bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunohistochemical Detection of Activated Caspases in Apoptotic Hepatocytes in Rat Liver
Authors: Eckle Veit-Simon , Buchmann Albrecht , Bursch Wilfried , Schulte-Hermann Rolf , Schwarz Michael
Published: October 2004

In our study we tested the utility of antibodies that specifically recognize the cleaved large (active) subunits of caspase-3 and caspase-9 for immunohistochemical detection of apoptotic hepatocytes in rat liver sections using archival material from cyproterone acetate (CPA)-treated and control rats. CPA blocks apoptosis of hepatocytes and discontinuation of CPA treatment results in a syncronized wave of hepatocyte apoptosis. By comparing liver sections from CPA-treated and control rats with high and low rates of apoptosis we observed a close correlation between the occurrence of cleaved caspase-positive apoptotic figures and H&E-stained apoptotic bodies when evaluated in parallel sections. Caspase-stained figures were either immuno-positive apoptotic bodies or pre-apoptotic hepatocytes showing cytoplasmic and/or nuclear caspase-staining with otherwise normal cellular appearance. In extension of these observations we developed a double-immunohistochemical staining procedure which enables the detection of caspase-3-positive apoptotic hepatocytes within glutathione-S-transferase-P (GST-P)-positive preneoplastic liver foci. By use of this technique, inhibition of apoptosis by 2,3,7,8-tetrachlorodibenzo- p-dioxin as detected by counting of H&E-stained apoptotic bodies was found to correlate with a strong reduction of cleaved caspase-positive hepatocytes in GST-P-positive preneoplastic foci. In summary, this study demonstrates that cleaved caspase-positive apoptotic hepatocytes could be reliably identified and quantified both in normal and neoplastically transformed liver tissue.
Localization of Satratoxin-G in Stachybotrys chartarum Spores and Spore-Impacted Mouse Lung Using Immunocytochemistry
Authors: Gregory Laurel , Pestka James J. , Dearborn Dorr G. , Rand Thomas G.
Published: October 2004

Satratoxin-G (SG) is the major macrocyclic trichothecene mycotoxin produced by Stachybotrys chartarum ( atra) and has been implicated as a cause of a number of animal and human health problems including pulmonary hemorrhage in infants. However, there is little understanding where this toxin is localized in the spores and mycelial fragments of this species or in the lung impacted by SG-sequestered spores. The purpose of this study was to evaluate the distribution of SG in S. chartarum spores and mycelium in culture, and spore-impacted mouse lung in vivo, using immunocytochemistry. SG was localized predominately in S. chartarum spores with moderate labelling of the phialide-apex walls. Labelling was primarily along the outer plasmalemma surface and in the inner wall layer. Only modest labelling was observed in hyphae. Toxin localization at these sites supports the position that spores contain the highest satratoxin concentrations and that the toxin is constitutively produced. In impacted mouse lung, highest SG labelling was detected in lysosomes, along the inside of the nuclear membrane in nuclear heterochromatin and RER within alveolar macrophages. Alveolar type II cells also showed modest labelling of the nuclear heterochromatin and RER. There was no evidence that the toxin accumulated in the neutrophils, fibroblasts, or other cells associated with the granulomas surrounding spores or mycelial fragments. These observations indicate that SG displays a high degree of cellular specificity with respect to its uptake in mouse lung. They further indicate that the alveolar macrophages play an important role in the sequestration and immobilization of low concentrations of the toxin.
Follicular Epithelial Cell Hypertrophy Induced by Chronic Oral Administration of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Female Harlan Sprague—Dawley Rats
Authors: Tani Yoshiro , Maronpot Robert R. , Foley Julie F. , Haseman Joseph K. , Walker Nigel J. , Nyska Abraham
Published: October 2004

2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD) affects the thyroid morphologically and/or functionally in adult animals. Recently, the National Toxicology Program conducted a 2-year gavage study of TCDD in female Harlan Sprague—Dawley rats. The only treatment-related alterations found in thyroid follicles were decreased luminal size and increased height of the follicular epithelial cells, without prominent protrusion into the lumen. The present study elucidated the nature of these follicular lesions. Thyroid glands of 10 rats each from the control, high (100 ng/kg/day)-dose, and stop-study (100 ng/kg/day, 30 weeks; vehicle to study termination) groups in the 2-year study were evaluated microscopically. Twenty randomly selected follicles were measured morphometrically in each animal. TCDD treatment significantly decreased the mean ratio of luminal/epithelial areas and increased the mean sectional epithelial height of the high-dose group compared to controls. Thyroid sections were immunostained with antibody against minichromosome maintenance (MCM) proteins, a novel cell-cycle biomarker. The MCM labeling index of the high-dose group was significantly higher than that of the control; however, the TUNEL labeling index was also higher in the high-dose group than the control. All data from the stop group were comparable to those from controls. These results indicate that the follicular cell response was hypertrophic and reversible. This information should contribute to diagnosis of nonneoplastic thyroid follicular lesions in rats.
Metabolic Alterations of Toxic and Nonessential Elements by the Treatment of Sempervivum tectorum Extract in a Hyperlipidemic Rat Model
Authors: Szentmihályi Klára , Fehér Erzsébet , Vinkler Péter , Kéry Ágnes , Blázovics Anna
Published: October 2004

