bluuebunny/crossref_metadata_2025 huggingface dataset:
Season of Burn Influences Fire Behavior and Fuel Consumption in Restored Shortleaf Pine–Grassland Communities
Authors: Sparks Jeffrey C. , Masters Ronald E. , Engle David M. , Bukenhofer George A.
Published: March 2003

Pine forests of southeastern United States have been burned primarily in the dormant season to accomplish silvicultural objectives, but with increased emphasis on ecosystem restoration fires are now prescribed in other seasons. We observed fire behavior during both growing season and dormant season prescribed fires in shortleaf pine (Pinus echinata) stands managed as pine–grassland communities for the endangered Red‐cockaded Woodpecker (Picoides borealis). Fuel beds for dormant season fires were characterized by lower amounts of live fuels, higher amounts of 1‐hr time lag fuel and a greater total fuel load than growing season fires. Fuel consumption and percent of the total fuels consumed was greater in dormant season fires than in growing season fires. Fireline intensity, heat per unit area, reaction intensity, and rate of spread were greater in dormant season fires than in growing season fires. Lower fire intensity in growing season fires was possibly a function of lower amounts of 1‐hr time lag fuels, higher amounts of live herbaceous fuels, and possibly a less porous fuel bed. Additionally, growing season fires had lower heat per unit area and reaction intensity and slower rates of spread. The Keetch‐Byram drought index (KBDI) did not provide a good index for potential fire behavior on our drought‐prone sandy loam soils. KBDI during growing season fires averaged over four times greater than during dormant season fires, but fire intensity was greater in dormant season fires. Low KBDI values may be misleading and give a false sense of security for dormant season fire prescriptions on sandy loam soils because the duff layer may dry more quickly as a result of inherent low water holding capacity. High KBDI values may result in prescribed burns being canceled because of conditions that are erroneously perceived to be outside the prescription window. We caution against over‐reliance on KBDI as a determining factor for conducting prescribed burns on areas with sandy or sandy loam soils.
Effects of Jack Pine Plantation Management on Barrens Flora and Potential Kirtland's Warbler Nest Habitat
Authors: Houseman Gregory R. , Anderson Roger C.
Published: March 2003

Jack pine barrens, once common in northern lower Michigan, mostly have been converted to managed jack pine plantations. Management of the disturbances associated with logging provides the opportunity to maintain the unique plant assemblages of jack pine barrens and nest habitat of the federally endangered Kirtland's warbler. Studies indicate thatCarex pensylvanicacan develop into dense mats and strongly compete with other barrens species such asVaccinium angustifolium, which seem to be important species for Kirtland's warbler nest locations. According to forest managers, the most important factors facilitating high cover ofV. angustifoliumand reducing cover ofC. pensylvanicaare the amount of shade produced by tree crowns before harvest (pre‐harvest shade), the length of time between harvest and planting (planting delay), and fire. We found that high or low levels of pre‐harvest shade had no effect on cover of either V. angustifoliumorC. pensylvanica. Planting delays of at least three years following prescribed burns generally increased cover ofV. angustifoliumin forest plots, which are important for warbler nesting. Analysis of community composition in openings indicated that burning enhanced the growth of barrens species. We found only weak evidence for a negative correlation between the cover ofV. angustifoliumandC. pensylvanicaon our study sites. The openings created in the jack pine plantation are important refugia for barrens flora that would likely be lost under forests managed strictly for jack pine. Maintenance of jack pine barrens flora and Kirtland's warbler nest habitat is possible within the context of a heavily managed forest plantation system.
Microbial Community Structure and Carbon‐Utilization Diversity in a Mine Tailings Revegetation Study
Authors: Moynahan October Seastone , Zabinski Catherine A. , Gannon James E.
Published: March 2003

Restoration of metals‐contaminated environments requires a functional microbial community for successful plant community establishment, soil development, and biogeochemical cycling. Our research measured microbial community structure and carbon‐utilization diversity in treatment plots from a mine waste revegetation project near Butte, Montana. Treatments included two controls (raw tailings) either (1) with or (2) without tilling, (3) shallow‐tilled lime addition, (4) deep‐tilled lime addition, (5) lime slurry injection, (6) topsoil addition, and (7) an undisturbed area near the tailings. Microbial community structural differences were assayed by plate counts of heterotrophic bacteria, actinomycetes, fungi, and bacterial endospores, and quantification of arbuscular mycorrhizae colonization. Metabolic diversity differences were assessed by carbon‐utilization profiles generated with Biolog microtiter plates. Heterotrophic bacteria counts were significantly higher in the limed and topsoil treatment plots than the control plots, and the actinomycete and fungal counts increased in the tilled control plot as well. Endospore counts were significantly higher in the topsoil addition and the undisturbed plots than the other treatment plots. Carbon‐utilization activity was very low in untreated plots, intermediate in lime‐treated plots, and very high in topsoil and undisturbed plots. Arbuscular mycorrhizae (AM) colonization levels of two grass species showed low levels of colonization on control, shallow‐limed, and lime slurry‐injected plots, and high levels on the deep‐limed and topsoil‐addition plots. Plant and soil system components increased across the treatment plots, but individual components responded differently to changing environmental conditions.
Using Soil13C to Detect the Historic Presence ofSchizachyrium scoparium(Little Bluestem) Grasslands on Martha's Vineyard
Authors: Peterson G. Gregory , Neill Christopher
Published: March 2003

