Apical Axis Research Articles

Entomoneis tenera sp. nov., a new marine planktonic diatom (Entomoneidaceae, Bacillariophyta) from the Adriatic Sea

The genus Entomoneis Ehrenberg includes diatoms with structurally complex frustules having a bilobate keel elevated above the valve surface and numerous girdle bands. We describe here a new member of the genus, Entomoneis tenera sp. nov., a minute species found in the plankton of the south-eastern Adriatic Sea. The description and proposed taxonomic affiliation are based on both morphological observations and molecular analyses obtained from three cultivated strains. The cultures were established from plankton net samples taken during BIOTA (Bio-tracing Adriatic Water Masses) cruise conducted in February–March 2015. In addition to characteristic Entomoneis features such as panduriform cells, often twisted around the apical axis and a raphe with simple endings positioned on the sigmoid keel, morphological characteristics of E. tenera are: (1) very small cells, 16–21 μm long and 5–20 μm wide (2) very lightly silicified, delicate frustules without valve striation discernible in light microscopy, (3) broad lanceolate valves with scalpeliform apices (4) a straight to slightly arcuate junction line. Phylogenetic analyses using SSU, rbcL and psbC supported the position of E. tenera within the Entomoneis genus with a clear separation from the other described species.

Morphometric Asymmetry of Frustule Outlines in the Pennate Diatom Luticola poulickovae (Bacillariophyceae)

Side orientation of cells is usually ambiguous in unicellular organisms, making it impossible to separate components of directional asymmetry (DA) and fluctuating asymmetry (FA). However, frustules of the diatom Luticola poulickovae have biradially symmetric outlines, and their central areas bear ornamentation that is asymmetric across the apical axis. The goal of this study was to explore differentiation of morphometric asymmetry across the apical axis into DA and FA components. Is there detectable DA of the valve outlines of two L. poulickovae strains that may be related to the asymmetric central areas? Given that the life cycle of diatoms involves cell-size diminution, and cell shape is strongly affected by allometry, we also explored the question of whether asymmetry is correlated with cell size. The extent of symmetric variation among individuals in each strain, as well as DA and FA across the apical axis, were quantified using two Procrustes ANOVA models. The results revealed no correlation of either total asymmetry or FA with valve size. DA was significant and considerably more pronounced than FA in both strains, indicating that there is previously unknown systematic asymmetry of valve outlines of L. poulickovae, which may be related to the asymmetry of its central area.

Gomphonema shanghaiensis sp. nov., a new diatom species (Bacillariophyta) from a river in Shanghai, China

This paper describes the new species Gomphonema shanghaiensis sp. nov. from Shujiawan River, Shanghai City, in the lower reaches of Yangtze River, China. The description is based on data derived from light and scanning electron microscopy. Valves of Gomphonema shanghaiensis are narrowly lanceolate to rhombic-lanceolate, slightly asymmetrical to the apical axis, with a gibbous central region. The footpole is broadly rounded and the headpole is slightly rostrate to narrowly rounded. The axial area is narrow and linear. Central area is small, and irregularly rectangular in shape. 1–5 rounded external stigmal openings are evident, and internally 1–2 of these are positioned on the central nodule. Striae are slightly radiate at the center, radiate towards the poles. The new species was compared with G. hasta, G. archaevibrio, G. spiculoides, G. stagnorum, G. guaraniarum, G. tumens and G. disgracile, all of which resemble Gomphonema shanghaiensis but differ from the new species in specific details of size, striae density, valve shape and stigmal openings number. This species occurs in relatively clean water in Shanghai.

F5-peptide induces aspermatogenesis by disrupting organization of actin- and microtubule-based cytoskeletons in the testis.

During the release of sperm at spermiation, a biologically active F5-peptide, which can disrupt the Sertoli cell tight junction (TJ) permeability barrier, is produced at the site of the degenerating apical ES (ectoplasmic specialization). This peptide coordinates the events of spermiation and blood-testis barrier (BTB) remodeling at stage VIII of the epithelial cycle, creating a local apical ES-BTB axis to coordinate cellular events across the epithelium. The mechanism(s) by which F5-peptide perturbs BTB restructuring, and its involvement in apical ES dynamics remain unknown. F5-peptide, besides perturbing BTB integrity, was shown to induce germ cell release from the epithelium following its efficient in vivo overexpression in the testis. Overexpression of F5-peptide caused disorganization of actin- and microtubule (MT)-based cytoskeletons, mediated by altering the spatiotemporal expression of actin binding/regulatory proteins in the seminiferous epithelium. F5-peptide perturbed the ability of actin microfilaments and/or MTs from converting between their bundled and unbundled/defragmented configuration, thereby perturbing adhesion between spermatids and Sertoli cells. Since apical ES and basal ES/BTB are interconnected through the underlying cytoskeletal networks, this thus provides an efficient and novel mechanism to coordinate different cellular events across the epithelium during spermatogenesis through changes in the organization of actin microfilaments and MTs. These findings also illustrate the potential of F5-peptide being a male contraceptive peptide for men.

