Effect of endothelin-1 on release of arginine-vasopressin from perifused rat hypothalamus

Endothelin-1 (ET-1) is an endothelium-derived vasoconstrictor peptide with potent pressor activity. We studied the effect of ET-1 on release of arginine-vasopressin (AVP) from perifused rat hypothalamus. ET-1 (10(-10) to 10(-8) M) significantly stimulated AVP release. The ET-1-induced AVP release was completely blocked in the presence of nicardipine. Our results suggest a possible involvement of ET in the regulation of AVP release.     

Possible physiological role of guanosine triphosphate and inositol 1,4,5-trisphosphate in Ca2+ release in macrophages stimulated with chemotactic peptide.

The release of Ca2+ induced by inositol 1,4,5-trisphosphate (InsP3) in the presence of GTP was examined by using saponin-permeabilized macrophages. The origin and the amount of mobilized Ca2+ in intact macrophages stimulated with chemotactic peptide were also examined to assess the physiological significance of GTP and InsP3 on Ca2+-releasing activities. The total amount of Ca2+ released by 20 microM-A23187 from the unstimulated intact macrophages was 1.4 nmol/4 x 10(6) cells, and the mitochondrial uncoupler did not cause an efflux of Ca2+ from the cells. The Ca2+ accumulation by the non-mitochondrial pool(s) was inhibited by the presence of GTP, and the total amount of releasable Ca2+ (1.4 nmol/4 x 10(6) cells) was comparable with that accumulated by the non-mitochondrial pool(s) in the presence of GTP at a free Ca2+ concentration of 0.14 microM. The mobilized and subsequently effluxed Ca2+ in cells stimulated with chemotactic peptide was estimated to be 0.3 nmol/4 x 10(6) cells. Much the same amounts were released by about the half-maximal dose of InsP3 from the non-mitochondrial pool(s) of saponin-treated macrophages that had accumulated Ca2+ at a free concentration of 0.14 microM in the presence of GTP. These results suggest that the Ca2+-releasing activity induced by GTP may play a role in the long-term regulation of Ca2+ content in the non-mitochondrial pool(s) of macrophages, and that released by InsP3 can explain, quantitatively, the chemotactic-peptide-induced mobilization of Ca2+.     

Individual growth and smoltification of juvenile masu salmon, Oncorhynchus masou Brevoort, under rearing conditions

In a reared population of individually marked juvenile masu salmon, individual growth was monitored from the first autumn in 1983 to the following spring. The potential smolts were not significantly greater in mean fork length and body weight than the potential parr in late August of the first year, but they then grew faster until March of the second year. As a result, the potential smolts formed the upper mode of the bimodal length distribution after February. Especially in autumn (October and November) the specific growth rates of potential smolts were significantly greater than those of parr, and the bimodality in growth rate distribution was more distinct for males than females. These suggest that there are two groups having different growth rates in autumn of the first year and that sufficient growth in this period may play an important role in smoltification in the following spring.     

Succession of sessile organisms on experimental plates immersed in Nabeta Bay,Izu Peninsula,Japan V. An integrated consideration on the definition and prediction of succession

Successional changes of sessile organisms over about 3 years on concrete plates immersed at depths of 1.0, 2.5, 4.0 and 5.5 m in Nabeta Bay, Shimoda, Pacific coast of Japan, were investigated from their species composition, percentage cover, and the structure, metabolism, biomass and maturity of the community for the purpose of verifying the hypothesis of succession by Margalef (1968) and Odum (1969). The process of succession was divided into five stages from a cluster analysis based on Horn's (1966) similarity in community structure. The five stages were characterized from dominant, species and 18 community attributes in terms of structure, metabolism, biomass and maturity. With the advance of stages, two large-sized, long-lived species, the kelpEisenia bicyclis and the oysterCrassostrea nippona, dominated; 18 community attributes showed a directional succession ending in a constant community structure, low community metabolism, accumulation of community biomass except chlorophylla and an enhanced degree of community maturity. This directionality in succession of community attributes was valid for the prediction of Margalef and Odum, despite a tendency for estimated daily energy budget to be more heterotrophic in such an open system. From these results, it was suggested that the definition of succession by Odum (1969) should be interpreted as the regularity in shift of dominant species, not individual species, and as the control of system by feedback mechanism developing with succession rather than community-controlled mechanism.     

Identification of the region including the epitope for a monoclonal antibody which can neutralize human parvovirus B19.

In this study, we identified a region in the human parvovirus structural protein which involves the neutralization of the virus by a monoclonal antibody and site-specific synthetic peptides. A newly established monoclonal antibody reacted with both viral capsid proteins VP1 and VP2. The epitope was found in six strains of independently isolated human parvovirus B19. The monoclonal antibody could protect colony-forming unit erythroid in human bone marrow cell culture from injury by the virus. The monoclonal antibody reacted with only 1 of 12 peptides that were synthesized according to a predicted amino acid sequence based on nucleotide sequences of the coding region for the structural protein of B19 virus. The sequence recognized by the antibody was a site corresponding to amino acids 328 to 344 from the amino-terminal portion of VP2. This evidence suggests that the epitope of the viral capsid protein is located on the surface of the virus and may be recognized by virus-neutralizing antibodies.     