A hyperlipidemic rat model was used to examine the therapeutic effect of Sempervivum tectorum plant extract on the metabolic alterations of Al, As, B, Ba, Cd, Hg, Ni, Pb, and Ti in the liver and bile. Hyperlipidemia was produced by lipogenic diet and alcohol and verified by morphological investigation of the liver with the aid of light and an electron microscope. Element concentration in the liver and bile were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration values in the liver higher than the detection limit (Al, Ba, Ni, Ti) were unambiguous. Significant differences were found for the four groups at p < 0 .05 level (ANOVA). A significant difference was observed between Al and B concentration in the bile fluids of the 4 groups ( p < 0 .05). The excretion of Al and Ti into the bile fluid increased significantly ( p < 0 .05). Following the administration of S. tectorum extract to rats with hyperlipidemia, the excretion of Al, B and Ba increased, whereas the excretion of Ti decreased significantly ( p < 0 .05). The favorable action of the extract (protecting the liver in hyperlipidemic rats) was verified by morphological studies, and its detoxicating property was shown by the elimination of Al, Ba, Ni, and Ti from the liver.
Promotion of Colon Tumors in C57BL/6J-APCmin/+ Mice by Thiazolidinedione PPARγ Agonists and a Structurally Unrelated PPARγ Agonist
Authors: Pino Michael V. , Kelley Michael F. , Jayyosi Zaid
Published: October 2004

Thiazolidinedione PPAR γ agonists (troglitazone and rosiglitazone) were previously shown to promote colon tumor formation in C57BL/6JAPC min/+ mice, a model for human familial adenomatous polyposis. This study was conducted to determine if another thiazolidinedione PPAR γ agonist, pioglitazone, and a PPAR γ agonist structurally unrelated to the thiazolidinedione family, NID525, (a tetrazole-substituted phenoxymethylquinolone), would also promote colon tumors in this mouse model. Mice were treated in-feed with the thiazolidinediones troglitazone (150 mg/kg/day), rosiglitazone (20 mg/kg/day), or pioglitazone (150 mg/kg/day), or with NID525 (150 mg/kg/day) for 8 weeks. An increased incidence in colon tumors compared to controls was observed for all of the thiazolidinedione-treated groups as well as the NID525-treated group. These results indicate that the tumor-promoting effect of PPAR γ agonists in the colon of C57BL/6J-APCmin/+ mice is likely related to the pharmacological activity of this group of drugs and not the thiazolidinedione structure.
Male Reproductive Tract Lesions at 6, 12, and 18 Months of Age Following in Utero Exposure to Di(n-butyl) Phthalate
Authors: Barlow Norman J. , Mcintyre Barry S. , Foster Paul M.D.
Published: October 2004

In utero exposure of male rats to the antiandrogen di( n-butyl) phthalate (DBP) leads to decreased anogenital distance (AGD) on postnatal day (PND) 1, increased areolae retention on PND 13, malformations in the male reproductive tract, and histologic testicular lesions including marked seminiferous epithelial degeneration and a low incidence of Leydig cell (LC) adenomas on PND 90. One objective of this study was to determine the incidence and persistence of decreased AGD, increased areolae retention, and LC adenomas in adult rats following in utero DBP exposure. A second objective was to determine whether AGD and areolae retention during the early postnatal period are associated with lesions in the male reproductive tract. Pregnant Crl:CD(SD)BR rats were gavaged with corn oil or DBP at 100 or 500 mg/kg/day, 10 dams per group. Three replicates of rats (n = 30 rats per replicate) were exposed from gestation day 12 to 21 and the male offspring allowed to mature to 6, 12, or 18 months of age. Gross malformations in the male reproductive tract and histologic lesions in the testes were similar to those previously described. However, testicular dysgenesis, a lesion of proliferating LCs and aberrant tubules that has not been previously described in DBP-exposed testes, was diagnosed. The incidence of this lesion was approximately 20% unilateral and 7—18% bilateral in the high-dose group and was similar among all ages examined, implicating a developmental alteration rather than an age-related change. AGD and areolae retention were found to be permanent changes following in utero exposure to 500 mg/kg/day of DBP. Decreased AGD was a sensitive predictor of lesions in the male reproductive tract, relatively small changes in AGD were associated with a significant incidence of male reproductive malformations. In utero DBP exposure induced proliferative developmental lesions, some of which would have been diagnosed as LC adenomas by the morphological criteria set forth by the Society of Toxicologic Pathology. However, these lesions were dissimilar to traditional LC adenomas as the LCs were poorly differentiated and the lesions contained aberrant seminiferous tubules. While the morphology and incidence of this DBP-induced testicular developmental lesion has been fully characterized by this study, the detailed pathogenesis warrants further investigation.
Effects of Dietary Isoflavone Aglycones on the Reproductive Tract of Male and Female Mice
Authors: Cline J. Mark , Franke Adrian A. , Register Thomas C. , Golden Deborah L. , Adams Michael R.
Published: October 2004

