Intrapulmonary artery Doppler to predict mortality and morbidity in fetuses with mild or moderate left-sided congenital diaphragmatic hernia.

OBJECTIVES: In fetuses with isolated left-sided congenital diaphragmatic hernia (LCDH), prenatal detection of severe pulmonary hypoplasia is important, as fetal therapy can improve survival. Cases with mild or moderate lung hypoplasia still carry a considerable risk of mortality and morbidity, but there has been less interest in the accurate prediction of outcome in these cases. In this study of fetuses with mild or moderate isolated LCDH, we aimed to investigate: (1) the association between intrapulmonary artery (IPA) Doppler findings and mortality at discharge; (2) whether adding IPA Doppler findings improves the prediction of mortality based on lung size and liver herniation; and (3) the association between IPA Doppler findings and early neonatal morbidity. METHODS: This was a retrospective study of all consecutive fetuses assessed at the BCNatal and UZ Leuven hospitals between 2008 and 2020 with a prenatal diagnosis of isolated, non-severe LCDH, defined as observed-to-expected lung-to-head ratio (o/e-LHR) > 25%, that were managed expectantly during pregnancy followed by standardized neonatal management. An additional inclusion criterion was the availability of IPA Doppler measurements. The primary outcome was the association between IPA Doppler findings and mortality at discharge. Other predictors included o/e-LHR, liver herniation and gestational age at birth. Secondary outcomes were the association between IPA Doppler findings and the presence of pulmonary hypertension (PHT), need for supplemental oxygen at discharge and need for extracorporeal membrane oxygenation. IPA pulsatility index (PI) values were converted into Z-scores. Logistic regression analysis was performed to investigate the associations between predictor variables and outcome, and the best model was chosen based on the Nagelkerke R2 . RESULTS: Observations for 70 non-severe LCDH cases were available. Fifty-four (77%) fetuses survived until discharge. On logistic regression analysis, higher IPA-PI was associated with an increased risk of mortality (odds ratio (OR), 3.96 (95% CI, 1.62-9.70)), independently of o/e-LHR (OR, 0.87 (95% CI, 0.79-0.97)). An IPA-PI Z-score cut-off of 1.8 predicted mortality with a detection rate of 69% and specificity of 93%. Adding IPA-PI to o/e-LHR improved significantly the model's performance (Nagelkerke R2 , 46% for o/e-LHR + IPA-PI vs 28% for o/e-LHR (P < 0.002)), with a detection rate of 81% at a 10% false-positive rate. IPA-PI was associated with PHT (OR, 2.20 (95% CI, 1.01-4.59)) and need for oxygen supplementation at discharge (OR, 1.90 (95% CI, 1.10-3.40)), independently of lung size. CONCLUSIONS: In fetuses with mild or moderate LCDH, IPA-PI was associated with mortality and morbidity, independently of lung size. A model combining o/e-LHR with IPA-PI identified up to four in five cases that eventually died, despite being considered to have non-severe pulmonary hypoplasia. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal endoscopic tracheal occlusion reverses the natural history of right-sided congenital diaphragmatic hernia: European multicenter experience.

