Tracing the Evolution of the Floral Homeotic B- and C-Function Genes through Genome Synteny

The evolution of the floral homeotic genes has been characterized using phylogenetic and functional studies. It is possible to enhance these studies by comparing gene content and order between species to determine the evolutionary history of the regulatory genes. Here, we use a synteny-based approach to trace the evolution of the floral B- and C-function genes that are required for specification of the reproductive organs. Consistent with previous phylogenetic studies, we show that the euAP3–TM6 split occurred after the monocots and dicots diverged. The Arabidopsis TM6 and papaya euAP3 genes are absent from the respective genomes, and we have detected loci from which these genes were lost. These data indicate that either the TM6 or the euAP3 lineage genes can be lost without detriment to flower development. In contrast, PI is essential for male reproductive organ development; yet, contrary to predictions, complex genomic rearrangements have resulted in almost complete breakdown of synteny at the PI locus. In addition to showing the evolution of B-function genes through the prediction of ancestral loci, similar reconstructions reveal the origins of the C-function AG and PLE lineages in dicots, and show the shared ancestry with the monocot C-function genes. During our studies, we found that transposable elements (TEs) present in sequenced Antirrhinum genomic clones limited comparative studies. A pilot survey of the Antirrhinum data revealed that gene-rich regions contain an unusually high degree of TEs of very varied types, which will be an important consideration for future genome sequencing efforts

Hemorrhagic shock after endoscopic biopsy of sigmoid cancer: pseudoaneurysm of the rectal superior artery

An 86-year-old man without significant comorbidity presented with weight loss, diarrhea, and iron deficiency anemia. No signs of gastrointestinal bleeding were noticed. Colonoscopy was performed, and sigmoid cancer was suspected (a). Biopsies were obtained, which confirmed colonic adenocarcinoma. Eight hours after the endoscopy, the patient developed massive hematochezia, followed by hemodynamic instability (blood pressure 60/30 mm Hg; heart rate 120 bpm; and hemoglobin drop from 9.8 g/dL to 6.1 g/dL within 2 hours). After stabilization with intravenous fluids, norepinephrine, and transfusion of 1 unit of red blood cells, endoscopy was repeated and ruled out ongoing bleeding. A computed tomography scan confirmed a mass of the sigmoid colon, which extended along the inferior mesenteric artery and to the os sacrum. Within the sigmoid wall, extravasation of the contrast medium was seen into a structure of 2.3 × 1.7 cm. Computed tomography reconstructions suspected pseudoaneurysm of the inferior mesenteric artery (Figures B, C). In the absence of distant metastases, surgical resection was attempted urgently. However, owing to infiltration of the aortic wall, curative resection was impossible and colostomy was performed. Angiography confirmed a large pseudoaneurysm of the rectal superior artery, and embolization was performed successfully. The further course was unremarkable

Simple, robust eddy correlation amplifier for aquatic dissolved oxygen and hydrogen sulfide flux measurements

The aquatic application of the eddy correlation (EC) technique is growing more popular and is gradually becoming a standard method for resolving benthic O2 fluxes. By including the effects of the local hydrodynamics, the EC technique provides greater insight into the nature of benthic O2 exchange than traditional methods (i.e., benthic chambers and lander microprofilers). The growing popularity of the EC technique has led to a greater demand for easily accessible and robust EC instrumentation. Currently, the EC instrumentation is limited to two commercially available systems that are still in the development stage. Here, we present a robust, open source EC picoamplifier that is simple in design and can be easily adapted to both new and existing acoustic Doppler velocimeters (ADV). The picoamplifier has a response time of < 0.1 ms and features galvanic isolation that ensures very low noise contamination of the signal. It can be adjusted to accommodate varying ranges of microelectrode sensitivity as well as other types of amperometric microelectrodes. We show that the extracted flux values are not sensitive to reduced microelectrode operational ranges (i.e., lower resolution) and that no signal loss results from using either a 16- or 14-bit analog-to-digital converter. Finally, we demonstrate the capabilities of the picoamplifier with field studies measuring both dissolved O2 and H2S EC fluxes. The picoamplifier presented here consistently acquires high-quality EC data and provides a simple solution for those who wish to obtain EC instrumentation. The schematic of the amplifier’s circuitry is given in the Web Appendix

