bluuebunny/crossref_metadata_2025 huggingface dataset:
Sorbitol Accumulation In Ascorbic Acid Treated Schwann Cells Cultured In High Glucose Medium
Authors: Suzuki T , Yashima S , Taniko K , Mizuno K , Suzuki T , Yabe‐Nishimura C.
Published: March 2003

Unless the expression of aldose reductase (AR) was upregulated, sorbitol was not accumulated under high glucose conditions in Schwann cells isolated from adult rat sciatic nerves (1). In the peripheral nerve, however, Schwann cells of both myelinated and un‐myelinated fibers are ensheathed by the basement membrane. To evaluate the effect of basement membrane formation on sorbitol accumulation, we examined the sorbitol levels in Schwann cells pre‐cultured for 12 days in the medium containing 50μg/ml ascorbic acid and 20nM progesterone that elicit basement membrane synthesis on the plate coated with extracellular matrix. In the cells cultured in ascorbic acid containing medium, type IV collagen, one of the basement membrane components, was detected. When these cells were incubated with 50mM glucose for 6 days, a significant level of sorbitol accumulation was observed without any change in the activity of AR and SDH. Fidarestat, an inhibitor of AR, decreased the sorbitol levels in a dose‐dependent manner. Increased fructose levels in these cells were simultaneously suppressed by the addition of fidarestat. Our findings therefore suggest that accumulation of sorbitol in Schwann cells takes place under diabetic conditions, only when cells are ensheathed by the basement membrane.

(1) Suzuki, T., et al. (1999). J. Neurosci. Res., 57, 495‐503.
Elevation Of Electric Gustatory Threshold In Type 2 Diabetic Patients With Neuropathy
Authors: Sakamoto Y , Akaboshi M , Mokuda O.
Published: March 2003

To specify the diabetic complications related to taste function in type 2 diabetes mellitus, electrogustometry was performed in 49 patients and 48 normal subjects. The results showed that the electric gustatory threshold (EGT) rose with aging. The EGT in normal subjects was, on average, not changed compared to the diabetics without complications (6.29 dB vs 6.3 dB), but the EGT was significantly higher in diabetic patients with neuropathy compared to the normal (13.3 dB vs 6.29 dB p < 0.05). The EGT was significantly higher in diabetic patients with both neuropathy and retinopathy (18.1 dB vs 6.29 p < 0.05). In the patients with chronic renal failure due to chronic glomerulonephritis treated with hemodialysis, the EGT was not changed compared to the normal (3.8 dB vs 6.29 dB), but the EGT in the diabetic renal failure treated with hemodialysis was much higher compared to the CGN patients (19.1 dB vs 3.0 dB). Thus, the electric gustatory threshold is a sensitive indicator of diabetic complications.
Motor Axonal Neuropathy During Treatment With Simvastatin
Authors: Ceschin V , Gragnani F , Morino S , Pennisi ME , Bucci E , Antonini G.
Published: March 2003

Simvastatin is a cholesterol‐lowering drug that acts by inhibiting hydroxymethylglutaryl coenzyme A (HMG‐CoA) reductase, the rate‐limiting enzyme in cholesterol synthesis. Abnormal laboratory findings include transient increases in serum creatine kinase (CK) due to a myopathic syndrome. Rarely, neurological side effects include axonal sensory‐motor peripheral neuropathy, characterized in some cases by a prevalent motor involvement accompanied by subclinical sensory damage. We report a case of purely motor axonal neuropathy associated with simvastatin. A 72‐year‐old woman, after five years of treatment with simvastatin, developed progressive weakness, cramps and fasciculations mainly involving proximal muscles in the lower limbs, though without sensory symptoms or signs. Deep reflexes were lost in the lower limbs. There was no sign of upper motor‐neuron involvement. CK was elevated (up to 2000 U/l). EMG showed marked neurogenic damage with fibrillations and fasciculations in the lower limbs. ENG showed motor fiber loss within the lower limb nerves without involvement of sensory fibers. CSF examination was normal. Deltoid muscle biopsy showed neurogenic changes and some ragged‐red fibers. One year after simvastatin withdrawal the patient's state of weakness improved and the cramps resolved. The CK level dropped to 700 U/l.
Poems Syndrome With Vasa Nervorum Vasculitis: A Case Report
Authors: Bruno R , Manganelli F , Nolano M , Barbieri F , Santoro L.
Published: March 2003

POEMS syndrome is a rare multisystemic disorder which includes polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes. The disease is more frequent in Japan where it is known as Crow‐Fukase syndrome. Although pathogenesis remains unclear, there is evidence that vasculopathy may have an important role. We report the case of a 45‐year‐old woman with a 2 year history of progressive and symmetric distal paresthesias, muscle weakness and atrophy that rendered her severely quadriparetic and bedridden. Electrophysiological study showed a severe axonal and demyelinating polyneuropathy with evidence of active denervation. Additional investigation disclosed IgG‐lambda monoclonal serum protein, skin hyperpigmentation, diabetes mellitus, increased cerebrospinal fluid protein, organomegaly (liver and kidney) and multiple osteoclastic lesions involving the second and third lumbar vertebra, the hip, the femur and the tibia. Biopsy of the osteoclastic vertebra revealed a marked lymphoplasmocytic infiltrate. The sural nerve biopsy showed a complete loss of the large myelinated fibres and a moderate reduction of the small ones with signs of Wallerian‐like degeneration. Furthermore, epineurial small vessel destructuration and enlargement and a perivascular infiltration of inflammatory cells in one of them was present, compatible with a previous vascular inflammatory disease. In accordance with this picture, immunohistochemical study of glabrous skin double marked for neural and vascular structures showed a marked loss of Meissner corpuscles and myelinated nerve fibers with evident anomalies of blood vessels. Blood examination did not show cryoglobulin, anti‐nucleus (ANA) or anti‐double strand DNA antibodies. The vascular abnormalities in nerve biopsy or in other tissue biopsies are not frequently described in POEMS syndrome. Our case, as reported by other authors, suggests that microangiopathy could be responsible for peripheral neuropathy and for systemic manifestations of POEMS syndrome.
Taurine counteracts oxidative stress and nerve growth factor deficit in early experimental diabetic neuropathy
Authors: Obrosova IG , Fathallah L , Stevens MJ
Published: March 2003

