Optimization of inhaled anesthesia for Octodon degus using electroencephalography.

Physiological responses to inhaled anesthetics vary among species. Therefore, a precise anesthetic technique is important for each individual species. In this study, we focused on the degu (Octodon degus), a small herbivorous rodent. Degus have recently begun to be used as laboratory models for brain research because of certain human-like characteristics, such as spontaneous development of Alzheimer's disease. In this study, we evaluated appropriate induction and maintenance anesthesia conditions for isoflurane and sevoflurane in degus by a stimulation test, electroencephalography (EEG), minimum alveolar concentration (MAC), and vital signs. During induction, more rapid time to loss of the righting reflex and deeper anesthesia in degus were observed in isoflurane. The MAC value for degus were 1.75 ± 0.0% in isoflurane and 2.25 ± 0.27% in sevoflurane. Whereas some degus were awake during maintenance anesthesia using both anesthetics at concentrations of ≤2%, no rats were awake when using sevoflurane at a concentration of 2%. The duration of the total flat EEG, a measure of the depth of maintenance anesthesia, was longer for isoflurane than for sevoflurane. Furthermore, higher concentrations of both anesthetics suppressed the respiratory rate in degus. These new findings regarding inhalation anesthesia in degus will contribute to future developments in the fields of laboratory animals and veterinary medicine.

Long-term behavioral effects of social separation during early life in a social mammal, Octodon degus.

Social separation is thought to induce a strong stress response in social juvenile mammals, but little is known about how this response might vary throughout the development. The present study examines the long-term effects of early-life stress (ELS) induced by social separation on individual behaviors later in life using the social and precocious species Octodon degus. Four experimental groups were established a positive control group of mothers and siblings from six litters comprised the socially housed (SH) group, while pups from seven litters were randomly assigned to three treatments: pups experiencing no separation (NS) treatment while their siblings did; repeated bouts of consecutive separation (CS); intermittent separation (IS). We analyzed the effects of separation treatment on the frequency and duration of freezing, rearing and grooming behaviors. ELS was correlated with higher hyperactivity, and hyperactivity increased with more frequent separation. However, the behavioral trend of the NS group changed to hyperactive in long-term observation. The findings suggest that the NS group was indirectly affected by ELS. In addition, suggesting ELS acts to converge an individual's behavioral tendencies in a certain direction.

Message to researchers: the characteristic absence of a posterior communicating artery is easily lost in the gerbil.

The Mongolian gerbil has historically been useful for brain ischemia experiments, owing to the gerbil's uniquely underdeveloped circle of Willis (CoW). This led to a gerbil model of cochlear ischemia being generated in our unit. However, we have found that the usual severe hearing loss seen in this model was not being induced consistently in recent experiments using the MON/Jms/GbsSlc gerbil (the sole commercially available gerbil in Japan). We set out to evaluate the posterior communicating artery (PcomA) in MON/Jms/GbsSlc, to re-establish whether this strain is appropriate for ischemia models. Having found that this unique feature is often lost, we then attempted to breed for the characteristic absent PcomA. India-ink perfusion revealed that the percentage of intact bilateral PcomA ("communicating type") in the MON/Jms/GbsSlc gerbil was 57%; unilateral only ("unilateral communicating type") was 39%; and completely absent PcomA ("non-communicating type") was 4%. We were able to obtain few examples of the indigenous old aged Japanese UNG/Mz gerbil strain (at University of Miyazaki). Unfortunately, the pure UNG/Mz female was too elderly for mating. Therefore, selective breeding crosses between MON/Jms/GbsSlc and male UNG/Mz were carried out. After five generations of selective breeding, the percentage of non-communicating type gerbils was significantly higher in the newly generated strain, MON/Jms/SlcMz (F6 generation; 63%) than in the MON/Jms/GbsSlc gerbil. Bilateral common carotid artery occlusion surgery demonstrated that the cerebral blood flow was significantly reduced in MON/Jms/SlcMz compared with MON/Jms/GbsSlc (p < 0.0001) and induced more hippocampal injuries in MON/Jms/SlcMz than in MON/Jms/GbsSlc (p < 0.01). In conclusion, the commercially available MON/Jms/GbsSlc gerbil can easily regain PcomA, and we established a new gerbil strain (MON/Jms/SlcMz) displaying non-PcomA.

