Separate Stations Research Articles

Phytochelatin concentrations in the equatorial Pacific

Phytochelatin, an intracellular metal-binding polypeptide synthesized in eucaryotic algae in response to metals such as Cd and Cu, was measured in particulate samples collected from the equatorial Pacific. The concentrations in these samples (normalized to total particulate chl a) were unexpectedly high compared to laboratory culture data and were on average slightly more than in coastal areas where the metal concentrations are typically much greater. In part, the high field concentrations can be explained by the low cellular concentrations of chlorophyll a resulting from very low ambient Fe, but laboratory experiments provide a possible explanation for the rest of the difference. At low concentrations of inorganic Cd (Cd′=3 pM), increasing amounts of phytochelatin were induced by decreasing Zn concentrations in the culture medium of two diatoms: Thalassiosira weissflogii, a coastal species, and T. parthenaia, an isolate from the equatorial Pacific. In all previous studies, phytochelatin production has been directly correlated with increasing metal concentrations. Decreasing Co also resulted in higher phytochelatin concentrations in T. weissflogii and Emiliania huxleyi. Replicating the field concentrations of Zn, Co, and Cd in the laboratory results in cellular concentrations (amol -1 cell) that are very similar to those estimated for the field. Contrary to the expectation that high metal concentrations in the equatorial upwelling would cause elevated phytochelatin concentrations, there was no increase in phytochelatin concentrations from 20° S to 10° N—near surface samples were roughly the same at all stations. Also, most of the depth profiles had a distinct subsurface maximum. Neither of these features is readily explained by the available Zn and Cd data. Incubations with additions of Cd and Cu performed on water sampled at four separate stations induced significantly higher concentrations of phytochelatins than those in controls in a majority of the samples. The differences between metal additions and controls were greater within the upwelling zone, where water presumably has had less time to accumulate biogenic complexing agents. However, the uniformity of phytochelatin concentrations in and out of the upwelling region suggests that the phytoplankton or the biota are successfully maintaining a tight control over the trace metal chemistry both intra- and extracellularly across a wide range of oceanic conditions.

Seasonal and Spatial Patterns of an Epibenthic Decapod Crustacean Assemblage in North-west Atlantic Continental Shelf Waters

To examine seasonal and spatial patterns in a mobile marine assemblage, monthly samples were taken in triplicate with a 2-m beam trawl (6-mm mesh) at three separate stations (landward of the ridge, on the ridge top, and seaward of the ridge). The assemblage was of epibenthic decapod crustaceans, and was situated at a north-west Atlantic continental shelf, sandy ridge site. The assemblage was composed of nine species and was extremely variable over time and space. The sevenspine bay shrimp (Crangon septemspinosa), the Atlantic rock crab (Cancer irroratus), the spider crab (Libinia emarginata) and the lady crab (Ovalipes ocellatus) were the numerical dominants, comprising >98% of all decapods collected. Three of these species (C. septemspinosa,C. irroratus,L. emarginata) exhibited marked spatial heterogeneity in abundance, with many fewer found on the ridge top than at either of the other two stations.Ovalipes ocellatuswas not as spatially variable.Crangonshowed two clear peaks, in spring and fall, as didLibinia, but neither appeared to use the site as a nursery area.Ovalipes ocellatusandC. irroratuseach showed a single peak of very small individuals in the summer and appeared to use this site for settlement. Komolgorov-Smirnov tests, analysis of variance and cluster analysis showed much less difference in assemblage structure between the landward and seaward stations than was demonstrated between either station and the ridge top. The presence of the sand ridge had a clear impact on the abundance and distribution of local decapod crustacean populations.

Spatial and temporal distribution of algal biomass in a large, subtropical lake

Epipelon, epiphyton, and phytoplankton biomass were measured quarterly for one year from 20 stations located throughout Lake Okeechobee, a large, subtropical lake located in south-central Florida, USA. Seasonal variability was evident in all algal components. The water column accounted for the majority of chlorophyll-a (>90 %) in December, March, and September, but accounted for only 61.1% of total chlorophyll-a in June. Conservative estimates of total chlorophyll-a biomass ranged from 1300 to 36,600kg kg for attached algae, and from 41,770 to 206,600kg kg for phytoplankton. Overall, the greatest epipelon biomass was measured in June, the greatest epiphyton biomass was measured in March, and the greatest phytoplankton biomass was measured in December in the pelagic region and in June in the littoral region. Stations deep within the littoral zone had greater epipelic and epiphytic biomass than those located along the fringe zone between the pelagic and littoral zones. Principal components analyses revealed that stations located within the marsh formed the most distinct groupings. Light-related factors were important in separating stations along axis 1, whereas water chemistry helped separate stations along axis 2. Overall, these results suggest that epipelon, epiphyton, and phytoplankton communities are responding differently to the forcing functions in this large, subtropical lake. Management decisions influencing lake level may affect these communities differentially, which in turn, may influence ecosystem processes.

