The reduction of tetrazolium salts by plant mitochondria

Summary Data has been obtained concerning the reduction of tetrazolium salts by mitochondria isolated from Jerusalem artichoke tubers with succinate as the substrate using a direct recording spectrophotometric method of assay. ATP was found to increase the rate of reduction of the tetrazolium salts, this being independent of the effect ATP had on the rate of oxygen uptake. The magnitude of the stimulation by ATP depended on the concentration of tetrazolium salts present and under certain circumstances was suppressed by the addition of azide and cyanide. The sites at which the tetrazolium salts were reduced along the electron transport chain were investigated. The role of ATP has been discussed in relation to the mechanism of tetrazolium reduction.Abbreviations TTC 2,3,5-triphenyl-2,1,3,4-tetrazolium chloride - BT 5,5-diphenyl-3,3-(3,3-dimethoxy-4,4-diphenylene)-ditetrazolium chloride - NT 2,2,5,5-tetraphenyl-3,3-(p-diphenylene)-ditetrazolium chloride - MTT 3-(4,5-dimethyl thiozolyl-2)-2,5-diphenyl tetrazolium bromide - INT 2-(p-iodophenyl)-3-p-dinitrophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride - NBT 2,2-dinitrophenyl-5,5-diphenyl-3,3-dimethoxy-4,4-diphenylene)-ditetrazolium chloride - TNBT 2,2-5,5-tetra-p-nitrophenyl-3,3-dimethoxy-4,4-diphenylene) ditetrazolium chloride     

Preparation and heteronuclear 2D NMR spectroscopy of a DNA dodecamer containing a thymidine residue with a uniformly 13C-labeled deoxyribose ring

Summary [¹³C₅]-2-Deoxy-d-ribose, synthesized from [¹³C₆]-d-glucose (98% ¹³C), was coupled with thymine to give [1,2,3,4,5-¹³C₅]-thymidine (T) in an 18% overall yield. The thymidine was converted to the 3-phosphoramidite derivative and was then incorporated into a dodecamer 5-d(CGCGAATTCGCG)-3 by solid-phase DNA synthesis. Preparation of 0.24 mole of the labeled dodecamer, which is sufficient for a single NMR sample, consumed only 25 mg of glucose. By virtue of the ¹³C labels, all of the ¹H-¹H vicinal coupling constants in the sugar moieties were accurately determined by HCCH-E.COSY.     

Genetic polymorphisms of gene conversion within the duplicated human α-globin loci

Summary Of the 645 Japanese subjects studied, we have identified 10 individuals heterozygous for a chromosome with the triplicated -globin loci. The frequency of the triple -loci was 0.008 in this population, while that of the single -locus, i.e., -thalassemia 2 gene, might be lower than 0.0008. Analysis of haplotypes using particular RsaI site polymorphism in the -globin gene complex strongly suggests that the triple loci may have had multiple origins in this population.     

The acoustic near field of a dancing honeybee

Summary The acoustic near field close to honeybees performing the wagging dance was investigated with pairs of small, matched microphones placed in various positions around the dancing bees. The dance sounds are produced by the wings, which act as an asymmetrical dipole emitter. Close to the abdomen, the sound pressures in the air spaces above and below the plane of the wings are totally out of phase. A zone of very intense acoustical short-circuiting exists close to the edges of the wings, where pressure gradients of about 1 Pa/mm are observed in the dorso-ventral direction (perpendicular to the plane of the wings). The pressure gradients drive air movements with velocity amplitudes up to about 1 m/s. The pressure gradients are much smaller in directions radially away from the bee and decrease rapidly with increasing distance from the wings. The sound pressure detected by a stationary probe at one side of the bee is strongly modulated at 12–13 Hz as a result of the bee's side-to-side wagging. Surprisingly little sound is found near the dancer's head. The positions of the follower bees reflect the properties of the acoustic field: The follower bees place their antennae in the zone of maximum acoustical short-circuiting where the air particle movements are most intense. These observations suggest 1) how follower bees can avoid mixing up the messages carried by the dance sounds when two or more bees are dancing only a few cm apart and 2) how the followers might extract information about a dancer's spatial orientation from the acoustic near field she produces. The observations also provide clues regarding the nature of the putative sound receivers.Dedicated to Professor Dr. Drs. h.c. mult. H. Autrum on the occasion of his 80th birthday     