We assessed the effects of dietary consumption of soy isoflavone aglycones on the reproductive tract of sexually mature male and female mice. Isoflavone concentrates with a ratio of 10:1, 2:1 or 1:10 genistein:daidzein (G:D) were added to provide 120 mg total isoflavones/1800 Calories (approximately 40 mg/kg body weight) to diets having either casein/lactalbumin or soy protein isolate as the source of protein. After 16 weeks, mice were necropsied and gross and histopathologic assessments of uterus, vagina, testes and accessory sex glands were completed. Effects of the 10G:1D isoflavone concentrates were absent or minimal in females but in males included atrophy of accessory sex glands. In contrast, the 2G:1D and 1G:10D concentrates caused dramatic estrogenic effects in both male and female mice. Effects in females included endometritis and effects typical of estrogenic stimulation (i.e., uterine enlargement, keratinization of vaginal epithelium, increased height of endometrial surface epithelial cells, and uterine squamous metaplasia). Effects in males included reduced plasma testosterone concentrations, atrophy of seminiferous epithelium, atrophy of accessory sex glands, and squamous metaplasia of seminal vesicles. Some effects varied with protein source. We conclude that a diet containing approximately 40 mg/kg soy isoflavone aglycones with a genistein:daidzein ratio of 2:1 or less has marked estrogenic effects on the reproductive system of male and female mice.
Society of Toxicologic Pathology Position on Histopathology Data Collection and Audit Trail: Compliance with 21 CFR Parts 58 and 11
Authors: Tuomari Darrell , Elliott Glenn , Kulwich Barbara , Yarrington John , Fouillet Xavier , Geoly Frank , Long Philip
Published: October 2004

The purpose of this paper is to discuss the requirement of the audit trail to track changes made to the histopathology data, in order to be compliant with the Code of Federal Regulations (CFR), Volume 21, for both Part 58 (Good Laboratory Practices [GLP]) and Part 11 (Electronic Records/Signatures).
Fatigue in the general population: A translation and test of the psychometric properties of the Norwegian version of the fatigue severity scale
Authors: Lerdal Anners , Wahl Astrid K. , Rustoen Tone , Hanestad Berit R. , Moum Torbjorn
Published: October 2004

Objective: A study was undertaken to test the psychometric properties of the Fatigue Severity Scale (FSS), and to explore the relationship between fatigue and sociodemographic variables in the general population. Method: A national representative sample of 1893 respondents was randomly selected from a pool of 4,000 Norwegians aged 19—81 years. A mailed questionnaire that included the FSS was used to measure fatigue severity. Results: The FSS showed satisfactory internal consistency (Cronbach's alpha 0.88). The prevalence of high fatigue (FSS score>=5) was 23.1% in the total sample. More women (26.2%) than men (19.8%) experienced high fatigue (p=0.004). Respondents with chronic illness (more than six months) reported a higher mean (M=4.69, SD=1.35) than the rest of the sample (M=3.67, SD=1.17) (p<0.001). An inverse correlation was found between fatigue and level of formal education (r=0.20, p<0.001). Conclusion: The psychometric properties of the Norwegian version of FSS were satisfactory. To avoid over-diagnosing people for high level of fatigue, the threshold for high fatigue probably should be 5 on the FSS scale instead of 4 as had been suggested originally, but further validation of the cut-off point is needed.
NGF Controls Dendrite Development in Hippocampal Neurons by Binding to p75NTRand Modulating the Cellular Targets of Notch
Authors: Salama-Cohen Patricia , Arévalo María-Ángeles , Meier Jochen , Grantyn Rosemarie , Rodríguez-Tébar Alfredo
Published: October 2004

Notch and neurotrophins control neuronal shape, but it is not known whether their signaling pathways intersect. Here we report results from hippocampal neuronal cultures that are in support of this possibility. We found that low cell density or blockade of Notch signaling by a soluble Delta-Fc ligand decreased the mRNA levels of the nuclear targets of Notch, the homologues of enhancer-of-split 1 and 5 (Hes1/5). This effect was associated with enhanced sprouting of new dendrites or dendrite branches. In contrast, high cell density or exposure of low-density cultures to NGF increased the Hes1/5 mRNA, reduced the number of primary dendrites and promoted dendrite elongation. The NGF effects on both Hes1/5 expression and dendrite morphology were prevented by p75-antibody (a p75NTR-blocking antibody) or transfection with enhancer-of-split 6 (Hes6), a condition known to suppress Hes activity. Nuclear translocation of NF-kappaB was identified as a link between p75NTRand Hes1/5 because it was required for the up-regulation of these two genes. The convergence of the Notch and p75NTRsignaling pathways at the level of Hes1/5 illuminates an unexpected mechanism through which a diffusible factor (NGF) could regulate dendrite growth when cell-cell interaction via Notch is not in action.
FAT/CD36-mediated Long-Chain Fatty Acid Uptake in Adipocytes Requires Plasma Membrane Rafts
Authors: Pohl Jürgen , Ring Axel , Korkmaz Ümine , Ehehalt Robert , Stremmel Wolfgang
Published: October 2004

We previously reported that lipid rafts are involved in long-chain fatty acid (LCFA) uptake in 3T3-L1 adipocytes. The present data show that LCFA uptake does not depend on caveolae endocytosis because expression of a dominant negative mutant of dynamin had no effect on uptake of [3H]oleic acid, whereas it effectively prevented endocytosis of cholera toxin. Isolation of detergent-resistant membranes (DRMs) from 3T3-L1 cell homogenates revealed that FAT/CD36 was expressed in both DRMs and detergent-soluble membranes (DSMs), whereas FATP1 and FATP4 were present only in DSMs but not DRMs. Disruption of lipid rafts by cyclodextrin and specific inhibition of FAT/CD36 by sulfo-N-succinimidyl oleate (SSO) significantly decreased uptake of [3H]oleic acid, but simultaneous treatment had no additional or synergistic effects, suggesting that both treatments target the same mechanism. Indeed, subcellular fractionation demonstrated that plasma membrane fatty acid translocase (FAT/CD36) is exclusively located in lipid rafts, whereas intracellular FAT/CD36 cofractionated with DSMs. Binding assays confirmed that [3H]SSO predominantly binds to FAT/CD36 within plasma membrane DRMs. In conclusion, our data strongly suggest that FAT/CD36 mediates raft-dependent LCFA uptake. Plasma membrane lipid rafts might control LCFA uptake by regulating surface availability of FAT/CD36.
Anillin Binds Nonmuscle Myosin II and Regulates the Contractile Ring
Authors: Straight Aaron F. , Field Christine M. , Mitchison Timothy J.
Published: October 2004

