Nachweise von Zweitbruten beim Wei?sternigen Blaukehlchen (Luscinia svecica cyanecula)

Summary Close to the village Trieb in Upper Franconia (50° 09 N/11° 10 E) two cases of second breeding in the Bluethroat could be proved. The birds were colour-banded. Second broods are presumably rather common in the population along the upper River Main.     

Mechanical constraints canalizing the evolutionary transformation of tetrapod limbs

A reconstruction of the anagenetic transformations from fins to tetrapod limbs is represented considering the self-evident mechanical constraints which must have limited the construction and thus the function and the transformation.     

Impaired natural killer cell function in hemophiliacs with or without continuous substitution

In the present study, 28 hemophiliacs substituted continuously and 5 hemophiliacs who had received almost no blood products were investigated. Cells of OKT 3+, OKT 4+, and OKT 8+ subsets were counted. Percoll separated fractions of peripheral blood mononuclear cells were examined by morphological criteria and were tested for NK cell activity. We found that the NK cell activity of both groups of hemophiliacs was decreased on testing Ficoll separated cells or low density Percoll separated cells. Normal NK cell activity was found in medium density cells of hemophiliacs. Two possible explanations are discussed: first, the NK cell activity may be suppressed in hemophiliacs and secondly, there may be a block in maturation of NK cell activity. It is unlikely that chronic substitution by blood products counts for these alterations. The possible role of chronic infections is discussed.     

Differential staining of plant chromosomes with Giemsa

Simple Giemsa staining techniques for revealing banding patterns in somatic chromosomes of plants are described. The value of the methods in the recognition of heterochromatin was demonstrated using five monocotyledonous and two dicotyledonous species. In Trillium grandiflorum the stronger Giemsa stained chromosome segments were shown to be identical with the heterochromatic regions (H-segments) revealed by cold treatment. Preferential staining of H-segments was also observed in chromosomes from three species of Fritillaria and in Scilla sibirica. Under suitable conditions the chromosomes of Vicia faba displayed a characteristic banding pattern and the bands were identified as heterochromatin. The Giemsa techniques proved to be more sensitive than Quinacrine fluorescence in revealing a longitudinal differentiation of the chromosomes of Crepis capillaris, where plants with and without B-chromosomes were examined. Again all chromosome types had their characteristic bands but there was no difference in Giemsa staining properties between the B-chromosomes and those of the standard complement.     

Die Spermiohistogenese des Süßwasser-Ostracoden Notodromas monacha O. F. Müller

Zusammenfassung Bei Notodromas monacha (Ostracoda) wird die Entwicklung der Spermatiden von der Spindelbis zur Schlauchform mit Phasenkontrast und elektronenmikroskopisch untersucht. Am Kern der spindelförmigen Spermatiden sind an zwei gegenüberliegenden Seiten jeweils zwei Ausstülpungen der Membran zu beobachten. Aus ihnen werden offenbar unter Beteiligung von Vesikeln des endoplasmatischen Reticulum zwei Flügelstrukturen aufgebaut. Jede Flügelstruktur besteht aus zwei Lamellen, die mit tubulären Elementen besetzt sind. An den schlauchförmigen Spermatiden läßt sich ein dicker Körper und ein dünner Faden unterscheiden. Kern, Nebenkern-Derivate und Flügelstrukturen durchziehen den Körper der Länge nach. Der Faden enthält nur noch den Kern und die Ausläufer der Flügelstrukturen. Im Bereich des freien Körperendes liegt im Kern ein als Chromatin gedeuteter Kolben. Diesem folgt in Richtung zum Fadenende ein dichter Achsenstab, der von einer Doppelmembran umhüllt ist. Im dorso-lateralen Kernraum finden sich elektronendichte Brocken unbekannter Bedeutung. Nach Beendigung des Aufbaues der Flügelstrukturen wird das endoplasmatische Reticulum samt Mikrotubuli weitgehend abgebaut. Gleichzeitig verschwindet die den Achsenstab umhüllende Doppelmembran. Die Flügelstrukturen werden als das für die Motilität der Spermien verantwortliche Organell gedeutet.

