Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
2.
Cardiol Young ; 34(3): 483-488, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37466015

RESUMEN

OBJECTIVE: To determine the prevalence and timing of autism spectrum disorder diagnosis in a cohort of congenital heart disease (CHD) patients receiving neurodevelopmental follow-up and identify associated risk factors. METHOD: Retrospective single-centre observational study of 361 children undergoing surgery for CHD during the first 6 months of life. Data abstracted included age at autism spectrum disorder diagnosis, child and maternal demographics, and medical history. RESULTS: Autism spectrum disorder was present in 9.1% of children with CHD, with a median age at diagnosis of 34 months and 87.9% male. Prematurity, history of post-operative extracorporeal membrane oxygenation, and seizures were higher among those with autism (p = 0.013, p = 0.023, p = 0.001, respectively). Infants with autism spectrum disorder were older at the time of surgery (54 days vs 13.5 days, p = 0.002), and infants with surgery at ≥ 30 days of age had an increased risk of autism spectrum disorder (OR 2.31; 95% CI =1.12, 4.77, p = 0.023). On multivariate logistic regression analysis, being male (OR 4.85, p = 0.005), surgery ≥ 30 days (OR 2.46, p = 0.025), extracorporeal membrane oxygenation (OR 4.91, p = 0.024), and seizures (OR 4.32, p = 0.003) remained associated with increased odds for autism spectrum disorder. Maternal age, race, ethnicity, and surgical complexity were not associated. CONCLUSIONS: Children with CHD in our cohort had more than three times the risk of autism spectrum disorder and were diagnosed at a much earlier age compared to the general population. Several factors (male, surgery at ≥ 30 days, post-operative extracorporeal membrane oxygenation, and seizures) were associated with increased odds of autism. These findings support the importance of offering neurodevelopmental follow-up after cardiac surgery in infancy.


Asunto(s)
Trastorno del Espectro Autista , Cardiopatías Congénitas , Niño , Lactante , Humanos , Masculino , Femenino , Trastorno del Espectro Autista/complicaciones , Trastorno del Espectro Autista/diagnóstico , Trastorno del Espectro Autista/epidemiología , Estudios Retrospectivos , Cardiopatías Congénitas/complicaciones , Cardiopatías Congénitas/epidemiología , Cardiopatías Congénitas/cirugía , Factores de Riesgo , Convulsiones
3.
J Autism Dev Disord ; 2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37581718

RESUMEN

In the current study, we examined adaptive skills and trajectories over time in 257 individuals with Angelman syndrome (AS) using the Vineland Adaptive Behavior Scales, 2nd Edition. Multilevel linear models were used to examine differences between molecular subtypes over time, from one year to 13 years of age, in the adaptive domains of communication, daily living skills, socialization and motor skills. Individuals with non-deletion subtypes typically demonstrated a higher level of adaptive skills compared to those with deletion subtypes. Statistically significant growth was observed in all adaptive domains through at least early adolescence. Individuals with AS should continue to receive developmental services and educational supports through adolescence and into adulthood given the slow rates of growth being observed across adaptive domains.

4.
J Autism Dev Disord ; 53(2): 720-737, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33517526

RESUMEN

We describe the development of 236 children with Angelman syndrome (AS) using the Bayley Scales of Infant and Toddler Development, Third Edition. Multilevel linear mixed modeling approaches were used to explore differences between molecular subtypes and over time. Individuals with AS continue to make slow gains in development through at least age 12 years of age at about 1-2 months/year based on age equivalent score and 1-16 growth score points/year depending on molecular subtype and domain. Children with a deletion have lower scores at baseline and slower rate of gaining skills while children with UBE3A variant subtype demonstrated higher scores as well as greater rates of skill attainment in all domains. The developmental profiles of UPD and ImpD were similar.


