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41.
For analytical purposes bioluminescence can be used in three main ways: 1. luminescence measurement of bioluminescent system components isolated in vitro; 2. determination of luminous organisms' reaction to the in vivo test-action; 3. measurement of bioluminescence in marine ecological systems. The majority of the reports of this Symposium are dealing with the first two topics. The aim of our presentation is to draw attention to the third one. The possibilities of bioluminescent analysis are wider than its traditional scheme of applications in the laboratory, when the emitting system is withdrawn from a native source and is placed in a cuvette of the light measuring device. The reverse scheme is also possible, i.e. the device can be introduced into light emitting system such as a marine biocenosis–the community of the sea inhabitants–where we obtain a highly sensitive and rapid means of gaining the information on the vital activity of marine ecosystems, i.e. their spatial structure, rhythms, man's influence upon them, etc. The present communication will consider the possibilities of this form of bioluminescent analysis. 相似文献
42.
The ionic requirements for K+-evoked efflux of endogenous taurine from primary cerebellar astrocyte cultures were studied. The Ca2+ ionophore A23187 evoked taurine efflux in a dose-dependent fashion with a time-course identical to that of K+-induced efflux. The Ca2+-channel antagonist nifedipine had no effect upon efflux induced by 10 or 50 mM K+. In addition, verapamil did not antagonize 50 mM K+-evoked efflux except at high, non-pharmacological concentrations (>100 M), and preincubation with 2 M -conotoxin had no effect on 50 mM K+-evoked efflux. Similarly, preincubation with 1 mM ouabain had no effect on the amount of taurine released by K+ stimulation, but did accelerate the onset of efflux by 2–4 min. Although 2 M tetrodotoxin had no effect on K+-evoked release, replacing Na+ with choline abolished the taurine efflux seen in response to K+ stimulation. Together, these findings suggest that neuronal N- and L-type Ca2+- and voltage-dependent Na+-channels are not involved in the influx of Ca2+ which appears to be necessary for K+-evoked taurine efflux, and that in addition to Ca2+, extracellular Na+ is also required. 相似文献
43.
Bulk inorganic nitrogen deposition was monitored over a period of 3 years at the Bavella Pass (Corsica, France). Annual fluxes range between 126 and 150mol.m–2.d-–1, increasing slightly with annual rainfall. Natural background average concentrations of rain water and associated fluxes were estimated from a classification of rain events into natural (Oceanic and Saharan), polluted and composite. Long range transport of incoming polluted air masses increases the atmospheric wet nitrogen input by at least a factor of 1.6 in this Mediterranean area. Extrapolation of atmospheric dissolved inorganic nitrogen input to the Western Mediterranean leads to fluxes of 80 to l00mol.m–2.d-–1. This atmospheric input is in the same order of magnitude as the inorganic nitrogen riverine input. As a consequence, the nitrogen budget for the Mediterranean has had to be reassessed. Atmospheric wet inorganic nitrogen input is of noticeable importance to marine Mediterranean ecosystems, representing on average 10 to 25% of new production in the Western Basin, with values of up to 60% in oligotrophic zones. 相似文献
44.
Serum-free culture of enriched mouse anterior and ventral prostatic epithelial cells in collagen gel
Timothy Turner Howard A. Bern Peter Young Gerald R. Cunha 《In vitro cellular & developmental biology. Plant》1990,26(7):722-730
Summary Sustained growth of mouse ventral and anterior prostatic epithelial cells embedded within collagen gel matrix was achieved
in a serum-free medium composed of Dulbecco's modified Eagle's medium and Ham's F12 medium, 1∶1 (vol/vol), supplemented with
bovine serum albumin fraction V, epidermal growth factor, transferrin, cholera toxin, prolactin, 5α-dihydrotestosterone, cortisol,
putrescine, fibroblast growth factor, and a trace element mixture. Three-dimensional growth of prostatic epithelial cells
occurred inside the collagen gel matrix. This serum-free medium allowed cell growth greater than sevenfold over 10 d in culture.
Tissue recombination and cell culture techniques were integrated to demonstrate that cultured cells retained prostatic characteristics.
Following 10 d of culture, epithelial colonies from mouse ventral and anterior prostatic epithelial cell cultures were isolated
and combined with rat fetal urogenital sinus mesenchyme and grown for 4 wk under the renal capsule of intact athymic male
mice. These tissue recombinants showed distinctive prostatic histologic characteristic (alveoli and ducts lined with cuboidal
or columnar epithelium surrounded by stroma). When histologic sections of recombinants were stained with the Hoechst 33258,
epithelial cells of mouse origin were distinguishable from stromal cells of rat origin.
Aided by grants CA-05388 and CA-09041 from the National Institutes of Health, Bethesda, MD, and by M. A. R. C. fellowship
GM08730 to T. T. 相似文献
45.
