hosimary: a new hAT transposon group involved in horizontal transfer

A PCR screening approach was used to search for sequences homologous to a previously described hAT transposon found in Drosophila simulans and Drosophila sechellia, named here as hosimary. In this study, 52 Drosophilidae species were analyzed and these sequences seem to be restricted to some species of the melanogaster group and Zaprionus indianus. These species present variable number of copies and most of those appear to be putatively encoding. The high hosimary sequences similarity among different species and the patchy distribution presented by this transposon strongly support the hypothesis that hosimary was horizontally transferred between the melanogaster group species and Z. indianus.     

Is the association between optimistic cardiovascular risk perceptions and lower rates of cardiovascular disease mortality explained by biomarkers of systemic inflammation or endothelial function? A case-cohort study

Background  

More optimistic perceptions of cardiovascular disease risk are associated with substantively lower rates of cardiovascular death among men. It remains unknown whether this association represents causality (i.e. perception leads to actions/conditions that influence cardiovascular disease occurrence) or residual confounding by unmeasured factors that associate with risk perceptions and with physiological processes that promote cardiovascular disease (i.e. inflammation or endothelial dysfunction).     

Generalized arterial calcification of infancy and pseudoxanthoma elasticum can be caused by mutations in either ENPP1 or ABCC6

Spontaneous pathologic arterial calcifications in childhood can occur in generalized arterial calcification of infancy (GACI) or in pseudoxanthoma elasticum (PXE). GACI is associated with biallelic mutations in ENPP1 in the majority of cases, whereas mutations in ABCC6 are known to cause PXE. However, the genetic basis in subsets of both disease phenotypes remains elusive. We hypothesized that GACI and PXE are in a closely related spectrum of disease. We used a standardized questionnaire to retrospectively evaluate the phenotype of 92 probands with a clinical history of GACI. We obtained the ENPP1 genotype by conventional sequencing. In those patients with less than two disease-causing ENPP1 mutations, we sequenced ABCC6. We observed that three GACI patients who carried biallelic ENPP1 mutations developed typical signs of PXE between 5 and 8 years of age; these signs included angioid streaks and pseudoxanthomatous skin lesions. In 28 patients, no disease-causing ENPP1 mutation was found. In 14 of these patients, we detected pathogenic ABCC6 mutations (biallelic mutations in eight patients, monoallelic mutations in six patients). Thus, ABCC6 mutations account for a significant subset of GACI patients, and ENPP1 mutations can also be associated with PXE lesions in school-aged children. Based on the considerable overlap of genotype and phenotype of GACI and PXE, both entities appear to reflect two ends of a clinical spectrum of ectopic calcification and other organ pathologies, rather than two distinct disorders. ABCC6 and ENPP1 mutations might lead to alterations of the same physiological pathways in tissues beyond the artery.     

Case report: probable transmission of vaccine strain of yellow fever virus to an infant via breast milk