OBJECTIVE: To evaluate the neonatal outcome of fetuses with isolated right-sided congenital diaphragmatic hernia (iRCDH) based on prenatal severity indicators and antenatal management. METHODS: This was a retrospective review of prospectively collected data on consecutive cases diagnosed with iRCDH before 30 weeks' gestation in four fetal therapy centers, between January 2008 and December 2018. Data on prenatal severity assessment, antenatal management and perinatal outcome were retrieved. Univariate and multivariate logistic regression analysis were used to identify predictors of survival at discharge and early neonatal morbidity. RESULTS: Of 265 patients assessed during the study period, we excluded 40 (15%) who underwent termination of pregnancy, two cases of unexplained fetal death, two that were lost to follow-up, one for which antenatal assessment of lung hypoplasia was not available and six cases which were found to have major associated anomalies or syndromes after birth. Of the 214 fetuses with iRCDH included in the neonatal outcome analysis, 86 were managed expectantly during pregnancy and 128 underwent fetal endoscopic tracheal occlusion (FETO) with a balloon. In the expectant-management group, lung size measured by ultrasound or by magnetic resonance imaging was the only independent predictor of survival (observed-to-expected lung-to-head ratio (o/e-LHR) odds ratio (OR), 1.06 (95% CI, 1.02-1.11); P = 0.003). Until now, stratification for severe lung hypoplasia has been based on an o/e-LHR cut-off of 45%. In cases managed expectantly, the survival rate was 15% (4/27) in those with o/e-LHR ≤ 45% and 61% (36/59) for o/e-LHR > 45% (P = 0.001). However, the best o/e-LHR cut-off for the prediction of survival at discharge was 50%, with a sensitivity of 78% and specificity of 72%. In the expectantly managed group, survivors with severe pulmonary hypoplasia stayed longer in the neonatal intensive care unit than did those with mildly hypoplastic lungs. In fetuses with an o/e-LHR ≤ 45% treated with FETO, survival rate was higher than in those with similar lung size managed expectantly (49/120 (41%) vs 4/27 (15%); P = 0.014), despite higher prematurity rates (gestational age at birth: 34.4 ± 2.7 weeks vs 36.8 ± 3.0 weeks; P < 0.0001). In fetuses treated with FETO, gestational age at birth was the only predictor of survival (OR, 1.25 (95% CI, 1.04-1.50); P = 0.02). CONCLUSIONS: Antenatal measurement of lung size can predict survival in iRCDH. In fetuses with severe lung hypoplasia, FETO was associated with a significant increase in survival without an associated increase in neonatal morbidity. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

[When should gestation of a gastroschisis be terminated?] / ¿Cuándo debe terminarse la gestación de una gastrosquisis?

OBJECTIVES: In gastroschisis pregnancies, a) to correlate prenatal ultrasound variables with postnatal outcome and b) to determine the ideal time for setting the delivery in order to achieve the best neonatal outcome. MATERIAL AND METHODS: Retrospective review (2000-2015) of all available gastroschisis whose prenatal findings could be correlated with the neonatal outcome. Two study groups have been defined according to the complications present after birth: favorable gastrosquisis and complicated. Prenatal variables were compared by groups using McWhitney or Chi tests as needed. RESULTS: Twenty-two gastroschisis fulfilled the requirement. Twelve cases had uneventful outcomes. Ten patients experienced complications, including death in five. In the complicated group there were 15 episodes of sepsis and 17 reoperations. Any single ultrasound parameter could predict a bad follow up. In thirteen cases, delivery was forced due to sudden changes on ultrasound bowel appearance. Nine of these patients had very good neonatal outcome. CONCLUSIONS: Finishing pregnancy when sudden changes on the fetal bowel were identified was the only strategy that leaded us to diminish the complication rate in gastroschisis.

OBJETIVOS: En las gestaciones con gastrosquisis, a) valorar la presencia de algún dato ecográfico prenatal que pueda predecir la evolución postnatal de la gastrosquisis, y b) determinar el momento ideal del nacimiento de los pacientes con gastrosquisis que se relacione con una mejor evolución postnatal. MATERIAL Y METODOS: Revisión retrospectiva (2000-2015) de las gastrosquisis cuyos datos ecográficos prenatales hemos podido relacionar con las características de los pacientes y su evolución clínica posterior. Se han determinado dos grupos en función de la evolución favorable o complicada de la gastrosquisis. Todas las variables ecográficas prenatales se han comparado entre grupos según los test de McWitney o Chi cuadrado. RESULTADOS: Veintidós gastrosquisis cumplieron el requisito anterior. Doce casos tuvieron una evolución sin incidencias significativas. Diez pacientes tuvieron una evolución complicada, de los cuales cinco fueron exitus. En este grupo hubo 15 episodios de sepsis y 17 reintervenciones. Ningún parámetro ecográfico prenatal predijo con fiabilidad una evolución desfavorable. En 13 casos se finalizó la gestación porque aparecieron cambios súbitos en la ecografía. Nueve de estos pacientes evolucionaron sin ninguna complicación. CONCLUSIONES: Terminar la gestación cuando se produce un cambio súbito de la apariencia ecográfica de los intestinos fetales es la única estrategia que nos ha permitido disminuir la incidencia de complicaciones en los pacientes con gastrosquisis.

Case report: Orbital epithelioid haemangioendothelioma. / Caso clínico: hemangioendotelioma epitelioide orbitario.