OS 23-06 CAN LEFT VENTRICULAR TORSIONAL MECHANICS USING SPECKLE TRACKING ECHOCARDIOGRAPHY IN PREGNANCY TO PREDICT THE NEW ONSET HEART FAILURE?

Objective: Normal pregnancy is associated with reversible changes in both systolic and diastolic mechanics, consistent with an increase in preload and decrease in afterload and systemic vascular resistance. The aim is to evaluate left ventricular (LV) twist and untwist mechanics in a population of pregnant women during differing stages of a healthy pregnancy. Design and Method: We included 22 pregnant patients, 10 with multiple pregnancy (mean age 36.5 ± 3 years) and 20 healthy non pregnant women (mean age 33 ± 4years). Apical and basal short axis for 2D images were acquired (frame rate 65 ± 7 frames/s) and images will be obtained during the first, second, and third trimester, as well as up to two months postpartum. Results: Peak LV twist and untwisting rate increased significantly in the 3rd trimester of normal pregnancy (13.48 ± 2.90°, 13.12 ± 3.30°, 16.83 ± 3.61°, P < 0.001; and −111.52 ± 23.54°/sec, −107.40 ± 26.58°/sec, −144.30 ± 45.14°/sec, P < 0.001; in the 1st, 2nd, and 3rd trimester, respectively). The pregnants with twins have the higher value for LVT and LVUR compare p < 0.01), but in the last trimester, the time to peak LVUR is prolonged. An independent association was found between the change in LV twist and LV end-systolic volume between the 1st and 3rd trimester. Peak untwisting rate at the 3rd trimester correlated significantly with peak twist and LV end-diastolic volume. Multiple regression analysis indicates that only systolic blood pressure (r = 0.394, P = 0.005) was an independent predictor for increased LV torsion. Conclusions: LV twist and peak untwisting rate increase in the 3rd trimester and correlate with end-systolic and end-diastolic volume, respectively. Blood pressure and condition of multiple pregnancy are independently associated with increased torsion during pregnancy and may predict the new onset heart failure and perinatal cardiomyopathy.

Phylogeny, ecology, morphological evolution, and reclassification of the diatom orders Surirellales and Rhopalodiales

The Surirellales and Rhopalodiales are large, widespread, and morphologically diverse groups of raphid pennate diatoms (Bacillariphyta) whose raphe, a structure that facilitates active motility, opens internally into a siliceous canal. We collected 202 representatives of the lineage and sequenced genes from the nuclear, plastid, and mitochondrial genomes to infer phylogenetic relationships as a basis for comparative study of ecology and morphological evolution as well as reclassification. The lineage was ancestrally marine, and we report the first evidence for a ‘stepping stone’ model of marine–freshwater transitions in which freshwater invasions were preceded by adaptation to intermediate brackish habitats. Phylogenetic comparative analyses also showed that the shift from an apical (e.g., Entomoneis) to transapical major axis of development (e.g., Surirella) did not have to proceed through subcircular intermediate forms (i.e., Campylodiscus). Rather, subcircular forms evolved both within lineages with longer apical axis or longer transapical axis. We also used the inferred phylogeny as a basis for genus-level reclassification of the lineage. Campylodiscus now includes the fastuosoid members of Surirella and Campylodiscus, but excludes other marine Campylodiscus which are now classified as Coronia. Surirella includes the Surirella striatula clade, Surirella Pinnatae group, and species formerly classified as Cymatopleura. We resurrected the genus Iconella to accommodate Stenopterobia and the robustoid members of Surirella and Campylodiscus. We broadened Epithemia to include members of the paraphyletic genus Rhopalodia. Finally, we discuss the challenges of constructing a classification that best leverages available phylogenetic data, while minimizing disruption to the research community and recognizing practical considerations stemming from the slow rate of progress on systematic studies of understudied organisms.

