Direct and feeding‐induced interactions between two rice planthoppers, Sogatella furcifera and Nilaparvata lugens: effects on dispersal capability and performance

Abstract. 1. A series of laboratory experiments was conducted to explore the effects of inter‐specific interactions, both direct interactive effects and those induced through previous feeding, on the dispersal capability (proportion of macropterous adults) and performance (development time and survival) of two wing‐dimorphic planthoppers, the whitebacked planthopper Sogatella furcifera and the brown planthopper Nilaparvata lugens, two pests of rice throughout Asia. 2. An asymmetric effect of inter‐specific crowding on dispersal capability was detected between the two planthoppers. With density controlled, the proportion of macropterous adults in N. lugens was higher when raised in mixed populations with S. furcifera than in pure cultures comprised of conspecifics, suggesting that interspecific effects on dispersal capability are stronger than intraspecific effects. In contrast, interspecific effects on macroptery (%) were weaker than intraspecific impacts for S. furcifera. 3. This trend was parallelled by adverse competitive effects on survival, with interspecific effects stronger than intraspecific impacts for N. lugens and intraspecific effects stronger for S. furcifera. 4. Crowding also affected the incidence of macroptery indirectly through feeding‐induced changes in plant physiology. Rearing N. lugens on plants fed on previously by heterospecifics resulted in a higher incidence of macroptery in females and protracted development than for N. lugens raised on plants fed on previously by conspecifics. By contrast, the intraspecific effect of previous feeding was stronger than the interspecific effect in S. furcifera, with higher macropter production and prolonged development occurring on plants exposed previously to conspecifics. 5. The results suggest that interspecific interactions between herbivorous insects, both direct and via feeding‐induced changes in plant physiology, can have negative consequences for performance and survival and promote the production of flight‐capable adults that can disperse.     

Brain-derived Neurotrophic Factor (BDNF) Induces Sustained Intracellular Ca2+ Elevation through the Up-regulation of Surface Transient Receptor Potential 3 (TRPC3) Channels in Rodent Microglia

Microglia are immune cells that release factors, including proinflammatory cytokines, nitric oxide (NO), and neurotrophins, following activation after disturbance in the brain. Elevation of intracellular Ca²⁺ concentration ([Ca²⁺]_i) is important for microglial functions such as the release of cytokines and NO from activated microglia. There is increasing evidence suggesting that pathophysiology of neuropsychiatric disorders is related to the inflammatory responses mediated by microglia. Brain-derived neurotrophic factor (BDNF) is a neurotrophin well known for its roles in the activation of microglia as well as in pathophysiology and/or treatment of neuropsychiatric disorders. In this study, we sought to examine the underlying mechanism of BDNF-induced sustained increase in [Ca²⁺]_i in rodent microglial cells. We observed that canonical transient receptor potential 3 (TRPC3) channels contribute to the maintenance of BDNF-induced sustained intracellular Ca²⁺ elevation. Immunocytochemical technique and flow cytometry also revealed that BDNF rapidly up-regulated the surface expression of TRPC3 channels in rodent microglial cells. In addition, pretreatment with BDNF suppressed the production of NO induced by tumor necrosis factor α (TNFα), which was prevented by co-adiministration of a selective TRPC3 inhibitor. These suggest that BDNF induces sustained intracellular Ca²⁺ elevation through the up-regulation of surface TRPC3 channels and TRPC3 channels could be important for the BDNF-induced suppression of the NO production in activated microglia. We show that TRPC3 channels could also play important roles in microglial functions, which might be important for the regulation of inflammatory responses and may also be involved in the pathophysiology and/or the treatment of neuropsychiatric disorders.     

Formation of Chlorophyll-Protein Complexes during Greening 1. Distribution of Newly Synthesized Chlorophyll among Apoproteins

