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  • Articles  (136)
  • mitochondria  (53)
  • Triticum aestivum
  • fish
  • Springer  (136)
  • 1995-1999  (136)
  • 1997  (136)
  • 1
    Electronic Resource
    Electronic Resource
    Early signs of disruption of wheat anther development associated with the induction of male sterility by meiotic-stage water deficit (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 40-48 
    Details
    ISSN: 1432-2145
    Keywords: Key words Male sterility ; Starch ; Triticum aestivum ; Water stress ; Anther ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Water deficit during meiosis in microspore mother cells of wheat (Triticum aestivum L.) induces male sterility, which reduces grain yield. In plants stressed during meiosis and then re-watered, division of microspore mother cells seems to proceed normally, but subsequent pollen development is arrested. Stress-affected anthers generally lack starch. We employed light microscopy in conjunction with histochemistry to compare the developmental anatomy of water-stress-affected and normal anthers. The earliest effects of stress, detectable between meiosis and young microspore stages, were the degeneration of meiocytes, loss of orientation of the reproductive cells, and abnormal vacuolization of tapetal cells. Other effects observed during subsequent developmental stages were deposition of starch in the connective tissue where it is normally not present, hypertrophy of the middle layer or endothecial cells, and deposition of sporopollenin-like substances in the anther loculus. The resulting pollen grains lacked both starch and intine. These results suggest that abnormal degeneration of the tapetum in water-stressed anthers coupled with a loss of orientation of the reproductive cells could be part of early events leading to abortion of microspores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050066
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro development of wheat (Triticum aestivum L.) from zygote to plant via ovule culture (1997)
    Springer
    Plant cell reports 16 (1997), S. 663-667 
    Details
    ISSN: 1432-203X
    Keywords: Key words Embryogenesis ; Ovule culture ; Triticum aestivum ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ovules of the wheat breeding line Veery #5 were excised and transferred to culture within 24 h after pollination. When ovules were cultured on Phytagel-solidified medium, and the pericarp removed exclusively at the micropylar tip and the abaxial side, zygotes from up to 79.2% of the ovules underwent embryogenesis with the same developmental pattern as found in planta. Embryos from more than 50% of the cultured ovules germinated when transferred to regeneration medium. More than 100 plantlets were randomly chosen for transfer to soil, all of which developed to phenotypically normal and fertile plants. With this system, the entire process of zygotic embryogenesis can be studied using living material. Furthermore, the method could be used as an embryo rescue technique for plant breeding purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050298
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of light on the accumulation of abscisic acid and expression of an early cysteine-labeled metallothionein gene in microspores of Triticum aestivum during induced embryogenic development (1997)
    Springer
    Plant cell reports 16 (1997), S. 458-463 
    Details
    ISSN: 1432-203X
    Keywords: Key words Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01092766
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of oxidative phosphorylation genes in muscle cell cultures from patients with mitochondrial myopathies (1997)
    Springer
    Molecular and cellular biochemistry 168 (1997), S. 73-85 
    Details
    ISSN: 1573-4919
    Keywords: muscular diseases ; mitochondria ; MTDNA ; ATP synthase ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of several mitochondrial and nuclear genes involved in ATP production was examined in cells cultured from muscle biopsies of patients harboring mitochondrial pathologies. The transcript patterns in muscle cells from the patients affected by carnitine palmitoyl transferase II or 2-ketoglutarate dehydrogenase deficiencies were almost similar to control patterns. In the opposite, patterns were strikingly abnormal in all the other cell cultures from patients with defects in enzymatic complexes involved in oxidative phosphorylation: mitochondrial complex II and III deficiencies, two MELAS syndromes (myopathy, encephalopathy, lactic acidosis and stroke like episodes), a case of Kearns-Sayre syndrome and a case of chronic progressive external ophthalmoplegia. In cultured muscle cells from patients with mtDNA mutations, the percentage of mutated mtDNA was low as compared with those determined in the corresponding skeletal muscle biopsy. Moreover, the complex II defect resulting of a nuclear mutation was not expressed in the cell cultures. Thus, an undetermined transcriptional event, transmitted from muscle biopsies to cultured muscle cells, should be involved to account for such abnormal transcript patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006830807107
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  • 5
    Electronic Resource
    Electronic Resource
    Lipid peroxidation induced by a novel porphyrin plus light in isolated mitochondria: Possible implications in photodynamic therapy (1997)
    Springer
    Molecular and cellular biochemistry 166 (1997), S. 25-33 
    Details
    ISSN: 1573-4919
    Keywords: porphyrin derivative ; mitochondria ; ascites ; singlet oxygen ; photosensitization ; lipid peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract With a view to locate porphyrins for use in photodynamic therapy (PDT), the new modality of cancer treatment we have evaluated the ability of a novel water soluble porphyrin meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP) to induce damage to mitochondria during photosensitization. T4CPP, when exposed to visible light, induced lipid peroxidation in rat liver mitochondria as assessed by the formation of thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (LOOH). The effect on mitochondrial function was assessed by estimating the activity of succinate dehydrogenase (SDH). The peroxidation induced was observed to be time- and concentration- dependent. Analysis of product formation and selective inhibition by scavengers of reactive oxygen species showed that the oxidative damage observed was mainly due to singlet oxygen (1O2) and partly due to other reactive species. T4CPP plus light also caused significant lipid peroxidation in Sarcoma 180 ascites tumour mitochondria. Our studies indicate that T4CPP has the potential to photoinduce damage in hepatic and ascites mitochondria, a crucial site of damage in PDT. (Mol Cell Biochem 166: 25-33, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006840714583
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  • 6
    Electronic Resource
    Electronic Resource
    Mitochondrial involvement in the ageing process. Facts and controversies (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 325-328 
    Details
    ISSN: 1573-4919
    Keywords: ageing ; theory ; mitochondria ; respiratory chain ; mitochondrial DNA mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondria are believed to be involved in human ageing. Whilst it is clear that various mitochondrial DNA mutations do accumulate in human tissues with age, whether or not they interfere with respiratory chain function is uncertain. We question the results of previous studies which have measured respiratory chain function in human skeletal muscle with age. Whilst cytochrome c oxidase deficient fibres are a real finding in skeletal muscle, the contribution of mitochondrial DNA mutations to human ageing is still controversial. Our results show for mitochondria to be involved in ageing then it must be through a more subtle mechanism than a global decline in respiratory chain function. (Mol Cell Biochem 174: 325–328, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006847319162
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  • 7
    Electronic Resource
    Electronic Resource
    Transcription of mitochondrial and mitochondria-related nuclear genes in rabbit bladder following partial outlet obstruction (1997)
    Springer
    Molecular and cellular biochemistry 173 (1997), S. 1-8 
    Details
    ISSN: 1573-4919
    Keywords: outlet obstruction ; bladder ; mitochondria ; transcription ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Using the rabbit model, we showed that partial outlet obstruction of theurinary bladder causes significant changes in the status and expression ofthe mitochondrial (mt) genetic system in bladder smooth muscle immediatelyafter obstruction is initiated. Here we investigate quantitatively theseverity of the mt genetic response to partial outlet obstruction in bothshort- and long-term obstructed rabbits. Based on previous functionalstudies, bladders with mass 〈 6 fold greater than control were consideredcompensated; bladders with mass 〉 6 fold that of control were considereddecompensated. Analyses of DNA from compensated rabbit bladders showed thatrelative mt genome copy number decreased to 30% of control values.Transcript analyses for these samples showed that mt RNA levels increased 3fold to compensate for lower template copy number. Analysis of decompensatedbladders demonstrated that mt genome copy number increased to approximately90% of control levels; mt transcripts progressively decreased inthese samples by as much as 30 fold. In contrast, transcription of amt-related nuclear gene decreased 3-9 fold in compensated bladders butincreased 10-30 fold in decompensated bladders. Activity for the cytochromeoxidase complex, and for the mt enzyme citrate synthase, decreased steadilywith increasing bladder hypertrophy. These data suggest that bladderdysfunction following partial outlet obstruction is mediated partly by asignificant loss in mt and mt-related nuclear gene coordination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006890527552
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  • 8
    Electronic Resource
    Electronic Resource
    Oxidative phosphorylation in myocardial mitochondria 'in situ': a calorimetric study on permeabilized cardiac muscle preparations (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 101-113 
    Details
    ISSN: 1573-4919
    Keywords: calorimetry ; cardiac muscle ; mitochondria ; oxidative phosphorylation ; atractyloside ; dinitrophenol ; ectonucleotidase ; respiratory control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A novel flow calorimetric technique was developed to study the energy turnover of myocardial mitochondria. Cylindrical strands of cardiac muscle (trabeculae) weighing 100–500 µg were isolated from guinea-pig heart and mounted in a tubular recording chamber which was continuously perfused with physiological salt solution at 37°C. The temperature difference between the upstream and the downstream side of the chamber, which is proportional to the rate of heat production of the trabecula, was measured at high resolution. In this way the rate of energy expenditure of isolated cardiac muscle could be recorded continuously for several hours. When the preparations were superfused with an 'intracellular' solution containing 5 mM pyruvate and 2 mM malate as substrates, permeabilization of the sarcolemma with 25 µM digitonin induced a marked increase in the measured heat rate in the presence of 2 mM ADP. The major fraction of the ADP sensitive heat production (83%) could be blocked with 400 µM at ractyloside, an inhibitor of the adeninenucleotide translocase, and by 600 µM α-cyano-4-hydroxycinnamate, an inhibitor of monocarboxylate/H+ co-transport. The atractyloside sensitive heat production was abolished in anoxic solution. These results suggest that the atractyloside-sensitive heat production (21.8 ± 3.5 mW cm-3 of tissue) was attributable to oxidative phosphorylation. The mitochondria apparently remained intact after treatment with digitonin, since application of the uncoupler 2,4-dinitrophenol (DNP) produced a very large increase in heat rate. A minor fraction of the heat rate induced by ADP in permeabilized cardiac muscle preparations (17%) was not sensitive to atractyloside. This component was also seen before application of digitonin and was probably related to ectonucleotidases. In conclusion, our calorimetric technique allows investigation of the energy metabolism of myocardial mitochondria 'in situ', i.e. without destroying the microarchitecture of cardiac muscle cells. (Mol Cell Biochem 174: 101–113, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006838509090
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  • 9
    Electronic Resource
    Electronic Resource
    Two modes of activation of the permeability transition pore: The role of mitochondrial cyclophilin (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 181-184 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; cyclosporin ; cyclophilin ; channels ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondria possess an inner membrane channel, the permeability transition pore, which is inhibited by cyclosporin A (CBA) and by matrix protons. As suggested recently by our laboratory, pore closure by these inhibitors may be due to dissociation of mitochondrial cyclophilin (CyP-M), a matrix peptidyl-prolyl-cis-trans isomerase, from its putative binding site on the pore. Unbinding of CyP-M would follow a CsA-dependent or proton-dependent change in conformation of the CyP-M molecule. It is interesting that upon binding of CsA the enzymatic activity of CyP-M is inhibited, but it is not clear whether this event plays a role in pore inhibition. Here we report experiments designed to further test the role of CyP-M in pore function. Our results indicate that CyP-M-dependent and independent mechanisms of pore activation may exist, and that the peptidylprolyl-cis-trans-isomerase activity of CyP-M is not necessarily involved in pore modulation by CyP-M. (Mol Cell Biochem 174: 181–184, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006887921810
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  • 10
    Electronic Resource
    Electronic Resource
    Hormonal stimulation, mitochondrial Ca2+ accumulation, and the control of the mitochondrial permeability transition in intact hepatocytes (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 173-179 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; calcium ; permeability transition ; vasopressin ; glucagon ; thapsigargin ; protein kineses and phosphatases ; rat hepatocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Ca2+ functions as an intracellular signal to transfer hormonal messages to different cellular compartments, including mitochondria, where it activates intramitochondrial Ca2+-dependent enzymes. However, excessive mitochondrial Ca2+ uptake can promote the mitochondrial permeability transition (MPT), a process known to be associated with cell injury. The factors controlling mitochondrial Ca2+ uptake and release in intact cells are poorly understood. In this paper, we investigate mitochondrial Ca2+ accumulation in intact hepatocytes in response to the elevation of cytosolic Ca2+ levels ([Ca2+]c) induced either by a hormonal stimulus (vasopressin), or by thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ pump. After stimulation, cells were rapidly permeabilized for the determination of the mitochondrial Ca2+ content (Ca2+_m) and to analyze the susceptibility of the mitochondria to undergo the MPT. Despite very similar levels of [Ca2+]c elevation, vasopressin and thapsigargin had markedly different effects on mitochondrial Ca2+ accumulation. Vasopressin caused a rapid (〈 90 sec), but modest (〈 2 fold) increase in Ca2+m that was not further increased during prolonged incubations, despite a sustained [Ca2+]c elevation. By contrast, thapsigargin induced a net Ca2+ accumulation in mitochondria that continued for up to 30 min and reached Ca2+_m levels 10–20 fold over basal. Accumulation of mitochondrial Ca2+ was accompanied by a markedly increased susceptibility to undergo the MPT. Both mitochondrial Ca2+ accumulation and MPT activation were modulated by treatment of the cells with inhibitors of protein kineses and phosphatases. The results indicate that net mitochondrial Ca2+ uptake in response to hormonal stimulation is regulated by processes that depend on protein kinase activation. These controls are inoperative when the cytosol is flooded by Ca2+ through artificial means, enabling mitochondria to function as a Ca2+ sink under these conditions. (Mol Cell Biochem 174: 173–179, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006831703155
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  • 11
    Electronic Resource
    Electronic Resource
    Point mutations in the mitochondrial tRNALys gene: Implications for pathogenesis and mechanism (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 215-219 
    Details
    ISSN: 1573-4919
    Keywords: MERRF ; mitochondria ; mtDNA ; genetics ; tRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract MERRF (myoclonic epilepsy with ragged-red fibers) is a severe, multisystem disorder characterized by myoclonus, seizures, progressive cerebellar syndrome, muscle weakness, and the presence of ragged-red fibers in the muscle biopsy. MERRF is associated with heteroplasmic point mutations, either A8344G or T8356C, in the gene encoding the mitochondrial tRNALys. The human ro cell system was utilized to examine the phenotypic consequences of these mutations, and to investigate their molecular genetic causes. Wild-type and mutant transmitochondrial cell lines harboring a pathogenic point mutation at either A8344G or T8356C in the human mitochondrial tRNALys gene were isolated and examined. Mitochondrial transformants containing 100% mutated mitochondrial DNAs (mtDNAs) exhibited severe defects in respiratory chain activity, in the rates of protein synthesis, and in the steady-state levels of mitochondrial translation products as compared with mitochondrial transformants containing 100% wild-type mtDNAs. In addition, both mutant cell lines exhibited the presence of aberrant mitochondrial translation products. These results demonstrate that two different mtDNA point mutations in tRNALys result in fundamentally identical defects at the cellular level, and that these specific protein synthesis abnormalities contribute to the pathogenesis of MERRF. (Mol Cell Biochem 174: 215–219, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006808524536
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  • 12
    Electronic Resource
    Electronic Resource
    Alterations in susceptibility to carbon tetrachloride toxicity and hepatic antioxidant/detoxification system in streptozetocin-induced short-term diabetic rats: Effects of insulin and Schisandrin B treatment (1997)
    Springer
    Molecular and cellular biochemistry 175 (1997), S. 225-232 
    Details
    ISSN: 1573-4919
    Keywords: diabetes ; carbon tetrachloride ; liver toxicity ; glutathione ; mitochondria ; Schisandra chinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The streptozotocin-induced short-term (2 week) diabetic rats showed an increase in susceptibility to carbon tetrachloride (CCl4)-induced hepatocellular damage. This diabetes-induced change was associated with a marked impairment in the hepatic glutathione antioxidant/detoxification response to CCl4 challenge, as indicated by the abrogation of the increases in hepatic reduced glutathione (GSH) level, glucose-6-phosphate dehydrogenase and microsomal glutathione S-transferases (GST) activities upon challenge with increasing doses of CCl4. While the hepatic GSH level was increased in diabetic rats, the hepatic mitochondrial GSH level and Se-glutathione peroxidase activity were significantly reduced. Insulin treatment could reverse most of the biochemical alterations induced by diabetes. Both insulin and schisandrin B (Sch B) pretreatments protected against the CCl4 hepatotoxicity in diabetic rats. The hepatoprotection was associated with improvement in hepatic glutathione redox status in both cytosolic and mitochondrial compartments, as well as the increases in hepatic ascorbic acid level and microsomal GST activity. The ensemble of results suggests that the diabetes-induced impairment in hepatic mitochondrial glutathione redox status may at least in part be attributed to the enhanced susceptibility to CCl4 hepatotoxicity. Sch B may be a useful hepatoprotective agent against xenobiotics-induced toxicity under the diabetic conditions. (Mol Cell Biochem 175: 225–232, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006883919687
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  • 13
    Electronic Resource
    Electronic Resource
    The use of confocal microscopy in the investigation of cell structure and function in the heart, vascular endothelium and smooth muscle cells (1997)
    Springer
    Molecular and cellular biochemistry 172 (1997), S. 171-194 
    Details
    ISSN: 1573-4919
    Keywords: heart ; vascular endothelium ; vascular smooth muscle ; confocal microscopy ; pH ; calcium ; sodium ; voltage probe ; heart ; endothelin-1 ; Angiotensin II ; PAF ; nucleus ; mitochondria ; SR ; cardiomyopathy ; cells interaction ; R-type Ca2+ channel ; excitation-contraction coupling ; dystrophic mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In recent years, fluorescence microscopy imaging has become an important tool for studying cell structure and function. This non invasive technique permits characterization, localisation and qualitative quantification of free ions, messengers, pH, voltage and a pleiad of other molecules constituting living cells. In this paper, we present results using various commercially available fluorescent probes as well as some developed in our laboratory and discuss the advantages and limitations of these probes in confocal microscopy studies of the cardiovascular system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006840228104
