bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF FIXATIVES ON THE ULTRASTRUCTURE OF PHYSODES IN VEGETATIVE CELLS OF SCYTOSIPHON LOMENTARIA (SCYTOSIPHONACEAE, PHAEOPHYTA)1
Authors: Clayton Margaret N. , Beakes Gordon W. 
Published: November 2004

ABSTRACTThe effects of different glutaraldehyde‐osmium fixation schedules on the ultrastructure of the vegetative cells from the meristematic regions of Scytosiphon lomentaria (Lyngbye) Link fronds are described. The best overall preservation of cell structure was obtained with a 2 h fixation in 2.5–3.5% glutaraldehyde in 0.1 M cacodylate buffered seawater (pH 7.0), followed after washing by 1 h post fixation in 1% osmium tetroxide. The addition of 1% caffeine to the glutaraldehyde fixative resulted in better retention and spatial localization of the electron dense phenolic deposits within the cells. Particular attention was paid to the effects of the various fixation schedules on the electron‐dense material within the cells and the images obtained were compared with previous accounts of brown algal cells. It is proposed that the term physode should be restricted to the discrete electron dense spherical bodies within the vacuoles and not applied to electron dense material in general. Although the organization of Scytosiphon cells was similar to that previously reported in the Scytosiphonaceae, the organization of the plasmodesmata into pit fields is at variance with previous accounts.
SURVEY OF SELECTED SEA WEEDS FOR SIMULTANEOUS PHOTOPRODUCTION OF HYDROGEN AND OXYGEN1
Authors: Greenbaum E. , Ramus J. 
Published: November 2004

ABSTRACTTen seaweed species were surveyed for simultaneous photoevolution of hydrogen and oxygen. In an attempt to induce hydrogenase activity (as measured by hydrogen photoproduction) the seaweeds were maintained under anaerobiosis in CO2‐free seawater for varying lengths of time. Although oxygen evolution was observed in every alga studied, hydrogen evolution was not observed. One conclusion of this research is that, in contrast to the microscopic algae, there is not a single example of a macroscopic alga for which the photoevolution of hydrogen has been observed, in spite of the fact that there are now at least nine macroscopic algal species known for which hydrogenase activity has been reported (either by dark hydrogen evolution or light‐activated hydrogen uptake). These results are in conflict with the conventional view that algal hydrogenase can catalyze a multiplicity of reactions, one of which is the photoproduction of molecular hydrogen. Two possible explanations for the lack of hydrogen photoproduction in macroscopic algae are presented. It is postulated that electron acceptors other than carbon dioxide can take up reducing equivalents from Photosystem I to the measurable exclusion of hydrogen photoproduction. Alternatively, the hydrogenase system in macroscopic algae may be primarily a hydrogen‐uptake system with respect to light‐activated reactions. A simple kinetic argument based on recent measurements of the photosynthetic turnover times of simultaneous light‐activated hydrogen and oxygen production is presented that supports the second explanation.
AMMONIUM INDUCED PHOTOSYNTHETIC SUPPRESSION IN AMMONIUM LIMITED DUNALIELLA TERTIOLECTA (CHLOROPHYTA)1
Authors: Turpin David H. 
Published: November 2004

ABSTRACT Dunaliella tertiolecta (Butcher) was grown in chemostat culture over a wide range of ammonium limited growth rates. The addition of ammonium caused a rapid temporary suppression of photosynthetic carbon fixation. The magnitude of ammonium induced photosynthetic suppression increased with the severity of ammonium limitation. Cells growing at rates greater than ca. 80%μmax exhibited no photosynthetic suppression in response to additions of the limiting nutrient. The duration of photosynthetic suppression was related to the concentration of added ammonium. Immediately following the suppression, photosynthesis was enhanced with respect to the controls. The eventual degree of enhancement increased with the concentration of added ammonium. Steady‐state cellular chlorophyll concentrations, photosynthetic rates, and assimilation numbers are reported.
RHODELLA RETICULATASP. NOV., A NEW COCCOID RHODOPHYTAN ALGA (PORPHYRIDIALES)1,2
Authors: Deason Temd R. , Butler Gary L. , Rhyne Charles 
Published: November 2004

