bluuebunny/crossref_metadata_2025 huggingface dataset:
Apheresis Therapy for Living‐Donor Liver Transplantation
Authors: Kozaki Koichi , Kasahara Mureo , Oike Fumitaka , Ogawa Kohei , Fujimoto Yasuhiro , Ogura Yasuhiro , Ueda Mikiko , Kaihara Satoshi , Fukatsu Atushi , Tanaka Koichi
Published: March 2003

Abstract: Liver transplantation is a fundamental treatment for patients with end‐stage hepatic failure. In order to perform living‐donor liver transplantations under safer conditions, apheresis plays a major role in Japan due to the prevalence of living‐donor liver transplantation wherein later retransplantation is difficult. In our department, the roles of apheresis in liver transplantation are as follows: as bridge therapy to liver transplantation (n = 45); as a supplement to the graft liver until the recovery of hepatic function (n = 77); as treatment for multiple organ failure including posttransplantation renal failure (n = 15); and as a means with which to reduce antibody titers for antibodies such as anti‐A or anti‐B in persons with ABO blood type = incompatible liver transplantation (n = 23). In our department, we have performed 822 liver transplantations at present. Of those cases, 183 were selected wherein apheresis was performed around the time of the operation. In all cases, transplantation with sufficient apheresis was performed before the surgical operation, however, 22 patients (48.9%) died after undergoing surgery. Among the patients who underwent the postoperative apheresis, those in the nonsurvivor group had lower grafted liver weights compared to those of the survivor group. The kidney was the organ that most frequently failed due to postoperative complications. In cases of ABO blood type‐incompatible liver transplantations, patients with high preoperative anti‐A/B IgM antibody titers sustained bile duct complications, patients with high preoperative anti‐IgG antibody titers sustained hepatic necrosis, and patients with high postoperative anti‐A/B IgM and anti‐IgG antibody titers sustained hepatic necrosis most frequently.
Miller Fisher Syndrome and Plasmapheresis
Authors: Kambara Chiaki , Matsuo Hidenori , Fukudome Takayasu , Goto Hirofumi , Shibuya Noritoshi
Published: March 2003

Abstract: Treatment for Miller Fisher syndrome (MFS) is controversial, and even the natural history and prognosis are not fully understood. We retrospectively reviewed our cases of MFS for the last 3 years. The analysis of 4 MFS cases revealed that we had performed plasmapheresis or additional immunotherapy to each of 4 patients, and their symptoms resolved for up to 50 days after the onset (ataxia improved 20–35 days and ophthalmoplegia for 25–50 days) except for 1 patient, and that Guillain‐Barré syndrome had been diagnosed in 1 patient who had developed profound muscle weakness. We also discovered that MFS patients had a deviated T‐helper Type‐1 (Th1)/T‐helper Type‐2 (Th2) polarization and that plasmapheresis can shift Th2‐dominant status to Th1‐dominant status in patients with MFS. Although plasmapheresis may remove humoral factors, including anti‐GQ1b, and may induce a shift of the Th1/Th2 cytokine‐producing cell balance in peripheral blood, the therapeutic rationale has not yet been established. Therefore, controlled clinical trials are required to show whether plasmapheresis leads to earlier recovery with fewer neurologic deficits in patients with MFS.
Use of Restored Riparian Habitat by the Endangered Least Bell's Vireo (Vireo bellii pusillus)
Authors: Kus Barbara E.
Published: March 2003

A primary objective of riparian restoration in California is the creation of habitat for endangered species. Four restoration sites in San Diego County were monitored between 1989 and 1993 and evaluated for their suitability as nesting habitat for Vireo bellii pusillus (Least Bell's Vireo), a state and federally endangered obligate riparian breeder. Vegetation structure at each site was quantified annually and compared to a model of canopy architecture derived from Least Bell's Vireo territories in natural habitat. Vireo use of restored habitat was documented through systematic surveys and nest monitoring. By 1993, only one site in its entirety met the habitat suitability criteria of the model, but portions of each site during all years did so. Differences between sites in the time required to develop suitable habitat—well‐developed layered vegetation from the ground to under 8m in height)—were attributable largely to variation in annual rainfall. Vireos visited restoration sites to forage as early as the first growing season, but they did not establish territories or nest there until at least part of the site supported suitable habitat as determined from the model. Placement of territories and nests coincided with patches of dense vegetation characteristic of natural nesting areas. Occupation of restored sites was accelerated by the presence of adjacent mature riparian habitat, which afforded birds nest sites and/or foraging habitat lacking in the planted vegetation. Vireos nesting in restored habitat achieved success comparable to that of vireos nesting in surrounding natural habitat, and there was no evidence that productivity was reduced in created areas. These findings indicate that creating nesting habitat for this target species is feasible and suggest that the critical components of vireo nesting habitat have been captured in both the design and quantitative assessment of restoration sites.
Restoration of Tropical Moist Forests on Bauxite‐Mined Lands in the Brazilian Amazon
Authors: Parrotta John A. , Knowles Oliver H.
Published: March 2003