Asunto(s)
Síndrome de Angelman , Trastorno del Espectro Autista , Lactante , Niño , Humanos , Discapacidades del Desarrollo/diagnóstico , Destreza Motora , Síndrome de Angelman/diagnóstico , Síndrome de Angelman/genética , Desarrollo Infantil
5.
Ann Thorac Surg ; 114(6): 2347-2354, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35346625

RESUMEN

BACKGROUND: Infants who undergo surgery for congenital heart disease are at risk of neurodevelopmental delay. Cardiac surgery-associated acute kidney injury (CS-AKI) is common but its association with neurodevelopment has not been explored. METHODS: This was a single-center retrospective observational study of infants who underwent cardiac surgery in the first year of life who had neurodevelopmental testing using the Bayley Scale for Infant Development, third edition. Single and recurrent episodes of stages 2 and 3 CS-AKI were determined. RESULTS: Of 203 children with median age at first surgery of 12 days, 31% had one or more episodes of severe CS-AKI; of those, 16% had recurrent CS-AKI. Median age at neurodevelopmental assessment was 20 months. The incidence of delay was similar for patients with and patients without CS-AKI but all children with recurrent CS-AKI had a delay in one or more domains and had significantly lower scores in all three domains, namely, cognitive, language, and motor. CONCLUSIONS: This study has assessed the association of CS-AKI with neurodevelopmental delay after surgery for congenital heart disease in infancy. Infants who have recurrent CS-AKI in the first year of life are more likely to be delayed and have lower neurodevelopmental scores.


Asunto(s)
Lesión Renal Aguda , Procedimientos Quirúrgicos Cardíacos , Cardiopatías Congénitas , Lactante , Niño , Humanos , Recién Nacido , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Lesión Renal Aguda/epidemiología , Lesión Renal Aguda/etiología , Cardiopatías Congénitas/complicaciones , Cardiopatías Congénitas/cirugía , Estudios Retrospectivos , Desarrollo Infantil , Factores de Riesgo
6.
Glob Chang Biol ; 28(7): 2425-2441, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34908205

RESUMEN

Depolymerization of high-molecular weight organic nitrogen (N) represents the major bottleneck of soil N cycling and yet is poorly understood compared to the subsequent inorganic N processes. Given the importance of organic N cycling and the rise of global change, we investigated the responses of soil protein depolymerization and microbial amino acid consumption to increased temperature, elevated atmospheric CO2 , and drought. The study was conducted in a global change facility in a managed montane grassland in Austria, where elevated CO2 (eCO2 ) and elevated temperature (eT) were stimulated for 4 years, and were combined with a drought event. Gross protein depolymerization and microbial amino acid consumption rates (alongside with gross organic N mineralization and nitrification) were measured using 15 N isotope pool dilution techniques. Whereas eCO2  showed no individual effect, eT had distinct effects which were modulated by season, with a negative effect of eT on soil organic N process rates in spring, neutral effects in summer, and positive effects in fall. We attribute this to a combination of changes in substrate availability and seasonal temperature changes. Drought led to a doubling of organic N process rates, which returned to rates found under ambient conditions within 3 months after rewetting. Notably, we observed a shift in the control of soil protein depolymerization, from plant substrate controls under continuous environmental change drivers (eT and eCO2 ) to controls via microbial turnover and soil organic N availability under the pulse disturbance (drought). To the best of our knowledge, this is the first study which analyzed the individual versus combined effects of multiple global change factors and of seasonality on soil organic N processes and thereby strongly contributes to our understanding of terrestrial N cycling in a future world.


Asunto(s)
Sequías , Pradera , Aminoácidos , Dióxido de Carbono/análisis , Ecosistema , Nitrógeno/análisis , Suelo/química , Microbiología del Suelo
7.
Soil Biol Biochem ; 136: 107521, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31700196

RESUMEN

Microorganisms are critical in mediating carbon (C) and nitrogen (N) cycling processes in soils. Yet, it has long been debated whether the processes underlying biogeochemical cycles are affected by the composition and diversity of the soil microbial community or not. The composition and diversity of soil microbial communities can be influenced by various environmental factors, which in turn are known to impact biogeochemical processes. The objectives of this study were to test effects of multiple edaphic drivers individually and represented as the multivariate soil environment interacting with microbial community composition and diversity, and concomitantly on multiple soil functions (i.e. soil enzyme activities, soil C and N processes). We employed high-throughput sequencing (Illumina MiSeq) to analyze bacterial/archaeal and fungal community composition by targeting the 16S rRNA gene and the ITS1 region of soils collected from three land uses (cropland, grassland and forest) deriving from two bedrock forms (silicate and limestone). Based on this data set we explored single and combined effects of edaphic variables on soil microbial community structure and diversity, as well as on soil enzyme activities and several soil C and N processes. We found that both bacterial/archaeal and fungal communities were shaped by the same edaphic factors, with most single edaphic variables and the combined soil environment representation exerting stronger effects on bacterial/archaeal communities than on fungal communities, as demonstrated by (partial) Mantel tests. We also found similar edaphic controls on the bacterial/archaeal/fungal richness and diversity. Soil C processes were only directly affected by the soil environment but not affected by microbial community composition. In contrast, soil N processes were significantly related to bacterial/archaeal community composition and bacterial/archaeal/fungal richness/diversity but not directly affected by the soil environment. This indicates direct control of the soil environment on soil C processes and indirect control of the soil environment on soil N processes by structuring the microbial communities. The study further highlights the importance of edaphic drivers and microbial communities (i.e. composition and diversity) on important soil C and N processes.

