Developmental Stage-dependent Manner Research Articles

Developmental stage dependent metabolic regulation during meiotic differentiation in budding yeast.

BackgroundThe meiotic developmental pathway in yeast enables both differentiation of vegetative cells into haploid spores that ensure long-term survival, and recombination of the parental DNA to create genetic diversity. Despite the importance of proper metabolic regulation for the supply of building blocks and energy, little is known about the reprogramming of central metabolic pathways in meiotically differentiating cells during passage through successive developmental stages.ResultsMetabolic regulation during meiotic differentiation in budding yeast was analyzed by integrating information on genome-wide transcriptional activity, 26 enzymatic activities in the central metabolism, the dynamics of 67 metabolites, and a metabolic flux analysis at mid-stage meiosis. Analyses of mutants arresting sporulation at defined stages demonstrated that metabolic reprogramming is tightly controlled by the progression through the developmental pathway. The correlation between transcript levels and enzymatic activities in the central metabolism varies significantly in a developmental stage-dependent manner. The complete loss of phosphofructokinase activity at mid-stage meiosis enables a unique setup of the glycolytic pathway which facilitates carbon flux repartitioning into synthesis of spore wall precursors during the co-assimilation of glycogen and acetate. The need for correct homeostasis of purine nucleotides during the meiotic differentiation was demonstrated by the sporulation defect of the AMP deaminase mutant amd1, which exhibited hyper-accumulation of ATP accompanied by depletion of guanosine nucleotides.ConclusionsOur systems-level analysis shows that reprogramming of the central metabolism during the meiotic differentiation is controlled at different hierarchical levels to meet the metabolic and energetic needs at successive developmental stages.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-014-0060-x) contains supplementary material, which is available to authorized users.

Temporally defined neocortical translation and polysome assembly are determined by the RNA-binding protein Hu antigen R.

Precise spatiotemporal control of mRNA translation machinery is essential to the development of highly complex systems like the neocortex. However, spatiotemporal regulation of translation machinery in the developing neocortex remains poorly understood. Here, we show that an RNA-binding protein, Hu antigen R (HuR), regulates both neocorticogenesis and specificity of neocortical translation machinery in a developmental stage-dependent manner in mice. Neocortical absence of HuR alters the phosphorylation states of initiation and elongation factors in the core translation machinery. In addition, HuR regulates the temporally specific positioning of functionally related mRNAs into the active translation sites, the polysomes. HuR also determines the specificity of neocortical polysomes by defining their combinatorial composition of ribosomal proteins and initiation and elongation factors. For some HuR-dependent proteins, the association with polysomes likewise depends on the eukaryotic initiation factor 2 alpha kinase 4, which associates with HuR in prenatal developing neocortices. Finally, we found that deletion of HuR before embryonic day 10 disrupts both neocortical lamination and formation of the main neocortical commissure, the corpus callosum. Our study identifies a crucial role for HuR in neocortical development as a translational gatekeeper for functionally related mRNA subgroups and polysomal protein specificity.

Tetrabromobisphenol A disrupts vertebrate development via thyroid hormone signaling pathway in a developmental stage-dependent manner.

Data concerning effects of tetrabromobisphenol A (TBBPA) on thyroid hormone (TH)-dependent vertebrate development have been limited, although TBBPA has been demonstrated in vitro to disrupt the TH signaling pathway at the transcriptional level. In this study, we investigated the effects of TBBPA on T3-induced and spontaneous Xenopus laevis metamorphosis, which share many similarities with TH-dependent development in higher vertebrates. In a 6-day T3-induced metamorphosis assay using premetamorphic tadpoles, 10-1000 nM TBBPA exhibited inhibitory effects on T3-induced expression of TH-response genes and morphological changes in a concentration-dependent manner, with a weak stimulatory action on tadpole development and TH-response gene expression in the absence of T3 induction. In a spontaneous metamorphosis assay, we further found that TBBPA promoted tadpole development from stage 51 to 56 (pre- and prometamorphic stages) but inhibited metamorphic development from stage 57 to 66 (metamorphic climax). These results strongly show that TBBPA, even at low concentrations, disrupts TH-dependent development in a developmental stage-dependent manner, i.e., TBBPA exhibits an antagonistic activity at the developmental stages when animals have high endogenous TH levels, whereas it acts as an agonist at the developmental stages when animals have low endogenous TH levels. Our study highlights the adverse influences of TBBPA on TH-dependent development in vertebrates.

