Secchi disks have played an important role in hydrologic optics (Preisendorfer, 1986), in part because they allow an easy and inexpensive measure of water transparency. To make a Secchi depth measurement, a white disk is lowered into the water on the sunny side of the ship; the Secchi Depth (SD) is the depth where the disk disappears from view (Secchi, circa 1866). Secchi depth measurements have been used as a real-time assessment of water transparency during optical measurements and as a quality check during analysis of radiometric profiles (Mueller and Austin, 1992). Due to the existence of a large historical database of Secchi disk measurements, attempts have been made to derive Kd(490), the downwelling diffuse attenuation coefficient at 490 nm, and compare them to values of Kd(490) derived from the Coastal Zone Color Scanner (CZCS) on board the Nimbus-7 satellite (Estep and Arnone, 1993). CZCS ceased operating in 1986 and SeaWiFS (Sea-viewing Wide Field-of-view Sensor), a follow-on ocean color sensor, was launched in 1997 aboard the OrbView-2 satellite. In comparison to CZCS, SeaWiFS has additional bands in the blue, green and near-IR regions of the electromagnetic spectrum. These bands were selected based on historical considerations, the spectral absorption characteristics of some common inwater optical constituents, and the spectral transmittance of atmospheric oxygen and water vapor constituents.

Two families of glycoprotein are defined in Dictyostelium discoideum by the presence of different glycoconjugates, both of which are highly immunogenic in mice. The previously described monoclonal antibodies MUD50 and MUD62 recognize the glycoconjugates and identify the respective glycoprotein families. Both types of glycosylation occur on vegetative and developmentally regulated glycoproteins. The immunodominant components of both families are reportedly O-linked sugars, but Western blots do not identify any glycoprotein that has both O-glycans, suggesting that there are two independently processed types of O-linked glycosylation in D. discoideum. The synthesis of the two O-glycan families is affected by glycosylation-defective mutations. Strains with a mutation at the modB locus lack one of these glycosylation types (that recognized by MUD50) and this mutation alters the size of two minor glycoproteins in the second family. Two new mutants, HU2470 (mod-352) and HU2471 (mod-353), lack the epitope recognized by MUD62. The two mutations map to different chromosomes. The mod-353 mutation also affects the size of PsA, a cell surface glycoprotein carrying the modB-dependent O-glycan.

The monoclonal antibodies MUD1 and MUD50 recognize peptide and carbohydrate epitopes, respectively, on the Dictyostelium discoideum developmentally regulated cell surface glycoprotein PsA. PsA is a putative prespore cell adhesion molecule during the slug stage and is anchored to the cell membrane via a phosphatidylinositol glycan. Here we report on the presence of a PsA-like homolog in several Dictyostelium species. The MUD1 epitope is mostly confined to the D. discoideum complex, and only one non-D. discoideum strain reacted strongly with this antibody. By contrast, the mAb MUD50 recognises a homologous molecule in several Dictyostelium species that do not react with MUD1. With mAb MUD50 immunoaffinity chromatography, it was possible to purify and obtain an amino-terminal sequence for the PsA homolog from the Dictyostelium sp. strain ZA3A and from one strain of D. purpureum.

