The effects of temperature and moisture on dark respiration in the foliose lichen Umbilicaria antarctica

The dark respiration of field‐fresh thalli of Umbilicaria antarctica Frey et Lamb is reported for temperatures from −5.5 to 19°C, and water contents from saturation to dryness. Detailed analysis of the respiratory response with changing water content has suggested that Michaelis‐Menten kinetics appear to provide a useful model. Q10 values are used to indicate possible ice formation in the thallus and water loss characteristics are explained in terms of thallus anatomy. The ecological implications of this approach are discussed

Moisture and temperature dependent changes in the cuticular permeability of the antarctic springtail Parisotoma octooculata (Willem)

This paper provides an introduction to the literature on the drying of porous solids and the relevance of these drying theories to the drying of Collembola in general, and hygrophilic Collembola in particular is discussed. The rate of drying of Parisotoma octooculata was highly dependent on both moisture content and temperature. Increasing the external drying temperature from 5 to 20°C, increased the cuticular conductance or permeability to water vapour from 15.8 to 72.0 mm/min; a change of 56.2 mm/min. Decreasing the moisture content from 3.5 to 2.0 g/g (grammes of water per gramme desiccated weight), whilst simultaneously increasing the temperature from 5 to 20°C, retarded the rate of transpiration. Moisture and temperature acted antagonistically to retard and promote transpiration in equal measure. The cuticular conductances to water vapour, of 16 species of Collembola from a wide range of habitats, were calculated using equivalent units, and then compared. There was a strong correlation between permeability and habitat type: the drier the habitat the lower the conductance value

The effects of temperature and moisture on CO2 uptake and total resistance to water loss in the antarctic foliose lichen Umbilicaria antarctica

Maximum net photosynthesis of field‐fresh thalli, illuminated at 200 μmol photons m−2 s−1 (PAR), was attained at 13 °C and 1.10 g g−1 water content. Small but significant rates of photosynthesis were measured at −5.5 °C. Depression of net photosynthesis at high thallus water contents is explained in terms of thallus anatomy. Calculation of evaporative resistance of the thallus by a new method showed a moisture‐dependent response pattern, and was in agreement with direct observations made on other foliose species

Water or ice? - the challenge for invertebrate cold survival

The ecophysiology of cold tolerance in many terrestrial invertebrate animals is based on water and its activity at low temperatures, affecting cell, tissue and whole organism functions. The normal body water content of invertebrates varies from 40 to 90% of their live weight, which is influenced by water in their immediate environment, especially in species with a water vapour permeable cuticle. Water gain from, or loss to, the surrounding atmosphere may affect animal survival, but under sub-zero conditions body water status becomes more critical for overwinter survival in many species. Water content influences the supercooling capacity of many insects and other arthropods. Trehalose is known to maintain membrane integrity during desiccation stress in several taxa. Dehydration affects potential ice nucleators by reducing or masking their activity and a desiccation protection strategy has been detected in some species. When water crystallises to ice in an animal it greatly influences the physiology of nearby cells, even if the cells remain unfrozen. A proportion of body water remains unfrozen in many cold hardened invertebrates when they are frozen, which allows basal metabolism to continue at a low level and aids recovery to normal function when thawing occurs. About 22% of total body water remains unfrozen from calculations using differential scanning calorimetry (compared with ca 19% in food materials). The ratio of unfrozen to frozen water components in insects is 1 : 4 (1 : 6 for foods). Such unfrozen water may aid recovery of freezing tolerant species after a freezing exposure. Rapid changes in cold hardiness of some arthropods may be brought about by subtle shifts in body water management. It is recognised that cold tolerance strategies of many invertebrates are related to desiccation resistance, and possibly to mechanisms inherent in insect diapause, but the role of water is fundamental to them all. Detailed experimental studies are needed to provide information which will allow a more complete and coherent understanding of the behaviour of water in biological systems and aid the cryopreservation of a wide range of biological material