Cenozoic silicoflagellate skeletal morphology: a review and suggested terminology

Silicoflagellate skeletons are made up of siliceous components that interconnect through triple-junctions to form a basket-shaped design made of basal and apical structures. The skeletal framework has a domal shape that can be paired with another to form a double skeleton. For Cenozoic skeletal morphologies, the basal structure consists of a ring of polygonal shape that often includes spines at the basal corners that are directed radially away from the double-skeleton central point, and pikes that point towards the apical axis. The apical structure is made up of elements of less thickness that are connected to the basal ring by struts. The skeletal components of the silicoflagellate conform to a consistently applied set of rules. There is a need to standardize silicoflagellate descriptive terminology in light of recent studies and detailed examination of the elements, spines and pikes that comprise Cenozoic skeletons. Here we review established and recently defined terminology that relates to silicoflagellate skeletons and suggest terminology to standardize future descriptive work.

LO092: The educational impact of a formalized RUSH (Rapid Ultrasound in Shock) protocol in emergency medicine residency ultrasound training

Introduction: Point of care ultrasound for assessment of undifferentiated hypotension and shock is part of the clinical scope of Emergency Physicians in Canada. The RUSH Exam outlines a systematic approach to these patients. A RUSH Exam educational model using didactic and hands on practice was developed and implemented for Emergency Medicine (EM) residents. This study evaluated the effectiveness of the module in a simulated setting on the following endpoints: improvement in image acquisition, interpretation, speed, and subjective comfort level, among EM residents with basic ultrasound training. Methods: Approval was received from the institutional health research ethics board for this before and after simulation study. Residents in the -EM Program or CCFP-EM Program from July 2014 to July 2015 were eligible to consent. Participants were excluded if they were unable to complete all portions. All residents were educated to the same level of introductory ultrasound training based on the curriculum in place at our institution. The 8-hour intervention included RUSH didactic and hands on small group sessions. Testing before and after the intervention was performed with the SonoSim Livescan training platform. Two evaluators scored each resident on the accuracy of image acquisition, image interpretation, and time to scan completion. A before and after survey assessed resident comfort level with performing ultrasound on an emergency patient in shock, and basing decisions on ultrasound findings. Statistical analysis was performed using McNemar’s test for image acquisition and interpretation, a paired T test for time, and the Bahpkar test for the questionnaire. Results: 16 EM residents including 11 senior residents and 5 junior residents were enrolled. Improvement was achieved in the categories of IVC image acquisition and interpretation, as well as interpretation for B-lines, lung sliding, cardiac apical and parasternal long axis, and DVT (p&lt;0.05). Subjective comfort level of performing ultrasound in shock and basing decisions on the findings was increased (p&lt;0.0001). Among junior residents, there was an increased speed of image acquisition. Conclusion: With the introduction of the RUSH Exam educational module, EM residents showed improved image acquisition, image interpretation, speed, and comfort level when using ultrasound in critically ill patients.

13 MACE rate following normal regadenoson stress perfusion cardiovascular magnetic resonance: A single centre experience

Stress perfusion cardiovascular magnetic resonance (SPCMR) is now established in the investigation of myocardial ischaemia. Various pharmacological options exist for inducing stress conditions. Regadenoson is an A-2A agonist with many advantages over Adenosine, including easier administration and fewer side effects. Whilst the use of Regadenoson has been studied in nuclear myocardial perfusion imaging (MPI), its efficacy has not been as robustly documented in SPCMR. Our centre has a large nuclear MPI service, with a smaller but rapidly growing stress perfusion CMR service. The aim of this study was to determine the major adverse cardiac event (MACE) rate following a normal Regadenoson SPCMR examination. A retrospective RIS (Radiology Information System) search was performed over a 2 year period (2013 – 2014) which yielded 156 SPCMR studies. 95 were excluded due to alternative/undocumented pharmacological stress agents, positive results for inducible ischaemia or failure to complete stress perfusion sequences. This yielded a total cohort of 61 patients who had a normal Regadenoson SPCMR study (this included well documented artefacts such as dark-rim). Basal, mid and apical short axis views were obtained during first pass of contrast (Gadovist, 0.2mg/kg, 6ml/second) at peak stress (400 micrograms Regadenoson). Rest perfusion was repeated 15 min after the initial contrast injection. All patients were scanned on a Siemens 1.5T Avanto MRI scanner. All patients were followed up for at least 1 year for MACE, i.e. cardiovascular death, myocardial infarction or coronary revascularisation. Out of 61 patients who had a normal Regadenoson SPCMR study, 1 patient experienced MACE within the follow up period (intra-operative death during cardiac transplantation). Excluding this, no patients suffered adverse events during the follow up period. In conclusion, a normal Regadenoson stress perfusion CMR examination is associated with a very low MACE rate within 2 years.

