Determination of 17alpha-methyltestosterone in muscle tissues of tilapia, rainbow trout, and salmon using liquid chromatography-tandem mass spectrometry

An analytical method was developed to quantitate and confirm the presence of 17alpha-methyltestosterone in the muscles of tilapia, rainbow trout, and salmon. The method employed two liquid-liquid partitioning steps and two solid-phase extraction columns for sample cleanup. The final extracts were analyzed on an isocratic reverse-phase liquid chromatography-tandem mass spectrometry system with atmospheric-pressure chemical ionization in the positive ion mode. The method was validated at levels from 0.40 to 1.6 ng/g, with MT-d3 used as an internal standard. The accuracy was between 100% and 110%, and coefficients of variation of <10% were obtained for all three fish species. Muscle tissues from dosed fish were also assayed to demonstrate the effectiveness of the method for recovering the parent drug.     

Electrical wind force-driven and dislocation-templated amorphization in phase-change nanowires

Phase-change materials undergo rapid and reversible crystalline-to-amorphous structural transformation and are being used for nonvolatile memory devices. However, the transformation mechanism remains poorly understood. We have studied the effect of electrical pulses on the crystalline-to-amorphous phase change in a single-crystalline Ge(2)Sb(2)Te(5) (GST) nanowire memory device by in situ transmission electron microscopy. We show that electrical pulses produce dislocations in crystalline GST, which become mobile and glide in the direction of hole-carrier motion. The continuous increase in the density of dislocations moving unidirectionally in the material leads to dislocation jamming, which eventually induces the crystalline-to-amorphous phase change with a sharp interface spanning the entire nanowire cross section. The dislocation-templated amorphization explains the large on/off resistance ratio of the device.     

The psyllid Macrohomotoma gladiata Kuwayama, 1908 (Hemiptera: Psylloidea: Homotomidae): a Ficus pest recently introduced in the EPPO region

The psyllid Macrohomotoma gladiata, is a new insect pest of Ficus originating from Asia which has recently been found in Spain (Alicante) on urban Ficus microcarpa trees. This species may be of phytosanitary concern because of its leaf wrapping habits, wax secretion and honeydew excretion that may lead to direct and secondary twig damage. Although more studies are needed on the biology of M. gladiata, it is suspected that it might behave in the Euro‐Mediterranean as an invasive alien species. The predation by Anthocoris sp. (nemoralis?) needs to be investigated in order to assess its effectiveness as a natural biological control agent. This is the first report of M. gladiata from the EPPO region.     

SUSTAINABLE NITROGEN MANAGEMENT IN AUSTRALIAN AGROECOSYSTEMS: CHALLENGES AND OPPORTUNITIES

● There is huge potential for improvement of nitrogen management in Australia. ● N management should incorporate environmental, social and economic sustainability. ● Agronomic, ecological and socioeconomic approaches and efforts are needed. Nitrogen is an essential nutrient that supports life, but excess N in the human-environment system causes multiple adverse effects from the local to the global scale. Sustainable N management in agroecosystems, therefore, has become more and more critical to address the increasing concern over food security, environmental quality and climate change. Australia is facing a serious challenge for sustainable N management due to its emission-intensive lifestyle (high level of animal-source foods and fossil fuels consumption) and its diversity of agricultural production systems, from extensive rainfed grain systems with mining of soil N to intensive crop and animal production systems with excessive use of N. This paper reviews the major challenges and future opportunities for making Australian agrifood systems more sustainable, less polluting and more profitable.     