Flow cytometry is an excellent method for studying the physiological function in adipocytes because their response to hormones, especially insulin, varies with cell maturity and therefore size. Adipocytes present a unique technical challenge. A freshly prepared adipocyte suspension contains cells and fat droplets ranging from 10 to greater than 120 microns in diameter. Stored fat occupies 90-98% of the cell volume, making it difficult to distinguish cells from fat droplets. Other difficulties include buoyancy, large size, fragility, and tendency to aggregate and clog the sample tube and nozzle. These obstacles were overcome by 1) maintaining the sample, sample line, sheath fluid, reservoir, and nozzle assembly at 37 degrees C; 2) using a 200 microns diameter orifice; 3) using a short, 300 microns inside diameter Teflon sample delivery line; 4) injecting the sample at constant flow rate into the sheath fluid at low pressure; and 5) using the pH-sensitive vital stain, biscarboxyethylcarboxyfluorescein (BCECF) to distinguish cells from fat droplets. Stained cells are brightly fluorescent when excited at 488 nm. Because fat droplets do not fluoresce, they can be distinguished from fat cells by gating on the BCECF emission. The cytosolic pH of intact, viable, mature adipocytes was derived from the ratio of the fluorescent emission intensities at 520 and 620 nm and was estimated to be 7.2. Unlike BCECF, several other useful fluorescent probes of cell function, e.g., the intracellular calcium indicator, indo-1, label both fat cells and fat droplets.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibodies are used extensively in flow cytometry to identify subpopulations of cells differing in surface antigens. Conventional studies on living cells do not allow analysis of internal antigens, because antibody molecules do not pass through an intact plasma membrane. It is important for developmental studies on Dictyostelium discoideum that not only surface but also internal antigens be analysed. Here techniques are reported that make possible such studies by permeabilising cells with mild detergent treatments using digitonin. Flow cytometer profiles of unfixed cells show that antigens recognised by two monoclonal antibodies, MUD102 and MUD3, are found inside subpopulations of cells in the D. discoideum slug. Double-labelling experiments were carried out to demonstrate that the antigens recognised by these antibodies are present inside prespore but not prestalk cells. The detergent treatment leads to loss of forward-angle light scatter, but 90 degrees light scatter of cells is not greatly affected. While fixed cells sometimes gave satisfactory results, internal labelling did not reliably demonstrate the two subpopulations observed with unfixed cells.

Sea surface temperature (SST) maps and imagery derived from the NOAA 6 satellite Advanced Very High Resolution Radiometer (AVHRR) for June and July 1981 in the eastern tropical Pacific portray the wavelike structure of the cool water along the equator from 93°W to 125°W. Cusped waves of approximately 1000‐km zonal wavelength and 25‐day period propagated westward with a phase speed of 40 km/day. The observed meridional extent between the crest and trough of the waves is about 300 km. Details in the imagery show cooler water at the cusps advected north and then east with the north equatorial countercurrent (NECC), consistent with the suggestion of a series of anticyclonic eddies occupying the shear zone between the NECC and the westward flowing south equatorial current. Absolute SST estimates from the AVHRR data agree to within 0.6°C with shipboard data taken along 110° W between 5°N and 5°S. The wavelike structures in the SST maps are also in agreement at the surface with a vertical expendable bathythermograph temperature section made along the equator between 93°W and 125°W, which shows the phase of the waves tilting westward with increasing depth over the upper 75 m. Such a phase shift, if it extended 100–200 km meridionally in either direction from the equator, would be associated with an equatorward flux of heat. Similar phase shifts appear in temperature time series at depths of 20 and 50 m, from a mooring at 0°33′N, 110°30′W. Near‐surface currents measured at this and a second mooring on the equator at 109°40′W indicate a regular pattern of northward advection when wave cusps pass them, followed by southwest flow during the passage of wave troughs, again consistent with an equatorward flux of heat, as well as with earlier theoretical and drift buoy findings.

Cellular slime molds have been classified on the basis of a small number of descriptive criteria such as fruiting body color and morphology, and, in heterothallic species, by assignment to compatible mating groups. However, some isolates which are morphologically classified as conspecific do not fall into a simple mating-type classification; for example some are asexual or homothallic. An increasing interest in inter-strain genetic variation in studies of development and simple behavior has led us to reassess genetic relationships among a number of frequently used isolates. Allozyme electrophoresis of 16 soluble enzymes and use of a monoclonal antibody show that there is relatively little genetic diversity among sexually competent Dictyostelium discoideum isolates, despite considerable variation in geographic origin and time since isolation in the laboratory. In contrast a pair of asexual strains and each of two homothallic strains are genetically quite distinct and differ sufficiently from each other, and from sexually competent isolates, to warrant their recognition as separate species. There are probably four biological species represented in the supposedly D. discoideum isolates studied. This heterogeneity extends to other cellular slime mold species. Each of three isolates of Dictyostelium purpureum is genetically distinct from the others. Limited analysis of other cellular slime molds indicates that the generic distinction of Dictyostelium and Polysphondylium must be questioned. This study emphasizes that caution should be applied in classifying simple organisms on morphological criteria.