CASE REPORT: A 13-year-old boy presented with right eye proptosis and lateral dystopia. A soft non-pulsatile mass was found in the superomedial orbital region. An excisional biopsy was performed, for which the histopathology reported an epithelioid haemangioendothelioma. DISCUSSION: Haemangioendothelioma is a borderline vascular lesion within the spectrum of clinically benign and malignant tumours. These can arise from soft tissue or bone. There are few reports of these tumours located in the orbit.

Orbital liposarcoma. / Liposarcoma de la órbita.

CASE REPORT: The case is presented of a 46-year-old male with right eye proptosis and conjunctival hyperaemia, of 18 months onset. A well-defined intraconal mass was found in the computed tomography. In magnetic resonance this was hypo-intense on T1, enhanced with gadolinium and hyperintense on T2. Excisional biopsy was performed, which was reported as a well-differentiated liposarcoma in the histopathology study. DISCUSSION: Liposarcoma is a malignant adipose tissue tumour. It is very rare in the orbit, with 5 histological types, the most common being myxoid. The treatment of choice is wide surgical excision and may be accompanied with radiotherapy. As it is an infiltrative tumour, It has a high rate of recurrence.

[Eye and systemic manifestations of Mobius syndrome]. / Manifestaciones oculares y sistémicas del síndrome de Möebius.

INTRODUCTION: Mobius syndrome is characterized by damage in the nucleus of the sixth and seventh cranial nerves, with subsequent facial palsy and abduction limitation of the eyes. The aim of this article is to describe the ophthalmological findings of the Mobius syndrome in Mexican children. PATIENTS AND METHODS: A cross-sectional, retrospective, observational and descriptive study was conducted. A review was made of the clinical charts of patients with Mobius syndrome who were seen in the National Institute of Pediatrics in Mexico, between the years 2000 and 2010. RESULTS: A total of 64 charts were reviewed. The most important findings were eye abduction limitation (100%), facial palsy (100%), esotropia (54%), epicanthus (51.5%), entropion (22%), and history of use of abortion inducers in the mother in the first trimester of pregnancy (28%). We also found exotropia and hypertropia in some cases. CONCLUSIONS: Mobius syndrome has a wide spectrum of ophthalmological manifestations that are important to detect early in order to improve function and esthetics.

[Bilateral persistent hyaloid artery. A case report]. / Persistencia bilateral de la arteria hialoidea. Reporte de un caso.

CASE REPORT: A 5-year-old male presented with bilateral poor vision, esotropia and a previous diagnosis of cataract since he was 1 year old. The physical examination revealed bilateral posterior paracentric capsule opacification, vitreous cavity with a permeable pulsatile blood filled hyaloid artery in both eyes. He was kept under observation. DISCUSSION: Persistent hyaloid artery is an uncommon faulty primary vitreous regression, often unilateral (although it may be bilateral) and sporadic, associated with microphthalmos. It may be complicated with glaucoma and phthisis bulbi. Vitrectomy plus lensectomy or simple observation are the accepted treatment options.

Interleukin-1 gene polymorphisms and periodontal status in a Spanish population.

The aim of this study was to investigate the possible association between interleukin (IL)-1A (+4845) and/or IL-1B (+3954) gene polymorphisms and the onset and progression of chronic periodontal disease (PD), an issue that remains controversial. The relationship between IL-1ß concentration in the gingival crevicular fluid (GCF) and disease activity was also evaluated. The study was performed on 25 individuals with no gingivitis or PD and on 25 subjects with active chronic PD. Two samples of GCF were obtained from each subject and IL-1ß was determined by enzyme-linked immunoabsorbent assay. Blood samples (10 ml) were drawn from each subject to detect polymorphisms in IL-1A (+4845) and IL-1B (+3954) by polymerase chain reaction. Mean GCF IL-1ß concentrations were higher in patients with active chronic PD compared to the control group. No significant association was found in either group between GCF IL-1ß concentration and the presence of polymorphisms in IL-1A (+4845), IL-1B (+3954) or both genotypes. No significant difference was found in either group with regard to the presence of polymorphisms in IL-1A (+4845), IL-1B (+3954) or both genotypes (p=0.556). The concentration of IL-1ß in GCF was almost 2-fold higher in patients with chronic PD than in the healthy individuals. The presence of polymorphisms in IL-1A (+4845) and/or IL-1B (+3954) genotypes is not associated with IL-1ß overproduction in GCF and is not a risk factor for chronic PD. IL-1ß is considered a suitable marker of the severity and progression of chronic PD. The presence of IL-1A (+4845) and/or IL-1B +3954 gene polymorphisms does not appear to be a risk factor for chronic PD. Therefore, the IL-1A (+4845) and/or IL-1B +3954 gene polymorphisms cannot be considered genetic markers of chronic PD. Moreover, these polymorphisms do not indicate an overproduction of IL-1ß in GCF.

