Date Palm DNA Mini-Preparation without Liquid Nitrogen

We have developed a new mini-procedure for isolation of total cellular DNA from date palm (Phoenix dactylifera L.). The procedure, which does not use liquid nitrogen, has proved useful due to temporary disruptions in supplies of liquid nitrogen that occur in countries where date palm trees are cultivated. DNA suitable for RFLP and PCR analyses is obtained.     

A tracer method to study unidirectional fluxes of lithium: Application to frog skin

We describe a new tracer method to measure unidirectional fluxes of Li⁺, despite the lack of any utilizable radioisotope of lithium. This method uses the purified stable isotopes, ⁶Li and ⁷Li, detected with an ion-probe microanalyser. The accuracy is comparable to that obtained for other ions (e.g., Na⁺) with radiotracers.The method has been applied to frog skin with both faces bathed in a 20% lithium/80% sodium medium. Sodium and lithium unidirectional fluxes have been measured simultaneously. The results are consistent with lithium being actively pumped, the outflux of lithium being, however, much larger than that of sodium.     

Versuche zum Herbizideinsatz in gesäten Kohlarten

In den Jahren 1987 bis 1989 wurden die Auswirkungen und Effekte eines kombinierten Befalls des Winterweizens mit Sitobion avenae (Fabr.) und Puccinia recondita Rob.ex Desm. f.sp.tritici Erikss. untersucht. Dabei wurde das Verhalten der Schaderregerpopulationen und die Einflußnahme auf das Ertragsgeschehen bei separatem und simultanem Befall erfaßt. Während bei starkem Befall der oberen Blattetagen mit P.recondita eine Förderung der Aphidenpopulation an den Ähren der befallenen Pflanzen registriert werden konnte, war bei schwachem Braunrostbefall keine Einflußnahme auf die Blattläuse nachweisbar. Durch das kombinierte Auftreten beider Schaderreger kann es zu Reduktionen bei der Kornmasse/Ähre und bei der Tausendkornmasse kommen, die größer sind, als die Summe der Verluste bei Einzelbefall. Ähren stark braunrostbefallener Winterweizenpflanzen wurden zeitiger von S.avenae angeflogen und schneller besiedelt als diese von gesunden Kontrollpflanzen. Als Ursache für die Förderung der Populationsentwicklung von S.avenae werden durch P.recondita induzierte Veränderungen im Angebot an freien Aminosäuren in der Wirtspflanze diskutiert.     

Climate‐driven rampant speciation of the Cape flora

Aim To test whether the radiation of the extremely rich Cape flora is correlated with marine‐driven climate change. Location Middle to Late Miocene in the south‐east Atlantic and the Benguela Upwelling System (BUS) off the west coast of South Africa. Methods We studied the palynology of the thoroughly dated Middle to Late Miocene sediments of Ocean Drilling Program (ODP) Site 1085 retrieved from the Atlantic off the mouth of the Orange River. Both marine upwelling and terrestrial input are recorded at this site, which allows a direct correlation between changes in the terrestrial flora and the marine BUS in the south‐east Atlantic. Results Pollen types from plants of tropical affinity disappeared, and those from the Cape flora gradually increased, between 10 and 6 Ma. Our data corroborate the inferred dating of the diversification in Aizoaceae c. 8 Ma. Main conclusions Inferred vegetation changes for the Late Miocene south‐western African coast are the disappearance of Podocarpus‐dominated Afromontane forests, and a change in the vegetation of the coastal plain from tropical grassland and thicket to semi‐arid succulent vegetation. These changes are indicative of an increased summer drought, and are in step with the development of the southern BUS. They pre‐date the Pliocene uplift of the East African escarpment, suggesting that this did not play a role in stimulating vegetation change. Some Fynbos elements were present throughout the recorded period (from 11 Ma), suggesting that at least some elements of this vegetation were already in place during the onset of the BUS. This is consistent with a marine‐driven climate change in south‐western Africa triggering substantial radiation in the terrestrial flora, especially in the Aizoaceae.     

Ultrastructural demonstration of NAD-pyrophosphorylase activity in mouse liver nuclei.

Ultrastructural demonstration of NAD-pyrophosphorylase activity (E.C.2.7.7.1) in isolated mouse liver nuclei was investigated with the use of an electronhistochemical procedure based on the precipitation of pyrophosphate ions with lead ions under conditions permitting simultaneous ATPase inhibition by formaldehyde/ethanol prefixation. In isolated mouse liver nuclei activity of NAD-pyrophosphorylase was found in nucleoli, in interchromatin granules, coiled bodies and strand-like structures in nucleoplasm.     

Regulation of nitrogenase activity by oxygen in Azospirillum brasilense and Azospirillum lipoferum.

The nitrogenase activity of the microaerophilic bacteria Azospirillum brasilense and A. lipoferum was completely inhibited by 2.0 kPa of oxygen (approximately 0.02 atm of O2) in equilibrium with the solution. The activity could be partially recovered at optimal oxygen concentrations of 0.2 kPa. In contrast to the NH4+ switch off, no covalent modification of the nitrogenase reductase (Fe protein) was involved, as demonstrated by Western-blotting and 32P-labeling experiments. However, the inhibition of the nitrogenase activity under anaerobic conditions was correlated with covalent modification of the Fe protein. In contrast to the NH4+ switch off, no increase in the cellular glutamine pool and no modification of the glutamine synthetase occurred under anaerobic switch-off conditions. Therefore, a redox signal, independent of the nitrogen control of the cell, may trigger the covalent modification of the nitrogenase reductase of A. brasilense and A. lipoferum.