Nine-month-old infants update their predictive models of a changing environment.

Humans generate internal models of their environment to predict events in the world. As the environments change, our brains adjust to these changes by updating their internal models. Here, we investigated whether and how 9-month-old infants differentially update their models to represent a dynamic environment. Infants observed a predictable sequence of stimuli, which were interrupted by two types of cues. Following the update cue, the pattern was altered, thus, infants were expected to update their predictions for the upcoming stimuli. Because the pattern remained the same after the no-update cue, no subsequent updating was required. Infants showed an amplified negative central (Nc) response when the predictable sequence was interrupted. Late components such as the PSW were also evoked in response to unexpected stimuli; however, we found no evidence for a differential response to the informational value of surprising cues at later stages of processing. Infants rather learned that surprising cues always signal a change in the environment that requires updating. Interestingly, infants responded with an amplified neural response to the absence of an expected change, suggesting a top-down modulation of early sensory processing in infants. Our findings corroborate emerging evidence showing that infants build predictive models early in life.

Infants differentially update their internal models of a dynamic environment.

Unexpected events provide us with opportunities for learning about what to expect from the world around us. Using a saccadic-planning paradigm, we investigated whether and how infants and adults represent the statistics of a changing environment (i.e. build an internal model of the environment). Participants observed differently colored bees that appeared at an unexpected location every few trials. The color cues indicated whether the subsequent bees would appear at this new location (i.e. update trials) or at the same location as previously (i.e. no-update trials). Infants learned the predictive value of the color cues and updated their internal models when necessary. Unlike infants, adults had a tendency to update their models each time they observed a change in the structure. We argue that infants are open to learning from current evidence due to being less influenced by their prior knowledge. This is an advantageous learning strategy to form accurate representations in dynamic environments, which is fundamental for successful adaptation.

SQUID-detected FMR: Resonance in single crystalline and polycrystalline yttrium iron garnet.

Here two new techniques for the detection of broadband (100 MHz-20 GHz) ferromagnetic resonance (FMR)/ferrimagnetic resonance in single and poly-crystalline materials, which rely on SQUID-based gradiometry detection of small changes in the magnetisation, are developed. In the first method, small changes in the along-the-applied-field projection of the coupled magnetic moment (Δmz) are detected as the material is driven into resonance. Absolute measurement of the longitudinal component of the magnetisation and the resonance induced lowering of this moment makes estimation of the precession cone angle accessible, which is typically difficult to extract using conventional cavity or stripline based detection methods. The second method invokes the change in Δmz with the resonance-induced thermal heating dmzdT. Magnetisation dynamics in bulk Y3Fe5O12 are observed over a broad range of experimental temperatures (4 K-400 K) and fields (10-500 mT). The inhomogeneous microwave excitation allows for the observation of higher magnetostatic modes and the convenient tracking of very broad resonances. The two SQUID-detection techniques when combined with conventional broadband vector network analyser-FMR, low-frequency magnetic susceptibility, and DC magnetometry, all easily realised, essentially concurrently, using the same module, greatly expand the amount of static and dynamic information accessible.

A national evaluation of the management practices of acute diverticulitis.

INTRODUCTION: Diverticulitis is a common surgical admission that presents with a wide range of symptoms and severity. Overall there has been a shift to conservative management practices, including the consideration of non-antibiotic treatment approaches in select cases. METHODS: A national survey of all consultant surgeons evaluating their practices was performed. Reasons for changes in management, use of radiological imaging, role of non-antibiotic treatment approaches and indications for elective surgical management were evaluated. RESULTS: Response rate for this survey was 67.7% (n = 67/99). An overwhelming 92.5% stated that computed tomography imaging was routinely used to investigate acute presentations. Interestingly, 22.4% stated they would consider a non-antibiotic treatment approach in uncomplicated diverticulitis. Main reasons for adopting this approach was low inflammatory markers with short duration of symptoms. Co-amoxiclav was the most common antibiotic used for acute diverticulitis, with considerable variability in duration of treatment. Additionally, there was considerable heterogeneity regarding how many recurrences were necessary before surgical management was required. CONCLUSION: This review highlights substantial variation in the management of diverticulitis across Ireland. Shifts to non-antibiotic treatment approaches for uncomplicated cases are observed, but less so than in Northern Europe. National guidelines are required to establish uniform treatment protocols including indications for surgical resection.

