bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular evolution of the Li/li chemical defence polymorphism in white clover (Trifolium repens L.)
Authors: OLSEN K. M. , SUTHERLAND B. L. , SMALL L. L.
Published: September 2007

White clover (Trifolium repens) is naturally polymorphic for cyanogenesis (hydrogen cyanide release following tissue damage). The ecological factors favouring cyanogenic and acyanogenic plants have been examined in numerous studies over the last half century, making this one of the best‐documented examples of an adaptive polymorphism in plants. White clover cyanogenesis is controlled by two, independently segregating Mendelian genes: Ac/ac controls the presence/absence of cyanogenic glucosides; and Li/li controls the presence/absence of their hydrolysing enzyme, linamarase. In this study, we examine the molecular evolution and population genetics of Li as it relates to the cyanogenesis polymorphism. We report here that Li exists as a single‐copy gene in plants possessing linamarase activity, and that the absence of enzyme activity in li/li plants is correlated with the absence of much or all of the gene from the white clover genome. Consistent with this finding, we confirm by reverse transcription–polymerase chain reaction that Li gene expression is absent in plants lacking enzyme activity. In a molecular population genetic analysis of Li and three unlinked genes using a worldwide sample of clover plants, we find an absence of nucleotide variation and statistically significant deviations from neutrality at Li; these findings are consistent with recent positive directional selection at this cyanogenesis locus.
Neurogastroenterology of tegaserod (HTF 919) in the submucosal division of the guinea‐pig and human enteric nervous system
Authors: Fang X. , Liu S. , Wang X‐y. , Gao N. , Hu H‐z. , Wang G‐d. , Cook C. H. , Needleman B. J. , Mikami D. J. , Xia Y. , Fei G‐j. , Hicks G. A. , Wood J. D.
Published: August 2007

Abstract  Actions of the 5‐HT4 serotonergic receptor partial agonist, tegaserod, were investigated on mucosal secretion in the guinea‐pig and human small intestine and on electrophysiological behaviour of secretomotor neurons in the guinea‐pig small intestinal submucosal plexus. Expression of 5‐HT4 receptor protein and immunohistochemical localization of the 5‐HT4 receptor in the submucosal plexus in relation to expression and localization of choline acetyltransferase and the vesicular acetylcholine (ACh) transporter were determined for the enteric nervous system of human and guinea‐pig small intestine. Immunoreactivity for the 5‐HT4 receptor was expressed as ring‐like fluorescence surrounding the perimeter of the neuronal cell bodies and co‐localized with the vesicular ACh transporter. Exposure of mucosal/submucosal preparations to tegaserod in Ussing chambers evoked increases in mucosal secretion reflected by stimulation of short‐circuit current. Stimulation of secretion had a relative high EC50 of 28.1 ± 1.3 μmol L−1, was resistant to neural blockade and appeared to be a direct action on the secretory epithelium. Tegaserod acted at presynaptic 5‐HT4 receptors to facilitate the release of ACh at nicotinic synapses on secretomotor neurons in the submucosal plexus. The 5‐HT2B receptor subtype was not involved in actions at nicotinic synapses or stimulation of secretion.
Birthweight distributions by gestational age: comparison of LMP‐based and ultrasound‐based estimates of gestational age using data from the Swedish Birth Registry
Authors: Haglund Bengt
Published: September 2007

Studies based on data from the US have reported that the birthweight distribution at gestational age 28–31 weeks is bimodal with a second peak occurring at approximately 3300 g, suggesting that there is misclassification of term infants. In these studies, gestational ages were estimated from the date of the last menstrual period (LMP), and it has been suggested that ultrasound‐based estimates of gestational age would eliminate the problem with bimodal birthweight distributions. Swedish data include both measures, thus offering an opportunity for comparison. All singleton births in Sweden from 1993 to 2002 with information on birthweight were included in the study (n = 917 901). Both LMP‐ and ultrasound‐based estimates of gestational age were available for 75.1% of the births. Two possible sources of misclassification were considered: measurement error, assuming that ultrasound‐based estimates are better, and data entry errors. An algorithm for assessment of data entry errors was developed; 67.4% of the births were left for the analyses of data ‘cleaned’ from data entry errors.

Based on the entire study population, the LMP‐based birthweight curves for lower‐gestational‐age preterm births were bimodal, with a second peak around 3500 g. The bimodal distribution was greatly attenuated when using ultrasound‐based gestational age categories, but did not disappear. After cleaning the data, the LMP‐based birthweight distributions for infants at gestational ages <32 weeks were no longer bimodal, and were very similar to the ultrasound‐based curves. In conclusion, data entry errors are more likely to cause the bimodality in the birthweight distribution among preterm infants than measurement errors in the LMP‐based gestational age estimate.
Postoperative intra‐abdominal adhesions: a personal view
Authors: Ellis H.
Published: September 2007

This paper reviews a near half century of interest and personal involvement in the topic of intra‐abdominal adhesions. During this time, much has been learned about the aetiology of this condition, which results from the presence of ischaemic or foreign material in the peritoneal cavity. This knowledge, in turn, has led to modifications in our operative practices. While for many years a rather neglected subject, recent studies have stressed the complications that may result from adhesions, in particular small bowel obstruction, and have documented the clinical burden of adhesions on the health services. For over a century, surgeons have investigated means of preventing or at least modifying the formation of adhesions. At first, these were carried out in a quite arbitrary manner, but in more recent times, there has been a more rational approach, based on our clearer knowledge of their aetiology.
Biology of the peritoneum in normal homeostasis and after surgical trauma
Authors: Van Der Wal J. B. C. , Jeekel J.
Published: September 2007

