Possible role of rat fatty acid-binding proteins in the intestine as carriers of phenol and phthalate derivatives

Fatty acid-binding proteins of hepatic and intestinal type and gastrotropin-like protein (GTLP) were purified from rat intestinal cytosol by Sephadex G-75 gel filtration and DEAE-cellulose, CM-cellulose, and hydroxylapatite chromatographies. In addition to fatty acids, butylated hydroxytoluene (BHT), phthalate dibutyl, and di(2-ethylhexyl) esters (DBP and DEHP) were identified by gas liquid chromatography and mass spectrometry as endogenous ligands from the extract of either fatty acid-binding protein superfamily. These protein families in the intestine may have an important role as carriers in the initial step of arresting these exogenous pollutants.     

Identification of lactotropes (PRL cells), somatotropes (GH cells), corticotropes (ACTH cells) and thyrotropes (TSH cells) in the pituitary gland of the musk shrew, Suncus murinus L. (Insectivora), by immunohistochemistry

By means of immunohistochemistry, lactotropes, somatotropes, corticotropes and thyrotropes in the pituitary of the male musk shrew, Suncus murinus L., were identified at the electron-microscopic level. Lactotropes were classified into three types: type I containing large (200-450 nm in diameter) round secretory granules, type II with medium-sized (150-250 nm in diameter) ones and type III with small (50-150 nm in diameter) ones. Somatotropes were also classified into type I somatotropes that contain large (450 nm in diameter) spherical secretory granules and type II somatotropes containing comparatively small (300 nm in diameter) round granules. Both type I and II somatotropes were small and sometimes contained rod-shaped granules. Corticotropes were round or oval cells with round secretory granules in various densities and sizes (150-500 nm in diameter) scattered all over the cytoplasm. Thyrotropes were angular or polyhedral cells containing electron-transparent round secretory granules (200-300 nm in diameter) and large irregularly shaped granules with a maximum diameter of about 1,500 nm. Each type of the cells may be distinguished by its respective ultrastructural characteristics alone without the aid of immunohistochemistry.     

Effect of short — chain fatty acids on electrical activity of the small intestinal mucosa of rat

Intravenous administration of short-chain fatty acid (SCFA), such as propionate, butyrate, valerate and caproate, caused a transient increase in transmural potential difference (p.d.) across the small intestine of rat $\text{in vivo}$. There was a sigmoid relationship between the change in the p.d. and the logarithm of the dose of SCFA. The median effective dose of propionate, n-butyrate, n-valerate and n-caproate, which was calculated from the each dose-response curve obtained from the terminal ileum, 1.31, 1.43, 0.83 and 0.81 μmole, respectively. Repeated administrations of the same dose of propionate evoked progressively smaller response. The dose-response curve of propionate was shifted to the left by neostigmine and to the right by atropine, suggesting that the action of SCFA may be mediated by acetylcholine, which was released from a nerve ending.     

Cartilage-derived factor (CDF) : II. Somatomedin-like action on cultured chondrocytes

Previously, we showed that fetal bovine cartilage contains a polypeptide that stimulates the incorporation of [³⁵S]sulfate into proteoglycans synthesized by rat and rabbit costal chondrocytes in culture. In this paper, we report that the cartilage-derived factor (CDF) increases not only [³⁵S]sulfate incorporation but also [³H]thymidine incorporation into rabbit chondrocytes in monolayer culture. The dose-response curve of CDF stimulation of DNA synthesis was similar in profile to that of CDF stimulation of proteoglycan synthesis. In addition, CDF markedly enhanced [³H]uridine incorporation into rabbit chondrocytes and significantly enhanced [³H]serine incorporation into total protein. These findings indicate that fetal bovine cartilage contains a factor that shows somatomedin-like activity in monolayer cultures of rabbit chondrocytes.     

In vivo degradation of rat globin messenger RNA during maturation of reticulocytes.

The degradation of globin mRNA in rat reticulocytes maturing in the peripheral blood was investigated. Poly(A) and non poly(A) portions of mRNA molecules were determined quantitatively by hybridization with radioactive poly(U) and complementary DNA, respectively. During the degradation of mRNA in vivo, it was shown that (1) globin mRNA and the bulk of RNA decrease in parallel, (2) the average chain length of poly(A) segments in the mRNA does not change, (3) the percentage of poly(A) (-) globin mRNA in total globin mRNA does not change, and (4) fragments of large molecular weight do not accumulate. Possible mechanisms of degradation of globin mRNA in the reticulocytes are discussed on the basis of these observations.     

