Differential substrate specificity and kinetic behavior of Escherichia coli YfdW and Oxalobacter formigenes formyl coenzyme A transferase

The yfdXWUVE operon appears to encode proteins that enhance the ability of Escherichia coli MG1655 to survive under acidic conditions. Although the molecular mechanisms underlying this phenotypic behavior remain to be elucidated, findings from structural genomic studies have shown that the structure of YfdW, the protein encoded by the yfdW gene, is homologous to that of the enzyme that mediates oxalate catabolism in the obligate anaerobe Oxalobacter formigenes, O. formigenes formyl coenzyme A transferase (FRC). We now report the first detailed examination of the steady-state kinetic behavior and substrate specificity of recombinant, wild-type YfdW. Our studies confirm that YfdW is a formyl coenzyme A (formyl-CoA) transferase, and YfdW appears to be more stringent than the corresponding enzyme (FRC) in Oxalobacter in employing formyl-CoA and oxalate as substrates. We also report the effects of replacing Trp-48 in the FRC active site with the glutamine residue that occupies an equivalent position in the E. coli protein. The results of these experiments show that Trp-48 precludes oxalate binding to a site that mediates substrate inhibition for YfdW. In addition, the replacement of Trp-48 by Gln-48 yields an FRC variant for which oxalate-dependent substrate inhibition is modified to resemble that seen for YfdW. Our findings illustrate the utility of structural homology in assigning enzyme function and raise the question of whether oxalate catabolism takes place in E. coli upon the up-regulation of the yfdXWUVE operon under acidic conditions.     

Histopathologic observations on thyroid carcinoma with amyloid stroma.

The authors describe histopathologic aspects in ten cases of thyroid carcinoma with amyloid stroma. This form of cancer represents 3.4% of all the thyroid cancer cases in the last five years in the Institute of Endocrinology. Microscopic examination reveals a polymorphous picture alongside with amyloid deposits. The authors attribute to the tumor cells an important role in producing thyroid amyloidosis.     

Mutations in C8orf37, encoding a ciliary protein, are associated with autosomal-recessive retinal dystrophies with early macular involvement

Cone-rod dystrophy (CRD) and retinitis pigmentosa (RP) are clinically and genetically overlapping heterogeneous retinal dystrophies. By using homozygosity mapping in an individual with autosomal-recessive (ar) RP from a consanguineous family, we identified three sizeable homozygous regions, together encompassing 46 Mb. Next-generation sequencing of all exons, flanking intron sequences, microRNAs, and other highly conserved genomic elements in these three regions revealed a homozygous nonsense mutation (c.497T>A [p.Leu166^∗]) in C8orf37, located on chromosome 8q22.1. This mutation was not present in 150 ethnically matched control individuals, single-nucleotide polymorphism databases, or the 1000 Genomes database. Immunohistochemical studies revealed C8orf37 localization at the base of the primary cilium of human retinal pigment epithelium cells and at the base of connecting cilia of mouse photoreceptors. C8orf37 sequence analysis of individuals who had retinal dystrophy and carried conspicuously large homozygous regions encompassing C8orf37 revealed a homozygous splice-site mutation (c.156−2A>G) in two siblings of a consanguineous family and homozygous missense mutations (c.529C>T [p.Arg177Trp]; c.545A>G [p.Gln182Arg]) in siblings of two other consanguineous families. The missense mutations affect highly conserved amino acids, and in silico analyses predicted that both variants are probably pathogenic. Clinical assessment revealed CRD in four individuals and RP with early macular involvement in two individuals. The two CRD siblings with the c.156−2A>G mutation also showed unilateral postaxial polydactyly. These results underline the importance of disrupted ciliary processes in the pathogenesis of retinal dystrophies.     

Immunohistochemistry of thyroid hormones as a functional parameter in thyroid pathology

The authors study by means of immunoperoxidase method the pattern of thyroglobulin, triiodothyronine and thyroxine distribution in 58 cases of thyroid disorders: 15 euthyroid goiters, 10 Graves' disease, 7 Hashimoto's thyroiditis, 11 folliculo-papillary carcinomas (6 primary tumors and 5 lymph node metastases), 8 follicular carcinomas, 4 anaplastic carcinomas and 3 medullary carcinomas. Thyroglobulin, triiodothyronine and thyroxine were present in most of the thyroid disorders, excepting anaplastic and medullary carcinomas. Thyroglobulin and thyroxine were localized both in the follicular epithelium and in the colloid, whereas triiodothyronine was present especially in the follicular cells. The thyroid hormones distribution in benign lesions is rather similar. In carcinomas, the pattern of thyroglobulin, triiodothyronine and thyroxine is more heterogeneous, but generally the triiodothyronine distribution is similar to that of thyroglobulin. In some carcinomas, triiodothyronine and thyroxine showed a weak or negative immunostaining. The immunoperoxidase method is a valuable tool in the study of functional disturbances in the thyroid pathology and in the diagnosis of thyroid carcinoma metastases as well. Positive thyroid hormones staining clearly indicates the thyroid origin of metastases.     

