Ecological and evolutionary genomics of marine photosynthetic organisms

Environmental (ecological) genomics aims to understand the genetic basis of relationships between organisms and their abiotic and biotic environments. It is a rapidly progressing field of research largely due to recent advances in the speed and volume of genomic data being produced by next generation sequencing (NGS) technologies. Building on information generated by NGS-based approaches, functional genomic methodologies are being applied to identify and characterize genes and gene systems of both environmental and evolutionary relevance. Marine photosynthetic organisms (MPOs) were poorly represented amongst the early genomic models, but this situation is changing rapidly. Here we provide an overview of the recent advances in the application of ecological genomic approaches to both prokaryotic and eukaryotic MPOs. We describe how these approaches are being used to explore the biology and ecology of marine cyanobacteria and algae, particularly with regard to their functions in a broad range of marine ecosystems. Specifically, we review the ecological and evolutionary insights gained from whole genome and transcriptome sequencing projects applied to MPOs and illustrate how their genomes are yielding information on the specific features of these organisms.

Occurrence of the toxic dinoflagellate Ostreopsis cf. ovata in relation with environmental factors in Monaco (NW Mediterranean)

To study environment characteristics favoring the toxic benthic dinoflagellate Ostreopsis cf. ovata, a survey was conducted in Monaco (NW Mediterranean Sea), in summers 2007 and 2008. Epiphytic and planktonic blooms occurred almost simultaneously and a high variation of abundances at low spatial scales was observed. An early and very marked bloom occurred in 2007, compared to a later and less abundant development in 2008. These distinct patterns in bloom timing corresponded with very different hydroclimatic scenarios in 2007 (hot spring and relatively cold summer) and 2008 (standard year compared to the median year profile estimated with data from 1995 to 2008). No clear impacts of summer seawater temperature, rainfall or nutrient concentrations were evident. Strong wind may favor the dispersal of benthic and planktonic cells. Our study suggests that further investigations are needed to examine the potential role of Ostreopsis nutritional mode (i.e. autotrophy vs. mixotrophy).

Vancomycin prescription in neonates and young infants: toward a simplified dosage

BACKGROUND

There is no consensus on vancomycin dosing in newborns and young infants.

OBJECTIVE

The first objective was to assess the efficiency of a simplified dosing regimen with a cohort study. The secondary objective was to examine pharmacokinetic data to determine how this simplified dosing could be improved.

METHODS

All neonates admitted to our intensive care unit and treated with vancomycin were included in the pharmacokinetic study (PK group, 83 treatments, 156 measurements). The vancomycin dosing regimen consisted of a loading dose of 7 mg/kg, followed by a constant continuous dose of 30 mg/kg/day. The target serum vancomycin concentration ranged from 10 mg/l to 30 mg/l. Data from patients whose medications followed the scheduled dosing without modifications or prescription errors (actual dosing group: 62 treatments, 108 measurements) were analysed separately. A population pharmacokinetic analysis was performed (PK group) to simulate several vancomycin dosings.

RESULTS

Prescription errors were found in 10 of 83 treatments (12%). In the actual dosing group, 89.2% of vancomycin measurements were within the target range. Serum creatinine remained stable throughout treatment. Vancomycin concentrations varied widely. The modified regimen for a target vancomycin concentration of 25 mg/l consisted of a bolus of 20 mg/kg followed by continuous infusion of 30 mg/kg.

CONCLUSION

Our pharmacokinetic data and bedside results suggest that a simplified schedule of vancomycin can achieve the targeted drug concentrations in most patients while avoiding secondary renal toxicity. The proposed new dosing scheme should be validated in a drug survey, but due to pharmacokinetic variability, still requires therapeutic drug monitoring.

[Multinodular hepatopathy with fever in a tropical climate: hepatic amebiasis with multiple abscesses]

Hepatic amebiasis is common in tropical zones. Solitary abscess is the classical form but multinodular presentation does not rule out amebiasis as the underlying cause. Definitive diagnosis cannot be based on clinical and radiologic findings alone. Serological testing for amebiasis is necessary. In zones where serology is unavailable, response to presumptive metronidazole treatment is still a useful for diagnosis.

