Shine a light: Under-ice light and its ecological implications in a changing Arctic Ocean.

The Arctic marine ecosystem is shaped by the seasonality of the solar cycle, spanning from 24-h light at the sea surface in summer to 24-h darkness in winter. The amount of light available for under-ice ecosystems is the result of different physical and biological processes that affect its path through atmosphere, snow, sea ice and water. In this article, we review the present state of knowledge of the abiotic (clouds, sea ice, snow, suspended matter) and biotic (sea ice algae and phytoplankton) controls on the underwater light field. We focus on how the available light affects the seasonal cycle of primary production (sympagic and pelagic) and discuss the sensitivity of ecosystems to changes in the light field based on model simulations. Lastly, we discuss predicted future changes in under-ice light as a consequence of climate change and their potential ecological implications, with the aim of providing a guide for future research.

F-Specific RNA Bacteriophages, Especially Members of Subgroup II, Should Be Reconsidered as Good Indicators of Viral Pollution of Oysters.

Norovirus (NoV) is the leading cause of gastroenteritis outbreaks linked to oyster consumption. In this study, we investigated the potential of F-specific RNA bacteriophages (FRNAPH) as indicators of viral contamination in oysters by focusing especially on FRNAPH subgroup II (FRNAPH-II). These viral indicators have been neglected because their behavior is sometimes different from that of NoV in shellfish, especially during the depuration processes usually performed before marketing. However, a significant bias needs to be taken into account. This bias is that, in the absence of routine culture methods, NoV is targeted by genome detection, while the presence of FRNAPH is usually investigated by isolation of infectious particles. In this study, by targeting both viruses using genome detection, a significant correlation between the presence of FRNAPH-II and that of NoV in shellfish collected from various European harvesting areas impacted by fecal pollution was observed. Moreover, during their depuration, while the long period of persistence of NoV was confirmed, a similar or even longer period of persistence of the FRNAPH-II genome, which was over 30 days, was observed. Such a striking genome persistence calls into question the relevance of molecular methods for assessing viral hazards. Targeting the same virus (i.e., FRNAPH-II) by culture and genome detection in specimens from harvesting areas as well as during depuration, we concluded that the presence of genomes in shellfish does not provide any information on the presence of the corresponding infectious particles. In view of these results, infectious FRNAPH detection should be reconsidered as a valuable indicator in oysters, and its potential for use in assessing viral hazard needs to be investigated.IMPORTANCE This work brings new data about the behavior of viruses in shellfish, as well as about the relevance of molecular methods for their detection and evaluation of the viral hazard. First, a strong correlation between the presence of F-specific RNA bacteriophages of subgroup II (FRNAPH-II) and that of norovirus (NoV) in shellfish impacted by fecal contamination has been observed when both viruses are detected using molecular approaches. Second, when reverse transcription-PCR and culture are used to detect FRNAPH-II in shellfish, it appears that the genomes of the viruses present a longer period of persistence than infectious virus, and thus, virus genome detection fails to give information about the concomitant presence of infectious viruses. Finally, this study shows that FRNAPH persist at least as long as NoV does. These data are major arguments to reconsider the potential of FRNAPH as indicators of shellfish viral quality.

Relevance of F-Specific RNA Bacteriophages in Assessing Human Norovirus Risk in Shellfish and Environmental Waters.

UNLABELLED: Human noroviruses (HuNoVs) are the main cause of shellfish-borne gastroenteritis outbreaks. In the absence of routine technical approaches allowing infectious particles to be detected, this viral pathogen is currently targeted by genome research, leading to difficult interpretations. In this study, we investigated the potential of F-specific RNA bacteriophages (FRNAPH) as fecal and viral contamination indicators in shellfish and water from a local harvesting area. FRNAPH were also used as microbial source tracking tools. Constraints imposed by detection limits are illustrated here by the detection of infectious FRNAPH in several samples in the absence of FRNAPH genomes. The opposite situation was also observed, likely explained by the persistence of the genomes being greater than infectivity. Similar considerations may be applied to HuNoVs, suggesting that HuNoV genome targeting is of limited relevance in assessing infectious risks. While FRNAPH did not provide any benefits compared to Escherichia coli as fecal pollution indicators in water, novel observations were made in shellfish: contrary to E. coli, a seasonal trend of infectious FRNAPH concentrations was observed. These concentrations were higher than those found in water, confirming bioaccumulation in shellfish. This study also underlines a relationship between the presence of HuNoV genomes and those of human-specific FRNAPH subgroup II (FRNAPH-II) in shellfish collected throughout Europe. Further research should be undertaken to evaluate FRNAPH potential as an indicator of the presence of infectious HuNoVs. To this end, shellfish involved in HuNoV-caused gastroenteritis outbreaks should be analyzed for the presence of infectious FRNAPH-II. IMPORTANCE: This work provides new data about the use of F-specific RNA phages (FRNAPH) as a tool for evaluating fecal or viral contamination, especially in shellfish. In our case study, FRNAPH did not provide any benefits compared to E. coli as fecal pollution indicators in water but were found to be very useful in shellfish. Their concentrations in shellfish were higher than those found in the surrounding water, confirming bioaccumulation. This study also underlines a relationship between the presence of human norovirus genomes (HuNoVs) and those of FRNAPH subgroup II (FRNAPH-II). Considering that the two virus types have similar behaviors and since FRNAPH infectivity can be investigated, the specific detection of infectious FRNAPH-II could be regarded as an indication of the presence of infectious HuNoVs. The contribution of infectious human FRNAPH targeting for assessing the viral risk associated with HuNoVs in shellfish should thus be investigated.