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  • 14
    Electronic Resource
    Electronic Resource
    Reversibility of thiamine deficiency-induced partial necrosis and mitochondrial uncoupling by addition of thiamine to neuroblastoma cell suspensions (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 121-124 
    Details
    ISSN: 1573-4919
    Keywords: thiamine deficiency ; mitochondria ; energy metabolism ; necrosis ; neuroblastoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Culture of neuroblastoma cells in the presence of low thiamine concentration (6 nM) and of the transport inhibitor amprolium leads to the appearance of signs of necrosis: the chromatin condenses, the oxygen consumption decreases and is uncoupled, the mitochondrial cristae are disorganized, the thiamine diphosphate-dependent dehydrogenase activities are impaired. When 10 µM thiamine are added to these cells, the basal respiration increases, the coupled respiration is restored and mitochondrial morphology is recovered within 1 h. Addition of succinate, which is oxidized via a thiamine diphosphate-independent dehydrogenase, to digitonin-permeabilized cells immediately restores a coupled respiration. Our results suggest that the slowing of the citric acid cycle is the cause of the biochemical lesion induced by severe thiamine deficiency and that part of the mitochondria remain functional. (Mol Cell Biochem 174: 121–124, 1997)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006842609998
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  • 15
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    Nitric oxide inhibition of cytochrome oxidase and mitochondrial respiration: Implications for inflammatory, neurodegenerative and ischaemic pathologies (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 189-192 
    Details
    ISSN: 1573-4919
    Keywords: nitric oxide ; mitochondria ; inflammation ; respiration ; astrocytes ; cytochrome oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Nitric oxide (NO) at high levels is cytotoxic, and may be involved in a range of inflammatory, neurodegenerative, and cardiovascular/ischaemic pathologies. The mechanism of NO-induced cytotoxicity is unclear. Recently we and others have found that low (nanomolar) levels of NO reversibly inhibit mitochondrial respiration by binding to the oxygen binding site of cytochrome oxidase in competition with oxygen. This raises the apparent Km for oxygen of mitochondrial respiration into the physiological range, potentially making respiration sensitive to the oxygen level. The NO inhibition of oxygen consumption was seen in isolated cytochrome oxidase, mitochondria, brain nerve terminals, and cultured cells. Cultured astrocytes activated to express the inducible form of NO synthase produced up to 1 µM NO and strongly inhibited their own cellular respiration rate. This respiratory inhibition was rapidly reversed by removing the NO, and was due to the inhibition of cytochrome oxidase. These results suggest that any cell producing high levels of NO will inhibit its own respiration and that of surrounding cells, and make the respiration rate sensitive to the oxygen level. This inhibition of energy metabolism may contribute to cytotoxity or cytostasis in some pathologies. (Mol Cell Biochem 174: 189–192, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006800322719
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  • 16
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    Identification of mitochondrial deficiency using principal component analysis (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 149-156 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; mitochondrial myopathies ; oxidative phosphorylation ; principal component analysis (PCA) ; biplot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The mitochondrial pathologies are a heterogeneous group of metabolic disorders that are characterized by anomalies of oxidative phosphorylation, especially in the respiratory chain. The diagnosis of these pathologies involves many investigations among which biochemical study is at present the main tool. However, the analysis of the results obtained during such study remains complex and often does not make it possible to conclude clearly if a patient is affected or not by a biochemical and/or bioenergetic deficiency. This arises from two main problems: 1. The determination of control values from the whole set of variable values (affected and unaffected people). 2. The small size of the population studied and the large number of variables collected which present a rather large variability. To cope with these problems, the principal component analysis method is applied to the results obtained during our biochemical studies. This analysis makes it possible for each respiratory chain complex, to distinguish clearly two subsets of the whole population (affected and unaffected people) as well as to detect the variables which are the most discriminative. (Mol Cell Biochem 174: 149–156, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006840218253
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  • 17
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    Mitochondrial, but not peroxisomal, β-oxidation of fatty acids is conserved in coenzyme A-Deficient rat liver (1997)
    Springer
    Molecular and cellular biochemistry 175 (1997), S. 37-42 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; peroxisomes ; fatty acids metabolism ; coenzyme A deficiency ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Hepatic coenzyme A (CoA) plays an important role in cellular lipid metabolism. Because mitochondria and peroxisomes represent the two major subcellular sites of lipid metabolism, the present study was designed to investigate the specific impact of hepatic CoA deficiency on peroxisomal as well as mitochondrial β-oxidation of fatty acids. CoA deficiency (47% decrease in free CoA and 23% decrease in total CoA) was produced by maintaining weanling male Sprague-Dawley rats on a semipurified diet deficient in pantothenic acid (the precursor of CoA) for 5 weeks. Hepatic mitochondrial fatty acid oxidation of short-chain and long-chain fatty acids were not significantly different between control and CoA-deficient rats. Conversely, peroxisomal poxidation was significantly diminished (38% inhibition) in livers of CoA-deficient rats compared to control animals. Peroxisomal β-oxidation was restored to normal levels when hepatic CoA was replenished. It is postulated that since the role of hepatic mi tochondrial β-oxidation is energy production while peroxisomal β-oxidation acts mainly as a detoxification system, the mitochondrial pathway of β-oxidation is spared at the expense of the peroxisomal pathway when liver CoA plummets. The present study may offer an animal model to investigate mechanisms involved in peroxisomal diseases. (Mol Cell Biochem 175: 37–42, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006877021617
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  • 18
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    Are Tropical Herbivores More Resistant Than Temperate Herbivores to Seaweed Chemical Defenses? Diterpenoid Metobolites from Dictyota acutiloba as Feeding Deterrents for Tropical Versus Temperate Fishes and Urchins (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 289-302 
    Details
    ISSN: 1573-1561
    Keywords: Acutilol diterpenes ; biogeography ; chemical defenses ; Dictyota ; diffuse coevolution ; fish ; plant–herbivore interactions ; sea urchin ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Because herbivory is more intense in the tropics, tropical seaweeds may be better defended against herbivory than are temperate seaweeds. A “diffuse” coevolutionary corollary to this hypothesis is that tropical herbivores should be more resistant to seaweed defenses than temperate herbivores because tropical herbivores more commonly encounter heavily defended seaweeds. We begin to test the latter prediction using three newly discovered diterpenoid secondary metabolites from the tropical brown alga Dictyota acutiloba. We tested the feeding deterrent properties of these compounds against common herbivorous fishes and sea urchins from warm-temperate North Carolina versus tropical Guam using standardized laboratory feeding assays. The temperate herbivores were deterred by lower concentrations of secondary metabolites than the tropical herbivores. In no case was a tropical herbivore more deterred by a compound than a temperate herbivore, suggesting that temperate herbivores may be more strongly affected by seaweed chemical defenses. Feeding by the temperate pinfish Lagodon rhomboides was significantly reduced by two of the three diterpenes at a concentration that was only 13–18% of the natural concentration found in the alga. Feeding by four species of tropical fishes (two parrotfishes and two surgeonfishes) was unaffected by metabolite concentrations that deterred the temperate fish. At 100% of natural concentrations, only one of the three compounds deterred the two parrotfishes, and none of the three compounds deterred the surgeonfishes. Contrasts between the temperate sea urchin Arbacia punctulata and the tropical sea urchin Diadema savignyi showed a similar pattern; low concentrations of acutilol A acetate strongly deterred the temperate, but not the tropical, urchin. Tropical herbivores appear more resistant than temperate herbivores to seaweed chemical defenses.
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    URL: http://dx.doi.org/10.1023/B:JOEC.0000006360.36833.13
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    WHOLE-CATCHMENT LIMING AT TJØNNSTROND, NORWAY: AN 11-YEAR RECORD (1997)
    Springer
    Water, air & soil pollution 94 (1997), S. 163-180 
    Details
    ISSN: 1573-2932
    Keywords: acid deposition ; liming ; catchment ; lake ; water chemistry ; fish ; soil ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In June 1983 a whole-catchment liming experiment was conducted at Tjønnstrond, southernmost Norway, to test the utility of terrestrial liming as a technique to restore fish populations in remote lakes with short water-retention times. Tjønnstrond consists of 2 small ponds of 3.0 and 1.5 ha in area which drain a 25-ha catchment. The area is located at about 650–700 meters above sea-level in sparse and unproductive forests of spruce, pine and birch with abundant peatlands. A dose of 3 ton/ha of powdered limestone were spread by helicopter to the terrestrial area. No limestone was added to the ponds themselves. The ponds were subsequently stocked with brown and brook trout. Liming caused large and immediate changes in surface water chemistry; pH increased from 4.5 to 7.0, Ca increased from 40 to 200 μeq/L, ANC increased from –30 to +70 μeq/L, and reactive-Al decreased from about 10 to 3 μmol/L. During the subsequent 11 years the chemical composition of runoff has decreased gradually back towards the acidic pre-treatment situation. The major trends in concentrations of runoff Ca, ANC, pH, Al and NO3 in runoff are all well simulated by the acidification model MAGIC. Neither the measured data nor the MAGIC simulations indicate significant changes in any other major ion as a result of liming. The soils at Tjønnstrond in 1992 contained significantly higher amounts of exchangeable Ca relative to those at the untreated reference catchment Storgama. In 1992 about 75% of the added Ca remains in the soil as exchangeable Ca, 15% has been lost in runoff, and 10% is unaccounted for. The whole-catchment liming experiment at Tjønnstrond clearly demonstrates that this liming technique produces a long-term stable and favourable water quality for fish. Brown trout in both ponds in 1994 have good condition factors, which indicate that the fish are not stressed by marginal water quality due to re-acidification. The water quality is still adequate after 11 years and 〉20 water renewals. Concentrations of H+ and inorganic Al have gradually increased and approach levels toxic to trout, but the toxicity of these are offset by the continued elevated Ca concentrations. Reduced sulphate deposition during the last 4 years (1990–94) has also helped to slow and even reverse the rate of reacidification. The experiment at Tjønnstrond demonstrates that for this type of upland, remote terrain typical of large areas of southern Norway, terrestrial liming offers a suitable mitigation technique for treating acidified surface waters with short retention times.
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    URL: http://dx.doi.org/10.1023/A:1026442821924
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    Structural and functional impairment of the hypothalamo- pituitary-interrenal axis in fish exposed to bleached kraft mill effluent in the St Maurice River, Quebec (1997)
    Springer
    Ecotoxicology 6 (1997), S. 1-12 
    Details
    ISSN: 1573-3017
    Keywords: cortisol ; BKME ; fish ; interrenal ; pituitary ; morphol ogy ; acute stress ; endocrine dysfunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effects of bleached kraft mill effluent (BKME) on blood cortisol levels and the morphology of the pituitary-interrenal axis were investigated in two species of teleost fish, the northern pike, Esox lucius, and the yellow perch, Perca flavescens, sampled upstream and downstream from a pulp and paper mill on the St Maurice River, Quebec. Fish were acutely stressed by a standardized capture and sampling protocol at both sites, and their ability to elevate blood cortisol levels in response to the capture stress was compared. Blood cortisol levels in fish from the upstream site (〉100 ng/ml plasma) were higher than the levels in fish from the BKME site, and the pituitary corticotropes and the interrenal steroidogenic cells of the upstream fish were larger and had larger nuclei compared with cells from the downstream fish. The low blood cortisol levels in fish exposed to BKME were correlated to cellular atrophy within the hypothalamo-pituitary-interrenal (HPI) axis. The reduced ability to elevate blood cortisol in response to an acute stress may be an endocrine dysfunction occuring in fish chronically exposed to chemical stressors in their environment
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    URL: http://dx.doi.org/10.1023/A:1018699405158
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    Insulin as a probe of mitochondrial metabolism in situ (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 91-96 
    Details
    ISSN: 1573-4919
    Keywords: insulin ; mitochondria ; Krebs cycle ; pyruvate ; succinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Our previous studies of insulin action have led us to the finding that insulin acts specifically on the mitochondrial Krebs cycle to stimulate, by 30%, the oxidation of carbons 2 and 3 of pyruvate to CO2. Insulin also stimulates the oxidation of both carbons of acetate. These carbons can be converted to CO2 only after passing through all of the reactions of the Krebs cycle more than once. Carboxyl groups, such as number 1 of pyruvate, are oxidized to CO2 without any effect of insulin, and can be converted to CO2 by extramitochondrial enzyme. We conclude that insulin must act on the complete intramitochondrial cycle and not on the four enzymes of the Krebs cycle which are present in the cytoplasm. The path taken by those carbons affected by insulin is traced through the complete Krebs cycle, and the necessity for this effect to be mitochondrial has been verified by demonstration of the same specific effect of insulin on the oxidation of the 2 and 3 carbons of succinate. The use of this phenomenon is proposed for the study not only of human diabetes, but of all mitochondrial disorders, by using 14C specifically labeled tracers in culture or biopsy material, or 13C labeled tracer material in vivo. (Mol Cell Biochem 174: 91–96, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006834408181
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    Inhibition of complex I by neuroleptics in normal human brain cortex parallels the extrapyramidal toxicity of neuroleptics (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 255-259 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; neuroleptics ; oxidative phosphorylation ; complex I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract There is increasing evidence that a defect of the mitochondrial respiratory chain is implicated in the development of Parkinson disease. Decreased complex I activity of the mitochondrial respiratory chain has been reported in platelets, muscle, and brain of patients with Parkinson disease. Extrapyramidal symptoms (e.g. parkinsonism and dystonic reactions) are major limiting side effects of neuroleptics. Experimental evidence suggests that neuroleptics inhibit complex I in rat brain. There has not been a study of the effects of neuroleptics in human tissue, however. We therefore analyzed the activities of complexes I + III, complexes II + III, succinate dehydrogenase, complex IV (cytochrome c oxidase), and of citrate synthase in normal human brain cortex after the addition of haloperidol and chlorpromazine and the atypical neuroleptics risperidone, zotepine, and clozapine. Activity of complex I was progressively inhibited by all neuroleptics. Half maximal inhibition (IC50) was 0.1 mM fo r haloperidol, 0.4 mM for chlorpromazine, and 0.5 mM for risperidone and zotepine. Clozapine had no effect on enzyme activity at concentrations up to 0.5 mM, followed by a slow decline with a maximum inhibition of 70% at 10 mM. IC50 was at about 2.5 mM. Thus, the concentration of clozapine needed to cause 50% inhibition of the activity of complexes I and III was about 5 times that of zotepine and risperidone, about 6 times that of chlorpromazine, and 25 times that of haloperidol. The inhibition thus paralleled the incidence of extrapyramidal effects caused by the different neuroleptics as they are known from numerous clinical studies. Our data support the hypothesis that neuroleptic-induced extrapyramidal side effects may be due to inhibition of the mitochondrial respiratory chain. (Mol Cell Biochem 174: 255–259, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006872911332
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    Mitochondrial abnormalities and peripheral europathy in inflammatory myopathy, especially inclusion body myositis (1997)
    Springer
    Molecular and cellular biochemistry 174 (1997), S. 277-281 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; myopathy ; inclusion body myositis ; neuropathy ; vasculitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Computer retrieval in a database, comprising 7,225 muscle cases, revealed that mitochondrial myopathies do not occur more frequently in inflammatory myopathies (3.74%) than in the whole series (3.69%). A more detailed study of inclusion body myositis (IBM), however, showed that severe mitochondrial alterations were apparent in about twice as many IBM cases as expected. This confirms recent studies of others although a causal relationship has thus far not been established. Identification of mitochondrial deletions by Southern blotting corresponded to the presence of severe structural abnormalities of mitochondria. Peripheral neuropathy of variable severity was noted in all cases of IBM and mitochondrial myopathy. By contrast, the association of severe mitochondrial abnormalities with polymyositis, systemic scleroderma, and vasculitis observed in some cases of the present series may be incidental or age dependent. (Mol Cell Biochem 174: 277–281, 1997)
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    URL: http://dx.doi.org/10.1023/A:1006829129079
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    Hg(II)-induced renal cytotoxicity: In vitro and in vivo implications for the bioenergetic and oxidative status of mitochondria (1997)
    Springer
    Molecular and cellular biochemistry 177 (1997), S. 53-59 
    Details
    ISSN: 1573-4919
    Keywords: mercury ; rat kidney ; mitochondria ; oxidative phosphorylation ; FoF1-ATPase ; ATP synthesis ; ATP hydrolysis ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of Hg(II) on bioenergetic and oxidative status of rat renal cortex mitochondria were evaluated both in vitro, and in vivo 1 and 24 h after treatment of animals with 5 mg HgCl2/kg ip. The parameters assessed were mitochondrial respiration, ATP synthesis and hydrolysis, glutathione content, lipid peroxidation, protein oxidation, and activity of antioxidant enzymes. At low concentration (5 µM) and during a short incubation time, Hg(II) uncoupled oxidative phosphorylation while at slightly higher concentration or longer incubation time the ion impaired the respiratory chain. The rate of ATP synthesis and the phosphorylation potential of mitochondria were depressed, although inhibition of ATP synthesis did not exceed 50%. In vivo, respiration and ATP synthesis were not affected 1 h post-treatment, but were markedly depressed 24 h later. ATP hydrolysis by submitochondrial particle FoF1-ATPase was inhibited (also by no more than 50%) both in vitro, and in vivo 1 and 24 h post-treatment. Hg(II) induced maximum ATPase inhibition at about 1 uM concentration but did not have a strong inhibitory effect in the presence of Triton X-100. Oxidative stress was not observed in mitochondria 1 h post-treatment. However, 24 h later Hg(II) reduced the GSH/GSSG ratio and increased mitochondrial lipid peroxidation and protein oxidation, as well as inhibited GSH-peroxidase and GSSG-reductase activities. These results suggest that the following sequence of events may be involved in Hg(II) toxicity in the kidney: (1) inhibition of FoFl-ATPase, (2) uncoupling of oxidative phosphorylation, (3) oxidative stress-associated impairment of the respiratory chain, and (4) inhibition of ATP synthesis.
