Ultrastructural autoradiographic study of the intracellular fixation of3H-acrolein

Summary The fixation of³H acrolein inDunaliella bioculata was followed by means of quantitative autoradiography electron microscopy. A fixation was observed mostly in the nucleus where aldehyde linkage remained stable at least for 48 hours.     

Avantages et inconvénients de la fixation par perfusion du tissu nerveux à la lumière d'une donnée de cytochimie

Summary It has been extensively demonstrated that perfusion is the best fixation procedure for providing good morphological evidence ofstructures, especially in the case of nervous tissue. But it might be questioned if it should also be preferred whencytochemical data have to be obtained or compared.As a preliminary attempt to answer this question, lipoproteic inclusions in nerve cells of vegetative ganglia of adult cat have been considered. These occur in about 25% of cells after immersion in fixative, whereas if perfusion is used, a relation appears between the amount of saline perfused before the fixative fluid and the percentage of cells containing inclusions: this falls to 10% after 300 ml saline, to 1% after 800 ml. In conclusion, though structural artefacts have been avoided and fixation appears excellent, perfusion is significantly responsible for a definite cytochemical alteration.     

Does ammonium uptake influence xylem sap composition inPhaseolus vulgaris L. andGlycine max (L.) Merill?

The question of whether ammonium uptake influences the occurrence of ureides in legumes has been addressed in this study by investigating threeP. vulgaris genotypes as well as one cultivar ofGlycine max. All plants were raised in sand culture during the dry season in northern Thailand and irrigated daily with nitrogen-free nutrient solution, or the same solution containing 12 mol m^–3 nitrogen in the form of (NH₄)₂SO₄ or KNO₃, each treatment consisting of different proportions of either compound. Regression analyses of xylem sap composition relative to ammonium vs. nitrate supply of plants harvested at V4, R1 and R6 indicated close positive correlations of xylem amino nitrogen content and negative correlations with xylem nitrate content and ammonium supply. Statistically significant correlations between relative xylem ureide content and ammonium availability could be established for theP. vulgaris cultivar Brilliant up to stage R1, but not for the other plants investigated. It was concluded that at least for some genotypes of common bean a relationship exists between ureide production and ammonium uptake by the root system. Since the extent to which ureide production is stimulated remains quite small, its relevance to the xylem solute technique for measurement of N₂ fixation may be limited. Nevertheless, due to the possibility of large genotypic differences in the impact of ammonium on ureide production, this factor must be considered in calculations if N₂ fixation is to be determined in soils containing significant amounts of ammonium, e.g. in paddy fields.     

Einfluss einiger lipophiler Lösungsmittel in gasförmigem Zustand auf die CO2-fixierung durch Luzerne

Summary Vapourized organic solvents such as: diethyl ether, methylene chloride, carbon disulfide, benzene, and n-octane have an inhibiting effect on CO₂ fixation in alfalfa leaves (Medicago sativa). One exception is CS₂ which stimulates overall fixation up to 10 vol%. Beyond 10 vol% it inhibits overall CO₂ fixation like the other solvents, but stimulates the formation ofl-alanine as the major remaining fixation product. Proportionality exists between water insolubility of the organic solvents and their inhibiting effect on CO₂ fixation.     

Action of alkylating agents on nitrogen fixation by clones of Anabaena doliolum Bharadwaja

Summary The physiological and mutagenic actions of three alkylating agents have been studied on the process of nitrogen fixation byAnabaena doliolum Bharadwaja. The results show that these chemicals presumably switch off the activity of nitrogenase, resulting in the inhibition of fixation.     