The peritoneum is a serous membrane, which has a protective function for the contents of the abdominal cavity. It maintains homeostasis by allowing exchange of molecules and production of peritoneal fluid, thus providing an environment in which intra‐abdominal organs can function properly. When traumatized, whether by surgery or due to inflammatory processes, a series of responses come into action to regenerate the injured part of the peritoneum. The inflammatory reaction causes influx of inflammatory cells but also activates resident mesothelial cells, ultimately leading to a fibrinous exudate. Depending on the severity of the trauma this exudate is transient due to fibrinolysis, or becomes more dense as a result of fibroblasts persisting, leading to fibrinous adhesions. A pivotal role is taken by the enzyme plasmin and its promotors and inhibitors; it is mainly the tissue‐type plasminogen activator/plasminogen activator inhibitor ratio which determines the rate of fibrinolysis and therefore the rate of adhesion formation. The rate of injury determines the rate and extent of the inflammatory response to that injury; in its turn the inflammatory reaction determines the extent of adhesion formation. One should realize this when performing intra‐abdominal surgery, which is in fact operating inside the peritoneal organ.
BAYESIAN BETA REGRESSION: APPLICATIONS TO HOUSEHOLD EXPENDITURE DATA AND GENETIC DISTANCE BETWEEN FOOT‐AND‐MOUTH DISEASE VIRUSES
Authors: Branscum Adam J. , Johnson Wesley O. , Thurmond Mark C.
Published: August 2007

There is considerable interest in understanding how factors such as time and geographic distance between isolates might influence the evolutionary direction of foot‐and‐mouth disease. Genetic differences between viruses can be measured as the proportion of nucleotides that differ for a given sequence or gene. We present a Bayesian hierarchical regression model for the statistical analysis of continuous data with sample space restricted to the interval (0, 1). The data are modelled using beta distributions with means that depend on covariates through a link function. We discuss methodology for: (i) the incorporation of informative prior information into an analysis; (ii) fitting the model using Markov chain Monte Carlo sampling; (iii) model selection using Bayes factors; and (iv) semiparametric beta regression using penalized splines. The model was applied to two different datasets.
Measuring Unemployment in Developing Countries: The Case of Indonesia
Authors: Suryadarma Daniel , Suryahadi Asep , Sumarto Sudarno
Published: September 2007

Abstract.  Measuring unemployment in developing countries is not straightforward due to the presence of a large number of discouraged workers. Including them into the labor force is sometimes appropriate in order to reflect the true state of unemployment. However, the decision must be based on careful research. This study provides a case study of Indonesia, whose decision to include discouraged workers into its labor force resulted in an artificially high unemployment rates and disguised the actual post‐crisis decline in unemployment in Indonesia. The discouraged workers can be classified based on their willingness to work. If Indonesia still wants to include discouraged workers into the labor force, only those willing to work should be included.
PhD Graduates with Post‐doctoral Qualification in the Private Sector: Does It Pay Off?
Authors: Recotillet Isabelle
Published: September 2007

Abstract.  In this paper, we address the question of the early careers of French PhD graduates in science and engineering sciences in 1996. Post‐doctoral training was initially developed for PhD graduates wishing to embark on a career in the public sector. However, a large proportion of post‐doctorate graduates turn to the private sector, and in particular to occupations that do not involve research. The question we raise is that of the wage premium on post‐doctoral training. To control for selection bias arising in the case where unobservable elements are correlated between participation and wages, we first estimate a treatment effect model. The main finding is that when selection bias is not controlled for, post‐doctoral participation increases earnings; however, when selection bias is controlled for, the participation in a post‐doctoral programme has no positive effect. With regards to this finding we show that post‐doctoral programmes play much more the role of a signal in the first stage of a career. This finding is also reinforced when we use a bivariate selection rule to control for the endogenous nature of having been recruited in the private sector.
The prevalence of intellectual disability in a major UK prison
Authors: Hayes Susan , Shackell Phil , Mottram Pat , Lancaster Rachel
Published: September 2007

Accessible summary

This research aimed to find out how many people in a big English prison had a learning disability.

One‐tenth of the people in the prison were chosen to take part. There were 140 prisoners involved in the study.

The prisoners were asked questions about their lives and took tests to see if they had a learning disability.

The researchers found there were more people with learning disabilities in prison than people had thought before.

People in prison who have a learning disability need extra help.

People who have a learning disability also need special help when they leave prison and go back to live in the community.