[Utility of the ECMO in patients with congenital diaphragmatic hernia]. / Utilidad de la ECMO en pacientes con hernia diafragmática congénita.

At the moment the extracorporeal membrane oxygenation (ECMO) constitutes the last link in the therapeutic one of the handling of the respiratory failure in patients with Congenital Diaphragmatic Hernia (HDC). We presented our experience. From January 2001 we arrange the ECMO in neonative UCI. 76 HDC, 13 (3 rights and 10 lefts) they have needed ECMO (one in two occasions; altogether 14 procedures). Criteria of inclusion: refractory hypoxaemia, oxigenaction index > 40 and weight > 2 kg. 5 girls and 8 boys with gestacional age between 35 and 41 weeks (average: 38) and weight when being born between 2,300 and 3,500 grams (average 2,817). In 6 cases (5 transferred from other centers) the diagnosis was posnatal. Of the 7 with prenatal diagnosis, in 4 cases fetal therapy by means of traqueal occlusion had been made. Veno-venous in 8 and veno-arterial procedure in 5. Rank of duration: 68-606 hours, average of 228.35. The surgery has been made before the ECMO in 9 cases, 2 during and 1 later. In an occasion there was no surgery. The complications have been of hemorrágico type in one patient and infectious in three cases with sudden sepsis in one. Precocious mortality has been of 6 patients and delayed the 2 (total 61%). Although this procedure has the high morbi-mortality, it is necessary to consider that is patients very badly prognosis without another alternative (with mortality of the 100%). Multicentric studies are needed to establish indicators prognoses pre and postbirthdays.

Induction of the halobenzoate catabolic pathway and cometabolism of ortho-chlorobenzoates in Pseudomonas aeruginosa 142 grown on glucose-supplemented media.

The aerobic cometabolism of ortho-substituted chlorobenzoates by Pseudomonas aeruginosa strain 142 growing on glucose-supplemented medium was analyzed. The strain, which can use 2-chlorobenzoate (2-CBA) and 2,4-dichlorobenzoate (2,4-DCBA) as sole carbon and energy sources, showed high rates of 2-CBA metabolism in glucose-fed cells. In contrast, 2,4-DCBA was metabolized only after extended incubation of the full grown culture and depletion of glucose. In addition to the ortho-dehalogenation (ohb142) genes encoding the alpha and beta subunits of the oxygenase component of a 2-halobenzoate dioxygenase, strain 142 harbours a closely related ohbABCDFG gene cluster previously identified in P. aeruginosa JB2 (ohbJB2). The genes for the chlorocatechol ortho-catabolic pathway were identified and sequenced in this strain, showing a near complete identity with the clcABD operon of the pAC27 plasmid. Relative quantification of mRNA by RT-PCR shows a preferential induction of ohb142 by 2-CBA, which is abolished in glucose-grown cultures. The alternate ohbJB2 and clc genes were expressed preferentially in 2,4-DCBA grown cultures. Only ohbJB2 appears to be expressed in the presence of the carbohydrate. Detection of chlorocatechol-1,2-dioxygenase activity in 2,4-DCBA plus glucose grown cultures suggests the presence of an alternate system for the ortho-cleavage of chlorobenzoates. The recruitment of elements from two halobenzoate dioxygenase systems with different induction patterns, together with a chlorocatechol degradative pathway not repressed by carbon catabolite, may allow P. aeruginosa 142 to cometabolize haloaromatics in carbohydrate grown cultures.

Gastrointestinal helminths of Commerson's dolphins Cephalorhynchus commersonii from central Patagonia and Tierra del Fuego.

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.

[Factors associated with arterial distensibility in hypertension]. / Factores relacionados con la distensibilidad arterial en la hipertensión.