Systematic chemical and molecular profiling of MLL-rearranged infant acute lymphoblastic leukemia reveals efficacy of romidepsin.

To address the poor prognosis of mixed lineage leukemia (MLL)-rearranged infant acute lymphoblastic leukemia (iALL), we generated a panel of cell lines from primary patient samples and investigated cytotoxic responses to contemporary and novel Food and Drug Administration-approved chemotherapeutics. To characterize representation of primary disease within cell lines, molecular features were compared using RNA-sequencing and cytogenetics. High-throughput screening revealed variable efficacy of currently used drugs, however identified consistent efficacy of three novel drug classes: proteasome inhibitors, histone deacetylase inhibitors and cyclin-dependent kinase inhibitors. Gene expression of drug targets was highly reproducible comparing iALL cell lines to matched primary specimens. Histone deacetylase inhibitors, including romidepsin (ROM), enhanced the activity of a key component of iALL therapy, cytarabine (ARAC) in vitro and combined administration of ROM and ARAC to xenografted mice further reduced leukemia burden. Molecular studies showed that ROM reduces expression of cytidine deaminase, an enzyme involved in ARAC deactivation, and enhances the DNA damage-response to ARAC. In conclusion, we present a valuable resource for drug discovery, including the first systematic analysis of transcriptome reproducibility in vitro, and have identified ROM as a promising therapeutic for MLL-rearranged iALL.

Maternal depressive symptoms during pregnancy, placental expression of genes regulating glucocorticoid and serotonin function and infant regulatory behaviors.

BACKGROUND: Glucocorticoids and serotonin may mediate the link between maternal environment, fetal brain development and 'programming' of offspring behaviors. The placenta regulates fetal exposure to maternal hormonal signals in animal studies, but few data address this in humans. We measured prospectively maternal depressive symptoms during pregnancy and mRNAs encoding key gene products determining glucocorticoid and serotonin function in term human placenta and explored associations with infant regulatory behaviors. METHOD: Bi-weekly self-ratings of the Center for Epidemiologic Studies Depression Scale from 12th to 13th gestational week onwards and term placental mRNAs of 11beta-hydroxysteroid dehydrogenase type 2 (HSD2B11), type 1 (HSD1B11), glucocorticoid (NR3C1), mineralocorticoid receptors (NR3C2) and serotonin transporter (SLC6A4) were obtained from 54 healthy mothers aged 32.2 ± 5.3 years with singleton pregnancies and without pregnancy complications. Infant regulatory behaviors (crying, feeding, spitting, elimination, sleeping and predictability) were mother-rated at 15.6 ± 4.2 days. RESULTS: Higher placental mRNA levels of HSD2B11 [0.41 standard deviation (s.d.) unit increase per s.d. unit increase; 95% confidence interval (CI) 0.13-0.69, p = 0.005], HSD1B11 (0.30, 0.03-0.57, p = 0.03), NR3C1 (0.44, 0.19-0.68, p = 0.001) and SLC6A4 (0.26, 0.00-0.53, p = 0.05) were associated with more regulatory behavioral challenges of the infant. Higher placental NR3C1 mRNA partly mediated the association between maternal depressive symptoms during pregnancy and infant regulatory behaviors (p < 0.05). CONCLUSIONS: Higher placental expression of genes regulating feto-placental glucocorticoid and serotonin exposure is characteristic of infants with more regulatory behavioral challenges. Maternal depression acts, at least partly, via altering glucocorticoid action in the placenta to impact on offspring regulatory behaviors.

Maternal depressive symptoms throughout pregnancy are associated with increased placental glucocorticoid sensitivity.

