Synthese der Hämolymphproteine und die Aufnahme der Dotterfraktion in die Oocyte unter Actinomycin-Einflu\ (Untersuchungen anMusca domestica)

Zusammenfassung Mit Hilfe von autoradiographischen und elektrophoretischen Methoden wurde die Dottereinlagerung in den wachsenden Oocyten vonMusca domestica untersucht. Sie beginnt nach 30 min im Autoradiogramm sichtbar zu werden. Durch ihre Färbbarkeit und Markierung konnte die Dotterfraktion im Pherogramm von Ovar und Hämolymphe eines mittleren Wachstumsstadiums (Stadium 3) nachgewiesen werden. Nach Abschlu\ der Vitellogenese tritt sie in der Hämolymphe nicht mehr auf. Die Einlagerung der Dotterproteine wird durch Actinomycin gestört, dagegen läuft ihre Synthese nahezu unbeeinflu\t weiter. Die Transporthemmung kann als bisher unbekannter Nebeneffekt des Actinomycins gedeutet werden.

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Synthesis of haemolymph proteine and the uptake of the yolk fraction in the oocyte during Actinomycin-treatment. (Studies onMusca domestica)

Summary By means of radioautographic and electrophoretic techniques yolk protein uptake in the growing oocytes ofMusca domestica was investigated. After 30 min yolk protein becomes visible in the radioautograms. By stainability and labeling the yolk fraction could be demonstrated in the pherogram of ovary and haemolymph in an intermediate developmental stage (stage 3). After the end of vitellogenesis it does not appear in the haemolymph. The yolk protein uptake is inhibited by Actinomycin, but the synthesis goes on nearly as normal. This inhibition can be interpretated as a new accessory effect of Actinomycin.

     

Geschlechtliche organisation,fortpflanzungsverhalten und ursachen der sexuellen vermehrung von Stenostomum sthenum nov. spec. (Turbellaria,Catenulida)

Certain temperatures and H-Ion concentrations are necessary for the development of male and female reproductive organs. The differentiation of the reproductive system from undifferentiated cells conforms precisely with data on other species of Stenostomum.

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Abkürzungen in den Abbildungen b Bindegewebszelle - c Cilien - cy Cytoplasma - d Darm - de Ductus ejaculatorius - dl Darmlumen - do Dotter - dr Drüsenzellen - lr Lÿckenraum - m Mundöffnung - n Nucleolus - np Nephroporus - o Ovar - p männlicher Genitalporus - pa parenchymatischer Raum - pf periembryonale Flüssigkeit - dse dorsale Epidermis - e dorsolaterale Epidermis - ed extraembryonaler Dotter - ee Epidermiseinstülpung - eh Epidermis +Hautmuskelschlauch - em Embryo - ex Exkretvakuole - f Freßzelle - g Gehirn - ga Gehirnanlagen - gr Granula - h Hautmuskelschlauch - hz Hüzllzelle - kl Versehlußkegel/Klebkegel - in indifferente Zelle - k Kern - kdr Klebdrüsenzelle(n) - kk kollabierter Kanal - kö Körnerkolbenzelle - kp Kopulationsorgan - ku Kufen - kw Körperwand - l Lichtsinnesorgan - li Linsenkörper - lk lichtbrechende Konkremente im Darmgewebe - ph Pharynx - phr Pharynxregion - pr Zentralkanal des Protonephridialsystems - ps Präspermatide - pu Punktfeld - q Zellquartett - r Riechgruben - rh Rhombuszellenband - rhb Rhabditen - rm Radiärmuskelzelle - rhs Rhabditenschleim - rs resorbierende Darmzelle(n) - s Schale - sc Spermatocyten - se Sekretgang - t Tastborste - ta Auflösungsprodukte des Hodens - te Hoden - to Terminalorgane(e) - tz Teilungszone - v Vakuole - w vermutliches Rudiment des weiblichen Genitalporus     

Cytological and autoradiographic studies in Sciara coprophila salivary gland chromosomes

