First report of the invasive crop pest Stenocranus pacificus (Hemiptera: Delphacidae) in temperate Asia

Numerous delphacid planthopper species are major pests of economically important and widely cultivated crops (i.e. rice, corn, and sugarcane). These insects have the potential to become serious crop pests in areas where they have either naturally migrated or been newly introduced. The white-bellied planthopper, Stenocranus pacificus Kirkaldy, 1907, originally known from tropical South Pacific islands, appeared in tropical and subtropical Asia in the early years of the 21st century. Since then, S. pacificus has become a serious pest of corn in some Southeast Asian countries, although it also feeds on rice, sugarcane, sorghum, and other grasses. Here, we report the presence of S. pacificus in mainland Japan, representing the first record of this species in temperate Asia. Seven male and 17 female adult individuals collected in Kumamoto Prefecture in 2019 and 2020 were identified as S. pacificus based on their morphological characteristics and mitochondrial COI sequences. In addition, molecular phylogenetic analysis showed that S. pacificus formed a distinct clade from other Stenocranus species, indicating uncertainty in its generic assignment. Although crop damage by S. pacificus has not yet been reported from temperate regions, given its wide range of plant hosts and the potential for future range expansions, damaged crops in Asia, including in temperate regions, should be monitored for the presence of this species.     

Localization of pp60c-src in growth cone of PC12 cell

By immunocytochemical and biochemical techniques, we observed the localization and expression of pp60c-src in nerve growth factor (NGF)-treated PC12 cells. Immunostaining of pp60c-src is detected in the neuronal soma and the tips of neurites (growth cones). Immunofluorescence in the neurites is less significant. High-resolution microscopy reveals that the location of pp60c-src in growth cone is in good agreement with the adhesive site of growth cone to the substratum. The pp60c-src kinase activity and the pp60c-src protein level increase 3.1- to 3.5-fold and 2.0-fold during differentiation of PC12 cells, respectively. The pp60c-src levels in the neurite fraction are also higher than those in the neuronal soma fraction. These results support the immunocytochemical finding that pp60c-src is localized in growth cones of differentiated PC12 cells. Furthermore, we discuss the possible role of pp60c-src in growth cone.     

Rap1 is activated by erythropoietin or interleukin-3 and is involved in regulation of beta1 integrin-mediated hematopoietic cell adhesion

The CrkL adaptor protein is involved in signaling from the receptor for erythropoietin (Epo) as well as interleukin (IL)-3 and activates beta(1) integrin-mediated hematopoietic cell adhesion through its interaction with C3G, a guanine nucleotide exchange factor for Rap1. We demonstrate here that Epo as well as IL-3 activates Rap1 in an IL-3-dependent hematopoietic cell line, 32D, expressing the Epo receptor. The cytokine-induced activation of Rap1 was augmented in cells that inducibly overexpress CrkL or C3G. The CrkL-mediated enhancement of cell adhesion was inhibited by expression of a dominant negative mutant of Rap1, Rap1A-17N, whereas an activated mutant of Rap1, Rap1A-63E, activated beta(1) integrin-dependent adhesion of hematopoietic cells. In 32D cells, Rap1 was also activated by phorbol 12-myristate 13-acetate and ionomycin, which also enhanced cell adhesion to fibronectin, whereas, an inhibitor of phospholipase C, inhibited both cytokine-induced activation of Rap1 and cell adhesion. It was also demonstrated that Rap1 as well as CrkL is involved in signaling from the EpoR endogenously expressed in a human leukemic cell line, UT-7. These results suggest that Epo and IL-3 activate Rap1 at least partly through the CrkL-C3G complex as well as through additional pathways most likely involving phospholipase Cgamma and strongly implicate Rap1 in regulation of beta(1) integrin-mediated hematopoietic cell adhesion.     