Morphological Analysis of the Transfer of VSV ts-045 G Glycoprotein from the Endoplasmic Reticulum to the Intermediate Compartment in Vero Cells

Vero cells were infected with the ts-045 strain of vesicular stomatitis virus, and the cells were incubated at 39°C to accumulate the mutant G glycoprotein in the ER as a misfolded aggregate. Cycloheximide was added to the culture medium 3.5 h after infection to prevent further protein synthesis, and the temperature was lowered to 10, 15, or 31°C. At these temperatures, the mutant G glycoprotein correctly folds and oligomerizes. Immunofluorescence light microscopy showed that the G glycoprotein was exported to the Golgi complex at 31°C and to the intermediate compartment (IC) at 15°C, but no export was observed at 10°C. However, incubations at 10°C followed by shift to 15 or 31°C resulted in the normal transfer of the glycoprotein to the IC and the Golgi, respectively. Immunoelectron microscopical analysis confirmed all these results, but showed also that the glycoprotein was frequently clustered in the ER at 10°C. Conventional electron microscopy showed that the morphology of the ER, IC, and Golgi complex remained essentially unchanged at all temperatures. The only significant difference detectable in cells incubated at 10°C was the increased number of partially coated ER protrusions, longer than those detected at higher temperatures. These results demonstrate that the transport toward the Golgi complex of G glycoprotein can be arrested at a step preceding the entry into the IC, thus suggesting that ER and IC are separate stations in the exocytic pathway.

Es-reflections in the region of the main ionospheric trough

This paper is concerned with the results of an investigation into some observations of the Es-layer with a group delay (Esr) in the main ionospheric trough (MIT) based on data from a high-latitude meridional chain of ionosondes (L = 90°E, Φ = 62–74°N). Esrlayers are broken down according to their association with magnetic activity and extent in time and space. The dependence of Esr-layer occurrence on the value of Kp-index and AE-index is investigated. Possible mechanisms for their formation are discussed. It is concluded that short-lived Esr-layers observed at separate stations in the dayside sector in the presence of low magnetic activity can be identified with isolated patches and arcs as detected in the main ionospheric troughs region from satellites.

The GDP/GTP cycle of Rab5 in the regulation of endocytotic membrane traffic.

In eukaryotic cells, endocytosis plays a central role in the maintenance of cellular organization and function. The endocytotic route is composed of separate stations that carry out specialized functions such as uptake of nutrients, clearance of metabolites from the medium, internalization and down-regulation of receptors, turnover of membranes, and antigen processing. Proteins, lipids, and solutes internalized at the cell surface are first transported into early endosomes. The best-characterized route to this compartment is the clathrin-coated-vesicles-mediated route (Robinson 1994), but non-clathrin-mediated mechanisms also contribute to the endocytotic traffic (Watts and Marsh 1992; Sandvig and van Deurs 1994). From the early endosomes, internalized constituents can be either recycled to the cell surface, possibly through a recycling compartment distinct from the early endosome (Yamashiro and Maxfield 1984; Dunn et al. 1989; Hopkins et al. 1994), or transported to late endosomes and lysosomes for degradation. The endocytotic pathway is also connected to the exocytotic...

