bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of hydrothermal temperature on SnO
2 nanorod formation
Authors: Khuc Quang Trung , Hien Vu Xuan , Vuong Dang Duc , Chien Nguyen Duc
Published: August 2010

SnO
2 nanorods were successfully prepared by a hydrothermal method using tin chloride, liquid ammonia, sodium hydroxide and cetyltrimethyl ammonium bromide (CTAB) as starting materials. Structural properties and surface morphologies of the SnO
2 nanorods were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Experimental results showed that the diameter of the nanorods is in the range of 100–300 nm with a length of several micrometers. The hydrothermal treatment temperature was found to play an important role in determining the morphology and diameter of the SnO
2 nanorods. Possible growth mechanisms of SnO
2 nanorods were proposed.
Population Structure, Mating Type, and Mefenoxam Sensitivity of Phytophthora nicotianae in Virginia Tobacco Fields
Authors: Parkunan V. , Johnson C. S. , Bowman B. C. , Hong C. X.
Published: August 2010

Black shank is an important disease of tobacco (Nicotiana tabacum) caused by the fungus-like organism, Phytophthora nicotianae. Three physiological races (0, 1, and 3) have been documented in the United States. Shifts in the pathogen population structure have become a concern due to the widespread use of cultivars possessing resistance to race 0 arising from a single gene (Php or Phl). A comprehensive statewide survey conducted throughout major tobacco-growing areas during summer 2006 and supplemented by additional isolates in 2007 and 2008 yielded 217 isolates from flue-cured, burley, and dark fire-cured tobacco fields. After determining species identity using a single-strand conformational polymorphism fingerprinting technique, the race identity of isolates was assessed via greenhouse tests using three differential cultivars (Hicks, L8, and NC1071). Approximately 76% of the isolates belonged to race 1, 21% to race 0, and the remaining 3% were race 3. This race structure was comparable with those in the other tobacco-producing states in the United States. Approximately 94% of isolates belonged to A2 mating type and merely 6% were A1. These data suggest that it is unlikely that sexual recombination serves as a major mechanism enhancing the genetic diversity of the pathogen in Virginia. All isolates were also evaluated against mefenoxam at 5 μg/ml. None were insensitive; 98% of isolates were either highly sensitive or sensitive and the remaining 2% were intermediately sensitive. These results indicate that mefenoxam remains effective for control of black shank in Virginia. The results of this study can assist breeders to develop cultivars possessing the most appropriate set of disease resistance traits, as well as extension specialists, county agents, and tobacco growers in their decision-making process to manage tobacco black shank in Virginia.
Relative addition rate and external concentration; Driving variables used in plant nutrition research
Authors: INGESTAD TORSTEN
Published: August 2010

Abstract An increasing literature accounting for various types of experiments indicates that far lower external nutrient concentrations are required by plants than is usually thought to be the case. It is concluded that the ion uptake capacity of the roots, as described by the carrier concept, is high compared to that required for maintenance of the internal concentration. Serious errors in experimental conclusions are associated with insufficient and constant nutrient addition rates. The main errors are caused by non‐steady states of the plants both with regard to the internal nutrient concentrations and the relative growth rate.

A dynamic concept has been proposed for direct use as the treatment variable within the range of sub‐optimum nutrition. The nutritional factor is expressed as a flow, the relative nutrient addition rate in laboratory studies and the nutrient flux density in the field. The experimental use of the relative addition rate has led to steady‐state nutrient status and relative growth rate and the interpretation of plant responses which differ fundamentally from accepted views. Thus, for instance, deficiency symptoms disappear, as in natural conditions, when the internal nitrogen concentration is stable, independent of level. The nutrition/growth relationships are very different from those observed when external concentration is varied. The regression line of relative growth rate on relative addition rate passes near to the origin at an angle close to 45 to the axes, which implies that the obtained relative growth rate approximates closely the treatment variable. A striking example of observed differences is the positive effect on nitrogen fixation exerted by high relative nitrogen addition rates compared to the well‐known negative effect of increasing external nitrogen concentration.

The application of fertilizer on the basis of the nutrient flux density concept provides the possibility of supplying fertilizers corresponding to the consumption potential of the vegetation and to the natural flux density resulting from mineralization in the soil. Nitrogen utilization is high under such conditions and the resulting feedback of nutrition on the mineralization rate suggests that there will be a long‐term increase in fertility.
Stomatal behaviour and water movement through roots of wheat plants treated with abscisic acid
Authors: DAVIES W. J. , RODRIGUEZ J. L. , FISCUS E. L.
Published: August 2010

Abstract Experiments with isolated roots of wheat plants suggested that when water uptake rates are low, low concentrations of abscisic acid (ABA) may increase the flux of water into roots. This increase was recorded despite an ABA‐stimulated reduction in the hydraulic conductance of the whole root system. Hydraulic conductances were measured under steady‐state conditions. A system is described where the stomatal behaviour and water movement through roots of a single intact plant may be concurrently monitored. Experiments with intact plants confirmed that application of ABA could increase the rate of water movement into roots when uptake rates were low. No such increase was observed at high flux rates. Application of ABA to roots caused partial stomatal closure and caused conductance to oscillate around a reduced mean value. An ABA‐stimulated increase in the turgor sensitivity of stomata is postulated and the significance of this effect is discussed.
Evidence that a mustard seedling responds to the amount of Pfr and not to the Pfr/Ptotratio
Authors: SCHMIDT R. , MOHR H.
Published: August 2010

