bluuebunny/crossref_metadata_2025 huggingface dataset:
The sedimentation of amyloplasts in living statocytes of the dandelion flower stalk
Authors: CLIFFORD PAUL E. , BARCLAY GREGOR F.
Published: August 2010

Abstract The sedimentation of amyloplasts in inverted statocytes of the flower stalk of dandelion (Taraxacum officinale Weber) was followed using light microscopy. Much variety in sedimentation pattern was evident with complete sedimentation occurring in as little as 3–4 min to as much as a few h and individual amyloplasts showing barely perceptible sedimentation or sedimenting at speeds of up to 40 μm min−1. It was also apparent that amyloplasts were subjected to considerable movement after they had sedimented. Large vacuoles and cytoplasmic streaming in statocytes were confirmed and are considered to greatly influence amy‐loplast sedimentation pattern. The implications of these observations for the starch‐statolith hypothesis of geotropism are discussed.
Vegetative crop growth model incorporating leaf area expansion and senescence, and applied to grass
Authors: JOHNSON I. R. , THORNLEY J. H. M.
Published: August 2010

Abstract. A crop growth model incorporating leaf area expansion and senescence is constructed. Leaf area is treated as an independent state variable with the incremental specific leaf area a function of the storage/structure ratio. The vegetative grass crop, which usually has three green leaves per tiller, is particularly considered; the above‐ground dry matter is assumed to occupy four compartments: growing leaves, first fully expanded leaves, second fully expanded leaves, and senescing leaves. Each compartment is described by two state variables—structural weight and leaf area index. Newly synthesized structural material comprises leaf, sheath and stem in fixed proportions, although defoliation can alter these proportions in the standing crop. Photosynthesis and respiration are calculated in the usual way. Root growth, root: shoot partitioning, soil water and nutrients are assumed to be relatively unimportant for an established vegetative grass crop grown under favourable conditions. The model is used to simulate the time course of dry matter and leaf area development for crops that are exposed to a constant environment, a seasonally varying environment, and are defoliated.
Effect of sowing date on the temperature response of leaf emergence and leaf size in barley
Authors: KIRBY E. J. M. , APPLEYARD MARGARET , FELLOWES GWYNNETH
Published: August 2010

Abstract Rate of leaf emergence of barley grown in the field in each of 2 years was affected by sowing date and, where direct comparisons were possible, it was found that leaves on late‐sown plants emerged more quickly. Rate of leaf emergence fluctuated throughout the season, slowing almost to zero in the winter. Much of this variation in rate was removed when the number of leaves was plotted against accumulated temperature rather than time. When emergence rates for each sowing were calculated using a common base temperature they were found to be well correlated with rate of change of daylength. However, it was (bund that base temperature as well as temperature response was affected by date of sowing. The pattern of change of size of leaves was also affected by date of sowing. It appeared that in low temperatures and short days, there was no increase in leaf size from leaf position to leaf position. The responses of leaf emergence, extension and final size to date of sowing appear to adapt the plant to grow quickly when sown early but to cease growth and possibly frost‐harden at low temperatures.
Incorporating Gene Functional Annotations in Detecting Differential Gene Expression
Authors: Pan Wei
Published: August 2010

The importance of incorporating existing biological knowledge, such as gene functional annotations in gene ontology, in analysing high throughput genomic and proteomic data is being increasingly recognized. In the context of detecting differential gene expression, however, the current practice of using gene annotations is limited primarily to validations. Here we take a direct approach to incorporating gene annotations into mixture models for analysis. First, in contrast with a standard mixture model assuming that each gene of the genome has the same distribution, we study stratified mixture models allowing genes with different annotations to have different distributions, such as prior probabilities. Second, rather than treating parameters in stratified mixture models independently, we propose a hierarchical model to take advantage of the hierarchical structure of most gene annotation systems, such as gene ontology. We consider a simplified implementation for the proof of concept. An application to a mouse microarray data set and a simulation study demonstrate the improvement of the two new approaches over the standard mixture model.
Education in OR/MS at a Glance: Results of the First IFORS Survey
Authors: Tavares L. Valadares
Published: August 2010

An IFORS survey was prepared during 1990/1991 to obtain an international picture of the main features of the educational programs in the field of OR/MS. Seventeen countries sent information concerning a total of 176 programs and major conclusions are presented in this paper.
An Anisotropic Model for Spatial Processes
Authors: Deng Minfeng
Published: August 2010

One of the key assumptions in spatial econometric modeling is that the spatial process is isotropic, which means that direction is irrelevant in the specification of the spatial structure. On the one hand, this assumption largely reduces the complexity of the spatial models and facilitates estimation and interpretation; on the other hand, it appears rather restrictive and hard to justify in many empirical applications. In this article a very general anisotropic spatial model, which allows for a high level of flexibility in the spatial structure, is proposed. This new model can be estimated using maximum likelihood and its asymptotic properties are derived at length. When the model is applied to the well‐known 1970 Boston housing prices data, it significantly outperforms the isotropic spatial lag model. It also provides interesting additional insights into the price determination process in the properties market. Finally, a Monte Carlo simulation study is used to confirm the optimal properties of the model.
A Bayesian Dynamic Spatio‐Temporal Interaction Model: An Application to Prostate Cancer Incidence
Authors: Kim Hoon , Oleson Jacob J.
Published: August 2010

