Decomposition in salt marsh ecosystems: The phases and major factors affecting disappearance of above-ground organic matter

Decay of litter of salt marsh grasses occurs in three phases. First there is an early phase lasting less than a month, with fast rates of weight loss, during which 5 to 40% of the litter is lost, probably by leaching of soluble compounds. A second slower phase lasts up to a year. In this second phase, microbial degradation of organic matter and subsequent leaching of hydrolyzed substances remove an additional 40 to 70% of the original material. A third phase may last an additional year; in this phase decay is very slow because only relatively refractory materials remain. By this third stage as little as 10% of the original material may remain. Differences in the chemical makeup of litter are the major factors affecting the amount of decay during the leaching and decomposer phases. Such chemical differences may be due to differences in the chemistry of the plant species producing the litter or in nutrient supply. Spartina patens (Ait.) Muhl., for example, produces litter that decays more slowly than that of S. alterniflora Loisel. Increases in internal nitrogen content of litter increase loss of weight during the leaching and decomposer phases, while the external supply of nitrogen increases decay rates only during the decomposer phase. Temperature increases decay rates to some extent during the decomposer phase. The feeding activity of large detritus-feeding invertebrates produces a small but significant increase in decay rate during the decomposer phase. Decay rate in litterbags mimics decay of litter in the field, and makes possible estimates of litter turnover. The turnover of litter of S. alterniflora was 1.1-1.4 · yr-1. Litter of S. patens turns over more slowly, 2.1 · yr-1. Nutrient enrichment accelerates turnover of litter up to 24% compared to control litter. Since eutrophication of salt marshes both enriches litter and changes species of plants, it has broad consequences for ecological processes dependent on decomposition of organic matter. © 1985

Decomposition in salt marsh ecosystems: The phases and major factors affecting disappearance of above-ground organic matter

Decay of litter of salt marsh grasses occurs in three phases. First there is an early phase lasting less than a month, with fast rates of weight loss, during which 5 to 40% of the litter is lost, probably by leaching of soluble compounds. A second slower phase lasts up to a year. In this second phase, microbial degradation of organic matter and subsequent leaching of hydrolyzed substances remove an additional 40 to 70% of the original material. A third phase may last an additional year; in this phase decay is very slow because only relatively refractory materials remain. By this third stage as little as 10% of the original material may remain. Differences in the chemical makeup of litter are the major factors affecting the amount of decay during the leaching and decomposer phases. Such chemical differences may be due to differences in the chemistry of the plant species producing the litter or in nutrient supply. Spartina patens (Ait.) Muhl., for example, produces litter that decays more slowly than that of S. alterniflora Loisel. Increases in internal nitrogen content of litter increase loss of weight during the leaching and decomposer phases, while the external supply of nitrogen increases decay rates only during the decomposer phase. Temperature increases decay rates to some extent during the decomposer phase. The feeding activity of large detritus-feeding invertebrates produces a small but significant increase in decay rate during the decomposer phase. Decay rate in litterbags mimics decay of litter in the field, and makes possible estimates of litter turnover. The turnover of litter of S. alterniflora was 1.1-1.4 · yr-1. Litter of S. patens turns over more slowly, 2.1 · yr-1. Nutrient enrichment accelerates turnover of litter up to 24% compared to control litter. Since eutrophication of salt marshes both enriches litter and changes species of plants, it has broad consequences for ecological processes dependent on decomposition of organic matter. © 1985

De novo and inherited mutations in the X-linked gene CLCN4 are associated with syndromic intellectual disability and behavior and seizure disorders in males and females

