A New Malaria Parasite Plasmodium (Sauramoeba) heischi in Skinks (Mabuya striata) from Nairobi, with a Brief Discussion of the Distribution of Malaria Parasites in the Family Scincidae

ABSTRACT. A new species of malaria parasite, Plasmodium (Sauramoeba) heischi , is described from African skinks (Mabuya striata). Eleven individuals of 90 specimens collected in Nairobi were found to be infected. The new parasite is a large species, characterized by spindle-shaped gametocytes, the female often with a subterminal nucleus. The schizonts produce up to 65 nuclei and cause great hypertrophy and distortion of the host cell. Although similar to P. (Sauramoeba) giganteum in dimensions and merozoite numbers, P. heischi is easily distinguished by gametocyte and schizont shapes.     

Cell-free translation of human uroporphyrinogen decarboxylase mRNAs

Uroporphyrinogen decarboxylase was synthesized in a reticulocyte lysate cell-free system under the direction of messenger RNAs isolated from human fetal liver and from human reticulocytes. The enzyme was specifically isolated by immuno affinity chromatography. Analysis of the translation products showed that uroporphyrinogen decarboxylase was synthesized in vitro with its mature molecular weight. This enzyme represented 0.04% of the total neosynthesized proteins under the direction of fetal liver mRNA and about ten times less (0.005%) with reticulocyte mRNA.     

Coupling between redox and acid-base energy by cytochrome b-564 in Baker's yeast mitochondria

Baker's yeast mitochondrial cytochrome b-564 is characterized by exhibiting both a labile pH-independent high-potential form (E'o, pH 7 = + 190 mV) and a stable pH-dependent (pKa = 6.8) low-potential form (E'o, pH 7 = + 70 mV). The different behavior of these two forms of cytochrome b-564 versus pH seems to be a decisive factor for transduction of redox energy into acid-base energy in oxidative phosphorylation site 2. Deenergizing treatments, such as ADP plus Pi, result in the conversion of all the mitochondrial cytochrome b-564 into its low-potential form, whereas energization with ATP specifically transforms the cytochrome into its high-potential form, the ATP effect being neutralized by the ATPase inhibitor oligomycin and by the uncoupler FCCP. Accordingly, a minimal model for coupling between redox energy and acid-base energy through an electronically energized and protonated ferricytochrome b-564 intermediate is proposed. The energy-transducing properties of mitochondrial cytochrome b-564 seems to be shared by chloroplast cytochrome b-559.     

Mutant hemoglobin stability depends upon location and nature of single point mutation

The temperature dependence of the rates of heme release from the beta subunits of methemoglobin A and 5 beta mutant methemoglobins has been determined. The rates were largest for two hemoglobins with mutations distal to heme, previously known to be unstable. The other 3 mutants also released heme faster than A. These hemoglobins, with single point mutations at the alpha 1/beta 2 interface, were previously thought to be stable. The low reported yields of the 5 mutant proteins covaries with the relative rates of heme release from the met species.     

The Spontaneous Formation of Antheridia in Onoclea is not Blocked by Light

Onoclea sensibilis gametophytes were grown from spores on ashedsoil and agar to determine if the spontaneous formation of antheridiacan be blocked by light. Under most conditions, dark-grown gametophytesformed antheridia later than or at the same time as gametophytesgrown in the light. Under no circumstances was there a rapidonset of maleness in the dark. These results contradict thehypothesis that, in Onoclea, antheridiogen is required to inducemaleness because light inhibits the formation of antheridia.In the light, antheridia formed on heart-shaped thalli. In darkness,antheridia formed on filamentous gametophytes. The timing ofonset of maleness was affected by temperature and the presenceof sucrose. The effect of sucrose on the comparison betweenlight and dark treatments depended on both substrate and temperature Onoclea sensibilis, L., sensitive fern, fern gametophytes, sexuality, light-induced block     

The C4 and Slp genes of the complement region of the murine H-2 major histocompatibility complex

Recent analyses, at the protein and DNA levels of structure, of the murine complement components C4 and the closely related sex-limited protein, Slp have led to new insights into the H-2/S region-linked C4 and Slp genes and their products. The primary products are 200 000 Da precursors which are cleaved, intracellularly and extracellularly, into the the mature alpha-beta-gamma-subunit molecules of plasma. Precursor order of subunits is beta-alpha-gamma; a complementary DNA clone spanning the alpha-gamma junction has been extensively analysed. The C-terminal of the alpha-chain is of particular interest because of post-secretion processing which differentiates 'secreted' and 'plasma' forms of C4, both apparently functional, and because allelic variants of C4 and the Slp protein, which differ substantially in molecular masses, owe their differences principally to different levels of glycosylation of the alpha-chain. Allelic variations in rate of C4 synthesis (C4-high compared with C4-low) have been analysed in cultures of hepatocytes and macrophages. Three distinct modes of genetic regulation of the expression of the Slp protein have been identified.     

