Rhythmic firing activity of median neurosecretory cells of the subesophageal ganglion and its coordination with periodically occurring abdominal movements in the tenebrionid [corrected] beetle, Zophobas atratus [corrected

An immunocytochemical study using an FXPRLamide antiserum revealed three clusters of neurosecretory cells along the midline of the subesophageal ganglion of the tenebrionid [corrected] beetle, Zophobas atratus [corrected] Firing activity of five pairs of neurosecretory cells in the mandibular and maxillary clusters was recorded from an axonal tract of the cells throughout the entire pupal period. The population of neurosecretory cells became active during the middle and late pupal periods, and they usually discharged clusters of action potentials at an interval of 30-90 min. The ultradian activity rhythm of the cells in Z. atratus [corrected] was related to a periodic discharge of electrical activity in developing flight muscles, as has been observed in the homologous cells in the silkmoth, Bombyx mori. Furthermore, the rhythmic activity of the neurosecretory cells in the mealworm was closely synchronized with periodically occurring rhythmic abdominal movements that caused extracardiac hemocoelic pulsations, which facilitate hemolymph circulation and exchange of respiratory gases. The results suggest that the secretory products of the neurosecretory cells may activate and/or orchestrate physiological mechanisms supporting morphogenesis during metamorphosis.     

Identification of phosphoproteins associated with maintenance of transformed state in temperature-sensitive Rous sarcoma-virus infected cells by proteomic analysis

To identify phosphotyrosine-containing proteins essential for maintaining the transformed state, we studied the tyrosine phosphorylation profile of temperature-sensitive mutant of Rous sarcoma virus, tsNY68, infected cells (68N7). Shifting the temperature from 39 degrees C (nonpermissive) to 32 degrees C (permissive) markedly increased the expression of phosphotyrosine-containing cell membrane proteins of approximately 40kDa, as assessed by SDS-PAGE. Membrane and nuclear proteins were separated by two-dimensional gel electrophoresis and immunoblotted with anti-phosphotyrosine antibody. Proteins showing temperature-dependent changes in phosphorylation profile were subjected to in-gel digestion with trypsin and analyzed by mass spectrometry. Five proteins were identified: heterogeneous nuclear ribonucleoprotein (hnRNP) A3, hnRNP A2, annexin II, phosphoglycerate mutase 1, and triosephosphate isomerase 1. hnRNP A3 was phosphorylated at serine residues and had both serine and tyrosine phosphorylated sites. These results suggest an important complementary role for proteomics in identifying molecular abnormalities associated with tumor progression that may be attractive candidates for tumor diagnosis.     

Synergistic activation of NF-kappaB by nontypeable H. influenzae and S. pneumoniae is mediated by CK2, IKKbeta-IkappaBalpha, and p38 MAPK

In review of the past studies on NF-kappaB regulation, most of them have focused on investigating how NF-kappaB is activated by a single inducer at a time. Given the fact that, in mixed bacterial infections in vivo, multiple inflammation inducers, including both nontypeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae, are present simultaneously, a key issue that has yet to be addressed is whether NTHi and S. pneumoniae simultaneously activate NF-kappaB and the subsequent inflammatory response in a synergistic manner. Here, we show that NTHi and S. pneumoniae synergistically induce NF-kappaB-dependent inflammatory response via activation of multiple signaling pathways in vitro and in vivo. The classical IKKbeta-IkappaBalpha and p38 MAPK pathways are involved in synergistic activation of NF-kappaB via two distinct mechanisms, p65 nuclear translocation-dependent and -independent mechanisms. Moreover, casein kinase 2 (CK2) is involved in synergistic induction of NF-kappaB via a mechanism dependent on phosphorylation of p65 at both Ser536 and Ser276 sites. These studies bring new insights into the molecular mechanisms underlying the NF-kappaB-dependent inflammatory response in polymicrobial infections and may lead to development of novel therapeutic strategies for modulating inflammation in mixed infections for patients with otitis media and chronic obstructive pulmonary diseases.     

Symbiotic Bacteria Associated with Stomach Discs of Human Lice

The symbiotic bacteria associated with the stomach disc, a large aggregate of bacteriocytes on the ventral side of the midgut, of human body and head lice were characterized. Molecular phylogenetic analysis of 16S rRNA gene sequences showed that the symbionts formed a distinct and well-defined clade in the Gammaproteobacteria. The sequences exhibited AT-biased nucleotide composition and accelerated molecular evolution. In situ hybridization revealed that in nymphs and adult males, the symbiont was localized in the stomach disc, while in adult females, the symbiont was not in the stomach disc but in the lateral oviducts and the posterior pole of the oocytes due to female-specific symbiont migration. We propose the designation “Candidatus Riesia pediculicola” for the louse symbionts.     