Oxidative stress has a key role in the pathogenesis of diabetic complications. We have previously reported that taurine (T), which is known to counteract oxidative stress in tissues (lens, kidney, retina) of diabetic rats, attenuates nerve blood flow and conduction deficits in early experimental diabetic neuropathy (EDN). The purpose of this study was to evaluate whether dietary T supplementation counteracts oxidative stress and the nerve growth factor (NGF) deficit in the diabetic peripheral nerve. The experiments were performed in control rats and streptozotocin‐diabetic rats fed standard or 1% T‐supplemented diets for 6 weeks. All measurements were performed in the sciatic nerve. Malondialdehyde (MDA) plus 4‐hydroxyalkenals (4‐HA) were quantified with N‐methyl‐2‐phenylindole. GSH, GSSG, dehydroascorbate (DHAA), and ascorbate (AA) were assayed spectrofluorometrically, T by reverse‐phase HPLC, and NGF by ELISA. MDA plus 4‐HA concentration (mean +/− SEM) was increased in diabetic rats (0.127 +/−0.006 vs 0.053 +/−0.003 mu mol/g in controls, P<0.01), and this increase was partially prevented by T (0.0960.004, P<0.01 vs untreated diabetic group). GSH levels were similarly decreased in diabetic rats treated with or without taurine vs controls. GSSG levels were similar in control and diabetic rats but were lower in diabetic rats treated with T (P<0.05 vs controls). AA levels were decreased in diabetic rats (0.133+0.015 vs 0.219 +/−0.023 mu mol/g in controls, P<0.05), and this deficit was prevented by T. DHAA/AA ratio was increased in diabetic rats vs controls (P<0.05), and this increase was prevented by T. T levels were decreased in diabetic rats (2.7 +/−0.16 vs 3.8 +/−0.1 mu mol/g in controls, P<0.05) and were repleted by T supplementation (4.20.3). NGF levels were decreased in diabetic rats (2.35 +/−0.20 vs 3.57 +/−0.20 ng/g in controls, P<0.01), and this decrease was attenuated by T treatment (3.160.28, P<0.05 vs diabetic group). In conclusion, T counteracts oxidative stress and the NGF deficit in early EDN. Antioxidant effects of T in peripheral nerve are, at least in part, mediated through the ascorbate system of antioxidative defense. The findings are consistent with the important role for oxidative stress in impaired neurotrophic support in EDN.
Functional interactions between tumor and peripheral nerve: changes in excitability and morphology of primary afferent fibers in a murine model of cancer pain
Authors: Cain DM , Wacnik PW , Turner M , Wendelschafer‐Crabb G , Kennedy WR , Wilcox GL , Simone DA
Published: March 2003

We used a murine model to investigate functional interactions between tumors and peripheral nerves that may contribute to pain associated with cancer. Implantation of fibrosarcoma cells in and around the calcaneus bone produced mechanical hyperalgesia of the ipsilateral paw. Electrophysiological recordings from primary afferent fibers in control and hyperalgesic mice with tumor revealed the development of spontaneous activity (0.2‐3.4 Hz) in 34% of cutaneous C‐fibers adjacent to the tumor (9‐17 d after implantation). C‐fibers in tumor‐bearing mice exhibited a mean decrease in heat threshold of 3.5 +/− 0.10 °C. We also examined innervation of the skin overlying the tumor. Epidermal nerve fibers (ENFs) were immunostained for protein gene product 9.5, imaged using confocal microscopy, and analyzed in terms of number of fibers per millimeter of epidermal length and branching (number of nodes per fiber). Divergent morphological changes were linked to tumor progression. Although branching of ENFs increased significantly relative to control values, in later stages (16‐24 d after implantation) of tumor growth a sharp decrease in the number of ENFs was observed. This decay of epidermal innervation of skin over the tumor coincided temporally with gradual loss of electrophysiological activity in tumor‐bearing mice. The development of spontaneous activity and sensitization to heat in C‐fibers and increased innervation of cutaneous structures within the first 2 weeks of tumor growth suggest activation and sensitization of a proportion of C‐fibers. The decrease in the number of ENFs observed in later stages of tumor development implicates neuropathic involvement in this model of cancer pain.
CONTACT‐DEPENDENT DEMYELINATION BY MYCOBACTERIUM LEPRAE IN THE ABSENCE OF IMMUNE CELLS
Authors: Rambukkana A , Zanazzi G , Tapinos N , Salzer JL
Published: March 2003

Demyelination results in severe disability in many neurodegenerative diseases and nervous system infections, and it is typically mediated by inflammatory responses. Mycobacterium leprae, the causative organism of leprosy, induced rapid demyelination by a contact‐dependent mechanism in the absence of immune cells in an in vitro nerve tissue culture model and in Rag1‐knockout (Rag1(−/−)) mice, which tack mature B and T lymphocytes. Myelinated Schwann cells were resistant to M. leprae invasion but undergo demyelination upon bacterial attachment, whereas nonmyelinated Schwann cells harbor intracellular M. leprae in large numbers. During M. leprae‐induced demyelination, Schwann cells proliferate significantly both in vitro and in vivo and generate a more nonmyelinated phenotype, thereby securing the intracellular niche for M. leprae.
CORTICOSPINAL TRACT INVOLVEMENT IN A VARIANT OF GUILLAIN‐BARRÉ SYNDROME
Authors: Oshima Y , Mitsui T , Endo I , Umaki Y , Matsumoto T.
Published: March 2003

