Mutant alleles enable a D-glutamate auxotroph to grow with lower requirements for exogenous D-glutamate.

D-glu is a key component of peptidoglycan (PG) and is essential for growth in most bacteria. To assess constraints on PG evolution and bacterial requirements for D-glu, we sought to artificially evolve PG biosynthesis, leading to either replacement of D-glu in the PG peptide or alternative pathways to D-glu incorporation. We previously found that suppression of D-glu auxotrophy in a mutant of grown on lysogeny broth salts (LBS) medium was rare but could be accomplished by mutation of , with restoration of wild-type PG structure.

Application of amplicon sequencing to characterize microbial communities associated with juvenile and adult squid.

The symbiotic relationship between and the Hawaiian bobtail squid, , serves as a key model for understanding host-microbe interactions. Traditional culture-based methods have primarily isolated from the light organs of wild-caught squid, yet culture-independent analyses of this symbiotic microbiome remain limited. This study aims to enhance species-level resolution of bacterial communities associated with using amplicon sequencing.

Climate-Driven Warming Disrupts the Symbiosis of Bobtail Squid Euprymna scolopes and the Luminous Bacterium Vibrio fischeri.

Under the current climate crisis, marine heatwaves (MHW) are expected to intensify and become more frequent in the future, leading to adverse effects on marine life. Here, we aimed to investigate the impact of environmental warming on the symbiotic relationship between the Hawaiian bobtail squid (Euprymna scolopes) and the bioluminescent bacterium Vibrio fischeri. We exposed eggs of E.

An acidic microenvironment produced by the V-type ATPase of Euprymna scolopes promotes specificity during Vibrio fischeri recruitment.

Animals often acquire their microbial symbionts from the environment, but the mechanisms underlying how specificity of the association is achieved are poorly understood. We demonstrate that the conserved proton pump, V-type ATPase (VHA), plays a key role in the establishment of the model light-organ symbiosis between the squid Euprymna scolopes and its bacterial partner, Vibrio fischeri. Recruitment of V.

Application of amplicon sequencing to characterize microbial communities associated with juvenile and adult squid.

The symbiotic relationship between and the Hawaiian bobtail squid, , serves as a key model for understanding host-microbe interactions. Traditional culture-based methods have primarily isolated from the light organs of wild-caught squid, yet culture-independent analyses of this symbiotic microbiome remain limited. This study aims to enhance species-level resolution of bacterial communities associated with using amplicon sequencing.

Transient infection of with an engineered D-alanine auxotroph of .

The symbiosis between and the Hawaiian bobtail squid, , is a tractable and well-studied model of bacteria-animal mutualism. Here, we developed a method to transiently colonize using D-alanine (D-ala) auxotrophy of the symbiont, controlling the persistence of viable infection by supplying or withholding D-ala. We generated alanine racemase () mutants of that lack avenues for mutational suppression of auxotrophy or reversion to prototrophy.

Insulin Mimicking Mystery: Decoding Recurrent Hypoglycemia.

Insulin antibody syndrome (IAS), also known as Hirata disease, is a rare condition characterized by spontaneous hypoglycemic episodes unrelated to exogenous insulin exposure. It is caused by elevated serum levels of insulin autoantibodies (IAA). IAS typically occurs when a triggering factor, such as medication or viral infection, interacts with a predisposing genetic background.

A new lexicon in the age of microbiome research.

At a rapid pace, biologists are learning the many ways in which resident microbes influence, and sometimes even control, their hosts to shape both health and disease. Understanding the biochemistry behind these interactions promises to reveal completely novel and targeted ways of counteracting disease processes. However, in our protocols and publications, we continue to describe these new results using a language that originated in a completely different context.

Maturation state of colonization sites promotes symbiotic resiliency in the Euprymna scolopes-Vibrio fischeri partnership.

Background: Many animals and plants acquire their coevolved symbiotic partners shortly post-embryonic development. Thus, during embryogenesis, cellular features must be developed that will promote both symbiont colonization of the appropriate tissues, as well as persistence at those sites. While variation in the degree of maturation occurs in newborn tissues, little is unknown about how this variation influences the establishment and persistence of host-microbe associations.

Ciliated epithelia are key elements in the recruitment of bacterial partners in the squid-vibrio symbiosis.

The Hawaiian bobtail squid, , harvests its luminous symbiont, , from the surrounding seawater within hours of hatching. During embryogenesis, the host animal develops a nascent light organ with ciliated fields on each lateral surface. We hypothesized that these fields function to increase the efficiency of symbiont colonization of host tissues.

Transitioning to confined spaces impacts bacterial swimming and escape response.

Symbiotic bacteria often navigate complex environments before colonizing privileged sites in their host organism. Chemical gradients are known to facilitate directional taxis of these bacteria, guiding them toward their eventual destination. However, less is known about the role of physical features in shaping the path the bacteria take and defining how they traverse a given space.