Over‐representation of people with learning disability in prisons has been demonstrated in many Western jurisdictions. This was the first comprehensive research in a UK prison. The research used a random 10% sample of a prison population (n = 140). A semi‐structured interview, the Wechsler Adult Intelligence Scale – III (UK version) and the Vineland Adaptive Behavior Scales (VABS) Interview Edition were administered. On the Wechsler Adult Intelligence Scale – III, UK version (WAIS‐III (UK)), 7.1% of participants achieved standard scores below 70 and a further 23.6% were in the 70–79 (borderline) range. The VABS results indicated that 10.1% had standard scores below 70 and a further 33.3% were in the borderline range. The results indicate that the prevalence of intellectual (or learning) disability as measured on either or both of the WAIS‐III (UK) or the Vineland Adaptive Behavior Scales is higher than previous research in the UK has indicated. The results have implications for provision of services in prison and post‐release.
ULTRAPLANKTON BIOMASS, PRODUCTIVITY AND EFFICIENCY IN LAC MATAMEC, A PRECAMBRIAN SHIELD LAKE1,2
Authors: Ross P. E. , Duthie H. C.
Published: August 2007

In extremely oligotrophic Lac Matamec (Quebec, Canada) the ultraplankton (<15 μm) represented 47% of total phytoplankton biomass but accounted for 71% of the primary production and was 2.5 times more photosynthetically efficient than larger phytoplankton. Cell surface area was a good predictor of efficiency, while cell numbers and bio‐mass were not. High surface:volume ratios may explain the high efficiency of the ultraplankton.
CHARACTERISTICS OF SEXUAL AND ASEXUAL RESTING CYST (STATOSPORE) FORMATION IN DINOBRYON CYLINDRICUM IMHOF (CHRYSOPHYTA)1
Authors: Sandgren Craig D.
Published: August 2007

The reproductive significance of siliceous cysts (statospores) produced by the common vernal chrysophyte Dinobryon cylindricum Imhof has been investigated under defined culture conditions. Three types of statospores have thus far been induced in culture: 1) uninucleate, asexual; 2) binucleate, asexual (potentially autogamic); 3) binucleate, sexual (zygotic). The production of each type of cyst responds differently to an array of nutrient deficiencies (P, N, vitamins, micrometals). An individual clone may be capable of participating in the production of all or only a subset of these types of resting cysts. All D. cylindricum statospores are morphologically identical regardless of their reproductive significance. Sexual reproduction leading to zygotic statospore formation is anisogamous, heterothallic, and involves a gametogenic hormone (erogen) that is apparently continuously released from female clones. Only a single bipolar mating group is documented here and clonal compatibility varies considerably within the mating group.

The dynamics of encystment for each type of statospore has been determined relative to the growth of the vegetative cell population. Statospores may be produced either during the exponential phase (intrinsic encystment) or stationary phase (extrinsic encystment) of culture growth depending on the clones involved. The effect of both asexual and sexual resting cyst production on the net growth rate and dynamics of natural chrysophyte populations is discussed. Statospores appear to represent a more flexible reproductive strategy than the resistant zygospores produced by the other common groups of planktonic microalgae.
ULTRASTRUCTURE OF ACTIVE AND RESTING COLONIES OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE)1
Authors: Wolf Fred R. , Cox Elenor R.
Published: August 2007

The ultrastructure of resting state colonies of Botryococcus braunii Kützing from two localities is compared to active state colonies maintained in the laboratory. Qualitative hydrocarbon analyses confirmed the physiological status of each sample according to the precedent in the literature; resting state colonies contained botryococcenes, while active state colonies contained a predominance of straight‐chain olefins. The ultrastructure of resting and active state colonies is fundamentally similar. The chloroplast of resting state cells contains fewer thylakoids and larger relative numbers of plastoglobuli than the chloroplast of active state cells maintained under favorable growth conditions. Previously undescribed phenomena include the cytochemical demonstration of polyphosphate bodies microbody‐like organelles and ER‐ribosomal‐mitochondrial complexes.

Attempts to elicit the transition of active to resting state colonies utilizing different light intensities and/or nitrogen deficient media were unsuccessful. Instead, these experiments induced the formation of yellow or whitish‐brown senescent colonies which always contained a predominance of olefins. Senescent cells contain reduced, peripherally displaced organelles. Most of the cytoplasm is occupied by vacuoles and lipid (probably hydrocarbon) inclusions. Morphologically identifiable polyphosphate bodies are usually small or absent. Observations pertinent to the mechanism of hydrocarbon secretion were in basic agreement with previously published information. The outer cell wall, or trilamellar structure (TLS), was recently as the primary site of hydrocarbon accumulation and production. The role of the TLS in hydrocarbon biosynthesis, however, should be cautiously regarded without additional evidence.
THE DISTRIBUTION OF EDAPHIC DIATOMS ALONG ENVIRONMENTAL GRADIENTS OF A LOUISIANA SALT MARSH1
Authors: Cook Lawrence L. , Whipple Stephen A.
Published: August 2007

Edaphic (sediment‐associated) diatoms were collected from five sites along a gradient from slightly brackish to saline marsh on 30 November 1977 and 29 April 1978. Several environmental factors change along this gradient in addition to salinity, including tidal flushing and percent organic content of the soil. A total of 112 taxa were identified, with Amphora exigua Greg., Navicula phyllepta Kütz., N. salinarum Grun., and N. tripunctata (Müll.) Bory being among the five most abundant taxa on both sampling dates. The taxonomic composition of the diatom flora was very similar to those observed for other salt marshes located along the Gulf and Atlantic coasts. Diatom taxa were generally euryhaline and distributed continuously along the gradient from brackish to saline marsh. Species diversity (H1) and the number of taxa in a sample (S) were also similar to those reported for other North American salt marshes. The number of taxa in a sample was higher in the saline than in the brackish area on both sampling dates while species diversity was greater in the saline area only in April.
NITRATE AND PHOSPHATE UPTAKE INTERACTIONS IN A MARINE PRYMNESIOPHYTE1
Authors: Terry Kenneth L.
Published: August 2007