Studies on the Accumulation of Drought-Induced Boiling Soluble Proteins (Hydrophilins) at Vegetative and Reproductive Phases of Drought Tolerant and Susceptible Cultivars of <i>Triticum aestivum</i>

Drought is one of the major environmental constraints affecting the crops worldwide. Expression of boiling soluble proteins (BSPs) is of paramount importance, because they play important roles in the water stress responses and also in plant metabolism. In this study, the effect of drought on BSPs at vegetative (shoots) and reproductive (seeds) phases of drought tolerant (cv. ‘PBW 527’) and drought susceptible (cv. ‘PBW 343’) cultivars of Triticum aestivum were carried at three different developmental stages. The boiling soluble protein profiles of shoots and seeds were outlined via SDS-PAGE followed by immune-blot analysis using anti-HSP, anti-APase, anti-LEA, anti-SOD, anti-AQUA and anti-CAT antibodies. Western blot analysis revealed that expression of BSPs was modulated differentially in a stress, tissue, developmental stage and cultivar dependent manner. For instance, enhanced expression of seeds BSPs (APase, LEA, CAT, AQUA) was observed in the tolerant cv. ‘PBW 527’ after drought stress. However, no such enhancement was observed in the susceptible cultivar. Similarly, in shoots of cv. ‘PBW 527’, a substantial increase of BSP (SOD) expression was established after drought stress treatment, indicating their role in drought stress adaptation. Further, to gain an insight into the role of BSPs, a time course pre- and post-stress kinetic studies were also conducted in the seeds of tolerant and susceptible wheat cultivars. Based upon the observations, the possible role of boiling soluble proteins (hydrophilins) in water stress tolerance is discussed.

Studies on the Accumulation of Drought-Induced Boiling Soluble Proteins (Hydrophilins) at Vegetative and Reproductive Phases of Drought Tolerant and Susceptible Cultivars of <i>Triticum aestivum</i>

Drought is one of the major environmental constraints affecting the crops worldwide. Expression of boiling soluble proteins (BSPs) is of paramount importance, because they play important roles in the water stress responses and also in plant metabolism. In this study, the effect of drought on BSPs at vegetative (shoots) and reproductive (seeds) phases of drought tolerant (cv. ‘PBW 527’) and drought susceptible (cv. ‘PBW 343’) cultivars of Triticumaestivum were carried at three different developmental stages. The boiling soluble protein profiles of shoots and seeds were outlined via SDS-PAGE followed by immune-blot analysis using anti-HSP, anti-APase, anti-LEA, anti-SOD, anti-AQUA and anti-CAT antibodies. Western blot analysis revealed that expression of BSPs was modulated differentially in a stress, tissue, developmental stage and cultivar dependent manner. For instance, enhanced expression of seeds BSPs (APase, LEA, CAT, AQUA) was observed in the tolerant cv. ‘PBW 527’ after drought stress. However, no such enhancement was observed in the susceptible cultivar. Similarly, in shoots of cv. ‘PBW 527’, a substantial increase of BSP (SOD) expression was established after drought stress treatment, indicating their role in drought stress adaptation. Further, to gain an insight into the role of BSPs, a time course pre- and post-stress kinetic studies were also conducted in the seeds of tolerant and susceptible wheat cultivars. Based upon the observations, the possible role of boiling soluble proteins (hydrophilins) in water stress tolerance is discussed.

