Friday, January 24, 2025

Evolution without sex: How mites have survived for millions of years

University of Cologne

Scanning electron microscopy images of Platynothrus peltifer — image:
The asexual oribatid mite *Platynothrus peltifer* reproduces parthenogenetically: Mothers produce daughters from unfertilized eggs, resulting in a population consisting entirely of females.
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Credit: Dr Mark Maraun und Dr Katja Wehner

In collaboration with colleagues from international partner institutions, researchers at the University of Cologne have investigated the asexual reproduction of oribatid mites using genome sequencing techniques. They show that the key to evolution without sex in oribatid mites may lie in the independent evolution of their two chromosome copies – a phenomenon known as the ‘Meselson effect’. The research team identified various mechanisms that may contribute to the genetic diversity of the chromosome sets, potentially enabling the long-term persistence of the mite.

Like humans, oribatid mites possess two sets of chromosomes. However, the asexual oribatid mite Platynothrus peltifer reproduces parthenogenetically: Mothers produce daughters from unfertilized eggs, resulting in a population consisting entirely of females. Using single-individual sequencing, the researchers analysed the accumulated differences between the chromosome copies for the first time and evaluated their significance for the mite’s survival. The study titled ‘Chromosome-scale genome dynamics reveal signatures of independent haplotype evolution in the ancient asexual mite Platynothrus peltifer’, funded by the German Research Foundation (DFG), was published in Science Advances.

Sex is the driving force of evolution: It promotes genetic diversity and helps organisms to adapt more quickly to changing environmental conditions. Without sex, however, organisms risk genetic stagnation and extinction – at least according to prevailing evolutionary theory. Yet, the oribatid mite Platynothrus peltifer challenges this paradigm: It has existed for over 20 million years – entirely without sex. The asexual oribatid mites produce their female offspring from unfertilized eggs without males. Males are absent or extremely rare and do not contribute to the gene pool. Depending on the mechanism restoring the diploid set of chromosomes, offspring can inherit either all or some of the mother’s gene variants (alleles). They can therefore be ‘full clones’ of the mother.

In the oribatid mite, the two copies of the chromosome sets evolve independently of each other, allowing new genetic variants to emerge while also retaining important information. The team observed notable differences in gene expression – in other words, which copies of the genes are active and to what extent. These differences enable rapid responses to environmental changes and provide a selective advantage.

Another mechanism contributing to genetic diversity is horizontal gene transfer (HGT), i.e. the movement of genetic material outside of the confined barriers of sexual reproduction. “Horizontal gene transfer can be thought of as adding new tools to an existing toolbox. Some of these genes seem to help the mite to digest cell walls, thus expanding its food spectrum,” explained the study’s first author, Dr Hüsna Öztoprak from the University of Cologne’s Institute of Zoology.

Additionally, transposable elements (TE) or ‘jumping genes’, play an important role. TEs move within the genome like chapters in a book that are rearranged to change the course of the plot. The fact that the activity of these TEs differs between the two chromosome copies is particularly exciting. While they are active on one copy and thus can cause dynamic changes, they tend to remain rather inactive on the other.

The study provides new insights into the survival strategies of asexual organisms. Asexual evolution is supported by various sources of genetic diversity, to which the research team draws attention in the study. “In future research projects, we would like to find out whether there are additional mechanisms that might be important for evolution without sex,” said Dr Jens Bast, Emmy Noether group leader at the University of Cologne.

Journal

Science Advances

DOI

10.1126/sciadv.adn0817

Method of Research

Observational study

Subject of Research

Animals

Article Title

Chromosome-scale genome dynamics reveal signatures of independent haplotype evolution in the ancient asexual mite Platynothrus peltifer’

Article Publication Date

24-Jan-2025

What to do with aging solar panels?

Texas A&M University

The National Science Foundation Convergence Accelerator Program has granted $5 million dollars to Phase 2 of the project “Securing critical material supply chains by enabling phOtovoltaic circuLARity (SOLAR).”

SOLAR’s goal is to proactively ensure circularity of solar panels by providing solutions to barriers throughout the end-to-end supply chain. The intent is to make solar panels recyclable and find a solution to remanufacturing them at a competitive cost. Achieving this will help promote a clean and resilient energy system in the United States.

The three-year project is led by Battelle Memorial Institute with partner organizations including Texas A&M University’s Energy Institute. The interdisciplinary team provides the expertise needed to address muti-faceted issues related to solar manufacturing supply chain resilience.

Texas A&M’s participation will be led by Texas A&M Energy Institute’s associate director of Supply Chain Resilience and Sustainability and the Harvey Hubbell Professor of Industrial Distribution, Dr. Eleftherios Iakovou, with the director of the Texas A&M Energy Institute and distinguished professor in the Department of Chemical Engineering, Dr. Stratos Pistikopoulos.