Sex-related Left Ventricle Rotational and Torsional Mechanics by Block Matching Algorithm.

Background:The aim of the present study was to evaluate how left ventricular twist and torsion are associated with sex between sex groups of the same age. Materials and Methods: In this analytical study, twenty one healthy subjects were scanned in left ventricle basal and apical short axis views to run the block matching algorithm; instantaneous changes in the base and apex rotation angels were estimated by this algorithm and then instantaneous changes of the twist and torsion were calculated over the cardiac cycle. Results:The rotation amount between the consecutive frames in basal and apical levels was extracted from short axis views by tracking the speckle pattern of images. The maximum basal rotation angle for men and women were -6.94°±1.84 and 9.85°±2.36 degrees (p-value = 0.054), respectively. Apex maximum rotation for men was -8.89°±2.04 and for women was 12.18°±2.33 (p-value < 0.05). The peak of twist angle for men and women was 16.78 ± 1.83 and 20.95± 2.09 degrees (p-value < 0.05), respectively. In men and women groups, the peak of calculated torsion angle was 5.49°±1.04 and 7.12± 1.38 degrees (p-value < 0.05), respectively. Conclusion:The conclusion is that although torsion is an efficient parameter for left ventricle function assessment, because it can take in account the heart diameter and length, statistic evaluation of the results shows that among men and women LV mechanical parameters are significantly different. This study was mainly ascribed to the dependency of the torsion and twist on patient sex.

Clinical assessment of intraventricular blood transport in patients undergoing cardiac resynchronization therapy.

In the healthy heart, left ventricular (LV) filling generates different flow patterns which have been proposed to optimize blood transport by coupling diastole and systole. This work presents a novel image-based method to assess how different flow patterns influence LV blood transport in patients undergoing cardiac resynchronization therapy (CRT). Our approach is based on solving the advection equation for a passive scalar field from time-resolved blood velocity fields. Imposing time-varying inflow boundary conditions for the scalar field provides a straightforward method to distinctly track the transport of blood entering the LV in the different filling waves of a given cardiac cycle, as well as the transport barriers which couple filling and ejection. We applied this method to analyze flow transport in a group of patients with implanted CRT devices and a group of healthy volunteers. Velocity fields were obtained using echocardiographic color Doppler velocimetry, which provides two-dimensional time-resolved flow maps in the apical long axis three-chamber view of the LV. In the patients under CRT, the device programming was varied to analyze flow transport under different values of the atrioventricular conduction delay, and to model tachycardia (100 bpm). Using this method, we show how CRT influences the transit of blood inside the left ventricle, contributes to conserving kinetic energy, and favors the generation of hemodynamic forces that accelerate blood in the direction of the LV outflow tract. These novel aspects of ventricular function are clinically accessible by quantitative analysis of color-Doppler echocardiograms.

Myocardial Rotation and Torsion in Child Growth.

BackgroundThe speckle tracking echocardiography can benefit to assess the regional myocardial deformations. Although, previous reports suggested no significant change in left ventricular (LV) torsion with aging, there are certain differences in LV rotation at the base and apex. The purpose of this study was to evaluate the change and relationship of LV rotation for torsion with aging in children.MethodsForty healthy children were recruited and divided into two groups of twenty based on whether the children were preschool-age (2–6 years of age) or school-age (7–12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotation were assessed with speckle tracking echocardiography. LV rotation in the basal and apical short axis planes was determined using six myocardial segments along the central axis.ResultsApical and basal LV rotation did not show the statistical difference with increased age between preschool- and school-age children. Apical radial strain showed significant higher values in preschool-age children, especially at the anterior (52.8 ± 17.4% vs. 34.7 ± 23.2%, p < 0.02), lateral (55.8 ± 20.4% vs. 36.1 ± 22.7%, p < 0.02), and posterior segments (57.1 ± 17.6% vs. 38.5 ± 21.7%, p < 0.01). The torsion values did not demonstrate the statistical difference between two groups.ConclusionThis study revealed the tendency of higher rotation values in preschool-age children than in school-age children. The lesser values of rotation and torsion with increased age during childhood warrant further investigation.

