Distension of the uterus induces HspB1 expression in rat uterine smooth muscle

The uterine musculature, or myometrium, demonstrates tremendous plasticity during pregnancy under the influences of the endocrine environment and mechanical stresses. Expression of the small stress protein heat shock protein B1 (HspB1) has been reported to increase dramatically during late pregnancy, a period marked by myometrial hypertrophy caused by fetal growth-induced uterine distension. Thus, using unilaterally pregnant rat models and ovariectomized nonpregnant rats with uteri containing laminaria tents to induce uterine distension, we examined the effect of uterine distension on myometrial HspB1 expression. In unilaterally pregnant rats, HspB1 mRNA and Ser(15)-phosphorylated HspB1 (pSer(15) HspB1) protein expression were significantly elevated in distended gravid uterine horns at days 19 and 23 (labor) of gestation compared with nongravid horns. Similarly, pSer(15) HspB1 protein in situ was only readily detectable in the distended horns compared with the nongravid horns at days 19 and 23; however, pSer(15) HspB1 was primarily detectable in situ at day 19 in membrane-associated regions, while it had primarily a cytoplasmic localization in myometrial cells at day 23. HspB1 mRNA and pSer(15) HspB1 protein expression were also markedly increased in ovariectomized nonpregnant rat myometrium distended for 24 h with laminaria tents compared with empty horns. Therefore, uterine distension plays a major role in the stimulation of myometrial HspB1 expression, and increased expression of this small stress protein could be a mechanoadaptive response to the increasing uterine distension that occurs during pregnancy.     

Strain uses gap junctions to reverse stimulation of osteoblast proliferation by osteocytes

Identifying mechanisms by which cells of the osteoblastic lineage communicate in vivo is complicated by the mineralised matrix that encases osteocytes, and thus, vital mechanoadaptive processes used to achieve load‐bearing integrity remain unresolved. We have used the coculture of immunomagnetically purified osteocytes and primary osteoblasts from both embryonic chick long bone and calvariae to examine these mechanisms. We exploited the fact that purified osteocytes are postmitotic to examine both their effect on proliferation of primary osteoblasts and the role of gap junctions in such communication. We found that chick long bone osteocytes significantly increased basal proliferation of primary osteoblasts derived from an identical source (tibiotarsi). Using a gap junction inhibitor, 18β‐glycyrrhetinic acid, we also demonstrated that this osteocyte‐related increase in osteoblast proliferation was not reliant on functional gap junctions. In contrast, osteocytes purified from calvarial bone failed to modify basal proliferation of primary osteoblast, but long bone osteocytes preserved their proproliferative action upon calvarial‐derived primary osteoblasts. We also showed that coincubated purified osteocytes exerted a marked inhibitory action on mechanical strain–related increases in proliferation of primary osteoblasts and that this action was abrogated in the presence of a gap junction inhibitor. These data reveal regulatory differences between purified osteocytes derived from functionally distinct bones and provide evidence for 2 mechanisms by which purified osteocytes communicate with primary osteoblasts to coordinate their activity.     

Cyanobacterial cell division: Genetics and comparative genomics of cyanobacterial cell division

Division of cyanobacteria serves as a model for studying division of plant chloroplasts. Analysis of mutants obtained by methods of “forward” and “reverse” genetics underlies effective strategy for studying genetics of cell division in these photoautotrophic prokaryotes. Comparative genomic analysis indicates that some cyanobacterial genes involved in the control of cell division have homologs among cyanobacteria, green algae, and higher plants, some others, only in bacteria, whereas the remaining genes are specific only for cyanobacteria.     

Six polymorphic microsatellite loci in the Natterjack toad,Bufo calamita

The Natterjack toad, Bufo calamita, is a locally endangered anuran endemic to Europe. It has been used as a model organism in several ecological studies. When studying the genetic structure of marginalized populations of the species, there was a need to involve more loci in the study than those previously published. Here we present the development of six polymorphic microsatellite loci in the Natterjack. The loci will be used for studying population genetic structure and gene flow between populations.     

Yeast Systems Biology: Model Organism and Cell Factory

For thousands of years, the yeast Saccharomyces cerevisiae (S. cerevisiae) has served as a cell factory for the production of bread, beer, and wine. In more recent years, this yeast has also served as a cell factory for producing many different fuels, chemicals, food ingredients, and pharmaceuticals. S. cerevisiae, however, has also served as a very important model organism for studying eukaryal biology, and even today many new discoveries, important for the treatment of human diseases, are made using this yeast as a model organism. Here a brief review of the use of S. cerevisiae as a model organism for studying eukaryal biology, its use as a cell factory, and how advances in systems biology underpin developments in both these areas, is provided.     