Abstract Phytochrome‐mediated anthocyanin synthesis of the mustard seedling (Sinapis alba L.) was investigated. Light pre‐treated and dark‐grown seedlings differing in responsiveness and level of phytochrome (Ptot) were compared. The data obtained support the traditional view that a seedling measures the amount of Pfr. The alternative view that a plant measures the Pfr/Ptot ratio does not seem to be compatible with the data obtained with the mustard seedling.
Two Heads Aren’t Always Better Than One
Authors: Bobaljik Jonathan David , Thráinsson Höskuldur
Published: August 2010

We propose a novel theory of verb raising in which different surface positions of the finite verb across languages reflect differences in phrase structure in a principled manner. Assuming that the inventory of functional projections dominating VP is not universal (e.g., the presence of Agr‐Phrases is a point of parametric variation) current assumptions about locality predict obligatory verb raising in a language with Agr‐Phrases, but obligatory V in situ in a simple IP‐VP configuration. We predict a correlation with other morpho‐syntactic phenomena reflecting the presence/absence of AgrPs: “extra” subject and object positions, transitive expletive constructions, multiple infelectional affixes, etc. This prediction is borne out for the VO Germanic languages; for the OV languages we predict the existence of head‐final Infl projections.
Women Managers, Gendered Cultural Processes and Organizational Change
Authors: Green Eileen , Cassell Catherine
Published: August 2010

This paper develops a critical approach towards the nature of research and knowledge about Women in Management (WIM). A variety of perspectives in the WIM area are reviewed from an inter‐disciplinary standpoint. Drawing on radical approaches to organization analysis, the paper aims to evaluate the insights provided into the position of women in management from the perspectives outlined. It is argued that feminist approaches which focus on the gendered nature of organizational processes and in particular organizational cultures, represent an important way forward in the development of adequate theorizations of the position of women managers. The paper examines the implications of this analysis for the Women in Management research agenda and explores appropriate strategies for organizational change within this arena.
Gendered Organizational Cultures: Narratives of Women Travellers in a Male World
Authors: Gherardi Silvia
Published: August 2010

The paper will present various self‐identity narratives of women pioneers in male occupations who ‘take their place’ in a male gendered organizational culture. These narratives belong to a single discourse of what may be called ‘travellers in a male world’. This discourse presumes the existence of a territory marked out as male which is trespassed upon by females who are formally members of the same occupational community, but who, in actual practice, must stake out their positions in the field. Social structures coerce discourse positions and set up a series of expectations and social obligations, although several subject positions can be taken up for oneself, and for the ‘other’. This process has been labelled ‘positioning gender relations within an organizational culture’ and has been described as liminal work, performed discursively and in transitional spaces. Gender relations can therefore be viewed as cultural performances learned and enacted on appropriate occasions both by men and women.
Equality Management – Towards a Materialist Approach
Authors: Miller Doug
Published: August 2010

Attempts to redefine equality initiatives to fit squarely within the enterprise culture serve only to mask an ongoing conceptual confusion in the area of equality management. This theoretical article attempts to show that this conceptual confusion lies within the narrowness of approaches which address labour market inequalities from both an equality of opportunity and an equality of outcome perspective. The inability of these perspectives to satisfactorily address systemic causes of labour market inequalities pulls our attention towards a more materialist approach which may be found (this side of a capitalist/patriarchal society) within an equality of condition frame of reference. This widens the perspective from which equality management can be pursued so that measures to address the differential distribution of resources, rewards, opportunities and treatment in the workplace are informed by all three equalities: opportunity, outcome and conditions. Such a theoretical approach is inevitably limited in that it only provides a framework for addressing those who are in paid employment, i.e. seeks to reform the capitalist/patriarchal system. However, by posing questions of the crucial pillars of such systems notably status, reward and with that power, the ‘long’ and ‘radical’ agendas of the equality project may once again be picked up.
Continuity of Midwifery Care in England: A New Professional Project?
Authors: Sandall Jane
Published: August 2010

Over the last decade, an increasing amount of research has examined the relationship between gender and professionalization using female professional projects to illustrate how the generic notion of a profession has been a gendered one.

This paper develops Witz’s (1990) theory of professional strategies in female‐dominated occupations particularly regarding midwives in Britain in the twentieth century and suggests that an important dimension that also needs to be critically examined in midwifery history is the interaction of gender and social class within midwifery. Furthermore it documents the traditional emphasis in midwifery on the single women’s career path. This historical analysis has resonance today as midwifery in Britain is undergoing a renaissance. The role of the midwife and the current organization of the maternity services are being reviewed with the intention of providing increased choice and control over the reproductive process for women and increased continuity of care with a midwife. These changes are viewed as midwives’ new professional project and the implications for midwives and women discussed.