The relationship between the accumulation of Chl and the apoproteinsof the light-harvesting Chl a/b-protein complex of PS II (LHCII)during the greening of cucumber cotyledons was studied. LHCIIapoproteins were not detected in etiolated cotyledons. Uponillumination, Chl a was formed as a result of photoconversionof protochlorophyllide (Pchlide) which had accumulated in thedark. During the lag period that preceded the accumulation ofChl, a small amount of LHCII apoproteins appeared. The amountof LHCII apoproteins increased with increases in levels of Chlb, though somewhat more rapidly during the first 10 h of greening.Treatment with benzyladenine (BA) or levulinic acid (LA) wasused to vary the supply of Chl a for apoproteins by promotingor inhibiting the synthesis of Chl a, respectively. LA decreasedbut BA increased the rate of accumulation of Chl b and LHCIIapoproteins. Only small amounts of Chl b and LHCII apoproteinswere formed under intermittent illumination. However, in thepresence of chloramphenicol (CAP), which inhibits the synthesisof plastome-coded proteins including apoproteins of the P700-Chla-protein complex (CP1) and a Chl a-protein complex of PS II(CPa), we observed the accumulation of Chl b and LHCII apoproteins,both of which are of nuclear origin. During incubation in thedark after intermittent exposure to light, CAP alone allowedneither destruction nor accumulation of Chl b and LHCII apoproteins,but it did enhance the effect of CaCl₂ in inducing both Chlb and these apoproteins. These results can be explained by assumingthat apoproteins of CP1 and CPa have a higher affinity for Chla than do LHCII apoproteins. When the availability of Chl ais limited, these apoproteins compete with one another for Chla, with the resultant preferential formation of CP1 and CPa.However, when the supply of Chl a becomes large enough for saturationof apoproteins of CP1 and CPa, some of the Chl a is incorporatedinto LHCII apoproteins either directly or after conversion toChl b. Thus, the formation of different Chl-protein complexes(CPs) is regulated by the relative rates of synthesis of Chla and apoproteins and by differential affinities of the apoproteinsfor Chl a. ⁴Present address: Kyowa Hakko Co., Ltd., 4041, Ami-machi, Inashiki,Ibaraki, 300-03 Japan (Received September 14, 1989; Accepted April 26, 1990)     

Russula velenovskyi new to Japan,with phylogenetic implications of Russula species between Japanese subalpine forests and Northern Europe

To compare morphological characters and phylogenetic placement between Japanese and European Russula, 32 specimens of 12 species were collected from Japanese subalpine forests and Northern Europe. Several sequences of nrDNA ITS region (ITS) of these Russula species were obtained. High homological similarities were shown between ITS sequences of several Russula samples collected from Japanese subalpine forests, Europe and North America. These facts show distribution of the same Russula species among these areas. From morphological observations and phylogenetic analyses, two same Russula species, R. velenovskyi, and R. decolorans are found in Japan, Europe and North America. Of these, R. velenovskyi collected from Mt. Fuji, Mt. Nyukasa and Mt. Tateshina in mountainous area of central Honshu is reported as a new Japanese record.     

Effects of dibutyryl cAMP and bromodeoxyuridine on expression ofN-acetylglucosaminyltransferases III and V in GOTO neuroblastoma cells

The sugar chain structures of the cell surface change dramatically during cellular differentiation. A human neuroblastoma cell line, GOTO, is known to differentiate into neuronal cells and Schwannian cell-like cells on treatments with dibutyryl cAMP and bromodeoxyuridine, respectively. We have examined the expression of UDP-N-acetylglucosamine: -d-mannoside -1,4N-acetylglucosaminyltransferase III (GnT-III: EC 2.4.1.144) and UDP-N-acetylglucosamine: -6-d-mannoside -1,6N-acetylglucosaminyltransferase V (GnT-V: EC 2.4.1.155), two major branch forming enzymes inN-glycan synthesis, in GOTO cells on two distinct directions of differentiation.In neuronal cell differentiation, GnT-III activity showed a slight increase during initial treatment with Bt₂cAMP for 4 days and decreased drastically after the fourth day, but the mRNA level of GnT-III did not show a decrease but in fact a slight increase. GnT-V activity increased to approximately two- to three-fold the initial level with increasing mRNA level after 8 days, and lectin blot analysis showed an increase in reactivity toDatsura stramonium (DSA) of the immunoprecipitated neural cell adhesion molecule (NCAM). In Schwannian cell differentiation, the activity and mRNA level of GnT-III showed no significant change on treatment with BrdU. GnT-V activity also showed no change in spite of the gradual increase in the mRNA level. These results suggest that the activation of GnT-V during neuronal cell differentiation of GOTO cells might be a specific change for branch formation in N-glycans, and this affects the sugar chain structures of some glycoproteins such as NCAM.Abbreviations and trivial names GnT N-acetylglucosaminyltransferase - Bt₂cAMP N ⁶,O ⁶-dibutyryl cAMP - BrdU bromodeoxyuridine - DSA Datsura stramonium - NCAM neural cell adhesion molecule - PAGE polyacrylamide gel electrophoresis     

Effects of fibroblasts of different origin on long term maintenance of xenotransplanted human epidermal kerationocytes in immunodeficient mice

We examined effects of fibroblasts of different origin on long-term maintenance of xenotransplanted human epidermal keratinocytes. A suspension of cultured epidermal cells, originating from adult human trunk skin, was injected into double mutant immunodeficient (BALB/c nu/scid) mice subcutaneously, with or without cultured fibroblastic cells of different origin. At one week after transplantation, the epidermal cells generated epidermoid cysts consisting of human epidermis-like tissue. When the epidermal cells were injected alone or together with fibroblastic cells derived from human bone marrow, muscle fascia, or murine dermis, organized epidermoid cysts regressed within 6 weeks. In contrast, when the epidermal cells were injected together with human dermal fibroblasts, generated epidermoid cysts were maintained in vivo for more than 24 weeks. Histological examination showed that the reorganized epidermis, after injection of both epidermal keratinocytes and dermal fibroblasts, retained normal structures of the original epidermis during 6 to 24 weeks after transplantation. The results indicate that human dermal fibroblasts facilitate the long-term maintenance of the reorganized epidermis after xenotransplantation of cultured human epidermal keratinocytes by supporting self renewal of the human epidermal tissue in vivo.     

