Epidemiology of parainfluenza virus types 1, 2 and 3 infections based on virus isolation between 2002 and 2011 in Yamagata,Japan

To clarify the epidemiology of viral acute respiratory infections (ARIs), 305 human parainfluenza virus types 1 (HPIV1), 154 HPIV2 and 574 HPIV3 strains were isolated from 16,962 nasopharyngeal swabs obtained between 2002 and 2011 at pediatric clinics in Yamagata, Japan. The total isolation frequency for HPIV1–3 was 6.1%. Unlike HPIV1 infections, HPIV3 showed clear seasonality with yearly outbreaks in the spring–summer season. HPIV2 tended to appear biannually in autumn–winter. Although no reliable techniques for the laboratory diagnosis of these infections have been established, the present results suggest that HPIV1–3 are an important causative agent of ARIs in children.     

Ribosomal protein modification in Escherichia coli

Summary Among mutants of E. coli selected for temperaturesensitive growth, four were found to possess alterations in ribosomal proteins L7/L12. Of these, three apparently lack protein L7, the acetylated form of protein L12. Genetic analyses have revealed that the mutation responsible for this alteration maps at a locus around 34 min of the current E. coli genetic map, which is clearly different from the location for the structural gene for protein L7/L12 which is situated at 89 min. Hence, the gene affected in these mutants was termed rimL. Tryptic and thermolysin fingerprints of the protein L12 purified from the rimL mutants showed a profile indistinguishable from that of wild-type protein. It was found that the acetylase activity specific for protein L12 was negligible, when assayed in vitro, in the high-speed supernatant prepared from mutant cells. These results indicated that the three mutants contain mutations in the gene rimL that codes for an acetylating enzyme specific for ribosomal protein L12.Previous paper in this series is Isono and Isono (1980)     

Membrane-potential- and surface-potential-induced absorbance changes of merocyanine dyes added to chromatophores from Rhodopseudomonas sphaeroides

(1) Three analogs of merocyanine dyes added to suspensions of chromatophore vesicles showed absorbance changes responding to the change in surface potential induced by salt addition and to the change in membrane potential induced by illumination. (2) The extent of the light-induced absorbance changes of the dyes was linearly related, in the presence and absence of uncouplers, to that of carotenoid spectral shift which is an intrinsic probe of the intramembrane electric field. (3) Comparison of the merocyanine absorbance changes induced by salt addition with those induced by illumination indicated that the surface potential change in the outer surface of chromatophore membranes during illumination was very small. (4) Judging from the spectra of these absorbance and from the low permeabilities of the dyes to membrane, the absorbance change are attributed to change in distribution of the dyes between the medium and the outer surface region in chromatophore membranes. The extent of the light-induced absorbance changes of merocyanine dyes depended on the salt concentration of the medium. The types of dependence were different among three merocyanine analogs. This is explained by the mechanism mentioned above assuming appropriate parameters. It is suggested that, under continuous illumination, an equilibrium of the electrochemical potential of H⁺ is reached between the bulk aqueous phase and the outer surface region in the membrane where the merocyanine dyes are distributed.     

Deterred oviposition response of Monochamus alternatus (Coleoptera: Cerambycidae) to oviposition scars occupied by eggs

1 The oviposition behaviour and response of Monochamus alternatus females to oviposition scars were investigated in the laboratory. 2 Prior to oviposition, females gnawed at the bark surface of Pinus densiflora bolts to make a wound. Then females turned their bodies 180° to position their ovipositors over the wounds and inserted them under the bark through the wounds. After an oviposition, a jelly was deposited while the ovipositor was still inserted. The females then withdrew their ovipositors and rubbed the oviposition scars with the tips of their abdomens. 3 When searching females encountered oviposition scars, they stopped walking and drummed the surface and inside of the oviposition scars with their maxillary and labial palpi. 4 Eighty-six percent of females left oviposition scars containing single eggs after the palpation. By contrast, when females encountered oviposition scars containing no eggs, 76% of them began to gnaw at the scars and 64% deposited single eggs. The response to artificial oviposition scars was similar to that to vacant oviposition scars made by the females. 5 The results of various observations and experiments showed that the females could recognize oviposition scars and discriminate the scars occupied by single eggs from vacant ones, and suggested that the palpation of oviposition scars was the critical discrimination behaviour, indicating mediation by chemical cues.     

