How tardigrades survive extreme circumstances


This March 2017 video says about itself:

Without water, a human can only survive for about 100 hours. But there’s a creature so resilient that it can go without it for decades. This 1-millimeter animal can survive both the hottest and coldest environments on earth, and can even withstand high levels of radiation. Thomas Boothby introduces us to the tardigrade, one of the toughest creatures on Earth.

From the University of California – San Diego in the USA:

Cracking how tardigrades survive the extremes

Researchers discover that a protein in tiny tardigrades binds and forms a protective cloud against extreme survival threats such as radiation damage

October 1, 2019

Summary: Scientists have gained a new understanding of how tiny, ultra-resilient invertebrates known as tardigrades, or ‘water bears’, are protected in extreme conditions. Tardigrades are found in water environments around the world — including mountainous, deep sea and Antarctic environments. The researchers discovered that a tardigrade protein named Dsup binds to chromatin — DNA inside cells — and forms a protective cloud against extreme survival threats such as radiation damage.

Diminutive animals known as tardigrades appear to us as plump, squeezable toys, earning them irresistible nicknames such as “water bears” and “moss piglets.”

But don’t let their squishy appearance fool you. These microscopic invertebrates are highly resilient. In fact, they’re considered “extremophiles“, with near super-power abilities of defense in harsh conditions. What’s behind these capabilities?

Scientists at the University of California San Diego have gained a new understanding of how tardigrades are protected in extreme conditions. Their findings are published in the journal eLife on Oct. 1, 2019.

At roughly 0.1 to one millimeter in size, tardigrades are found in water environments around the world — including mountainous, deep sea and Antarctic environments. They are well documented as having remarkable abilities to survive extreme conditions, from dangerously high radiation levels to chillingly low temperatures to exposure to deadly chemicals. They’ve even been launched into space as part of a project to transfer life forms to the moon (and crash-landed there with the Beresheet lander spacecraft earlier this year).

Carolina Chavez (undergraduate, now a PhD student at UCLA), Grisel Cruz-Becerra (postdoctoral scholar), Jia Fei (assistant project scientist), George A. Kassavetis (research scientist) and James T. Kadonaga (distinguished professor) of UC San Diego’s Division of Biological Sciences employed a variety of biochemical techniques to investigate the mechanisms underlying the survivability of tardigrades in the extremes.

Previous studies identified a protein named Dsup (for Damage suppression protein), which is found only in tardigrades. Intriguingly, when Dsup is tested in human cells, it can protect them from X-rays; however, it was not known how Dsup performs this impressive feat. Through biochemical analysis, the UC San Diego team discovered that Dsup binds to chromatin, which is the form of DNA inside cells. Once bound to chromatin, Dsup protects cells by forming a protective cloud that shields DNA from hydroxyl radicals, which are produced by X-rays.

“We now have a molecular explanation for how Dsup protects cells from X-ray irradiation,” said Kadonaga, a distinguished professor and the Amylin Endowed Chair in Lifesciences Education and Research. “We see that it has two parts, one piece that binds to chromatin and the rest of it forming a kind of cloud that protects the DNA from hydroxyl radicals.”

However, Kadonaga doesn’t think this protection was meant specifically to shield against radiation. Instead, it’s probably a survival mechanism against hydroxyl radicals in the mossy environments that many terrestrial tardigrades inhabit. When the moss dries up, tardigrades shift into a dormant state of dehydration, or “anhydrobiosis,” during which Dsup protection should help them survive.

The researchers say the new findings eventually could help researchers develop animal cells that can live longer under extreme environmental conditions. In biotechnology, this knowledge could be used to increase the durability and longevity of cells, such as for the production of some pharmaceuticals in cultured cells.

“In theory, it seems possible that optimized versions of Dsup could be designed for the protection of DNA in many different types of cells,” said Kadonaga. “Dsup might thus be used in a range of applications, such as cell-based therapies and diagnostic kits in which increased cell survival is beneficial.”

The eLife paper is dedicated to Professor Russell F. Doolittle, a UC San Diego professor emeritus of molecular biology and a pioneer in protein evolution, who carried out the evolutionary analysis of Dsup for the new research and provided guidance throughout the project.

