Annexins A2 and A6 interact with the extreme N terminus of tau and thereby contribute to tau's axonal localization.

During neuronal development, the microtubule-associated protein tau becomes enriched in the axon, where it remains concentrated in the healthy brain. In tauopathies such as Alzheimer's disease, tau redistributes from the axon to the somatodendritic compartment. However, the cellular mechanism that regulates tau's localization remains unclear. We report here that tau interacts with the Ca2+-regulated plasma membrane-binding protein annexin A2 (AnxA2) via tau's extreme N terminus encoded by the first exon (E1). Bioinformatics analysis identified two conserved eight-amino-acids-long motifs within E1 in mammals. Using a heterologous yeast system, we found that disease-related mutations and pseudophosphorylation of Tyr-18, located within E1 but outside of the two conserved regions, do not influence tau's interaction with AnxA2. We further observed that tau interacts with the core domain of AnxA2 in a Ca2+-induced open conformation and interacts also with AnxA6. Moreover, lack of E1 moderately increased tau's association rate to microtubules, consistent with the supposition that the presence of the tau-annexin interaction reduces the availability of tau to interact with microtubules. Of note, intracellular competition through overexpression of E1-containing constructs reduced tau's axonal enrichment in primary neurons. Our results suggest that the E1-mediated tau-annexin interaction contributes to the enrichment of tau in the axon and is involved in its redistribution in pathological conditions.

Novel domain architectures and functional determinants in atypical annexins revealed by phylogenomic analysis.

The fundamental cellular role and molecular interactions of annexins in vesicle trafficking and membrane remodeling remain to be further clarified in order to better understand and exploit their contributions to health and disease. We focused on distinctive features of atypical annexins from all domains of life using phylogenomic, molecular systematic and experimental approaches, to extend the current paradigm and better account for annexin diversity of structure, function and mechanistic role in membrane homeostasis. The analysis of gene duplications, organization of domain architectures and profile hidden Markov models of subfamily orthologs defined conserved structural features relevant to molecular interactions and functional divergence of seven family clades ANXA-G. Single domain annexins of bacteria, including cyanobacteria, were frequently coupled to enzymatic units conceivably related to membrane metabolism and remodeling. Multiple ANX domains (up to 20) and various distinct functional domains were observed in unique annexins. Canonical type 2 calcium binding ligands were well-preserved in roughly half of all ANX domains, but alternative structural motifs comprised of 'KGD', cysteine or tryptophan residues were prominently conserved in the same strategic interhelical loops. Selective evolutionary constraint, site-specific location and co-occurrence in all kingdoms identify alternative modes of fundamental binding interactions for annexins.

An evolutionary roadmap to the microtubule-associated protein MAP Tau.

BACKGROUND: The microtubule associated protein Tau (MAPT) promotes assembly and interaction of microtubules with the cytoskeleton, impinging on axonal transport and synaptic plasticity. Its neuronal expression and intrinsic disorder implicate it in some 30 tauopathies such as Alzheimer's disease and frontotemporal dementia. These pathophysiological studies have yet to be complemented by computational analyses of its molecular evolution and structural models of all its functional domains to explain the molecular basis for its conservation profile, its site-specific interactions and the propensity to conformational disorder and aggregate formation. RESULTS: We systematically annotated public sequence data to reconstruct unspliced MAPT, MAP2 and MAP4 transcripts spanning all represented genomes. Bayesian and maximum likelihood phylogenetic analyses, genetic linkage maps and domain architectures distinguished a nonvertebrate outgroup from the emergence of MAP4 and its subsequent ancestral duplication to MAP2 and MAPT. These events were coupled to other linked genes such as KANSL1L and KANSL and may thus be consequent to large-scale chromosomal duplications originating in the extant vertebrate genomes of hagfish and lamprey. Profile hidden Markov models (pHMMs), clustered subalignments and 3D structural predictions defined potential interaction motifs and specificity determining sites to reveal distinct signatures between the four homologous microtubule binding domains and independent divergence of the amino terminus. CONCLUSION: These analyses clarified ambiguities of MAPT nomenclature, defined the order, timing and pattern of its molecular evolution and identified key residues and motifs relevant to its protein interaction properties and pathogenic role. Additional unexpected findings included the expansion of cysteine-containing, microtubule binding domains of MAPT in cold adapted Antarctic icefish and the emergence of a novel multiexonic saitohin (STH) gene from repetitive elements in MAPT intron 11 of certain primate genomes.

