Michele Nishiguchi

• PhD
• Professor (Full) at University of California, Merced

Symbiotic marine bacteria that are transmitted through the environment are susceptible to abiotic factors (salinity, temperature, physical barriers) that can influence their ability to colonize their specific hosts. Given that many symbioses are driven by host specificity, environmentally transmitted symbionts are more susceptible to extrinsic fact...

Many female squids and cuttlefishes have a symbiotic reproductive organ called the accessory nidamental gland (ANG) that hosts a bacterial consortium involved with egg defense against pathogens and fouling organisms. While the ANG is found in multiple cephalopod families, little is known about the global microbial diversity of these ANG bacterial s...

Synopsis Few animal groups can claim the level of wonder that cephalopods instill in the minds of researchers and the general public. Much of cephalopod biology, however, remains unexplored: the largest invertebrate brain, difficult husbandry conditions, and complex (meta-)genomes, among many other things, have hindered progress in addressing key q...

Symbiosis refers to the interactions between different organisms. It is usually categorized into three main associations, which include mutualism, parasitism, and commensalism. Here, we define all types and the specialized forms that separate them from one another. Symbiosis typically involves an organism known as the symbiont residing within anoth...

Teaching students at all levels of education has undergone extensive changes, particularly in the past decade. Our present student population has transformed dramatically in the 21st century due to the changing demographics of the nation, an increasing use of technology both inside and outside the classroom, along with an expectation to have inform...

The Vibrio fischeri–Euprymna scolopes symbiosis has become a powerful model for the study of specificity, initiation, and maintenance between beneficial bacteria and their eukaryotic partner. In this invertebrate model system, the bacterial symbionts are acquired every generation from the surrounding seawater by newly hatched squid. These symbionts...

Biocrusts harbor soil-surface communities composed of autotrophic and heterotrophic microbiota that affect nutrient cycling, plant performance, soil hydrology and stability within drylands. Biocrust community composition is mostly thought to be driven by abiotic factors, but the structure of the bacteria, fungi, protist, and microfauna taxa are rar...

Editorial on the Research Topic Symbiosis in a Changing Environment

Due to their large size (∼3–5 Gb) and high repetitive content, the study of cephalopod genomes has historically been problematic. However, with the recent sequencing of several cephalopod genomes, including the Hawaiian bobtail squid (Euprymna scolopes), whole-genome studies of these molluscs are now possible. Of particular interest are the sepioli...

Symbiotic bacteria in the Vibrionaceae are a dynamic group of γ-Proteobacteria that are commonly found throughout the world. Although they primarily are free-living in the environment, they can be commonly found associated with various Eukarya, either as beneficial or pathogenic symbionts. Interestingly, this dual lifestyle (free-living or in symbi...

Abiotic variation can influence the evolution of specific phenotypes that contribute to the diversity of bacterial strains observed in the natural environment. Environmentally transmitted symbiotic bacteria are particularly vulnerable to abiotic fluctuations, given that they must accommodate the transition between the free-living state and the host...

Vibrio fischeri is a cosmopolitan marine bacterium that oftentimes displays different colony morphologies, switching from a smooth to a wrinkly phenotype in order to adapt to changes in the environment. This wrinkly phenotype has also been associated with increased biofilm formation, an essential characteristic for V. fischeri to adhere to substrat...

For micro-organisms cycling between free-living and host-associated stages, where reproduction occurs in both of these lifestyles, an interesting inquiry is whether evolution during the free-living stage can be positively pleiotropic to microbial fitness in a host environment. To address this topic, the squid host Euprymna tasmanica and the marine...

Symbiosis between southern dumpling squid, Euprymna tasmanica (Cephalopoda: Sepiolidae), and its luminescent symbiont, the bacterium Vibrio fischeri, provides an experimentally tractable system to examine interactions between the eukaryotic host and its bacterial partner. Luminescence emitted by the symbiotic bacteria provides light for the squid i...