Regulatory Roles of the N-Terminal Intrinsically Disordered Region of Modular Src.

Src, the prototype of Src family kinases (SFKs), is a modular protein consisting of SH4 (SH4) and unique (UD) domains in an N-terminal intrinsically disordered region (IDR), and SH3, SH2, and kinase (KD) folded domains conserved among SFKs. Src functions as a pleiotropic signaling hub in proliferating and post-mitotic cells, and it is related to cancer and neurological diseases. However, its regulatory mechanism is unclear because the existing canonical model is derived from crystallographic analyses of folded constructs lacking the IDR. This work reviews nuclear magnetic resonance analyses of partially structured lipid-binding segments in the flexible UD and the fuzzy intramolecular complex (FIMC) comprising IDR and SH3 domains, which interacts with lipid membranes and proteins. Furthermore, recently determined IDR-related Src characteristics are discussed, including dimerization, SH4/KD intramolecular fastener bundling of folded domains, and the sorting of adhesive structures. Finally, the modulatory roles of IDR phosphorylation in Src activities involving the FIMC are explored. The new regulatory roles of IDRs are integrated with the canonical model to elucidate the functions of full-length Src. This review presents new aspects of Src regulation, and provides a future direction for studies on the structure and function of Src, and their implications for pathological processes.

Comparison of the gut microbiotas of laboratory and wild Asian house shrews (Suncus murinus) based on cloned 16S rRNA sequences.

The Asian house shrew, Suncus murinus, is an insectivore (Eulipotyphla, Mammalia) and an important laboratory animal for life-science studies. The gastrointestinal tract of Suncus is simple: the length of the entire intestine is very short relative to body size, the large intestine is quite short, and there are no fermentative chambers such as the forestomach or cecum. These features imply that Suncus has a different nutritional physiology from those of humans and mice, but little is known about whether Suncus utilizes microbial fermentation in the large (LI) or small (SI) intestine. In addition, domestication may affect the gastrointestinal microbial diversity of Suncus. Therefore, we compared the gastrointestinal microbial diversity of Suncus between laboratory and wild Suncus and between the SI and LI (i.e., four groups: Lab-LI, Lab-SI, Wild-LI, and Wild-SI) using bacterial 16S rRNA gene library sequencing analyses with a sub-cloning method. We obtained 759 cloned sequences (176, 174, 195, and 214 from the Lab-LI, Lab-SI, Wild-LI, and Wild-SI samples, respectively), which revealed that the gastrointestinal microbiota of Suncus is rich in Firmicutes (mostly lactic acid bacteria), with few Bacteroidetes. We observed different bacterial communities according to intestinal region in laboratory Suncus, but not in wild Suncus. Furthermore, the gastrointestinal microbial diversity estimates were lower in laboratory Suncus than in wild Suncus. These results imply that Suncus uses lactic acid fermentation in the gut, and that the domestication process altered the gastrointestinal bacterial diversity.

Nonphosphorylatable Src Ser75 Mutation Increases Ethanol Preference and Consumption in Mice.

Src is highly expressed in CNS neurons and contributes not only to developmental proliferation and differentiation but also to high-order brain functions, such as those contributing to alcohol consumption. Src knock-out mice exhibit no CNS abnormalities, presumably due to compensation by other Src family kinases (SFKs), but have a shortened lifespan and osteopetrosis-associated defects, impeding investigations of the role of Src on behavior in adult mice. However, the Unique domain of Src differs from those in other SFKs and is phosphorylated by cyclin-dependent kinase 1 (Cdk1) and Cdk5 at Ser75, which influences its postmitotic function in neurons. Therefore, ethanol consumption in mice harboring nonphosphorylatable (Ser75Ala) or phosphomimetic (Ser75Asp) Src mutants was investigated. Mice harboring the Ser75Ala Src mutant, but not the Ser75Asp mutant, had a higher preference for and consumption of solutions containing 5% and 10% ethanol than wild-type mice. However, plasma ethanol concentrations and sensitivities to the sedative effects of ethanol were not different among the groups. In mice harboring the Ser75Ala Src mutant, the activity of Rho-associated kinase (ROCK) in the striatum was significantly lower and Akt Ser473 phosphorylation was significantly higher than in wild-type mice. These results suggest that Src regulates voluntary ethanol drinking in a manner that depends on Ser75 phosphorylation.