Evolutionary adaptation of plant annexins has diversified their molecular structures, interactions and functional roles.

Annexins are an homologous, structurally related superfamily of proteins known to associate with membrane lipid and cytoskeletal components. Their involvement in membrane organization, vesicle trafficking and signaling is fundamental to cellular processes such as growth, differentiation, secretion and repair. Annexins exist in some prokaryotes and all eukaryotic phyla within which plant annexins represent a monophyletic clade of homologs descended from green algae. Genomic, proteomic and transcriptomic approaches have provided data on the diversity, cellular localization and expression patterns of different plant annexins. The availability of 35 complete plant genomes has enabled systematic comparative analysis to determine phylogenetic relationships, characterize structures and observe functional specificity between and within individual subfamilies. Short amino termini and selective erosion of the canonical type 2 calcium coordinating sites in domains 2 and 3 are typical of plant annexins. The convergent evolution of alternate functional motifs such as 'KGD', redox-sensitive Cys and hydrophobic Trp/Phe residues argues for their functional relevance and contribution to mechanistic diversity in plant annexins. This review examines recent findings and advances in plant annexin research with special focus on their structural diversity, cellular and molecular interactions and their potential integrated functions in the broader context of physiological responses.

Strumpellin is a novel valosin-containing protein binding partner linking hereditary spastic paraplegia to protein aggregation diseases.

Mutations of the human valosin-containing protein gene cause autosomal-dominant inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia. We identified strumpellin as a novel valosin-containing protein binding partner. Strumpellin mutations have been shown to cause hereditary spastic paraplegia. We demonstrate that strumpellin is a ubiquitously expressed protein present in cytosolic and endoplasmic reticulum cell fractions. Overexpression or ablation of wild-type strumpellin caused significantly reduced wound closure velocities in wound healing assays, whereas overexpression of the disease-causing strumpellin N471D mutant showed no functional effect. Strumpellin knockdown experiments in human neuroblastoma cells resulted in a dramatic reduction of axonal outgrowth. Knockdown studies in zebrafish revealed severe cardiac contractile dysfunction, tail curvature and impaired motility. The latter phenotype is due to a loss of central and peripheral motoneuron formation. These data imply a strumpellin loss-of-function pathogenesis in hereditary spastic paraplegia. In the human central nervous system strumpellin shows a presynaptic localization. We further identified strumpellin in pathological protein aggregates in inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia, various myofibrillar myopathies and in cortical neurons of a Huntington's disease mouse model. Beyond hereditary spastic paraplegia, our findings imply that mutant forms of strumpellin and valosin-containing protein may have a concerted pathogenic role in various protein aggregate diseases.

[Capillary HbA1c determination on type 2 diabetes patients in a primary health centre]. / Estudio de la determinación de la hemoglobina glucosilada en pacientes con diabetes mellitus 2 en sangre capilar en un centro de atención primaria.

