The cyanobacterium Prochlorococcus has divergent light-harvesting antennae and may have evolved in a low-oxygen ocean

Marine picocyanobacteria of the genus Prochlorococcus are the most abundant photosynthetic organisms in the modern ocean, where they exert a profound influence on elemental cycling and energy flow. The use of transmembrane chlorophyll complexes instead of phycobilisomes as light-harvesting antennae is considered a defining attribute of Prochlorococcus. Its ecology and evolution are understood in terms of light, temperature, and nutrients. Here, we report single-cell genomic information on previously uncharacterized phylogenetic lineages of this genus from nutrient-rich anoxic waters of the eastern tropical North and South Pacific Ocean. The most basal lineages exhibit optical and genotypic properties of phycobilisome-containing cyanobacteria, indicating that the characteristic light-harvesting antenna of the group is not an ancestral attribute. Additionally, we found that all the indigenous lineages analyzed encode genes for pigment biosynthesis under oxygen-limited conditions, a trait shared with other freshwater and coastal marine cyanobacteria. Our findings thus suggest that Prochlorococcus diverged from other cyanobacteria under low-oxygen conditions before transitioning from phycobilisomes to transmembrane chlorophyll complexes and may have contributed to the oxidation of the ancient ocean.

The free-living, planktonic, unicellular cyanobacterium of the genus Prochlorococcus is the smallest and most abundant photosynthetic organism on Earth (1). Together with their closest phylogenetic relatives of the genus Synechococcus, they are collectively known as the marine picocyanobacteria (≤2 μm in cell diameter) and are significant contributors to primary production in the modern ocean (2). Distinguishing characteristics of Prochlorococcus, vis-a-vis other marine cyanobacteria, include an extremely small size (<1 μm in diameter) and the possession of transmembrane divinyl chlorophyll a and b complexes as their main photosynthetic light-harvesting antennae instead of the membrane-bound phycobilisomes that are present in most other cyanobacteria (1, 3). These features are readily discernible with flow cytometry and are widely utilized to selectively quantify Prochlorococcus in marine samples (1). The coding potential and diversity of Prochlorococcus have been studied in numerous phylogenetically distinct isolates and hundreds of single-cell–amplified genomes (SAGs) (4). Based on their physiology, genetic characteristics, and environmental niches, the genus is broadly divided into high-light (HL) and low-light (LL) adapted ecotypes (5). The current understanding is that light, temperature, and nutrients—including iron—play integral roles in the ecology and evolution of Prochlorococcus (6–10).Prochlorococcus thrives in and is best known from sunlit and well-oxygenated, nutrient-poor, tropical and subtropical waters. However, Prochlorococcus is also the dominant photoautotroph in the nutrient-rich, oxygen-depleted waters of major anoxic marine zones (AMZs) in the Arabian Sea and the eastern tropical North (ETNP) and South Pacific (ETSP) (11, 12), where photosynthetic eukaryotes are not found. In these systems, Prochlorococcus can drive a cryptic oxygen cycle (13), by which aerobic metabolic processes can exist under apparent anoxic conditions due to the oxygen produced through oxygenic photosynthesis. Phylogenetic analysis of environmental sequences of the 16S to 23S ribosomal RNA (rRNA) internal transcribed spacer (ITS) region has revealed that the majority of the AMZ Prochlorococcus belong to two distinct phylogenetic lineages, originally termed LL V and LL VI (12) and renamed here as AMZ I and AMZ II. These lineages correspond to uncultured basal groups within the Prochlorococcus genus, for which there is no public genetic information except for their inferred capacity for nitrate utilization based on limited shotgun metagenomic sequencing data (14). Thus, further details on their coding potential and evidence for anaerobic or microaerobic metabolisms remain unconstrained for these AMZ lineages. Such information is important for understanding the origin and structure of the photosynthetic apparatus (15, 16), the evolution of marine pelagic picocyanobacteria (17), the functioning of ancient and modern AMZs (18), and the differential modes of metabolic coupling between Prochlorococcus and other AMZ microorganisms.     

Bisphenol a induces both transient and permanent histofunctional alterations of the hypothalamic-pituitary-gonadal axis in prenatally exposed male rats

