A Comparison of the Energy Yield at the End User for M. x giganteus Using Two Different Harvesting and Transport Systems

A comparison between two different harvest systems for Miscanthus x giganteus crop (direct cut/chip and mow/bale) in terms of the net energy delivered to an end user, and the various energy costs and energy yields associated with each system was conducted. Only minor differences in terms of energy consumption were observed between the two harvest systems when all phases of the harvesting chain had been taken into account. Chip harvesting consumed 0.11 GJ?t^?1 compared with 0.13 GJ?t^?1 for bale harvesting. Chip transportation was considerably more expensive than bale transportation for a set distance of 50 km (0.18 and 0.11 GJ?t^?1 for chip and bale, respectively). Despite this, higher overall net energy yield was achieved by direct cutting and chipping the material. This was due to the higher proportion of harvestable energy lost in the field as a result of the use of a mowing/baling system. The overall net energy delivered in terms of harvestable material by the direct cut and chip system was 12.45 GJ?t^–1 compared with 11.78 GJ?t^?1 by the mow and bale system, making direct cut the more efficient system even up to a transport distance of 400 km. A sensitivity analysis indicated that the choice of transport system becomes more important for energy efficiency as transport distance increases.     

Ecosystem-Service Tradeoffs Associated with Switching from Annual to Perennial Energy Crops in Riparian Zones of the US Midwest

Integration of energy crops into agricultural landscapes could promote sustainability if they are placed in ways that foster multiple ecosystem services and mitigate ecosystem disservices from existing crops. We conducted a modeling study to investigate how replacing annual energy crops with perennial energy crops along Wisconsin waterways could affect a variety of provisioning and regulating ecosystem services. We found that a switch from continuous corn production to perennial-grass production decreased annual income provisioning by 75%, although it increased annual energy provisioning by 33%, decreased annual phosphorous loading to surface water by 29%, increased below-ground carbon sequestration by 30%, decreased annual nitrous oxide emissions by 84%, increased an index of pollinator abundance by an average of 11%, and increased an index of biocontrol potential by an average of 6%. We expressed the tradeoffs between income provisioning and other ecosystem services as benefit-cost ratios. Benefit-cost ratios averaged 12.06 GJ of additional net energy, 0.84 kg of avoided phosphorus pollution, 18.97 Mg of sequestered carbon, and 1.99 kg of avoided nitrous oxide emissions for every $1,000 reduction in income. These ratios varied spatially, from 2- to 70-fold depending on the ecosystem service. Benefit-cost ratios for different ecosystem services were generally correlated within watersheds, suggesting the presence of hotspots – watersheds where increases in multiple ecosystem services would come at lower-than-average opportunity costs. When assessing the monetary value of ecosystem services relative to existing conservation programs and environmental markets, the overall value of enhanced services associated with adoption of perennial energy crops was far lower than the opportunity cost. However, when we monitized services using estimates for the social costs of pollution, the value of enhanced services far exceeded the opportunity cost. This disparity between recoverable costs and social value represents a fundamental challenge to expansion of perennial energy crops and sustainable agricultural landscapes.     

The effect of harvest date and harvest method on the combustion characteristics of Miscanthus × giganteus

Miscanthus × giganteus is an energy crop with many attributes that make it a potential biofuel feedstock. This study examined the chemical composition of M. × giganteus stems cut at different dates throughout the spring harvest window (January, February and March) and either left in a swath or left flat in a thin layer on the ground and compared the composition to that of the standing crop collected on the same date in April (control). The research then examined the effect of cutting date on the chemical composition of whole plant M. × giganteus biomass (leaf and stem). The parameters examined in both parts of this experiment were lower heating value on a wet basis (LHV_WB), ash, chlorine, potassium, nitrogen, sulphur, carbon and hydrogen content. The range of values recorded for the parameters from both aspects of this trial were LHV_WB 4.84–11.87 MJ kg^?1; ash 1.44–1.97%; Cl 0.07–0.23%; K 0.15–0.32%; N 0.28–0.39%; S 0.13–0.19%; C 46.75–50.00%; H 5.76–6.09%. The length of time that the M. × giganteus remained in the field after cutting affected the LHV_WB (increased with time) of the stem biomass material. Cutting the biomass and leaving it in the field lowered the ash, Cl and C content of the stem material compared to that of the control which was cut and collected on the same date. No differences were observed for the other parameters. Date of harvest affected the LHV_WB, Cl and C content which all improved with later cutting dates. Thus, combustion quality can be improved by delaying the harvest date or by cutting the crop and leaving it in the field for a period prior to collection. Choosing the correct combination of time and harvest method can therefore improve biomass fuel quality.     