We evaluated forest structure and composition in 9‐ to 13‐year‐old stands established on a bauxite‐mined site at Trombetas (Pará), Brazil, using four different reforestation techniques following initial site preparation and topsoil replacement. These techniques included reliance on natural forest regeneration, mixed commercial species plantings of mostly exotic timber trees, direct seeding with mostly native early successional tree species, and mixed native species plantings of more than 70 tree species (the current operational restoration treatment at this site). Replicated fixed‐radius plots in each treatment and in undisturbed primary forest were used to quantify the canopy and understory structure and the abundance and diversity of all vascular plant species. Treatment comparisons considered regeneration density, species richness and diversity for all floristic categories, and, for trees and shrubs, the relative contribution of initial planting and subsequent regeneration from soil seed banks and seed inputs from nearby primary forests. With the possible exception of the stands of mixed commercial species, which were superior to all others in terms of tree basal‐area development but relatively poor in species richness, all treatments were structurally and floristically diverse, with a high probability of long‐term restoration success. Of these, the mixed native species plantings appeared to be at least risk of arrested succession due to the dominance of a broader range of tree species of different successional stages or expected life spans. In all treatments, several locally important families of primary forest trees (Annonaceae, Chrysobalanaceae, Lauraceae, Palmae and Sapotaceae) were markedly underrepresented due to a combination of poor survival of initial plantings and limitations on seed dispersal from the surrounding primary forest.
Application of Reference Data for Assessing and Restoring Headwater Ecosystems
Authors: Rheinhardt Richard D. , Rheinhardt Martha Craig , Brinson Mark M. , Faser Karl E.
Published: March 2003

Attributes of 25 headwater streams and their associated wetlands were quantitatively sampled in the inner coastal plain of eastern North Carolina. Data from these sites were used to construct and test one functional assessment model (biogeochemical cycling) using the hydrogeomorphic (HGM) approach. Of the 25 sites sampled, 16 unaltered sites were used to establish standards against which field indicators could be compared (indexed). Nine altered sites were used to examine the sensitivity of the model to assess the types of alterations typically inflicted upon headwater ecosystems in eastern North Carolina: channelization, logging, construction of cross‐floodplain ditches to shunt water directly from uplands to the main stream channel, and conversion of stream floodplains and buffer zones to cropland. Of 30 field indicators measured that potentially could be used to model alterations to hydrologic regime and biomass stocks, we found six were robust in assessing conditions related to biogeochemical cycling. Hydrologic indicators used in the model included: (1) presence/absence of channelization, (2) presence/absence of cross‐floodplain ditches, and (3) a measure of buffer condition (using width and quality). Biomass indicators included: (4) total basal area of trees, (5) percent litter cover, and (6) volume of coarse woody debris. Our preliminary biogeochemical cycling model using these six variables was sensitive to alterations in nine altered sites and to a suite of hypothetical restorations of the most altered site. However, in order to improve accuracy of our preliminary model, it should be validated with studies designed to measure how alterations of various types and magnitudes affect biogeochemical processes.
The Role of Isolated Trees in Facilitating Tree Seedling Recruitment at a Degraded Sub‐Tropical Rainforest Site
Authors: Toh Ing , Gillespie Melina , Lamb David
Published: March 2003

Successional development at abandoned farmlands in southern Queensland, formerly occupied by sub‐tropical rain forest is centred around scattered, isolated trees. Soil seed banks contain few woody plants and most tree species appear to be recruited from seed dispersed into the site by birds or bats. Scattered, low‐growing trees <3 m in height act as the initial focus for the activities of seed‐dispersing birds, but this process is accelerated by the development of taller trees> 6 m in height that act as bird perches. The identity of these trees and whether or not they offer a fruit reward appears to matter less than their structure and suitability as a bird perch. The process of seedling recruitment may be accelerated when two or more trees form a cluster. The proportion of seedlings that survive and grow beyond 150 cm in height appears to be very small. Most of those that do can be classed as secondary rather than primary forest species, even though many primary forest species initially colonize the site. These observations were used to develop guidelines to accelerate the recovery of rainforest at degraded sites. The guidelines promote the early establishment of species that are usually poorly dispersed (e.g., large‐fruited species), planted in scattered clumps. The guidelines should be suitable for situations where relatively large areas are in need of rehabilitation.
Reducing Competitive Suppression of a Rare Annual Forb by Restoring Native California Perennial Grasslands
Authors: Carlsen Tina M. , Menke John W. , Pavlik Bruce M.
Published: March 2003

Populations of the rare annual forb Amsinckia grandiflora may be declining because of competitive suppression by exotic annual grasses, and may perform better in a matrix of native perennial bunchgrasses. We conducted a field competition experiment in which Amsinckia seedlings were transplanted into forty 0.64‐m2 experimental plots of exotic annual grassland or restored perennial grassland. The perennial grassland plots were restored using mature 3 cm‐diameter plants of the native perennial bunchgrass Poa secunda planted in three densities. The exotic annual grassland plots were established in four densities through manual removal of existing plants. Both grass types reduced soil water potential with increasing biomass, but this reduction was not significantly different between grass types. Both grass types significantly reduced the production of Amsinckia inflorescences. At low and intermediate densities (dry biomass per unit area of 20–80 g/m2), the exotic annual grasses reduced Amsinckia inflorescence number to a greater extent than did Poa, although at high densities (>90 g/m2) both grass types reduced the number of Amsinckia inflorescences to the same extent. The response of Amsinckia inflorescence number to Poa biomass was linear, whereas the same response to the annual grass biomass is logarithmic, and appeared to be related to graminoid cover. This may be because of the different growth forms exhibited by the two grass types. Results of this research suggest that restored native perennial grasslands at intermediate densities have a high habitat value for the potential establishment of the native annual A. grandiflora.
Deer Herbivory as an Ecological Constraint to Restoration of Degraded Riparian Corridors
Authors: Opperman Jeff J. , Merenlender Adina M.
Published: March 2003

