Maintenance of Complex Life Cycles Via Cryptic Differences In The Ecophysiology Of Haploid And Diploid Spores Of An Isomorphic Red Alga1.

Recognition of the wide diversity of organisms that maintain complex haploid-diploid life cycles has generated interest in understanding the evolution and persistence of such life cycles. We empirically tested the model where complex haploid-diploid life cycles may be maintained by subtle/cryptic differences in the vital rates of isomorphic haploid-diploids, by examining the ecophysiology of haploid tetraspores and diploid carpospores of the isomorphic red alga Chondrus verrucosus. While tetraspores and carpospores of this species did not differ in size or autofluorescence, concentrations of phycobiliproteins of carpospores were greater than that of tetraspores. However, tetraspores were more photosynthetically competent than carpospores over a broader range of photosynthetic photon flux densities (PPFDs) and at PPFDs found at both the depth that C. verrucosus is found at high tide and in surface waters in which planktonic propagules might disperse. These results suggest potential differences in dispersal potential and reproductive success of haploid and diploid spores. Moreover, these cryptic differences in ecological niche partitioning of haploid and diploid spores contribute to our understanding of some of the differences between these ploidy stages that may ultimately lead to the maintenance of the complex haploid-diploid life cycle in this isomorphic red alga.

Cellulomonas algicola sp. nov., an actinobacterium isolated from a freshwater alga.

An actinomycete strain, TKZ-21T, was isolated from a freshwater alga (Chetophoraceae) collected from the Takizawa River, Yamanashi, Japan, and examined using a polyphasic taxonomic approach. Cells were Gram-stain positive, aerobic, non-sporulating, motile, and coccoid or short rod-shaped. The strain grew in the presence of 0-4 % (w/v) NaCl, between pH 6-9.4, and over a temperature range of 15-40 °C, with optimum growth at 30 °C. The peptidoglycan type of strain TKZ-21T was A4ß, containing l-ornithine as diagnostic diamino acid and d-glutamic acid as the interpeptide bridge. The predominant menaquinone was MK-9(H4). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, ninhydrin-positive glycolipid, and unidentified phospholipids. The major cellular fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0, and the DNA G+C content was 75.6 mol%. On the basis of 16S rRNA gene sequence analysis, strain TKZ-21T was closely related to Cellulomonas fimi (98.5 % sequence similarity) and Cellulomonas biazotea (98.3 %). The genome orthoANI value between strain TKZ-21T and C. biazotea and C. fimi were 84.7 and 84.2 %, respectively. On the basis of fatty acid and MALDI-TOF MS profile analysis, phylogenetic analyses, genomic analysis, and phenotypic data, it is proposed that the isolate be classified as a representative of a novel species of the genus Cellulomonas, with the name Cellulomonas algicola sp. nov. The type strain is TKZ-21T (=NBRC 112905T=TBRC 8129T).

Omaezallene from red alga Laurencia sp.: structure elucidation, total synthesis, and antifouling activity.

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene-containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated.