Phytic acid. A natural antioxidant

The catalysis by iron of radical formation and subsequent oxidative damage has been well documented. Although many iron-chelating agents potentiate reactive oxygen formation and lipid peroxidation, phytic acid (abundant in edible legumes, cereals, and seeds) forms an iron chelate which greatly accelerates Fe2+-mediated oxygen reduction yet blocks iron-driven hydroxyl radical generation and suppresses lipid peroxidation. Furthermore, high concentrations of phytic acid prevent browning and putrefaction of various fruits and vegetables by inhibiting polyphenol oxidase. These observations indicate an important antioxidant function for phytate in seeds during dormancy and suggest that phytate may be a substitute for presently employed preservatives, many of which pose potential health hazards.     

Genetic Mapping in Xenopus Laevis: Eight Linkage Groups Established

Inheritance of alleles at 29 electrophoretically detected protein loci and one pigment locus (albinism) was analyzed in Xenopus laevis by backcrossing multiply heterozygous individuals generated by intersubspecies hybridization. Pairwise linkage tests revealed eight classical linkage groups. These groups have been provisionally numbered from 1 to 8 in an arbitrarily chosen order. Linkage group 1 includes ALB-2 (albumin), ADH-1 (alcohol dehydrogenase), NP (nucleoside phosphorylase), and ap (periodic albinism). Linkage group 2 contains ALB-1 and ADH-2, and probably is homeologous to group 1. Linkage group 3 comprises PEP-B (peptidase B), MPI-1 (mannosephosphate isomerase), SORD (sorbitol dehydrogenase), and mIDH-2 (mitochondrial isocitrate dehydrogenase). Linkage group 4 contains GPI-1 (glucosephosphate isomerase) and EST-4 (esterase 4). Linkage group 5 contains GPI-2 and PEP-D (peptidase D). Linkage group 6 comprises ACP-3 (acid phosphatase), sME (cytosolic malic enzyme), and GLO-2 (glyoxalase). Linkage group 7 consists of sSOD-1 (cytosolic superoxide dismutase), GPD-2 (glycerol-3-phosphate dehydrogenase), mME (mitochondrial malic enzyme), and the sex determining locus. Linkage group 8 includes FH (fumarate hydratase) and TRF (transferrin). Recombination frequencies between linked loci showed differences related to the genomic constitution (parental subspecies) and to the sex of the heterozygous parent. Independent assortment was observed between the duplicate ALB loci. This is true for the duplicate ADH, GLO, and MPI loci as well, supporting the view that these genes have been duplicated as part of a genome duplication that occurred in the evolutionary history of X. laevis. Comparative analysis of genetic maps reveals a possible conservation of several linkages from the Xenopus genome to the human genome.     

Transfer and co-amplification of a gene encoding a 96-kDa immune IFN-inducible human melanoma-associated antigen. Preferential expression by mouse melanoma host cells

An immune IFN-inducible human melanoma-associated glycoprotein Ag, 96-kDa MAA, having preferential distribution on metastases has been defined by mouse mAb CL203.4. To initiate molecular genetic analysis of 96-kDa MAA, the gene encoding the Ag was transfected into mouse B16 melanoma cell clone B78H1. Formation of B78H1-transfectant colonies expressing a surface Ag reactive with mAb CL203.4 in an immunorosetting assay was dependent on addition of chromosomal DNA from human melanoma cells [primary (1 degree) transfer] or from Ag-expressing transfectant cells (2 degrees, 3 degrees, 4 degrees transfer). The mAb CL203.4-reactive species expressed by the transfectant cells is a glycoprotein with a molecular mass 93-kDa, within the range of 93 to 96-kDa observed for the endogenous human Ag. In the presence of tunicamycin, an inhibitor of N-linked glycosylation, both mouse melanoma transfectants and human melanoma cells express a 50- to 51-kDa antigenic species. Human alu family repeat sequences (h-alu) are present in the genomes of 3 degrees transfectant cells. Continued presence of these h-alu after dilution of extraneous human DNA by three cycles of transfection suggests their association with the transferred 96-kDa MAA gene. Use of a selective co-amplification procedure led to transfectant cells' increased expression of 96-kDa MAA and to commensurate increases in their content of presumed 96-kDa MAA gene-associated h-alu. Preferential DNA-mediated transferability of the 96-kDa MAA+ phenotype into B78H1 cells as compared with LMTK- mouse fibroblasts suggests host cell specificity of 96-kDa MAA gene expression.     

Comparison of 16S rRNA sequences from the family Pasteurellaceae: phylogenetic relatedness by cluster analysis

The taxonomy of the family Pasteurellaceae has remained controversial despite investigations of biochemistry, serology, and nucleic acid relatedness. In an attempt to resolve some of this confusion, we have partially sequenced the 16S rRNAs of seven members of the family, representing all three genera. The sequences were aligned, similarity scores calculated, and single, average and complete linkage cluster analysis of the resulting distance matrix performed. In this way, an evolutionary branching pattern of these closely related species was reconstructed, and the approximate phylogenetic position of the family determined. Actinobacillus (Haemophilus) actinomycetemcomitans clustered with Haemophilus instead of Actinobacillus, supporting transfer of this species to the genus Haemophilus. Thus cluster analysis of phylogenetic relatedness was found to be particularly useful for studying closely related organisms, and could be performed using a microcomputer.     