The aim of this paper is to explore the explanatory power of these approaches to current developments in maternity care and by drawing historical parallels, consider the impact that this professionalizing strategy may have for those who are excluded from this process of ‘dual closure’. Furthermore, this paper asks whether this new way of working empowers midwives, women, both or neither?
Feminist geography, the ‘everyday’, and local–global relations: hidden spaces of place‐making*
Authors: Dyck Isabel
Published: August 2010

An interest in the taken‐for‐granted, mundane routine activities of women's lives has long been central to the production of knowledge in feminist geography. Here, I revisit the ‘everyday’ in relation to changing lines of inquiry as geographers work to capture the complexity of local–global relations in conceptualising an accelerated pace of the stretching of social relations over space. Through a primary focus on feminist work on care in the home, I explore the various ways in which the meanings and organisation of caregiving activity are intricately connected with the intertwining of globalisation, neoliberalism, social conservatism and a ‘greying’ population in the West. Foregrounding gender in my discussion, I review literature and draw on research examples to illustrate ways in which various types of ‘hidden’ caregiving contribute to contemporary place‐making, and open up our understanding of the ‘local’.
How green is the valley? Foreign direct investment in two Norwegian industrial towns
Authors: Jakobsen Stig‐Erik , Rusten Grete , Fløysand Arnt
Published: August 2010

Since the early 1900s, foreign direct investments (FDIs) have greatly affected Norwegian society, especially peripheral communities. This article analyses how transnational corporations (TNCs) use territory down to the local level, and how this complex relationship between firms and spaces is shaped by attributes related to the TNC and the characteristics of the local economy. An extensive literature discusses different types of effects and spillovers, such as vertical supply linkages and spin‐offs, but theoretical explanations of outcomes are more difficult. The literature links positive as well as negative outcomes to local conditions and to the investment motives of the entity making the FDI, but says little about how these vary with types of business, communities and national economies, and how these interactions generate different outcomes. We conclude that FDIs have different abilities to transform an area. We argue that FDI can trigger path‐dependent dependency when it is dominated by economic capital and path‐dependent development when it consists of a balance of economic capital, social networks and knowledge. This variation in the effects of FDI is illustrated by an empirical analysis of two industrial towns in Western Norway, one with natural resources and the other with intangible technology resources.
A Domain‐level Approach to Describing Growth in Achievement
Authors: Schulz E. Matthew , Lee Won‐Chan , Mullen Ken
Published: August 2010

Descriptions of growth in educational achievement often rely on the notion that higher‐level students can do whatever lower‐level students can do, plus at least one more thing. This article presents a method of supporting such descriptions using the data of a subject‐area achievement test. Multiple content domains with an expected order of difficulty were defined within the Grade 8 National Assessment of Educational Progress (NAEP) in mathematics. Teachers were able to reliably classify items into the domains by content. Using expected percentage correct scores on the domains, it was possible to describe each achievement level boundary (Basic, Proficient, and Advanced) on the NAEP scale by patterns of skill that include both mastery and non‐mastery, and to show that higher achievement levels are associated with mastery of more skills. We conclude that general achievement tests like NAEP can be used to provide criterion‐referenced descriptions of growth in achievement as a sequential mastery of skills.
A Comparison of IRT Equating and Beta 4 Equating
Authors: Kim Dong‐In , Brennan Robert , Kolen Michael
Published: August 2010

Four equating methods (3PL true score equating, 3PL observed score equating, beta 4 true score equating, and beta 4 observed score equating) were compared using four equating criteria: first‐order equity (FOE), second‐order equity (SOE), conditional‐mean‐squared‐error (CMSE) difference, and the equipercentile equating property. True score equating more closely achieved estimated FOE than observed score equating when the true score distribution was estimated using the psychometric model that was used in the equating. Observed score equating more closely achieved estimated SOE, estimated CMSE difference, and the equipercentile equating property than true score equating. Among the four equating methods, 3PL observed score equating most closely achieved estimated SOE and had the smallest estimated CMSE difference, and beta 4 observed score equating was the method that most closely met the equipercentile equating property.
CELL DIVISION AND FILAMENT FORMATION IN THE DESMIDBAMBUSINA BREBISSONII(CHLOROPHYTA)1
Authors: Krupp Jonathan M. , Lang Norma J.
Published: August 2010

Cell division and semicell expansion in the filamentous desmidBambusina brebissoniiKütz. were investigated using transmission and scanning electron microscopy. Interphase cells are typical of desmids, containing a full complement of organelles and a cell wall penetrated by complex pores, but the cells lack a well‐defined median constriction. Cell division involves an open spindle and the centripetal growth of a primary septum formed by the fusion of small, dark‐staining vesicles probably derived from dictyosomes. Telophase nuclei are separated by a system of interzonal microtubules and numerous large, lighter‐staining vesicles also derived from the dictyosomes. Following cell division, an elaborate replicate cross wall is formed which consists of both primary and secondary wall layers. During semicell expansion, a portion of the primary wall splits apart as the new semicells evaginate and expand to their full size. The primary wall stops splitting at a thick ring of secondary wall material leaving the cells united by the remaining common layer of primary wall. When semicell expansion is completed, the primary wall is not shed from the lateral walls of the new semicells, and pores through both primary and secondary wall layers begin to produce sheath material. However, pores in the end walls of cells do not function unless the filament is broken. The intact primary wall between cells and the absence of sheath production between cells comprise the mechanism serving to hold the cells ofBambusina brebissoniitogether in long filaments.
INTERACTIONS OF LIGHT/DARK CYCLES AND NITROGEN PULSES ON THE TIMING OF CELL DIVISION IN THE NITROGEN‐LIMITED MARINE DIATOM CYLINDROTHECA FUSIFORMIS (BACILLARIOPHYCEAE)1
Authors: Plumley F. Gerald , Darley W. Marshall
Published: August 2010