BACKGROUND: Maternal prenatal depression predicts post-partum depression and increases risk of prematurity and low birth weight. These effects may be mediated by altered placental function. We hypothesized that placental function would be influenced by the gestational week of experiencing depressive symptoms and aimed to examine associations between maternal depressive symptoms during pregnancy and placental expression of genes involved in glucocorticoid and serotonin transfer between mother and fetus. METHOD: We studied women participating in a prospective pregnancy cohort: the Prediction and Prevention of Preeclampsia (PREDO) Study, Helsinki, Finland. Maternal depressive symptoms were assessed at 2-week intervals throughout pregnancy in 56 healthy women with singleton, term pregnancies. Messenger ribonucleic acid (mRNA) levels of glucocorticoid (GR) and mineralocorticoid (MR) receptors and serotonin transporter (SLC6A4), 11ß-hydroxysteroid dehydrogenase type 1 (HSD1) and 2 (HSD2) were quantified in placental biopsies. RESULTS: In adjusted analyses women who reported higher depressive symptoms across the whole pregnancy had higher mRNA levels of GR [effect size 0.31 s.d. units, 95% confidence interval (CI) 0.01-0.60, p = 0.042] and MR (effect size 0.34 s.d. units, 95% CI 0.01-0.68, p = 0.047). These effects were significant for symptoms experienced in the third trimester of pregnancy for GR; findings for MR were also significant for symptoms experienced in the second trimester. GR and MR mRNA levels increased linearly by having the trimester-specific depressive symptoms scores 0, 1 or 2-3 times above the clinical cut-off for depression (p = 0.003, p = 0.049, respectively, and p = 0.004, p = 0.15 in adjusted analyses). CONCLUSIONS: Our findings offer potential gestational-age-specific mechanisms linking maternal depressive symptoms during pregnancy via placental biology. Future studies will test whether these also link with adverse offspring outcomes.

Patient classification and hospital reimbursement for inguinal hernia repair: a comparison across 11 European countries.

PURPOSE: This comparative study examines the categorisation of patients undergoing surgical repair of inguinal hernia in the diagnosis-related group (DRG) systems of 11 European countries (Austria, England, Estonia, Finland, France, Germany, Ireland, the Netherlands, Poland, Spain and Sweden). Understanding the design and operation of DRG systems for this common surgical procedure is important, given their increasing use internationally for hospital reimbursement and performance measurement. METHODS: A common definition was used to identify inguinal hernia patients and the corresponding data were extracted from national databases. The analysis compared the variables and algorithms for classifying these patients to DRGs across the participating countries, as well as the number, composition and relative resource intensity of groups. An index case and six standardised vignettes were grouped using each country's DRG system and the associated quasi-prices were calculated. RESULTS: The number of groups to which inguinal hernia patients are assigned is typically three or four, but ranges from two in Poland to ten in France. In most systems, categorising patients is contingent on procedure, principal and secondary diagnoses, and age, with treatment setting (day case/inpatient) being less common. Added to these, the French system also incorporates length of stay and whether the patient died. More resource intensive DRGs generally contained patients who were older, treated as inpatients, did not die, had (more severe) complications and/or co-morbidities, and/or underwent laparoscopic repair. There are cross-country disparities in day case rates and the use of laparoscopic repairs. CONCLUSIONS: The categorisation of inguinal hernia patients varies across the 11 European DRG systems under study. By highlighting the main differences across these systems, this comparative analysis allows the relevant decision makers to assess the adequacy and specificity of their own DRG systems.

Altered maternal hypothalamic-pituitary-adrenal axis activity in obese pregnancy is associated with macrosomia and prolonged pregnancy.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) axis is important for fetal growth and timing of parturition. Maternal obesity is associated with macrosomia (birthweight ⩾4000g) and prolonged pregnancy (⩾41weeks). We aimed to characterise HPA axis hormones in obese pregnancy and to test associations with these pregnancy outcomes. METHOD: Fasting cortisol was measured by radioimmunoassay in venous blood at 16, 28 and 36 weeks of gestation in 286 obese (BMI 44.05±3.98kg/m(2)) and 137 lean (BMI 22.71±1.66kg/m(2)) pregnant women. In subsets (n=20 obese, 20 lean) we measured corticosteroid binding globulin (CBG) and CRH by radioimmunoassay; progesterone, estradiol (E2), estriol (E3) and sex-hormone-binding-globulin (SHBG) by ELISA; and albumin by bromocresol green binding. Free cortisol levels were calculated using Coolen's equation. RESULTS: Cortisol, CBG, calculated free cortisol, CRH, E2, E3, progesterone and SHBG levels rose similarly during pregnancy in obese and lean, but were significantly lower in obese (p<0.05). In obese, lower free cortisol at 16 weeks was associated with higher birthweight (r=-0.46, p<0.05). Cortisol was not associated with labour onset. CRH was significantly lower at 36 weeks in women who delivered at ⩾41weeks and in women with macrosomic babies (p<0.05); and correlated negatively with gestation at delivery in obese (r=-0.557, p<0.05). CONCLUSION: Our findings suggest that decreased HPA axis activity in obese pregnancy may be a mechanism underlying macrosomia and prolonged pregnancy.

