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  • 1
    Electronic Resource
    Electronic Resource
    Heliospheric current sheet inclinations at Venus and Earth (1999)
    Springer
    Annales geophysicae 17 (1999), S. 642-649 
    Details
    ISSN: 0992-7689
    Keywords: Interplanetary physics (interplanetary magnetic fields; sources of solar wind)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We investigate the inclinations of heliospheric current sheet at two sites in interplanetary space, which are generated from the same solar source. From the data of solar wind magnetic fields observed at Venus (0.72 AU) and Earth (1 AU) during December 1978–May 1982 including the solar maximum of 1981, 54 pairs of candidate sector boundary crossings are picked out, of which 16 pairs are identified as sector boundaries. Of the remainder, 12 pairs are transient structures both at Venus and Earth, and 14 pairs are sector boundaries at one site and have transient structures at the other site. It implies that transient structures were often ejected from the coronal streamer belt around the solar maximum. For the 16 pairs of selected sector boundaries, we determine their normals by using minimum variance analysis. It is found that most of the normal azimuthal angles are distributed between the radial direction and the direction perpendicular to the spiral direction both at Venus and Earth. The normal elevations tend to be smaller than ≈45° with respect to the solar equatorial plane, indicating high inclinations of the heliospheric current sheet, in particular at Earth. The larger scatter in the azimuth and elevation of normals at Venus than at Earth suggests stronger effects of the small-scale structures on the current sheet at 0.72 AU than at 1 AU. When the longitude difference between Venus and Earth is small (〈40° longitudinally), similar or the same inclinations are generally observed, especially for the sector boundaries without small-scale structures. This implies that the heliospheric current sheet inclination tends to be maintained during propagation of the solar wind from 0.72 AU to 1 AU. Detailed case studies reveal that the dynamic nature of helmet streamers causes variations of the sector boundary structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-0642-z
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  • 2
    Electronic Resource
    Electronic Resource
    The role of cytotoxic macrophages in non-obese diabetic mice: cytotoxicity against murine mastocytoma and beta-cell lines (1993)
    Springer
    Diabetologia 36 (1993), S. 1252-1257 
    Details
    ISSN: 1432-0428
    Keywords: Non-obese diabetic mice ; macrophage ; Type 1 (insulin-dependent) diabetes mellitus ; cytokine ; nitric oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cytotoxicity of macrophages from non-obese diabetic (NOD) mice against murine mastocytoma (P-815), and murine beta-cell lines having the NOD gene background (MIN6N-9a), were examined. Peritoneal exudate cells from 20-week-old mice showed higher cytotoxicity, measured as inhibition of thymidine uptake into P-815, than those from 12-week-old mice (p 〈0.01). In cyclophosphamide-injected mice, cytotoxicity of peritoneal exudate cells had increased at 8 days post-injection, at which time the mice were not diabetic. To confirm macrophage cytotoxicity against pancreatic cells and examine its cytolytic mechanism, the cytotoxicity of peritoneal exudate cells from cyclophosphamide-injected NOD mice against MIN6N-9a cells was measured by the chromium release assay. These peritoneal exudate cells showed higher cytotoxicity as compared to those of saline-injected mice (p 〈0.001). Macrophages were demonstrated to be the major component of peritoneal exudate cells (50%) by flowcytometric analyses. Cytotoxicity increased with macrophage enrichment by adhesion (p 〈0.01). Furthermore, a macrophage toxin, silica, completely blocked the cytotoxicity (p 〈0.001). Cytokines (interleukin 1 and tumour necrosis factor) and a nitric-oxide-producing vasodilator, sodium nitroprusside, were cytotoxic to MIN6N-9a cells but only sodium nitroprusside showed cytotoxicity when incubated for the same period as peritoneal exudate cells. Thus, macrophages play an important role in beta-cell destruction and soluble factors other than cytokines (e.g. nitric oxide) may be mediators of this early cytolytic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400802
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  • 3
    Electronic Resource
    Electronic Resource
    Progression in nemaline myopathy (1989)
    Springer
    Acta neuropathologica 78 (1989), S. 484-491 
    Details
    ISSN: 1432-0533
    Keywords: Nemaline myopathy ; Lysosomal enzymes ; Acid phosphatase ; Cathepsins ; Myofibrillar degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four of seven patients with nemaline myopathy had severe, rapidly progressing symptoms. These four showed an increase in acid phosphatase activity in muscle fibers demonstrated by histochemistry and cathepsin B&L activity by biochemical measurement. On electron microscopy, nemaline bodies, occasionally disorganized myofibrils and autophagic vacuoles containing sarcoplasmic debris and glycogen particles were seen. Focal myofibrillar degeneration, through an unknown pathogenetic mechanism, induces an increase in lysosomal enzymes in the skeletal muscles which may be closely correlated with a rapid aggravation of muscle weakness in nemaline myopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687709
