Postglacial environmental change of the Pacific Ocean off the coasts of central Japan

Downcore changes in microfossil assemblages and oxygen isotope ratios in three piston cores recovered from the Northwestern Pacific, off central Japan, show that the subtropical Kuroshio front was located to the south of C-4 core site (Lat. 33° N) during the last glacial. The front then advanced northward, passing over the C-4 site and the C-6 site (34.6° N) at about 13 ka and 10 ka, respectively, and reached the C-1 core site (36° N) at about 7 ka. After 5.5 ka it retreated to the area between the C-1 and C-6 sites. A brief but significant cold event, the readvance of the cold Oyashio Current, is recognized between 11 and 10 ka in the two northern cores, but the current did not reach the southern C-4 site. A contemporaneous cold event is known in the North Atlantic, and the cooling was probably a global phenomenon likely to be associated with lowering of sea level. Contamination of isotopically light water is apparent between 14 and 11 ka in the marked change in isotopic composition of benthic foraminifers. Oxygen isotope ratios of planktonic foraminifers show that prior to the advance of the Kuroshio front, the surface water at these core sites was isotopically lighter than the Kuroshio water at that time.     

Expression and processing of cyanobacterial Mn-stabilizing protein in Escherichia coli

The woxA gene of cyanobacterium Anacystis nidulans R2, which encodes the precursor of the Mn-stabilizing protein involved in photosynthetic water oxidation, was found to be expressed in Escherichia coli. The 30-kDa expression product was indistinguishable from the authentic mature protein on SDS/PAGE. Upon fractionation of E. coli cells, the expression product was co-precipitated with the membrane fraction, which is consistent with the water-insoluble nature of the authentic mature protein. Analysis of the amino-terminal amino acid sequence of the product revealed that it is identical to the sequence from the 28th residue of the precursor, indicating that the precursor is processed in E. coli. The expression product was digested by trypsinization of E. coli spheroplasts, but not by that of intact cells. This observation suggests that the product is secreted from the cytoplasmic membrane, but not from the outer membrane. The occurrence of both processing and secretion suggests that a signal peptidase of E. coli can recognize the structure for translocation across the thylakoid membrane. Comparison of the signal sequence and the presequence of sweet potato sporamin A suggests that the processing enzymes of the thylakoid membrane and endoplasmic reticulum possess a common substrate specificity.     

Intragranular co-storage of neuropeptide Y and arginine vasopressin in the paraventricular magnocellular neurons of the rat hypothalamus

Summary Certain populations of arginine vasopressin (AVP) neurons in the magnocellular paraventricular nucleus became immunoreactive for neuropeptide Y (NPY) when rats were treated with colchicine or monosodium glutamate (MSG). The co-storage of these peptides was examined by empooying a post-embedding electron-microscopic immunohistochemistry technique using goldlabeled antibodies to the two peptides. In colchicinetreated rats, the neuronal perikarya contained numerous secretory granules showing co-storage of the two peptides. The cells of the MSG-treated rats were characterized by having well-developed Golgi bodies with the granular structures also co-storing the two peptides, although the secretory granules in the perikarya were rather fewer than in the colchicine-treated rats. It is concluded that the destruction of the arcuate nucleus by MSG-treatment may potentiate the synthesis of NPY in AVP neurons, the synthesis of which is latent in intact animals.     

Epidermal growth factor (EGF)-induced morphological changes in the basement membrane of chick embryonic skin

Summary The effect of epidermal growth factor (EGF) on the basement membrane structure of chick embryonic skin cultured in a chemically defined medium (BGJb) containing 20 mM hydrocortisone, and EGF at 10, 50, or 100 ng/ml supplemented with 5% delipidized fetal calf serum, was examined by electron microscopy. During development of the epidermis in vitro, EGF (100 ng/ml) caused striking changes to occur in the basement membrane structure and in the keratinization process. The basement membrane frequently became discontinuous with many gaps apparent in section, and occasionally became folded following detachment from the basal surface of the epidermis and protruded into the underlying dermis. In the basal and intermediate cells of EGF-treated epidermis, tonofilament bundles were decreased in number, while desmosomes and hemidesmosomes revealed no significant changes in morphology.     

