ALBERT

Notizen: Zusammenfassung Agar-aktiviertes Kaninchenplasma (Anaphylatoxin) setztin vitro Histamin und Serotonin aus normalen Kaninchenblutplättchen frei. Dieser Effekt ist vom Stoffwechsel der Thrombocyten abhängig, da er durch Dinitrophenol gehemmt wird. Bei Anwesenheit von Glukose wird die Hemmung aufgehoben.

Notizen: Summary InSolanum lycopersicum pachytene chromosomes the gradient in chromomere size, originating on both sides of the kinetochore, reveals the following characteristics: 1. a relatively abrupt decrease in size of the large chromomeres, 2. the gradient is related to arm length in 9 of the 12 chromosomes, 3. the gradient is particularly irregular in the short arm of the nucleolar chromosome and in the long arm is not conspicuous, 4. chromosome 6 shows an abrupt interruption in the gradient close to the kinetochore. Salvia viridis andZea mays chromosomes represent intermediate conditions between species with well defined and species without gradients. InSalvia the intermediate condition is manifested by the presence of a very large chromomere on each side of the kinetochore followed by very small chromomeres. In two chromosomes the intermediate condition is particularly apparent. In these chromosomes two chromomeres of intermediate size are present in the proximal region of the long arm. The nucleolar organizing arm has also an irregular pattern in this species. Maize has a less distinct gradient than tomato in all its chromosomes. Chromosomes 3, 4, 5 and 8 are those where the gradient is the least sharp. The nucleolar organizing arm of chromosome 6 has also an irregular pattern. In a translocation between chromosomes 5 and 6 of maize, a segment composed of very small chromomeres from the distal region of 5 which was moved to the right of the kinetochore of chromosome 6, did not change appreciably its phenotype after ten years of cultivation. During the period of cultivation a selection was made for plants where the original phenotype was preserved so that this result cannot be considered as demonstrating an absence of change in chromomere phenotype with changed position. InDrosophila andChironomus salivary gland chromosomes where chromomeres are large, and no selection has been carried out with such a purpose, the pattern and nucleic acid content of the bands is known to change when rearrangements occur within the chromosome.

Notizen: Summary 1. Chromosomes ofAllium cepa, Tradescantia virginiana andT. paludosa were studied at mitosis in order to investigate the behavior of telomeres at anaphase. The studies were made in untreated fixed material, in cochicine treated cells, and in living staminal hairs. 2. InAllium cepa andT. virginiana chromosomes of untreated material, when the kinetochores start separating to opposite poles at early anaphase of mitosis, the median regions of the arms separate first, the proximal regions next and the telomeres last. 3. To study which region of the arms outside the proximal regions was involved in holding the sister chromatids together, 736 chromosome arms of completely flattened chromosomes were analyzed in colchicine treated cells ofA. cepa. In 14.9% the delayed separation involved the whole arm, in 2.8% it was in the median region, in 8.9% it was close to the telomere, and in 71.0% of the cases it was well localized at the telomere. 4. The colchicine treatment causes a change in the timing of the separation process in bothA. cepa andT. virginiana. When this treatment is applied the proximal regions of the arms separate later than the ends. 5. A study was made at mitosis of the whole chromosome complement ofAllium cepa. 1472 chromatid arms were analyzed and measured. All the 8 chromosomes of the haploid set ofA. cepa can be identified in well flattened cells. To find out whetherthere is any correlation between the division cycle of the telomere region and arm length (the distance telomere—kinetochore), an analysis was made of 736 chromosome arms. The 16 arms of the complement were grouped according to their length. Group I contains the two smallest arms and group IV the three largest. A statistical analysis of the data shows that there is a significant difference between the delayed separation at the ends of small versus longer arms. A χ2 of group I versus groups II, III, and IV gives the value 12.71 with P〈 0.001. The telomeres which are situated closer to the kinetochore separate earlier than those that are situated further away. This is not interpreted as being due to a mechanical effect of the kinetochore, because the proximal regions which are situated between the kinetochores and the telomeres, separate later than the telomeres of all groups of arms. 6. Studies of mitotic chromosomes were madein vivo in the staminal hairs ofT. virginiana andT. paludosa. At anaphase the telomeres can be seen to separate last just as in the fixed untreated material. 7. When the sister chromatids of an arm separate at early anaphase the telomere is considered to have the role of the fulcrum of a lever. The two arms of a chromosome are lifted as levers by the kinetochore and in the telomeres they get their point of support. In short arms such an adaptation is not necessary, as the telomeres are quite close to the kinetochore, but in long arms, as those of the species studied here, this adaptation results in an easier and more regular separation of the arms.

Notizen: Summary Whole cysts in the testicular tubes of Melanoplus differentialis disintegrate giving rise to large Feulgen positive bodies. The disintegration affects all the nuclei of a cyst. The Feulgen positive bodies are strongly labelled with tritiated thymidine, a confirmation of their DNA content. Spectrophotometric measurements reveal that the bodies contain 3.5 times more DNA per unit area than the autosomes of normal spermatocyte nuclei and an equal amount of DNA per unit area as the sex chromosome of the same nuclei. This regular disintegration of spermatocytes is not considered as a pathological condition but as an adaptation by which large amounts of DNA are easily released at a convenient time of development.

Notizen: Summary In Tipula oleracea females 2n=6+XX (Diptera) a Feulgen positive body is present in the oogonia and oocyte nuclei. This body appears in the nucleus at the oogonial divisions that precede meiosis. It gets larger by leptotene, attaining a diameter of 6 microns, and at diplotene suddenly disintegrates. By metaphase I the body is not seen. Injection of tritiated thymidine into the larvae leads to a heavy labelling of the Feulgen positive body. The body is found to synthesize DNA at a different period of time from the chromosomes, and there is an intermediate period when the synthesis of the two nuclear structures overlaps. The tritium labelled thymidine is released from the body between the third and fourth day of pupal life. At this time the yolk granules in the cytoplasm become particularly conspicuous. When the body disintegrates the labelled material becomes easily diluted. The volume of the nucleus and of the cytoplasm are sufficiently large to dilute this material in such a way that it easily becomes indistinguishable from background radiation. Spectrophotometric measurements of the body reveal that it contains four times more DNA per unit area than the chromosomes. The area of the body is 28.3 square microns and that of the chromosomes 78.5 square microns. This means that the amount of DNA in the body is of a higher order of magnitude than that found in all the chromosomes. This large amount of DNA becomes suddenly available either to the chromosomes or other cellular components. DNA can carry its own genetic information to other cellular components.

Notizen: Chemical and spectroscopic evidence leads to constitution III for the bluish-red antibiotic biflorin, C20H20O3 obtained from Capraria biflora L.