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    URL: http://dx.doi.org/10.1023/A:1006861319378
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    Hyperthyroidism and Mitochondrial Uncoupling (1997)
    Springer
    Bioscience reports 17 (1997), S. 17-21 
    Details
    ISSN: 1573-4935
    Keywords: Hyperthyroidism ; mitochondria ; uncoupling ; proton-leak ; pump-slip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract During the past years many efforts have been made to elucidate the origin of the uncoupling mechanisms induced by hyperthyroidism in mitochondria. Two main mechanisms have been proposed: a classical protonophoric uncoupler mechanism, considering the action of thyroid hormones at the level of the lipid membrane bilayer, and a slipping mechanism with more localized effects at the level of the redox proton pumps. This short review is devoted to comparing and discussing the evidence against and in favour of these two mechanisms.
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    The Role of Reactive Oxygen Species in Mitochondrial Permeability Transition (1997)
    Springer
    Bioscience reports 17 (1997), S. 43-52 
    Details
    ISSN: 1573-4935
    Keywords: Calcium ; cyclosporin A ; lipid peroxidation ; mitochondria ; mitochondrial membrane permeability transition ; protein oxidation ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have provided evidence that mitochondrial membrane permeability transition induced by inorganic phosphate, uncouplers or prooxidants such as t-butyl hydroperoxide and diamide is caused by a Ca2+-stimulated production of reactive oxygen species (ROS) by the respiratory chain, at the level of the coenzyme Q. The ROS attack to membrane protein thiols produces cross-linkage reactions, that may open membrane pores upon Ca2+ binding. Studies with submitochondrial particles have demonstrated that the binding of Ca2+ to these particles (possibly to cardiolipin) induces lipid lateral phase separation detected by electron paramagnetic resonance experiments exploying stearic acids spin labels. This condition leads to a disorganization of respiratory chain components, favoring ROS production and consequent protein and lipid oxidation.
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    URL: http://dx.doi.org/10.1023/A:1027335217774
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    Role of the Mitochondrial Permeability Transition Pore in Apoptosis (1997)
    Springer
    Bioscience reports 17 (1997), S. 67-76 
    Details
    ISSN: 1573-4935
    Keywords: Apoptosis ; necrosis ; mitochondria ; megachannel ; permeability transition ; programmed cell death ; poteases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mitochondrial permeability transition (PT) involves the formation of proteaceous, regulated pores, probably by apposition of inner and outer mitochondrial membrane proteins which cooperate to form the mitochondrial megachannel (=mitochondrial PT pore). PT has important metabolic consequences, namely the collapse of the mitochondrial transmembrane potential, uncoupling of the respiratory chain, hyperproduction of superoxide anions, disruption of mitochondrial biogenesis, outflow of matrix calcium and glutathione, and release of soluble intermembrane proteins. Recent evidence suggests that PT is a critical, rate limiting event of apoptosis (programmed cell death): (i) induction of PT suffices to cause apoptosis; (ii) one of the immediate consequences of PT, disruption of the mitochondrial transmembrane potential (ΔΨm), is a constant feature of early apoptosis; (iii) prevention of PT impedes the ΔΨm collapse as well as all other features of apoptosis at the levels of the cytoplasma, the nucleus, and the plasma membrane; (iv) PT is modulated by members of the apoptosis-regulatory bcl-2 gene family. Recent data suggest that the acquisition of the apoptotic phenotype, including characteristic changes in nuclear morphology and biochemistry (chromatin condensation and DNA fragmentation), depends on the action of apoptogenic proteins released from the mitochondrial intermembrane space.
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    The Non-Ohmic Proton Leak—25 Years On (1997)
    Springer
    Bioscience reports 17 (1997), S. 251-257 
    Details
    ISSN: 1573-4935
    Keywords: Leak ; mitochondria ; proton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The proton conductance of the mitochondrial inner membrane can be quantified by applying Ohm's law to the experimentally determined protonmotive force and the proton current flowing around the proton circuit in the absence of ATP synthesis or ion transport. This last parameter is derived from the rate of State 4 respiration multiplied by the H+/O stoichiometry for the substrate. When the activity of the dehydrogenase supplying electrons to the respiratory chain is progressively increased the proton conductance increases rapidly when the protonmotive force is greater than 220 mV. The consequences of this non-ohmic relationship are discussed.
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    Generating, Partitioning, Targeting and Functioning of Superoxide in Mitochondria (1997)
    Springer
    Bioscience reports 17 (1997), S. 259-272 
    Details
    ISSN: 1573-4935
    Keywords: Superoxide ; hydrogen peroxide ; electron leak ; proton leak ; H+/2e ; membrane potential ; reactive oxygen cycle ; heat production ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recently, we proposed a hypothetical model of coexistence of “Reactive oxygen cycle” with Q cycle and H+ cycle in mitochondrial respiratory chain to combine both processes of univalent electron leak for production of superoxide and of proton leak across inner mitochondrial membrane. This review presents a more detailed description of this model and summarizes the supporting experimental evidence obtained.
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    Membrane-Linked Systems Preventing Superoxide Formation (1997)
    Springer
    Bioscience reports 17 (1997), S. 347-366 
    Details
    ISSN: 1573-4935
    Keywords: Reactive oxygen species ; mitochondria ; pore ; apoptosis ; uncoupling ; non-coupled respiration ; aconitase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract New facts and ideas concerning the membrane-linked mechanisms preventing superoxide formation are summarised here. It is assumed that aerobic cells possess several lines of anti-ROS defence, including optimisation of the intracellular oxygen concentration, decrease in the concentration and life-time of one-electron O2 reductants such as CoQH; and mitochondrial and cell selections, i.e. elimination of mitochondria and cells producing ROS at high rate. It is postulated that ROS-dependent pore opening and ROS-dependent apoptosis are involved in mitochondrial and cell selections.
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    Characterization of the plant homologue of prohibitin, a gene associated with antiproliferative activity in mammalian cells (1997)
    Springer
    Plant molecular biology 33 (1997), S. 753-756 
    Details
    ISSN: 1573-5028
    Keywords: antiproliferation ; Arabidopsis ; mitochondria ; subcellular fractionation ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This report describes the cloning and characterization of a plant cDNA coding for a protein which shows high amino acid sequence similarity with prohibitin, whose gene is associated with antiproliferative activity in mammalian cells. Arabidopsis thaliana and Nicotiana tabacum prohibitin complete cDNAs were isolated, and the expression pattern of prohibitin was examined using polyclonal antibodies raised against the Arabidopsis recombinant prohibitin expressed in Escherichia coli. A single immunoreactive protein was detected in various plant species and in all Arabidopsis organs examined. Subcellular fractionation using tobacco leaves revealed prohibitin in a mitochondrial-enriched fraction. Phylogenetic conservation of prohibitin's amino acid sequence and subcellular localization suggests a similar function in plants, yeast and mammals.
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    URL: http://dx.doi.org/10.1023/A:1005737026289
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    Effects of light on the accumulation of abscisic acid and expression of an early cysteine-labeled metallothionein gene in microspores ofTriticum aestivum during induced embryogenic development (1997)
    Springer
    Plant cell reports 16 (1997), S. 458-463 
    Details
    ISSN: 1432-203X
    Keywords: Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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    URL: http://dx.doi.org/10.1007/BF01092766
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    Protein evolution in dynamically managed populations of wheat: adaptive responses to macro-environmental conditions (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 932-941 
    Details
    ISSN: 1432-2242
    Keywords: Key words Genetic resources ; Dynamic conservation ; Two-dimensional electrophoresis ; Artificial population ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Dynamic management of genetic resources aims to conserve genetic variability between different populations evolving in contrasting environments. It is thus of importance to determine whether differences appearing between populations are stochastic or if they come about from adaptation. Two-dimensional electrophoresis (2DE) was used to study genetic differentiation of 11 wheat populations evolving since 1984 in a multi-site network covering the major cultivation area of wheat in France. Gels were scanned and protein-spot intensities were measured through image analysis. As it was not possible to assay each individual, populations were characterized using pooled extracts from several plants. In the first step, two parents among the 16 parental lines involved in the initial wheat composite-cross population were exhaustively studied to identify a set of polymorphic spots against which the entire set of evolved populations could be compared. This analysis confirmed the efficiency of gel image-processing to determine the composition of pooled extracts. Of the 48 spots used to investigate population differentiation, 15 showed significant differences at the P〈0.05 level. Populations that evolved independently at the same location showed similar differentiation, even when their cultivation methods were different. These results suggest that natural selection acted strongly on the evolution of the populations, and that responses to selection were determined primarily by macro-environmental conditions.
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    Chromosomal location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L. em. Thell.) 4. Gene Pm 24 in Chinese landrace Chiyacao (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 950-953 
    Details
    ISSN: 1432-2242
    Keywords: Key words Wheat landrace ; Triticum aestivum ; Powdery mildew resistance ; Monosomic analysis ; Gene location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Chinese wheat landrace Chiyacao exhibited a response pattern different from that of the cultivars/lines possessing documented Pm genes after inoculation with 106 isolates of Erysiphe graminis f. sp. tritici. To characterize this resistance and to determine the chromosomal location of the gene or genes present, we crossed the landrace to susceptible cultivar ‘Chinese Spring’ and also to a set of 21 ‘Chinese Spring’ monosomic lines. Monosomic F1 plants were allowed to self-pollinate and to produce F2 seeds. Seedlings of F2 plants and their parents were inoculated with isolates nos. 5 and 12 of Erysiphe graminis f. sp. tritici. The results revealed that one major dominant gene is located on chromosome 6D of Chinese common wheat landrace Chiyacao. The new gene is designated Pm 24.
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    DNA content of wheat monosomics at interphase estimated by flow cytometry (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 1300-1304 
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    ISSN: 1432-2242
    Keywords: Key words Flow cytometry ; Triticum aestivum ; DNA analysis ; Monosomics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Two complete, independently maintained sets of 21 monosomic wheat lines derived from cv. ‘Chinese Spring’ were analyzed for their DNA content at the G1 stage with flow cytometry. The DNA content of individual chromosomes was estimated by subtracting the value of a monosomic line from that of euploid wheat. Our data show that the estimated 2C DNA of individual wheat chromosomes in 21 monosomics at the G1 stage ranges from about 0.58 pg in chromosome 1D to approximately 1.12 pg in chromosome 3A. The A genome (2C=6.15 pg) seems to contain more DNA than the B (2C=6.09 pg) and D (2C=5.05 pg) genomes. Analysis of variance showed significant differences (α=0.01) in DNA content both among homoeologous groups and among genomes. Our estimates of interphase DNA content of wheat chromosomes from monosomic lines were poorly correlated to the chromosome sizes at metaphase (r=0.622, P≤0.01). This poor correlation might be due to differential coiling among chromosomes during cell division, possible bias of fluorochrome binding to heterochromatin, or heterogeneity among monosomic lines. Finally, flow cytometry may aid but cannot replace cytological checks in aneuploid maintenance.
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    Genetic diversity in Eastern U.S. soft winter wheat (Triticum aestivum L. em. Thell.) based on RFLPs and coefficients of parentage (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 472-479 
    Details
    ISSN: 1432-2242
    Keywords: Key words Genetic diversity ; RFLP ; Coefficient of parentage ; Triticum aestivum ; Gene pool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic diversity in a set of 11 red and 11 white wheat lines from the Eastern U.S. soft wheat germplasm pool was measured using restriction fragment length polymorphism (RFLP) assay and coefficients of parentage (COP) analysis. On average, 78% of all bands revealed by three enzymes with 48 RFLP clones were monomorphic. Average pairwise genetic similarity (GS) was 0.97 when data from all enzymes were pooled. Probe Polymorphic Information Content (PIC) indexes ranged from 0 to 0.73 with a mean of 0.2. Fewer than 55% of the probes revealed any polymorphism. The frequency of polymorphism in the Eastern U.S. soft white winter (SWW) wheat gene pool was much lower than that observed in the Eastern U.S. soft red winter (SRW) wheat gene pool. SWW lines formed a single group on a dendrogram based on cluster analysis of RFLP-derived GS estimates, while SRW lines did not form a single group. COP values for all pairs of the Eastern U.S. soft wheat lines ranged from 0.02 to 0.9 with a mean of 0.21. SWW wheat lines traced to 53 ancestral lines and had an average COP of 0.51. The SRW wheat gene pool had more complex parentages (mean COP=0.15 and a total of 65 ancestral lines). COPs were correlated with RFLP-based GS for all line pairs (r=0.73, P〈0.01). However, correlations between the two similarity measures were substantially lower when the SRW and SWW wheat gene pools were considered individually (r values of 0.23 and 0.28, respectively). The actual GS among unrelated lines in the U.S. Eastern soft wheat gene pool appears to be higher than that observed for unrelated landraces from Southwest Asia (0.96 vs. 0.905), suggesting that the ancestral landrace parents of this gene pool were themselves drawn from a base population where inbreeding, i.e., F, was greater than zero.
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    URL: http://dx.doi.org/10.1007/s001220050439
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    RAPDs as molecular markers for the detection of Aegilops markgrafii chromatin in addition and euploid introgression lines of hexaploid wheat (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 934-940 
    Details
    ISSN: 1432-2242
    Keywords: Key words Aegilops markgrafii ; Triticum aestivum ; RAPD ; Addition lines ; Leaf rust ; Powdery mildew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops markgrafii contains resistance genes to powdery mildew, leaf rust and stripe rust, and also has high crude protein and lysine contents, which can be useful for wheat improvement. These important traits are localized on different chromosomes. Disomic Triticum aestivum-Ae. markgrafii addition lines and euploid introgression lines showing leaf-rust and powdery mildew resistance were screened with RAPDs to detect chromosome-specific markers which can accelerate the breeding process. RAPD markers for all six available disomic addition lines were obtained. The additional chromosomes B, C, D, E, F and G were identified by three, three, three, two, one and seven primers, respectively. All three chromosome-B-specific RAPD markers demonstrated the presence of alien chromatin in the leaf-rust-resistant 42-chromosome introgression lines as well as in the segregating progeny. The three chromosome-C-identifying primers also demonstrated the presence of that chromosome in powdery mildew-resistant euploid introgression lines. The substitution lines (5A)5C and (5D)5C with different genetic backgrounds for both parents, in comparison to the lines mentioned above, showed the chromosome C-specific band with only two of the three primers. The chromosome F-specific primer and a primer evident on all the Ae. markgrafii chromosomes analysed did not generate the expected fragments on the chromosome Fdel addition line, indicating that the markers are located on the deleted part of chromosome F.
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    URL: http://dx.doi.org/10.1007/s001220050498
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    Hessian fly-resistance gene transferred from chromosome 4Mv of Aegilops ventricosa to Triticum aestivum (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 858-864 
    Details
    ISSN: 1432-2242
    Keywords: Key words Aegilops ventricosa ; Triticum aestivum ; Mayetiola destructor ; Hessian fly ; Resistance gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A new Hessian fly (Mayetiola destructor) resistance gene from Aegilops ventricosa and its transfer to hexaploid wheat is described. The 4D(4Mv) substitution line H-93-33 derived from the cross [(Triticum turgidum H-1-1×Aegilops ventricosa no. 11)×Triticum aestivum H-10-15] was highly resistant to the Spanish population tested. Resistance seemed to be inherited as a single dominant factor in the F2 generation resulting from a cross of H-93-33 with its susceptible parent (H-10-15). Resistance in Ae. venticosa no. 10 was located on chromosome 4Mv using Mv wheat/Ae. ventricosa addition lines. The resistance gene transferred from Ae. ventricosa no. 11 to H-93-33 (H27) is allelic with respect to that of Ae. ventricosa no. 10 and is non-allelic with respect to the genes H3 and H6 from Monon and Caldwell respectively. The assignment of H27 gene to chromosome 4Mv is further supported by its linkage to a gene encoding isozyme Acph-Mv1, previously located on chromosome 4Mv in the line H-93-33. A new marker from homoeologous chromosome group 4 (Amp-Mv2) present in H-93-33 and the 4Mv addition line is described.