Characterization of two paralogous StAR genes in a teleost, Nile tilapia (Oreochromis niloticus)

Steroidogenic acute regulatory protein (StAR) transports cholesterol, the substrate for steroid synthesis, to the inner membranes of mitochondria. It is well known that estrogen is essential for female sex determination/differentiation in fish. However, no reports showed that the conventional StAR, which was supposed to be essential for estrogen production, was expressed in female gonads during the critical timing of sex determination/differentiation. In this study, two different StAR isoforms, named as StAR1 and StAR2, were characterized from the gonads of Nile tilapia (Oreochromis niloticus). Phylogenetic and synteny analysis revealed that two StAR genes existed in teleosts, Xenopus and chicken indicating that the duplication event occurred before the divergence of teleosts and tetrapods. Real-time PCR revealed that StAR1 was dominantly expressed in the testis, head kidney and kidney; while StAR2 was expressed exclusively in the gonads. In situ hybridization and immunohistochemistry demonstrated that StAR1 was expressed in the interrenal cells of the head kidney and Leydig cells of the testis; while StAR2 was expressed in the Leydig cells of the testis and the interstitial cells of the ovary. Ontogenic analysis demonstrated that StAR2 was expressed abundantly from 5days after hatching (dah) in the somatic cells in XX gonads, whereas in XY gonads, both StARs could be detected from 30dah until adulthood. Intraperitoneal injection of human chorionic gonadotropin experiments showed that expression of StAR1 and 2 was significantly elevated at 8h and persisted until 24h after injection in the testis. Taken together, our data suggested that StAR1 is likely to be required for cortisol production in the head kidney, and StAR2 is probably involved in estrogen production during early sex differentiation in XX gonads. In contrast, both StARs might be required for androgen production in testes. For the first time, our data demonstrated that two fish StARs might be involved in steroidogenesis in a tissue and developmental stage dependent manner.

The effect of temperature gradients on endocrine signaling and antioxidant gene expression during Chironomus riparius development

Temperature is one of the most important environmental factors affecting the biological processes of aquatic species. To investigate the potential effects of temperature on the developmental processes of aquatic invertebrates, we analyzed biological and molecular transcriptional responses during Chironomus riparius development, including five stages spanning from embryo to adult stages. We assessed the temperature change-induced reduction of survival rate, changes in biological development including the male:female ratio in emerged adults, the success rates of pupation and emergence, and the developmental timing of pupation and emergence. The increased temperature induced expression of endocrine signaling genes, such as the ecdysone receptor, ultraspiracle (ortholog of the RXR), and the estrogen-related receptor in the fourth-instar larval and pupal stages of C. riparius development. Altered temperature also affected the activity of antioxidant genes, including catalase, peroxidase, glutathione peroxidase, and superoxide dismutase during the fourth-instar larval to adult stages of C. riparius development, as a result of altered development. Increased temperature during the fourth-instar larval stage increased oxidative stress in pupae and adults. Responses of antioxidant genes to increased temperature occurred in a developmental stage-dependent manner. However, reduced temperature did not induce the expression of antioxidant genes in a developmental stage-dependent manner, although it did induce oxidative stress during C. riparius development. Increased temperature also caused greater toxicity of di-ethylhexyl phthalate (DEHP) in fourth-instar larvae. Our findings suggest that altered temperatures may disturb the invertebrate hormone system and developmental processes by inducing oxidative stress in aquatic environments.

The Single-Stranded DNA-Binding Protein WHIRLY1 Represses WRKY53 Expression and Delays Leaf Senescence in a Developmental Stage-Dependent Manner in Arabidopsis

Leaf senescence in plants involves both positive and negative transcriptional regulation. In this work, we show evidence for the single-stranded DNA-binding protein WHIRLY1 (WHY1) that functions as an upstream suppressor of WRKY53 in a developmental stage-dependent manner during leaf senescence in Arabidopsis (Arabidopsis thaliana). The why1 mutant displayed an early-senescence phenotype. In this background, the expression levels of both WRKY53 and the senescence-associated protease gene SAG12 increased. WHY1 bound to the sequence region that contains an elicitor response element motif-like sequence, GNNNAAATT, plus an AT-rich telomeric repeat-like sequence in the WRKY53 promoter in in vivo and in vitro mutagenesis assays as well as in a chromatin immunoprecipitation assay. This binding to the promoter of WRKY53 was regulated in a developmental stage-dependent manner, as verified by chromatin immunoprecipitation-polymerase chain reaction assay. This direct interaction was further determined by a transient expression assay in which WHY1 repressed β-GLUCURONIDASE gene expression driven by the WRKY53 promoter. Genetic analysis of double mutant transgenic plants revealed that WHY1 overexpression in the wrky53 mutant (oeWHY1wrky53) had no effect on the stay-green phenotype of the wrky53 mutant, while a WHY1 knockout mutant in the wrky53 mutant background (why1wrky53) generated subtle change in the leaf yellow/green phenotype. These results suggest that WHY1 was an upstream regulator of WRKY53 during leaf senescence.

Spatiotemporal Secretion of PEROXIDASE36 Is Required for Seed Coat Mucilage Extrusion in Arabidopsis

The epidermal cells of the Arabidopsis thaliana seed coat, which correspond to the second layer of the outer integument (oi2), contain large quantities of a pectic polysaccharide called mucilage within the apoplastic space beneath the outer periclinal cell wall. Immediately after seed imbibition, the mucilage is extruded and completely envelops the seed in a gel-like capsule. We found that a class III peroxidase family protein, PEROXIDASE36 (PER36), functions as a mucilage extrusion factor. Expression of PER36 occurred only in oi2 cells for a few days around the torpedo stage. A PER36-green fluorescent protein fusion was secreted into the outer cell wall in a polarized manner. per36 mutants were defective in mucilage extrusion after seed imbibition due to the failure of outer cell wall rupture, although the mutants exhibited normal monosaccharide composition of the mucilage. This abnormal phenotype of per36 was rescued by pectin solubilization, which promoted cell wall loosening. These results suggest that PER36 regulates the degradation of the outer cell wall. Taken together, this work indicates that polarized secretion of PER36 in a developmental stage-dependent manner plays a role in cell wall modification of oi2 cells.

Propofol Anesthesia Impairs the Maturation and Survival of Adult-born Hippocampal Neurons

Adult neurogenesis occurs in the hippocampus of most mammals, including humans, and plays an important role in hippocampal-dependent learning. This process is highly regulated by neuronal activity and might therefore be vulnerable to anesthesia. In this article, the authors investigated this possibility by evaluating the impact of propofol anesthesia on mouse hippocampal neurons generated during adulthood, at two functionally distinct maturational stages of their development. Adult-born hippocampal neurons were identified using the cell proliferation marker bromodeoxyuridine or a retroviral vector expressing the green fluorescent protein in dividing cells and their progenies. Eleven or 17 days after the labeling procedure, animals (n = 3-5 animals per group) underwent a 6-h-long propofol anesthesia. Twenty-one days after labeling, the authors analyzed the survival, differentiation, and morphologic maturation of adult-born neurons using confocal microscopy. Propofol impaired the survival and maturation of adult-born neurons in an age-dependent manner. Anesthesia induced a significant decrease in the survival of neurons that were 17 days old at the time of anesthesia, but not of neurons that were 11 days old. Similarly, propofol anesthesia significantly reduced the dendritic maturation of neurons generated 17 days before anesthesia, without interfering with the maturation of neurons generated 11 days before anesthesia. These results reveal that propofol impairs the survival and maturation of adult-born hippocampal neurons in a developmental stage-dependent manner in mice.