Differential regulation of meristem size, morphology and organization by the ERECTA, CLAVATA and class III HD-ZIP pathways.

ABSTRACTThe shoot apical meristem (SAM) of angiosperm plants is a small, highly organized structure that gives rise to all above-ground organs. The SAM is divided into three functional domains: the central zone (CZ) at the SAM tip harbors the self-renewing pluripotent stem cells and the organizing center, providing daughter cells that are continuously displaced into the interior rib zone (RZ) or the surrounding peripheral zone (PZ), from which organ primordia are initiated. Despite the constant flow of cells from the CZ into the RZ or PZ, and cell recruitment for primordium formation, a stable balance is maintained between the distinct cell populations in the SAM. Here we combined an in-depth phenotypic analysis with a comparative RNA-Seq approach to characterize meristems from selected combinations of clavata3 (clv3), jabba-1D (jba-1D) and erecta (er) mutants of Arabidopsis thaliana. We demonstrate that CLV3 restricts meristem expansion along the apical-basal axis, whereas class III HD-ZIP and ER pathways restrict meristem expansion laterally, but in distinct and possibly perpendicular orientations. Our k-means analysis reveals that clv3, jba-1D/+ and er lead to meristem enlargement by affecting different aspects of meristem function; for example, clv3 displays an increase in the stem cell population, whereas jba-1D/+ er exhibits an increase in mitotic activity and in the meristematic cell population. Our analyses demonstrate that a combined genetic and mRNA-Seq comparative approach provides a precise and sensitive method to identify cell type-specific transcriptomes in a small structure, such as the SAM.

Determination of strain pattern in patients with cardiac amyloidosis secondary to Multiple myeloma: a feature tracking study

Methods Comprehensive strain analysis was performed in 46 patients with multiple myeloma with suspected cardiac amyloidosis. MRI strain by feature tracking was measured using 2D cardiac performance analysis MR software (Tomtec, Germany). Global longitudinal strain (GLS) was obtained obtained from averaging longitudinal strains of apical 4-, 2and 3-chamber views. Global circumferential strain (GCS) was obtained from averaging circumferential strains of the basal, mid and apical short axis views. Endocardial and epicardial contours were analyzed separately. Right ventricular GLS was derived from apical 4 chamber view, only endocardial contour was analyzed.

Abstract 15755: Adverse Cardiac Remodeling in Obese Children

Background: Obesity (OB) and hypertension (HTN) are risk factors for early cardiovascular disease (CVD). The aim of this study was to determine the effect of OB and HTN on myocardial mechanics in children using speckle-tracking echocardiography (STE). Methods: Echocardiograms (echo) and ambulatory blood pressure monitors were performed in children referred for HTN from 2009 to 2014. Traditional echo Doppler indices, mass and volume parameters, 24-hr systolic blood pressures (24SBP) and 24-hr diastolic BP indices were obtained. Post-processing was performed on the 2D gray scale images of LV in apical 4-chamber and parasternal short axis mid-papillary views to obtain strain indices (Image Arena, Tomtec). Associations of obesity and BP to the myocardial indices were explored independently using Spearman correlation coefficient. Results: Among 107 patients, 6 - 21 yrs age, 79.4% were males; 42% OB and 53% were hypertensive. Mean Z scores for BMI were 1.5 ± 1.1 and SBP were 1.5 ± 1.2. Mean LV mass (LVM, 2D area-length) was 131 + 42.8 gms, LVMI 2.7 was 40.7 + 9.6 gms, LVM/volume ratio was 0.94 + 0.17. Mean mitral septal E/e’ was 8.3 + 2.1, lateral E/e’ was 5.9 + 1.5 and mitral E/A ratio was 1.8 + 0.4. The mean global longitudinal strain (GLS) was – 17.7 + 3.6, global circumferential strain (GCS) was -20.4 + 3.8, average radial strain (ARS) was 22 + 11.9, average longitudinal strain rate (ALSR) was -1.0 + 0.35 and average circumferential strain rate (ACSR) was -1.5 + 0.5 for all patients. BMI Z scores positively correlated with LVM (r=0.38, p&lt;0.01), LVM/vol (r=0.32, p&lt;0.01), mitral E/e’ (r=0.28, p&lt;0.01), LVMI 2.7 (r=0.5, &lt;0.01). Increased BMI negatively correlated to GLS, GCS and ACSR (r=0.3, p&lt;0.01). Higher SBP, diastolic and mean BP were associated with higher mitral medial E/e’ (r=0.3, p&lt;0.01), however did not have statistically significant correlations to strain indices. Conclusions: Obesity causes adverse cardiac remodeling in obese children. This may provide insights into mechanisms of long-term CV effects of obesity. Myocardial effects of HTN were not apparent, possibly due to heterogeneity of the study group and low power.

