EGF-induced PGE2 release is synergistically enhanced in retinoic acid treated fetal rat lung cells

Retinoic acid has been shown to induce a 2.5-fold increase in 125I-EGF binding capacity through increased EGF receptor synthesis in a fetal rat lung (FRL) cell line (1). In FRL cells, incubation with either EGF or retinoic acid induces a modest increase in PGE2 secretion (80% or 40%, respectively). However, in the presence of both EGF and retinoic acid, FRL cells exhibit a 6.4-fold increase in PGE2 secretion. Retinoic acid and EGF dose-response curves demonstrate that the effect on PGE2 secretion correlates with the retinoic acid induced increase in EGF receptors. These data suggest a relationship between increased EGF receptor expression and increased EGF responsiveness. Furthermore, these data indicate a potential mechanism by which EGF and retinoic acid may interact in lung physiology.     

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO(2) Levels

Suspension cultures of cotton (Gossypium hirsutum), Amaranthus cruentus, A. powellii, Datura innoxia, and a Nicotiana tabacum-N. glutinosa fusion hybrid were adapted to grow photoautotrophically under continuous light. The cotton strain grew with an atmosphere of ambient CO₂ (about 0.06 to 0.07% in the culture room) while the other strains required elevated CO₂ levels (5%). Photoautotrophy was indicated by the requirement for CO₂ and for light for growth. The strains grew with doubling times near 14 days and had from 50 to 600 micrograms of chlorophyll per gram of fresh weight. The cells grew in small to moderate sized clumps with cell sizes from 40 to 70 micrometers (diameter). Like most photoautotrophic cultures described so far the ribulose 1,5-bisphosphate carboxylase (RuBPcase) activity levels were well below those of mature leaves. The phosphoenolpyruvate carboxylase levels were not elevated in the C₄Amaranthus species. The cells showed high dark respiration rates and had lower net CO₂ fixation under high O₂ conditions. Dark CO₂ fixation rates ranged from near 10 to 30% of that in light. Fluorescence emission spectra measurements show that the cell antenna pigments systems of the four strains examined are similar to that of chloroplasts of green plants. The cotton strain which was capable of growth under ambient CO₂ conditions showed the unique properties of a high RuBPcase activation level in ambient CO₂ and a stable ability to show net CO₂ fixation in 21% O₂ conditions.     

Linkage relationships of seven enzyme and two pigmentation loci in the snail Biomphalaria glabrata

Crossing experiments with inbred stocks of the snail (Biomphalaria glabrata) demonstrated that variants at two loci determining pigmentation and seven enzyme-determining loci exhibited normal Mendelian segregation ratios in F2 progeny. Among 39 pairwise comparisons for joint segregation, there was evidence of genetic linkage between a locus controlling mantle pigmentation (S) and 6-phosphogluconate dehydrogenase (Pgd) and confirmation of a previously described linkage between esterase-2 (Est-2) and catalase (Cat). Recombination fractions were estimated to be 17 +/- 4 for S-Pgd and 33 +/- 5 for Est-2-Cat. The remaining five loci--Acon-1, Pgm-1, Lap-1, Lap-2, and Pgd--assorted independently. This brings to 17 the number of loci examined for segregation and assortment in this medically important species. As Biomphalaria has a chromosome number n = 18, markers should soon be available for most or all of the linkage groups.     

Prenatal diagnosis of 21-hydroxylase deficiency congenital adrenal hyperplasia using the polymerase chain reaction

Summary We present an improved method for the prenatal diagnosis of congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. The polymerase chain reaction (PCR) was used to analyze DNA from an affected index case, the parents, and a cultured chorionic villus sample, for point mutations in the steroid 21-hydroxylase (CYP21) gene. We can predict that the fetus is an unaffected carrier.     

Reversible inhibition of osteoclastic activity by bone-bound gallium (III).

