Cooperation between passive and active silicon transporters clarifies the ecophysiology and evolution of biosilicification in sponges.

The biological utilization of dissolved silicon (DSi) influences ocean ecology and biogeochemistry. In the deep sea, hexactinellid sponges are major DSi consumers that remain poorly understood. Their DSi consumption departs from the Michaelis-Menten kinetics of shallow-water demosponges and appears particularly maladapted to incorporating DSi from the modest concentrations typical of the modern ocean. Why did sponges not adapt to the shrinking DSi availability that followed diatom expansion some 100 to 65 million years ago? We propose that sponges incorporate DSi combining passive (aquaglyceroporins) and active (ArsB) transporters, while only active transporters (SITs) operate in diatoms and choanoflagellates. Evolution of greater silicon transport efficiency appears constrained by the additional role of aquaglyceroporins in transporting essential metalloids other than silicon. We discuss the possibility that lower energy costs may have driven replacement of ancestral SITs by less efficient aquaglyceroporins, and discuss the functional implications of conservation of aquaglyceroporin-mediated DSi utilization in vertebrates.

Enhanced resilience towards ROADM-induced optical filtering using subcarrier multiplexing and optimized bit and power loading.

In flexible optical networks, lightpaths are routed from source to destination thanks to reconfigurable optical add-drop multiplexers (ROADMs) placed in every node connected by a line system. As ROADMs are based on wavelength selective switches (WSSs), which imply channel filtering, a non negligible performance reduction can be observed when lightpaths traverse many network nodes. Control plane software network controllers that base their decision on the quality of transmission of the physical layer must also take into account the impact of ROADMs cascading. The penalties caused by WSS cascading in single-carrier systems are mostly driven by uncompensated inter-symbol interference (ISI), and therefore their evaluation cannot be based on simple analytical solutions as required for real-time network control. In this paper, we consider a 200G optical system based on multi-subcarrier (MSC) modulation with hybrid modulation formats. Using a fully analytical framework, we show that it is possible to predict ROADM-induced penalties offline and accurately estimate the required settings for their transmitter-side mitigation through bit and/or power-loading. Moreover, resorting to both simulations and experiments, we also demonstrate that properly optimized MSC signals can provide an increased resilience to ROADM filtering with respect to standard single-carrier systems: applying analytically-driven bit-loading over 8×4 Gbaud and 16×2 Gbaud MSC signals after crossing 8 cascaded WSSs in a noise loading scenario, we experimentally found ∼2 dB gain in required SNR with respect to a traditional 32 Gbaud single-carrier signal.

Population structure and connectivity in the Mediterranean sponge Ircinia fasciculata are affected by mass mortalities and hybridization.

Recent episodes of mass mortalities in the Mediterranean Sea have been reported for the closely related marine sponges Ircinia fasciculata and Ircinia variabilis that live in sympatry. In this context, the assessment of the genetic diversity, bottlenecks and connectivity of these sponges has become urgent in order to evaluate the potential effects of mass mortalities on their latitudinal range. Our study aims to establish (1) the genetic structure, connectivity and signs of bottlenecks across the populations of I. fasciculata and (2) the hybridization levels between I. fasciculata and I. variabilis. To accomplish the first objective, 194 individuals of I. fasciculata from 12 locations across the Mediterranean were genotyped at 14 microsatellite loci. For the second objective, mitochondrial cytochrome c oxidase subunit I sequences of 16 individuals from both species were analyzed along with genotypes at 12 microsatellite loci of 40 individuals coexisting in 3 Mediterranean populations. We detected strong genetic structure along the Mediterranean for I. fasciculata, with high levels of inbreeding in all locations and bottleneck signs in most locations. Oceanographic barriers like the Almeria-Oran front, North-Balearic front and the Ligurian-Thyrrenian barrier seem to be impeding gene flow for I. fasciculata, adding population divergence to the pattern of isolation by distance derived from the low dispersal abilities of sponge larvae. Hybridization between both species occurred in some populations that might be increasing genetic diversity and somewhat palliating the genetic loss caused by population decimation in I. fasciculata.

Characterization of the transcriptome and gene expression of four different tissues in the ecologically relevant sea urchin Arbacia lixula using RNA-seq.

The sea urchin Arbacia lixula is a keystone species in Mediterranean ecosystems that drive landscape changes in littoral communities. However, genomic information available for the whole order Arbacioida is very limited. Using RNA-seq techniques, we have characterized the transcriptome of four different tissue types in A. lixula: the 'somatic' tissues (coelomocytes and digestive tissue) and the 'reproductive' tissues (ovary and testis), from two replicated cDNA libraries for each sample. Additionally, we performed a de novo assembly to build the 'reference' transcriptome, pooling reads of the four tissues, to analyse the differential expression (DE) in pairwise comparisons between tissues. The complete de novo assembly yielded 186,084 transcripts, with a sequence size limit of 100 nt, being 31% of them spliced isoforms. Approximately 21% of the transcripts had blast hits against proteins of metazoans (E < 10(-5) ), being less than 2.2% functionally annotated. Between coelomocytes and digestive, 30,794 transcripts showed DE (~11.8% of them with blast hit), and 19,567 transcripts did so between testis and ovary (~28.5% of them with blast hit). Major GO-term categories upregulated in somatic tissues were those related to muscle contraction and energy generation in digestive, and lipid metabolism associated with immune response in coelomocytes. Between reproductive tissues, the major upregulated GO categories were related to energy generation in testis, and negative regulation of nucleotide metabolism in ovary. We particularly screened for a collection of target genes in each tissue because of their relevance for further studies on evolution and adaptation of echinoids.