Thrombin activates p38 mitogen-activated protein kinase in vascular smooth muscle cells

Thrombin is a potent mitogen for vascular smooth muscle cells. However, the signaling pathways by which thrombin mediates its mitogenic response are not fully understood. The ERK (extracellular signal-regulated protein kinase) and JNK (c-Jun N-terminal kinase) members of the mitogen-activated protein kinase (MAPK) family are reported to be activated by thrombin. We have investigated the response to thrombin of another member of the MAPK family, p38 MAPK, which has been suggested to be activated by both stress and inflammatory stimuli in vascular smooth muscle cells. We found that thrombin induced time- and dose-dependent activation of p38 MAPK. Maximal stimulation of p38 MAPK was observed after a 10-min incubation with 1 unit ml(-1) thrombin. GF109203X, a protein kinase C inhibitor, and prolonged treatment with phorbol 12-myristate 13-acetate partially inhibited p38 MAPK activation. A tyrosine kinase inhibitor, genistein, also inhibited p38 MAPK activation in a dose-dependent manner. p38 MAPK activation was inhibited by overexpression of betaARK1ct (beta-adrenergic receptor kinase I C-terminal peptide). p38 MAPK activation was also inhibited by expression of dominant-negative Ras, not by dominant-negative Rac. We next examined the effect of a p38 MAPK inhibitor, SB203580, on thrombin-induced proliferation. SB203580 inhibited thrombin-induced DNA synthesis in a dose-dependent manner. These results suggest that thrombin activates p38 MAPK in a manner dependent on Gbetagamma, protein kinase C, a tyrosine kinase, and Ras, that p38 MAPK has a role in thrombin-induced mitogenic response in the cells.     

Signaling via fibroblast growth factor receptor-1 is dependent on extracellular matrix in capillary endothelial cell differentiation

Differentiation of endothelial cells, i.e., formation of a vessel lumen, is a prerequisite for angiogenesis. The underlying molecular mechanisms are ill defined. We have studied a brain capillary endothelial cell line (IBEC) established from H-2Kb-tsA58 transgenic mice. These cells form hollow tubes in three-dimensional type I collagen gels in response to fibroblast growth factor-2 (FGF-2). Culture of IBEC on collagen gels in the presence of FGF-2 protected cells from apoptosis and allowed tube formation (i.e., differentiation) but not growth of the cells. FGF-induced differentiation, but not cell survival, was inhibited by treatment of the cells with an anti-beta1-integrin IgG. Changes in integrin expression in the collagen-gel cultures could not be detected. Rather, cell-matrix interactions critical for endothelial cell differentiation were created during the culture, as indicated by the gradual increase in tyrosine phosphorylation of focal adhesion kinase in the collagen-gel cultures. Inclusion of laminin in the collagen gels led to FGF-2-independent formation of tube structures, but cells were not protected from apoptosis. These data indicate that FGF receptor-1 signal transduction in this cell model results in cell survival. Through mechanisms dependent on cell-matrix interactions, possibly involving the alpha3beta1-integrin and laminin produced by the collagen-cultured IBE cells, FGF stimulation also leads to differentiation of the cells.     

Heat stress aggravates viral myocarditis in mice

While a beneficial effect of hyperthermia on viral infection has been hypothesized, there are no data on viral myocarditis in vivo. To investigate whether hyperthermia might attenuate the course or severity of viral myocarditis, we studied the pathological changes in a murine model of viral myocarditis. C3H mice were inoculated i.p. with the encephalomyocarditis virus (500 pfu). They were anesthetized and heated to a body temperature of 42.5+/-0.2 degrees C for 30 min. The latter was performed 4 hr before (n=28, HB) or 4 hr after (n=28, HA) the viral inoculation; results were compared with nonheated, infected controls (n=30, Cont). Cardiac viral titers were recorded on day 3, and the body weight (BW), heart weight (HW) and pathological changes were recorded on days 5 and 10. The incidence of spontaneous mortality on day 10 was significantly higher in the HA group (all deaths occurring by day 7 post-inoculation) as compared with the HB (35%) or Cont (18%) groups. Viral titers in the HA group (n=4) were significantly (P<0.05) higher than those in the Cont (n=7) or HB (n=7) groups (4.11+/-0.54 vs 3.01+/-0.44 and 3.23+/-0.45 LogTCID50/mg, respectively). On day 5, the HW, the BW/HW ratio, and the severity of myocardial necrosis were all significantly higher in the HA than in the Cont and HB groups. To confirm the effect of hyperthermia on the expression of heart shock protein (HSP), immunohistochemical staining was done in the virus-infected hearts. The nucleus and cytoplasm of the injured myocardium in the HA group strongly expressed HSP70, whereas the HB and Cont groups were negative for this protein. In conclusion, induction of hyperthermia after viral inoculation aggravated the viral-induced myocardial necrosis and increased the mortality rate in a murine model of viral myocarditis and induced myocardial heat shock protein 70.     