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    The development of a nuclear male sterility system in wheat. Expression of the barnase gene under the control of tapetum specific promoters (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 125-131 
    Details
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Triticum aestivum ; Transformation ; Nuclear male sterility ; DNA-integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Nuclear male sterility within Triticum aestivum is considered as the ideal basis for the development of a hybridization system for wheat. We engineered nuclear male sterility in wheat by introducing the barnase gene under the control of tapetum-specific promoters derived from corn and rice. A biolistic-mediated transformation method, based on the use of the poly(ADP-ribose)polymerase inhibitor niacinamide, was set up which enriched for low-copy integrations (1–3 copies). Most of these copies were not linked and segregated in the next generation.
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    URL: http://dx.doi.org/10.1007/s001220050540
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    Risk from genetically engineered and modified marine fish (1997)
    Springer
    Transgenic research 6 (1997), S. 59-67 
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    ISSN: 1573-9368
    Keywords: Sparus aurata ; transgenic ; ecologicalrisk ; release ; genetic modification ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In support of the emerging industries of warmwater marine fish mariculture, genetic engineering and classical genetic improvement programmes have been initiated for a variety of exclusively marine fish. These programmes have the potential to perturb allele and genotype frequencies, or introduce novel alleles and genes into conspecific wild populations. Despite concerns to the contrary, the following hypothesis remains to be falsified: ‘laboratory induced allele frequency/genotype changes and novel alleles or genes have a negligible probability of being selectively favoured in wild populations under natural selection, and accordingly, without sustained large scale releases, have little potential for ecological impact’
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    URL: http://dx.doi.org/10.1023/A:1018457100476
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    Fusarium nisikadoi, a new species from Japan (1997)
    Springer
    Mycoscience 38 (1997), S. 329-333 
    Details
    ISSN: 1618-2545
    Keywords: conidial morphology ; form-sectionLiseola ; Fusarium nisikadoi ; Phyllostachys nigra var.henonis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species ofFusarium, F. nisikadoi, isolated fromPhyllostachys nigra var.henonis (bamboo) andTriticum aestivum (wheat) in Japan, is described, illustrated and discussed. This species is differentiated from other known species of the genus by the following characteristics: whitish colony color, long zigzag-like chains of 0–3(-5)-septate clavate conidia, intermixed with pyriform conidia, produced mostly from monophialides and rarely from polyphialides in the aerial mycelium, very long and slender sporodochial conidia, and no chlamydospores. The long chains of septate conidia are known only in this species of the genusFusarium. The conidiophores on the aerial mycelium sometimes proliferate sympodially. The species is tentatively placed in the form-sectionLiseola.
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    Food-web manipulation in a small, eutrophic Lake Wirbel, Poland: the effect of replacement of key predators on epiphytic fauna (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 377-381 
    Details
    ISSN: 1573-5117
    Keywords: key-predator replacement ; fish ; invertebrate carnivores ; epiphytic fauna ; Chironomidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of fish removal on the invertebrate fauna associatedwith Stratiotes aloides was studied in a shallow, eutrophiclake. The biomass of invertebrate predators was approximately 2.5times higher in the invertebrate-dominated year (1992) than in thefish-dominated year (1991), while the density of non-predatoryinvertebrates in 1991 was ca half that in theinvertebrate-dominated year. The decrease was due to a sharp fallin the density of epiphytic chironomids, with the density ofplant-mining chironomids being far less affected. Marked declinesin the density of non-predatory invertebrates in theinvertebrate-dominated year were most probably caused byinvertebrate predators. Once freed from suppression induced byfish, invertebrate predators were able to control the density ofepiphytic prey more effectively than fish.
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    Ecomorphological diet predictions: an assessment using inland silverside (Menidia beryllina) and longear sunfish (Lepomis megalotis) from Lake Texoma (1997)
    Springer
    Hydrobiologia 350 (1997), S. 87-98 
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    ISSN: 1573-5117
    Keywords: ecomorphology ; trophic ecology ; physiology ; diet ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The functions of an organism‘s morphological structures indicatethe organism‘s potential resource use (fundamental niche). Whilethis information often is also used to predict differences inactual resource use (realized niche) among individuals or species,such predictions may not be accurate because the maximum abilitiesmay not be useful to the organism under specific conditions or inspecific environments. We investigated the importance of sixpreviously studied morphologically based performanceabilities/constraints in structuring the diet of Menidiaberyllina (inland silverside) and Lepomis megalotis (longearsunfish) in Lake Texoma, a reservoir in the Red River basin(Oklahoma-Texas, USA). Of the six morphological characteristicsmeasured (number of gill rakers, length of gill rakers, spacebetween gill rakers, eye lens diameter, mouth size, mouthprotrusibility), only one characteristic for M. beryllina(mouth size) and three for L. megalotis (space betweenrakers, mouth size, and raker length) correlated with the gutcontents as predicted by previous functional morphology studies.This indicates that caution should be exercised when makinguntested predictions about the ecology of an organism based on itsfunctional morphology.
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    Effects of zebra mussels on food webs: interactions with juvenile bluegill and water residence time (1997)
    Springer
    Hydrobiologia 354 (1997), S. 141-150 
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    ISSN: 1573-5117
    Keywords: Dreissena ; mesocosm ; seston ; fish ; food web ; manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We evaluated how water residence time mediated the impact of zebramussels Dreissena polymorpha and bluegill sunfish Lepomis macrochirus on experimental food webs established in1100-l outdoor mesocosms. Water residence time was manipulated asa surrogate for seston resupply – a critical variable affectinggrowth and survival of suspension-feeding invertebrates. We used a2×2×2 factorial experimental design witheight treatment combinations (3 replicates/treatment) including thepresence or absence of Dreissena (2000 per m2), juvenilebluegill (40 per mesocosm), and short (1100 l per d) or long (220 lper d) water residence time. Measures of seston concentration(chlorophyll a, turbidity and suspended solids) were greaterin the short- compared to long water-residence mesocosms, butintermediate in short water-residence mesocosms containing Dreissena. Abundance of rotifers (Keratella and Polyarthra) was reduced in Dreissena mesocosms and elevatedin short residence time mesocosms. Cladocera abundance, in general,was unaffected by the presence of Dreissena; densities werehigher in short-residence time mesocosms, and reduced in thepresence of Lepomis. The growth of juvenile Lepomiswere unaffected by Dreissena because of abundant benthicfood. The final total mass of Dreissena was significantlygreater in short- than long-residence mesocosms. Impacts of Dreissena on planktonic food webs may not only depend on thedensity of zebra mussels but also on the residence time of thesurrounding water and the resupply of seston.
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    Genetic variability in the European minnow, Phoxinus phoxinus (L.) (1997)
    Springer
    Hydrobiologia 364 (1997), S. 183-188 
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    ISSN: 1573-5117
    Keywords: fish ; genetic variability ; protein polymorphism ; heterosis ; heterozygosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An electrophoretic study of genetic variation at 11 loci was performedfor a population of European minnows, Phoxinus phoxinus (L.). Ten loci, EST-1 *, EST-2 * EST-3 *,GPD-1 *,GPD-2 *,GPI-1 *,GPI-2 *,MPI *,6PGD * and PGM * were polymorphic. IDH *wasmonomorphic. The mean number of heterozygotic loci over all 176 fish was 3.05 ± 0.104(SE). Observed mean heterozygosity was 0.28±0.058(SE) and expected mean heterozygosity was 0.27±0.054(SE). EST-2 *, EST-3 * andPGM * were not in Hardy-Weinberg equilibrium. Length,condition, parasite numbers or male breeding characters, i.e. red colorationand tubercles, were not influenced by single enzyme loci.
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    Influence of fish on the breeding of the red-necked grebe Podiceps grisegena (Boddaert, 1783) (1997)
    Springer
    Hydrobiologia 344 (1997), S. 57-63 
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    ISSN: 1573-5117
    Keywords: red-necked grebe ; breeding sites ; fish ; macroinvertebrates ; food competition ; physical and chemicalconditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I determined whether selection of breeding sites by thered-neckedgrebe Podiceps grisegena (Boddaert, 1783) was affectedbycompetition for food with fish. During 1987–89, ten ponds inScania, southern Sweden were investigated, five with(‘breedingsites’) and five without breeding red-necked grebe(‘non-breedingsites’). I quantified the biomass of fish and macrozoans(here:larger invertebrates and small vertebrates) and measured thephysical and chemical conditions of the ponds.Breeding sites had significantly lower relative fish abundancethannon-breeding sites. They were either devoid of fish or hadonly nine-spined sticklebackPungitius pungitius. The biomass (dry weight) ofmacrozoans,many of which represent a food resource for grebes, was 16timesgreater at breeding than at non-breeding sites. The physicalandchemical conditions of the ponds did not differsignificantly.These results are consistent with the hypothesis thatcompetitionfor macrozoans occurs between red-necked grebe and fish andthat adense population of many fish species caused red-necked grebestoavoid otherwise acceptable breeding sites.
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    Tolerance levels of redbreast tilapia, Tilapia rendalli (Boulenger, 1896) to natural suspended silt (1997)
    Springer
    Hydrobiologia 344 (1997), S. 11-18 
    Details
    ISSN: 1573-5117
    Keywords: fish ; silt ; exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tilapia rendalli was exposed to various siltconcentrationsfor different exposure periods to determine LC50 andsublethalconcentration ranges. The extent of damaging effects, if any,ofsuspended silt on the exposed fish, were investigated by meansofscanning electron microscopy. The LC50 values rangedbetween21 to 24 g l™1 and 42–48 g l™1 for juveniles andadultsrespectively. The silt concentrations tolerated by the testfisheswere above those found in most natural waters. The resultstherefore support the hypothesis that suspended silt is lethaltofish at concentrations higher than those naturally observed insurface water. The observed mortalities can be attributed tothecombined physical effects of high silt concentrations andassociated reduction in dissolved oxygen levels. To preventfishmortalities and other impacts on biota, anthropogenicactivitiesthat affect the natural variation in suspended siltconcentrationsin surface water should be carefully monitored and, wherepossible,be restricted.
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    Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea Coast of Yemen (1997)
    Springer
    Hydrobiologia 352 (1997), S. 251-262 
    Details
    ISSN: 1573-5117
    Keywords: Red Sea ; PAHs ; oil pollution ; HPLC ; GC/MS ; fish ; origin ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed analytical study using combined normal phase high pressure liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) of Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea was undertaken. This investigation involves a preliminary assessment of the sixteen parent compounds issued by the U.S. Environmental Protection Agency(EPA). The study revealed measurable levels of Σ PAHs (the sum of three to five or six ring parent compounds) (49.2 ng g−1 dry weight) and total PAHs (all PAH detected) (422.1 ng g−1 dry weight) in edible muscle of fishes collected from the Red Sea. These concentrations are within the range of values reported for other comparable regions of the world. Mean concentrations for individual parent PAH in fish muscles were; naphthalene 19.5, biphenyl 4.6, acenaphthylene 1.0, acenaphthene 1.2, fluorene 5.5, phenanthrene 14.0, anthracene 0.8, fluoranthene 1.5, pyrene 1.8, benz(a)anthracene 0.4, chrysene 1.9, benzo(b)fluoranthene 0.5, benzo(k)fluoranthene 0.5, benzo(e)pyrene 0.9, benzo(a)pyrene 0.5, perylene 0.2, and indeno(1,2,3-cd)pyrene 0.1 ng g−1 dry weight respectively. The Red Sea fish extracts exhibit the low molecular weight aromatics as well as the discernible alkyl-substituted species of naphthalene, fluorene, phenanthrene and dibenzothiophene. Thus, it was suggested that the most probable source of PAHs is oil contamination originating from spillages and/or heavy ship traffic. It was concluded that the presence of PAHs in the fish muscles is not responsible for the reported fish kill phenomenon. However, the high concentrations of carcinogenic chrysene encountered in these fishes should be considered seriously as it is hazardous to human health. Based on fish consumption by Yemeni‘s population it was calculated that the daily intake of total carcinogens were 0.15 µg/person/day.
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    Top-down control in freshwater lakes: the role of nutrient state, submerged macrophytes and water depth (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 151-164 
    Details
    ISSN: 1573-5117
    Keywords: top-down control ; shallow lakes ; trophic structure ; trophic cascade ; macrophytes ; zooplankton ; fish ; biomanipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on data from 233 Danish lakes, enclosure experiments, full-scaleexperiments and published empirical models we present evidence that top-downcontrol is more important in shallow lakes than in deep lakes, excepting lakeswith a high abundance of submerged macrophytes. The evidence in support is: (1)That at a given epilimnion total phosphorus concentration (TP) the biomass offish per m2 is independent of depth, which means that biomassper m3is markedly higher in shallow lakes. (2) That the biomass of benthic invertebratesis higher in shallow lakes, which means that the benthi-planktivorous fish areless dependent on zooplankton prey than in deep lakes. By their ability to shiftto zooplankton predation their density can remain high even in periods whenzooplankton is scarce and they can thereby maintain a potentially high predationpressure on zooplankton. (3) That the possibilities of cladocerans to escapepredation by vertical migration are less. (4) That the zooplankton:phytoplanktonmass ratio per m2 is lower and presumably then also thegrazing pressure onphytoplankton. (5) That nutrient constraints appear to be weaker, as evidenced bythe fact that at a given annual mean TP, summer TP is considerably higher inshallow lakes, especially in eutrophic lakes lacking submerged macrophytes. (6)That negative feedback on cladocerans by cyanobacteria is lower as cyanobacterialdominance is less frequent in shallow lakes and more easily broken (at least inNorthern temperate lakes), and (7) That top-down control by benthi-planktivorousfish is markedly reduced in lakes rich in submerged macrophytes because theplants serve as a refuge for pelagic cladocerans and encouragepredatory fish at the expense of prey fish. We conclude that manipulation of fishand submerged macrophytes may have substantial impact on lake ecosystems, inparticular in shallow eutrophic lakes. On the contrary, if the conditions formore permanent changes in plant abundance or fish community structure are lackingthe feed-back mechanisms that endeavour a return to the original turbid state willbe particularly strong in shallow lakes.
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    Lake Volkerak-Zoom: a lake shifting from the clear to the turbid state (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 367-376 
    Details
    ISSN: 1573-5117
    Keywords: phytoplankton ; zooplankton ; eutrophication ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lake Volkerak-Zoom (area 6000 ha, mean depth 5 m) was createdin1987 by isolating a part of the Eastern Scheldt estuary. A fewyears after enclosure the new freshwater lake was cleardespite ahigh phosphorus loading. However from 1990 on the transparencydropped.This paper describes the transition from the clear to theturbidstate of lake Volkerak-Zoom. The processes responsible for theultimate lowering of the transparency in the period 1988–1994willbe discussed and also the measures necessary to meet thetargetsituation: clear water with a transparency of 2 m. From 1990ontransparency is decreasing due to an increasing algal biomass,probably caused by a reduced grazing of the zooplankton. It ispossible that deterioration of the food quality (by increasedcyanobacterial blooms) reduced the zooplankton grazing.However,there are indications that increased mortality, caused by fishpredation, played the most important role in the reduction ofthezooplankton grazing. In 1992 the recruitment of fish,especially ofroach (Rutilus rutilus), was high (c. 40 kg ha−1).Thiscaused a high predation pressure on the zooplankton and isshown bya decrease of the mean length and vertical migration of Daphnia in 1992. In the same year the largest zooplanktonspecies,Daphnia pulex, disappeared from the lake. Smallerzooplanktonspecies with a lower grazing capacity remained. Because of thedecreased grazing, the algal biomass increased and thetransparencydropped. We expect that inthe future the lake will become more turbid. As an additionalmeasure to P-reduction, removing of fish is suggested to meetthetarget situation: a lasting clear water state.
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    Isolation and characterization of cDNA for a plant mitochondrial phosphate translocator (Mpt1): ozone stress induces Mpt1 mRNA accumulation in birch (Betula pendula Roth) (1997)
    Springer
    Plant molecular biology 35 (1997), S. 271-279 
    Details
    ISSN: 1573-5028
    Keywords: Betula pendula Roth ; differential display ; gene expression ; mitochondria ; oxidative stress ; ozone ; phosphate translocator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated by DDRT-PCR (differential-display reverse-transcription polymerase chain reaction) and cDNA library screening a 1.3 kb cDNA corresponding to a strongly ozone-inducible transcript from birch (Betula pendula Roth). Nucleotide sequence analysis suggests that it encodes a mitochondrial phosphate translocator protein (Pi c), the first one isolated from plants. The isolated birch mitochondrial phosphate translocator cDNA (designated Mpt1) contains an open reading frame of 1092 bases encoding a 364 amino acid polypeptide. The deduced protein is 66% similar to bovine Pic isoform B. Comparison of the N-terminal amino acid sequence to known mammalian Pic proteins and the existence of an in-frame stop codon upstream of the initiation codon suggest that the isolated cDNA is full-length. Southern hybridization analysis of birch genomic DNA shows that Mpt1 is a single-copy gene. Accumulation of Mpt1 mRNA during oxidative stress imposed by ozone is detectable already at 2 h and it is at maximum ca. 12 h after the beginning of an 8 h ozone exposure (150 ppb). A second O3 peak at 48–56 h did not increase transcript levels further. O3 exposure for 2 h was sufficient for Mpt1 induction. Birch Mpt1 transcript levels remain at moderately low level during leaf development and is lower in roots and leaves when compared to young shoots undergoing wood formation and lignification.