Synopsis The goal of the Society for Integrative and Comparative Biology’s Broadening Participation Committee (SICB BPC) is to increase the number of underrepresented group (URG) members within the society and to expand their capabilities as future researchers and leaders within SICB. Our short-term 10-year goal was to increase the recruitment and...

N. lolii is a naturally occurring fungus whose complete cycle occurs within perennial ryegrass. The fungus grows between the cells of the host plant drawing nutrients from it, and in return, the endophyte produces chemical compounds that provide resistance to drought, pests, and protection from overgrazing. Therefore, the aim of this study was to g...

Multiple symbiotic and free-living Vibrio spp. grow as a form of microbial community known as a biofilm. In the laboratory, methods to quantify Vibrio biofilm mass include crystal violet staining, direct colony-forming unit (CFU) counting, dry biofilm cell mass measurement, and observation of development of wrinkled colonies. Another approach for b...

Environmentally-transmitted symbiotic bacteria must balance selective pressures of host specificity and the abiotic environment. Here, we investigate genomes of three strains of Vibrio fischeri isolated from three different squid species living in various temperature and salinity environments. These sequences were compared to others from symbiotic...

Background: A number of bacterial species are capable of growing in various life history modes that enable their survival and persistence in both planktonic free-living stages as well as in biofilm communities. Mechanisms contributing to either planktonic cell or biofilm persistence and survival can be carefully delineated using multiple different...

The Vibrionaceae are a genetically and metabolically diverse family living in aquatic habitats with a great propensity toward developing interactions with eukaryotic microbial and multicellular hosts (as either commensals, pathogens, and mutualists). The Vibrionaceae frequently possess a life history cycle where bacteria are attached to a host in o...

The monogeneric family Idiosepiidae (Mollusca: Cephalopoda: Idiosepiida) contains the smallest living representatives of squid. Sexual dimorphism, presence of an adhesive organ on the dorsal mantle integument, lack of fully developed tentacles on hatching, and ability to produce large quantities of eggs relative to their body size during reproducti...

The monogeneric family Idiosepiidae (Mollusca: Cephalopoda: Idiosepiida) contains the smallest living representatives of squid. Sexual dimorphism, presence of an adhesive organ on the dorsal mantle integument, lack of fully developed tentacles on hatching, and ability to produce large quantities of eggs relative to their body size during reproducti...

Environmentally acquired beneficial associations are comprised of a wide variety of symbiotic species that vary both genetically and phenotypically, and therefore have differential colonization abilities, even when symbionts are of the same species. Strain variation is common among conspecific hosts, where subtle differences can lead to competitive...

Bobtail squids of the genus 𝐸𝑢𝑝𝑟𝑦𝑚𝑛𝑎 are small in size with a benthic habit. Such small size results in their insignificance in fisheries and aquaculture focused for human consumption. The unique ability of the voluntary adhesion system and symbiotic bacteria used for bioluminescence is now a primary research focus with potential industrial and bio...

Vibrio fischeri isolated from Euprymna scolopes (Cephalopoda: Sepiolidae) was used to create 24 lines that were serially passaged through the non-native host Euprymna tasmanica for 500 generations. These derived lines were characterized for biofilm formation, swarming motility, carbon source utilization, and in vitro bioluminescence. Phenotypic ass...

The monogeneric family Idiosepiidae (Mollusca: Cephalopoda: Idiosepiida) contains the smallest living representatives of squid. Sexual dimorphism, presence of an adhesive organ on the dorsal mantle integument, lack of fully developed tentacles on hatching, and ability to produce large quantities of eggs relative to their body size during reproducti...

Catalase activity through hydrogen peroxide decomposition in a 1 mM bulk solution above Vibrio fischeri (-Protebacteria-Vibrionaceae) bacterial biofilms of either symbiotic or free-living strains was studied in real time by scanning electrochemical microscopy (SECM). The catalase activity, in units of µmoles hydrogen peroxide decomposed per minute...

Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be contro...