The Galactic structure and chemical evolution traced by the population of planetary nebulae

We use an extended and homogeneous data set of Galactic planetary nebulae (PNe) to study the metallicity gradients and the Galactic structure and evolution. The most up-to-date abundances, distances (calibrated with Magellanic Cloud PNe) have been employed, together with a novel homogeneous morphological classification, to characterize the different PN populations. We confirm that morphological classes have a strong correlation with PN Peimbert's Type, and also with their distribution on the Galactic landscape. We studied the alpha-element distribution within the Galactic disk, and found that the best selected disk population, together with the most reliable PN distance scale yields to a radial oxygen gradient of d[log(O/H)]/dR=-0.023 +- 0.006 dex/ kpc for the whole disk sample, and of d[log(O/H)]/dR= -0.035+-0.024, -0.023+-0.005, and -0.011+-0.013 dex/kpc respectively for Type I, II, and III PNe. Neon gradients for the same PN types confirm the trend. Accurate statistical analysis show moderately high uncertainties in the slopes, but also confirm the trend of steeper gradient for PNe with more massive progenitors, indicating a possible steepening with time of the Galactic disk metallicity gradient. The PN metallicity gradients presented here are consistent with the local metallicity distribution; furthermore, oxygen gradients determined with young and intermediate age PNe show good consistency with oxygen gradients derived respectively from other young (OB stars, HII regions) and intermediate (open cluster) Galactic populations. We also extend the Galactic metallicity gradient comparison by revisiting the open cluster [Fe/H] data from high resolution spectroscopy. The analysis suggests that they could be compliant with the same general picture of a steepening of gradient with time.Comment: ApJ, in pres

Comparison of ESTs from juvenile and adult phases of the giant unicellular green alga Acetabularia acetabulum

BACKGROUND: Acetabularia acetabulum is a giant unicellular green alga whose size and complex life cycle make it an attractive model for understanding morphogenesis and subcellular compartmentalization. The life cycle of this marine unicell is composed of several developmental phases. Juvenile and adult phases are temporally sequential but physiologically and morphologically distinct. To identify genes specific to juvenile and adult phases, we created two subtracted cDNA libraries, one adult-specific and one juvenile-specific, and analyzed 941 randomly chosen ESTs from them. RESULTS: Clustering analysis suggests virtually no overlap between the two libraries. Preliminary expression data also suggests that we were successful at isolating transcripts differentially expressed between the two developmental phases and that many transcripts are specific to one phase or the other. Comparison of our EST sequences against publicly available sequence databases indicates that ESTs from the adult and the juvenile libraries partition into different functional classes. Three conserved sequence elements were common to several of the ESTs and were also found within the genomic sequence of the carbonic anhydrase1 gene from A. acetabulum. To date, these conserved elements are specific to A. acetabulum. CONCLUSIONS: Our data provide strong evidence that adult and juvenile phases in A. acetabulum vary significantly in gene expression. We discuss their possible roles in cell growth and morphogenesis as well as in phase change. We also discuss the potential role of the conserved elements found within the EST sequences in post-transcriptional regulation, particularly mRNA localization and/or stability

