Search results for "coda"

The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo

1998

The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral …

Analysis of the infectious entry pathway of human papillomavirus type 33 pseudovirions.

2002

AbstractHuman papillomavirus type 33 (HPV-33) pseudovirus infection is a slow process dependent on the initial interaction with cell-surface heparan sulfate (T. Giroglou, L. Florin, F. Schafer, R. E. Streeck, and M. Sapp, 2001a, J. Virol. 75, 1565–1570). We have now further dissected the initial steps of pseudovirus uptake using removal of cell-surface proteoglycans and selective inhibition of entry pathways. Treatment of cells with heparinase I, but not with phosphoinositol-specific phospholipase C (PIPLC), prevented binding of papillomavirus-like particles and infection with HPV-33 pseudovirions, indicating that GPI-linked proteoglycans (glypicans) are not required for productive infectio…

Les récepteurs olfactifs et le codage des odeurs

2008

The first step of the olfactory detection involves the activation by odorants of olfactory receptors, which are membrane proteins embedded in the membrane of olfactory neurons. Odour coding results from the combinatory activation of a set of receptors and rests on their clonal expression. Neuronal olfactory connexion leads to the formation, in the cortex, of a specific sensory map, which gives rise to the odor perception. This combinatorial system allows, with approximately 340 different receptors, to discriminate myriads of odorants that are natural or not (new cooking flavours, synthetic chemicals…). The extreme olfactory genome diversity in human beings may explain different food behavio…

Freshwater ostracods (Crustacea: Ostracoda) of the circum-Sicilian islands

2007

Ostracods of Mediterranean temporary inland waters (Greece, Southern Italy, and Malta)

2015

Estratigrafía y paleontología del yacimiento QUIN-18 (Formación Valmayor, Frasniense, sinclinal de Almaden, España)

2021

n el núcleo del Sinclinal de Almadén (Ciudad Real, España) aflora una potente sucesión vulcano-sedimentaria (Complejo Vulcano-Sedimentario de Chillón), que se apoya sobre una sucesi6n esencialmente limo-pelÍtica (Fm. Yalmayor), ambas frasnienses, en el techo de esta ultima se encontr6 el yacimiento QUIN- I 8, especialmente rico en braquiópodos y ostrácodos fósiles. La edad indicada por estos correspondería a la parte alta de la Zona de Mesotaxis asymmetricus Media hasta la Zona de M. asymmetricus Superior (parte alta de la Zona de Palmatolepis punctata a la Zona de P. hassi Inferior, en la zonación estandar de conodontos).
 Los ostrácodos pertenecen al llamado ecotipo (ökotyp) eifélico…

Dis-organizing centrosomal clusters: specific cancer therapy for a generic spread?

2015

Cancer is a leading cause of mortality and the annual incidence of new cancer cases is rising worldwide. Due to the frequent development of resistance and the side effects of established anti-cancer drugs, the quest for new drugs with improved therapeutic features goes on. In contrast to cytotoxic chemotherapy of the past, the concept of targeted chemotherapy attempts to increase specificity of therapy by attacking tumor-related mechanisms. A novel emerging treatment concept represents the inhibition of centrosomal clustering. The centrosome regulates mitotic spindle formation assuring uniform separation of chromosomes to daughter cells. Many tumors contain supernumerary centrosomes, which …

Perturbation vectors to evaluate air quality using lichens and bromeliads: a Brazilian case study.

2017

10 pages; International audience; Samples of one lichen species, Parmotrema crinitum, and one bromeliad species, Tillandsia usneoides, were collected in the state of Rio de Janeiro, Brazil, at four sites differently affected by anthropogenic pollution. The concentrations of aluminum, cadmium, copper, iron, lanthanum, lead, sulfur, titanium, zinc, and zirconium were determined by inductively coupled plasma-atomic emission spectroscopy. The environmental diagnosis was established by examining compositional changes via perturbation vectors, an underused family of methods designed to circumvent the problem of closure in any compositional dataset. The perturbation vectors between the reference s…

New insights into seismic absorption imaging

2020

Abstract In recent years, attenuation has been used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. From seismic hazard analysis to oil and gas exploration and rock physics, many fields need a better reconstruction of energy absorption, a constituent of seismic attenuation generally considered a reliable marker of fluid saturation in space. Here, we propose absorption tomography (AT), a technique grounded on the principles of scattering tomography and Multiple Lapse Time Window Analysis. We benchmark its efficiency to image absorption in space by comparing its results with those obt…

Understanding seismic path biases and magmatic activity at Mount St Helens volcano before its 2004 eruption

2020

SUMMARY In volcanoes, topography, shallow heterogeneity and even shallow morphology can substantially modify seismic coda signals. Coda waves are an essential tool to monitor eruption dynamics and model volcanic structures jointly and independently from velocity anomalies: it is thus fundamental to test their spatial sensitivity to seismic path effects. Here, we apply the Multiple Lapse Time Window Analysis (MLTWA) to measure the relative importance of scattering attenuation vs absorption at Mount St Helens volcano before its 2004 eruption. The results show the characteristic dominance of scattering attenuation in volcanoes at lower frequencies (3–6 Hz), while absorption is the primary atte…