Hexbyte Glen Cove Researchers describe new tardigrade fossil found in 16 million year old Domincan amber

Hexbyte Glen Cove

Artistic reconstruction of Paradoryphoribius chronocaribbeus gen. et sp. nov. in mosses. Credit: Original art created by Holly Sullivan

Tardigrades, also known as water bears, are a diverse group of charismatic microscopic invertebrates that are best known for their ability to survive extreme conditions. A famous example was a 2007 trip to space where tardigrades were exposed to the space vacuum and harmful ionizing solar radiation, and still managed to survive and reproduce after returning to Earth. Tardigrades are found in all the continents of the world and in different environments including marine, freshwater, and terrestrial.

Tardigrades have survived all five Phanerozoic Great Mass Extinction events, yet the earliest modern-looking tardigrades are only known from the Cretaceous, approximately 80 million years ago. Despite their long evolutionary history and global distribution, the fossil record is exceedingly sparse. Due to their microscopic size and non-biomineralizing body, the chance of tardigrades to become fossilized is small.

In a paper published October 6 in Proceedings of the Royal Society B researchers describe a new modern-looking tardigrade fossil that represents a new genus and new species. The study used confocal laser microscopy to obtain higher resolution images of important anatomical characteristics that aid in phylogenetic analyses to establish the taxonomic placement of the fossil.

The new fossil Paradoryphoribius chronocaribbeus is only the third tardigrade amber fossil to be fully described and formally named to date. The other two fully described modern-looking tardigrade fossils are Milnesium swolenskyi and Beorn leggi, both known from Cretaceous-age amber in North America. Paradoryphoribius is the first fossil to be found embedded in Miocene (approximately 16 million years ago) Dominican amber and the first fossil representative of the tardigrade superfamily Isohypsibioidea.

Co-author Phillip Barden, New Jersey Institute of Technology, introduced the fossil to lead author Marc A. Mapalo, Ph.D. Candidate, and senior author Professor Javier Ortega-Hernández, both in the Department of Organismic and Evolutionary Biology, Harvard University. Barden’s lab discovered the fossil and teamed with Ortega-Hernández and Mapalo to analyse the fossil in detail. Mapalo, who specializes in tardigrades, took the lead in analyzing the fossil using confocal microscopes located in the Harvard Center for Biological Imaging.

“The difficulty of working with this amber specimen is that it’s far too small for dissecting microscopes, we needed a special microscope to fully see the fossil,” Mapalo said. Generally the light transmitted by dissecting microscopes works well to reveal the morphology of larger inclusions such as insects and spiders in amber. Paradoryphoribius, however, has a total body length of only 559 micro meters, or slightly over half a millimeter. At such a small scale a dissecting microscope can only reveal the external morphology of the fossil.

Left) Lateral view of Paradoryphoribius chronocaribbeus gen. et sp. nov. viewed with transmitted light under streomicroscope (top) and with autofluorescence under confocal laser microscope (bottom). Right) Ventral view of Paradoryphoribius chronocaribbeus gen. et sp. nov. viewed with transmitted light under streomicroscope (top) and with autofluorescence under confocal laser microscope (bottom). Credit: Marc A. Mapalo

Fortunately, Tardigrade’s cuticle is made of chitin, a fibrous glucose substance that is a primary component of cell walls in fungi and the exoskeletons of arthropods. Chitin is fluorescent and easily excited by lasers making it possible to fully visualize the tardigrade fossil using confocal laser microscopy. The use of confocal laser microscopy instead of transmitted light to study the fossil created degrees of fluorescence allowing a more clear view of the internal morphology. With this method Mapalo was able to fully visualize two very important characters of the fossil, the claws and the buccal apparatus, or the foregut of the animal which is also made of cuticle.

“Even though externally it looked like a modern tardigrade, with confocal laser microscopy we could see it had this unique foregut organization that warranted for us to erect a within this extant group of tardigrade superfamilies,” said Mapalo. “Paradoryphoribius is the only genus that has this specific unique character arrangement in the superfamily Isohypsibioidea.”

“Tardigrade fossils are rare,” said Ortega-Hernández. “With our new study, the full tally includes only four specimens, from which only three are formally described and named, including Paradoryphoribius. This paper basically encompasses a third of the tardigrade fossil record known to date. Furthermore, Paradoryphoribius offers the only data on a tardigrade buccal apparatus in their entire fossil record.”