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  • 4
    Electronic Resource
    Electronic Resource
    Sensitivity of zooxanthellae and non-symbiotic microalgae to stimulation of photosynthate excretion by giant clam tissue homogenate (1994)
    Springer
    Marine biology 118 (1994), S. 687-693 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stimulation of photosynthate excretion from zooxanthellae and free-living algae by tissue homogenate of several bivalves was studied. Mantle tissue homogenate of Tridacna derasa enhanced 10-to 15-fold excretion of photosynthetically fixed carbon from freshly isolated zooxanthellae within 2 h incubation. Maximum carbon excretion was 35 to 45% of the total carbon fixed. This excretion stimulating activity was detected in the homogenates of the mantle, adductor muscle, gill, and kidney. However, no excretion stimulating activity was detected in the haemolymph. The excretion stimulation activity of mantle homogenate, directed against freshly isolated zooxanthellae from T. derasa, was higher in bivalves belonging to the Tridacnidae (T. derasa, T. crocea, T. maxima, T. squamosa, Hippopus hippopus) than in the Cardiidae (Fragum fragum, F. mundum, F. unedo), non-symbiotic bivalves (Mytilus edulis, Meretrix lusoria, Ruditapes philippinarum) or gastropods (Umbonium giganteum, Turbo argyrostoma). The mantle homogenate of T. derasa enhanced photosynthate excretion by free-living algae belonging to the Dinophyceae (Prorocentrum micans, Amphidinium carterae, and Heterocapsa triquetra) but did not enhance its excretion by free-living algae belonging to the Chlorophyceae, Cyanophyceae, Rhodophyceae, Prasinophyceae, and Haptophyceae. T. derase used in this study originated from Belau (Palau). T. crocea, T. squamosa, T. maxima, H. hippopus and F. unedo were collected at Ishigaki Island in Okinawa in 1992. F. mundum and F. fragm were collected at Okinawa Island in 1992.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347517
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  • 5
    Electronic Resource
    Electronic Resource
    Adaptation of solitary corals and their zooxanthellae to low light and UV radiation (1993)
    Springer
    Marine biology 117 (1993), S. 685-691 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adaptation of solitary corals, Fungia repanda and F. echinata, and their zooxanthellae to low light and ultraviolet light B (UV-B) was studied with respect to changes in their protein contents, photosynthetic pigment contents and the photosynthesis-irradiance (P-I) curves. The corals were collected from 1 to 50 m depths in the Republic of Belau (Paulau) in 1990 and 1991. The chlorophyll a content in a unit surface area of the coral did not change significantly with the depth of the habitat, whereas cellular chlorophyll a in the algae increased with the depth. Zooxanthellae density and protein content in a unit surface area of Fungia spp. decreased with the depth. Photosynthetic parameters normalized by a unit surface area of the Fungia spp., maximum gross photosynthetic rate (P gmax area-1) and dark respiration rate (R area-1), were negatively correlated with the depth, while initial slope of the P-I curve (α) did not show significant correlation with the depth. Compensation light intensity (Ic) decreased with the depth. In isolated zooxanthellae, P max chl a -1, and R chl a -1 decreased with the depth, while αchl a was constant. P gmax cell-1 and R cell-1 did not change significantly but αcell increased with the depth. Ic decreased with the depth as in the intact corals. Reduction of protein content in a unit area of the coral from deeper habitat implies decrease of host animal tissues. Reduction of Ic can be explained by decrease of R area-1, which may be due to the diminution of animal tissues. The photoadaptational response to low light intensity of intact Fungia spp. was found to be a combination of the photoadaptation of symbiotic algae and the decrease of host animal tissue. In order to study their adaptation to ultraviolet (UV) radiation, P-I curves of Fungia spp. and isolated zooxanthellae were analyzed before and after UV-B irradiation. 1 h UV-B irradiation showed no effect on the photosynthetic rate of the shallow water (1 m) corals, while it inhibited the photosynthesis of the deep water (30 m) corals and zooxanthellae isolated from both shallow and deep water corals. These results indicate that the host, Fungia spp., in shallow water have protective mechanism for intense UV-B in their habitat. These photoadaptational mechanisms seem to allow the Fungia spp. to have wide vertical distribution where light intensity spans more than two orders of magnitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349781
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  • 6