Exposure to bisphenol A (BPA) in utero has been shown to induce alterations in the prostate of 30-d-old Wistar rats. Herein, we examine both the time course of BPA action on the rat prostate and the effects of BPA on the male hypothalamic-pituitary-gonadal axis. This was achieved by exposing rats to BPA in utero, followed by immunohistochemistry and morphometric analysis of prostatic tissue, evaluation of estrogen receptor-alpha (ERalpha) and ERbeta mRNA expression in both the preoptic area (POA) and medial basal hypothalamus, and determination of PRL, LH, and testosterone serum levels. On d 30 (peripubertal period), the prostatic periductal stroma of BPA-exposed rats demonstrated a significantly larger layer of fibroblasts than that of controls, whereas on d 120 (adulthood) no significant differences were observed. Moreover, BPA-exposed rats on d 15 exhibited an increase in stromal cellular proliferation compared with controls. Decreased expression of both androgen receptor in prostatic stromal cells and prostatic acid phosphatase in epithelial cells was observed only on d 30 in BPA-exposed males. BPA did not alter POA ERalpha mRNA expression, whereas a 4-fold increase in POA ERbeta mRNA expression was observed on both d 30 and 120. No alterations were observed in either ERalpha or ERbeta expression in the medial basal hypothalamus. BPA-exposed males exhibited increased PRL levels only on d 30, whereas a transient increase in serum testosterone levels was observed on d 15. These results support the hypothesis that prenatal exposure to environmental doses of BPA induces both transient and permanent age-dependent alterations in the male reproductive axis at different levels.     

Orthostatic Hypotension in Parkinson Disease: How Much You Fall or How Low You Go?

Orthostatic hypotension (OH) is frequent in patients with Parkinson's disease (PD) and can occur with or without symptoms. Pharmacological treatments are effective, but often exacerbate supine hypertension. Guidelines exist for the diagnosis, but not for the treatment of OH. We examined the relationship between blood pressure (BP) and symptoms in a cohort of PD patients with the goal of identifying a hemodynamic target to guide treatment. We measured BP supine and upright (tilt or active standing) and identified the presence or absence of symptomatic OH by using a validated patient‐reported outcome questionnaire in 210 patients with PD. We evaluated the usefulness of the 20/10 and 30/15 mmHg diagnostic criteria (systolic/diastolic) to identify symptomatic OH. Fifty percent of the PD patient cohort met criteria for the 20/10 fall and 30% for the 30/15 BP fall. Among the patients who met either OH criteria, the percentage of those with symptoms was small (33% of those with 20/10 and 44% of those with 30/15 mmHg; 16% and 13%, respectively, overall). Symptomatic OH was associated with an upright mean BP below 75 mmHg. A mean standing BP <75 mmHg had a sensitivity of 97% and a specificity of 98% for detecting symptomatic OH. Although the prevalence of OH in PD is high, not all patients have symptoms of organ hypoperfusion. A mean standing BP below 75 mmHg appears to be a useful benchmark when deciding whether the benefits of initiating pharmacological treatment of OH outweigh the risks of exacerbating supine hypertension. © 2015 International Parkinson and Movement Disorder Society     

Patrones de recaída y respuesta patológica según tipo subrogado en pacientes con cáncer de mama y axila negativa al inicio tratadas con quimioterapia neoadyuvante

PurposeTo determine relapse patterns and pathological response in relation to surrogate types of breast cancer after neoadjuvant treatment to analyse survival and optimize surveillance.Material and methodsRetrospective analysis of 112 patients with 116 tumours, with negative axillary involvement, treated with neoadjuvant chemotherapy at our hospital, between 2008 and 2014, who systematically underwent surgery. We analysed pathological response according to surrogate subtypes, rates and patterns of recurrence, disease free survival (DFS) and overall survival (OS).ResultsPathological complete response (pCR) was achieved in 52.6%, finding that these patients had better survival (p< .05). Looking at surrogate subtypes, we observed a pCR in 85% of pure Her-2/neu positive tumours, 65.6% of triple negatives, 43.8% of Her -2 positive Luminal B, 40% of Luminal B and 25% of Luminal A (p< .05). With a median follow-up of 53 months, we found a 9% rate of relapses. The less aggressive types had a median loco-regional relapse time of 38.5 months and a systemic recurrence time of 74 months. The more aggressive types showed a loco-regional relapse time of 36.2 months and systemic recurrence time of 8 months.ConclusionsNeoadjuvant chemotherapy according to surrogate type is a useful strategy to attempt pCR. Loco-regional relapse and systemic recurrence patterns allow surveillance adjustments.     

Effect of bimodal mesoporous carbon as PtRu catalyst support for direct methanol fuel cells