We demonstrate that the contractile ring protein anillin interacts directly with nonmuscle myosin II and that this interaction is regulated by myosin light chain phosphorylation. We show that despite their interaction, anillin and myosin II are independently targeted to the contractile ring. Depletion of anillin in Drosophila or human cultured cells results in cytokinesis failure. Human cells depleted for anillin fail to properly regulate contraction by myosin II late in cytokinesis and fail in abscission. We propose a role for anillin in spatially regulating the contractile activity of myosin II during cytokinesis.
Phytochemical Assays of Commercial Botanical Dietary Supplements
Authors: Krochmal Robert , Hardy Mary , Bowerman Susan , Lu Qing-Yi , Wang H-J , Elashoff RM , Heber David
Published: October 2004

The growing popularity of botanical dietary supplements (BDS) has been accompanied by concerns regarding the quality of commercial products. Health care providers, in particular, have an interest in knowing about product quality, in view of the issues related to herb‐drug interactions and potential side effects. This study assessed whether commercial formulations of saw palmetto, kava kava, echinacea, ginseng and St. John′s wort had consistent labeling and whether quantities of marker compounds agreed with the amounts stated on the label. We purchased six bottles each of two lots of supplements from nine manufacturers and analyzed the contents using established commercial methodologies at an independent laboratory. Product labels were found to vary in the information provided, such as serving recommendations and information about the herb itself (species, part of the plant, marker compound, etc.) With regard to marker compound content, little variability was observed between different lots of the same brand, while the content did vary widely between brands (e.g. total phenolic compounds in Echinacea ranged from 3.9–15.3 mg per serving; total ginsenosides in ginseng ranged from 5.3–18.2 mg per serving). Further, the amounts recommended for daily use also differed between brands, increasing the potential range of a consumer′s daily dose. Echinacea and ginseng were the most variable, while St. John′s wort and saw palmetto were the least variable. This study highlights some of the key issues in the botanical supplement market, including the importance of standardized manufacturing practices and reliable labeling information. In addition, health care providers should keep themselves informed regarding product quality in order to be able to appropriately advise patients utilizing both conventional and herbal medicines.
Distinct protein interfaces in transmembrane domains suggest an in vivo folding model
Authors: Stevens Timothy J. , Mizuguchi Kenji , Arkin Isaiah T.
Published: October 2004

Given the known high‐resolution structures of α‐helical transmembrane domains, we show that there are statistically distinct classes of transmembrane interfaces which relate to the folding and oligomerization of transmembrane domains. Distinct types of interfaces have been categorized and refer to those between: the same polypeptide chain, different polypeptide chains, helices that are sequential neighbors, and those that are nonsequential. These different interfaces may reflect different phases in the mechanism of transmembrane domain folding and are consistent with the current experimental evidence pertaining to the folding and oligomerization of transmembrane domains. The classes of helix‐helix interfaces have been identified in terms of the numbers and different types of pairwise amino acid interactions. The specific measures used are interaction entropy, the information content of interacting partners compared to a random set of contacts, the amino acid composition of the classes and the abundances of specific amino acid pairs in close contact. Knowledge of the clear differences in the types of helix‐helix contacts helps with the derivation of knowledge‐based constraints which until now have focused on only the interiors of transmembrane domains as compared to the exterior. Taken together, an in vivo model for membrane protein folding is presented, which is distinct from the familiar two‐stage model. The model takes into account the different interfaces of membrane helices defined herein, and the available data regarding folding in the translocation channel.
To be folded or to be unfolded?
Authors: Garbuzynskiy Sergiy O. , Lobanov Michail Yu. , Galzitskaya Oxana V.
Published: October 2004

The lack of ordered structure in “natively unfolded” proteins raises a general question: Are there intrinsic properties of amino acid residues that are responsible for the absence of fixed structure at physiological conditions? In this article, we demonstrate that the competence of a protein to be folded or to be unfolded may be determined by the property of amino acid residues to form a sufficient number of contacts in a globular state. The expected average number of contacts per residue calculated from the amino acid sequence alone (using the average number of contacts for 20 amino acid residues in globular proteins) can be used as one of the simple indicators of natively unfolded proteins. The prediction accuracy for the sets of 80 folded and 90 natively unfolded proteins reaches 89% if the expected average number of contacts is used as a parameter and 83% in the case of hydrophobicity. An optimal set of artificial parameters for 20 amino acid residues obtained by Monte Carlo algorithm to maximally separate the sets of 90 natively unfolded and 80 folded proteins demonstrates the upper limit for prediction accuracy, which is 95%.
Folding of a designed simple ankyrin repeat protein
Authors: Devi V. Sathya , Binz H. Kaspar , Stumpp Michael T. , Plückthun Andreas , Bosshard Hans Rudolf , Jelesarov Ilian
Published: October 2004