Menopausal hormone therapy and new-onset diabetes in the French Etude Epidemiologique de Femmes de la Mutuelle Générale de l'Education Nationale (E3N) cohort

AIMS/HYPOTHESIS

Two US randomised trials found a lower incidence of type 2 diabetes in women treated by menopausal hormone therapy (MHT) with oral conjugated equine oestrogen combined with medroxyprogesterone acetate. The purpose of this study was to evaluate the influence of various MHTs, according to their formulation and route of administration, on new-onset diabetes in a cohort of postmenopausal French women.

METHODS

The association between MHT use and new-onset diabetes was investigated by Cox regression analysis in 63,624 postmenopausal women in the prospective French cohort of the Etude Epidemiologique de Femmes de la Mutuelle Générale de l'Education Nationale (E3N). Cases of diabetes were identified through self-reporting or drug-reimbursement record linkage, and further validated.

RESULTS

1,220 new-onset diabetes cases were validated. We observed a lower risk of new-onset diabetes among women who had ever used MHT (HR 0.82 [95% CI 0.72-0.93]), compared with those who had never used MHT. Adjustment for BMI during follow-up (rather than according to baseline BMI) did not substantially modify this association. An oral route of oestrogen administration was associated with a greater decrease in diabetes risk than a cutaneous route (HR 0.68 [95% CI 0.55-0.85] vs 0.87 [95% CI 0.75-1.00], p for homogeneity = 0.028). We were not able to show significant differences between the progestagens used in combined MHT.

CONCLUSIONS/INTERPRETATION

Use of MHT appeared to be associated with a lower risk of new-onset diabetes. This relationship was not mediated by changes in BMI. Further studies are needed to confirm the stronger effect of oral administration of oestrogen compared with cutaneous administration.

Effects of Three‐Hour Restricted Food Access during the Light Period on Circadian Rhythms of Temperature, Locomotor Activity, and Heart Rate in Rats

The effects of food on biological rhythms may influence the findings of chronopharmacological studies. The present study evaluated the influence of a restricted food access during the rest (light) span of nocturnally active Wistar rats on the 24 h time organization of biological functions in terms of the circadian rhythms of temperature (T), heart rate (HR), and locomotor activity (LA) in preparation for subsequent studies aimed at evaluating the influence of timed food access on the pharmacokinetics and pharmacodynamics of medications. Ten-wk-old male Wistar rats were housed under controlled 12:12 h light:dark (LD) environmental conditions. Food and water were available ad libitum, excepted during a 3 wk period of restriction. Radiotelemetry transmitters were implanted to record daily rhythms in T, HR, and LA. The study lasted 7 wk and began after a 21-d recovery span following surgery. Control baseline data were collected during the first wk (W1). The second span of 3 wk duration (W2 to W4) consisted of the restricted feeding regimen (only 3 h access to food between 11:00 and 14:00 h daily) during the L (rest span) under 12:12 h LD conditions. The third period of 3 wk duration (W5 to W7) consisted of the recovery span with ad libitium normal feeding. Weight loss in the amount of 5% of baseline was observed during W1 with stabilization of body weight thereafter during the remaining 2 wk of food restriction. The 3 h restricted food access during the L rest span induced a partial loss of circadian rhythmicity and the emergence of 12 h rhythms in T, HR, and LA. Return to ad libitum feeding conditions restored circadian rhythmicity in the manner evidenced during the baseline control span. Moreover, the MESORS and amplitudes of the T, HR, and LA 24 h patterns were significantly attenuated during food restriction (p < 0.001) and then returned to initial values during recovery. These changes may be interpreted as a masking effect, since T, HR, and LA are known to directly react to food intake. The consequences of such findings on the methods used to conduct chronokinetic studies, such as the fasting of animals the day before testing, are important since they may alter the temporal structure of the organism receiving the drug and thereby compromise findings.