The short‐ and long‐term uptake of nitrate and phosphate ions, and their interactions, were studied as functions of the preconditioning of Pavlova lutheri (Droop) Green. Populations were preconditioned in continuous culture at a variety of growth rates and N:P supply ratios. The maximum uptake rates cell−1 for nitrate and phosphate were of similar magnitudes, in spite of the forty‐fold smaller requirement for phosphorus. Short‐term phosphate uptake was independent of the nitrate concentration, but the short‐term nitrate uptake rate was reduced in the presence of phosphate. The severity of inhibition of nitrate uptake by phosphate was positively correlated with the preconditioning N:P supply ratio and the preconditioning growth rate. In response to large additions of nutrients, P. lutheri was able to increase its phosphorus content sixty‐fold, but was only able to take up enough nitrate to double its nitrogen content. The high rate of phosphate uptake relative to its requirement, the inhibition of nitrate uptake by phosphate, and the large capacity for phosphorus storage relative to its requirement, all of which were observed even under N limitation, may imply that even where nitrogen is limiting there can be interspecific competition for available phosphate.
COLONIZATION AND SUCCESSION OF ALGAE AND SOIL‐ALGAL INTERACTIONS ASSOCIATED WITH DISTURBED AREAS1
Authors: Starks Thomas L. , Shubert L. Elliot
Published: August 2007

The number and abundance of algal species were not significantly different between non‐topsoiled areas and top‐soiled areas. Successional trends were evident at both sites, since the number of species and their abundance increased over time. Soil‐algal interactions were determined by regression analysis. A conceptual model was developed that illustrated the influence of soil chemical properties on algal abundance. Important factors affecting the soil algae were sodium, calcium, potassium, magnesium and certain trace elements. The possible influence of these factors on algal growth is discussed.
AUTECOLOGY OF AN ULTRAPLANKTONIC SHADE ALGA IN LAKE TAHOE2
Authors: Vincent Warwick F.
Published: August 2007

The ultraplanktonic green alga Monoraphidium contortum Korm. in Lake Tahoe (California‐Nevada) demonstrated several ecological and physiological attributes of a genetically adapted shade species. Monoraphidium contortum achieved maximum biomass during deep mixing in winter when light availability was at a minimum. During stratification it was found in maximum abundance in the deep euphotic region, 100–150 m. This species was also distributed through the deep aphotic zone where, despite prolonged darkness, it remained capable of immediate photosynthesis when re‐exposed to light levels in the euphotic zone. The spirally twisted cells were grazed by two calanoid copepods in Lake Tahoe as readily as much larger‐celled phytoplankton species of less complex morphology. Slow growth rates in combination with high susceptibility to copepod grazing may effectively exclude M. contortum from the upper 75 m, where it was rarely recorded. In culture it showed a marked incapacity to adjust to ‘sun’ conditions but was well adapted to low light regimes. Under a wide range of irradiances, photochemical capacity, photosynthetic capacity and growth rates were low, but cellular pigment content remained high. The ratio of Pmax to respiration was at the lower end of the range for shade plants. Genetically distinct sun and shade populations of phytoplankton may play a determining role in major shifts of community structure over depth and time in Lake Tahoe.
ADAPTATION OF CERATIUM FURCA AND GONYAULAX POLYEDRA (DINOPHYCEACE) TO DIFFERENT TEMPERATURES AND IRRADIANCES: GROWTH RATES AND CELL VOLUMES1
Authors: Meeson Blanche W. , Sweeney Beatrice M.
Published: August 2007

Growth rates and cell volumes of Ceratium furca Ehrenberg and Gonyaulax polyedra Stein were determined during the log phase of growth in cultures which had been extensively adapted to one of three temperatures and five irradiances. At each temperature, curves for the growth rate vs. irradiance for both species had light‐limited and light‐saturated regions. Three properties of these curves characterized the response of each species to temperature: the light‐saturated growth rate, the irradiance at which growth became light‐saturated and the compensation irradiance for growth. For both species, the first two properties generally decreased with declining growth temperature, while the compensation irradiance declined for Ceratium but had a V‐shaped response pattern for Gonyaulax. The light‐saturated growth rates were generally higher for Ceratium than for Gonyaulax, while the irradiance at which growth became saturated and the compensation irradiance were lower for Ceratium. The changes in cell volume associated with the irradiance and temperature of growth were very different for Ceratium and Gonyaulax. The cell size of Gonyaulax increased as irradiance and temperature decreased, while cell volumes of Ceratium did not change with temperature but were smallest at the highest and lowest growth irradiances. In general, the growth rate patterns were similar for Ceratium and Gonyaulax, while those for cell size were different. The maximum growth rate, the irradiance at which growth became saturated, the compensation irradiance, and the cell volume all showed that Ceratium grew at the same rate or faster than Gonyaulax over the entire range of irradiances and temperatures examined.
FACTORS CONTROLLING THE INTERTIDAL ZONATION OF IRIDAEA FLACCIDA (RHODOPHYTA)1
Authors: Foster Michael S.
Published: August 2007