Ungulate herbivory can impact riparian vegetation in several ways, such as by reducing vigor or reproductive output of mature plants, and through increased mortality of seedlings and saplings. Much work has focused on the effects of livestock grazing within riparian corridors, while few studies have addressed the influence of native ungulate herbivory on riparian vegetation. This study investigated the effect of deer herbivory on riparian regeneration along three streams with degraded riparian corridors in Mendocino County, California. We utilized existing stream restoration efforts by private landowners and natural resource agencies to compare six deer exclosures with six upstream control plots. Livestock were excluded from both exclosure and control plots. Three of the deer exclosures had been in place for 15 years, one for 6 years, and two for 4 years. The abundance and size distribution of woody riparian plant species such as Salix exigua, S. laevigata, S. lasiolepis, Alnus rhombifolia, and Fraxinus latifolia were quantified for each exclosure and control plot. The mean density of saplings in deer exclosures was 0.49 ± 0.15/m2, while the mean density of saplings in control plots was 0.05 ± 0.02/m2. Within exclosures, 35% of saplings were less than 1 m and 65% were greater than 1 m; within control plots, 97% of saplings were less than 1 m in height. The fact that little regeneration had occurred in control plots suggests that deer herbivory can substantially reduce the rate of recovery of woody riparian species within degraded riparian corridors. Exclusionary fencing has demonstrated promising results for riparian restoration in a region with intense deer herbivory.
Restoration of a Cirsio‐Molinietum Fen Meadow on an Agriculturally Improved Pasture
Authors: Tallowin J. R. B. , Smith R. E. N.
Published: March 2003

The objective of this study was to identify soil nutrient availability conditions that would allow the establishment of key species of the Molinia caerulea‐Cirsium dissectum fen meadow. The restoration site was a species‐poor agriculturally improved pasture that had received no inorganic fertilizer for greater than 13 years. Treatments designed to reduce site fertility included: cutting and removal of herbage, cultivation, fallowing and topsoil removal. Straw and/or lignitic‐clay were incorporated as soil amendment treatments. Cirsio‐Molinietum species were either sown or planted as seedlings on treated plots. Neither soil nitrogen nor potassium availability, per se, appeared to limit the establishment of Cirsio‐Molinietum species, whereas enhanced phosphorus availability did. Removal of the top 15–20 cm of soil reduced the total soil phosphorus amount by about 85 percent and depleted plant P availability. Nutrient‐poor and relatively calcium‐enriched soil exposed by topsoil removal allowed the development of a community with affinities to the Cirsio‐Molinietum typical fen meadow. Redundancy analysis indicated the existence of marked vegetational gradients within the topsoil removal treatments that were influenced by the straw and the lignitic‐clay amendments. The way in which these two amendments influenced edaphic conditions were unclear. Where the topsoil was not removed the vegetation became dominated by a few competitive species and although many of the planted Cirsio‐Molinietum species were still present after four years, they were found only in trace amounts. Removal of most of the soil organic matter was a practical success in that it created suitable edaphic conditions for all the planted Cirsio‐Molinietum species to remain well established.
Soil Seed Bank as an Input of Seed Source in Revegetation of Lead / Zinc Mine Tailings
Authors: Zhang Z. Q. , Shu W. S. , Lan C. Y. , Wong M. H.
Published: March 2003

The goal of the present study was to assess a soil seed bank as an input seed source for revegetating lead/zinc (Pb/Zn) mine tailings. The seed bank source was abandoned farmland, whose top 10‐cm layer of topsoil contained 6,850 ± 377 seeds/m2 from 41 species. The seeds in the soil were principally distributed in the upper 0–2 cm, which held 75.8% of total seeds and 92.7% of species composition. The top 2‐cm layer of topsoil may be sufficient to serve the purpose of providing a seed source for revegetation on derelict lands, including mined lands. Four different thicknesses of topsoil (1, 2, 4, and 8 cm, redistributed from the total 0–10‐cm layer from the farmland) were field‐tested on the Pb/Zn mine tailings. There was no significant difference in seedling density among the 4 thickness treatments. Many seeds in the treatments with more than 1‐cm of topsoil were unable to emerge from the deeper layer. Seedlings in plots with topsoil of 1‐, 2‐ and 4‐cm failed to establish within 1 year due to the extremely high acidity (pH 2.39 to 2.76). A shallow layer of topsoil cannot neutralize the sulfuric acid generated from oxidation of pyrites in the tailings. For establishment of seedlings on metalliferous lands, an insulating layer such as subsoil, building rubble, or domestic refuse is necessary before covering with valuable topsoil. The woody legume Leucaena leucocephala grown on the tailings with a topsoil cover of 8‐cm was the most dominant species. Lead was accumulated in root, branch, stem bark, and xylem, which accounted for more than 80% of the total metal concentration in the plant. This portion of Pb will reside in the plant for a long period, while the smaller portion of Pb in the leaf (about 15%) could be returned to the environment as litter during growth. Woody plants may have an advantage in metal‐phyto‐remediation over herbaceous plants.
Restoration of a Landfill Site in Berlin, Germany by Spontaneous and Directed Succession
Authors: Rebele Franz , Lehmann Cornelia
Published: March 2003