Influence of phosphorus supply and light intensity on mycorrhizal response inPisum-Rhizobium-Glomus symbiosis

The influence of mycorrhizal colonization withGlomus mosseae on parameters of N₂ fixation and plant growth was studied in pot experiments with pea plants (Pisum sativum L.) infected withRhizobium leguminosarum and supplied with varied levels of phosphorus (P) and nitrogen (N). Reduced light intensities were used to evaluate the dependence of the microsymbionts on assimilate supply. In plants grown with low P supply, mycorrhization increased the concentration of P in shoots, and thus N₂ fixation. Reduced light intensity significantly depressed mycorrhizal colonization and nodule growth in low-P plants. When P supply did not limit plant growth and N₂ fixation, however, the percentage of mycorrhizal colonization was reduced due to the higher P status, and the microsymbionts were not impaired by low light intensities. To maximize carbohydrate supply, another experiment was carried out at high light intensity of 900 mol m^–2s^–1 and with non-limiting P supply. Nitrogen fertilization, given as starter N, enhanced plant growth, but delayed nodule formation. Towards flowering, nodulation rapidly increased, but less so inGlomus inoculated plants. After 28 days mycorrhizal plants were lower in shoot dry weight, nodule dry weight and nitrogenase activity. The results suggest that under many, but not all, environmental conditions the host plant is able to restrict mycorrhizal colonization and, thus, to prevent impairment ofRhizobium symbiosis.deceased in May 1994     

Temporal storage of kynurenine and 3-OH-kynurenine in the fat body of metamorphosingEphestia kühniella

Summary During the pharate pupal stage a massive accumulation of kynurenine and 3-OH-kynurenine is observed in the fat body ofEphestia kühniella. By injection it can be demonstrated that this organ is capable of sequestering at least 3-OH-kynurenine, the dominating tryptophan metabolite inEphestia. It is suggested that the fat body reduces a possibly harmfull excess of tryptophan metabolites at the beginning of metamorphosis. These sequestered metabolites provide a precursor depot for ommochrome synthesis in later development.     

High genetic variability despite haplodiploidy in primitive sawflies of the genusCephalcia (Hymenoptera,Pamphiliidae)

Hymenoptera are haplodiploid and usually display very low genetic variation. Most data concern social or parasiticApocrita, while the little information available for the primitive phytophagous species of the suborder Symphyta is contradictory. The present study is related to seven species of the genusCephalcia, living in coniferous forests of Northern Eurasia and sharing spruce (Picea sp. pl.) as host plant. Individuals from 22 populations belonging toCephalcia abietis, C. alashanica, C. arvensis, C. erythrogaster, C. fallenii, C. fulva, C. klugii from Europe and China were surveyed for genetic variation at 28 loci using enzyme electrophoresis. Pairs of sibling species were recognized withinC. arvensis andC. fallenii, corresponding to different phenological and morphological forms. In the latter case, reproductive isolation in sympatry occurs despite low genetic distance (D=0.059). Large genetic distances and fixed alternate alleles were observed between Chinese and European populations ofC. abietis andC. arvensis. Expected heterozygosity ofCephalcia populations (0.197, SD 0.064) is significantly higher than that of other Symphyta (Tenthredinoidea) (averageH _exp 0.059, SD 0.032) (two-tailed Mann-Whitney test, Z=4.39, p<0.01). These data suggest that haplodiploidy per se does not reduce the genetic variation in mostCephalcia populations. Most of the factors that can lower the potential for genetic diversity in a haplodiploid genetic system are not so effective inCephalcia populations, which seem to be comparable to diplodiploid insect populations in diversity. In a few isolated populations the large number of fixed loci and the large genetic distances may support the predicted faster rate of fixation, as a consequence of haplodiploidy.     

De l'emploi d'isotopes radioactifs artificiels,dans le but d'exercer un effet radio-biologique localisé

