Stem cells for the replacement of inner ear neurons and hair cells

Stem cells in the nervous system have some capacity to restore damaged tissue. Proliferation of stem cells endows them with self-renewal ability and accounts for in vitro formation of neurospheres, clonally derived colonies of floating cells. However, damage to the nervous system is not readily repaired, suggesting that the stem cells do not provide an easily recruited source of cells for regeneration. The vestibular and auditory organs, despite their limited ability to replace damaged cells, appear to contain cells with stem cell properties. These inner ear stem cells, identified by neurosphere formation and by their expression of markers of inner ear progenitors, can differentiate to hair cells and neurons. Differentiated cells obtained from inner ear stem cells expressed sensory neuron markers and, after co-culture with the organ of Corti, grew processes that extended to hair cells. The neurons expressed synaptic vesicle markers at points of contact with hair cells. Exogenous stem cells have also been used for hair cell and neuron replacement. Embryonic stem cells are one potential source of both hair cells and sensory neurons. Neural progenitors made from embryonic stem cells, transplanted into the inner ear of gerbils that had been de-afferented by treatment with a toxin, differentiated into cells that expressed neuronal markers and grew processes both peripherally into the organ of Corti and centrally. The regrowth of these neurons suggests that it may be possible to replace auditory neurons that have degenerated with neurons that restore auditory function by regenerating connections to hair cells.     

Geographic structure in Gran Chaco Amerindians based on five X-chromosome STRs

We investigated the genetic differentiation of five X-chromosome STR markers among five native South American Amerindian populations inhabiting three different areas of the Gran Chaco: Mocoví, Chorote, Wichí, Lengua, and Ayoreo. The observed genetic structure showed correspondence with geographic distribution more clearly than previous information obtained from autosomal STRs for the same samples. On the other hand, X-chromosome STR data did not agree with linguistic affinities. These markers proved to be informative for the study of the native populations of the Gran Chaco region.     

Effects of light quality,CO2 tensions and NO 3 +− concentrations on the inorganic nitrogen metabolism of Chlamydomonas reinhardii

The blue light dependent utilization of nitrate by green algae under common air and high irradiances, besides its assimilatory nature, is associated with the release of NO₂ ^– and NH₄ ⁺ to the culture medium. If the CO₂ content of the sparging air was increased up to 2%, previously excreted NO₂ ^– and NH₄ ⁺ were rapidly assimilated. When under air and high irradiances the cell density in the culture reached values corresponding to 25 g Ch 1.ml^-1, no further growth was observed and the highest values of NO₃ ^– consumption and NO₂ ^– and NH₄ ⁺ release were attained. Besides low CO₂ tensions, increasing NO₃ ^– concentrations in the medium stimulated the release of NO₃ ^– and NH₄ ⁺. Under CO₂-free air the consumption of NO₃ ^– and the release of NO₂ ^– and NH₄ ⁺ on a total N bases were almost stoichiometric and their rates saturated at much lower irradiances than under air. Under CO₂-free air high rates of NO₂ ^– release were only observed under the blue radiations that were effectively absorbed by photosynthetically active pigments, i.e. 460 nm, but not under 404 and 630 nm radiations. However, the simultaneous illumination of the cells with 404 and 630 nm monochromatic light showed a remarkable synergistic effect on NO₂ ^– release.The results are discussed in terms of the close relationship between C and N metabolism, the photosynthetic reducing power required to convert NO _inf3 ^sup± -N into R – NH₂-N and the blue light activation of nitrate reductase.     

Determination of protein concentration in downstream biomanufacturing processes by in-line index of refraction

Protein concentration determination is a necessary in-process control for the downstream operations within biomanufacturing. As production transitions from batch mode to an integrated continuous bioprocess paradigm, there is a growing need to move protein concentration quantitation from off-line to in-line analysis. One solution to fulfill this process analytical technology need is an in-line index of refraction (IoR) sensor to measure protein concentration in real time. Here the performance of an IoR sensor is evaluated through a series of experiments to assess linear response, buffer matrix effects, dynamic range, sensor-to-sensor variability, and the limits of detection and quantitation. The performance of the sensor was also tested in two bioprocessing scenarios, ultrafiltration and capture chromatography. The implementation of this in-line IoR sensor for real-time protein concentration analysis and monitoring has the potential to improve continuous bioprocess manufacturing.     