AbstractWe used differences in soil carbon δ13C values between forested sites and grasslands dominated by the C4grassSchizachyrium scoparium(little bluestem) to detect the presence of former grasslands in the historical landscape of the coastal sand plain of Martha's Vineyard, Massachusetts, U.S.A. Soil δ13C was measured at (1) sites with long‐term forest or grassland vegetation and (2) sites with known histories where forest vegetation invaded grassland and where forest converted to grassland. The δ13C of soil under long‐term grassland was –24.1‰ at 0 to 2 cm depth and –23.4‰ at 2 to 10 cm and was enriched by 3.4‰ and 2.8‰ compared with soil under long‐term forest. In forests that invaded grasslands dominated byS. scoparium, soil δ13C decreased as C derived from trees replaced C fromS. scoparium. This decline occurred faster in surface soils and in the light soil organic matter fraction than in the mineral soil. In forests that converted to grasslands, soil δ13C increased and the rate of increase was similar in surface and mineral soil and in the different soil organic matter fractions. Rates of change indicated that soil δ13C could be used to detect changes in vegetation involving the presence or absence ofS. scopariumduring the last 150 years. Application of this model to a potential grassland restoration site on Martha's Vineyard where the landscape history was not known indicated that the site was previously unoccupied byS. scopariumduring this time. The δ13C of surface mineral soil can be useful for detecting the presence of historicS. scopariumgrasslands but only in the period well after European settlement of these coastal sand plain landscapes.
Increased expression of chemokines (MCP‐1, MIP‐1α, RANTES) after peripheral nerve transection
Authors: Taskinen Hanna‐Stiina , Röyttä Matias
Published: March 2003

Abstract  After nerve injury, recruitment of circulating macrophages into the endoneurium is essential for degeneration and subsequently for successful regeneration. However, the factors leading to macrophage recruitment are not known in detail. Chemokines are one of many possible factors influencing recruitment. In this study we wanted to examine, immunohistochemically, the expression of MCP‐1, MIP‐1α and RANTES from 6 hours up to 4 weeks after transection of rat sciatic nerve. An increased expression of MCP‐1 was noted already 6 hours after transection, mainly in Schwann cells. Later, the MCP‐1 positive staining was seen also in macrophages, fibroblast‐like cells and endothelial cells. An increased number of MIP‐1α positive cells could be noticed after 24 hours, the maximum expression in Schwann cells was noted at the 5‐day timepoint. Later, part of the positive cells appeared to be macrophages. RANTES was mainly expressed in inflammatory cells. Endothelial cells in the epi‐ and endoneurium showed positive staining for every chemokine studied after transection. The contralateral non‐operated nerves showed an increased number of positive cells for MCP‐1 and MIP‐1α. In the control nerves MCP‐1 and MIP‐1α positive cells were scattered throughout the endoneurium. This study shows that increased expression of chemokines takes place within endoneurium after peripheral nerve transection. Thus, it is probable that chemokines can take part in the recruitment of macrophages. It further shows that there is an increased expression of the studied chemokines in the non‐operated contralateral nerves. Even in normal conditions chemokines are needed, probably to keep resident macrophages within endoneurium.
Prosaposin‐derived peptides enhanced sprouting of sensory neurons in vitro and induced sprouting at motor endplates in vivo
Authors: Campana W. Marie , Mohiuddin L. , Misasi R. , O'brien J.S. , Calcutt N.A.
Published: March 2003

Abstract  Prosaposin exhibits neurotrophic factor properties that are localized to a 12‐amino acid sequence located in the amino terminal portion of the saposin C domain. Prosaptides are peptides derived from the neurotrophic portion of prosaposin; these have been previously reported to be bioactive in neuroblastoma cell lines in vitro. We report that prosaptides were also bioactive in explants of adult primary sensory neurons by dose‐dependently increasing both the number (3‐ to 4‐fold) and elongation of these neurites by 50%. Local injection of prosaptides into the gluteus muscle of adult mice also induced sprouting at the motor endplate. Our results indicate that prosaptides are potent neuritogenic factors for both sensory and motor neurons of adult peripheral nerve.
Local administration of vasoactive intestinal peptide after nerve transection accelerates early myelination and growth of regenerating axons
Authors: Zhang Qian‐Lin , Liu Jie , Lin Peng‐Xin , DeF. Webster Henry
Published: March 2003

Abstract  Our goal was to determine whether local injections of vasoactive intestinal peptide (VIP) promote early stages of regeneration after nerve transection. Sciatic nerves were transected bilaterally in 2 groups of 10 adult mice. In the first group, 15 μg (20 μL) of VIP were injected twice daily into the gap between transected ends of the right sciatic nerve for 7 days (4 mice) or 14 days (6 mice). The same number of mice in the second group received placebo injections (20 μL of 0.9% sterile saline) in the same site, twice daily, for the same periods. After 7 days, axon sizes, relationships with Schwann cells and degree of myelination were compared in electron micrographs of transversely sectioned distal ends of proximal stumps. Fourteen days after transection, light and electron microscopy were used to compare and measure axons and myelin sheaths in the transection gap, 2‐mm distal to the ends of proximal stumps. Distal ends of VIP‐treated proximal stumps contained larger axons 7 days after transection. More axons were in 1:1 relationships with Schwann cells and some of them were surrounded by thin myelin sheaths. In placebo‐treated proximal stumps, axons were smaller, few were in 1:1 relationships with Schwann cells and no myelin sheaths were observed. In VIP‐treated transection gaps, measurements 14 days after transection showed that larger axons were more numerous and their myelin sheaths were thicker. Our results suggest that in this nerve transection model, local administration of VIP promotes and accelerates early myelination and growth of regenerating axons.
Burst Discharge In Primary Sensory Neurons: Triggered By Subthreshold Oscillations, Maintained By Depolarizing Afterpotentials
Authors: Amir R , Michaelis M , Devor M.
Published: March 2003