The authors note there is a strong preservation bias for tardigrade fossils in amber due to their and habitat preferences. Thus, amber deposits provide the most reliable source for finding new tardigrade fossils, even though that does not mean finding them is an easy task. The discovery of a tardigrade fossil in Dominican amber suggests that other frequently sampled sites, such as Burmese and Baltic amber deposits, could also harbor tardigrade fossils. Historically there is a bias towards larger inclusions in amber as inclusions as small as tardigrades are hard to see and require extremely good observational skills, as well as some specialist knowledge.

“Scientists know where tardigrades broadly fit in the tree of life, that they are related to arthropods, and that they have a deep origin during the Cambrian Explosion. The problem is that we have this extremely lonely phylum with only three named fossils. Most of the fossils from this phylum are found in amber but, because they’re small, even if they are preserved it may be really difficult to see them,” Ortega-Hernández said.

Mapalo agreed, “If you look at the external morphology of tardigrades, you might assume that there are no changes that occurred within the body of tardigrades. However, using confocal laser microscopy to visualize the internal morphology, we saw characters that are not observed in extent species but are observed in the fossils. This helps us understand what changes in the body occurred across millions of years. Furthermore, this suggests that even if tardigrades may be the same externally, some changes are occurring internally.”

Mapalo and Ortega-Hernández continue to employ confocal laser microscopy technology to study other tardigrades in amber in their hopes to expand the tardigrade fossil record.



More information:
A tardigrade in Dominican amber, Proceedings of the Royal Society B (2021). rspb.royalsocietypublishing.or … .1098/rspb.2021.1760

Citation:
Researchers describe new tardigrade fossil found in 16 million year old Domincan amber (2021, October 5)
retrieved 6 October 2021
from https://phys.org/news/2021-10-tardigrade-fossil-million-year-domincan.html

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Hexbyte Glen Cove If endangered primates disappear, so will their parasites. That's actually a problem thumbnail

Hexbyte Glen Cove If endangered primates disappear, so will their parasites. That’s actually a problem

Hexbyte Glen Cove

New research predicts that the loss of 108 threatened primates could doom an additional 176 parasite species to extinction, because they have no other suitable hosts. Credit: Marie-Claire Chelini and TriCEM

We put “save the chimps” on t-shirts and posters. But you’ll never see anyone walking around in a shirt that says “save the chimpanzee lice.” People seem to be more aware of the plight of endangered gorillas than of the gorillas’ gut worms, or are understandably more enamored with mouse lemurs than their mites.

Our closest animal relatives face a precarious future: Half of the world’s roughly 500 primate are at risk of extinction due to human activities such as hunting, trapping and deforestation. But the demise of the world’s threatened primates could trigger even more species extinctions for the parasites that lurk on and in them, according to a Duke University-led study.

“If all the primates that are threatened with extinction really do die out, they won’t be the only species that go extinct,” said first author James Herrera of the Duke Lemur Center. “It could also be twice that many parasites.”

“That’s a whole realm of biodiversity that could be going extinct without us even noticing,” Herrera said. “There’s so little that we know about what they do in the body, that we don’t even know what we’re losing.”

One previous study suggests that some 85% to 95% of the parasitic worms of animals aren’t even known to science yet, much less evaluated by the authoritative extinction ‘Red List’ kept by the International Union for Conservation of Nature (IUCN).

Herrera admits this may seem like an odd thing to get worked up about, given all our efforts to deworm and delouse ourselves and our pets. To most people, parasites are “something we want to eradicate, rather than conserve,” Herrera said.

The thought of alien creatures biting, wriggling, squirming, and nestling into the warm wet folds of the intestines makes most people shudder. But parasites don’t always cause noticeable symptoms or make their hosts sick, Herrera said. Parasites can even have some surprising benefits, such as when worms in the gut help the body ward off other infections, or keep autoimmune disorders in check.

To gauge the potential loss of biodiversity if primates go extinct, Herrera and Duke professors Charlie Nunn and James Moody used network analysis techniques to measure the potential ripple effects on the parasites that set up camp in or on primate bodies. Their work appeared Sept. 20 in the journal Philosophical Transactions B.

In their model, species are connected in complex webs of interactions involving 213 primates—monkeys, apes, lemurs and galagos—and 763 worms, mites, protists, and other parasites known to infect them. When one primate host disappears, the parasites connected to it can no longer depend on it for survival. Sever enough of these connections, and their loss sets off a deadly cascade where one extinction begets another.

