Expression analysis of some genes regulated by retinoic acid in controls and triadimefon‐exposed embryos: is the amphibian Xenopus laevis a suitable model for gene‐based comparative teratology?

BACKGROUND: The use of nonmammal models in teratological studies is a matter of debate and seems to be justified if the embryotoxic mechanism involves conserved processes. Published data on mammals and Xenopus laevis suggest that azoles are teratogenic by altering the endogenous concentration of retinoic acid (RA). The expression of some genes (Shh, Ptch‐1, Gsc, and Msx2) controlled by retinoic acid is downregulated in rat embryos exposed at the phylotypic stage to the triazole triadimefon (FON). In order to propose X. laevis as a model for gene‐based comparative teratology, this work evaluates the expression of Shh, Ptch‐1, Gsc, and Msx2 in FON‐exposed X. laevis embryos. METHODS: Embryos, exposed to a high concentration level (500 µM) of FON from stage 13 till 17, were examined at stages 17, 27, and 47. Stage 17 and 27 embryos were processed to perform quantitative RT‐PCR. RESULTS: The developmental rate was never affected by FON at any considered stage. FON‐exposed stage 47 larvae showed the typical craniofacial malformations. A significant downregulation of Gsc was observed in FON‐exposed stage 17 embryos. Shh, Ptch‐1, Msx2 showed a high fluctuation of expression both in control and in FON‐exposed samples both at stages 17 and 27. CONCLUSION: The downregulation of Gsc mimics the effects of FON on rat embryos, showing for this gene a common effect of FON in the two vertebrate classes. The high fluctuation observed in the gene expression of the other genes, however, suggests that X. laevis at this stage has limited utility for gene‐based comparative teratology. Birth Defects Res (Part B) 92:189–194, 2011. © 2011 Wiley‐Liss, Inc.     

The effects of seed availability on habitat use by a specialist seed predator

Space-use patterns of seed predators are strongly affected by spatiotemporal variation in the abundance of different tree seeds, their major food source. However, most studies have measured relationships between overall food availability and space use, and there are few cases where effects of different food resources have been explored. We studied the effects of two food resources, Norway spruce and silver fir seeds, on space and habitat use in red squirrel in a subalpine conifer forest from 2000 to 2006. Fir seeds disperse in the autumn of the year they are produced, spruce the following spring. We estimated spruce and fir seed availability within individual home ranges and monitored home-range size using radiotelemetry. Males had larger home ranges than females and the sexes responded differently to variation in food and density. Spruce seed availability negatively affected home-range and core-area sizes of males in spring–summer. Space use was not affected by fir seed availability. Squirrels positively selected spruce for foraging and spruce was always preferred over fir. Our results showed that spruce, but not fir, affected space and habitat use of squirrels, suggesting they do not behaviourally respond to early seed dispersal in fir.     

Associations between the masticatory system and muscle activity of other body districts. A meta-analysis of surface electromyography studies

The aim of this meta-analysis regarding the use of surface electromyography (sEMG) is to assess the scientific evidence for detectable correlations between the masticatory system and muscle activity of the other body districts, particularly those mainly responsible for body posture. A literature survey was performed using the PubMed database, covering the period from January 1966 to April 2011, and choosing medical subject headings. After selection, five articles qualified for the final analysis. One study article was judged to be of medium quality, the remaining four of low quality. No study included a control group or follow-up; in only one study, subjects with impairment of the masticatory system were enrolled. In all studies, detectable correlations between the masticatory systems and muscle activity of the other body districts, or vice versa, were found; however, after a reappraisal of the data provided in these studies, only weak correlations were found, which reached biological, but not clinical relevance. With the limitations that arise from the poor methodological quality of the published study reports discussed here, the conclusion is that a correlation between the masticatory system and muscle activity of the other body districts might be detected through sEMG under experimental conditions; however, this correlation has little clinical relevance. While more investigations with improved levels of scientific evidence are needed, the current evidence does not support clinically relevant correlations between the masticatory system and the muscle activity of other body districts, including those responsible for body posture.     