Field experiments were used to examine the effects of biological interactions on the abundance of Iridaea flaccida (S. & G.) Silva within and below its normal range in the intertidal zone of central California. A combination of competitor removal, grazer exclusion and transplant manipulations showed that within the I. flaccida zone, this alga can be the first macroscopic plant to become reestablished after clearing and that this can occur in less than two months. Grazing by molluscs within this zone retards, but does not prevent, re‐establishment. Although absent prior to the experiments, both I. flaccida and I. cordata (Turn.) Bory settled, grew rapidly and reproduced in cleared areas below the I. flaccida zone, regardless of the presence of grazers. These plants did not establish themselves if entire thalli or holdfasts of other algae normally occupying the lower zone were present. The results support the few other in situ experimental investigations of algal zonation by showing that, when bounded by other plants, the lower limits of intertidal algae are directly determined by competition. They also suggest that I. flaccida and I. cordata may be conspecific.
RESPONSE OF PROROCENTRUM MARIAE‐LEBOURIAE (DINOPHYCEAE) TO LIGHT OF DIFFERENT SPECTRAL QUALITIES AND IRRADIANCES: GROWTH AND PIGMENTATION1
Authors: Faust Maria A. , Sager John C. , Meeson Blanche W.
Published: August 2007

Growth and pigment concentrations of the, estuarine dinoflagellate, Prorocentrum mariae‐lebouriae (Parke and Ballantine) comb. nov., were measured in cultures grown in white, blue, green and red radiation at three different irradiances. White irradiances (400–800 nm) were 13.4, 4.0 and 1.8 W · m−2 with photon flux densities of 58.7 ± 3.5, 17.4 ± 0.6 and 7.8 ± 0.3 μM quanta · m−2· s−1, respectively. All other spectral qualities had the same photon flux densities. Concentrations of chlorophyll a and chlorophyll c were inversely related to irradiance. A decrease of 7‐ to 8‐fold in photon flux density resulted in a 2‐fold increase in chlorophyll a and c and a 1.6‐ to 2.4‐fold increase in both peridinin and total carotenoid concentrations. Cells grown in green light contained 22 to 32% more peridinin per cell and exhibited 10 to 16% higher peridinin to chlorophyll a ratios than cells grown in white light. Growth decreased as a function of irradiance in white, green and red light grown cells but was the same at all blue light irradiances. Maximum growth rates occurred at 8 μM quanta · m−2· s−1 in blue light, while in red and white light maximum growth rates occurred at considerably higher photon flux densities (24 to 32 μM quanta · m−2· s−1). The fastest growth rates occurred in blue and red radiation. White radiation producing maximum growth was only as effective as red and blue light when the photon flux density in either the red or blue portion of the white light spectrum was equivalent to that of a red or of blue light treatment which produced maximum growth rates. These differences in growth and pigmentation indicate that P. mariae‐lebouriae responds to the spectral quality under which it is grown.
THE NORMAL AND INDUCED OCCURRENCE OF CYANOPHYCIN INCLUSION BODIES IN SEVERAL BLUE‐GREEN ALGAE1
Authors: Lawry Nelson H. , Simon Robert D.
Published: August 2007

Multi‐L‐arginyl‐poly(L‐aspartic acid) [arg‐poly(asp)], the polypeptide component of the cyanophycin inclusion body, is found in cells of many blue‐green algae. Formation of this material can be induced by a variety of treatments including the addition of excess nitrogen‐containing compounds, the addition of specific inhibitors of macromolecular synthesis, and the exclusion of sulfur or phosphorus. Knowledge of the conditions that induce the synthesis of this polypeptide has made possible an ultrastructural survey to determine the presence and cellular location of cyanophycin bodies in a variety of cyanobacteria. Data presented show that certain strains of the unicellular genus Synechococcus Nägeli do not contain arg‐poly(asp) under environmental conditions that markedly increase the level of such material in other cyanobacteria. In addition many strains show spatial localization of the cyanophycin bodies under normal growth conditions, and moreover the normal pattern is retained even when massive synthesis of arg‐poly(asp) is induced. Finally there is no evidence that these inclusion bodies occur in certain beggiatoan gliding bacteria.
ACROSYMPHYTON FIRMUM SP. NOV. (RHODOPHYTA, CRYPTONEMIALES), A NEW SUBTIDAL RED ALGA FROM NEW ZEALAND; DEVELOPMENTAL MORPHOLOGY AND DISTRIBUTION OF THE GAMETOPHYTE1
Authors: Hawkes Michael W.
Published: August 2007

Acrosymphyton firmum sp. nov., is described from the northeastern coast of North 1., New Zealand. Gametophytes are spring–summer annuals which grow subtidally on cobbles. Thalli are uniaxial; each axial cell bears a whorl of four indeterminate and one determinate branchlets. Indeterminate branchlets are alternately arranged giving the thallus a distichous and feather‐like appearance. Numerous corticating rhizoidal filaments are produced from the periaxial and lower whorl branchlet cells. These rhizoids entwine and obscure the main axis as the thallus develops until in the mature plant the axes have a firm consistency and lubricous texture. The carpogonial branch bearing short lateral filaments and auxiliary cell branch with terminal auxiliary cell place this new species in the genus Acrosymphyton Sjöstedt. Of the three described species in the genus, A. firmum is most similar to A. taylori. This is the first report of the genus Acrosymphyton and the only confirmed report of the family Dumontiaceae in New Zealand waters.
PHYSIOLOGY OF SEA ICE DIATOMS. I. RESPONSE OF THREE POLAR DIATOMS TO A SIMULATED SUMMER‐WINTER TRANSITION1
Authors: Palmisano Anna C. , Sullivan Cornelius W.
Published: August 2007