Physiological Predictors in Calves of Dairy Breeds: Part 1. Genetic Parameters of Basal and Induced Growth Hormone Secretion

Abstract Genetic variation in plasma growth hormone (GH) concentration before and after GRF (growth hormone releasing factor) stimulation was studied in young bulls (N=284) and heifers (N=212), the progeny of 53 sires of four dairy and dual-purpose breeds (Danish Jersey, Red Dane, Danish Friesian and Danish Red and White). Male and female calves were reared, fed and tested on separate experimental stations; thus sex, station and feeding were completely confounded effects. The animals were tested at about 9 months of age, after a 24 h fast. GH concentration was measured in serial plasma samples collected for 1 h before and 1 h following intravenous administration of 2.0 ug synthetic GRF(1–29)NH2/kg live weight>0.75. Prior to statistical analysis, concentrations were loge-transformed. Response variables were BASELINE (mean GH in -15, -5 and 0 min samples) and PEAK (mean GH in 10, 15 and 20 min samples). A statistical model taking at least three generations of ancestral relationships into account was used to...

Space‐time evolution of void fraction under a plunging breaking wave

Bubble plumes generated by natural wave breaking in the ocean under moderate to strong wind are found to be important for acoustic reverberation near the air‐sea boundary layer. The most significant underlying physical parameter is the void fraction of the bubbly medium. So far, very little quantitative data of the void fraction due to wave breaking are available. In this paper, some results shall be presented on the spatial‐temporal evolution of void fraction under a plunging breaking wave. The experiment is conducted in a large wave tank (12 × 15 × 350 ft) with a programmable wave maker at the Oregon State University Wave Research Facility. The plunging breaking wave of a 3‐s wave period with a maximum wave height of about 5 ft is created within a wave packet. The void fraction is measured at three depths below the wave surface at six separate stations 10 ft apart. It is found that the maximum void fraction reach of about 40% to the depth of the maximum wave height over spatial distance is close to the wavelength of 60 ft. The e‐folding time for the decay of the void fraction of the initial bubble plume is less than the one‐half of the wave period, but a significant void fraction (70.1%), which causes large sound‐speed deficits persisting up to six wave periods, is also found. The void fraction is measured by a resistance gauge based on a theory originated by James Maxwell. [This project is funded by the Office of Naval Research Acoustic Reverberation program.]

A multiprocessor system for the on-line collection and handling of the LNS Crystal Ball data

The data acquisition system for the 4 pi multidetector Crystal Ball of the LNS (Laboratorio Nazionale del Sud) is described. This system is built around a modular multiprocessor architecture. VMEbus-based, using a one-broadcasting/many receivers data-passing scheme, in order to allow different functions to be performed asynchronously and concurrently on separate receiver stations. A well-tested software architecture is used, to keep simple the interaction of the user with the whole system. >

Robotic work station for microscale synthetic chemistry: On-line absorption spectroscopy, quantitative automated thin-layer chromatography, and multiple reactions in parallel

A robotic work station has been constructed for automatically initiating and monitoring microscale chemical reactions. The work station consists of a robot with a general-purpose arm and interchangeable special-purpose hands, a carousel of seven reaction vessels, a series of stations for performing quantitative automated thin-layer chromatography (TLC), an on-line multichannel absorption spectrophotometer, sensors for verification, syringes and pumps for sample and solvent delivery, a supervisory computer for real-time data acquisition and process control, and a graphics terminal for data display. The controlling software is menu-driven and contains a scheduling algorithm that permits multiple reactions to be performed simultaneously. The automated TLC process is performed in four stages (plate dispensing, sample application, plate development, and plate densitometry), and samples are moved sequentially among these stations by the robot. The partial autonomy of these separate stations permits distributed sample processing. Four TLC plates are processed simultaneously with interleaving segmented schedules, giving a 160% increase in TLC sample throughput. The workstation can be applied to yield optimizations of synthetic reactions and to the exploration of synthetic reaction spaces. The capabilities of the workstation are demonstrated in the two-step synthesis of tetraphenylporphyrin from benzaldehyde and pyrrole in 1 h at room temperature. Kinetic data are obtained from a single-batch reaction concerning the consumption of benzaldehyde, the side reactions forming dipyrrylmethenes, and the formation of tetraphenylporphyrin.

Shared meal preparation in residential kitchens: implications for kitchen planning

A comparison was made of the use of residential kitchen work centres by one worker and by two workers during a dinner meal preparation in which a microwave oven was utilized. When the meal was prepared by two workers they divided the work load by menu item and utilized separate work stations; typically, only one worker prepared the menu items requiring actual cooking. However, whether the meal preparation was individual or shared, the sink and preparation centres were the most frequently used.

