Microbiome of the Queensland Fruit Fly through Metamorphosis

Bactrocera tryoni (Froggatt) (Queensland fruit fly, or “Qfly”) is a highly polyphagous tephritid fruit fly and a serious economic pest in Australia. Qfly biology is intimately linked to the bacteria and fungi of its microbiome. While there are numerous studies of the microbiome in larvae and adults, the transition of the microbiome through the pupal stage remains unknown. To address this knowledge gap, we used high-throughput Next-Generation Sequencing (NGS) to examine microbial communities at each developmental stage in the Qfly life cycle, targeting the bacterial 16S rRNA and fungal ITS regions. We found that microbial communities were similar at the larval and pupal stage and were also similar between adult males and females, yet there were marked differences between the larval and adult stages. Specific bacterial and fungal taxa are present in the larvae and adults (fed hydrolyzed yeast with sugar) which is likely related to differences in nutritional biology of these life stages. We observed a significant abundance of the Acetobacteraceae at the family level, both in the larval and pupal stages. Conversely, Enterobacteriaceae was highly abundant (>80%) only in the adults. The majority of fungal taxa present in Qfly were yeasts or yeast-like fungi. In addition to elucidating changes in the microbiome through developmental stages, this study characterizes the Qfly microbiome present at the establishment of laboratory colonies as they enter the domestication process.

Potassium and nitrogen poising: Physiological changes and biomass gains in rice and barley

Britto, D. T., Balkos, K. D., Becker, A., Coskun, D., Huynh, W. Q. and Kronzucker, H. J. 2014. Potassium and nitrogen poising: Physiological changes and biomass gains in rice and barley. Can. J. Plant Sci. 94: 1085–1089. Soil nitrogen, potassium, and water are three of the most important factors influencing, often interdependently, the growth of plants. Maximizing plant growth is not simply a matter of maximizing the availability of these and other nutrients; indeed, excess supply can be deleterious to plant performance. Rather, optimal performance may come about by adjusting the supply of each of the disparate factors required for plant growth, not only individually, but in relation to one another. In our work investigating the nutritional maximization of plant growth, we have found that altering the ratios of N and K provided to seedlings of cereal grasses can result in very substantial increases in vegetative biomass accrual, e.g., >220% of low-K+ controls, in short-term studies with rice, the world's most important cereal grain, and even greater gains in grain yield, in the longer term. Hence, the findings in our laboratory are of direct relevance to the aim of NSERC's Green Crop Network, which was to contribute to the amelioration of climate change by improvement of carbon capture and sequestration in crop plants. In addition, these findings may help to increase the world's food supply, the security of which is sometimes at odds with proposed means to thwart climate change. Our work in this area has also led to a potential breakthrough of a more fundamental sort in plant nutritional biology, which may in itself have important practical implications: evidence that aquaporin-type transport proteins conduct rapid NH3 fluxes into roots at toxic levels of external ammonia/ammonium.

Perspectives

This concluding chapter looks at some of the big issues that remain in nutritional biology. Exploding protein into its constituent amino acids means having to deal with 19 extra dimensions, which is fine in theory but daunting in practice. However, such an expansion is what will be needed to understand the mechanisms of protein appetite, the role of protein in aging, obesity, and immune function, or the behavioral and metabolic consequences of replacing marine-based animal proteins with plant-derived alternatives in the diets of farmed fish. The next step will be to associate primary response variables such as life span, disease susceptibility, and fecundity with associated physiological, metabolic, and geometric responses. Other issues include nutritional epigenetics and early-life prevention of metabolic disease, human obesity, nutritional immunology, and modeling nutritional interactions.

Morphometric data on the intestines of five Australian marsupials (Marsupialia).

THE nutritional biology of marsupials has been a subject of numerous studies, culminating in valuable compilations covering a wide range of aspects (Osman Hill and Rewell 1954; Walton and Richardson 1989; Hume 1982, 1999; Kerle 2001). Despite this thorough coverage, there remains a scarcity of morphometric data on the intestines of monotremes and marsupials. In an attempt to approach this need, an effort was initiated to provide morphometric data on monotremes (Snipes et al. 2002) and marsupials (Snipes et al. 1993, 2003).