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    Geranylgeranyl pyrophosphate synthase encoded by the newly isolated gene GGPS6 from Arabidopsis thaliana is localized in mitochondria (1997)
    Springer
    Plant molecular biology 35 (1997), S. 331-341 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana/ ; carotenoid ; crtE/ ; gene cloning ; GGPP synthase ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have cloned a new geranylgeranyl pyrophosphate (GGPP) synthase gene, designated GGPS6/, from Arabidopsis thaliana genomic DNA. Nucleotide sequence analysis revealed that the GGPS6 gene contains an open reading frame coding for a protein of 343 amino acid residues with a calculated molecular mass of 37 507 Da. Also, the gene is not interrupted by an intron. The predicted amino acid sequence of the GGPS6 gene shows significant homology (34.0–57.7%) with other GGPP synthases from Arabidopsis. The GGPS6 protein contains a N-terminal signal peptide which is thought to function as an organelle targeting sequence. In fact, the GGPS6-GFP fusion protein was found to be localized exclusively in mitochondria when expressed in tobacco BY-2 cells. In vitro analysis of the enzyme activity as well as genetic complementation analysis with Erwinia uredovora crt gene cluster expressed in Escherichia coli showed that the GGPS6 gene most certainly encodes a GGPP synthase catalyzing the conversion of farnesyl pyrophosphate to GGPP.
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    “Mild” Uncoupling of Mitochondria (1997)
    Springer
    Bioscience reports 17 (1997), S. 273-279 
    Details
    ISSN: 1573-4935
    Keywords: Uncoupling ; mitochondria ; free radicals ; thyroid hormones ; steroid hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Recently, it was proposed that the thyroid hormone-mediated uncoupling in mitochondria is involved in the cellular defence system against free radicals (Skulachev V.P. (1996) Quart. Rev. Biophys. 29:169–202). This phenomenon was named “mild” uncoupling. It was postulated to be a protein-mediated process controlled by several factors. The data reported during the past 40 years, pointing to the protein-mediated uncoupling mechanism in mitochondria, are reviewed in a context of hypothetical properties of “mild” uncoupling. The mechanism of “mild” uncoupling is suggested to be the following: (a) mitochondria possess protein(s) that regulate the proton permeability of inner mitochondrial membrane; (b) these proteins are regulated by binding of an unidentified low-molecular-weight endogenous compound with properties resembling those of the most active artificial uncouplers like FCCP and SF6847; (c) the interaction of this compound with its target protein(s) is modulated by a thyroid hormone in a positive (i.e. enhancing the proton permeability) way and by sex steroid hormones in a negative way; (e) endogenous fatty acids can attenuate the influence of both thyroid and steroid hormones.
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    Structure and Function of the Plant Alternative Oxidase: Its Putative Role in the Oxygen Defence Mechanism (1997)
    Springer
    Bioscience reports 17 (1997), S. 319-333 
    Details
    ISSN: 1573-4935
    Keywords: Plant alternative oxidase ; mitochondria ; oxidative stress ; active oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Current understanding of the structure and function of the plant alternative oxidase is reviewed. In particular, the role of the oxidase in the protection of tissues against oxidative stress is developed.
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    URL: http://dx.doi.org/10.1023/A:1027388729586
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    An Uncoupling of the Processes of Oxidation and Phosphorylation in Glycolysis (1997)
    Springer
    Bioscience reports 17 (1997), S. 521-527 
    Details
    ISSN: 1573-4935
    Keywords: Glyceraldehyde-3-phosphate dehydrogenase ; glycolysis ; oxidation ; uncoupling ; thiols ; hydrogen peroxide ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Data on alterations of the properties of glyceraldehyde-3-phosphate dehydrogenase upon oxidation of its functional groups are reviewed; a mechanism of uncoupling of oxidation and phosphorylation in glycolysis is considered. Possible ways of regulating uncoupling, and the physiological importance of this process, are discussed.
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    Sensitivity of Ca2+ Transport of Mitochondria to Reactive Oxygen Species (1997)
    Springer
    Bioscience reports 17 (1997), S. 557-567 
    Details
    ISSN: 1573-4935
    Keywords: Reactive oxygen species (ROS) ; mitochondria ; Ca2+ transport ; energy transduction ; electron paramagnetic resonance (EPR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between Ca2+ transport and energy transduction of myocardial mitochondria in the presence of reactive oxygen species was investigated. Following treatment with oxygen free radicals [superoxide(O 2 • ) or hydroxyl radical (•)OH], lipid free radicals in myocardial mitochondrial membrane could be detected by using the method of EPR spin trap. Simultaneously there were obvious alterations in the free Ca2+ ([Ca2+]m) in the mitochondrial matrix; the physical state of membrane lipid; the efficiency of oxidative phosphorylation (ADP/O); the value of the respiratory control ratio (RCR); and the membrane potential of the inner membrane of myocardial mitochondria. If the concentrations of reactive oxygen species were reduced by about 30%, the alterations in the physical state of the membrane lipid and energy transduction of myocardial mitochondria were not observed, but the changes in Ca2+ homeostasis remained. We conclude that Ca2+ transport by myocardial mitochondria is more sensitive to agents such as (O 2 • ) or •OH, etc. than are oxidation phosphorylation and the respiratory chain.
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    Heterosis and combining ability for plant height and its components in hybrid wheat with Triticum timopheevi cytoplasm (1997)
    Springer
    Euphytica 95 (1997), S. 337-345 
    Details
    ISSN: 1573-5060
    Keywords: hybrid wheat ; Triticum aestivum ; plant height ; internode length ; heterosis ; combining ability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The heterosis and combining ability for plant height and its components of hybrid wheat were investigated in an incomplete diallel experiment including 5 CMS lines and 4 restorer lines. The results showed that heterosis (HS) and heterobeltiosis (HBS) occurred in plant height (PH) and length of the first internode (LFI), second internode (LSI), third internode (LTI), basal internode (LBI) and the spike (LS) of hybrids, but their values varied among crosses and characters; the HS and HBS of LBI were larger than those of other characters, the HS and HBS of LSI and LTI contributed a lot to those of PH. There were significant relationships between internode lengths and PH for specific combining ability (SCA) and general combining ability (GCA), and among lengths of the adjacent internodes for SCA and/or GCA effects. However, the relationships of LS with the lengths of internodes and PH were insignificant for GCA, SCA, HS and HBS. The SCA effects were more important than GCA effects for LFI, the reverse was true for LSI, LTI, LS and PH, and the SCA effects was nearly equal to the GCA effects for LBI. So, LFI was mainly influenced by non-additive effect of genes, while LSI, LTI, LS and PH were mainly controlled by additive gene effects, LBI was controlled equally by additive and non-additive effects of genes. The genes that control the length of specific internode not only affect PH, but also the length of the adjacent internode. The genetic system in charge of lengths of internodes and plant height is independent of that for length of spike. Thus, it is possible to develop new wheat cultivars or hybrid combinations having long spike but dwarf plant height.
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    URL: http://dx.doi.org/10.1023/A:1003092432309
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    Components of quantitative resistance to yellow rust in ten spring bread wheat cultivars and their relations with field assessments (1997)
    Springer
    Euphytica 96 (1997), S. 215-223 
    Details
    ISSN: 1573-5060
    Keywords: Puccinia striiformis ; Triticum aestivum ; association of components ; stripe rust ; durable resistance ; infection frequency ; latency period ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Latency period, infection frequency, lesion length, lesion growth, disease severity and percentage of infected leaf parts were assessed on 10-day-old seedling leaves and flag leaves of ten bread wheat (Triticum aestivum L.) cultivars after inoculation with urediospores of Puccinia striiformis Westend. f. sp. tritici. For all components significant genotypic differences were detected. Components of resistance tended to be associated. A long latency period was associated with a low infection frequency, small lesions, a low disease severity and a low percentage of infected leaf parts. The latency period, measured as time period until first pustule appearance (LP1), was highly correlated with the latency period measured as time period until 50% of the pustules appeared (LP50). Assessment of latency period of large numbers of cultivars could therefore be reliably done by measuring LP1 which is less time consuming than measuring LP50. Latency period, infection frequency and disease severity were highly correlated with disease development data from field experiments. These results suggest that selection in the greenhouse for one of these components should result in cultivars with high levels of quantitative resistance. Disease severity after uniform inoculation in the greenhouse can be used for monocyclic evaluations because it is the easiest to assess.
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    URL: http://dx.doi.org/10.1023/A:1002916110347
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    Effects of barley chromosome on heading characters in wheat-barley chromosome addition lines (1997)
    Springer
    Euphytica 96 (1997), S. 281-287 
    Details
    ISSN: 1573-5060
    Keywords: heading character ; Hordeum vulgare ; Triticum aestivum ; wheat-barley chromosome addition line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Heading time in cereals is a composite character determined by vernalization requirement, photoperiodic sensitivity and narrow-sense earliness. To study the effects of added barley chromosomes on the heading characters in wheat, two sets of wheat-barley chromosome addition lines, i.e., ‘Betzes’ barley chromosomes 2H to 7H added to ’Chinese Spring‘ wheat (CS-Be2H to CS-Be7H) and ‘New Golden’ barley chromosomes 5H and 6H added to ‘Shinchunaga’ wheat (Shi-NG5H, Shi-NG6H), were examined for their heading characters. All barley chromosomes except Be6H affected vernalization requirement and/or narrow-sense earliness in CS or Shi. Be5H chromosome also slightly increased the photoperiodic sensitivity of CS. Shi-NG5H addition line showed significantly decreased vernalization requirement in comparison with Shi, whereas CS-Be5H did not show any difference from CS. The F1 hybrid of the cross, Shi-NG5H × CS-Be5H, exhibited the same level of vernalization insensitivity as the Shi-NG5H addition line, and plants with and without a vernalization requirement segregated in a 1 : 3 ratio in the F2 generation. These observations, together with previous reports, suggest that the decreased vernalization requirement in the Shi-NG5H addition line was caused by the presence of a major dominant gene for spring habit, Sh2, located on the NG5H barley chromosome. Furthermore, this study revealed that the Sh2 gene in barley has a similar but weaker effect than the wheat vernalization insensitive gene, Vrn1, on the vernalization response in wheat.
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    URL: http://dx.doi.org/10.1023/A:1003025501591
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    Response of wheat genotypes to sowing date and boron fertilization aimed at controlling sterility in a rice-wheat rotation in Nepal (1997)
    Springer
    Plant and soil 188 (1997), S. 249-256 
    Details
    ISSN: 1573-5036
    Keywords: boron ; rice-wheat rotation ; sterility ; time of sowing ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Spikelet sterility in wheat (Triticum aestivum L.) is emerging as a production threat in different parts of Nepal. This study was aimed at determining the effects of sowing date and boron application in controlling spikelet sterility in four different genotypes of spring wheat in a rice-wheat system in the western hills of Nepal. Four genotypes of known different responses to boron were planted on 21 November, 6 December and 21 December, 1994 with or without boron application at 1 kg B ha-1 (i.e. 9 kg borax ha-1) on a soil that was known to be deficient in boron. The effect of sowing date was significant for the phenology, yield components, percentage sterility and grain yield. Sterility was significantly increased in the crop planted on 21 December, which had also the lowest 1000 seed weight and grain yield; there was an almost 50% grain yield reduction compared to the crop planted on 21 November. Terminal moisture stress (i.e. lack of moisture during the later part of the development) was observed in the late sown crop which also amplified the extent of sterility associated with boron deficiency. Genotypes differed in response to sowing dates and boron treatment for all of the phenological events measured, yield components, grain yield and percentage sterility. SW-41 and BL-1022 had significantly higher sterility at all sowing dates. BL-1249 showed a consistently lower% sterility over all sowing dates and boron treatments. The addition of boron significantly increased the number of grains set per spike thereby decreasing the total sterility in boron responsive genotypes SW-41 and BL-1022 while those not susceptible did not respond. The boron concentration in the flag leaf at anthesis was increased in treatments with added B in the soil but genotypes did not differ in boron concentration for any soil treatment.
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    URL: http://dx.doi.org/10.1023/A:1004202725382
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    Regulation of nitrogen fixation in infected cells of leguminous root nodules in relation to O2 supply (1997)
    Springer
    Plant and soil 191 (1997), S. 189-203 
    Details
    ISSN: 1573-5036
    Keywords: bacteroids ; leghaemoglobin ; mitochondria ; nitrogenase ; oxygen ; pro-plastids ; regulation ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Respiration and nitrogen fixation in legume root nodules is considered to be limited by the rate at which O2 from the atmosphere can enter nodules. A thin diffusion barrier in the inner cortex, restricts access to the central tissue where there is a high demand for and low concentration of O2. Observed variations in rates of nodule activities in response to imposed stresses, are often attributed to variations in the diffusion resistance of the barrier. In the present work, alternative or supplementary metabolic mechanisms are considered. Aspects of nodule structure and of metabolism underlying nodule activities are reviewed in terms of components of the symbiotic system, the nature of steady states and in relation to homeostasis of low concentration of O2 within the bacteroid-filled host cells. It is suggested that variations in O2-demand of both mitochondria and bacteroids, serve to preserve nitrogenase activity by poising O2 concentration within ‘safe’ limits. Further, data from isolated soybean bacteroids suggest that nitrogenase is converted to a less active but more robust form, in the presence of O2 in excess of about 70 nM, thus protecting nitrogenase from irreversible inactivation by excess O2. This regulation is rapidly-reversible when O2 concentration falls below about 0.1 µM. Respiration by large numbers of host mitochondria in the periphery of infected nodule cells, adjacent to gas-filled intercellular spaces, is considered to play an important part in maintaining a steep gradient of O2 concentration in this zone. Also, it is possible that variations in nodule O2 demand may be involved in the apparent variations in resistance of the diffusion barrier. It is concluded that there are many biochemical components which should be considered, along with possible changes to the diffusion barrier, when the effects of imposed stresses on nodule activities are being analysed.
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    URL: http://dx.doi.org/10.1023/A:1004236922993
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    The relationship between green spot initiation and plantlet regeneration of wheat callus grown under short-term conditions (1997)
    Springer
    Plant cell, tissue and organ culture 50 (1997), S. 67-69 
    Details
    ISSN: 1573-5044
    Keywords: immature embryos ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six wheat genotypes (three varieties and three whole chromosome substitution lines) were used to analyse the relationship between the initiation of green spots and plant regeneration under short-term tissue culture conditions. The highest percentage of green spot initiation was observed after one week culture on maintenance medium (M-Med.). The calluses producing green spots at the end of the first and second week on M-Med. were highest in regeneration frequency compared to late green spot producing ones. A significant positive correlation between green spot initiation and plantlet regeneration was observed for calluses showing green spots within the first two weeks on M-Med. and was decreased for calluses producing green spots afterwards. The results suggest that by selecting only calluses producing early green spots the experimental efficiency will be increased.
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    URL: http://dx.doi.org/10.1023/A:1005855912655
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    Isolation, identification and characterization of disomic and translocated barley chromosome addition lines of common wheat (1997)
    Springer
    Euphytica 96 (1997), S. 289-296 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; Hordeum vulgare ; wheat ; barley ; chromosome addition lines ; translocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two disomic barley chromosome addition lines and five translocated chromosome addition lines of common wheat cultivar Shinchunaga were isolated. They were derived from a hybrid plant between Shinchunaga and cultivated barley Nyugoruden (New Golden) by backcrossing with wheat and self pollination. Barley chromosomes added to chromosome arms involved in the translocated chromosomes were identified by C-banding method and by crossing these lines with Chinese Spring/Betzes addition lines. Two disomic addition lines were identified to have chromosome 6 and 7 of barley, respectively. Two of the five translocated chromosome addition lines were clarified to have same chromosome constitution, 42 wheat chromosomes and a pair of translocated chromosomes constituted with a long arm of chromosome 5B of wheat and a short arm of chromosome 7 of barley. The other three lines could not be identified due to chromosome rearrangement. Performances of these seven lines on agronomic characters were examined. Addition of barley chromosome 7 induced early heading, and chromosome 6 showed lated heading. Almost all of the lines except that of chromosome 6 showed short culm length and all showed reduced number of tillers, spikelets and grains per ear, and low seed fertility. These lines would be useful for genetic analyses in wheat and barley and for induction of useful genes of barley into wheat.
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    Structuring genotype × environment interaction for quality traits in bread wheat, in two multi-location series of trials (1997)
    Springer
    Euphytica 97 (1997), S. 53-66 
    Details
    ISSN: 1573-5060
    Keywords: clustering procedure ; genotype × environment interaction ; multi-trait analysis ; quality ; wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Structure of genotype × environment interaction was studied in two series of trials for three quality traits in bread wheat. Two kinds of environments were present in each series of trials: macro-environments defined as locations or location × year combinations and micro-environments induced by diversified cultural practices within each site. For each trait, a simultaneous clustering procedure was used to identify groups of environments which were homogeneous for interaction. An optimised series of trials was proposed from the clusters obtained. The cultural practice based on nitrogen fertilisation seemed to better diversify environments for interaction than use of fungicide, when all quality traits were considered. Determining an optimised series of trials simultaneously for the three traits led to keeping more environments than when one trait was considered. Suggestions for establishing a series of trials for a multi-trait analysis were proposed.