Transcription‐induced chromatin association of RNA surveillance factors mediates facultative heterochromatin formation in fission yeast

Facultative heterochromatin is reversibly established and disrupted during differentiation, but its regulation remains mechanistically unclear. Here, we show that two meiotic gene loci in fission yeast, mei4 and ssm4, comprise facultative heterochromatin that is regulated in a developmental stage-dependent manner. This heterochromatin coordinates expression levels by associating with a chromodomain protein Chp1 and an antisilencing factor Epe1. It has been recently shown that an RNA surveillance machinery for eliminating meiotic gene transcripts, which involves a cis-element called the determinant of selective removal (DSR) and transacting factors, Mmi1 and Red1, also participates in heterochromatin formation at the meiotic genes, but the molecular mechanism underlying the process is largely unknown. By dissecting the mei4 gene, we identified a region that promotes DSR-dependent methylation of histone H3 lysine 9 (H3K9). Integration of this mei4 region together with DSR into an unrelated gene results in ectopic H3K9 methylation. Moreover, our results suggest that transcription of these elements induces chromatin association of Mmi1, which, in turn, recruits Red1 interacting with Clr4/Suv39h H3K9 methyltransferase. Mmi1 remains associated in cells lacking Red1, suggesting that the recruitment of Red1 follows the chromatin association of Mmi1. Overall, we provide detailed insights into the facultative heterochromatin regulation in fission yeast.

Characterization and expression patterns of microRNAs involved in rice grain filling.

MicroRNAs (miRNAs) are upstream gene regulators of plant development and hormone homeostasis through their directed cleavage or translational repression of the target mRNAs, which may play crucial roles in rice grain filling and determining the final grain weight and yield. In this study, high-throughput sequencing was performed to survey the dynamic expressions of miRNAs and their corresponding target genes at five distinct developmental stages of grain filling. In total, 445 known miRNAs and 45 novel miRNAs were detected with most of them expressed in a developmental stage dependent manner, and the majority of known miRNAs, which increased gradually with rice grain filling, showed negatively related to the grain filling rate. Detailed expressional comparisons revealed a clear negative correlation between most miRNAs and their target genes. It was found that specific miRNA cohorts are expressed in a developmental stage dependent manner during grain filling and the known functions of these miRNAs are involved in plant hormone homeostasis and starch accumulation, indicating that the expression dynamics of these miRNAs might play key roles in regulating rice grain filling.

IMP2 regulates differentiation potentials of mouse neocortical neural precursor cells

Neural precursor cells (NPCs) in the mammalian neocortex generate various neuronal and glial cell types in a developmental stage-dependent manner. Most neocortical NPCs lose their neurogenic potential after birth. We have previously shown that high-mobility group A (HMGA) proteins confer the neurogenic potential on early-stage NPCs during the midgestation period, although the underlying mechanisms are not fully understood. In this study, we found that HMGA2 promotes the expression of insulin-like growth factor 2 mRNA-binding protein 2 (IMP2, Igf2bp2) in neocortical NPCs. The level of IMP2 was indeed high in early-stage NPCs compared with that in late-stage NPCs. Importantly, over-expression of IMP2 increased the neurogenic potential and suppressed astrocytic differentiation of late-stage NPCs, whereas knockdown of IMP2 promoted astrocytic differentiation and reduced the neurogenic potential of early-stage neocortical NPCs without overtly affecting cell proliferation. Our results thus identified IMP2 as a developmental stage-dependent regulator of the differentiation potentials of NPCs in the mouse neocortex.

