Book reviews

Ohne Zusammenfassung

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Book reviews

     

The morphology of the eyes of Limulus

Summary The dioptric apparatus of the Limulus compound eye is composed of the corneal cuticle with its internally projecting cuticular cones and the specialized underlying epidermis. The latter is composed of three distinct cell types. The guanophores, located between cuticular cones, contain guanine as a reflecting pigment. The distal pigment cells, which clothe the sides of the cuticular cones and form a sheath around the underlying ommatidium, contain massive bundles of microtubules, abundant pigment droplets and a large Golgi system. The cone cells are positioned between the flattened tip of the cuticular cone and the apex of the ommatidium. They serve to anchor the retinula cells to the cuticle and, by virtue of long processes along the periphery of the rhabdome, perform a glial function with respect to the interaction of adjacent retinula cells. The geometry and fine structure of the dioptric apparatus provide supporting evidence for the wide angle of acceptance and lack of polarized light perception by the ommatidia.This study constitutes publication No. 288 from the Oregon Regional Primate Research Center, supported in part by Grants FR 00163 and NB 07717-01 from the National Institutes of Health and in part by a Bob Hope Fight For Sight Grant-in-Aid of the National Council to Combat Blindness, Inc. The author wishes to thank Mrs. Audrey Griffin for patient and excellent technical assistance.     

Zur Genetik und Klinik kleiner Chromosomenaberrationen

Summary A family is described wherein a G-chromosome carrying a structural anomaly within the short arm region, is transferred from each of both parents. In the mother, this chromosome has a secondary constriction on the enlarged short arm and in addition normal satellites (Gp+h); this maker chromosome is also found in the maternal grandfather. In the father, the aberrant G-chromosome presents giant satellites (Gs+). At least one of both marker chromosomes is transferred to all four children. Three of these are healthy, the fourth is retarded mentally and statically, and has a number of congenital anomalies. It is discussed whether these small chromosome aberrations range under normal variability or may be responsible for the developmental disorders exhibited in the proband.

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Wesentliche Teile der vorliegenden Arbeit wurden von H. Lohmann als Dissertation der Medizinischen Fakultät der Universität Freiburg i. Br. vorgelegt.     

Über den lichtgeförderten Influx von Ionen in Blättern von Elodea densa. Vergleich der Influxe von K+- und Cl--Ionen

Summary The light-dependent influxes of K⁺ and Cl^- in detached leaves of Elodea densa were measured using ³⁶Cl^- and ⁴²K⁺ or ⁸⁶Rb⁺ as tracers.The K⁺ and Cl^- influxes were enhanced by light and also in the dark after a preillumination. The rate of influx decayed in the dark according to a first order reaction with a half-time of 25 or 27 sec.DCMU inhibits the light-dependent K⁺ influx more severely in the presence of CO₂ than in its absence in an atmosphere of N₂ containing a trace of oxygen. This is similar to the effect of DCMU on the Cl^- influx. CCCP¹, atebrin (quinacrine) and Dio-9 all affect the influx of K⁺ and Cl^- in a comparable way. CCCP exerts the strongest effect at low light intensities; atebrin and Dio-9 inhibit strongly even at high intensities when the ion influxes are light-saturated. The influence of these two inhibitors in attributed to an effect at the cellular membranes in addition to an effect on photophosphorylation. The effect of CCCP is ascribed to uncoupling of photophosphorylation, as photosynthesis is inhibited by about the same concentration as is ion influx.In far-red light the relative quantum yields of K⁺ and Cl^- influx drop to a similar degree as does the quantum yield of photosynthesis. Estimated values of the quantum requirement of ion influx are given. The quantum requirement in air is higher than in an atmosphere of N₂. It is a function of ion concentration and is lower at higher external concentrations.The results indicate that the K⁺ and Cl^- influxes are partially coupled. The linkage of the ion influxes with the energy sources in the light and a possible contribution of a pseudocyclic photophosphorylation are discussed.     