Modeling the Expansion of an Introduced Tree Disease

Pine wilt disease is caused by the introduced pinewood nematode, Bursaphelenchus xylophilus, for which the vector is the pine sawyer beetle, Monochamus alternatus. Native Japanese pines, black pine (Pinus thunbergii) and red pine (P. densiflora), are extremely sensitive to the nematode's infection, and the parasite has been expanding nationwide in the last few decades, despite intensive control efforts. To understand the parasite's range expansion in Japan, we modeled the dynamics of the pines and the beetle that disperses the nematode, using an integro-difference equation in a one-dimensional space. Based on field data collected in Japan, we investigated the dependence of the parasite's rate of range expansion on the eradication rate of the beetle, the initial pine density, and the beetle dispersal ability. Our model predicts several results. (1) The Allee Effect operates on beetle reproduction, and consequently the parasite cannot invade a pine stand, once the beetle density decreases below a threshold. (2) The distribution of the dispersal distance of the beetles critically affects the expansion rate of the disease. As the fraction of the beetles that travel over long distance increases from zero, the range expansion accelerates sharply. (3) However, too frequent long-range dispersal results in a failure of the parasite invasion due to the Allee Effect, suggesting the importance of correctly assessing the beetle's mobility to predict the speed of range expansion of the parasite. (4) As the eradication rate is increased, the range expansion speed decreases gradually at first and suddenly drops to zero at a specific value of the eradication rate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Purification of Ribulose 5-phosphate Kinase and Minor Polypeptides of Pyrenoid from the Green Alga Bryopsis maxima

Ribulose 5-phosphate (Ru5P) kinase (ATP:D-ribulose 5-phosphate1-phosphotrans- ferase; EC 2.7.1.19 [EC] ), an enzyme in the reductivepentose phosphate cycle, was purified from the green alga Bryopsismaxima and its activity and peptide composition were studied.The specific activity of purified Ru5P kinase was 20 µmoleRuBP formed (mg protein)^–1 min^–1 corresponding toa 490-fold purification from the supernatant of chloroplasts.The K_m values of Ru5P kinase for ATP and Ru5P were 69 µMand 330 µM, respectively. The molecular size of Ru5P kinase was estimated as 90 kDa bygel filtration and that of its polypeptide as 41 kDa by SDS-polyacrylamidegel electrophoresis. A small portion of the Ru5P kinase wasfound in a large molecular state (500 kDa) which was consideredto be an inactive form of the enzyme. Ru5P kinase activity has been reported in the pyrenoid of Eremosphaeraviridis as well as ribulose 1,5-bisphosphate carboxylase-oxygenase(RuBisCO) and ribose 5-phosphate isomerase activity (Holdsworth1971). In Bryopsis maxima, among the pyrenoid polypeptides otherthan that of RuBisCO, we found a polypeptide of 42 kDa, similarto that of Ru5P kinase in molecular size and ratio to RuBisCO.A peptide map of the 42 kDa pyrenoid polypeptide, however, showedthat it differed from that of Ru5P kinase. In conclusion, Ru5Pkinase may be not involved in the pyrenoid of this alga. (Received January 19, 1985; Accepted May 15, 1985)     

RAD51 homologues in Xenopus laevis: two distinct genes are highly expressed in ovary and testis

The RAD51 gene is a eukaryotic counterpart of the Escherichia coli recA gene which is involved in genetic recombination. Two distinct Xenopus laevis RAD51 cDNA clones (XRAD51.1 and XRAD51.2) were isolated from an oocyte cDNA library using the human RAD51 cDNA (HsRAD51) as a probe. Sequence analysis revealed that 98.2% of the amino-acid residues were identical between XRAD51.1 and XRAD51.2, and that both were 95% identical to HsRAD51. Both of the XRAD51 genes were expressed at a higher level in ovary and testis than in other somatic tissues, suggesting their involvement in meiotic recombination. The expression of XRAD51.1 was about eightfold in excess of that of XRAD51.2 in all of the tissues examined. Analysis of the rates of synonymous substitution in the coding sequences of the two XRAD51 suggests that these two genes diverged about 50 million years ago. The structural similarities of the XRAD51 proteins to RecA in E. coli and Rad51 in yeasts or vertebrates are discussed.     