The biosynthetic pathway of new polyamines in Caldariella acidophila

A spontaneous mutant of Escherichia coli (strain AB2847), selected for resistance to the aminoglycoside antibiotic neamine, shows severe restriction of amber suppressors in vivo. Ribosomes isolated from the mutant exhibit only low misreading in vitro in the presence of the antibiotic. Genetic and biochemical analyses indicate that the neamine-resistant phenotype is the result of two distinct mutations. The first, res3128, appears to affect the gene (strA) coding for the ribosomal protein S12. Although it leads to a restrictive phenotype it does not, however, confer resistance to streptomycin. The second mutation, X3128, is located between the sirA and AROB loci and is lethal when segregated from the res3128 mutation. It may affect the ribosome at the level of a post-translational modification.     

Localization of acid phosphatase activity in the liver of pregnant rats

Synopsis In the liver of pregnant rats, fedad libitum, there was an increase in acid phosphatase specific activity which occurred in two peaks, one at the 15th day and the other at the end of gestation. By light and electron microscopic histochemistry, the activity was found to be localized in parenchymal cell peribiliary dense bodies and also in phagosomes present in macrophages and parenchymal cells. There was an increase in liver weight which reached a peak at the 17th day of gestation. Total DNA also rose to the 17th day; there was a high rate of cell division in the hepatic parenchyma at the 17th and 18th days of gestation. During this period single cell deletion by apoptosis was relatively frequent and in late pregnancy there was evidence of cell deletion by lysis.During pregnancy there was a slight increase in sinusoidal macrophages as a proportion of the total cell population but there did not appear to be significant changes in macrophage enzymic activity. It is suggested that the acid phosphatase activity present in macrophages makes a minor contribution to total liver activity, most of which is present in parenchymal cells. Acid phosphatase activity associated with single cell deletion appears to be quantitatively negligible.There was a direct relationship between total hepatic acid phosphatase activity and the numbers of peribiliary dense bodies, which were most numerous at the 15th day and at the end of gestation. It is suggested that these residual bodies contain products of detoxification processes and also cell structural elements resulting from enhanced liver metabolism and intracellular turnover during pregnancy.     

ON THE MECHANISM OF ELECTROSHOCK-INDUCED INHIBITION OF PROTEIN SYNTHESIS IN RABBIT CEREBRAL CORTEX

Abstract— The mechanism of electroshock (ES)-induced inhibition of protein synthesis in rabbit cerebral cortex has been investigated by using a cell-free system. The protein biosynthetic activity of the post-mitochondrial supernatant (PMS) obtained from the cerebral cortex of ES-treated animals was found to be markedly lower than in controls (C). This inhibition was accompanied by a decrease of polysomes and an increase of monomers. In addition, a relative increase in light polysomes was evident at short intervals after ES treatment. No difference was found in the total soluble activity and in the activity of the elongation factors and ribonuclease present in the cell sap of C and ES animals. The biosynthetic activity of ES-total. free and membrane-bound ribosomes was approx 45% lower than that of the corresponding C fractions: polysome/monomer ratios were similarly reduced. The total content of cortical ribosomes was not affected by ES. Following ES treatment there was no change in the ribo-somal ability to elongate, terminate and release polypeptide chains, nor a decrease in the polysomal content of poly(A)-containing mRNA. These data strongly suggest that the ES-induced inhibition of protein synthesis results from a defect in the initiation process. The possible mechanisms mediating this defect have been discussed.     

Ecophenotypic strategies of dalmanellid brachiopods

General ecophenotypic patterns, of particular interest when they apply to all, or most, taxa of the group concerned, can never be demonstrated until after monophyletic taxa have been recognized, that is, until after the initial stages of phylogeny construction have been carried out. In criticizing certain dalmanellid phylogenies, and based in large part on a study of five 'species subgroups'. Hurst & Watkins (1978; Geologica et Palaeontologica 12 ) postulate ecophenotypic patterns for Isorthis , and Hurst (1978; Palaeontology 21 ) postulates general patterns of ecophenotypic variation for dalmanellid brachiopods. These patterns may be invalid for four reasons: (1) Univariate and 'bivariate' statistical analysis of the samples used to define the five subgroups reveals no significant differences between subgroups, or vertical trends, for the very morphological characters claimed to exhibit the ecophenotypic patterns; (2) Hurst & Watkins' discriminant function analysis contains procedural errors and its results are ambiguous; (3) several of the five subgroups represent mixtures of unrelated taxa; (4) in recognizing the alleged patterns, Hurst & Watkins ignored contrary evidence from many taxa (and from many dalmanellid studies). □ Brachiopoda, Dalmanellidae, Silurian, ecology, evolution, systematics.