Gamma irradiation-induced oxidative stress and developmental impairment in the hermaphroditic fish, Kryptolebias marmoratus embryo

This study investigated the effects of gamma radiation on the early developmental stages in hermaphroditic fish embryos of Kryptolebias marmoratus. The authors measured reactive oxygen species (ROS) level and antioxidant enzyme activities with the endpoint hatching rate after gamma irradiation of different embryonic stages. Then, the transcriptional changes of antioxidant enzyme-coding genes were evaluated by quantitative real-time reverse transcription polymerase chain reaction in response to gamma radiation on embryonic stages. Gamma radiation inhibited hatching rate and caused developmental impairment in a dose-dependent manner. Embryos showed tolerances in a developmental stage-dependent manner, indicating that early embryonic stages were more sensitive to the negative effects of gamma radiation than were later stages. After 5 Gy rate of radiation, the ROS level increased significantly at embryonic stages 2, 3, and 4 with a significant induction of all antioxidant enzyme activities. The expressions of glutathione S-transferase isoforms, catalase, superoxide dismutase (Mn-SOD, Cu/Zn-SOD), glutathione reductase, and glutathione peroxidase mRNA were upregulated in a dose-and-developmental stage-dependent manner. This finding indicates that gamma radiation can induce oxidative stress and subsequently modulates the expression of antioxidant enzyme-coding genes as one of the defense mechanisms. Interestingly, embryonic stage 1 exposed to gamma radiation showed a decreased expression in most antioxidant enzyme-coding genes, suggesting that this is also related to a lower hatching rate and developmental impairment. The results of this study provide a better understanding of the molecular mode of action of gamma radiation in aquatic organisms.

HMGA regulates the global chromatin state and neurogenic potential in neocortical precursor cells

Neural precursor cells (NPCs) in the mouse neocortex generate various neuronal and glial cell types in a developmental stage–dependent manner. Most NPCs lose their neurogenic potential during development, although the underlying mechanisms of this process are not fully understood. We found that the chromatin of mouse NPCs gradually becomes more condensed and less dynamic on a global scale during neocortical development. Furthermore, we found high mobility group A (HMGA) proteins to be essential for the open chromatin state of NPCs at early developmental stages. Knockdown of HMGA proteins in early-stage NPCs reduced their neurogenic potential. Conversely, overexpression of HMGA proteins conferred neurogenic potential on late-stage NPCs, an effect that was antagonized by coexpression of a histone H1 mutant that inhibits chromatin opening. Thus, HMGA proteins contribute to the neurogenic potential of NPCs in the early stages of neocortical development, possibly through induction of an open chromatin state.

Gamma irradiation‐induced oxidative stress and developmental impairment in the hermaphroditic fish, Kryptolebias marmoratus embryo

This study investigated the effects of gamma radiation on the early developmental stages in hermaphroditic fish embryos of Kryptolebias marmoratus. The authors measured reactive oxygen species (ROS) level and antioxidant enzyme activities with the endpoint hatching rate after gamma irradiation of different embryonic stages. Then, the transcriptional changes of antioxidant enzyme-coding genes were evaluated by quantitative real-time reverse transcription polymerase chain reaction in response to gamma radiation on embryonic stages. Gamma radiation inhibited hatching rate and caused developmental impairment in a dose-dependent manner. Embryos showed tolerances in a developmental stage-dependent manner, indicating that early embryonic stages were more sensitive to the negative effects of gamma radiation than were later stages. After 5 Gy rate of radiation, the ROS level increased significantly at embryonic stages 2, 3, and 4 with a significant induction of all antioxidant enzyme activities. The expressions of glutathione S-transferase isoforms, catalase, superoxide dismutase (Mn-SOD, Cu/Zn-SOD), glutathione reductase, and glutathione peroxidase mRNA were upregulated in a dose-and-developmental stage-dependent manner. This finding indicates that gamma radiation can induce oxidative stress and subsequently modulates the expression of antioxidant enzyme-coding genes as one of the defense mechanisms. Interestingly, embryonic stage 1 exposed to gamma radiation showed a decreased expression in most antioxidant enzyme-coding genes, suggesting that this is also related to a lower hatching rate and developmental impairment. The results of this study provide a better understanding of the molecular mode of action of gamma radiation in aquatic organisms.