We report on spontaneous and directed succession on a dry sandy landfill site of low fertility at Berlin‐Malchow, Germany. Changes in species composition and cover were followed on unmown and mown permanent plots of 2 × 2 m size through 5 years of vegetation development. Species richness on unmown plots was relatively constant during the time of observation, with 20 to 25 species per 4 m2. Total cover of unmown plots continuously increased from approximately 10% in the first year to 80% in the fifth year. There are no clearly discernible sequential successional stages until present. The species composition includes species of all life forms, which colonized the site immediately after the initiation of the succession process representing the initial floristic composition type of vegetation development. However, perennial grasses and herbs gradually increased in cover up to approximately 40%. Woody plants were also present from the first year of succession and increased up to more than 20% cover in the fifth year, forming a shrub layer (>0.5 m) after the second year. Mowing significantly increased species richness, which was evident from the third year onward. This effect was mainly due to the reduction of the tall perennial grass Calamagrostis epigejos. Solidago canadensis and woody species were also significantly affected (lower cover and height), whereas short perennial herbs like Plantago lanceolata and Trifolium repens benefited from mowing.
Patterns of Species Richness and Composition in Re‐Created Grassland
Authors: Sluis William J.
Published: March 2003

The success of many prairie restorations is not well documented. A restoration begun in 1975 at the Fermi National Accelerator Laboratory near Chicago, Illinois allows assessment of restoration efforts as well as changes through time. Data are presented on species richness and composition for 13 restorations planted in successive years between 1975 and 1990 and two remnant prairies. Presence of species was recorded using a stratified random design. Species richness at several scales and non‐metric multidimensional scaling ordination were used to assess trends in the vegetation. Species richness declined through time at all scales examined and was always less in the restored prairies than that found in the remnant prairies. Species composition changed with time but not in the direction of the composition found in the remnants. Our understanding of the maintenance of species richness is not sufficient to allow the re‐creation of patterns of species found in remnant grassland communities.
An Assessment of a Small Urban Stream Restoration Project in Northern California
Authors: Purcell Alison H. , Friedrich Carla , Resh Vincent H.
Published: March 2003

Stream restoration projects have become increasingly common, and the need for systematic post‐project evaluation, particularly for small‐scale projects, is evident. This study describes how a 70‐m restored reach of a small urban stream, Baxter Creek (in Poinsett Park, El Cerrito, California), was quickly and inexpensively evaluated using habitat, biological, and resident‐attitude assessments. The restoration involved opening a previously culverted channel, planting riparian vegetation, and adding in‐stream step‐pool sequences and sinuosity. Replicated benthic macroinvertebrate samples from the restored site and an upstream unrestored site were compared using several metrics, including taxa richness and a biotic index. Both biological and habitat quality improved in the restored compared with the unrestored section. However, when compared with a creek restored 12 years before, habitat condition was of lower quality in the recently restored creek. A survey of the neighborhood residents indicated that, overall, they were pleased with the restored creek site. The approach used in this demonstration project may be applicable to other small‐scale evaluations of urban stream restorations.
Decomposition of Sarcocornia quinqueflora on an Iron‐Smelting Slag Substrate
Authors: Dick T. M. , Streever W. J. , Osunkoya O. O.
Published: March 2003

Restoration of salt marsh habitat is becoming more common in Australia. However, little is known about restoring salt marshes on substrates contaminated by slag from iron smelting, which could affect microbial activity. This study, conducted near Newcastle, Australia, compares initial C, N, and P mass and decomposition of Sarcocornia quinqueflora (glasswort or samphire) from (1) a restoration site with a slag‐and‐mud substrate, (2) the restoration site's donor marsh, and (3) other nearby sites sampled to provide information on background variability. A litterbag technique with a 180‐day incubation period was used to quantify total, C, N, and P mass losses from decomposition. Although there were significant differences between sites in initial N mass and loss of C and P over the period of our study, the presence of slag did not slow decomposition rates as measured using litterbags. Further work is needed to assess other aspects of wetland structure and function on slag substrates.
Influence of Spacing on Mechanically Transplanted Seagrass Survival in a High Wave Energy Regime
Authors: Paling Eric I. , Van Keulen Mike , Wheeler Karen D. , Phillips Jim , Dyhrberg Roger
Published: March 2003

