Author: admin

Perseverance is hitting the ‘open road’ on Mars like no other rover.

On June 19, the six-wheeled explorer officially completed the longest day trip of any robot vehicle on another planet.

In a single drive, the rover rolled over 411 meters of Mars’ rocky surface (more than a quarter mile).

Related: Perseverance Found a Zebra-Striped Rock on Mars, And NASA Is Excited

That may not sound like much, but compared to Curiosity and Opportunity, which inch along at a relative snail’s pace, Percy is a speed demon.

That’s because Perseverance has self-driving software, which can process and analyze images even while its wheels are turning.

By contrast, Curiosity and Opportunity need to stop, take images, and then process that information before deciding on a good path forward.

The ability to drive longer distances in a day opens up new possibilities for scientific studies on Mars.

Since Percy landed on the red planet in 2021, and completed its first hesitant test drive – a flawless 6.5-meter up-and-back – the rover has come far.

Its travels include an epic climb up a crater and the longest drive of any vehicle without human review on another planet – 700 meters of pure, ‘wind-in-the-hair’ freedom.

The reason for its recent long road trip has to do with the rocks that Percy is on a mission to collect.

For the past month and a half, the rover has searched for clay-bearing rocks on the Krokodillen plateau, which lies on the outer slopes of the Jezero crater rim.

If samples here are found to contain minerals known as ‘phyllosilicates’, it could mean abundant water may have existed here in the distant past. Phyllosilicates can also preserve remnants of organic materials from billions of years ago.

“If we find a potential biosignature here, it would most likely be from an entirely different and much earlier epoch of Mars evolution than the one we found last year in the crater with ‘Cheyava Falls’,” said Ken Farley, deputy project scientist for Perseverance, in May.

“The Krokodillen rocks formed before Jezero Crater was created, during Mars’ earliest geologic period, the Noachian, and are among the oldest rocks on Mars.”

On some parts of the plateau, however, Perseverance has found clay-bearing rocks that break easily when handled.

Picking out a solid sample is crucial. Only the best evidence will do.

“There are seven empty sample tubes remaining and a lot of open road in front of us,” said Perseverance acting project scientist Katie Stack Morgan in May.

In late June, the NASA team that drives Percy decided to turn the rover around, driving it back to a spot previously sampled, which contains the strongest clay signature of the bunch.

Hence the long drive.

Of all the rovers to roam other planets, the Opportunity rover, which has been on Mars since 2004, has racked up the most overall kilometers of driving, more than 40 km.

But Opportunity can’t move with the same finesse as Perseverance, and neither can Curiosity.

At this rate, it won’t be long until Perseverance takes the lead. Its current total distance sits at nearly 36 km.

Throughout Earth’s history, shifts in ocean redox influenced the bioavailability of trace metals, shaping the activity of microorganisms.

In Proterozoic oceans, the precipitation of copper (Cu) with sulfide was hypothesized to limit the bioavailability of Cu. This limitation may have suppressed microbial reduction of nitrous oxide (N2O), due to the Cu dependency of nitrous oxide reductase (Nos). It is thought that without this critical microbial sink, Proterozoic oceans were a significant net source of N₂O.

Here, we revisit this paradigm in light of recently derived ∼20-fold lower estimates for sulfide in Proterozoic seawater and an empirical evaluation of the potential for microbial N2O reduction under sulfidic conditions. Leveraging publicly available environmental metatranscriptomes, we infer active N₂O reduction from the detection of nosZ transcripts in multiple marine and lacustrine systems in which sulfide and Cu concentrations are analogous to those of the Proterozoic.

In controlled culture experiments, we demonstrate that the purple non-sulfur bacterium Rhodopseudomonas palustris can reduce N₂O at sulfide concentrations up to 100 µM, well above levels predicted for Proterozoic oceans. Based on trace metal speciation modeling, we suggest that Cu remains bioavailable under Proterozoic-like conditions as a dissolved CuHS0 complex.

Using phylogenetics, we infer that early N₂O reducers were probably anoxygenic phototrophs and performed N₂O reduction as dark metabolism. Collectively, these observations suggest microbial N₂O reduction occurs under euxinic conditions, implying that Proterozoic marine N₂O emissions were substantially lower than previously proposed.

Our conclusions inform our understanding of the microbial ecology in sulfidic waters, the early climate, and the search for extraterrestrial life.