During the past three decades, prostate cancer incidence has changed substantially in the United States. A fully Bayesian hierarchical spatio‐temporal interaction model is proposed to estimate prostate cancer incidence rates in the state of Iowa. We introduce random spatial effects to capture the local dependence among regions, random temporal effects to explain the nonlinearity of rates over time, and random spatio‐temporal interactions. In addition, we introduce fixed age effects because most epidemiologic data are strongly related to age. We find that prostate cancer incidence in Iowa counties increased sharply over age while incidence rates increased initially, then decreased over time. We identify hot spots of high and low rates for age groups and time periods using disease mapping.
DIVERSITY OF PLASTID DNA CONFIGURATION AMONG CLASSES OF EUKARYOTE ALGAE1
Authors: Coleman Annette W.
Published: August 2010

Information is presented concerning the overall arrangement of plastid DNA (ptDNA) in plastids of approximately 100 spp. of eukaryote algae, representing all classes. The three‐dimensional arrangement of the ptDNA was assessed by study of both living and fixed material, stained with the DNA fluorochrome 4′,6‐diamidino‐2‐phenylindole (DAPI), using both phase and fluorescence microscopy. The widespread occurrence of two major types of ptDNA configuration known from prior electron microscopy studies was confirmed. These are (1) DNA densities (nucleoids) of variable size and morphology, scattered throughout the plastid, and (2) a ring nucleoid, beaded or unbeaded, lying just within the girdle lamella. Type 1 is characteristic of Rhodophyta, Dinophyta, Chlorophyta, Cryptophyta, Prymnesiophyceae and Eustigmatophyceae (with one exception). Type 2 is characteristic of Phaeophyceae, Bacillariophyceae, Raphidophyceae, Chrysophyceae (except silicoflagellates and organisms such asSynuraandDinobryon),and Xanthophyceae (with the exception ofVaucheriaand three genera known to lack girdle lamellae,Bumilleria, Bumilleriopsis,andPseudobumilleriopsis).Some of these exceptional forms, as well as Euglenophyta, have configurations of ptDNA not previously recognized. In all the configurations observed, the DNA of a single plastid could be interpreted as being in continuity.

This character of plastids appears to be stable under varied conditions of growth and at differing stages of the life cycle, where examined, and has confirmed the reclassification made on other grounds of several taxonomic entities. It has also revealed new questionable classifications. Since DAPI staining is far simpler than serial sectioning for electron microscopy in revealing ptDNA architecture, use of the technique may be valuable for future studies of numerous organisms, both to help in their identification and as an aid to unravelling major taxonomic affinities. In light of the endosymbiont hypothesis, plastid characters may require as great attention as those of the remainder of the cell.
OSMOTIC ADJUSTMENT INLAMINARIA DIGITATA(PHAEOPHYTA) WITH PARTICULAR REFERENCE TO SEASONAL CHANGES IN INTERNAL SOLUTE CONCENTRATIONS1
Authors: Davison Ian R. , Reed Robert H.
Published: August 2010

Laboratory studies have indicated that Na+, K+(together with Cl−the presumed counter‐ion to these cations), NO3−and mannitol represent the major cellular osmotica inLaminaria digitata(Huds.) Lamour. The cellular content of NO3−(together with a fraction of the K+pool which acts as the counter‐ion to NO3−) was found to be inversely proportional to that of mannitol, suggesting thatL. digitatamaintains a constant turgor by means of an isotonic substitution between these compounds. An analysis of the seasonal changes in solute content in an Arbroath (Scotland) population ofL. digitataconfirmed this hypothesis and indicated that the total pool of stored photosynthate was partitioned between the interconvertible carbohydrates mannitol and laminaran (which has a much lower osmotic potential than mannitol) depending on the size of the cellular pool of NO3−.
CHEMICAL PROFILE OF SELECTED SPECIES OF MICROALGAE WITH EMPHASIS ON LIPIDS1
Authors: Ben‐Amotz Ami , Tornabene Thomas G. , Thomas William H.
Published: August 2010

The lipid profile of seven species of unicellular eukaryotic microalgae grown under controlled conditions was studied with emphasis on the hydrocarbons and the fatty acids as part of a search for oil‐producing algae. Green, slow‐growing colonies of Botryococcus braunii Kutz contained the highest lipid content of 45% based on the organic weight, with an increase to 55% under nitrogen deficiency and with no effect of sodium chloride stress. Ankistrodesmus sp. Thomas, Dunaliella spp., Isochrysis sp., Nannochloris sp. Thomas, and Nitzschia sp. Chapman contained an average of 25% lipids under nitrogen sufficient conditions. Nitrogen deficiency resulted in significant increase in the lipid content in all species but Dunaliella spp., which produced a higher content of carbohydrates. Significant low amounts of acyclic hydrocarbons were detected only in Botryococcus braunii Kutz and not in the other algae. The major hydrocarbon fractions in nitrogen deficient Botryococcus braunii Kutz, Dunaliella salina Thomas, Isochrysis spp. and Nannochloris sp. Thomas were cyclic and branched polyunsaturated components which were identified as various isoprenoid derivatives. The polar lipid composition of glycolipids and phospholipids of all species investigated was fairly typical of photosynthetic eukaryotic algae. Fatty acid composition was species specific, with changes occurring in the relative amounts of individual acids of cells cultivated under different conditions and growth phases. All species synthesized C14:0, C16.0, C18:1, C18:2 and C18:3 fatty acids; C 16:4 in Ankistrodesmus sp. Thomas; C18:4 and C 22.6 in Isochrysis sp.; C16:2, C16:3 and C20:5 in Nannochloris sp. Thomas; C16:2, C16:3 and C20:5 in Nitzschia sp. Chapman. Nitrogen deficiency and salt stress induced accumulation of C18:1 in all treated species and to a lesser extent in Botryococcus braunii Kutz. The low production of hydrocarbons under optimal growth conditions and the high production of hydrocarbons under limited growth conditions cannot support the notion that microalgae can be utilized as biosolar energy converters for the production of liquid fuel, but point to the availability of a variety of neutral and polar lipid products.
TWO NEW SPECIES OF TAYLORIELLA (RHODOMELACEAE, RHODOPHYTA) FROM THE NORTHEASTERN NORTH PACIFIC1
Authors: Wynne Michael J.
Published: August 2010