Cell division in most eukaryotic algae grown on alternating periods of light and dark (LD) is synchronized or phased so that cell division occurs only during a restricted portion of the LD cycle. However, the phase angle of the cell division gate, the time of division relative to the beginning of the light period, is known to be affected by growth conditions such as nutrient status and temperature. In this study, it is shown that the phase angle of cell division in a diatom, Cylindrotheca fusiformis Reimann and Lewin, is affected by the N‐limited growth rate; cell division occurred later in the dark period (12:12 h LD cycle) when the growth rate was infradian (D = 0.42 d−1) than when it was ultradian (D = 1.0 d−1). Nitrogen‐pulses did not affect the phase angle of the division gate, but could shift the time of peak cell division activity within the division gate. The effects, if any, of N‐pulses were dependent upon the growth rate and the time of day that the pulses were administered. These responses indicate that the timing of cell division in this diatom is not determined solely by the zeitgeber from the LD cycle, but rather that a LD cycle control mechanism and a N‐mediated control mechanism are both involved and are somewhat interdependent. In addition, an increase in protein was observed immediately after administering a N‐pulse to C. fusiformis in the ultradian growth mode indicating that the accumulation of protein can be uncoupled from the cell division cycle.
COLONIZATION OF THE EPINEUSTON BY CYSTODINIUM BATAVIENSE(DINOPHYCEAE): BEHAVIOR OF THE ZOOSPORE1
Authors: Timpano Peter , Pfiester Lois A.
Published: August 2010

Cystodinium bataviense Klebs is the first dinoflagellate observed to exhibit specialized zoospore behavior which results in colonization of the epineuston. The zoospore: (1) is strongly phototactic; (2) changes shape rapidly upon release; (3) possesses at least two types of swimming behavior, including a “stop mechanism”; and, (4) sheds its theca as the new cell wall asymmetrically elongates into the immobile vegetative stage. These features working in concert facilitate the entrance of Cystodinium into the epineuston. Detailed observations of zoospore morphology and analysis of its behavior are used as new characters to further delimit C. bataviense. Since vegetative morphology has proven unsatisfactory in circumscribing other Cystodinium species, the study of variation in zoospore characters will help to clarify taxonomic units within the genus.
KINETICS OF PHOSPHATE TRANSPORT BY SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYTA): EVIDENCE FOR DIFFUSION LIMITATION OF PHOSPHATE UPTAKE1
Authors: Mierle Greg
Published: August 2010

The kinetics of phosphate transport by Synechococcus leopoliensis (Racih.) Komarek was investigated. Deviations from Michaelis‐Menten kinetics were observed at law concentrations of phosphate and the deviations were consistent with diffusion limitation of transport. Activation energy analysis of the transport process at two concentrations, one at carrier saturation and the other at zero added phosphate yielded activation energies of 11.9 and 5.6 kcal/mole respectively at 25° C. The first is consistent with an enzyme limited process and the second with diffusion limitation through the unstirred layer.
ULTRASTRUCTURE OF AUXILIARY AND GONIMOBLAST CELLS DURING CARPOSPOROPHYTE DEVELOPMENT IN FAUCHEOCOLAX ATTENUATA (RHODOPHYTA)1
Authors: Kugrens Paul , Delivopoulos Stylianos G.
Published: August 2010

The ultra structure of post‐fertilization development in Faucheocolax attenuata Setch. is described. Following fertilization and transfer of the diploid nucleus to the auxiliary cell, four gonimoblast initials usually are produced of the multinucleate auxiliary cell. Gonimoblast initials originally are uninucleate but undergo karyokinesis to form multinudeate gonimoblast cells. Terminal or generative gonimoblast cells cleave successively to form lobes of incipient carpospores, with each group of spores differentiating synchronously. Portions of the initial generative gonimoblast cells, however, remain to resume karyokinesis and repeat the process of cleavage into carpospores. Axial gonimoblast cells are transformed into secretory cells, which produce mucilage. Generative gonimoblast cells and auxiliary cells are similar in cellular structure. Both contain typical red algal proplastids, some dictyosomes, cytoplasmic concentric membranes, and numerous small vesicles. In addition, dark staining spherical masses, occurring in the cytoplasm of all cell types, may represent dehydrated haploid chromatin. Large septal plugs interconnect gonimoblast cells and the auxiliary cell. These plugs are small when first formed but increase dramatically in size during carposporophyte development.
CELL DIVISION AND THE ROLE OF THE PRIMARY WALL IN THE FILAMENTOUS DESMIDONYCHONEMA LAEVE(CHLOROPHYTA)1
Authors: Krupp Jonathan M. , Lang Norma J.
Published: August 2010