Occurrence of and Sequence Variation among F-Specific RNA Bacteriophage Subgroups in Feces and Wastewater of Urban and Animal Origins.

F-specific RNA bacteriophages (FRNAPH) have been widely studied as tools for evaluating fecal or viral pollution in water. It has also been proposed that they can be used to differentiate human from animal fecal contamination. While FRNAPH subgroup I (FRNAPH-I) and FRNAPH-IV are often associated with animal pollution, FRNAPH-II and -III prevail in human wastewater. However, this distribution is not absolute, and variable survival rates in these subgroups lead to misinterpretation of the original distribution. In this context, we studied FRNAPH distribution in urban wastewater and animal feces/wastewater. To increase the specificity, we partially sequenced the genomes of phages of urban and animal origins. The persistence of the genomes and infectivity were also studied, over time in wastewater and during treatment, for each subgroup. FRNAPH-I genome sequences did not show any specific urban or animal clusters to allow development of molecular tools for differentiation. They were the most resistant and as such may be used as fecal or viral indicators. FRNAPH-II's low prevalence and low sequence variability in animal stools, combined with specific clusters formed by urban strains, allowed differentiation between urban and animal pollution by using a specific reverse transcription-PCR (RT-PCR) method. The subgroup's resistance over time was comparable to that of FRNAPH-I, but its surface properties allowed higher elimination rates during activated-sludge treatment. FRNAPH-III's low sequence variability in animal wastewater and specific cluster formation by urban strains also allowed differentiation by using a specific RT-PCR method. Nevertheless, its low resistance restricted it to being used only for recent urban pollution detection. FRNAPH-IV was too rare to be used.

Biocidal efficacy of monochloramine against planktonic and biofilm-associated Naegleria fowleri cells.

AIMS: Free-living amoebae (FLA) in aqueous systems are a problem for water network managers and health authorities because some are pathogenic, such as Naegleria fowleri, and they have also been reported to operate as reservoirs and vectors of several pathogenic bacteria. Therefore, to better control the occurrence of such amoebae, we evaluate the efficacy of monochloramine against planktonic forms (trophozoites and cysts) and also biofilm-associated cells of N. fowleri as FLA are often associated with biofilms. METHODS AND RESULTS: From a freshwater biofilm growing in a pilot reactor and inoculated with N. fowleri, we obtained Ct values ranging from 4 to 17 mg Cl2 min l(-1) at 25°C and pH 8·2 on both planktonic and biofilm associated cells. In addition, the inactivation pattern of biofilm associated was intermediate between those of trophozoïtes and cysts. CONCLUSIONS: The monochloramine efficiency varies with the life stage of N. fowleri (trophozoïte, cyst, and biofilm-associated). The sensitivity to disinfectant of amoeba, that is, trophozoïtes and cysts, in the biofilm life stage is as high as that of their planktonic cyst form. SIGNIFICANCE AND IMPACT OF THE STUDY: This study gives Ct values for cysts and biofilm-associated N. fowleri. This may impact on water treatment strategies against amoebae and should be considered when controlling N. fowleri in man-made water systems such as cooling towers or hot water systems.

5-HT(2B) receptors are required for serotonin-selective antidepressant actions.

The therapeutic effects induced by serotonin-selective reuptake inhibitor (SSRI) antidepressants are initially triggered by blocking the serotonin transporter and rely on long-term adaptations of pre- and post-synaptic receptors. We show here that long-term behavioral and neurogenic SSRI effects are abolished after either genetic or pharmacological inactivation of 5-HT(2B) receptors. Conversely, direct agonist stimulation of 5-HT(2B) receptors induces an SSRI-like response in behavioral and neurogenic assays. Moreover, the observation that (i) this receptor is expressed by raphe serotonergic neurons, (ii) the SSRI-induced increase in hippocampal extracellular serotonin concentration is strongly reduced in the absence of functional 5-HT(2B) receptors and (iii) a selective 5-HT(2B) agonist mimics SSRI responses, supports a positive regulation of serotonergic neurons by 5-HT(2B) receptors. The 5-HT(2B) receptor appears, therefore, to positively modulate serotonergic activity and to be required for the therapeutic actions of SSRIs. Consequently, the 5-HT(2B) receptor should be considered as a new tractable target in the combat against depression.

Unbiased counting of neurons in the cochlea of developing gerbils.