Two new species are recognized in the rhodomelacean genus Tayloriella Kylin: T. divaricata sp. nov. and T. abyssalis sp. nov. These two taxa are distributed in the northeastern North Pacific, the former ranging from Amchitka Island in the Aleutians through southcentral Alaska to northern British Columbia, and the latter ranging also from Amchitka Island through southcentral Alaska and British Columbia into northern Washington. A characteristic of these two species shared with the type of Tayloriella is that the abaxial lateral always overtops the monopodially developed axes in every order of branching. The laterals have little congenital fusion with the parent axes. A common feature in these two species is that the laterals are terminated in a relatively long monosiphonous portion (usually 6 or 7 cells). The relationship of Tayloriella to Pterosiphonia and Pterosiphoniella is discussed.
INTERACTIONS BETWEEN LIGHT, NH4+, AND CO2 IN BUOYANCY REGULATION OF ANABAENA FLOS‐AQUAE (CYANOPHYCEAE)1
Authors: Spencer Craig N. , King Darrell L.
Published: August 2010

Buoyancy of the gas‐vacuolate alga Anabaena flosaquae Brébisson was measured under various levels of light, NH4+, and CO2. At high irradiance (50 μE · m−2·−1) the alga was non‐buoyant regardless of the availability of CO2 and NH4+. At low irradiance (≤10 μE · m −2· s−1) buoyancy was controlled by the availability of NH4+ and CO2. When NH4+ was abundant, algal buoyancy was high over a wide range of CO2 concentrations. In the absence of NH4+, algal buoyancy was reduced at high CO2 concentrations, however as the CO2 concentration declined below about 5 μmol · L−1, algal buoyancy increased. These results help explain why gas vacuolate, nitrogen‐fixing blue‐green algae often form surface blooms in eutrophic lakes.
STUDIES IN PENNATE DIATOMS: VALVE MORPHOLOGIES OF LICMOPHORA AND CAMPYLOSTYLUS1
Authors: Wahrer Richard J. , Fryxell Greta A. , Cox Elenor R.
Published: August 2010

Using scanning electron and light, microscopy, several hundred specimens of Campylostylus normanianus (Grev.) Gerloff, Licmophora abbreviata Agardh, L. gracilis var. anglica (Kütz) Per. et Per., and L. flabellata (Carm.) Agardh were examined to elucidate their valve morphology. These species were found to be heterovalvar with respect to the presence of the labiate process in the basal apices of the cell, although one was always present at the head pole of each valve. This form of heterovalvar may be one basis for partitioning the large and variable family Diatomaceae. Because of the similar valve morphologies exhibited by C. normanianus and Licmophora species examined, it is recommended that Campylostylus normanianus be placed in the older genus Licmophora, as L. normaniana (Grev.) Wahrer.
LIGHT, TEMPERATURE AND PHOTOPERIOD AS FACTORS CONTROLLING REPRODUCTION INULOTHRIX ZONATA(ULVOPHYCEAE)1
Authors: Graham James M. , Graham Linda E. , Kranzfelder James A.
Published: August 2010

In many lakes in the northern United States and Canada the filamentous green algaUlothrix zonata(Weber and Mohr) Kütz grows abundantly in early spring in shallow waters. Asexual reproduction occurs by formation of quadriflagellate zoospores which disrupt, the integrity of the cells upon release causing the filament to disintegrate. Study of the effects of 100 different combinations of irradiance, temperature and photoperiod revealed that zoospore formation is favored by high temperatures near 20°C, high light levels of 520 μE·m−2·s−1and photoperiods of either short day (8:16 h light‐dark) or long day cycles (16:8 h light‐dark). Zoospore formation is minimal under conditions of low temperature (5°C), low irradiance (32.5 μE·m−2·s−1) and neutral day‐lengths (12:12 h light‐dark). These observations explain the decline inU. zonatabiomass when water temperatures rise above 10° C. The combined effect of rising water temperatures and increasing daylengths causes progressively more filaments to switch from vegetable growth to zoospore production resulting in an increasing loss of biomass.
MORPHOLOGICAL VARIATION WITHIN AND BETWEEN NATURAL POPULATIONS OF NON‐TIDE POOL FUCUS DISTICHUS (PHAEOPHYTA) IN NEW ENGLAND1,2
Authors: Sideman Eric J. , Mathieson A. C.
Published: August 2010

