Molecular mimicry and ankylosing spondylitis: possible role of a novel sequence in pullulanase of Klebsiella pneumoniae.

Molecular mimicry has been shown between two sequences of Klebsiella pneumoniae pulD secretion protein (DRDE) with HLA-B27 (DRED) and pulA (pullulanase) enzyme (Gly-X-Pro) with types I, III and IV collagen respectively. IgG antibody levels in AS patients were elevated against 16mer synthetic peptides of HLA-B27 and pulD by enzyme immunosorbent assay (ELISA) compared to controls (P < 0.001).

Computer control of carbon-nitrogen ratio in Spirulina platensis.

An on-line computer was used to control the ratio of carbon to nitrogen in algal biomass. An indirect method of growth and biomass estimation was utilized. This was based on balancing the amount of CO(2) carbon in and out of the algal bioreactor.

Maximum photosynthetic efficiency: a problem to be resolved.

The great disarray in the measurements of the maximum efficiency of conservation of light energy in photosynthesis is an outstanding problem in the development of photosynthetic biotechnology. The short-term measurements of the efficiency based on O(2) release by suspensions of cells or chloroplasts have given minimum quantum demands between 4 and 12 hv/O(2). The defect of the short term measurements is that the effects of growth conditions, which can alter the efficiency by a factor of 2, have been generally ignored.

Maintenance energy: a general model for energy-limited and energy-sufficient growth.

The new model proposed to account for the energy requirement for growth includes both a constant maintenance energy term (m) independent of the specific growth rate and a term (m') which decreases linearly with increase in specific growth rate and becomes zero at the maximum specific growth rate. The available data for testing the model do not deviate significantly from the relations predicted. Consistent values of the maximum growth yield (YG) can be derived, irrespective of whether the cultures are energy limited or energy sufficient.

Conversion of glucose to fatty acids and methane: roles of two mycoplasmal agents.

Two species of obligately anaerobic mycoplasmas were the major components of a methanogenic glucose-limited enrichment culture. In pure culture, one of these organisms, tentatively named Anaeroplasma sp. strain London, was shown to be responsible for the fermentation of glucose to fatty acids, hydrogen, and carbon dioxide; the other mycoplasma was shown to produce methane from hydrogen and carbon dioxide and was named Methanoplasma elizabethii.

Chemically-defined media for production of insect cells and viruses in vitro.

Two chemically-defined media are described. They support the growth of a) an established cell line of Spodoptera frugiperda cells and b) two established mosquito cell lines from Aedes aegypti and Anopheles gambiae. The replication of Autographa californica Nuclear Polyhedrosis Virus (ACNPV) in S.

Growth of human diploid cells (strain MRC-5) in defined medium; replacement of serum by a fraction of serum ultrafiltrate.

A calf serum ultrafiltrate fraction permitted growth for at least 3.5 generations, including one subculture, of MRC-5 cells in defined medium in the absence of whole serum. The active material has a molecular weight of 10 000 Daltons or less.

Biomass yields of Chlorella from iron (Yx/Fe) in iron-limited batch cultures.

The maximum biomass in iron-limited photosynthetic batch cultures of chlorella increased as the logarithm of the iron concentration. The growth yield from iron (UxFe) showed a marked inverse relation to the specific growth rate. The maximum biomass yield, g dry biomass/g iron consumed, was 7.

Development of the agar disk method for the rapid selection of cephalosporin producers with improved yields.

To screen the abilities of mutant strains of Cephalosporium to produce cephalosporin C, colonies of the organism were grown on the surface of small (4-mm diameter) disks of agar medium. After incubation of the disks for periods of up to 5 days, the antibiotic contents of the disks were assayed by placing them on agar plates of the assay organism and determining the diameters of the inhibition zones. The amount of nitrogen source in the agar disk medium was used to control the amount of antibiotic produced in the disk and, thus, the sensitivity of screening.

Nutrition and factors limiting the growth of a methanogenic bacterium (Methanobacterium thermoautotrophicum).

The purification of Methanobacterium thermoautotrophicum from a culture contaminated with a heterotrophic organism is described. A defined inorganic medium under H2/CO2 (80:20 v/v) has been developed to support growth of M. thermoautotrophicum up to a concentration of at least 1.

The nutrient requirements of MRC-5 human diploid cells.

Nutrients were assayed by their effect on maximum cell yield (maximum cell population less inoculum) of MRC-5 cells previously maintained in Eagle's basal medium with 10% (v/v) serum, trypsinised, centrifuged and washed. When nonlimiting amounts of iron, methylcellulose and a 68-component supplement were included in our defined medium, cell yields obtained were equivalent to those obtained with 2 to 3% whole serum. Growth then became limited by serum growth factors which, when serum was fractionated by the low temperature ethanol procedure, appeared to precipitate with the alpha-globulins, although the distribution of activity varied from batch to batch of serum.

Factors influencing the formation and stability of D-glucoside 3-dehydrogenase activity in cultures of Agrobacterium tumefaciens.

D-glucoside 3-dehydrogenase specific activity in Agrobacterium tumefaciens was maximal towards the end of the exponential growth phase of batch cultures; over 90% of the activity disappeared within the next 15 h. Manganese ions, although essential for growth of the organism, strongly repressed D-glucoside 3-dehydrogenase synthesis in sucrose medium but had little effect when the carbon source was methyl alpha-D-glucoside. D-Glucoside 3-dehydrogenase activity increased linearly with increasing specific growth rate in chemostat cultures limited by carbon, nitrogen, phosphate or manganese when methyl alpha-D-glucoside was the carbon source.

Growth dynamics of Agrobacterium tumefaciens in chemostat cultures limited by carbon source and mineral nutrients.

Agrobacterium tumefaciens was grown in a chemostat in a chemically-defined medium which hs alpha-methyl D-glucoside, magnesium, manganese, phosphate or urea as the growth-limiting nutrient. Steady-state biomass concentrations were dependent on the specific growth rate of the organism when alpha-methyl D-glucoside, manganese or phosphate were growth-limiting nutrients. During magnesium-limited growth, large undamped oscillations in biomass concentration occurred.

The quantitative requirements of human diploid cells (strain MRC-5) for amino acids, vitamins and serum.

The uptakes of all essential amino acids, vitamins (except riboflavin), glucose and serum during growth of human diploid cells (MRC-5) were determined. The amino acid uptakes varied considerably with the conditions of culture. The glucose requirement is several times greater than that for mouse LS or human HeLa cells.