The Energy Institute’s role in SOLAR is focused on advancing reverse logistics models and next-generation data-driven supply chains specifically for recycling solar panels and reusing their critical materials, such as silicon and silver.

“We are enhancing the competitiveness of the U.S. solar manufacturing supply chain by retrieving rare earth minerals from solar panels that are decommissioned, either because they break or have reached end of life,” Iakovou said. “These precious rare earth minerals have the potential to be used in other critical and increasingly reshored supply chains, developing a circular economy for solar panels, while further enhancing the overall resilience and sustainability of the nation’s energy and manufacturing supply chains within the new geopolitical landscape.”

According to Pistikopoulos, transitioning the solar industry towards a circular economy by establishing sustainable recycling pathways for solar panels involves three core areas: sorting, upcycling, and logistics.

Sorting focuses on creating field guides, developing workforce skills and deploying sensors for panel damage detection.
Upcycling is the recovery and purification of critical materials such as silicon.
Logistics is the component responsible for creating user-friendly modeling tools to streamline supply chain management for recyclable materials.

Together, these three core areas form a comprehensive approach to address the complex challenges in the solar panel ecosystem.

“Our contribution emphasizes the development of reverse supply chain logistics and decision-making frameworks, facilitating a more sustainable end-of-life management,” Pistikopoulos said. “By addressing complex logistics and recycling challenges, we aim to enable efficient pathways for re-integrating critical materials into the economy.”

During the next three years, the SOLAR team will conduct yearly evaluations to assess progress. They will also integrate new insights to ensure they build on previous findings from Phase 1 while adapting to technological advances and market conditions.

“The knowledge, tools, and technologies we are developing here will play a crucial role in shaping a future where solar energy can be both renewable and circular, ultimately contributing to a resilient and secure materials supply chain for the U.S.,” Pistikopoulos said. “As solar panel deployment continues to accelerate, establishing a sustainable and economically viable end-of-life management in terms of reducing waste and regaining important materials is essential.”

By Jennifer Nichols and Raven Wuebker, Texas A&M Engineering

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Collaboration to develop sorghum hybrids to reduce synthetic fertilizer use and farmer costs

Donald Danforth Plant Science Center

image:
Veena Veena, PhD, MBA, principal investigator and director of the Plant Transformation Core Facility at the Donald Danforth Plant Science Center
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Credit: Donald Danforth Plant Science Center

ST. LOUIS, MO, January 24, 2025 - A new collaborative research team of leading plant scientists are developing sorghums with nitrogen-saving traits by utilizing the genetic diversity of wild relatives to improve resilience and productivity for grain sorghum producers.

The project is part of a $38 million investment in nine projects by the U.S. Department of Energy, DOE, Advanced Research Projects Agency-Energy, ARPA-E, to develop advanced technologies for plants to increase nitrogen-use efficiency and reduce nitrogen pollution from U.S. bioenergy feedstocks.

Veena Veena, PhD, MBA, principal investigator and director of the Plant Transformation Core Facility at the Donald Danforth Plant Science Center is serving as a Co-PI on the project. Veena will provide specialized knowledge in genome modification technologies and will utilize advanced genetic engineering techniques to develop sorghum lines with enhanced traits, including improved nutrient cycling, increased resilience, productivity, drought resistance and.

The project is led by Sakiko Okumoto, PhD, AgriLife Research plant physiologist and associate professor at Texas A&M College of Agriculture and Life Sciences Department of Soil and Crop Sciences.

The Texas A&M AgriLife Research team has been studying the potential of biological nitrification inhibition, BNI, a unique trait found in wild relatives, through previous research efforts to reduce fertilizer application and enhance environmental benefits.

The technologies developed in the project will target the grain ethanol sorghum market, Okumoto said. By leveraging genetic diversity from wild varieties, new sorghum hybrids will offer unique opportunities for both growers and sorghum grain buyers to reduce costs by lowering fertilizer application levels.

Co-PIs at Texas A&M include, Nithya Rajan, PhD., Center for Greenhouse Gas Management in Agriculture and Forestry director, crop physiologist and professor; Bill Rooney, PhD., sorghum breeder, professor and Borlaug-Monsanto Chair for Plant Breeding and International Crop Improvement; Sanjay Antony-Babu, PhD., microbiologist and assistant professor in the Department of Plant Pathology and Microbiology; and Aniruddha Datta, PhD., professor in the Department of Electrical and Computer Engineering in the College of Engineering.