Hillary A. Hahm Margot M. Ip Kathleen Darcy Jennifer D. Black Wendy K. Shea Suzanne Forczek Masami Yoshimura Takami Oka 《In vitro cellular & developmental biology. Plant》1990,26(8):803-814
Summary A serum-free primary culture system is described which allows normal rat mammary epithelial cells (RMECs) embedded within
a reconstituted basement membrane to undergo extensive growth and functional differentiation as detected by synthesis and
secretion of the milk products casein and lipid. RMECs isolated from mammary glands of immature virgin rats were seeded within
an extracellular matrix preparation derived from the Engelbreth-Holm-Swarm sarcoma and cultured in a serum-free medium consisting
of Dulbecco's modified Eagle's medium-F12 containing insulin, prolactin, progesterone, hydrocortisone, epidermal growth factor,
bovine serum albumin, transferrin, and ascorbic acid. Casein synthesis and secretion were documented at the electron microscopic
level as well as by an enzyme-linked immunosorbent assay (ELISA) assay using a polyclonal antibody against total rat caseins.
Numerous secretory vesicles with casein micelles were noted near the apical surface of the RMECs, and secreted casein was
observed in the lumen. These ultrastructural data were confirmed by the ELISA assay which showed that microgram amounts of
casein per well were synthesized by the RMECs and that the amount of casein increased with time in culture. Using immunoblot
analysis it was demonstrated that the full complement of casein proteins was synthesized. In addition to casein protein, β-casein
mRNA levels were shown to increase with time. Synthesized lipid was detected at both the light and electron microscopic levels.
Phase contrast photomicrographs demonstrated extensive intracellular lipid accumulation within the ductal and lobuloalveolarlike
colonies, and at the electron micrograph level, lipid droplets were predominantly localized near the apical surface of the
RMECs. The lipid nature of these droplets was verified by oil red O staining. Results from this study demonstrate that RMECs
from immature virgin rats proliferate extensively and rapidly develop the capacity to synthesize and secrete casein and lipid
when grown within a reconstituted basement membrane under defined serum-free conditions. This unique system should thus serve
as an excellent model in which the regulation of mammary development and gene expression can be investigated.
This work was supported by grants CA 33240 and CA 35641 and by core grant CA 24538 from the National Institutes of Health,
Bethesda, MD. 相似文献
46.
David A. Raftos Dan L. Stillman Edwin L. Cooper 《In vitro cellular & developmental biology. Plant》1990,26(10):962-970
Summary Pharyngeal explants and circulatory hemocytes from the tunicateStyela clava were cultured in a medium containing tunicate plasma, artificial seawater, RPMI 1640, and antibiotics. Pharnngeal tissue
remained viable and proliferated for up to 72 d in vitro. Proliferative activity maintained the pool of hemocytes within explants
and facilitated the migration of pharyngeal hemocytes from explants into culture supernatants. The diversity of morphologically
distinct cell types within the hemocyte pool of pharyngeal cultures indicated that cell division was followed by regulated
differentiation. In contrast to pharyngeal cultures, suspensions of circulatory hemocytes did not survive for prolonged periods
in vitro. Proliferative activity could not be detected in circulatory hemocyte cultures. These results are discussed in terms
of the differentiation state of hemocytes and the efficacy of culture conditions.
This study was supported by the National Science Foundation, Washington, DC (grant DCB 85 19848) and by BRSG funds from UCLA
Schools of Medicine and Dentistry. Flow cytometric facilities were sponsored in part by a Johnson Cancer Center Core Grant
(CA 16042). David A. Raftos is a Fulbright Postdoctoral Fellow and recipient of a Frederik B. Bang Scholarship in Marine Invertebrate
Immunology administered by the American Association of Immunologist. Dan L. Stillman was supported by an REU supplement from
the National Science Foundation. 相似文献
47.
Charles R. Goldman James J. Elser Robert C. Richards John E. Reuters John C. Priscu A. L. Levin 《Hydrobiologia》1996,331(1-3):9-24
Lake Baikal, Russian Siberia, was sampled in July 1990 during the period of spring mixing and initiation of thermal stratification. Vertical profiles of temperature, dissolved nutrients (nitrate and soluble reactive phosphorus), phytoplankton biomass, and primary productivity were determined in an eleven-station transect encompassing the entire 636 km length of the lake. Pronounced horizontal variability in hydrodynamic conditions was observed, with the southern region of the lake being strongly thermally stratified while the middle and north basins were largely isothermal through July. The extent of depletion of surface water nutrients, and the magnitude of phytoplankton biomass and productivity, were found to be strongly correlated with the degree of thermal stratification. Horizontal differences likely reflected the contribution of two important factors: variation in the timing of ice-out in different parts of the lake (driving large-scale patterns of thermal stratification and other limnological properties) and localized effects of river inflows that may contribute to the preliminary stabilization of the water column in the face of intense turbulent spring mixing (driving meso-scale patterns). Examination of the relationships between surface water inorganic N and P depletion suggested that during the spring and early summer, phytoplankton growth in unstratified portions of the lake was largely unconstrained by nutrient supplies. As summer progressed, the importance of co-limitation by both N and P became more apparent. Uptake and regeneration rates, measured directly using the stable isotope 15N, revealed that phytoplankton in stratified portions of the lake relied primarily on NH4 as their N source. Rates of NH4 regeneration were in approximate equilibrium with uptake; both processes were dominated by organisms <2 µm. This pattern is similar to that observed for oligotrophic marine systems. Our study underscores the importance of hydrodynamic conditions in influencing patterns of biological productivity and nutrient dynamics that occur in Lake Baikal during its brief growing season. 相似文献
48.