---

The spermiogenesis of the fresh-water ostracod Notodromas monacha O. F. Müller

Summary The transformation of spindle-like spermatids into tubular forms in Notodromas monacha (Ostracoda) has been studied by means of phase contrast and electron microscopy. At each of two opposite sides of the nucleus of spindle-like spermatids, two extensions of the nuclear membrane arise. These extensions form two Flügelstrukturen (wing-like structures) obviously by participation of vesicles of the endoplasmic reticulum. Each Flügelstruktur consists of two lamellae, each bearing numerous tubules. The tube-like spermatids consist of a large body and a small thread. The nucleus, the Nebenkern-derivatives and the Flügelstrukturen extend through the whole body. Within the thread only the nucleus and the outermost parts of the Flügelstrukturen are found. A columnar body, supposed to be chromatin, is located within that part of the nucleus which is situated in the free end of the body. A dense axial rod extends between the columnar body and the free end of the thread. The dorso-lateral sphere of the nucleus contains electron dense particles of unknown function. As soon as the construction of the Flügelstrukturen is finished, the endoplasmic reticulum and the microtubules are reduced. Simultaneously the double-membrane surrounding the axial rod disappears. The Flügelstrukturen are interpreted as organelles responsible for the motility of the sperm.

     

Genetische Untersuchungen zur Resistenz der Gerste gegen Gelbrost (Puccinia striiformis West.)

Zusammenfassung Fünf Sommergersten, die gegen Rasse 24 von Puccinia striiformis resistent sind, wurden in fast allen möglichen Kombinationen miteinander und mit drei anfälligen Formen gekreuzt. Die F ₂-Generationen, in zwei Fällen auch die F ₃, wurden im Gewächshaus mit Rasse 24 infiziert. Zusätzlich konnten F ₂-Generationen einiger Kreuzungen auch auf dem Feld mit Rasse 24 geprüft werden. Eine sichere Klassifikation und damit die eindeutige Analyse der Ergebnisse war nur im Gewächshaus möglich. Die Feldversuche stützen zwar diese Ergebnisse, hätten aber allein keine sicheren Schlüsse erlaubt.Die Resistenz aller fünf untersuchten Gersten ist monogen rezessiv bedingt. Drei von ihnen sind bezüglich des Resistenzgens allel: Bigo — yr, Ab. 14 — yr, BBA 2890 — yr. In Abed Binder 12 liegt yr2 vor, in I 5 yr3. Die Ergebnisse deuten auf Unabhängigkeit der drei Gene, enge Kopplung kann ausgeschlossen werden.

---

Genetic studies on the resistance of barley to yellow rust (Puccinia striiformis West.)

Summary Five spring barley varieties resistant to race 24 of Puccinia striiformis were crossed with each other and with three susceptible varieties (Table 1) in almost all possible combinations. The F ₂ generations and in two cases also the F ₃, were inoculated in the greenhouse with race 24. F ₂ generations of some of the crosses were, in addition, tested with race 24 in the field. Dependable classification of resistance and, consequently, unambiguous interpretation of results was possible only for the experiments carried out in the greenhouse. Although the field tests confirmed these results, they would not have been conclusive by themselves.The resistance of all of the five varieties studied is due to single recessive genes (Table 2). Three of the varieties have alleles at the same locus, the other two varieties have other resistance genes (Tables 3 and 4): Bigo — yr, Ab. 14 — yr, BBA 2890 — yr; Abed Binder 12 — yr2; I 5 — yr3. The results suggest that the three genes are inherited independently, close linkage can be excluded.

---

---

Angenommen durch H. Stubbe     

Book reviews

Ohne Zusammenfassung

---

Book reviews