OBJECTIVE: To determine the reliability and practicability of the point-of-care- test (POCT) analyzer, Afinion, for capillary HbA1c testing. To assess the benefits of its implementation on the intra-annual follow up of type 2 diabetic patients. DESIGN: Descriptive cross-sectional study. Analytical validation of the Afinion reader. SETTING: Primary Health Care (CAP Carmel and Bon Pastor Clinic Laboratory). PARTICIPANTS: A total of 94 type 2 diabetic patients selected according to their previous HbA1c value. METHODS: We performed one capillary puncture and one venous extraction on each visit. The capillary sample was assessed in real time on the Afinion in the Primary Health Care Centre and the venous sample was sent to Bon Pastor Clinic Laboratory for assessment on an Afinion analyzer and by a high performance liquid chromatrography (HPLC) reference method. Practicability was assesses by both by the operators of the Afinion and the patients using an 11 question questionnaire. The efficiency in terms of process timings was also evaluated. RESULTS: Intra-serial coefficient of variation (CV) was lower than 1% and inter-serial lower than 3%. The regression analysis showed: Afinion capillary sample=0.95 Afinion venous+0.21. No systematic or proportional error was detected in the 95% confidence interval (95% CI). The comparison between venous HPLC and Afinion showed: Afinion capillary sample=0.80 HPLC+1.14. A statistically significant difference was shown for these values at the 95% CI. Practicability was valued by users from 7 to 9.2 (professionals) and from 7.7 to 9.2 (patients). Implementation of the Afinion capillary method for intra-annual testing in follow up of diabetic patients could result in the saving of 600-900 professional hours/year. CONCLUSIONS: Afinion seems to be a good choice for the intra-annual determination of HbA1c when compared to the traditional process due to its accessibility, practicability and efficiency. Professionals should know the limitations of the POCT method in order to consider the validity of the results.

[Abuse in the elderly]. / Maltrato en el anciano.

Reflections on the UN decree of June 15 as International Day of No Abuse of the Elderly which have been enhanced by the celebration in Madrid, Hospital Clinico San Carlos, a day devoted to this topic with the aim of raising awareness among professionals working in health centers and other interest groups, groups of retirees and social services, health problems and abuse in the elderly

Assessment of (-) epicatechin as natural additive for improving safety and functionality in fresh "Piel de Sapo" melon juice.

Epicatechin (EC) is a very abundant flavonoid in vegetable tissues that presents high antioxidant activity in living systems. The minimum inhibitory concentration (MIC) of (-)EC was determined in three species of bacteria commonly associated with foodborne illness of plant origin: Listeria (L.) monocytogenes, Escherichia (E.) coli -serogroups O157: H7 and O111- and Bacillus (B.) cereus; two strains of probiotic-type lactic acid bacteria (PT-LAB) and two control strains. All 10 strains were assayed under three temperature conditions (30º, 10º, and 4ºC) and at each temperature under two pH conditions (6.7 and 5.5). Mean EC MIC values were generally lower at refrigeration (4º and 10ºC) temperatures and at standard pH (6.7). By inoculating with each of the strains separately, both melon juice (MJ) and MJ supplemented with EC (ECSMJ), at the accepted maximum sensorial limit, and storing them at 4ºC for 10 days; the final counts (CFU/mL) were lower for ECSMJ than for plain MJ both for pathogenic bacteria and for PT-LAB. The presence of EC during refrigerated storage counteracted the ability of MJ as a growth medium for all the pathogenic bacteria. ECSMJ increased the antioxidant activity of MJ significantly to levels similar to those of EC alone. (-) Epicathechin would be a promising ingredient for increasing the functional properties of "Piel de Sapo" MJ (phenolic compounds and antioxidant ability) while contributing to improving the safety of this type of juice during prolonged refrigerated storage at 4ºC.

Assessment of Stress by Serum Biomarkers in Calves and Their Relationship to Ultimate pH as an Indicator of Meat Quality.

Seventy-eight calves from Asturiana de los Valles, Retinta, and Rubia Gallega breeds, under extensive and intensive farm systems and animal mixing and non-mixing conditions, and during the transport and lairage in slaughterhouses, were studied. This research aimed to study the effect of breed, farm system and mixing conditions on serum biomarkers (cortisol, lactate, glucose, serum amyloid A, haptoglobin, and C-reactive protein) and their relationship with pHu at slaughter time, and to evaluate the response of the serum biomarkers of calves throughout fattening period. Moreover, this study aims to evaluate the response of the biomarkers in each breed during the fattening period. At slaughter time, cortisol and lactate were affected by BreedxFarm; Retinta showed the opposite pattern to the others and revealed the highest glucose in extensive farm systems. Rubia Gallega in mixing revealed the highest Amyloid A and haptoglobin. Extensive calves in mixing conditions showed the highest glucose. There was a relationship among the variables cortisol, lactate, Amyloid A, and pHu. Slaughter time was a major stressor, and the stress response was mainly affected by breed. At slaughter, several biomarkers should be considered.