The anthropological characteristics of the people who lived during the cultural period of the Late Bronze Age in South West
France still remain practically unknown because very few sites have provided skeletal remains which permit of an exhaustive
study. The cave of Sindou is, in that sense, one of the scarce exceptions. Although the sample of Sindou cannot be considered
as representative of the whole regional population (N=50), we studied the presence and severity of DJD and enthesopathies
of microtraumatic origin with the aim of finding some data which contribute to the knowledge of several biological aspects
of this human group. From the results of the comparisons of the Sindou remains with two different medieval samples, a great
similarity is deduced for these skeletal markers, but the higher frequency and severity of Achilles tendon enthesopathy in
Sindou is a probable index of a higher level of physical stress at this specific localisation. 相似文献
49.
M. Tébar C. Bellido J. Th. J. Uilenbroek J. E. Sánchez-Criado 《Cellular and molecular neurobiology》1996,16(3):283-295
Summary 1. In the rat, the LH-dependent ovarian progesterone rise mediates several actions of the primary surge of LH on the ovary. This experiment was aimed at elucidating the effects of the antiprogestagen RU486 on the LH-dependent decrease in both the serum concentrations and the ovarian content of inhibin.2. All rats in this experiment were treated with an antagonist of LHRH (1 mg/200 µl saline at 0800 h in proestrus) to supress the endogenous release of LH. One group of rats received 32 µg LH/250 µl saline at 1200 h in proestrus. Other group was given 4 mg RU486/200 µl oil at 0800 h in proestrus. The third group was injected with both RU486 and LH. Rats from the control group were injected with 250 µl saline and 200 µl oil. Animals were decapitated at 1700 h in proestrus and trunk blood and ovaries collected to determine the serum concentrations of LH, FSH, progesterone, 17ß-estradiol and inhibin as well as the ovarian content of inhibin.3. The ovulatory dose of LH in LHRHa-treated rats decreased both the serum concentrations and the ovarian content of inhibin and increased the serum concentrations of FSH. The administration of RU486 blocked the effect of LH on the serum concentrations of inhibin but not that on the ovarian content of inhibin.4. Since the antiprogestagen RU486 blocked the effect of LH on the serum concentrations of inhibin, we conclude that ovarian progesterone, besides mediating the effects of the primary LH surge on the ovulatory process and luteinization, participates in the LH-dependent drop in the serum concentrations of inhibin in proestrous afternoon. 相似文献
50.
Soil nitrogen dynamics along a gradient of long-term soil development in a Hawaiian wet montane rainforest 总被引:1,自引:0,他引:1
Kanehiro Kitayama 《Plant and Soil》1996,183(2):253-262
I analyzed the rates of net N mineralization and nitrification of soils from seven sites in a Hawaiian wet montane forest. The sites differ in age, ranging from 400 to 4,100,000 yr, but are comparable in other variables (all at 1200 miasl with 4000 mm or more mean annual rainfall), and the chronosequence simulated a development of soils from basaltic lava. Soils were incubated for 20 days at 17.5 °C, which is nearly equivalent to a mean field air temperature of the sites, and at an elevated temperature of 25.5 °C under three treatments: 1) field-wet without amendments, 2) air dried to a permanent wilting point, and 3) fertilized with phosphate (NaH2PO4) at the rate of 50 g P per g dry soil. Both mineralization and nitrification rates varied significantly among the sites at the field temperature (p<.00001). Fractions of the mineralized organic matter (indexed by the N produced per g organic C) increased sharply from the youngest to the 5000-yr site before declining abruptly to a near constant value from the 9000 to the 1,400,000-yr sites. Total organic C in the top soils (<15 cm deep) increased almost linearly with age across the sites. Consequently, net NH4- and NO3-N produced on an area basis (g m-2 20 d-1) increased sharply from 0.2 in the youngest site to 1.2 in the 5000-yr site, then both became depressed once but steadily increased again. The fraction of organic matter mineralized, and the net N turnover rates were outstandingly high in the oldest site where a large amount of organic matter was observed; the topsoil organic matter which was used in this analysis appeared to be highly labile, whereas the subsurface organic matter could be relatively recalcitrant. As suggested by earlier workers, the initial increase in N turnover seemed to correspond to the increasing quantity of N in the soils through atmospheric deposition and biological fixation. The later decline in fraction of organic matter mineralized seemed to relate to increasing soil C/N ratios, increasingly recalcitrant organic matter, and poorer soil drainage with age. The elevated temperature treatment produced significantly higher amounts of N mineralization, except for the youngest site where N was most limiting, and for two sites where soil waterlogging might be severe. P fertilization invariably resulted in slower N turnovers, suggesting that soil microbes responded to added P causing N immobilization. The youngest site did not significantly respond to added P. The magnitude of immobilization was higher in older than in younger soils, suggesting that P more strongly limits microbial populations in the older soils. 相似文献