Akt is an endogenous inhibitor toward tumor necrosis factor-related apoptosis inducing ligand-mediated apoptosis in rheumatoid synovial cells

Akt is known to be activated in the rheumatoid synovial tissues. We examined here functional role of Akt during tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-mediated apoptosis in rheumatoid synovial cells. Rheumatoid synovial cells in vitro were rapidly committed to apoptosis in response to TRAIL in mitochondria-dependent manner whereas Akt and extracellular signal-regulated kinase (ERK) were also phosphorylated. TRAIL-mediated apoptosis in synovial cells was significantly increased through inactivation of Akt by LY294002, however, that process was not so changed by adding ERK inhibitor, PD98059. Platelet-derived growth factor (PDGF) clearly phosphorylated both Akt and ERK in synovial cells, and PDGF pretreatment markedly suppressed TRAIL-mediated synovial cell apoptosis. The use of not PD98059 but LY294002 abrogated PDGF-mediated inhibitory effect toward TRAIL-induced apoptosis in synovial cells. The above protective effect of Akt was confirmed by the use of short interfering RNA (siRNA)-directed inhibition of Akt. Our data suggest that Akt is an endogenous inhibitor during TRAIL-mediated synovial cell apoptotic pathway, which may explain that synovial cells in situ of the rheumatoid synovial tissues are resistant toward apoptotic cell death in spite of death receptor expression.     

Anticarcinogenesis pathways activated by bovine lactoferrin in the murine small intestine

Oral administration of bovine lactoferrin (bLF) inhibits carcinogenesis in the colon and other organs in rats, and lung metastasis in mice. A likely mechanism by which bLF mediates its anticarcinogenesis effects is by enhanced expression of cytokines and subsequent activation of immune cells. Oral administration of bLF enhances expression of interleukin-18 (IL-18) mRNA in the mucosa of the small intestine of mice. Importantly, the pepsin hydrolysate of bLF (bLFH) also induced expression of IL-18 mRNA in the mouse small intestine and a peptide produced by pepsin digestion of bLF, bovine lactoferricin (bLFcin), induced expression of mature IL-18 in organ culture. In addition to IL-18, bLF and bLFcin both induced significant increases in caspase-1 activity in peritoneal macrophages and in organ cultures. The increase of mature IL-18 by macrophages was inhibited by caspase-1 inhibitor: caspase-1 is known to cleave the proform of IL-18 to produce active mature IL-18. Finally, bLF also induced expression of IFNgamma by peritoneal macrophages. Importantly, in IFNgamma knockout (GKO) mice, bLF administration resulted in increased expression of caspase-1 protein, but induction of IL-18 mRNA, caspase-1 activity, and mature IL-18 was not observed. These results indicate that orally administered bLF can induce expression of IFNgamma and caspase-1 in the small intestine. IFNgamma in turn increases expression of target genes, including IL-18. Active caspase-1 then cleaves pro-IL-18 to generate mature IL-18. Thus, bLF activates an effector pathway mediated by IFNgamma, caspase-1, and IL-18. We also show that ingested bLF is able to activate more than a single effector pathway. For example, in GKO mice while bLF administration could not activate the IFNgamma/caspase-1/IL-18 effector pathway, it was able to inhibit tumor growth and metastasis by activation of an IFNalpha/IL-7 effector pathway.     

Formation of toxic fibrils of Alzheimer's amyloid beta-protein-(1-40) by monosialoganglioside GM1, a neuronal membrane component

A pathological hallmark of Alzheimer's disease (AD) is the deposition of amyloid beta-protein (Abeta) in fibrillar form on neuronal cells. However, the role of Abeta fibrils in neuronal dysfunction is highly controversial. This study demonstrates that monosialoganglioside GM1 (GM1) released from damaged neurons catalyzes the formation of Abeta fibrils, the toxicity and the cell affinity of which are much stronger than those of Abeta fibrils formed in phosphate-buffered saline. Abeta-(1-40) was incubated with equimolar GM1 at 37 degrees C. After a lag period of 6-12 h, amyloid fibrils were formed, as confirmed by circular dichroism, thioflavin-T fluorescence, size-exclusion chromatography, and transmission electron microscopy. The fibrils showed significant cytotoxicity against PC12 cells differentiated with nerve growth factor. Trisialoganglioside GT1b also facilitated the fibrillization, although the effect was weaker than that of GM1. Our study suggests an exacerbation mechanism of AD and an importance of polymorphisms in Abeta fibrils during the pathogenesis of the disease.