Highly stable L-lysine 6-dehydrogenase from the thermophile Geobacillus stearothermophilus isolated from a Japanese hot spring: characterization, gene cloning and sequencing, and expression

L-Lysine dehydrogenase, which catalyzes the oxidative deamination of L-lysine in the presence of NAD, was found in the thermophilic bacterium Geobacillus stearothermophilus UTB 1103 and then purified about 3,040-fold from a crude extract of the organism by using four successive column chromatography steps. This is the first report showing the presence of a thermophilic NAD-dependent lysine dehydrogenase. The product of the enzyme catalytic activity was determined to be Delta1-piperideine-6-carboxylate, indicating that the enzyme is L-lysine 6-dehydrogenase (LysDH) (EC 1.4.1.18). The molecular mass of the purified protein was about 260 kDa, and the molecule was determined to be a homohexamer with subunit molecular mass of about 43 kDa. The optimum pH and temperature for the catalytic activity of the enzyme were about 10.1 and 70 degrees C, respectively. No activity was lost at temperatures up to 65 degrees C in the presence of 5 mM L-lysine. The enzyme was relatively selective for L-lysine as the electron donor, and either NAD or NADP could serve as the electron acceptor (NADP exhibited about 22% of the activity of NAD). The Km values for L-lysine, NAD, and NADP at 50 degrees C and pH 10.0 were 0.73, 0.088, and 0.48 mM, respectively. When the gene encoding this LysDH was cloned and overexpressed in Escherichia coli, a crude extract of the recombinant cells had about 800-fold-higher enzyme activity than the extract of G. stearothermophilus. The nucleotide sequence of the LysDH gene encoded a peptide containing 385 amino acids with a calculated molecular mass of 42,239 Da.     

Cytokine mRNA expression in unilateral ischemic-reperfused rat lung with salt solution supplemented with low-endotoxin or standard bovine serum albumin

Our aim was to determine whether cytokine mRNA expression is induced by experimental manipulation including artificial perfusate or ischemia-reperfusion (I/R) in an isolated, perfused rat lung model. Constant pulmonary flow [Krebs-Henseleit solution supplemented with low-endotoxin (LE) or standard (ST) bovine serum albumin 4%, 0.04 ml/g body wt] and ventilation were maintained throughout. Right and left pulmonary arteries were isolated, and the left pulmonary artery was occluded for 60 min and then reperfused for 30 min. Analysis of tumor necrosis factor-alpha, IL-1 beta, IL-6, IL-10, and IFN-gamma mRNA expression by RT-PCR and evaluation of vascular permeability by bronchoalveolar lavage (BAL) fluid albumin content were conducted separately in right and left lung. Both LE and ST groups (each 12 rats) showed increases in vascular permeability by I/R (BAL fluid albumin content: 5.53 +/- 1.55 vs. 15.63 +/- 8.87 and 4.76 +/- 2.71 vs. 16.72 +/- 4.85 mg.ml BAL fluid-1.g lung dry wt-1, mean +/- SD; right vs. left lung in LE and ST groups, P < 0.05 between right and left). Cytokine mRNA expression was significantly higher in the I/R lung than in the control lung in the LE group, whereas it was higher in the control lung in the ST group (P < 0.05). mRNAs of not only proinflammatory but also anti-inflammatory cytokines were expressed in I/R lung, which are expected to aggravate I/R injury. The reversed pattern of cytokine mRNA expression in the ST group was possibly due to the longer perfusion of control lung with perfusate containing endotoxin, which caused no lung damage without I/R.