Ankyrin repeats (AR) are 33‐residue motifs containing a β‐turn, followed by two α‐helices connected by a loop. AR occur in tandem arrangements and stack side‐by‐side to form elongated domains involved in very different cellular tasks. Recently, consensus libraries of AR repeats were constructed. Protein E1_5 represents a member of the shortest library, and consists of only a single consensus repeat flanked by designed N‐ and C‐terminal capping repeats. Here we present a biophysical characterization of this AR domain. The protein is compactly folded, as judged from the heat capacity of the native state and from the specific unfolding enthalpy and entropy. From spectroscopic data, thermal and urea‐induced unfolding can be modeled by a two‐state transition. However, scanning calorimetry experiments reveal a deviation from the two‐state behavior at elevated temperatures. Folding and unfolding at 5°C both follow monoexponential kinetics with kfolding = 28 sec−1 and kunfolding = 0.9 sec−1. Kinetic and equilibrium unfolding parameters at 5°C agree very well. We conclude that E1_5 folds in a simple two‐state manner at low temperatures while equilibrium intermediates become populated at higher temperatures. A chevron‐plot analysis indicates that the protein traverses a very compact transition state along the folding/unfolding pathway. This work demonstrates that a designed minimal ankyrin repeat protein has the thermodynamic and kinetic properties of a compactly folded protein, and explains the favorable properties of the consensus framework.
Evolutionarily conserved regions and hydrophobic contacts at the superfamily level: The case of the fold‐type I, pyridoxal‐5′‐phosphate‐dependent enzymes
Authors: Paiardini Alessandro , Bossa Francesco , Pascarella Stefano
Published: October 2004

The wealth of biological information provided by structural and genomic projects opens new prospects of understanding life and evolution at the molecular level. In this work, it is shown how computational approaches can be exploited to pinpoint protein structural features that remain invariant upon long evolutionary periods in the fold‐type I, PLP‐dependent enzymes. A nonredundant set of 23 superposed crystallographic structures belonging to this superfamily was built. Members of this family typically display high‐structural conservation despite low‐sequence identity. For each structure, a multiple‐sequence alignment of orthologous sequences was obtained, and the 23 alignments were merged using the structural information to obtain a comprehensive multiple alignment of 921 sequences of fold‐type I enzymes. The structurally conserved regions (SCRs), the evolutionarily conserved residues, and the conserved hydrophobic contacts (CHCs) were extracted from this data set, using both sequence and structural information. The results of this study identified a structural pattern of hydrophobic contacts shared by all of the superfamily members of fold‐type I enzymes and involved in native interactions. This profile highlights the presence of a nucleus for this fold, in which residues participating in the most conserved native interactions exhibit preferential evolutionary conservation, that correlates significantly (r = 0.70) with the extent of mean hydrophobic contact value of their apolar fraction.
Predicting enzyme family class in a hybridization space
Authors: Chou Kuo‐Chen , Cai Yu‐Dong
Published: October 2004

Given the sequence of a protein, how can we predict whether it is an enzyme or a non‐enzyme? If it is, what enzyme family class it belongs to? Because these questions are closely relevant to the biological function of a protein and its acting object, their importance is self‐evident. Particularly with the explosion of protein sequences entering into data banks and the relatively much slower progress in using biochemical experiments to determine their functions, it is highly desired to develop an automated method that can be used to give fast answers to these questions. By hybridizing the gene ontology and pseudo‐amino‐acid composition, we have introduced a new method that is called GO‐PseAA predictor and operate it in a hybridization space. To avoid redundancy and bias, demonstrations were performed on a data set in which none of the proteins in an individual class has ≥40% sequence identity to any other. The overall success rate thus obtained by the jackknife cross‐validation test in identifying enzyme and non‐enzyme was 93%, and that in identifying the enzyme family was 94% for the following six main Enzyme Commission (EC) classes: (1) oxidoreductase, (2) transferase, (3) hydrolase, (4) lyase, (5) isomerase, and (6) ligase. The corresponding rates by the independent data set test were 98% and 97%, respectively.
EFFECT OF ROCKY INTERTIDAL AMPHIPODS ON ALGAL RECRUITMENT: A FIELD STUDY1
Authors: Buschmann Alejandro H. , Vergara Pedro A.
Published: October 2004

Evidence about the potential of mobile marine invertebrates to act as algal spore dispersal agents is presently circumstantial. Using a field correlational and experimental protocol, our study tested the hypothesis that amphipods can increase the spore recruitment of the red algaIridaea laminarioidesBory.Iridaea laminarioidesspore recruitment onto glass slides was measured at a site with high amphipod abundance and a site with low density of amphipods. To evaluate the effect of anUlvacanopy on recruitment, replicated glass slides with and without a surroundingUlvacanopy were installed at both sites. The number ofI. laminarioidesspores recruited on the glass slides was four to eight times higher at the high amphipod abundance site than at the low density site. However, the presence of anUlvacanopy covering the glass slides did not significantly increase the recruitment ofI. laminarioides.Because the abundance ofI. laminarioides, the proportion of cystocarpic plants, and the percentage of open cystocarps only differed slightly between the low and high abundance amphipod sites, we suggest that the variation in recruitment between the sites is due to the differences in amphipod abundance (and their movements) and not to differences in spore production. Moreover, the presence ofI. laminarioidescystocarps showing amphipod grazing scars was significantly higher at the high amphipod density site than at the low density site.
CIRCADIAN REGULATION OF BIOLUMINESCENCE IN THE DINOFLAGELLATE PYROCYSTIS LUNULA1
Authors: Colepicolo Pio , Roenneberg Till , Morse David , Taylor Walter R. , Hastings J. Woodland
Published: October 2004

