Use of satellite observations for operational oceanography: recent achievements and future prospects

The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite observations are important future priorities

Antenatal environmental stress and maturation of the breathing control, experimental data.

International audienceThe nervous respiratory system undergoes postnatal maturation and yet still must be functional at birth. Any antenatal suboptimal environment could upset either its building prenatally and/or its maturation after birth. Here, we would like to briefly summarize some of the major stresses leading to clinical postnatal respiratory dysfunction that can occur during pregnancy, we then relate them to experimental models that have been developed in order to better understand the underlying mechanisms implicated in the respiratory dysfunctions observed in neonatal care units. Four sections are aimed to review our current knowledge based on experimental data. The first will deal with the metabolic factors such as oxygen and glucose, the second with consumption of psychotropic substances (nicotine, cocaine, alcohol, morphine, cannabis and caffeine), the third with psychoactive molecules commonly consumed by pregnant women within a therapeutic context and/or delivered to premature neonates in critical care units (benzodiazepine, caffeine). In the fourth section, we take into account care protocols involving extended maternal-infant separation due to isolation in incubators. The effects of this stress potentially adds to those previously described

Rhythmic activity from transverse brainstem slice of neonatal rat is modulated by nitric oxide.

We investigated the role of nitric oxide (NO) in the modulation of respiratory-like activity recorded from hypoglossal rootlets in brainstem slices of neonatal rats (P0-P8). Sodium nitroprusside (SNP), S-Nitroso-N-acetyl-D,L-penicillamine (SNAP) and diethylamine-NO (DEA-NO), three NO-donors, reversibly increased hypoglossal burst amplitude with inconsistent effects on burst frequency. Similar effects were also obtained with the endogenous substrate of nitric oxide synthase (NOS), L-arginine, whereas the inactive enantiomer D-arginine had no effect. The NO-trap agent methylene blue significantly depressed both the amplitude and frequency of hypoglossal activity while hemoglobin depressed only the amplitude. Furthermore, the addition of NO-trap agents significantly attenuated the excitatory response to SNP. Inhibiting NOS with either N(omega)-Nitro-L-Arginine (L-NNA) or 7-Nitroindazole (7-NI), decreased the amplitude of hypoglossal activity with no effects on frequency. Histochemical analysis of NADPH-diaphorase activity, a marker for NOS, was performed on slices not treated pharmacologically and in brainstem sections of newborn rats, perfused in situ. Comparison between in vitro and in vivo conditions indicated that NOS activity was maintained in slice preparations. Neurons in the ambiguus and hypoglossal nuclei (dorsal division) exhibited a granular staining, suggesting the presence of NADPHd-positive terminals. Neurons with cytoplasmic staining were identified in regions connected to the hypoglossal nucleus (nucleus tractus solitarius, paramedian and gigantocellular reticular nuclei). These neurons might be involved in nitrergic control of hypoglossal activity. Both pharmacological and histochemical data suggest that endogenous NO may reinforce the output activity of the medullary respiratory network

Brainstem and hypothalamic areas involved in respiratory chemoreflexes: a Fos study in adult rats.

The adaptation to hypoxia and hypercapnia requires the activation of several anatomical structures along the neuraxis. In this study, using Fos immunoreactivity, we sought to map neuronal populations involved in chemoreflex networks activated during the responses to moderate hypoxia (O(2) 11%), and hypercapnia (CO(2) 5%) in the brainstem and the hypothalamus of the rat. In the medulla, hypoxia elicited marked and significant staining in the nucleus of the solitary tract (NTS), and in parapyramidal neurons located near the ventral surface, whereas hypercapnia evoked significantly c-fos only near the ventral surface in paraolivar neurons. In contrast, within pontine and suprapontine structures, both hypoxia and hypercapnia evoked similarly Fos immunoreactivity in the lateral parabrachialis area, the central grey, the caudal hypothalamus (dorsomedial and posterior hypothalamic nuclei), and in a ventro-lateral hypothalamic area, extending from the rostral limit of the mammillary nuclei to the retrochiasmatic area. More rostrally, labelling was observed in the paraventricular nucleus of the hypothalamus in response to hypercapnia, and in the supraoptic nucleus in response to hypoxia. These results support the hypothesis that chemoreflexes pathways are not only restricted to medulla and pons but also involved mesencephalic and hypothalamic regions. The parabrachialis area and the central grey may be key relays between caudal and ventral hypothalamic neurons, and medullary neurons involved in the response to hypoxia and hypercapnia

Changes in Fos-like immunoreactivity evoked by maturation of the sneeze reflex triggered by nasal air puff stimulation in kittens.

