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Understanding the conditions of dissolved organic matter (DOM) release from thawing peat in the Arctic regions and identifying the pathways of processing DOM by soil and aquatic heterotrophic bacteria are critical in the context of rapid climate change. Until now, experimental approaches did not allow quantitative predictions of temperature and biota effects on carbon release from peat in permafrost-affected aquatic environments. In this study, we incubated frozen peat and its aqueous leachate at various temperatures (4, 25 or 45°C), with and without culturable heterotrophic bacteria Iodobacter sp., extracted from thermokarst lakes, to quantify the release and the removal rate of organic carbon (OC) with time. The metabolic diversity of the native microbial community associated with the substrates involved in OC processing was also characterized. Transmission electron microscopy revealed that, after degradation, the associated bacteria are mostly located in the inner parts of plant cells, and that the degradation of organic matter around bacteria is more pronounced at 4 and 25°C compared to 45°C. The metabolic diversity of heterotrophic bacteria was equally high at 4 and 25°C, but lower at 45°C. Regardless of the microbial consortium (native community alone or with added culturable heterotrophs), both the OC release from peat and the OC removal from peat leachate by bacteria were similar at 4 and 25°C. Very low apparent activation energies of DOM biodegradation between 4 and 25°C (−4.23 ± 12.3 kJ mol − 1) suggest that the short-period of surface water warming in summer would have an insignificant effect on DOM microbial processing. Such duration (1-3 weeks) is comparable with the water residence time in peat depressions and permafrost subsidences, where peat degradation and DOM microbial processing occur. This questions the current paradigm of a drastic effect of temperature rise on organic carbon release from frozen peatlands, and should be considered for modelling short-term climate impacts in these regions.

Objective: To evaluate whether prophylactic administration of 200 mg vaginal progesterone can reduce the incidence of preterm birth in women with documented history of preterm birth <37 weeks of gestation or not. Setting: Obstetrics and Gynecology Department, Zagazig University Hospital, Egypt. Methods: Ninety patients with previous history of preterm birth prior to 37 week presenting with singleton pregnancy between 20 -24 weeks were randomly allocated to receive either the progesterone 200 mg vaginal suppository or no treatment. Results: The incidence of preterm labor before 37 weeks of gestation was significantly lower in the study group than in the control group (22.2% vs. 53.3%) especially in earlier gestational ages. While, the mean birth weight was significantly higher in the study group than in control group (2872.67 ± 565.76 gm vs. 2487.78 ± 742.40 gm). The neonatal morbidities and mortality associated with preterm labor were significantly lower in the study group than in the control group as shown by lower incidence of neonatal RDS (13.3% vs. 31.1%; P = 0.043) and lower incidence of the need for NICU admission (15.6% vs. 35.5%; P = 0.03). Conclusion: Administration of prophylactic vaginal progesterone (200 mg, daily) can significantly reduce the rate of preterm birth before 37, 32 and 28 wks of gestation among women with previous spontaneous preterm birth. In addition, the rates of RDS and admission to NICU were significantly decreased among infants of women assigned to progesterone treatment. Also, there was an additional benefit of vaginal progesterone for prevention of preterm birth in women who had prior spontaneous preterm birth and cervical length < 25 mm.