Effects of prostaglandins E2, I2 and F2α, arachidonic acid and indomethacin on pressor responses to norepinephrine in conscious rats

The effects of prostaglandins E₂ (PGE₂), I₂ (PGI₂) and F₂α (PGF₂α), arachidonic acid and indomethacin on pressor responses to norepinephrine were examined in conscious rats. Intravenously infused PGE₂ (0.3, 1.25 μg/kg/min), PGI₂ (50, 100 ng/kg/min), PGF₂α (1.8, 5.4 μg/kg/min) and arachidonic acid (0.7, 1.4 mg/kg/min) did not change the basal blood pressure. Both PGE₂ and PGI₂ significantly attenuated pressor responses to norepinephrine, whereas PGF₂α significantly potentiated them. Arachidonic acid, a precursor of the prostaglandins (PGs), significantly attenuated pressor responses to norepinephrine. Since the attenuating effect of arachidonic acid was completely abolished by the pretreatment with indomethacin (5 mg/kg), arachidonic acid is thought to exert an effect through its conversion to PGs. On the contrary, intravenously injected indomethacin (0.2–5.0 mg/kg) facilitated pressor responses to norepinephrine in a dose-related manner without any direct effect on the basal blood pressure. These results suggest that endogenous PGs may participate in the regulation of blood pressure by modulating pressor responses to norepinephrine in conscious rats.     

Contribution of the T cell receptor BJ gene to recognition of the P91A tumor antigen in DBA/2 mice

 To understand specific immune responses against a tumor, it is important to characterize T cells that recognize the tumor antigen. The mouse P91A antigen is one of the well-defined tumor antigens that is expressed on the P911 cell line, and T cells responding to the antigen in DBA/2 mice were reported to be restricted to BV8S2/S3 families in their T cell receptor (TCR) BV gene usage. We have further characterized the P91A-responding T cells in DBA/2 mice, focusing on TCR BJ gene usage and using the polymerase chain reaction/enzyme-linked immunosorbent assay and DNA sequencing studies of their third complementarity-determining (CDR3) regions. As a result, T cells with cytotoxic activity to the P91A antigen, induced from murine spleen cells both in vivo and in vitro, showed predominant use of the BJ2S1 gene segment in both BV8S2 and BV8S3 T cells compared to unmanipulated murine spleen cells. Sequencing studies of the CDR3 regions in the BV8S3 T cells revealed clonal expansion of T cells with the BV8S3-BJ2S1 combination in two of three DBA/2 mice tested. In the remaining mouse, clonal expansion was not detected despite predominant use of the BJ2S1 segment by these T cells. These data suggest that P91A-recognizing T cells would predominantly use the BV8S2/S3-BJ2S1 combination. Analysis of T cells with these TCR BV-BJ gene combinations may contribute to the evaluation, monitoring and development of a T-cell-mediated immunotherapeutic strategy. Received: 3 July 1997 / Accepted: 17 November 1997     

Inhibition of ATPase Activity in Pea Plasma Membranes by Fungal Suppressors from Mycosphaerella pinodes and Their Peptide Moieties

The effects of two suppressors of the defense reactions of hostplants, which had been purified from the pea pathogen Mycosphaerellapinodes, as well as the effects of peptide moieties, on theATPase activity in pea plasma membranes were examined in vitro.One of the suppressors, Supprescin B, inhibited the ATPase activityin a non-competitive manner, but the other suppressor, SupprescinA, did not. Supprescin A was observed to reduce the inhibitoryeffect of Supprescin B. A tripeptide, Ser-Ser-Gly, and a hexapeptide,Ser-Ser-Gly-Asp-Glu-Thr, which were the respective peptide moietiesof Supprescin A and B, inhibited the ATPase activity in a competitivemanner. Supprescin B and fragments of the hexapeptide, suchas Asp-Glu-Thr and Gly- Asp-Glu, inhibited not only the ATPaseactivity but also the acid phosphatase activity of plasma membranesin vitro. These results indicate that the acidic amino-acidresidues of the "Asp-Glu" moiety seem to act as inhibitors ofthe phosphatase activity. Thus, the peptide moiety of SupprescinB consists of at least two functional elements. (Received October 23, 1992; Accepted January 18, 1993)     

Characterization of Intravacuolar Pigmented Structures in Anthocyanin-Containing Cells of Sweet Potato Suspension Cultures

Intravacuolar pigmented structures occurred in anthocyanin-producingcultured cells of sweet potato (Ipomoea batatas) were characterized.Formation of the pigmented structures in sweet potato cellswas induced by transfer of callus cultured in 2,4-D containingagar medium into 2,4-D free liquid medium under continuous illumination.These structures were found in the vacuoles. The pigmented structureswere isolated from the protoplasts by precipitation in 60% (w/w)sucrose after centrifugation. Electron microscopic observationsof the anthocyanin-containing cultured cells showed these structureshad neither membrane boundary nor internal structures, and werefound as strongly osmiophilic globules in vacuoles. Numeroussmall osmiophilic globules were observed in central vacuolesat the early stage of anthocyanin accumulation, but not foundin cytoplasm. Similar pigmented structures in vacuoles werealso formed by treatment with neutral red. These observationsindicate that these pigmented structure is the high densityand insoluble globules highly concentrated with anthocyanin,which was synthesized in cytoplasm and transported to the centralvacuoles. ⁴Present address: Department of Cell Biology, National Institutefor Basic Biology Myodaijicho, Okazaki, 444 Japan     

Redescription of a rare callionymid fish,Paradiplogrammus corallinus,from Hawaii and Japan

Paradiplogrammus corallinus (Gilbert) has been represented by only two female specimens collected from the Hawaiian Islands. The species is redescribed on the basis of male and female specimens from the Hawaiian Islands and Hachijo-jima, Izu Islands, Japan. This species is unique amongParadiplogrammus in having a pair of supraorbital cirri.     

