ALBERT

Notes: Summary The extensive genetical analysis of the T-locus in mice, carried out by Dunn and his co-workers, has revealed that the breeding pattern of t-alleles is very peculiar. The complexity of the T-locus indicates that some structural rearrangements are involved here. The purpose of the present work was to gain some informations on the structure of chromosomes in which t-alleles are present. 2. The course of spermatogenesis in the lines of mice of the following genotypes was investigated: +/+; T/+; T/t n — namely T/t 0, T/t12, T/tw1, T/tw6, T/tw18; tn/tx — namely t 0/t12, t0/tw18, t12/tw18, tw1/t12, tw1/t0, tw1/tw6, tw1/tw18, and in heterozygotes for translocations T138 and T190, both involving the fragment of linkage group IX in which some t-alleles are present and used as markers. 3. The alleles T and t w1 are not connected with structural rearrangements, as far as detectable by the methods used. The alleles t 0, tw6 and t w18 are interstitial deficiencies involving different chromosomal regions. The most complete data were obtained for t 0: in T/t 0 heterozygotes a loop corresponding to a big interstitial deficiency was present, in all t 0/tn compounds the aberrant structure of one of the bivalents indicated that an interstitial deficiency is here involved. By analysis of translocation T190 the deficiency loop is localized in the chromosome representing linkage group IX. The identification of t w6 as a small interstitial deficiency is based on the analysis of T/t w6 heterozygotes and its localization in linkage group IX on the presence of this deficiency in translocation T138. The description of tw18 as a small interstitial deficiency stems from the analysis of T/tw18 and t 0/tw18, the localization in linkage group IX is shown by its presence in t 0/tw18 in the same bivalent as t 0. The evidence obtained for t 12 indicates that it is either a big terminal deficiency or a small interstitial one inducing constant asynapsis in adjacent terminal segments of the bivalent. 4. The reasons why loops encountered in genotypes involving t 0, tw6 and t w18 are considered as deficiencies and not as duplications are based on available embryological and genetical data. The possible connections between the mode of action of the investigated t-alleles as embryonic lethals and the cytological results on their structure and localization are discussed. 5. Most of the lethal t-alleles suppress crossing-over in the region T-tf. Factors reducing the frequency of recombination in other organisms are discussed in comparison. It is concluded that the pattern of aberation in meiotic behavior of the bivalent carrying t-alleles is for almost each of the studied alleles rather specific and does not permit for suggesting any general mechanism which could account for the action of investigated lethal t-alleles as crossing-over suppressors. 6. A diagram of the presumable localisation of genetical factors in linkage group IX is presented. It is concluded that the so-called T-locus occupies the main part of the long arm of the chromosome corresponding to linkage group IX and that the investigated t-alleles are not unilocal neither with the gene T nor each with other, but scattered along the chromosome. 7. The possible modes of the origin of new t-alleles are discussed, and the hypothesis is advanced that this event might be connected with mistakes of replication of the strand on which a new t-allele arises.

Notes: Summary The first spermatocyte division has been investigated in Rhabdophaga batatas Walsh and Wachtliella persicariae L. It was shown that the course of this division cannot be described as mitosis, either “unipolar” or “modified bipolar”. Its essential features are: complete absence of pairing and the segregation of the chromosomes into two groups composed of 4 and 30-odd chromosomes. The segregation is accomplished by a peculiar expulsion of the group of 4 chromosomes from the main nucleus followed by an unequal cytokinesis. The spindle is absent and the nuclear membrane remains present during the entire course of the division. The second spermatocyte division occurs only in the smaller cell, which contains 4 chromosomes and bears all features of normal mitosis. For the description of the course of the first spermatocyte division and chromosome distribution, which occurs in this division, the terms “segregating division” and “monocentric configuration” were proposed. The available descriptions of the first spermatocyte division in other species of Cecidomyiidae have been analyzed. The pattern of this division in all so far investigated cecidomyiid species is very uniform and the terms “unipolar” or “modified bipolar” mitoses are here also inadequate. The cases were discussed in which the peculiar chromosome arrangements arise merely as a result of positive or negative interrelations between the centriole and the chromosome parts. With this as background, the monocentric configurations in Cecidomyiidae were explained in terms of an attraction between the centriole and centromeres, operating in one group, and a repulsion between the centriole and the chromosome ends acting in the second. The other so-called unipolar mitoses have been analyzed. It was shown that under this term at least three intrinsically different configurations have been described. For the cases of Sciara, Micromalthus debilis and Cecidomyiidae, the common denominator can be found: the chromosome movements in Sciara and M. debilis can also be explained as set forth above for Cecidomyiidae, i.e. in terms of two kinds of forces operating between the centriole and the chromosomes. The several spindle fibers present in Sciara and Micromalthus do not seem to be crucial for the chromosome movements.