In the unicellular algae Pyrocystis lunula Schütt and Gonyaulax polyedra Stein, bioluminescence and its circadian regulation are similar in several respects, but there are also several important differences. As in G. polyedra, P. lunula emits light both as bright flashes and as a low intensity glow. At 20° C, the individual flashes are considerably brighter than in G. polyedra, and their durations are typically less than 500 ms. Both species show a circadian rhythm in the frequency of spontaneous flashes, which peaks in the night‐phase under light–dark cycles and continues in both continuous light and dark. However, compared to G. polyedra, the circadian system in P. lunula is more sensitive to light: 10 min exposures (500 μmol · m–2· s–1 white light) can shift the phase of the rhythm by more than 8 h, and rhythmicity is completely suppressed at an irradiance above 20 μmol · m–2· s–1, where the G. polyedra rhythym persists for weeks. Like G. polyedra, period length increases with increasing irradiance of continuous red light but decreases with increasing intensity of continuous blue light. The glow in P. lunula differs markedly from that in G. polyedra in that it occurs at about the same intensity at all times during the circadian cycle; thus, it is not under circadian control but may fluctuate 5–10‐fold in intensity within a time frame of seconds. This suggests that the glow may differ in its physiological basis in the two organisms. The results also indicate that the circadian regulation of luciferase activity differs in the two species. In G. polyedra, the organelle responsible for bioluminescence and luciferase is lost and then reformed on a daily basis; in P. lunula, the luciferase is conserved and localized elsewhere during the nonbioluminescent phase of the cycle.
REVEALING GENETIC MARKERS IN GELIDIUM VAGUM (RHODOPHYTA) THROUGH THE RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) TECHNIQUE1
Authors: Patwary Mohsin U. , MacKay Ron M. , van der Meer John P.
Published: October 2004

The recently developed random amplified polymorphic DNA technique was evaluated as a method for characterizing isolates of the agarophyte Gelidium vagum Okamura. Reaction conditions for single primer polymerase chain reaction were optimized to obtain a high degree of reproducibility of the amplified bands generated from purified G. vagum DNA. A total of 165 primers, including both (A + T)‐ and (G + C)‐rich sequences, was screened for DNA amplification using template DNA from a single Gelidium isolate. None of the 45 (A + T)‐rich primers was positive (i.e. band‐producing). Of the (G + C)‐rich primers, 47 were positive, generating a total of 322 prominent amplification products for DNA from 13 different G. vagum isolates. Polymorphic DNA loci were detected by 37 of the primers. Unweighted pair‐group arithmetic average cluster analysis (UPGMA) of these loci was used to group the G. vagum isolates and thereby determine which were most similar. G. latifolium, used as an out‐group for the UPGMA analysis, showed a high degree of dissimilarity.
THE LIFE CYCLE OE SARGASSUM HORNERI (PHAEOPHYTA) IN LABORATORY CULTURE1
Authors: Uchida Takuji
Published: October 2004

The life cycle of the large dioecious alga Sargassum horneri (Turner) C. Agardh was completed in unialgal culture by controlling photoperiod in relation to the phase of growth. Embryos isolated from a naturally grown female thallus gave rise to early germlings that rapidly formed blades under both short‐day (9 h L) and long‐day (15 h L) conditions at 20° C Shoot elongation, which followed early blade formation, occurred under the short‐day conditions hut not under the long‐day conditions. Functional female and male receptacles developed when thalli 8–14 cm long grown under the short‐day conditions were transferred to the long‐day conditions; gamete fusion occurred when male and female thalli were grown together. Fertilized oospores gave rise to normal thalli in a manner similar to that for in situ plants. Thus, the life cycle of S. horneri was completed in laboratory culture.
RELATIONSHIPS OF SEDIMENTED DIATOM SPECIES (BACILLARIOPHYCEAE) TO ENVIRONMENTAL GRADIENTS IN DILUTE NORTHERN NEW ENGLAND LAKES1
Authors: Anderson Dennis S. , Davis Ronald B. , Ford Mary S. (Jesse)
Published: October 2004

Limnological gradients of small, oligotrophic, and low conductance lakes in northern New England were defined by principal components analysis; relationships of sedimented diatom species to the gradients were investigated by correlation analysis. Diatom distributions were most strongly related to the gradient of pH and alkalinity and the covarying variables, conductance, Mg, Ca, total Al, and exchangeable Al. Weaker relationships to lake morphology, dissolved organic carbon and water color, altitude and marine aerosol inputs, and the distinctive water chemistry of some New Hampshire lakes were also present. Results for 16 taxa of importance in our studies of lake acidity are given in detail and are compared to results from other regions of eastern North America. Planktonic taxa were absent below pH 5.5, with the exception of the long form of Asterionella ralfsii var. americana Korn. The two forms of this taxon differed ecologically: the long form (>45μm) had an abundance weighted mean (AWM) pH 4.90 and occurred mostly in lakes that were deep relative to transparency; the short form (<45μm)had an AWM pH and occurred on lakes that were shallow relative to transparency. The ecological advantage of a “splitter” approach to diatom taxonomy was demonstrated by examination of other taxa as well, including Tabellaria flocculosa (Roth) Kütz. These results have important implications for paleolimnological interpretations.
EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE GROWTH OF TWO FRESHWATER PHOTOSYNTHET1C CRYPTOPHYTES1
Authors: Ojala Anne
Published: October 2004