To determine the involvement of the corticospinal tract in Guillain‐Barré syndrome (GBS), we examined central motor conduction in patients with GBS‐like symptoms and hyperreflexia using a magnetic stimulation technique. The subjects were 3 patients who exhibited ascending muscle weakness 2–4 weeks after preceding infections. Deep tendon reflexes were exaggerated in all four limbs of the 3 patients. The results of cerebrospinal fluid examinations revealed protein elevation without pleocytosis. The serum anti‐GM(1) antibody titer was elevated in 2 patients. The results of nerve conduction study revealed axonal motor neuropathy and normal F‐wave conduction. Central motor conduction time (CMCT) in patients with hyperreflexia was significantly delayed compared to that in patients with GBS and areflexia (p < 0.001), and the delayed CMCTs were significantly improved in the recovery periods (p < 0.001). Although hyperreflexia is a controversial symptom in patients with GBS, these findings indicate that there is functional corticospinal tract involvement in patients with a GBS variant.
PERIPHERAL VASCULAR AND NERVE FUNCTION ASSOCIATED WITH LOWER LIMB AMPUTATION IN PEOPLE WITH AND WITHOUT DIABETES
Authors: Carrington AL , Abbott CA , Griffiths J , Jackson N , Johnson SR , Kulkarni J , Van Ross ERE , Boulton AJM.
Published: March 2003

Multiple factors, including peripheral vascular disease and neuropathy, contribute to the development and perpetuation of complications of the lower extremities in diabetes. The main aim of the present study was to assess the peripheral vascular and nerve status of diabetic and non‐diabetic subjects that had undergone lower limb amputation. Various non‐invasive tests of peripheral vascular and nerve function were carried out on subjects who had undergone unilateral lower limb amputation and were now attending a Rehabilitation Centre. The control group (n = 23), the diabetic amputee group (n = 64) and the non‐diabetic amputee group (n = 32) were age‐matched. Only the diabetic amputee group had evidence of medial arterial calcification. Transcutaneous oxygen levels were significantly lower in the diabetic amputee group (median 43 mmHg; interquartile range 33–49 mmHg) than in the control (59; 56–74 mmHg) and non‐diabetic amputee (57; 43–65 mmHg) groups (control compared with diabetic amputee group, P < 0.001; diabetic amputee compared with non‐diabetic amputee group, P < 0.01). The same trend was found for carbon dioxide levels in the skin [mmHg: diabetic amputees, 25 (21–37); controls, 38 (32–42); non‐diabetic amputee, 34 (31–39)] (control compared with diabetic amputee, P < 0.01; diabetic amputee compared with non‐diabetic amputee, P < 0.05). Vibration and pressure perception measurements (which assess A beta nerve fibre function) showed that both the diabetic amputee and non‐diabetic amputee subjects had significantly greater impairment than the controls. However, measures of A alpha and C nerve fibre function were abnormal only in the diabetic amputee group. Thus the peripheral vascular and nerve functions of age‐matched diabetic and non‐diabetic subjects having undergone lower limb amputation show specific differences, with non‐diabetic amputees exhibiting signs of neuropathy. This indicates that factors characteristic of diabetes (such as hyperglycaemia and non‐enzymic glycation) are associated with calcification, lower oxygen and carbon dioxide levels in the skin, and abnormal A alpha and C nerve fibre function.
STATUS OF CURRENT CLINICAL TRIALS IN DIABETIC POLYNEUROPATHY
Authors: Bril V.
Published: March 2003

Peripheral polyneuropathy is the most frequent complication of diabetic mellitus. In spite of many clinical trials of different specific interventions for diabetic polyneuropathy, intensive glycemic control remains the only effective specific therapy currently available for this troublesome complication. This systematic overview reports the status of current clinical trials in diabetic polyneuropathy with an emphasis on those interventions directed towards specific pathophysiological derangements. A discussion of clinical trials of agents directed towards relieving painful symptoms of diabetic polyneuropathy concludes this overview.
CHEMICAL DEFENSE AGAINST HERBIVORY IN THE ANTARCTIC MARINE MACROALGAE IRIDAEA CORDATA AND PHYLLOPHORA ANTARCTICA (RHODOPHYCEAE)
Authors: Amsler Charles D. , McClintock James B. , Baker Bill J.
Published: March 2003

Iridaea cordata (Turner) Bory and Phyllophora antarctica A. et E. S. Gepp (Gigartinales, Rhodophyceae) are common in many high‐latitude, shallow benthic marine communities in Antarctica, but previous observations have indicated little or no exploitation by potential herbivores. We have measured retention of test disks over the mouths of the common Antarctic sea urchin Sterechinus neumayeri Meissner, and we have used this assay to examine potential chemical defenses in I. cordata and P. antarctica. Thallus disks of both macroalgal species were retained by the urchins for significantly shorter times than inert filter paper disks and much shorter times than paper disks with a feeding stimulant. Both nonpolar and polar extracts of each macroalgal species added to disks with a feeding stimulant significantly decreased retention times relative to controls. These results support the hypothesis that chemical defenses in I. cordata and P. antarctica play a role in deterring potential herbivores.
POLYPHYLY OF TETRASPORALEAN GREEN ALGAE INFERRED FROM NUCLEAR SMALL‐SUBUNIT RIBOSOMAL DNA
Authors: Booton Gregory C. , Floyd Gary L. , Fuerst Paul A.
Published: March 2003