Cell division and the role of the primary wall in filament formation in the desmidOnychonema laeveNordst. were investigated by transmission and scanning electron microscopy. In addition, sequential chemical extractions and enzyme treatments were performed, on cell walls of intact filaments. Interphase cells are deeply constricted, consisting of two semicells, each elliptical in front view and circular in side view. In addition to two short lateral spines, each semicell has two apical processes that originate on opposite sides at an angle of about 15° from the central axis and overlap the adjacent cell. Division is initiated as in other desmids by a slight separation of the semicells and development of a girdle of primary wall material at the isthmus. InO. laevethe girdle of primary wall expands to form a spherical vesicle (termed a division vesicle) between the separating semicells. Nuclear division and septum formation occur in this vesicle when it is nearly the full diameter of the filament. Morphogenesis of the apical processes begins with completion of the septum, before the secondary wall appears. At maturity each apical process is surrounded by a thick layer of both secondary and primary wall, except that its capitate tip protrudes through the shroud of primary wall. Sequential treatment with hot ammonium oxalate, 4% NaOH, 17.5% NaOH and 10% chromic acid or various enzyme solutions did not cause filament breakage. SEM and TEM views ofO. laeveafter these treatments show intact secondary walls and intact primary wall material covering and connecting the apical processes of adjacent cells. It is the persistence of the primary wall between cells and around the apical processes that maintains the long, unbranched filamentous morphology ofOnychonema laeve.
THE INFLUENCE OF SEA ANEMONES ON THE MORPHOLOGY AND PRODUCTIVITY OF TWO INTERTIDAL SEAWEEDS1
Authors: Taylor Phillip R.
Published: August 2010

The intertidal seaweeds Corallina vancouveriensis Yendo and Gelidium coulteri Harv. respond to the experimental removal of associated mats of the clonal anemone Anthopleura elegantissima Brandt with morphological changes that affect their photosynthetic performances. With the removal of anemones, these seaweeds develop a tight compaction of thalli which aids in the retention of moisture during aerial exposure. The morphological response, however, results in greatly reduced net photosynthesis in C. vancouveriensis (–98%) and G. coulteri (–73%) on an areal basis. Association with the clonal anemones allows these seaweeds to maintain a morphology that is more highly productive yet inconsistent with the exposure stresses in many microhabitats at similar tidal levels.
BACTERIAL INFLUENCE UPON GROWTH AND HYDROCARBON PRODUCTION OF THE GREEN ALGABOTRYOCOCCUS BRAUNII1
Authors: Chirac Christian , Casadevall Eliette , Largeau Claude , Metzger Pierre
Published: August 2010

Batch cultures of the hydrocarbon‐rich algaBotryococcus braunii,Kütz. (axenic strains, non‐axenic strains, associations with selected microorganisms) were examined with regard to total biomass and hydrocarbons at the onset of the stationary phase. Pronounced variations, related to the origin of the strains and to growth conditions, were observed with axenic cultures. It also appeared that the presence of microorganisms is not essential for high hydrocarbon production. Nevertheless, numerous bacteria were shown to exert considerable influence, antagonistic or beneficial, onB. brauniigrowth yield and hydrocarbon production. Such effects were strongly dependent on the species involved and on culture conditions. The presence of various microorganisms can influence not only the quantity of hydrocarbons produced, but also their level in the algal biomass and their relative abundance. However, their chemical structure is not affected. Intricate relationships were observed inB. braunii‐bacteria systems and numerous factors (including, in some cultures, large positive effects due to bacterially produced CO2) were implicated. Accordingly, specific associations should provide appropriate conditions for renewable hydrocarbon production viaB. brauniilarge scale cultures.
SPORE FORMATION IN THE LIFE CYCLES OF THE DIATOMS CHAETOCEROS DIADEMA AND LEPTOCYLINDRUS DANICUS1
Authors: French Fred W. , Hargraves Paul E.
Published: August 2010

A nitrogen limitation technique elicited the entire life cycle of the marine centric diatoms Chaetoceros diadema (Ehr.) Gran and Leptocylindrus danicus Cleve. In C. diadema the sexual cycle followed the same pattern as in the previously investigated C. didymus. Sexuality took place in narrow diameter cells, only at 2 and 5° C, and was seldom seen. Resting spore formation took place in cells of all sizes and at all temperatures at which the species grew vegetatively (2–15° C). The L. danicus life cycle is probably unique among diatoms. Nitrogen depletion induced sexuality in the entire culture at 10 and 15° C if the cell diameter was narrow (3–8 μm). Auxospore formation was followed by resting spore formation directly within the auxospore. In C. diadema, as in most centric diatoms, resting spores are not an obligate part of the life cycle, but they are in L. danicus. Resting spore formation is a versatile adaptive response in C. diadema, depending only on nitrogen depletion, although promoted by low temperatures. In L. danicus the linkage to the sexual process sharply limits conditions under which resting spores can form.
MITOSIS AND CELL DIVISION IN CYLINDROCAPSA GEMINELLA (CHLOROPHYCEAE)1
Authors: Sluiman Hans J.
Published: August 2010