How tardigrades protect their DNA to defy death. A ‘fluffy cloud’ of protein shields water bears’ DNA from radiation, drying and other damage: here.

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How jellyfish regenerate body parts


This July 2017 video from Japan is about Cladonema pacificum jellyfish.

From Tohoku University in Japan:

Jellyfish‘s ‘superpowers’ gained through cellular mechanism

October 1, 2019

Jellyfish are animals that possess the unique ability to regenerate body parts. A team of Japanese scientists has now revealed the cellular mechanisms that give jellyfish these remarkable “superpowers”.

Their findings were published on August 26, 2019 in PeerJ.

“Currently our knowledge of biology is quite limited because most studies have been performed using so-called model animals like mice, flies, worms and fish etc. Given that millions of species exist on the earth, it is important to study various animals and broaden our knowledge,” said Yuichiro Nakajima, Assistant Professor at the Frontier Research Institute for Interdisciplinary Sciences, Tohoku University in Japan, and corresponding author of the study.

“Jellyfish are one of such animals with interesting biological features,” Nakajima said. “For example, they have stinging cells, called cnidocytes, to capture prey.”

Cnidarian jellyfish — named for their stinging cells — have existed on the earth for more than 500 million years. They form part of a unique group of animals that are not bilaterally symmetrical and also possess the capacity to regenerate body parts — a trait most of the complex animals, including humans, have lost. These early-diverging primitive animals could play a pivotal role in helping us better understand the evolutionary biology of bilaterally symmetrical animals, like us humans.

For their study, the researchers used Cladonema pacificum — a jellyfish species from the Cnidaria phylum that has branching tentacles — to investigate the spatial pattern of cell proliferation and their roles during jellyfish development and regeneration, aiming to establish the cellular basis of these phenomena. “With easy lab maintenance and a high spawning rate, Cladonema is suitable for studying various aspects of jellyfish biology,” Nakajima explained.

To investigate the role of cell proliferation following food uptake in determining body-size growth, appendage shape, and regeneration in Cladonema jellyfish, the researchers examined the distribution of cells that play a key role in DNA replication through cell division, producing new ‘daughter’ cells that are identical to the original ‘parent’ cell. They found spatially distinct groups of proliferating cells in the medusa (sexual) life-stage, with cell proliferation in the umbrella-shaped portion of their body being uniform, while cell proliferation in the tentacles was clustered.

After withholding food or blocking cell proliferation using a cell-cycle inhibiting agent, the researchers found body size growth was inhibited, and they also observed defects in tentacle branching, differentiation of stem cells into stinging cells, and regeneration. These results suggest that free-swimming adult jellyfish in the sexual stage possess actively proliferating cells that play a key role in controlling body-size, tentacle shape, and regeneration.

Additionally, the researchers found that when food was not available, the jellyfish exhibited a gradual decrease in body size after 24 hours, suggesting they are sensitive to food availability and are able to adapt to metabolic changes in response to environmental conditions.

“We are currently trying to understand the molecular mechanisms of Cladonema development and regeneration,” said Sosuke Fujita, a master student in the Graduate School of Life Sciences, Tohoku University, and the first author of the study. “Based on this research, molecular control of cell proliferation is the key to deciphering jellyfish growth and regeneration.

According to Nakajima, the researchers also plan to investigate the differences between the two different adult stages in jellyfish: medusae (sexual) and polyps (asexual). “For these purposes, we will identify gene expression changes associated with different developmental and regeneration contexts and plan to introduce genetic tools for manipulation of genes.”

Saving freshwater fish species and aquariums


This 2015 video from the USA says about itself:

Tennessee Aquarium Conservation Institute – Freshwater Biodiversity

The warm waters of the southeastern United States are home to an amazing diversity of animals and habitats. The Tennessee Aquarium Conservation Institute, TNACI, works to protect and sustain the region’s natural treasures and bring people of all ages closer to nature. Help us celebrate and care for these riches in our backyards.

