A nuclear specific glycoprotein representative of a unique pattern of glycosylation

Whole rat liver nuclei were reacted with UDP-[14C]galactose in the presence of bovine beta(1----4) galactosyltransferase. The reaction mixture was electrophoresed on a reducing sodium dodecyl sulfate-polyacrylamide gel. Autoradiograms of the gel demonstrated a major labeled broad band migrating with an apparent molecular weight of 65,000-66,000. A number of other less prominently labeled bands were also present. The labeled 65,000-66,000 band when cut from the gel and subjected to alkaline reduction while in the gel matrix exclusively yielded a 14C-labeled disaccharide that co-migrated with a [14C]Gal-GlcNAcol standard in descending paper chromatography. Treatment of this disaccharide with beta-galactosidase (beta-D-galactoside galactohydrolase; EC 3.2.1.23) from Aspergillus niger removed all the [14C]galactose label. Treatment of the labeled 65,000-66,000 polypeptide with Endoglycosidase F, however, did not remove the [14C]galactose label. Western transfer blots of sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels performed with horseradish peroxidase-labeled succinyl wheat germ agglutinin, a lectin specific for GlcNAc, on unlabeled nuclei revealed a dominant band at 63,000-64,000. Subjecting 14C-labeled nuclei to this procedure resulted in a shift of the major horseradish peroxidase-labeled succinyl wheat germ agglutinin band to 65,000-66,000. The shifted band was coincident with the [14C]galactose band as visualized on an autoradiogram. A survey of other rat tissue nuclei revealed the same spectrum of [14C]galactose acceptor proteins with a dominant 65,000-66,000 galactose-labeled band.     

Inactivation of rat pineal hydroxyindole-O-methyltransferase by disulfide-containing compounds

Rat pineal hydroxyindole-O-methyltransferase activity in crude homogenates is reduced by treatment with disulfides. Cystamine (IC50 = 128 microM) and selenocystamine (IC50 = 13 microM) are the most potent compounds tested. Reduced cystamine (cysteamine) and diaminohexane are inactive. N,N'-Diacetylcystamine, penicillamine disulfide, and glutathione disulfide are less potent or inactive; but several peptides (oxytocin, vasopressin, and arginine vasotocin) are active. Inactivation by cystamine is time- and temperature-dependent and is accelerated at higher pH. Disulfide treatment of intact pinealocytes also inactivates the enzyme. Addition of dithiothreitol during the enzyme assay completely reactivates inactivated enzyme formed by disulfide treatment of homogenates or intact cells. Rat hydroxyindole-O-methyltransferase is also inactivated in the absence of added disulfides and dissolved O2. This spontaneous inactivation is time-, temperature-, and pH-dependent and can be completely prevented, but not reversed, by dithiothreitol. In contrast to the inhibitory effects of cystamine on the rat enzyme, cystamine does not alter bovine hydroxyindole-O-methyltransferase and increases ovine hydroxyindole-O-methyltransferase activity. The bovine and ovine enzymes do not become inactive in the absence of added disulfides. Together these observations indicate that rat pineal hydroxyindole-O-methyltransferase can be inactivated by a protein thiol:disulfide exchange mechanism. This mechanism may contribute to the physiological regulation of this enzyme in the rat pineal gland but does not appear to be a common feature of pineal hydroxyindole-O-methyltransferase regulation in all species.     

Increased near-ultraviolet induced DNA fragmentation in xeroderma pigmentosum variants.

Immediate fragmentation of parental DNA by near-ultraviolet irradiation at 313 nm was measured in cultured skin fibroblasts from normal individuals, patients with Xeroderma pigmentosum of complementation group A (XPA) and Xeroderma pigmentosum variants (XPV) by the alkaline elution procedure. For a dose of 2.25 KJm^?2 given at O^o fragmentation was comparable in all cell strains. However, fragmentation was strongly increased relative to O^o in XPV but not in normal fibroblasts and the XPA strains when irradiation was carried out at 37^o. From our results it appears that a step in the repair of $\text{parental}$ DNA is abnormal in XPV.     

Antibacterial activity of Turkish propolis and its qualitative and quantitative chemical composition

The antibacterial activity of propolis from different regions of Turkey was studied, accompanied by TLC and GC-MS analyses of its chemical composition and spectrophotometric quantification of the most important active principles. All six samples were active against the bacterial test strains used; however, samples 1 (Yozgat), 2 (Izmir) and 3 (Kayseri) were more active than samples 4 (Adana), 5 (Erzurum) and 6 (Artvin). By TLC comparison all samples were found to contain poplar taxonomic markers but in samples 4 (Adana), 5 (Erzurum) and 6 (Artvin), different substances were observed, which were not present in P. nigra L. bud exudate. The typical poplar samples 1 (Yozgat), 2 (Izmir) and 3 (Kayseri) displayed very similar phenolic and flavonoid content. Samples 4 (Adana), 5 (Erzurum) and 6 (Artvin) were characterized by low phenolic and very low flavonoid concentrations. Qualitative analysis by GC-MS revealed that sample 4 (Adana) contained diterpenic acids and high percent of cinnamyl cinnamate, sample 5 (Erzurum)-significant amounts of hydroxy fatty acids and triterpenic alcohoLs, and sample 6 (Artvin)-phenolic glycerides, characteristic for the bud exudate of Populus euphratica Oliv. The results confirm the importance of phenolics for propolis antibacterial activity, and the significance of P. nigra L. as a propolis source, which provides the hive with the best defense against microorganisms.     

Relationship between postabsorptive respiratory exchange ratio and plasma free fatty acid concentrations

The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m⁻²). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ² test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation.     

The ossification centers in the lower end of tibiotarsus in domestic fowl.

The morphogenesis of lower end of tibia in chick is studied commonly but the process of ossification of the same has received very little attention so far. The present study is directed to throw some light on the appearance of ossification centers in the lower end of tibiotarsus of chick. The histology of lower end of tibiotarsus was studied by procuring developing tibiotarsi from chick embryos (20) of 6th day incubation till hatching and 3 post hatched chicks. The transparancies of chick embryos at different incubation periods and post hatched chicks were prepared by Dawson's Alizarin staining method. Three cartilage center (tibial, fibulare and intermedium) appeared in 6...9 days of incubation period in the tarsal region. These gradually fused with the lower end of tibia. Three ossification centres developed in the lower end of tibiotarsus. One for intermedium appeared on 16th day and two fotibial and fibulare on 20th day. All these three centres could be located in the transparancies of the chick embryos in tarsal region. The present study proves that the three cartilages centres maintain their individuality during the ossification process even though those fuse completely with the lower end of tibia in chick. The centers for tibial and fibulare are similar to epiphyseal centres of mammals in histological details.