Variability of sunflower inbred lines to iron deficiency stress

Sunflower (Helianthus annuus L.) has been classified as a Fe-efficient species; however differences have been reported in susceptibility to Fe deficiency stress among cultivars and inbred lines. This paper reports research on responses of inbred lines to Fe deficiency stress (release of protons and root capacity to reduce Fe). When plants were grown individually in aerated nutrient solution without Fe the new selected inbred lines were classified as: a) Lines with good Fe deficiency stress response (RHA 271, RHA 273 and RHA 274); b) Lines that did not lower root external pH (HA 89 and RHA 299), one with very low reducing capacity (HA 89) and the other with reducing capacity (RHA 299); and c) One segregating line (RHA 276) from which two sister lines were selected. When a buffer (5 mM MES, 2-(N- morpholino) ethanesulfonic acid) was added to the root nutrient solution without Fe during growth, the reducing capacity of Fe-inefficient lines was higher for buffered than for unbuffered roots. Therefore, differences among lines for reducing capacity depend on experimental conditions.     

Sensory deficits induced by cadmium in banded kokopu, Galaxias fasciatus, juveniles

The potential for cadmium to produce sensory deficits in the mechanosensory lateral line and olfactory systems was examined in migratory Galaxias fasciatus juveniles or whitebait. Using a two-choice chamber apparatus, three groups of whitebait were tested for a known attraction to adult pheromones and then exposed to either 0.1, 0.5 or 1g Cd⁺² l^-1 for 48h and retested. The attraction to adult pheromones had been eliminated after exposure to concentrations of 0.5 and 1g Cd⁺² l^-1, indicating these levels of cadmium exposure had impaired olfactory function. Rheotaxis trials were conducted to determine the level of cadmium exposure which would inhibit lateral line function. The lateral line system was not blocked until a concentration of 2g Cd⁺² l^-1. The blocking of the lateral line and olfactory sensory systems was reversible. After 14 days recovery in clean freshwater both rheotaxis and the attraction to adult pheromones had returned. Whitebait were also tested for a preference/avoidance response at 2g Cd⁺² l^-1. Fish showed neither a preference for, or an avoidance of, a concentration which would disable both the lateral line and olfactory sensory systems. The disabling of these sensory systems may render migratory cues undetectable, affecting habitat selection by whitebait, which may ultimately affect the distribution of banded kokopu populations.     

Über die Herkunft „synaptischer“ Bläschen in neurosekretorischen Axonen

Zusammenfassung In der Neurohypophyse fetaler und neugeborener Ratten entsteht die Mehrzahl der synaptischen Bläschen aus Erweiterungen der Neurotubuli. Ferner können pinocytotische Bläschen als synaptische Vesikel imponieren. Die Bläschenbildung aus Membranen von Elementargranula (vgl. Herlant, 1967) tritt dagegen in den Hintergrund. Ein Auftreten von Vesikeln im Innern von Elementargranula wurde nicht beobachtet.

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The origin of synaptic vesicles in neurosecretory axons

Summary In the neurohypophysis of fetal and newborn rats the majority of synaptic vesicles originate from dilatations of neurotubuli. Moreover, pinocytotic invaginations give rise to synaptic vesicles. Evaginations of elementary granule membranes, as described by Herlant (1967), are seldom to be found and do not seem to play an important role in the formation of synaptic vesicles. The occurrence of vesicles within elementary granules was not observed.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Relationships of Agropyron intermedium chromosomes determined by chromosome pairing and alcohol dehydrogenase isozymes in common wheat background

Summary The relationships of Agropyron intermedium chromosomes in two wheat-Agropyron addition series were determined. Chromosome pairing behaviour revealed that the alien chromosome in lines TAF-2 and L7 of Vilmorin-A. intermedium set are homologous to the alien chromosomes in lines P and C of the Caribo-A. intermedium set respectively. Localization of alcohol dehydrogenase isozyme genes in Vilmorin-Agropyron addition line L4 and in Caribo-Agropyron line O indicated relationships with wheat chromosomes of homoeologous group 4.     