Afferent discharge generated ectopically in the cell soma of dorsal root ganglion (DRG) neurons may play a role in normal sensation, and it contributes to paraesthesias and pain after nerve trauma. This activity is critically dependent on subthreshold membrane potential oscillations; oscillatory sinusoids that reach threshold trigger low‐frequency trains of intermittent spikes. Ectopic firing may also enter a high‐frequency bursting mode, however, particularly in the event of neuropathy. Bursting greatly amplifies the overall ectopic barrage. In the present report we show that subthreshold oscillations and burst discharge occur in vivo, as they do in vitro. We then show that although the first spike in each burst is triggered by an oscillatory sinusoid, firing within bursts is maintained by brief regenerative post‐spike depolarizing afterpotentials (DAPs). Numerical simulations were used to identify the cellular process underlying rebound DAPs, and hence the mechanism of the spike bursts. Finally, we show that slow ramp and hold (tonic) depolarizations of the sort that occur in DRG neurons during physiologically relevant events are capable of triggering sustained ectopic bursting, but only in cells with subthreshold oscillatory behavior. Oscillations and DAPs are an essential substrate of ectopic burst discharge. Therefore, any consideration of the ways in which cellular regulation of ion channel synthesis and trafficking implement normal sensation and, when disrupted, bring about neuropathic pain must take into account the effects of this regulation on oscillations and bursting.
Homozygous Defects In Lmna, Encoding Lamin A/C Nuclear‐Envelope Proteins, Cause Autosomal Recessive Axonal Neuropathy In Human (Charcot‐Marie‐Tooth Disorder Type 2) And Mouse
Authors: De Sandre‐Giovannoli A , Chaouch M , Kozlov S , Vallat JM , Tazir M , Kassouri N , Szepetowski P , Hammadouche T , Vandenberghe A , Stewart CL , Grid D , Levy N.
Published: March 2003

The Charcot‐Marie‐Tooth (CMT) disorders comprise a group of clinically and genetically heterogeneous hereditary motor and sensory neuropathies, which are mainly characterized by muscle weakness and wasting, foot deformities, and electrophysiological, as well as histological, changes. A subtype, CMT2, is defined by a slight or absent reduction of nerve‐conduction velocities together with the loss of large myelinated fibers and axonal degeneration. CMT2 phenotypes are also characterized by a large genetic heterogeneity, although only two genes‐NF‐L and KIF1Bbeta‐have been identified to date. Homozygosity mapping in inbred Algerian families with autosomal recessive CMT2 (AR‐CMT2) provided evidence of linkage to chromosome 1q21.2‐q21.3 in two families (Z(max) = 4.14). All patients shared a common homozygous ancestral haplotype that was suggestive of a founder mutation as the cause of the phenotype. A unique homozygous mutation in LMNA (which encodes lamin A/C, a component of the nuclear envelope) was identified in all affected members and in additional patients with CMT2 from a third, unrelated family. Ultrastructural explor‐ ation of sciatic nerves of LMNA null (i.e., −/−) mice was performed and revealed a strong reduction of axon density, axonal enlargement, and the presence of nonmyelinated axons, all of which were highly similar to the phenotypes of human peripheral axonopathies. The finding of site‐specific amino acid substitutions in limb‐girdle muscular dystrophy type 1B, autosomal dominant Emery‐Dreifuss muscular dystrophy, dilated cardiomyopathy type 1A, autosomal dominant partial lipodystrophy, and, now, AR‐CMT2 suggests the existence of distinct functional domains in lamin A/C that are essential for the maintenance and integrity of different cell lineages. To our knowledge, this report constitutes the first evidence of the recessive inheritance of a mutation that causes CMT2; additionally, we suggest that mutations in LMNA may also be the cause of the genetically overlapping disorder CMT2B1.
Response Characteristics Of Cutaneous Mechanoreceptors In Neuropathic Rats
Authors: Bulka A , Hao JX , Wiesenfeld‐Hallin Z.
Published: March 2003

The activity of single myelinated afferents was recorded from dorsal roots L4‐5 in normal Sprague‐Dawley rats and animals that developed mechanical hypersensitivity following ischemic injury to the sciatic nerve. The mechanical response properties and conduction velocity of afferents conducting through the injury site (about 50% of units) were similar to controls. However, the majority of afferents not conducting through the injury site exhibited ongoing activity. The results suggest that mechanical allodynia may be at least partly due to the central integration of activity arising from these two populations of afferents in neuropathic rats.
The Mitochondrial Genome And Human Mitochondrial Diseases
Authors: Sukernik RI , Derbeneva OA , Starikovskaya EB , Volodko NV , Mikhailovskaya IE , Bychkov IY , Lott M , Brown M , Wallace D.
Published: March 2003

To date, more than 100 point mutations and several hundreds of structural rearrangements of mitochondrial DNA (mtDNA) are known too be connected with characteristic neuromuscular and other mitochondrial syndromes varying from those causing death at the neonatal stage to diseases with late ages of onset. The immediate cause of mitochondrial disorders is a defective oxidative phosphorylation. Wide phenotypic variation and the heteroplasmy phenomenon, which some authors include in mutation load, are characteristic of human mitochondrial diseases. As the numbers of cases identified and pedigrees described increase, data on the genotype‐phenotype interaction and the structure and frequency of pathogenic and conditionally pathogenic mtDNA mutations in human populations are rapidly accumulated. The data on the genetics and epidemiology of mitochondrial diseases are not only important for differential diagnosis and genetic counseling. Since both neutral and mildly pathogenic mutations of mtDNA are progressively accumulated in maternal phyletic lines, molecular analysis of these mutations permits not only reconstruction of the genealogical tree of modern humans, but also estimation of the role that these mutations play in natural selection.
Subthreshold Oscillations Induced By Spinal Nerve Injury In Dissociated Muscle And Cutaneous Afferents Of Mouse DRG
Authors: Liu CN , Devor M , Waxman SG , Kocsis JD.
Published: March 2003

