Apogamous sporophyte formation in a fernPteris multifida and its characteristics

When spores of the fern,Pteris multifida, were aseptically cultured in the dark, sporophytic plants were apogamously induced. The plants have been subsequently grown in pots until the development of leaves with many sporangia for observations of meiotic characteristics in their sporocytes. The sporophytic plants originated from spores were estimated to be haploid, and the estimation was supported by abnormal meiosis in sporocytes and the absence of mature spores, but some chromosomes (n=58) formed bivalents in the meiotic process.     

Seasonal changes in the biomass of floating leaved plant,Trapa spp., and its relation with a leaf beetle,Galerucella nipponensis,in Lake Inba,Japan

Limnology - Trapa spp. dominate many shallow eutrophic lakes in Japan, which must affect the nutrient dynamics in lakes. Trapa spp. are utilized by several animals, in particular the leaf beetle,...     

Identification of important bases for the self-cleavage activity at two single-stranded regions of genomic HDV ribozyme.

In order to determine important bases at two single-stranded regions [SSrA (726-731 nt) and SSrB (762-766)] derived mainly from secondary structure models in genomic hepatitis delta virus (HDV) ribozyme possessing self-cleavage activity, we have constructed several point mutants at these two regions on the HDV88 molecule (683-770). Among the bases at SSrA and SSrB regions C763 was found to play an essential role during self-cleavage process since substitutions to any other bases viz. A or G or U completely abolished the activity.     

Dissection of the role of macrophages in triggering T lymphocytes for interleukin 2 production by monoclonal antibody OKT3

Unfractionated human peripheral blood mononuclear cells produce a small amount of interleukin 2 (IL 2) by stimulation with a monoclonal anti-T3 antibody (OKT3) in vitro. The IL 2 production could be greatly augmented by the addition of a phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). In the presence of TPA, the T cell enriched fraction deprived of macrophages did not produce IL 2, but the T cells pulse-incubated with OKT3 and reconstituted with macrophages efficiently produced IL 2 in subsequent culture in the presence of TPA as did T cells reconstituted with OKT3-pulse-incubated macrophages. The stimulating effect of OKT3 in the presence of macrophages was inhibited dose-dependently by the addition of immunoglobulins, particularly by mouse IgG2a which is the same isotype as that of the OKT3 antibody, showing that it inhibits by blocking the binding of OKT3 to Fc receptors on macrophages. The same extent of IL 2 production was induced in T cells when paraformaldehyde-fixed macrophages were substituted for intact macrophages. Remarkable IL 2 production was also induced by OKT3 when latex beads coated with rabbit anti-mouse IgG2a antibody and TPA were added to the culture. It was confirmed that the production induced by these stimulations was due to an increase of IL 2 mRNA. These results show that effective signals for IL 2 production are generated by efficient crosslinking of T3 molecules which results from multi-interaction of T3 molecules on the T cell membrane and anti-T3 antibody molecules on macrophage membrane or on the surface of the latex particle.     

Characterization by [3H]Dihydroergocryptine Binding of Alpha-Adrenergic Receptors in Neuroblastoma × Glioma Hybrid Cells

[3H]Dihydroergocryptine ([3H]DHE) was shown to bind to sites in membranes from neuroblastoma X glioma hybrid cells (NG 108-15) that had the characteristics expected of alpha-adrenergic receptors. The binding was saturable with 0.3 pmol [3H]DHE bound per mg of protein and of high affinity, with an apparent dissociation constant (KD) of 1.8 nM. The specificity of the binding site for various ligands was more similar to that of alpha 2 receptors than to that of alpha 1. No specific binding of [3H]WB-4101 was found in the membranes derived from NG 108 cells. This finding also indicated that the [3H]DHE binding site in the cell is the alpha 2 receptor. GTP lowered the affinity of agonists for the [3H]DHE binding site, although the nucleotide hardly affected the affinity of antagonists including [3H]DHE.     

Immunolocalization of β-1-4-galactan and its relationship with lignin distribution in developing compression wood of Cryptomeria japonica

Compression wood (CW) contains higher quantities of β-1-4-galactan than does normal wood (NW). However, the physiological roles and ultrastructural distribution of β-1-4-galactan during CW formation are still not well understood. The present work investigated deposition of β-1-4-galactan in differentiating tracheids of Cryptomeria japonica during CW formation using an immunological probe (LM5) combined with immunomicroscopy. Our immunolabeling studies clearly showed that differences in the distribution of β-1-4-galactan between NW (and opposite wood, OW) and CW are initiated during the formation of the S₁ layer. At this stage, CW was strongly labeled in the S₁ layer, whereas no label was observed in the S₁ layer of NW and OW. Immunogold labeling showed that β-1-4-galactan in the S₁ layer of CW tracheids significantly decreased during the formation of the S₂ layer. Most β-1-4-galactan labeling was present in the outer S₂ region in mature CW tracheids, and was absent in the inner S₂ layer that contained helical cavities in the cell wall. In addition, delignified CW tracheids showed significantly more labeling of β-1-4-galactan in the secondary cell wall, suggesting that lignin is likely to mask β-1-4-galactan epitopes. The study clearly showed that β-1-4-galactan in CW was mainly deposited in the outer portion of the secondary cell wall, indicating that its distribution may be spatially consistent with lignin distribution in CW tracheids of Cryptomeria japonica.     