The 17D yellow fever vaccine is a live-virus vaccine that has been in use since the 1940s. The incidence of encephalitis after yellow fever vaccination among young infants is much higher than among children older than nine months of age. Until recently, avoidance of vaccination by breastfeeding women who have received yellow fever vaccine had been based on theoretical grounds only. We report the probable transmission of vaccine strain of yellow fever virus from a mother to her infant through breastfeeding.A previously healthy five-week-old male infant presented to hospital with a two-day history of fever and irritability. The day before his admission, he had been noted to have focal seizures on alternating sides. He had poor appetite and had vomited once, but did not develop diarrhea or rash. His fever was preceded by a two-week history of nonspecific rhinorrhea and cough.A left-sided focal seizure was witnessed in the emergency department. At that time, his temperature was 38°C, his respiratory rate was 60 breaths/min, his pulse was 164 beats/min and his oxygen saturation was 93% on room air. He was irritable, with a full anterior fontanelle, nasal congestion, supple neck, and normal tone and reflexes. The remainder of his examination was unremarkable.The patient had been born vaginally at term. His mother had tested positive on a vaginal swab test for group B streptococcus and had received appropriate intrapartum antibiotics. When the infant was 10 days of age, his mother had received pretravel advice and travel vaccinations. She had been given yellow fever vaccine along with inactivated typhoid vaccine and did not report substantial adverse effects. Three days later, the infant and his mother had departed to Venezuela for one week. They had stayed exclusively in the city of Caracas, and breastfeeding was continued. The baby had showed no insect bites nor had contact with sick people, nor had he been exposed to animals in Canada or abroad. There was no history of herpes infection in family members. He had not received any vaccinations before presentation. Before the onset of his symptoms, his sister (aged five years) and father had upper respiratory tract symptoms. The infant was brought to hospital 20 days after returning to Canada.Anticonvulsants were administered initially to control seizures, along with empiric ampicillin, cefotaxime and acyclovir at doses appropriate for treating meningitis. Abnormalities on results of a complete blood count included a platelet count of 740 (normal 150–400) × 10⁹/L and a total leukocyte count of 13.2 (normal 4.0–11.0) × 10⁹/L. Serum electrolytes and levels of calcium and magnesium were normal. A computed tomographic scan of the head was normal, and a lumbar puncture was performed. Cerebrospinal fluid parameters were abnormal, with a total leukocyte count of 128.9 × 10⁶ with 30% neutrophils, 32% lymphocytes and 36% monocytes. No red blood cells and no xanthochromia were seen. Glucose was 2.2 (serum 4.3) mmol/L and protein was elevated at 1.1 g/L. Bacterial cultures of blood, urine and cerebrospinal fluid were negative, as was polymerase chain reaction testing of cerebrospinal fluid for herpes simplex virus and enteroviruses. Nucleic acid sequence-based amplification on a nasopharyngeal specimen was also negative for enterovirus.An electroencephalogram was performed and showed multifocal, potentially epileptogenic discharges. A repeat study 10 days later showed lateral temporal spikes consistent with encephalitis. Magnetic resonance imaging of the head revealed meningeal enhancement in the frontoparietal regions that was consistent with meningoencephalitis. Antibiotics were discontinued after bacterial cultures were reported negative, and the infant was given a 21-day course of acyclovir. His fever resolved after two days, and he had no further seizures. He was discharged with no medication after completion of the course of acyclovir and a normal neurologic exam. A follow-up evaluation five months later confirmed normal development and absence of neurologic deficit. The timeline of events is shown in Figure 1.Open in a separate windowFigure 1:Timeline of events surrounding probable transmission of vaccine strain of yellow fever virus to an infant via breastfeeding.A serum sample taken on the patient’s admission to hospital was reported to be positive for yellow fever on an IgM capture enzyme-linked immunosorbent assay from the Centers for Disease Control and Prevention. A serum-dilution–plaque-reduction neutralization test for yellow fever was also positive at a titre of 1:5120, and the yellow fever hemagglutination inhibition titre was 1:160. Yellow fever IgG was negative. In addition, a sample of cerebrospinal fluid taken on admission was reported by the Centers for Disease Control and Prevention to be positive for yellow fever antigen by IgM capture enzyme-linked immunosorbent assay, but negative for yellow fever virus by polymerase chain reaction. There were no samples of breast milk available for testing.Convalescent serum testing four months after admission showed persistence of yellow fever virus IgM, with a drop in the plaque reduction neutralization test titre to 1:320, which was suggestive of recent exposure. Serologic testing for western and eastern equine encephalitis, St. Louis encephalitis, Powassan encephalitis and dengue were negative (National Microbiology Laboratory) along with Mayaro, Venezuelan equine encephalitis and West Nile viruses (Centers for Disease Control and Prevention).     

Lubricin is expressed in chondrocytes derived from osteoarthritic cartilage encapsulated in poly (ethylene glycol) diacrylate scaffold

