Participation of mitochondrial proliferation in morphological differentiation of murine mastocytoma cells

Proliferation of a cold-sensitive cell-cycle mutant isolated from an undifferentiated murine mastocytoma line is reversibly arrested at the nonpermissive temperature of 33 degrees C, and the arrested cells undergo morphological differentiation as expressed by the formation of metachromatic granules. Following transfer of these mutant cells from the permissive temperature of 39.5 to 33 degrees C, a transient increase in both cytochrome c oxidase and DNA polymerase gamma was observed, the ratio of total mitochondrial volume to cell volume nearly doubled within 6 days, and numbers of mitochondrial cross-sections per cellular cross-section as determined in electron micrographs underwent a threefold increase. Addition of chloramphenicol (100 micrograms/ml) to the mutant cell cultures 6 days prior to transfer from 39.5 to 33 degrees C prevented the increase in the ratio of total mitochondrial to cell volume. Furthermore, chloramphenicol markedly inhibited the increase in granule number per cell that normally is observed after transfer of cultures to 33 degrees C or during treatment with 1 mM butyrate, suggesting that mitochondrial proliferation may be an obligatory step in the process of morphological differentiation of these mastocytoma cells.     

Cell-type preference of immunoglobulin kappa and lambda gene promoters.

Immunoglobulin gene constant regions are known to be associated with strictly tissue-specific enhancer elements. Until recently the promoter of the variable region, which becomes linked to the constant region by somatic rearrangement, could have been viewed as a passive recipient of the enhancer stimulus. Here we show that the promoters of the immunoglobulin kappa and lambda light chain genes are approximately 20-30 times more active in lymphoid cells than in non-lymphoid cells. To avoid the problem of differential mRNA stability upon transfection of immunoglobulin genes into non-lymphoid cells we have constructed chimeric genes. All kappa mRNA sequences were progressively deleted to fuse the kappa gene promoter to a globin gene coding body. A similar chimeric gene was constructed with the promoter of the lambda gene. The cell-type preference of the promoter may be exploited during B-lymphocyte differentiation to regulate the immunoglobulin gene promoter independently from the enhancer.     

CHANGES IN HEPATIC STRUCTURE IN RATS PRODUCED BY BREATHING PURE OXYGEN

The livers of rats exposed to pure oxygen were examined electron microscopically to study toxic effects of oxygen in a metabolically sensitive organ. Pressures of 1/3 (258 mm Hg), 1 (760 mm Hg), and 3 (2280 mm Hg) atmospheres were used, with exposures up to 90 days with the lowest pressures. The first changes in the hepatocytes were loss of glycogen and enlargement of mitochondria with development of mitochondria with bizarre shapes which were seen after 3 days at 258 mm, 1 day at 760 mm, and 3 hours at 2280 mm. These changes were followed by formation of increased numbers of cristae, membranes surrounding mitochondria, autophagic vacuoles, and polyribosome clusters. After 2 weeks at 258 mm, which is the pressure of the atmosphere of space cabins, numerous mitochondrial myelin figures appeared but the mitochondrial enlargement had begun to regress. After 90 days at 258 mm, the liver cells appeared almost normal except that many pigment granules had accumulated in the pericanalicular zones. The changes were non-specific and seemed to parallel biochemical alterations recorded elsewhere. They are not considered the result of toxicity but rather of adaptation. These atmospheres, which are used in clinical medicine and in space travel, appear to have no permanent deleterious effects on the liver in rats under the conditions of this experiment.     

A microdeletion of less than 250 kb, including the proximal part of the FMR-1 gene and the fragile-X site, in a male with the clinical phenotype of fragile-X syndrome

A gene designated "FMR-1" has been isolated at the fragile-X locus. One exon of this gene is carried on a 5.1-kb EcoRI fragment that exhibits length variation in fragile-X patients because of amplification of or insertion into a CGG-repeat sequence. This repeat probably represents the fragile site. The EcoRI fragment also includes an HTF island that is hypermethylated in fragile-X patients showing absence of FMR-1 mRNA. In this paper, we present further evidence that the FMR-1 gene is involved in the clinical manifestation of the fragile-X syndrome and also in the expression of the cellular phenotype. A deletion including the HTF island and exons of the FMR-1 gene was detected in a fragile X-negative mentally retarded male who presented the clinical phenotype of the fragile-X syndrome. The deletion involves less than 250 kb of genomic DNA, including DXS548 and at least five exons of the FMR-1 gene. These data support the hypothesis that loss of function of the FMR-1 gene leads to the clinical phenotype of the fragile-X syndrome. In the fragile-X syndrome, there are pathogenetic mechanisms other than amplification of the CGG repeat that do have the same phenotypic consequences.     

