Tag: Metabolism

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The Blood and the Run by Mike Fainzilber

flying dracula
bleeding to run
running to bleed

by Mike Fainzilber

This is a haiku about the stuff of nightmares – vampire bats. As we know, vampire bats feed on blood, and blood is low in carbohydrates and lipids that are the typical fuel for activities that require high energy. Flight is highly costly in energy, so how can it be fueled by blood alone? Certain blood-sucking insects can fuel their flight by direct metabolism of amino acids (the building blocks of proteins) in their blood meals, but this metabolic specialization was known only in very few insect species.

A team of biologists traveled from the University of Toronto to Belize to find out if vampire bats can do the same. The researchers took advantage of the fact that vampire bats are exceptionally good runners, and they use this to approach their prey along the ground. Bats were fed cow blood with labeled amino acids and the researchers then placed them on treadmills, monitoring tracer release in the bat’s breath as they ran on the treadmill.

The experiments clearly showed that vampire bats use amino acids as their main fuel source while running. Since running is a major hunting mode for this species, they literally bleed prey to run, and run to bleed…

Further reading:

‘Vampire bats rapidly fuel running with essential or non-essential amino acids from a blood meal’, 2024, Rossi, G.S. & Welch, K.C., Biology Letters, available: https://doi.org/10.1098/rsbl.2024.0453

‘How blood-sucking vampire bats get their energy’, 2024, The Economist, available: https://www.economist.com/science-and-technology/2024/11/06/how-blood-sucking-vampire-bats-get-their-energy

Author bio:

Mike Fainzilber’s day job is a biologist. He began writing haiku and senryu during the pandemic, and this side effect of COVID-19 has not worn off yet. Editors in his two spheres of activity have been known to suggest that he should best restrict his efforts to the other sphere. Find out more about Mike’s research via his lab’s website and connect with him on X/Twitter @MFainzilber or on Bluesky at https://bsky.app/profile/mfainzilber.bsky.social

Read more sciku by Mike: ‘The deepest shade’, ‘Jellyfish’, and ‘In the Deep’.

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Mistletoe

festive parasites
regulating virulence
to preserve their hosts

Mistletoe is a parasitic plant often found growing on hardwoods, such as apple trees. Whilst able to photosynthesize itself, the majority of a mistletoe plant’s water and nutrients are taken from its host, putting strain on the host plant.

The burden of parasitism can be particularly hard on the host when environmental conditions are tough, for instance during a drought. Research by Nabity et al. (2021), however, has shown that the desert mistletoe (Phoradendron californicum) is able to adjust the balance between autotrophy (the amount it obtains resources for itself through photosynthesis) and heterotrophy (the amount it takes resources from its host).

During dry periods the researchers found that desert mistletoe plants increased the amount of photosynthesis they performed, limiting the burden they place on their environmentally stressed host, the velvet mesquite (Prosopsis velutina). In this way mistletoe plants increase the chances of their host plants surviving the harsh environmental conditions and, as a result, increase their own chances of survival.

The researchers also demonstrated evidence of competition for xylem resources between mistletoe plants on the same host, some of the first evidence of intraspecific competition in parasites. The mistletoe plants are able to detect other mistletoe plants on the same host and can adjust their virulence accordingly. Possible ways that mistletoe could detect one another include via scent (chemical compounds released through a plant’s pores) or through chemical compounds traveling along the host’s xylem.

The research also suggests that levels of relatedness between mistletoe plants sharing the same host may even affect virulence. More research is needed to clarify this, however, and to investigate whether the plants can actually detect relatedness or whether mistletoe’s method of seed dispersal simply means that plants sharing the same host are likely to have higher levels of relatedness than mistletoe plants on separate hosts.

Further reading: http://dx.doi.org/10.1016/j.cub.2021.01.034

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On a knife edge

Life on a knife edge:

The metabolic demands

facing polar bears.

 

Polar bears rely on marine mammals such as seals which are high-fat prey. Despite the richness of their diet however, new research suggests that a reduction in the prey availability can have severe consequences on polar bear survival.

Pagano et al (2018) monitored nine free-ranging female polar bears over 2 years, measuring their metabolic rates, daily activity patterns, body condition and foraging success. They found that more than half of the bears had an energy deficit resulting from a high metabolic rate (1.6 times higher than previously assumed) and a low intake of the high-fat prey. As fragmentation of sea ice continues and seals become harder to catch the high metabolic requirements of polar bears is likely to become increasingly catastrophic for the species.

Original research: https://doi.org/10.1126/science.aan8677

 

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Alchemist goldfish

Alchemist goldfish

change acid to alcohol

through doubled proteins.

 

Many species of carp (including goldfish) can survive for months over winter in frozen lakes despite a lack of oxygen. Without oxygen they use anaerobic respiration resulting in the production of lactic acid. To avoid a deadly build up of lactic acid the fish convert it into ethanol which diffuses across their gills into the surrounding water.

Researchers have now discovered how the fish do this. During energy production in the absence of oxygen a mutated set of proteins switches the metabolic pathway within mitochondria to produce ethanol instead. The fish have two sets of these proteins, one set which is very similar to that found in other species and one set that appears to be a duplicate of the first. These sets of proteins appear to have arisen during a whole genome duplication event approximately 8 million years ago and have enabled the fish to survive in conditions other species can’t. Fagernes et al, 2017.