A series of satellite sea surface temperature (SST) intercomparison workshops were conducted under NASA sponsorship at the Jet Propulsion Laboratory. Three different satellite data sets were compared with each other, with routinely collected ship data, and with climatology for the months of November 1979, December 1981, March 1982, and July 1982. The three satellite data sets were (1) AVHRR—SST estimates produced operationally by the National Oceanic and Atmospheric Administration from the advanced very high resolution radiometer aboard the NOAA polar‐orbiting weather satellites; (2) HIRS/MSU—SST estimates produced by a research group at the NASA Goddard Space Flight Center from the 20‐channel high resolution infrared sounder and the 4‐channel microwave sounding unit, also aboard the same NOAA satellites; and (3) SMMR—SST estimates produced by another group at Goddard from the scanning multifrequency microwave radiometer on the NASA research satellite Nimbus 7. The satellite and ship data were differenced against an accepted climatology to produce anomalies, which in turn were spatially and temporally averaged into 2° latitude‐longitude, 1‐month bins. Monthly statistics on the satellite and ship bin average SST yielded rms differences ranging from 0.58° to 1.37°C and mean differences ranging from −0.48° to 0.72°C, varying substantially from month to month and sensor to sensor. The SMMR generally had the largest rms differences and time‐dependent biases, while the AVHRR and HIRS/MSU had smaller more comparable values. The monthly bins were further smoothed spatially to correspond to 600‐km averages to further suppress the noise of individual observations, particularly for the ship data. When this was done the monthly ship data standard deviations about climatology varied between 0.35° and 0.63°C. Taking these values as true SST signal standard deviation levels, and the satellite‐ship rms differences as noise levels, results in signal‐to‐noise variance ratios of about 0.25 for SMMR and 1.0 for AVHRR and HIRS/MSU. Maps of SST anomaly reveal a complex pattern of partial agreement and disagreement between ship and satellite data. Maps of satellite minus ship and satellite minus satellite SST differences were often dominated by coherent large‐scale patterns of obvious geophysical origin related to distributions of surface wind speed, atmospheric water vapor, cloudiness, and stratospheric aerosols. Unfortunately, the spatial scales of these patterns are often quite similar to those associated with actual SST anomalies. Caution must therefore be exercised when dealing with the satellite data so that errors are not misinterpreted as true SST anomalies.

The upper ocean temperature and dynamic height fields are correlated in the western North Pacific Ocean. This relationship can be used to map a relative geostrophic stream function of the Kuroshio Extension using temperature data from expendable bathythermograph (XBT) surveys. We have examined the ability of the North Pacific ship of opportunity XBT program, known as TRANSPAC, to carry out this procedure. Estimates of 600/1200 dbar geostrophic shear were generated from the XBT data utilizing objective mapping techniques. These estimates were compared with measured currents at 600 m relative to 1200 m along 152°E from 27°N to 42°N. The estimated and measured relative currents are positively correlated, with an rms error of ±6 cm/s over a measured dynamic range of 30 cm/s. However, the XBT estimated shears consistently underestimate the measured values by a factor of 2 to 3. The underestimate of the amplitude is the result of both undersampling and mapping produres that eliminate high wavenumber contributions of the dynamic height variability. These factors appear to be responsible for previous differences in amplitude between directly measured and TRANSPAC XBT estimated values of relative eddy kinetic energy and Reynolds stress. The TRANSPAC XBT survey can only monitor qualitatively the dynamic topography of the Kuroshio Extension meanders and rings. The variability outside of the extension with a temperature range of 3°C cannot be resolved because of inaccuracies in the temperature‐dynamic height relationship. To monitor the Kuroshio Extension variability in the future, it is recommended that TRANSPAC XBT resources in the western North Pacific concentrate on obtaining a denser sample of the field during the fall and winter seasons because of incomplete ship track coverage in spring and summer.