8.
Soil Biol Biochem ; 128: 45-55, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31579288

RESUMEN

The ratio of carbon (C) that is invested into microbial growth to organic C taken up is known as microbial carbon use efficiency (CUE), which is influenced by environmental factors such as soil temperature and soil moisture. How microbes will physiologically react to short-term environmental changes is not well understood, primarily due to methodological restrictions. Here we report on two independent laboratory experiments to explore short-term temperature and soil moisture effects on soil microbial physiology (i.e. respiration, growth, CUE, and microbial biomass turnover): (i) a temperature experiment with 1-day pre-incubation at 5, 15 and 25 °C at 60% water holding capacity (WHC), and (ii) a soil moisture/oxygen (O2) experiment with 7-day pre-incubation at 20 °C at 30%, 60% WHC (both at 21% O2) and 90% WHC at 1% O2. Experiments were conducted with soils from arable, pasture and forest sites derived from both silicate and limestone bedrocks. We found that microbial CUE responded heterogeneously though overall positively to short-term temperature changes, and decreased significantly under high moisture level (90% WHC)/suboxic conditions due to strong decreases in microbial growth. Microbial biomass turnover time decreased dramatically with increasing temperature, and increased significantly at high moisture level (90% WHC)/suboxic conditions. Our findings reveal that the responses of microbial CUE and microbial biomass turnover to short-term temperature and moisture/O2 changes depended mainly on microbial growth responses and less on respiration responses to the environmental cues, which were consistent across soils differing in land use and geology.

9.
Soil Biol Biochem ; 135: 304-315, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31579295

RESUMEN

Microbial nitrogen use efficiency (NUE) is the efficiency by which microbes allocate organic N acquired to biomass formation relative to the N in excess of microbial demand released through N mineralization. Microbial NUE thus is critical to estimate the capacity of soil microbes to retain N in soils and thereby affects inorganic N availability to plants and ecosystem N losses. However, how soil temperature and soil moisture/O2 affect microbial NUE to date is not clear. Therefore, two independent incubation experiments were conducted with soils from three land uses (cropland, grassland and forest) on two bedrocks (silicate and limestone). Soils were exposed to 5, 15 and 25 °C overnight at 60% water holding capacity (WHC) or acclimated to 30 and 60% WHC at 21% O2 and to 90% WHC at 1% O2 over one week at 20 °C. Microbial NUE was measured as microbial growth over microbial organic N uptake (the sum of growth N demand and gross N mineralization). Microbial NUE responded positively to temperature increases with Q10 values ranging from 1.30 ± 0.11 to 2.48 ± 0.67. This was due to exponentially increasing microbial growth rates with incubation temperature while gross N mineralization rates were relatively insensitive to temperature increases (Q10 values 0.66 ± 0.30 to 1.63 ± 0.15). Under oxic conditions (21% O2), microbial NUE as well as gross N mineralization were not stimulated by the increase in soil moisture from 30 to 60% WHC. Under suboxic conditions (90% WHC and 1% O2), microbial NUE markedly declined as microbial growth rates were strongly negatively affected due to increasing microbial energy limitation. In contrast, gross N mineralization rates increased strongly as organic N uptake became in excess of microbial growth N demand. Therefore, in the moisture/O2 experiment microbial NUE was mainly regulated by the shift in O2 status (to suboxic conditions) and less affected by increasing water availability per se. These temperature and moisture/O2 effects on microbial organic N metabolism were consistent across the soils differing in bedrock and land use. Overall it has been demonstrated that microbial NUE was controlled by microbial growth, and that NUE controlled gross N mineralization as an overflow metabolism when energy (C) became limiting or N in excess in soils. This study thereby greatly contributes to the understanding of short-term environmental responses of microbial community N metabolism and the regulation of microbial organic-inorganic N transformations in soils.