    Electronic Resource
    Electronic Resource
    Fecal discharge of zooxanthellae in the giant clam Tridacna derasa, with reference to their in situ growth rate (1997)
    Springer
    Marine biology 127 (1997), S. 473-477 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The population dynamics of zooxanthellae living in the mantle of a giant clam, Tridacna derasa, was studied. The giant clams with shell lengths of 5 to 6 cm which had been reared in the Palau Mariculture Demonstration Center, in the Republic of Palau, were transferred to aquaria on deck of the R.V. “Sohgen-maru” and kept in running sea water at 29 to 30 °C. Two clams were removed from the aquaria, and zooxanthellae in the mantle were isolated every 2 h for 24 h. Numbers of the zooxanthellae in or not in the cell division stage were counted for calculations of the zooxanthellae population in the mantle and their mitotic index (MI). The MI increased after sunset and reached the maximum values of 6.1 to 11.5% at 03:00 to 05:00 hrs. The specific growth rate, μ, estimated from the MI was 0.083 to 0.14 d−1. Five clams were kept in each of 2 Plexiglas containers in the aquarium for collection of the discharged feces every 3 to 4 h. The discharged zooxanthellae in the feces were counted. The zooxanthellae discharged in 24 h were 0.38 to 1.46% of the total zooxanthella population in the mantle, and 2.7 to 16.9% of the newly formed zooxanthella population in a day. Increase of zooxanthella population in the mantle was estimated from clam shell growth rate and from the correlation between zooxanthella population and clam shell size. Daily increase of zooxanthella population in the mantle was estimated to be approximately 7.6 to 19% of the newly formed zooxanthella population. Therefore, the sum of zooxanthellae populations accounting for daily increase in the mantle and discharge in the feces was 11 to 36% of the newly formed population. About 64 to 89% of the newly formed cells were missing; some of these may have been digested by the clam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050035
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  • 7
    Electronic Resource
    Electronic Resource
    UV-absorbing substances in the tunic of a colonial ascidian protect its symbiont, Prochloron sp., from damage by UV-B radiation (1997)
    Springer
    Marine biology 128 (1997), S. 455-461 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis by cells of Prochloron sp. freshly isolated from the ascidian host, Lissoclinum patella, collected from shallow waters in Palau, was severely inhibited by ultraviolet (UV) irradiation. No photoinhibition, however, was observed in Prochloron cells isolated from intact colonies after UV irradiation, suggesting some protection by the ascidian host. It was shown that UV protection was brought about by the thick gelatinous tunic covering the whole ascidian colony. Analysis revealed that the surface tunic of L. patella, although transparent to visible light, contains several UV-absorbing substances, identified by high-performance liquid chromatography as mycosporine-like amino acids (MAAs). The predominant MAA identified was shinorine (λmax = 334 nm), followed by mycosporine-glycine (λmax = 310 nm) and a small amount of palythine (λmax = 320 nm). Although isolated Prochloron cells also contained shinorine, on a protein-weight basis it was less than half of that observed in the host tunic. These results suggest that the surface tunic of a L. patella colony, which is transparent to visible light for photosynthesis, also contains UV-absorbing compounds that protect its photoautotrophic symbiont, Prochloron sp., from damage by the intense UV-irradiation that they receive daily in shallow, tropical marine waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050112
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  • 8
    Electronic Resource
    Electronic Resource
    UV-absorbing substances in zooxanthellate and azooxanthellate clams (1997)
    Springer
    Marine biology 128 (1997), S. 649-655 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of UV-A and UV-B radiation on photosynthesis of zooxanthellae within the siphonal mantle of the giant clam, Tridacna crocea, and in isolation were studied. While UV-B irradiation (2.4 W m−2, 20 min) completely suppressed photosynthesis of the isolated zooxanthellae, it had little effect on their photosynthetic ability if they were irradiated while within the siphonal mantle of the host tissue. Chemical analysis of the siphonal mantle of T. crocea showed the presence of significant amounts of mycosporine-like amino acids (MAAs), which absorb UV-A and -B light. However, no MAA was detected in the isolated zooxanthellae. MAAs were concentrated in the siphonal mantle and kidney tissues in comparison with other tissues. In the siphonal mantle, MAA concentrations were the highest in the outermost surface layer where most of the zooxanthella cells resided. This indicates that the zooxanthellae are protected from UV radiation by a screen of concentrated MAAs in the host clam. Aside from T. crocea, significant amounts of MAAs were found not only in other zooxanthellate clams, such as T. derasa, Hippopus hippopus, Colculum cardissa and Fragum unedo, but also in a closely related azooxanthellate clam, Vasticardium subrugosum. On the other hand, no MAA was detected in any of the zooxanthellae from these zooxanthellate clams. No MAA was detected in the tissues of a deep-sea bivalve, Calyptogena soyoae. Although MAAs seem to block strong UV radiation in the shallow-water clam, they are probably not essential for the clam's life in the dark. MAAs in shallow-water clams may be derived from food and accumulated in their tissues, especially in the siphonal mantle and kidney.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050131