PDK1 regulates the generation of oligodendrocyte precursor cells at an early stage of mouse telencephalic development

During the development of the mouse telencephalon, multipotent neural precursor cells (NPCs) generate oligodendrocyte precursor cells (OPCs), progenitors restricted to the oligodendrocyte lineage, at various sites in a developmental stage-dependent manner. Although substantial progress has been made in identifying the transcription factors that control the production of OPCs, the signaling pathways that regulate these transcription factors and the spatiotemporal pattern of OPC production have been only partially clarified. Here, we show that the serine-threonine kinase 3-phosphoinositide-dependent kinase 1 (PDK1) contributes to an early wave of OPC production in the developing mouse telencephalon. Ablation of PDK1 in NPCs resulted in a reduction in the number of OPCs positive for Sox10 and platelet-derived growth factor receptor α (PDGFRα) within the neocortex and striatum at embryonic day (E) 15.5, but not at E18.5. Furthermore, pharmacological inhibition of phosphoinositide 3-kinase (PI3K) or deletion of the PDK1 gene suppressed the generation of OPCs from NPCs induced by fibroblast growth factor (FGF) 2 in culture. These results implicate the PI3K-PDK1 pathway in the physiological regulation of OPC production in a developmental context-dependent manner.

Pediatric Anesthesia Neurotoxicity

Through the years, care of millions of premature infants and young children has resulted in numerous exposures to a variety of anesthetic and sedative agents. These agents, designed to achieve the substantial depth of neuronal inhibition required for complete loss of consciousness and insensitivity to pain, are often a necessary component of successful treatment. However, data collected in animal models over the past decade suggest that general anesthetics damage developing neurons. Emerging animal and human data also suggest an association between early exposure to general anesthesia and long-term impairment of cognitive development. Consequently, the prudence of administering anesthesia to this population is now being scrutinized. Because general anesthesia cannot often be avoided when young children are diagnosed with conditions requiring surgery, or undergo time in intensive care units, the scientific community is focused on gaining a thorough understanding of the mechanisms of action so that we may take full advantage of the beneficial effects of anesthetics and sedatives without potentially devastating neurotoxic outcomes. A distinctive panel of speakers convened during SmartTots: Pediatric Anesthesia Neurotoxicity, a session at the 2011 International Anesthesia Research Society Annual Meeting, to provide an overview of 2 important lines of research. One focused on improving our knowledge of the cellular mechanisms operational in anesthetic-induced developmental neurotoxicity, and another focused on advancing our understanding of anesthesia-related neurobehavioral sequelae in mammalian species exposed to anesthesia during critical stages of brain development. Laszlo Vutskits, MD, PhD, University Hospitals of Geneva and Head, Neuroscience-oriented Anesthesia Research Group, University of Geneva, Switzerland, offered insight into recent experimental work demonstrating that general anesthetics have a major impact on the formation and elimination of synaptic contacts between neurons. The purpose of this presentation, “Beyond Toxicity: General Anesthetics and Synaptogenesis,” was to address (1) major neurodevelopmental events taking place during the brain growth spurt with a special emphasis on synaptogenesis, (2) the role of neural activity during neural network formation, and (3) how general anesthetics, being powerful modulators of neural activity, influence physiological patterns of synaptogenesis in a developmental stage–dependent manner. Vutskits reviewed basic neurobiological doctrines related to the brain growth spurt and recent observations suggesting that general anesthetics might stand as powerful regulators of synaptogenesis and thereby neural plasticity. Vutskits provided the following conclusions: (1) neural activity has a fundamental role during the assembly of the central nervous system; (2) functional properties of developing neural networks are fundamentally different between the early and late stage of the growth spurt, thus emphasizing the need for probing multiple time points; and (3) general anesthetics can rapidly induce developmental stage–dependent, persistent changes in synapse densities. Functional implications and significance of these conclusions remain unclear. Greg Stratmann, MD, PhD, Associate Professor of Clinical Anesthesia and Perioperative Care at the University of California, San Francisco, presented his research investigating whether anesthesia-induced cognitive decline is treatable. During his presentation, Stratmann discussed a conceptual framework of the neurocognitive deficit that may be caused by anesthesia in infancy, the concepts of prevention and treatment of anesthesia-induced neurocognitive decline, and the efficacy of an intervention designed to treat anesthesia-induced neurocognitive decline in rats. Stratmann reviewed his model for environmental enrichment and discussed his findings that the ill effects of anesthesia on brain function, which are apparent later in life, can be overcome when environmental enrichment is instituted up to 3 weeks after exposure to sevoflurane. These findings support the concept that harnessing the brain’s natural ability to adapt to functional demands can modify the course of anesthesia-induced cognitive decline in rats. He emphasized the need to understand if, and how, anesthesia changes brain function both in animals and in humans. Stratmann cautioned that clinical practice should not be changed until we are certain that a change is From the Departments of Anesthesiology and Neuroscience, University of Virginia Health System, Charlottesville, Virginia. Accepted for publication August 10, 2011. Supported by SmartTots. Conflict of Interest: See Disclosures at the end of the article. Reprints will not be available from the author. Address correspondence to Vesna Jevtovic-Todorovic, MD, PhD, MBA, University of Virginia Health System, Medical School/Steele Wing, PO Box 800710, Charlottesville, VA 22908. Address e-mail to VJ3W@hscmail. mcc.virginia.edu Copyright © 2011 International Anesthesia Research Society DOI: 10.1213/ANE.0b013e3182326622