Variants in CLCN4, which encodes the chloride/hydrogen ion exchanger CIC-4 prominently expressed in brain, were recently described to cause X-linked intellectual disability and epilepsy. We present detailed phenotypic information on 52 individuals from 16 families with CLCN4-related disorder: 5 affected females and 2 affected males with a de novo variant in CLCN4 (6 individuals previously unreported) and 27 affected males, 3 affected females and 15 asymptomatic female carriers from 9 families with inherited CLCN4 variants (4 families previously unreported). Intellectual disability ranged from borderline to profound. Behavioral and psychiatric disorders were common in both child- and adulthood, and included autistic features, mood disorders, obsessive-compulsive behaviors and hetero- and autoaggression. Epilepsy was common, with severity ranging from epileptic encephalopathy to well-controlled seizures. Several affected individuals showed white matter changes on cerebral neuroimaging and progressive neurological symptoms, including movement disorders and spasticity. Heterozygous females can be as severely affected as males. The variability of symptoms in females is not correlated with the X inactivation pattern studied in their blood. The mutation spectrum includes frameshift, missense and splice site variants and one single-exon deletion. All missense variants were predicted to affect CLCN4's function based on in silico tools and either segregated with the phenotype in the family or were de novo. Pathogenicity of all previously unreported missense variants was further supported by electrophysiological studies in Xenopus laevis oocytes. We compare CLCN4-related disorder with conditions related to dysfunction of other members of the CLC family.Molecular Psychiatry advance online publication, 23 August 2016; doi:10.1038/mp.2016.135.status: publishe

De novo and inherited mutations in the X-linked gene CLCN4 are associated with syndromic intellectual disability and behavior and seizure disorders in males and females

Variants in CLCN4, which encodes the chloride/hydrogen ion exchanger CIC-4 prominently expressed in brain, were recently described to cause X-linked intellectual disability and epilepsy. We present detailed phenotypic information on 52 individuals from 16 families with CLCN4-related disorder: 5 affected females and 2 affected males with a de novo variant in CLCN4 (6 individuals previously unreported) and 27 affected males, 3 affected females and 15 asymptomatic female carriers from 9 families with inherited CLCN4 variants (4 families previously unreported). Intellectual disability ranged from borderline to profound. Behavioral and psychiatric disorders were common in both child-and adulthood, and included autistic features, mood disorders, obsessive-compulsive behaviors and hetero-and autoaggression. Epilepsy was common, with severity ranging from epileptic encephalopathy to well-controlled seizures. Several affected individuals showed white matter changes on cerebral neuroimaging and progressive neurological symptoms, including movement disorders and spasticity. Heterozygous females can be as severely affected as males. The variability of symptoms in females is not correlated with the X inactivation pattern studied in their blood. The mutation spectrum includes frameshift, missense and splice site variants and one single-exon deletion. All missense variants were predicted to affect CLCN4's function based on in silico tools and either segregated with the phenotype in the family or were de novo. Pathogenicity of all previously unreported missense variants was further supported by electrophysiological studies in Xenopus laevis oocytes. We compare CLCN4-related disorder with conditions related to dysfunction of other members of the CLC family

AAV9-mediated gene transfer of desmin ameliorates cardiomyopathy in desmin-deficient mice

Mutations of the human desmin (DES) gene cause autosomal dominant and recessive myopathies affecting skeletal and cardiac muscle tissue. Desmin knockout mice (DES-KO), which develop progressive myopathy and cardiomyopathy, mirror rare human recessive desminopathies in which mutations on both DES alleles lead to a complete ablation of desmin protein expression. Here, we investigated whether an adeno-associated virus-mediated gene transfer of wild-type desmin cDNA (AAV-DES) attenuates cardiomyopathy in these mice. Our approach leads to a partial reconstitution of desmin protein expression and the de novo formation of the extrasarcomeric desmin-syncoilin network in cardiomyocytes of treated animals. This finding was accompanied by reduced fibrosis and heart weights and improved systolic left-ventricular function when compared with control vector-treated DES-KO mice. Since the re-expression of desmin protein in cardiomyocytes of DES-KO mice restores the extrasarcomeric desminsyncoilin cytoskeleton, attenuates the degree of cardiac hypertrophy and fibrosis, and improves contractile function, AAV-mediated desmin gene transfer may be a novel and promising therapeutic approach for patients with cardiomyopathy due to the complete lack of desmin protein expression