Regulation of IL-27p28 gene by lipopolysaccharide in dendritic DC2.4 cells

To elucidate the regulation of IL-27p28 gene, we analyzed the promoter region of the gene in DC2.4 cells with or without lipopolysaccharide (LPS)-treatment. The results indicate that a region (-648 to -364) of p28 promoter was responsible for LPS-induction. EMSA with DNA probes within the region reveals that binding of GATA motif bound proteins was decreased by LPS-treatment. We identified one of the proteins as non-POU domain-containing octamer binding protein (NonO). Taken together, LPS-induced activation of IL-27p28 gene can be accounted for by the displacement of bound NonO protein from the IL-27p28 promoter.     

Stable knock-down of vomeronasal receptor genes in transgenic Xenopus tadpoles

Xenopus V2R (xV2R), a family of G-protein-coupled receptors with seven transmembrane domains, is expressed in the Xenopus vomeronasal organ (VNO). There are six subgroups of xV2R, one of which, xV2RE, is predominantly expressed in the VNO. To understand the function of xV2R during VNO development, we developed a new method to achieve stable siRNA-suppression of the V2RE genes by introducing siRNA expression transgenes into the genomes of unfertilized eggs. We found that some of the derived transgenic tadpoles lacked VNOs and that their olfactory epithelium was fused. With the exception of one tadpole, expression of xV2RE was not detected in morphologically abnormal mutant tadpoles, although the olfactory marker protein and the olfactory receptors were expressed. These results suggest that we successfully produced transgenic tadpoles in which xV2RE expression was stably suppressed by siRNA, and that xV2RE plays a role in the morphogenesis of olfactory organs.     

Ars insulator identified in sea urchin possesses an activity to ensure the transgene expression in mouse cells

Sea urchin arylsulfatase (Ars) gene locus has features of an insulator, i.e., blocking of enhancer and promoter interaction, and protection of a transgene against positional effects [Akasaka et al. (1999) Cell. Mol. Biol. 45, 555-565]. To examine the effect of Ars insulator on long-term expression of a transgene, the insulator was inserted into LTR of retrovirus vector harboring hrGFP gene as a reporter, and then introduced into mouse myoblast cells. The isolated clones transduced with the reporter gene with or without Ars insulator were cultured for more than 20 wk in the absence of a selection reagent, and the expression of hrGFP was periodically determined. Expression of hrGFP in four clones transduced with the reporter gene without Ars insulator was completely silenced after 20 wk of culture. On the other hand, hrGFP was expressed in all clones with Ars insulator inserted in one of the two different orientations. Histone H3 deacetylation and DNA methylation of the 5'LTR promoter region, signs for heterochromatin and silencing, were suppressed in the clones that were expressing hrGFP. Ars insulator is effective in maintaining a transgene in mouse cells in an orientation-dependent manner, and will be a useful tool to ensure stable expression of a transgene.     

Disruption of phospholipase Cdelta4 gene modulates the liver regeneration in cooperation with nuclear protein kinase C

Phospholipase Cdelta4 (PLC delta4) gene has been cloned from the cDNA library of regenerating rat liver. Using PLC delta4 gene-disrupted mice (PLC delta4(-/-)), we studied a role of PLC delta4 during liver regeneration after partial hepatectomy (PH). In PLC delta4(-/-), liver regeneration occurred in an apparently normal way. However, BrdU-indices indicated that PLC delta4 gene disruption delayed the onset of DNA synthesis by 2 h. Noticeably, the BrdU-indices in PLC delta4(+/+) remained rather constant throughout S phase, 25-35%, whereas in PLC delta4(-/-), it fluctuated drastically from 25% at 34 h to 65% at late S, 42 h after PH. This fact showed that PLC delta4 gene disruption caused a higher synchronization of cell proliferation. The mRNA for PLC delta4 in PLC delta4(+/+) appeared at late G1, and the expression continued throughout S phase. PLC activity increased transiently in chromatin at the late G1 and S phases in only PLC delta4(+/+), but not in PLC delta4(-/-). The specific increases in PLC activity well correlated with the transient increases of protein kinase C (PKC) alpha in chromatin of PLC delta4(+/+). PKC epsilon also increased transiently in chromatin from PLC delta4(+/+) at late S. It is concluded that PLC delta4 regulates the liver regeneration in cooperation with nuclear PKC alpha and epsilon.