Molecular phylogeny of the springhare, Pedetes capensis, based on mitochondrial DNA sequences

The phylogenetic position of the Pedetidae, represented by a single species Pedetes capensis, is controversial, reflecting in part the retention of both Hystricomorphous and Sciurognathous characteristics in this rodent. In an attempt to clarify the species evolutionary relationships, mtDNA gene sequences from 10 rodent species (representing seven families) were analyzed using phenetic, parsimony, and maximum-likelihood methods of phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as outgroups. Investigation of 714 base pairs of the protein-coding cytochrome b gene indicate strong base bias at the third codon position with significant rate heterogeneity evident between the three structural domains of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA gene revealed a transversion bias in the loop sections of all taxa. The cytochrome b gene sequences proved useful in resolving associations between closely related species but failed to produce consistent tree topologies at the family level. In contrast, phylogenetic analysis of the 12S rRNA gene resulted in strong support for the clustering of Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is concordant with studies of rodent fetal membranes as well as reproductive and other anatomical features.      

Immunological similarities between microsomal, cytosolic and nuclear progesterone receptors in the chick oviduct

Progesterone receptor of microsomal, cytosolic and nuclear fractions of the chick oviduct was studied by using biochemical, immunochemical and immunohistochemical analyses. In the oviducts of estrogen-treated immature chicks cytosolic, microsomal and nuclear PR were 90, 9.6 and 0.4% of the total binding, respectively, whereas the corresponding values 1 h after progesterone administration were 33, 6 and 61%, respectively. Progesterone decreased the cytosolic and microsomal PR 90 and 88%, respectively. All the receptor forms were similarly recognized by anti-PR-IgG raised against B-subunit of the PR. By using a sensitive immunoelectron microscopy in most cells of the oviduct only nuclear PR antigen was detected both in estrogen-treated and estrogen-progesterone-treated chick oviductal cells. In most cells no PR was found in the cytoplasm nor in the microsomes. Occasionally in very few cells small amounts of PR were found, associated with rough endoplasmic reticulum close to the nucleus containing a high concentration of the PR. This is probably due to a nascent synthesis of the PR. It is concluded that the major part of the cytosolic as well as microsomal PR is due to a homogenization artefact caused by a redistribution of the unoccupied PR located in the nuclei in situ.     

Intestinal barrier function in response to abundant or depleted mucosal glutathione in Salmonella-infected rats

Background  

Glutathione, the main antioxidant of intestinal epithelial cells, is suggested to play an important role in gut barrier function and prevention of inflammation-related oxidative damage as induced by acute bacterial infection. Most studies on intestinal glutathione focus on oxidative stress reduction without considering functional disease outcome. Our aim was to determine whether depletion or maintenance of intestinal glutathione changes susceptibility of rats to Salmonella infection and associated inflammation.     

A novel tissue-slice culture model for non-malignant human prostate

A novel tissue culture system was established for modeling the non-neoplastic human prostate in vitro. Precision-cut prostate slices were cultivated in culture plates with a gas-permeable base in a novel serum-free mixture. Cultivated specimens was evaluated by an immunohistochemical analysis of cytokeratins 18 and 14, androgen receptor (AR), prostate specific antigen (PSA), prostate acid phosphatase (PAP), and the endothelial cell marker von Willebrand factor. Epithelial viability in the presence and absence of dihydrotestosterone (DHT) was also assessed. Satisfactory maintenance of glandular cytoarchitecture was observed in the presence of DHT with approximately half of the glands displaying a columnar or cuboidal phenotype and an intact layer of basal cells. In the absence of DHT, the corresponding percentage was significantly lower. The occurrence of involutive changes and epithelial cell death was significantly higher in the absence of DHT. Glandular and stromal cells maintained their capacity to express AR. PSA and PAP were expressed throughout the culture period, albeit at a lower level than in uncultured tissue. The viability of endothelial cells differed markedly between individual samples. During culture, the tissue slices became covered with epithelial cells originating from glands that were cut open during tissue slicing. This cell layer consisted of a stratified basal compartment overlaid by cells with a luminal phenotype. The present culture system provides a novel in vitro setting in which to study normal human prostate biology and pathobiology and may help to obviate problems related to the use of established cancer cell lines and animal models. This study was supported by grants from competitive research funding of the Pirkanmaa Hospital District, TEKES Drug 2000, and the Juliana von Wendt Fund.     

