Nitrogen phytoremediation by water hyacinth (Eichhornia crassipes (Mart.) Solms)

The phytoremediation potential of water hyacinth, Eichhornia crassipes (Mart.) Solms, was examined in two independent studies under nitrogen (N) rates of 0, 40, 80, 100, 150, 200, and 300 ppm. A modified Hoagland solution was added to ponds containing water hyacinths which were rated and measured weekly for 4 weeks. The hyacinths accounted for 60¿85% of the N removed from solution. Net productivity, as measured by dry matter gain, increased with an increase in N rate until 80 ppm. Above that level dry matter productivity was similar. Tissue N increased linearly with dry matter gain, but total nitrogen removal from the water increased exponentially with net dry matter gain or with an increase in canopy cover. The relation between total N in plant tissue and N removal from the water was similar for the two experiments

Development of guidelines for using bioextraction technologies to manage nutrients in New Hampshire\u27s estuarine waters

There is growing literature on bioextraction approaches to managing nutrients in coastal waters, and it includes studies using a variety of species. Bivalve mollusks and macroalgae have received the most attention for several reasons, but perhaps foremost because of their aquaculture potential. A December 2009 workshop at the University of Connecticut, which included speakers from several countries, indicated overall that although bioextraction approaches hold substantial potential there are still many unanswered questions. The present review takes a “what we know/what we need to know” perspective, and focuses on aquaculture. For some taxa (e.g., eastern oyster), wild populations occur in New Hampshire which provide substantial nutrient bioextraction. The associated processes that result in nutrient removal from the ecosystem, however, are generally more complicated and much more difficult to unambiguously quantify except when actual harvest data are available. Therefore, the present review focuses on aquaculture, and it is restricted to those taxa (plants and animals) that occur in New Hampshire. It should be noted that the present project is associated with a recently completed project (funded by the Piscataqua Region Estuaries Partnership [PREP]) consisting of a field experiment designed to provide empirical data on nutrient uptake by oysters. The final report for this project represents the starting point for future research that will more completely characterize the bioextraction potential for oysters in New Hampshire (see discussion of Grizzle and Ward 2011 below)

The lady vanishes: what's missing from the stem cell debate

Most opponents of somatic cell nuclear transfer and embryonic stem cell technologies base their arguments on the twin assertions that the embryo is either a human being or a potential human being, and that it is wrong to destroy a human being or potential human being in order to produce stem cell lines. Proponents’ justifications of stem cell research are more varied, but not enough to escape the charge of obsession with the status of the embryo. What unites the two warring sides in ‘the stem cell wars’ is that women are equally invisible to both: ‘the lady vanishes’. Yet the only legitimate property in the body is that which women possess in their reproductive tissue and the products of their reproductive labour. By drawing on the accepted characterisation in law of property as a bundle of rights, and on a Hegelian model of contract as mutual recognition, we can lessen the impact of the tendency to regard women and their eggs as merely receptacles and women’s reproductive labour as unimportant

Most Asked Agronomic Questions

Exact date of bulletin unknown.PDF pages: 4

Spots & stripes: pleomorphic patterning of stem cells via p-ERK-depenendent cell chemotaxis shown by feather morphogenesis & mathematical simulation

A key issue in stem cell biology is the differentiation of homogeneous stem cells towards different fates which are also organized into desired configurations. Little is known about the mechanisms underlying the process of periodic patterning. Feather explants offer a fundamental and testable model in which multi-potential cells are organized into hexagonally arranged primordia and the spacing between primordia. Previous work explored roles of a Turing reaction–diffusion mechanism in establishing chemical patterns. Here we show that a continuum of feather patterns, ranging from stripes to spots, can be obtained when the level of p-ERK activity is adjusted with chemical inhibitors. The patterns are dose-dependent, tissue stage-dependent, and irreversible. Analyses show that ERK activity-dependent mesenchymal cell chemotaxis is essential for converting micro-signaling centers into stable feather primordia. A mathematical model based on short-range activation, long-range inhibition, and cell chemotaxis is developed and shown to simulate observed experimental results. This generic cell behavior model can be applied to model stem cell patterning behavior at large

Pathophysiological aspects of the problem of prolonged hypokinesia

The changes in man's acitivity due to modern life with automation and sedentary activities and man's exploration of space in a state of weightlessness have accentuated the importance of hypokinesia. The pathogenesis of hypokinesia is discussed. Experiments and results made on man and animals are included