Annual fluctuations of the subtidal macroinfauna in an Estuary of South of Chile

Monthly samples taken at two separate stations in the Queule River Estuary, between May 1980 and April 1981, were used to study annual fluctuations of the subtidal macroinfauna. In both stations, t...

Tropical Atlantic wind field variations during sequal: Preliminary results

An evaluation of the U.S. Navy NOGAPS surface wind product is made to establish its utility as an initial descriptor of the surface wind field in the tropical Atlantic during SEQUAL. In this preliminary study, NOGAPS synoptic fields are compared to synoptic ship reports, and to winds measured at three separate stations along the equator during SEQUAL I. At least within 20° of the equator the comparisons suggest that the mean monthly surface winds from NOGAPS almost always differ by less than 2 m/s from averages of surface wind observations, and can be less than 1 m/s. Similar comparisons are also found from daily mean winds derived from NOGAPS, along the equator near 30°W. A comparison of NOGAPS monthly mean winds with 100‐year climatology of merchant ship reports suggests that the major surface wind anomaly during SEQUAL I in the tropical Atlantic occurred in March and April 1983 along the equator west of 30°W.

Global properties of the magnetosphere during a substorm growth phase: A case study

At approximately 0100 UT on December 29, 1976, a large injection of energetic (>30 keV) particles was observed by Los Alamos instrumentation onboard spacecraft 1976‐059 (35°W longitude) at geostationary orbit. This injection was closely associated with the onset of a major substorm (also at 0100 UT) identified by sharp negative bays in the H components of magnetic records at Leirvogur (22°W) and Narssarssuaq (45°W) and by the occurrence of a positive H component bay at 0100 UT in the mid‐latitude magnetogram record at M'Bour (17°W). This substorm expansion onset (and concomitant particle injection) was preceded (between 2330 and 0100 UT) by a pronounced ‘stretching’ of the magnetic field at synchronous orbit into a taillike configuration and by a development of highly cigarlike (field‐aligned) electron distributions at geostationary orbit that we have in the past identified with the substorm growth phase. Of principal importance in this case are two other auxiliary data sets. The first is a well‐timed set of DMSP auroral images taken during the course of the growth and expansion phases of the substorm. The images before and during the growth (cigar) phase, including one auroral zone crossing at ∼0050 UT, show quiet aurora with no observable substorm activity in the visible polar region. The second relevant data set is a broad set of riometer data from 13 separate stations in three general meridians (west coast Greenland, east coast Greenland, and northern Scandinavia) from magnetic latitudes of ∼65° to ∼90°. The riometer data also show clearly that there was no measurable substorm activity anywhere, either in longitude or latitude, as the magnetosphere developed its very stressed, growth‐phase configuration prior to substorm expansion onset. These results support the concept of a storage of energy (growth phase) prior to its rapid release at substorm onset. IMP 8 observations in the high southern magnetotail lobe at ∼35 RE geocentric radial distance provide strong corroborative evidence of this storage and subsequent release of magnetic energy.

Characterization of lightning return stroke electric and magnetic fields from simultaneous two‐station measurements

We present a characterization of Florida lightning return stroke electric and magnetic fields derived from simultaneous measurements of the fields at two separate stations, one station being within 15 km of the lightning, the other at either about 50 or 200 km from the lightning. We give (1) examples of correlated wave forms, (2) typical first and subsequent stroke wave forms over the distance range 1.0–200 km, and (3) the following statistical data from which the typical wave forms were derived: for electric field, rise time, initial peak value, ramp starting time, ramp slope, value at 170 μs, ratio of value at 170 μs to initial peak, zero‐crossing time for 50 and 200 km wave forms; for magnetic fields, time of hump following initial peak, ratio of hump value to initial peak value, zero‐crossing time for 50 and 200 km wave forms. Return stroke electric and magnetic field characteristics appear to be independent of location in Florida.