Spinal Cord Stimulation Exerts Neuroprotective Effects against Experimental Parkinson’s Disease

In clinical practice, deep brain stimulation (DBS) is effective for treatment of motor symptoms in Parkinson’s disease (PD). However, the mechanisms have not been understood completely. There are some reports that electrical stimulation exerts neuroprotective effects on the central nervous system diseases including cerebral ischemia, head trauma, epilepsy and PD, although there are a few reports on neuroprotective effects of spinal cord stimulation (SCS). We investigated the neuroprotective effects of high cervical SCS on PD model of rats. Adult female Sprague-Dawley rats received hour-long SCS (2, 50 or 200 Hz) with an epidural electrode at C1–2 level for 16 consecutive days. At 2 days after initial SCS, 6-hydroxydopamine (6-OHDA) was injected into the right striatum of rats. Behavioral evaluations of PD symptoms were employed, including cylinder test and amphetamine-induced rotation test performed at 1 and 2 weeks after 6-OHDA injection. Animals were subsequently euthanized for immunohistochemical investigations. In order to explore neurotrophic and growth factor upregulation induced by SCS, another cohort of rats that received 50 Hz SCS was euthanized at 1 and 2 weeks after lesion for protein assays. Behavioral tests revealed that the number of amphetamine-induced rotations decreased in SCS groups. Immunohistochemically, tyrosine hydroxylase (TH)-positive fibers in the striatum were significantly preserved in SCS groups. TH-positive neurons in the substantia nigra pars compacta were significantly preserved in 50 Hz SCS group. The level of vascular endothelial growth factor (VEGF) was upregulated by SCS at 1 week after the lesion. These results suggest that high cervical SCS exerts neuroprotection in PD model of rats, at least partially by upregulation of VEGF. SCS is supposed to suppress or delay PD progression and might become a less invasive option for PD patients, although further preclinical and clinical investigations are needed to confirm the effectiveness and safety.     

Amyloid β-Mediated Zn2+ Influx into Dentate Granule Cells Transiently Induces a Short-Term Cognitive Deficit

We examined an idea that short-term cognition is transiently affected by a state of confusion in Zn²⁺ transport system due to a local increase in amyloid-β (Aβ) concentration. A single injection of Aβ (25 pmol) into the dentate gyrus affected dentate gyrus long-term potentiation (LTP) 1 h after the injection, but not 4 h after the injection. Simultaneously, 1-h memory of object recognition was affected when the training was performed 1 h after the injection, but not 4 h after the injection. Aβ-mediated impairments of LTP and memory were rescued in the presence of zinc chelators, suggesting that Zn²⁺ is involved in Aβ action. When Aβ was injected into the dentate gyrus, intracellular Zn²⁺ levels were increased only in the injected area in the dentate gyrus, suggesting that Aβ induces the influx of Zn²⁺ into cells in the injected area. When Aβ was added to hippocampal slices, Aβ did not increase intracellular Zn²⁺ levels in the dentate granule cell layer in ACSF without Zn²⁺, but in ACSF containing Zn²⁺. The increase in intracellular Zn²⁺ levels was inhibited in the presence of CaEDTA, an extracellular zinc chelator, but not in the presence of CNQX, an AMPA receptor antagonist. The present study indicates that Aβ-mediated Zn²⁺ influx into dentate granule cells, which may occur without AMPA receptor activation, transiently induces a short-term cognitive deficit. Extracellular Zn²⁺ may play a key role for transiently Aβ-induced cognition deficits.     

Calcitonin gene-related peptide and substance P in the pharynx and lung of the bullfrog,Rana catesbeiana

Indirect double immunofluorescence labelling in the pharynx and lung of the bullfrog, Rana catesbeiana, demonstrated the occurrence, distribution, and coexistence of two neuropeptides. In the pharynx, immunoreactive calcitonin gene-related peptide (CGRP) and substance P (SP) were localized in nerve fibers distributed within and just beneath the ciliated epithelium. In the lung, CGRP and SP were localized in nerve fibers in five principal locations: 1) within the smooth muscle layer in the interfaveolar septa; 2) in the luminal thickened edges of the septa; 3) around the pulmonary vasculature; 4) within, and 5) under the ciliated epithelium. Within the smooth muscle layer in the septa, luminal thickened septa, and around blood vessels, almost all fibers showed coexistence of CGRP and SP. Within and just beneath the ciliated epithelium in the thickened septa, all fibers showed coexistence of CGRP and SP. No immunoreactivity for vasoactive intestinal polypeptide, neuropeptide Y, galanin, somatostatin, FMRFamide, and leucine-and methionine-enkephalins was detected in the nerve fibers within the larynx and the lung. Together with our previous data, the present findings suggest that peptidergic mechanisms are involved in the regulation of amphibian respiratory systems throughout their life.