Summary One of the authors has previously reported on a method which consists in the utilization of an artifical radioactive isotope (Zn⁶³), suspended in a suitably prepared solution ofpectin, for the production oflocalized biological radiation effects.This « macromolecular occlusion » of the radioactive isotope enables one to perform intraperitoneal injections (in cases of cancer of the ovaries with severe metastatic peritoneal extension), evidently also instillations in cavernous organs, and furthermore direct intratumoral injections, without diffusion of the radioactivity outside the treated areas, as shown both by autoradiographs and controls of blood and urine specimens with a Geiger counter.The authors investigated further whether this procedure would also be suitable for obtaining, by means ofintravenous injections, alocalized radiation effect within thelungs, as presumably the radiozinc, held in the large molecules of pectin, could thus be retained in the pulmonary capillaries. Intravenous injections of such a pectin solution containing radiozinc were performed on rabbits, and autoradiographic controls gave evidence of this expected fixation within the lungs.For the purpose of preliminary clinical investigation 40 millicuries of Zn⁶³ suspended in 6 cm³ of a 3 p. c. isotonic pectin solution were injectedintravenously in a female patient with mainly pulmonary metastases of a previously operated hypernephroma. This patient had been also submitted to X-ray therapy. In spite of a poor general condition, the injection was well tolerated. Autoradiographic controls showed quite clearly that the radioactivity remains precisely localized within the pulmonary areas. No radioactivity whatsoever was demonstrated with the counter in the urine eliminated by this patient after the injection, a fact which points to a rather amazing accuracy of the fixation of the radiozinc in the lungs. This first clinical experience seems quite interesting in view of improving the therapeutic possibilities of pathological, especially neoplastic pulmonary conditions.     

Delayed metamorphosis and diapause in the sugar cane borerDiatraea saccharalis

Summary The problem of arrested or delayed development was examined in the sugar cane borer,Diatraea saccharalis. It was found that the insect can either enter diapause or exhibit a period of delayed metamorphosis according to the photoperiod conditions prevailing. We have observed the development characteristics ofD. saccharalis and conclude that a distinction should be made between a delayed metamorphosis phase and a diapause stage.This work was supported by a grant from NSERC.     

Chromosomal organization at the level of gene complexes

Metazoan genomes primarily consist of non-coding DNA in comparison to coding regions. Non-coding fraction of the genome contains cis-regulatory elements, which ensure that the genetic code is read properly at the right time and space during development. Regulatory elements and their target genes define functional landscapes within the genome, and some developmentally important genes evolve by keeping the genes involved in specification of common organs/tissues in clusters and are termed gene complex. The clustering of genes involved in a common function may help in robust spatio-temporal gene expression. Gene complexes are often found to be evolutionarily conserved, and the classic example is the hox complex. The evolutionary constraints seen among gene complexes provide an ideal model system to understand cis and trans-regulation of gene function. This review will discuss the various characteristics of gene regulatory modules found within gene complexes and how they can be characterized.     

Induction of uncoiled chromosomes by vibration.

Chromatin condensation during metaphase can be removed by simple vibration of metaphase cells prior to fixation. Uncoiled chromosome arms consist of long threads with dense regions at irregular distances each from the other.     

Colorants acides et détermination embryonnaire chez les Echinodermes

Summary The effects of three dyes with carboxyl groups are been studied on the developing eggs of the sea urchin,Paracentrotus lividus. Uranin and rose Bengal are both some derivative of the xanthene. Chrome violet CG is a carboxyl derivative of pararosolic acid. In dilute solutions these three dyes induce the development of radial larvae. At higher concentration, uranin and rose Bengal are very effective animalizing agents. Rose Bengal is more active than uranin. Rose Bengal differs from uranin by the fixation of halogens on the molecule of dye which increase the acidity of the carboxyl group. It appears that animalizing activity runs parallel with acidity. The results of these experiments are discussed in relation to the animalizing effects of various acid sulfonated dyes. The possible significance of the combinations between acid dyes and basic components of the cells in the animalization is considered.     

Education and Training in the Mining Industry, 1750-1860: European Models and the Italian Case

Mining education was one of the areas of technical savoir transformed during the eighteenth century. Mining academies arose and spread through Europe in the second half of that century. This happened first in the German states and the Austrian dominions, due to the cameralistic system, and soon developed elsewhere through a transfer of the German model to France (Ecole des mines) as well as to other francophone and Spanish-speaking areas (Belgium and Piedmont-Savoy, Spain and America). The mining academies may rightly be considered among the prototypes of technical high schools (Polytechniques and Technische Hochschulen) established during the nineteenth century. In the course of exploring some of the details of this development, the present paper aims at suggesting outlines to be followed in pursuing a comparative analysis of special schools for the training of technicians and mining officers (Bergschulen and Bergakademien). A second aim is to examine more closely the Italian case as a typical example of adaptation, although on a smaller scale, of French and German experiences. This can provide a framework within which to place further microanalyses and case-studies.     