About the Donald Danforth Plant Science Center
Founded in 1998, the Donald Danforth Plant Science Center is a not-for-profit research institute with a mission to improve the human condition through plant science. Research, education, and outreach aim to have impact at the nexus of food security and the environment and position the St. Louis region as a world center for plant science. The Center’s work is funded through competitive grants from many sources, including the National Science Foundation, National Institutes of Health, U.S. Department of Energy, U.S. Agency for International Development, and the Bill & Melinda Gates Foundation, and through the generosity of individual, corporate, and foundation donors.

For more information contact:
Karla Roeber, Vice President, Public and Government Affairs, kroeber@danforthcenter.org

New twist in mystery of dinosaurs' origin

University College London

An artist’s illustration of Nyasasaurus — image:
Nyasasaurus could be the earliest known dinosaur, or else a close relative of early dinosaurs.
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Credit: Mark Witton/The Trustees of the Natural History Museum, London

The remains of the earliest dinosaurs may lie undiscovered in the Amazon and other equatorial regions of South America and Africa, suggests a new study led by UCL (University College London) researchers.

Currently, the oldest known dinosaur fossils date back about 230 million years and were unearthed further south in places including Brazil, Argentina and Zimbabwe. But the differences between these fossils suggest dinosaurs had already been evolving for some time, pointing to an origin millions of years earlier.

The new study, published in the journal Current Biology, accounted for gaps in the fossil record and concluded that the earliest dinosaurs likely emerged in a hot equatorial region in what was then the supercontinent Gondwana – an area of land that encompasses the Amazon, Congo basin, and Sahara Desert today.

Lead author and PhD student Joel Heath (UCL Earth Sciences and the Natural History Museum, London) said: “Dinosaurs are well studied but we still don’t really know where they came from. The fossil record has such large gaps that it can’t be taken at face value.

“Our modelling suggests that the earliest dinosaurs might have originated in western, low-latitude Gondwana. This is a hotter and drier environment than previously thought, made up of desert- and savannah-like areas.

“So far, no dinosaur fossils have been found in the regions of Africa and South America that once formed this part of Gondwana. However, this might be because researchers haven’t stumbled across the right rocks yet, due to a mix of inaccessibility and a relative lack of research efforts in these areas.”

The modelling study drew on fossils and evolutionary trees of dinosaurs and their close reptile relatives, as well as the geography of the period. It accounted for gaps in the fossil record by treating areas of the globe where no fossils had been found as missing information rather than areas where no fossils exist.

Initially, early dinosaurs were vastly outnumbered by their reptile cousins.

These included the ancestors of crocodiles, the pseudosuchians (an abundant group including enormous species up to 10 metres long), and pterosaurs, the first animals to evolve powered flight (flying by flapping wings rather than gliding), who grew as big as fighter jets.

By contrast, the earliest dinosaurs were much smaller than their descendants – more the size of a chicken or dog than a Diplodocus. They walked on two legs (were bipedal) and most are thought to have been omnivores.

Dinosaurs became dominant after volcanic eruptions wiped out many of their reptile relatives 201 million years ago.

The new modelling results suggested that dinosaurs as well as other reptiles may have originated in low-latitude Gondwana, before radiating outwards, spreading to southern Gondwana and to Laurasia, the adjacent northern supercontinent that later split into Europe, Asia and North America.

Support for this origin comes from the fact it is a midpoint between where the earliest dinosaurs have been found in southern Gondwana and where the fossils of many of their close relatives have been discovered to the north in Laurasia.

As there is uncertainty about how the most ancient dinosaurs were related to one another and to their close relatives, the researchers ran their model on three proposed evolutionary trees.

They found strongest support for a low-latitude Gondwanan origin of the dinosaurs in the model that counted silesaurids, traditionally regarded as cousins of dinosaurs but not dinosaurs themselves, as ancestors of ornithischian dinosaurs.

Ornithischians, one of the three main dinosaur groups that later included plant eaters Stegosaurus and Triceratops, are mysteriously absent from the fossil record of these early years of the dinosaur era. If silesaurids are the ancestors of ornithischians, this helps to fill in this gap in the evolutionary tree.

Senior author Professor Philip Mannion (UCL Earth Sciences) said: “Our results suggest early dinosaurs may have been well adapted to hot and arid environments. Out of the three main dinosaur groups, one group, sauropods, which includes the Brontosaurus and the Diplodocus, seemed to retain their preference for a warm climate, keeping to Earth’s lower latitudes.

“Evidence suggests the other two groups, theropods and ornithischians, may have developed the ability to generate their own body heat some millions of years later in the Jurassic period, allowing them to thrive in colder regions, including the poles.”

The earliest known dinosaurs include Eoraptor, Herrerasaurus, Coelophysis, and Eodromaeus.