Karyotype analysis in meiosis: Giemsa banding in the genus Secale L.

Summary Terminal bands of meiotic chromosomes stained by the Giemsa technique are permanent genetic structures of the nucleus during PMC differentiation in 8 samples of wild, primitive, and cultivated species of rye. The characteristic meiotic banding pattern is probably identical with the heterochromatic regions of mitotic chromosomes of root meristem cells (RMC) which have so far been studied. Karyotype analysis can be significantly improved by quantitative studies of the number and size of the bands combined with certain well-known chromosome characters in diplotene and diakinesis. The chromosomes involved in multivalents of some natural and synthetic species hybrids are identified for the first time. The results are discussed both in relation to the problems of chromosome evolution and their significance for marker techniques in cytogenetics.     

Mother-young Relationships in Captive Ungulates: Behavioral Changes over Time

Ungulates are frequently classified into two groups: the “followers”, in which young initially stay close to their mother and the “hiders”, in which young remain at some distance from their mother, often concealed in vegetation. To examine differences in mother-young behavior between the follower and hider groups and among species within these groups, we studied 63 mother-young pairs, representing 22 ungulate species, for 7 weeks after birth of the young. The follower group had consistently higher scores than the hider group on measures of mother-young association, and lower scores on the percentage of time the young spent lying; however, there was considerable variation within each group. In follower species, two measures of mother and young association decreased over time. In hiders, contact between mother and young did not increase over time although the distance between them, while both were lying, decreased. This reduction in the resting distance between mother and young did not always coincide with other changes possibly indicative of the end of the hiding period. The amount of time young hiders spent lying decreased over time.     

Endogene Stoffproduktionsrhythmen bei Phaseolus vulgaris

Experimente mit vollausgewachsenen Primär- und Folgeblättern der Buschbohne cv. Saxa unter programmierten Klimabedingungen ergaben bei der Bestimmung der Stoffproduktion mit Hilfe eines Kalorimeters rhythmische Änderungen in dem auf die assimilierende Blattfläche (V_F) bzw. das Trockengewicht bezogenen (V_T) Energiegehalt der produzierten Pflanzenstoffe. Die Trockensubstanzproduktion paßte sich regelmäßig der in der Klimakammer eingestellten Photoperiode an. Am Ende einer Lichtperiode ist der auf die Blattfläche bezogene Kalorienwert V_F stets wesentlich höher als am Ende einer Dunkelperiode; die Pflanze arbeitet also nur im Licht mit positiver Bilanz. Bezieht man den Energiewert jedoch auf das Trockengewicht (V_T), ist es gerade umgekehrt, d. h. in der Dunkelheit werden relativ mehr energiereiche Substanzen angehäuft als im Licht. Im Dauerlicht und Dauerdunkel schwingt der Rhythmus nach. Beim Umschalten auf eine veränderte Photoperiode paßt sich der Rhythmus erst nach Durchlaufen je einer Licht- und Dunkelphase der neuen Behandlung an. Als Auslöser scheint ein einmaliger Hell- und Dunkelwechsel möglich, verschiedene Lichtqualitäten und Photoperioden bleiben ohne Einfluß. Der Zeitgeber für die endogene Rhythmik ist noch unbekannt     

Analysis of single protoplasts and regenerated plants by PCR and RAPD technology

Summary We investigated the use of the polymerase chain reaction (PCR) and the associated random amplification of polymorphic DNA (RAPD) technique in the analysis of DNA and specific genes in plant cells at different stages of regeneration in in vitro cultures. We demonstrate that both procedures can be used to differentiate reproducibly between closely related species as well as to reveal levels of DNA polymorphism in regenerated plants. We also demonstrate that both procedures, using protocols that we have developed, are applicable at all tissue culture stages, from single isolated protoplasts to regenerated plants. Possible explanations for the variation levels detected in regenerated wheat plants are advanced.