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1. Algal-fungal symbiosis leads to photosynthetic mycelium

   https://doi.org/10.7554/eLife.47815  

   Du, Zhi-Yan ; Zienkiewicz, Krzysztof ; Vande Pol, Natalie ; Ostrom, Nathaniel E ; Benning, Christoph ; Bonito, Gregory M ( July 2019 , eLife)

   Yeast, molds and other fungi are found in most environments across the world. Many of the fungi that live on land today form relationships called symbioses with other microbes. Some of these relationships, like those formed with green algae, are beneficial and involve the exchange carbon, nitrogen and other important nutrients. Algae first evolved in the sea and it has been suggested that symbioses with fungi may have helped some algae to leave the water and to colonize the land more than 500 million years ago. A fungus called Mortierella elongata grows as a network of filaments in soils and produces large quantities of oils that have various industrial uses. While the details of Mortierella’s life in the wild are still not certain, the fungus is thought to survive by gaining nutrients from decaying matter and it is not known to form any symbioses with algae. In 2018, however, a team of researchers reported that, when M. elongata was grown in the laboratory with a marine alga known as Nannochloropsis oceanica, the two organisms appeared to form a symbiosis. Both the alga and fungus produce oil, and when grown together the two organisms produced more oil than when the fungusmore »or algal cells were grown alone. However, it was not clear whether the fungus and alga actually benefit from the symbiosis, for example by exchanging nutrients and helping each other to resist stress. Du et al. – including many of the researchers involved in the earlier work – have now used biochemical techniques to study this relationship in more detail. The experiments found that there was a net flow of carbon from algal cells to the fungus, and a net flow of nitrogen in the opposite direction. When nutrients were scarce, algae and fungi grown in the same containers grew better than algae and fungi grown separately. Further, Mortierella only obtained carbon from living algae that attached to the fungal filaments and not from dead algae. Unexpectedly, further experiments found that when grown together over a period of several weeks or more some of the algal cells entered and lived within the filaments of the fungus. Previously, no algae had ever been seen to inhabit the living filaments of a fungus. These findings may help researchers to develop improved methods to produce oil from M. elongata and N. oceanica. Furthermore, this partnership provides a convenient new system to study how one organism can live within another and to understand how symbioses between algae and fungi may have first evolved.« less
2. Volvox and volvocine green algae

   https://doi.org/doi: 10.1186/s13227-020-00158-7  

   Umen, James G ( July 2020 , EvoDevo)

   The transition of life from single cells to more complex multicellular forms has occurred at least two dozen times among eukaryotes and is one of the major evolutionary transitions, but the early steps that enabled multicellular life to evolve and thrive remain poorly understood. Volvocine green algae are a taxonomic group that is uniquely suited to investigating the step-wise acquisition of multicellular organization. The multicellular volvocine species Volvox carteri exhibits many hallmarks of complex multicellularity including complete germ-soma division of labor, asymmetric cell divisions, coordinated tissue-level morphogenesis, and dimorphic sexes-none of which have obvious analogs in its closest unicellular relative, the model alga Chlamydomonas reinhardtii. Here, I summarize some of the key questions and areas of study that are being addressed with Volvox carteri and how increasing genomic information and methodologies for volvocine algae are opening up the entire group as an integrated experimental system for exploring the evolution of multicellularity and more.
3. Draft genome sequence of the Antarctic green alga Chlamydomonas sp. UWO241

   https://doi.org/https://doi.org/10.1016/j.isci.2021.102084  

   Zhang, Xi ; Cvetkovska, Marina ; Morgan-Kiss, Rachael ; Hüner, Norman PA ; Smith, David R ( January 2021 , iScience)

   Antarctica is home to an assortment of psychrophilic algae, which have evolved various survival strategies for coping with their frigid environments. Here, we explore Antarctic psychrophily by examining the ∼212 Mb draft nuclear genome of the green alga Chlamydomonas sp. UWO241, which resides within the water column of a perennially ice-covered, hypersaline lake. Like certain other Antarctic algae, UWO241 encodes a large number (≥37) of ice-binding proteins, putatively originating from horizontal gene transfer. Even more striking, UWO241 harbors hundreds of highly similar duplicated genes involved in diverse cellular processes, some of which we argue are aiding its survival in the Antarctic via gene dosage. Gene and partial gene duplication appear to be an ongoing phenomenon within UWO241, one which might be mediated by retrotransposons. Ultimately, we consider how such a process could be associated with adaptation to extreme environments but explore potential non-adaptive hypotheses as well.
4. A Functional K+ Channel from Tetraselmis Virus 1, a Member of the Mimiviridae

   https://doi.org/10.3390/v12101107  

   Kukovetz, Kerri ; Hertel, Brigitte ; Schvarcz, Christopher R. ; Saponaro, Andrea ; Manthey, Mirja ; Burk, Ulrike ; Greiner, Timo ; Steward, Grieg F. ; Van Etten, James L. ; Moroni, Anna ; et al ( October 2020 , Viruses)

   Potassium ion (K+) channels have been observed in diverse viruses that infect eukaryotic marine and freshwater algae. However, experimental evidence for functional K+ channels among these alga-infecting viruses has thus far been restricted to members of the family Phycodnaviridae, which are large, double-stranded DNA viruses within the phylum Nucleocytoviricota. Recent sequencing projects revealed that alga-infecting members of Mimiviridae, another family within this phylum, may also contain genes encoding K+ channels. Here we examine the structural features and the functional properties of putative K+ channels from four cultivated members of Mimiviridae. While all four proteins contain variations of the conserved selectivity filter sequence of K+ channels, structural prediction algorithms suggest that only two of them have the required number and position of two transmembrane domains that are present in all K+ channels. After in vitro translation and reconstitution of the four proteins in planar lipid bilayers, we confirmed that one of them, a 79 amino acid protein from the virus Tetraselmis virus 1 (TetV-1), forms a functional ion channel with a distinct selectivity for K+ over Na+ and a sensitivity to Ba2+. Thus, virus-encoded K+ channels are not limited to Phycodnaviridae but also occur in the members of Mimiviridae. The largemore »sequence diversity among the viral K+ channels implies multiple events of lateral gene transfer.« less
5. Marine Benthic Algae from Ni‘ihau and Adjacent Lehua Islet, Main Hawaiian Islands

   Tsuda, R.T. ; Abbott, I.A. ; Spalding, H.L. ; Giuseffi, L.M. ; Okano, R. ; Kennedy, B.H. ; Sherwood, A.R. ( July 2021 , Bishop Museum occasional papers)

   The published records of marine benthic algal species from the privately-owned island of Ni‘ihau (Hawaiian Islands) are represented by four species cited in abbott (1999) and abbott & Huisman (2004). The species consist of the red alga Chondrophycus dotyi (y. Saito) k.w. Nam [= Laurencia dotyi y. Saito], two brown algae Dictyopteris plagio - gramma (Montagne) Vickers and Distromium flabellatum womersley, and the green alga Pseudochlorodesmis parva w. J. gilbert [= Siphonogramen parvum (w.J. gilbert) I.a. abbott & Huisman]. Distromium flabellatum and Pseudochlorodesmis parva were collected in waters between Ni‘ihau and Lehua Islet. The paucity of algal records from Ni‘ihau is not surprising, very few collections have been made along its coastline because of its remoteness and general lack of access.