Frequency-resolved noise figure measurements of phase (in)sensitive fiber optical parametric amplifiers.

We measure the frequency-resolved noise figure of fiber optical parametric amplifiers both in phase-insensitive and phase-sensitive modes in the frequency range from 0.03 to 3 GHz. We also measure the variation in noise figure due to the degradation in pump optical signal to noise ratio and also as a function of the input signal powers. Noise figure degradation due to stimulated Brillouin scattering is observed.

Occurrence of somatic cells within the spermatic cysts of demosponges: a discussion of their role.

During ultrastructural studies on the spermatogenesis of two demosponges, Raspaciona aculeata and Petrosia ficiformis, somatic cells were detected within their spermatic cysts. In R. aculeata large, amoeboid somatic cells, presumably derived from follicle cells, were found inside cysts filled with secondary spermatocytes. These cells were actively phagocytosing spermatocytes. Such phagocytosis could be directed to eliminate aberrant spermatogenic cells, maintain appropriate cell number within the cysts, or recapture energetic reserves originally allocated to the reproductive process via phagocytosis of spermatocytes. In P. ficiformis, somatic round cells were observed only after the spawning event, phagocytosing unspawned sperm in nearly emptied spermatic cysts. Unlike in R. aculeata, these cells were more similar to archaeocytes (common cells of the demosponge mesohyl with phagocytic activity) than to follicle cells. Phagocytosis of spermatogenic cells and unspawned spermatozoa by somatic cells from the wall of the testes is a well-known process in vertebrates and many invertebrates. Occurrence of somatic cells in the spermatic cysts of sponges, whose function appears to be partially analogous to that of Sertoli cells, reveals that sponges possess cellular mechanisms to regulate testis functioning that are equivalent to those in higher metazoans.

[Renal function and cardiovascular risk in patients with essential hypertension. The "FRESHA" study]. / Función renal y riesgo cardiovascular en pacientes con hipertensión arterial esencial. Estudio FRESHA.

BACKGROUND: In the past few years there has been a growing amount of information about renal dysfunction and cardiovascular risk. The objectives of this study were to assess the prevalence of renal dysfunction and evaluate the relation between renal function and cardiovascular risk in patients with essential hypertension. METHODS: A multicenter, cross-sectional survey of unselected patients with essential hypertension attending primary care settings in Spain was performed between june and november 2004. Renal function was evaluated with the abbreviated equation of the Modification of Diet in Renal Disease study. Renal insufficiency was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m2. RESULTS: Eighty-eight investigators from 50 centers recruited 2130 patients being mean age 65.6 +/- 11 years and female 53%. Prevalence of diabetes, lipid abnormalities, and previous cardiovascular disease were 30.3%, 45.9%, and 42.1% respectively. Prevalence of renal insufficiency was 32.4% (95% CI 30.4-34.4). Patients suffering from renal insufficiency showed a higher prevalence of cardiovascular disease when comparing with those with an estimated glomerular filtration rate = or >60 ml/min/1.73 m2 (56.2% vs. 35.3%, OR 2.35, 95% CI 1.95-2.82, p < 0.001). A logistic regression analysis showed that the relation of renal dysfunction with cardiovascular disease was independent of other variables or classical cardiovascular risk factors as age, female sex, diabetes, smoking, hypercholesterolemia, and systolic blood pressure. CONCLUSIONS: Renal insufficiency was present in 32.4% of patients with essential hypertension attending primary care settings. Cases with renal dysfunction showed a higher cardiovascular risk. Hypertensive patients with renal insufficiency should be considered as candidates for an aggressive approach of cardiovascular risk management.

Disfunção sistólica aguda de ventrículo esquerdo após drenagem de derrame pericárdico / Transient left ventricular systolic dysfunction after pericardial effusion drainage

Paciente com timoma e função sistólica normal do ventrículo esquerdo desenvolveu tamponamento cardíaco, revertido por pericardiocentese. Após quatro dias, foi submetida à exérese do tumor e, em aproximandamente uma semana da drenagem, apresentou disfunção sistólica aguda e grave do ventrículo esquerdo, que melhorou com terapia venosa, normalizando o quadro em três dias.

[Acute left ventricular systolic dysfunction after pericardial effusion drainage]. / Disfunção sistólica aguda de ventrículo esquerdo após drenagem de derrame pericárdico.

A patient with a thymoma and initially normal ventricular systolic function developed cardiac tamponade, which was relieved by pericardiocentesis. After four days, the tumor was removed and, one week after the relief of tamponade, she developed severe left ventricular systolic dysfunction, that recovered in three days with venous therapy.