A procedure for estimating sea surface temperature was developed by using the near and thermal infrared data available from full resolution (1.1 km field of view) daytime passes of the NOAA 6 satellite Advanced Very High Resolution Radiometer. It is demonstrated that spatially unresolved clouds and variable amounts of water vapor in the atmosphere are the major error sources. The procedure therefore incorporates a means of identifying radiometer fields of view which are virtually cloud‐free, by comparing measured solar radiation at 1 μm, backscattered from the atmosphere, against that expected from a simple scattering model. A set of 82 cloud‐free fields of view is then assembled, spatially and temporally nearly coincident with research quality (±0.2°C) in situ ship and buoy sea surface temperature reports collected during 1979 and 1980. The set is then used to develop and evaluate a simple model to reduce variable water vapor effects by relating in situ sea surface temperature to the infrared brightness temperatures measured by the radiometer at 3.7 and 11 μm. Residual disagreement between satellite estimates and in situ measurements of sea surface temperature is about 0.6°C for the data set which extends from the equator to 50°N in the northeast Pacific. The procedure is then applied to 10 satellite passes in the northeast Pacific during April 1981 to obtain monthly mean sea surface temperature and temperature anomaly (departure from climatological norm) maps. These maps are compared against similar ones produced from routine ship reports, mostly consisting of engine injection temperature data, typically good to no better than 1°C. The maps agree to ±0.8°C (1 sigma), with the level of agreement clearly limited by the poor accuracy of the ship reports. It now appears that the radiometer data, when properly handled, can be used as a more accurate substitute for routine ship reports of sea surface temperature in applications such as climate variability studies requiring 0.5–1.0°C accuracy.

Sea surface temperature data from the SEASAT Scanning Multichannel Microwave Radiometer (SMMR) has been mapped for the period July 7 to August 6, 1978, in the western North Pacific, 20°N–50°N, 140°E–180°, and compared against similar maps constructed from all available ship observations. The temperature difference between the SMMR and ship maps has a standard deviation of 0.75°C, about a mean bias of 0.22°C, SMMR being warmer. The average standard deviation of all individual observations about the mapped values is 1.51°C and 2.10°C for SMMR and ship, respectively. Both the SMMR and ship maps exhibit the known major climatological features for the region. In addition, both data types yield similar maps of sea surface temperature anomaly (departure from climatology), with large‐scale (>500 km) anomaly features of 1°–3°C. Aside from having a lower noise level, the SMMR data is superior to the ship data for constructing large‐scale maps because it is more uniformly distributed in space and time.

Radar altimeters of great precision (≈10 cm), such as the one that flew on the SEASAT satellite, are capable of measuring the small oceanic height variations associated with geostrophic ocean currents. An experiment was conducted in the Kuroshio Current east of Japan, verifying this capability. Air‐expendable bathythermographs (AXBT's) were dropped to coincide with the SEASAT subtrack during flights on September 25 and October 5 and 13, 1978. Changes in surface dynamic height between flights were inferred from the AXBT data. They agreed generally to within ±10 cm of height changes observed in the altimeter data.

The space scales associated with the semidiurnal internal tides in the central Pacific are investigated by using time series of temperatures obtained from moored buoy arrays. Excellent phase coherence was found in the vertical from near the surface to depths exceeding 150 m. Phase coherence existed horizontally over distances of at least 5 but less than 50 km. With one exception the thermobaric energy associated with the semidiurnal tide showed no coherence in either the vertical (0–150 m) or the horizontal (5–500 km).

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The time and length scales of baroclinic eddies in the eastern half of the North Pacific Subtropical Gyre are examined using four data sets: 1) single vertical sections of temperature, based on closely spaced bathy-thermograph (BT) casts (cast spacing 100 km. The spectra attenuate toward higher wavenumbers as the square of the wavenumber over the range 200 to 600 km. Spatial autocorrelation in both horizontal dimensions of the second data set yields a correlation matrix with a first zero crossing at 150 km in both dimensions, im...