A Follow-Up Study of Cognitive Development in Low Risk Preterm Children.

The results of a longitudinal study on the cognitive development of one group of full-term and three groups of low risk preterm children with different gestational ages (GA) are presented. The 181 participants were divided into four GA groups of similar size. The aims were: 1) To check if there are differences in cognitive development (measured through the Batelle scale) among the GA groups. 2) To establish the predictive factors of cognitive development at 22 and 60 months of age, taking into account biomedical, environmental and individual factors. The results of the repeated measures ANOVA performed at 22 and 60 months of age indicated that the cognitive trajectories of the four GA groups were similar. Linear regression analyses showed that the effect of the different predictors changed in relation to the time of measurement of cognitive development. Biological factors and the quality of home environment had a moderate effect on the cognitive development at 22 months of age. Cognitive results obtained at 22 months of age, and, to a lesser extent, working memory had the greatest effect on cognitive development at 60 months. GA does not predict cognitive development. Preterm children do not show cognitive delay if they are healthy.

Deciphering function and mechanism of calcium-binding proteins from their evolutionary imprints.

Calcium-binding proteins regulate ion metabolism and vital signalling pathways in all living organisms. Our aim is to rationalize the molecular basis of their function by studying their evolution using computational biology techniques. Phylogenetic analysis is of primary importance for classifying cognate orthologs; profile hidden Markov models (HMM) of individual subfamilies discern functionally relevant sites by conservation probability analysis; and 3-dimensional structures display the integral protein in context. The major classifications of calcium-binding proteins, viz. EF-hand, C2 and ANX, exhibit structural diversity in their HMM fingerprints at the subfamily level, with functional consequences for protein conformation, exposure of receptor interaction sites and/or binding to membrane phospholipids. Calmodulin, S100 and annexin families were characterized in Petromyzon marinus (sea lamprey) to document genome duplication and gene creation events during the key evolutionary transition to primitive vertebrates. Novel annexins from diverse organisms revealed calcium-binding domains with accessory structural features that define their unique molecular fingerprints, protein interactivity and functional specificity. These include the first single-domain, bacterial annexin in Cytophaga hutchinsonii, the 21 tetrad annexins from the unicellular protist Giardia intestinalis, an ancestor to land plant annexins from the green alga Ostreococcus lucimarinus, invertebrate octad annexins and a critical polymorphism in human ANXA7. Receptor docking models supported the hypothesis of a potential interaction between annexin and C2 domains as a propitious mechanism for ensuring membrane translocation during signal transduction.

[Annexin A2 expression in head and neck squamous cell carcinoma]. / Expresión de la anexina A2 en los carcinomas epidermoides de cabeza y cuello.

OBJECTIVE: Over-expression of annexin A2 (ANXA2) has been reported in various cancers. However, no data are available on the expression of this protein in head and neck squamous cell carcinomas (HNSCC). The objective of this preliminary study is to investigate the expression of ANXA2 in these carcinomas. MATERIAL AND METHOD: ANXA2 expression was analyzed by immunohistochemistry in paraffin-embedded sections from 9 patients with premalignant lesions and 21 patients with HNSCC. RESULTS: All dysplastic tissues showed significantly reduced ANXA2 expression compared to normal tissue. In contrast, ANXA2 expression was observed in all but one of the tumours studied. There was a significant correlation of lower ANXA2 expression with a poorer histological differentiation, larger tumours, and nodal metastases. CONCLUSIONS: Our data show for the first time that ANXA2 is expressed in head and neck squamous cell carcinomas and that its expression seems to be related with the degree of differentiation status of these tumours.

Structure-function relationship in annexin A13, the founder member of the vertebrate family of annexins.