The sneeze reflex is a valuable tool for exploring the maturation of the respiratory control in the newborn as it alters both inspiratory and expiratory activities. Air puff stimulation of the superior nasal meatus innervated by ethmoidal afferents consistently evokes sneeze in adult cats. Such stimulation evokes only a reinforcement of expiratory activities in newborn kittens. This study demonstrates that the pattern of Fos-like immunoreactivity evoked by nasal stimulation changes during functional maturation of sneeze. Nasal stimulation evoked immunoreactivity (i) in the trigeminal sensory complex, at the levels where nasal afferents project, (ii) in the reticular formation, (iii) in the solitary complex and (iv) in the parabrachial area of mature kittens. The evoked immunoreactivity was the same in newborn kittens as in mature kittens in the projection areas of the nasal primary afferents. Fos response was less than half that in mature kittens in the reticular formation and absent in the solitary complex or the parabrachial area. Sneeze can be elicited from the time when evoked immunoreactivity in the solitary complex and the parabrachial area is above control levels. These data provide evidence that the maturation of sneeze is dependent on the development of central relays allowing peripheral inputs to be integrated by neurons engaged in respiratory control

Postnatal changes in Fos-like immunoreactivity evoked by hypoxia in the rat brainstem and hypothalamus.

We have recently used Fos expression in adult rats to map neuronal populations activated in the brainstem and hypothalamus during the acute ventilatory response to moderate hypoxia (O(2) 11%). Although present at birth, this response evolves postnatally. The present investigation aimed at a better understanding of these maturational processes by delineating structures that might functionally develop after birth. The developmental pattern Fos expression evoked by hypoxia was analysed in rats aged from 0 to 26 postnatal days. The numbers of Fos positive neurons markedly increased with the age in the medullary areas related to respiratory control during the 2 first postnatal weeks. Thereafter, the response plateaued in the nucleus tractus solitarius and attenuated in the ventral medulla. In the upper brainstem (parabrachial area, central grey) and the hypothalamus (posterior and dorsomedial nuclei, ventral zone), Fos response to hypoxia was absent or weak at birth and increased until late development. The significance of the development of evoked Fos expression in these rostral sites is discussed together with their possible contribution to the maturation of O(2)-sensitive chemoreflex pathways

Sea-level variability in the Mediterranean Sea from altimetry and tide gauges

Sea-level variability in the Mediterranean Sea was investigated by means of in-situ (tide-gauge) and satellite altimetry data over a period spanning two decades (from 1993 to 2012). The paper details the sea-level variations during this time period retrieved from the two data sets. Mean sea-level (MSL) estimates obtained from tide-gauge data showed root mean square differences (RMSDs) in the order of 40–50 % of the variance of the MSL signal estimated from satellite altimetry data, with a dependency on the number and quality of the in-situ data considered. Considering the individual time-series, the results showed that coastal tide-gauge and satellite sea-level signals are comparable, with RMSDs that range between 2.5 and 5 cm and correlation coefficients up to the order of 0.8. A coherence analysis and power spectra comparison showed that two signals have a very similar energetic content at semi-annual temporal scales and below, while a phase drift was observed at higher frequencies. Positive sea-level linear trends for the analysis period were estimated for both the mean sea-level and the coastal stations. From 1993 to 2012, the mean sea-level trend (2.44 ± 0.5 mm year- 1) was found to be affected by the positive anomalies of 2010 and 2011, which were observed in all the cases analysed and were mainly distributed in the eastern part of the basin. Ensemble empirical mode decomposition showed that these events were related to the processes that have dominant periodicities of ∼ 10 years, and positive residual sea-level trend were generally observed in both data-sets. In terms of mean sea-level trends, a significant positive sea-level trend (> 95 %) in the Mediterranean Sea was found on the basis of at least 15 years of data. © 2016, The Author(s)

Effect of postnatal exposure to caffeine on the pattern of adenosine A1 receptor distribution in respiration-related nuclei of the rat brainstem.

Caffeine, which belongs to the methylxantine family of compounds, is commonly ingested in a range of beverages such as coffee, tea, and cola drinks. It is also used therapeutically and is frequently employed in the treatment of respiratory disturbances in human neonates. The aim of the present work has been to examine the ontogeny of the adenosine A1 receptor system in the brainstem of the newborn rat following postnatal treatment with caffeine to mimic the therapeutic administration of caffeine to premature human infants. The effect of this postnatal exposure to caffeine on the gradual appearance of adenosine A1 receptors was analysed by determining immunohistochemically the distribution of the receptors. The main difference between control animals and animals exposed to caffeine was the transient increase (only at postnatal day 6) in the number of immunopositive neurons in two brainstem areas, the ventrolateral medulla and the rostral dorsolateral pons, in caffeine-treated rat pups, or more specifically, the parabrachial and K?ker-Fuse nuclei, both of which are classically associated with respiratory control. With previous research highlighting the important role played by the rostral pons in respiratory modulation by the adenosine A1 receptor system, it is thus possible that postnatal exposure to caffeine modulates the ontogeny of the adenosine A1 receptor network. This could imply that the role of caffeine to decrease the incidence of neonatal respiratory disturbances may be due to the earlier than normal development of the adenosinergic system in the brain