The relationship of environmental variability to the spatial patterns of phytoplankton biomass in Lake Tahoe

Horizontal transects measuring phytoplankton biomass and temperaturewere made in Lake Tahoe in the nearshore epilimnion in 1976and 1977, near the deep chlorophyll maximum in midlake in 1977,and in the deep thermocline in 1976. Variance spectra from thesetransects indicate that large length scale patchiness dependson large-scale habitat variability, manifested as nitrate patchiness,caused by stream inflow in the nearshore epilimnion and by differentialtransport processes in the deeper water. When large-scale sourcesof habitat variability are absent, phytoplankton spatial patternsare not dominated by large-scale patches and are consistentwith a random distribution. No significant small-scale patchinesswas seen under any environmental conditions. ^*Current address: Jet Propulsion Laboratory, 183/501, 4800 OakGrove Drive, Pasadena, CA 91109, and Scripps Institution ofOceanography, A-002, University of California, La Jolla, CA92093 USA     

The influence of water circulation on chlorophyll-turbidity relationships in Lake Okeechobee as determined by remote sensing

The spatial distribution of phytoplankton can be difficult toassess in shallow, productive aquatic systems due to frequentalgal blooms, high turbidity and sediment-resuspension events.We conducted a study to assess the distribution of suspendedparticles in Lake Okeechobee, Florida, utilizing both Landsat(1974–75) or Advanced Very High Resolution Radiometer(AVHRR) (1987) satellite remote sensing. Surface water sampleswere collected by helicopter to determine in situ chlorophyll-aand turbidity levels at 20 stations on four dates in 1974–75and six dates in 1987. Remotely sensed reflectance values agreedwell with in situ particle densities at the 20 in-lake stations(average R²: Landsat = 0.81, AVHRR = 0.53) and independent,synoptic boat mapping of algal blooms (r² = 0.79, P < 0.01).Basin-wide maps of chlorophyll and turbidity, as well as additionalspatial sampling, both indicated that these parameters are notnecessarily coupled in Lake. Our data concur with the hypothesisthat the spatial distributions of chlorophyll and turbidityare shaped by different forces. The highest concentrations ofchlorophyll occurred in the vicinity of tributary nutrient inputsat the lake's perimeter, while turbidity increased towards thecenter of the lake, reflecting predominant water circulationpatterns. ²Present address: Department of Biology & Romberg TiburonEnvironmental Center, San Francisco State University, San Francisco,CA 94132, USA ³Present address: Idaho Division of Environmental Quality, 1420North Hilton, Boise, ID 83706-1260, USA ⁴Present address: 5642 Santiago Circle, Boca Raton, FL 33433,USA     

Effect of Nasal Dilators on Perceived Odor Intensity

Subjects wearing nasal dilators rated olfactory stimuli as beingmore intense compared with ratings done without nasal expansion.The results support a perceptual constancy model in olfaction.Chem. Senses 22: 177–180, 1997. ¹Present address: Biology Department, St Lawrence UniversityCanton, NY 13617, USA ²Present address: PO Box 802, Drew University, Madison, NJ 07940,USA     

Effects of nitrogen and phosphorus starvation on nucleic acid and protein content of Heterocapsa sp.

Changes in the protein, RNA and DNA content related to nitrogen(N) and phosphorus (P) starvation were studied in the marinedinoflagellate Heterocapsa sp. grown in batch cultures. In bothcases of nutrient starvation, metabolic adaptations affectedprotein and RNA pools, while the DNA content per cell remainedapproximately constant. N starvation led to a parallel decreasein protein and RNA concentration which caused the protein/RNAratios to remain constant. A dramatic decrease in the RNA contentcharacterized the P-starved cultures, although protein synthesiscontinued. The ribosomal RNA content was lower than expectedgiven the continuation of protein synthesis. It is suggestedthat protein/RNA ratios could be used as an indicator of P starvation,while protein/chlorophyll ratios would characterize N starvation ¹Present address: University of Hawaii at Manoa Soest, BiologicalOceanography, 1000 Pope Road, Honolulu, HI 96822, USA     

Comparison of methods for extracting intracellular pools of inorganic nitrogen from marine phytoplankton