Accurate counting of neurons in the cochlea has a significant impact on the interpretation of research and clinically relevant data. However, reports of numbers of neurons in the spiral ganglion are widely variable across studies, even within the same species. We suggest that the implementation of a more standardized, unbiased counting method will improve the consistency and accuracy of neuron counts and will impact scientific interpretations. To test this view, we compared, in different ways, the numbers of neurons in the spiral ganglia of developing gerbils, previously reported to decrease by 22-27% between birth and age 7 days. Cochleae from gerbils, aged newborn, 7 days, 20 days, 1.5 years and 2.5 years were embedded in Araldite and serially sectioned at 5 µm. A computer based stereological method was used to unambiguously count every neuron in serial sections, either throughout the entire cochlea, or in a 100-µm segment of the cochlea. No significant changes in neuron numbers during cochlear maturation were found. We demonstrate that in methods using sampling of sections, the identity of the starting section and the interval between sections impacts the variability of the estimate of neuron numbers. In addition, we show that packing density differs between the newborn and seven-day old animals. The data demonstrate that variability in counting methods and the comparison of non-uniform samples can lead to neuron number estimates that show differences where none exist. We propose that a standardized counting protocol be implemented across studies and suggest possible approaches to different types of comparisons between neurons of spiral ganglia from different sources.

Liming as an advanced treatment for sludge sanitisation: helminth eggs elimination--Ascaris eggs as model.

The presence of helminth eggs (Ascaris eggs) in sewage sludge may constitute a sanitary risk when used as agricultural fertiliser. Sanitisation of sewage sludge can be achieved by treatment with quick lime, a process that destroys sludge pathogens in two ways: pH increase and temperature rise. Among the pathogens of epidemiological relevance, Ascaris eggs are the most resistant to liming, and, hence, may serve as indicators of hygienic quality of biosolids. This research aims at defining, between 50 degrees C and 60 degrees C, the time required in the case of limed sludge to obtain a product with a negligible level of viable Ascaris eggs. To achieve this objective, investigations on inactivation kinetics of Ascaris eggs were conducted in the following products: contaminated milk of lime; naturally contaminated sludge treated with slaked lime and heat; naturally contaminated sludge treated with quick lime; and sludge treated at full scale with quick lime. For the inactivation kinetics where a negligible level of Ascaris eggs was reached, the inactivation threshold was determined. Depending on the experimental situation, the inactivation threshold period was found to fluctuate between 5 and 75 min at 55 degrees C and between 1 and 8 min at 60 degrees C.

Parasite contamination of liquid sludge from urban wastewater treatment plants.

This study was performed on sludge samples from 20 wastewater treatment plants located in the north west of France with capacities of 1,000-20,000 inhabitant equivalents. The types of treatment studied were activated sludge low charge with and without denitrification. Respectively, 110 samples of fresh sludge and 84 samples of discharged sludge for spreading were analysed. Globally 78.6% of samples contained helminth eggs belonging to the cestodes (6.1%) and nematodes (93.9%). Most of the nematode eggs detected were viable with 135 positive samples. The distribution, according to genera, indicated a high prevalence of Toxocara eggs (77.4%) followed by Capillaria (13.2%), Trichuris (8.1%) and Ascaris (1.3%). For viable nematode eggs, the concentrations detected ranged from < 1 to 28/4 gDM for fresh sludge and from < 1 to 9.6/4 gDM for discharged sludge.

Irradiation of Ascaris ova in sludge using an electron beam accelerator.

The efficiency of sludge disinfection by irradiation was investigated using an electron beam accelerator, with the Ascaris ovum as a model. Ova suspensions prepared by worm dissection, immediately after preparation and after storage at 4 degrees C for 2 months were tested. Suspensions of ova extracted from slaughterhouse sludge were also tested. The ova were irradiated in sludge to determine, by probit analysis, the dose that inactivated 90% of viable ova. The D10 values obtained for irradiation of residual sludge contaminated with ova depended on the source of the ova, the D10 values were 788 +/- 172 Gy for suspensions of ova extracted from slaughterhouse sludge and 1125 +/- 145 Gy for suspensions freshly prepared by dissection. Ova suspensions freshly prepared by dissection were more proof against irradiation. Similarly, the D10 value was affected by storage: 1125 +/- 145 Gy for freshly produced ova suspensions and 661 +/- 45 Gy for suspensions of ova stored for 2 months at 4 degrees C in deionized water. The medium in which the ova were irradiated (deionized water or sludge) also affected D10 values, the indirect effects were smaller in samples of contaminated sludge, which were rich in organic matter, with the action of the radiation being mostly direct.

[Spinal reflexes in the determination of brain death]. / Odruchy rdzeniowe w przypadkach z rozpoznana smiercia mózgu.

The authors present the results of spinal cord function evaluation in organ donors by examination of reflexes. The knee reflex and ankle jerk, as well as abdominal reflex and foot withdrawal reaction were tested in 31 donors. At least one of the above was seen in 25 individuals. It is suggested on the basis of data obtained not to hamper the transplant procedure in cases of tested reflex persistency when brain death is revealed on relevant examination.