Monoclonal Antibodies Specific for NADH-Ferricyanide Reductase Domain of Spinach Leaf Nitrate Reductase

Two monoclonal antibodies, 17(3)9 and 36(79)4, were preparedagainst nitrate reductase from Spinacia oleracea L. leaves.An enzyme-linked immunosorbent assay showed that 17(3)9, butnot 36(79)4, reacted more strongly to heat-denatured than nativeantigen. These antibodies inhibited NADH-nitrate reductase aswell as its various partial activities including reduced methylvilogen-nitrate reductase, reduced flavin mononucleotide-nitratereductase and NADH-cytochrome c reductase activities, but notNADH-ferricyanide reductase activity. Immunoblotting after electrophoreticseparation of nitrate reductase fragments obtained by Staphyrococcusaureus V8 protease digestion of native enzyme revealed thatthe two monoclonal antibodies bind to different epitopes locatedon the 28 kDa of the NADH-ferricyanide reductase domain. (Received October 2, 1987; Accepted June 9, 1988)     

Increase in nucleoside diphosphatase in rat brain striatum lesioned with kainic acid

The activity of ammoniagenesis from guanine nucleotides was found to increase significantly in rat brain after infusion of kainic acid into the striatum. Among the enzymes involved in degrading guanine nucleotides, nucleoside diphosphatase was markedly increased in the lesioned striatum. The enzyme activity began to increase 2 days after the infusion, and reached the maximum on the 13th day, the level being 4 times as high as that of the intact contralateral region. The increased activity was due to Type L enzyme, judging from its substrate specificity. Puromycin and cycloheximide inhibited this increase, indicating that the increased activity resulted from an increase in the net synthesis of the enzyme. These findings suggest that Type L NDPase might play some important roles in gliosis after neuronal lesion.     

Changes of carp myosin subfragment-1 induced by temperature acclimation

Summary Heavy meromyosin subfragment-1 (S1) was prepared by -chymotrypsin from myosin of carp acclimated to either 10°C or 30°C for a minimum of 5 weeks. The objective of these studies was to document thermally-induced changes in the myosin molecule and to extend previous observations. Ca²⁺- and K⁺ (EDTA)-ATPase activities of cold-acclimated carp S1 were 1.1 and 0.8 mol P_i·min^-1·mg^-1, respectively, and these values did not differ significantly from those of warm-acclimated carp. The inactivation rate constant (K_D) of S1 from cold-acclimated carp was 32.1x10^-4· s^-1, compared to 13.2x10^-4·s^-1 for warm-acclimated carp. The maximum initial velocity of acto-S1 Mg²⁺-ATPase activity at pH 7.0 in 0.05 M KCl was 9.3 s^-1 with cold-acclimated carp, about 3.7 times higher than that for warm-acclimated carp. However, no significant difference was observed in the apparent affinity of S1 to actin. Peptides maps of the heavy chain of S1 were different and suggested distinct isoforms for the myosins from warm- and cold-acclimated muscle.Abbreviations ATPase adenosine 5-triphosphatase - DTNB 5,5-dithiobis (2-nitrobenzoic acid) - DTT dithiothreitol - EDTA ethylenediaminetetraacetic acid - EGTA ethyleneglycol bis (-aminoethylether)-N,N,N,N-tetraacetic acid - K _D inactivation rate constant - K _m apparent dissociation constant - P _i inorganic -phosphate - PMSF phenylmethane-sulfonyl fluoride - S ₁ heavy meromyosin subfragment-1 - SDS sodium dodecyl sulfate - SDS-PAGE SDS-polyacrylamide gel electrophoresis - TPCK N-tosyl-l-phenylalanyl chloromethyl ketone - V _max maximum initial velocity     