Three axenic polar sea ice diatom cultures were subjected to a 30 day simulated summer‐winter transition in which light and temperature were decreased and salinity was increased to mimic seasonal changes previously reported for ice‐covered polar seas. The diatoms responded to these changes by a reduction in cellular metabolism as indicated by: 1) A decline in growth rate and photosynthetic rate; 2) a decrease in cellular ATP; and 3) the storage and subsequent utilization of endogenous carbon reserves. In addition, heterotrophic potential of the three clones increased by as much as 60‐fold. In some cases, the decrease in light intensity characteristic of the onset of polar winter was alone sufficient to trigger these physiological changes.
ZINC ADSORPTION AND TRANSPORT BYCHLAMYDOMONAS VARUIABILISANDSCENEDESMUS SUBSPICATUS(CHLOROPHYCEAE) GROWN IN SEMICONTINUOUS CULTURE1
Authors: Bates Stephen S. , Tessier André , Campbell Peter G. C. , Buffle Jacques
Published: August 2007

The amount of zinc adsorbed onto the cell surface of the unicellular green algaeScenedesmus subspicatusHodat andChlamydomonas variabilisDangeard was operationally defined by extraction with EDTA; it was a function of the concentration of free ionic zinc remaining in the growth medium, rather than that of the total (free plus complexed) zinc concentration, and could be described by Langmuir isotherms. Conditional adsorption equilibrium constants for zinc were 0.123 and 0.039 L ·μmol−1forS. subspicatusandC. variabilis, respectively. A portion of the zinc adsorbed ontoC. variabiliswas released into solution after 1 h of contact with the metal, providing a possible tolerance mechanism for this alga; the division rate ofC. variabiliswas not altered by up to 12 μmol Zn2+· L−1, although the cell yield obtained during the stationary phase was significantly decreased. The amount of transported or cellular zinc, for both algal species, was operationally defined as the zinc remaining with the cell after EDTA‐extraction; it was a linear function of the free ionic zinc concentration remaining in solution, suggesting that the zinc transported into the cell was not derived from the total adsorbed fraction, although the latter may contain some zinc originating from specific sites leading to zinc transport.
ACCUMULATION OF β‐CAROTENE IN HALOTOLERANT ALGE: PURIFICATION AND CHARACTERIZATION OF β‐CAROTENE‐RICH GLOBULES FROM DUNALIELLA BARDAWIL (CHLOROPHYCEAE)1
Authors: Ben‐Amotz Ami , Katz Adriana , Avron Mordhay
Published: August 2007

Dunaliella bardawil Ben‐Amotz & Avron, but not most other Dunaliella species, has a unique property of being able to accumulate, in addition to glycerol, large amounts of β‐carotene when cultivated under appropriate conditions. These include high light intensity, a high sodium chloride concentration, nitrate deficiency and extreme temperatures. Under conditions of maximal carotene accumulation D. bardawil contains at least 8% of its dry weight as β‐carotene while D. salina grown under similar conditions contains only about 0.3%. Electron micrographs of D. bardawil grown under conditions of high β‐carotene accumulation show many β‐carotene containing globules located in the interthylakoid spaces of the chloroplast. The same algae grown under conditions where β‐carotene does not accumulate, contain few to no β‐carotene globules. The β‐carotene‐rich globules were released from the algae into an aqueous medium by a two‐stage osmotic shock technique and further purified by centrifugal ion on 10% sucrose. The isolated purified globules were shown by electron microscopy to be free of significant contamination and composed of membrane‐free osmiophilic droplets with an average diameter of 150 nm. Reversed phase high performance liquid chromatography of a total pigment extract of the cells revealed the presence of β‐carotene as the major pigment, together with chlorophylls a and b, α‐carotene and the xanthophylls lutein, neoxauthin and zeaxanthin. β‐Carotene accounted for essentially all the pigment in the purified globules. Analysis of the algal and globule β‐carotene fractions by HPLC showed that the β‐carotene was composed of approximately equal amounts of all‐trans β‐carotene and of its 9‐cis isomer. Intact D. bardawil cells contained on a dry weight basis about 30% glycerol, 30% protein, 18% lipid, 11% carbohydrate, 9%β‐carotene and 1% chlorophyll. The β‐carotene globules were composed of practically only neutral lipids, more than half of which was β‐carotene. It is suggested that the β‐carotene globules may serve to protect D. bardawil against injury by the high intensity irradiation to which this alga is usually exposed in nature.
CONSPICUOUS ALGAL COLONIZATION OF THE ASH FROM MOUNT ST. HELENS1
Authors: Rayburn William R. , Mack Richard N. , Metting Blaine
Published: August 2007

Conspicuous growth of green and yellow‐green algae developed in arid steppe communities in eastern Washington on the silt‐sized ash from the 18 May 1980 eruption of Mount St. Helens. In a veneer on the ash, cell numbers per gram dry ash of these aerial immigrants equaled or exceeded the highest reported values for terrestrial chlorophytes (108 cells · g−1 dry soil). Such pronounced growth was restricted largely to three microsites (under the canopy of Artemisia tridentata, along the runways of the vole, Microtus montanus, and surrounding emergent agarics), apparently in response to water‐holding properties of the ash, localized nutrient input and possible reduction of predation by nematodes. Highest algal counts were in Microtus runways where daily water and urea‐N input per adult animal may be 8 mL and 23 mg, respectively. Cyanophytes, commonly considered early colonizers of volcanic ash, were extremely rare. The role of blue‐green algae in succession on volcanic materials may be more restricted geographically than previously recognized.
ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). I. ZOOSPORES1
Authors: Henry Eric C. , Cole Kathleen M.
Published: August 2007

