Conformation of full-length Bruton tyrosine kinase (Btk) from synchrotron X-ray solution scattering

Brutons's tyrosine kinase (Btk) is a non-receptor protein tyrosine kinase (nrPTK) essential for the development of B lymphocytes in humans and mice. Like Src and Abl PTKs, Btk contains a conserved cassette formed by SH3, SH2 and protein kinase domains, but differs from them by the presence of an N-terminal PH domain and the Tec homology region. The domain structure of Btk was analysed using X-ray synchrotron radiation scattering in solution. Low resolution shapes of the full-length protein and several deletion mutants determined ab initio from the scattering data indicated a linear arrangement of domains. This arrangement was further confirmed by rigid body modelling using known high resolution structures of individual domains. The final model of Btk displays an extended conformation with no, or little, inter-domain interactions. In agreement with these results, deletion of non-catalytic domains failed to enhance the activity of Btk. Taken together, our results indicate that, contrary to Src and Abl, Btk might not require an assembled conformation for the regulation of its activity.     

Immunoglobulin-secreting cells of maternal origin can be detected in B cell-deficient mice

It is well known that the transfer of immunoglobulins (Igs) from mother to young via milk contributes to the offspring's immune defense. The present study suggests that not only is IgG transmitted to progeny, but that functional maternal Ig-secreting cells (or B cells) can also be transferred to the neonate. We have used B cell-deficient (micro(-/-)) mice and found that a high proportion of them obtain long-lasting, partial reconstitution of their serum Ig levels if born to micro(+/-) mothers. In some of these serum IgG-positive micro(-/-) mice, Ig-secreting cells were detected in spleen and bone marrow. To ensure that cells of maternal origin were present in the progeny, micro(-/-) offspring born to micro(+/-) dams transgenic for green fluorescent protein (GFP) were used. In spleens and bone marrow from some of these micro(-/-)GFP(-/-) offspring, GFP-positive cells were detected, which demonstrated that cells of maternal origin could infiltrate the progeny. In addition, splenic Ig-secreting cells were detected in micro(-/-) mice that were born to micro(-/-) dams and transferred to a lactating micro(+/+) foster dam at birth. This indicates that maternal Ig-secreting cells can be transferred postnatally via milk.     

Vascular continuity and auxin signals

Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular tissues usually differentiate at predictable positions but the wide range of functional patterns generated in response to abnormal growth conditions or wounding reveals partially self-organizing patterning mechanisms. Signals ensuring aligned cell differentiation within vascular strands are crucial in self-organized vascular patterning, and the apical-basal flow of indole acetic acid has been suspected to act as an orienting signal in this process. Several recent advances appear to converge on a more precise definition of the role of auxin flow in vascular tissue patterning.     

Arabidopsis ATP A2 peroxidase. Expression and high-resolution structure of a plant peroxidase with implications for lignification

Lignins are phenolic biopolymers synthesized by terrestrial, vascular plants for mechanical support and in response to pathogen attack. Peroxidases have been proposed to catalyse the dehydrogenative polymerization of monolignols into lignins, although no specific isoenzyme has been shown to be involved in lignin biosynthesis. Recently we isolated an extracellular anionic peroxidase, ATP A2, from rapidly lignifying Arabidopsis cell suspension culture and cloned its cDNA. Here we show that the Atp A2 promoter directs GUS reporter gene expression in lignified tissues of transgenic plants. Moreover, an Arabidopsis mutant with increased lignin levels compared to wild type shows increased levels of ATP A2 mRNA and of a mRNA encoding an enzyme upstream in the lignin biosynthetic pathway. The substrate specificity of ATP A2 was analysed by X-ray crystallography and docking of lignin precursors. The structure of ATP A2 was solved to 1.45 Å resolution at 100 K. Docking of p-coumaryl, coniferyl and sinapyl alcohol in the substrate binding site of ATP A2 were analysed on the basis of the crystal structure of a horseradish peroxidase C-CN-ferulic acid complex. The analysis indicates that the precursors p-coumaryl and coniferyl alcohols are preferred by ATP A2, while the oxidation of sinapyl alcohol will be sterically hindered in ATP A2 as well as in all other plant peroxidases due to an overlap with the conserved Pro-139. We suggest ATP A2 is involved in a complex regulation of the covalent cross-linking in the plant cell wall.     

Arabidopsis map kinase 4 negatively regulates systemic acquired resistance

Transposon inactivation of Arabidopsis MAP kinase 4 produced the mpk4 mutant exhibiting constitutive systemic acquired resistance (SAR) including elevated salicylic acid (SA) levels, increased resistance to virulent pathogens, and constitutive pathogenesis-related gene expression shown by Northern and microarray hybridizations. MPK4 kinase activity is required to repress SAR, as an inactive MPK4 form failed to complement mpk4. Analysis of mpk4 expressing the SA hydroxylase NahG and of mpk4/npr1 double mutants indicated that SAR expression in mpk4 is dependent upon elevated SA levels but is independent of NPR1. PDF1.2 and THI2.1 gene induction by jasmonate was blocked in mpk4 expressing NahG, suggesting that MPK4 is required for jasmonic acid-responsive gene expression.     