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    URL: http://dx.doi.org/10.1023/A:1003048720423
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    Genetic suppression of the cereal rye-derived gene Pm8 in wheat (1997)
    Springer
    Euphytica 93 (1997), S. 353-360 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; Secale cereale ; powdery mildew ; Erysiphe graminis f.sp. tritici ; resistance ; suppression ; segregation distortion ; wheat ; rye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The location of wheat gene Pm8 for resistance to powdery mildew in the 1RS chromosome segment derived from cereal rye cultivar Petkus was confirmed. There was reduced transmission of the 1BL.1RS chromosome relative to its wheat homologue in four of the five crosses examined. Pm8 was not expressed in some wheat cultivars and selections which possessed the 1RS chromosome identified by the presence of relevant genes for resistance to the three rusts, due to the presence of a dominant suppressor gene(s) in the wheat genome. The frequency of suppression in 1BL.1RS wheats from Mexico was significantly higher than in a group of wheats (both local and exotic) introduced from China and was probably much higher than in European wheats.
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    The genetics of rachis fragility and glume tenacity in semi-wild wheat (1997)
    Springer
    Euphytica 94 (1997), S. 119-124 
    Details
    ISSN: 1573-5060
    Keywords: glume tenacity ; inheritance ; rachis fragility ; spelta ; semi-wild wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The inheritance of rachis fragility and glume tenacity in semi-wild wheat was studied in an attempt to help establish the taxonomic status and genetic origin of semi-wild wheat. Progenies of crosses and backcrosses of semi-wild wheat with the cultivar Columbus (common wheat) indicated that the fragile rachis and non-free-threshing character of semi-wild wheat were dominant to the tough rachis and free-threshing character of common wheat. F2 and backcross data indicated that the rachis fragility and glume tenacity of semi-wild wheat were each controlled by a single gene in the cross of semi-wild wheat with Columbus. In the cross of semi-wild wheat with Triticum aestivum spp. spelta, the F2 and F3 population did not segregate for glume tenacity, but did segregate for rachis fragility. The F2 and backcross data suggest that three genes interact to control three types of rachis fragility, i.e. semi-wild wheat-type, spelta-type and the tough rachis of common wheat. Semi-wild wheat differs from common wheat in rachis fragility and glume tenacity. This wheat also differs from other wheats with fragile rachis and tenacious glumes (T. aestivum ssp. spelta, macha and vavilovii) in the pattern and degree of rachis disarticulation. We conclude that semi-wild wheat is likely a subspecies within T. aestivum at the same taxonomic level as spp. spelta, macha and vavilovii.
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    Effect of genome and ploidy on photosynthesis of wheat (1997)
    Springer
    Euphytica 94 (1997), S. 303-309 
    Details
    ISSN: 1573-5060
    Keywords: photosynthesis ; hexaploid wheat ; A genome ; D genome ; polyploidy ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We assessed (1) the effects of addition and doses of the D genome from different sources and (2) the addition of either the A genome or the D genome on the photosynthesis of synthesized hexaploid wheats. On average, the increased doses of the D genome reduced photosynthesis, but the depression was dependent on the source of the D genome. Two accessions of Aegilops squarrosa had depressed photosynthetic rates, but not another accession of Ae. squarrosa. The D genome of cv. Thatcher did not contribute to depress photosynthetic rate. Triticum monococcum had considerably higher photosynthetic rates than Ae. squarrosa. However, addition of the A genome from T. monococcum did not increase the photosynthetic rates of hexaploids. Chlorophyll a : b ratio, functional photosystem II and the core complex of photosystem II did not account for the variation in photosynthetic rate among the genotypes studied. In our experiment, photosynthesis of polyploids was not dependent on photosynthesis rates of the donor genomes.
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    Variation in sterility among wheat (Triticum aestivum L.) genotypes in response to boron deficiency in Nepal (1997)
    Springer
    Euphytica 95 (1997), S. 21-26 
    Details
    ISSN: 1573-5060
    Keywords: Boron ; genotypic variability ; sterility ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two field experiments were carried out at the Khairanitar Farm, Nepal during the winter season of 1993 to investigate whether wheat genotypes differ in their sterility response to low soil boron and whether boron added to soil can correct sterility. A nursery consisting of 41 diverse genotypes from Nepal, India, Bangladesh, Thailand, China, Pakistan and CIMMYT/Mexico were evaluated in a plot where severe sterility had been observed in previous years. The second experiment involved six genotypes of known sterility responses to boron grown with or without an application of boron at 1 kg ha-1. Large differences were observed among genotypes in terms of number of grain set per ear (range 0.5 to 30 ) and sterility (5.5% to 97.5%). About one third of all the genotypes had 〈25% sterility and 16 of them suffered 〉75% sterility. The genotypes Fang-60, Sonalika, De Mai 6-22, BUC/FLK/MYNA/VL and HDW-234 were highly tolerant to boron deficiency with 〈10% sterility. In sharp contrast, genotypes BOW/BUT, SERI/THB, Glennson, SW-41, Yunmai-33 and UHU were highly susceptible and set virtually no grains in the boron deficient plots. Strong responses to boron application were observed and genotypic variations were evident. Boron at 1 kg ha-1significantly reduced the number of late ears, increased number of grains per ear and grain yield in boron-responsive genotypes. Tolerant genotypes were not influenced by added boron. Given these striking genetic differences, progress in breeding wheat for B-deficient soils in Nepal should be worthwhile.
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    Emission of water stress ethylene in wheat (Triticum aestivum L.) ears: effects of rewatering (1997)
    Springer
    Plant growth regulation 21 (1997), S. 121-126 
    Details
    ISSN: 1573-5087
    Keywords: Triticum aestivum ; water stress ; ethylene ; antioxidant enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this work it has been found that ethylene production increased only slightly under conditions of a moderate or severe water stress. However, the rehydration of the plants at full turgor after desiccation caused a high emission of ethylene. The desiccation would not irreversibly inactivate the enzymes of the ethylene pathway, since rehydration made the synthesis recommence almost immediately. Water deficit also increased the free radical levels and the antioxidant scavengers, such as superoxide dismutase. Free radicals promote the conversion of 1-amino-cyclopropane-1-carboxylic acid to ethylene, then it is logical to think that both chemical species are involved in the phenomenon of the acceleration of the grain maturity before the plant collapses.
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    The status and distribution of lake sturgeon, Acipenser fulvescens, in the Canadian provinces of Manitoba, Ontario and Quebec: a genetic perspective (1997)
    Springer
    Environmental biology of fishes 48 (1997), S. 299-309 
    Details
    ISSN: 1573-5133
    Keywords: postglacial recolonization ; anthropogenic influences ; fish ; Acipenseridae ; conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic analysis of mitochondrial DNA sequence variation indicates that most of a sample of 396 lake sturgeon, Acipenser fulvescens, from the northern part of their range belonged to either one of two haplotypes. The vast majority of fish from the Great Lakes/St. Lawrence and Mississippi drainages were of a single haplotype while those from the Hudson/James Bay were composed of both haplotypes. This haplotypic distribution suggests that fish from one refugium (possibly Missourian) recolonized the Hudson-James Bay drainage while those from a second (possibly Mississippian) recolonized the Laurentian Great Lakes and St. Lawrence River. Lake sturgeon still inhabit much of their native postglacial distribution in Manitoba, Ontario and Quebec. However, the stresses of commercial overexploitation and habitat alteration, usually through hydroelectric dam construction and operation, have either singly or in tandem brought about the reduction, if not extirpation, of some populations within the range. The largest zone of extirpation and population reduction has occurred in the Lake Winnipeg drainage area, which covers more than one-third of Manitoba. Other areas where populations have been reduced to remnant levels, if not extirpated, include the lower Laurentian Great Lakes of Lake Ontario and Lake Erie. In northern Ontario, lake sturgeon populations whose riverine habitats have been fragmented by two or more dams are substantially reduced from their former levels. In Quebec, more attention has been paid to limiting the exploitive stresses on lake sturgeon populations. Combination of the genetic and status data suggests that both northern and southern populations of lake sturgeon (possibly from two glacial refugia) have been impacted severely from anthropogenic influences.
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    Weight-length relationship and condition of the characiform Triportheus guentheri (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 319-330 
    Details
    ISSN: 1573-5133
    Keywords: condition factor ; biometric indices ; Brazil ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sources of variations in the weight-length relationship parameters, and in the Fulton's, allometric, and relative condition factors (K) of the characiform fish Triportheus guentheri were investigated. The use of these indices as indicators of condition were also discussed. The 2899 females and 2491 males were captured with gill nets from January 1986 to March 1988 in Três Marias Reservoir (18° 15′ and 45° 15′ W), Brazil. Weight-length relationship parameters varied monthly in both sexes mainly due to the skewness of the relative frequency of the number of fish per body length. This suggests that a selective sample and/or the population length structure may strongly influence the estimate of those parameters. The K showed high correlations (r ≥ 0.99) among themselves. Their variations were ascribed to carcass weight in both sexes when analyzed by month, or to the ovary weights when analyzed by female gonad development intervals. The monthly weight-length relationship parameters of T. guentheri presented low or null correlation with K, except for the female's coefficient of regression. Problems using these parameters as indicators of condition suggested that they are not good indices to express condition. Some restrictions regarding the use of K are discussed.
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    General response patterns of fish populations to stress: an evaluation using an individual-based simulation model (1997)
    Springer
    Journal of aquatic ecosystem stress and recovery 6 (1997), S. 15-31 
    Details
    ISSN: 1573-5141
    Keywords: contaminants ; fish ; general response patterns ; individual-based ; population dynamics ; simulation model ; yellow perch ; walleye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract General response patterns of fish populations tostress, originally proposed by Colby for fisheriesrehabilitation and later adapted by Munkittrick forcontaminants, were evaluated using an individual-basedsimulation model. General response patterns relatechanges in population-level variables to the type ofstress. The model follows the daily growth,mortality, and spawning of individual yellow perch andwalleye through their lifetime, and was corroboratedusing Oneida Lake data. Two versions of the model wereused: population (yellow perch only) and community(dynamic predation on yellow perch by walleye). Eightstresses were imposed on the population and communityversions of the model and 100-year simulations wereperformed. Response patterns were defined by changesin predicted yellow perch mean population abundance,mean age of adults, and mean adult growth (representedby mean length at age-7). Proposed response patternswere similar to those predicted using the populationversion of the model. Simulations using the communityversion of the model distorted the response patterns,either causing amplification, dampening, or reversalof many of the patterns. Predicted response patternsbecame unique when additional variables were included.Our model results suggest that caution is appropriatein interpreting general response patterns based onmean age, or when the population of interest plays amajor role in a relatively simple food web. The responsepattern approach may be better at identifying the lifestage impacted rather than the mechanism of the stress.
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    Characterization of molecular variants of GnRH, induction of spermiation and sex reversal using salmon GnRH-A and domperidone in the protogynous diandric fish, Synbranchus marmoratus Bloch, (Teleostei, Synbranchidae) (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 425-436 
    Details
    ISSN: 1573-5168
    Keywords: fish ; GnRH ; domperidone ; hermaphroditism ; protogynous ; diandric ; sex reversal ; spermiation ; Synbranchidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper studies the molecular variants of gonadotropin-releasing hormone (GnRH) present in the brain of the protogynous swamp eel, Synbranchus marmoratus, and the effects of the administration of salmon GnRH analogue (sGnRH-A) and the dopamine receptor antagonist, domperidone (DOM) on final maturation and gamete release in this species. Evidence for the presence of two GnRH variants, sGnRH and cIIGnRH were obtained by reverse phase high-pressure liquid chromatography (RP-HPLC) and radioimmunoassay with different antisera. The effects of treatment with sGnRH-A+DOM were checked by three ways: oocyte and milt release by stripping, histological analysis of the gonadal tissue, and androgen serum levels at different times throughout the experiment. In males, spermiation was induced after three weeks of treatment. In the female group, sGnRH-A+DOM did not induce ovulation at the end of the experiment. Histological analysis of the gonads from the female group showed evidence of sex reversal. All the treated fish had elevated androgen serum levels from the third week, with respect to control fish. In all cases, serum estradiol levels were undetectable. These results suggest that treatment with sGnRH analog and DOM induce sex reversal in female and spermiation in males.
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    URL: http://dx.doi.org/10.1023/A:1007772416539
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    Plasticity of the properties of mitochondria from rainbow trout red muscle with seasonal acclimatization (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 531-541 
    Details
    ISSN: 1573-5168
    Keywords: mitochondria ; muscle ; thermal acclimatization ; fish ; substrate preferences ; phospholipid fatty acid composition ; oxidative capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cold-acclimation of rainbow trout brings only limited changes in muscle metabolic capacities, but marked modifications in membrane composition. Thus, we examined whether the functional properties of mitochondria from trout red muscle were modified by seasonal temperature acclimatization. Mitochondria from fall-acclimatized trout had higher maximal capacities (state 3 rates) for the oxidation of pyruvate and acyl carnitines at 12 and 20 °C than mitochondria isolated from summer-acclimatized trout. For these substrates, the increased oxidative capacity completely compensated for the seasonal drop in temperature. Pyruvate and palmitoyl carnitine were consistently the preferred substrates, while decanoyl and octanoyl carnitine were oxidized at higher rates than glutamine, particularly in fall trout. State 4 rates of oxygen uptake (obtained when all ADP has been converted to ATP) differed less among substrates, but varied seasonally. State 4 rates at 12 and 20 °C were higher in mitochondria isolated from fall than summer trout. At low temperatures, the Q10 of both maximal and state 4 rates of substrate oxidation tended to be higher for mitochondria from fall trout. The apparent Arrhenius activation energy (Ea) for mitochondrial pyruvate oxidation was higher in fall than summer trout whereas the Ea’s for palmitoyl carnitine and decanoyl carnitine oxidation did not change. The fatty acids of mitochondrial phospholipids from fall trout were more polyunsaturated than those from summer trout, with 12% more double bonds occurring than in summer trout, suggesting that membrane restructuring may be involved in the observed compensatory responses.
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    URL: http://dx.doi.org/10.1023/A:1007708826437
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    Reproduction related immunoglobulin changes in rainbow trout (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 415-421 
    Details
    ISSN: 1573-5168
    Keywords: fish ; trout ; reproduction ; seasonal changes ; immunoglobulin ; testosterone ; estradiol-17β ; 11-ketotestosterone ; water temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Annual changes in plasma immunoglobulin (IgM) levels were investigated in three strains of rainbow trout Oncorhynchus mykiss which have different spawning periods, i.e., September–October, November–December, and January, reared under constant water temperature and natural day length. Plasma IgM levels decreased during the spawning season in all strains tested. The IgM changes became reversed in response to significant increases in plasma testosterone (T) and estradiol-17β in females and T and 11-ketotestosterone in males. Though the IgM decline showed a connection with suppressed immunocompetence, since many mature fish caught fungal diseases, no clear differences were observed in the plasma IgM levels between infected and noninfected fish during the spawning season. Incidentally, plasma IgM levels in infection prone fish were higher than in noninfection prone fish prior to the spawning season, whereas coincident differences in the plasma steroid levels were observed. Immature fish reared under lower water temperatures showed lower IgM levels. The effect of water temperature may have to be considered when analyzing the defense mechanism during the spawning season in rainbow trout.
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    URL: http://dx.doi.org/10.1023/A:1007795827112
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    Transcriptional regulation of fish growth hormone gene (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 237-246 
    Details
    ISSN: 1573-5168
    Keywords: fish ; growth hormone gene ; thyroid hormone ; transcription ; DNA response element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcription of growth hormone (GH) genes in vertebrates depends, among other factors, on pituitary specific transcription factors (such as Pit-1) and on thyroid hormone (TH) and TH receptors. Gel retardation experiments indicated the presence of proteins in the carp pituitary nuclear extract that specifically bind the Pit-1 DNA response element and the adjacent putative TH DNA response element (TRE), on the Atlantic salmon (Salmo salar) GH proximal promoter. The putative TRE element competes effectively in vitro in gel retardation assays with 4×TREpal, a consensus TRE element, on zebrafish (Danio rerio) purified recombinant TH receptor (zfTHR). The zfTHR/TRE complex can also be further identified with antibodies to rat THR that causes the complex a supershift in gel retardation assay. Cross competition was observed in nuclear extracts between the TRE and Pit-1 sites. It was found that 100 molar fold excess of Pit-1 binding element can compete effectively with the TH binding element and reduce its binding activity. The endogenous TRE binding element, on the other hand, cannot effectively reduce the binding activity of the Pit-1 DNA binding element. This unexpected competition between the two sites was examined in the presence and absence of the hormones: TH, 9-cis retinal, and TH + 9-cis retinal. The addition of the two hormones together significantly increased the binding properties of the TH response element as compared to its binding in the absence of the hormones, and also improved its binding activity in the presence of the Pit-1 DNA competitor. In summary, the two adjacent sites that control GH gene transcription, Pit-1 and TRE, on the fish GH promoter exhibit some degree of interaction between their respective transcription factors, the Pit-1 protein and the thyroid/retinoic acid receptors.
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    URL: http://dx.doi.org/10.1023/A:1007762325604
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    Critical thermal maxima of diploid and triploid brook charr, Salvelinus fontinalis (1997)
    Springer
    Environmental biology of fishes 49 (1997), S. 259-264 
    Details
    ISSN: 1573-5133
    Keywords: triploidy ; thermal tolerance ; lethal limits ; brook trout ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The purpose of this experiment was to determine whether diploid and triploid brook charr, Salvelinus fontinalis, differ in their critical thermal maxima (CTM). Two age classes were tested (underyearlings, having average weight of 25 g, and yearlings, having average weight of 668 g) at two rates of temperature increase (2° C h-1 and 15° C h-1). No effect of ploidy on CTM was found. Fish exposed to the faster rate of temperature increase had higher CTM values than those exposed to the slower rate (underyearlings: 29.5 ± 0.1° C versus 29.1 ± 0.1° C in one trial and 29.8 ± 0.1° C versus 28.3 ± 0.1° C in a second trial; yearlings: 29.3 ± 0.1° C versus 27.7 ± 0.1° C in two trials, p 〈 0.001 in all cases). Underyearlings had higher CTM values than yearlings (29.2 ± 0.1° C versus 28.5 ± 0.1° C, p 〈 0.05). Female yearlings, which were immature, had higher CTM values than males, which had previously matured as one-year-olds (28.8 ± 0.1° C versus 28.3 ± 0.1° C, p 〈 0.001).