Gallium(III) is a new therapeutic agent for hypercalcemia. Ga3+ reduces osteoclast action, but how it inhibits the cell's physiology is unknown. In vivo, 7-12 microM Ga(III) reduces calcium release from bone, but surprisingly, 10-100 microM Ga3+ added to isolated avian osteoclasts did not reduce their degradation of L-(5-3H)-proline bone. 3H-proline labels bone collagen specifically, and collagenolysis is an excellent indicator of bone dissolution because collagen is the least soluble component of bone. Ga(III) greater than 100 microM inhibited osteoclasts in vitro, but also killed the cells. To resolve this apparent conflict, we measured 67Ga distribution between bone, cells, and media. Gallium binds avidly but slowly to bone fragments. One hundred micrograms of bone clears 60% of 1 microM gallium from 500 microliters of tissue culture medium, with steady state at greater than 24 h. Osteoclasts on bone inhibited gallium binding capacity approximately 40%, indicating a difference in available binding area and suggesting that osteoclasts protect their substrate from Ga binding. Less gallium binds to bone in serum-containing medium than in phosphate-buffered saline; 30% reduction of the affinity constant suggests that the serum containing medium competes with bone binding. Consequently, the effect of [Ga] on bone degradation was studied using accurately controlled amounts of Ga(III) pre-bound to the bone. Under these conditions, gallium sensitivity of osteoclasts is striking. At 2 days, 100 micrograms of bone pre-incubated with 1 ml of 1 microM Ga3+, with 10 pmoles Ga3+/micrograms bone, was degraded at 50% the rate of control bone; over 50 pM Ga3+/micrograms bone, resorption was essentially zero. In contrast, pre-treatment of bone with [Ga3+] as high as 15 microM had no significant effect on bone resorption rate beyond 3 days, indicating that gallium below approximately 150 pg/micrograms bone acts for a limited time and does not permanently damage the cells. We conclude that bone-bound Ga(III) from medium concentrations less than 15 microM inhibits osteoclasts reversibly, while irreversible toxicity occurs at solution [Ga3+] greater than 50 microM.     

Mapping of FMR1, the gene implicated in fragile X-linked mental retardation, on the mouse X chromosome

A genetic map of the Cf-9 to Dmd region of the mouse X chromosome has been established by typing 100 offspring from a Mus musculus x Mus spretus interspecific backcross for the four loci Cf-9, Cdr, Gabra3, and Dmd. The following order and genetic distances in centimorgans were determined: (Cf-9)-2.4 +/- 1.7-(Cdr)-2.0 +/- 1.4-(Gabra3)-4.1 +/- 2.0-(Dmd). Six backcross offspring carrying X chromosomes with recombination events in the Cdr-Dmd region were identified. These recombination events were used to define the position of Fmr-1, the murine homologue of FMR1, which is the gene implicated in the fragile X syndrome in man, and that of DXS296h, the murine homologue of DXS296. Both Fmr-1 and DXS296h were mapped into the same recombination interval as Gabra3 on the mouse X chromosome. These findings provide strong support for the concept that the order of loci lying in the Cf-9 to Gabra3 segment of the X chromosome is highly conserved between human and mouse.     

Effect of asynchronous transfer and oestrogen administration on survival and development of porcine embryos.

Results indicate that recovery of embryos on Days 11 and 13 of pregnancy was reduced for Day 5 embryos transferred to recipients on Day 6 of their oestrous cycle and was greatly reduced when embryos were transferred to recipients on Day 7 of the cycle (P less than 0.01). Administration of oestradiol-17 beta on Day 11 of the recipient's cycle did not appear to affect embryo development on Day 13. Day 6 embryos transferred to recipients on Day 8 of the oestrous cycle deteriorated rapidly within 24 h of transfer; there was no recovery of embryos from the uterus after 36 h. Treatment of pregnant gilts with 1 mg oestradiol-17 beta (i.v.) on Day 10.5 resulted in total embryonic loss by Day 23, but pregnancy rates of gilts treated with oestradiol-17 beta on Day 12 were similar to those of vehicle-treated gilts (60.6 vs. 71.4%).     

A temperature-sensitive lesion in the small subunit of the vaccinia virus-encoded mRNA capping enzyme causes a defect in viral telomere resolution.

Using pulsed-field gel electrophoresis, we demonstrated that the temperature-sensitive (ts) conditional lethal mutant ts9383 is, at the nonpermissive temperature, defective in the resolution of concatemeric replicative intermediate DNA to linear 185-kb monomeric DNA genomes. The resolution defect was shown to be the result of a partial failure of the mutant virus to convert the replicated form of the viral telomere to hairpin termini. In contrast to other mutants of this phenotype, pulse-labeling of viral proteins at various times postinfection revealed no obvious difference in the quantity or temporal appearance of members of the late class of polypeptides. Using the marker rescue technique, we localized the ts lesion in ts9383 to an approximately 1-kb region within the HindIII D fragment. Both the ts phenotype and the resolution defect were shown to be caused by a single-base C----T point mutation resulting in the conversion of the amino acid proline to serine in codon 23 of open reading frame D12. This gene encodes a 33-kDa polypeptide which is known to be the small subunit of the virus-encoded mRNA capping enzyme (E. G. Niles, G. J. Lee-Chen, S. Shuman, B. Moss, and S. S. Broyles, Virology 172:513-522, 1989). The data are consistent with a role for this capping enzyme subunit during poxviral telomere resolution.