A comparison of phytoplankton assemblages in the Chesapeake and Delaware estuaries (USA), with emphasis on diatoms

The Delaware Bay is characterized as having greater nutrient and turbidity levels than the Chesapeake Bay. In reference to these differences, a one year study was conducted to identify any similarities and differences in the phytoplankton populations in these estuaries. The results indicated patterns of similarity in the diatom composition, with the total phytoplankton assemblage forming two site groups along a salinity gradient in each bay. These site groups were associated with stations located in the tidal fresh-oligohaline and meso-polyhaline regions of both estuaries. The seasonal concentrations of diatoms and total phytoplankton in both of these regions were higher in the Chesapeake Bay.Subtle differences between the two estuaries include a more diversified and abundant assemblage of neritic phytoplankters (including dinoflagellates) are present in the lower Chesapeake Bay. In contrast, a diatom dominated community is more characteristic of Delaware Bay. It is suggested the entry of neritic species into lower regions of the estuaries was enhanced by the reduced amount of rainfall and flow rates that occurred during the study period. The greater success of neritic species in the Chesapeake Bay is attributed to the lower turbidity of that estuary compared to Delaware Bay.     

Nuclear envelope assembly after mitosis

In higher eukaryotes, the entire nucleus disassembles during prometaphase of the cell cycle and later reassembles around daughter chromosomes. Remarkably, the complex events that occur to create a functional nucleus in vivo can be duplicated in vitro by using cell-free extracts. Current experiments are aimed at understanding the molecular mechanisms of assembly and disassembly of the nuclear pore complexes and nuclear membranes, and the functional roles of four identified inner membrane proteins, two of which bind to both chromatin and the nuclear lamina.     

Microspectrophotometric studies of Romanowsky stained blood cells. IV. Maturation of myeloid and erythroid cell lines in bone marrow

A quantitative characterization has been made of azure B/eosin stained cells from bone marrow. Two cell lines were followed: the myeloid line (white cell blast, promyelocyte, neutrophilic myelocyte, neutrophilic metamyelocyte, neutrophilic band, neutrophilic segmented) and the erythroid line (rubriblast, prorubricyte, rubricyte, metarubricyte, diffusely basophilic erythrocyte, erythrocyte). A consensus scheme was used to obtain the "true" classification of the cells. Cell types were characterized by three methods: absorbance spectra, dye binding, and chromaticities. Within both cell lines nuclear maturation is accompanied by an overall increase in peak absorbance with little shift in the position of the maximum. Generally, binding of azure B and eosin increases; azure B dimer/monomer ratios show a slight downward trend during maturation. Changes in chromaticities are to bluish purples of increasing saturation. Cytoplasmic changes accompanying maturation are much more striking than nuclear changes, and again the two cell lines show similarities. Generally, there is decreased binding of azure B during maturation. In the erythroid line, the Soret band of hemoglobin becomes increasingly prominent. Chromaticities change from bluish purples to purplish pinks, particularly in the erythroid line.     

A modified direct phosphate assay for studying ATPases

A simple, rapid assay for purified ATPases is presented, based upon the formation of phosphomolybdate and its extraction into butyl acetate. The inclusion of imidazole makes the assay more sensitive and reproducible apparently because of the formation of an imidazole-phosphomolybdate complex. Protein (100 micrograms), Hepes buffer [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] (0.1 M) and nucleotides (1 mM) were all shown to cause interference. The interference by nucleotides could be counteracted by using more molybdate. Butyl acetate was shown to extract virtually all of the phosphomolybdate almost instantaneously upon vortex mixing.     

Hypothesis--a chemical mechanism for the biosynthesis of ATP involving ion-exchange reactions

Dissociation constants for Mg . ATP were determined by displacing ATP from Dowex-1 resin with magnesium. These constants were then used to analyze the kinetics of yeast mitochondrial ATPase, in terms of the concentrations of free magnesium and free ATP, at a series of pH values. Both Mg . ATP and hydroxide ions were found to compete with the binding of ATP to the enzyme. These results were interpreted, in terms of an ion-exchange model, to mean that the synthesis of ATP may require the utilization of both magnesium and hydroxide ions for the dissociation of ATP from the enzyme as Mg . ATP. The concentrations of Mg and hydroxide required to compete with ATP were both found to be about three orders of magnitude greater than those required to form products, indicating that magnesium and hydroxide ions can contribute about 8 kcal of energy when ATP is synthesized.     

Detection of protein in polyacrylamide gels using an improved silver stain

A much improved silver staining procedure for the detection of protein in polyacrylamide gels of 0.8-3.0 mm thickness is described. It achieves very high sensitivity (detecting less than 0.01 ng bovine serum albumin/mm2) by overstaining and subsequently removing nonspecific background stain using a modified, reliable destaining procedure. Maximum sensitivity follows prediamine equilibration in 0.1% (w/v) formaldehyde solution. With two-dimensional electrophoresis the improved staining procedure reveals greater than 200 polypeptides in unconcentrated human urine and greater than 150 polypeptides in a single human fingerprint.     

Relevance of duration of transient ischaemic attacks in carotid territory.

A retrospective review of the clinical and angiographic features of 116 patients who had had one or more transient ischaemic attacks in the carotid territory showed that stenosis of ther cervical portion of the internal carotid artery was significantly more prevalent among patients whose attacks had been brief, with full recovery in under one hour. This information may be helpful in selecting patients for angiography.     

Cell surface changes in diabetic rats. Studies of lectin binding to liver cell plasma membranes.

We have previously reported changes in the chemical composition of cell surface membranes in diabetic rats (Chandramoulis, V. and Carter, Jr., J. R. (1975) Diabetes 24, 257-262 [1]). To examine the possible implications of these changes for cell surface structures, we have measured the binding of labeled lectins and desialylated glycoproteins to plasma membranes prepared from the livers of streptozotocin--diabetic and control rats. Lectins were chosen which have affinities for different carbohydrate moieties. The binding of ricin and concanavalin A to liver cell membranes from the diabetic rats was significantly reduced, but no change in the binding of wheat germ agglutinin was noted. Binding of desialylated thyrozine--binding globulin, previously shown to be dependent on membrane sialic acid residues, ws strongly suggest that insulin deficiency leads to generalized changes in cell surfaced glycoproteins, at least in this animal model of diabetes.