Nature and Science are renowned for publishing the highest-quality peer-reviewed research across all fields of science and technology, with articles that consistently rank among the most cited globally. While Cell focuses on experimental biology, its impact is equally profound. In this section, Tomáš Pánek provides a summary of the latest protistology research published in these prestigious journals over the past four months.
Evolutionary genomics of the emergence of brown algae as key components of coastal ecosystems by France Denoeud et al. (Cell)
Brown seaweeds are keystone species of coastal ecosystems, often forming extensive underwater forests, and are under considerable threat from climate change. Emergence of the brown algal lineage was associated with a marked gain of new orthologous gene families, enhanced protein domain rearrangement, increased horizontal gene transfer events, and the acquisition of novel signaling molecules and key metabolic pathways, the latter notably related to the biosynthesis of the alginate-based extracellular matrix, and halogen and phlorotannin biosynthesis. We show that brown algal genome diversification is tightly linked to phenotypic divergence, including changes in life cycle strategy and zoid flagellar structure. The study also showed that integration of large viral genomes has had a significant impact on brown algal genome content throughout the emergence of the lineage.
A gut commensal protozoan determines respiratory disease outcomes by shaping pulmonary immunity by Kyle Burrows et al. (Cell)
The underlying mechanisms used by the intestinal microbiota to shape disease outcomes of the host are poorly understood. Here, we show that the gut commensal protozoan, Tritrichomonas musculis, remotely shapes the lung immune landscape to facilitate perivascular shielding of the airways by eosinophils. Lung-specific eosinophilia requires a tripartite immune network between gut-derived inflammatory group 2 innate lymphoid cells and lung-resident T cells and B cells. This network exacerbates the severity of allergic airway inflammation while hindering the systemic dissemination of pulmonary Mycobacterium tuberculosis. The identification of protozoan DNA sequences in the sputum of patients with severe allergic asthma further emphasizes the relevance of commensal protozoa in human disease. Collectively, these findings demonstrate that a commensal protozoan tunes pulmonary immunity via a gut-operated lung immune network, promoting both beneficial and detrimental disease outcomes in response to environmental airway allergens and pulmonary infections.
Widespread occurrence and relevance of phosphate storage in foraminifera by N. Glock et al. (Nature)
Figure 3: Ultrastructure of A. veneta specimens.
Foraminifera are ubiquitous marine protists that intracellularly accumulate phosphate. Here we show that phosphate storage in foraminifera is widespread, from tidal flats to the deep sea. The total amount of intracellular phosphate stored in the benthic foraminifer Ammonia confertitesta in the Wadden Sea during a bloom is as high as around 5% of the annual consumption of phosphorus (P) fertilizer in Germany. Budget calculations for the Southern North Sea and the Peruvian Oxygen Minimum Zone indicate that benthic foraminifera may buffer riverine P runoff for approximately 37 days at the Southern North Sea and for about 21 days at the Peruvian margin. This indicates that these organisms are probably relevant for marine P cycling — they potentially buffer anthropogenic eutrophication in coastal environments. Phosphate is stored as polyphosphate in cell organelles that are potentially acidocalcisomes. Their metabolic functions can range from regulation of osmotic pressure and intracellular pH to calcium and energy storage. In addition, storage of energetic P compounds, such as creatine phosphate and polyphosphate, is probably an adaptation of foraminifera to oxygen depletion.
A multicellular developmental program in a close animal relative by M. Olivetta et al. (Nature)
By combining time-resolved imaging and transcriptomic profiling, an international team led by ISOP members, Omaya Dudin and John Burns, shows that single cells of the ichthyosporean Chromosphaera perkinsii — a close relative that diverged from animals about 1 billion years ago — undergo symmetry breaking and develop through cleavage divisions to produce a prolonged multicellular colony with distinct co-existing cell types. Their findings about the autonomous and palintomic developmental program of C. perkinsii hint that multicellular development typical for animals either is much older than previously thought or evolved convergently in ichthyosporeans.
Tissue spaces are reservoirs of antigenic diversity for Trypanosoma brucei by A.K. Beaver et al. (Nature)
Extended Data Fig. 1: T. brucei parasites are found in interstitial tissue spaces.
The protozoan parasite Trypanosoma brucei evades clearance by the host immune system through antigenic variation of its dense variant surface glycoprotein (VSG) coat, periodically ‘switching’ expression of the VSG using a large genomic repertoire of VSG-encoding genes. Recent studies of antigenic variation in vivo have focused near exclusively on parasites in the bloodstream, but research has shown that many, if not most, parasites reside in the interstitial spaces of tissues. We sought to explore the dynamics of antigenic variation in extravascular parasite populations using VSG-seq, a high-throughput sequencing approach for profiling VSGs expressed in populations of T. brucei. Here we show that tissues, not the blood, are the primary reservoir of antigenic diversity during both needle- and tsetse bite-initiated T. brucei infections, with more than 75% of VSGs found exclusively within extravascular spaces. We found that this increased diversity is correlated with slower parasite clearance in tissue spaces. Together, these data support a model in which the slower immune response in extravascular spaces provides more time to generate the antigenic diversity needed to maintain a chronic infection. Our findings reveal the important role that extravascular spaces can have in pathogen diversification.