Osteoarthritis (OA) is characterized by degenerative changes within joints that involved quantitative and/or qualitative alterations of cartilage and synovial fluid lubricin, a mucinous glycoprotein secreted by synovial fibroblasts and chondrocytes. Modern therapeutic methods, including tissue-engineering techniques, have been used to treat mechanical damage of the articular cartilage but to date there is no specific and effective treatment. This study aimed at investigating lubricin immunohistochemical expression in cartilage explant from normal and OA patients and in cartilage constructions formed by Poly (ethylene glycol) (PEG) based hydrogels (PEG-DA) encapsulated OA chondrocytes. The expression levels of lubricin were studied by immunohistochemistry: i) in tissue explanted from OA and normal human cartilage; ii) in chondrocytes encapsulated in hydrogel PEGDA from OA and normal human cartilage. Moreover, immunocytochemical and western blot analysis were performed in monolayer cells from OA and normal cartilage. The results showed an increased expression of lubricin in explanted tissue and in monolayer cells from normal cartilage, and a decreased expression of lubricin in OA cartilage. The chondrocytes from OA cartilage after 5 weeks of culture in hydrogels (PEGDA) showed an increased expression of lubricin compared with the control cartilage. The present study demonstrated that OA chondrocytes encapsulated in PEGDA, grown in the scaffold and were able to restore lubricin biosynthesis. Thus our results suggest the possibility of applying autologous cell transplantation in conjunction with scaffold materials for repairing cartilage lesions in patients with OA to reduce at least the progression of the disease.     

Molecular phylogeny of the subgenus Drosophila (Diptera, Drosophilidae) with an emphasis on Neotropical species and groups: a nuclear versus mitochondrial gene approach

The genus Drosophila has played an essential role in many biological studies during the last 100 years but much controversy and many incompletely addressed issues still remain to be elucidated regarding the phylogeny of this genus. Because information on the Neotropical species contained in the subgenus Drosophila is particularly incomplete, with this taxonomic group being underrepresented in many studies, we designed a study to answer some evolutionary questions related to these species. We subjected at least 41 Drosophilidae taxa to a phylogenetic analysis using a 516-base pair (bp) fragment of the alpha-methyldopa (Amd) nuclear gene and a 672 bp fragment of the mitochondrial cytochrome oxidase subunit II (COII) gene both individually and in combination. We found that the subgenus Drosophila is paraphyletic and subdivided into two main clusters: the first containing species traditionally placed in the virilis-repleta radiation and the second assembling species of the immigrans-Hirtodrosophila radiation. Inside the first of these clusters we could detect the monophyly of both the flavopilosa (the sister-clade of the annulimana group) and the mesophragmatica (closely related to the repleta group) species groups. Concerning the immigrans-Hirtodrosophila lineage, Zaprionus, Liodrosophila, Samoaia, and Hirtodrosophila were the early offshoots, followed by the immigrans, quinaria, testacea, and funebris species groups. The tripunctata radiation appears to be a derived clade, composed of a paraphyletic tripunctata group, intimately interposed with members of the cardini, guarani, and guaramunu species groups. Overall, the COII gene yielded a poor phylogenetic performance when compared to the Amd gene, the evolutionary hypothesis of which agreed with the total evidence tree. This phenomenon can be explained by the fast saturation of transitional substitutions in COII, due to strong biases in both base composition and substitution patterns, as also by its great among-site rate variation heterogeneity.     

Stem CO2 release under illumination: corticular photosynthesis,photorespiration or inhibition of mitochondrial respiration?

In illuminated stems and branches, CO2 release is often reduced. Many light-triggered processes are thought to contribute to this reduction, namely photorespiration, corticular photosynthesis or even an inhibition of mitochondrial respiration. In this study, we investigated these processes with the objective to discriminate their influence to the overall reduction of branch CO2 release in the light. CO2 gas-exchange measurements of young birch (Betula pendula Roth.) branches (< 1.5 cm) performed under photorespiratory (20% O2) and non-photorespiratory (< 2%) conditions revealed that photorespiration does not play a pre-dominant role in carbon exchange. This suppression of photorespiration was attributed to the high CO2 concentrations (C(i)) within the bark tissues (1544 +/- 227 and 618 +/- 43 micromol CO2 mol(-1) in the dark and in the light, respectively). Changes in xylem CO2 were not likely to explain the observed decrease in stem CO2 release as gas-exchange measurements before and after cutting of the branches did not effect CO2 efflux to the atmosphere. Combined fluorescence and gas-exchange measurements provided evidence that the light-dependent reduction in CO2 release can pre-dominantly be attributed to corticular refixation, whereas an inhibition of mitochondrial respiration in the light is unlikely to occur. Corticular photosynthesis was able to refix up to 97% of the CO2 produced by branch respiration, although it rarely led to a positive net photosynthetic rate.