Notes: Zusammenfassung Aus einem Natriumaluminiumsilicat-Glas mit der Synthese-Zusammensetzung (Mol-%) 27% Na2O, 8% Al2O3 und 65% SiO2 (NAS 27-8) wurden Glaselektroden hergestellt, deren Eignung zur Indizierung der Kaliumtitration mit Zn[SiF6] in methanoliseher Lösung untersucht wurde. In reinen, schwach sauren Kaliumsalzlösungen erhält man gut auswertbare Titrationskurven. Die Glaselektrode versagt in stark saurer Lösung. Außer den Ionen, die mit Hexafluorosilicat schwerlösliche Salze bilden, stören auch Ca2+, Mg2+ und Al3+, die mit den im Gleichgewicht vorliegenden Fluoridionen reagieren.

Notes: Zusammenfassung Es wurde das Verhalten von SbIII, SnIV und AsIII in 0,1 m Ammoniumoxalat-0,1 m Oxalsäure einzeln und in Kombinationen untersucht. SbIII und SnIV geben in dieser Grundlösung gut ausgebildete Stufen und lassen sich nebeneinander bestimmen. Tritt noch AsIII hinzu, erhält man ein dreistufiges Polarogramm, dessen quantitative Auswertung lediglich für SbIII mit der üblichen polarographischen Genauigkeit möglich ist; SnIV und AsIII können dagegen nur mit geringer Genauigkeit erfaßt werden. Bessere Werte wurden auf derivativ-polarographischem Wege erhalten. Im Derivativpolarogramm, drei Strommaxima aufweisend, ist der Spitzenstrom des Antimons linear der des Zinns und Arsens logarithmisch proportional zur Konzentration.

Notes: Zusammenfassung Über die Verdampfungsform eines Elementes kann man mittels thermodynamischer Näherungsrechnungen Aussagen erhalten. Derartige Betrachtungen erweisen sich als günstig für die Dimensionierung der Elektrodenabmessungen und für die Voraussage auf Störeffekte bzw. für deren Beseitigung. Die Wirksamkeit eines Puffers läßt sich aus der Brennspannung des Bogens beurteilen. Eine optimale Pufferwirkung ergibt sich, wenn die Brennspannungen von Probe und Puffer einander ähnlich sind.

Notes: Zusammenfassung Die Elektrodenfunktionen eines Glases, bestehend aus (Mol-%) 27% Na2O, 8% Al2O3 und 65% SiO2, wurden gegenüber verschiedenen Kationen geprüft. Die Glaselektrode zeigt eine ausgeprägte Silberfunktion und läßt sich als Indicatorelektrode bei der Fällungstitration des Silberions mit Halogenid im neutralen Medium einsetzen. Als günstigster Titrator erwies sich Magnesiumchlorid, das zu einem deutlichen Potentialsprung im Äquivalenzpunkt führt. Zweiwertige Kationen beeinflussen die Indizierung nicht, wohl aber stören größere Mengen an Alkaliionen.

Notes: Aus D-Gluconsäure-δ -lacton wurden mit aliphatischen Diaminen die Mono- und Diacylverbindungen erhalten und durch Derivate charakterisiert.  -  Eine Imidazolinbildung tritt unter den angewandten milden Reaktionsbedingungen nicht ein.