Ring chromosome 15 in a mother and her children

Summary A case of ring chromosome 15 passed on to the index patient's two children is reported, and possible reasons for the infrequent records of inheritance of ring chromosome are suggested.     

New PCR-RFLP analysis for the mouse Tnfsf6gld gene caused by a point mutation in the Tnfsf6 [tumor necrosis factor (ligand) superfamily, member 6] locus.

A new polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was developed for genetic typing of the mouse Tnfsf6gld mutation. An artificial restriction site was introduced to the mouse Tnfsf6gld mutation by PCR amplification using a modified primer. The three genotypes of the Tnfsf6 locus (Tnfsf6gld/Tnfsf6gld, Tnfsf6gld/+, and +Tnfsf6-gld/+Tnfsf6-gld) could be distinguished clearly and easily. This PCR-RFLP analysis was found to be useful for the identification of the mouse Tnfsf6gld mutation.     

An algorithmic approach to constructing the on-line estimation system for the specific growth rate

The objective of this article is to propose an algorithm for the on-line estimation of the specific growth rate in a batch or a fed-batch fermentation process. The algorithm shows the practical procedure for the estimation method utilizing the macroscopic balance and the extended Kalman filter. A number of studies of the on line estimation have been presented. However, there are few studies discussing about the selection of the observed variables and for the tuning of some parameters of the extended Kalman filter, such as covariance matrix and initial values of the state.The beginning of this article is devoted to explain the selection of the observed variable. This information is very important in terms of the practical know-how for using technique. It is discovered that the condition number is a practically useful and valid criterion for number is a practically useful and valid criterion for choosing the variable to be observed.Next, when the extended Kalman filter in applied to the online estimation of the specific growth rate, which is directly unmeasurable, criteria for judging the validity of the estimated value from the observed data are proposed. Based on the proposed criterial, the system equation of the specific growth rate is selected and initial value of the state variable and covariance matrix of the system noises are adjusted. From many experiments, it is certified that the specific growth rate in the batch or fed -batch fermentation can be estimated accurately by means of the algorithm proposed here. In these experiments, that is, when the cell concentration is measured directly, the extended Kalman filter using the convariance matrix with a constant element can estimate more accurately values of the specific growth rate than the adaptive extended Kalman filter does.     

Transmembrane diffusion of hydrophobic antimicrobial agents and cell surface hydrophobicity in Bacteroides fragilis

The transmembrane diffusion of hydrophobic antimicrobial agents, e.g. lincomycin and clindamycin, was examined in Bacteroides fragilis which is sensitive to these agents. The results showed that these agents penetrate efficiently through the outer membrane. Cell surface hydrophobicity measured by the partition assay between water and p-xylene revealed that the cell surface of B. fragilis is more hydrophobic than that of Salmonella typhimurium or Pseudomonas aeruginosa. Furthermore, treatment with low concentrations of surfactant caused cell lysis. These results suggest that the cell surface hydrophobicity in B. fragilis plays an important role in the efficient transmembrane penetration of hydrophobic compounds. This efficiency explains the susceptibility of B. fragilis to hydrophobic antimicrobial agents.     

Variation of Phosphoenolpyruvate Carboxylase Activity in Dunaliella Associated with Changes in Atmospheric CO2 Concentration

In Dunaliella tertiolecta, D. bioculata and D. viridis the activitiesof phosphoenolpyruvate carboxylase and carbonic anhydrase werehigher in the cells grown in ordinary air (low-CO₂ cells) thanin those grown in air enriched with 1–5% CO₂ (high-CO₂cells), whereas in Porphyridium cruentum R-1 there was no differencein phosphoenolpyruvate carboxylase activity between these twotypes of cells. Apparent K_m(NaHCO₃) values for photosynthesisin low-CO₂ cells of all species tested were smaller than thosein high-CO₂ cells. Most of the ¹⁴C was incorporated into 3-phosphoglycerate,sugar mono- and di-phosphates during the initial periods ofphotosynthetic NaH¹⁴CO₃ indicating that both types of cellsin D. tertiolecta are C₃ plants. (Received May 27, 1985; Accepted June 25, 1985)     

