Embryonic salivary gland epithelial branching activity is experimentally independent of epithelial expansion activity

Embryonic mouse submandibular salivary gland rudiments undergo morphogenesis in organ culture, characterized by extensive epithelial growth and expansion and repetitive branching activity. Tunicamycin, at a concentration of 25 ng/ml culture medium, decreases the degree of net protein accumulation by 83% and the degree of epithelial expansion by 70% compared to controls, over a 48-hr culture tenure. These decreases correlate with reduced incorporation of [3H]thymidine into DNA. Nevertheless, epithelial branching activity is uncompromised, undergoing an approximately 10-fold increase in lobe numbers, in both controls and tunicamycin-treated rudiments, during the same 48-hr period. The effect is most striking during the 24- to 48-hr culture interval, when controls and tunicamycin-treated rudiments each triple their lobe numbers and controls approximately double epithelial area, while tunicamycin virtually stops all epithelial expansion.     

DNA and RNA Levels in Bundle Sheath and Mesophyll Cells of Pearl Millett (Pennisetum americanum)

The DNA content of bundle sheath cells and mesophyll protoplasts from the C₄ plant pearl millet (Pennisetum americanum, Tift 23DB) was determined by microspectrophotometry to be 1.8 to 2.3 and 3.2 to 4.0 picograms/nucleus, respectively. Measurement of RNA by ultraviolet spectroscopy indicated that bundle sheath cells contain twice as much RNA as mesophyll cells.     

Floral-specific polypeptides of the Japanese morning glory

Polypeptides from stems, leaves, sepals, corollas, stamens and pistils of the Japanese morning glory (Ipomoea nil Roth (Pharbitis nil Chois.)) were separated by one- and two-dimensional gel electrophoresis and visualized by silver staining. The majority of polypeptides were expressed in two or more organs, while those specific to only one organ were comparatively rate. Among the polypeptides of the former class were two which appeared to be floral-specific. A 46-kDa (kilodalton) polypeptide was expressed in corollas, stamens and pistils, whereas a 32-kDa polypeptide was observed only in extracts prepared from reproductive organs. Polypeptide spots from the various organs were compared with those from leaves, and it was found that sepals and stems shared 40–50% of their polypeptides with leaves, whereas corollas, stamens and pistils shared 20% or less. The latter organs shared 120 polypeptides or roughly 15% of those identified in the floral extracts. Floralorgan-specific polypeptides comprised nearly 10% of the total floral polypeptides identified.Abbreviations kDa kilodalton - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecylsulfate     

Characterization and metabolism of ovine foetal lipids

1. Total phospholipid concentrations in liver, kidney and brain of the 140-day ovine foetus were only half of those in comparable maternal tissues. 2. Phosphatidylcholine was the predominant phospholipid in all foetal tissues examined. The most striking difference between foetal and maternal tissues in individual phospholipids was in the heart; foetal heart contained more ethanolamine plasmalogen than choline plasmalogen, whereas in adult tissue the concentration of these was reversed. Sphingomyelin content of foetal brain was only one-sixth of that of maternal brain tissue. 3. Oleic acid (18:1) was the predominant acid in the phospholipid extracted from foetal tissues, except in brain where palmitic acid (16:0) was slightly higher. In phospholipids from adult tissues there was a higher proportion of unsaturated fatty acids (linoleic acid, 18:2, and linolenic acid, 18:3) and a correspondingly lower proportion of oleic acid (18:1). The distribution of fatty acids in the neutral lipid fraction of foetal and maternal tissues was very similar; oleic acid (18:1) was generally the principal component. 4. (14)C derived from [U-(14)C]-glucose and [U-(14)C]fructose infused into the foetal circulation in utero was incorporated into the neutral lipids and phospholipids of heart, liver, kidney, brain and adipose tissue. 5. Phospholipid analysis revealed that the specific activity of phosphatidic acid was higher in liver than in other tissues. The specific activity of phosphatidylethanolamine was less than that of phosphatidylcholine in heart, but in other tissues they were about the same. The specific activities of phosphatidylinositol and phosphatidic acid in brain were very similar and were higher than the other components. The specific activity of phosphatidylserine was highest in liver and brown fat. 6. The pattern of incorporation of (14)C derived from [(14)C]glucose and [(14)C]fructose into foetal neutral lipids was similar. Diglyceride accounted for most of the radioactivity in brain, whereas triglyceride had more label in heart, liver, kidney and fat.     