Marine phytoplankton can accumulate large intracellular poolsof nitrate and ammonium under some growth conditions. A numberof different methods have been used to extract these pools whichdiffer primarily in the way the cells are broken to releasethe pools. In this study, seven methods of extracting nitrateand ammonium pools were examined in four species of marine phytoplanktongrown so that extraction of both large and small pools couldbe tested. The methods of breaking cells examined included variouscombinations of osmotic shock, heat treatment, grinding, sonication,and freeze–thawing. Of these, two methods which use osmoticshock or osmotic shock combined with heating, yielded the highestpool concentrations, the best percent recoveries, and the leastvariability. Osmotic shock combined with heat is the recommendedextraction procedure since it may be more effective with cellswhich are difficult to break. ¹Current address: Bigelow Laboratory for Ocean Sciences, MckownPoint, West Boothbay, Maine 04575, USA     

Immunocytochemical Localization of Uricase in Peroxisomes of Soybean Cotyledons

Antibodies specific for nodule uricase were used for immunocytochemistryto demonstrate the presence of uricase in cotyledons of soybean(Glycine max) during germination and early seedling growth.The enzyme was localized exclusively in peroxisomes. ¹Permanent address: Department of Plant Cytology and Cytochemistry,University of Lodz, Lodz, Poland ²Current address: Department of Plant Science, University ofArizona, Tucson, AZ 85721, U.S.A.     

Excess RNA Editing in Rice Mitochondrial atp9 Transcripts

RNA editing for subunit 9 of ATPase from rice mitochondria wasexamined. C residues at eight positions in the genomic DNA wereconverted to T in the cDNA sequences. Excess RNA editing atnucleotide positions 216 and 254 was identified. The identicalpeptide sequence was deduced from 22 independent cDNA clones. ¹Permanent address: Faculty of Agriculture, Meiji UniversityKawasaki, 214 Japan.     

Sucrose concentration and xylem regeneration in Coleus internodes in vitro

The induction of xylem elements in inflicted wound areas ofisolated Coleus internodes was dependent upon the presence ofsucrose in the agar growth media. The number, size and wallstructure of regenerated xylem vessels were related to the concentrationof sucrose, the presence or absence of IAA, and the orientationof the stem segments on the experimental media. ¹Current address: Forest Physiology Laboratory, Forest Service,Beltsville, Maryland, U.S.A. ²Current address: Department of Botany, Rutgers University,New Brunswick, New Jersey, U.S.A. (Received September 2, 1968; )     

Response of marine phytoplankton to low levels of arsenate

Phytoplankton species vary widely in their degree of inhibitionto low levels of dissolved arsenate (1 – 10 ? ambient).Similarly, natural phytoplankton assemblages cultivated outdoorsunder ambient temperature and nutrient conditions indicate thatthe observed variance in sensitivity is sufficient to causea marked change in species composition and succession in dosedassemblages relative to controls, again at very low levels ofarsenate. The changes in species that occurred, however, werenot always similar to the response predicted from single–speciescultures. In addition, a species' level of resistance to arsenateis often not comparable with its resistance to other anthropogenicstress. It is therefore questionable whether predictions concerningenvironmental consequences of a given pollutant can be madeon the basis of laboratory bioassays of a single species. ¹Contribution # 4695 Woods Hole Oceanographic Institution ²Present address: Academy of Natural Sciences, Division of EnvironmentalResearch, Benedict Estuarine Research Laboratory, Benedict,MD 20612, USA     

Determination of membrane-bound chloroplast RNA by the ethidium bromide fluorometric method

The method of El-Hamalawi et al. [(1975) Anal. Biochem.67, 384–391] for the fluorometric determination of nucleic acids with ethidium bromide has been adapted for the assay of membrane-associated chloroplast RNA. Membranes are stripped of RNA by incubation in a high-salt buffer lacking Mg²⁺, and the RNA is collected by magnesium phosphate-ethanol coprecipitation. RNA levels are determined by measuring the degree of enhancement of ethidium bromide fluorescence.     

