Deep-sea hydrothermal vents are hot springs on the ocean floor. Sea water penetrates into the ocean crust, becomes heated, and rises to the seafloor surface carrying dissolved nutrients. Around these vents, far from any sunlight, vibrant biological communities are found. Here, microbes play the role of primary producers through chemosynthesis — similar to the role that plants play on land through photosynthesis.

Researchers at Hokkaido University, in collaboration with colleagues at Woods Hole Oceanographic Institution, have been working on understanding microbial diversity at deep-sea hydrothermal environments on the East Pacific Rise based on microbe cultivation studies. They isolated a novel campylobacterial strain from a warm-water vent known as ‘Crab Spa’ and named it Hydrogenimonas cancrithermarum, after the site. Their findings were published in the journal International Journal of Systematic and Evolutionary Microbiology.

“Chemolithoautotrophic species of the class Campylobacteria (aka Epsilonproteobacteria) are recognized as an ecologically important bacterial group at hydrothermal vents, contributing to primary production,” explains Assistant Professor Sayaka Mino, first author of the paper and research group leader at the Faculty of Fisheries Sciences, Hokkaido University. “On the other hand, some members of this class, e.g., Helicobacter, Arcobacter, and Campylobacter, are also well known pathogens of humans and animals.”

Hydrogenimonas is known as the thermophilic (adapted to hot temperatures) genus that is most closely related to mesophilic and pathogenic genera in the class Campylobacteria. Yet, only two described species have so far been reported in this genus. The present study revealed that the new strain represents the first mesophilic (adapted to moderate temperatures) and sulfur-oxidizing bacterium in the genus, expanding the physiological and metabolic characteristics of the genus.

“The discovery of a mesophilic Hydrogenimonas species was unexpected. The strain likely provides us with the opportunity to investigate their evolutionary transition from a thermophilic to a mesophilic and from an autotrophic (capable of creating organic compounds) to a heterotrophic (consumes autotrophs to obtain organic compounds) lifestyle,” says Mino.

They further conducted a comprehensive comparative study of the genomes of Campylobacteria, and discovered that the genes responsible for the phosphotransacetylase-acetate kinase (Pta-AckA) pathway tend to be conserved between Hydrogenimonas and the mesophilic species that subsequently diverged from Hydrogenimonas, regardless of their metabolism and pathogenicity.

“The Pta-AkaA pathway has been reported in a pathogenic Campylobacter species to play an important role in colonizing hosts. While we don’t yet understand its specific role in the genus Hydrogenimonas, the acquisition of the genes might represent a key event that enabled their diversification from deep-sea vents to other environments,” says Dr. Stefan Sievert, leader of the research group at the Woods Hole Oceanographic Institution.

“Nowadays, studies of microbial diversity largely rely on cultivation-independent metagenomic sequencing approaches which produce massive amounts of data,” concludes Mino, “Yet, it is vital to remember the significance of cultivation, as shown by the isolation of the new strain that differs markedly from other members of the genus Hydrogenimonas.” The researchers will continue their efforts to discover new culturable species and thus contribute to the understanding of the diversity of Campylobacteria.

A new study by researchers at the John A. Burns School of Medicine (JABSOM) at the University of Hawaiʻi at Mānoa and Kapiʻolani Medical Center for Women & Children examined placentas donated by women who delivered in Hawaiʻi from 2006 to 2021, and found the presence of microplastic particles in the placenta.

Microplastics are visible to the naked eye, and examples can range from the plastic beads once found in exfoliating soaps, to particles from disintegrating plastic bags, to bits of plastic found in microwavable containers which are then inadvertently consumed by humans.

“We were shocked that these little pieces of plastic were getting across the mom’s gut and landing in the placenta,” said Men Jean Lee, an obstetrician and researcher at JABSOM and Kapiʻolani Medical Center. Lee, Rodrigo Weingrill and Johann Urschitz from UH Mānoa’s Institute for Biogenesis Research co-authored the research recently published in Environment International.

The researchers collected and studied 10 placentas in 2006, 2013 and 2021 and found the presence of microplastics grew each year.

• In 2006, 6 of the 10 placentas contained microplastics.
• In 2013, microplastics were found in 9 of the 10 placentas.
• In 2021, researchers found microplastics in all 10 placentas.

