RNA-Induced Interference with Animal Virus Infection

Some RNAs, including both single- and double-stranded RNAs, when incubated with chick embryo cell culture induce cellular resistance against viruses. Evidence was now obtained indicating that the induction of cellular resistance by RNA depends on the cellular metabolic activity, especially on the synthesis of cellular RNA and protein. Thus, inhibitors of RNA and protein synthesis, actinomycin D and cycloheximide, were found to inhibit the development of an antiviral state when added before, or during the relatively early period of, incubation of the cells with RNA. In the course of induction of cellular resistance, three stages may be distinguished, the priming stage, the developing stage, and the established resistant stage.     

The influence of motor unit composition and stature on fractionated patellar reflex times in untrained men

The purpose of the present study was to investigate the influence of muscle fibre composition and stature on fractionated patellar reflex times in ten healthy untrained men (mean age: 23.3 years, SD 3.1; mass: 65.9 kg, SD 8.5; height: 172.3 cm, SD 5.3). Biopsies were taken from the right vastus lateralis muscle. Using staining for myofibrillar adenosine triphosphatase after pre-incubation at pH 4.3 and 4.6, muscle fibres were classified into slow twitch (ST), fast twitch, oxidative-glycolytic (FTa) and fast twitch, glycolytic (FTb) fibres. Total patellar reflex time (TRT) and its fractionated components--reflex latency (LAT) and reflex motor time (MT)--were obtained from the mean of ten trials in each subject whilst performing Jendrassik's maneuvre. The TRT, LAT and MT were 77.7 ms, SD 16.5, 23.4 ms, SD 1.3 and 54.2 ms, SD 16.3, respectively. The LAT was significantly correlated to the percentage number of ST (r = 0.758, P less than 0.05) and FTa fibres (r = -0.657, P less than 0.05), fast twitch:slow twitch ratio (r = -0.799, P less than 0.01) and to the height of the subjects (r = 0.901, P less than 0.001), whereas TRT and MT were not significantly correlated with either fibre types or the height of the subjects. From these results it can be concluded that the LAT during the patellar reflex is influenced by muscle fibre composition and the length of the sensory and/or motor nerve.     

Phosphorylation sites of bovine brain myelin basic protein phosphorylated with Ca2+-calmodulin-dependent protein kinase from rat brain

The phosphorylation sites of myelin basic protein from bovine brain were determined after phosphorylation with Ca2+-calmodulin-dependent protein kinase. Four phosphorylated peptides were selectively and rapidly separated by reversed-phase high-performance liquid chromatography. Partial sequencing of the phosphorylated peptides by automated Edman degradation revealed that Ca2+-calmodulin-dependent protein kinase phosphorylated serine-16, serine-70, and threonine-95 specifically, as well as serine-115, which is located on the experimental allergic encephalitogenic determinant of the protein. Of the four amino acid sequences determined, two sequences surrounding phosphorylated amino acids, -Lys-Tyr-Leu-Ala-Ser(P)16-Ala- and -Arg-Phe-Ser(P)115-Trp-Gly-, have both sides of each phosphoserine residue occupied by hydrophobic amino acids, and a basic amino acid, arginine or lysine, is located at the position 2 or 4 residues amino-terminal to the phosphoserine residue. In contrast, the two other sequences surrounding phosphorylated amino acids, -Tyr-Gly-Ser(P)70-Leu-Pro-Glu-Lys- and -Ile-Val-Thr(P)95-Pro-Arg-, have a basic amino acid at the position 2 or 4 residues carboxyl-terminal to the phosphoamino acid residue.     

Phosphorylation and Inactivation of Brain Glycogen Synthase by a Multifunctional Calmodulin-Dependent Protein Kinase

Glycogen synthase was partially purified from canine brain to about 70% purity. The purified enzyme showed differences from the properties of the skeletal muscle enzyme with respect to molecular weights of the holoenzyme and subunit and phosphopeptide mapping. The multifunctional calmodulin-dependent protein kinase from the brain phosphorylated brain glycogen synthase with concomitant inactivation of the enzyme. Although about 1.3 mol of phosphate/mol subunit was maximally incorporated into glycogen synthase, 0.4 mol of phosphate/mol subunit was sufficient for the maximal inactivation of the enzyme. The results indicate that brain glycogen synthase is regulated in a calmodulin-dependent manner similarly to the skeletal muscle enzyme, but that the brain enzyme is different from the skeletal muscle enzyme.     