Application of morphometric techniques to postnatal rat testes in organ culture: insights into testis growth

The extent of Sertoli cell proliferation during fetal and neonatal development determines the final adult testis size and potential for sperm output. To gain further knowledge of the factors that regulate Sertoli cell proliferation, the present study used a new approach to analyse changes in morphology and proliferation in the postnatal testis by combining organ culture with morphometric analysis. Fragments of rat testes from days 0 to 10 postpartum were cultured in contact with DMEM for 6 h or 72 h and fixed. The effects of ovine follicle-stimulating hormone (FSH) and activin were studied in an additional 72-h organ culture experiment using day 9 testes. Bromodeoxyuridine (BrdU) was added for the last 6 h of culture to mark proliferating cells. Two-microm sections of the fragments were analysed for morphological changes of the seminiferous cords, and the proportion of BrdU-labelled Sertoli and germ cells was determined. Assessment of 6-h samples revealed growth characteristics consistent with those observed in vivo during days 1-10 of postnatal development. From day 2 onwards, the volume fraction of seminiferous cords began to increase, while significant growth in cross-sectional area of the cords occurred only after day 6. In these culture conditions, germ cell proliferation and testicular architecture was consistent with that expected for the age of the tissue at time of explant. The proportion of dividing Sertoli cells declined from 15-20% at days 0-4 postpartum to below % at day 10 postpartum in the 6-h culture, and it was low or abolished in the 3-day culture at all time points. Activin and FSH together, but not singly, stimulated Sertoli cell proliferation in the 72-h culture. This paper presents a new approach to analysis of in vitro testis development. The combination of fragment culture and stereological analysis permits rigorous and detailed assessment of developmental changes in the postnatal testis.     

Cloning and developmental expression of MARK/Par-1/MELK-related protein kinase xMAK-V in<Emphasis Type="Italic"> Xenopus laevis</Emphasis>

MAK-V/Hunk is a recently identified MARK/Par-1-related mammalian protein kinase. Although the precise function of this protein kinase is yet to be established, available data suggest its involvement in animals development and in the physiology of the nervous system. Here we report characterization of a cDNA encoding Xenopus laevis orthologue of MAK-V/Hunk protein kinase, xMAK-V. The in silico analysis also revealed MAK-V/Hunk orthologues in the fish Fugu rubripes and primitive chordate Ciona intestinalis but not in invertebrate species such as Drosophila melanogaster and Caenorhabditis elegans, suggesting that MAK-V/Hunk is a chordate-specific protein kinase. The expression of xmak-v in X. laevis embryos was analyzed using whole-mount in situ hybridization. Expression of xmak-v has been detected in all developmental stages studied including maternal expression in unfertilized eggs. The xmak-v mRNA has a predominant occurrence on the animal hemisphere of the egg, and this pattern of expression is sustained throughout cleavage and blastula stages. At the gastrula stage xmak-v expression is restricted to the ectoderm. In the later stage embryos xmak-v is expressed over the entire embryonic surface including the open neural plate at stage 15 and also in neural tube at stage 22. At tadpole stage xmak-v expression is strong in embryonic epidermis, nervous system and sensory organs, and is also obvious in perisomitic mesoderm and brachial arches.Edited by N. Satoh     

Estimating the latitudinal origins of migratory birds using hydrogen and sulfur stable isotopes in feathers: influence of marine prey base

Hydrogen stable isotope analysis of feathers is an important tool for estimating the natal or breeding latitudes of nearctic-neotropical migratory birds. This method is based on the latitudinal variation of hydrogen stable isotope ratios in precipitation in North America (deltaD(p)) and the inheritance of this variation in newly formed feathers (deltaD(f)). We hypothesized that the typically strong relationship between deltaD(p) and deltaD(f) would be decoupled in birds that forage in marine food webs because marine waters have relatively high deltaD values compared to deltaD values for local precipitation. Birds that forage on marine prey bases should also have feathers with high delta(34)S values, since delta(34)S values for marine sulfate are generally higher than delta(34)S values in terrestrial systems. To examine this potential marine effect on feather stable isotope ratios, we measured deltaD and delta(34)S in the feathers of nine different species of raptors from both inland and coastal locations across North America. Feathers from coastal bird-eating raptors had consistently higher deltaD and delta(34)S values than feathers from inland birds. Birds that had high delta(34)S values also deviated strongly from the typical relationship between deltaD(p) and deltaD(f). We recommend measuring both sulfur and hydrogen stable isotope ratios in feathers when some members of a migrant population could potentially forage in marine habitats. We suggest using a practical cutoff of delta(34)S >10 per thousand to remove marine-foraging birds from a migrant sample when using stable isotopes of hydrogen to estimate the latitudinal origins of migrants because high deltaD(f) values for marine-foraging birds could potentially distort estimates of origins.