Zoospores of 17 species in 14 genera of Laminariales, collected in the northeast Pacific Ocean, were studied by electron microscopy. These zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and any associated swelling at the base of the shorter, posterior flagellum. Spores of all species examined possess a distal whiplash portion on the longer, mastigoneme‐bearing anterior flagellum. This appendage may sometimes be as long as the mastigoneme‐bearing portion of the flagellum, but it is only seldom preserved in the preparations for electron microscopy. A microtubular cytoskeleton is probably responsible for maintaining the shape of the spore. It consists of a short band of about 10 microtubules between the two basal bodies, scattered tubules converging at the anterior of the spore, a band of 7–9 tubules directed anteriorly from the anterior basal body, and a band directed posteriorly from the posterior basal body. These anterior and posterior bands may form one continuous band looping around the periphery of the spore. Variation with possible taxonomic significance was found in the ultrastructure of vesicles which apparently contain adhesive material, and which are extruded through the plasmalemma when the zoospores settle.
ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). II. SPERM1
Authors: Henry Eric C. , Cole Kathleen M.
Published: August 2007

The ultrastructure of sperm from 13 species in 11 genera of Laminariales collected in the northeast Pacific Ocean is unique in the brown algae. The sperm are elongate, and possess a nucleus, several mitochondria and two or three chloroplasts, but no eyespot. The anterior flagellum bears mastigonemes on the proximal half of its length; a distal “whiplash” portion lacks mastigonemes and is an extension of only the two central singlet microtubules of the axoneme. A peculiar feature of these sperm is the posterior flagellum, which is longer than the anterior flagellum and tapers distally as the doublet microtubules become singlets and decrease in number. This feature contrasts with the laminarialean zoospore, which possesses a short posterior flagellum with the usual “9 + 2” axoneme. The structure of these sperm differs from that reported for Chorda, the sperm of which resembles a primitive brown algal zoospore. The facts support the concept that Chorda is the most primitive member of the Laminariales.
Photopheresis in pediatric graft‐versus‐host disease after allogeneic marrow transplantation: clinical practice guidelines based on field experience and review of the literature
Authors: Kanold Justyna , Merlin Etienne , Halle Pascale , Paillard Catherine , Marabelle Aurelien , Rapatel Chantal , Evrard Bertrand , Berger Claire , Stephan Jean‐Louis , Galambrun Claire , Piguet Christophe , D'Incan Michel , Bordigoni Pierre , Deméocq François
Published: September 2007

BACKGROUND: Extracorporeal photochemotherapy (ECP) gives positive results in the management of graft‐versus‐host disease (GVHD), but in children, specific difficulties can outweigh this benefit. These difficulties must be taken into consideration when establishing a standardized reproducible procedure for implementation under a quality management plan.

STUDY DESIGN AND METHODS: Twenty‐seven children underwent ECP for severe acute GVHD (aGVHD) or chronic GVHD (cGVHD) after allogeneic marrow transplantation. Data were collected prospectively, with particular emphasis placed on technical, biologic, immunologic, clinical, and long‐term follow‐up issues.

RESULTS: The 27 children underwent a total of 750 sessions. Mononuclear cells were collected on a commercially available apheresis system (COBE Spectra, Gambro BCT). Overall survival was 73 percent, and ECP led to significant improvement in 21 of the 27 patients (11 with complete response and 10 with partial response, i.e., >50% of organ involvement). Tolerance was good overall, the main limiting factors being vascular access and the psychological impact of repeated apheresis procedures. Children weighing less than 25 kg were not more susceptible to side effects.

CONCLUSION: A specifically pediatric‐dedicated and ‐experienced team faces only limited difficulties when treating children with GVHD by ECP. Overall, ECP is efficient and well tolerated. Our experience was therefore pooled together with available pediatric data to establish clinical practice guidelines. These guidelines consider ECP as a first‐line therapy in Grade IV aGVHD (in association with conventional pharmacologic approaches) and limited cGVHD and as a second‐line therapy in steroid‐resistant Grades II to III aGVHD and extensive cGVHD.
Monocyte enrichment from leukapheresis products by using the Elutra cell separator
Authors: Kim Sinyoung , Kim Hyun Ok , Baek Eun‐Jung , Choi Youjeong , Kim Han‐Soo , Lee Min‐Geul
Published: September 2007

BACKGROUND: Dendritic cells (DCs), used in clinical trials for cancer immunotherapy, require processing on an expanded scale to conform to current good manufacturing practice guidelines. This study evaluated a large‐scale monocyte enrichment procedure with a commercially available cell separator (Elutra, Gambro BCT) and analyzed the capacity of enriched monocytes to differentiate into DCs.

STUDY DESIGN AND METHODS: Mononuclear cells were collected in two patients with malignant melanoma and seven healthy donors by leukapheresis. Continuous‐counterflow elutriation with the Elutra was performed to enrich and purify monocytes from leukapheresis products. Purity and recovery of enriched monocytes were analyzed by flow cytometry. DCs were generated from the elutriated monocytes and characterized by phenotypic surface marker and stimulatory capacity in an allogeneic mixed lymphocyte reaction.

RESULTS: In the leukapheresis products, the total MNC count was 7.3 × 109 ± 0.7 × 109 and the mean percentage of CD14+ monocytes was 16.5 ± 3.8 percent, which increased to 68.9 ± 7.4 percent after elutriation with the Elutra. The mean monocyte recovery was 94.3 percent. Elutriated monocytes were successfully cultured into phenotypically and functionally mature DCs.

