Margaret McFall-Ngai | |
---|---|
Born | Margaret Jean McFall-Ngai |
Nationality | American |
Alma mater | University of San Francisco University of California, Los Angeles |
Known for | Host-bacterial symbiosis 'Design' of tissues that interact with light |
Scientific career | |
Fields | Biology |
Institutions | Caltech University of Hawaiʻi at Mānoa University of Wisconsin-Madison University of Southern California |
Thesis | (1983) |
Doctoral advisor | James Morin |
Other academic advisors | Joseph Horwitz George Somero |
Website | http://glowingsquid.org/ |
Margaret McFall-Ngai (born 1951) is an American animal physiologist and biochemist [1] best-known for her work related to the symbiotic relationship between Hawaiian bobtail squid, Euprymna scolopes and bioluminescent bacteria, Vibrio fischeri . Her research helped expand the microbiology field, primarily focused on pathogenicity and decomposition at the time, to include positive microbial associations. [2] [3] [4] She has been a professor at PBRC’s Kewalo Marine Laboratory [5] and director of the Pacific Biosciences Research Program at the University of Hawaiʻi at Mānoa. [6] However, in 2022, she moved her laboratory to Caltech, in Pasadena, California. [7]
McFall-Ngai spent her childhood in Southern California and attended Immaculate Heart High School in Los Angeles. [3] She attended college at the University of San Francisco, graduating in 1973 with a Bachelors of Science in biology. [3] She chose to further her education at the University of California, Los Angeles (UCLA) with doctoral advisor, James Morin, studying functional morphology and comparative physiology [8] while working as a teaching assistant/fellow. [5] Her graduate research took her to the central Philippines to study the relationship between bioluminescent bacteria found in the leiognathid light organ in fish, [9] [10] igniting her “lifelong interest” [3] in the blend of the two subjects. McFall-Ngai graduated with her Ph.D. in Biology in 1983 and went on to complete two postdoctoral fellowships. [6] For her first postdoc, she remained at UCLA working on protein biochemistry-biophysics [8] for the Jules Stein Eye Institute with advisor, Joseph Horwitz. [5] She then moved to San Diego to work with advisor George Somero on protein chemistry enzymology [8] at the Scripps Institute of Oceanography at the University of California, San Diego. [5] On the side McFall-Ngai had been exploring the Hawaiian bobtail squid as an alternative to the fish she had studied in graduate school and initiated what would become a career-long collaboration with microbiologist, Edward (Ned) Ruby, who had written his dissertation on the squids’ symbionts, Vibrio fischeri . [1]
In 1989 McFall-Ngai accepted a position and later received tenure at the University of Southern California in the Department of Biology and began breeding and studying the Hawaiian bobtail squid. [2] She and Ruby moved to Hawaii in 1996 to better study the squid-bacteria relationship, both accepting positions at Pacific Biomedical Research Center at the University of Hawaii. [6] In 2004, McFall-Ngai accepted a position as professor in the Department of Medical Microbiology and Immunology at the University of Wisconsin–Madison and the Eye Research institute. [11] She returned to Hawaii in 2015 when she accepted the position as director of the Pacific Biosciences Research Program [6] and professor at PBRC’s Kewalo Marine Laboratory at the University of Hawaiʻi at Mānoa. [5]
McFall-Ngai is a pioneer in the study of animal-bacterial symbiosis and known for her research of the Hawaiian bobtail squid, Euprymna scolopes , and its relationship with bacteria, Vibrio fischeri . She initially began her research in graduate school studying fish with a similar bioluminescent bacterial relationship, [9] [10] however, these fish proved difficult to grow in the lab. At a meeting, a visiting researcher from the University of Hawaii suggested she investigate the Hawaiian bobtail squid and its bioluminescent symbionts V. fischeri as an alternative. [1] McFall-Ngai found that the squid worked great in the lab with 8-10 pairs of squid generating roughly 60,000 juveniles a year. [2] To fully study this relationship, McFall-Ngai began collaborating with Edward (Ned) Ruby, a microbiologist who had written his dissertation on V. fischeri. [1]
Over the next three decades, McFall-Ngai, Ruby, and dozens of postdocs and students would investigate all aspects of the symbiotic relationship. [12] They worked to understand the development of the relationship at different stages of the squid life cycle, [13] [14] analyze the initiation of symbiosis in real time, [15] [16] and identify how the host selects its symbionts. [17] [18] [19] They learned that the squid follows a rhythmic pattern in which the bacteria are brightest when the squid hunt at night [20] and are then expelled at dawn. [21] [22] As analysis tools advanced, Ruby and McFall-Ngai were able to map transcriptional patterns and identify related genes that control the squid's rhythmic behaviors and symbiotic relationship. [23] [24] The sum of their Hawaiian bobtail squid research is an extremely well defined model organism fit for studying bacterial symbioses, light interacting tissues, and cephalopod development. [25]
Source: [5]
An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualistic relationship. Examples are nitrogen-fixing bacteria, which live in the root nodules of legumes, single-cell algae inside reef-building corals, and bacterial endosymbionts that provide essential nutrients to insects.