Scatchard analysis of EGF receptor and effects of EGF on growth and TA-4 production of newly established uterine cervical cancer cell line (OMC-1)

Effects of epidermal growth factor (EGF) on growth and tumor antigen-4 (TA-4) production of newly established uterine cervical cancer cell line (OMC-1) are reported. OMC -1 was established from a metastatic lesion of Virchow's lymph node of a large cell non-keratinizing squamous cell carcinoma of the uterine cervix and successively subcultured for about 4 years. Scatchard analysis of EGF binding to OMC-1 cells indicated a single class of binding sites with a dissociation constant (Kd) of 360 pM. The theoretical maximum number of binding sites was 2.4 x 10(4) sites/cell. The growth of OMC-1 cells was stimulated by EGF at 0.01-0.1 nM and inhibited at higher concentrations. The TA-4 production of OMC-1 cells was slightly stimulated by EGF at 0.01-1 nM and significantly stimulated at 10 nM. OMC-1 may serve as one of the available model systems for studies of regulation of proliferation and tumor marker production by EGF, particularly in cervical squamous cell carcinomas.     

Resolution of liver cirrhosis using vitamin A-coupled liposomes to deliver siRNA against a collagen-specific chaperone

There are currently no approved antifibrotic therapies for liver cirrhosis. We used vitamin A-coupled liposomes to deliver small interfering RNA (siRNA) against gp46, the rat homolog of human heat shock protein 47, to hepatic stellate cells. Our approach exploits the key roles of these cells in both fibrogenesis as well as uptake and storage of vitamin A. Five treatments with the siRNA-bearing vitamin A-coupled liposomes almost completely resolved liver fibrosis and prolonged survival in rats with otherwise lethal dimethylnitrosamine-induced liver cirrhosis in a dose- and duration-dependent manner. Rescue was not related to off-target effects or associated with recruitment of innate immunity. Receptor-specific siRNA delivery was similarly effective in suppressing collagen secretion and treating fibrosis induced by CCl(4) or bile duct ligation. The efficacy of the approach using both acute and chronic models of liver fibrosis suggests its therapeutic potential for reversing human liver cirrhosis.     

<Emphasis Type="Italic">Dipturus wuhanlingi</Emphasis>, a new species of skates (Elasmobranchii: Rajidae) from China

Dipturus wuhanlingi, a new rajid species, is described from an immature male and female collected from the southern East China Sea and off Haimen, Shantou, in the South China Sea, respectively. The specimens conform to the genus Dipturus in having the combination of the following characters: a long rostral cartilage (length more than 60% of dorsal head length), greatly depressed and laterally expanded mesocondyle, and a total length greater than 55 cm when adult. Dipturus wuhanlingi is distinct from all other Dipturus species in the following combination of characters: a pair of scapular thorns, three or four nuchal thorns, an irregular row of lumbar thorns along the dorsal midline of the disc, a single row of tail thorns in both sexes, pores of ampullae of Lorenzini extending to just anterior to the pelvic girdle, anterior fenestra of scapulocoracoid strongly horizontally elliptical, mesocondyle located at about the middle between the procondyle and metacondyle, and three pairs of obturator foramina on the pelvic girdle.     

Patterns of Plant Invasions: A Case Example in Native Species Hotspots and Rare Habitats

Land managers require landscape-scale information on where exotic plant species have successfully established, to better guide research, control, and restoration efforts. We evaluated the vulnerability of various habitats to invasion by exotic plant species in a 100,000 ha area in the southeast corner of Grand Staircase-Escalante National Monument, Utah. For the 97 0.1-ha plots in 11 vegetation types, exotic species richness (log₁₀) was strongly negatively correlated to the cover of cryptobiotic soil crusts (r = −0.47, P < 0.001), and positively correlated to native species richness (r = 0.22, P < 0.03), native species cover (r = 0.23, P < 0.05), and total nitrogen in the soil (r = 0.40, P < 0.001). Exotic species cover was strongly positively correlated to exotic species richness (r = 0.68, P < 0.001). Only 6 of 97 plots did not contain at least one exotic species. Exotic species richness was particularly high in locally rare, mesic vegetation types and nitrogen rich soils. Dry, upland plots (n = 51) had less than half of the exotic species richness and cover compared to plots (n = 45) in washes and lowland depressions that collect water intermittently. Plots dominated by trees had significantly greater native and exotic species richness compared to plots dominated by shrubs. For the 97 plots combined, 33% of the variance in exotic species richness could be explained by a positive relationship with total plant cover, and negative relationships with the cover of cryptobiotic crusts and bare ground. There are several reasons for concern: (1) Exotic plant species are invading hot spots of native plant diversity and rare/unique habitats. (2) The foliar cover of exotic species was greatest in habitats that had been invaded by several exotic species.(3) Continued disturbance of fragile cryptobiotic crusts by livestock, people, and vehicles may facilitate the further invasion of exotic plant species. This revised version was published online in July 2006 with corrections to the Cover Date.