Genetic diversity in relation to heterosis and combining ability in spring wheat

Summary Genetic diversity among ten varieties of spring wheat used as parents in a diallel cross was assessed through multivariate analysis (D²-statistics) and then related to heterosis and SCA effects of their hybrids. The parents fell into three groups. Group I contained the varieties, Nobre, Girua and Carazinho; group II contained Sonalika, Lyallpur and Pitic 62 and group III contained Indus 66, Balaka, Sonora 64rs and MSl. The varieties of group I were good general combiners, while the varieties of group III were poor combiners. Significant heterotic and SCA effects for yield and yield components were observed in the hybrids of the parents belonging to different groups but not in the same group. Genetic divergence between the parents had a positive relationship with heterosis and SCA effects of the hybrids.     

Reversible and irreversible damage in reoxygenated ‘ischemic’ ventricular myocytes in culture

The LDH release pattern from cardiomyocytes under ischemia-like conditions shows two phases. In the initial slow phase, reoxygenation immediately stops further enzyme release. Accelerated LDH release, which occurs concomitantly with Iysosomal enzyme release, characterizes the second phase of ischemia. Reoxygenation at this stage does not put a stop to further enzyme release.Reoxygenation during the first phase of ischemia rapidly restored ATP level, while in the second phase, ATP levels remained low even after 6 h of reoxygenation.This study as well as previous data seem to suggest that irreversible cellular damage leading to cell death, occurs by synergistic action of many effectors, each of which does not necessarily cause irreversible damage.     

Bioassembly of acyl lipids in microspore-derived embryos of Brassica campestris L.

The native lipid composition and the capacity of cell-free extracts to biosynthesize acyl lipids in vitro were determined for the first time using the recently reported microspore-derived (MD) embryo system from the Brassica campestris low erucic acid line BC-2 (Baillie et al. 1992). The total lipid fraction isolated from midcotyledonary stage MD embryos (21 days in culture) was composed primarily of triacylglycerol (76%) with an acyl composition quite similar to that of mature BC-2 seed. When incubated in the presence of glycerol-3-phosphate, ¹⁴C 181-CoA, and reducing equivalents, homogenates prepared from 21-day cultured MD embryos were able to biosynthesize glycerolipids via the Kennedy pathway. The maximum in vitro rate of triacylglycerol biosynthesis could more than account for the known rate of lipid accumulation in vivo. The homogenate catalyzed the desaturation of 181 to 182 and to a lesser extent, 183. The newly-synthesized polyunsaturated fatty acids initially accumulated in the polar lipid fraction (primarily phosphatidic acid and phosphatidylcholine) but began to appear in the triacylglycerol fraction after longer incubation periods. As expected for a low erucic acid cultivar, homogenates of MD embryos from the BC-2 line were incapable of biosynthesizing very long chain monounsaturated fatty acyl moieties (201 and 221) from 181-CoA in vitro. Nonetheless, embryo extracts were still capable of incorporating these fatty acyl moieties into triacylglycerols when supplied with ¹⁴C 201-CoA or ¹⁴C 221-CoA. Collectively, the data suggest that developing BC-2 MD embryos constitute an excellent experimental system for studying pathways for glycerolipid bioassembly and the manipulation of this process in B. campestris.Abbreviations CPT sn-1,2-diacylglycerol cholinephosphotransferase - DAG diacylglycerol - DGAT diacylglycerol acyltransferase - DGDG digalactosyldiacylglycerol - G-3-P glycerol-3-phosphate - G-3-PAT glycerol-3-phosphate acyltransferase - LPA lyso-phosphatidic acid - LPAT lyso-phosphatidic acid acyltransferase - LPC lyso-phosphatidylcholine - LPCAT acyl-CoA: lyso-phosphatidylcholine acyltransferase - LPE lyso-phosphatidylethanolamine - MGDG monogalactosyldiacylglycerol - PA phosphatidic acid - PA Phosphatase, phosphatidic acid phosphatase - PC phosphatidylcholine - PE phosphatidylethanolamine - PG phosphatidylglycerol - TAG triacylglycerol - 181-CoA oleoyl-Coenzyme A - 181 oleic acid, cis-9-octadecenoic acid - 182 linoleic acid, cis-9,12-octadecadienoic acid - 183 -linolenic acid, cis-9,12,15-octadecatrienoic acid - 201 cis-11-eicosenoic acid - 221 erucic acid, cis-13-docosenoic acid; all other fatty acids are designated by number of carbon atoms: number of double bonds National Research Council of Canada Publication No. 35896     