Mitosis and cell division were studied in the green alga Cylindrocapsa geminella Wolle with transmission electron microscopy. Vegetative cells possess a parietal, lobed chloroplast, and a central pyrenoid. Prophase and metaphase nuclei are surrounded by 1–3 layers of perinuclear endoplasmic reticulum. At early prophase a small number of perinuclear microtubules (MTs) are present while at late prophase MTs are concentrated at the presumptive spindle poles. At the same time, MTs begin to appear in the nucleoplasm. Metaphase spindles are diamond‐shaped and centric. During telophase, centrioles migrate towards the center of the equatorial zone, presumably guided by a small group of perinuclear MTs. A second system of MTs develops in the equatorial plane, initially consisting of randomly orientated microtubular elements. Later they tend to run in a predominantly radial direction although a common MT focal point or organizing center is not apparent. The two centriole complexes remain at the center of the equatorial plane until well into interphase, facing each other across the newly formed transverse septum. Centrioles are associated with root templates and connecting fibers. The present observations corroborate the view that C. geminella does not form a true filament in the ulotrichalean or chaetophoralean sense, but rather consists of a row of autospores. Its affinity with other “pseudo‐filamentous” green algae and the Chlorococcales is discussed. The interpretation of the cytokinetic MTs in C. geminella as a phycoplast appears to be problematic.
STEADY‐STATE LUXURY CONSUMPTION AND THE CONCEPT OF OPTIMUM NUTRIENT RATIOS: A STUDY WITH PHOSPHATE AND NITRATE LIMITED SELENASTRUM MINUTUM (CHLOROPHYTA)1
Authors: Elrifi Ivor R. , Turpin David H.
Published: August 2010

Selenastrum minutum (Naeg.) Collins was grown over a wide range of growth rates under phosphate or nitrate limitation with non‐limiting nutrients added to great excess. This resulted in saturated luxury consumption. The relationships between growth rate and cell quota for the limiting nutrients were well described by the Droop relationship. The observed variability in N cell quota under N limitation as reflected in kQ·Qmax−1*, was similar in magnitude to previously reported values but kQ·Qmax−1* for P under P limitation was greater than previously reported for other species. These results were evaluated in light of the optimum ratio hypothesis. Our findings support previous work suggesting that the use of a single optimum ratio (kQi·KQj−1) is inappropriate for dealing with a species growing under steady‐state nutrient limitation. Under these conditions the optimum ratio should be viewed as a growth rate dependent variable. Two approaches for testing the growth rate dependency of optimum ratios are proposed.

The capacity for luxury consumption differed between nutrients and was growth rate dependent. At low growth rates, the coefficient of luxury consumption (Rsat) for P was ca. four times that for N. The set of all possible relationships between N and P cell quota under these conditions was reported and these values were then used to establish the cellular N:P niche boundaries for S. minutum. Cell quotas of non‐limiting nutrients were not described by the Droop equation. Analysis showed that as the cellular N:P ratio deviates from the optimum ratio, the ability of the Droop equation to describe the relationship between growth rate and non‐limiting cell quotas decreases. When non‐limiting nutrient cell quotas are saturated, the Droop equation appears to be invalid. Previously reported patterns of non‐limiting nutrient utilization are summarized in support of this conclusion. The physiological and ecological consequences of luxury consumption and growth rate dependent optimum ratios are considered.
THE FLAGELLAR APPARATUS OF OXYRRHIS MARINA (PYRROPHYTA)1
Authors: Roberts Keith R.
Published: August 2010

The three‐dimensional structure of the flagellar apparatus in the dinoflagellate Oxyrrhis marina has been reinvestigated and found to consist of several previously unknown components and component combinations that appear strikingly similar to those of some gymnodinoid taxa.

The flagellar apparatus of this dinoflagellate is asymmetric and extremely complex consisting of a longitudinal and a transverse basal body that gives rise to eight structurally different components. The only posteriorly directed component is the large microtubular root that consists of 45–50 microtubules at its origin and is attached proximally to a perpendicularly oriented striated fibrous component. Arising from each basal body, two striated fibrous roots with different periodicities extend to the cell's left. A single stranded microtubular root with associated electron dense material emanates from the transverse basal body and also extends to the cell's left. A striated fibrous connective arises from the longitudinal basal body and extends toward the cell's right ventral surface and terminates near the sub‐thecal microtubular system. A compound root consisting of microtubules and electron dense material also originates from the longitudinal basal body and extends ventrally into the anterior region of the tentacle.

Structural similarities between the parallel striated fibrous roots of Oxyrrhis and Polykrikos are discussed as are flagellar apparatus similarities among other gymnodinoid dinoflagellates. A diagrammatic reconstruction of the Oxyrrhis flagellar apparatus is also presented.
AN INVESTIGATION OF DISTRIBUTIONAL PATTERNS IN THE DIATOM FLORA OF NETARTS BAY, OREGON, BY CORRESPONDENCE ANALYSIS1
Authors: Whiting Mark C. , McIntire C. David
Published: August 2010

Distributional patterns in assemblages of epiphytic and sediment‐associated diatoms were investigated in Netarts Bay, Oregon. The method of reciprocal averaging revealed a floristic discontinuity between the epiphytic and sediment samples in ordination space. The basis for this discontinuity was the presence of a large number of sediment‐associated taxa that were either very rare or not observed in the epiphytic samples. Within the sediment samples, the diatom flora formed a distributional continuum which had relatively high correlations with mean grain size, a sediment sorting coefficient, and the organic matter content of the sediment. A comparison of the flora in Netarts Bay with floras in other Oregon estuaries indicates that epiphytic, epilithic, and sediment‐associated diatom assemblages do not exhibit conspicuous latitudinal changes along the coast of Oregon, and that many of the same taxa can be expected to occur in samples from comparable habitats in estuaries throughout the temperate regions of the world.
EFFECTS OF SELENIUM DEFICIENCY ON THE MORPHOLOGY AND ULTRASTRUCTURE OF THE COASTAL MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)1,2
Authors: Doucette Gregory J. , Price Neil M. , Harrison Paul J.
Published: August 2010

