Epeiric sedimentation and sea level: synthetic ecostratigraphy

Carbonate strata from the central parts of epicontinental seas are ideal for detailed biostratigraphic study of eustatic sea level change. Using a model for epeiric seas in which carbonate accumulation rate is depth-dependent, we derive synthetic stratigraphies for sea level histories simulating post-glacial transgression and constant and sinusoidally fluctuating ridge volume increase. These sea level histories give distinctively different trends for water depth as a function of stratigraphic position in sections' bathymetric curves. In general, depth is proportional to the rate of sea level rise. Depth-dependent sedimentation leads to a time lag between sea level fluctuation and corresponding depth fluctuation which, as examples show, can approach 10⁶ years for depth fluctuations of only a few meters – a fundamental consideration in reconstructing sea level curves, time-correlating sections by their bathymetric curves, and attempting to relate bathymetric history on continents to mechanisms driving sea level change. Bathymetric curves based on gradient analysis of fossil assemblages (coenocorrelation curves) for Middle Ordovician sections in New York and the American Midwest approximate patterns for sinusoidally increasing sea level. The model's predictions are tested in an ‘artificial experiment’ that takes advantage of differential subsidence between the craton's middle and its edge to make a difference in the bathymetric histories of sections that otherwise record the same sea level history. Depth fluctuations of no more than a few meters over million year spans are potentially useful in time-correlation to within fractions of a cycle's period. The depth-dependence in sedimentation was that, above wave base, net accumulation per year was very roughly three-millionths the water depth. Association of volcanic ash layers with transitory sea level minima on the craton, and with onset of more rapid subduction in the Taconic are - continent collision zone, suggests interrelationship on a million year scale between sea level and large-scale tectonic phenomena.     

Effects of piretanide on plasma fibrinolytic activity,platelet aggregation and platelet factor-4 release in man

Piretanide, 4-phenoxy-3-(pyrrolidinyl)-5-sulphamoyl benzoic acid, apart from being an efficient diuretic, enhances endogenous plasma fibrinolytic activity after a single dose of 6 mg administered by oral route. After ingestion of the drug, acceleration of fibrinolytic acitivity became manifest within 1 h, reached its peak in 3 h and was associated with a fall in fibrinogen and diminished urokinase excretion. Piretanide did not cause lysis of fibrinin vitro. Primary platelet aggregation, induced by adenosine-diphosphate, was inhibited by piretanide. Inin vitro experiments piretanide led to effective inhibition of adenosine-diphosphate-induced platelet aggregation with complete inhibition at 5 mM concentration. Piretanide led to a highly significant decrease of platelet factor-4 release.     

Light-driven proton transport of bacteriorhodopsin incorporated into long-term stable liposomes of a polymerizable sulfolipid

The chromoprotein bacteriorhodopsin from Halobacterium halobium has been incorporated into liposomes made of a fully synthetic, polymerizable lipid. Bacteriorhodopsin is found to be active in these polymer liposomes. The advantage in the use of such polymer systems concerning long-term stability in comparison with liposomes made of natural lipid is demonstrated.     

Effects of N,N′-dicyclohexylcarbodiimide on isolated and reconstituted cytochrome b-c1 complex from bovine heart mitochondria

N,N′-Dicyclohexylcarbodiimide (DCCD) inhibits the activity of ubiquinol-cytochrome c reductase in the isolated and reconstitued mitochondrial cytochrome b-c₁ complex. DCCD inhibits equally electron flow and proton translocation (i.e., the $\text{H}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$ ratio is not affected) catalysed by the enzyme reconstituted into phospholipid vesicles. The inhibitory effects are accompanied by structural alterations in the polypeptide pattern of both isolated and reconstituted enzyme. Cross-linking was observed between subunits V (iron-sulfur protein) and VII, indicating that these polypeptides are in close proximity. A clear correlation was found between the kinetics of inhibition of enzymic activity and the cross-linking, suggesting that the two phenomena may be coupled. Binding of [¹⁴C]DCCD was also observed, to all subunits with the isolated enzyme and preferentially to cytochrome b with the reconstituted vesicles; in both cases, however, it was not correlated kinetically with the inhibition of the enzymic activity.     

A comparison of sperm morphology and silver nitrate staining characteristics in the domestic ferret and the black-footed ferret

Ejaculated sperm from the domestic ferret (Mustela putorius furo) and the black-footed ferret (Mustela nigripes) were compared for differences in morphological abnormalities and argentophilic protein distribution. Thawed domestic ferret sperm was also compared to fresh sperm to determine whether there were any effects on cell morphology due to cryopreservation. There were statistically significant differences between the two species of ferret in two of the categories scored. The domestic ferret had a higher frequency of cells that were bent in the midpiece and in the principal piece, and a higher frequency of headless and tailless cells when compared to the black-footed ferret. There were no statistically significant differences in cell morphology between the fresh and cryopreserved ejaculates of the domestic ferret employing a standard egg yolk cryoextender. Silver nitrate staining distribution was different between the two species in both the head and tail region.     