Morphology of the granular hemocytes of the Japanese horseshoe crabTachypleus tridentatus and immunocytochemical localization of clotting factors and antimicrobial substances

Summary The structure of hemocytes in the normal state and during blood coagulation, and the intracellular localization of three clotting factors and two antimicrobial factors were examined in the Japanese horseshoe crabTachypleus tridentatus. Two types of hemocytes were found in the circulating blood: non-granular and granular hemocytes. The latter contained numerous dense granules classed into two major types: L- and D-granules. The L-granules were larger (up to 1.5 m in diameter) and less electron-dense than the D-granules (less than 0.6 m in diameter). The L-granules contained three clotting factors and one antimicrobial factor, whereas the D-granules exclusively contained the other antimicrobial factor. After treatment with endotoxin, the L-granules were released more rapidly than the D-granules, although almost all granules were finally exocytosed. The granular hemocyte possessed a single Golgi complex; possible precursor granules of L-granules and D-granules contained tubular and condensed dense material, respectively. These data are discussed in relation to the self-defense mechanisms of the horseshoe crab.     

In vivo activation of cirral movement in Stylonychia by calcium

Summary Motor responses of cirri (= organelles consisting of bundles of cilia) in the protozoan Stylonychia are elicited by positive or negative shifts of the membrane voltage from its resting state. The same responses are evoked at voltages near the Ca²⁺ equilibrium potential (E_Ca) applying extremely positive steps under voltage clamp. Motor responses recorded at large positive voltages approaching E_Ca from the negative side corresponded to cirral activation following physiological depolarization from the resting potential (DCA). The hyperpolarization-induced activation of the cirri (HCA) was documented during step potentials positive to E_Ca, suggesting that the observed HCA of the cirri resulted from an efflux of Ca²⁺ from the ciliary space as compared with DCA, which is related to Ca²⁺ influx. The ciliary responses were graded functions of the rising outward or inward driving force for Ca²⁺. Slopes of reciprocal plots of response latencies near E_Ca as a function of membrane potential indicate a removal of Ca²⁺ during HCA which exceeds the free intraciliary Ca²⁺ content at rest. It is suggested that this excess Ca²⁺ is released from axonemal binding sites.     

Analyses of constituents of feces and the effect of a vitamin B12 fortified diet on coprophagy in the mouse

In order to investigate coprophagy from the viewpoint of nutrition, fecal constituents were analyzed in freeze-dried samples. Feces were collected from 7:00 to 11:00 and from 19:00 to 23:00. Inorganic elements and crude fibers per unit weight were 3-4 times more concentrated in feces than in basal diet, whereas, crude proteins, crude fats and nitrogen-free extract showed various degrees of reduction. There were no differences in these tendencies with sampling time. As for some B vitamins, feces collected from 7:00 to 11:00 contained 22-92% more vitamins than feces collected from 19:00 to 23:00. In comparison with the dietary concentration, vitamin B12 was increased by 124-197 times (520-730 micrograms/100 g) in feces collected between 7:00 and 11:00. Folic acid in feces collected between 7:00 and 11:00 was 10 times greater than that in the diet. On the basis of the findings on vitamins, the effect of a vitamin B12 fortified diet (1,350 micrograms/100 g) on coprophagy was examined. Mean frequency of coprophagy per animal per day was 9.6 when animals were fed on the basal diet, whereas the frequency was immediately and significantly (p less than 0.05 approximately p less than 0.01) reduced to 4.7 after the diet had been replaced by the fortified one. However, coprophagy was not completely inhibited by vitamin B12 fortification. This indicates that some nutrient(s) in feces other than vitamin B12 might be of use to the host, and that otherwise, coprophagy might be a basically habitual form of behavior. Furthermore, under the fortified diet, the frequency of coprophagy increased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)