“We believe that the plastics may be floating around in food or being inhaled. It’s coming through our digestive fluids or lungs, and the particles are getting absorbed through the gut and traveling through the bloodstream, and then somehow collecting in the placenta during pregnancy,” Lee said. “The big question is, as it’s traveling through the placenta, can it get through the umbilical cord and then to the baby? We don’t know that right now.”

Link to global plastic production

We know that the rise in microplastics found in the placentas of Hawaiʻi mothers corresponds with the skyrocketing levels of global plastic production.

According to the Journal of Hazardous Materials, more than 6,000 megatons of plastic were produced in 2020. Less than 2,000 megatons were produced in 2000.

The big question is, as it’s traveling through the placenta, can it get through the umbilical cord and then to the baby? — Men Jean Lee

Lee believes HHawaiʻi’s remote location creates an added dependency on plastic.

“We’re the world’s most remote population center or island chain. We’re 2,300 miles from California and 4,000 miles from Japan,” Lee said. “For daily conveniences, we commonly use plastic wrap, plastic containers, plastic bags and single use water bottles.”

She suggests Hawaiʻi’s location in the center of the Pacific Ocean, tropical climate, and lack of recycling centers can exacerbate how these plastics are disintegrating or breaking down.

“The incineration of garbage, landfills and marine pollution affect our communities. When trash is being burned, dust particles are released, and can spread into the air we breathe,” Lee said. “In fact, we are concerned about how the debris from the recent Lahaina fires may contain microplastics and other chemical toxins in the remains of the fires. Meanwhile, we already know that sunlight, heat and salt can speed up the breakdown of these everyday plastics. I’ve noticed plastic bags, even shoes, wear out quickly in Hawaiʻi and turn to dust. I never experienced this when I was living back in New York.”

Can microplastics enter the fetus too?

Lee and the JABSOM researchers will continue their research, now focused on seeing if the microplastics can pierce the protection of the placenta and enter the fetus before birth.

“We’re not trying to scare people,” Lee said, but acknowledges there are other questions that still need to be answered. “What are the sources of maternal microplastics? What are the plastics doing in the mother’s body and the placenta? Are they benign, or are they crossing over to the fetal side into the umbilical cord that is connected to the baby? If they are getting to the other side, are they affecting fetal growth and what happens to the baby when he/she grows up?”

Immune-regulating brain cells known as microglia are known to play a role in the progression of Alzheimer’s disease (AD). A new study by investigators from Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, explores how the genetics of microglia contribute to neuroinflammation and, in turn, AD. The team revealed that a reduction of INPP5D, a gene found in microglia, results in neuroinflammation and increases the risk for AD. Their results, which have important implications for the design of microglia-centered therapeutics for Alzheimer’s disease and related disorders, are published in Nature Communications.

“We know that microglia play important roles in the healthy and diseased brain, but, in many cases the molecular mechanisms underlying this relationship are poorly understood,” said corresponding author Tracy Young-Pearse, PhD, from the Department of Neurology at Brigham and Women’s Hospital. “If we’re able to identify and understand the significance of specific genes that play a role in neuroinflammation, we can more readily develop effective, targeted therapeutics.”

Neuroinflammation is important to monitor in people with neurodegenerative diseases, but it can be difficult to detect, especially in the early stages of AD. The earlier neurologists can identify it, the earlier they can treat it. Microglia are clearly involved in the process of neuroinflammation, but there are many unanswered questions regarding the molecular pathways involved.

The team used a variety of experimental approaches to probe the relationship between levels of INPP5D and a specific type of brain inflammation, activation of the inflammasome. As part of their study, the team compared human brain tissue from patients with AD and a control group. They found lower levels of INPP5D in the tissues of patients with AD and when INPP5D was reduced, it activated inflammation. In parallel, they used living human brain cells derived from stem cells to study the intricate molecular interactions within microglia that mediate inflammatory processes with a reduction of INPP5D. These studies identified specific proteins that could be inhibited to block inflammasome activation in microglia.

Although the team’s work represents the most comprehensive analysis of INPP5D in the AD brain, it remains to be determined whether INPP5D should be targeted with therapeutics. The team notes that their findings suggest INPP5D activity in AD brains is complex and future studies are needed to understand if INPP5D can be targeted to prevent cognitive decline in patients with AD.

“Our results highlight an exciting promise for INPP5D, but some questions still remain,” said Young-Pearse. “Future studies examining the interaction between INPP5D activity and inflammasome regulation are essential to improve our understanding of microglia in AD and to help develop a comprehensive toolbox of therapeutics that can be deployed to treat each of the molecular roads that lead to AD.”