akashiwo is a poor competitor compared to other algal species. Instead, Heterosigma may proliferate under dynamic conditions due to its ability to respond

quickly to nutrient input. The objectives of this investigation were to examine changes in transcriptional expression of nitrate reductase (NR) as a proxy for nitrate assimilation in Heterosigma. Here, the gene sequence for H. akashiwo nitrate reductase (NR1) was amplified by PCR, and the full-length gene sequence was obtained and characterized. Using quantitative reverse transcriptase real-time PCR (QRT-PCR), changes CAL-101 concentration in NR1 expression were evaluated in relation to temperature and nitrogen status. Expression of NR1 was not significantly different for cultures acclimated to temperatures ranging from 18°C to 28°C. Results also demonstrated that NR1 was expressed constitutively, even in the absence of nitrate and in the presence of ammonium. An apparent biphasic expression of NR1 was observed upon addition of nitrate to N-starved cultures, with significant increases at 15 and 60 min after addition. In contrast, addition of nitrate to nitrate-replete

cultures resulted in a significant decrease in NR1 transcript BI 2536 in vitro abundance, likely due to repression by downstream products of nitrate assimilation. These results suggest that Heterosigma responds rapidly to changes

in the environment by up- or down-regulating the NR transcript pool in relation to the nitrogen status of the cell. “
“Seaweeds are ecologically important primary producers, competitors, and ecosystem engineers that play a central role in coastal habitats ranging from kelp forests to coral reefs. Although seaweeds are known to be vulnerable to physical and chemical changes in the marine environment, the impacts of ongoing and future anthropogenic climate change in seaweed-dominated ecosystems remain poorly understood. In this review, we describe the ways in which changes in the environment directly affect seaweeds in terms of their physiology, growth, reproduction, and Phospholipase D1 survival. We consider the extent to which seaweed species may be able to respond to these changes via adaptation or migration. We also examine the extensive reshuffling of communities that is occurring as the ecological balance between competing species changes, and as top-down control by herbivores becomes stronger or weaker. Finally, we delve into some of the ecosystem-level responses to these changes, including changes in primary productivity, diversity, and resilience. Although there are several key areas in which ecological insight is lacking, we suggest that reasonable climate-related hypotheses can be developed and tested based on current information.