Plasma clearance of radiolabelled IGF-1 in the late gestation ovine fetus

We investigated the distribution of radiolabelled IGF-1 in the late gestation ovine fetus by exclusion gel chromatography following intravenous injection of 125I rh (recombinant human) met-IGF-1 into the chronically instrumented fetal lamb (120-130 days, n = 7). One minute after injection of 125I rh met-IGF-1 into the fetal femoral vein, 20.9 +/- 3.1% of the counts circulated in the 150K binding protein region, 55.0 +/- 3.7% in the 50K binding protein region and 18.7 +/- 0.6% in the free or 7K region. The chromatographic profiles obtained in the fetus were in general similar to those previously seen in the adult sheep. After an initial equilibration phase the half life of IGF-1 associated with the 150K binding fractions were 412.1 +/- 103.6 min. Two phases of clearance were observed for IGF-1 in association with the 50K binding fractions, an initial phase with a half life of 30.6 +/- 4.5 min followed by a second phase with a half life of 202.3 +/- 10.3 min. The 7K or 'free' form of IGF-1 had an initial half life of 12.6 +/- 5.1 min. Chromatography of samples of fetal tracheal fluid, fetal urine, amniotic fluid, maternal uterine venous plasma and maternal systemic plasma showed no movement of intact IGF-1 out of the fetal circulation into the fetal fluids or into the maternal circulation. However, when simultaneous samples were obtained from the fetal femoral artery and umbilical vein, higher radioactivity was consistently observed in the fetal femoral artery raising the possibility of placental uptake of IGF-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Search for unstable DNA in schizophrenia families with evidence for genetic anticipation.

Evidence for genetic anticipation has recently become an important subject of research in clinical psychiatric genetics. Renewed interest in anticipation was evoked by molecular genetic findings of a novel type of mutation termed "unstable DNA." The unstable DNA model can be construed as the "best fit" for schizophrenia twin and family epidemiological data. We have performed a large-scale Southern blot hybridization, asymmetrical PCR-based, and repeat expansion-detection screening for (CAG)n/(CTG)n and (CCG)n/(CGG)n expansions in eastern Canadian schizophrenia multiplex families demonstrating genetic anticipation. There were no differences in (CAG)n/(CTG)n and (CCG)n/(CGG)n pattern distribution either between affected and unaffected individuals or across generations. Our findings do not support the hypothesis that large (CAG)n/(CTG)n or (CCG)n/(CGG)n expansions are the major etiologic factor in schizophrenia. A separate set of experiments directed to the analysis of small (30-130 trinucleotides), Huntington disease-type expansions in individual genes is required in order to fully exclude the presence of (CAG)n/(CTG)n- or (CCG)n/(CGG)n-type unstable mutation.     

Evidence for anticipation in schizophrenia.

Anticipation, or increasing severity of a disorder across successive generations, is a genetic phenomenon with an identified molecular mechanism: expansion of unstable trinucleotide repeat sequences. This study examined anticipation in familial schizophrenia. Three generations of siblines from the affected side of families selected for unilineal, autosomal dominant-like inheritance of schizophrenia were studied (n = 186). Across generations more subjects were hospitalized with psychotic illness (P < .001), at progressively earlier ages (P < .0001), and with increasing severity of illness (P < .0003). The results indicate that anticipation is present in familial schizophrenia. These findings support both an active search for unstable trinucleotide repeat sequences in schizophrenia and reconsideration of the genetic model used for linkage studies in this disorder.