ATP Content and Cell Viability as Indicators for Cryostress Across the Diversity of Life

Abstract

In many natural environments, organisms get exposed to low temperature and/or to strong temperature shifts. Also, standard preservation protocols for live cells or tissues involve ultradeep freezing in or above liquid nitrogen (-196°C or -150°C, respectively). To which extent these conditions cause cold- or cryostress has rarely been investigated systematically. Using ATP content as an indicator of the physiological state of cells, we found that representatives of bacteria, fungi, algae, plant tissue, as well as plant and human cell lines exhibited similar responses during freezing and thawing. Compared to optimum growth conditions, the cellular ATP content of most model organisms decreased significantly upon treatment with cryoprotectant and cooling to up to -196°C. After thawing and a longer period of regeneration, the initial ATP content was restored or even exceeded the initial ATP levels. To assess the implications of cellular ATP concentration for the physiology of cryostress, cell viability was determined in parallel using independent approaches. A significantly positive correlation of ATP content and viability was detected only in the cryosensitive algae Chlamydomonas reinhardtii SAG 11-32b and Chlorella variabilis NC64A, and in plant cell lines of Solanum tuberosum. When comparing mesophilic with psychrophilic bacteria of the same genera, and cryosensitive with cryotolerant algae, ATP levels of actively growing cells were generally higher in the psychrophilic and cryotolerant representatives. During exposure to ultralow temperatures, however, psychrophilic and cryotolerant species showed a decline in ATP content similar to their mesophilic or cryosensitive counterparts. Nevertheless, psychrophilic and cryotolerant species attained better culturability after freezing. Cellular ATP concentrations and viability measurements thus monitor different features of live cells during their exposure to ultralow temperatures and cryostress.

Hibernator-Derived Cells Show Superior Protection and Survival in Hypothermia Compared to Non-Hibernator Cells

“…Another mechanism present in cooled cells that may explain ferroptosis is the strong reduction in mitochondrial function. In turn, the observed mitochondrial failure leads to reduced ATP levels during hypothermia, as previously reported in a variety of non-hibernator species [17,32]. Because of this energy depletion, a plethora of energy demanding cellular functions are inhibited.…”

Assessment of Performance of Two Rapid Methods for On-Site Control of Microbial and Biofilm Contamination

“…For example, measurement of ATP luminescence is often employed for this purpose due to the presence of ATP molecules in every microorganism, but this is also the case of other cells present in food residues [14]. Additionally, microorganisms surviving a disinfection process can be stressed and have their ATP levels depleted [15], leading to underestimation of microorganism numbers when using this technique. Specific methods for detection of microorganisms, such as contact plates or swabbing provide information on the numbers of microorganisms recovered from the surfaces and, if selective media are used, they will also discriminate among different classes of microorganisms.…”

Rosiglitazone in the thawing medium improves mitochondrial function in stallion spermatozoa through regulating Akt phosphorylation and reduction of caspase 3

“…The cryopreserved spermatozoa show impaired mitochondrial activity due to oxidative stress and the osmotic damage that occurs during thawing [20–23]; further, cryopreserved spermatozoa present diminished mitochondrial oxygen consumption [24]. This damage compromises the capability of thawed stallion spermatozoa to produce ATP through oxidative phosphorylation [15, 25, 26]. Thus, the cryopreserved spermatozoa have lower motility and lower ATP content compromising their functionality and finally their fertilizing ability.…”