Evidence of Genomic Diversification in a Natural Symbiotic Population Within Its Host.

Planktonic cells of the luminous marine bacterium establish themselves in the light-emitting organ of each generation of newly hatched bobtail squid. A symbiont population is maintained within the 6 separated crypts of the organ for the ∼9-month life of the host. In the wild, the initial colonization step is typically accomplished by a handful of planktonic cells, leading to a species-specific, but often multi-strain, symbiont population.

Independent host- and bacterium-based determinants protect a model symbiosis from phage predation.

Bacteriophages (phages) are diverse and abundant constituents of microbial communities worldwide, capable of modulating bacterial populations in diverse ways. Here, we describe the phage HNL01, which infects the marine bacterium Vibrio fischeri. We use culture-based approaches to demonstrate that mutations in the exopolysaccharide locus of V.

Getting the Message Out: the Many Modes of Host-Symbiont Communication during Early-Stage Establishment of the Squid-Vibrio Partnership.

Symbiosis, by its basic nature, depends on partner interactions that are mediated by cues and signals. This kind of critical reciprocal communication shapes the trajectory of host-microbe associations from their onset through their maturation and is typically mediated by both biochemical and biomechanical influences. Symbiotic partnerships often involve communities composed of dozens to hundreds of microbial species, for which resolving the precise nature of these partner interactions is highly challenging.

A lasting symbiosis: how Vibrio fischeri finds a squid partner and persists within its natural host.

As our understanding of the human microbiome progresses, so does the need for natural experimental animal models that promote a mechanistic understanding of beneficial microorganism-host interactions. Years of research into the exclusive symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium Vibrio fischeri have permitted a detailed understanding of those bacterial genes underlying signal exchange and rhythmic activities that result in a persistent, beneficial association, as well as glimpses into the evolution of symbiotic competence. Migrating from the ambient seawater to regions deep inside the light-emitting organ of the squid, V.

MicroRNA-Mediated Regulation of Initial Host Responses in a Symbiotic Organ.

One of the most important events in an animal's life history is the initial colonization by its microbial symbionts, yet little is known about this event's immediate impacts on the extent of host gene expression or the molecular mechanisms controlling it. MicroRNAs (miRNAs) are short, noncoding RNAs that bind to target mRNAs, rapidly shaping gene expression by posttranscriptional control of mRNA translation and decay. Here, we show that, in the experimentally tractable binary squid-vibrio symbiosis, colonization of the light organ induces extensive changes in the miRNA transcriptome.

Modeled microgravity alters lipopolysaccharide and outer membrane vesicle production of the beneficial symbiont Vibrio fischeri.

Reduced gravity, or microgravity, can have a pronounced impact on the physiology of animals, but the effects on their associated microbiomes are not well understood. Here, the impact of modeled microgravity on the shedding of Gram-negative lipopolysaccharides (LPS) by the symbiotic bacterium Vibrio fischeri was examined using high-aspect ratio vessels. LPS from V.

HbtR, a Heterofunctional Homolog of the Virulence Regulator TcpP, Facilitates the Transition between Symbiotic and Planktonic Lifestyles in Vibrio fischeri.

The bioluminescent bacterium forms a mutually beneficial symbiosis with the Hawaiian bobtail squid, , in which the bacteria, housed inside a specialized light organ, produce light used by the squid in its nocturnal activities. Upon hatching, juveniles acquire from the seawater through a complex process that requires, among other factors, chemotaxis by the bacteria along a gradient of -acetylated sugars into the crypts of the light organ, the niche in which the bacteria reside. Once inside the light organ, transitions into a symbiotic, sessile state in which the quorum-signaling regulator LitR induces luminescence.

The impact of persistent colonization by on the metabolome of the host squid .

Associations between animals and microbes affect not only the immediate tissues where they occur, but also the entire host. Metabolomics, the study of small biomolecules generated during metabolic processes, provides a window into how mutualistic interactions shape host biochemistry. The Hawaiian bobtail squid, , is amenable to metabolomic studies of symbiosis because the host can be reared with or without its species-specific symbiont, In addition, unlike many invertebrates, the host squid has a closed circulatory system.

Interactions of Symbiotic Partners Drive the Development of a Complex Biogeography in the Squid-Vibrio Symbiosis.

Microbes live in complex microniches within host tissues, but how symbiotic partners communicate to create such niches during development remains largely unexplored. Using confocal microscopy and symbiont genetics, we characterized the shaping of host microenvironments during light organ colonization of the squid by the bacterium During embryogenesis, three pairs of invaginations form sequentially on the organ's surface, producing pores that lead to interior compressed tubules at different stages of development. After hatching, these areas expand, allowing cells to enter and migrate ∼120 μm through three anatomically distinct regions before reaching blind-ended crypt spaces.