Acute myeloid leukaemia in Western Australia 1991-2005: a retrospective population-based study of 898 patients regarding epidemiology, cytogenetics, treatment and outcome.

BACKGROUND: Patient characteristics and cytogenetics of acute myeloid leukaemia (AML) in clinical trials do not reflect that of the general population. There has not been a large population-based study that has examined cytogenetic features and outcomes of AML in Australia. AIM: Investigation of epidemiological, prognostic, treatment and outcome data in adults diagnosed with AML in Western Australia between 1991 and 2005. METHODS: Patients were identified utilising the Western Australia Cancer Registry, cytogenetic databases and hospital inpatient discharge diagnoses. Data were retrospectively collected from patients presenting to tertiary hospitals on patient characteristics, karyotype, induction therapy, remission, transplantation and survival. RESULTS: A total of 987 patients with AML was identified, of which 91% (898) attended a tertiary hospital. Median age was 67 years and 45% of cases represented secondary AML. Cytogenetic analysis was available in 81% of patients. Frequent karyotypes were normal (38.8%), complex (13.8%) and -7/add(7q)/del(7q) (12.1%). Aggressive therapy was initiated in 62.6%. Less than 15% were enrolled in clinical trials. Overall 16.5% received a stem cell transplant. Median overall survival for all patients was 5.6 months. In patients treated aggressively, complete remission was achieved in 56.9% and median overall survival was 12.2 months. Age, secondary disease and karyotype were significantly predictive of remission and overall survival. CONCLUSION: Age distribution, remission and survival rates were comparable with published population-based studies. High median age was reflected in the rate of secondary AML and trial eligibility. These findings highlight the need for prospective data collection.

Social network size affects neural circuits in macaques.

It has been suggested that variation in brain structure correlates with the sizes of individuals' social networks. Whether variation in social network size causes variation in brain structure, however, is unknown. To address this question, we neuroimaged 23 monkeys that had been living in social groups set to different sizes. Subject comparison revealed that living in larger groups caused increases in gray matter in mid-superior temporal sulcus and rostral prefrontal cortex and increased coupling of activity in frontal and temporal cortex. Social network size, therefore, contributes to changes both in brain structure and function. The changes have potential implications for an animal's success in a social context; gray matter differences in similar areas were also correlated with each animal's dominance within its social network.

Risk Factors and Seroprevalence of Hepatitis C among Patients Hospitalized at Mulago Hospital, Uganda.

The emergence of hepatitis C virus (HCV) and its associated sequelae in Africa is a cause for significant concern. Human immunodeficiency virus (HIV) positive patients are at an increased risk of contracting HCV infection due to similar risk factors and modes of transmission. We investigated the seroprevalence of hepatitis C in hospitalized HIV-positive and HIV-negative patients in Mulago Hospital, an academic hospital in Uganda. Blood samples were first tested for HCV antibodies, and positive tests were confirmed with HCV RNA PCR. We enrolled five hundred patients, half HIV-positive and half HIV negative. Overall, 13/500 patients (2.6%) tested positive for HCV antibodies. There was no difference in HCV antibody detection among HIV-positive and HIV-negative patients. Out of all risk factors examined, only an age greater than 50 years was associated with HCV infection. Traditional risk factors for concurrent HIV and HCV transmission, such as intravenous drug use, were exceedingly rare in Uganda. Only 3 of 13 patients with detectable HCV antibodies were confirmed by HCV RNA detection. This result concurs with recent studies noting poor performance of HCV antibody testing when using African sera. These tests should be validated in the local population before implementation.

A metaproteomic approach gives functional insights into anaerobic digestion.

