The compact genome of Fugu rubripes has been sequenced to over 95% coverage, and more than 80% of the assembly is in multigene-sized scaffolds. In this 365-megabase vertebrate genome, repetitive DNA accounts for less than one-sixth of the sequence, and gene loci occupy about one-third of the genome. As with the human genome, gene loci are not evenly distributed, but are clustered into sparse and dense regions. Some “giant” genes were observed that had average coding sequence sizes but were spread over genomic lengths significantly larger than those of their human orthologs. Although three-quarters of predicted human proteins have a strong match to Fugu , approximately a quarter of the human proteins had highly diverged from or had no pufferfish homologs, highlighting the extent of protein evolution in the 450 million years since teleosts and mammals diverged. Conserved linkages between Fugu and human genes indicate the preservation of chromosomal segments from the common vertebrate ancestor, but with considerable scrambling of gene order.

Insects vary considerably in their ability to survive low temperatures. The tractability of these organisms to experimentation has lead to considerable physiology-based work investigating both the variability between species and the actual mechanisms themselves. This has highlighted a range of strategies including freeze tolerance, freeze avoidance, protective dehydration and rapid cold hardening, which are often associated with the production of specific chemicals such as antifreezes and polyol cryoprotectants. But we are still far from identifying the critical elements behind over-wintering success and how some species can regularly survive temperatures below −20°C. Molecular biology is the most recent tool to be added to the insect physiologist’s armoury. With the public availability of the genome sequence of model insects such as Drosophila and the production of custom-made molecular resources, such as EST libraries and microarrays, we are now in a position to start dissecting the molecular mechanisms behind some of these well-characterised physiological responses. This review aims to provide a state-of-the-art snapshot of the molecular work currently being conducted into insect cold tolerance and the very interesting preliminary results from such studies, which provide great promise for the future.

Animal physiology, ecology and evolution are affected by temperature and it is expected that community structure will be strongly influenced by global warming. This is particularly relevant in the tropics, where organisms are already living close to their upper temperature limits and hence are highly vulnerable to rising temperature. Here we present data on upper temperature limits of 34 tropical marine ectotherm species from seven phyla living in intertidal and subtidal habitats. Short term thermal tolerances and vertical distributions were correlated, i.e., upper shore animals have higher thermal tolerance than lower shore and subtidal animals; however, animals, despite their respective tidal height, were susceptible to the same temperature in the long term. When temperatures were raised by 1°C hour⁻¹, the upper lethal temperature range of intertidal ectotherms was 41–52°C, but this range was narrower and reduced to 37–41°C in subtidal animals. The rate of temperature change, however, affected intertidal and subtidal animals differently. In chronic heating experiments when temperature was raised weekly or monthly instead of every hour, upper temperature limits of subtidal species decreased from 40°C to 35.4°C, while the decrease was more than 10°C in high shore organisms. Hence in the long term, activity and survival of tropical marine organisms could be compromised just 2–3°C above present seawater temperatures. Differences between animals from environments that experience different levels of temperature variability suggest that the physiological mechanisms underlying thermal sensitivity may vary at different rates of warming.

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapsho

Antarctic marine species have evolved in one of the coldest and most temperature-stable marine environments on Earth. They have long been classified as being stenothermal, or having a poor capacity to resist warming. Here we show that their ability to acclimate their physiology to elevated temperatures is poor compared with species from temperate latitudes, and similar to those from the tropics. Those species that have been demonstrated to acclimate take a very long time to do so, with Antarctic fish requiring up to 21–36 days to acclimate, which is 2–4 times as long as temperate species, and invertebrates requiring between 2 and 5 months to complete whole-animal acclimation. Investigations of upper thermal tolerance (CTmax) in Antarctic marine species have shown that as the rate of warming is reduced in experiments, CTmax declines markedly, ranging from 8 to 17.5°C across 13 species at a rate of warming of 1°C day−1, and from 1 to 6°C at a rate of 1°C month−1. This effect of the rate of warming on CTmax also appears to be present at all latitudes. A macrophysiological analysis of long-term CTmax across latitudes for marine benthic groups showed that both Antarctic and tropical species were less resistant to elevated temperatures in experiments and thus had lower warming allowances (measured as the difference between long-term CTmax and experienced environmental temperature), or warming resistance, than temperate species. This makes them more at risk from warming than species from intermediate latitudes. This suggests that the variability of environmental temperature may be a major factor in dictating an organism's responses to environmental change.