Ultrastructural studies of tetrasporalean green algae have suggested the order is polyphyletic. These features, including the absolute orientation of the flagellar apparatus and the bi‐ versus quadriflagellated motile cell morphology, suggest that Chaetopeltis as well as a number of others, may be ancestral to a group that includes Tetraspora. In this study, we examine the phylogenetic relationships of selected tetrasporalean taxa based on analysis of 18S ribosomal RNA gene sequences. Results show that the tetrasporalean taxa are polyphyletic. Biflagellated genera group with biflagellated volvocalean taxa, whereas the quadriflagellated species compose a distinct monophyletic clade not closely related to the biflagellated taxa. In addition, tetrasporalean taxa group with other chlorophycean algal species with similar flagellar apparatus absolute orientation, but the quadriflagellated Tetrasporales do not appear to be ancestral to the entire Chlorophyceae. These results are concordant with previous conclusions drawn from ultrastructural data and further confirm the utility of (small‐subunit) ribosomal RNA gene sequences to discern green algal evolutionary relationships.
DIFFERENT RESPONSE MECHANISMS OF TWO PLANKTONIC DESMID SPECIES (CHLOROPHYCEAE) TO A SINGLE SATURATING ADDITION OF PHOSPHATE
Authors: Spijkerman Elly , Coesel Peter F. M.
Published: March 2003

Two planktonic algal species, Staurastrum chaetoceras (Schr.) G. M. Smith and Cosmarium abbreviatum Rac. var. planctonicum W. et G. S. West, from trophically different alkaline lakes, were compared in their response to a single saturating addition of phosphate (P) in a P‐limited growth situation. Storage abilities were determined using the luxury coefficient R = Qmax/Q0. Maximum cellular P quotas differed, depending on whether cells were harvested during exponential growth at μmax (Qmax, R being 26.7 and 9.1 for C. abbreviatum and S. chaetoceras, respectively) or harvested after a saturating pulse at P‐limited growth conditions (Q′max, R being 53.5 and 20.2 for C. abbreviatum and S. chaetoceras, respectively). At stringent P‐limited conditions, maximum initial uptake rates were higher in S. chaetoceras than in C. abbreviatum (0.094 and 0.073 pmol P·cell−1·h−1, respectively), but long‐term (net) uptake rates (over ∼20 min) were higher in C. abbreviatum than in S. chaetoceras (0.048 and 0.019 pmol P·cell−1·h−1, respectively). Before growth resumed after the onset of a large P addition (150 μmol·L−1), a lag phase was observed for both species. This period lasted 2–3 days for S. chaetoceras and 3–4 days for C. abbreviatum, corresponding with the time to reach Q′max. Subsequent growth rates (over ∼10 days) were 0.010 h−1 and 0.006 h−1 for S. chaetoceras and C. abbreviatum, respectively, being only 20%–30% of maximum growth rates. In conclusion, S. chaetoceras, with a relatively high initial P‐uptake rate, short lag phase, and high initial growth rate, is well adapted to a P pulse of short duration. Conversely, C. abbreviatum, with a high long‐term uptake rate and high storage capacity, appears competitively superior when exposed to an infrequent but lasting pulse. These characteristics provide information about possible strategies of algal species to profit from temporarily high P concentrations.
EFFECTS OF IRON AND LIGHT STRESS ON THE BIOCHEMICAL COMPOSITION OF ANTARCTIC PHAEOCYSTIS SP. (PRYMNESIOPHYCEAE). II. PIGMENT COMPOSITION
Authors: van Leeuwe Maria A. , Stefels Jacqueline
Published: March 2003

A strain of Phaeocystis sp., isolated in the Southern Ocean, was cultured under iron‐ and light‐limited conditions. The cellular content of chlorophyll a and accessory light‐harvesting (LH) pigments increased under low light intensities. Iron limitation resulted in a decrease of all light‐harvesting pigments. However, this decrease was greatly compensated for by a decrease in cell volume. Cellular concentrations of the LH pigments were similar for both iron‐replete and iron‐deplete cells. Concentrations of chlorophyll a were affected only under low light conditions, wherein concentrations were suppressed by iron limitation. Ratios of the LH pigments to chlorophyll a were highest for iron‐deplete cells under both light conditions. The photoprotective cycle of diato/diadinoxanthin was activated under high light conditions, and enhanced by iron stress. The ratio of diatoxanthin to diadinoxanthin was highest under high light, low iron conditions.  Iron limitation induced synthesis of 19′‐hexanoyloxyfucoxanthin and 19′‐butanoyloxyfucoxanthin at the cost of fucoxanthin. Fucoxanthin formed the main carotenoid in iron‐replete Phaeocystis cells, whereas for iron‐deplete cells 19′‐hexanoyloxyfucoxanthin was found to be the main carotenoid. This shift in carotenoid composition is of importance in view of the marker function of both pigments, especially in areas where Phaeocystis sp. and diatoms occur simultaneously. A hypothesis is presented to explain the transformation of fucoxanthin into 19′‐hexanoyloxyfucoxanthin and 19′‐butanoyloxyfucoxanthin, referring to their roles as a light‐harvesting pigment.
INTRASPECIFIC TRANSFER OF HERBICIDE RESISTANCE IN THE RED MICROALGA PORPHYRIDIUM SP. (RHODOPHYCEAE) VIA PROTOPLAST FUSION
Authors: Sivan Alex , (Malis) Arad Shoshana
Published: March 2003