Abstract The wave‐exposed nature of much of the southwestern Australian coastline considerably reduces the protective influence of seagrasses, and sediment movement appears to be relatively unaffected by their presence. Present seagrass restoration efforts focus on the deployment of large mechanically transplanted “sods” of seagrass as a means of combating the negative effects of water motion on transplant survival. The aim of this study was to investigate the combined role of wave energy and transplant spacing on sediment movement and transplant survival to provide guidance for seagrass transplantation in areas of high wave energy. One hundred sixty sods (0.25 m2) of seagrass were mechanically extracted from a mixed meadow consisting of Amphibolis griffithii (Cymodoceaceae) and Posidonia coriacea (Posidoniaceae) and planted in a high wave energy site with the treatments configured as three replicates of 16 sods placed in 4 × 4–meter squares at distances of 0.5, 1.0, and 2.0 meters apart. An additional 16 single sods were planted randomly throughout the site. Monitoring was conducted at two monthly intervals and consisted of counting the number of sods surviving and measuring the shoot density of seagrass species within each surviving sod. Sediment height was monitored using a series of sediment plates and an electronic sediment level sensor. Sod spacing had no significant effect upon transplant survival, which remained above 90% for 4 months after transplantation and then declined with the onset of winter (June to August). After 14 months individual sod survival was between 9% and 40%. Initial shoot densities were 200 to 500 shoots/m2 and declined to less than 50 shoots/m2. Sediment fluctuations up to 35 cm were noted, occasionally taking place over a matter of hours, and storms during winter caused significantly increased sediment movement. This probably curtailed rhizome extension and prevented the expansion of the transplants. This study indicates that the ability of seagrasses to influence sediment would appear to vary with the prevailing hydrodynamic regime and that a reappraisal of the notion that all seagrass communities trap sediment is necessary.
Role Of Meissner Corpuscles In Tactile Potential Generation
Authors: Nolano M , Provitera V , Lullo F , Saltalamacchia A , Crisci C , Santoro L.
Published: March 2003

Sensory potentials evoked by a physiological stimulus, tactile stimulation, can be recorded along a nerve. These responses express the function of the whole distal part of the sensory pathway, including mechanoreceptors and their afferent fibers, structures by‐passed by the electrical stimulation. Using immunohistochemical procedures it is possible to investigate morphology and distribution of the neural structures presumably involved in the generation of tactile responses in digital glabrous skin. The mechanoreceptor density is higher in fingertip and in younger people. The area of the tactile potential tends to be smaller in older people and following the stimulation of the proximal phalanx with respect to the stimulation of the distal one, suggesting a correlation between tactile potential area and Meissner corpuscles' density. To assess the exact role of Meissner corpuscles in tactile potentials formation, we investigated in normal subjects the morphology, density and distribution of mechanoreceptors and their afferent myelinated fibers, and tactile and electrical responses. To correlate electrophysiological and morphological data we recruited a group of patients affected by congenital and acquired sensory neuropathies that underwent both skin biopsy and electrophysiological tests. We found a significant correlation between the area of the tactile potentials and the density of normal Meissner corpuscles and papillary myelinated fibers. These data support the hypothesis that Meissner corpuscles play a significant role in the generation of tactile potential. Therefore tactile stimulation is a reliable way to investigate the sensory pathway extreme termination.
Neurological Dysfunction And Axonal Degeneration In Charcot‐Marie‐Tooth Disease Type 1A
Authors: Krajewski KM , Lewis RA , Fuerst DR , Turansky C , Hinderer SR , Garbern J , Kamholz J , Shy ME
Published: March 2003

Charcot‐Marie‐Tooth disease type 1A (CMT1A), the most frequent form of GAIT, is caused by a 1.5 Mb duplication on the short arm of chromosome 17. Patients with CMT1A typically have slowed nerve conduction velocities (NCVs), reduced compound motor and sensory nerve action potentials (CMAPs and SNAPs), distal weakness, sensory loss and decreased reflexes. In order to understand further the molecular pathogenesis of CMT1A, as well as to determine which features correlate with neurological dysfunction and might thus be amenable to treatment, we evaluated the clinical and electrophysiological phenotype in 42 patients with CMT1A. In these patients, muscle weakness, CMAP amplitudes and regeneration, motor unit number estimates correlated with clinical disability, while motor NCV did not. In addition, loss of joint position sense and reduction in SNAP amplitudes also correlated with clinical disability, while sensory NCV did not. Taken together, these data strongly support the hypothesis that neurological dysfunction and clinical disability in CMT1A are caused by loss or damage to large calibre motor and sensory axons. Therapeutic approaches to ameliorate disability in CMT1A, as in amyotrophic lateral sclerosis and other neurodegenerative diseases, should thus be directed towards preventing axonal degeneration and/or promoting axonal regeneration.
An experimental study on the perineurial window
Authors: Sugimoto Yoshihisa , Takayama Shinichiro , Horiuchi Yukio , Toyama Yoshiaki
Published: March 2003

Abstract  Neurological symptoms of herniated nerve fibers resulting from limited perineurial injury from sharp materials such as needles have become a recent topic in clinical practice. However, the mechanism of this disorder, which is known as a perineurial window, has not been clarified. To investigate the mechanism of nerve damage in the perineurial window, we designed small (1‐mm length) and large (5‐mm length) perineurial windows using tibial nerves of Wistar rats. In the 1‐mm group, a marked hernia of the endoneurial contents developed soon and decreased in size with time, but protrusion of nerve fibers was still observed after 12 weeks. Nerve fibers in both the herniated portion and under the edge of the window were damaged. Even after 12 weeks, regeneration of the nerve fibers and the perineurium was incomplete. In contrast, in the 5‐mm group, the initial endoneurial edema was remarkable, but herniated nerve fibers were not seen after 12 weeks. Neurological impairment in the 5‐mm group was marked in the early stage but rapidly recovered. The repair of the perineurium and nerve fibers in the 1‐mm group was slower than in the 5‐mm group. Persistent neurological symptoms in the perineurial window appeared to be more closely associated with entrapment of nerve fibers at the window edge rather than with disruption of endoneurial homeostasis.
STEROLS OF SOME MARINE PRYMNESIOPHYCEAE
Authors: Ghosh Parthasarathi , Patterson Glenn W. , Wikfors Gary H.
Published: March 2003

