Extracellular ATP activates Ca2(+)-dependent K+ conductance via Ca2+ influx in mouse macrophages

1. Using the perforated patch recording, the effects of ATP on membrane current were investigated in mouse peritoneal macrophages. 2. Extracellularly applied ATP induced a biphasic current consisting of a initial inward current [Ii(ATP)] followed by an outward current [Io(ATP)]. These currents were associated with a marked increase in conductance at their peaks. 3. Ii(ATP) reversed close to 0 mV and was attenuated by removal of external Na+. 4. Io(ATP) reversed near -80 mV and was increased by decreasing the external concentration of K+. 5. Io(ATP) was completely abolished by removal of external Ca2+, treatment with an intracellular Ca2+ chelator, the acetoxymethyl ester of 1,2-bis (2-aminophenoxy) ethane-N,N,N',N'-tetra acetic acid (BAPTA-AM) and bath applied quinidine but not tetraethylammonium (TEA) or apamin. 6. These results suggest that Ii(ATP) and Io(ATP) are due to an activation of nonspecific cationic and Ca2(+)-dependent K+ conductances, respectively, and raise the possibility that the putative ATP receptor may be important in regulating macrophage functions, motility, phagocytosis and cytokines secretion.     

Reproductive conflict between laying workers in the ant Aphaenogaster senilis

Since workers of the ant Aphaenogaster senilis can lay male eggs, reproductive conflict may occur between these workers. We examined the occurrence of worker conflicts in groups of workers either with or without the queen. Intranidal aggression was observed in each nest for 10 min each day, and the immatures produced were counted once a week for two months. Pairs of workers involved in aggression were taken regularly from each nest and used for chemical, morphological and anatomical analyses. The attacker and the attacked workers differed in their cuticular hydrocarbon profiles. The attacker and the attacked ants were at the same middle-aged fertile stage. The attacker ant was significantly larger and more fertile than the attacked ant, and more mature physiologically (poison gland was darker). There was apparently no stable hierarchy between laying workers. In the first weeks under queenless conditions, most eggs and larvae were destroyed, but they were later reared to obtain males. The intranidal worker aggression in this highly evolved ant is discussed in relation to dominance and worker policing. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Uptake of juvenile hormone esterase by pericardial cells of Manduca sexta

Immunohistochemical studies were conducted to determine tissue(s) which might be involved in the uptake of juvenile hormone esterase (JHE) from larval hemolymph. Purified JHE expressed by a recombinant baculovirus carrying the JHE gene from Heliothis virescens was injected into the hemolymph of second stadium larvae of Manduca sexta. Immunoreactive material detected with specific antibodies against the natural JHE purified by affinity chromatography from the hemolymph of H. virescens was localized only in the dorsal regions of whole larval mounts. Further immunohistochemical studies of whole and dissected larvae at the light and electron microscopic level showed the specific localization of JHE in pericardial cells. Western blot analysis confirmed the localization of injected JHE in pericardial cells and also indicated some apparent degradation of the incorporated JHE. Similar results were obtained with the JHE from H. virescens injected into larvae of H. virescens. These results indicate that pericardial cells are involved in the uptake of injected JHE from insect hemolymph and its degradation.     

Ultrastructure of the parathyroid gland of the japanese lizard in the spring and summer season

The ultrastructure of the parathyroid glands of adult Japanese lizards (Takydromus tachydromoides) in the spring and summer season was examined. The parenchyma of the gland consists of chief cells arranged in cords or solid masses. Many chief cells contain numerous free ribosomes and mitochondria, well-developed Golgi complexes, a few lysosome-like bodies, some multivesicular bodies and relatively numerous lipid droplets. The endoplasmic reticulum is mainly smooth-surfaced. Cisternae of the rough endoplasmic reticulum are distributed randomly in the cytoplasm. Small coated vesicles of 700-800 Å in diameter are found occasionally in the cytoplasm, especially in the Golgi region. The chief cells contain occasional secretory granules of 150-300 nm in diameter that are distributed randomly in the cytoplasm and lie close to the plasma membrane. Electron dense material similar to the contents of the secretory granules is observed in the enlarged intercellular space. These findings suggest that the secretory granules may be discharged into the intercellular space by an eruptocrine type of secretion. Coated vesicles (invaginations) connected to the plasma membrane and smooth vesicles arranged in a row near the plasma membrane are observed. It is suggested that such coated vesicles may take up extracellular proteins. The accumulation of microfilaments is sometimes recognized. Morphological evidence of synthetic and secretory activities in the chief cells suggests active parathyroid function in the Japanese lizard during the spring and summer season.     