A molecular recombination map of Antirrhinum majus

<p>Abstract</p> <p>Background</p> <p>Genetic recombination maps provide important frameworks for comparative genomics, identifying gene functions, assembling genome sequences and for breeding. The molecular recombination map currently available for the model eudicot <it>Antirrhinum majus </it>is the result of a cross with <it>Antirrhinum molle</it>, limiting its usefulness within <it>A. majus</it>.</p> <p>Results</p> <p>We created a molecular linkage map of <it>A</it>. <it>majus </it>based on segregation of markers in the F2 population of two inbred lab strains of <it>A. majus</it>. The resulting map consisted of over 300 markers in eight linkage groups, which could be aligned with a classical recombination map and the <it>A. majus </it>karyotype. The distribution of recombination frequencies and distorted transmission of parental alleles differed from those of a previous inter-species hybrid. The differences varied in magnitude and direction between chromosomes, suggesting that they had multiple causes. The map, which covered an estimated of 95% of the genome with an average interval of 2 cM, was used to analyze the distribution of a newly discovered family of MITE transposons and tested for its utility in positioning seven mutations that affect aspects of plant size.</p> <p>Conclusions</p> <p>The current map has an estimated interval of 1.28 Mb between markers. It shows a lower level of transmission ratio distortion and a longer length than the previous inter-species map, making it potentially more useful. The molecular recombination map further indicates that the <it>IDLE </it>MITE transposons are distributed throughout the genome and are relatively stable. The map proved effective in mapping classical morphological mutations of <it>A. majus</it>.</p

Negative affective burden is associated with higher resting-state functional connectivity in subjective cognitive decline

Publisher Copyright: © 2022, The Author(s).Subjective cognitive decline (SCD), as expressed by older adults, is associated with negative affect, which, in turn, is a likely risk factor for Alzheimer’s Disease (AD). This study assessed the associations between negative affective burden, cognitive functioning, and functional connectivity in networks vulnerable to AD in the context of SCD. Older participants (60–90 years) with SCD (n = 51) and healthy controls (n = 50) were investigated in a cross-sectional study. Subclinical negative affective burden, quantified through a composite of self-reported negative affective factors, was related to cognitive functioning (self-perceived and objective) and functional connectivity. Seed-to-voxel analyses were carried out in default mode network (DMN) and salience network (SAL) nodes using resting-state functional magnetic resonance imaging. Greater negative affective burden was associated with lower self-perceived cognitive functioning and lower between-network functional connectivity of DMN and SAL nodes in the total sample. In addition, there was a significant moderation of SCD status. Greater negative affective burden related to higher functional connectivity within DMN (posterior cingulate-to-precuneus) and within SAL (anterior cingulate-to-insula) nodes in the SCD group, whereas in controls the inverse association was found. We show that negative affective burden is associated with functional brain alterations in older adults, regardless of SCD status. Specifically in the SCD phenotype, greater negative affective burden relates to higher functional connectivity within brain networks vulnerable to AD. Our findings imply that negative affective burden should be considered a potentially modifiable target for early intervention.Peer reviewe

Evolutionary Dynamics of Floral Homeotic Transcription Factor Protein–Protein Interactions

Protein–protein interactions (PPIs) have widely acknowledged roles in the regulation of development, but few studies have addressed the timing and mechanism of shifting PPIs over evolutionary history. The B-class MADS-box transcription factors, PISTILLATA (PI) and APETALA3 (AP3) are key regulators of floral development. PI-like (PIL) and AP3-like (AP3L) proteins from a number of plants, including Arabidopsis thaliana (Arabidopsis) and the grass Zea mays (maize), bind DNA as obligate heterodimers. However, a PIL protein from the grass relative Joinvillea can bind DNA as a homodimer. To ascertain whether Joinvillea PIL homodimerization is an anomaly or indicative of broader trends, we characterized PIL dimerization across the Poales and uncovered unexpected evolutionary lability. Both obligate B-class heterodimerization and PIL homodimerization have evolved multiple times in the order, by distinct molecular mechanisms. For example, obligate B-class heterodimerization in maize evolved very recently from PIL homodimerization. A single amino acid change, fixed during domestication, is sufficient to toggle one maize PIL protein between homodimerization and obligate heterodimerization. We detected a signature of positive selection acting on residues preferentially clustered in predicted sites of contact between MADS-box monomers and dimers, and in motifs that mediate MADS PPI specificity in Arabidopsis. Changing one positively selected residue can alter PIL dimerization activity. Furthermore, ectopic expression of a Joinvillea PIL homodimer in Arabidopsis can homeotically transform sepals into petals. Our results provide a window into the evolutionary remodeling of PPIs, and show that novel interactions have the potential to alter plant form in a context-dependent manner. Key words: PISTILLATA, Poales, APETALA3, convergent molecular evolution, B-class MADS box genes, evolution of flower development