Summary Morphological and metabolic changes on the salivary chromosomes of Sciara coprophila were followed during the later half of the fourth larval instar.Cytological maps were prepared for five successive stages from mid-fourth instar to the prepupal stage. These maps, which constitute a revision of those published earlier by Crouse, summarized our cytological findings and were the basis for studies on DNA replication of these chromosomes.Similar to earlier studies in Chironomidae, differences in the puffing pattern were noted between the anterior and the posterior portions of the salivary gland. The most striking difference was noted in region 2B on chromosome III which produces a large puff only in nuclei from the anterior part of the gland. Other autosomal puffs, although present in both parts of the gland, showed constant differences in size.An increase in the number of bands from mid-fourth to late fourth instar was observed. The new bands are all of the light-staining kind.In Sciara the puffed area may include a large number of bands in addition to the bands which originated the puff. The maximal extent of puffs was determined in terms of chromosomal map regions and the number of bands subject to obliteration.In the autoradiographic experiments use was made of H³-thymidine as DNA precursor. The aim of these studies was to detect any asynchronies in the replication time of bands. In fact, marked differences in the relative rates of uptake of H³-thymidine of a number of bands in a certain proportion of chromosomes have been observed, while others showed uniform incorporation. Since these latter were found with higher frequency the period of uniform labeling must comprise a larger part of the replication cycle then the periods of localized labeling. To assess the validity and constancy of the observed patterns of unequal incorporation, a semiquantitative analysis was carried out. It showed that the bands showing localized uptake may be separated into two broad groups. In one of these groups are the centromere regions and certain chromosomal ends, which are presumably heterochromatic. The other group comprises most of the puff sites and bulbs. Since late replication is characteristic of heterochromatin, we assumed that bands of the former group (C) replicate late in the cycle, while puffs and bulbs start replication early, and the period of equal labeling is intermediate. Other intermediate labeling patterns were observed and are described.It is known that in the fourth instar from two to three DNA replications occur in the salivary gland nuclei, the last of which coincides with puffing. Several stages may be distinguished in the puffing process based on morphology and rates of isotope uptake of the puffs. The first sign of puffing is a very high rate of incorporation at puffs. It is maintained throughout this last DNA synthesis period and only declines when all other chromosomal regions have ceased to replicate. A pattern of high and exclusive uptake at the heterochromatic sites (pattern C) was never observed in this replication; instead puffs are the last regions to terminate DNA synthesis.These results are discussed in relation to several current problems, such as, asynchronous DNA replication, the problem of metabolic DNA, and the concept of the heterochromatic state.Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, in the Faculty of Pure Science, Department of Zoology, Columbia University, New York. This work has been supported by U.S. Public Health Training Grant No. 2Tl-GM-216-05; partial support has been received also from Grants GB 42 and G-14043 from the National Science Foundation to Dr. H. V. Crouse.     

Harnsäure als zusätzliche stickstoffquelle Für larven von Lasioderma Serricorne F.

Zusammenfassung Larven von Lasioderma serricorne F. sind in der Lage, bei Unterdosierung des Caseins in synthetischen Diäten Guanin, Xanthin, Harnsäure und Allantoin als zusätzliche N- Quellen zu verwerten. Die Bedeutung für den Proteinhaushalt der Larven Bowie die Beteiligung der Symbionten werden diskutiert.     

Configurations resulting from iso-chromatid and iso-subchromatid unions after meiotic and mitotic prophase irradiation

Summary By making use of the chromosomes of Trillium erectum as a model, potential and actual configurations arising from presumed iso-chromatid and iso-subchromatid unions after irradiation of meiotic or mitotic prophase have been studied and analyzed. Diagrams and photographs of various recognizable types of chromatid or subchromatid rearrangements are presented. A minimum of two iso-chromatid unions within an arm of a single chromosome in meiotic prophase, if separated by a single chiasma, can give rise to a monocentric chromosome with a triplicated segment, the middle portion of which is an inversion. A minimum of two iso-subchromatid breaks within an arm at either meiotic or mitotic prophase also can result in the production of a monocentric chromosome containing a triplicated segment. The stage of appearance of dicentrics or bridges arising from chromatid or subchromatid unions in meiotic prophase is influenced by chiasma number and pattern and by the number of strands per chromosome or chromatid. Some of the rearrangements described may have genetic and evolutionary implication of considerable potential importance which has not been recognized previously.Research carried out at Brookhaven National Laboratory under the auspices of the U.S. Atomic Energy Commission.