Localization and anchorage of maternal mRNAs to cortical structures of ascidian eggs and embryos using high resolution in situ hybridization.

In several species, axis formation and tissue differentiation are the result of developmental cascades which begin with the localization and translation of key maternal mRNAs in eggs. Localization and anchoring of mRNAs to cortical structures can be observed with high sensitivity and resolution by fluorescent in situ hybridization coupled with labeling of membranes and macromolecular complexes. Oocytes and embryos of ascidians--marine chordates closely related to vertebrates--are ideal models to understand how maternal mRNAs pattern the simple ascidian tadpole.

Divergent mechanisms specify chordate motoneurons: evidence from ascidians.

Ascidians are members of the vertebrate sister group Urochordata. Their larvae exhibit a chordate body plan, which forms by a highly accelerated embryonic strategy involving a fixed cell lineage and small cell numbers. We report a detailed analysis of the specification of three of the five pairs of motoneurons in the ascidian Ciona intestinalis and show that despite well-conserved gene expression patterns and embryological outcomes compared with vertebrates, key signalling molecules have adopted different roles.

Ammonium transport in the kidney.

Ammonium excretion into the urine is the main mechanism of renal acid excretion. Ammonium is produced by epithelial cells of the proximal tubule and then secreted into the luminal fluid. However, before its final excretion into urine, ammonium ion is reabsorbed by the thick ascending limb (TAL), and accumulated in the interstitium to build up a corticopapillary gradient of ammonium which is necessary for the final diffusion of the gas NH3 in parallel to active proton secretion.

Response of the calcifying coccolithophore to low pH/high pCO: from physiology to molecular level.

The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO in the widespread and abundant coccolithophore . Batch cultures were subjected to increased partial pressure of CO (pCO; i.

Interactions between giant unilamellar vesicles and charged core-shell magnetic nanoparticles.

This work combined two tools, giant unilamellar vesicles (GUVs) and core-shell magnetic nanoparticles (CSMNs), to develop a simplified model for studying interactions between the cell membrane and nanoparticles. We focused on charged functionalized CSMNs that can be either cationic or anionic. Using optical, electron, and confocal microscopy, we found that giant vesicle-nanoparticle interactions did not result from a simple electrostatic phenomenon because cationic CSMNs tended to bind to positively charged bilayers, whereas anionic CSMNs remained inert.

Adaptive remodeling of trabecular bone core cultured in 3-D bioreactor providing cyclic loading: an acoustic microscopy study.

Scanning acoustic microscopy (SAM) provides high-resolution mapping of acoustic impedance related to tissue stiffness. This study investigates changes in tissue acoustic impedance resulting from mechanical loading in trabecular bone cores cultured in 3-D bioreactor. Trabecular bone cores were extracted from bovine sternum (n = 15) and ulna metaphysis (n = 15).

Dual mechanism controls asymmetric spindle position in ascidian germ cell precursors.

Mitotic spindle orientation with respect to cortical polarity cues generates molecularly distinct daughter cells during asymmetric cell division (ACD). However, during ACD it remains unknown how the orientation of the mitotic spindle is regulated by cortical polarity cues until furrowing begins. In ascidians, the cortical centrosome-attracting body (CAB) generates three successive unequal cleavages and the asymmetric segregation of 40 localized postplasmic/PEM RNAs in germ cell precursors from the 8-64 cell stage.

Rod-derived cone viability factor for treating blinding diseases: from clinic to redox signaling.

The identification of one mechanism that causes vision loss in inherited degenerative retinal disorders revealed a new signaling molecule that represents a potential therapy for these currently untreatable diseases. This protein, called rod-derived cone viability factor (RdCVF), maintains the function and consequently the viability of cone photoreceptor cells in the retina; mice that lack this factor exhibit a progressive loss of photoreceptor cells. The gene encoding RdCVF also encodes, by differential splicing, a second product that has characteristics of a thioredoxin-like enzyme and protects both photoreceptor cells and, more specifically, its interacting protein partner, the tau protein, against oxidative damage.

Mertk in daily retinal phagocytosis: a history in the making.

It took 62 years from the description of the retinal dystrophy in rats from the Royal College of Surgeons (RCS) strain to the discovery of the molecular defect underlying the phenotype. Phagocytosis of photoreceptor outer segments (POS) by retinal pigment epithelial (RPE) cells follows a daily rhythm with a peak of activity 1.5-2 h after light onset for rod photoreceptors.

Climate-driven basin-scale decadal oscillations of oceanic phytoplankton.

Phytoplankton--the microalgae that populate the upper lit layers of the ocean--fuel the oceanic food web and affect oceanic and atmospheric carbon dioxide levels through photosynthetic carbon fixation. Here, we show that multidecadal changes in global phytoplankton abundances are related to basin-scale oscillations of the physical ocean, specifically the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. This relationship is revealed in approximately 20 years of satellite observations of chlorophyll and sea surface temperature.