Whole cell patch‐clamp recordings were obtained from dissociated mouse lumbar dorsal root ganglion (DRG) neurons. Recordings were made from control neurons and neurons axotomized by transection of the corresponding spinal nerve 1‐2 days prior to dissociation. Medium to large muscle and cutaneous afferent neurons were identified by retrograde transport of True Blue or Fluoro‐Gold injected into the corresponding peripheral tissue. Action potentials were classified as non‐inflected spikes (A(0)) and inflected spikes (A(inf)). High‐frequency, low‐amplitude subthreshold membrane potential oscillations were observed in 8% of control A(0) neurons, but their incidence increased to 31% in the nerve injury group. Fifty percent of axotomized muscle afferent A(0) cells displayed oscillations, while 26% of axotomized cutaneous afferents exhibited oscillations. Lower‐frequency oscillations were also observed in a small fraction (4%) of A(inf) neurons on strong depolarization. Their numbers were increased after the nerve injury, but the difference was not statistically significant. The oscillations often triggered burst firing in distinct patterns of action potential activity. These results indicate that injury‐induced membrane oscillations of DRG neurons, previously observed in whole DRG of rats, are present in dissociated DRG neurons of the adult mouse. Moreover, these observations indicate that both muscle and cutaneous afferents in the A(beta) size range give rise to injury‐induced membrane oscillations, with muscle afferents being more prone to develop oscillations.
Identification of novel sequence variants in the neurofilament‐light gene in a Japanese population: analysis of Charcot‐Marie‐Tooth disease patients and normal individuals
Authors: Yoshihara Tsuyoshi , Yamamoto Masahiko , Hattori Naoki , Misu Ken‐ichiro , Mori Keiko , Koike Haruki , Sobue Gen
Published: March 2003

Abstract  Mutations of the neurofilament‐light (NEFL/NF‐L) gene were examined in 124 unrelated Japanese patients with Charcot‐Marie‐Tooth disease (CMT) without known gene mutations, and 248 normal Japanese individuals. A new method, which can detect basepair mismatches with RNase cleavage on agarose gel electrophoresis, coupled with DNA sequencing, identified 8 novel sequence variations in the NF‐L gene. In these sequence variants, 5 variants were polymorphisms, including 3 single nucleotide polymorphisms (SNPs), and 3 other missense mutations (Pro22Thr, Asn97Ser and Ala148Val) were found in the patients with CMT phenotype. The variant alleles in the NF‐L gene could influence the developing process of CMT phenotype and also might cause CMT phenotype.
CAN ELECTROPHYSIOLOGY DIFFERENTIATE POLYNEUROPATHY WITH ANTI‐MAG/SGPG ANTIBODIES FROM CHRONIC INFLAMMATORY DEMYELINATING POLYNEUROPATHY?
Authors: Capasso M , Torrieri F , Di Muzio A , De Angelis MV , Lugaresi A , Uncini A.
Published: March 2003

Objectives: Patients with polyneuropathy and antibodies to myelin‐associated glycoprotein (MAG) and sulphated glucuronyl paragloboside (SGPG) differ from chronic inflammatory demyelinating polyneuropathy (CIDP) because of a slower, progressive course, symmetrical and predominantly sensory involvement of legs, predominantly distal slowing of motor conductions, and poorer response to therapy. We studied whether a wide set of electrophysiologic parameters may differentiate these two neuropathies. Methods: We reviewed the electrophysiological studies of 10 patients with anti‐MAG/SGPG antibodies and 22 with CIDP examining: (1) motor conduction velocity and distal compound muscle action potential amplitude; (2) conduction block (CB) and temporal dispersion; (3) distal motor latency and terminal latency index (TLI); (4) F wave and proximal conduction time; and (5) sensory conduction and occurrence of abnormal median with normal sural sensory potential. Results: Anti‐MAG/SGPG neuropathies showed: (1) more severe involvement of peroneal nerves; (2) more frequent disproportionate distal slowing of motor conductions (TLI less than or equal to 0.25) and absent sural potential; and (3) no CB. However 3/22 CIDP patients also had at least two nerves with TLI 0.25 and no CB. Conclusions: Electrophysiologic findings suggest in anti‐MAG/SGPG neuropathy a length‐dependent process with a likely centripetal evolution. A disproportionate slowing of conduction in distal segments of motor nerves suggests the diagnosis of anti‐MAG/SGPG neuropathy, although it is not pathognomonic.
IS CARDIOVASCULAR DISEASE A RISK FACTOR IN THE DEVELOPMENT OF AXONAL POLYNEUROPATHY?
Authors: Teunissen LL , Franssen H , Wokke JHJ , Van Der Graaf Y , Linssen WHJP , Banga JD , Laman DM , Notermans NC
Published: March 2003