What leads from <Emphasis Type="Italic">dead-end?</Emphasis>

The 129 mouse strain develops congenital testicular germ cell tumors (TGCTs) at a low frequency. TGCTs in mice resemble the testicular tumors (teratomas) that occur in human infants. The genes that cause these tumors in 129 have not been identified. The defect at the Ter locus increases TGCT incidence such that 94% of 129-Ter/Ter males develop TGCTs. The primary effect of the Ter mutation is progressive loss of primordial germ cells (PGCs) during embryonic development. This results in sterility in adult Ter/Ter mice on all mouse strain backgrounds. However, on the 129 background, Ter causes tumor development in addition to sterility. Therefore, Ter acts as a modifier of 129-derived TGCT susceptibility genes. Ter was identified to be a mutation that inactivates the Dead-end1 (Dnd1) gene. In this perspective, I discuss the possible areas of future investigations to elucidate the mechanism of TGCT development due to Dnd1 inactivation. Received 29 September 2006; received after revision 29 January 2007; accepted 19 February 2007     

Sequential analysis of Giemsa banded chromosomes inVicia faba

Summary Vicia faba (broad bean) root-tip chromosomes were subjected to the SSC-Giemsa and trypsin-Giemsa regimes. Phase-lucent cross-bands seen after fixation/SSC treatment subsequently stain positively with Giemsa. Sequential analysis of the trypsin-Giemsa regime shows, in contrast, that bands are manifest through selective removal of material from interband regions.     

The genetics of phytotoxin production by plant pathogenic fungi

Little is known about the genetic control of phytotoxin production by plant pathogenic fungi. The production of host-selective toxins known to play a role in disease development has been genetically analyzed in three species ofCochliobolus. InC. heterostrophus, a single genetic locus with two alleles has been identified controlling the production of HMT-toxin. This locus appears to be at or near the breakpoint of a chromosome rearrangement. Single genetic loci have also been identified controlling the production of HC-toxin byC. carbonum and HV-toxin byC. victoriae. The locus inC. carbonum may be a cluster of tightly linked genes.     

The C4-dicarboxylate transport system ofRhizobium meliloti and its role in nitrogen fixation during symbiosis with alfalfa (Medicago sativa)

TheRhizobium meliloti C₄-dicarboxylate transport (Dct) system is essential for an effective symbiosis with alfalfa plants. C₄-dicarboxylates are the major carbon source taken up by bacteroids. Genetic analysis of Dct^– mutant strains led to the isolation of thedct carrier genedctA and the regulatory genesdctB anddctD. The carrier genedctA is regulated in free-living cells by the alternative sigma factor RpoN and the two-component regulatory system DctB/D. In addition, DctA is involved in its own regulation, possibly by interacting with DctB. In bacteroids, besides the DctB/DctD system an additional symbiotic activator is thought to be involved indctA expression. Further regulation ofdctA in the free-living state is reflected by diauxic growth of rhizobia, with succinate being the preferred carbon source. The tight coupling of C₄-dicarboxylate transport and nitrogen fixation is revealed by a reduced level of C₄-dicarboxylate transport in nitrogenase negative bacteroids.     

Ursachen der geschlechtsunterschiedlichen MilchdrÜsengewebsentwickiung bei Ratten

Summary Under the same hormonal conditions, mammary gland growth in adult female rats is more pronounced than in males. Since there are no differences in the glandular development of both sexes, either at birth or at 30 days of life, it is assumed that male rats react less sensitively than female rats in response to a hormonal stimulus with regard to mammary gland growth. It is presumed that androgen influence during the differentiation stage is responsible for the fixation of a decreased sensitivity of the positive feedback-mechanism between estrogens and prolactin secretion in males. Thus changes in sensitivity would be the reason for mammary gland growth in males being smaller than in females under the same hormonal conditions.

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Dieser Arbeit liegen zum Teil die Untersuchungsergebnisse einer SchÜler-Facharbeit von U.Rieser zugrunde.