Biology subjects

Sato, N.

Publications and source records attributed to Sato, N..

27 records · Page 2Linked to original sources

bioRxiv2021

Independent adoptions of a set of proteins found in the matrix of the mineralized shell-like eggcase of Argonaut octopuses

The Argonaut octopus, commonly called the paper nautilus, has a spiral-coiled shell-like eggcase. As the main characteristics, the eggcase has no internal septum, is composed entirely of calcite with chitosan being the main polycarbonate and is reportedly formed by organic materials secreted from the membranes of the arms. Meanwhile, the biomineralized external "true" shells of the Mollusks, which includes the Cephalopods, are secreted from the mantle tissue. Therefore, the histological origin of the two shells is completely different. The question of how the Argonauts, which phylogenetically diverged from the completely shell-less octopuses, could form a converging shell-like external structure has thus intrigued biologists for a long time. To answer this question, we performed a multi-omics analysis of the transcriptome and proteome of the two congeneric Argonaut species, Argonauta argo and A. hians. Our result indicates that the shell-like eggcase is not a homolog of the shell, even at the protein level, because the Argonauts apparently recruited a different set of protein repertoires to as eggcase matrix proteins (EcMPs). However, we also found the homologs of three shell matrix proteins (SMPs) of the Conchiferan Mollusks, Pif-like, SOD, and TRX, in the eggcase matrix. The proteins were also found in the only surviving shelled Cephalopods, the nautiloid Nautilus pompilius. Phylogenetic analysis revealed that homologous genes of the Conchiferan SMPs and EcMPs were found in the draft genome of shell-less octopuses. Our result reported here thus suggests that the SMP-coding genes are conserved in both shelled and shell-less Cephalopods. Meanwhile, the Argonauts adopted some of the SMP-coding genes and other non-SMP-coding genes, to form a convergent, non-homologous biomineralized external structure, the eggcase, which is autapomorphic to the group.

evolutionary biology↗

bioRxiv2021

Action selection based on multiple-stimulus aspects in the wind-elicited escape behavior of crickets

Animals detect approaching predators via sensory inputs through various modalities and immediately show an appropriate behavioral response to survive. Escape behavior is essential to avoid the predators attack and is more frequently observed than other defensive behaviors. In some species, multiple escape responses are exhibited with different movements. It has been reported that the approaching speed of a predator is important in choosing which escape action to take among the multiple responses. However, it is unknown whether other aspects of sensory stimuli, that indicate the predators approach, affect the selection of escape responses. We focused on two distinct escape responses (running and jumping) to a stimulus (short airflow) in crickets and examined the effects of multiple stimulus aspects (including the angle, velocity, and duration) on the choice between these escape responses. We found that the faster and longer the airflow, the more frequently the crickets jumped, meaning that they could choose their escape response depending on both velocity and duration of the stimulus. This result suggests that the neural basis for choosing escape responses includes the integration process of multiple stimulus parameters. It was also found that the moving speed and distance changed depending on the stimulus velocity and duration during running but not during jumping, suggesting higher adaptability of the running escape. In contrast, the movement direction was accurately controlled regardless of the stimulus parameters in both responses. The escape direction depended only on stimulus orientation, but not on velocity and duration. Summary statementWhen air currents triggering escape are faster and longer, crickets more frequently jump than run. Running speed and distance depend on stimulus velocity and duration, but direction control is independent.

animal behavior and cognition↗

bioRxiv2021

Sense of absence: Spatial perception through active sensing by insect antennal mechanosensory system

Animals perceive their surroundings by using various modalities of sensory inputs to navigate their locomotion. Nocturnal insects such as crickets use mechanosensory inputs mediated by their antennae to navigate under dark conditions. Active sensing with voluntary antennal movements improves spatial information, but it remains unclear how accurately the insects can perceive the surrounding space by using their antennal system. Crickets exhibit escape behavior in response to a short air-puff, which is detected by the abdominal mechanosensory organ called cerci and is perceived as a "predator approach" signal. We placed objects of different shapes at different locations with which the cricket actively made contact using its antenna. We then examined the effects on wind-elicited escape. The crickets changed their movement trajectory depending on the shape and location of the objects so that they could avoid collision with these obstacles even when the escape behavior was triggered by another modality of stimulus. For instance, when a wall was placed in front of the crickets so that it was detected by one side of their antenna, the escape trajectory in response to a stimulus from behind was significantly biased toward the side opposite the wall. However, if the antenna on the free side without the wall was ablated, this modulation to avoid collision diminished, suggesting that the antenna on the free side provided information of "absence" of obstacles. This study demonstrated that crickets were able to perceive spatial information, including the presence or absence of objects by active sensing with their antennal system. Summary StatementCrickets can acquire spatial information such as shape, location and orientation of objects through active sensing by antennal mechanosensory system, which also provides information about the absence of objects.