Objectives: To determine if cardiovascular disease may be a risk factor in the development of chronic idiopathic axonal polyneuropathy (CIAP). Methods: In this incidence case‐control study, the prevalence of cardiovascular disease and risk factors in 97 patients with CIAP (mean age 67.5 (SD 7.9) years) and the prevalence of neuropathic features in 97 patients with peripheral arterial disease (PAD) (mean age 67.1 (SD 7.3) years) were investigated. The results were compared with those for 96 age and sex matched controls without diagnosed PAD or polyneuropathy (mean age 67.5 (SD 9.1) years). In a randomly chosen subgroup of 23. patients with CIAP, 42 patients with PAD, and 48 controls, an electrodiagnostic investigation was performed. Results: Patients with CIAP more often had manifest cardiovascular disease and cardiovascular risk factors than controls (stroke 18% v 6% of patients, odds ratio (OR) 3.2 (95% confidence interval (0) 1.8 to 5.9); heart disease 29% v 15%, OR 2.4 (95% Cl 1.2 to 4.9); family history of cardiovascular disease 42% v 21%, OR 2.8 (95% Cl (1.5 to 5.2); hypertension 56% v 39%, OR 2.0 (95% Cl 1.1 to I I 3.6); hypercholesterolaemia 46% v 21%, OR 3.3 (95% Cl 1.5 to 7.3); current smoking 38% v 23%, OR 2.1 (95% Cl I. I to 3.9)). The prevalence of cardiovascular disease and cardiovascular risk factors was lower than in patients with PAD. Patients with PAD more often had polyneuropathy than controls (15% v 5%, OR 3.3 (95% Cl 1.1 to 10.0)). There was a trend towards lower nerve conduction velocities and lower amplitudes on electrodiagnostic investigation compared with controls. Conclusion: This study shows that cardiovascular disease and CIAP often coexist, and therefore cardiovascular disease may be a cofactor in the development of CIAP.
DEGRADATIVE DISEASE IN ULVA RIGIDA (CHLOROPHYCEAE) ASSOCIATED WITH ACROCHAETE GENICULATA (CHLOROPHYCEAE)
Authors: Del Campo Elena , García‐Reina Guillermo , Correa Juan A.
Published: March 2003

A destructive disease affecting tank‐cultivated Ulva rigida C. Agardh. was characterized by green spots, initially located at the base of the thalli, that spread through the host thallus and gradually caused perforations of the frond. The endophytic filamentous green alga Acrochaete geniculata (Gardner) O’Kelly was identified as the causative agent of the disease. The effects of this infection on the host varied from minor injuries to gross frond destruction. Advanced stages of infection resulted in frond wrinkling and severe tissue loss. These symptoms were caused by a primary compaction of the host cells due to a direct effect of the endophyte followed by secondary bacterial infections that became part of the degradative process initiated by the algal pathogen. Co‐cultivation of healthy and diseased fronds resulted in transfer of the infection within 2 weeks; however, attempts to infect the host in the laboratory with actively reproducing suspensions of the endophyte were unsuccessful.
CHARACTERIZATION OF A LYTIC VIRUS INFECTIOUS TO THE BLOOM‐FORMING MICROALGA AUREOCOCCUS ANOPHAGEFFERENS (PELAGOPHYCEAE)
Authors: Garry Ronald T. , Hearing Patrick , Cosper Elizabeth M.
Published: March 2003

Aureococcus anophagefferens Hargraves and Sieburth has caused recurring monospecific blooms in Long Island embayments since it was first described in 1985. It was termed the “brown tide,” due to the resulting water color, and has had a devastating effect on Long Island’s (New York) marine ecosystem. In 1992, a virus that was capable of causing lysis of A. anophagefferens was isolated and maintained in culture. We report on the further characterization of this virus, Aureococcus anophagefferens virus‐1 (AaV‐1), indicated by a buoyant density of 1.2776 g·mL−1 in a CsCl equilibrium gradient. Electron microscopy revealed a phage with a hexagonal head and tail similar to previously described phages. By using adenovirus for calibration, the virus was found to have a head 50—55 nm wide and a tail 70–75 nm long. The viral band was infectious to A. anophagefferens after dialysis. The virus was composed of at least 16 distinct polypeptides ranging in molecular weight from 20 to 230 kDa. The adsorption coefficient for the virus was 7.2 × 10−9 mL·min−1, and the burst size was calculated to be 9.4 viruses per A. anophagefferens cell at 20° C. Complete lysis of A. anophagefferens occurred with a titer as low as 893 viruses·mL−1, and the lower limit of infectivity was 93 viruses·mL−1. The virus lost its infectivity between 30° and 40° C. These results suggest that AaV‐1 is highly infectious and that the role of the virus in preventing or ending A. anophagefferens blooms needs further investigation.
GPA, A CALCIUM‐BINDING PROTEIN IN THE COCCOLITHOPHORID EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE)
Authors: Corstjens Paul L. A. M. , Van Der Kooij Annemieke , Linschooten Cornelis , Brouwers Geert‐Jan , Westbroek Peter , Jong Elisabeth W. de Vrind‐de
Published: March 2003

Intracellular polysaccharide fractions were isolated from calcifying B‐type cells of Emiliania huxleyi and separated by electrophoretic fractionation. In all fractions, the polysaccharide was immunologically related to the polysaccharide of (extracellular) B‐type coccoliths (CP‐B) and not to polysaccharides of A‐type coccoliths (CP‐A). Most polysaccharide fractions also contained protein material. The fraction with the largest proportion of protein was used to raise antibodies. The resulting antiserum, α‐BP, contained antibodies against both CP‐B‐ and protein‐epitopes. The antibodies specific for polysaccharide‐epitopes reacted with intracellular polysaccharide fractions of B‐type cells only. In contrast, the antibodies specific for protein‐epitopes reacted with the intracellular fractions of B‐type as well as A‐type cells. With immunolocalization, the presence of protein antigen in a layer surrounding both types of cells was demonstrated. A cDNA library of E. huxleyi was screened with α‐BP, and a gene called gpa was isolated. The open reading frame of gpa was found to encode a protein (GPA) of 36,608 D, containing, inter alia, 24% acidic residues (18% glutamic acid and 6% aspartic acid), 12% proline, and 23% alanine. GPA has two repeats, one containing a sequence resembling the Ca2+‐binding loop of EF‐hands. Overproduction of GPA in a prokaryotic system yielded a dimeric product capable of binding Ca2+. The possible role of GPA in the formation of coccoliths in E. huxleyi is discussed.
EXPERIMENTAL MESOCOSM STUDIES OF SALINITY EFFECTS ON THE BENTHIC ALGAL COMMUNITY OF A SALINE LAKE
Authors: Herbst David B. , Blinn Dean W.
Published: March 2003