Variation in sperm morphology is widespread throughout the metazoa, and has been used as an informative taxonomic character. Electron microscopy techniques allowed spermatozoa ultrastructure analyses of three sepiolid squid species with restricted habitats at different geographical locations —Sepiola atlantica from the Northeastern Atlantic, Euprym...

Bioluminescent bacteria from the g-Proteobacterial family Vibrionaceae share mutualistic symbiosis with a variety of sepiolid and loliginid squids (Mollusca: Cephalopoda). The bacteria are housed in a bilobed light organ within the mantle cavity of the host squid . Although the association between squid hosts and Vibrio bacteria is specific, the di...

Loliginid and sepiolid squid light organs are known to host a variety of bacterial species from the family Vibrionaceae, yet little is known about the species diversity and characteristics among different host squids. Here we present a broad-ranging molecular and physiological analysis of the bacteria colonizing light organs in loliginid and sepiol...

The symbiosis between marine bioluminescent Vibrio bacteria and the sepiolid squid Euprymna is a model for studying animal-bacterial Interactions. Vibrio symbionts native to particular Euprymna species are competitively dominant, capable of outcompeting foreign Vibrio strains from other Euprymna host species. Despite competitive dominance, secondar...

Biofilms are increasingly recognized as being the predominant form for survival for most bacteria in the environment. The successful colonization of Vibrio fischeri in its squid host Euprymna tasmanica involves complex microbe-host interactions mediated by specific genes that are essential for biofilm formation and colonization. Here, structural an...

In certain gastropod mollusks, the central neurons VD(1) and RPD(2) express a distinct peptide, the so-called VD(1)/RPD(2) α1-neuropeptide. In order to test whether this peptide is also present in the complex cephalopod central nervous system (CNS), we investigated several octopod and squid species. In the adult decapod squid Idiosepius notoides th...

The mutualistic system between the luminescent bacteria Vibrio fischeri and its host the sepiolid squid, is one of the most studied in biology. There is a difference of brightness between various bacterial strains within the host, some bright and some extremely dim. Previous research has suggested that the difference between bright and dim strains...

Persistence and survival under various environmental stresses has been attributed to the capacity of most bacteria to form biofilms. In aquatic environments, the symbiotic bacterium Vibrio fischeri survives variable abiotic conditions during its free-living stage that dictates its ability to colonize the squid host. In the present study, the influe...

Bobtail squid from the genera Sepiola and Rondeletiola (Cephalopoda: Sepiolidae) form mutualistic associations with luminous Gram-negative bacteria (Gammaproteobacteria: Vibrionaceae) from the genera Vibrio and Photobacterium. Symbiotic bacteria proliferate inside a bilobed light organ until they are actively expelled by the host into the surroundi...

The family Vibrionaceae (Domain Bacteria, Phylum Proteobacteria, Class Gammaproteobacteria) is comprised mostly of motile gram-negative chemoorganotrophs, possessing at least one polar flagellum (Farmer III and Janda, 2005; Thompson and Swings, 2006). Vibrios are facultative anaerobes, having both respiratory and fermentative metabolisms, and the m...

Luminescent bacteria (gamma-Proteobacteria: Vibrionaceae) are found in complex bilobed light organs of both sepiolid and loliginid squids (Mollusca: Cephalopoda). Despite the existence of multiple strain colonization between Vibrio bacteria and loliginid squids, specificity at the genus level still exists and may influence interactions between symb...

Adhesion and biofilm forming ability of symbiotic bacteria play a crucial role in host colonization and tissue infection. Bacteria benefit by adhering to their host in a manner that allows them to successfully maintain contact for the exchange of nutrients, hormones, or other necessary products. This study examined pili morphology, motility, and bi...

The class Cephalopoda (Phylum Mollusca), encompassing squids and octopuses, contains multiple species that are characterized by the presence of specialized organs known to emit light. These complex organs have a variety of morphological characteristics ranging from groups of simple, light-producing cells, to highly specialized organs (light organs)...

While much has been known about the mutualistic associations between the sepiolid squid Euprymna tasmanica and the luminescent bacterium, Vibrio fischeri, less is known about the connectivity between the microscopic and molecular basis of initial attachment and persistence in the light organ. Here, we examine the possible effects of two symbiotic g...