Stable progeny doubly resistant to the herbicides sulfometuron methyl (SMM) and diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] (DCMU) were obtained at a frequency of 2% on fusion of protoplasts derived from mutants of Porphyridium sp. (UTEX 637) that were resistant only to SMM (strain SMR) or DCMU (strain DC‐2). In the presence of both herbicides, only the fusion progeny could grow; both parental mutants were inhibited. In the absence of SMM, the activity of acetohydroxy acid synthase (AHAS) in the wild‐type strain was similar to that in DC‐2, exceeding that of SMR by up to 4.5‐fold. AHAS activities of all fusion progeny were lower than those of the wild‐type strain and DC‐2 but higher than that of SMR. In the presence of SMM, AHAS activities of all tested fusion progeny ranged between those of the two parental mutants. This result indicates that both types of AHAS, the type resistant to SMM and the sensitive type, originating from SMR and DC‐2, respectively, were expressed in the fusion progeny. In the presence of DCMU, the photosynthetic activity of SMR was completely inhibited, whereas that of DC‐2 was unaffected. The photosynthetic activity of the fusion progeny in the presence of DCMU was slightly lower than that of DC‐2. Both the cell volume and the DNA content of the fusion progeny were similar to those of the parents. However, the genetic nature of the fusion products has not yet been elucidated. To the best of our knowledge, this is the first report on transfer of herbicide resistance via protoplast fusion in algae.
PHYLOGENETIC ANALYSIS AND GENOME SIZE OF OSTREOCOCCUS TAURI (CHLOROPHYTA, PRASINOPHYCEAE)
Authors: Courties Claude , Perasso Roland , Chrétiennot‐Dinet Marie‐Josèphe , Gouy Manolo , Guillou Laure , Troussellier Marc
Published: March 2003

Ostreococcus tauri Courties et Chrétiennot‐Dinet is the smallest described autotrophic eukaryote dominating the phytoplanktonic assemblage of the marine Mediterranean Thau lagoon (France). Its taxonomic position was partly elucidated from ultrastructure and high‐pressure liquid chromatography (HLPC) pigment analysis. The sequence analysis of the 18S rDNA gene of O. tauri measured here is available in EMBL Nucleotide Sequence Database (accession number: Y15814) and allowed to clarify its phylogenetic position. O. tauri belongs to the Prasinophyceae and appears very close to Mantoniella, a typical scaly Prasinophyceae, morphologically very different from the naked and coccoid Ostreococcus. An electrophoretic analysis of O. tauri shows that the nucleus contains 10.20 mbp. This small genome, fragmented into 14 chromosomes ranging in size from 300 to 1500 kbp, confirms the minimalist characteristics of Ostreococcus tauri.
MORPHOLOGY AND SYSTEMATICS OF RHODOCALLIS ELEGANS, RHODOCALLIDEAE, TRIB. NOV. (CERAMIACEAE, RHODOPHYTA), FROM SOUTHEASTERN AUSTRALIA
Authors: Hommersand Max H. , Wilson Sarah M. , Kraft Gerald T.
Published: March 2003

Recent collections of Rhodocallis elegans Kützing from southeastern Australia have permitted detailed observations of vegetative and reproductive structures that reveal features not exhibited by any existing tribe of Ceramiaceae. As a consequence, we establish the new tribe Rhodocallideae based on the unispecific genus Rhodocallis. Defining characters include: 1) four periaxial cells cut off in an alternating (rhodomelaceous) sequence; 2) determinate branchlets of two types: a) persistent lateral branchlets produced from the first‐formed periaxial cells, and b) deciduous transverse branchlets produced from the second and third periaxial cells, with cortical filaments issuing from all four periaxial cells; 3) first‐ and second‐order determinate branchlets terminated by thick‐walled spines; 4) indeterminate branches formed at the tips of directly converted determinate branchlets; 5) axial cells of indeterminate branches heavily corticated by a cylinder of descending rhizoidal filaments; 6) spermatangial parent cells borne directly on unmodified outer cortical cells; 7) carpogonial branches borne in series on second and third periaxial cells of modified indeterminate axes; 8) procarps lacking sterile‐cell groups; 9) a single derivative of the zygote nucleus transferred from the carpogonium to the auxiliary cell directly through a tube rather than by means of a connecting cell; 10) gonimoblasts surrounded by a network of rhizoidal filaments through which the gonimolobes protrude, the carposporophyte subtended by an investment of determinate branchlets; and 11) tetrasporangia tetrahedrally divided, borne on surface cortical cells of special determinate branchlets and protruding outside the cuticular layer.
THE USE OF CHLAMYDOMONAS (CHLOROPHYTA: VOLVOCALES) AS A MODEL ALGAL SYSTEM FOR GENOME STUDIES AND THE ELUCIDATION OF PHOTOSYNTHETIC PROCESSES
Authors: Davies John P. , Grossman Arthur R.
Published: March 2003

Chlamydomonas reinhardtii Dangeard is a unicellular, haploid green alga that has been used as a model genetic system to investigate basic biological processes in photosynthetic eukaryotes. This organism has been particularly useful for dissecting photosynthesis because it can grow heterotrophically as well as photoautotrophically; this has allowed for the isolation and characterization of a large number of mutants that are completely devoid of photosynthetic CO2 fixation. Over the past 10 years there has been a dramatic increase in the number of molecular technologies that can be applied to studies of Chlamydomonas, enhancing its value as a model organism. Nuclear transformation has enabled researchers to generate and complement a range of different mutants and to investigate transcriptional control of gene expression in vivo. The development of methods for chloroplast transformation has helped elucidate the functions of chloroplast genes and the factors that modulate their expression. Genome‐wide studies will further enhance the value of Chlamydomonas as a resource for the biological community and will have a profound effect on the types of experimentation for which this alga is used. For example, the generation and characterization of a library of expressed sequence tags (ESTs) would identify cDNAs for most of the genes present on the Chlamydomonas genome. DNA microarray technology could be used to place these cDNAs on “chips,” configured from microscope slides, that would enable investigators to monitor changes in gene expression of essentially the entire genome simultaneously. The development of methods to identify strains harboring insertions in specific genes would help elucidate the functions of the genes that are represented in the EST library and that have been characterized for expression via the microarray technology. The production of linked physical and genetic maps would facilitate the map‐based cloning of any gene identified by a mutant phenotype. Finally, completing the sequence of the chloroplast genome and analyzing the function and expression of individual chloroplast genes would enhance our knowledge of the activities and biogenesis of this organelle. In thisreview we discuss the application of genomic technologies to studies of Chlamydomonas and how they would help elucidate the metabolism of plants, especially with respect to photosynthetic processes.
REGENERATION OF PROTOPLASTS FROM DISINTEGRATED CELLS OF BRYOPSIS PLUMOSA (DERBESIALES, CHLOROPHYTA)
Authors: Kim G.H. , Klotchkova T.A. , Kang Y.‐M.
Published: March 2003