Human macrophage colony-stimulating factor heterogeneity results from alternative mRNA splicing, differential glycosylation, and proteolytic processing

The single gene for human macrophage colony-stimulating factor (M-CSF, or CSF-1) generates multiple mRNA species that diverge within the coding region. We have characterized translation products of these mRNA species from native and recombinant sources. Immunoblots of reduced native M-CSF indicate that multiple glycosylated species ranging from 25 kd to 200 kd are secreted by human monocytes and cell lines. In contrast, CV-1 cells expressing a short M-CSF clone secrete only 24 kd recombinant M-CSF. Synthetic peptide antibodies were developed to distinguish between secreted recombinant M-CSF from long and short mRNA splicing variants. Immunoblot analysis indicates that alternative mRNA splicing generates some M-CSF protein heterogeneity. Most secreted MIA PaCa-2 M-CSF reacts with long-clone-specific antibody. Lectin affinity chromatography shows that variable glycosylation contributes significantly to MIA PaCa-2 M-CSF size heterogeneity. In addition, cell lysates also contain larger M-CSF species that apparently undergo proteolytic processing before secretion. The data indicate that M-CSF protein heterogeneity results from both pre- and post-translational processing.     

Structural and developmental differences between three types of Na channels in dorsal root ganglion cells of newborn rats

Summary The changes in Na current during development were studied in the dorsal root ganglion (DRG) cells using the whole-cell patch-clamp technique. Cells obtained from rats 1–3 and 5–8 days after birth were cultured and their Na currents were compared. On top of the two types of Na currents reported in these cells (fast-FA current and slow-S current) a new fast current was found (FN). The main characteristics of the three currents are: (i) The voltages of activation are –37, –36, and –23 mV for the FN, FA and S currents, respectively. (ii) The activation and inactivation kinetics of FN and FA currents are about five times faster than those of the S current. (iii) The voltages at which inactivation reaches 50% are –139, –75 and –23 mV for the FN, FA and S currents, respectively.The kinetics and voltage-dependent parameters of the three currents and their density do not change during the first eight days after birth. However, their relative frequency in the cells changes. In the 1–3 day-old rats the precent of cells with S, FA, and mixed S+FN currents is 22, 18, and 60% of the cells, respectively. In the 5–8 day-old, the percent of cells with S, FA, and FN+S is 10, 66 and 22%. The relative increase in the frequency of cells with FA current during development can contribute to the ease of action potential generation compared with cells with FN currents, which are almost completely inactivated under physiological conditions. The predominance of FA cells also results in a significant decrease in the relative frequency of cells with the high-threshold, slow current.Antibodies directed against a part of the S₄ region of internal repeat I of the sodium channel (C ₁ ⁺ , amino acids 210–223, eel channel numbering) were found to shift the voltage dependence of FA current inactivation (but not of FN or S currents) to more negative potentials. The effect was found only when the antibodies were applied externally. The results suggest that FN, FA and S types of Na currents are generated by channels, which are different in the topography of the C ₁ ⁺ region in the membrane.     

Uptake of phosphate from soils and fertilizers as affected by soil P availability and solubility of phosphorus fertilizers

Fertilizers labelled with ³²P were used to measure amounts of phosphorus, P_s and P_F, taken up by Lolium perenne from available soil P and from P fertilizer respectively, when applied at a rate of 66 mg P·(kg soil^–1) in greenhouse experiments. The quantity P_s of phosphorus taken up from soil in the presence of P fertilizer was compared to the quantity P_o taken up from soil without P fertilizer. The quantity (P_s–P_o) is positive for low P_o values, i.e. in soils poor in available phosphorus, but is negative for high P_o values indicating that an input of P fertilizer can induce a decrease in the utilization of available soil phosphorus. Moreover, for a given soil, the quantity (P_s–P_o) depends on the chemical form of the fertilizer. The standard method of evaluation of P fertilizer efficiency is based on the assumption that P_s=P_o, but P_s can differ from P_o. This result can explain the contradictory data published from field experiments about the efficiency of the various P fertilizers.     

湖北菱科植物的数量分类研究 Ⅲ.分类性状的定量评价

用R聚类分析和主分量分析,定量研究了湖北菱科5种8变种37个形态和生态性状的变异及分类学价值。结果表明,植物体大小变异是形态演化的主要方向之一。形态演化的同时,也发生生态分化。除少数性状例外,形态演化与生态分化在相当程度上是独立的。     

流域开发生态建设发展战略

以往研究流域开发战略问题,多从流域内资源的开发利用方面考虑,而衡量其方案的优劣也多以经济效益的大小为准绳。现在,环境污染与生态危机已威胁着人类的生存与发展,因此在研究流域战略问题时,必须开拓思路,