Calculation of protoplast freezing strain in multicellular plant tissues

A method for calculating the contraction strain (or the converse stress) to protoplasts of frozen multicellular plant tissues is described. The method requires (i) a nuclear magnetic resonance (NMR) measure of the quantity of bound water per gram dry weight (K), (ii) a gravimetric measure of grams of H₂O per gram dry weight (L₀), (iii) a measure of solute concentration in non-frozen cells (C₀), (iv) an estimate of the specific volume of tissue dry matter (0.625 ml/g), (v) an NMR measure of the fraction of tissue water that is intracellular osmotic water (P_a), and (vi) a measure of the fraction of the dry weight that is cell wall (f_cw). This method is a refinement of previous methods that calculate cell contraction strain from four (L₀, K, C₀, and 0.625) of the above six measurements. Comparison of the calculated protoplast strain to the calculated cell strain indicates that the two measures are quite similar, however, the measure of protoplast strain is, in theory, a more appropriate measure of the freezing strain. It is also demonstrated that derivation of a measure of strain from the parameters controlling it is useful, because it allows one to evaluate the relative contribution of each parameter in preventing the development of strain.     

Correction to: Deceived,but not betrayed: static allometry suggests female ornaments in the long‑tailed dance fly (Rhamphomyia longicauda) exaggerate condition to males

Evolutionary Ecology -     

Possible role of transient electric fields in freezing-induced membrane destabilization

Summary Evidence is presented to support the hypothesis that electrical potentials generated during the freezing of aqueous solutions (the Workman-Reynolds effect) may contribute to the destabilization of the plasma membrane and cryoinjury of isolated protoplasts. Specifically. (1) electric potential diffrences of sufficient magnitude to cause lysis of the plasma membrane occur during the rapid freezing of isolated protoplasts suspended in sorbitol: (2) survival of protoplasts is inversely correlated with the magnitude of the potential difference and (3) cold acclimation increases the stability of the plasma membrane to applied electric fields. A discussion is given of the different physical phenomena though to be involved in the Workman-Reynolds effect. The basis equations for these phenomena are outlined.     

Toward a New Generation of Environmental Technology: The Need For Legislative Reform

Given near unanimity in the environmental and industrial communities about the need for a new generation of environmental technology, the policy process unfortunately lags behind in moving toward this objective. This article examines causes and remedies for this gap in the context of American environmental policy. U.S. environmental laws continue to be pervaded by structural biases against new technology, and the complexity of their administration exacerbates the problem. Within the last few years, several important reform initiatives have arisen from inside the regulatory community; however, these can only go so far, given the current statutory framework Congress, too long quiescent, needs to become involved. A legislative reform package is proposed consisting of four main elements: a legislative mandate that makes promotion of technological innovation an explicit environmental objective; elimination of structural features in current law that impede innovation; creation of a new framework for standard-setting and enforcement that puts every firm on a trajectory toward environmental and technological improvement; and enlisting regulation as a "demand-pull" for environmentally superior technology.