When injured, the protoplasms come out from the multi‐nucleate giant cell of a green alga Bryopsis plumosa and can generate numerous new cells spontaneously. The cell organelles aggregated rapidly in sea water and became covered with a gelatinous envelope within fifteen minutes. A lipid cell membrane was formed inside the envelope within nine to twelve hours. Cytochemical studies using Nile Red and various enzymes revealed that the primary envelope is initially composed of polysaccharides then becoming a polysaccharide‐lipid complex. Fluorescein diacetate (FDA) staining showed that the primary envelope has some characteristics of cell membranes including semipermeability and selective transport of materials. The aggregation of cell organelles appears to be mediated by two kinds of material; one in vacuolar sap and the other on the surface of cell organelles. About a thousand new cells were generated from a single disintegrated branch and forty percent of them eventually developed into mature plants.
NEW GENERA OF FRESHWATER CRYPTOMONADS FROM COLORADO
Authors: Kugrens P. , Aguiar R. , Clay B.L. , Lee R.E.
Published: March 2003

Electron microscopic examinations of numerous isolates from Colorado lakes and reservoirs have revealed several new genera and species. Based on the furrow/gullet variations and the structure of the periplast, four new genera are proposed. These new genera and their characteristics are as follows. The first genus has a furrow without a gullet, and it has oval periplast plates. There are two chloroplasts per cell and two nucleomorphs located anterior to the chloroplasts in the periplastidial compartment. Pyrenoids are lacking. Chloroplasts contain phycoerythrin 566. The second genus is similar in shape and structure to Plagioselmis, but it has small rectangular plates rather than hexagonal plates. There is one dorsal chloroplast per cell, with a single stalked pyrenoid, which is not traversed by thylakoids and associated with two starch plates. The nucleomorph is posterior to the pyrenoid and is located between the nucleus and pyrenoid. Chloroplasts contain phycoerythrin 566. The third genus lacks a gullet and furrow and has an inner periplast sheet. Cells have two chloroplasts without pyrenoids, and the chloroplasts contain phycoerythrin 566. The nucleomorphs are located in the anterior portion of the plastidial compartment. The fourth genus is blue‐green in color, it lacks a furrow/gullet, and the internal and surface periplast components consist of hexagonal plates. Cells have a large pyrenoid that protrudes ventrally into the cytoplasm and is traversed by numerous paired thylakoids. The nucleomorph is situated lateral to the pyrenoid. Chloroplasts contain phycocyanin 645. This cryptomonad was previously identified as Chroomonas pochmanni, and it is mixotrophic.
STRUCTURE, COMPOSITION AND BIOGENESIS OF PRASINOPHYTE SCALES
Authors: Becker B.
Published: March 2003

The cell body and flagellar surfaces of prasinophytes are covered by non‐mineralyzed scales. Scales consist mainly of acidic polysaccharides containing large amounts of 2‐keto sugar acids. Glycoproteins are minor components and probably mainly involved in mediating scale‐subunit and scale‐membrane interactions. In thecate prasinophytes the cell body scales coalesce to form a rigid cell wall, generally known as a theca. We have studied the polysaccharides and glycoproteins of the thecate prasinophytes Tetraselmis striata and Scherffelia dubia over the last years. New results regarding the structure of carbohydrates and proteins will be presented.
COMPARING RESPIRATORY (ETS) ACTIVITY OF BACTERIA ATTACHED TO PHYTOPLANKTON AND FREELY SUSPENDED IN SURROUNDING SEAWATER
Authors: Milbrandt E.C. , Shapiro L.S.
Published: March 2003

We conducted investigated respiratory (ETS) activity of bacteria attached to phytoplankton and living free in surrounding seawater collected from coastal waters at Charleston, Oregon, USA. We hypothesized that the surface of a phytoplankton cell provides a habitat that permits enhanced metabolic activity in attached bacteria. In order to test this hypothesis, the number of bacteria that reduce 5‐Cyano‐2,3‐di‐tolyl tetrazolium chloride (CTC) were compared to the total number of bacteria, assessed by the nucleic acid stain, 4′,6‐diamidino‐2‐phenylindole (DAPI). Two‐hour incubations with the CTC dye and subsequent staining allowed for direct viewing of the position and the number of ETS active versus inactive bacteria in each sample. We found that the percentage of active bacteria attached to the phytoplankton cells' surface (42%) was 10 times that of bacteria freely suspended in the surrounding seawater (4%). Previous investigations of ETS activity of freely suspended bacteria found that 1% to 8% are actively respiring while non‐living particle associated bacteria showed that 20 to 35% of bacteria are actively respiring. Our results suggest that bacteria in coastal waters are substrate limited, and the extracellular products of photosynthesis may be more important than is generally realized. The surfaces of phytoplankton cell surfaces may provide habitat and substrates for a disproportionate share of bacterial production in coastal waters.
SEASONAL SUCCESSION OF PHYTOPLANKTON IN LAKE PRINCE, SUFFOLK, VIRGINIA: PRELIMINARY REPORT
Authors: Muscio C.M
Published: March 2003

