Penicillus

Abstract: The Codiacean green algae Halimeda and Penicillus and the brown alga Padina are important producers of both calcium carbonate and organic matter in shallow water tropical and subtropical areas1,2. Estimates of algal contribution to shallow water carbonate deposition range from 0 to 61%3–5. However, direct observations on algal carbonate production are very rare. Available data include short-term measurements of calcium and carbon uptake6–9, observations of growth of aquarium specimens10 and periodic observations of death rate for a year at fixed stations11. I report here on in situ measurements taken in Harrington Sound, Bermuda, a shallow subtropical lagoon. Production rates were ∼50 (Halimeda incrassata), 30 (Penicillus capitatus) and 240 Padina sanctae-crucis) g m−2 yr−1 calcium carbonate. The measured growth rates suggest that the algae renew their standing stock approximately once every month (Halimeda and Padina) or once every one and a half months (Penicillus) during their growing season.

Abstract: Recent field observations of highly organized, species- and sex-specific patterns of synchronous gamete release by tropical green algae (Bryopsidales) invite a variety of future studies into the ecology and life histories of an important component of tropical reef communities. This paper details sexual reproduction by 22 algal species within five common genera (Caulerpa, Halimeda, Penicillus, Rhipocephalus, and Udotea), including field observations on the spatial occurrence, timing, and color changes associated with fertility, data on gamete size and behavior, and descriptions of coincident changes in local species abundances. Ecologically ephemeral episodes of sexual reproduction involved macroscopic changes that reliably indicated developmental state and sexual identity. The time from onset of fertility to gamete release was 36 h (Halimeda), 48 h (Caulerpa, Penicillus, and Rhipocephalus), or 96 h (Udotea). All species produced flagellated, negatively buoyant, anisogamous gametes. Microgametes of all species were similar in size; however, considerable species-specific differences were seen in the size of macrogametes. In Caulerpa, Halimeda, and Udotea flabellum (Ellis and Solander) Lamouroux, the volumetric ratio of macrogametes to microgametes ranged from 2:1 to 45: 1, whereas more extreme levels of anisogamy (104: 1) were observed for Penicillus spp., Rhipocephalus phoenix (Ellis and Solander) Kuetzing, and other Udotea spp. The macrogametes of Caulerpa and Halimeda showed strong positive phototaxis. Although only a subset (generally about 5%) of the thalli representing each species released gametes on a given morning, most species underwent bouts of sexual reproduction on numerous occasions during the seasonal peak of reproductive activity (March–May). As might be expected for holocarpic species, dramatic declines in local algal abundance coincided with these periods. The density of sand-dwelling genera such as Penicillus fell by 80– 90% during this 3-month period in 1997. Similar declines in the cover of sprawling species such as Caulerpa racemosa ((Forsskal) J. Agardh) exposed large (35–50 m2) sections of previously overgrown reef substrate.

Abstract: Calcium oxalate crystals occur in the marine green algae Penicillus, Rhipocephalus, and Udotea, known as producers of sedimentary aragonite needles. In contrast to the externally deposited aragonite crystals which are generally < 15 micrometers long, the oxalate crystals are larger (up to 150 micrometers) and are located in the vacuolar system of the plant. No calcium oxalate was found in the related but noncalcifying genera Avrainvillea and Cladocephalus.

Abstract: A whole-cell-based assay using Saccharomyces cerevisiae strains that overexpress Candida albicans CDR1 and MDR1 efflux pumps has been employed to screen natural product extracts for reversal of fluconazole resistance. The tropical green alga Penicillus capitatus was selected for bioassay-guided isolation, leading to the identification of capisterones A and B (1 and 2), which were recently isolated from this alga and shown to possess antifungal activity against the marine pathogen Lindra thallasiae. Current work has assigned their absolute configurations using electronic circular dichroism and determined their preferred conformations in solution based on detailed NOE analysis. Compounds 1 and 2 significantly enhanced fluconazole activity in S. cerevisiae, but did not show inherent antifungal activity when tested against several opportunistic pathogens or cytotoxicity to several human cancer and noncancerous cell lines (up to 35 μM). These compounds may have a potential for combination therapy of fungal inf...