Foliar application of urea to “Sauvignon Blanc” and “Merlot” vines: doses and time of application

A careful control of the N nutritional status of grapevines can have a determining effect on wine characteristics; therefore a suitable management of N fertilization might allow some wine parameters to be modified, thereby improving product quality. The aim of this study was to determine the effect of foliar application of urea at different doses and different times of the growing season on the parameters of Sauvignon Blanc and Merlot grape juice. The research described herein involved Sauvignon Blanc and Merlot grapevines (V. vinifera L.) at a commercial vineyard and was conducted over 2 years. In the first year, N treatment involved a foliar application at a dose of 10 kg N ha^?1 during veraison, whereas in the second year it involved a foliar urea application at two doses (10 and 50 kg N ha^?1) and at three different times—3 weeks before veraison, during veraison and 3 weeks after veraison. In this second year, the urea applied at a dose of 10 kg N ha^?1 was isotopically labelled with 1% ¹⁵N. Chemical parameters, yeast assimilable N, amino acid content, amino acid profile and N isotopic composition were determined for all treatments. Grape and grape-juice parameters for Merlot were found to be more affected by N fertilization than for Sauvignon Blanc and were also more affected during the second year than during the first year, thus indicating that the climatic characteristics of each campaign could affect these parameters. The yeast assimilable N in grape juice was found to be higher for late applications of foliar urea, with application of the higher dose of urea during veraison increasing the amino acid and proline contents in both varieties. The isotopic analysis data showed that the urea applied to leaves was transferred to the berries, with the maximum translocation in Sauvignon Blanc occurring for the post-veraison treatment and in Merlot for the veraison treatment. We can therefore conclude that foliar application of urea could modify grape juice quality and could therefore be used as a tool for obtaining quality wines.     

Epithelial organization: may the force be with you

Multicellular organization is determined by the balance of forces between cells as much as by the expression of genes. A recent study in Drosophila combines physical modeling with experimental measurements and mechanical perturbations to shed light on the processes that influence cell patterns in vivo.     

The Effects of Direct Instillations of a Therapeutic Mixture Into the Tracheobronchial Tree

Twenty-two patients with chronic productive bronchitis or bronchiectasis were treated by direct instillations of normal saline and N-acetylcysteine into the trachea through a percutaneous catheter following a period of conventional routine therapy.The instillation, using either normal saline or varying concentrations of N-acetylcysteine did not produce significant change in alveolar gas exchange as reflected by measurement of arterial PaCO₂ and the alveolar arterial gradient for oxygen during and after the introduction of the medication into the bronchial tree. Studies were carried out after patients had been stabilized breathing pure oxygen on an IPPB machine for 30 minutes.Evaluation of the treatment by means of pulmonary function tests demonstrated significant improvement in overall function following therapy.The results indicate that the technique of tracheobronchial lavage is physiologically benign and that overall improvement in pulmonary function can be obtained by this means in cases of the type described in this study.     

Endogenous circadian rhythms in pigment composition induce changes in photochemical efficiency in plant canopies

There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical efficiency. To address these questions, we maintained canopies of bean and cotton, after an entrainment phase, under constant (light or darkness) conditions for 30–48 h. Photosynthesis and quantum yield peaked at subjective noon, and non‐photochemical quenching peaked at night. These oscillations were not associated with parallel changes in carbohydrate content or xanthophyll cycle activity. We observed robust oscillations of Chl a/b during constant light in both species, and also under constant darkness in bean, peaking when it would have been night during the entrainment (subjective nights). These oscillations could be attributed to the synthesis and/or degradation of trimeric light‐harvesting complex II (reflected by the rhythmic changes in Chl a/b), with the antenna size minimal at night and maximal around subjective noon. Considering together the oscillations of pigments and photochemistry, the observed pattern of changes is counterintuitive if we assume that the plant strategy is to avoid photodamage, but consistent with a strategy where non‐stressed plants maximize photosynthesis.