CONCLUSION: These results indicate that the Elutra cell separator allows for fast and easy enrichment of monocytes within a closed system. Furthermore, these monocytes can be differentiated into functionally mature DCs. Compared to plastic adherence and immunomagnetic selection methods, the elutriation procedure is inexpensive, efficient, and very effective.
In vitro assessment of recombinant, mutant immunoglobulin G anti‐D devoid of hemolytic activity for treatment of ongoing hemolytic disease of the fetus and newborn
Authors: Nielsen Leif K. , Green Trine H. , Sandlie Inger , Michaelsen Terje E. , Dziegiel Morten H.
Published: September 2007

BACKGROUND: A specific treatment for ongoing hemolytic disease of the fetus and newborn (HDFN) due to anti‐D would be very attractive. One approach could be administration to the mother of nonhemolytic anti‐D, which by crossing the placenta can block the binding of hemolytic maternal anti‐D.

STUDY DESIGN AND METHODS: Two anti‐D immunoglobulin G3 (IgG3) heavy‐chain mutants were expressed in Chinese hamster ovary cells. To investigate whether these anti‐D IgG3 mutants could inhibit the red blood cell–destructive activity of recombinant human (rHu)IgG1 with identical antigen‐binding region as well as polyclonal anti‐D having multiple D epitope specificities, two assays were used, antibody‐dependent cell‐mediated cytotoxicity (ADCC) and a chemiluminescence (CL)‐based method for detection of respiratory burst in peripheral blood monocytes.

RESULTS: The two IgG3 anti‐D heavy‐chain mutants inhibited the ADCC and CL responses mediated by a rHuIgG1 anti‐D with identical antigen‐binding region as the mutant antibodies, as well as the destructive activity mediated by a polyclonal anti‐D.

CONCLUSION: The use of nonhemolytic anti‐D may be an effective countermeasure against hemolysis in HDFN due to anti‐D.
Deal Size, Bid Premium, and Gains in Bank Mergers: The Impact of Managerial Motivations
Authors: Gupta Atul , Misra Lalatendu
Published: September 2007

Do mergers with greater target relative to acquirer size create more value than mergers with smaller relative sized targets? Do larger bid amounts represent wealth transfers from acquirers or do they signal greater expected merger gains? We hypothesize that the relations among aggregate merger gains, relative size, and bid premiums are asymmetric across mergers made by value‐enhancing versus value‐reducing managers. We use a large sample of bank mergers to test these predictions and find that the value response to different explanatory variables is asymmetric. Our findings provide new insights into how the market values merger bids.
Trading Volume and Market Volatility: Developed versus Emerging Stock Markets
Authors: Girard Eric , Biswas Rita
Published: September 2007

We investigate the relation between volatility and volume in 22 developed markets and 27 emerging markets. Compared to developed markets, emerging markets show a greater response to large information shocks and exhibit greater sensitivity to unexpected volume. We find a negative relation between expected volume and volatility in several emerging markets, which can be attributed to the relative inefficiency in those markets. Previous research reports that the persistence in volatility is not eliminated when lagged or contemporaneous trading volume is considered. Our findings show that, when volume is decomposed into expected and unexpected components, volatility persistence decreases.
Determining the Effective Sample Size of a Parametric Prior
Authors: Morita Satoshi , Thall Peter F. , Müller Peter
Published: September 2007

Summary We present a definition for the effective sample size of a parametric prior distribution in a Bayesian model, and propose methods for computing the effective sample size in a variety of settings. Our approach first constructs a prior chosen to be vague in a suitable sense, and updates this prior to obtain a sequence of posteriors corresponding to each of a range of sample sizes. We then compute a distance between each posterior and the parametric prior, defined in terms of the curvature of the logarithm of each distribution, and the posterior minimizing the distance defines the effective sample size of the prior. For cases where the distance cannot be computed analytically, we provide a numerical approximation based on Monte Carlo simulation. We provide general guidelines for application, illustrate the method in several standard cases where the answer seems obvious, and then apply it to some nonstandard settings.
Novel Composites Constituted from Hafnia and a Polymer‐Derived Ceramic as an Interface: Phase for Severe Ultrahigh Temperature Applications
Authors: Brahmandam Sudhir , Raj Rishi
Published: September 2007

HfO2–SiCN (polymer‐derived silicon carbonitride) composites were prepared by two methods. In one case, equal volume fractions of HfO2 and pyrolyzed powders of SiCN were co‐sintered, to create a particulate composite. The second type, called interface composites, were prepared by coating HfO2 particles with a thin film of the polymer precursor, followed by sintering so that densification and pyrolysis of the precursor occurred simultaneously; this process results in a ∼5‐nm‐thick grain boundary film constituted from Hf, O, and Si. The fracture properties and environmental degradation (in a humid environment at a velocity of 17.6–35.0 cm/s at 1300°C) of these two composites were measured. They were compared with the properties of a reference material made by sintering HfO2 powders without any additives, under similar conditions (1450°C for 2 h in air). The interface composite yielded the highest sintered density (0.90), exhibited negligible grain growth, and possessed the highest fracture strength (110 MPa). The strength remained immune to hydrothermal oxidation for several hundred hours. In contrast, the particulate composite suffered severe degradation in strength after hydrothermal exposure. The interface composites, with their highly refractory grain boundaries, represent a new class of ceramics for structural applications in harsh environments and at ultrahigh temperatures.