Temperature preferences of the mite, Alaskozetes antarcticus, and the collembolan, Cryptopygus antarcticus from the maritime Antarctic

The thermal preferences of Alaskozetes antarcticus (Acari, Cryptostigmata) and Cryptopygus antarcticus (Collembola, Isotomidae) were investigated over 6 h within a temperature gradient (−3 to +13 °C), under 100% relative humidity (RH) conditions. After 10 days of acclimation at −2 or +11 °C, individual supercooling points (SCP) and thermopreferences were assessed, and compared with animals maintained for 10 days under fluctuating field conditions (−6 to +7 °C). Acclimation at −2 °C lowered the mean SCP of both A. antarcticus (−24.2 ± 9.1) and C. antarcticus (−14.7 ± 7.7) compared to field samples (−19.0 ± 9.0 and −10.7 ± 5.2, respectively). Acclimation at +11 °C increased A. antarcticus mean SCP values (−13.0 ± 8.5) relative to field samples, whereas those of C. antarcticus again decreased (−16.7 ± 9.1). Mites acclimated under field conditions or at +11 °C selected temperatures between −3 and +1 °C. After acclimation at −2 °C, both species preferred +1 to +5 °C. Cryptopygus antarcticus maintained under field conditions preferred +5 to +9 °C, whereas individuals acclimated at +11 °C selected +9 to +13 °C. For A. antarcticus, thermopreference was not influenced by its cold hardened state. The distribution of field specimens was further assessed within two combined temperature and humidity gradient systems: (i) 0–3 °C/12% RH, 3–6 °C/33% RH, 6–9 °C/75% RH and 9–12 °C/100% RH and (ii) 0–3 °C/100% RH, 3–6 °C/75% RH, 6–9 °C/33% RH and 9–12 °C/12% RH. In gradient (i), C. antarcticus distributed homogeneously, but, in gradient (ii), C. antarcticus preferred 0–3 °C/100% RH. Alaskozetes antarcticus selected temperatures between 0 and +6 °C regardless of RH conditions. Cryptopygus antarcticus appears better able than A. antarcticus to opportunistically utilize developmentally favourable thermal microclimates, when moisture availability is not restricted. The distribution of A. antarcticus appears more influenced by temperature, especially during regular freeze-thaw transitions, when this species may select low temperature microhabitats to maintain a cold-hardened state

First report of a multicenter prospective registry of cranioplasty in the United Kingdom and Ireland

Background: There are many questions that remain unanswered regarding outcomes following cranioplasty including the timing of cranioplasty following craniectomy as well as the material used. Objective: To establish and evaluate 30-d outcomes for all cranial reconstruction procedures in the United Kingdom (UK) and Ireland through a prospective multicenter cohort study. Methods: Patients undergoing cranioplasty insertion or revision between June 1, 2019 and November 30, 2019 in 25 neurosurgical units were included. Data collected include demographics, craniectomy date and indication, cranioplasty material and date, and 30-d outcome. Results: In total, 313 operations were included, consisting of 255 new cranioplasty insertions and 58 revisions. Of the new insertions, the most common indications for craniectomy were traumatic brain injury (n = 110, 43), cerebral infarct (n = 38, 15), and aneurysmal subarachnoid hemorrhage (n = 30, 12). The most common material was titanium (n = 163, 64). Median time to cranioplasty was 244 d (interquartile range 144-385), with 37 new insertions (15) within or equal to 90 d. In 30-d follow-up, there were no mortalities. There were 14 readmissions, with 10 patients sustaining a wound infection within 30 d (4). Of the 58 revisions, the most common reason was due to infection (n = 33, 59) and skin breakdown (n = 13, 23). In 41 (71) cases, the plate was removed during the revision surgery. Conclusion: This study is the largest prospective study of cranioplasty representing the first results from the UK Cranial Reconstruction Registry, a first national registry focused on cranioplasty with the potential to address outstanding research questions for this procedure. © 2021 Congress of Neurological Surgeons 2021