Phytochrome Control of Its Own Synthesis in Pisum sativum

An analysis of phytochrome synthesis in Pisum seedlings by measuringthe activity of polysomal polyadenylated RNA (poly-A⁺-RNA) codingfor phytochrome apoprotein showed phytochrome control of itsown synthesis; brief red-light irradiation of pea seedlingsinhibited the activity of the RNA, and the red-light effectwas red/far-red reversible. ⁴ Permanent address: Biology Department, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan. (Received August 13, 1984; Accepted September 17, 1984)     

In situ measurement of filtering rates of the salp, Thalia democratica, on phytoplankton and bacteria

Salps were gently captured in a perspex chamber by a SCUBA diver,who then injected a suspension of ¹⁴C-labeled phytoplanktonand ³H-labeled bacteria into the chamber. After 0.5 h incubationin situ, filtering rates were estimated from incorporation ofthe two isotopes, and expressed as a function of each salp'ssize. Both bacteria and phytoplankton were grazed by Thalia,the latter at higher rates. Weight-specific grazing rates increasedwith increasing size of salp. Estimated hourly rations rangedfrom 1% of bodily C for small Thalia feeding only on phytoplanktonto 8% of bodily C for large Thalia feeding on all particulateorganic C. The method gave repeatable results for Thalia, butwas unsatisfactory for the pteropod, Cavolinia. ¹Present address: Institute of Marine Resources, A-018, Universityof California, San Diego, Scripps Institution of Oceanography,La Jolla, CA 92093, USA.     

Recent introduction of the planktonic calanoid copepod Sinocalanns doerrii (Centropagidae) from mainland China to the Sacramento-San Joaquin Estuary of California

The planktonic calanoid copepod, Sinocalanus doerrii, a nativeof the rivers of mainland China was found in 1978 in California'sSacramento-San Joaquin Estuary during routine plankton sampling.Previous plankton surveys in 1963 and from 1972 to the presentindicate that the introduction occurred a relativery short timebefore specimens were first caught. The most probable mode ofintroduction is ballast water from Japanese freighters previouslydocking in China. S. doerrii became abundant in the Sacramentoand San Joaquin Rivers in 1979 and may be regarded as well established.Its impact on the native plankton is as yet unknown. ⁴Present address: Department of Biological Science, FloridaState University, Tallahassee, FL 32306, USA. ⁵Present address: 5 Hemingway Street, Branford, CT 06405, USA.     

Comparison of radioactive and stable isotope tracer techniques for measuring photosynthesis: 13C and 14C uptake by marine phytoplankton

The stable carbon isotope ¹³C has been used in the open oceanto estimate the inorganic carbon uptake by phytoplankton andthis technique has been compared with the ¹³C tracer method.An overall correlation coefficient of 0.806 and a regressionslope of 1.29 were calculated from 50 sample pairs gatheredduring three cruises in widely different oceanic areas rangingin production rates from 0.01 to 6 mgC m^–3 h^–1.However, significant differences between the two methods wereapparent for cruises located in nutrient-depleted areas. Possibleexplanations lie either in a volume effect, the high silicatecontent of the ¹⁴C solution which could stimulate the ¹⁴C uptakeor in errors associated with the particulate carbon measurementswhich are necessary to convert specific uptake rates to absoluteuptake rates and to yield compatible units for the comparison,in laboratory cultures the ¹⁴C technique overestimated the netparticulate carbon increase by — 16%. ⁺Present address: Laboratoire marin CNRS-IFREMER, L'Houmeau,17137 Nieul-sur-Mer, France. ^*This paper is the result of a study made at the Group for AquaticPrimary Productivity (GAP) First International Workshop heldat the Limnological Institute, University of Konstanz, in April1982.     

Taste quality changes as a function of salt concentration in single human taste papillae

A series of experiments were performed to determine whetherconcentration-dependent taste quality changes occur in simplesalt solutions when presentation of these solutions is restrictedto single fungiform taste papillae. Preliminary experiments,using small area, dorsal tongue stimulation, revealed the presenceof a sour-salty confusion in response to NaCl and HCl stimulation.This confusion was found to be greater at higher concentrationsand was affected by a pre-rinse. Taste quality changes as afunction of solution concentration for NaCl, KCl, and LiCl stimulationof single papillae were found to parallel those found previouslywith whole-mouth stimulation, although the sour component wasgreater at high concentrations, reflecting the effect of thepreviously identified sour-salty confusion. The data are discussedwithin the context of Dzendolet's (1968) physicochemical theoryof taste quality changes in salts. ^*This research was conducted as part of a thesis submitted inpartial fulfilment of the requirements for the degree of Doctorof Philosophy at the University of Massachusetts/Amherst. ^{* *}Current address: Behavioral Sciences Division, Food SciencesLaboratory, US Army Natick Research and Development Command,Natick, MA 01760, USA     

Phytoplankton in the surface and chlorophyll maximum off southern California in August, 1978

