Effects of dissolved oxygen levels on survival and growth in vitro of Haliclona pigmentifera (Demospongiae).
In vitro sponge cultures are considered as legitimate alternatives for utilizing marine sponges (Porifera) to yield bioactive molecules. Optimization of culture methodologies for enhancing sponge survival is in progress for the identification of the factors regulating sponge survival in vitro. Dissolved oxygen (DO) is an essential factor promoting sponge survival. However, the effects of variable DO levels on the in vitro survival responses of sponges are not fully understood. Hence, we have investigated the effects of variable DO levels on the survival of the marine sponge, Haliclona pigmentifera (Demospongiae), with no external nutritional supplementation in closed type incubator chambers. Our results indicate that, under hypoxic conditions (1.5-2.0 ppm DO), H. pigmentifera with intact ectodermal layers and subtle oscula show adherent growth for 42+/-3 days. Sponges with prominent oscula, foreign material, and damaged pinacoderm exhibit poor survival under similar conditions. Complete mortality occurs within 2 days under anoxia (<0.3 ppm DO), and survival for a few days has been observed at >4.0 ppm DO without adhesion. Cellular differences between the outer and inner zones and collagen-like extracellular matrix have been identified in adherent sponges. Based on the hypothesis that hypoxia-inducible factor1-alpha (HIF-1alpha) is a ubiquitous protein promoting hypoxic survival in animals, we have detected, by Western blot, a protein band corresponding to human HIF-1alpha-like protein from sponges exposed to hypoxia and to hypoxia-mimicking agents. We thus report, for the first time, adhesive growth and a protein band corresponding to human HIF-1alpha-like protein in sponges surviving hypoxia in vitro.
Gunda
Venu Gopal
VG
Toxicology Unit, Biology Division, Indian Institute of Chemical Technology, Hyderabad, India.
Janapala
Venkateswara Rao
VR
D000818:Animals; D015153:Blotting, Western; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D047129:Haliclona / Q000254:growth & development / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010100:Oxygen / Q000502:physiology*; D016019:Survival Analysis
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010100:Oxygen