Computationally exact methods for stochastic periodic dynamics: Spatiotemporal dispersal and temporally forced transmission

The dynamics of many diseases and populations possess distinct recurring phases. For example, many species breed only during a subset of the year and the infection dynamics of many pathogens have transmission rates that vary with season. Here I investigate computational methods for studying transient and long-term behaviour of stochastic models which have periodic phases—several different potential techniques for studying long-term behaviour will be contrasted. I illustrate the results with two studies: The first is of a spatially realistic metapopulation model of malleefowl (Leipoa ocellata), a species which disperses only during a quarter of the year; this model is used to highlight the advantages and disadvantages of the particular methods presented. The second study is of a model for disease dynamics which incorporates seasonality in both the rate of within-population transmission and also in the rate of transmission effected via aerosol importation. This model has applications to studying disease invasion and persistence in captive-breeding populations. We demonstrate, via comparison to appropriately matched models with constant transmission rates and also no aerosol transmission, that seasonality and aerosol importation may alter control choices, with possibly an increase in the threshold population size for local control surveillance, transfer of importance to limiting aerosol transmission, and the use of temporally targetted surveillance. The methodology presented is the gold-standard for dealing with many phased processes in ecology and epidemiology, but its application is limited to systems of small size.     

Arabidopsis thaliana as a model for functional nectary analysis

Nectaries and nectar have received much research attention for well over 200 years due to their central roles in plant–pollinator interactions. Despite this, only a few genes have demonstrated impacts on nectary development, and none have been reported to mediate de novo nectar production. This scarcity of information is largely due to the lack of a model that combines sizeable nectaries, and high levels of nectar production, along with suitable genomics resources. For example, even though Arabidopsis thaliana has been useful for developmental studies, it has been largely overlooked as a model for studying nectary function due to the small size of its flowers. However, Arabidopsis nectaries, along with those of related species, are quite operational and can be used to discern molecular mechanisms of nectary form and function. A current understanding of the machinery underlying nectary function in plants is briefly presented, with emphasis placed on the prospects of using Arabidopsis as a model for studying these processes.     

Mechanical Vessel Injury in Zebrafish Embryos

Zebrafish (Danio rerio) embryos have proven to be a powerful model for studying a variety of developmental and disease processes. External development and optical transparency make these embryos especially amenable to microscopy, and numerous transgenic lines that label specific cell types with fluorescent proteins are available, making the zebrafish embryo an ideal system for visualizing the interaction of vascular, hematopoietic, and other cell types during injury and repair in vivo. Forward and reverse genetics in zebrafish are well developed, and pharmacological manipulation is possible. We describe a mechanical vascular injury model using micromanipulation techniques that exploits several of these features to study responses to vascular injury including hemostasis and blood vessel repair. Using a combination of video and timelapse microscopy, we demonstrate that this method of vascular injury results in measurable and reproducible responses during hemostasis and wound repair. This method provides a system for studying vascular injury and repair in detail in a whole animal model.     

Photoresponsivity and motility in the planarian Schmidtea mediterranea vary diurnally

ABSTRACT

The planarian flatworm has become one of the leading animal model systems for studying stem cell behavior and tissue regeneration. Recent studies have shown that components of the circadian clockwork have important roles in tissue homeostasis and repair. However, it remains unknown whether planarians exhibit circadian or diurnal rhythms in physiology or behavior. Here, we developed a behavioral assay to evaluate diurnal activity in planarians based upon their well-established propensity to swim away from light (negative phototaxis). We show evidence that the planarian Schmidtea mediterranea has diurnal variability in negative phototaxis as a function of daily variation in motility. We also demonstrate that variation in planarian motility over 48 h occurs with 24-h periodicity. Our data suggest that S. mediterranea may be a useful model for studying the interplay between the circadian system and tissue regeneration.     

Evidence for Carrier-Mediated Transport of Monosaccharides in the Ehrlich Ascites Tumor Cell

Evidence for carrier-mediated transport of monosaccharides in the Ehrlich ascites tumor cells was provided through kinetic analysis of data obtained by: (a) studying sugar uptake by dilute cell suspensions with an optical densimetric apparatus, (b) studying sugar uptake by thicker cell suspensions by means of direct chemical analytical methods using packed cell plugs, (c) observing the effects of a competitive inhibitor upon sugar uptake with the chemical analytical method, and (d) measurement of tracer uptake of a high affinity sugar in thick cell suspensions in the absence of net movement. Quantitative application of the data obtained with the above experimental procedures to theoretical model systems derived for both carrier-mediated transport and simple passive diffusion indicated that the results were consonant with predictions for the carrier-mediated transport model, but could not be explained on the basis of uncomplicated diffusion.     

Altered tracheal smooth muscle activities in an animal model of human myotonic dystrophy.

Although the 20,25 Diazacholesterol-treated rat exhibits several pathological changes involving skeletal muscle and other tissues resembling those seen in human myotonic dystrophy patients, this animal has not hitherto been examined as a model for studying smooth muscle involvement in this human disease. Rats were therefore treated chronically with 20, 25-D and comparisons made with control animals of dose-response curves of tracheal strip preparations to carbamylcholine, before and after partial irreversible blockade of cholinergic receptors by Dibenamine. Tracheas from myotonic animals exhibited diminished contractility and an increased ED₅₀. The dissociation constant for the carbamylcholine-cholinergic receptor interaction was decreased and the percentage receptor occupancy for a given contractile response was increased. These results indicate that tracheal smooth muscle function is altered after 20,25-D administration and suggest that such animals may constitute a model for studying smooth muscle function in human myotonic dystrophy.     