A synoptic sampling of 30 stations in a 25 km x40 km grid closeto the southern California coast revealed that chlorophyll andphytoplankton biomass were higher nearshore and to the south,where relatively large dinoflagellates dominated. A subsurfacechlorophyll maximum was present at each station, near the nitraclineand 10% light level. Nearshore and to the south, these maximarepresented higher levels of phytoplankton biomass than at thesurface whereas at the other stations, chlorophyll maxima couldbe attributed to physiological changes in chlorophyll contentof small flagellated phytoplankton rather than to the accumulationof phytoplankton at depth. Univariate and multivariate statisticalprocedures were used to demonstrate that phytoplankton assemblagesseparated by tens of meters in the vertical were just as differentas those separated by tens of kilometers in the horizontal.We conclude that residence time of water near the coast is ofgreat importance to the determination of the abundance and taxonomiccharacteristics of phytoplankton, and that advection of offshorewater towards the coast was the major determinant of the patternobserved during our study. ¹Present address: University of Texas, Port Aransas Marine Laboratory,Port Aransas, TX 78373, USA     

Evaluation of methods for the separation and analysis of proteins and free amino acids in phytoplankton samples

Due to their importance as not only major constituents in paniculatematter but also the metabolism of nitrogen in marine microorganisms,numerous methods have been employed to measure proteins andfree amino acids. However, two difficulties frequently complicatethese measurements. First, an initial separation of proteinsfrom free amino acids is helpful since most analytical methodsare somewhat sensitive to both compound types. Second, the choiceof detection techniques that minimize response differences betweenvarious proteins or amino acids is desirable since natural samplesof microorganisms consist of mixtures of many proteins and aminoacids. To address these problems, four protein detection techniques(modified Lowry et al., Dorsey et al., Bradford and fluorescamine)and two amino acid detection techniques (fluorescamine and o-phthaldialdehyde)were evaluated. Relative extraction efficiencies for proteinfrom phytoplankton samples were also evaluated with six homogenizationsolutions/protocols (TCA, NaOH, boiling NaOH, Triton X-100,NaOH plus Triton X-100 and distilled water). TCA homogenizationyielded the highest protein recoveries, and sufficient physicalseparations between proteins and free amino acids were obtainedwith TCA concentrations between 0.18 and 0.37 M. Results ofthese studies allowed for development of a method for extracting,separating and analyzing proteins and total free amino acidsfrom a common phytoplankton sample. The procedure involves initialhomogenization in a TCA solution, followed by centrifugationto separate protein and free amino acid fractions. Proteinsare then analyzed by a modification of the Lowry et al. procedure,and amino acids by a fluorescamine procedure. ²Present address: Science Applications International Corporation,4224Campus Point Court, San Diego, CA 92121, USA     

Quantitation of DNA and RNA in crude tissue extracts by flow injection analysis.

An automated two-dye flow injection analysis system to quantitate DNA and RNA in crude extracts of tissues is described. The method uses the fluorochrome dyes ethidium bromide and Hoechst 33258. DNA concentration is determined directly from its fluorescence in Hoechst dye. RNA is estimated from fluorescence in ethidium bromide after subtraction of the fluorescence due to DNA. This method has several advantages: a simple extraction procedure, a low detection limit (0.01 micrograms DNA and 0.10 micrograms RNA), automation, and a high sample throughput.     

Activities of RNases in different cell compartments in different regions of pea roots

RNase activity in three different regions of pea roots—thetip, middle and basal regions—was analyzed. There werethree types of RNases differing from each other in their intracellularlocalization; the enzymes in a soluble form and two bound formsassociated with unknown, small particles or ribosomes and withthe microsomal membrane. The top region showed a high activityper DNA content of RNase in the microsomal membrane and lowactivities for the other two RNases, as compared with the otherregions. The middle region contained a low amount of RNA perDNA and showed a higher activity per DNA content of RNase inthe unknown particles or ribosomes than in the basal region.The activity of RNase in the unknown particles or ribosomesvaried greatly among the regions, but that in microsomal membranevaried only slightly. ¹ Present address: Okitsu Branch, Fruit Tree Research Station,Okitsu, Shizuoka, Japan. ² Present address: Asahi Denka Co. Ltd., 7–1 Higashiogu,Arakawa, Tokyo, Japan. (Received July 25, 1974; )