The effect of long-term selenium and vitamin E-enriched diet on the content of lipid peroxides and cholesterol in rats

The effect of long-term diets enriched with natural antioxidants was studied on Wistar rats with average initial body weight 150 g. After enrichment of the diet with selenium (0.1 ppm of sodium selenite per 100 g of diet), with vitamin E (6 mg of alpha-tocopherol per 100 g of diet) and selenium and vitamin E together the following results were obtained: diets enriched with selenium or vitamin E given for 12 months reduced the production of lipid peroxides in the liver and serum of the rats. On the other hand, addition of both antioxidants to the diet had no effect on lipid peroxide levels in the animals. Diet enrichment for 12 and 18 months with selenium or vitamin E had no effect on the levels of total cholesterol and HDL cholesterol. The obtained results suggest that selenium and alpha-tocopherol exert an inhibitory action on the processes of ageing in the experimental animal model.     

Diastereomers of thymidine 3'-O-(methanephosphonothioate): synthesis, absolute configuration and reaction with 3'-methoxyacetylthymidine under conditions of triester approach to oligonucleotide synthesis

Diastereomers of the title compound were obtained and absolute configuration was assigned by means of stereochemical correlation. Their reaction with 3'-O-methoxyacetylthymidine in the presence of triisopropylbenzenesulphonyl (4-nitro) triazole is neither chemo- nor stereo-selective and leads to diastereomeric pairs of dithymidyl (3',5')methanephosphonate and -methanephosphonothioate. Obtained results are discussed in terms of mechanism of activation of phosphodiesters under conditions known as "phosphotriester approach to oligonucleotide synthesis".     

A new species of the genusLotus (Fabaceae) in North Africa

A new species,Lotus digii, has been found in Morocco growing on the coastal sandy soils. Further localities are from Algeria and Egypt. It should be expected also in Libya.     

Comparison of two methods for detection of Mollicutes (Mycoplasmatales and Acholeplasmatales) in cell cultures in The Netherlands

A total of 1949 cell cultures was tested for contamination with mollicutes by cultivation on and in mycoplasma media, 25.7% of the cell cultures was positive, 243 strains of Mycoplasma hyorhinis were isolated. Furthermore, mainly M. arginini and M. orale were detected, less often Acholeplasma laidlawii, M. fermentans and M. pneumoniae. Optimal conditions for isolation were discussed. About one third of 217 hybridoma cultures and two third of 57 myeloma cultures proved to be contaminated, all with M. hyorhinis. A DNA fluorochrome staining method (DAPI-test) was compared to cultivation for testing 1039 cell cultures. The efficiency of the DAPI-test could be estimated to be about 96% that of cultivation about 89%, but cultivation is more specific. The highest assurance is obtained when both methods are applied.     

Non-Decarboxylating transformation of indol-3-ylacetic acid in apple seeds

An enzyme extract from apple(Pyrus malus Borb.) seeds which causes the disappearance of free indol-3-ylacetic acid (IAA) requires the presence of oxygen, but is not inhibited by cyanide. Using 1-¹⁴C-IAA it has been demonstrated that the IAA transformation is not accompanied by its decarboxylation. Decarboxylating IAA oxidase is absent during the whole period of apple seed cold stratification. Free IAA has not been detected in dormant apple seeds and in seeds stratified at low temperature. It appears during stratification at 25 °C. Ethyl ester of IAA and indol-3-ylacetyl aspartate have been identified in dormant and after-ripened seeds. Exogenous 1-¹⁴C IAA taken up by apple embryos is converted into conjugates with aspartate and short peptides containing an aspartate moiety.     

Arterial supply of the choriocapillaris of anuran amphibians (Rana temporaria,Rana esculenta)

Summary The pattern of the vascular supply to the choroid of the frog eye was studied in toto with the use of the injection-replication-SEM technique. The choroid of anuran amphibians is composed mainly of the choriocapillaris. In both species studied (Rana temporaria, Rana esculenta), an independent arterial supply to the choriocapillaris supplemented that from the ciliary arteries. This additional vascular route arises from the optic artery, a separate branch of the arteria infundibularis superficialis. The optic artery, accompanied by its vein within the vascular sheath of the optic nerve, joins the rich arterial capillary network of the choriocapillaris and supplies the posterior pole of the ocular bulb. The superficial capillary network displays a dense collar around the entrance of the optic nerve into the eye and is composed of a circular meshwork of small capillaries, several layers deep. More peripherally, however, it becomes single layered. This capillary network, as a whole, establishes numerous connections with the adjacent choriocapillaris at the posterior pole of the ocular bulb. In anuran amphibians the complex arrangement of both arterial systems supporting the choriocapillaris may be regarded as a more complete equivalent of the short posterior ciliary arteries of mammals.     

The superficial vascular hyaloid system in the eye of the frogs,Rana temporaria and Rana esculenta

Summary The angioarchitecture of the superficial vascular hyaloid system (membrana vasculosa retinae) of the frog eye was studied by means of scanning electron microscopy of vascular corrosion casts. The terminal vessels form a single-layered sheath intimately adjacent to the vitreal side of the avascular retina. The hyaloid system is subdivided by the ventral venous trunk into three central areas: the dorsal, the temporo-ventral, and the naso-ventral area. Toward the ora serrata, the hyaloid system is bordered by an arterial ring, and by nasal and temporal venous branches forming more or less complete hemicircles. A vascular zone composed of several tongue-like sectors establishes an inter-connection between the peripheral vascular rings and the central areas of the fundus. The arterial blood is supplied from the arterial ring. The drainage of the hyaloid system is provided via two routes: (1) the Y-shaped ventral trunk collects blood from the central areas, (2) the two peripheral venous branches drain the tongue-like sectors. The vessels within the dorsal area follow preferentially a dorso-ventral meridional direction. This densely capillarized territory corresponds in localization to the area centralis retinae. The ultrastructure of microvessels of the hyaloid system is characterized by features typical for capillaries of the central nervous system.