The preparation of vesicles bounded by single phospholipid bilayers and loaded with acetylcholine

Summary Vesicles bounded by single lipid bilayer membranes (outside diameter 350 to 400 Å) can be made to enclose aqueous solutions of a variety of compounds. The procedure to prepare such vesicles in suspension is demonstrated with solutions of acetylcholine (ACh) in different concentrations as inside media. Several points are submitted as proof that the vesicles can contain a particular compound not present in the outside aqueous solution.The results of this work were presented in part at the First European Biophysics Congress, Baden near Vienna, Austria, September 14–17, 1971. Supported by a grant from the Medical Research Council of Canada.Scholar of the Medical Research Council of Canada.     

Respiration deficient mutants of Schizosaccharomyces Pombe I

Summary By use of N-methyl-N-nitro-N-nitrosoguanidin (NG) respiration deficient (RD) mutants were induced. They could be selected by replica-plating on glycerol medium. RD mutants were also induced by UV irradiation, enriched by use of 2,3,5-triphenyltetrazolium chloride (TTC) and tested for their inability to grow on glycerol medium. The RD mutants were characterized enzymatically for their decrease or loss in cytochrome c oxidase activity and in succinate- cytochrome c reductase activity. These assays allowed the localization of the mutational blocks in complexes II, III and IV of the respiratory chain. Tetrad analysis and random spore analysis demonstrated that all mutants contained chromosomal defects.     

Untersuchungen über die Aktivität der Galaktokinase im Blut von Normalpersonen und von Patienten mit GDo-Trisomie

Zusammenfassung Die Messung der Aktivitäten der Galaktokinase und der Galaktose-1-phosphat-uridyltransferase an Blutzellen bei 38 Mongoloiden und 51 Normalpersonen ergab, daß bei Mongoloiden die Aktivitäten beider Enzyme erhöht sind.Bei bis zu 15 Jahre alten Probanden beider Stichproben nehmen beide Enzymaktivitäten mit zunehmendem Alter ab. Der Vergleich zweier Stichproben gleichen Durchschnittsalters ergibt bei Mongoloiden eine Erhöhung der Kinase um 39%, der Transferase um 41%. Hypothesen zur Deutung dieser Befunde werden diskutiert.

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The activities of galactokinase and of galactose-1-phosphate-uridyltransferase have been measured in blood cells of 38 patients with G_Do-trisomy and of 51 normal persons. The mongoloids show higher activities of both enzymes than the controls. In the children up to 15 years, mongoloids as well as normals, an age dependency has been found: the enzyme activities decrease with increasing age.Mongoloid children show an increase of the kinase activity of 39% and of the transferase activity of 41% compared with normal controls of the same age groups. Some hypothetical interpretations of these results are discussed.

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Direktor: Prof. Dr. med. Dr. H. Baitsch

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Mit 3 Textabbildungen     

DNS-Reduplikationsmuster bei den Riesen-Geschlechtschromosomen von Microtus agrestis

Summary The X-chromosome of Microtus agrestis (2 n=50), comprising about 20 per cent of the homogametic haploid (AX) set, is the largest X-chromosome reported so far in placental mammals. It is four times the size of the X possessed by a great majority of mammals, including the human and the mouse. The Y-chromosome is also enormous, almost three-fifths the size of the X.The present cytological study concerned somatic interphase and prophase nuclei as well as the DNA replication pattern revealed by labeling cultured bone marrow cells with tritiated thymidine.In the male nuclus, the entire Y as well as the long arm and proximal part of the short arm of the X are late labeling and positively heteropycnotic. In the female, one entire X is late labeling and condensed, while the other X shows the same labeling pattern as the male X. Thus the pattern of inactivation of this huge X is such that in each diploid nucleus of both sexes, the amount of euchromatic X-chromosome material is the same as it is in the majority of placental mammals in which the X comprises about five per cent of the haploid set.

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Wesentliche Teile der vorliegenden Arbeit werden von Gertraud Flinspach als Dissertation der Medizinischen Fakultät der Universität Freiburg i.Br. vorgelegt.