Specific immunocytochemical localization of cathepsin E at the ruffled border membrane of active osteoclasts

The immunocytochemical localization of cathepsin E, a non-lysosomal aspartic proteinase, was investigated in rat osteoclasts using the monospecific antibody to this protein. At the light-microscopic level, the preferential immunoreactivity for cathepsin E was found at high levels in active osteoclasts in the physiological bone modeling process. Neighboring osteoblastic cells were devoid of its immunoreactivity. At the electron-microscopic level, cathepsin E was exclusively confined to the apical plasma membrane at the ruffled border of active osteoclasts and the eroded bone surface. Cathepsin E was also concentrated in some endocytotic vacuoles of various sizes in the vicinity of the ruffled border membrane, some of which appeared to be secondary lysosomes containing the phagocytosed materials. These results strongly suggest that this enzyme is involved both in the extracellular degradation of the bone organic matrix and in the intracellular breakdown of the ingested substances in osteoclasts.     

Primary human immunodeficiency virus type 1 viremia and central nervous system invasion in a novel hu-PBL-immunodeficient mouse strain.

We established four new mouse strains with defective T and B cells as well as defects in innate immunological reactions using an NK cell depletion antibody and showed that all mutant mouse strains efficiently received human peripheral blood leukocyte (PBL) engraftment (hu-PBL-scid mice). Higher levels of human immunodeficiency virus type 1 (HIV-1) replication were observed in these new hu-PBL-scid mice than in conventional hu-PBL-C.B-17-scid mice. In one particular strain, hu-PBL-NOD-scid mice, high levels of HIV-1 viremia (more than 10(6) 50% infectious doses per ml) were detected after infection with HIV-1. The plasma viral load was about 100 to 1,000 times higher than that observed in other hu-PBL-scid mice infected with HIV-1. Although high-level viremia did not correlate with the total amount of HIV-1 RNA in cells from infected mice, high levels of free virions were detected only in hu-PBL-NOD-scid mice. HIV-1 viremia induced systemic HIV-1 infection involving the liver, lungs, and brain. PCR in situ hybridization confirmed that HIV-1-infected cells invaded the brain tissue of the hu-PBL-NOD-scid mice. Our results suggest that the genetic background, including innate immunity, is critical in the development of primary HIV-1 viremia and subsequent central nervous system invasion with HIV-1. The hu-PBL-NOD-scid mouse represents a useful model for the study of the pathogenesis of HIV-1 in vivo, especially brain involvement, and therapy of primary HIV-1 viremia.     

Imaging of intracellular Ca waves induced by muscarinic receptor stimulation in rat parotid acinar cells

Changes in cytosolic Ca²⁺ concentration ([Ca²⁺]_i) following muscarinic receptor stimulation were studied with digital imaging microscopy in small clusters of Fura-2 loaded rat parotid acinar cells. In the absence of extracellular Ca²⁺, the increase in [Ca²⁺]_i evoked by a high concentration (10 IM) of carbachol (CCh) was initiated in the apical pole of the acinar cells about 0.4 s after stimulation and then rapidly spread as a Ca²⁺ wave toward the basolateral region. The [Ca²⁺]_i reached the maximum high level throughout the cells 1–2 s after stimulation. As Ca²⁺ was eliminated from the extracellular medium, the Ca²⁺ wave was a result of Ca²⁺ release from intracellular stores. The magnitude and velocity of the Ca²⁺ wave decreased with decreasing concentration of CCh, and the increase in [Ca²⁺]_i induced by low CCh concentrations (≤ 0.5 μM) was always larger in the apical region of acinar cells than in the basal region. The Ca²⁺ wave was also observed in isolated single acinar cells, indicating that the maintenance of acinar structure is not essential for the development of the Ca²⁺ wave. Thapsigargin (ThG), an inhibitor of the endoplasmic reticulum Ca²⁺ pump, caused a slow and homogeneous increase in [Ca²⁺]_i throughout the cells. Addition of ThG after CCh, or addition of CCh after ThG, did not stimulate further increases in [Ca²⁺]_i suggesting that the inositol-1,4,5-trisphosphate (InsP₃) and ThG-sensitive Ca²⁺ stores overlap in parotid acinar cells. The present study supports the hypothesis that formation of InsP₃ is essential to trigger the Ca²⁺ wave and that the development of the Ca²⁺ wave may be attributed to regional differences in InsP₃ sensitivity of Ca²⁺ stores. The agonist-induced Ca²⁺ wave is probably a general phenomenon in exocrine acinar cells.