Proksimal ve Distal Femur Morfolojisinin Osteometrik Değerleri

Purpose: The current study was undertaken to determine the surgically relevant parameters of proximal and distal femur from right and left femora in our population. Methods: These measurements were taken from 400 adult femora (200 right, 200 left) from Department of Anatomy laboratory of Cukurova University, Faculty of Medicine using an electronic digital caliper and goniometer. The mean values of the neck of the length (NL), maximum femoral length (FL), the length of femoral shaft (FSL), intertrochanteric apical axis length (ITAAL), maximum vertical diameter of the femoral head (VDH), neck shaft angle (NSA), superiorinferior femoral neck diameter (SID) and intercondylar notch witch (ICNW) were taken. Results: The mean values of these measurements were found to be 22.2 ± 3.0 mm, 429.5 ± 35.0 mm, 306.5 ± 26.7 mm, 61.9 ± 5.7 mm, 44.2 ± 3.8 mm, 121.10 ± 4.00 , 30.8 ± 3.1 and 2.4 ± 0.2 cm in the right side respectively. However, in the left side same dimensions were 22.5 ± 4.4 mm, 431.3 ±26.2 mm, 299.5 ± 59.4 mm, 61.4 ± 5.1 mm, 44.2 ± 3.3 mm, 121.2 ± 4.0 0 , 30.0 ± 2.9 and 2.3 ± 0.2 cm respectively. Conclusion: The observations presented in the report have defined anatomic parameters that need to be taken into consideration when surgical procedures are performed in hip and knee area for this population.

PH homeostasis during coral calcification in a free ocean CO2 enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef

Geochemical analyses (δ(11)B and Sr/Ca) are reported for the coral Porites cylindrica grown within a free ocean carbon enrichment (FOCE) experiment, conducted on the Heron Island reef flat (Great Barrier Reef) for a 6-mo period from June to early December 2010. The FOCE experiment was designed to simulate the effects of CO2-driven acidification predicted to occur by the end of this century (scenario RCP4.5) while simultaneously maintaining the exposure of corals to natural variations in their environment under in situ conditions. Analyses of skeletal growth (measured from extension rates and skeletal density) showed no systematic differences between low-pH FOCE treatments (ΔpH = ∼-0.05 to -0.25 units below ambient) and present day controls (ΔpH = 0) for calcification rates or the pH of the calcifying fluid (pHcf); the latter was derived from boron isotopic compositions (δ(11)B) of the coral skeleton. Furthermore, individual nubbins exhibited near constant δ(11)B compositions along their primary apical growth axes (±0.02 pHcf units) regardless of the season or treatment. Thus, under the highly dynamic conditions of the Heron Island reef flat, P. cylindrica up-regulated the pH of its calcifying fluid (pHcf ∼8.4-8.6), with each nubbin having near-constant pHcf values independent of the large natural seasonal fluctuations of the reef flat waters (pH ∼7.7 to ∼8.3) or the superimposed FOCE treatments. This newly discovered phenomenon of pH homeostasis during calcification indicates that coral living in highly dynamic environments exert strong physiological controls on the carbonate chemistry of their calcifying fluid, implying a high degree of resilience to ocean acidification within the investigated ranges.

Kurtkrammeria, a new genus of freshwater diatoms (Bacillariophyta, Cymbellaceae) separated from Encyonopsis

The new genus Kurtkrammeria is erected to include 13 species assigned to Encyonopsis that have (1) slit-like or crescent-shaped areolae aligned lengthwise along the apical axis, (2) striae convergent at the apices, and (3) internal proximal raphe ends hooked strongly towards the dorsal side of the valve. Some species of Kurtkrammeria also have dorsal stigmata, apical pore fields and internal anastomosing costae at both poles, and lateral papilla-like projections from intercostae into internal areola openings. Species of Kurtkrammeria are reported infrequently from fossil deposits and from recent diatom assemblages. Kurtkrammeria is a genus of remote and undeveloped regions from the Arctic to the Tropics, in both the Old World and New World. Most species are local or regional endemics and only four species - K. aequalis, K. neoamphioxys, K. recta, and K. subspicula - appear to be widely distributed. Kurtkrammeria species consistently occur in oligotrophic or dystrophic waters with very low specific conductance and circumneutral pH. An extant population of the very rare Kurtkrammeria stodderi is described from Montana, USA. Living cells of K. stodderi were observed to be motile and to have plastids similar to those of Encyonema species. Examination under SEM reveals that K. stodderi also has apical pore fields at both poles.

