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Molecular chaperones are synthesized and accumulated under a variety of unfavorable conditions in all organisms. Heat shock protein 90 (Hsp90) and Hsp60, which are classified into the major classes of molecular chaperones, play important roles in cellular stress responses. In this study, we characterized sterile Ulva pertusa Hsp90 ( UpHsp90) and UpHsp60 genes which may be involved in tolerance to thermal and heavy metal stresses in this alga. The UpHsp90 cDNA consisting of 2,118 nucleotides encoded a polypeptide of 705 amino acids (AA). On the other hand, the UpHsp60 cDNA consisting of 1,722 nucleotides encoded a protein whose predicted length was 573 AA. The AA sequence alignment and phylogenetic analyses showed that the UpHsp90 and UpHsp60 proteins were more similar to cytoplasmic Hsp90s and mitochondrial Hsp60s, respectively, than to other types of the respective Hsps. Southern blot analysis indicated that the sterile U. pertusa genome had at least two cytoplasmic Hsp90-encoding genes and two mitochondrial Hsp60-encoding genes. The UpHsp90 and UpHsp60 mRNA levels were significantly affected by diurnal and temperature changes, and slightly affected by exposure to heavy metals. These results suggest that UpHsp90 and UpHsp60 genes play particularly important roles in adaptation to diurnal and temperature changes. [ABSTRACT FROM AUTHOR]

Discusses a study conducted by researchers in Japan, which found that the sterile Ulva pertusa exposed to hypersaline conditions accumulated an organic osmolytes proline such as other green macroalgae. Preparation of seawater media of low and high salinities by diluting natural seawater; Investigation of the changes in the chemical components such as photosynthetic pigments, free amino acids and total carbon and nitrogen in thalli exposed to extreme low and high salinities.

Characterizes complementary DNA clone encoding glutamate dehydrogenase in green alga, Ulva pertusa. Amino acid sequence; Nucleotide sequence; Expression of messenger RNA; Tissue distribution.

The potential use of deep seawater (DSW) for the cultivation of macroalgae was evaluated by analysis of the growth rate of thalli (by surface area), photosynthetic pigment content, and total free amino acid content of sterile Ulva pertusa cultured in the control medium (one-fifth strength Provasoli's enriched seawater (PES) medium), surface seawater (SSW) medium and also seawater medium collected from 400 m depth (400-DSW) and 1,200 m depth (1,200-DSW). The growth rate of the sterile U. pertusa grown in 400-DSW and 1,200-DSW was similar to that of thalli cultured in the one-fifth strength PES medium that had previously been shown to be the optimum concentration for the cultivation of Ulva. Photosynthetic pigment content in the control medium, 400-DSW- and 1,200-DSW-cultured thalli was 1.7-2.0 times higher than that of the SSW-cultured thalli. The total free amino acids content of the control medium and SSW-cultivated thalli was 264 ± 64 and 120 ± 39 mg per 100 g dry weight, whereas the 400-DSW- and 1,200-DSW-cultivated thalli had significantly more amino acids (342 ± 69-327 ± 64 mg per 100 g dry weight). The results of this study indicate that DSW has a high potential for cultivation of edible macroalgae without any supply of extra nutrient until it grows to harvest size. [ABSTRACT FROM AUTHOR]