Live cell analysis at sea reveals divergent thermal performance between photosynthetic ocean microbial eukaryote populations.

Experimentation at sea provides insight into which traits of ocean microbes are linked to performance in situ. Here we show distinct patterns in thermal tolerance of microbial phototrophs from adjacent water masses sampled in the south-west Pacific Ocean, determined using a fluorescent marker for reactive oxygen species (ROS). ROS content of pico-eukaryotes was assessed after 1, 5 and 25 h of incubation along a temperature gradient (15.

Shaping up for stress: Physiological flexibility is key to survivorship in a habitat-forming macroalga.

Organisms from all domains of life can have highly variable morphologies, with this plasticity suggested to increase fitness and survivability under stressful conditions. Predicting how organisms will adapt to environmental change requires an understanding of how variable morphologies perform under environmental stress. Morphological plasticity has been documented within marine macroalgae inhabiting environmental gradients, however the functional consequences of this variation has been rarely tested.

Potential for adaptation in response to thermal stress in an intertidal macroalga.

Understanding responses of marine algae to changing ocean temperatures requires knowledge of the impacts of elevated temperatures and the likelihood of adaptation to thermal stress. The potential for rapid evolution of thermal tolerance is dependent on the levels of heritable genetic variation in response to thermal stress within a population. Here, we use a quantitative genetic breeding design to establish whether there is a heritable variation in thermal sensitivity in two populations of a habitat-forming intertidal macroalga, Hormosira banksii (Turner) Descaisne.

Bradydysrhythmias and atrioventricular conduction blocks.

Bradydysrhythimas include sinus bradycardia, junctional brady-cardia, and idioventricular rhythm, which can be distinguished by examining the tracing for the presence or absence of P waves,noting the morphology of these P waves, and determining the width of the QRS complex. Sinoatrial blocks may occur in either first, second, or third degree varieties. Only second degree sinoatrial block can be detected on the 12-lead ECG.