Abortive Infection of L Cells by Influenza B Virus: Defect in Bud Formation

Host-dependent restriction of influenza B virus replication in L cells was analysed in comparison with productive infection in MDCK or 1–5C-4 cells. The synthesis and intracellular distribution of virus-specific proteins and the production of cytoplasmic ribonucleoproteins in nonpermissive L cells were similar to those in permissive MDCK cells. However, an electron microscopic study of infected L cells showed neither extracellular virions nor budding virus particles on the cell surface, in contrast to MDCK cells which produced numerous virus particles. PAGE analysis of the plasma membrane isolated from the cells demonstrated no significant difference in the composition of viral polypeptides between permissive 1-5C-4 and nonpermissive L cells. It was noted that the abortiveness of influenza B virus infection in L cells may be due to a defect in host cell function involved in the initiation of virus budding.     

Macrophage chemotactic factor (MCF) produced by a human T cell hybridoma clone

A human T cell hybridoma clone, D6-18, producing high levels of macrophage chemotactic factor (MCF) was established by the emetine-actinomycin D selection method. MCF was found to be present not only in the culture medium but also in the cell lysate of D6-18 cells. The secretion of the MCF from D6-18 cells was effectively inhibited by disodium cromoglycate, which is an inhibitor of the degranulation of mast cells, suggesting that MCF is stored in granules. The MCF of D6-18 cells was purified from the sonicated cell lysate by ion-exchange chromatographies and high-performance liquid chromatography. The amino acid sequence of the purified MCF was revealed to be WLGREDGSE or WLGRQDGSE. The synthetic peptide WLGREDGSE showed chemotactic activity against guinea pig macrophages and human monocytes at the concentration of about 10(-8) M.     

Effect of chemical modifications on freeze denaturation of lactate dehydrogenase

Lactate dehydrogenase (LDH) was chemically ethyl-acetimidated (EA-), dimethyladipimidated (DMA-), carbamylated, acetylated, acetoacetylated, or succinylated in order to alter the ionic charges on the epsilon-amino group of lysine residues. Acetylation, acetoacetylation, and succinylation, which change the positive charge at the lysine side chains to a negative one, inactivated the enzymic activity, but the rest of the modifications exerted no such inactivating effects. The active modified enzymes were subjected to freeze denaturation study, using the enzymic activity as an indication of the degree of the denaturation. The active enzymes were diluted with deionized water and stored in a freezer (-23 degrees C) for 1-3 days. Enzymic activity was assayed immediately after thawing. All the modified enzymes retained their activity even after the 3-day frozen storage, while the control or native enzyme lost its activity within 1 day of storage. Furthermore, the modified LDHs freeze-stored in 0.2 M monosodium glutamate (MSG) or 0.2 M lysine-hydrochloride (Lys-HCl) retained their activity. The cryoprotective effects exerted by the modifications and by 0.2 M MSG seemed to be synergistic, whereas those exerted by the modifications and by 0.2 M Lys-HCl did not. The mechanisms of cryoprotection and freeze denaturation are discussed in relationship with the cryoprotective effect exerted by already known cryoprotectants, such as sucrose or dimethyl sulfoxide.     

Lidocaine inhibits stimulation-coupled responses of neutrophils and protein kinase C activity

The effects of lidocaine, a local anesthetic, on various stimulation-coupled responses of neutrophils were studied. Superoxide generation, generation of chemiluminescence, depolarization of membrane potential and transitional increase in intracellular Ca2+ were inhibited by lidocaine in a concentration dependent manner. Lidocaine also inhibited Ca(2+)-activated phospholipid-dependent protein kinase (PKC) in the presence of various concentrations of Ca2+, phosphatidylserine and dioleoylglycerol. For the inhibition of all these stimulation-coupled responses, a similar order of the lidocaine concentration was needed. As in the case of dibucaine (Mori, T., Takai, Y., Minakuchi, R., Yu, B. and Nishizuka, Y., J. Biol. Chem. 255:8378-8380, 1980), lidocaine inhibited PKC activity in a manner competitive with phosphatidylserine. Lidocaine also inhibited the phosphorylation of 47 kDa neutrophil cytosplasmic protein, a phosphorylated protein required for NADPH oxidase activation. Thus, the cellular membrane phospholipid may be one of the target sites of lidocaine for the inhibitory action on the various stimulation-coupled responses of neutrophils, and these effects of lidocaine may correlate with its inhibitory action on PKC activity.     

Effects of water level fluctuation on the growth ofNelumbo nucifera Gaertn. in Lake Kasumigaura,Japan

Investigations were made of the growth ofNelumbo nucifera, an aquatic higher plant, in a natural stand in Lake Kasumigaura. A rise of 1.0 m in the water level after a typhoon in August 1986 caused a subsequent decrease in biomass ofN. nucifera from the maximum of 291 g d.w. m⁻² in July to a minimum of 75 g d.w. m⁻². The biomass recovered thereafter in shallower regions. The underground biomass in October tended to increase toward the shore. The total leaf area index (LAI) is the sum of LAI of floating leaves and emergent leaves. The maximum total LAI was 1.3 and 2.8 m² m⁻² in 1986 and 1987, respectively. LAI of floating leaves did not exceed 1 m² m⁻². The elongation rates of the petiole of floating and emergent leaves just after unrolling were 2.6 and 3.4 cm day⁻¹, respectively. The sudden rise in water level (25 cm day⁻¹) after the typhoon in August 1986 caused drowning and subsequent decomposition of the mature leaves. Only the young leaves were able to elongate, allowing their laminae to reach the water surface. The fluctuation in water level, characterized by the amplitude and duration of flooding and the time of flooding in the life cycle, is an important factor determining the growth and survival ofN. nucifera in Lake Kasumigaura.     

Growth analysis ofQuercus serrata seedlings withinMiscanthus sinensis grass canopies differing in light availability

The effects of different light regimes on the survival, growth and morphology ofQuercus serrata seedlings were studied in canopies ofMiscanthus sinensis. The seedlings of various ages (0–3 yr) were grown in three light regimes: under a denseM. sinensis canopy (TG plot) receiving 2.5%–8.7% of full sunlight, under a relatively sparse canopy (SG plot) receiving 3.8%–16.1% of light and in an adjacent open site (NG plot). There was a little difference in the survival ofQ. serrata seedlings among the three plots. Height and diameter of stem and total leaf area of the seedlings were significantly lower in the shadier plots. However, the first (bottom) flush of the stem was significantly longer in the TG plot than in the NG and SG plots. Total dry weights of individual 1- and 2-yr-oldQ. serrata seedlings in the TG plot were reduced to about one-twelfth of those in the NG plot. Although the relative proportion in dry weight of each organ did not differ significantly among the plots, leaf area ratio, specific leaf area and stem height per unit dry weight were significantly higher in shadier plots. The leaf area per unit stem height was increased considerably in the sunnier plots.     

Preferential ADP-ribosylation of arginine-3 in synthetic heptapeptide Leu-Arg-Arg-Ala-Ser-Leu-Gly.

Hen liver nuclear ADP-ribosyltransferase modified the synthetic heptapeptide Kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly) at arginine-2 and/or arginine-3. Trypsin treatment of ADP-ribosyl-Kemptide revealed that the ADP-ribosylation of arginine-3 was constantly more abundant than that of arginine-2. ADP-ribosylation of Kemptide suppressed the subsequent phosphorylation by cyclic AMP-dependent protein kinase.