Lake Prince is a reservoir lake that provides the region with drinking water, recreational boating, and fishing. The Virginia Department of Game and Inland Fisheries has an interest in the quantity and quality of phytoplankton production in the lake, especially regarding the health of fish populations. Another concern in this reservoir is oxygen availability, and aerators have been installed in the main body of the lake. A year‐long examination of the phytoplankton community structure is being conducted. Duplicate surface water samples are collected monthly from three stations, along with physical and chemical baseline data. Community structure and dominance are being examined with regard to the physical and chemical parameters, as well as seasonal climate changes. Cyanobacteria and Cryptophytes are the dominant spring flora. Diatoms and Chrysophytes are sub‐dominant populations.
CONFUSING CONVERGENT MORPHOLOGIES: DIVERSITY AND DIFFICULTIES IN NEW ZEALAND ERYTHROPELTIDALES AND BANGIALES
Authors: Nelson W.A. , Broom J.E. , Farr T.J.
Published: March 2003

An examination of New Zealand species of Porphyra and Bangia has led to the discovery of unexpectedly high diversity. In excess of 30 species of Porphyra and 5 species of Bangia can be distinguished, based on 18S rDNA sequence data. It is possible to develop a workable taxonomic framework to distinguish species of Porphyra found within this geographic region using a range of characters (morphological, anatomical, biochemical, physiological, life history characteristics). However, the taxonomic distinctions do not necessarily reflect phylogenetic relationships revealed by sequence analyses: convergence in character states is obscuring relationships. In the course of our work we have discovered that four species, originally described on the basis of traditional morphological and anatomical characters as Porphyra or Bangia, are more closely related to members of the order Erythropeltidales than to the Bangiales. These results are challenging us to consider new ways of describing and defining these organisms. We are finding convergence in character states, not only within Porphyra sens. lat. But spanning both the Bangiales and Erythropeltidales, which confounds both taxonomic distinctions and also phylogenetic hypotheses based on morphology and anatomy. This confusion could be countered effectively by the inclusion of molecular sequence data based on vouchered or type material in descriptions of taxa in the orders Bangiales and Erythropeltidales. This would allow conclusive identification of collected material by appropriate molecular tests, which are quicker and more direct identification tools than, for example, using characters drawn from the growth of these organisms under controlled culture conditions.
DEMOGRAPHY OF FRONDS OF SARGASSUM LAPAZEANUM FROM SOUTHERN BAJA CALIFORNIA, MEXICO, DURING EARLY STAGES
Authors: Rivera M.G. , Scrosati R.
Published: March 2003

In terms of biomass, Sargassum lapazeanum (Phaeophyceae, Fucales) is one of the most important seaweeds in La Paz Bay, on the southeastern coast of the Baja California Peninsula, Mexico. This species can be found year‐round in shallow subtidal sites. Standing biomass is lowest between fall and winter and highest between spring and summer. We are currently studying the annual demography of fronds as a necessary step to understanding the mechanisms of population regulation. Work is being done on a bed of about 90 m in length and three m in width. At this stage of abstract submission, we can report results for winter only. Random samples were collected in February and in March 2000 to estimate stand biomass, frond density, and size (frond length) structure. In addition, we labeled fronds with numbered plastic tags to estimate their rates of growth and of mortality during this period. Rates of recruitment were estimated from a combined analysis of the above. In February, fronds were all shorter than 6.5 cm. Between February and March, mean total frond density increased from 122 to 776 fronds m−2 (n = 30 quadrats). The mean recruitment rate was 667 fronds m−2, the mean growth rate was 0.5 cm day−1 (n = 60 fronds), and the mean mortality rate was 43 fronds m−2. From last year's preliminary observations, we expect to observe peaks of biomass and of reproduction in late spring, followed by negative growth rates and high mortality rates during summer.
LIGHT REGULATION OF PHYCOBILISOME BIOSYNTHESIS AND CONTROL BY A PHYTOCHROME‐LIKE PHOTORECEPTOR
Authors: Terauchi K. , Ort L. , Grossman A.R. , Kehoe
Published: March 2003

Ambient light quality changes dramatically affect the composition of light harvesting structures, the phycobilisomes, in many cyanobacterial species. In the cyanobacterium Fremyella diplosiphon, shifts in the ratio of red to green light lead to transcriptional changes and altered synthesis of several phycobilisome components. This process is called complementary chromatic adaptation (CCA). These two colors have opposite effects: red light activates an operon encoding the biliprotein phycocyanin (PC) and inactivates the operon encoding phycoerythrin (PE), whereas green light activates PE synthesis and shuts down PC synthesis. The effects of red and green light on CCA are photoreversible. Thus, CCA is similar to transcriptional processes that are controlled by phytochromes, a family of eukaryotic red/far red photoreversible photoreceptors. We are using molecular genetics to determine the mechanisms by which F. diplosiphon senses changes in the color of light of its environment. Initial mutant generation and complementation lead to the discovery of three CCA regulatory components that are part of a complex two component system. The most interesting of these is RcaE (regulator of chromatic adaptation), a histidine kinase‐class protein containing a region in its amino‐terminal half with similarity to the chromophore binding domains of phytochromes. Within this region, RcaE contains a cysteine residue in a similar location as that used for covalent attachment of the open‐chain tetrapyrrole chromophore in phytochromes. We will present recent data characterizing RcaE, including in vivo analysis of the chromophore that is attached to RcaE, as well as results from our recent isolation of a new CCA regulatory component.
PHYLOGENETIC RELATIONSHIPS OF GELIDIALES SPECIES IN COSTA RICA
Authors: Thomas D.T. , Freshwater D.W.
Published: March 2003