It’s a bit like the classic kids’ game, KerPlunk, Herrera said. You have a clear tube filled with marbles, which are resting on top of a web of crisscrossing sticks. Removing one or two sticks—or in this case, primate hosts—from the network does little harm, because the marbles are still supported by the remaining sticks. But as the game goes on and fewer sticks remain, it gets harder to keep the marbles from crashing down.

Currently, 108 of the 213 in their dataset are considered threatened by the IUCN. The team found that if all those species were to go kaput, an additional 250 parasites could be doomed as well, and that 176 of these parasite species have no other suitable hosts.

The extinction cascade will likely be worse in isolated places like the island of Madagascar, the study revealed. There, shrinking forests, illegal hunting and collection for the pet trade are pushing 95% of lemur species ever closer to the brink, and more than 60% of lemur parasites inhabit a single host.

For instance, at least two species of nematode worms depend on the aye-aye, a long-fingered, bushy-tailed lemur with beaver-like teeth. If the aye-aye dies out, so too will the worms it carries.

The researchers say they aren’t able to predict, from their analyses, how many of the in their dataset could potentially avert extinction by jumping ship and adapting to new hosts that are more abundant. But some of the most notorious diseases in humans, such as malaria, AIDS caused by HIV and yellow fever, got their start in other primates before spilling over to people, for instance when we share a watering hole, or when we butcher them for meat.

“It’s not that hard to imagine,” Herrera said.

The study is part of a special issue of Philosophical Transactions of the Royal Society B devoted to infectious disease macroecology.



More information:
James P. Herrera et al, Predictions of primate–parasite coextinction, Philosophical Transactions of the Royal Society B: Biological Sciences (2021). DOI: 10.1098/rstb.2020.0355

Citation:
If endangered primates disappear, so will their parasites. That’s actually a problem (2021, September 23)
retrieved 24 September 2021

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Hexbyte Glen Cove Want to reduce cockroach sex? Block an enzyme thumbnail

Hexbyte Glen Cove Want to reduce cockroach sex? Block an enzyme

Hexbyte Glen Cove

Credit: Unsplash/CC0 Public Domain

It’s not the look in her compound eyes or the shape of her carapace that really attracts the male cockroach to his mate. Instead, it’s all those 29-carbon hydrocarbons in her cuticle that drive him wild. How the female cockroach regulates production of these contact sex pheromones, and what happens when she produces too few, is the subject of a new study publishing on July 27th in the open-access journal PLOS Biology by Tong-Xian Liu of Northwest A&F University in Yangling, China, and colleagues.

The German , Blatella germanica, is the most common, and most despised, cockroach around the world. Like other insects, its exoskeleton is impregnated with a rich mix of molecules, including oily hydrocarbons that help keep the cockroach from drying out. A key feature that distinguishes male from female cockroaches is the abundance of one such , called 3,11-DimethylC29, which is chemically converted into a female sex pheromone. When the male senses the pheromone with his antennae, he raises his wings to expose a nutrient-containing gland. While the female feasts on its contents, the male copulates with her.

Like other long-chain fatty molecules, the pheromone precursor is synthesized in part by elongating a shorter hydrocarbon chain, through the action of a type of enzyme called an elongase. To better understand how that synthesis is regulated, the authors blocked the set of cockroach elongases using RNA interference. When one elongase, BgElo12, was knocked down, they found that the level of the pheromone was reduced and males were less attracted to the affected females.

Using RNAi knockdown, they showed that BgElo12 production was regulated by two insect sex differentiation studied previously in fruit flies. In male cockroaches, a gene called Doublesex repressed the production of the elongase, limiting the amount of pheromone produced. In females, however, another gene, called Transformer, blocked the effect of Doublesex, turning on the elongase gene. The authors showed that knocking down Transformer in females led again to limited production and to reduced sexual attractiveness.

“The identification of this pathway regulating female contact pheromones is valuable,” Liu said, “as it enriches our general understanding of the regulation of insect sexual behavior. Further, the elucidation of this key pathway in the cockroach in particular may well lead to better ways to control reproduction of this globally significant pest.”



More information:
Xiao-Jin Pei et al, Modulation of fatty acid elongation in cockroaches sustains sexually dimorphic hydrocarbons and female attractiveness, PLOS Biology (2021). DOI: 10.1371/journal.pbio.3001330

Citation:
Want to reduce cockroach sex? Block an enzyme (2021, July 27)
retrieved 28 July 2021
from https://phys.org/news/2021-07-cockroach-sex-block-enzyme.html

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