Scientists found the oldest sperm sample

Entangled in amber during the Cretaceous period, And hidden in a collection for decades, the sperm’s evolutionary grandfather was patiently searching for scientists.

In 2020, the day finally arrived. In a new study, scientists report that they have discovered the oldest known sperm cells ever.

Cells reported in a paper published on Wednesday Proceedings of the Royal Society B, A hystero of Ostracode was found in the reproductive tract of an undiscovered species – a class of crustaceans about 1 millimeter smaller in size.

The entire amber sample dates back to the Cretaceous period, meaning that for 100 million years, the sample was incomplete.

This creature, dub MyanmarSprice Hui, Live in the coastal and inland waters of Myanmar, which are covered with dense trees. M. Hui, Likely now having sex with the world’s oldest sperm owner, before being enclosed in a coat of amber that preserves both her body and soft sperm cells.

Renate Matzke-Karasz is the study’s lead author and a paleontologist at Ludwig Maximilian University in Munich. She Tells In the shlokas That these sperm cells are almost 50 million years old Compared to previously identified older sperm cells. The last oldest sperm cells can be attributed to a source that was found in the cocoons of an extinct Antarctic worm species, which were reported in 2015.

The amber fragments were analyzed as part of the study.Photo courtesy of Renate Matzke-Karcz

Matzke-Karasz Adds Owned by a collector named Cheng Hu, his team came upon specimens in a private collection in China.

“She realized that there were these little ostracodes in amber,” she explains In the shlokas. “We named the new species after that.

Both the age and status of the discovery are exciting, however, there was something extra special about sperm in Burmese amber: sperm may be larger than you would expect from a creature weighing less.

An example of this Sperm count, And proof that A. Alternative Sperm Strategy Millions of years ago there was an effective method of copulating.

“This is evidence that the giant sperm are no extravagant whispers,” she explains.

M. during the Cretaceous period. Reconstruction of Hui Mating Artists. Since the sperm cells were still in the female’s reproductive tract, scientists propose that the pair were formed shortly before the female was trapped in amber.

What does this search change? – Sperm are thought to be small, roughly 50-micrometer swimmers commonly found in males. Matzke-Karz states that these types of sperm represent the concept used by vertebrates and most other animals: produce as many sperm as possible and hope that the strongest, fastest floating female eggs Reach.

However, this is not the only sperm strategy respected by nature. At the other end of the spectrum is sperm vastness – the idea that an organism can produce few, very long sperm compared to its body size.

it is a matter Drosophila bifurca, A fruit fly that produces sperm that is 5.8 cm long when left untouched (about 20 times the body length). Ostracodes like M. Hui Also known as particularly long sperm, as long as their body length is about 4.5 times or about Matzke-Karz.

5 feet, 5 inches long for a human, which would translate to a sperm length of about 23 feet, she explains.

Sperm from a living ostracode.Courtesy of Renate Matzke-Karrez

Found in sperm Mhui This is difficult to measure (not uncommon for Ostracode) due to the “intriguing mass” of the sample, the authors note. But he estimates that it is at least 200 micrometers long.

As impressive as these measurements are, it is unclear exactly how useful this strategy was. Large sperm come at a cost, Matzke-Karz explains.

Long sperm, such as those found in it M. Hui, Are stable and require a funnel in the reproductive tract of the woman, which means that the organism’s body must invest in additional organs and energy to reproduce. Large sperm are also produced by large reproductive organs, creating an additional drain on energy.

“Reproductive organs are much larger than other species, they are taking up too much space in the animal, and mating lasts a long time,” she says. “This is a lot of biological energy that must be allocated for reproduction.”

A reconstruction of the sperm found in M.Hui.Courtesy of Renate Matke-Karz

Evolutionarily speaking without pay, “expensive” features are considered counter-productive, although there are examples of beings or those whose extraordinary traits pay off. Male peacock feathers, for example, help them attract mates.

Longer sperm coming from smaller organisms, however, present no obvious benefit. Some studies in mammals have shown that the more sperm length can grow faster, the more competitive sperm can swim, but the evidence is mixed.

The fact that it is an example of sperm abundance All but one indication is that this copulation strategy remained in the Ostracodes for millions of years. Matzke-Karz saw this as proof that something about that strategy would be working, even though we don’t know if something isn’t there yet.

“At first, we weren’t sure that if animals ‘switched’ to using these giant sperm at a certain point in their evolutionary history, they would go extinct very quickly,” he continues. “But at Ostracodes, it worked for over 100 million years.”

abstract: The divalent crustacean ostracodes have the richest fossil record of any arthropod group and exhibit complex reproductive strategies contributing to their evolutionary success. Sexual reproduction related to giant sperm, shared by three superfamilies of living ostracode crustaceans, is one of the most attractive behaviors. However, the origin and development of this reproductive system is largely unclear because fossil preservation of such characteristics is extremely rare. Here, we report an exceptionally preserved ostracode with soft parts (appendages and reproductive organs) in a fragment of mid-Cretaceous Kachin amber (about 100 mya). Ostracod assembling is composed of 39 individuals. Thirty-one individuals belong to the genus Myanmarcapris Hui, a new species and genus. Et sp. Performing an ontogenetic sequence from novice, juvenile to adult (male and female). Seven individuals have been assigned to Thalasocapria sp. (Cypridoidea, Candonida, Paracipridina) and one to Sanuania sp. (Cytheroid, Loxoconchida). Our micro-CT reconstructions provide direct evidence of male clappers, sperm pumps (Zenker organs), hemi-pens, eggs, and female sperm with giant sperm. Our results suggest that the list of reproductive behavioral repertoires, associated with considerable morphological changes, has remained unchanged for at least 100 million years – a paramount example of evolutionary stagnation. These results also double the age of the oldest unequal fossil animal sperm. This finding exposes Amber’s ability to document soft parts that are rarely recorded by other deposition environments.