The sources of morphological variation in natural populations of Fucus distichus L. ssp. edentatus (De la Pyiaie) Powell and F. distichus L. ssp, evanescens (C. Agardh) Powell from New England were evaluated. Individuals from different populations were morphologically distinct as judged by population means and analysis of variance. A correlation between the plant's form and its habitat was established by field observation. The broadest material grows in calm estuarine habitats, while the narrowest plants occur in exposed, open coastal areas. Major differences in morphology also appear seasonally. In addition, microhabitat factors such as exposure to wave action and elevation explain some morphological variation. Cultured germlings from distinct populations of “evanescens” and “edentatus” type plants were outplanted to an experimental garden in order to ascertain whether the variation was heritable or environmentally induced. The latter experiments indicate that major differences in morphology are genetically determined.
DISTRIBUTION, SEASONALITY AND REPRODUCTIVE PHENOLOGY OFBANGIA ATROPURPUREA(RHODOPHYTA) IN RHODE ISLAND, U.S.A.1
Authors: Sheath Robert G. , VanAlstyne Kathryn L. , Cole Kathleen M.
Published: August 2010

Forty‐seven sites along the Rhode Island coastline were sampled on a seasonal basis for the presence of the red algaBangia atropurpurea(Roth) C. Ag. This species was found to be widely distributed, occurring at 94% of the hard, stable substrates sampled.Bangiapopulations were most, widespread in the winter (71% of sites) and least frequent in the summer (29% of sites). At one location, three high intertidal populations (average height 101 cm) and three low intertidal populations (average height 14 cm) were sampled monthly for two years. The upper intertidal populations appeared in September and persisted until at least May, whereas the lower populations were ephemeral, appearing for only a few months in late winter. The high intertidal populations were present on 85% of the sampling dates white the lower ones were observed on 25% of the sampling dates. Upper intertidal filaments reproduced exclusively by asexual monospores unlike those of the lower populations which were largely sexual. The maximum diameter of asexual and carpogonial filaments was 120 and 250 nm, respectively. Monosporagenesis was strongly correlated to temperature whereas gametogenesis was strongly correlated to photopriod.
TRANSLOCATION OF IODINE IN LAMINARIA SACCHARINA(PHAEOPHYTA)1
Authors: Amat Mireille A. , Srivastava Lalit M.
Published: August 2010

Long‐distance translocation of 125I in Laminaria saccharina (L.) Lamour. followed a “source to sink” pattern. When the source of 125I was placed on the distal mature part of the blade, the translocation was unidirectional, basipetal and directed towards the meristematic region at the blade‐stipe junction. When the source was placed directly at the meristem there was no movement of label distal to the meristem. The velocity of125I transport ranged from 2 to 3.5 cm · h−1. The anion I− seemed to be the only species of125I transported. An assay of iodine content in different parts of L. saccharina plant showed much higher levels of iodine in the meristem, stipe and holdfast than in the blade. This distribution concurs well with the pattern of I− translocation.
PHOTOSYNTHESIS‐IRRADIANCE RELATIONSHIPS IN SEA ICE MICROALGAE FROM McMURDO SOUND, ANTARCTICA1
Authors: Palmisano Anna C. , SooHoo Janice Beeler , Sullivan Cornelius W.
Published: August 2010

Sea ice microalgae in McMurdo Sound, Antarctica were examined for photosynthesis‐irradiance relationships and for the extent and time course of their photoadaptation to a reduction in in situ irradiance. Algae were collected from the bottom centimeter of coarse‐grained congelation ice in an area free of natural snow cover. Photosynthetic rate was determined in short term (1 h) incubations at −2° C over a range of irradiance from 0 to 286 μE·m−2·s−1. Assimilation numbers were consistently below 0.1 mg C·mg chl a−1·h−1. The Ik's3 averaged only 7 μE·m−2·s−1, and photosynthesis was inhibited at irradiances above 25 μE·m−2·s−1.

Photosynthetic parameters of the ice algal community were examined over a nine day period following the addition of 4 cm of surface snow while a control area remained snow‐free. A reduction of 40% in PmB relative to the control occurred after two days of snow cover; α, β, Ik, and Im were not significantly altered. Low assimilation numbers and constant standing crop size, however, suggested that the algal bloom may have already reached stationary growth phase, possibly minimizing their photoadaptive response.
GROWTH AND BRANCHED HYDROCARBON PRODUCTION IN A STRAIN OF BOTRYOCOCCUS BRAUNII (CHLOROPHYTA)1
Authors: Wolf Fred R. , Nonomura Arthur M. , Bassham James A.
Published: August 2010

A strain Botryococcus braunii Kütz. that produces high levels of branched hydrocarbons (botryococcenes) was grown under different environmental conditions to investigate the relationship between growth and hydrocarbon production. Carbon dioxide concentration had the most significant influence on growth; 0.3% CO2‐enriched cultures demonstrated a minimum mass doubling time of ca. 40 h, compared to ca. 6 days for ambient air cultures grown on the same buffered growth medium. The botryococcene fraction, which consisted of 10 identified compounds (CnH2n‐10; n = 30–34), usually constituted ca. 25–40% of the culture dry weight under various growth regimes, including nitrogen‐ and/or phosphate‐deficiencies. CO2 enrichment initially favored the production of the lower botryococcenes (C30–C32), whereas relatively slow‐growing ambient air cultures accumulated C33 and C34 compounds.