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    URL: http://dx.doi.org/10.1023/A:1007361231325
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    Predation of zebra mussels by round gobies, Neogobius melanostomus (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 267-273 
    Details
    ISSN: 1573-5133
    Keywords: exotic species ; laboratory experiment ; size selectivity ; Great Lakes ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preliminary gut analysis of a recent Great Lakes invader, the round goby, Neogobius melanostomus (7.0–8.4 cm), collected from the Detroit River, showed that they ate zebra mussels (58%), snails (6%), and other invertebrates (36%), including aquatic insects (Hexagenia), softshelled crayfish, and zooplankton. Because zebra mussels, Dreissena polymorpha, predominated as prey, we investigated the ability of round gobies to consume different size classes of zebra mussels. In laboratory experiments, we examined feeding preferences of three size classes of round gobies (5.5–6.9 cm; 7.0–8.4 cm; 8.5–10.3 cm standard length) on four different size classes of zebra mussels (6.0–9.9 mm, 10.0–12.9 mm, 13.0–15.9 mm, 16.0–18.9 mm). All sizes of round gobies ate zebra mussels 〈 10.0 mm. Only the largest size class of round gobies ate larger zebra mussels (10.0–12.9 mm) when all prey sizes were presented. The association between the total mass of zebra mussels available and the amount consumed by round gobies increased positively up to about 6.5 g of available mussels and then levelled off. Round gobies consumed an average of 1.0 g of mussels in 24 h. There was a significant positive relationship between gape size and standard length of round gobies. Although larger round gobies (over the size range of fish in our study) are able to consume larger zebra mussels, small mussels were preferred. Our findings suggest that the preference of small zebra mussels by round gobies has the potential to alter the size structure of zebra mussel populations.
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    URL: http://dx.doi.org/10.1023/A:1007379220052
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    Proton pumps in the fish gill and kidney (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 363-369 
    Details
    ISSN: 1573-5168
    Keywords: vacuolar ATPase ; proton pump ; gill ; kidney ; acid-base regulation ; ionic regulation ; chloride cell ; pavement cell ; cortisol ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The proton pump or vacuolar type H+-ATPase is an oligomeric protein responsible for electrogenic H+ secretion in a variety of acid-secreting epithelia. Recently, the proton pump was identified in both the gill and kidney of freshwater-adapted rainbow trout (Oncorhynchus mykiss). Using immunocytochemistry, H+-ATPase has been localized in the pavement cells and chloride cells of the lamellar epithelium. During periods of internal acidosis, there is a marked increase in the expression of the branchial proton pump as identified by Western analysis, immunocytochemistry and in situ hybridization. This augmented expression of proton pumps occurs concomitantly with a marked increase in branchial acid excretion and Na+ uptake. Immunocytochemical studies suggest that the pavement cell, rather than the chloride cell, is the predominant site of acid excretion during periods of acidosis. These findings are consistent with the notion that in freshwater teleosts, Na+ uptake and H+ excretion are linked via the coupling of the electrogenic proton pump to apical membrane Na+ channels. This mechanism may be controlled by hormones including cortisol and/or growth hormone. The fish kidney plays an important role in regulating acidosis via the re-absorption of filtered HCO3 -. Recently, we have demonstrated using Western analysis and immunocytochemistry, the presence of proton pump in rainbow trout kidney and observed increased H+-ATPase expression during respiratory acidosis. These new findings suggest a role for the renal proton pump in acid-base regulation.
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    URL: http://dx.doi.org/10.1023/A:1007746217349
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    Seasonal variation of muscle metabolic organization in rainbow trout (Oncorhynchus mykiss) (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 139-155 
    Details
    ISSN: 1573-5168
    Keywords: season ; metabolic organization ; muscle ; fish ; temperature ; lipid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examined how muscle metabolic organization varied during an annual cycle in which rainbow trout (Oncorhynchus mykiss) were held in outdoor holding ponds in which they were exposed to natural changes in temperature (range 0.2 to 15.6°C) and photoperiod. We examined the activities of glycolytic and mitochondrial enzymes in red and white muscle to evaluate whether trout enhance their capacity for lipid and carbohydrate oxidation during cold-acclimization. When assayed at habitat temperature, the enzyme activities generally increased in spring to reach a maximum in summer followed by a decrease in the fall. This led to significantly higher activities at warm than cold periods for all enzymes measured in red muscle and all but one in white muscle. The activities at 10°C provided little evidence for compensatory adjustments of aerobic capacity. Particularly in red muscle, enzyme levels at 10°C were generally lower during cold than warm periods. The variation of enzyme activities throughout the cycle was not due to changes in protein concentration, as the same responses were observed when activities were expressed per g wet mass or per mg protein. Although the aerobic capacity did not increase with cold-acclimatization, the relative capacity for lipid oxidation was higher in winter than in summer trout. In contrast, the relative capacity for aerobic glycolysis was higher in summer than in winter trout. Thus, the metabolic capacities of trout muscle undergo seasonal reorganization.
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    URL: http://dx.doi.org/10.1007/BF00004671
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    Vascular actions of neurohypophysial peptides in the flounder (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 313-318 
    Details
    ISSN: 1573-5168
    Keywords: teleost ; fish ; blood pressure ; arginine vasotocin ; isotocin ; ventral aorta ; dorsal aorta ; neurohypophysial hormone receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Free swimming, chronically cannulated flounder have been used to study the blood pressure effects of arginine vasotocin (AVT) and isotocin. The initial fall in dorsal aortic blood pressure following AVT injection coincided with an increase in ventral aortic blood pressure, suggesting AVT caused constriction of the arterio-arterial pathway. Ventral aortic blood pressure increased in a dose dependent manner with increasing AVT dose. Dorsal aortic blood pressure also increased following the initial fall but not in a dose dependent manner, the effect at higher doses being off set by branchial vasoconstriction. Isotocin also caused dorsal aortic blood pressure to fall due to branchial vasoconstriction, but no subsequent pressor effect was seen. Branchial vasoconstriction caused by both teleost neurohypophysial peptides suggests the presence of neurohypophysial peptide receptor(s) in the gill, although it is unclear as to whether this is a single common receptor or different populations for each peptide. The dorsal aortic pressor effect of AVT and its absence following isotocin injection suggests there may be other types of neurohypophysial receptors in post-branchial vascular beds. The vascular actions of AVT and isotocin suggest that these peptides may play some role in the regulation of blood pressure or regional blood flow distribution.
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    URL: http://dx.doi.org/10.1023/A:1007745821969
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    Effects of low temperature on induction and differentiation of wheat calluses (1997)
    Springer
    Plant cell, tissue and organ culture 49 (1997), S. 35-38 
    Details
    ISSN: 1573-5044
    Keywords: callus ; regeneration ; tissue culture ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Young inflorescences and long-term culture calluses of wheat (Triticum aestivum L.) were used to investigate the effect of low temperature treatment on the potential of plant regeneration. The results indicated that the frequency of callus induction from immature inflorescences was decreased when treated for a long time at 5 °C. However, it was found that a 5 °C treatment significantly improved the regeneration frequency of calluses. The clear difference of peroxidases of wheat calluses was apparent after the cultures were treated at the low temperature. The isozyme band 8 became clearly faint, however, bands 6 and 9 became intense.
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    Regulation of gene expression and biological activity of rainbow trout estrogen receptor (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 123-133 
    Details
    ISSN: 1573-5168
    Keywords: reproduction ; steroid receptors ; estradiol ; estrogen receptor ; vitellogenin ; liver ; hepatocyte ; gene transcription ; mRNA stability ; fish ; rainbow trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rainbow trout estrogen receptor (rtER) concentration was highly induced in the liver after in vivo estradiol (E2) treatment or in vitro, in hepatocyte aggregate culture. Determination of transcription rate and mRNA half-life demonstrated that E2-induction of hepatic rtER level is caused essentially by an increase in the transcriptional and post-transcriptional activity of rtER gene. However, the expression of rtER gene in the liver seems to be down-regulated by glucocorticoids. We have used transient transfection assays with reporter plasmids linked to 5′ flanking regions of the rtER gene promoter, to identify cis-elements responsible for E2 inducibility. Deletion analysis localized a functional estrogen-responsive-element (ERE), near the transcription start site, with one mutation on the first base compared to the consensus sequence. This element and 200 bp fragment of the rtER promoter encompassing the ERE appear to be the major cis-acting element involved in the regulation of the gene. Data obtained from transfection experiments and footprinting analysis, suggested that the receptor is one of the major trans-factors implicated in the regulation of its own gene. However, interaction of ER with other transcription factors is required for maximal E2-stimulation.
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    URL: http://dx.doi.org/10.1023/A:1007706207857
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    Ontogeny of somatolactin mRNA in the gilthead sea bream Sparus aurata (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 247-252 
    Details
    ISSN: 1573-5168
    Keywords: somatolactin ; growth hormone ; mRNA ; Northern ; fish ; Sparus aurata ; embryos ; larvae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of somatolactin (SL) gene during embryonal and early stages of larval development of the teleost Sparus aurata was determined by Northern blot analysis. Poly(A+)RNA was prepared from a pool of embryos collected at early and late stages or from larvae collected on different days after hatching. When hybridized to Sparus aurata SL cDNA, SL specific mRNA was seen both in embryos and in larvae. Levels of SL increased from day 1 onwards and reached the highest levels on day 21. Re-hybridization with Sparus aurata growth hormone (GH) cDNA revealed GH specific mRNA first on day 6 post-hatching. Levels of GH increased to maximal levels on day 10 and then decreased on days 15 and 21, thereby confirming the pattern of GH expression (Funkenstein and Cohen 1996). The patterns of SL and GH gene expression are different in gilthead sea bream during embryonal and larval development. Furthermore, the presence of SL transcript in embryos, prior to pituitary gland development, suggests the possibility that SL mRNA of maternal origin may be present in the oocyte.
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    URL: http://dx.doi.org/10.1023/A:1007714409674
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    Gonadotropin-releasing hormone and gonadotropin in goldfish and masu salmon (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 1-8 
    Details
    ISSN: 1573-5168
    Keywords: gonadotropin-releasing hormone ; GnRH ; gonadotropin ; GTH ; reproduction ; reproductive endocrinology ; gonadal development ; fish ; goldfish ; masu salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reproductive activities in vertebrates are regulated by an endocrine system, consisting of the brain-pituitary-gonad axis. In teleosts, gonadotropin-releasing hormone (GnRH) in the brain stimulates gonadotropin (GTH) release in the pituitary gland, but because of lack of the portal vessel, it is not known when and how much GnRH is released for the regulation of GTH release. There are multiple molecular types of GnRH in teleosts and several distinct populations of GnRH neurons in the brain. However, we do not know which types and populations of GnRH neurons regulate reproductive activities. Here we summarize our recent studies on GnRH and GTH in masu salmon Oncorhynchus masou and goldfish Carassius auratus. Immunocytochemistry showed the location and molecular types of GnRH neurons. Salmon (sGnRH) and chicken-II GnRH (cGnRH-II) neuronal fibers were widely distributed in the brain of both masu salmon and goldfish. Only sGnRH fibers were observed in the pituitary of masu salmon, whereas both sGnRH and cGnRH-II fibers were observed in the goldfish pituitary, indicating that species specific GnRH profiles are involved in the regulation of pituitary function in teleosts. A series of experiments in masu salmon and goldfish suggest that among GnRH neuron populations GnRH neurons in the ventral telencephalon and the hypothalamus regulate GTH release, and that GnRH of the terminal nerve origin is not essential to gonadal maturation and ovulation. The biological function of other GnRH neurons remains unkown. Two GTHs appear to be characteristic of teleost; however, regulation of reproduction by these GTHs is a question that remains to be elucidated. In salmonid species, it is proposed that GTH I stimulates early gonadal development, whereas GTH II acts in later stages. When GTH expression was examined in goldfish, both GTH I β and II β mRNA levels in the pituitary gland showed increases in accordance with gonadal development, unlike the sequential expression of GTH subunits in salmonids. The expression of these GTH subunit mRNAs were affected by water temperature, starvation, and steroid hormones in goldfish, but in what manner these two GTHs regulate gonadal development remains to be clarified.
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    Steady-State Proton Translocation in Bovine Heart Mitochondrial bc 1 Complex Reconstituted into Liposomes (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 81-87 
    Details
    ISSN: 1573-6881
    Keywords: bc 1 complex ; mitochondria ; cytochromes ; transmembrane pH difference ; H+/e − ratio ; decoupling ; azide ; arachidonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of different anions on the steady-state proton translocation in bovine bc 1 complex reconstituted in liposomes was studied. The H+/e − ratio for vectorial proton translocation is at the steady state definitely lower than that measured at level flow, (0.3 vs. 1.0). The presence of azide or arachidonate at micro- and submicromolar concentrations, respectively, gave a substantial reactivation of the proton pumping activity at the steady state, without any appreciable effect on respiration-dependent transmembrane pH difference. Addition of azide to turning-over bc 1 vesicles also caused a transition of b cytochromes toward oxidation. The results are discussed in terms of possible involvement of an acidic residue in the protonation of the semiquinone/quinol couple at the N side of the membrane.
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    URL: http://dx.doi.org/10.1023/A:1022467923837
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    Nuclear Control of Respiratory Chain Expression in Mammalian Cells (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 109-119 
    Details
    ISSN: 1573-6881
    Keywords: ETS domain ; gene expression ; mammalian cells ; mitochondria ; nuclear respiratory factors ; oxidative phosphorylation ; regulation ; respiratory chain ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The majority of gene products required for mitochondrial respiratory function are encoded in the nuclear genome. These include most of the respiratory subunits and all of the proteins that regulate the mitochondrial genetic system. One approach to understanding nucleo-mitochondrial interactions in mammalian cells is to identify the nuclear transcription factors that are common to the expression of these gene products. This has led to the purification and molecular cloning of nuclear respiratory factors, NRF-1 and NRF-2. The DNA binding and transcriptional specificities of these proteins have implicated them in the expression of many respiratory subunits along with key components of the mitochondrial transcription, replication, and heme biosynthetic machinery. In addition, tissue-specific transcription factors have been linked to the coordinate synthesis of contractile proteins and muscle-specific respiratory subunits whereas other more ubiquitous factors may have a dual function in nuclear and mitochondrial gene activation. These findings provide a framework for further investigations of the nuclear genetic mechanisms that integrate the expression of the respiratory apparatus with that of other cellular systems during growth and development.
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    URL: http://dx.doi.org/10.1023/A:1022681828846
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    Cardiolipin Remodeling in a Chinese Hamster Lung Fibroblast Cell Line Deficient in Oxidative Energy Production (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 291-298 
    Details
    ISSN: 1573-6881
    Keywords: Cardiolipin metabolism ; CCL16-B2 cells ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The metabolism of cardiolipin was investigated in a Chinese hamster lung fibroblast cell line CCL16-B2 deficient in oxidative energy metabolism and its parental cell line CCL16-B1. Mitochondrial enzyme activities involved in de novo cardiolipin biosynthesis were elevated in CCL16-B2 cells compared with CCL16-B1 cells, indicating initially an elevation in cardiolipin biosynthesis. Content of all phospholipids, including cardiolipin and its precursors, and high energy nucleotides were unaltered in CCL 16-B2 cells compared to CCL 16-B1 cells. When cells were incubated with [1,3-3H]glycerol for up to 4 h radioactivity incorporated into cardiolipin in CCL16-B2 cells did not differ compared with CCL16-B1 cells. In contrast, radioactivity incorporated into phosphatidylglycerol, the immediate precursor of cardiolipin, was elevated over 2-fold in CCL16-B2 cells compared with CCL16-B1 cells. Analysis of the fatty acid molecular species in cardiolipin revealed alterations in the level of unsaturated but not saturated fatty acids in B2 compared with B1 cells. In vivo cardiolipin remodeling, that is, the deacylation of cardiolipin to monolysocardiolipin followed by reacylation back to cardiolipin, with [1-14C]palmitate and [l-14C]oleate and in vitro mitochondrial phospholipid remodeling with [1-14C]linoleate were altered in CCL16-B2 cells compared to CCL16-B1 cells. Since both the appropriate content and molecular composition of cardiolipin is required for optimum mitochondrial oxidative phosphorylation, we suggest that the difference in CL molecular species composition observed in CCL16-B2 cells, mediated by alterations in in vivo cardiolipin remodeling, may be one of the underlying mechanisms for the reduction in oxidative energy production in CCL16-B2 cells.
