Publications by authors named "Joel Nichols"

Yield in many crops is affected by abscission during the early stages of fruitlet development. The reasons for fruitlet abscission are often unclear but they may include genetic factors because, in some crops, self-pollinated fruitlets are more likely to abscise than cross-pollinated fruitlets. Pollen parentage can also affect final fruit size and fruit quality.

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Tree crop yield is highly dependent on fertiliser inputs, which are often guided by the assessment of foliar nutrient levels. Traditional methods for nutrient analysis are time-consuming but hyperspectral imaging has potential for rapid nutrient assessment. Hyperspectral imaging has generally been performed using the adaxial surface of leaves although the predictive performance of spectral data has rarely been compared between adaxial and abaxial surfaces of tree leaves.

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Background And Aims: Pollen limitation is most prevalent among bee-pollinated plants, self-incompatible plants and tropical plants. However, we have very little understanding of the extent to which pollen limitation affects fruit set in mass-flowering trees despite tree crops accounting for at least 600 million tons of the 9200 million tons of annual global food production.

Methods: We determined the extent of pollen limitation in a bee-pollinated, partially self-incompatible, subtropical tree by hand cross-pollinating the majority of flowers on mass-flowering macadamia (Macadamia integrifolia) trees that produce about 200 000-400 000 flowers.

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Tree nuts play an important role in healthy diets, but their economic value and nutritional quality may be affected by their size and paternity. We assessed relationships between nut size and kernel recovery, the incidence of whole kernels, fatty acid composition and mineral nutrient concentrations in three macadamia cultivars, "Daddow", "816" and "A4". We determined to what extent differences in nut size and quality were the result of different levels of cross- or self-paternity.

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Premise Of The Study: (Sapindaceae) is an endangered rainforest tree known from only two populations. In this study, we identified polymorphic microsatellites, in silico, improving the effectiveness and efficiency of microsatellite development of nonmodel species. The development of genetic markers will support future conservation management of the species.

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While studies clearly point to a role for cortisol signaling in seawater adaptation, very little is known about salinity impact on glucocorticoid receptor (GR) expression in fish. To this end, we investigated the temporal GR expression in the gill and liver of rainbow trout (Oncorhynchus mykiss) to salinity exposure. Trout were subjected to gradual salinity increases (11 ppt for 1 d, 17 ppt for 2 d and 23 ppt for 2 d) over a five day period.

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To help extend the freshwater based biotic ligand model for silver (Ag) into brackish and saltwater conditions, 50g Gulf toadfish (Opsanus beta) were acclimated to 2.5%, 5%, 10%, 20%, 40%, 80%, or 100% salt water and exposed for 6d to 1.0microM AgNO(3), with or without 10mg C/L organic matter.

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To distinguish physiologically regulated uptake from passive uptake of inorganic Hg in fish, rainbow trout (Oncorhynchus mykiss) were exposed to inorganic Hg (0.5, 1, or 2 microM total Hg) in ion-poor water with various treatments. Addition of ions to the water (mM concentrations of Ca, K, Cl) did not consistently alter Hg accumulation by trout gills, although there was a trend to higher Hg accumulation at higher ion concentrations.

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In this study, we set out to examine the role of the somatotropic axis in the ion-regulation process in rainbow trout. Specifically, our objective was to examine whether plasma insulin-like growth factor-binding proteins (IGFBPs) are modulated by gradual salinity exposure. To this end, freshwater (FW)-adapted rainbow trout were subjected to gradual salinity increases, up to 66% seawater, over a period of 5 days.

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"Reconstructed" gill epithelia on filter supports were grown in primary culture from dispersed gill cells of freshwater rainbow trout (Oncorhynchus mykiss). This preparation contains both pavement cells and chloride cells, and after 7-9 days in culture, permits exposure of the apical surface to true freshwater while maintaining blood-like culture media on the basolateral surface, and exhibits a stable transepithelial resistance (TER) and transepithelial potential (TEP) under these conditions. These epithelia were used to develop a possible in vitro version of the biotic ligand model (BLM) for silver; the in vivo BLM uses short-term gill binding of the metal to predict acute silver toxicity as a function of freshwater chemistry.

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