Sterols were identified in six marine prymnesiophyte isolates, some of which appear to have value as bivalve food. The principal sterol in Pleurochrysis carterae (Milford #961) and an unidentified prymnesiophyte (CCMP1215) was 24‐methylcholesta‐5,22‐dienol, a common sterol in prymnesiophytes. Isolates CCMP594, CCMP609, and CCMP459 contained either 24‐ethylcholesta‐5,22‐dienol or 24‐ethylcholest‐22‐enol as the major sterol. In addition, Pavlova pinguis (CCMP609) and Pavlova sp. (CCMP459) contained the unusual dihydroxysterols 24‐methylpavlovol and 24‐ethylpavlovol, which have been found only in members of the Pavlovales. Prymnesium parvum contained cholesterol without traces of other sterols. Compared to the other isolates, the quantity of sterols was extremely low in P. parvum.
ENVIRONMENTAL AND ENDOGENOUS REGULATION OF CYST GERMINATION IN TWO FRESHWATER DINOFLAGELLATES
Authors: Rengefors Karin , Anderson Donald M.
Published: March 2003

The role of excystment in relation to seasonal succession was investigated in two freshwater dinoflagellates, Ceratium hirundinella (O.F. Müller) Dujardin and Peridinium aciculiferum (Lemmermann). Field studies and laboratory experiments were performed to determine which factors regulate the timing of cyst germination. Environmental factors (temperature, light, nutrients, and anoxia) and endogenous factors (maturation period and biological clock) were investigated. Our main results indicate that temperature and internal maturation period determine when germination can occur. C. hirundinella had a maturation period of 4.5 months and germinated in the laboratory and in the field at temperatures above 6° C. P. aciculiferum had a maturation period of 2.5 months and germinated in the laboratory and in the field at temperatures below 7° C. In addition, our results indicated that both species were regulated by a biological clock. Furthermore, anoxia prevented the germination of C. hirundinella, contrary to results in earlier studies. To conclude, we could explain the appearance in plankton of the two dinoflagellate species through two main factors regulating excystment, that is, temperature and maturation period.
DISTRIBUTION OF INTRACELLULAR NITROGEN IN MARINE MICROALGAE: BASIS FOR THE CALCULATION OF SPECIFIC NITROGEN‐TO‐PROTEIN CONVERSION FACTORS
Authors: Lourenço Sergio O. , Barbarino Elisabete , Marquez Ursula M. Lanfer , Aidar Elizabeth
Published: March 2003

The utilization of nitrogen‐to‐protein conversion factors (N‐Prot factors) is a widely accepted and practical way to determine total protein content. The accuracy of protein determination depends on the establishment of specific N‐Prot factors, since the conventional factor of 6.25 may be unsuitable for all species. This study was designed to determine the concentrations of the main nitrogenous compounds and to establish N‐Prot factors specific for the following marine microalgae: Chlorella minutissima, Dunaliella tertiolecta, Hillea sp., Isochrysis galbana, Nannochloropsis oculata, Phaeodactylum tricornutum, Prorocentrum minimum, Skeletonema costatum, Synechococcus subsalsus, and Tetraselmis gracilis. Cultures were maintained under a 12‐h photoperiod (300 μmol photons·m−2·s−1) at temperatures of 20.0°± 1.0° C (dark) to 23.0°± 2.0° C (light) in Walne’s culture medium without additional external carbon sources. The distribution of intracellular nitrogen was studied by determining total nitrogen (TN, by CHN [carbon, hydrogen, and nitrogen] analysis), protein N (PN, by analysis of total amino acids), and nonprotein N (NPN, determined by analysis of DNA, RNA, chlorophylls (chl) a,b, and c, and intracellular inorganic nitrogen—NO3−, NO2−, and NH3+ NH4+) in logarithmic and stationary growth phases of cultures. Variations occurred in both accumulation and distribution of PN and NPN among the species, as well as in each species during the different growth phases. Inorganic nitrogen compounds were observed to be the most important NPN source (from 6.4 ± 0.1% to 41.8 ± 4.2% of total N) in all species (except D. tertiolecta), followed by nucleic acids (from 0.8 ± 0.1% to 26.1 ± 2.4% of TN) and chlorophylls (from 0.2 ± 0.0% to 3.1 ± 0.3% of TN). Total amino acid residues ranged from 63.1 ± 4.6% up to 88.1 ± 11.2% of TN, which is in agreement with the presence of high NPN concentrations. N‐Prot factors are proposed for each growth phase in the studied species, based on the ratio of amino acid residues to TN, establishing specific N‐prot factors ranging from 3.60 ± 0.27 to 4.99 ± 0.64. The mean N‐Prot factor for all species/growth phases was 4.58 ± 0.11. The present study shows that the use of the traditional factor 6.25 is not suitable for these marine microalgae, and possibly for other species, because it overestimates their actual protein content.
CONFIRMATION OF CATFISH MORTALITIES RESULTING FROM MICROCYSTIN PRODUCED DURING MICROCYSTIS BLOOMS
Authors: Zimba P.V. , Khoo L. , Carmichael W.W. , Gaunt P.
Published: March 2003