Individual differences in torpor expression in adult mice are related to relative birth mass.

Daily torpor is a physiological adaptation in small mammals and birds, characterised by drastic reductions in metabolism and body temperature. Energy-constraining conditions, such as cold and starvation, are known to cause the expression of daily torpor. However, the reason for high degrees of inter- and intra-individual variation in torpor expression (TE) in similar situations is not clear. As littermates of altricial animals are exposed to an uneven allocation of maternal resources from conception to weaning, we tested whether early nutritional experiences have long-term effects on TE in adults. We used full-sibling littermates of laboratory mice that as adults were starved overnight to induce torpor. We measured body mass from birth until adulthood as an indicator of nutritional status, and calculated the relative body mass (RBM) as an indicator of the difference in nutritional status within a litter. After maturation, we subjected mice to five repeated torpor induction trials involving 24 h of fasting and 5 days of recovery. Half of the female mice displayed great individual variation in TE whereas male mice rarely exhibited daily torpor. In females, RBM at birth influenced TE, irrespective of body mass in adulthood; thus, female mice born with low RBMs displayed high TE in adulthood. In conclusion, we provide evidence that TE in mice differs among littermates, and that this variation is linked closely to heterogeneous nutritional experiences during the fetal period.

A Ser75-to-Asp phospho-mimicking mutation in Src accelerates ageing-related loss of retinal ganglion cells in mice.

Src knockout mice show no detectable abnormalities in central nervous system (CNS) post-mitotic neurons, likely reflecting functional compensation by other Src family kinases. Cdk1- or Cdk5-dependent Ser75 phosphorylation in the amino-terminal Unique domain of Src, which shares no homology with other Src family kinases, regulates the stability of active Src. To clarify the roles of Src Ser75 phosphorylation in CNS neurons, we established two types of mutant mice with mutations in Src: phospho-mimicking Ser75Asp (SD) and non-phosphorylatable Ser75Ala (SA). In ageing SD/SD mice, retinal ganglion cell (RGC) number in whole retinas was significantly lower than that in young SD/SD mice in the absence of inflammation and elevated intraocular pressure, resembling the pathogenesis of progressive optic neuropathy. By contrast, SA/SA mice and wild-type (WT) mice exhibited no age-related RGC loss. The age-related retinal RGC number reduction was greater in the peripheral rather than the mid-peripheral region of the retina in SD/SD mice. Furthermore, Rho-associated kinase activity in whole retinas of ageing SD/SD mice was significantly higher than that in young SD/SD mice. These results suggest that Src regulates RGC survival during ageing in a manner that depends on Ser75 phosphorylation.

Sheaf theoretic formulation for consciousness and qualia and relationship to the idealism of non-dual philosophies.

Questions about the nature of reality, whether Consciousness is the fundamental reality in the universe, and what is Consciousness itself, have no answer in systems that assume an external reality independent of Consciousness. Ultimately, the ontological foundation of such systems is the absolute division of subject and object. We advocate instead what we consider to be an approach that is in agreement with the foundation of quantum reality, which is based on Ramanuja's version of Vedanta philosophy and non-dual Kashmir Saivism. Quantum mechanics opened the door to consciousness, but it cannot account for consciousness. However, the quantum measurement problem implies that we cannot remove subjective experience from the practice of science. It is then appropriate to seek mathematical formalisms for the workings of consciousness that don't rely on specific interpretations of quantum mechanics. Temporal topos provides such a framework. In the theory of temporal topos, which we outline here, the difference between a subject and an object involves the direction of a morphism in a category. We also note that in the dual category, the direction of the morphism is in the opposite direction compared with the original direction of the original category. The resulting formalism provides powerful ways to address consciousness and qualia, beyond attempts to account for consciousness through physical theories. We also discuss the implications of the mathematics presented here for the convergence of science and non-dualist philosophies, as an emerging science of Consciousness, that may bring out the underlying unity of physics, life and mind.