Shape of Single and Multiple Central‐Place Territories in a Stream‐Dwelling Fish

Territory shape yields important insights into how animals exploit local resources. Territories of stream‐dwelling salmonids are typically (1) mapped around a single central‐place, (2) described as circular, elliptical or teardrop‐shaped, and (3) believed to reflect their exploitation of drifting invertebrate prey. In this study, we tested the current view of territory shape by mapping multiple central‐place territories for 50 young‐of‐the‐year Atlantic salmon. Multiple central‐place areas were more elongated (eccentricity: median = 1.301, range = 1.043–2.784) than the foraging patterns around each central place (eccentricity: median = 1.135, range = 1.014–1.385). In addition, multiple central‐place areas were elongated along the stream length (33 of 50 fish), whereas the foraging areas around each station tended to be elongated along the stream width (32 of 50 fish). These findings may be explained by the way that stream salmonids interact with drifting prey. At each central place, a wider foraging area should provide an increased access to prey drifting downstream. Similarly, by regularly patrolling a large multiple central‐place area along the stream axis, a territorial fish may increase its access to drifting prey by excluding competitors from upstream areas. Further studies are needed on the ecological factors that determine territory shape in stream fish and multiple central‐place foragers.     

The Terneuzen Birth Cohort: BMI Changes between 2 and 6 Years Correlate Strongest with Adult Overweight

Background

Complications of overweight amplify with age, and irreversible damage already exists in young persons. Identifying the most sensitive age interval(s) for adult overweight is relevant for primary prevention. The aim of the study was to assess the relative contribution of body mass index (BMI) changes between 0 and 18 years to adult overweight, and to identify the earliest critical growth period.

Methods and Findings

Data from 762 subjects in the Terneuzen Birth Cohort with an average of 21 growth measurements per subject from birth until 18 years were used. The main outcome measure was the BMI standard deviation score (SDS) at young adulthood. For each subject BMI SDS was fitted by a piecewise linear model at eight different ages and correlated to adult BMI SDS. The age intervals in between are considered critical according to three criteria, tested by respectively Students'' t-tests, multiple linear regression analyses and Pearson''s correlation tests. In the age intervals 4 months(m) -1 year(y), 2–6 y, 6–10 y and 10–18 y the BMI SDS change differs between adults with and without overweight (P≤0.001). The age intervals 2–6 y and 10–18 y also meet the second criterion, implying that the BMI change during this period has a predictive value for adult BMI SDS in addition to BMI SDS at the end of the period. The largest rise in correlation between estimated BMI SDS and measured adult BMI SDS occurs during the period 2–6 y (from 0.36 to 0.63), which results in a high sensitivity (0.6) and specificity (0.8) by the age of 6 y.

Conclusions/Significance

The age interval from 2 y to 6 y is the earliest and most critical growth period for adult overweight. Therefore, primary prevention of adult overweight seems most likely to be successful if targeted at this specific age interval. By identifying those with an upwards centile crossing between 2 and 6 years, the development towards adult overweight might be reversed.     

Mapping, characterization, and expression analysis of the SM-20 human homologue, c1orf12, and identification of a novel related gene, SCAND2

Major psychosis was shown to segregate with a balanced translocation (1q42.1; 11q14.3) in a multigenerational family. This study describes the identification of a human SM-20 homologue gene that lies at about 400 kb on the centromeric side of the 1q42.1 breakpoint. The full-length cDNA sequence and gene structure were determined. Expression analysis was performed, showing high expression levels in skeletal and cardiac muscles; in the central nervous system, expression was restricted to dopaminergic neurons and spinal motoneurons. A second gene displaying high sequence similarity with SM-20 was also identified by BLAST. This gene, located on chromosome 15, is likely to have evolved by retroposition of SM-20 mRNA and an exon-shuffling mechanism. It encodes a 306-amino-acid protein harboring strong homology with an N-terminal motif found in some zinc-finger proteins. This gene was named SCAND2 (SCAN domain-containing 2).