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  • 9
    Electronic Resource
    Electronic Resource
    Zooxanthellae release glucose in the tissue of a giant clam, Tridacna crocea (1999)
    Springer
    Marine biology 133 (1999), S. 665-673 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The giant clam Tridacna crocea harbors in the mantle tissue symbiotic microalgae commonly called zooxanthellae. Isolated zooxanthellae release glycerol into the medium in the presence of mantle tissue homogenate (MH), but it is not clear whether the cells do so in situ. In order to determine the photosynthetic products released by zooxanthellae in the mantle of the giant clam we traced photosynthetic fixation products from 13C- and 14C-bicarbonate both in the clam and in isolated zooxanthellae (IZ) in the presence or absence of MH. After 15 min incubation in the absence of MH the IZ released less than 0.6% of the fixed labeled carbon, mainly as glucose. The major intracellular photosynthates were neutral lipids, which constituted 20 to 40% of the total extractable 14C. In the presence of MH, the IZ released up to 5.6% of the total fixed 14C, mostly as glycerol, and the major intracellular photosynthate was glucose. In an intact clam incubated in sea water containing 14C-bicarbonate, 46 to 80% of the fixed 14C was translocated from the zooxanthellae to the host tissues. Most of the 14C in the hemolymph, in the isolated zooxanthellae and in intact mantle tissue (containing zooxanthellae) was recovered as glucose. No 14C-glycerol was detected in the mantle after 1 to 30 min incubation, and, even after 60 min, far less 14C-glycerol was synthesized than by IZ in the presence of MH. The possibility that in clam tissue glycerol is converted to glucose was examined by tracing the labeled carbon from 14C-glycerol injected into the adductor muscle. After 5 min incubation, no labeled glucose was found in the hemolymph, but after 60 min, some 20% was found as glucose. Thin slices containing zooxanthellae, cut from the surface of the mantle, fixed inorganic carbon supplied as NaH14CO3 in the medium and mainly released 14C-glucose. The addition of MH to the surrounding medium did not affect the release rate or form of release product. When the slices were cut into smaller pieces, however, the ratio of glycerol to glucose in the release product increased. These results indicate that in the presence of MH the metabolism of isolated zooxan- thellae was different from that of zooxanthellae in the mantle. In the presence of MH, isolated zooxanthellae release mostly glycerol, whereas in the mantle they release glucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050507
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  • 10
    Electronic Resource
    Electronic Resource
    Spatial mesoscale patterns of West Pacific picophytoplankton as analyzed by flow cytometry: their contribution to subsurface chlorophyll maxima (1993)
    Springer
    Marine biology 115 (1993), S. 209-215 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vertical distributions of picophytoplankton (ppp) (〈2 μm) were studied by ship-board flow cytometry during two cruises in Western Pacific waters to Palau and to Australia in 1990. Weak red-fluorescing small “ppp”, supposed to be free-living prochlorophytes (Chisholm et al. 1988), were abundant in the area surveyed. These ppp, designated “the prochlorophytes”, were abundant in the surface waters (〉104 cells ml-1) at the northern region (27°03′N; 7°11′N) in November, whereas in December at the southern tropical stations (0°23.54′S; 9°20.30′S; 13°50.6′S), they formed subsurface maximum layers (〉105 cells ml-1) on a nitracline at a depth of 3.5 to 5.4% surface irradiation. Their fluorescence intensity increased with depth below 10% surface irradiation. The prochlorophytes at a depth of 1% surface irradiation had ten times higher fluorescence than those at the surface layer. The total fluorescence intensity of the prochlorophytes accounted for 32 to 63% of the sum of the total fluorescence intensity of all fluorescing phytoplankton detected at subsurface chlorophyll maxima in the tropical area. These results suggest that distribution of the prochlorophytes is greatly affected by nitracline and by light intensity and that their chlorophyll is a major contributor to the subsurface chlorophyll maximum in the pelagic West Pacific Ocean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346337
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