A three-year study of benthos of muddy environments in Port Phillip Bay, Victoria

Samples taken four times a year over three years (1973–1975) at three widely separate stations in muddy environments in Port Phillip Bay were used to compare species diversity and composition of the benthic community between areas, seasons and years. Analysis of variance of five community statistics: the number of individuals, the number of species, Shannon's diversity and two evenness measures; showed that differences between the three stations and between years contributed the largest fractions of the variance in number of individuals and species but little to diversity or evenness. Seasonal differences contributed negligibly to variance in any statistic except diversity. Smallscale spatial patchiness (from replicate samples within stations) contributed a significant fraction of variance to all five statistics. The fauna at all stations was dominated by the deposit-feeding bivalve Theora fragilis and the decapod shrimp Callianassa limosa; only minor species were restricted to single stations. The density of few species varied seasonally but several were more abundant in some years than others. Hierarchical classification using the Canberra metric dissimilarity coefficient grouped samples into station groups. Use of the Bray-Curtis coefficient grouped some samples by station and some by season and it was concluded that the main differences between stations were in overall species composition, not in the densities of dominant species. Temporal changes in community structure were non-seasonal but, rather, were irregular changes occurring at single stations. Differences in fauna between stations were related in part to small differences in sediment-type but not to physico-chemical features of the overlying water. The irregular fluctuations in density of the common species and in the identity of the minor species suggest that multiple-stable points in community structure may exist for the silty-clay community. The two major species seemed not to have altered each other's environment over the sampling period. Considerable variation in species composition may occur in soft-bottom benthos in the absence of marked environmental perturbations.

The enigma of Daphnia death rates1

Birth rates, rates of population change, and mortality rates were computed for Daphnia pulex and Daphnia rosea collected at three separate stations in. 2.5‐ha meromictic Crawford Lake. Birth and death rates for the same species at the three separate stations, or at the same station but living at slightly different mean depths were substantially different. A correction for tow net efficiency for young and adult animals increased birth rate values by 40%.Mean finite birth rate, B, for Daphnia in a thermally stratified lake is calculated from the relation urn:x-wiley:00243590:media:lno19782350970:lno19782350970-math-0001 where for each stratum, s, E is number of eggs, D is egg development time, N is number of animals, and n is number of strata. An assumption of this formulation is that all individuals in the population behave similarly, hut at Crawford Lake D. pulex behaves like two separate populations for at least part of the year.High death rates were calculated for D. rosea in midsummer. A comparison of observed neonates with expected neonates during this period led to the conclusion that most mortality in the population occurs either in late embryos or at hatching.

Geomagnetic investigations in the seismoactive regions of middle Asia.

Investigations of local geomagnetic field changes have been carried out in Middle Asia in the following regions: Tashkent, including Charvak reservoir, Fergana and Kyzyl-Kum. Since 1968, a variety of total field features have been observed there, including: (a) slow changes at separate stations, which may be explainable by compression or tension of individual earth’s crustal blocks; (b) a variety of field changes with amplitudes of a few gammas and periods of 0.5–2 years; (c) variations, which may be due to different conductivity of rocks; (d) anomalous changes in the fracture zones; (e) anomalous variations in the Charvak region, connected with reservoir filling. The amplitudes of these variations are 3–5 nT/year at Fergana, 8–9 nT/year at Kyzyl-Kum, 20–25 nT/year at Tashkent regions and up to 15–25 nT/year at Charvak reservoir area. Sometimes these anomalous changes are correlated with seismic activity (for example, Tashkent 1968 earthquakes).

High-Speed Profile Measurement with Electro-Optics

A high-speed profile monitor has been developed for Frank-ford Arsenal as an integral part of an automatic 5.56 mm cartridge case ammunition inspection system. This profile gaging monitor uses a dual measurement station each with solid state linear diode arrays and shadow-imaging optics to achieve a throughput rate that exceeds 1200 cases/minute with a diameter measurement standard deviation better than ± 1.5 x 10-3 inch. Fourteen diameters and two lengths are measured on each cartridge case by separate gaging stations. Length measurements use a snapshot-type optical system while diameter measurements require both image tracking of the case shadow and scanning operation to get the diameter measurements from two diode array elements. A mini-computer with a direct memory input from the gaging stations provides an engineering unit conversion from the gaging stations and a dynamic accept/reject decision based on minimum accept and maximum accept limits.

Propagation of transient, cylindrical waves in an infinite, viscoelastic body

This study involves a linear viscoelastic body of infinite extent through which runs a cylindrical hole of circular section. The object of the study is to find the response of the body to a uniform pressure, applied to the wall of the hole, which has an arbitrary dependence on time. The method of characteristics is chosen for the solution and responses are found at two separate stations for three different viscoelastic materials. When the responses can be compared with those of others, they appear to be correct, and when they cannot, they are qualitatively what one would expect from intuition.