Colony color changed in response to different light intensities. High light increased the carotenoid/chlorophyll ratio, which resulted in orange colonies. Cultures exposed to low light intensity appeared green. This change in coloration was reversible over a period of a few days, and at no time were the linear hydrocarbons characteristic of the other form of the alga detected. Ostensible colony color is not, therefore, a reliable indicator of qualitative hydrocarbon content.

Sequential solvent extraction experiments indicated that up to ca. 7% of the botryococcene fraction was intracellular and that the remainder was located within the colonial matrix. The internal (cellular) pool principally consisted of C30–C32 botryococcenes, whereas the external (colonial matrix) pool contained >99% of the C33 and C34 compounds, in addition to large amounts of the lower botryococcenes. These results, taken in conjunction with other data, are compatible with the hypothesis that the C30 botryococcene is the precursor, presumably via methylation, of the higher botryococcenes.
UTEX 1336: PERIDINIUM CINCTUM OR PERIDINIUM VOLZII (DINOPHYCEAE)?1
Authors: Pfiester Lois A. , Carty Susan
Published: August 2010

Plate pattern variation in UTEX clone 1336 and published photographs using this clone indicate the presence of two taxa: Peridinium cinctum and Peridinium volzii. All subclones established from UTEX 1336 contain the same two cell types. The identification of UTEX 1336 and its future use by researchers are discussed.
VEGETATIVE AND REPRODUCTIVE MORPHOLOGY IN RETICULOCAULIS GEN. NOV. AND NACCARIA HAWAIIANA SP. NOV. (RHODOPHYTA, NACCARIACEAE)1
Authors: Abbott Isabella A.
Published: August 2010

A secondarily formed reticulum of cells that encloses axial strands and a carposporophyte that is almost entirely converted to sporangia are the diagnostic features of a new genus, Reticulocaulis (Naccariaceae, Nemaliales), with R. mucosissimus as the type species. A new species of Naccaria, N. hawaiiana permits close comparison with the new genus and other previously described species of Naccaria. Until now, no Naccariaceae were known in the Pacific, and these new taxa are part of the sketchily known subtidal marine flora of Hawaii.
COMPARATIVE STUDIES ON THE CELL WALLS OF SEXUAL AND ASEXUAL BANGIA ATROPURPUREA (RHODOPHYTA). I. HISTOCHEMISTRY OF POLYSACCHARIDES1
Authors: Cole Kathleen M. , Park Carol M. , Reid Philip E. , Sheath Robert G.
Published: August 2010

A comparative histochemical study of the nature and distribution of acidic and neutral cell wall polysaccharides was conducted on marine sexual and asexual filaments of the red alga Bangia atropurpurea (Roth) C. Ag. Outer and inner walls of this species were clearly partitioned according to staining and transmission electron microscopic characteristics. Neutral polysaccharides were detected in the outer coating (cuticle) but were absent from outer and inner walls of all filaments. Acidic polysaccharides were noted in the outer wall material but not in the inner wall layers of any filaments at any developmental stages. The major staining component of vegetative regions of sexual material and all regions of asexual filaments was a highly sulfated polymer. During sexual reproduction only there was a generalized change in the nature of the acidic component, characterized by a decrease in intensity of staining for sulfates in both male and female filaments and the appearance, in female filaments only, of polysaccharides which presumably were carboxylated. Spermatia attached to both male and female filaments in regions where sexual differentiation was initiated and where changes in the outer wall components commenced.
REGULATION OF GAS VESICLE CONTENT AND BUOYANCY IN LIGHT‐ OR PHOSPHATE‐LIMITED CULTURES OF APHANIZOMENON FLOS‐AQUAE (CYANOPHYTA)1
Authors: Konopka Allan , Kromkamp Jacco , Mur Luuc R.
Published: August 2010

Measurements of the gas vesicle space in steady‐state light or phosphate‐limited cultures of Aphanizomenon flos‐aquae Ralfs, strain 7905 showed that gas vesicle content decreased as energy‐limited growth rate increased hut was the same at several phosphate‐limited growth rates. Upon a decrease in growth irradiance, gas vesicle content did increase in phosphate‐limited cultures, hut the cultures remained nonbuoyant as long as P was limiting. Buoyant, energy‐limited cultures lost their buoyancy in less than 2 h when exposed to higher irradiances. The primary mechanism for buoyancy loss was the accumulation of polysaccharide as ballast. Collapse of gas vesicles by turgor pressure played a minor role in the loss of buoyancy. When cultures were exposed to higher irradiances, cells continued to synthesize gas vesicles at the same rate as before the shift for at least 1 generation time. The amount of ballast required to make individual filaments in the population sink varied 4‐fold. This variation appears to be due to differences in gas vesicle content among individual filaments.
INTRACELLULAR PHOTOSYNTHATE ALLOCATION AND THE CONTROL OF ARCTIC MARINE ICE ALGAL PRODUCTION1
Authors: H. Smith Ralph E. , Clement Pierre , Cota Glenn F. , Li William K. W.
Published: August 2010