‘Free’ iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat

Free iron concentration, as determined by electron paramagnetic resonance (EPR) spectroscopy, and lipid peroxidation (LPO), as determined by thiobarbituric acid test, were assessed in the lung, heart, liver, spleen, brain and kidney of rats subjected to experimental iron overload. Two tests, Desferal- and NO-available iron, were used to measure free iron and gave comparable results. The most pronounced accumulation of free iron was observed in liver, kidney and spleen. Differences between control and iron loaded animals increased during the initial 90 days of treatment. Between 90 and 180 days free iron concentration reached a steady state level, or even decreased, as in the case of liver. Lipid peroxidation level, measured in the organs of both treated and matched controls, did not give any significant difference during the initial 90 days of treatment. A significant augmentation was observed in liver, kidney, spleen and heart at 180 days. The results of the present research show that, under conditions of moderate siderosis, the occurrence of LPO is partially related to the level of free iron.     

Genotypic control of pollen plant formation in Nicotiana tabacum L.

Summary Tobacco plants (Nicotiana tabacum L.) of four varieties (Badischer Burley, White Burley, Techne, Kupchunos) were raised at different temperatures and daylengths and the effect of genotype on embryogenic pollen grain formation in situ and on pollen plant formation in anther and pollen cultures from these plants was studied. Genotype controlled embryogenic pollen grain and pollen plant formation by defining productivity under standard growth conditions (long days at 24 °C). Kupchunos was the most productive variety, followed by White Burley, Techne, and Badischer Burley. Furthermore, genotype defined which environmental factor was able to affect embryogenic pollen grain and pollen plant formation and also to which degree. In anther cultures, in addition to these effects, genotype controlled the formation of (an) inhibitory substance(s) in the anther wall in interaction with the plant growth conditions. In Badischer Burley and Techne, inhibitor action could be prevented by isolation of the pollen after one week of anther culture. Finally, direct pollen cultures in Badischer Burley and Techne produced embryos were only when the pollen was isolated from nearly mature anthers, while in White Burley and Kupchunos, embryos also produced at earlier stages and at higher yields. This indicated that genotype controls the time when the embryogenic pollen grains become ready to divide. The results are discussed in relation to strategies to overcome recalcitrance of species and genotypes.     