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    URL: http://dx.doi.org/10.1023/A:1022418328922
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    On the Structure and Gating Mechanism of the Mitochondrial Channel, VDAC (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 525-531 
    Details
    ISSN: 1573-6881
    Keywords: Porin ; ion channel ; mitochondria ; VDAC ; electron microscopy ; sequence analysis ; β-barrel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract There is considerable evidence that the voltage-gated mitochondrial channel VDAC forms a β-barrel pore. Inferences about the number and tilt of β-strands can be drawn from comparisons with bacterial β-barrel pores whose structures have been determined by x-ray crystallography. A structural model for VDAC is proposed (based on sequence analysis and electron crystallography) in which the open state is like that of bacterial porins with several important differences. Because VDAC does not occur as close-packed trimers, there are probably fewer interpore contacts than in the bacterial porins. VDAC also appears to lack a large, fixed intraluminal segment and may not have as extensive a region of uniformly 35°-tilted β-strands as do the bacterial porins. These structural differences would be expected to render VDAC's β-barrel less stable than its bacterial counterparts, making major conformational changes like those associated with gating more energetically feasible. A possible gating mechanism is suggested in which movement of the N-terminal α-helix out of the lumen wall triggers larger-scale structural changes.
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    URL: http://dx.doi.org/10.1023/A:1022489832594
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  • 90
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    The First Steps of Protein Import into Mitochondria (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 11-17 
    Details
    ISSN: 1573-6881
    Keywords: Protein targeting ; protein import ; mitochondria ; molecular chaperones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Protein import into mitochondria is initiated by the recognition and binding of precursor proteins by import components in the cytosol, on the mitochondrial surface, and in the mitochondrial outer membrane. Following their synthesis on cytoplasmic ribosomes, some precursor proteins interact with molecular chaperones in the cytosol which function in maintaining the precursor protein in an import-competent state and may also aid in the delivery of the precursor to the mitochondria. A multisubunit protein import receptor then recognises and binds precursor proteins before feeding them into the outer membrane import site. Some proteins are sorted from the import site into the outer membrane, but most precursor proteins travel through the outer membrane import site into the mitochondria, where the later steps of protein import take place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022451520203
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    Molecular Chaperones and Mitochondrial Protein Folding (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 35-43 
    Details
    ISSN: 1573-6881
    Keywords: Chaperonins ; heat-shock proteins ; mitochondria ; molecular chaperones ; protein folding ; protein import
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Precursor proteins destined for the mitochondrial matrix traverse inner and outer organelle membranes in an extended conformation. Translocation events are therefore integrally coupled to the processes of protein unfolding in the cytosol and protein refolding in the matrix. To successfully import proteins from the cytoplasm into mitochondria, cells have recruited a variety of molecular chaperone systems and folding catalysts. Within the organelles, mitochondrial Hsp70 (mt-Hsp70) is a major player in this process and exerts multiple functions. First, mt-Hsp70 binds together with cohort proteins to incoming polypeptide chains, thus conferring unidirectionality on the translocation process, and then assists in their refolding. A subset of imported proteins requires additional assistance by chaperonins of the Hsp60/Hsp10 family. Protein folding occurs within the cavity of these cylindrical complexes. A productive interaction of precursor proteins with molecular chaperones in the matrix is not only crucial for correct refolding and assembly, but also for processing of presequences, intramitochondrial sorting, and degradation of proteins. This review focuses on the role of mt-Hsp70 and Hsp60/Hsp10 in protein folding in the mitochondrial matrix and discusses recent findings on their molecular mechanism of action.
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    URL: http://dx.doi.org/10.1023/A:1022407705182
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    Proton Pumping of Mitochondrial Complex I: Differential Activation by Analogs of Ubiquinone (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 71-80 
    Details
    ISSN: 1573-6881
    Keywords: NADH: ubiquinone reductase ; ubiquinone ; proton pumping ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract As part of the ongoing studies aimed at elucidating the mechanism of the energy conserving function of mitochondrial complex I, NADH: ubiquinone (Q) reductase, we have investigated how short-chain Q analogs activate the proton pumping function of this complex. Using a pH-sensitive fluorescent dye we have monitored both the extent and initial velocity of proton pumping of complex I in submitochondrial particles. The results are consistent with two sites of interaction of Q analogs with complex I, each having different proton pumping capacity. One is the physiological site which leads to a rapid proton pumping and a stoichiometric consumption of NADH associated with the reduction of the most hydrophobic Q analogs. Of these, heptyl-Q appears to be the most efficient substrate in the assay of proton pumping. Q analogs with a short-chain of less than six carbons interact with a second site which drives a slow proton pumping activity associated with NADH oxidation that is overstoichiometric to the reduced quinone acceptor. This activity is also nonphysiological, since hydrophilic Q analogs show little or no respiratory control ratio of their NADH:Q reductase activity, contrary to hydrophobic Q analogs.
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    URL: http://dx.doi.org/10.1023/A:1022415906999
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    Homologous and Heterologous Interactions between Hexokinase and Mitochondrial Porin: Evolutionary Implications (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 97-102 
    Details
    ISSN: 1573-6881
    Keywords: Hexokinase ; binding to mitochondria ; mitochondria ; binding of hexokinase to ; Porin ; VDAC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Binding of the Type I isozyme of mammalian hexokinase to mitochondria is mediated by the porin present in the outer mitochondrial membrane. Type I hexokinase from rat brain is avidly bound by rat liver mitochondria while, under the same conditions, there is no significant binding to mitochondria from S. cerevisiae. Previously published work demonstrates the lack of significant interaction of yeast hexokinase with mitochondria from either liver or yeast. Thus, structural features required for the interaction of porin and hexokinase must have emerged during evolution of the mammalian forms of these proteins. If these structural features serve no functional role other than facilitating this interaction of hexokinase with mitochondria, it seems likely that they evolved in synchrony since operation of selective pressures on the hexokinase–mitochondrial interaction would require the simultaneous presence of hexokinase and porin capable of at least minimal interaction, and be responsive to changes in either partner that affected this interaction. Recent studies have indicated that a second type of binding site, which may or may not involve porin, is present on mammalian mitochondria. There are also reports of hexokinase binding to mitochondria in plant tissues, but the nature of the binding site remains undefined.
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    URL: http://dx.doi.org/10.1023/A:1022472124746
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    ADP-Regulation of Mitochondrial Free Radical Production Is Different with Complex I- or Complex II-Linked Substrates: Implications for the Exercise Paradox and Brain Hypermetabolism (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 241-249 
    Details
    ISSN: 1573-6881
    Keywords: ADP ; mitochondria ; free radical production ; brain ; heart ; exercise ; hypermetabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract In agreement with classic studies, succinate-supplemented rat and pigeon heart and nonsynaptic brain mitochondrial free radical production is stopped by ADP additions causing the stimulation of respiration from State 4 to State 3. Nevertheless, with Complex I-linked substrates, mitochondria produce free radicals in State 3 at rates similar or somewhat higher than during resting respiration. The absence of sharp increases in free radical production during intense respiration is possible due to strong decreases of free radical leak in State 3. The results indicate that Complex I is the main mitochondrial free radical generator in State 3, adding to its already known important generation of active oxygen species in State 4. The observed rate of mitochondrial free radical production with Complex I-linked substrates in the active State 3 can help to explain two paradoxes: (a) the lack of massive muscle oxidative damage and shortening of life span due to exercise, in spite of up to 23-fold increases of oxygen consumption together with the very low levels of antioxidants present in heart, skeletal muscle, and brain; (b) the presence of some degree of oxidative stress during exercise and hyperactivity in spite of the stop of mitochondrial free radical production by ADP with succinate as substrate.
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    URL: http://dx.doi.org/10.1023/A:1022458010266
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    Localized Firefly Luciferase Probes ATP at the Surface of Mitochondria (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 549-559 
    Details
    ISSN: 1573-6881
    Keywords: Luciferase ; localized probe ; heterogeneous coupled systems ; mitochondria ; hexokinase ; nucleotide concentration gradients ; cellular catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The concentration of ATP generated by yeast mitochondria and consumed by yeast hexokinase was monitored using native firefly luciferase in solution, or recombinant luciferase localized at the surface of mitochondria. In the absence of hexokinase, both probes perform similarly in detecting exogenous or mitochondrially-generated ATP. The steady-state concentrations of ATP can be reduced in a dose-dependent manner by hexokinase. With hexokinase added in large excess, the localized probe reports substantial ATP concentrations while none is detectable by soluble luciferase. Thus, ATP accumulates near the membrane where it appears, relatively to solution, and vice versa for ADP. The extent of nucleotide gradients is shown to be correlated with the specific activity of oxidative phosphorylation and with the viscosity of the medium, but independent of the concentration of the organelles. A simple model involving diffusional restrictions is presented to describe this behavior. The metabolic and evolutionary implications of cellular catalysis limitation by physical processes are discussed.
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    URL: http://dx.doi.org/10.1023/A:1022478917573
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    Lineage-Specific Evolution of Echinoderm Mitochondrial ATP Synthase Subunit 8 (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 233-239 
    Details
    ISSN: 1573-6881
    Keywords: ATP synthase subunit 8 ; genes ; mammals ; mitochondria ; sea urchins ; sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Peculiar evolutionary properties of the subunit 8 of mitochondrial ATP synthase (ATPase8) are revealed by comparative analyses carried out between both closely and distantly related species of echinoderms. The analysis of nucleotide substitution in the three echinoids demonstrated a relaxation of amino acid functional constraints. The deduced protein sequences display a well conserved domain at the N-terminus, while the central part is very variable. At the C-terminus, the broad distribution of positively charged amino acids, which is typical of other organisms, is not conserved in the two different echinoderm classes of the sea urchins and of the sea stars. Instead, a motif of three amino acids, so far not described elsewhere, is conserved in sea urchins and is found to be very similar to the motif present in the sea stars. Our results indicate that the N-terminal region seems to follow the same evolutionary pattern in different organisms, while the maintenance of the C-terminal part in a phylum-specific manner may reflect the co-evolution of mitochondrial and nuclear genes.
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    URL: http://dx.doi.org/10.1023/A:1022406026196
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    Early Bioenergetic Changes in Hepatocarcinogenesis: Preneoplastic Phenotypes Mimic Responses to Insulin And Thyroid Hormone (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 303-313 
    Details
    ISSN: 1573-6881
    Keywords: Hepatic preneoplasia ; glycogenotic foci ; amphophilic foci ; mitochondria ; peroxisomes ; hepatocellular neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Biochemical and molecular biological approaches in situ have provided compelling evidence for early bioenergetic changes in hepatocarcinogenesis. Hepatocellular neoplasms regularly develop from preneoplastic foci of altered hepatocytes, irrespective of whether they are caused by chemicals, radiation, viruses, or transgenic oncogenes. Two striking early metabolic aberrations were discovered: (1) a focal excessive storage of glycogen (glycogenosis) leading via various intermediate stages to neoplasms, the malignant phenotype of which is poor in glycogen but rich in ribosomes (basophilic), and (2) an accumulation of mitochondria in so-called oncocytes and amphophilic cells, giving rise to well-differentiated neoplasms. The metabolic pattern of human and experimentally induced focal hepatic glycogenosis mimics the phenotype of hepatocytes exposed to insulin. The conversion of the highly differentiated glycogenotic hepatocytes to the poorly differentiated cancer cells is usually associated with a reduction in gluconeogenesis, an activation of the pentose phosphate pathway and glycolysis, and an ever increasing cell proliferation. The metabolic pattern of preneoplastic amphophilic cell populations has only been studied to a limited extent. The few available data suggest that thyromimetic effects of peroxisomal proliferators and hepadnaviral infection may be responsible for the emergence of the amphophilic cell lineage of hepatocarcinogenesis. The actions of both insulin and thyroid hormone are mediated by intracellular signal transduction. It is, thus, conceivable that the early changes in energy metabolism during hepatocarcinogenesis are the consequence of alterations in the complex network of signal transduction pathways, which may be caused by genetic as well as epigenetic primary lesions, and elicit adaptive metabolic changes eventually resulting in the malignant neoplastic phenotype.
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    URL: http://dx.doi.org/10.1023/A:1022438528634
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    Human Cytochrome c Oxidase: Structure, Function, and Deficiency (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 151-163 
    Details
    ISSN: 1573-6881
    Keywords: cytochrome c oxidase ; respiratory chain ; mitochondria ; assembly ; enzyme deficiency ; Leigh's syndrome ; mitochondrial myopathy (Saccharomyces cerevisiae, human)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract As the terminal component of the mitochondrial respiratory chain, cytochrome c oxidase plays a vital role in cellular energy transformation. Human cytochrome c oxidase is composed of 13 subunits. The three major subunits form the catalytic core and are encoded by mitochondrial DNA (mtDNA). The remaining subunits are nuclear-encoded. The primary sequence is known for all human subunits and the crystal structure of bovine heart cytochrome c oxidase has recently been reported. However, despite this wealth of structural information, the role of the nuclear-encoded subunits is still poorly understood. Yeast cytochrome c oxidase is a close model of its human counterpart and provides a means of studying the effects of mutations on the assembly, structure, stability and function of the enzyme complex. Defects in cytochrome c oxidase function are found in a clinically heterogeneous group of disorders. The molecular defects that underlie these diseases may arise from mutations of either the mitochondrial or the nuclear genomes or both. A significant number of cytochrome c oxidase deficiencies, often associated with other respiratory chain enzyme defects, are attributed to mutations of mtDNA. Mutations of mtDNA appear, nonetheless, uncommon in early childhood. Pedigree analysis and cell fusion experiments have demonstrated a nuclear involvement in some infantile cases but a specific nuclear genomic lesion has not yet been reported. Detailed analyses of the many steps involved in the biogenesis of cytochrome c oxidase, often pioneered in yeast, offer several starting points for further molecular characterizations of cytochrome c oxidase deficiencies observed in clinical practice.
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    URL: http://dx.doi.org/10.1023/A:1022638013825
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    Hexokinase Binding to Mitochondria: A Basis for Proliferative Energy Metabolism (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 331-338 
    Details
    ISSN: 1573-6881
    Keywords: Cancer ; proliferation ; Crabtree effect ; insulin action ; compartmentation ; aerobic glycolysis ; hexokinase ; mitochondria ; porin ; protein synthesis ; TCA cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Current thought is that proliferating cells undergo a shift from oxidative to glycolytic metabolism, where the energy requirements of the rapidly dividing cell are provided by ATP from glycolysis. Drawing on the hexokinase–mitochondrial acceptor theory of insulin action, this article presents evidence suggesting that the increased binding of hexokinase to porin on mitochondria of cancer cells not only accelerates glycolysis by providing hexokinase with better access to ATP, but also stimulates the TCA cycle by providing the mitochondrion with ADP that acts as an acceptor for phosphoryl groups. Furthermore, this acceleration of the TCA cycle stimulates protein synthesis via two mechanisms: first, by increasing ATP production, and second, by provision of certain amino acids required for protein synthesis, since the amino acids glutamate, alanine, and aspartate are either reduction products or partially oxidized products of the intermediates of glycolysis and the TCA cycle. The utilization of oxygen in the course of the TCA cycle turnover is relatively diminished even though TCA cycle intermediates are being consumed. With partial oxidation of TCA cycle intermediates into amino acids, there is necessarily a reduction in formation of CO2 from pyruvate, seen as a relative diminution in utilization of oxygen in relation to carbon utilization. This has been assumed to be an inhibition of oxygen uptake and therefore a diminution of TCA cycle activity. Therefore a switch from oxidative metabolism to glycolytic metabolism has been assumed (the Crabtree effect). By stimulating both ATP production and protein synthesis for the rapidly dividing cell, the binding of hexokinase to mitochondrial porin lies at the core of proliferative energy metabolism. This article further reviews literature on the binding of the isozymes of hexokinase to porin, and on the evolution of insulin, proposing that intracellular insulin-like proteins directly bind hexokinase to mitochondrial porin.
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    URL: http://dx.doi.org/10.1023/A:1022442629543
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    Effects of biomanipulation in the large and shallow Lake Wolderwijd, The Netherlands (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 335-349 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; lake restoration ; biomanipulation ; fish ; zooplankton ; phytoplankton ; macrophytes ; transparency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since the early seventies, Lake Wolderwijd (2650 ha, mean depth1.5 m) suffered from cyanobacterial blooms, turbid water and a poorsubmerged vegetation as a result of eutrophication. From 1981onwards the lake was flushed with water low in phosphorus and highin calcium bicarbonate. Total-P and chlorophyll a in the lakemore than halved, but Secchi depth in summer increased from 0.20 to0.30 m only. In the hope of triggering a shift from thealgae-dominated turbid water state to a macrophyte-dominated clearwater state, the lake was biomanipulated during winter 1990/1991.The fish stock, mainly bream (Abramis brama) and roach (Rutilus rutilus),was reduced from 205 to 45 kg ha−1. In May1991, 575 000 (217 ind ha−1) pike fingerlings (Esoxlucius) were introduced. In spring 1991 the lake cleared as aresult of grazing by Daphnia galeata. The clear water phaselasted for only six weeks. Macrophytes did not respond as expectedand most of the young pike died. However, from 1991 to 1993 thesubmerged vegetation is gradually changing. Characeae began tospread over the lake (from 28 ha in 1991 to 438 ha in 1993). Thewater over the Chara meadows was clear, probably as a resultof increased net sedimentation in these areas. It is hypothesizedthat expansion of the Chara meadows might ultimately resultin a shift of the whole lake to a lasting clear water state. Inorder to promote the Chara, the fish stock reductions aimedat a spring clear water phase should be continued.
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    URL: http://dx.doi.org/10.1023/A:1017088701621
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