Effect of resting smooth muscle length on contractile response in resistance airways

We studied the effect of resting smooth muscle length on the contractile response of the major resistance airways (generations 0-5) in 18 mongrel dogs in vivo using tantalum bronchography. Dose-response curves to 10(-10) to 10(-7) mol/kg methacholine (MCh) were generated [at functional residual capacity (FRC)] by repeated intravenous bolus administration using tantalum bronchography after each dose. Airway constriction varied substantially with dose-equivalent stimulation and varied sequentially from trachea (8.8 +/- 2.2% change in airway diam) to fifth-generation bronchus (49.8 +/- 3.0%; P less than 0.001). Length-tension curves were generated for each airway to determine the airway diameter (i.e., resting in situ smooth muscle length) at which maximal constriction was elicited using bolus intravenous injection of 10(-8) mol/kg MCh. A Frank-Starling relationship was obtained for each airway; the transpulmonary pressure at which maximal constriction was elicited increased progressively from 2.50 +/- 1.12 cmH2O for trachea (approximately FRC) to 18.3 +/- 1.05 cmH2O for fifth-generation airways (approximately 50% TLC) (P less than 0.001). A similar relationship was obtained when change in airway diameter was plotted as a function of airway radius. We demonstrate substantial heterogeneity in the lung volumes at which maximal constriction is elicited and in distribution of parasympathomimetic constriction within the first few generations of resistance bronchi. Our data also suggest that lung hyperinflation may lead to augmented airway contractile responses by shifting resting smooth muscle length toward optimum resting smooth muscle length.     

Cloning and functional analysis of molecular chaperone genes from Bacillus stearothermophilus SIC1

Genes homologous to groES and groEL, which are recognized as molecular chaperone genes, from Bacillus stearothermophilus SIC1 were cloned and sequenced. By addition of GroES, GroEL and ATP in vitro, remaning activity of the alcohol dehydrogenase from Saccharomyces cerevisiae after heat treatment at 50°C for 6 min was improved from 55% to 90%. Furthermore, even though inclusion bodies were formed when a single chain Fv(sFv) was expressed in E. coli cells, during in vivo coexpression with molecular chaperone, a significant amount of the antibody protein could be recovered from the soluble fraction.     

Coevolution of Bacteriophage PP01 and Escherichia coli O157:H7 in Continuous Culture

The interaction between Escherichia coli O157:H7 and its specific bacteriophage PP01 was investigated in chemostat continuous culture. Following the addition of bacteriophage PP01, E. coli O157:H7 cell lysis was observed by over 4 orders of magnitude at a dilution rate of 0.876 h⁻¹ and by 3 orders of magnitude at a lower dilution rate (0.327 h⁻¹). However, the appearance of a series of phage-resistant E. coli isolates, which showed a low efficiency of plating against bacteriophage PP01, led to an increase in the cell concentration in the culture. The colony shape, outer membrane protein expression, and lipopolysaccharide production of each escape mutant were compared. Cessation of major outer membrane protein OmpC production and alteration of lipopolysaccharide composition enabled E. coli O157:H7 to escape PP01 infection. One of the escape mutants of E. coli O157:H7 which formed a mucoid colony (Mu) on Luria-Bertani agar appeared 56 h postincubation at a dilution rate of 0.867 h⁻¹ and persisted until the end of the experiment (~200 h). Mu mutant cells could coexist with bacteriophage PP01 in batch culture. Concentrations of the Mu cells and bacteriophage PP01 increased together. The appearance of mutant phage, which showed a different host range among the O157:H7 escape mutants than wild-type PP01, was also detected in the chemostat culture. Thus, coevolution of phage and E. coli O157:H7 proceeded as a mutual arms race in chemostat continuous culture.