[The role of vitamin A in the functioning of Golgi apparatus]. / Uchastie vitamina A v funktsionirovanii kompleksa Gol'dzhi.

Vitamin A participation in the Golgi complex functioning has been studied using the mucosa intermediate area of the chicken glandular stomach as a model. It is shown that in case of A-avitaminosis the electrophoretic profile of soluble proteins of mucosa and [I-14C]acetate and Na2(35)SO4 incorporation into it do not change, while in a secretion all these parameters are highly changed. Four glycoproteins are isolated from the mucous secretion, they differ in solubility in 6% perchloric acid and in staining by kumassi and alcine blue. These data and those obtained before underlie the conclusion that the effect of vitamin A on the secretion formation is realized on the level of the Golgi complex function.

[The role of vitamin A in the formation of extracellular structures of the chicken glandular stomach]. / Rol' vitamina A v obrazovanii vnekletochnykh struktur zhelezistogo zheludka tsypliat.

Main notions on the vitamin A function in the organism are considered. A new concept is formulated postulating the vitamin A role in the support of the structure and function of the Golgi complex of epithelial cells of glandular stomach mucosa of chickens.

[Cellular retinol-binding protein from the mucous intermediate zone of the glandular stomach of chickens]. / Kletochnyi retinolsviazyvaiushchii belok iz slizistoi promezhutochnoi zony zhelesistogo zheludka kur.

A protein which specifically binds [3H]retinol in vitro and has a sedimentation coefficient of 2S was isolated from the soluble fraction of chicken glandular stomach intermediate zone mucosa cells and purified to homogeneity. The purification procedure included gel filtration through Sephadex G-75 and G-50 and ion-exchange chromatography on DEAE-cellulose. The properties of the protein were compared to those of the retinol-binding protein from rat liver.

[Biological function of vitamin A]. / Biologicheskaia funktsiia vitamina A.

The paper deals with the generalized results of complex studies in the biological function of vitamin A conducted on the chicken glandular stomach. It is found out that at a certain diet the glandular stomach of chickens manifests a specific response to vitamin A deficiency: the amount of cells in the organ increases, their differentiation changes, the tissues relation is disturbed, hyperfunction is observed. The content of acid glycosaminglycanes varies, their biosynthesis is inhibited, the concentration of cations in the intercellular space increases. On the basis of these facts a conclusion is drawn that disturbances in the structure and function of glycocalyx are decisive in development of A-avitaminosis. It is established that the stomach intermediate zone mucosa secretion contains vitamin A which is strongly bound with a specific water-insoluble glycolipoprotein. The absence of vitamin A causes a disturbance in lipidation, glycosylation sulphatation and hydration of the secretion. A hypothesis is put forward according to which, vitamin A, joining the specific protein synthetized on ribosomes, initiates organization of the lipid phase. The latter might determine the direction and rate of protein transport in the system of smooth membranes where it is glycosidated. Formation of the lipid phase is disturbed when vitamin A is absent. This leads to changes in the protein migration pathways in the Golgi apparatus, which results in glycosidation disturbance as well. According to the same principle vitamin A may articipate in formation of glycolipoproteins not only of secretion but also of the intercellular substance, plasmatic membranes nuclei, lysosomes and other organelles.

[Biological activity of retinoic acid and methylretinoate]. / O biologicheskoi aktivnosti retinoevoi kisloty i metilretinoata.

Vitamin A lack in the diet of chicken produces a significant increase in the glandular stomach as well as formation of erosions and ulcers on the surface of the mucous membrane of the intermediate zone. Replacement of retinyl acetate in the diet by retinoic acid or methyl retionate gives no rise to changes in the morphological integrity of the glandular stomach of the chickens. Moreover, these compounds produce a reverse development of vitamin A-induced changes. It is thus concluded that when the diet lacks vitamin A, both retinoic acid and methyl retionate are capable of maintaining the structural integrity of the stomach.

[Changes in lipid composition of mucosa secretion from chick glandular stomach intermediate zone in A-vitaminosis]. / Izmenenie lipidnogo sostava sekreta slizistoi promezhutochnoi zony Zhlezistogo zheludka tsypliat pri a-Avitaminoze.

The lipid composition of secretion and the vitamin A content in it were studied. Secretion of normal chickens is shown to contain 96 +/- 3.1 mg of lipids, 82.5 +/- 3.4 of substances extracted by the solvent hexane-diethyl ester, 30 +/- 2.1 of unsaponifiable lipids and 2.43 +/- 0.285 micrograms of vitamin A per 1 g of dry residue. With A-avitaminosis the secretion amount is twice as large with vitamin A absent; the lipid content is almost twice as low, the total weight of substances extracted by the solvent hexane-diethyl ester is four times as low and that of the lipid unsaponifiable fraction--2.5 times as low. Quantitative and qualitative changes in lipid zones were detected by means of thin-layer chromatography and UV-spectroscopy, and structural changes in the secretion--by electron microscopy. Vitamin A is suggested to participate in formation of macromolecular lipid systems of the secretion.

[Changes in chemical composition, biosynthesis and structure of secretion of intermediate area of chicken stomach with A-avitaminosis]. / Izmenenie khimicheskogo sostava, binsinteza i struktury sekreta promezhutochnoi zony zheludka tsypliat pri A-avitaminoze.

In the intermediate area of the chicken stomach with A-avitaminosis the amount of the secretion increases and its chemical composition changes sharply: the content of water, lipids, hexolamines and suphates lowers. By means of 14-C-acetate, 35S-methionine and 35S-sulphate it is established that renewal of the secretion is inhibited. The electron-microscopic examinations showed that the secret is homogenous in normalcy but with A-avitaminosis it acquires a honeycomb structure, its physicochemical properties being changed: it becomes rigid, cuticle-like. As a result there appear deep cracks reaching mucosa, which lead to formation of erosions and ulcers. An assumption is advanced that the initial disturbances of the secretion might be not related to protein component (as the ratio of amino acids in it's almost unchanged) and depend on the carbohydrate and lipid components. The hypothesis of de Luc et al. as to the transport and intermediatory function of vitamin A in biosynthesis of glycosamineglycanes, glycolipids and glycolipoproteins is questioned. Vitamin A may take part in these processes but not as an intermediator of metabolic systems but as the level of biological structures (for instance, the Golgi apparatus and others) which organize these systems and coordinate their function.

[Vitamin A, membranes and the differentiation of cells]. / Vitamin A, membrany i differentsiatsiia kletok

The paper deals with analysis of biochemical, morphological and physiological changes in vitamin A-deficiency. On the basis of this analysis a conclusion is drawn that vitamin A is first of all the factor of differentiation. The intercellular zone is considered to be the most probable sphere of its primary effect. Deficiency in vitamin A causes a change in a concentration and ratio of cations and glycosaminglycans in this zone, that results in disturbance of the intercellular interactions. Other changes--in the DNA-RNA system, protein biosynthesis, sulphate, energy and other metabolisms--might be secondary. By the character of action vitamin A may be closed to hormones than to water-soluble vitamins.