Effects of light and temperature on growth of two freshwater photosynthetic cryptophytes of different cell size were studied in batch cultures. For the smaller Cryptomonas 979/67, Steele's model and equation of Platt et al. described the relationship between growth rate and photon flux density (PFD), whereas a hyperbolic tangent function gave a better fit for the larger Cryptomonas 979/62. Maximum growth rates given by the three models were consistent with each other, but the hyperbolic tangent function gave slightly lower estimates. Maximum growth rates in relation to temperature were well described for both species by the model of Logan et al. The optimum temperature for growth for Cryptomonas 979/67 was ca. 24.5° C and 19.0° C for Cryptomonas 979/62. The lethal temperatures were 30.4° C and 23.1° C for 979/67 and 979/62, respectively. The estimated maximum growth rates were 1.38 div.·day−1 for Cryptomonas 979/67 and 0.87 div.·day −1 for Cryptomonas 979/62. There were interspecific differences in photoadaptation strategies, as Cryptomonas 979/67 required relatively high PFDs to show net growth, whereas Cryptomonas 979/62 grew at lower irradiances. Cryptomonas 979/67 showed photoinhibition soon after the saturation point, but Cryptomonas 979/62 tolerated a much wider range of irradiance. From their growth responses to light, Cryptomonas 979/ 67 appears to be a stenotopic and Cryptomonas 979/ 62 a eurytopic strain.
EFFECTS OF NITRATE AVAILABILITY AND IRRADIANCE ON INTERNAL NITROGEN CONSTITUENTS IN CORALLINA ELONGATA (RHODOPHYTA)1
Authors: Vergara Juan J. , Niell F. Xavier
Published: October 2004

Short‐term (5‐h) phycobiliprotein photoacclimation was a NO3−, dependent process in the red alga Corallina elongata Ellis et Soland. At low irradianre levels, phycobiliprotein synthesis (both r‐phycocyacin and r‐phycocyanin) took place when N supply was sufficient but was restricted by N limitation. Exposure to saturating irradiance resulted in pigment degradation under N limitation; however, under N‐sufficient conditions a partial r‐phycoerythrin synthesis was observed, despite the repressing role of high photon flux densities on phycobiliprotein synthesis. Soluble protein was less affected than phycobiliprotein by N limitation at low photon flux densities indicating that N limitation stimulates the flow of internal N metabolites toward the synthesis of nonpigmented proteins rather than pigmented proteins.

The addition of protein synthesis inhibitors revealed that new phycobiliprotein synthesis occurs in response to sufficient N conditions. When protein synthesis was blocked in the chloroplast and cytoplasm simultaneously (addition of chloramphemcol and cycloheximide), both pigmented and nonpigmented protein synthesis was inhibited. Howeever, when protein systhesis was blocked in the chloroplast, only phycobiliprotein synthesis was clearly inhibited, whereas nonpigmented protein was less affected, indicating that phycobiliprotein is the main fraction of protein synthesized in the chloroplast at low photon flux densities when external N is available. This inhibition of phycobiliprotein synthesis was consistent with a maximal increase in metabolites of protein synthesis (internal NH4+ and amino acids).

Our results suggest that phycobiliproteins may be an important N reservoir to meet internal N demands during N limitations in C. elongata. Moreover, r‐phycoerythrin, synthesized even at saturating irradiance levels, and the major constituent of the phycobiliprotein pigments, may be more sensitive to changes in N supply than r‐phycocyanin. The influence of limited irradiance levels on N assimilation and the effects of repressing protein synthesis on internal N accumulation are also discussed.
A MODIFIED CELL WALL MUTANT OF THE RED MICROALGA RHODELLA RETICULATA RESISTANT TO THE HERBICIDE 2,6‐DICHLOROBENZONITRILE1
Authors: Arad Shoshana (Malis) , Dubinsky Ofer , Simon Bracha
Published: October 2004

The rigid component of the cell walls of red macroalgae, cellulose, is lacking in the red microalgae. Instead, the cells are encapsulated within an amorphous polysaccharide. These complex sul fated polysaccharides are composed of at least 10 different sugars, but their structure is not known, When the herbicide 2,6‐dichlorobenzonitrile (DCB), a compound that specifically inhibits cellulose biosynthesis, was applied to cultures of the red microalga Rhodella reticulata upon inoculation, growth was inhibited. When added during the stationary phase of growth (after cell division had ceased), DCB did not affect cell number but it did inhibit polysaccharide production. A spontaneous mutant resistant to DCB was selected; it had physiological characteristics similar to those of the wild‐type parent. The composition of the cell wall polysaccharide of the mutant was totally modified, being composed almost entirely (98% of its dry matter, as compared to 2.9% in the wild type) of methyl galactose, but retaining the same sulfate content. The molecular mass of the mutant polysaccharide was, however, similar to that of the wild‐type parent (∼6 × 106 daltons), although its viscosity was significantly lower.
CHROMOSOMES AND DNA IN SYMBIODINIUM FROM AUSTRALIAN HOSTS1
Authors: Udy James W. , Hinde Rosalind , Vesk Maret
Published: October 2004