As closed‐basin systems, saline lakes are prone to fluctuate in level and salinity with climate change and hydrologic alterations. Loss of many Great Basin lakes has resulted from the diversion of tributary streams for agricultural or municipal uses. At Mono Lake, an alkaline salt lake in eastern California, salinities have risen from 50 to 100 g·L−1 in just 50 years. Experimental mesocosms were established to simulate some of the potential ecological effects that could have accompanied this change. The influence of salinity on diatom diversity, taxonomic structure, and primary production was tested using mesocosms deployed at Mono Lake. Mesocosm tanks were 500 L in volume, 1 m square, and 0.5 m deep, with open tops covered by 1 mm mesh net. Five treatments (50, 75, 100, 125, and 150 g·L−1) with four replicates per treatment were used over a 2‐month period. The diatom‐dominated benthic algae were reduced both in standing crop (from 6 to <0.1 g·m−2) and diversity (from 30 to 12 taxa) with increased salinity, with most loss occurring in salinities ≥75 g·L−1. Photosynthetic oxygen production also was significantly lower at salinities ≥75 g·L−1. Diatom indicator taxa for these shifts included Denticula sp., Nitzschia frustulum, N. monoensis, N. communis, and Stephanodiscus oregonicus increasing in relative abundance in higher salinity treatments, accompanied by decreases in Achnanthes minutissima, Cymbella minuta, N. dissipata, and Rhoicosphenia abbreviata. Exhibiting dominance at moderate salinity levels (75 to 125 g·L−1) were Nitzschia frustulum, N. communis, N. palea, and Navicula crucialis. These latter species may be limited by both physiological stress at high salinity and grazing and competition at low salinity. The filamentous chlorophyte, Ctenocladus circinnatus, and cyanobacteria (Oscillatoria spp.) occurred only in salinity treatments from 50 to 100 g·L−1. Diversion of tributary stream flow and resulting salinity increases in this lake threaten sustained benthic primary production and algal species diversity relative to conditions prior to stream diversion. The 1994 decision of the California State Water Resources Control Board to return stream flows to Mono Lake will raise the lake level and reduce salinity to around 75 g·L−1 and is expected to increase the diversity and productivity of the benthic algae of this ecosystem.
PHYLOGENETIC ANALYSIS OF NINE SPECIES OF PROROCENTRUM (DINOPHYCEAE) INFERRED FROM 18S RIBOSOMAL DNA SEQUENCES, MORPHOLOGICAL COMPARISONS, AND DESCRIPTION OF PROROCENTRUM PANAMENSIS, SP. NOV.
Authors: Grzebyk Daniel , Sako Yoshihiko , Berland Brigitte
Published: March 2003

Sequences of 18S rRNA genes were obtained from eight species of Prorocentrum Ehrenberg: P. minimum (Pavillard) Schiller, P. mexicanum Osorio Tafall, P. emarginatum Fukuyo, P. lima (Ehrenberg) Dodge, P. arenarium Faust, P. maculosum Faust, P. concavum Fukuyo, and P. panamensis, sp. nov. Prorocentrum panamensis is a new species of tropical dinoflagellate isolated from a benthic coral reef on the Pacific coast of Panama and described here using scanning electron microscopy. Cells are heart shaped, 46–52 μm long and 43–46 μm wide. The valve surfaces are areolate except in the central area. Pores of 0.15 μm in diameter are scattered in areolae, mainly around the periphery of the cell. The right valve has a specific ovoid depression with numerous appressed pores; we named this structure the sieve‐like depression. The periflagellar area is nearly ovoid, located in a shallow depression, and almost equally set into both valves. It is unornamented (no apical expansion) but has numerous depressions in platelets. The flagellar and auxiliary pores are different in size and shape. The intercalary band is transversally striated. Phylogenetic relationships of gonyaulacoid, peridinioid, gymnodinioid, and prorocentroid dinoflagellates were inferred from complete 18S rDNA sequences. Two distinct phylogenetic analyses are presented for armored and unarmored Dinophyceae in an attempt to make the phylogenetic relationships between these different kinds of organisms clearer. The Prorocentrales appear to have a common origin, although two groups of Prorocentrum spp. are apparent. The first group includes benthic, symmetrical species (P. lima, P. arenarium, P. maculosum, and P. concavum). The second group contains planktonic and bentho‐planktonic species (P. micans Ehrenberg, P. minimum, P. mexicanum, and P. panamensis sp. nov.). Genetic distances between species within these two groups were high; however, the divergence between the two groups seems to have occurred late in dinoflagellate evolution. In addition, the bentho‐planktonic P. emarginatum appeared distantly related to both groups; however,its 18S rDNA sequence shares specific nucleotide substitutions with the two groups, suggesting an older origin of this species compared to the others. A morphological interpretation of this phylogenetic analysis is made on the basis of the specific structure of the periflagellar area. Finally, genetic data and morphological observations support the hypothesis that the genus Prorocentrum is rather heterogeneous; several species could be considered to constitute distinct genera.
INTRACELLULAR DIMETHYLSULFOXIDE (DMSO) IN UNICELLULAR MARINE ALGAE: SPECULATIONS ON ITS ORIGIN AND POSSIBLE BIOLOGICAL ROLE
Authors: Lee Peter A. , De Mora Stephen J.
Published: March 2003

