Carbonic anhydrases (CA; EC 4.2.1.1) play a vital role in dissolved inorganic carbon (DIC) transport to photosynthetic microalgae residing in symbiotic cnidarians. The temperate sea anemone Anthopleura elegantissima can occur in three symbiotic states: hosting Breviolum muscatinei (brown), hosting Elliptochloris marina (green) or without algal symbionts (aposymbiotic). This provides a basis for A. elegantissima to be a model for detailed studies of the role of CA in DIC transport. This study investigated the effects of symbiosis, body size and light on CA activity and expression, and suggests that A. elegantissima has a heterotrophy-dominated trophic strategy. We identified putative A. elegantissima CA genes and performed phylogenetic analyses to infer subcellular localization in anemones. We performed experiments on field-collected anemones to compare: (1) CA activity and expression from anemones in different symbiotic states, (2) CA activity in brown anemones as a function of size, and (3) CA activity in anemones of different symbiotic states that were exposed to different light intensities. CA activity in brown anemones was highest, whereas activity in green and aposymbiotic anemones was low. Several CAs had expression patterns that mirrored activity, while another had expression that was inversely correlated with activity, suggesting that symbionts may induce different DIC transport pathways. Finally, CA activity was inversely correlated with anemone size. Our results suggest that the observed CA activity and expression patterns are affected not only by symbiosis, but also by other factors in the host physiology, including trophic strategy as it relates to body size and cellular pH homeostasis.

Hydractinia symbiolongicarpus is an emerging model organism in which cutting-edge genomic tools and resources are being developed for use in a growing number of research fields. One limitation of this model system is the lack of long-term storage for genetic resources. The goal of this study was to establish a generalizable cryopreservation approach for Hydractinia that would support future repository development for other cnidarian species. Specific objectives were to: (1) characterize basic parameters related to sperm quality; (2) develop a generalizable approach for sperm collection; (3) assess the feasibility of in vitro fertilization (IVF) with sperm after refrigerated storage; (4) assess the feasibility of IVF with sperm cryopreserved with various sperm concentrations; (5) evaluate feasibility of cryopreservation with various freezing conditions, and (6) explore the feasibility of cryopreservation by use of a 3-D printed open-hardware (CryoKit) device. Animal husbandry and sperm collection were facilitated by use of 3-D printed open hardware. Hydractinia sperm at a concentration of 2 × 107 cells/mL stored at 4 °C for 6 d were able to achieve 50% fertilization rate. It appeared that relatively higher sperm concentration (>5 × 107 cells/mL) for cryopreservation could promote fertilization. A fertilization rate of 41–69% was observed using sperm equilibrated with 5, 10, or 15% (v/v) cryoprotectant (dimethyl sulfoxide or methanol) for 20 min, cooled at a rate of 5, 10, or 20 °C/min from 4 °C to −80 °C, at a cell concentration of 108/mL, in 0.25 mL French straws. Samples cryopreserved with the CryoKit produced a fertilization rate of 72–82%. Establishing repository capabilities for the Hydractinia research community will be essential for future development, maintenance, protection, and distribution of genetic resources. More broadly, these generalizable approaches can be used as a model to develop germplasm repositories for other cnidarian species.

Photothermal radiometry is being used e.g. for characterization of changes in the microstructure of metals. It is non-destructive, non-contact and much faster than a metallographic analysis. However, this method uses only one detector element, therefore the inspection of areas requires time-consuming scanning. In this paper, we will show that infrared cameras can be used for detection as well. With an exact synchronization between the excitation laser and the IR image grabbing, reproducible phase contrast values can be obtained, thus converting photothermal radiometry into an imaging method. This is demonstrated on samples with different case hardening depths and grinding burn respectively.

Carbonic anhydrase (CA) is an enzyme which catalyzes the interconversion of bicarbonate ions (HCO 3-) and carbon dioxide (CO 2). The activity levels of CA can be measured by taking advantage of the chemical reaction that it catalyzes. When CO 2 is added to a tissue homogenate, the CA present converts the CO 2 into HCO 3 and a hydrogen ion (H +), which results in a decrease in pH. The rate at which the pH drops can be measured and converted into a CA activity mesaure. If there is no CA activity, the pH level decreases slowly and if there is a high CA activity, the pH decreases quickly.

Carbonic anhydrase (CA) is an enzyme which catalyzes the interconversion of bicarbonate ions (HCO3-) and carbon dioxide (CO2). The activity levels of CA can be measured by taking advantage of the chemical reaction that it catalyzes. When CO2 is added to a tissue homogenate, the CA present converts the CO2 into HCO3- and a hydrogen ion (H+), which results in a decrease in pH. The rate at which the pH drops can be measured and converted into a CA activity mesaure. If there is no CA activity, the pH level decreases slowly and if there is a high CA activity, the pH decreases quickly.