Mesoporous carbons (MCs) with different pore sizes were synthesized and evaluated as a catalyst support for fuel cells. The MCs were obtained from resorcinol–formaldehyde precursors, polymerized in the presence of polydiallyldimethylammonium chloride (cationic polyelectrolyte) as a structuring agent and commercial silica (Sipernat® or Aerosil®) as the hard template. The MC obtained with Aerosil® shows a broad pore size distribution with a maximum at 21 nm. On the other hand, the MCs with Sipernat® show a bimodal pore size distribution, with a narrow peak centered at 5 nm and a broad peak with a maximum ca. 30 nm. All MCs present a high specific surface area (800–1000 m² g⁻¹) and total pore volume ranging from 1.36 to 1.69 cm³ g⁻¹. PtRu nanoparticles were deposited onto the MC support by an impregnation–reduction method with NaBH₄ at 80 °C in basic media. The electrochemical characterization reveals improved electrocatalysis towards the methanol oxidation for the catalyst deposited over the carbon with the highest total pore volume. This catalyst also presented the highest CO₂ conversion efficiency, ca. 80%, for the methanol oxidation as determined by differential electrochemical mass spectroscopy analysis. Moreover, the catalyst as a fuel cell anode showed the best performance, reaching a power density of 125 mW cm⁻² at 90 °C with methanol as fuel and dry O₂.

A porous carbon with different pore sizes was synthesized and employed as support for PtRu nanoparticles.     

Is ambulatory blood pressure monitoring useful in patients with chronic autonomic failure?

Management of blood pressure (BP) abnormalities in patients with autonomic failure is usually based on office BP readings. It is uncertain, whether office readings reflect actual BPs during a typical day. Therefore, in 45 patients with autonomic failure, we compared office BP values during a tilt test with those captured on a 24-h ambulatory monitor. Office BP values while supine predicted well the level of nighttime hypertension. However, in only 33 % of patients, office values during tilt test accurately reflected hypotension during a typical day. Therefore, ambulatory monitoring is useful to gauge the true severity of hypotension in patients with autonomic failure.     

Control of blood pressure levels in patients with premature coronary artery disease: Results from the Genetics of Atherosclerotic Disease study

High blood pressure (BP) is the major cardiovascular‐risk factor for coronary artery disease (CAD), principally in young patients who have an important and increasing socioeconomic burden. Despite the Seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC‐7), recommended BP target <140/90 mm Hg for patients with stable CAD, in 2017 the American College of Cardiology and the American Heart Association (ACC/AHA) updated BP target to <130/80 mm Hg. We aimed to analyze the prevalence of BP control in patients with premature CAD using both criteria. In addition, antihypertensive therapy, lifestyle, clinical, and sociodemographic characteristics of the patients were evaluated in order to identify factors associated with the achievement of BP targets. The present study included 1206 patients with CAD diagnosed before 55 and 65 years old in men and women, respectively. Sociodemographic, clinical, and biochemical data were collected. The results indicate that 85.6% and 77.5% of subjects with premature CAD achieved JNC‐7 non‐strict and ACC/AHA strict BP target, respectively. Consistently, number of antihypertensive drugs and hypertension duration >10 years were inversely associated with BP targets, whereas total physical activity and smoking were directly associated with BP targets, regardless of BP criteria. Considering that age, gender, and hypertension duration are non‐modifiable cardiovascular‐risk factors, our results highlight the need for more effective strategies focused on increase physical activity and smoking cessation in young patients with CAD. These healthier lifestyles changes should favor the BP target achievement and reduce the socioeconomic and clinical burden of premature CAD.     

Disturbances in affective touch in hereditary sensory & autonomic neuropathy type III

Hereditary sensory and autonomic neuropathy type III (HSAN III, Riley–Day syndrome, Familial Dysautomia) is characterised by elevated thermal thresholds and an indifference to pain. Using microelectrode recordings we recently showed that these patients possess no functional stretch-sensitive mechanoreceptors in their muscles (muscle spindles), a feature that may explain their lack of stretch reflexes and ataxic gait, yet patients have apparently normal low-threshold cutaneous mechanoreceptors. The density of C-fibres in the skin is markedly reduced in patients with HSAN III, but it is not known whether the C-tactile afferents, a distinct type of low-threshold C fibre present in hairy skin that is sensitive to gentle stroking and has been implicated in the coding of pleasant touch are specifically affected in HSAN III patients. We addressed the relationship between C-tactile afferent function and pleasant touch perception in 15 patients with HSAN III and 15 age-matched control subjects. A soft make-up brush was used to apply stroking stimuli to the forearm and lateral aspect of the leg at five velocities: 0.3, 1, 3, 10 and 30 cm/s. As demonstrated previously, the control subjects rated the slowest and highest velocities as less pleasant than those applied at 1–10 cm/s, which fits with the optimal velocities for exciting C-tactile afferents. Conversely, for the patients, ratings of pleasantness did not fit the profile for C-tactile afferents. Patients either rated the higher velocities as more pleasant than the slow velocities, with the slowest velocities being rated unpleasant, or rated all velocities equally pleasant. We interpret this to reflect absent or reduced C-tactile afferent density in the skin of patients with HSAN III, who are likely using tactile cues (i.e. myelinated afferents) to rate pleasantness of stroking or are attributing pleasantness to this type of stimulus irrespective of velocity.