Genes of Both Parental Origins Are Differentially Involved in Early Embryogenesis of a Tobacco Interspecies Hybrid

BackgroundIn animals, early embryonic development is largely dependent on maternal transcripts synthesized during gametogenesis. However, in higher plants, the extent of maternal control over zygote development and early embryogenesis is not fully understood yet. Nothing is known about the activity of the parental genomes during seed formation of interspecies hybrids.Methodology/Principal FindingsHere, we report that an interspecies hybridization system between SR1 (Nicotiana tabacum) and Hamayan (N. rustica) has been successfully established. Based on the system we selected 58 genes that have polymorphic sites between SR1 and Hamayan, and analyzed the allele-specific expression of 28 genes in their hybrid zygotes (Hamayan x SR1). Finally the allele-specific expressions of 8 genes in hybrid zygotes were repeatedly confirmed. Among them, 4 genes were of paternal origin, 1 gene was of maternal origin and 3 genes were of biparental origin. These results revealed obvious biparental involvement and differentially contribution of parental-origin genes to zygote development in the interspecies hybrid. We further detected the expression pattern of the genes at 8-celled embryo stage found that the involvement of the parental-origin genes may change at different stages of embryogenesis.Conclusions/SignificanceWe reveal that genes of both parental origins are differentially involved in early embryogenesis of a tobacco interspecies hybrid and functions in a developmental stage-dependent manner. This finding may open a window to seek for the possible molecular mechanism of hybrid vigor.

Predicted expansion of the claudin multigene family

Claudins (Cldn) are essential membrane proteins of tight junctions (TJs), which form the paracellular permselective barrier. They are produced by a multi-gene family of 24 reported members in mouse and human. Based on a comprehensive search combined with phylogenetic analyses, we identified three novel claudins (claudin-25, -26, and -27). Quantitative RT-PCR revealed that the three novel claudins were expressed in a tissue- and/or developmental stage-dependent manner. Claudins-25 and -26, but not claudin-27, were immunofluorescently localized to TJs when exogenously expressed in cultured MDCK and Eph epithelial cell lines. These findings expand the claudin family to include at least 27 members. Structured summary Claudin-25 and ZO-1 colocalize by fluorescence microscopy (View interaction) ZO-1 and Claudin-26 colocalize by fluorescence microscopy (View interaction)