Enigmatic deaths of finfish have occurred in freshwater systems for many years. Some of these fish mortalities can be attributed to the accumulation of cyanobacterial toxins during ingestion of floating feeds or passively through opercular ventilation. We recently were able to document the accumulation of microcystin and resulting catastrophic mortality of pond‐raised catfish (Ictalurus punctatus). The causative organism, Microcystis aeruginosa, was the dominant phytoplankton component within the cooler fall‐winter season. Microcystin, a hepatotoxin produced by Microcystis, was detected in water and catfish liver samples. Fish exposed to pond water containing this bloom were killed within 24 h. Necropsy of fish exposed to pond water revealed congested liver and spleen tissues. Environmental conditions associated with several similar bloom events suggest several predictive options to forecast conditions supporting toxin formation, particularly temperature.
THALASSOCHYTRIUM GRACILARIOPSIDIS (CHYTRIDIOMYCOTA), GEN. ET SP. NOV., ENDOSYMBIOTIC IN GRACILARIOPSIS SP. (RHODOPHYCEAE)
Authors: Nyvall Pi , Pedersén Marianne , Longcore Joyce E.
Published: March 2003

Thalassochytrium gracilariopsidis gen. et sp. nov. is an endosymbiotic, polycentric, zoosporic fungus that infected cultures of the red alga Gracilariopsis sp. Based on the posteriorly uniflagellate zoospore and the platelike cristae of the mitochondria, the fungus is placed in the Chytridiomycota. Ultrastructurally, the fungal zoospore is distinguished by the anterior position of the kinetosome, a unique microbody‐lipid globule complex, an electron‐opaque helix associated with the kinetosome and lipid globules, and a beaked nucleus. Zoospores are positively phototactic, and the unusual helix might constitute part of the photosensory apparatus. Zoospores lack certain taxonomically important structures, such as a rumposome, props, a nonflagellated kinetosome, and flagellar roots. The organism does not fit into any described genus, and the features of its zoospore differ from those of any described order. The fungal thallus is polycentric with multinucleate, septate hyphae. Haustoria form within the algal cells. The fungus does not appear to cause major harm to its host and seems to be host specific. However, during intense sporulation of the fungus, degradation of host chloroplasts was observed in medullary cells.
SALINITY‐DEPENDENT LIMITATION OF PHOTOSYNTHESIS AND OXYGEN EXCHANGE IN MICROBIAL MATS
Authors: Garcia‐Pichel Ferran , Kühl Michael , Nübel Ulrich , Muyzer Gerard
Published: March 2003

We used benthic flux chambers and microsensor profiling under standardized incubation conditions to compare the short‐term (hours) and long‐term (days) functional responses to salinity in eight different hypersaline microbial mats. The short‐term response of productivity to changes in salinity was specific for each community and in accordance with optimal performance at the respective salinity of origin. This pattern was lost after long‐term exposure to varying salinities when responses to salinity were found to approach a general pattern of decreasing photosynthesis and oxygen exchange capacity with increasing salinity. Exhaustive measurements of oxygen export in the light, oxygen consumption in the dark and gross photosynthesis indicated that a salinity‐dependent limitation of all three parameters occurred. Maximal values for all three parameters decreased exponentially with increasing salinity; exponential decay rates (base 10) were around 4–5 mL·g−1. The values of mats in steady state with respect to salinity tended to approach this salinity‐dependent limit. On the basis of environmental and ecophysiological data, we argue that this limitation was not caused directly by salinity effects on the microorganisms. Rather, the decreasing diffusive supply of O2 in the dark and the increasing diffusion barriers to O2 escape in the light, which intensify with increasing salinity, were likely responsible for the salinity‐dependent limitations observed.
PHYLOGENETIC POSITION OF SYMBIODINIUM (DINOPHYCEAE) ISOLATES FROM TRIDACNIDS (BIVALVIA), CARDIIDS (BIVALVIA), A SPONGE (PORIFERA), A SOFT CORAL (ANTHOZOA), AND A FREE‐LIVING STRAIN
Authors: Carlos Alvin A. , Baillie Brett K. , Kawachi Masanobu , Maruyama Tadashi
Published: March 2003