The effects of selenium deficiency on the siliceous and nonsiliceous components of the planktonic marine diatom Thalassiosira pseudonana (Hust.) Hasle and Heimdal (clone 3H) are examined using light and electron microscopy. Selenium deficiency induces elongation along the pervalvar axis initially as a result of chain formation caused by the failure of sibling cells to separate and subsequently by cell elongation via the production of hyaline girdle bands. In Se‐deficient cultures cell elongation involves the blockage of both mitotic and cytokinetic components of cell division. Selenium deficiency results in ultra‐structural alterations in the reticular membrane system and in mitochondrial and chloroplast membranes. Various types of inclusions are seen in vacuolar areas and the accumulation of lipid reserves is evident in Se‐deficient cells. These results provide indirect evidence for a metabolic Se requirement in this algal species.
OCCURRENCE OF THREENITZSCHIA(BACILLARIOPHYCEAE) TAXA WITHIN COLONIES OF TUBE‐FORMING DIATOMS1
Authors: Carr Jennifer M. , Hergenrader Gary L.
Published: August 2010

In benthic samples from the unchannelized Missouri River, the diatomsNitzschia dissipata(Kütz.) Grun.,N. filiformis(W.Sm.) Schütt andN. pseudofonticolaHust. were observed within the mucilage tubes of four tube‐forming diatoms: Cymbella prostrata(Berk.) Cl.,C. prostratavar.auerswaldii(Rabh.) Reim.,Navicula tripunctatavar.schizonemoides(V.H.) Patr., andNitzschia filiformis.Microscopical observations of live and preserved specimens indicated that “invasion” byNitzschiaoccurred primarily in older tubes. Data are presented on the environmental conditions in which the tube‐formers and their cohabitants have been found.
KINETICS OF NUTRIENT UPTAKE AND GROWTH IN PHYTOPLANKTON1
Authors: Morel François M. M.
Published: August 2010

Microscopic algae ran grow rapidly in natural waters that are extremely low in essential macro and micro nutrients. Yet, their nutrient uptake systems exhibit only mediocre nutrient affinities, the saturation constants being often 10–1000 times the (estimated) ambient concentrations. The large difference which exists between the saturation constants for growth (Kμ) and short term uptake (Kρ) are due to the acclimation capabilities of the organisms. Over the acclimation range, Kμ to Kρ, the algae can maintain maximum growth rate by modulating both their internal nutrient quotas (Q) and their maximum short term nutrient uptake rates (ρmax) in response to variations in external nutrient concentrations. The commonly assumed hyperbolic relationships for steady growth and uptake (viz “chemostat theory”) are coherent with a hyperbolic expression for short term uptake including a variable maximum (ρmax). The ratio of the saturation constants for growth and uptake is then directly related to the extreme in quotas and maximum uptake rates:

Kμ/Kρ= Qmin/Qmax·ρlomax/ρhimax. This result is applicable even when the exact hyperbolic laws are not. Published data on Fe, Mn, P and N limitation in algae are generally in accord with the theory and demonstrate a wider acclimation range for trace than for major nutrients.
NOSTOC (CYANOPHYCEAE) GOES NUDE: EXTRACELLULAR POLYSACCHARIDES SERVE AS A SINK FOR REDUCING POWER UNDER UNBALANCED C/N METABOLISM1
Authors: Otero Ana , Vincenzini Massimo
Published: August 2010

Many species of the filamentous N2‐fixing heterocyst‐forming Cyanobacteria of the genus Nostoc produce large amounts of extracellular polymeric substances (EPS), but hitherto no general model has been proposed of the factors that control their synthesis. Previously, we demonstrated a strong correlation between the presence of a glycocalyx (or EPS capsule) and diazotrophic growth in the genus Nostoc. When grown with nitrate, nude morphotypes lacking a glycocalyx were obtained for all the capsulated strains tested. CO2 availability was pro‐posed as a key factor that controls the synthesis of the capsule. To test this hypothesis, Nostoc PCC 7936 was cultured diazotrophically (N2) or with nitrate with different CO2 supplies. By tuning the pH and the supply of CO2, capsulated or nude mor‐photypes were obtained irrespective of the source of nitrogen. Exocellular polysaccharides were synthesized only when the fixed carbon exceeded the amount of nitrogen available. The glycocalyx is not needed for the optimal functioning of nitrogenase because diazotrophic cultures grew equally well, irrespective of whether they were capsulated or nude. Capsulated cultures possessed protein to carbohydrate ratios that ranged between 1 and 1.5, whereas in nude cultures the ratio ranged between 2 and 2.5. Low protein to carbohydrate ratios were indicative for either nitrogen‐limited or carbon‐oversaturated cultures. The results demonstrate that in Nostoc EPS serve as a sink for the excess fixed carbon under unbalanced C/N metabolism.
TABLET SENSITIVITY TESTING: A COMPARISON OF DIFFERENT METHODS
Authors: Casals Jose Bou , Pedersen O. Gylling
Published: August 2010