animal behavior and cognition↗

bioRxiv2020

Helping Behavior in Prairie Voles: A Model of Empathy and the Importance of Oxytocin

Several studies suggest that rodents show empathic responses and helping behavior toward others. We examined whether prairie voles (Microtus ochrogaster) would help conspecifics who were soaked in water by opening a door to a safe area. Door-opening latency decreased as task sessions progressed. When the conspecific was not soaked in water, the latency of the door-opening did not decrease, indicating that the distress of the conspecific is necessary for the learning of the door-opening. These suggest that prairie voles learn helping behavior. We found no sex difference in the door-opening latency or the interest in other voles soaked in water. Additionally, we also examined the helping behavior in prairie voles in which oxytocin receptors were genetically knocked out. Oxytocin receptor knockout voles demonstrated less learning of the door-opening and less interest in other voles soaked in water. This suggests that oxytocin is important for the emergence of helping behavior.

animal behavior and cognition↗

bioRxiv2020

Context-dependent behavioral plasticity compromises disruptive selection on sperm traits in squid

Male animals are not given equal mating opportunities under competitive circumstances. Small males often exhibit alternative mating behaviours and produce spermatozoa of higher quality to compensate for their lower chances of winning physical contests against larger competitors [1]. Because the reproductive benefits of these phenotypes depend on social status/agonistic ranks that can change during growth or aging [2], sperm traits should be developed/switched into fitness optima according to their prospects. However, reproductive success largely relies upon social contexts arising instantaneously from intra- and inter-sexual interactions, which deter males from developing extreme traits and instead favour behavioural plasticity. Nevertheless, the extent to which such plasticity influences developmentally regulated alternative sperm traits remains unexplored. Squids of the family Loliginidae are excellent models to investigate this, because they show sophisticated alternative reproductive tactics (ARTs) by which small males, known as "sneakers", produce longer spermatozoa and perform extra-pair copulation to attach their sperm packages near the female seminal receptacle (SR). In contrast, large "consort" males have shorter spermatozoa and copulate via pair-bonding to insert their sperm packages near the internal female oviduct [3]. In addition, plasticity in male mating behaviour is common in some species while it is either rare or absent in others. Thus, squid ARTs display a broad spectrum of adaptive traits with a complex repertoire in behaviour, morphology and physiology [3].

evolutionary biology↗

bioRxiv2020

Three-Component Model of the Spinal Nerve Branching Pattern, based on the View of the Lateral Somitic Frontier and Experimental Validation

One of the decisive questions about human gross anatomy is unmatching the adult branching pattern of the spinal nerve to the embryonic lineages of the peripheral target muscles. The two principal branches in the adult anatomy, the dorsal and ventral rami of the spinal nerve, innervate the intrinsic back muscles (epaxial muscles), as well as the body wall and appendicular muscles (hypaxial muscles), respectively. However, progenitors from the dorsomedial myotome develop into the back and proximal body wall muscles (primaxial muscles) within the sclerotome-derived connective tissue environment. In contrast, those from the ventrolateral myotome develop into the distal body wall and appendicular muscles (abaxial muscles) within the lateral plate-derived connective tissue environment. Thus, the ventral rami innervate muscles that belong to two different embryonic compartments. Because strict correspondence between an embryonic compartment and its cognate innervation is a way to secure the development of functional neuronal circuits, this mismatch indicates that we may need to reconcile our current understanding of the branching pattern of the spinal nerve with regard to embryonic compartments. Accordingly, we first built a model for the branching pattern of the spinal nerve, based on the primaxial-abaxial distinction, and then validated it using mouse embryos. In our model, we hypothesized the following: 1) a single spinal nerve consists of three nerve components: primaxial compartment-responsible branches, a homologous branch to the canonical intercostal nerve bound for innervation to the abaxial compartment in the ventral body wall, and a novel class of nerves that travel along the lateral cutaneous branch to the appendicles; 2) the three nerve components are discrete only during early embryonic periods but are later modified into the elaborate adult morphology; and 3) each of the three components has its own unique morphology regarding trajectory and innervation targets. Notably, the primaxial compartment-responsible branches from the ventral rami have the same features as the dorsal rami. Under the above assumptions, our model comprehensively describes the logic for innervation patterns when facing the intricate anatomy of the spinal nerve in the human body. In transparent whole-mount specimens of embryonic mouse thoraces, the single thoracic spinal nerve in early developmental periods trifurcated into superficial, deep, and lateral cutaneous branches; however, it later resembled the adult branching pattern by contracting the superficial branch. The superficial branches remained segmental while the other two branches were free from axial restriction. Injection of a tracer into the superficial branches of the intercostal nerve labeled Lhx3-positive motoneurons in the medial portion of the medial motor column (MMCm). However, the injection into the deep branches resulted in retrograde labeling of motoneurons that expressed Oct6 in the lateral portion of the medial motor column (MMCl). Collectively, these observations on the embryonic intercostal nerve support our model that the spinal nerve consists of three distinctive components. We believe that our model provides a framework to conceptualize the innervation pattern of the spinal nerve based on the distinction of embryonic mesoderm compartments. Because such information about the spinal nerves is essential, we further anticipate that our model will provide new insights into a broad range of research fields, from basic to clinical sciences.