4D flow MRI and T1 -Mapping: Assessment of altered cardiac hemodynamics and extracellular volume fraction in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is associated with altered hemodynamics in the left ventricular outflow tract (LVOT) and myocardial tissue abnormalities such as fibrosis. The aim of this study was to quantify changes in LVOT 3D hemodynamics and myocardial extracellular volume fraction (ECV, measure of fibrosis) and to investigate relationships between elevated flow metrics and left ventricular (LV) tissue abnormalities. Cardiac magnetic resonance imaging (MRI) including 4D flow (field strength = 1.5T, resolution = 2.1-4.0 × 2.1-4.0 × 2.5-3.2 mm(3) ; venc = 150-250 cm/s; TE/TR/FA = 2.2-2.5msec/4.6-4.9msec/15°) for the in vivo assessment of 3D blood flow velocities with full coverage of the LVOT was applied in 35 patients with HCM (54 ± 15 years) and 10 age-matched healthy controls (45 ± 14 years). In addition, pre- and postcontrast myocardial T1 -mapping (resolution = 2.3 × 1.8 mm, slice thickness = 8 mm, TE/TR-FA = 1.0-1.1msec/2.0-2.2msec/35°) of the LV (basal, mid-ventricular, apical short axis) was performed in a subgroup of 23 HCM patients. Analysis included the segmentation of the LVOT and quantification of peak systolic LVOT pressure gradients and rate of viscous energy loss EL ' as well as left ventricular ECV. HCM patients demonstrated significantly elevated peak systolic LVOT pressure gradients (21 ± 16 mmHg vs. 9 ± 2 mmHg) and energy loss EL ' (3.8 ± 2.5 mW vs. 1.5 ± 0.7 mW, P < 0.005) compared to controls. There was a significant relationship between increased LV fibrosis (ECV) with both elevated pressure gradients (R(2) = 0.44, P < 0.001) and energy loss EL ' (R(2) = 0.46, P < 0.001). The integration of 4D-flow and T1 -mapping-MRI allowed for the evaluation of tissue and flow abnormalities in HCM patients. Our findings suggest a mechanistic link between abnormal LVOT flow, increased LV loading, and adverse myocardial remodeling in HCM.

On the geographical distribution and ecology of Pseudostaurosira cataractarum (Bacillariophyceae): new findings in the Palearctic and Neotropic ecozones

The aim of this paper is to expand the current knowledge on the distribution, ecology and morphology of Pseudostaurosira cataractarum (Hustedt) C.E. Wetzel, E. Morales et Ector. We analysed several freshwater diatom assemblages within the Palearctic (Czech Republic, Europe) and Neotropic ecozones (Argentina and Bolivia, South America). In all localities, small araphids were the dominant or co-dominant group. Inside this group, P. cataractarum was only dominant in the samples from Argentina and Czech Republic, while the Bolivian samples had only a few individuals. RDA and PCA analyses show that the relative abundance of P. cataractarum was positively correlated with water conductivity. The following measurements resulted from the morphometric analysis, apical axis: 2.8–8.2 µm, transapical axis: 2.7–7.2 µm and stria density: 15–29 in 10 µm. In conclusion, the present is the first report of P. cataractarum for continental Europe (from fossil material) and the Neotropic ecozone (from extant populations). Besides having a preference for subaerial habitats, this taxon could be locally conditioned by water conductivity, although in each of the analysed samples this species was associated with cosmopolitan diatoms that are tolerant to a wide range of environmental conditions. Based on the morphometric analyses in studied populations, we propose that the size range for the apical and transapical axes of P. cataractarum should be expanded at the lower end of the range. Likewise, the range of stria density should be expanded since it is wider than that presented for the type population from Indonesia (Java). Consequently, an emended description is presented based on our study and on published data on type and fossil populations.