Chromosome counts are reported for five species of Symbiodinium Freudenthal isolated from the host species Plesiastrea versipora, Aiptasia pulchella, Parerythropodium sp., Zoanthus robustus, and Capnella gaboensis based on light and electron microscope studies. Both techniques resulted in large variations in the apparent numbers of chromosomes per nucleus in Symbiodinium isolated from the same host colony. Adjacent regions of condensed DNA were occasionally linked by thin fibrils of DNA, The results suggest that the regions of condensed nuclear DNA in dinoflagellates may not represent whole chromosomes, and so chromosome counts are considered inappropriate for defining Symbiodinium taxa.
INHIBITION OF FERTILIZATION IN FUCUS (PHAEOPHYCEAE) BY A MONOCLONAL ANTIBODY THAT BINDS TO DOMAINS ON THE EGG CELL SURFACE1
Authors: Stafford Christopjher J , Callow James A. , Green Jonathan R.
Published: October 2004

Fertilization in the brown alga Fucus serratus L. involves interactions between sperm and eggs and in species‐specific. Recent results with monoclonal antibodies(MAbs FS4 and FS5) that recognize glycoproteins on the Fucus egg cell surface have shown that different sets of glycoproteins are organized into distinct domains. Thus, regions on the egg surface are FS4+FS5− and FS4−FS5+, and some smaller regions are FS4+FS+. To determine functional differences between these domains, MAbs FS4 and FS5 were included in a fertilization assay, Purified FS5 antibody, which is an immunoglobulin class M (IgM), inhibited fertilization, whereas FS4 IgM had no effect, Fragment antigen‐binding fragment, which suggests that the effects were not due to steric hindrance by large IgM molecules or to cross‐linking of receptors. FS5 inhibited fertilization in both F. serratus and F. vesiculosus; therefore, its effect was not species‐specific, Thus we show that there is functional heterogeneity of the Fucus egg cell surface and compare our results to previous reports on inhibitory effects of lectins, Overall, the evidence suggests that there may be two levels of interaction between gametes in Fucus involoving nonspecific and species‐specific binding.
ULTRASTRUCTURE OF CHRYSODIDYMUS SYNUROIDEUS (SYNUROPHYCEAE)1
Authors: Graham Linda E. , Graham James M. , Wujek Daniel E.
Published: October 2004

A clonal isolate of Chrysodidymus synuroideus Prowse was derived form a Sphagnum bog in northern Wisconsin and maintained in culture for over 3 years. Cultured colonies consisted almost exclusively of two cells attached at the posterior, each cell bearing two unequal flagella. Correlative light and electron microscopic observations revealed that colonies composed of smaller, ovate cells represented more recent products of cell division, while colonies of elongate cells were more mature. These results support previous taxonomic conclusions, based on light microscopic observations, of field‐collected specimens and body scale ultrastructure, that Chrysodidymus is a valid genus, and that two species described by Prowse on the basis of cell size differences, should be merged. In addition, ultrastructural studies of cultured Chrysodidymus demonstrated that this genus is a member of the Synurophyceae on the basis of characters related to flagellar morphology, basal body arrangement, and cytoskeletal ultrastructure. Chrysodidymus synuroideus resembles Synura sphagnicola in body scale structure, the presence of distinctive linear or clavate scales on both flagella, a relatively loose scale case, and acidophilic habital, Unlike S. sphagnicola, Chrysodidymus has no Pyrennoids, Peripheral (rather than axial) plastids, and a single posterior storage vesicle (rather than two peripheral storage vesicles).
ASEXUAL AND SEXUAL REPRODUCTION IN GONIUM QUADRATUM (CHLOROPHYTA) WITH A DISCUSSION OF PHYLOGENETIC RELATIONSHIP WITHIN THE GONIACEAE1
Authors: Nozaki Hisayoshi
Published: October 2004

Morphological details of asexual and sexual reproduction in Gonium Quadratum Pringsheim ex Nozaki (Goniaceae, Chlorophyta) were observed by light microscopy, based on clonal cultured materials originating from Nepal. In asexual reproduction, the alga exhibited two different patterns of cell cleavage during formation of 8‐and 16‐celled daughter colonies. Sexual reproduction was heterothallic and isogamous. The gametes bore a tubular mating structure (bilateral mating papilla) at the base of the flagella, and the papillae of the two gametes. The germinating zygote gave rise to four biflagellate gone cells joined in a colony (germ colony). Possible phylogenetic relationships within the Goniaceae at the species level are outlined, mainly on the basis of reproduction characteristics.
PRODUCTION OF AXENIC CULTURES OF MICROMONAS PUSILLA (PRASINOPHYCEAE) USING ANTIBIOTIC 1
Authors: Cottrell Matthew T. , Suttle Curtis A.
Published: October 2004

Bacteria‐free cultures of the prasinophyte Micromonas pusilla (Butcher) Monton and Parke, UTEX LB 991, were produced by intially determining the effects of several antibiotics on the growth of this alga and then using a combination of these antibiotics to eliminate associated bacteria, Micrononas pusilla was resistant ot penicillin G, neomycin, gentamicin and streptomycin at bactericidal concentrations but sensitive to chloramphenicol and polymixin B. Passage of M. pusilla through the sequence of antibioties penicillin G → neomycin → gentamician → kanamycin resulted in an axenic culture of M, pusilla this method should be suitable for producing axenic culture of other strains of M. pusilla.