Combined Effects of Multiple cis-Acting Elements in Elicitor-Mediated Activation of PSCHS1 Gene

Promoter of a gene encoding chalcone synthase 1 (PSCHS1), amember of the defense-related genes in pea, was analyzed bytransient transfection assay. The results demonstrated thatin addition to the previously identified AT-rich sequences,at least four distinct cis-acting elements were required formaximal fungal elicitor-mediated activation of PSCHS1. ²Present address: Hikone Reserch Laboratories, Maruho Co. Ltd.,2763, Takamiya-cho, Hikone, Shiga, 522-02 Japan.     

Two Suppressors, Supprescins A and B, Secreted by a Pea Pathogen, Mycosphaerella pinodes

Two mucin-type glycopeptides that suppressed the productionof pisatin, a phytoalexin of pea, were purified from a pea pathogen,Mycosphaerella pinodes. The structures of Supprescin A (Mr,452) and Supprescin B (Mr, 959) were determined by an analysisof amino acid sequences and ¹³C- and ¹H-NMR. (Received April 22, 1992; Accepted June 16, 1992)     

Mutagenicity of bisphenol A and its suppression by interferon-α in human RSa cells

Bisphenol A is used as a monomer in the production of polycarbonate plastic products. The widespread use of bisphenol A has raised concerns about its effects in humans. Since there is little information on the mutagenic potential of the chemical, the mutagenicity of bisphenol A was tested using human RSa cells, which has been utilized for identification of novel mutagens. In genomic DNA from cells treated with bisphenol A at concentrations ranging from 1×10⁻⁷ to 1×10⁻⁵ M, base substitution mutations at K-ras codon 12 were detected using PCR and differential dot-blot hybridization with mutant probes. Mutations were also detected using the method of peptide nucleic acid (PNA)-mediated PCR clamping. The latter method enabled us to detect the mutation in bisphenol A-treated cells at a dose (1×10⁻⁸ M) equivalent to that typically found in the environment. Induction of ouabain-resistant (Oua^R) phenotypic mutation was also found in cells treated with 1×10⁻⁷ and 1×10⁻⁵ M of bisphenol A. The induction of K-ras codon 12 mutations and Oua^R mutations was suppressed by pretreating RSa cells with human interferon (HuIFN)-α prior to bisphenol A treatment. The cells treated with bisphenol A at the concentration of 1×10⁻⁶ M elicited unscheduled DNA synthesis (UDS). These findings suggested that bisphenol A has mutagenicity in RSa cells as well as mutagens that have been tested in these cells, and furthermore, that a combination of the PNA-mediated PCR clamping method with the human RSa cell line may be used as an assay system for screening the mutagenic chemicals at very low doses.     

Interaction between Cell Wall and Plasma Membrane via RGD Motif is Implicated in Plant Defense Responses

Integrin- and vitronectin-like proteins were found to existin the pea plasma membrane and cell wall, respectively. Thehexapeptide GRGDSP but not GRGESP inhibited either the bindingof cell wall protein(s) to plasma membrane protein(s) or thedefense response. A possible role of linkage via RGD motif inplant defenses is discussed. (Received April 20, 1998; Accepted September 1, 1998)     

A Flow Cytometric Assay Reveals a Suppression of Phagocytosis by Rabbit Defensin NP-3A in Mouse Peritoneal Macrophages

Phagocytosis of fluorescein isothiocyanate (FITC)-labeled polystyrene microparticles by peritonea] macrophages from thioglycollate-elicited mice was examined by means of flow cytometry (FCM). This assay revealed that rabbit defensin NP-3A suppressed the phagocytosis in a dose-dependent manner. The present results suggest that NP-3A released from neutrophils is one of the mediators which modulates the activity of macrophages in response to infection.