Molecular pathways involved in the cyclic activity of frog (Pelophylax esculentus) Harderian gland: Influence of temperature and testosterone

The Harderian gland of Pelophylax esculentus (previously: Rana esculenta) shows seasonal secretory activity changes. Specifically, the secretory activity reaches a maximum during the hottest months, i.e., July and August, drops in September and slowly increases from October onwards. Expressions of P-CaMKII, P-ERK1 and P-Akt1 correlate well with gland secretory activity; i.e., they peak immediately before the hottest part of the year (maximum secretory activity). When the gland activity declines, kinase expressions drop and remain low until February. Experiments of thermal manipulation indicate that high temperature induces the activation of CaMKII, ERK1 and Akt1, and at low temperatures, Akt1 expression decreases. Experiments of chemical castration indicate that the Harderian gland of Cyproterone acetate-treated frogs shows lower Akt1 activity as compared to controls, but the CaMKII and ERK1 activities remain unchanged. Furthermore, in a period of resumed gland activity (October–December) we observed the highest expression of PCNA, a mitotic marker. Immediately after the proliferative phase, we found the highest expression of caspase 3, an enzyme that plays a key role in apoptosis. In combination, the results suggest the following: 1) CaMKII, ERK1, and Akt1 modulate the annual secretory activity of the frog Harderian gland; 2) CaMKII and ERK1 activities are regulated by temperature, whereas both temperature and testosterone likely play a central role in Akt1 regulation; and 3) proliferation and apoptosis occur to restore and balance, respectively, an adequate cell number, which is essential to gland function.     

Oral candidosis: characterization of a sample of recurrent infections and study of resistance determinants

Recurrent oral candidosis is a common problem in immunocompromised patients, and it is frequently triggered by resistance induced by antifungal treatment. Knowledge of the mechanisms by which the yeast persists in the host could allow the management of this type of infection. This study used electrophoretic karyotyping and restriction fragment length polymorphism based on the use of 27A probe to study 12 pairs of Candida albicans isolates from patients with recurrent candidosis to distinguish new infections from relapses caused by the same strain responsible for the first episode. Subsequently, RT-PCR was used to evaluate expression of CDR1, CDR2 and MDR1 genes, which are involved in C. albicans azole resistance, in the three pairs that consisted of variants of the same strain. Restriction polymorphism resulted in better discrimination than with karyotyping in defining differences between strains. In one case, RT-PCR allowed us to identify deregulation of efflux pump genes as the possible underlying mechanism in recurrent candidosis. The techniques employed resulted effective for the characterization of recurrent oral candidosis. Broader analysis could help to control better these infections and choose adequate therapy.     

DNA strand breaks and base modifications induced by cholesterol hydroperoxides

Cholesterol (Ch) can be oxidized by reactive oxygen species, forming oxidized products such as Ch hydroperoxides (ChOOH). These hydroperoxides can disseminate the peroxidative stress to other cell compartments. In this work, the ability of ChOOH to induce strand breaks and/or base modifications in a plasmid DNA model was evaluated. In addition, HPLC/MS/MS analyses were performed to investigate the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) after the incubation of 2'-deoxyguanosine (dGuo) with ChOOH and Cu(2+). In the presence of copper ions, ChOOH induced DNA strand breaks in time and concentration-dependent manners. Purine and pyrimidine base modifications were also observed, as assessed respectively by the treatment with Fpg and Endo III repair enzymes. The detection of 8-oxodGuo by HPLC/MS/MS is in agreement with the dGuo oxidation in plasmid DNA. ChOOH-derived DNA damage adds further support to the role of lipid peroxidation in inducing DNA modifications and mutation.     