developmental biology↗

bioRxiv2020

An SNP variant MT1-MMP with a defect in its collagenolytic activity confers the fibrotic phenotype of Dupuytren's Disease

Dupuytrens Disease (DD) is a common fibroproliferative disease of the palmar fascia. We previously identified a strong association with a non-synonymous variant (rs1042704, pD273N) in MMP14 (encoding MT1-MMP). We investigated the functional consequences of this variant, and demonstrated that the variant MT1-MMP (MT1-N273) exhibits only 17% of cell surface collagenolytic activity compared to the ancestral enzyme (MT1-D273). Cells expressing both MT1-D273 and MT1-N273 in a 1:1 ratio, mimicking the heterozygous state, possess 38% of the collagenolytic activity compared to the cells expressing MT1-D273, suggesting that MT1-N273 acts in a dominant negative manner. Consistent with this hypothesis, patient-derived DD myofibroblasts expressing MT1-N273 demonstrated around 30% of full collagenolytic activity regardless of the heterozygous or homozygous state. 3D-molecular envelope modelling using small angle X-ray scattering demonstrated altered positioning of the catalytic domain within dimeric molecules. Taken together, our data suggest that rs1042704 directly contributes to the fibrotic phenotype of DD.

biochemistry↗

bioRxiv2020

Flexible annotation atlas of the mouse brain: combining and dividing brain structures of the Allen Brain Atlas while maintaining anatomical hierarchy

A brain atlas is necessary for analyzing structure and function in neuroimaging research. Although various annotation volumes (AVs) for the mouse brain have been proposed, it is common in magnetic resonance imaging (MRI) of the mouse brain that regions-of-interest (ROIs) for brain structures (nodes) are created arbitrarily according to each researchers necessity, leading to inconsistent ROIs among studies. One reason for such a situation is the fact that earlier AVs were fixed, i.e. combination and division of nodes were not implemented. This report presents a pipeline for constructing a flexible annotation atlas (FAA) of the mouse brain by leveraging public resources of the Allen Institute for Brain Science on brain structure, gene expression, and axonal projection. A mere two-step procedure with user-specified, text-based information and Python codes constructs FAA with nodes which can be combined or divided objectively while maintaining anatomical hierarchy of brain structures. Four FAAs with total node count of 4, 101, 866, and 1,381 were demonstrated. Unique characteristics of FAA realized analysis of resting-state functional connectivity (FC) across the anatomical hierarchy and among cortical layers, which were thin but large brain structures. FAA can improve the consistency of whole brain ROI definition among laboratories by fulfilling various requests from researchers with its flexibility and reproducibility. Highlights- A flexible annotation atlas (FAA) for the mouse brain is proposed. - FAA is expected to improve whole brain ROI-definition consistency among laboratories. - The ROI can be combined or divided objectively while maintaining anatomical hierarchy. - FAA realizes functional connectivity analysis across the anatomical hierarchy. - Codes for FAA reconstruction is available at https://github.com/ntakata/flexible-annotation-atlas - Datasets for resting-state fMRI in awake mice are available at https://openneuro.org/datasets/ds002551

neuroscience↗

bioRxiv2019

Polyandry is extremely rare in the firefly squid, Watasenia scintillans

Although polygamy has versatile benefits for both sexes, many species favor monogamy for reasons with the clarity or unclarity. In cephalopods, all species are regarded to be polygamous, which could be attributed to their common life-history traits. Contrary to this prediction, we show empirical evidence for monogamy in the firefly squid, Watasenia scintillans. The peak spawning season comes after male disappearance owning to long-reserved spermatangia deposited by male at exact locations (bilateral pouches under neck collar) on female with a symmetric distribution. Such a non-random placement of spermatangia prompted us to hypothesize that females engage in lifetime monoandry. Hence we assigned genotypes of female-stored spermatangia and offspring. We found that in 94.7 % females, the spermatangia were delivered from a single male and all embryos in the same egg string sired by sperm from stored spermatangia. Throughout the season, relative testes mass was much smaller in W. scintillans than all other cephalopods previously examined. The mean number of male-stored spermatophores was approximately 30, the equivalent to 2.5 mates. Our demographic and morphometrical data agree with the prediction that monogyny is favored when potential mates are scarce such as absence of female remating. Together, these results suggest the likelihood of mutual monogamy.

ecology↗