Distribution and evolution of C4 syndrome inRhynchospora (Rhynchosporeae-Cyperaceae)

In order to elucidate the evolution of C₄ syndrome, the taxonomic relationships, leaf anatomy, and ecological and global distribution of C₃ and C₄ species in the genusRhynchospora were investigated. The anatomical observation for 181 species revealed that 26 C₄ species occurred within theCapitatae group of the subgenusHaplostyleae, a natural group showing highly advanced morphological characteristics, together with several C₃ species. In spite of there being rather few C₄ species, they possessed two kinds of Kranz anatomical structure differing from each other in the location of Kranz cells. Some C₃ species ofCapitatae showed radial arrangement in mesophyll cells surrounding vascular bundles, which is distinguished from typical non-Kranz anatomy. The C₄ species extended their ecological ranges from wet habitats to dry savanna grasslands, while the C₃ species showed the best development in wet habitats. The C₃ species were widespread from tropical to temperate regions with partial range extension into subarctic regions of both hemispheres, showing conspicuously high concentration of species in the New World, but being absent from arid climatic regions. The C₄ species were distributed mostly in tropics and subtropics, showing two separate distributional centers in South and Central America and in Tropical Asia and Australia. The range of C₄ species was nearly completely included in the C₃ range. In conclusion, it seems that inRhynchospora the C₄ syndrome evolved relatively recently, and arose in at least two separate phylogenetic trends in the tropics and the subtropics, more probably in the Neotropics.     

Aminergic and peptidergic amplification of intracellular cyclic AMP levels in a molluscan neural network

1. Serotonin (5-hydroxytryptamine; 5-HT), dopamine (DA), and small cardioactive peptide B (SCPB) can activate adenylate cyclase and increase the intracellular cyclic AMP (cAMP) levels in the Limax procerebrum (PC), with differing time courses and to differing extents. 5-HT and SCPB are potent stimulators of adenylate cyclase, and when both were applied simultaneously, an additive effect was observed. 2. In contrast, DA shows a great variability in the time course of cAMP synthesis and is a weak stimulator. Ergonovine, a DA antagonist, failed to inhibit cyclase activation, indicating that ergonovine-sensitive receptors are absent or ergonovine-sensitive DA receptors are not coupled to adenylate cyclase. 3. 5-HT and SCPB cause a rapid synthesis of cAMP, reaching the maximum 20- to 30-fold increase within a minute. DA's effect is slow in onset and very prolonged, reaching a maximum of only a two- to three-fold increase in the cAMP level. Reasons for variability in DA action are discussed.     

TheRT1.G locus in the rat encodes a Qa/TL-like antigen

A new antigenic system in the rat homologous to theQa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations that were matched for theRT1. A, B, D, E loci in the major histocompatibility complex (MHC): (R11×BN)F₁ anti-BN.1L(LEW), (R18×BN)F₁ anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic and recombinant strains identified three alleles,RT1.G ^a ,G ^b ,G ^c , of whichG ^c is a null allele. The strain distribution of these alleles was determined, using 37 strains of rats representative of all of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains showed that theRT1.G locus was linked to the MHC and that the most probable gene order wasA-E-G. Testcross analysis showed that the map distance betweenA andG was 1.4 cM(4/285 recombinants). The RT1.G antigen has a heavy chain ofM _r 46 000 and is present on both T and B cells.     

Cloning of genes for a hemolytic factor of Leptospira interrogans serovar autumnalis strain Congo 21-543

A DNA fragment encoding a hemolytic factor was cloned from the parasitic spirochete Leptospira interrogans serovar autumnalis strain Congo 21-543. Initial clones were isolated by screening a genomic library in pBR322 in Escherichia coli for hemolytic activity. Hemolytic activity was coded by a 4.5 kilobase BamHI-HindIII fragment. Southern hybridization with DNAs from other strains of Leptospira using this gene as a probe showed that DNAs from non-parasitic strains failed to hybridize with the probe, whereas those from all parasitic strains tested had the sequence which hybridize to the probe.