Serological Cross-Reactivity to Rat Anti H-Y Antiserum in the Female European Eel (Anguilla anguilla)

Anti H-Y antiserum, raised in highly inbred Lewis rats, was absorbed with gonadal cells from European eels of both sexes. It was found that rat anti H-Y antiserum cross-reacts with gonadal cells from the eel ovary but not with eel testicular cells. From these results it is suggested that in the European eel, the female is the heterogametic sex.     

Neuromuscular Systems in Molluscs

Molluscs have become increasingly popular in the study of centralneural mechanisms. More recently, there have been attempts torelate activity in central neurons with behavior in animalsof this phylum. The latter studies necessitate an understandingof the effectors of such behaviors. This requires not only informationabout the neuromuscular junction, but also an awareness of thecapabilities of the muscles themselves. Therefore, we have discussedsome structural and related functional characteristics of molluscanmuscle. We suggest that invertebrate mucles might be comparedon three scales: the amount of myofilament organization, theamount of vesicular specialization and organization, and theamount of paramyosin. We have considered some characteristicsof the widely-studied sustained contraction, known as "catch."Finally, we have discussed the neuromuscular junction—thetypes of junctions, the multiplicity of innervation, and someaspects of pharmacology. The results of such a study indicatedmany areas in which further research is essential before wecan understand behavior in terms of activity in the centralnervous system.     

Cosmine resorption structures on three osteolepid jaws and their biological significance

Cosmine resorption structures on three osteolepid jaws provide evidence for two different types of resorption process, one superficial and one initially internal. The superficial process starts in the pore canal openings. and the internal probably in the dentine pulp cavities or other cavities within the cosminc. Different stages of the superficial process that have previously not been recorded can he seen. Their positions show that superficial resorption may start in a few centers, from which it may spread in all directions but at different rates in different directions. There is no observable correspondence between the occurrence of resorption and the growth of the dermal bones along their sutures. Thus, the primary reason for resorption is not to allow marginal growth of the dermal bones. □ Cosmine resorption, osteolepids, Middle Devonian.     

Interaction of Kinetin and Indoleacetic Acid in the Avena Straight-Growth Test

Kinetin has a stimulating effect in the Avena straight-growth test. The action of different concentrations of kinetin, 2.5 × 10^?7, 2.5 × 10^?6 and 2.5 × 10^?5M, in combination with different concentrations of IAA was studied in this test. It was shown that the effect of low IAA concentrations, 0.25 × 10^?7 and 1 × 10^?7M, was strongly enhanced by the addition of all the kinetin concentrations investigated. The effect of the highest IAA concentrations, 25 × 10^?7 and 100 × 10^?7M, on the other hand, was inhibited relatively strongly by the highest employed concentration of kinetin. The results are explained as due to a kinetin-produced increase of auxin in the coleoptile segment, which in combination with low IAA concentrations can lead to a growth stimulation and with high IAA concentrations to a growth inhibition. Since kinetin in purification and chromatography of auxin can partly follow IAA, thereby affecting the quantitative yield, it is emphasized that, prior to the test, auxin extracts containing cytokinins should be freed from the latter by, for example, gel filtration or paper electrophoresis.     

Rapid moult among palaearctic passerines in West Africa- an adaptation to the oncoming dry season?

Moult of some palaearctic migrant passerines was studied at a wintering site in northern Ghana, West Africa. We present data on moult pattern and estimated moult duration for a sample of species. Savi's Warbler Locustella luscinioides , Woodchat Shrike Lanius senator and probably Grasshopper Warbler Locustella naevia deviated from the ordinary descendent moult sequence. Different measures of moult speed (moult speed of retrapped individuals, growth of individual feathers, wing raggedness and first date of completion of moult) showed unexpectedly rapid moult among individuals of several species, notably the Great Reed Warbler Acrocephalus arundinaceus and the Sedge Warbler A. schoenobaenus. The rapid moult might be an adaptation to a limited period of abundant food which comes to an end at the beginning of the dry season.     

Iterative evolution in the diatom genus Rhizosolenia Ehrenberg

Sorhannus, U., Fenster, E. J., Hoffman, A. & Burckle, L. 1991 01 15: Iterative evolution in the diatom genus Rhizosolenia Ehrenberg. Lethaia , Vol. 24, pp. 39–44. Oslo. ISSN 0024–1164.
Two late Pliocene planktic diatom lineages, Rhizosolenia sigmoida Sörhannus and Rhizosolenia praebergonii Mukhina, originated consecutively from Rhizosolenia bergonii Peragallo in the eastern equatorial Pacific Ocean. This morphological iteration is closely associated with two successive shifts in the oxygen isotope record (¹⁸O/¹⁶O) at approximately 3.3 Ma and 2.9 Ma. suggesting that palcoenvironmental factors may have been directly or indirectly involved in initiating these events. Iterative evolution, pseudoextinction. diatom, oxygen isotope record .