10.
Soil Biol Biochem ; 130: 73-81, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31579309

RESUMEN

Proteins comprise the largest soil N reservoir but cannot be taken up directly by microorganisms and plants due to size constraints and stabilization of proteins in organo-mineral associations. Therefore the cleavage of this high molecular weight organic N to smaller soluble compounds as amino acids is a key step in the terrestrial N cycle. In the last years two isotope pool dilution approaches have been successfully established to measure gross rates of protein depolymerization and microbial amino acid uptake in soils. However, both require laborious sample preparation and analyses, which limits sample throughput. Therefore, we here present a novel isotope pool dilution approach based on the addition of 15N-labeled amino acids to soils and subsequent concentration and 15N analysis by the oxidation of α-amino groups to NO2 - and further reduction to N2O, followed by purge-and-trap isotope ratio mass spectrometry (PT-IRMS). We applied this method in mesocosm experiments with forest and meadow soils as well as with a cropland soil amended with either organic C (cellulose) or organic N (bovine serum albumin). To measure direct organic N mineralization to NH4 +, the latter was captured in acid traps and analyzed by an elemental analyzer coupled to an isotope ratio mass spectrometer (EA-IRMS). Our results demonstrate that the proposed method provides fast and precise measurements of at%15N even at low amino acid concentrations, allows high sample throughput and enables parallel estimations of instantaneous organic N mineralization rates.

11.
Soil Biol Biochem ; 133: 37-49, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31579313

RESUMEN

Proteins constitute the single largest soil organic nitrogen (SON) reservoir and its decomposition drives terrestrial N availability. Protein cleavage by extracellular enzymes is the rate limiting step in the soil organic N cycle and can be controlled by extracellular enzyme production or protein availability/stabilization in soil. Both controls can be affected by geology and land use, as well as be vulnerable to changes in soil temperature and moisture/O2. To explore major controls of soil gross protein depolymerization we sampled six soils from two soil parent materials (calcareous and silicate), where each soil type included three land uses (cropland, pasture and forest). Soil samples were subjected to three temperature treatments (5, 15, 25 °C at 60% water-holding capacity (WHC) and aerobic conditions) or three soil moisture/O2 treatments (30 and 60% WHC at 21% O2, 90% WHC at 1% O2, at 20 °C) in short-term experiments. Samples were incubated for one day in the temperature experiment and for one week in the moisture/O2 experiment. Gross protein depolymerization rates were measured by a novel 15N isotope pool dilution approach. The low temperature sensitivity of gross protein depolymerization, the lack of relationship with protease activity and strong effects of soil texture and pH demonstrate that this process is constrained by organo-mineral associations and not by soil enzyme content. This also became apparent from the inverse effects in calcareous and silicate soils caused by water saturation/O2 limitation. We highlight that the specific soil mineralogy influenced the response of gross depolymerization rates to water saturation/O2 limitation, causing (I) increasing gross depolymerization rates due to release of adsorbed proteins by reductive dissolution of Fe- and Mn-oxyhydroxides in calcareous soils and (II) decreasing gross depolymerization rates due to mobilization of coagulating and toxic Al3+ compounds in silicate soils.

12.
Congenit Heart Dis ; 14(5): 797-802, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31112369

RESUMEN

OBJECTIVE: Neurodevelopmental impairment is common after surgery for congenital heart disease (CHD) in infancy. While neurodevelopmental follow-up of high-risk patients has increased, the referral patterns for ancillary services following initial evaluation have not been reported. The aim of this study is to describe the rates and patterns of referral at the initial visit to our outcomes clinic of patients who underwent surgery for CHD during infancy. OUTCOMES MEASURES: The Cardiac Developmental Outcomes Program clinic at Texas Children's Hospital provides routine longitudinal follow-up with developmental pediatricians and child psychologists for children who required surgery for CHD within the first 3 months of life. Demographic, diagnostic, and clinical data, including prior receipt of intervention and referral patterns at initial presentation, were abstracted from our database. RESULTS: Between April 2013 and May 2017, 244 infants under 12 months of age presented for initial evaluation at a mean age of 7 ± 1.3 months. At presentation, 31% (76/244) were referred for either therapeutic intervention (early intervention or private therapies), ancillary medical services, or both. Referral rates for low-risk (STAT 1-3) and high-risk (STAT 4-5) infants were similar (28 vs. 33%, P = .48). Referrals were more common in: Hispanic white infants (P = .012), infants with non-cardiac congenital anomalies (P = .001), history of gastrostomy tube placement (P < .001), and infants with prior therapy (P = .043). Infants of non-English speaking parents were three times more likely to be referred (95% CI = 1.5, 6.4; P = .002). CONCLUSIONS: At the time of presentation, nearly 1 in 3 infants required referral. Referral patterns did not vary by traditional risk stratification. Sociodemographic factors and co-morbid medical conditions increased the likelihood of referral. This supports the need for routine follow-up for all post-surgical infants regardless of level of surgical complexity. Further research into the completion of referrals and long-term referral patterns is needed.


Asunto(s)
Desarrollo Infantil , Discapacidades del Desarrollo/etiología , Sistemas de Información en Salud/estadística & datos numéricos , Cardiopatías Congénitas/complicaciones , Derivación y Consulta/estadística & datos numéricos , Medición de Riesgo/métodos , Procedimientos Quirúrgicos Cardíacos , Preescolar , Discapacidades del Desarrollo/epidemiología , Discapacidades del Desarrollo/psicología , Femenino , Estudios de Seguimiento , Cardiopatías Congénitas/cirugía , Humanos , Incidencia , Lactante , Masculino , Estudios Retrospectivos , Factores de Riesgo , Texas/epidemiología
13.
Am J Med Genet A ; 179(6): 983-992, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30942555

RESUMEN

Maladaptive behaviors are challenging and a source of stress for caregivers of individuals with Angelman Syndrome (AS). There is limited information on how these maladaptive behaviors vary over time among individuals with AS due to different genetic etiologies. In this study, caregivers of 301 individuals with AS were asked questions about their child's behavior and completed the Aberrant Behavior Checklist-Community version (ABC-C). Developmental functioning was evaluated with either the Bayley Scales of Infant Development, Third Edition (Bayley-III) or the Mullen Scales of Early Learning (MSEL). Family functioning was assessed using the parent-completed Parenting Stress Index (PSI) and the Family Quality of Life questionnaire (FQoL). Approximately 70% of participants had AS due to a deletion on the maternally-inherited copy of chromosome 15q11q13. Results revealed that at baseline, individuals with AS had low scores in the domains of lethargy (mean: 2.6-4.2 depending on genotype) and stereotypy (mean: 2.3-4.2 depending on genotype). Higher cognitive functioning was associated with increased irritability (r = 0.32, p < .01). Hyperactivity (p < .05) and irritability (p < .05) increased with age across all genotypes and should be ongoing targets for both behavioral and pharmacological treatment. Concerns for short attention span were endorsed by more than 70% of caregivers at baseline. Maladaptive behaviors, particularly hyperactivity, irritability and aggression, adversely affected parental stress, and family quality of life.


Asunto(s)
Síndrome de Angelman/diagnóstico , Síndrome de Angelman/psicología , Conducta Estereotipada , Adolescente , Adulto , Alelos , Síndrome de Angelman/genética , Niño , Preescolar , Susceptibilidad a Enfermedades , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Lactante , Masculino , Responsabilidad Parental/psicología , Calidad de Vida , Índice de Severidad de la Enfermedad , Estrés Psicológico , Adulto Joven
14.
PLoS One ; 14(2): e0212120, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30763365

RESUMEN

Deadwood is an important structural component in forest ecosystems and plays a significant role in global carbon and nutrient cycling. Relatively little is known about the formation and decomposition of CWD by microbial communities in situ and about the factors controlling the associated processes. In this study, we intensively analyzed the molecular fungal community composition and species richness in relation to extracellular enzyme activity and differences in decomposing sapwood and heartwood of 13 temperate tree species (four coniferous and nine deciduous species, log diameter 30-40 cm and 4 m long) in an artificial experiment involving placing the logs on the forest soil for six years. We observed strong differences in the molecular fungal community composition and richness among the 13 tree species, and specifically between deciduous and coniferous wood, but unexpectedly no difference was found between sapwood and heartwood. Fungal species richness correlated positively with wood extractives and negatively with fungal biomass. A distinct fungal community secreting lignocellulolytic key enzymes seemed to dominate the decomposition of the logs in this specific phase. In particular, the relative sequence abundance of basidiomycetous species of the Meruliaceae (e.g. Bjerkandera adusta) correlated with ligninolytic manganese peroxidase activity. Moreover, this study reveals abundant white-rot causing Basidiomycota and soft-rot causing Ascomycota during this phase of wood decomposition.