Annexin A13 is considered the original progenitor of the 11 other members of vertebrate annexins, a superfamily of calcium/phospholipid-binding proteins. It is highly tissue-specific, being expressed only in intestinal and kidney epithelial cells. Alternative splicing generates two isoforms, both of which bind to rafts. In view of the lack of structural information supporting the physiological role of this annexin subfamily, we have cloned, expressed and purified human annexin A13b to investigate its structural and functional properties. The N-terminus of annexin A13b: (i) destabilizes the conserved protein core, as deduced from the low melting temperature in the absence (44 degrees C) or presence of calcium (55 degrees C), and (ii) impairs calcium-dependent binding to acidic phospholipids, requiring calcium concentrations >400 microM. Truncation of the N-terminus restores thermal stability and decreases the calcium requirement for phospholipid binding, confirming its essential role in the structure-function relationship of this annexin. Non-myristoylated annexin A13b only binds to acidic phospholipids at high calcium concentrations. We show for the first time that myristoylation of annexin A13b enables the direct binding to phosphatidylcholine, raft-like liposomes and acidic phospholipids in a calcium-independent manner. The conformational switch induced by calcium binding, from a 'closed' to an 'open' conformation with exposure of Trp227, can be mimicked by a decrease in pH, a process that may be relevant for membrane interactions. Our studies confirm that the common structural and functional characteristics that are dependent on the protein core of vertebrate annexins are likely to be common conserved features, whereas their variable N-termini confer distinct functional properties on annexins, as we report for myristoylation of annexin A13b.

Expression of annexin A1 in normal and chronically inflamed nasal mucosa.

OBJECTIVE: To examine the expression pattern of annexin A1 in normal and chronically inflamed nasal mucosa to investigate its possible role in nasal inflammation. DESIGN: Immunohistochemical analysis. SUBJECTS: Samples of middle turbinates from 5 healthy subjects and 5 patients with perennial rhinitis, and samples of nasal polyps from 7 patients. INTERVENTIONS: Annexin A1 expression was examined with a standard immunohistochemical protocol on paraffin-embedded sections. RESULTS: Annexin A1 was highly expressed by ciliated cells, where it was concentrated on the apical surface and within the cilia. Goblet cells and nondifferentiated basal epithelial cells did not stain. In the glands of the lamina propria, intense staining was found in the cytoplasm and in the nuclei of the cells in the duct epithelium, whereas acinar cells did not stain. Intense cytoplasmic staining was observed in infiltrating polymorphonuclear cells and macrophages. No differences in the pattern or the level of expression of annexin A1 were found in the epithelial cells and glands of normal and chronically inflamed (perennial rhinitis or polyps) nasal mucosa. CONCLUSION: These results suggest that the expression of annexin A1 in respiratory epithelium of nasal mucosa is related to cell type and differentiation status of the cells and is not significantly altered by inflammatory diseases.

Breakthroughs spotlighting roles for extracellular nucleotides and apyrases in stress responses and growth and development.

Animal and plant cells release nucleotides into their extracellular matrix when touched, wounded, and when their plasma membranes are stretched during delivery of secretory vesicles and growth. These released nucleotides then function as signaling agents that induce rapid increases in the concentration of cytosolic calcium, nitric oxide and superoxide. These, in turn, are transduced into downstream physiological changes. These changes in plants include changes in the growth of diverse tissues, in gravitropism, and in the opening and closing of stomates. The concentration of extracellular nucleotides is controlled by various phosphatases, prominent among which are apyrases EC 3.6.1.5 (nucleoside triphosphate diphosphohydrolases, NTPDases). This review provides phylogenetic and pHMM analyses of plant apyrases as well as analysis of predicted post-translational modifications for Arabidopsis apyrases. This review also summarizes and discusses recent advances in research on the roles of apyrases and extracellular nucleotides in controlling plant growth and development. These include new findings that document how apyrases and extracellular nucleotides control auxin transport, modulate stomatal aperture, and mediate biotic and abiotic stress responses, and on how apyrase suppression leads to growth inhibition.

Phosphorylation of CRN2 by CK2 regulates F-actin and Arp2/3 interaction and inhibits cell migration.