Human λ light chain locus: Organization and DNA sequences of three genomicJ regions

Evidence for the genomic organization of human lambda light chain joining (J) region gene segments is presented. A mouse J probe was used in Southern hybridizations to localize joining region sequences in a cosmid clone containing the genomic cluster of six human lambda constant (C) region gene segments. The results of these hybridizations suggest the presence of at least one J gene segment upstream from each constant region gene segment. The DNA sequences indicate that the human JI, J2, and J3 gene segments have consensus nonamer and heptamer sequences, proposed to be involved in V-J joining, are capable of encoding the known amino acid sequences for the respective J peptides, and have a sequence which could give functional RNA splice site at the end of their coding regions. Our data show that a single functional J is located 1.3 or 1.6 kb upstream of each of the C gene segments known to encode the Mcg, Kern^– Oz^–, and Kern^–Oz⁺ isotypes. Therefore, the gene organization of this region of the human lambda locus is J1 CI -J2C2-J3C3. The DNA sequences ofJ 1,J 2, andJ 3 presented in this paper establish that a singleJ gene segment precedes each expressed C gene segment, and support a model for the evolution of the human JC clusters where JICI andJ2C2-J3C3. arose from different ancestral JC units.     

Wheat chromosome 2D carries genes controlling the activity of two DNA-degrading enzymes

DNA-degrading enzymes of 24.0 kDa and 27.0 kDa were observed to have different activities in two common wheat (Triticum aestivum L.) cultivars, Wichita and Cheyenne. A substrate-based SDS-PAGE assay revealed that these two enzymes were much more active in Wichita than in Cheyenne. Genes controlling the activities of these two enzymes were localized on chromosome 2D by testing DNA-degrading activities in reciprocal chromosome substitution lines between Wichita and Cheyenne. While the allele on Wichita chromosome 2D stimulated the activities of the 24.0- and 27.0-kDa enzymes in Cheyenne, the allele on Cheyenne chromosome 2D did not reduce the activities of the 24-kDa and 27-kDa enzymes in Wichita. Whether these genes code for the DNA-degrading enzymes themselves or for factors that regulate the enzyme activities remains unknown.This work was supported in part by USDA-Competitive Research Grants Office grant No. 90-37140-5426 to P.S.B. Contribution from Agricultural Research Division, University of Nebraska. Journal Series Number 10304     

The role of knowledge and spatial contexts in biodiversity policies: a sociological perspective

In policy processes, biodiversity has been broadened into a holistic notion uniting a variety of cultural, social and economic issues with the biological conservation issue. Therefore, the formation of biodiversity conservation into concrete policy goals appears rather difficult. In this paper, we aim to explore the political implications and consequences of the strong dependency on science of the biodiversity issue. Concentrating especially on environmental policy options, we also examine the globalization and localization processes in the case of biodiversity. In spite of several controversial features and of an evident lack of knowledge on biological diversity, the issue undoubtedly has significant political strengths. However, from the viewpoint of research on environmental policies, the role of scientific knowledge in decision making should be recognized as an open empirical question depending on the concrete contexts of the decision-making process. Further, it is concluded that the concepts relating to global environment are objects of a continuous localization. Thus, any moral-technocratic solutions emphasizing simply universal interests as the basis for global biodiversity management must be met with caution. In future research there is a need for concrete case studies in order to clarify the local conditions and opportunities of biodiversity policies.     

α-Thalassemia and the production of different α chain variants in heterozygotes

The production of five chain variants (Hb G-Georgia, Hb St. Luke's, Hb Lloyd, Hb Montgomery, and Hb G-Philadelphia) in heterozygotes was evaluated through hematological observations, hemoglobin quantification, and biosynthetic studies. All heterozygotes for Hb St. Luke's and Hb Lloyd and most heterozygotes with Hb G-Georgia and Hb Montgomery had normal hematology and average / values of about 1.1. They were assigned a normal genotype (^G/), although the proportions of Hb St. Luke's and Hb G-Georgia were low (10 to 13%) and those of Hb Lloyd and Hb Montgomery twice as high (20%). Data from short-term incubations confirmed this genotype for some of these heterozygotes. Isolated Hb St. Luke's and Hb G-Georgia gave low ^G/ values (0.2 and 0.3) indicating that these Hb variants were defective at the level of Hb assembly. Isolated Hb Montgomery and Hb G-Philadelphia, however, gave higher ^G/ values of 0.6 and 0.8, respectively. A second type of variability existed among Hb G-Georgia (20 vs. 13%), Hb Montgomery (28 vs. 20%), and Hb G-Philadelphia (47 vs. 34%) heterozygotes, in whom the levels of Hb G differed. The occurrence of higher levels of these three chain heterozygosities was associated with hematological or biosynthetic evidence of a mild or moderate chain deficiency due to an -thalassemia-2 heterozygosity (^G/⁰ or ^0G/) or a homozygosity (^0G/⁰), respectively.This study was supported in part by USPHS Research Grants HLB-05168 and HLB-15158.     