Regression lines and their equations have been prepared for Neo‐Sensitabs® containing 26 different antimicrobials, using two different agar media and three different methods: usual without pre‐diffusion, 1 hour pre‐difusion and 1 + 20‐hour pre‐diffusion. The numerical value of the slope of a regression line indicates in mm the mean change in zone diameter for a 2‐fold change in MIC. The numerical value of the slope is increased when pre‐diffusion methods are employed, reaching its maximum with 1 + 20‐hour pre‐diffusion method. When comparing two agar media: Mueller Hinton and Danish Blood Agar, the difference between the slopes of the regression lines will be only slight if the same antimicrobial and the same method are used. There is a linear correlation between on a logarithmic scale the molecular weight of the antimicrobials contained in tablets or discs and, on a linear scale, the slope of the regression line pertaining to the particular drug.
PROPERTIES OF PURIFIED PHOSPHOLIPASE C FROM ACINETOBACTER CALCOACETICUS
Authors: Lehmann Vidar
Published: August 2010

Phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Acinetobacter calcoaceticus was purified 20‐fold by ultrafiltration and chromatography on DEAE‐Sephadex. The purified enzyme was markedly labile. Mg2+, deoxycholate and albumin enhanced the enzymatic activity against lecithin, while Ca2+, Zn2+ and ethylendiaminetetraacetate inhibited the activity. The temperature coefficient (Q10°C) was 1.7 and optimum pH 8.2–8.6. The Michaelis constant was found to be lower than 250 μM. At pH 8.3, lecithin, phosphatidylethanolamine, phosphatidylserine and sphingomyelin were attacked, while at pH 6.3 only lecithin and sphingomyelin were susceptible to hydrolysis.
Genetic relationship among several pig populations in East Asia analysed by blood groups and serum protein polymorphisrns
Authors: Tanaka K. , Oishi T. , Kurosawa Y. , Suzuki S.
Published: August 2010

The gene frequencies were calculated to investigate genetic variation apparent in blood group and serum protein systems in Asian native pigs. The results revealed that gene frequencies were generally similar in the nine pig populations, except in some systems. Differences of gene frequencies were recognized in HpY and Cpc detected on Taoyuan pigs of Taiwan and Ohmini pigs of Japan, respectively. TfC and AmC alleles were found in eight pig populations except Ohmini pigs.

The overall genetic distances were calculated by gene frequencies of 13 loci and it was observed that Taoyuan pigs are closer to Ohmini pigs than to Short‐ear pigs of Taiwan and other East Asian native pigs. However, the genetic distances between Asian native pigs and European or American breeds were larger than those among East Asian native pig populations.
Ultrastructural analysis of salivary gland pleomorphic adenoma, with particular reference to myoepithelial cells
Authors: PALMER R.M. , LUCAS R.B. , LANGDON J.D.
Published: August 2010

Previous ultrastructural studies of pleomorphic adenoma have presented conflicting results with regard to the role of myoepithelial cells in the histogenesis of this tumour. In the present study specimens of ten major salivary gland pleomorphic adenomas were examined ultrastructurally and a number of cell types identified. The material was subjected to quantification using the stereological method of point counting. The results showed a wide spectrum of differentiation within these tumours in which typical myoepithelial cells were rarely encountered even in situations where they are reported to occur in routine histological preparations. Cells with some myoepithelial features were more numerous but duct cells accounted for the majority of tumour cells. The ultrastructural findings correlated well with previously reported immunocytochemical data and further support certain ideas about salivary gland tumour histogenesis.
Laryngeal neuroendocrine tumour with features of a paraganglioma, intracytoplasmic lumina and acinar formation
Authors: SPAGNOLO D. V. , PARADINAS F. J.
Published: August 2010

A supraglottic laryngeal neuroendocrine tumour in a 71‐year‐old female is presented. In addition to the typical features of extra‐adrenal paragangliomas it showed unusual, numerous intracytoplasmic lumina and occasional true acini with accumulation of alcian blue and PAS positive secretory product in them which led originally to an erroneous diagnosis of metastatic adenocarcinoma. Ultrastructurally, the tumour was composed of light and dark chief cells containing varying numbers of dense‐core secretory granules. Intracytoplasmic lumina and true acini contained microvilli with glycocalyceal material and varying amounts of membranous and amorphous material, possibly secreted via small, smooth‐surfaced cytoplasmic vesicles but typical mucin granules were not seen. These features have not been previously described in laryngeal paragangliomas but are seen in endocrine tumours of other sites and have been used as an argument in favour of an endodermal rather than ectodermal origin for endocrine cells in those sites. Laryngeal paragangliomas are often malignant and the presence of spasmodic pain appears to be the most reliable indication of possible malignancy, histological criteria being as yet poorly defined.
Benign plexiform (multinodular) schwannoma: a rare tumour unassociated with neurofibromatosis
Authors: FLETCHER C.D.M. , DAVIES S.E.
Published: August 2010

In reviewing a large series of soft tissue tumours, seven cases of benign plexiform schwannoma have been retrieved. These were solitary lesions, not associated with von Recklinghausen's neurofibromatosis, which arose in the dermis or subcutaneous tissue, predominantly in young adults. None has recurred. While the schwannomatous nature of these rare lesions is readily appreciated, the frequent presence of nuclear pleomorphism and the plexiform growth pattern should not be regarded as having sinister prognostic significance.