ABSTRACTA new coccoid rhodophytan species is described and compared with other species in the genusRhodella.Thylakoids in the pyrenoid characterize the new species and indicate a closer relationships ofRhodellatoPorphyridiumthan was previously indicated.
NEW ENDOLITHIC CYANOPHYTES FROM THE NORTH ATLANTIC OCEAN. II. HYELLA GIGAS LUKAS & GOLUBIC SP. NOV. FROM THE FLORIDA CONTINENTAL MARGIN1
Authors: Lukas Karen J. , Golubic Stjepko 
Published: November 2004

ABSTRACTA new species of endolithic cyanophyte, Hyella gigas Lukas and Golubic (Order: Pleurocapsales), differs from other species of Hyella by its larger cell and filament dimensions and its laminated, often pigmented sheath. It bores into mollusk shells and other marine carbonate substrates on the east coast of North America, the Bahama Islands and the Northern Mediterranean Sea, where it is found from near mean low water down to 25 m depth. This comparatively shallow maximum depth is probably due to the limited capacity of Hyella gigas to adapt to changing light quality and intensity. We reject the suppression of the genus Hyella as proposed by Drouet and Daily.
THE FLAGELLAR APPARATUS OFENTOCLADIA VIRIDISMOTILE CELLS, AND THE TAXONOMIC POSITION OF THE RESURRECTED FAMILY ULVELLACEAE (ULVALES, CHLOROPHYTA)1
Authors: O'Kelly Charles J. , Floyd Gary L. 
Published: November 2004

ABSTRACTThe flagellar apparatuses of the quadriflagellate zoo‐spores and biflagellate female gametes of the marine chaetophoracean algaEntocladia viridisReinke are significantly different from those of algae belonging to Chaetophoraceae sensu stricto, but closely resemble those of ulvacean genera. These differences permit the taxonomic reassignment of certain marine chaetophoracean genera and an evaluation of the flagellar apparatus features used to characterize the class Ulvophyceae. Critical features of the zoospore include arrangement of the four basal bodies into an upper and a lower pair with the proximal ends of the upper basal bodies overlapping, terminal caps, proximal sheaths connected to one another by striated bands, and a cruciate microtubular rootlet system having a3‐2–3‐2alternation pattern and striated microtubule‐associated components that accompany the two‐membered rootlets. An indistinct distal fiber occurs just anterior to the basal bodies, and is closely associated with the insertion into the flagellar apparatus of the three‐membered rootlets. The flagellar apparatus demonstrates 180° rotational symmetry, and its components show counterclockwise absolute orientation when viewed from above. Newly described features include the prominently bilobed structure of the terminal caps on the upper basal body pair, and the presence of both a granular zone and an additional single microtubule anterior to each of the four rootlets, an arrangement termed the “stacked rootlet configuration.” Rhizoplasts were not observed and are presumed to be absent. The gamete is identical, except for the absence of the lower basal body pair and the presence of an electron‐dense membrane associated structure that resembles the mating structure found inUlvagametes. These findings, correlated with life history data, sporangial and gametangial structure and developmental patterns, chloroplast pigment arrays, and vegetative cell ultrastructural features, compel the removal ofEntocladia viridisand similar members of the marine Chaetophoraceae to a separate family, the Ulvellaceae. The latter is referred to the order Ulvales of the Ulvophyceae. The counterclockwise absolute orientation of components, and terminal caps, may be the most consistent flagellar apparatus features of ulvophycean green algae, while variations in other features previously considered diagnostic for the Ulvophyceae may serve instead to identify discrete lineages within this class.
NORTH CAROLINA MARINE ALGAE. XI. A NEW SPECIES OF HELMINTHOCLADIA (LIAGORACEAE, NEMALIALES, RHODOPHYTA) WITH A REAPPRAISAL OF THE GENERIC LIMITS OF HELMINTHOCLADIA AND HELMINTHORA1
Authors: Searles Richard B. , Lewis Sara M. 
Published: November 2004

ABSTRACTA new species in the Liagoraceae (Nemaliales) having vegetative and male reproductive characteristics usually associated with the genus Helminthora is assigned to Helminthocladia (as Helminthocladia andersonii Searles & Lewis) on the basis of the shape of the conical carpogonial protoplast, three‐celled carpogonial filament, development of the carposporophyte from both cells formed by division of the zygote and development of the involucre without the formation of a bridge around the zygote or formation of rhizoids from the involucre. All of these are consistent characteristics of Helminthocladia and distinguish its species from those of Helminthora.
FINE STRUCTURE OF THE SNOW ALGA (CHLAMYDOMONAS NIVALIS) AND ASSOCIATED BACTERIA1
Authors: Weiss Richard L. 
Published: November 2004