CRN2 (synonyms: coronin 1C, coronin 3) functions in the re-organization of the actin network and is implicated in cellular processes like protrusion formation, secretion, migration and invasion. We demonstrate that CRN2 is a binding partner and substrate of protein kinase CK2, which phosphorylates CRN2 at S463 in its C-terminal coiled coil domain. Phosphomimetic S463D CRN2 loses the wild-type CRN2 ability to inhibit actin polymerization, to bundle F-actin, and to bind to the Arp2/3 complex. As a consequence, S463D mutant CRN2 changes the morphology of the F-actin network in the front of lamellipodia. Our data imply that CK2-dependent phosphorylation of CRN2 is involved in the modulation of the local morphology of complex actin structures and thereby inhibits cell migration.

Particle repositioning maneuver versus Brandt-Daroff exercise for treatment of unilateral idiopathic BPPV of the posterior semicircular canal: a randomized prospective clinical trial with short- and long-term outcome.

OBJECTIVE: To compare the outcome and probability of recurrence in a series of patients with unilateral idiopathic benign paroxysmal positional vertigo of the posterior canal (PC-BPPV) that were randomly treated by Brandt-Daroff exercise (B-D exercise) or by particle repositioning maneuver (PRM). STUDY DESIGN: Randomized prospective clinical trial. SETTING: Tertiary referral center. PATIENTS: Patients were included in this study if they complained of vertigo and had been diagnosed as having unilateral idiopathic PC-BPPV for at least 1 week before Dix-Hallpike maneuver (DHM), remained for 30 days in the randomly assigned treatment, and had at least 48 months' follow-up. INTERVENTION: Forty-one patients were treated with a single PRM and 40 patients by B-D exercise. MAIN OUTCOME MEASURE: Resolution of benign paroxysmal positional nystagmus on the DHM. The probability of recurrence was also studied. RESULTS: At Day 7, DHM was negative in 80.5% of the PRM-treated patients and in 25% of those treated by B-D exercise (p < 0.001). At Month 1, the differences between both treatment groups remained statistically significant (92.7% in PRM versus 42.5% in the B-D exercise had a negative DHM; p < 0.001). The variable that influenced that DHM became negative was the PRM (RR = 4.8; 95% confidence interval, 2.5-9.2; p < 0.001). The number of recurrences in PRM and B-D exercise were 0.56 ± 0.8 and 0.48 ± 0.8, respectively (p = 0.48). The recurrence rate at 48 months was 35.5% (15/41) in B-D exercise and 36.6% (9/31) in the PRM group (p = 0.62). Although the time interval until the first recurrence was similar (p = 0.44), patients included in the PRM group showed a significantly longer time interval between the first and second recurrence (p = 0.04). CONCLUSION: PRM is more effective treatment and as safe as B-D exercise in the short term for unilateral and idiopathic PC-BPPV, and although it does not reduce the probability of recurrence in the 4-year follow-up period compared with B-D exercise, it may delay the second recurrence's onset in those patients who had already experienced a single recurrence. Our study supports the use of PRM as the treatment of choice in unilateral and idiopathic PC-BPPV, although exercise may be also considered as an alternative treatment in selected cases.

Structural and functional diversity of novel coronin 1C (CRN2) isoforms in muscle.

Coronin 1C (synonyms: coronin-3, CRN2), a WD40 repeat-containing protein involved in cellular actin dynamics, is ubiquitously expressed in human tissues. Here, we report on the identification and functional characterization of two novel coronin 1C isoforms, referred to as CRN2i2 and CRN2i3, which also associate with F-actin. Analyses of the coronin 1C gene disclosed a single promoter containing binding sites for myogenic regulatory factors and an alternative first exon 1b present in intron 1, which give rise to the novel isoforms. Chromatin immunoprecipitation studies demonstrate MyoD binding to a region of the CRN2 gene, which contains a highly conserved E-box element in exon 1a. Gel-filtration assays suggest that the largest isoform 3 exists as a monomer, in contrast to isoform 1 and isoform 2 appearing as trimers. CRN2i3, which can be induced by MyoD, is exclusively expressed in well-differentiated myoblasts as well as in mature skeletal muscle tissue. In human skeletal muscle, CRN2i3 is a novel component of postsynaptic neuromuscular junctions and thin filaments of myofibrils. Together, our findings postulate a role for CRN2 isoforms in the structural and functional organization of F-actin in highly ordered protein complexes.