Asunto(s)
Hongos/aislamiento & purificación , Hongos/metabolismo , Árboles/microbiología , Biodiversidad , Biomasa , Fenómenos Químicos , Espacio Extracelular/enzimología , Hongos/citología , Microbiota , Árboles/química
15.
Am J Med Genet A ; 176(5): 1099-1107, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-28944563

RESUMEN

Treatment for Angelman syndrome (AS) is currently limited to symptomatic interventions. A mouse model of AS has reduced calcium/calmodulin-dependent kinase II activity due to excessive phosphorylation of specific threonine residues, leading to diminished long-term potentiation. In a rat model of Parkinson disease, levodopa reduced phosphorylation of various proteins, including calcium/calmodulin-dependent kinase II. Further studies demonstrated that AS mice treated with levodopa performed better on rotarod testing than untreated AS mice. We conducted a multi-center double-blind randomized placebo-controlled 1-year trial of levodopa / carbidopa with either 10 or 15 mg/kg/day of levodopa in children with AS. The outcome of this intervention was assessed using either the Bayley Scales of Infant Development or the Mullen Scales of Early Learning, as well as the Vineland Adaptive Behavior Scales, and the Aberrant Behavior Checklist. Of the 78 participants enrolled, 67 participants received study medication (33 on levodopa, 34 on placebo), and 55 participants (29 on levodopa, 26 on placebo) completed the 1-year study. There were no clinically or statistically significant changes in any of the outcome measures over a 1-year period comparing the levodopa and placebo groups. The number of adverse events reported, including the more serious adverse events, was similar in both groups, but none were related to treatment with levodopa. Our data demonstrate that levodopa is well-tolerated by children with AS. However, in the doses used in this study, it failed to improve their neurodevelopment or behavioral outcome.


Asunto(s)
Síndrome de Angelman/tratamiento farmacológico , Levodopa/uso terapéutico , Síndrome de Angelman/diagnóstico , Síndrome de Angelman/fisiopatología , Síndrome de Angelman/psicología , Animales , Biomarcadores , Calcio/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Modelos Animales de Enfermedad , Humanos , Levodopa/administración & dosificación , Potenciación a Largo Plazo , Ratones , Pruebas Neuropsicológicas , Resultado del Tratamiento
16.
Soil Biol Biochem ; 123: 115-125, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31579317

RESUMEN

Amino sugars and D-amino acid enantiomers are major components of bacterial and fungal cell walls (i.e. peptidoglycan and chitin) and are often used as biomarkers of microbial residue turnover in soils. However, little is known about the in situ decomposition rates of microbial cell wall residues and how soil physicochemical properties affect this process. In this study, we investigated the in situ gross production and consumption rates of free amino sugars (glucosamine and muramic acid) and amino acids (meso-diaminopimelic acid, l-alanine, and d-alanine) by a novel isotope pool dilution assay using 15N-labeled amino compounds. Soils were obtained from six sites differing in land management (cropland, pasture, and forest) and bedrock (silicate and limestone) and incubated at three temperatures (5, 15, and 25 °C). Free glucosamine released during the decomposition of peptidoglycan and chitin contributed significantly to the extractable soil organic nitrogen pool. Gross production and consumption rates of glucosamine were higher than those of individual amino acids, i.e. L- and D-alanine. Muramic acid had a longer mean residence time (68 h compared to 2.7 h for glucosamine, L- and D-alanine) and made a negligible contribution to soil organic nitrogen fluxes, indicating that free muramic acid was not a major decomposition product of peptidoglycan in soils. Meso-diaminopimelic acid and D-alanine exhibited comparable gross production and consumption rates with L-alanine. These amino acids can be used as indicators to estimate the decomposition of peptidoglycan from bacterial cell wall residues. We found that chitin decomposition was greater in silicate soils, while peptidoglycan decomposition dominated in limestone soils. Glucosamine production rates were not correlated with soil total amino sugars, microbial community structure, or hydrolytic enzyme activities, but were highest in soils with low pH and high sand content, indicating that soil texture and soil pH may strongly influence the decomposition of amino sugar polymers. In contrast, mDAP, L- and D-alanine gross production and consumption rates were positively correlated with soil pH and clay content, due to greater depolymerization of peptidoglycan stem peptides in limestone soils. This isotope pool dilution approach strongly improves our understanding of the mechanisms and environmental controls on microbial cell wall decomposition in soils.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...