Evaluation of data transformations used with the square root and schoolfield models for predicting bacterial growth rate.

A comparison was made between mathematical variations of the square root and Schoolfield models for predicting growth rate as a function of temperature. The statistical consequences of square root and natural logarithm transformations of growth rate use in several variations of the Schoolfield and square root models were examined. Growth rate variances of Yersinia enterocolitica in brain heart infusion broth increased as a function of temperature. The ability of the two data transformations to correct for the heterogeneity of variance was evaluated. A natural logarithm transformation of growth rate was more effective than a square root transformation at correcting for the heterogeneity of variance. The square root model was more accurate than the Schoolfield model when both models used natural logarithm transformation.     

Xp-duplications with and without sex reversal

Duplications in Xp including the DSS (dosage sensitive sex reversal) region cause male to female sex reversal. We investigated two patients from families with Xp duplications. The first case was one of two sisters with karyotype 46,XY, der(22), t(X;22)(p11.3;p11)mat and unambiguous female genitalia. The living sister was developmentally retarded, and showed multiple dysmorphic features and an acrocallosal syndrome. The second case was a boy with a maternally inherited direct duplication of Xp21.3-pter with the breakpoint close to the DSS locus. He had multiple abnormalities and micropenis, but otherwise unambiguous male genitalia. We performed quantitative Southern blot analysis with probes from Xp22.13 to p21.2 to define the duplicated region. Clinical, cytogenetic, and molecular data from both patients were compared with those of previously reported related cases. A comparison of the extragenital symptoms revealed no differences between patients with or without sex reversal. In both cases, the symptoms were non-specific. Among 22 patients with a duplication in Xp, nine had unambiguous female genitalia and a well-documented duplication of the DSS region. Two patients with duplication of DSS showed ambiguous external genitalia. From these data, we conclude that induction of testicular tissue may start in these patients, but that the type of genitalia depends on the degree of subsequent degeneration by a gene in DSS.     

Computer Simulation of Clostridium botulinum Strain 56A Behavior at Low Spore Concentrations

It is generally assumed that spore behavior is independent of spore concentration, but recently published mathematical models indicate that this is not the case. A Monte Carlo simulation was employed in this study to further examine the independence assumption by evaluating the inherent variance in spore germination data. All simulations were carried out with @Risk software. A total of 500 to 4,000 iterations were needed for each simulation to reach convergence. Lag time and doubling time from a higher inoculum concentration were used to simulate the time to detection (TTD) at a lower inoculum concentration under otherwise identical environmental conditions. The point summaries of the simulated and observed TTDs were recorded for the 26 simulations, with kinetic data at the target inoculum concentration. The ratios of the median (R_m = median_obs/median_sim) and 90% range (R_r = 90% range_obs/90% range_sim) were calculated. Most R_m and R_r values were greater than one, indicating that the simulated TTDs were smaller and more homogeneous than the observed ones. R_r values departed farther from one than R_m values. Ratios obtained when simulating 1 spore with 10,000 spores deviated the farthest from one. Neither ratio was significantly different from the other when simulating 1 spore with 100 spores or simulating 100 spores with 10,000 spores. When kinetic data were not available, the percent positive observed at the 95th percentile of the simulated TTDs was obtained. These simulation results confirmed that the assumption of independence between spores is not valid.     

Turning in MFB-lesioned rats and antagonism of neuroleptic-induced catalepsy after lisuride and LSD.

The effects of lisuride, d-lysergic acid diethyl amide (LSD) and apomorphine were studied in rats with unilateral destruction of nigro-striatal nerve terminals either with 6-hydroxydopamine (6-OHDA) or 5, 6-dihydroxytryptamine (5,6-DHT). Lisuride at the dose of 50 μg kg^?1 i.p. induced contralateral turning for more than 4 hours while the circling induced by LSD (200 μg kg^?1) and apomorphine (1 mg kg^?1) persisted for only one hour. Lisuride, a compound stimulating both dopamine (DA) and 5-hydroxytryptamine (5-HT) receptors induced a more intense turning in 6-OHDA than in 5,6-DHT lesioned rats. This might indicate a modulation of 5-HT on rotational behavior. Haloperidol (1 mg kg^?1 i.p.) antagonized both lisuride- and LSD-induced turning. LSD, and much more persistently lisuride, counteracted the prochlorperazine-induced catalepsy. These findings correlate with the biochemical data indicating that lisuride is a very potent agonist at central dopaminergic receptors.