AIMS: The objective of this work was to provide functional evidence of key metabolic pathways important for anaerobic digestion processes through the identification of highly expressed proteins in a mixed anaerobic microbial consortium. METHODS AND RESULTS: The microbial communities from an anaerobic industrial-like wastewater treatment bioreactor were characterized using phylogenetic analyses and metaproteomics. Clone libraries indicated that the bacterial community in the bioreactor was diverse while the archaeal population was mainly composed of Methanocorpusculum-like (76%) micro-organisms. Three hundred and eighty-eight reproducible protein spots were obtained on 2-D gels, of which 70 were excised and 33 were identified. The putative functions of the proteins detected in the anaerobic bioreactor were related to cellular processes, including methanogenesis from CO(2) and acetate, glycolysis and the pentose phosphate pathway. Metaproteomics also indicated, by protein assignment, the presence of specific micro-organisms in the bioreactor. However, only a limited overlap was observed between the phylogenetic and metaproteomic analyses. CONCLUSIONS: This study provides some direct evidence of the microbial activities taking place during anaerobic digestion. SIGNIFICANCE AND IMPACT OF STUDY: This study demonstrates metaproteomics as a useful tool to uncover key biochemical pathways underpinning specific anaerobic bioprocesses.

210Pb-dating of a lake sediment core from Lough Carra (Co. Mayo, western Ireland): use of paleolimnological data for chronology validation below the 210Pb dating horizon.

The chronologies and sediment accumulation rates for a lake sediment sequence from Lough Carra (Co. Mayo, western Ireland) were established by applying the constant initial concentration (CIC) and constant rate of supply (CRS) hypotheses to the measured (210)Pb(excess) profile. The resulting chronologies were validated using the artificial fallout radionuclides (137)Cs and (241)Am, which provide independent chronostratigraphic markers for the second half of the 20th century. The validity of extrapolating the derived CIC and CRS dates below the (210)Pb dating horizon using average sedimentation rates was investigated using supplementary paleolimnological information and historical data. Our data confirm that such an extrapolation is well justified at sites characterised by relatively stable sedimentation conditions.

Nutritional intervention during gestation alters growth, body composition and gene expression patterns in skeletal muscle of pig offspring.

Variations in maternal nutrition during gestation can influence foetal growth, foetal development and permanently 'programme' offspring for postnatal life. The objective of this study was to analyse the effect of increased maternal nutrition during different gestation time windows on offspring growth, carcass quality, meat quality and gene expression in skeletal muscle. A total of 64 sows were assigned to the following feeding treatments: a standard control diet at a feed allocation of 2.3 kg/day throughout gestation, increased feed allowance of 4.6 kg/day from 25 to 50 days of gestation (dg), from 50 to 80 dg and from 25 to 80 dg. At weaning, Light, Medium and Heavy pigs of the same gender, within litter, were selected based on birth weight, individually penned and monitored until slaughter at 130 days post weaning. Carcass and meat quality traits of the semimembranosus (SM) muscle were recorded post mortem. A cross section of the semitendinosus (ST) muscle encompassing the deep and superficial regions were harvested from pigs (n = 18 per treatment) for RNA extraction and quantification of gene expression by real-time PCR. The results showed that doubling the feed intake from 25 to 50 dg reduced offspring growth, carcass weight, intramuscular fat content and increased drip loss of the SM muscle. Interestingly, protein phosphatase 3 catalytic subunit - α-isoform, which codes for the transcription factor calcineurin, was upregulated in the ST muscle of offspring whose mothers received increased feed allowance from 25 to 50 dg. This may provide an explanation for the previous observed increases in Type IIa muscle fibres of these offspring. Increasing the maternal feed intake from 50 to 80 dg negatively impacted pig growth and carcass weight, but produced leaner male pigs. Extending the increased maternal feed intake from 25 to 80 dg had no effect on offspring over the standard control gestation diet. Although intra-litter variation in pig weight is a problem for pig producers, increased maternal feeding offered no improvement throughout life to the lighter birth weight littermates in our study. Indeed, increased maternal nutrition at the three-gestation time windows selected provided no major benefits to the offspring.

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina.

Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 to 357 µg l(-1) As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 to 1326 µg l(-1) As. The pH range for the provinces of San Juan (7.2-9.7) and La Pampa (7.0-9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (>2,600 µS cm(-1)) and TDS (>1,400 mg l(-1)). Reverse osmosis (RO) treatment of well waters in La Pampa for domestic drinking water in EC and LU significantly reduced total arsenic concentrations from a range of 216-224 µg l(-1) As to 0.3-0.8 µg l(-1) As. Arsenic species for both provinces were predominantly As(III) and As(V). As(III) and As(V) concentrations in San Juan ranged from 4-138 µg l(-1) to <0.02-22 µg l(-1) for surface waters (in the San José de Jáchal region) and 23-346 µg l(-1) and 0.04-76 µg l(-1) for groundwater, respectively. This translates to a relative As(III) abundance of 69-100% of the total arsenic in surface waters and 32-100% in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As(V). However, data from the SPE methodology suggests that As(III) is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As(III) and As(V) concentrations of 5-1,332 µg l(-1) and 0.09-592 µg l(-1) for EC and 32-242 µg l(-1) and 30-277 µg l(-1) As for LU, respectively. Detectable levels of MA(V) were reported in both provinces up to a concentration of 79 µg l(-1) (equating to up to 33% of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in situ arsenic speciation in water supplies is discussed.

Field based speciation of arsenic in UK and Argentinean water samples.

A field method is reported for the speciation of arsenic in water samples that is simple, rapid, safe to use beyond laboratory environments, and cost effective. The method utilises solid-phase extraction cartridges (SPE) in series for selective retention of arsenic species, followed by elution and measurement of eluted fractions by inductively coupled plasma mass spectrometry (ICP-MS) for "total" arsenic. The method is suitable for on-site separation and preservation of arsenic species from water. Mean percentage accuracies (n = 25) for synthetic solutions of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA), and dimethylarsinic acid (DMA) containing 10 µg l(-1) As, were 98, 101, 94, and 105%, respectively. Data are presented to demonstrate the effect of pH and competing anions on the retention of the arsenic species. The cartridges were tested in the UK and Argentina at sites where arsenic was known to be present in surface and groundwaters, respectively, at elevated concentrations and under challenging matrix conditions. In Argentinean groundwater, 4-20% of speciated arsenic was present as MA and 20-73% as As(III). In UK surface waters, speciated arsenic was measured as 7-49% MA and 12-42% DMA. Comparative data from the field method using SPE cartridges and the laboratory method using liquid chromatography coupled to ICP-MS for all water samples provided a correlation of greater than 0.999 for As(III) and DMA, 0.991 for MA, and 0.982 for As(V) (P < 0.01).

Cultivation of low-temperature (15 degrees C), anaerobic, wastewater treatment granules.

AIMS: Anaerobic sludge granules underpin high-rate waste-to-energy bioreactors. Granulation is a microbiological phenomenon involving the self-immobilization of several trophic groups. Low-temperature anaerobic digestion of wastes is of intense interest because of the economic advantages of unheated bioenergy production technologies. However, low-temperature granulation of anaerobic sludge has not yet been demonstrated. The aims of this study were to (i) investigate the feasibility of anaerobic sludge granulation in cold (15 degrees C) bioreactors and (ii) observe the development of methanogenic activity and microbial community structure in developing cold granules. METHODS AND RESULTS: One mesophilic (R1; 37 degrees C) and two low-temperature (R2 and R3, 15 degrees C) laboratory-scale, expanded granular sludge bed bioreactors were seeded with crushed (diameter <0.4 mm) granules and were fed a glucose-based wastewater for 194 days. Bioreactor performance was assessed by chemical oxygen demand removal, biogas production, granule growth and temporal methanogenic activity. Granulation was observed in R2 and R3 (up to 33% of the sludge). Elevated hydrogenotrophic methanogenesis was observed in psychrophilically cultivated biomass, but acetoclastic methanogenic activity was also retained. Denaturing gradient gel electrophoresis of archaeal 16S rRNA gene fragments indicated that a distinct community was associated with developing and mature granules in the low-temperature (LT) bioreactors. CONCLUSIONS: Granulation was observed at 15 degrees C in anaerobic bioreactors and was associated with H(2)/CO(2)-mediated methanogenesis and distinct community structure development. SIGNIFICANCE AND IMPACT OF THE STUDY: Granulation underpins high-rate anaerobic waste treatment bioreactors. Most LT bioreactor trials have employed mesophilic seed sludge, and granulation <20 degrees C was not previously documented.