Patterning of the dorsal-ventral axis in echinoderms: insights into the evolution of the BMP-chordin signaling network.

Formation of the dorsal-ventral axis of the sea urchin embryo relies on cell interactions initiated by the TGFbeta Nodal. Intriguingly, although nodal expression is restricted to the ventral side of the embryo, Nodal function is required for specification of both the ventral and the dorsal territories and is able to restore both ventral and dorsal regions in nodal morpholino injected embryos. The molecular basis for the long-range organizing activity of Nodal is not understood.

Structure of carbon dioxide phase IV: breakdown of the intermediate bonding state scenario.

The existence of "intermediate bonding states" in solid CO2, separating the low-pressure molecular phases from the high-pressure polymeric forms, has been the matter of a long-standing debate. Here we determine the structure of CO2-IV using x-ray diffraction of single crystals grown inside a diamond anvil cell at 11.7 GPa and 830 K.

Performances of a bent-crystal spectrometer adapted to resonant x-ray emission measurements on gas-phase samples.

We describe a bent-crystal spectrometer adapted to measure x-ray emission resulting from core-level excitation of gas-phase molecules in the 0.8-8 keV energy range. The spectrometer is based on the Johann principle, and uses a microfocused photon beam to provide high-resolution (resolving power of approximately 7500).

Evidence of premature immune aging in patients thymectomized during early childhood.

While the thymus is known to be essential for the initial production of T cells during early life, its contribution to immune development remains a matter of debate. In fact, during cardiac surgery in newborns, the thymus is completely resected to enable better access to the heart to correct congenital heart defects, suggesting that it may be dispensable during childhood and adulthood. Here, we show that young adults thymectomized during early childhood exhibit an altered T cell compartment.

The timing of the shrew: continuous melatonin treatment maintains youthful rhythmic activity in aging Crocidura russula.

Background: Laboratory conditions nullify the extrinsic factors that determine the wild expected lifespan and release the intrinsic or potential lifespan. Thus, wild animals reared in a laboratory often show an increased lifespan, and consequently an increased senescence phase. Senescence is associated with a broad suite of physiological changes, including a decreased responsiveness of the circadian system.

MMP9 and SCF protect from apoptosis in acute kidney injury.

Apoptosis of tubular epithelial cells is a hallmark of acute kidney injury (AKI), but the cellular events preceding apoptosis in this setting are incompletely understood. Because matrix metalloproteinase 9 (MMP9) degrades matrix components involved in cell survival, we studied the role of MMP9 in AKI. In the mouse model of folic acid-induced AKI, we observed a marked increase of MMP9 activity in the S3 segment of the proximal tubule (S3PT), correlating with the apoptotic phase.

Changes in blood pressure in a large cohort of elderly individuals: Study 3C.

Objective: Analysis of changes in blood pressure with a two-year interval, and of factors associated with this change, in a large cohort of elderly individuals.

Methods: Follow-up of a cohort of 9294 individuals aged 65 years and over recruited from the general population for Study 3C. Changes in blood pressure are defined as the difference in its averages between the inclusion visit and the follow-up visit at 2 years.

Genetic factors of susceptibility and of severity in primary biliary cirrhosis.

Background/aims: In primary biliary cirrhosis (PBC), pathogenesis is influenced by genetic factors that remain poorly elucidated up to now. We investigated the impact of sequence diversity in candidate genes involved in immunity (CTLA-4 and TNFalpha), in bile formation (10 hepatobiliary transporter genes) and in the adaptative response to cholestasis (three nuclear receptor genes) on the susceptibility and severity of PBC.

Methods: A total of 42 Ht SNPs were identified and compared in 258 PBC patients and two independent groups of 286 and 269 healthy controls.

Clues about the genetic basis of adaptation emerge from comparing the proteomes of two Ostreococcus ecotypes (Chlorophyta, Prasinophyceae).

We compared the proteomes of two picoplanktonic Ostreococcus unicellular green algal ecotypes to analyze the genetic basis of their adaptation with their ecological niches. We first investigated the function of the species-specific genes using Gene Ontology databases and similarity searches. Although most species-specific genes had no known function, we identified several species-specific functions involved in various cellular processes, which could be critical for environmental adaptations.

GDF15 triggers homeostatic proliferation of acid-secreting collecting duct cells.

Although adult kidney cells are quiescent, enlargement of specific populations of epithelial cells occurs during repair and adaptive processes. A prerequisite to the development of regenerative therapeutics is to identify the mechanisms and factors that control the size of specific populations of renal cells. Unfortunately, in most cases, it is unknown whether the growth of cell populations results from transdifferentiation or proliferation and whether proliferating cells derive from epithelial cells or from circulating or resident progenitors.