The periosteum in experimental avian hyperostosis induced by MAV 2-0 myeloblastosis virus. Differential diagnosis from osteopetrosis

Diaphyseal tibial bones of 11-14-17 th day-old hatched chicks infected with retrovirus myeloblastic MAV 2-0 were examined by conventional optical microscopy. The characteristic lesion is osteoblastic hyperplasia with the development of spongious bone. The new formed bone contains abnormal chondroid tissue. The relation between osseous and cartilaginous tissues in this experimental model is discussed. As connective tissue took part in the constitution of this hyperostosis, this osteopathy may be considered as an hyperplastic, monodermic mesenchymatous, pluritissular tumour. The numerous works concerning the "avian hyperostosis osteopetrosis" are commented.     

Protease cytochemistry in the murine rodent,guinea-pig and marmoset placenta

Summary Plasma membrane and lysosomal proteases, -glutamyl transferase and extracellular matrix proteases were investigated by qualitative cytochemical means in the mature placenta of mice, rats, guinea-pigs and marmosets. These studies revealed similarities, which concerned, primarily the lysosomal proteases in different structures of the placenta and all proteases and -glutamyl transferases in the zone of placental shedding. However, species differences predominated. They were observed especially for aminopeptidase A and M, dipeptidyl peptidase IV and -glutamyl transferase in the plasma membranes and extracellular matrix of the placental barrier and decidual cells of all species and the cells of the basal zone in rats and mice. Plasma membrane and extracellular matrix proteases in other parts of the placenta, e.g. the placenta stem of guinea-pigs and basel plate, amniotic and chorionic plate of marmosets occurred only in these species. Elastase substrates hydrolysing endopeptidase I and kallikrein-, thrombin-, plasmin-, plasminogen- and cathepsin B substrates hydrolysing endopeptidase II were not observed in any of these species. A general comparison of the species revealed similarities for the mouse, rat and guinea-pig placental barrier, but not for that of marmosets. The proteases of this zone in the marmoset placenta are more similar to the human situation, but do not correspond to it completely.In honour of Prof. P. van DuijnSupported by the BMFT (Project CMT 35) and Sfb 174In part presented at a Symposion on Progress in General, Applied and Diagnostic Histochemistry (Modra, Czechoslovakia on 12–15 April, 1984; abstracts published in Histochem J 17, No 5, 1985)     

Über die Pseudopodien von Megakaryocyten und ihre Bedeutung für die Freisetzung von Thrombocyten

Zusammenfassung Im Knochenmark der Ratte werden große runde Megakaryocyten und Megakaryocyten mit zahlreichen Pseudopodien gefunden. Die prospektiven Plättchenfelder liegen in der Mitte der Pseudopodien und sind von der hyalinen Zone des Ektoplasmas umgeben. An der Spitze der Pseudopodien ist die hyaline Zone verbreitert. Die Pseudopodien ragen in Sinusoide und Kapillaren, werden aber auch extravasal gefunden. Gelegentlich läßt sich eine Kontinuität zwischen der Membran der Demarkationsbläschen und der Pseudopodienmembran beobachten. Eine intravasale Freisetzung von Thrombocyten aus Pseudopodien ist sehr wahrscheinlich.

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Pseudopodia of megakaryocytes and liberation of blood platelets

Summary In the bone marrow of rats large round megakaryocytes and megakaryocytes with numerous pseudopodia are to be found. The prospective fields of platelets are located in the central part of the pseudopodia. These fields are surrounded by the hyalin zone of ectoplasm. At the tip of a pseudopodium this zone is enlarged. Pseudopodia protrude into sinusoids and capillaries, but occur also extravasally. Continuity between the membrane of the vesicles for the demarcation of platelets and the cell membrane is occasionally observed. The intravasal liberation of thrombocytes from pseudopodia seems very likely.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Improved correlation between soil exchangeable K and plant K contents on a tissue water basis

In acid volcanic soils, plant roots are thought to be injured by acidity (low pH) and/or solubilized aluminium (Al) ions. An attempt was made to separate the effects of low pH from those of Al on the elongation and viability of alfalfa (Medicago sativa L.) radicles in water culture. Root elongation was irreversively curtailed by 20 hours treatment at pH 4.0 without Al or 20 mmol m^-3 Al at pH 5.0. Viability of surface cells of root tips was detected as a degrading activity of fluorescein diacetate (FDA) by cellular esterases and subsequent accumulation of derived fluorescein within cells. Large numbers of the surface cells lost their viability after four hours exposure at the low pH. In contrast, surface cells maintained both FDA degrading activity and ability to accumulate fluorescein 20 h after initial exposure to the Al solution (20 mmol Al m^-3, pH 5.0). These results suggest that there are some significant differences in the mechanisms of phytotoxicity to alfalfa root between the two stress factors.