The genus Symbiodinium is the commonly observed symbiotic dinoflagellate (zooxanthellae) that forms mutual associations with various marine invertebrates. Numerous studies have revealed that the genus is comprised of a group of diverse taxa, and information on the phylogenetic relationships among the genus’ members is increasing. In this study, small subunit (SSU) ribosomal RNA (ssrRNA) gene sequences were determined for 15 more Symbiodinium strains from 12 relatively unstudied host taxa (Indo‐Pacific tridacnids, cardiids, sponge, and soft coral), 1 hitherto unreported free‐living Symbiodinium strain, and 4 other Symbiodinium strains from four other host taxa (Indo‐Pacific zoanthid, foraminifer, jellyfish, and mid‐Pacific hard coral). Their respective phylogenetic positions were inferred, and strains that are either closely related to or distinct from previously reported Symbiodinium taxa were revealed. The cultured Symbiodinium strains isolated from individuals of six species of tridacnids and three species of cardiids all had identical ssrRNA gene sequences, are closely related to S. microadriaticum Freudenthal, and are indistinguishable from the RFLP Type A strain previously reported. However, the ssrRNA gene sequences of clam symbionts that were obtained via gene cloning were different from those of the cultured isolates and represent strains that are close to the RFLP Type C strains. The Symbiodinium‐like dinoflagellate from the Indo‐Pacific sponge Haliclona koremella De Laubenfels is distinct from any of the Symbiodinium taxa studied and may be similar to the symbiont previously isolated from the stony coral Montipora patula Quelch. The isolates from the soft coral Sarcophyton glaucum Quoy et Gaimard and from the zoanthid Zoanthus sp. are both very closely related to S. pilosum Trench et Blank. The free‐living Symbiodinium isolate is very closely related to the symbiont isolated from the Indo‐Pacific foraminifer Amphisorus hemprichii Ehrenberg, which in turn is distinct from the Red Sea strain isolated from a similar host. Theisolate from Cassiopeia sp. is different from S. microadriaticum F., the type species harbored by Cassiopeia xamachana Bigelow, and is instead very closely related to S. pulchrorum Trench isolated from a sea anemone. The symbiont from the stony coral M. verrucosa Lamarck is a sister taxon to the symbionts isolated from the foraminifera Marginopora kudakajimensis Gudmundsson and Sorites orbiculus Forskål. These data suggest that polymorphic symbioses extend from cnidarians to some bivalve, foraminifer, and jellyfish host species.
ULTRASTRUCTURE AND SYSTEMATICS OF TWO NEW FRESHWATER RED CRYPTOMONADS, STOREATULA RHINOSA, SP. NOV. AND PYRENOMONAS OVALIS, SP. NOV.
Authors: Kugrens Paul , Clay Brec L. , Lee Robert E.
Published: March 2003

The ultrastructure and systematics of two red colored freshwater cryptomonads, Storeatula rhinosa, sp. nov. and Pyrenomonas ovalis, sp. nov., are described for the first time. Storeatula, which had been described from marine waters only, has a single inner periplast sheet and a fibrous surface periplast component. Cells lack a furrow but possess a gullet, a bilobed chloroplast connected by a pyrenoid and a nucleomorph located in an indentation of the pyrenoid. This freshwater Storeatula possesses the same general features as the marine species, but it has a contractile vacuole and lacks the lobed chloroplast of S. major. P. ovalis has the generic characteristics described for marine species of Rhodomonas. These characteristics include a short furrow, a deep gullet, square inner periplast plates with beveled corners, a slightly fibrillar surface periplast component, a single chloroplast with two lobes connected by a pyrenoidal bridge and a nucleomorph located in an indentation of the pyrenoid.
A METHOD USING CHEMICAL OXIDATION TO REMOVE LIGHT ABSORPTION BY PHYTOPLANKTON PIGMENTS
Authors: Ferrari Giovanni M. , Tassan Stelvio
Published: March 2003

The effectiveness of a new method for the removal of pigment absorption in phytoplankton cells as required in optical measurements has been extensively tested and compared with the performance of the currently used methanol extraction method.
EFFECTS OF NH4+ ASSIMILATION ON DARK CARBON FIXATION AND β‐1,3‐GLUCAN METABOLISM IN THE MARINE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)
Authors: Granum Espen , Myklestad Sverre M.
Published: March 2003

The effects of NH4+ assimilation on dark carbon fixation and β‐1,3‐glucan metabolism in the N‐limited marine diatom Skeletonema costatum (Grev.) Cleve (Bacillariophyceae) were investigated by chemical analysis of cell components and incorporation of 14C‐bicarbonate. The diatom was grown in pH‐regulated batch cultures with a 14:10 h LD cycle until N depletion. The cells were then incubated in the dark with 14C‐bicarbonate, but without a source of N for 2 h, then in the dark with 63 μmol·L−1 NH4+ for 3 h. Without N, the cellular concentration of free amino acids was almost constant (∼4.5 fmol·cell−1). Added NH4+ was assimilated at a rate of 12 fmol·cell−1·h−1, and the cellular amino acid pool increased rapidly (doubled in <1 h, tripled in <3 h). The glutamine level increased steeply (45× within 3 h), and the Gln/ Glu ratio increased from 0.1 to 2.4 within 3 h. The rate of dark C fixation during N depletion was only 1.0 fmol·cell−1·h−1. The addition of NH4+ strongly stimulated dark C fixation, leading to an assimilation rate of 4.0 fmol·cell−1·h−1, corresponding to a molar C/N uptake ratio of 0.33. Biochemical fractionation of organic 14C showed no significant 14C fixation into amino acids during N depletion, but during the first 1–2 h of NH4+ assimilation, amino acids were rapidly radiolabeled, accounting for virtually all net 14C fixation. These results indicate that anaplerotic β‐carboxylation is activated during NH4+ assimilation to provide C4 intermediates for amino acid biosynthesis. The level of cellular β‐1,3‐d‐glucan was constant (16.5 pg·cell−1) during N depletion, but NH4+ assimilation activated a mobilization of 28% of the reserve glucan within 3 h. The results indicate that β‐1,3‐glucan in diatoms is the ultimate substrate for β‐carboxylation, providing precursors for amino acid biosynthesis in addition to energy from respiration.