Size isn't everything: movements,home range,and habitat preferences of eastern blue gropers (Achoerodus viridis) demonstrate the efficacy of a small marine reserve

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New production strategy for silver perch (Bidyanus bidyanus); over‐wintering fingerlings in a tank‐based recirculating aquaculture system

Slow growth and losses to bird predation and infectious diseases in winter can compromise the profitability of silver perch farming. To evaluate over‐wintering silver perch (Bidyanus bidyanus) in a recirculating aquaculture system (RAS), fingerlings (38 g) were stocked in either cages in a pond at ambient temperatures (10–21 °C) or tanks in the RAS at elevated temperatures (19–25 °C) and cultured for 125 days. Mean survival (96%), final weight (146 g), specific growth rate (1.07% day^?1) and production rate (28.1 kg m^?3) of fish in the RAS were significantly higher than for fish over‐wintered in cages (77%, 73 g, 0.53% day^?1, 11.1 kg m^?3). Fish from both treatments were then reared in cages for a further 129 days. Final mean weight of fish originally over‐wintered in the RAS was 426 g, while fish over‐wintered in cages were only 273 g. To determine optimal stocking densities, fingerlings (11.8 g) were stocked at 500, 1000 or 1500 fish m^?3 in tanks in the RAS and cultured for 124 days. Survival was not affected, but growth was significantly slower and feed conversion ratio higher at 1500 fish m^?3 compared with 500 or 1000 fish m^?3. Results demonstrate that over‐wintering silver perch in an RAS can produce large fingerlings for grow‐out in early spring. This strategy could eliminate bird predation, reduce losses to diseases and shorten the overall culture period.     

Alternative Solids Removal for Warm Water Recirculating Raft Aquaponic Systems

Aquaponics is an integrated fish and plant recirculating production system. The University of the Virgin Islands' raft aquaponic system uses a cylindro‐conical clarifier as a primary solids removal device; however, a swirl separator may offer advantages. The objectives of the 8‐wk experiment were to compare water quality parameters, Nile tilapia, Oreochromis niloticus, production and water spinach, Ipomoea aquatica, production in a raft aquaponic system using a clarifier or swirl separator for primary treatment of solids in the waste stream . No significant differences (P ≥ 0.05) existed between treatments for temperature, oxygen, pH, total suspended solids, alkalinity, electrical conductivity, total ammonia‐nitrogen, nitrite‐nitrogen, nitrate‐nitrogen, macronutrients, and micronutrients concentrations in the culture water. There were no significant differences (P ≥ 0.05) between treatments for Nile tilapia production, average weight, survival, or feed conversion ratio. There were no significant differences (P ≥ 0.05) between treatments for water spinach production or plant tissue analysis. In conclusion, the swirl separator used in this experiment performed similar to the clarifier and water spinach grew vigorously in the raft aquaponic system .     

Growth and fruit production of Sclerocarya birrea in the South African lowveld

Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro. is a common species throughout the semiarid, deciduous savannas of much of sub-Saharan Africa. It is a favoured species and is frequently maintained in homestead plots and arable fields in an agroforestry situation. Although the abundance and popularity of this species has led to several initiatives to commercialise a number of marula products, the sustainability of the resource base with respect to fruit production has not been considered. This paper reports on a field experiment that monitored growth rates and fruit production of a sample of adult trees from several wild populations. Mean fruit production was 36.8 kg per tree in the first year, and negligible in the second. This was considerably less than previous estimates, which were based largely on small samples or anecdotal reports. The maximum recorded yield was 416.6 kg per tree. Fruit production was positively related to the size of the tree. Growth rates of adult trees were slow. There was a strong positive relationship between mean annual diameter increment and stem diameter. The slow growth rates and low fruit yields indicate that more attention is required regarding the sustainability of there source and its ability to provide sufficient fruit for the growing subsistence and commercial demand at both local and national scales. This revised version was published online in June 2006 with corrections to the Cover Date.     

The grapevine aphid Aphis illinoisensis: a good example of recent invasion and rapid colonization by aphids

Aphis illinoisensis represents one of the most recent aphid invaders from the New World to the Mediterranean Region. This aphid, which is native to North America and is now widely distributed in Central and South America, was first found in Southern Turkey in 2002, and in 2005 it was also found in Crete (Greece). Thereafter it was recorded from Northern Cyprus, Israel, Tunisia, Algeria, Montenegro and Libya, and is now probably present throughout the Mediterranean. The present work provides data on the presence of this aphid in the Maltese islands, a group of low‐lying islands situated in the central Mediterranean Basin.