Three dimensional organization of mammalian adrenal cortex

Summary The adrenal cortex of different mammals was studied by SEM in order to demonstrate its actual three-dimensional organization. In the rat, as well as in the cat and pig, the adrenal cortex appeared as a tunnelled continuum of polyhedral cells arranged in plate-like structures (laminae). This laminar arrangement was more evident in the inner fasciculate and reticular zones where the cortex revealed a striking similarity to liver tissue. The polyhedral cells of all cortical zones possessed regular facets populated by small pits, larger invaginations and numerous microvilli with the exception of very short and smooth areas probably corresponding to attachment zones and/or gap junctions. This cellular architecture produced a labyrinthic system of intercellular channels or lacunae in which the capillaries were suspended.The pericapillary areas of this labyrinth contained microvilli, amorphous material, a delicate net of fibrils and occasional cells. The intercellular compartment of this lacunar system was mainly bordered by numerous microvilli arising from endocrine cells.The luminal surface of the capillary wall showed not only irregularly protruding margins (interpretable as endothelial junctions) but also clearly overlapping and flattened endothelial extensions.In all the animals and areas of the adrenal cortex examined, the endothelial wall was provided with abundant clusters of small fenestrations (about 50 nm in diameter) generally arranged in sieve plates. Larger fenestrations were noted mainly in the fasciculate and reticular zones of the cat and pig and occasionally in the rat.A final point related to the nature and significance of sinusoidal fenestrations was the occurrence of irregularly shaped and intracapillary located cells mainly noted in the deeper zones of the fasciculate and reticular zones of the gland. These elements — possessing the surface characteristics of macrophages — were observed, with their irregular and slender evaginations, in close proximity to the large fenestrations in a manner reminiscent of Kupffer cells within the lumen of liver sinusoids.     

13C Nuclear magnetic resonance study of salt induced conformational change of basic polypeptides: Poly (L-lysine), poly (L-arginine), and poly (L-ornithine)

A ¹³C-nmr study of the salt-induced helix–coil transition of the basic polypeptides poly(L -lysine) [(Lys)_n], poly(L -arginine) [(Arg)_n], and poly (L -ornithine) [(Orn)_n] was performed to serve as a reference of the helical portion of histones and other proteins. As is the case with pH-induced helix–coil transition, the downfield displacement of the C^α and carbonyl carbon signals are observed in the helical state. The upfield shift of the C^β signals, on the other hand, is noted in the salt-induced transition. Regardless of the differences in the side chains and also the salts used, very similar helix-induced chemical shifts are obtained for (Lys)_n and (Arg)_n. However, the displacement of the C^α, C^β, and carbonyl carbons of (Orn)n in the presence of 4M NaClO₄ is found to be almost 50% of that of (Lys)_n and (Arg)_n. This is explained by the fact that the maximum helical content is about 50%, consistent with the ORD result. Further, the motion of the backbone and side chains of the helical from was estimated by measuring the spin-lattice relaxation time (T₁), nuclear Overhauser enhancement (NOE), and line width. In the case of (Lys)_n, the motion of the side chains is charged very little in comparison with that of the random coil. Indicating that the aggregation of the salt-induced helix is small in contrast to that of the pH-induced helix. For (Arg)_n, however, the precipitate of the helical polymers is mainly due to aggregation.     

Plant growth-regulating activities of batatasin III analogues

Nine bibenzyls and 10 stilbenes were synthesized as analoguesof batatasin III, a growth inhibitor isolated from dormant yambulbils, and examined for their plant growth-regulating activities.The bioassays used were the elongation of dark-grown intactrice coleoptiles, auxin-induced elongation of excised oat coleoptiles,and germination of rape and barnyard grass seeds. In the elongationof intact rice coleoptiles, 3,3'-dihydroxy-5-methoxy- (batatasinIII), 3,5-dimethoxy-3'-nitro-, 4'-bromo-3-nitro-, 3-amino-3'-chloro-,3-amino-4'-chloro-bibenzyls and 3-benzyloxy-4'-bromo-5-methoxy-,3-benzyloxy-3',4'-dichloro-5-methoxy-stilbenes were inhibitory,and 4'-bromo-3-nitrostilbene was promotive at a concentrationof 100 mg/liter. The results obtained by the other bioassayswere qualitatively consistent with these findings, although3-amino-4'- chlorobibenzyl and 4'-bromo-3-nitrostilbene werenot tested in all the bioassays. In the seed germination, which was rather tolerant to the testanalogues, batatasin III was inactive but 3-benzyloxy-4'-bromo-5-methoxy-and 3-benzyloxy-3',4'-dichloro- 5-methoxystilbenes were veryactive. Thus, if substituted properly, bibenzyls and stilbenes are activewithout hydroxyl and methoxyl group(s) as the functional group. ³ Present address: The National Institute for EnvironmentalStudies, Yatabc, Ibaraki 300-21, Japan. (Received November 19, 1975; )