Learn more about the Tennessee Aquarium Conservation Institute and how you can help here.

From Aarhus University in Denmark:

The hidden ark: How a grassroots initiative can help save fish from extinction

October 1, 2019

Summary: Freshwater fish are the most threatened vertebrate group, and species are disappearing faster than scientists can describe them. A new study shows that aquarium hobbyists can play an important role in freshwater fish conservation by filling in the gaps left by the scientific community and conservation organizations.

Freshwater fish are a highly diverse group, representing nearly half of all fish species. Due to accelerating human activities, they are also the most threatened vertebrate group, and are disappearing faster than they can be described. Currently, half of all freshwater fish species are still not formally assessed by conservation organizations, such as the International Union for Conservation of Nature (IUCN), resulting in many species becoming extinct before conservation actions can even be initiated.

However, a newly published study by Dr. Jose Valdez from Aarhus University and Kapil Mandrekar from SUNY College of Environmental Science and Forestry, shows how aquarium hobbyists can play an important role in freshwater fish conservation by filling in the gaps left by the scientific community and conservation organizations.

Dedicated hobbyists

Aquarium keeping is one of the most popular hobbies in the world, with millions of fish owners participating in this activity worldwide. Due to their interest in fish conservation and a love for the species they own, hobbyists often pay more attention to the conservation status of particular fish groups than the scientific community and can be more knowledgeable of some species than their professional counterparts.

“In some cases, species that are not yet scientifically described are well known to hobbyists — such as many species from the armoured catfish family,” says Valdez.

Aquarium hobbyist organizations help bring these passionate enthusiasts together to exchange information on keeping and caring for specific groups of fishes. These hobbyist organizations, along with their dedicated members, have already helped discover new species while saving others from extinction by providing rare and extinct in the wild fish from their own aquariums towards various conservation projects.

Organizations ensure survival

This includes conservation projects such as the Fish Ark Project (FAP) and associated organizations such as the Goodeid Working Group (GWG), who successfully keep populations of the 12 most endangered or extinct-in-the-wild and 24 threatened goodeid species in Mexico. Others such as the Hobbyist Aqualab Conservation Project (HACP), has already provided specimens of rare fish species to 34 universities, public aquaria, zoos, and other hobbyists in 15 countries to ensure their survival.

The largest organization is the CARES (Conservation, Awareness, Recognition, Encouragement, and Support) preservation program, which is associated with some of the major aquarium hobbyist organizations. CARES has taken a grassroots initiative to encourage hobbyists to keep the most endangered, and in some cases, already extinct in the wild freshwater fish to ensure their continued survival.

“The importance of programs, such as CARES,” says Mandrekar, “is that some of the species they focus on have little to no commercial value in the fish trade, and emphasize those that are overlooked and not charismatic enough for many conservation programs.”

First study of potential

Although CARES was founded fifteen years ago, the study by Jose Valdez and Kapil Mandrekar was the first to assess the program’s species and the potential value of CARES to the scientific community and conservation.

The researchers found that CARES listed nearly six hundred species of freshwater fish and over eighty species which are currently unknown by the scientific community.

“Aquarium hobbyists often possess detailed descriptions of undescribed species and the habitats where they are found, which can provide a detailed background for future work by the scientific community,” explains Mandrekar.

The CARES list also contained over thirty species that they consider already extinct in the wild, even though more than a third of those were classified as not threatened by the IUCN.

Need for close partnership with scientists

The vast disconnect of information revealed by the study exemplifies the importance of programs such as CARES and the need for scientists and conservation organizations to not only develop closer partnerships with hobbyist organizations but also recognize them as a valuable resource that can help save freshwater fishes from extinction.

“Many species already extinct in the wild currently only exist because they are specifically being kept and bred by these hobbyists. By bridging these conservation and knowledge gaps, fish hobbyists from the comfort of their home, are playing a pivotal role in helping preserve many of these threatened and rare fishes for future generations,” explains Valdez.

Although CARES involves individuals with scientific backgrounds, the authors state that there must be closer collaborations with scientists across disciplines as well as partnering with in-situ and ex-situ conservation efforts.