The induction of reproductive cell formation of Ulva pertusa Kjellman (Ulvales, Ulvophyceae)

Abstract

Synchronous zooid formation in Uiva pertusa Kjellman was induced in excised disks maintained in sterilized seawater at 20X, 12:12 h L: D cycle and fluorescent light at 100 |xmol photons m ^ S"^ Zooids were reieased from mature disk tissue on the morning of the second or the third day after excision. The degree of zooid formation was found to be dependent on disk size and the region of the mother thalius from which the disk tissue was excised. Zooid formation was induced in more than 90% of small disks (0.9 mm in diameter) which were taken from the margins of the Uiva thalii. When disks were incubated together with a perforated mother thalius, the disks remained sterile. The presence of maturation inhibitors in vegetative thalli is suggested.

Differential response of varying salinity and temperature on zoospore induction, regeneration and daily growth rate in Ulva fasciata (Chlorophyta, Ulvales)

“…The induction of reproductive cells also has been reported to occur on the second or third day in U. pertusa at 20°C and 100 μmol photons m -2 s -1 with a 12: 12 light: dark cycle (Hiraoka and Enomoto 1998) (Hiraoka et al 2003). The quadriflagellate zoospores encountered in our study also have been reported in many green seaweeds including U. pertusa (Hiraoka and Enomoto 1998), U. spinulosa (Hiraoka et al 2003), U. fenestrata (Kalita and Tytlianov 2003) and Gayralia spp. (Pellizzari et al 2008).…”

“…The correct identification of life cycle phase was ascertained by type of zooids released from the mature disk. The presence of four equal flagella and non-sexual nature of zooids (zoospores) confirmed the sporophytic nature of the collected plants (Hiraoka and Enomoto 1998).…”

“…The induction of zoospores and gametes has been reported in Ulva mulabilis (Nordby and Hoxmark 1972) and Ulva pertusa (Hiraoka and Enomoto 1998), but the effect of salinity and temperature on the degree of reproductive cell formation has not been investigated. The present study clearly demonstrated that different salinities in combination with temperature showed significant variation in zoospore induction.…”

Isolation and characterization of a cDNA encoding a heat shock protein 70 from a sterile mutant of Ulva pertusa (Ulvales, Chlorophyta)

“…The mutant strain is more suitable for laboratory experiments than the ''wild'' strain, since the sterile mutant only develops vegetatively without sexual reproduction under chamber cultivation in the laboratory (Migita 1985;Hiraoka and Enomoto 1998;Hiraoka et al 2004). In addition, in order to understand the relationship between physiological and molecular characteristics in response to temperature and heavy metal stresses in the sterile U. pertusa, the level of transcript accumulation for the Hsp70 gene was investigated.…”

Morphological and molecular characterization of free-floating and attached green macroalgae Ulva spp. in the Yellow Sea of China

“…Collection sites are listed in Table 1. All collections were purified by the punch thalli method (Hiraoka and Enomoto 1998). Isolates were cultured in a Climacell incubator (MMM Medcenter Einrichtungen GmbH, Germany) at 20°C with 12 h/12 h light and dark.…”