Polyploid formation pathways have an impact on genetic rearrangements in resynthesized Brassica napus

? Polyploids can be produced by the union of unreduced gametes or through somatic doubling of F(1) interspecific hybrids. The first route is suspected to produce allopolyploid species under natural conditions, whereas experimental data have only been thoroughly gathered for the latter. ? We analyzed the meiotic behavior of an F(1) interspecific hybrid (by crossing Brassica oleracea and B.rapa, progenitors of B.napus) and the extent to which recombined homoeologous chromosomes were transmitted to its progeny. These results were then compared with results obtained for a plant generated by somatic doubling of this F? hybrid (CD.S?) and an amphidiploid (UG.S?) formed via a pathway involving unreduced gametes; we studied the impact of this method of polyploid formation on subsequent generations. ? This study revealed that meiosis of the F? interspecific hybrid generated more gametes with recombined chromosomes than did meiosis of the plant produced by somatic doubling, although the size of these translocations was smaller. In the progeny of the UG.S? plant, there was an unexpected increase in the frequency at which the C1 chromosome was replaced by the A1 chromosome. ? We conclude that polyploid formation pathways differ in their genetic outcome. Our study opens up perspectives for the understanding of polyploid origins.     

Utilization of copra meal in the formulation of compound diets for rohu, Labeo rohita, fingerlings

Six isonitrogenous (35% crude protein) experimental diets were formulated with raw and soaked de-oiled copra meal substituted for fish meal in the diet at 20, 30 and 40% levels by weight. The tannin content of raw de-oiled copra meal was reduced from 2.4 to 0.9% by soaking it in water for 16 h at room temperature. The response of rohu, Labeo rohita (Hamilton), fingerlings fed these diets for 80 days was compared with fish fed a fish meal-based control diet. On the basis of growth response, food conversion ratio and protein efficiency ratio, the 30% soaked copra meal diet resulted in the best fish performance (P < 0.01). The growth response of the fish was significantly (P < 0.01) affected by both type and inclusion level of the oilseed meal. The growth of fish declined with the increasing level of inclusion of copra meal, irrespective of the type of meal used. The apparent protein digestibilities (APDs) for the raw copra meal were lower at all levels of inclusion in comparison with those for the soaked meals. The highest amount of carcass protein was recorded in the fish fed the diet containing 30% soaked copra meal. The results showed that de-oiled copra meal can be incorporated into carp diets up to 20% in the raw condition and up to 30% in the treated condition without any deleterious effects on growth performance of Labeo rohita fingerlings.     

Holcus mollis L. subsp. hierrensis (Poaceae), a new subspecies of El Hierro (Canary Islands), and some notes on the species

Holcus mollis L. subsp. hierrensis is new to science. Its distinct chamaephytic habit and particular features of the morphology of the spikelets, provided in a key, as well as its ecology allow a taxonomic separation from the otherwise similar subsp. mollis. A short survey of important facts about the species given in the literature is presented. The possible status of the new subspecies as a neoendemic of the island of El Hierro (Canaries) is discussed.     

The incidence of air-borne fungus in Sydney

Summary A survey of the incidence of air-borne fungi in Sydney was carried out for one year by daily exposure of Petri plates containing Sabouraud's medium. A total of 3893 colonies were counted.The fungi most commonly grown wereCladosporium, Alternaria andEpicoccum; these accounted for 51.9% of all colonies.An attempt was made to correlate the work with the average daily mean temperature, the relative humidity and the number of rainy days. No clear correlation could be established between colony counts and wind direction and velocity.

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Zusammenfassung Eine Untersuchung über das Vorkommen von durch die Luft getragenen Pilzen in Sydney wurde während eines Jahres durch tägliche Ausstellung von Petri-Schalen mit Sabouraud's Nährmedium durchgeführt. Insgesamt sind 3893 Kolonien gezählt worden.Die am häufigsten gefundenen Pilze waren:Cladosporium, Alternaria undEpicoccum; sie umfassten 51.9% aller Kolonien.Ein Versuch wurde unternommen, um diese Befunde mit der durchschnittlichen, täglichen Mitteltemperatur, der relativen Feuchtigkeit und mit der Zahl der Regentage in Korrelation zu bringen. Keine klare Korrelation konnte zwischen Kolonie-Zahl, Windrichtung und Windgeschwindigkeit festgestellt werden.

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Working with the help of a full time grant from the National Health and Medical Research Council of Australia.