Achernar: Rapid Polarization Variability as Evidence of Photospheric and Circumstellar Activity

We present the results of a high accuracy ($\sigma \approx 0.005$) polarization monitoring of the Be Star Achernar that was carried out between July 7th and November 5th, 2006. Our results indicate that, after a near quiescent phase from 1998 to 2002, Achernar is presently in an active phase and has built a circumstellar disk. We detect variations both in the polarization level and position angle in timescales as short as one hour and as long as several weeks. Detailed modeling of the observed polarization strongly suggests that the short-term variations originate from discrete mass ejection events which produce transient inhomogeneities in the inner disk. Long-term variations, on the other hand, can be explained by the formation of an inner ring following one or several mass ejection events.Comment: 16 pages, 5 figures, Accepted to Ap

Perspectives on Systematic Analyses of Gene Function in Arabidopsis thaliana: New Tools, Topics and Trends

Since the sequencing of the nuclear genome of Arabidopsis thaliana ten years ago, various large-scale analyses of gene function have been performed in this model species. In particular, the availability of collections of lines harbouring random T-DNA or transposon insertions, which include mutants for almost all of the ~27,000 A. thaliana genes, has been crucial for the success of forward and reverse genetic approaches. In the foreseeable future, genome-wide phenotypic data from mutant analyses will become available for Arabidopsis, and will stimulate a flood of novel in-depth gene-function analyses. In this review, we consider the present status of resources and concepts for systematic studies of gene function in A. thaliana. Current perspectives on the utility of loss-of-function and gain-of-function mutants will be discussed in light of the genetic and functional redundancy of many A. thaliana genes

Perineal care and outcomes in a birth center

Objective: to analyse the perineal outcomes in childbirth and post-partum perineal care in a freestanding birth centre. Method: a cross-sectional study, with data collection performed in the women’s birth records forms from Casa Angela, a freestanding birth centre, São Paulo, Brazil, in 2016-2017 (n=415). The following data was analysed: occurrence and perineal tear degree; maternal, neonatal and birth care-related variables; perineal suture prevalence; complications in wound healing and natural methods on perineal care. Data were subjected to descriptive, inferential and multiple analyses. Results: in 11.8% of women, the perineum was kept intact, 61.9% had spontaneous first-degree tear and 26.3% had second-degree tear. The variables related to the occurrence and higher spontaneous degree tears were maternal age and second period of childbirth >2 hours. The protective factors against the occurrence and higher degree tears were number of previous vaginal childbirths and maternal position different from vertical during childbirth. Perineal suture was performed in 16.0% and 70.6% of women with spontaneous first- and second-degree tears, respectively. The main perineal complications after birth were edema (53.6%) and pain (29.4%); and the perineal suture increased the chance for these complications (OR=2.5; 95%CI 1.5-4.3). Perineum icepack compress was used in 53.8% of women during post-partum period. Conclusion: maternal and health-care related factors were associated to the prevalence and degree of spontaneous perineal tear. First-degree spontaneous perineal tears were prevalent and sutured in a low number of women. There were more complications in the wound healing process when the perineal suture was performed, regardless the tear degree. The number of natural methods in post-partum perineal care was higher than the use of medicines

Analysis of 101 nuclear transcriptomes reveals 23 distinct regulons and their relationship to metabolism, chromosomal gene distribution and co-ordination of nuclear and plastid gene expression

Post-endosymbiotic evolution of the proto-chloroplast was characterized by gene transfer to the nucleus. Hence, most chloroplast proteins are nuclear-encoded and the regulation of chloroplast functions includes nuclear transcriptional control. The expression profiles of 3292 nuclear Arabidopsis genes, most of them encoding chloroplast proteins, were determined from 101 different conditions and have been deposited at the GEO database (http://www.ncbi.nlm.nih.gov/geo/) under GSE1160-GSE1260. The 1590 most-regulated genes fell into 23 distinct groups of co-regulated genes (regulons). Genes of some regulons are not evenly distributed among the five Arabidopsis chromosomes and pairs of adjacent, co-expressed genes exist. Except regulons 1 and 2, regulons are heterogeneous and consist of genes coding for proteins with different subcellular locations or contributing to several biochemical functions. This implies that different organelles and/or metabolic pathways are co-ordinated at the nuclear transcriptional level, and a prototype for this is regulon 12 which contains genes with functions in amino acid and carbohydrate metabolism, as well as genes associated with transport or transcription. The co-expression of nuclear genes coding for subunits of the photosystems or encoding proteins involved in the transcription/translation of plastome genes (particularly ribosome polypeptides) (regulons 1 and 2, respectively) implies the existence of a novel mechanism that co-ordinates plastid and nuclear gene expression and involves nuclear control of plastid ribosome abundance. The co-regulation of genes for photosystem and plastid ribosome proteins escapes a previously described general control of nuclear chloroplast proteins imposed by a transcriptional master switch, highlighting a mode of transcriptional regulation of photosynthesis which is different compared to other chloroplast functions. From the evolutionary standpoint, the results provided indicate that functional integration of the proto-chloroplast into the eukaryotic cell was associated with the establishment of different layers of nuclear transcriptional control

A Survey of Chloroplast Protein Kinases and Phosphatases in Arabidopsis thaliana

Protein phosphorylation is a major mode of regulation of metabolism, gene expression and cell architecture. In chloroplasts, reversible phosphorylation of proteins is known to regulate a number of prominent processes, for instance photosynthesis, gene expression and starch metabolism. The complements of the involved chloroplast protein kinases (cpPKs) and phosphatases (cpPPs) are largely unknown, except 6 proteins (4 cpPKs and 2 cpPPs) which have been experimentally identified so far. We employed combinations of programs predicting N-terminal chloroplast transit peptides (cTPs) to identify 45 tentative cpPKs and 21 tentative cpPPs. However, test sets of 9 tentative cpPKs and 13 tentative cpPPs contain only 2 and 7 genuine cpPKs and cpPPs, respectively, based on experimental subcellular localization of their N-termini fused to the reporter protein RFP. Taken together, the set of enzymes known to be involved in the reversible phosphorylation of chloroplast proteins in A. thaliana comprises altogether now 6 cpPKs and 9 cpPPs, the function of which needs to be determined in future by functional genomics approaches. This includes the calcium-regulated PK CIPK13 which we found to be located in the chloroplast, indicating that calcium-dependent signal transduction pathways also operate in this organelle

Genome-wide analyses of light-regulated genes in Aspergillus nidulans reveal a complex interplay between different photoreceptors and novel photoreceptor functions

Fungi sense light of different wavelengths using blue-, green-, and red-light photoreceptors. Blue light sensing requires the “white-collar” proteins with flavin as chromophore, and red light is sensed through phytochrome. Here we analyzed genome-wide gene expression changes caused by short-term, low-light intensity illumination with blue-, red- or far-red light in Aspergillus nidulans and found that more than 1100 genes were differentially regulated. The largest number of up- and downregulated genes depended on the phytochrome FphA and the attached HOG pathway. FphA and the white-collar orthologue LreA fulfill activating but also repressing functions under all light conditions and both appear to have roles in the dark. Additionally, we found about 100 genes, which are red-light induced in the absence of phytochrome, suggesting alternative red-light sensing systems. We also found blue-light induced genes in the absence of the blue-light receptor LreA. We present evidence that cryptochrome may be part of this regulatory cue, but that phytochrome is essential for the response. In addition to in vivo data showing that FphA is involved in blue-light sensing, we performed spectroscopy of purified phytochrome and show that it responds indeed to blue light