Unrooted maximum likelihood phylogenetic tree of NosZ protein sequences. The phylogeny includes 595 nosZ sequences collected from genomes obtained from Zhu et al. (2019). Clade I (purple) and clade II (blue) nosZ sequences show distinct clade separation in the tree. Branch tips are colored by taxonomy at the level of phylum. Four phyla (Pseudomonadota, 360 Bacteroidota, Bacillota, and Euryarchaeota—boxed in the legend) forming large, notable clades within the tree are further distinguished by shading beyond branch tips. Metadata is shown for specific taxa with genomes represented in the tree. These include, phototrophy (phototrophs vs non-phototrophs), oxygen status (aerobes, anaerobes, facultative organisms, and microaerophiles), and presence or absence of nitrite reductase genes nirS and nirK in the 365 corresponding genomes. Halobacterium species are distinguished within the “phototrophy” category due to previous characterization of photobiology within the aerobic archaeon Halobacterium salinarum NRC-1 (DasSarma et al., 2001). Note that nirK, like nosZ, is a Cuusing enzyme and is distinguished in the tree. — biorxiv.org

Microbial N2O reduction in sulfidic waters: Implications for Proterozoic oceans, biorxiv.org

Astrobiology,

A ground-breaking study conducted by researchers from McGill University, the Lady Davis Institute for Medical Research (LDI) at the Jewish General Hospital, Princess Margaret Cancer Centre and MIT has identified a novel approach to combat aggressive breast cancers by retraining neutrophils, the body’s first responders, to directly kill tumour cells. This research offers new hope for patients with breast cancers that do not respond well to existing immunotherapies. 

Traditional immunotherapies primarily focus on reactivating tumour-specific T cells, which have limited effectiveness in breast cancers classified as immune cold – tumours that lack significant T cell infiltration. The new study, published in Science Advances, presents an alternative approach that harnesses the innate immune system by educating neutrophils to acquire tumoricidal properties. The researchers discovered that combining systemic Toll-like receptor (TLR) agonists with mitochondrial complex I inhibitors stimulates neutrophils to produce reactive oxygen species (ROS) and cytotoxic granules, thereby directly attacking breast cancer cells independently of cytotoxic T cell activity. 

According to John Heath, former postdoctoral fellow at the LDI now at the Princess Margaret Cancer Centre in Toronto and first author of the study, “Our research has shown that by leveraging the power of innate immunity, we can develop a new class of therapies that can effectively target and kill breast cancer cells, even in the absence of T cell inflammation.” 

“Our findings demonstrate that neutrophils can be reprogrammed to become potent anti-cancer agents in tumours that are otherwise resistant to current immunotherapies,” concurs Josie Ursini-Siegel, Principal Investigator and Director of the Molecular Oncology Group of the Cancer Research Axis at the LDI and lead author of the study. “This approach could open new avenues for treating aggressive breast cancers, particularly triple-negative breast cancer, which currently has limited treatment options due to the tumour’s ability to evade the immune system. This has great potential for patients who have limited treatment options and are in dire need of new and effective therapies.” 

The study highlights that TLR agonists elevate NF-κB signaling in neutrophils, increasing the production of secretory granules and components of the NADPH oxidase complex, necessary for a respiratory burst that elicits cytotoxic responses. Meanwhile, complex I inhibitors amplify this effect by potentiating the capacity of neutrophils to undergo a respiratory burst, leading to oxidative damage of breast cancer cells. Importantly, neutrophil depletion in experimental models abolished the anti-tumour effects, underscoring the critical role of these immune cells in the therapy’s success. This dual treatment approach not only mobilizes neutrophils into the tumour microenvironment but also enhances their cytotoxic functions, offering a promising new therapeutic strategy for immune cold breast tumours that have so far eluded effective immune-based treatments. 

The research also brings to light the importance of understanding the complex interactions between the tumour microenvironment and the immune system. By targeting key biological processes required for the survival of heterogeneous cancer cell populations, researchers can develop more effective therapies that abrogate the activation of a pro-tumorigenic immune microenvironment and instead engage novel modes of tumour immune surveillance.  

“Our findings have significant implications for the development of new treatments for breast cancer, particularly for patients with limited options,” said Ursini-Siegel. “It highlights the need for a multifaceted approach to cancer treatment, one that takes into account the complex interactions between the tumour and the immune system.” 

This research builds on the understanding that breast cancers often evade immune destruction through complex metabolic and inflammatory mechanisms, and it shifts the focus toward targeting innate immune cells rather than relying solely on adaptive immunity. While further research is needed to fully elucidate the mechanisms by which complex I inhibitors enhance neutrophil function, this study marks a significant step forward in precision oncology. 

About the study

Heath J, Ahn R, Sabourin V, Im YK, Rezzara SR, Annett A, Mirabelli C, Worme S, Maritan SM, Mourcos C, Lazaratos AM, Maldonado E, Shen YY, White FM, Kleinman CL, Siegel PM, Ursini-Siegel J. Complex I Inhibition combined with TLR Activation in the Breast Tumor Microenvironment Educates Cytotoxic Neutrophils. Sci. Adv.11,eadu5915(2025).DOI:10.1126/sciadv.adu5915.