ABSTRACTChlamydomonas nivalis(Bau.) Wille is present in red snow as large spherical resting cells. Fine structural studies reveal an abundance of clear granules in the cytoplasm and occasional starch grains in the chloroplast. Individual cells display a thick cell wall with a smooth outer surface. Cells may be surrounded by a loose fibrous network in which encapsulated bacteria are seen. The bacteria have a characteristic Gram‐negative cell wall and constrictive mode of division. The algal‐bacterial association appears to be characteristic of red snow populations.
PRESENCE AND DISTRIBUTION OF BROMINE IN THYSANOCLADIA DENSA (SOLIERIACEAE, GIGARTINALES), A MARINE RED ALGA FROM THE GREAT BARRIER REEF1
Authors: Pallaghy Charles K. , Minchinton Jeff , Kraft Gerald T. , Wetherbee Richard 
Published: November 2004

ABSTRACTElectron‐probe X‐ray microanalysis of freeze dried sections of growing branch tips of Thysanocladia densa Sander shows high concentrations of bromine in the region of the medulla. Indirect evidence infers that the Br is associated with intercellular, granular deposits which accumulate within the mucilage of the medulla. The concentration of Br decreases in older regions of the thalli.
THE MARINE, PLANKTONIC DIATOMS THALASSIOSIRA OCEANICA SP. NOV. AND T. PARTHENEIA1
Authors: Hasle Grethe Rytter 
Published: November 2004

ABSTRACTThe diatom clone 13–1 isolated from the Sargasso Sea by Dr. R. R. L. Guillard as Cyclotella nana Hust. or Thalassiosira pseudonana Hasle and Heimdal is described as a separate species, Thalassiosira oceanica sp. nov. An amplified diagnosis of Thalassiosira partheneia Schrader is given, and a comparison of the two species is made based on light and electron microscopy. Similarities are present in the apparent distribution pattern, cell size, and girdle structure. Differences are present in the shape of the areolae of the valvocopula and the copula, in the structure of the vela of these bands, in the texture of the external valve surface, in the morphology of the strutted processes, in the location of the labiate process, in the distance between the marginal strutted processes, and by the presence of a marginal ridge in T. oceanica. Fifteen nanoplanktonic (maximum diameter = 20 UmUm) Thalassiosira species are listed, among them T. oceanica and T. partheneia.
QUALITATIVE AND QUANTITATIVE OBSERVATIONS ON AQUATIC ALGAL COMMUNITIES AND RECOLONIZATION WITHIN THE BLAST ZONE OF MT. ST. HELENS, 1980 AND 19811
Authors: Ward Amelia K. , Baross John A. , Dahm Clifford N. , Lilley Marvin D. , Sedell James R. 
Published: November 2004

ABSTRACTDespite the destruction and total rearrangement of much of the area north of Mt St. Helens, many different species of algae became established in the aquatic systems located in the blast zone within 3–4 months after the eruption of May 18, 1980. Initial sites of intense algal activity were found in benthic regions associated with warm springs and in the littoral and phytoplanktonic communities of some small lakes. In the summers of 1980–81, overall phytoplankton numbers and activity were low in the large lakes closest to the crater (e.g. Spirit Lake). However, diatoms, blue‐green and green algal isolates from these lakes were obtained in laboratory cultures on a reduced inorganic medium used to enumerate metal and sulfur oxidizing bacteria. Species of Nodularia, Pseudanabaena, Anabaena, Oscillatoria, Nitzschia, Tribonema, Chlamydomonas, Chlorella, and microflagellates (predominantly cryptomonads) were among the more common forms found in preserved samples or isolated in cultures.
LIFE HISTORY AND HYBRIDIZATION STUDIES ONGIGARTINA STELLATAANDPETROCELIS CRUENTA(RHODOPHYTA) IN THE NORTH ATLANTIC1
Authors: Guiry Michael D. , West John A. 
Published: November 2004