Ice algae are a case study in photo‐autotrophic growth and metabolism under chronically low temperature and irradiance. We measured the allocation of 14C‐labelled photosynthate among major classes of intracellular carbon (low molecular weight compounds, or LMW; lipid; protein; and polysaccharide) and found light‐dependent changes in allocation broadly similar to photo‐adaptive responses known in phytoplankton at higher temperatures; average relative allocation to protein varied inversely (10–37%) and allocation to lipids and polysaccharides directly (10–23%, and 16–21%, respectively) with the sub‐inhibiting irradiance levels we employed (3.5–33.0 μE·M−2·s−1). Unlike many observations at higher temperatures, ours indicated (on average) a large and light‐insensitive allocation to LMW (ca. 40%) and a greater light‐sensitivity in lipid than in polysaccharide allocation. At the higher incubation irradiances, resembling in situ levels typical of areas with little (0–5 cm) snow cover, allocation to protein was often low (10–13%) compared to many observations of nutrient‐sufficient or light‐limited phytoplankton. Allocation to protein increased substantially (to ca. 40%) during a period of intensified tidal mixing, and assimilation numbers also attained a maximum at about the same time. Suck dynamics show that the ice algae are not constrained to their often protein‐poor allocation by the constantly low ambient temperature. Rather, they display marked shifts in metabolism consistent with major changes in light and inorganic nutrient supply, driven in part by the physical process of tidal mixing.
INTERACTIVE EFFECTS OF COPPER AND SILICIC ACID ON RESTING SPORE FORMATION AND VIABILITY IN A MARINE DIATOM1
Authors: Valente Raymond M. , Cosper Elizabeth M. , Wurster Charles F.
Published: August 2010

The toxic effects of copper on resting spore formation and viability in the marine diatom Chaetoceros protuberans Lauder were determined both with and without silicic acid added to the medium. With silicic acid available, partial inhibition of resting spore formation occurred only at the highest cupric ion activity (pCu 8.6), while the percentage of cells forming spores at pCu's 10.2 and 11.3 was nearly the same as in the controls. Without silicic acid added to the medium, sporulation was completely inhibited at pCu 8.6 and greatly inhibited, at pCu 10.2. At pCu 11.3 and in the controls, the rate of spore formation was less than 50%. The results indicate that the inhibition of resting spore formation by copper is related to the concentration of silicic acid available to cells of C protuberans. This is consistent with previous studies which show that copper toxicity during vegetative growth involves interference with silicification in diatoms and is a Junction of the silicic acid concentration of the medium.

Viable resting spores of C. protuberans were still present in cultures following exposure to elevated copper concentrations during a 100‐day incubation period. This indicates that resting spores can serve to enhance diatom survival in areas polluted by heavy metals.
AN ATLANTIC POPULATION OF PIKEA CALIFORNICA (DUMONTIACEAE, RHODOPHYTA)1
Authors: Maggs Christine A. , Guiry Michael D.
Published: August 2010

The marine red alga Pikea californica Harvey, previously known only from the east coast of Japan and the west coast of North America, was found in 1983 to be abundant in the surge zone throughout the Isles of Scilly archipelago, off SW England. Examination of herbarium material showed that the population was present in 1967. All plants observed in July 1983 and September 1984 were sterile, but reproductive male and female plants were collected in November 1983. The habitat and phenology of P. californica in the Isles of Scilly closely resemble those of Pacific populations. English plants are vegetatively and reproductively identical to the type and other California specimens. They can easily be distinguished from Sphaerococcus coronopifolius Stackhouse (Sphaerococcaceae, Gigartinales), the most similar species in the flora of the British Isles, by the presence in transverse sections of several lacunae, representing axial and whorl‐branchlet filaments, in contrast to the single axial filament of S. coronopifolius. It is possible that the Isles of Scilly population of P. californica is a relict of a species once more widespread, but it seems more likely that it is another example of the well‐established pattern of marine introductions into the British Isles from the North Pacific. The range of temperature regimes occupied by P. Californica in the Pacific suggests that the species could become more widespread in Europe, but at present it appears to be confined to the Isles of Scilly.
IMMUNOLOGICAL STUDIES OF THE L‐PHASE VARIANTS OF SOME E. COLI STRAINS
Authors: Kaijser B. , Brorson J.‐E. , Seeberg S.
Published: August 2010

As a basis for the studies of the role of Escherichia coli L‐phase variants in urinary tract infections the immunological characteristics of the L‐phase variants of three E. coli strains were studied (E. coli O8:K8:H4; E. coli O2:K1:H4 and E. coli O15:K?:H?). The L‐phase variants were induced by penicillin on solid media and could be subcultivated at least thirty times on penicillin‐free media without reverting to bacteria. Antisera to the bacteria and L‐phase variants were produced in rabbits. Most of the antigens in the bacteria were also found in the L‐phase variants. All L‐phase variants contained O antigen. In the L‐phase variant of E. coli O8:K8:H4 K antigen was also found. In all the micro‐organisms an antigen with high electrophoretic mobility common to many E. coli, Proteus and Pseudonomas strains was found. There was enough O antigen in all the L‐phase variants to induce an O antibody response in rabbits similar to the O antibody response induced by complete bacteria.
EFFECT OF IRRADIATION ON ESTABLISHED DELAYED HYPERSENSITIVITY
Authors: Visakorpi Risto
Published: August 2010