[Larrad biliopancreatic diversion. Description of an rat experimental model]. / Derivación biliopancreática de Larrad. Descripción de un modelo experimental en la rata.

UNLABELLED: OBJECTIVE.: To validate the experimental model of Larrad-biliopancreatic diversion (LBPD) and to analyze weight gain and mortality in rats fed with non- supplemented diets. MATERIAL AND METHOD: Control (6) and experimental (10) male Wistar rats were used. The experimental group was operated on using the human LBPD adapted for rats: Subcardial gastrectomy, a short biliopancreatic channel created at 5 cm from Treitz angle and common channel at 5 cm from ileocecal valve. After surgery recovery (7 days) the rats were fed ab libitum with a standard non-supplemented diet (without proteins, minerals or vitamins). Percentage of weight lost or gained up to the end of the experiment was analyzed. RESULTS: The control animals gained weight progressively from 13.1 +/- 2.4% at day 7 to 58 +/- 9.2% at day 63, when the animals were sacrificed. After LBPD, mortality was 50% at day 25 +/- 17.5(range, 14-56), no significant differences in the percentage of weight lost being found between surviving (-38.9 +/- 14.2%) and non-surviving rats (-29 +/- 5.6%; p = 0.192). Of the surviving animals, 80% progressively lost weight reaching a maximum loss between day 63 (-42.3 +/- 8%) and 70 (-44.1 +/- 9.7%), and 20% lost weight until day 35 and gained over 7% of body weight until sacrifice (day 147). CONCLUSIONS: An experimental model of LBPD in rats is technically feasible. Both mortality and percentage weight loss are not directly related. The bowel adaptation mechanism could mediate the percentage of weight regain in operated rats.

Comparative genetics and evolution of annexin A13 as the founder gene of vertebrate annexins.

Annexin A13 (ANXA13) is believed to be the original founder gene of the 12-member vertebrate annexin A family, and it has acquired an intestine-specific expression associated with a highly differentiated intracellular transport function. Molecular characterization of this subfamily in a range of vertebrate species was undertaken to assess coding region conservation, gene organization, chromosomal linkage, and phylogenetic relationships relevant to its progenitor role in the structure-function evolution of the annexin gene superfamily. Protein diagnostic features peculiar to this subfamily include an alternate isoform containing a KGD motif, an elevated basic amino acid content with polyhistidine expansion in the 5'-translated region, and the conservation of 15% core tetrad residues specific to annexin A13 members. The 12 coding exons comprising the 58-kb human ANXA13 gene were deduced from BAC clone sequencing, whereas internal repetitive elements and neighboring genes in chromosome 8q24.12 were identified by contig analysis of the draft sequence from the human genome project. A unique exon splicing pattern in the annexin A13 gene was corroborated by coanalysis of mouse, rat, zebrafish, and pufferfish genomic DNA and determined to be the most distinct of all vertebrate annexins. The putative promoter region was identified by phylogenetic footprinting of potential binding sites for intestine-specific transcription factors. Mouse annexin A13 cDNA was used to map the gene to an orthologous linkage group in mouse chromosome 15 (between Sdc2 and Myc by backcross analysis), and the zebrafish cDNA permitted its localization to linkage group 24. Comparative analysis of annexin A13 from nine species traced this gene's speciation history and assessed coding region variation, whereas phylogenetic analysis showed it to be the deepest-branching vertebrate annexin, and computational analysis estimated the gene age and divergence rate. The unique, conserved aspects of annexin A13 primary structure, gene organization, and genetic maps identify it as the probable common ancestor of all vertebrate annexins, beginning with the sequential duplication to annexins A7 and A11 approximately 700 MYA, before the emergence of chordates.