Induction of Cytoplasmic Streaming and Movement of Chloroplast Induced by L-Histidine and its Derivatives in Leaves of Egeria densa

Rotational cytoplasmic streaming in leaves of Egeria densa wasinduced by light as well as by L-histidine (L-His). During bothtreatement with light and with L-His chloroplasts on the periclinalface were dislodged and moved to the anticlinal face where rotationalcytoplasmic streaming occurred. The effective concentrationof L-His was about 0.01 mM and the effect was almost saturatedat 0.1 mM. A derivative of L-His, 3-methyl-L-histidine, wasslightly less effective than L-His. By contrast, 1-methyl-L-histidinewas almost ineffective for induction of streaming, not onlyin Egeria but also in Vallisneria. Our resutlts are in markedcontrast to Fitting's result (1936) that 1-M-L-His is more effectivethan L-His. In Egeria, 1-methyl-L-His counteracted the stimulativeeffect of L-His. 1-Methyl-L-His penetrated into leaf cells ofEgeria to the same extent as 3-methyl-L-His and to a greaterextent than L-His. This observation excludes the possibilitythat the impermeability of leaves to 1-M-L-His might be responsiblefor its ineffectiveness. 1-M-L-His did not interfere with photodinesis.Differences in the mechanism of induction of rotational streamingby L-His and by light are discussed. ⁴ Present address: Fukui Institute of Technology, Gakuen, Fukui,910 Japan (Received July 16, 1990; Accepted December 20, 1990)     

Cytoplasmic Alkalization and Cytoplasmic Streaming Induced by Light and Histidine in Leaf Cells of Egeria densa: in vivo 31P-NMR study

Rotational streaming of the cytoplasm including chloroplastswas induced by L-histidine, as well as by light, on the anticlinalface of leaf cells of Egeria densa. In the case of treatmentwith L-histidine some of the chloroplasts remained stationaryon the periclinal face of cells after rotational cytoplasmicstreaming was initiated. However, these chloroplasts were easilydislodged and translocated to the centrifugal end of the histidine-treatedcells by application of a centrifugal force that barely affectedthe location of chloroplasts in cells incubated in the darkwithout L-histidine. This result indicates that the anchoringof chloroplasts was weakened by L-histidine. Thus only the releaseof chloroplasts from anchoring was not enough for initiationof their streaming. The cytoplasmic pH (pH_c) and vacuolar pH(pH_v) were noninvasively monitored by in vivo ³¹P-nuclear magneticresonance (NMR) spectroscopy. Compared with the dark controlvalue, both illumination and treatment with L-histidine increasedthe pH_c by 0.3 units. In contrast, pH_v changed only a littlewith both illumination and treatment with L-histidine. Releaseof chloroplasts from anchoring and initiation of cytoplasmicstreaming are discussed in relation to the increase in pH_c inducedby both light and L-histidine. ⁴ Present address: Department of Cell Biology, National Instituteof Agrobiological Resources, Kannondai, Tsukuba, Ibaraki, 305Japan ⁵ Present address: Marine Biotechnology Institute Co., Ltd.,Head Office, 2-35-10 Hongo, Bunkyo-ku, Tokyo, 113 Japan (Received July 16, 1990; Accepted December 20, 1990)     

A novel MHC class I-related molecule expressed on mouse thymic stroma cells and mature lymphocytes

A monoclonal antibody (mAb) TP-3 has been established by immunizing rats with the BALB/c mouse thymic epithelial cell line TEL-2. The TP-3 antigen is expressed on stroma cells of thymus, spleen, and lymph node in syngeneic BALB/c mice (H-2 ^d ). This antigen is also expressed at a low level on the cell surface of immature thymocytes, and at a high level on mature T and B cells. In allogeneic mice such as C57BL/6 (H-2 ^b ) or C3H (H-2 ^k ), no cells expressed the TP-3 antigen. Using H-2 congenic mice, reactivity with mAb TP-3 was found to map to a region of H-2D ^d L ^d or between D ^d and Qa, suggesting that TP-3 is a major histocompatibility complex (MHC) class I antigen. However, immunoprecipitation analysis indicated that this antigen is not identical to the classical mouse class I molecules in terms of molecular size, antigenicity, and tissue distribution.     

Sequence and over-expression of subunits of adenosine triphosphate synthase in thermophilic bacterium PS3

The primary structures of all the subunits of thermophilic ATP synthase were determined, and its alpha, beta and gamma subunits could be over-expressed in Escherichia coli, because these subunits were stable and reconstitutable. DNA of 7500 base pairs in length was found to contain a cluster of nine genes for subunits of ATP synthase. The order of their reading frames (size in base pairs) was: I(381): a(630): c(216): b(489): delta(537): alpha(1507): gamma(858): beta(1419): epsilon(396), I being a gene for a small hydrophobic, basic protein expressed in vitro. All the termini of TF0F1 subunits were confirmed by peptide sequencing. Large quantities of the overexpressed thermophilic alpha, beta and gamma subunits were prepared from the extract of E. coli, by a few purification steps.