Human epicardium-derived cells fuse with high efficiency with skeletal myotubes and differentiate toward the skeletal muscle phenotype: a comparison study with stromal and endothelial cells

Recent studies have underscored a role for the epicardium as a source of multipotent cells. Here, we investigate the myogenic potential of adult human epicardium-derived cells (EPDCs) and analyze their ability to undergo skeletal myogenesis when cultured with differentiating primary myoblasts. Results are compared to those obtained with mesenchymal stromal cells (MSCs) and with endothelial cells, another mesodermal derivative. We demonstrate that EPDCs spontaneously fuse with pre-existing myotubes with an efficiency that is significantly higher than that of other cells. Although at a low frequency, endothelial cells may also contribute to myotube formation. In all cases analyzed, after entering the myotube, nonmuscle nuclei are reprogrammed to express muscle-specific genes. The fusion competence of nonmyogenic cells in vitro parallels their ability to reconstitute dystrophin expression in mdx mice. We additionally show that vascular cell adhesion molecule 1 (VCAM1) expression levels of nonmuscle cells are modulated by soluble factors secreted by skeletal myoblasts and that VCAM1 function is required for fusion to occur. Finally, treatment with interleukin (IL)-4 or IL-13, two cytokines released by differentiating myotubes, increases VCAM1 expression and enhances the rate of fusion of EPDCs and MSCs, but not that of endothelial cells.     

The larva of Eustra (Coleoptera, Paussinae, Ozaenini):a facultative associate of ants

Larvae of the ground beetle genus Eustra Schmidt-Goebel are described and illustrated for the first time and some biological notes are reported. One specimen of an unknown Eustra species was collected while excavating a nest of the ant Pachycondyla javana Mayr, in Taiwan, which is the first report of a paussine associated with a member of the ant subfamily Ponerinae. Several larvae and adults of a second species, Eustra chinensis Bänninger, were collected in Shanghai under bark with no association with ants. First instar larvae of the latter species were also reared in the lab. The occurrence of larvae of the genus Eustra both inside and outside ant nests, together with a report of adults collected inside a nest in Taiwan, suggests that members of this genus may be facultative predators or facultative symbionts of ants, an attribute that has never been reported for this genus. The larvae of Eustra show several unique features, including a peculiar bidentate mandibular apex, an extremely long galea, one of two tarsal claws greatly reduced, abdominal setae (including those of terminal disk) elongate and clavate at apex, urogomphi wide and flattened, and inflated sensilla S-I. Larvae were studied by both optical and scanning electron microscopy, their morphological features are compared with those of other described Paussinae larvae, and their potential phylogenetic and functional significance are discussed.     

Mutation discovery in mice by whole exome sequencing

We report the development and optimization of reagents for in-solution, hybridization-based capture of the mouse exome. By validating this approach in a multiple inbred strains and in novel mutant strains, we show that whole exome sequencing is a robust approach for discovery of putative mutations, irrespective of strain background. We found strong candidate mutations for the majority of mutant exomes sequenced, including new models of orofacial clefting, urogenital dysmorphology, kyphosis and autoimmune hepatitis.     

A complete skull of an early cretaceous sauropod and the evolution of advanced titanosaurians

Advanced titanosaurian sauropods, such as nemegtosaurids and saltasaurids, were diverse and one of the most important groups of herbivores in the terrestrial biotas of the Late Cretaceous. However, little is known about their rise and diversification prior to the Late Cretaceous. Furthermore, the evolution of their highly-modified skull anatomy has been largely hindered by the scarcity of well-preserved cranial remains. A new sauropod dinosaur from the Early Cretaceous of Brazil represents the earliest advanced titanosaurian known to date, demonstrating that the initial diversification of advanced titanosaurians was well under way at least 30 million years before their known radiation in the latest Cretaceous. The new taxon also preserves the most complete skull among titanosaurians, further revealing that their low and elongated diplodocid-like skull morphology appeared much earlier than previously thought.