When rats immunized with bovine serum albumin in complete adjuvant were irradiated 10 days later with 800 rads their ability to display a positive skin reaction to the test antigen was suppressed for 4–5 days. Thereafter recovery was evident in spite of persisting low blood leucocyte levels. Specific cells were demonstrated in the animals by migration inhibition of peritoneal cells two days after irradiation, when skin reactions were negative. On the other hand transfer of normal bone marrow cells corrected the ability to mount skin reactions but spleen, thoracic duct or lymph node cells did not. It seems that post‐irradiation suppression of skin reactions does not depend on damage of specific cells but depends on shortage of a bone marrow derived cell type participating in skin reactions as a nonspecific component.
HAEMOPOIETIC DEFECTS IN MICE INFECTED WITH LYMPHOCYTIC CHORIOMENINGITIS VIRUS
Authors: Bro‐Jørgensen Klaus , Volkert Mogens
Published: August 2010

In the preceding report (3) experiments were described which suggested the occurrence of haemopoietic disorders in mice infected with the LCM virus. Immunological disorders associated with the LCM virus infections of mice are well‐known. It was considered that both haemopoietic and immunological defects might be caused by some virus‐induced interference with the stem cells in the infected mice. Attempts were therefore made to estimate the numbers and the function of stem cells in mice infected with the LCM virus. Haemopoietic colony assays were employed, and both acutely infected mice and persistent, tolerant virus carriers were examined. The findings suggested a decrease in colony‐forming stem cells in the bone marrow during the acute infection. However, the most striking observation in the acutely infected mice was of a profound inhibition of the colony‐forming response of stem cells in these animals. The influences exerted upon the stem cell response seemed to be quite specific, in that the response of immunocompetent cells was almost unimpaired when examined at the same time. The inhibition was not caused by a direct viral effect upon the stem cells, nor by any immune‐mediated damage. Experiments with the adult, persistent, tolerant virus carriers indicated that the haemopoietic colony formation was not inhibited in these mice despite a pronounced viraemia. However, their numbers of colony‐forming stem cells amounted to about fifty per cent of the normal values and seemed to agree with their relative increase in sensitivity to X‐rays. It is suggested that virus‐induced interference with the function of haemopoietic stem cells plays a central role for the tolerogen effects of the LCM virus.
GRAFT‐VERSUS‐HOST ACTIVITY OF RAT LYMPHOCYTES AFTER SENSITIZATION IN VITRO
Authors: Nielsen Hans Erik
Published: August 2010

In order to test the hypothesis that the small increase in graft‐versus‐host (GVH) activity after immunization in vivo against strong histocompatibility antigens may be due to an inhibitory effect of allo‐antibody on the cellular immune response, rat lymphocytes were sensitized in vitro with allogeneic lymphocytes. Peripheral lymphocytes from inbred Fischer (F) strain rats were cultured in vitro either alone or together with (F × BN) F1 lymphocytes in conditions where humoral antibodies are not demonstrably formed. After 4 and 6 days of culture the activity of the stimulated and non‐stimulated cells was compared in a GVH assay using (F × BN) F1 and (F × AS2) F1 hybrids as hosts. The activity of the in vitro sensitized cells against (F × BN) F1 recipients after four and six days of culture was not significantly enhanced. These findings support the alternative hypothesis that a very high proportion of cells are in fact sensitive to histocompatibility antigens, even in the non‐immune animal.
FINE STRUCTURE OF MELANIN‐PRODUCING AEROMONADS
Authors: Aurstad Kjell , Dahle Hans Kolbein
Published: August 2010

The fine structure of Aeromonas liquefaciens and Aeromonas salmonicida grown in enriched and minimal media was examined by electron microscopy. When the organisms were grown aerobically, a larger amount of particles of high electron density was found than compared with cultivation under anaerobic condition. These particles were assumed to consist of melanin type of pigments. The cell wall, which was shown to consist of a distinct triple layered membrane is separated from a more indistinct triple layered cytoplasmic membrane by a relatively electron‐transparent periplasmic space of variable thickness. Channels may occur through the cell envelope, and the possible role of these channels in secretory functions of the cell is discussed. Some large inclusions of low electron density which appeared in the cytoplasma are associated with storage products of the cell.
FIMBRIATION AND COLONY TYPE OF MORAXELLA BOVIS IN RELATION TO CONJUNCTIVAL COLONIZATION AND DEVELOPMENT OF KERATOCONJUNCTIVITIS IN CATTLE
Authors: Pedersen Knud Børge , Frøholm Leif Oddvar , Bøvre Kjell
Published: August 2010

Morphological variants of four Moraxella bovis strains were studied, using different cultural conditions. On bovine blood agar medium two colony types could be distinguished: 1) large, flat, rough and agar‐corroding, and 2) most often smaller, convex, smooth and non‐corroding forms. When transferred to human blood agar, the flat type formed convex, spreading‐corroding colonies (SC type) and the other type remained convex, non‐spreading and non‐corroding (N type). Some cell lines lost the original flat colony appearance on bovine blood agar after passages for a longer period on human blood agar; on bovine blood agar these SC cells now formed convex, but still corroding colonies. By electron microscopy it was observed that cells from corroding colonies on either medium were strongly fimbriated, whereas preparations from non‐corroding populations had non‐fimbriated cells or contained only an occasional fimbria. Conjunctival infection experiments in calves revealed that only fimbriated variants of each strain were able to colonize the conjunctival mucosa. Ultraviolet irradiation of the eye prior to inoculation facilitated the bacterial colonization, with respect to initiation and duration. Non‐fimbriated M. bovis could not be reisolated even after irradiation. Keratitis and conjunctivitis only occurred in irradiated eyes inoculated with cell lines yielding typically flat, corroding colonies on bovine blood agar. The possible function of fimbriae for attachment of M. bovis to the mucous membranes of the eye is discussed.
NONEXPRESSOR OF PATHOGENESIS‐RELATED PROTEINS1 (NPR1) and some NPR1‐related proteins are sensitive to salicylic acid
Authors: MAIER FELIX , ZWICKER SYLVIA , HÜCKELHOVEN ANGELA , MEISSNER MEIKE , FUNK JENNIFER , PFITZNER ARTUR J. P. , PFITZNER URSULA M.
Published: August 2010