Heat shock protein 90 and the nuclear transport of progesterone receptor

Steroid receptors exist as large oligomeric complexes in hypotonic cell extracts. In the present work, we studied the nuclear transport of the 2 major components of the oligomeric complex, the receptor itself and the heat shock protein 90 (Hsp90), by using different in vitro transport systems: digitonin permeabilized cells and purified nuclei. We demonstrate that the stabilized oligomeric complex of progesterone receptor (PR) cannot be transported into the nucleus and that unliganded PR salt dissociated from Hsp90 is transported into the nucleus. When nonstabilized PR oligomer was introduced into the nuclear transport system, the complex dissociated and the PR but not the Hsp90 was transported into the nucleus. If PR exists as an oligomeric form after synthesis, as suggested by the experiments with reticulocyte lysate, the present results suggest that the complex is short-lived and is dissociated before or during nuclear transport. Thus, the role of Hsp90 in PR action is likely to reside in the Hsp90-assisted chaperoning process of PR preceding nuclear transport of the receptor.     

Absolute versus per unit body length speed of prey as an estimator of vulnerability to predation

To study whether absolute (m/s) or relative (body lengths/s) speed should be used to compare the vulnerability of differently sized animals, we developed a simple computer simulation. Human 'predators' were asked to 'catch' (mouse-click) prey of different sizes, moving at different speeds across a computer screen. Using the simulation, a prey's chances of escaping predation depended on its speed (faster prey were more difficult to catch than slower prey of the same body size), but also on its size (larger prey were easier to catch than smaller prey at the same speed). Catching time, the time needed to catch a prey, also depended on both prey speed and prey size. Relative prey speed (body lengths/s or body surface/s) was a better predictor of catching time than was absolute prey speed (m/s). Our experiment demonstrates that, in contrast to earlier assertions, per unit body length speed of prey may be more 'ecologically relevant' than absolute speed. Copyright 1998 The Association for the Study of Animal Behaviour.     

Maturation of human pluripotent stem cell derived cardiomyocytes is improved in cardiovascular construct

In order to translate preclinical data into the clinical studies, relevant in vitro models with structure and key functional properties similar to native human tissue should be used. In vitro cardiac models with vascular structures mimic the highly vascularized myocardium and provide interactions between endothelial cells, stromal cells and cardiomyocytes. Currently, human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have been shown to present immature morphology and fetal-like electrophysiological properties that may limit their use as physiological test platform. The aim of this study was to develop multicellular in vitro cardiovascular construct modeling human heart tissue. In the cardiovascular construct, hPSC-CMs were cultured with a vascular-like network formed by human foreskin fibroblasts and human umbilical vein endothelial cells that served as a platform in the construct. Cardiomyocyte orientation, maturation, electrophysiological properties and drug responses of the cardiovascular construct were characterized and compared to CM monoculture. hPSC-CMs in cardiovascular construct showed elongated morphology and aligned with the vascular-like network. Electrophysiological properties and calcium metabolism of hPSC-CMs as well as response to E-4031 and adrenaline demonstrated normal physiological behavior. Increased expression of cardiac structural proteins and ion channels in cardiovascular construct compared to CM monoculture were detected. In conclusion, vascular-like network supports the structural and functional maturation of hPSC-CMs. Our results suggest that cardiovascular construct presents more mature in vitro cardiac model compared to CM monoculture and could therefore serve as an advanced test system for cardiac safety and efficacy assessment as well as a model system for biomedical research.