Non-cooperative immobilization of residual water bound in lyophilized photosynthetic lamellae

Abstract

This study applied 1H-NMR in time and in frequency domain measurements to monitor the changes that occur in bound water dynamics at decreased temperature and with increased hydration level in lyophilizates of native wheat photosynthetic lamellae and in photosynthetic lamellae reconstituted from lyophilizate. Proton relaxometry (measured as free induction decay = FID) distinguishes a Gaussian component S within the NMR signal (o). This comes from protons of the solid matrix of the lamellae and consists of (i) an exponentially decaying contribution L1 from mobile membrane protons, presumably from lipids, and from water that is tightly bound to the membrane surface and thus restricted in mobility; and (ii) an exponentially decaying component L2 from more mobile, loosely bound water pool. Both proton relaxometry data and proton spectroscopy show that dry lyophilizate incubated in dry air, i.e., at a relative humidity (p/p0) of 0% reveals a relatively high hydration level. The observed liquid signal most likely originates from mobile membrane protons and a tightly bound water fraction that is sealed in pores of dry lyophilizate and thus restricted in mobility. The estimations suggest that the amount of sealed water does not exceed the value characteristic for the main hydration shell of a phospholipid. Proton spectra collected for dry lyophilizate of photosynthetic lamellae show a continuous decrease in the liquid signal component without a distinct freezing transition when it is cooled down to -60ºC, which is significantly lower than the homogeneous ice nucleation temperature [Bronshteyn, V.L. et al. Biophys. J. 65 (1993) 1853].

Rehydration of the sleeping chironomid, Polypedilum vanderplanki Hinton, 1951 larvae from cryptobiotic state up to full physiological hydration (Diptera: Chironomidae)

“…Antarctic lichenized fungi 55 – 57 . The observed mobile proton signal may be assigned to residual water 54 bound in dry larva, and/or to lipids mainly localized in larva fat bodies.…”

“…The 1 H-NMR immobilized proton signal component coming from the tissues of anhydrobiotic larva does not differ much from the one detected for other microheterogenous solids, and particularly, for other deeply dehydrated biological systems, eg. DNA-surfactant complexes 53 , photosynthetic membranes 54 , or for anhydrobiotic living organisms, e.g. Antarctic lichenized fungi 55 – 57 .…”

“…The cuticle forming outer integument of Insecta body is varied in internal structure and provides a very solid, efficient and lightweight skeleton and prevents the organs from environmental stresses, among them desiccation shock and decreased temperature (e.g. 54 , 58 – 61 ). Insect cuticle plays also important role in controlling water level in the insect body, especially for water insects in liquid permeability, although water into it inside the body can also be taken up through the rectum against large concentration gradients or by the mouth, anal opening, as well as with food (e.g.…”

A comparative analysis of gaseous phase hydration properties of two lichenized fungi: Niebla tigrina (Follman) Rundel & Bowler from Atacama Desert and Umbilicaria antarctica Frey & I. M. Lamb from Robert Island, Southern Shetlands Archipelago, maritime Antarctica

“…Slowly decaying signal coming from mobile protons is fitted by a superposition of two exponential function indicating that the two fractions of mobile protons may be distinguished. The signal from less mobile proton fraction, L 1 , component with T 2L1 * ≈ 100 μs may be connected partially with lipids, and partially with tightly bound water fraction (Harańczyk et al 2015), and is detected in many other extremely dry biological systems (Harańczyk et al 1999(Harańczyk et al , 2008(Harańczyk et al , 2009(Harańczyk et al , 2012ab, c).…”

“…Among them are 1 H-NMR relaxometry, 1 H-NMR spectroscopy, and sorption isotherm analysis. They allow the analysis of molecular dynamics of water molecules and differentiation of several fractions of residual water present in a cryptobiotic organism (in dehydrated lichenized fungi) (Harańczyk et al 2006(Harańczyk et al , 2008(Harańczyk et al , 2009(Harańczyk et al , 2012b, in freeze dried photosynthetic membranes (Harańczyk et al 2015), or in other extremely dry biological systems like DNA-based conducting polymers (Nizioł et al 2015).…”