Suppression of penetrative hyphae ofRhizopus oligosporus by membrane filters in a model solid-state fermentation system

Summary Membrane filters overlaid on slabs of a model solid substrate enabled recovery of biomass ofRhizopus oligosporus. Although the presence of the membrane filter affects the growth ofRhizopus oligosporus it provides a useful tool for studying solid-state fermentation.     

Fluorescence in situ hybridization for phytoplasma and endophytic bacteria localization in plant tissues

In the present study, we developed a rapid and efficient fluorescence in situ hybridization assay (FISH) in non-embedded tissues of the model plant Catharanthus roseus for co-localizing phytoplasmas and endophytic bacteria, opening new perspectives for studying the interaction between these microorganisms.     

Numerical investigation of a microwave discharge driven by the H 10-type wave

A two-dimensional numerical model is proposed for studying a steady microwave discharge driven by the H ₁₀-type wave. The parameters of a discharge in nitrogen at atmospheric pressure are calculated. The results obtained agree qualitatively with the experimental data.     

Molecular cloning,characterization and expression analysis of ATG1 in the silkworm, Bombyx mori

Atg1 is a Serine/Threonine protein kinase that plays a pivotal role in autophagy. A complete coding sequence of ATG1 is not available for the silkworm, Bombyx mori which is a good model for studying the autophagic process.     

Th17 Inflammation Model of Oropharyngeal Candidiasis in Immunodeficient Mice

Oropharyngeal Candidiasis (OPC) disease is caused not only due to the lack of host immune resistance, but also the absence of appropriate regulation of infection-induced immunopathology. Although Th17 cells are implicated in antifungal defense, their role in immunopathology is unclear. This study presents a method for establishing oral Th17 immunopathology associated with oral candidal infection in immunodeficient mice. The method is based on reconstituting lymphopenic mice with in vitro cultured Th17 cells, followed by oral infection with Candida albicans (C. albicans). Results show that unrestrained Th17 cells result in inflammation and pathology, and is associated with several measurable read-outs including weight loss, pro-inflammatory cytokine production, tongue histopathology and mortality, showing that this model may be valuable in studying OPC immunopathology. Adoptive transfer of regulatory cells (T_regs) controls and reduces the inflammatory response, showing that this model can be used to test new strategies to counteract oral inflammation. This model may also be applicable in studying oral Th17 immunopathology in general in the context of other oral diseases.     

Prostaglandin production by human epidermal cells in vitro: A model for studying pharmacologic inhibition of prostaglandin synthesis

An inv itro model for studying the biosynthesis of prostaglandins by isolated human epidermal cells is described. Production of prostaglandin E₂-equivalent activity over an 18-hour incubation period was measured using a radioimmunoassay. Prostaglandin production was significantly inhibited by indomethacin and aspirin in a concentration-dependent manner.     

Genetic population structure of the alpine species Rhododendron pseudochrysanthum sensu lato (Ericaceae) inferred from chloroplast and nuclear DNA

Background  

A complex of incipient species with different degrees of morphological or ecological differentiation provides an ideal model for studying species divergence. We examined the phylogeography and the evolutionary history of the Rhododendron pseudochrysanthum s. l.     

A predictive model for the spontaneous synchronization of Saccharomyces cerevisiae grown in continuous culture. I. Concept

A structured segregated model was developed for studying spontaneous oscillations of S. cerevisiae in continuous culture. The model is based on cells of a simple metabolic structure and assumptions about the modification of this structure during the cell cycle. The most important features of the model cells are the ability to grow on ethanol and glucose simultaneously in continuous culture, the accumulation of intracellular storage carbohydrates during the single cell phase and their mobilization during the budding phase. The model predicts oscillations of considerable similarity to those observed in experiments.     

Metabolomic and flux‐balance analysis of age‐related decline of hypoxia tolerance in Drosophila muscle tissue

The fruitfly Drosophila melanogaster is increasingly used as a model organism for studying acute hypoxia tolerance and for studying aging, but the interactions between these two factors are not well known. Here we show that hypoxia tolerance degrades with age in post‐hypoxic recovery of whole‐body movement, heart rate and ATP content. We previously used ¹H NMR metabolomics and a constraint‐based model of ATP‐generating metabolism to discover the end products of hypoxic metabolism in flies and generate hypotheses for the biological mechanisms. We expand the reactions in the model using tissue‐ and age‐specific microarray data from the literature, and then examine metabolomic profiles of thoraxes after 4 h at 0.5% O₂ and after 5 min of recovery in 40‐ versus 3‐day‐old flies. Model simulations were constrained to fluxes calculated from these data. Simulations suggest that the decreased ATP production during reoxygenation seen in aging flies can be attributed to reduced recovery of mitochondrial respiration pathways and concomitant overdependence on the acetate production pathway as an energy source.