Expression of estrogen receptor-alpha and -beta mRNA in the brain of Japanese quail embryos

The present study was conducted to investigate the mRNA expression of the two estrogen receptor (ER) subtypes ERalpha and ERbeta in the brain of Japanese quail embryos. We found expression of both ERalpha and ERbeta mRNA in homogenate of whole head from 6-day-old embryos, and in brain homogenate from 9- and 12-day-old embryos using real-time PCR. In 9- and 12-day-old embryos the ERalpha expression was higher in females than in males. We used in situ hybridization to examine the localization of the ERs in sections from male and female brains on day 9 and day 17 of incubation. On day 9, ERbeta mRNA was detected in the developing medial preoptic nucleus (POM), in the medial part of the bed nucleus of the striae terminalis (BSTm), and in the tuberal region of the hypothalamus. ERalpha signal could not be detected in the POM, the BSTm or the tuberal region in 9-day-old embryos. In 17-day-old embryos, ERbeta was highly expressed in the preoptic area, the nucleus Taeniae of the Amygdala (TnA) and the BSTm. Expression of ERalpha mRNA was detected in parts of the preoptic area and in the telencephalic TnA. No ERalpha expression was found in the BSTm, an area known to be sexually dimorphic in adults. The high embryonic expression of ERbeta in brain areas linked to sexual behavior indicates that ERbeta plays a role in sexual differentiation of the Japanese quail brain.     

The sister group relation of parmeliaceae (Lecanorales, Ascomycota)

The family Parmeliaceae (Lecanorales, Ascomycota) is possibly the largest, best known and most thoroughly studied lichen family within its order. Despite this fact the relationship between Parmeliaceae and other groups in Lecanorales is still poorly known. The aim of the present study is to contribute to finding the sister group of Parmeliaceae as an aid in future studies on the phylogeny and character evolution of the group. We do this by sampling all potential relatives to the Parmeliaceae that we have identified, i.e. Gypsoplaca, Japewia, Mycoblastus, Protoparmelia, and Tephromela, a good representation of the major groups within the Parmeliaceae s. lat. and a good representation of other taxa in the core Lecanorales. We use molecular data from two genes, the large subunit of the nuclear ribosomal RNA gene (nrLSU) and the small subunit of the mitochondrial ribosomal RNA gene (mrSSU), and a Bayesian analysis of the combined data. The results show that the closest relatives to Parmeliaceae are the two genera Protoparmelia and Gypsoplaca, which are crustose lichens. Parmeliaceae in our sense is a well supported group, including also the family segregates Alectoriaceae, Hypogymniaceae, Usneaceae and Anziaceae.     

Early Complications Following Oesophagectomy for Cancer in Relation to Long-Term Healthcare Utilisation: A Prospective Population-Based Cohort Study

Background

Little is known about how early postoperative complications after oesophagectomy for cancer influence healthcare utilisation in the long-term. We hypothesised that these complications also increase healthcare utilisation long after the recovery period.

Methods

This was a prospective, nationwide Swedish population-based cohort study of patients who underwent curatively intended oesophagectomy for cancer in 2001-2005 and survived at least 1 year postoperatively (n = 390). Total days of in-hospitalisation, number of hospitalisations and number of visits to the outpatient clinic within 5 years of surgery were analysed using quasi-Poisson models with adjustment for patient, tumour and treatment characteristics and are expressed as incidence rate ratios (IRR) and 95% confidence intervals (CI).

Results

There was an increased in-hospitalisation period 1-5 years after surgery in patients with more than 1 complication (IRR 1.5, 95% CI 1.0-2.4). The IRR for the number of hospitalisations by number of complications was 1.1 (95% CI 0.7-1.6), and 1.2 (95% CI 0.9-1.6) for number of outpatient visits in patients with more than 1 complication. The IRR for in-hospitalisation period 1-5 years following oesophagectomy was 1.8 (95% CI 1.0-3.0) for patients with anastomotic insufficiency and 1.5 (95% CI 0.9-2.5) for patients with cardiovascular or cerebrovascular complications. We found no association with number of hospitalisations (IRR 1.2, 95% CI 0.7-2.0) or number of outpatient visits (IRR 1.3, 95% CI 0.9-1.7) after anastomotic insufficiency, or after cardiovascular or cerebrovascular complications (IRR 1.2, 95% CI 0.7-1.9) and (IRR 1.1, 95% CI 0.8-1.5) respectively.

Conclusion

This study showed an increased total in-hospitalisation period 1-5 years after oesophagectomy for cancer in patients with postoperative complications, particularly following anastomotic insufficiency.     

Neospora caninum emerges from the shadow of Toxoplasma gondii

It is sometimes easy to make the mistake of assuming that everything that holds true for Toxoplasma gondii is also true for its relative Neospora caninum. However, a recurring theme in the recent review by Hemphill et al. is not the similarities but the striking differences between the two parasites.