provided measurements of biological activity are not required. Because of its speed and sensitivity, the assay can be used to monitor toxin production during fermentation and as an alternative to bioassay to measure antigen content during toxoiding and vaccine formulation.     

A 17-bp insertion and a Phe215----Cys missense mutation in the dihydrolipoyl transacylase (E2) mRNA from a thiamine-responsive maple syrup urine disease patient WG-34.

We have amplified the cDNA for the transacylase (E2) subunit of the branched-chain alpha-ketoacid dehydrogenase (BCKAD) complex from a thiamine-responsive MSUD cell line (WG-34) by the polymerase chain reaction. Sequencing of the amplified WG-34 cDNA showed a 17-bp insertion (AAATACCTTGTTACCAG) apparently resulting from an aberrant splicing of the E2 gene, and a missense (T----G) mutation that changes Phe215 to Cys in the E2 subunit. The existence of these two mutations was confirmed by probing the amplified E2 cDNA or genomic DNA with allele-specific oligonucleotides. The above results support the thesis that the thiamine-responsive MSUD patient (WG-34) is a compound heterozygote at the E2 locus. The implication of the E2 mutations for the thiamine-responsiveness observed in this patient is discussed.     

Dominant Mutators in ESCHERICHIA COLI

In this paper we report on the isolation and genetic analysis of a series of strong mutators mapping at five minutes on the E. coli chromosome. These mutations are dominant and show no evidence of interaction in merodiploids. Cultures grown in broth medium exhibit mutant frequencies five to six orders of magnitude higher than mut⁺ strains. Cultures propagated in minimal salts media mutate at rates one to three orders higher than wild-type. Three-factor crosses have been used to order these mutators relative to metD, proA, and a Tn10 insertion near five minutes.     

Actin acetylation in Drosophila tissue culture cells

In a permanent cell line derived from Drosophila embryos, cytoplasmic actin is produced as an unstable precursor, which is subsequently converted to a stable form. This conversion results in a reduction in isoelectric point, with no apparent change in molecular weight. The conversion involves an enzymatic acetylation, and results in an insensitivity to aminopeptidase digestion, suggesting N-terminal blockage. Both the acetylated and unacetylated actins can participate in the assembly of F-actin, but with different efficiencies.This work was supported by a grant from the NIH (GM 22866).     

Five-year perspective of the large-scale growth of mammalian cells in suspension culture

The Cell Culture Center at the University of Alabama in Birmingham was set up to produce large quantities of cells and their products from suspension cultured cell lines. This system has now been in operation for over five years and has been effective in producing large quantities of mammalian cells of murine and human origin. This article describes the system and some growth parameters which have been of importance for large-scale mammalian cell growth.     

Iron uptake with ferripyochelin and ferric citrate by Pseudomonas aeruginosa.

Pyochelin is an iron-binding compound produced by Pseudomonas aeruginosa and demonstrates siderophore activity by its involvement in iron transport. During the transport process, an energy-independent association of [55Fe]ferripyochelin with bacteria occurred within the initial 30 s of reaction, followed by an energy-dependent accumulation of iron. The energy-independent association with iron appeared to be at the surface of the bacteria because the iron could be washed from the cells with thioglycolate, whereas accumulated iron was not washed from the bacteria. Energy-independent association of iron with bacteria and energy-dependent accumulation of iron in the presence of ferripyochelin varied concomitantly in cells grown under various conditions, but pyochelin synthesis appeared to be controlled separately. 55Fe complexed with citrate was also taken up by P. aeruginosa with a lower level of initial cell association. Bacterial mechanisms for iron uptake from ferric citrate were present in cells grown in a variety of media and were in lowest levels in cells grown in citrate. The synthesis of bacterial components for iron uptake from ferric citrate and from ferripyochelin was inhibited by high concentrations of iron supplied in growth media.