4 research outputs found
A 15N stable isotope semen label to detect mating in the malaria mosquito Anopheles arabiensis Patton
In previous studies it was determined that the stable isotope 13-carbon can be used as a semen label to detect mating events in the malaria mosquito Anopheles arabiensis. In this paper we describe the use of an additional stable isotope, 15-nitrogen (15N), for that same purpose. Both stable isotopes can be analysed simultaneously in a mass spectrometer, offering the possibility to detect both labels in one sample in order to study complex and difficult-to-detect mating events, such as multiple mating. 15N-glycine was added to larval rearing water and the target enrichment was 5 atom% 15N. Males from these trays were mated with unlabelled virgin females, and spiked spermathecae were analysed for isotopic composition after mating using mass spectrometry. Results showed that spermathecae positive for semen could be distinguished from uninseminated or control samples using the raw δ15N‰ values. The label persisted in spermathecae for up to 5 days after insemination, and males aged 10 days transferred similar amounts of label as males aged 4 days. There were no negative effects of the label on larval survival and male longevity. Enrichment of teneral mosquitoes after emergence was 4.85 ± 0.10 atom% 15N. A threshold value defined as 3 standard deviations above the mean of virgin (i.e. uninseminated spermathecae) samples was successful in classifying a large proportion of samples correctly (i.e. on average 95%). We conclude that alongside 13C, 15N can be used to detect mating in Anopheles and the suitability of both labels is briefly discussed
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Variations in phosphorus acquisition from sparingly soluble forms by maize and soybean in low- and medium-P soils using P-32
A glasshouse pot experiment was conducted to evaluate the differential ability of maize (Zea mays) and soybean (Glycine max) to utilize soil phosphorus (P) for plant growth from total-P, available-P and inorganic (Ca-P, Al-P, and Ca-P) soil P pools using a carrier-free 32P solution. A maize variety (DK 315) and a soybean variety (TGX 1910-4F) were grown in pots containing 1 kg of a low available P (Hungarian) and a medium available P (Waldviertel) soils labeled with 32P for 42 days or without 32P (unlabelled) for 42 and 60 days. The shoot and root biomass of maize and soybean were significantly greater when grown on the Waldviertel than on the Hungarian soils. The shoot P concentrations were higher for soybean (1.7-2.2 g kg-1) than for maize (1.1-1.4 g kg-1). The total radioactivity (dpm x 106) was higher in plants grown in Waldviertel than in Hungarian soil and the values reflected on the plant P uptake and shoot biomass of soybean and maize. The L- values (μgP .g soil-1) of maize and soybean were higher in Waldviertel (72-78) than in Hungarian (9.6-20) soil. No significant differences in L-values were observed for maize and soybean grown on the Waldviertel, but for the Hungarian soil, the L-values were higher for maize (20.0) than for soybean (9.6) suggesting that in this low-P soil, maize was more efficient than soybean to take up soil P. The available P (Bray II) and the Ca-P were the fractions most depleted by plants followed by the Fe-P fractions in the two soils, but differences between the crops were not significant. Maize and soybean grown on medium-P soil had a lower specific radioactivity (KBq 103. mgP-1) in shoot than those grown on the low-P soil indicating that plants were using P from the inorganic soil P pools