ABSTRACTFourteen isolates of the crustose marine red algaPetrocelis cruentaJ. Agardh from various localities in the British Isles, France (including the type locality), Spain and Portugal gave rise in culture to dioecious foliose plants identifiable asGigartina stellata(Stackhouse) Batters although two isolates formed only sterile foliose blades. A total of 145 isolates ofGigartina stellatawere also grown in culture from various localities in the U.S.A. (Maine), the British Isles, Iceland, Denmark, France, Spain and Portugal using both carpospores and vegetative blade apices. Two basic types of life history were found among these isolates: a direct‐type life history involving the formation of further foliose plants from carpospores, some isolates of which also form spermatangia on the same papillae as the cystocarps; and a heteromorphic‐type in which only crustose plants resemblingPetrocelis cruentaare formed from carpospores. Only heteromorphic‐type life histories were found from Spain and Portugal. Both life history types were found in plants from the U.S.A., the British Isles and northern France. Only direct‐type life histories were found in plants from Iceland and Denmark. SomePetrocelis‐like crusts derived from field collectedG. stellatacarpospores andPetroceliscrusts of hybrid progeny formed tetrasporangia in 8:16 h LD, 10° C but not in 8:16 h LD, 15° C; 16:8 h LD 10° C or 15° C; and 10:6.5:1: 6.5 h LDLD, 10° C. The spores thus formed were viable and produced normal dioecious male and female gametophytes. Short day and low temperature conditions appear necessary for tetrasporogenesis. The results from crossing experiments with 32 male and 27 female isolates of the heteromorphic‐type derived from bothG. stellataandP. cruentashowed that two virtually non‐interbreeding populations with a high degree of geographical separation exist in the north‐eastern Atlantic. Morphological differences between plants from each population are described. On the basis of culture and crossing results,Petrocelis cruentaJ. Agardh is placed in synonymy withGigartina stellata(Stackhouse in Withering) Batters.
EFFECTS OF PHOTON FLUENCE RATE AND LIGHT SPECTRUM COMPOSITION ON GROWTH, PHOTOSYNTHESIS AND PIGMENT RELATIONS IN GRACILARIA SP.1
Authors: Beer Sven , Levy Israel 
Published: November 2004

ABSTRACTThe optimal photon fluence rate for growth of tha llus tips of Gracilaria sp. was low (about 100 μE·–2·1); higher photon fluence rates inhibited growth. Both phycoerythrin (PE) and chlorophyll (chl) contents decreased with increasing photon fluence rates (up to 100 μE·–m–2s–1) in a fashion inverse to the growth response. Chl/PE ratios varied directly as the growth response over a larger photon fluence rate range. The peak chl/PE ratios were obtained at a photon fluence rate optimal for growth, suggesting that this parameter may be used to estimate in situ growth rates. A low compensation point (about 7 μE·–2s–1) was observed for low light (15 μE·–2s–1) grown plants. This compensation point was also obtained for growth in the long–term (5–6 weeks) experiments. Plants grown at 60 and 140 μE·–2s–1 showed higher light compensation and saturation points, suggesting that the variations in pigment composition found between the different treatments determine the photosynthetic responses at sub–optimal photon fluence rates. Photosynthetic rates at light saturation were the same, on a biomass basis, for plants grown at the various photon fluence rates. Thus, the photosynthetic dark reactions were not influenced by previous light regimes. It is suggested that maximal photosynthetic rates expressed on a biomass basis better reflect the potential productivity at tight saturation than if expressed on a pigment basis. Gracilaria sp. grew better under non–filtered fluorescent and greenish than under reddish and blue–enriched light of equal and sub–optimal photon, fluence rate. However, the pigment relations of the algae did not change in a direction complementary to the light composition at which they grew. This, together with the relatively higher photosynthetic rates under reddish and blueish light for plants previously grown under reddish and blueish light, suggests that adaptations to variouslight spectra are based on mechanisms different from complementary chromatic adaptation of the pigments.
INTERCEPTION OF ATMOSPHERIC FIXED NITROGEN AS AN ADAPTIVE ADVANTAGE OF SCUM FORMATION IN BLUE‐GREEN ALGAE1
Authors: Lewis William M. 
Published: November 2004

ABSTRACTScum formation by blue‐green algae has been interpreted as a nonadaptive failure of the buoyancy control mechanism and, alternatively, as an adaptive mechanism to reduce inorganic carbon limitation. Data from Lake Valencia, Venezuela, are used to illustrate the principle that scum formers intercept significant amounts of fixed N deposited from the atmosphere at the water surface. Interception of fixed N at the surface can confer a significant selective advantage for populations that are strongly N limited, as in Lake Valencia. This additional adaptive advantage to scum formation may be alternative lo or complementary to the possible relief of carbon limitation.
A SIMPLIFIED, RAPID METHOD FOR IDENTIFYING MATING TYPE IN ALGAE: RESULTS WITH THE PANDORINA MORUM (CHLOROPHYCEAE) SPECIES COMPLEX1
Authors: Coleman Annette W. , Maguire Mark J. 
Published: November 2004