Recent studies have established that aqueous phase concentrations of dimethylsulfoxide (DMSO) often exceed those of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS). Yet, in comparison to DMSP and DMS, DMSO remains a poorly understood component of the marine sulfur cycle. Much of what is known about the mechanisms for the formation and loss for DMSO is inferred from laboratory experiments, and no explanation exists to rationalize how a large pool of DMSO is maintained. One formation pathway that, until very recently, has been ignored involves the direct synthesis of DMSO by marine phytoplankton. This review examines some of the circumstantial evidence for DMSO in marine particulate material and recent reports containing preliminary data for particulate DMSO (DMSOp) in the marine environment. Drawing on literature from a range of scientific disciplines, speculations on the possible origins and biological functions of intracellular DMSO are also made. On the basis of its physicochemical properties, intracellular DMSO could have a potential role as a cryoprotectant, a specialist cryo‐osmoregulator in extreme environments, an intracellular electrolyte modifier, and a free‐radical scavenger. The review also assesses the impact of DMSOp at both the organism and the global level. Consideration is given to the marine biogeochemical cycling of sulfur and potential links to climate control.
SHORT‐TERM EFFECTS OF UVB RADIATION ON CHLOROPHYLL FLUORESCENCE, BIOMASS, PIGMENTS, AND CARBOHYDRATE FRACTIONS IN A BENTHIC DIATOM MAT
Authors: Underwood Graham J. C. , Nilsson Claes , Sundbäck Kristina , Wulff Angela
Published: March 2003

The effects on UVB radiation on a subtidal, cohesive‐sediment biofilm dominated by the diatom Gyrosigma balticum (Ehrenberg) Rabenhorst were investigated. Chlorophyll fluorescence parameters (Fv/Fm, φPSII), pigment concentrations, cell densities, and carbohydrate fractions were measured in four treatments (no UVBR, ambient UVBR, +7%, and +15% enhancement with UVBR). Enhanced UVBR was provided by a computer‐controlled system directly linked to natural diel UVBR levels. Increases in φPSII values in the UVBR‐enhanced treatments and a decrease in the steady‐state fluorescence yield (Fs) from the surface of the biofilms during the middle and latter part of daily exposure periods suggested that G. balticum responded to enhanced UVBR by migrating down into the sediment. Diatoms in the +15% UVBR treatment also had significantly higher concentrations of β‐carotene after 5 days of treatment. Although G. balticum responded to enhanced UVBR by migration and increased β‐carotene concentrations, significant reduction in maximum quantum yield of PSII (Fv/Fm) and in minimal fluorescence (Fo) and decreases in cell densities occurred after 5 days. Concentrations of different carbohydrate fractions (colloidal carbohydrate, glucan, exopolymers [EPS]) associated with diatom biomass and motility also decreased in the UVBR‐enhanced treatments. Short‐term responses (migration) to avoid UVBR appear insufficient to prevent longer‐term decreases in photosynthetic potential and biofilm carbohydrate concentration and biomass.
KINETICS OF AMMONIUM ASSIMILATION IN TWO SEAWEEDS, ENTEROMORPHA SP. (CHLOROPHYCEAE) AND OSMUNDARIA COLENSOI (RHODOPHYCEAE)
Authors: Taylor Michael W. , Rees T. Alwyn V.
Published: March 2003

The kinetics of ammonium assimilation were investigated in two seaweeds from northeastern New Zealand, Enteromorpha sp. (Chlorophyceae, Ulvales) and Osmundaria colensoi (Hook. f. et Harvey) R.E. Norris (Rhodophyceae, Ceramiales), with the use of a recently developed method for measuring assimilation. In contrast to ammonium uptake, which was nonsaturable, ammonium assimilation exhibited Michaelis–Menten kinetics in both species. Maximum rates of assimilation (Vmax) were 27 and 12 μmol·(g DW)−1·h−1 for Enteromorpha sp. and O. colensoi, respectively, with half‐saturation (Km) constants for assimilation of 18 and 41 μM. At environmentally relevant concentrations, assimilation accounted for all of the ammonium taken up by both species. The maximum rate of assimilation in Enteromorpha sp. resembled very closely that of the ammonium assimilatory enzyme, glutamine synthetase, when activities of the latter were measured in the presence of subsaturating substrate (glutamate and ATP) concentrations. Moreover, the initial rate of glutamine production (measured with HPLC) following ammonium enrichment was almost identical to the rates determined above. The rate of ammonium assimilation was therefore determined by three independent methods, two of which involve in vivo measurements, and it is suggested that the use of assimilation kinetics may be useful when examining the nutrient relations of seaweeds.
SEPTUM FORMATION IN THE DESMID XANTHIDIUM (CHLOROPHYTA): EFFECTS OF CYTOCHALASIN D AND LATRUNCULIN B SUGGEST THE INVOLVEMENT OF ACTIN MICROFILAMENTS
Authors: Höftberger Margit , Lütz‐Meindl Ursula
Published: March 2003