NONEXPRESSOR OF PATHOGENESIS‐RELATED PROTEINS1 (NPR1; also known as NIM1) is a master regulator of systemic acquired resistance (SAR). SAR is induced by salicylic acid (SA), leading to the expression of PATHOGENESIS‐RELATED (PR) genes. Current evidence suggests that NPR1 is part of a transcription complex tethered to activation sequence‐1 (as‐1)‐like cis‐acting elements in PR‐1 gene promoters through TGA transcription factors, and that SA‐dependent PR‐1 gene expression is regulated by NIM1‐INTERACTING (NIMIN) proteins. In Arabidopsis, NPR1 is active only after SA induction. Regulation of Arabidopsis NPR1 activity has been proposed to comprise cysteine‐156 (Cys‐156), mediating SA‐induced cytoplasmic oligomer–nuclear monomer exchange, and Cys‐521 and Cys‐529, mediating SA‐dependent transcriptional activation. Tobacco NPR1 does not harbour these residues. To understand the function of tobacco NPR1, we analysed its biochemical capabilities in a heterologous system: yeast. Tobacco NPR1 differs from Arabidopsis NPR1 in its subcellular localization and its transactivation potential. Yet, both tobacco and Arabidopsis NPR1, as well as tobacco NIM1‐like1, alter some of their biochemical activities in response to SA. Whereas the addition of SA to yeast growth medium induces transcriptional activity in tobacco NPR1, its interaction with NIMIN2‐type proteins is suppressed. The effects of SA are specific, sensitive and occur coordinately. They are abolished completely by mutation of the arginine residue within the invariable penta‐amino acid motif LENRV, as present in the nonfunctional Arabidopsis nim1‐4 allele. Furthermore, NPR1 proteins with the LENRV domain coincidently harbour a broad and strongly conserved NIMIN1/NIMIN2 binding site. Our data suggest that NPR1 and some NPR1‐like proteins are sensitive to the plant hormone SA, altering some of their biochemical capabilities to enable stimulus‐dependent gene expression. The sensitivity of NPR1 proteins to SA, together with their differential interaction with diverse NIMIN proteins, seems a plausible molecular basis for the timely and coordinated activation of PR genes during SAR.
Food selection and competition in the East African buffalo (Syncerus caffer Sparrman)
Authors: SINCLAIR A. R. E. , GWYNNE M. D.
Published: August 2010

Rumen samples collected at different times of the year from buffalo in the Serengeti, were analysed with respect to proportions of plant parts present. Buffalo were almost exclusive grazers and were capable of selecting for grass leaf. At certain times of year it was the dominant food intake component but declined to only 11% of the diet by the end of the dry season. The amount of leaf in the diet was determined by the amount of rainfall which governed the growth of the food grasses. Experimental preference tests with tame animals indicated that they were capable of selecting for different grass species. The preferences were, however, for those species with a higher leaf: stem ratio. The mechanism of selection is discussed. The function of the behavioural selection appeared to be concerned with maximizing the nutrient quality of the food requirements. It appeared that ecological separation had evolved through interspecific competition.
Seasonal and interannual variations of oceanographic conditions off Mangalore coast (Karnataka, India) in the Malabar upwelling system during 1995–2004 and their influences on the pelagic fishery
Authors: KRISHNAKUMAR P. K. , BHAT G. S.
Published: August 2010

Mangalore coast is well known for its multi‐species and multi‐gear fisheries and the fishery and oceanographic features of this region is a true representation of the Malabar upwelling system. Ten years of study (1995–2004) of oceanographic parameters has been carried out from the inshore waters off Mangalore to understand their seasonal and interannual variations and influences on the pelagic fishery of the region. Attempt has been also made to understand the influence of local and global environmental conditions on the alternating patterns of abundance between the Indian mackerel and oil sardine from the area. Field‐ and satellite‐derived oceanographic data have shown that coastal upwelling occurs during July–September with a peak in August resulting in high nutrient concentrations and biological productivity along the coast. Nearly 70% of the pelagic fish catch, dominated by oil sardine and mackerel, was obtained during September–December, during or immediately after the upwelling season. Catches of scombroid fishes were significantly related to cold Sea Surface Temperature, while such relationships were not observed for sardines and anchovies. Significant positive correlations were observed between the ENSO events (MEI) and seawater temperature from the study area. The extreme oceanographic events associated with the cold La Niña, which preceded the exceptional 1997–98 El Niño event, were responsible for the collapse of the pelagic fishery, especially the mackerel fishery along the southwest coast of India (Malabar upwelling system). Coinciding with the collapse of the mackerel fishery, oil sardine populations revived during 1999–2000 all along the southwest coast of India. Tolerance of oil sardine to El Niño / La Niña events and the low predatory pressure experienced by their eggs and larvae due to the collapse of mackerel population might have resulted in its population revival.