ABSTRACTAs a collection expands, increasing numbers of test crosses are required to identify new isolates in algal species containing numerous pairs of mating types. A short‐cut is described that utilizes a reduced number of preliminary test crosses. The method was used successfully with the colonial green flagellate, Pandorina morum Bory de St. Vincent, to identify a new pair of milling types (syngen) from Japan and five new isolates from China of a previously known syngen. When tested on the 20 previously described syngens, it revealed one unexpected multi‐clone effect on mating. The method should be valuable for identifying newly collected clones, examining potential, interactions among incompatible mating types, and for screening other highly specific inter‐organism interactions such as host‐parasite infections.
Preference and performance of the hyperparasitoid Syrphophagus aphidivorus (Hymenoptera: Encyrtidae): fitness consequences of selecting hosts in live aphids or aphid mummies
Authors: Buitenhuis R. , Boivin G. , Vet L. E. M. , Brodeur J. 
Published: November 2004

Abstract.  1. Theoretical models predict that ovipositional decisions of parasitoid females should lead to the selection of the most profitable host for parasitoid development. Most parasitoid species have evolved specific adaptations to exploit a single host stage. However, females of the aphid hyperparasitoid Syrphophagous aphidivorus (Mayr) (Hymenoptera: Encyrtidae) display a unique and atypical oviposition behaviour by attacking either primary parasitoid larvae in live aphids, or parasitoid pupae in dead, mummified aphids.2. In the laboratory, the correlation between host suitability and host preference of S. aphidivorus on the host Aphidius nigripes Ashmead parasitising the aphid Macrosiphum euphorbiae (Thomas) was investigated.3. The relative suitability of the two host stages was determined by measuring hyperparasitoid fitness parameters (survival, development time, fecundity, sex ratio, and adult size of progeny), and calculating the intrinsic rate of population increase (rm). Host preference by S. aphidivorus females and the influence of aphid defence behaviour on host selection was also examined.4. Hyperparasitoid offspring performance was highest when developing from hosts in aphid mummies and females consistently preferred this host to hosts in parasitised aphids. Although aphid defensive behaviour may influence host selection, it was not a determining factor. Ecological and evolutionary processes that might have led to dual oviposition behaviour in S. aphidivorus are discussed.
Parasitoid behaviour: predicting field from laboratory
Authors: Casas Jerome , Swarbrick Susan , Murdoch William W. 
Published: November 2004

Abstract. 1. Most of what is known about parasitoid behaviour comes from laboratory observations: field quantitative observations on searching parasitoids are extremely difficult to do and are rare. The basic components ofAphytis melinus's response to California red scale (Aonidiella aurantii) were studied in the laboratory: encounter, rejection, drumming, probing, oviposition, and host‐feeding. It was then asked whether these observations provided a reliable guide to behaviour in the field in a situation that was very different from the laboratory.2. Field observations were carried out on bark on the trunk and interior branches of trees where live scale density is extremely high in patches, dead scale make up 90% of all scale, and could be expected to interfere withAphytissearch.3. The laboratory observations predicted well the time taken in the field for each basicevent(drumming or probing) and average times spent on a scale. Also well predicted were the distributions of times spent on drumming, probing, and total time on a scale. Rejection rates were much higher in the field. Thus, the laboratory studies predicted foraging behaviour in the field with variable success; potential explanations for observed mismatch between laboratory and field and its possible larger implications are discussed.
Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata
Authors: Pitts K. M. , Wall R. 
Published: November 2004

Abstract.  1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north‐western Europe.2. Populations of marked flies in six, 1 m3, outdoor field cages and unmarked wild flies at two farms in south‐west England were studied simultaneously between May and September 1998.3. In the field, wild female L. sericata were caught and aged using a combination of wing‐fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% (± 0.037) and 2.09% (± 0.044) per day‐degree and mean life expectancy of 51.5 and 47.9 day‐degrees above a threshold of 11 °C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively.4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day‐degree (± 3.49 × 10−4%) and the mean life expectancy was 123.1 day‐degrees above a threshold of 11 °C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best‐fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition.5. The differences between the field and cage populations highlight the caution required when extrapolating life‐history parameters from artificial to natural habitats.