Septum formation and mitosis were investigated by light and electron microscopical techniques as well as through the completion of inhibitor experiments in the unicellular desmid Xanthidium armatum (Bréb.) Rabenh. In untreated cells, numerous endoplasmic reticulum (ER) cisternae permeated the mitotic apparatus and secretory vesicles, and ER formed a band in front of the linearly growing septum, indicating the predetermined direction of septum growth. Under the influence of cytochalasin D (CD), the vesicle/ER band lost its proper orientation, which led to a malformed septum wall; moreover, abnormal septum branches could potentially have developed. Whereas the septum of an untreated cell only grew at its edge, the CD‐induced branches (also with a vesicle/ER band in front) represented additional growing zones. These observations indicated that actin filaments were involved in establishing, maintaining, and orienting the “preforming” vesicle/ER band and, thus, the later septum. Latrunculin B (LB) had more severe effects on septum formation than did CD. Only small accumulations of septum material were found at the septum edge, and no aberrant growth of the septum occurred in LB‐treated as in CD‐treated cells. This could be explained by the more rapid disturbance of all actin‐driven processes after LB treatment, which was assumed, because even low concentrations of the drug rapidly inhibited cytoplasmic streaming.
KARYOGAMY BLOCK BY HEAT STRESS IN THE FERTILIZATION OF BROWN ALGAE
Authors: Nagasato Chikako , Motomura Taizo , Ichimura Terunobu
Published: March 2003

Karyogamy was inhibited by heat stress in zygotes of Scytosiphon lomentaria (Lyngbye) Link (isogamy), Cutleria cylindrica Okamura (anisogamy), and Fucus distichus subsp. evanescens (C. Agardh) Powell (oogamy). Although high temperatures did not inhibit migration of the male and female nuclei, nuclear envelope fusion was blocked. The ultrastructural stage at which karyogamy was inhibited varied among these species. In S. lomentaria, the outer membranes fused with each other, but the inner membranes did not fuse. Partial fusion of the nuclear envelope occurred in C. cylindrica. In F. distichus, the block of karyogamy at high temperature was incomplete, and nuclear fusion proceeded gradually. The block to karyogamy in S. lomentaria zygotes was reversible, and karyogamy proceeded when zygotes were transferred from 22° to 14° C. Experiments using inhibitors suggested that proteins that might be formed de novo after fertilization do not participate in karyogamy or its inhibition at either 14° or 22° C.
Validation of bysmatrum arenicola horiguchi et pienaar, sp. nov. (dinophyceae)(Note)
Authors: Horiguchi Takeo , Pienaar Richard N.
Published: March 2003

Validation here of the name Bysmatrum arenicola Horiguchi et Pienaar sp. nov. rather than Scrippsiella arenicola for this sand‐dwelling dinoflagellate from South Africa also corrects the inadvertently invalid basionym publication.
Hypersalinity enhances the production of extracellular polymeric substance (eps) in the texas brown tide alga, aureoumbra lagunensis (PELAGOPHYCEAE)
Authors: Liu Hongbin , Buskey Edward J.
Published: March 2003

Laboratory experiments with batch cultures showed that the Texas brown tide alga, Aureoumbra lagunensis Stockwell, DeYoe, Hargraves et Johnson, produced a large amount of extracellular polymeric substance (EPS) that formed an extracellular polysaccharide mucus layer. Both dissolved and particulate carbohydrate and EPS concentrations increased as A. lagunensis cultures progressed from exponential growth phase, through stationary phase, to declining phase. Particulate carbohydrate and EPS concentrations per cell were more than three times higher during the declining phase than that in exponential growth phase, reflecting a large increase in the EPS mucus layer. The amounts of carbohydrate and EPS produced by A. lagunensis were significantly higher under hypersaline conditions. The thicker EPS mucus layer surrounding A. lagunensis cells under hypersaline conditions might be a protective adaptation that permits it to bloom under hypersaline conditions that most other phytoplankton cannot survive. This could be one of the reasons why the Texas brown tide persisted in the Laguna Madre, an often hypersaline coastal lagoon, for 7 years.
Xanthogenate nucleic acid isolation from cultured and environmental cyanobacteria
Authors: Tillett Daniel , Neilan Brett A.
Published: March 2003

The isolation of high‐quality nucleic acids from cyanobacterial strains, in particular environmental isolates, has proven far from trivial. We present novel techniques for the extraction of high molecular weight DNA and RNA from a range of cultured and environmental cyanobacteria, including stains belonging to the genera Microcystis, Lyngbya, Pseudanabaena, Aphanizomenon, Nodularia, Anabaena, and Nostoc, based on the use of the nontoxic polysaccharide solubilizing compound xanthogenate. These methods are rapid, require no enzymatic or mechanical cell disruption, and have been used to isolate both DNA and RNA free of enzyme inhibitors or nucleases. In addition, these procedures have proven critical in the molecular analysis of bloom‐forming and other environmental cyanobacterial isolates. Finally, these techniques are of general microbiological utility for a diverse range of noncyanobacterial microorganisms, including Gram‐positive and Gram‐negative bacteria and the Archea.
CHARACTERIZATION OF GYMNODINIUM MIKIMOTOI (DINOPHYCEAE) NUCLEI AND IDENTIFICATION OF THE MAJOR HISTONE‐LIKE PROTEIN, HGm
Authors: Wargo Matthew J. , Rizzo Peter J.
Published: March 2003

A simple and rapid method for isolation of nuclei from Gymnodinium mikimotoi Miyake et Kominami ex Oda is described along with chemical characterization of the nuclei. The isolated nuclei were completely free of whole cells, 99.96% free of cytoplasmic contamination, and were collected with a yield of 40% from harvested whole cells. Each nucleus contained 47 pg of DNA and the ratio of DNA to acid‐soluble proteins to acid‐insoluble proteins was 1:0.25:1.21, respectively. SDS electrophoresis of acid‐extracted proteins showed one histone‐like protein, which we termed HGm, with an apparent molecular mass of 12 kDa. V8 protease digestion analysis of HGm, the histone‐like protein from Crypthecodinium cohnii (HCc), and two histone‐like proteins from Gymnodinium dorsum, showed that the HGm digestion pattern was more similar to that of HCc than to that of either of the G. dorsum histone‐like proteins.