Nature teaches people a lot of things. Recently, Science explored how animals, plants, and bacteria can use different resilience strategies to survive in the face of scarce resources, predators, and other challenges.
1, Salamander Image source: DANTÉ FENOLIO
Regeneration Spell
Humans should be jealous of salamanders. People's ability to regenerate is limited: fractures, wound healing, most livers can regenerate, but that's about it. But a large salamander known as the "Mexican walking fish," which looks like a 20-centimeter-long legged eel, is able to regenerate all of its limbs, even its tail, meaning it can regrow its spinal cord, bones and muscles.
About 30 research groups are exploring how salamanders do this. They found that different tissues of salamanders work together to detect limb loss and coordinate regeneration. In the process, the animal activates the genetic pathways that guide the formation of structures during embryonic development, leading to stem cell differentiation.
In the animal kingdom, salamanders are only one of the animals with regenerative abilities. True planarians have a stronger ability to recover – recovering after losing 90% of their body. A small fraction of this 2-centimeter-long aquatic organism regenerates the brain, skin, intestines, and all other functional organs.
Similarly, stem cells are key, and a special set of genes active in euthypes muscles tells these stem cells what to do and activates the right cell growth and differentiation at the right time. Thus, true planarians can begin to respawn almost "from scratch", while salamanders can only be reborn if the subject remains intact.
This year, the researchers sequenced the genomes of both species, further studying the molecules behind their ability to regenerate. Ultimate hope: One day, injured humans will be able to make the same repairs.
2 Bacillus pneumoniae Image source: SPL
Steal genes to survive
Imagine a hospitalized cancer patient with a severe lung infection. When a powerful antibiotic keeps coming into patients, the pneumoniae seems doomed. But it could deploy a recovery strategy that has been through billions of years: borrowing a gene from another cell to allow the pathogen to survive.
When the environment changes, the organism adapts or dies. Pneumoniae and other bacteria accelerate the adaptation process by acquiring genes from elsewhere. This horizontal gene transfer has allowed these bacteria to acquire new properties, from thriving in cheese to antibiotic resistance.
The researchers believe that the pneumoniae acquired its antibiotic-damaging gene blaKPC from another bacteria that has not yet been identified. Bacillus pneumoniae with this gene produce an enzyme that breaks down several antibiotics.
Like many recovery strategies in nature, stealing genes comes at a cost. Sometimes microbes absorb harmful genes instead of beneficial ones. Just as a basketball team has just recruited a new player, the proteins produced from the acquired genes may not match the other proteins in the cell. But unfortunately, for patients, the strategy of Pneumoniae is very effective: these bacteria kill 40 to 70 percent of infected people.
3, Ground Squirrel Image source: GRACHEVA LAB
Squirrel's emergency fund
Running around the South Dakota prairie, ground squirrels will greet the arrival of winter in a wild way. When a squirrel is hibernating, its weight will soar by 40%, thanks to extra fat.
In droughts, migrations, cold winters, and other challenges, organisms often face resource scarcity. To solve this problem, squirrels, like many other creatures, store resources to be used later. In a single day, it can gain more than 2% of its body weight in seeds, grasshoppers and other delicacies.
But this strategy also has drawbacks. A stocky rodent is more likely to be prey to an eagle or coyote wolf. Moreover, these contingency funds will be depleted early. So once a squirrel grows fat enough, it goes into hibernation, reducing energy expenditure by 90%. At this point, its body temperature drops to just above freezing and its heart rate drops to 5 beats per minute, below the usual 350 to 400 beats.
The accumulation of fat requires metabolic and behavioral adjustments. However, squirrels somehow avoid the health problems that plague obese people. Although it developed some metabolic deficiencies in type 2 diabetes, it did not get sick. In the spring, the squirrels will be thin and strong, ready to start the cycle again.
4, Wild Tobacco Image source: STAN SHEBS
Plants can also fight
Unlike people with legs, plants can't escape what they don't like – but they show extraordinary resilience when attacked. The wild tobacco plant is a 1-meter-tall plant in North America that protects itself from hungry insects.
The plant senses amino acid compounds in the caterpillar's saliva and does so by sending out alarm signals— hydraulic or electrical impulses through its stems and leaves. Within minutes, plant cells accelerate the production of nicotine, a toxin that interferes with animal muscle function.
When attacked, one leaf of wild tobacco can produce the equivalent of half a box of nicotine. But some caterpillars, such as the moth, have evolved a way to get the toxin through the gut without absorbing it, forcing wild tobacco to tap into new countermeasures. These plants produce compounds that hinder digestion and make caterpillars sluggish, in order to damage rough grinding wheels in an attacker's mouthpiece.
At the same time, the plant can also attract caterpillar predators by emitting a scent that then sends chemical signals to guide these predators to catch already dull prey. In addition, besieged plants can redirect their resources, delaying flowering and growth until the caterpillars disappear. Amazingly, all of this is not determined by the plant's central brain, but by the decision cells that are scattered throughout the plant.
5, Seabream Image source: D. P. WILSON
Fish can switch genders
Fish are masters of reproductive resilience. Over a lifetime, about 450 fish species are able to change sex to maximize the number of their offspring.
Fish change their organs from one sex to another through hormonal changes. Patterns of sex transition vary from species to species. Large females produce more eggs than small females, so for some species, such as clownfish, it is best to be a male in the early stages of life and then become a female. However, for some fish, males fight each other for females or territory – such as groupers, seabream and echinaceans , and the males are too small to mean they have no offspring. Therefore, these fish are preferably females in their infancy.
Now, this ancient strategy allows fish such as seabream to adapt to modern challenges that have also upset the gender balance: overfishing. Fishermen like to catch larger fish. Because one sex is usually larger than the other, it is easier to be caught. But the researchers found that the seabream was ready.
In order to keep the males from being too large, some females will have sex changes earlier, so the balance between the sexes is preserved. Still, the researchers say this is a short-term strategy, not a long-term solution. This trend also means a decrease in the number of seabream offspring.
In any case, this resilience strategy allows fish to reproduce, but they cannot save themselves entirely on their own. (Compiled by Zhang Zhang)