Isoform-Specific Membrane Translocation of Protein Kinase C After Ischemic Preconditioning

Mild cerebral anoxic/ischemic/stress insults promote tolerance and thereby protect the brain from subsequent lethal anoxic/ischemic insults. We examined whether specific activation of PKC , , , or isoforms is associated with ischemic preconditioning (IPC) in rat brain. IPC was produced by a 2-minute global cerebral ischemia. Membrane and cytosolic fractions of the hippocampi were immunoblotted using specific antibodies for PKC, , , and . PKC showed a significant translocation to the membrane fraction from 30 min to 4 h and PKC at 4 h following IPC. In contrast, the membrane/cytosol ratio of PKC showed a tendency to decrease at 30 min and 8 h, and the membrane/cytosol ratio of PKC was significantly decreased from 30 min to 24 h following IPC. These findings indicate PKC isoform-specific membrane translocations in the hippocampus after brief global brain ischemia and suggest that activation of PKC and PKC may be associated with IPC-induced tolerance in the rat hippocampus.     

Nervous control of the branchial vascular resistance of the Atlantic cod,Gadus morhua

Summary The effects on branchial vascular resistance of electrical stimulation of the nervous supply to the gills of the Atlantic cod were studied in constant pressure perfused gill preparations.Stimulation of the right sympathetic chain immediately anterior to the coeliac ganglion produces either a -adrenoceptor mediated decrease in branchial vascular resistance of the gill arches on the right side, or an -adrenoceptor mediated increase which is reversed by phentolamine to a -adrenoceptor mediated decrease in branchial vascular resistance.Stimulation of the entire vago-sympathetic nerve trunk to the third isolated gill arch produces an increase in branchial vascular resistance, which in some preparations can be reversed by atropine to a -adrenoceptor mediated decrease. A second type of constrictory innervation of vagal origin (non-adrenergic, non-cholinergic) may be concluded from the lack of blocking capacity of cholinergic and adrenergic antagonists.It is concluded that the branchial vascular bed of the cod is controlled by both sympathetic (dilatory and sometimes also constrictory) and parasympathetic (constrictory) fibres. The site of action of the nerve supply on the various effectors of the complex vasculature of the gills is not known. An autonomic innervation with its direct, rapid and restricted effects may reinforce the more general effects of circulating vaso-active substances.     

Phlorizin binding to isolated enterocytes: Membrane potential and sodium dependence

Summary Phlorizin binding is studied in isolated intestinal epithelial cells of the chick. Cells are ATP depleted to allow extensive manipulation of ionic gradients and membrane potential (). Phlorizin binding is assayed at steady state. Carrier specific phlorizin binding is defined asd-glucose (90 mM) inhibitable binding. Specific binding displays simple Michaelian kinetics as a function of phlorizin. indicating the presence of a single homogeneous binding site. Sodium concentrations and modify the apparent binding affinity but not the maximum number of binding sites. In contrast, the activation curve as a function of sodium concentrations is sigmoid and the apparent maximum number of binding sites at saturating sodium is phlorizin dependent. The rate of phlorizin association is both and sodium-concentration dependent. Dissociation is sodium-concentration dependent but not dependent. Theoretical analysis indicates binding order of substrates is random. In addition, data suggests that the phlorizin/sodium stoichiometry is 2:1. The dependence can be explained by two models: either translocation is the -dependent step and the free carrier is anionic, or sodium binding is the -dependent step.