Mixed-ligand complexes of technetium XIII. A new and facile synthesis, structure and electrochemical behaviour of trans-[Tc(dppe)2(buNC)2](PF6)· ethanol (dppe = bis(diphenylphosphino)ethane, buNC= tert-butylisocyanide)

The Tc(I) mixed-ligand complex, trans-[Tc(dppe)₂(bu^tNC)₂](PF₆) (dppe=bis(diphenylphosphino)ethane, bu^tNC=tert-butyl-isocyanide) has been prepared from [Tc(tu−S)₆³⁺ (tu-S=thiourea) and a mixture of both ligands. The compound crystallizes triclinic in the space group

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). The technetium atom has a slightly distorted octahedral coordination sphere with the isocyanide ligands in trans-position to each other. By cyclic voltammetry, at a Pt electrode, trans-[Tc(dppe)₂(bu^tNC)₂](PF₆) undergoes a single electron reversible oxidation at E_1/2^ox=0.91 V versus SCE.     

Analysis of active nucleolus organizing regions in Capsicum (Solanaceae) by silver staining

Nucleolar activity of 22 samples belonging to nine diploid species of Capsicum was analyzed in somatic metaphases and interphase nuclei. They are: C, chacoënse, C. parvifolium, C. frutescens, C. chinense, C. annuum var. annuum, C. baccatum var. pendulum, C. pubescens, all with 2n = 24, and C. mirabile var. mirabile and C. campylopodium with 2n = 26. Silver staining was applied for the first time in Capsicum, providing useful markers for chromosome identification in combination with other banding techniques already employed in the genus. From two to eight AgNORs (silver-stained nucleolus organizing regions) were found in the diploid complement of the taxa studied. Nucleolar organizers are located at secondary constrictions of chromosomes which are conventionally stained or banded (C-banding or fluorochrome banding). Polymorphism of AgNORs and attached satellites often occurs. Nucleoli are usually fused to a variable extent. Number and position of active rDNA loci are variable not only between but also within species and populations. Homologies in position of NORs between species were established. The data obtained are related to previous conclusions on phylogenetic relationships in Capsicum. Possible trends of karyotype evolution concerning nucleolar organizers are discussed, and four NORs in the diploid complement (on chromosome pairs #1 [m] and #12 [st]) are regarded as the plesiomorphic condition.     

Glycosyl transferases in mouse and human milk fat globule membranes

Summary Membranes isolated from mouse and human milk fat globules were found to contain the enzymes responsible for the synthesis of dolichol monophosphate mannose and dolichol monophosphate glucose as well as those involved in the transference of the glycosyl residues from the two dolichol derivatives to dolichol diphosphate oligosaccharides. The levels of most of the enzymes were comparable to those found in mouse mammary gland microsomes. The presence of enzymes involved in protein glycosylation via dolichol derivatives in the milk fat globule membrane provides evidence in favor of an outward flow of membrane components from the rough endoplasmic reticulum, where these enzymes are active in vivo, towards the cell surface.     

Oncofetal antigen-I (OFA-I) relative antigenicity on melanoma cells

Summary The oncofetal antigen-I (OFA-I) has been defined as an immunogenic antigen that is expressed on human cancer cells and is cross reactive with fetal brain tissue. Quantitative variations in the expression of OFA-I among different cultured melanoma cell lines were determined by absorption techniques based on functionally monospecific anti-OFA-I serum. Allo-antibodies were removed by absorption with lymphoblasts autologous to an OFA-I-positive target cell. Functional monospecificity toward OFA-I was confirmed by complete absorption with a specimen of fetal brain but not by liver from the same fetus.Of 14 melanoma cell lines tested, two did not express OFA-I, whereas 12 expressed the antigen to varying degrees. Five of the cell lines were highly antigenic, and serum absorbed with 5×10⁵ of any of these cell lines could reduce the anti-OFA-I titer (1 : 96) at least four-fold. OFA-I was detected on biopsied melanomas autologous to the antigenic cultured cells. The ability to select highly antigenic cell lines could be useful in further attempts to characterize OFA-I and to monitor tumor immunity in vitro. Antigenic cell lines may improve the response of patients treated in trials of immunotherapy.     

Synthesis of dolichol derivatives in human erythrocyte membranes

Summary Human erythrocyte membranes contain the enzymes responsible for the synthesis of dolichol-P-glucose, dolichol-P-mannose, dolichol-PP-N-acetylglucosamine, dolichol-PP-NN diacetylchitobiose and of dolichol-PP-oligosaccharides containing NN diacetylchitobiose and mannose or the same sugar residues plus glucose. The transfer of the oligosaccharide moieties from the dolichol-PP-oligosaccharides to endogenous proteins could not be detected. These enzymes appeared to be integral membrane proteins.Abbreviation Dol dolichol Dedicated to ProfessorLuis f. Leloir on the occasion of his 70th birthday.     

Purification of goat serum retinol-binding protein and preparation of its antibodies

The method for the purification of goat serum retinol-binding protein consists of DEAE-cellulose chromatography of the serum followed by preparative polyacrylamide disc gel electrophoresis. After electrophoresis, the retinol-binding protein containing zone is identified by the specific fluorescence of retinol. For raising the antibodies, the portion of the gel containing retinol binding protein is homogenized and injected intradermally and intramuscularly to rabbits. The availability of this simple method for the isolation of retinol-binding protein and production of its antibodies enables the development of a radioimmunoassay for this protein.     

Species composition,similarity, and structure of mayan homegardens in tixpeual and tixcacaltuyub,yucatan, Mexico

We studied species composition, similarity, and structure of homegardens in two Yucatecan Maya communities, Tixpeual and Tixcacaltuyub, Yucatan, Mexico. The number of gardens sampled per village was 20 and 22; total area sampled was very similar, 45,265 m² and 40,150 m²; the number of trees and shrubs present was 5651 and 5603; and number of species was 135 and 133, respectively. Diversity was low for both sites (H′= 1.6), as were the correlation coefficients (r) for the species-area and individuals-area correlations. The relatively low values obtained for the structural parameters reflect the random pattern of plant incorporation to the gardens, the variability in the proportion of constantly used and not constantly used garden area, and a certain uniformity in the number of species used and number of individuals present, and the relationship between these parameters and garden size. All these reflect the uniqueness of each homegarden, which depends upon the cultural background of the owner. We noticed a trend towards a change in homegarden structure and function in response to the modernization process. Homegardens in villages in the outskirts of cities tend to have more ornamental species and commercial fruit plants than homegardens in isolated villages.