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Mutualistic relationships between bacteria and their eukaryotic hosts have existed for millions of years, and such associations can be used to understand the evolution of these beneficial partnerships. The symbiosis between sepiolid squids (Cephalopoda: Sepiolidae), and their Vibrio bacteria (gamma Proteobacteria: Vibrionaceae), has been a model sy...

Symbiosis between the bobtail squid Euprymna scolopes (Mollusca: Cephalopoda) and Vibrio fischeri bacteria has been a well-studied model for understanding the molecular mechanisms of colonization and adherence to host cells. For example, pilin expression has been observed to cause subtle variation in colonization for a number of Gram-negative bacte...

Vibrio fischeri is a bioluminescent bacterial symbiont of sepiolid squids (Cephalopoda: Sepiolidae) and monocentrid fishes (Actinopterygii: Monocentridae). V. fischeri exhibit competitive dominance within the allopatrically distributed squid genus Euprymna, which have led to the evolution of V. fischeri host specialists. In contrast, the host genus...

This chapter examines the phylogeny and evolution of the molluscan class Cephalopoda. It explains that all fossil and modern taxa are marine and that modern cephalopods have notoriety by being the subjects of myths or science fiction and as an important food source. It suggests that the ability of Cephalopoda to sense their surrounding environment...

The continuum between mutualistic and pathogenic symbioses has been an underlying theme for understanding the evolution of infection and disease in a number of eukaryotic-microbe associations. The ability to monitor and then predict the spread of infectious diseases may depend upon our knowledge and capabilities of anticipating the behavior of viru...

Recent molecular studies investigating higher-level phylogenetics of coleoid cephalopods (octopuses, squids and cuttlefishes) have produced conflicting results. A wide range of sequence alignment and analysis methods are used in cephalopod phylogenetic studies. The present study investigated the effect of commonly used alignment and analysis method...

Luminescent bacteria in the family Vibrionaceae (Bacteria: γ-Proteobacteria) are commonly found in complex, bilobed light organs of sepiolid and loliginid squids. Although morphology of these organs in both families of squid is similar, the species of bacteria that inhabit each host has yet to be verified. We utilized sequences of 16S ribosomal RNA...

Relatively little is known about large-scale spatial and temporal fluctuations in bacterioplankton, especially within the bacterial families. In general, however, a number of abiotic factors (namely, nutrients and temperature) appear to influence distribution. Community dynamics within the Vibrionaceae are of particular interest to biologists becau...

When using cephalopods as experimental animals, a number of factors, including morality, quality of information derived from experiments, and public perception, drives the motivation to consider welfare issues. Refinement of methods and techniques is a major step in ensuring protection of cephalopod welfare in both laboratory and field studies. To...

A major force driving in the innovation of mutualistic symbioses is the number of adaptations that both organisms must acquire to provide overall increased fitness for a successful partnership. Many of these symbioses are relatively dependent on the ability of the symbiont to locate a host (specificity), as well as provide some novel capability upo...

Squids from the genus Euprymna (Cephalopoda: Sepiolidae) and their symbiotic bacteria Vibrio fischeri form a mutualism in which vibrios inhabit a complex light organ within the squid host. A host-mediated daily expulsion event seeds surrounding seawater with symbiotically capable V. fischeri that environmentally colonize newly hatched axenic Euprym...

of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Monoplacophorans are among the rarest members of the phylum Mollusca. Previously only known from fossils since the Cambrian, the first living monoplacophoran was discovered during the famous second Galathea deep-sea expedition. The anatomy of these molluscs shocked the zoological community for presenting serially repeated gills, nephridia, and eigh...

The oceanic squid family Gonatidae (Mollusca: Cephalopoda) is widely distributed in subpolar and temperate waters, exhibiting behavioral and physiological specializations associated with reproduction. Females of several species undergo muscular degeneration upon maturation; origins of this complex morphogenic change are unknown, hindering our under...