A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.
Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in diverse organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, dinoflagellates and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.
Bobtail squid are a group of cephalopods closely related to cuttlefish. Bobtail squid tend to have a rounder mantle than cuttlefish and have no cuttlebone. They have eight suckered arms and two tentacles and are generally quite small.
Aliivibrio fischeri is a Gram-negative, rod-shaped bacterium found globally in marine environments. This bacterium grows most effectively in water with a salt concentration at around 20g/L, and at temperatures between 24 and 28°C. This species is non-pathogenic and has bioluminescent properties. It is found predominantly in symbiosis with various marine animals, such as the Hawaiian bobtail squid. It is heterotrophic, oxidase-positive, and motile by means of a tuft of polar flagella. Free-living A. fischeri cells survive on decaying organic matter. The bacterium is a key research organism for examination of microbial bioluminescence, quorum sensing, and bacterial-animal symbiosis. It is named after Bernhard Fischer, a German microbiologist.
The Vibrionaceae are a family of Pseudomonadota given their own order, Vibrionales. Inhabitants of fresh or salt water, several species are pathogenic, including the type species Vibrio cholerae, which is the agent responsible for cholera. Most bioluminescent bacteria belong to this family, and are typically found as symbionts of deep-sea animals.
Aposymbiosis occurs when symbiotic organisms live apart from one another. Studies have shown that the lifecycles of both the host and the symbiont are affected in some way, usually negative, and that for obligate symbiosis the effects can be drastic. Aposymbiosis is distinct from exsymbiosis, which occurs when organisms are recently separated from a symbiotic association. Because symbionts can be vertically transmitted from parent to offspring or horizontally transmitted from the environment, the presence of an aposymbiotic state suggests that transmission of the symbiont is horizontal. A classical example of a symbiotic relationship with an aposymbiotic state is the Hawaiian bobtail squid Euprymna scolopes and the bioluminescent bacterium Aliivibrio fischeri. While the nocturnal squid hunts, the bacteria emit light of similar intensity of the moon which camouflages the squid from predators. Juveniles are colonized within hours of hatching and Aliivibrio must outcompete other bacteria in the seawater through a system of recognition and infection.
Euprymna hyllebergi, the Thai bobtail squid is a species of squid belonging to the family Sepiolidae and is native to the eastern Indian Ocean. It is commonly found in the Andaman Sea of Thailand and in the Gulf of Thailand. E. hyllebergi can grow up to 35mm in mantle length and can be found in depths as low as 74m. The Thai bobtail squid is covered in chromatophores, which are pigmented cells that can expand or contract and are used to camouflage the squid. The normal lifespan of the Thai bobtail squid is between 92 and 122 days for males and between 80 and 113 days for females.
Euprymna scolopes, also known as the Hawaiian bobtail squid, is a species of bobtail squid in the family Sepiolidae native to the central Pacific Ocean, where it occurs in shallow coastal waters off the Hawaiian Islands and Midway Island. The type specimen was collected off the Hawaiian Islands and is located at the National Museum of Natural History in Washington, D.C.
In biology, an autoinducer is a signaling molecule that enables detection and response to changes in the population density of bacterial cells. Synthesized when a bacterium reproduces, autoinducers pass outside the bacterium and into the surrounding medium. They are a key component of the phenomenon of quorum sensing: as the density of quorum-sensing bacterial cells increases, so does the concentration of the autoinducer. A bacterium’s detection of an autoinducer above some minimum threshold triggers altered gene expression.
Reflectins are a family of intrinsically disordered proteins evolved by a certain number of cephalopods including Euprymna scolopes and Doryteuthis opalescens to produce iridescent camouflage and signaling. The recently identified protein family is enriched in aromatic and sulfur-containing amino acids, and is utilized by certain cephalopods to refract incident light in their environment. The reflectin protein is responsible for dynamic pigmentation and iridescence in organisms. This process is "dynamic" due to its reversible properties, allowing reflectin to change an organism's appearance in response to external factors such as needing to camouflage or send warning signals.
Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength.
The hologenome theory of evolution recasts the individual animal or plant as a community or a "holobiont" – the host plus all of its symbiotic microbes. Consequently, the collective genomes of the holobiont form a "hologenome". Holobionts and hologenomes are structural entities that replace misnomers in the context of host-microbiota symbioses such as superorganism, organ, and metagenome. Variation in the hologenome may encode phenotypic plasticity of the holobiont and can be subject to evolutionary changes caused by selection and drift, if portions of the hologenome are transmitted between generations with reasonable fidelity. One of the important outcomes of recasting the individual as a holobiont subject to evolutionary forces is that genetic variation in the hologenome can be brought about by changes in the host genome and also by changes in the microbiome, including new acquisitions of microbes, horizontal gene transfers, and changes in microbial abundance within hosts. Although there is a rich literature on binary host–microbe symbioses, the hologenome concept distinguishes itself by including the vast symbiotic complexity inherent in many multicellular hosts.
Bioluminescent bacteria are light-producing bacteria that are predominantly present in sea water, marine sediments, the surface of decomposing fish and in the gut of marine animals. While not as common, bacterial bioluminescence is also found in terrestrial and freshwater bacteria. These bacteria may be free living or in symbiosis with animals such as the Hawaiian Bobtail squid or terrestrial nematodes. The host organisms provide these bacteria a safe home and sufficient nutrition. In exchange, the hosts use the light produced by the bacteria for camouflage, prey and/or mate attraction. Bioluminescent bacteria have evolved symbiotic relationships with other organisms in which both participants benefit each other equally. Bacteria also use luminescence reaction for quorum sensing, an ability to regulate gene expression in response to bacterial cell density.
A microbiome is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps et al. as "a characteristic microbial community occupying a reasonably well-defined habitat which has distinct physio-chemical properties. The term thus not only refers to the microorganisms involved but also encompasses their theatre of activity". In 2020, an international panel of experts published the outcome of their discussions on the definition of the microbiome. They proposed a definition of the microbiome based on a revival of the "compact, clear, and comprehensive description of the term" as originally provided by Whipps et al., but supplemented with two explanatory paragraphs, the first pronouncing the dynamic character of the microbiome, and the second clearly separating the term microbiota from the term microbiome.
Microbial symbiosis in marine animals was not discovered until 1981. In the time following, symbiotic relationships between marine invertebrates and chemoautotrophic bacteria have been found in a variety of ecosystems, ranging from shallow coastal waters to deep-sea hydrothermal vents. Symbiosis is a way for marine organisms to find creative ways to survive in a very dynamic environment. They are different in relation to how dependent the organisms are on each other or how they are associated. It is also considered a selective force behind evolution in some scientific aspects. The symbiotic relationships of organisms has the ability to change behavior, morphology and metabolic pathways. With increased recognition and research, new terminology also arises, such as holobiont, which the relationship between a host and its symbionts as one grouping. Many scientists will look at the hologenome, which is the combined genetic information of the host and its symbionts. These terms are more commonly used to describe microbial symbionts.
Karen Visick is an American microbiologist and expert in bacterial genetics known for her work on the role of bacteria to form biofilm communities during animal colonization. She conducted doctoral research with geneticist Kelly Hughes at the University of Washington, where she identified a key regulatory checkpoint during construction of the bacterial flagellum. She conducted postdoctoral research on development of the Vibrio fischeri-Euprymna scolopes symbiosis with Ned Ruby at University of Southern California and University of Hawaiʻi. The bacteria are bioluminescent and provide light to the host. Visick and Ruby revealed that bacteria that do not produce light exhibit a defect during host colonization.
All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.
Marine prokaryotes are marine bacteria and marine archaea. They are defined by their habitat as prokaryotes that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. All cellular life forms can be divided into prokaryotes and eukaryotes. Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, whereas prokaryotes are the organisms that do not have a nucleus enclosed within a membrane. The three-domain system of classifying life adds another division: the prokaryotes are divided into two domains of life, the microscopic bacteria and the microscopic archaea, while everything else, the eukaryotes, become the third domain.
Jamie S. Foster is an American astrobiologist, microbiologist, and academic. She is an Assistant Director of the Astraeus Space Institute and a professor at the Department of Microbiology and Cell Science, and Genetics and Genomes Graduate Program at the University of Florida.