Protein restriction does not affect body temperature pattern in female mice.

Daily torpor is a physiological adaptation in mammals and birds characterized by a controlled reduction of metabolic rate and body temperature during the resting phase of circadian rhythms. In laboratory mice, daily torpor is induced by dietary caloric restriction. However, it is not known which nutrients are related to daily torpor expression. To determine whether dietary protein is a key factor in inducing daily torpor in mice, we fed mice a protein-restricted (PR) diet that included only one-quarter of the amount of protein but the same caloric level as a control (C) diet. We assigned six non-pregnant female ICR mice to each group and recorded their body weights and core body temperatures for 4 weeks. Body weights in the C group increased, but those in the PR group remained steady or decreased. Mice in both groups did not show daily torpor, but most mice in a food-restricted group (n=6) supplied with 80% of the calories given to the C group exhibited decreased body weights and frequently displayed daily torpor. This suggests that protein restriction is not a trigger of daily torpor; torpid animals can conserve their internal energy, but torpor may not play a significant role in conserving internal protein. Thus, opportunistic daily torpor in mice may function in energy conservation rather than protein saving.

Susceptibility of muridae cell lines to ecotropic murine leukemia virus and the cationic amino acid transporter 1 viral receptor sequences: implications for evolution of the viral receptor.

Ecotropic murine leukemia viruses (Eco-MLVs) infect mouse and rat, but not other mammalian cells, and gain access for infection through binding the cationic amino acid transporter 1 (CAT1). Glycosylation of the rat and hamster CAT1s inhibits Eco-MLV infection, and treatment of rat and hamster cells with a glycosylation inhibitor, tunicamycin, enhances Eco-MLV infection. Although the mouse CAT1 is also glycosylated, it does not inhibit Eco-MLV infection. Comparison of amino acid sequences between the rat and mouse CAT1s shows amino acid insertions in the rat protein near the Eco-MLV-binding motif. In addition to the insertion present in the rat CAT1, the hamster CAT1 has additional amino acid insertions. In contrast, tunicamycin treatment of mink and human cells does not elevate the infection, because their CAT1s do not have the Eco-MLV-binding motif. To define the evolutionary pathway of the Eco-MLV receptor, we analyzed CAT1 sequences and susceptibility to Eco-MLV infection of other several murinae animals, including the southern vole (Microtus rossiaemeridionalis), large Japanese field mouse (Apodemus speciosus), and Eurasian harvest mouse (Micromys minutus). Eco-MLV infection was enhanced by tunicamycin in these cells, and their CAT1 sequences have the insertions like the hamster CAT1. Phylogenetic analysis of mammalian CAT1s suggested that the ancestral CAT1 does not have the Eco-MLV-binding motif, like the human CAT1, and the mouse CAT1 is thought to be generated by the amino acid deletions in the third extracellular loop of CAT1.

Production of mouse ES cells homozygous for Cdk5-phosphorylated site mutation in c-Src alleles.

c-Src-null mutants have not provided a full understanding of the cellular functions of c-Src, reflecting the functional redundancy among Src family members. c-Src is phosphorylated by cyclin-dependent kinase 1 (Cdk1) and Cdk5 at Ser75 in the unique amino terminal c-Src-specific domain. The specific roles of c-Src may be assessed by establishing mouse embryonic stem (ES) cells homozygous for a point mutation at Ser75. Mammalian homozygous cultured cells with a point mutation, however, have not yet been produced by gene targeting. Here we show an efficient procedure for producing ES cell clones bearing a homozygous Ser75 to Asp mutation in the c-src gene. This procedure was developed by combining two previously reported strategies: our procedure for introducing a point mutation into one allele with no exogenous sequence, and the high-geneticin (G418) selection procedure for introducing a mutation into both alleles. The mutant clones expressed the same levels of c-Src protein and autophosphorylation activity as wild-type cells, but the mutant c-Src was not phosphorylated on Ser75 during mitosis. This procedure is feasible for generating cells homozygous for a subtle mutation in most genes, and is expected to be applicable to other somatic cell lines.