Despite a general paucity of studies on marine algae in Costa Rica, within the red algal order Gelidiales, 9 species are reported from the Caribbean, and 6 species from the Pacific. In this study 5 species from the southeast Caribbean coast and 2 species from the northwest Pacific coast of Costa Rica were collected for DNA sequence and morphological analyses. At the time of this writing, morphological observations of four Caribbean taxa have identified them as Gelidium microdonticum, Pterocladiella capillacea, P. melanoidea, and Gelidiella acerosa. In rbcL sequence analyses, Gelidium microdonticum is resolved within a clade of small Gelidium species predominantly found in the south Atlantic. Two collections representing different forms of Pterocladiella melanoidea sensu Dawson were found to have identical rbcL sequences. These samples were resolved in rbcL trees with a taxon from Texas identified as P. bartlettii and not P. melanoidea from Europe. Comparisons with type material are being made to verify these identifications so that the status of P. melanoidea in the Caribbean may be determined. The unidentified Caribbean taxon is resolved as a distinct species within the Pterocladiella clade as well. Gelidiella acerosa from Caribbean Costa Rica is closely allied with other Caribbean G. acerosa samples in rbcL trees. The two pacific taxa are small intertidal turf species and have not yet been identified. Sequence analyses resolve these taxa within a large clade of Indo‐Pacific and Caribbean Gelidium species.
EVIDENCE FOR GLUCAN COMPONENTS IN THE PRIMARY ZYGOTE WALL OF CHLAMYDOMONAS MONOICA
Authors: VanWinkle‐Swift K.P. , Salanga M.C. , Thompson E. G. , Bai  , Parish E.W.
Published: March 2003

The primary zygote wall of C. monoica is transient and is released from mature zygospores. The fluorochromes aniline blue and primulin, used in other systems to detect β‐1,3 glucans, stain the primary wall intensely. Two β‐1,3 glucan synthases have been identified in higher plants: a calcium‐dependent synthase produced in response to wounding and induced by chitosan, and a magnesium‐dependent enzyme, associated with pollen development and unresponsive to chitosan. Chitosan has no effect on C. monoica primary wall synthesis or staining properties. We are presently testing for the effect of magnesium and/or calcium depletion on primary wall synthesis. Aniline blue and primulin do not stain purified cellulose fibers, while the fluorochrome Calcofluor does. Calcofluor also stains the primary wall intensely. For all fluorochormes tested, fluorescence is first detected in motile quadriflagellate zygotes. Aniline blue staining maximizes quickly, while Calcofluor staining continues to intensify until primary wall release. Dinitrobenzonitrile, a specific inhibitor of cellulose synthesis in plants, has no effect on primary wall synthesis in C. monoica. Addition of glucanase or cellulase to partially purified primary walls results in wall thinning and loss of staining. Using electron microscopy, we are evaluating the effects of these enzymes on primary wall ultrastructure. Further studies are needed to determine whether all three fluorochromes are recognizing the same polysaccharide component (a β‐1,3 glucan or a β‐1,3; β‐1,4 mixed glucan), or whether Calcofluor staining indicates the presence of a distinct component containing β‐1,4 linkages, such as cellulose or a xyloglucan.
TEMPERATURE INDUCED PHOTOINHIBITION IN OUTDOOR CULTURES OF MONODUS SUBTERRANEUS
Authors: Vonshak A. , Torzillo G. , Boussiba S.
Published: March 2003

Outdoor algal cultures are continuously exposed to changes in environmental conditions, particularly irradiance and temperature. While the changes in light intensity take place in a range of one to two hours, the increase in temperature is a slower process and takes about four to five hours. This de‐synchronization between the two important environmental factors governing photosynthesis and growth of algae results in a unique stress condition where photoinhibition can be induced at relatively low light intensity. Outdoors the early morning culture temperature was found to be about 12 to 14° C, and reaches 25 to 28° C at mid‐day. In an experiment, such a natural temperature regime was compared to another one in which the morning temperature of the culture was increased to 20° C by using a heating system. A fast decline in the maximal photochemical efficiency of PSII (Fv/Fm) was observed starting as soon as sunrise. The decline was faster in the non‐heated culture and was to a lower value. The diurnal changes in the electron transfer rate (ETR) and in the non‐photochemical quenching (NPQ) of the cultures, indicated that the early morning exposure of cells to sub‐optimal temperature results in a fast inactivation of PSII activity which was reflected in an inhibition of the photosynthetic activity even when the two cultures finally reached the same temperature at mid‐day. Thus, under the same light and temperature mid‐day conditions the ETR was higher and the NPQ was significantly lower in the heated culture. Significant changes in productivity of the cultures also were observed.
DO PHYSICAL FACTORS REGULATE PHYTOPLANKTON DISTRIBUTION PATTERNS IN LARGE, SHALLOW LAKES?
Authors: Carrick H.J.
Published: March 2003

Factors that regulate phytoplankton dynamics in shallow, productive lakes are poorly understood, due to their predisposition for frequent algal blooms and sediment resuspension events. In Lake Apopka, greatest phytoplankton biomass reflects wind‐induced resuspension of algae (meroplankton) that exists on the aphotic lake bottom in a layer approximately 5 cm thick; this assemblage is dominated by diatoms (>60% of total biomass) that can occur in resting stages. Once exposed to moderate light, meroplankton are capable of growth and photosynthetic rates comparable with surface populations. In Lake Okeechobee, remote sensing was used to assess the basin‐wide distribution of suspended particles. Satellite reflectance values agreed well with in situ particle densities at 20 in‐lake stations (average r2; LANDSAT = 0.81, AVHRR = 0.53), and maps of algal blooms (r2 = 0.79, p ≤ 0.01). The greatest chlorophyll concentrations occurred in the vicinity of tributary nutrient inputs at the lake's perimeter, while turbidity increased towards the center of the lake reflecting predominant water circulation patterns. These results underscore the importance of physical‐biological interactions in lakes.