OBJECTIVE: To find out what variables affect changes in arterial compliance in subjects with hypertension by measuring their pulse wave velocity (PWV). DESIGN: Cross-sectional, descriptive study. SETTING: Rural health centre. PATIENTS: 156 hypertense patients under 76, chosen by simple random sampling from those on the hypertension register. MEASUREMENTS AND INTERVENTIONS: We determined the degree of hypertension, years of evolution, systolic pressure (SBP), diastolic pressure (DBP), body mass index (BMI), glucaemia, whether lipaemia existed, diabetes or glucose intolerance, tobacco habit, age, sex and PWV (measured automatically by computer). We performed multivariate analysis by means of multiple linear regression, with PWV as the dependent variable, and age, SBP, DBP, BMI, years of evolution of hypertension, cholesterol, triglycerides and glucaemia as independent variables. RESULTS: Mean age 62.5 (SD 8.8). 28.2% male. Mean SBP 153 (SD 18.9). Mean DBP 87 (SD 10.3). Mean years of evolution 10.4 (SD 7.4). Mean BMI 31.2 (SD 4.9). Hyperglucaemia 24.4%. Mean glucaemia 111.3 (SD 29). Mean PWV 11.82 (SD 2.37). PWV was above the theoretically normal figures in 69.2% of cases. Multiple linear regression showed that the variables which affected PWV significantly were age, SBP and hyperglucaemia. CONCLUSIONS: Arterial compliance can be improved by controlling SBP, given that the other related factors cannot be changed.

Covalent and metal-chelate immobilization of a modified 2-haloacid dehalogenase for the enzymatic resolution of optically active chloropropionic acid.

The stereospecific L-2-haloacid dehalogenase DehCI from Pseudomonas CBS3 was tagged with a peptide tail containing six histidines and overexpressed in Escherichia coli. The His-tagged protein was purified after a single-step affinity chromatography on Zn(2+)-chelating sepharose. The activity of the modified protein was tested after immobilization on Zn(2+)-chelating sepharose and on covalently bound acrylic polymer. Both immobilization systems were used for the transformation of racemic 2-chloropropionic acid into D-lactate and D-chloropropionic acid. Although immobilization on chelating sepharose produced a limited increase in stability, covalent immobilization on acrylic polymer significantly extended the operational temperature and pH range of the enzyme: up to 60% of activity was recovered at either 80 degrees C or pH 11, whereas no activity could be detected under these conditions in the soluble or chelate-immobilized enzyme. Both forms of immobilization extended the enzyme effective storage periods, and after 10 cycles of reutilization, 70% and 20% of the initial activity was recovered in the covalent- and chelate-immobilized enzyme, respectively.

Structural defects underlying protein dysfunction in human glucose-6-phosphate dehydrogenase A(-) deficiency.

The enzyme variant glucose-6-phosphate dehydrogenase (G6PD) A(-), which gives rise to human glucose-6-phosphate dehydrogenase deficiency, is a protein of markedly reduced structural stability. This variant differs from the normal enzyme, G6PD B, in two amino acid substitutions. A further nondeficient variant, G6PD A, bears only one of these two mutations and is structurally stable. In this study, the synergistic structural defect in recombinant G6PD A(-) was reflected by reduced unfolding enthalpy due to loss of beta-sheet and alpha-helix interactions where both mutations are found. This was accompanied by changes in inner spatial distances between residues in the coenzyme domain and the partial disruption of tertiary structure with no significant loss of secondary structure. However, the secondary structure of G6PD A(-) was qualitatively affected by an increase in beta-sheets substituting beta-turns related to the lower unfolding enthalpy. The structural changes observed did not affect the active site of the mutant proteins, since its spatial position was unmodified. The final result is a loss of folding determinants leading to a protein with decreased intracellular stability. This is suggested as the cause of the enzyme deficiency in the red blood cell, which is unable to perform de novo protein synthesis.

Molecular phylogeny and morphological homoplasy in fruitbats.

The present study evaluates the evolutionary framework of the Old World fruitbats based on the cytochrome b and 16S rRNA mitochondrial gene sequences from a wide range of taxa. Phylogenetic analyses indicated that morphology-based subfamilies and most suprageneric groups are nonnatural assemblages. They also support the existence of an endemic African clade of fruitbats. The discrepancy between the evolutionary relationships yielded by molecular and morphological data sets may be, at least in part, explained by the recurrent retention of primitive morphology (Rousettus-like) across different lineages. The maintenance of primitive characters in different groups of flying foxes, as well as morphological convergence in nectar-feeding bats and possibly also in short-muzzle bats, may have led to high levels of homoplasy, resulting in misleading taxonomic arrangements. This may be particularly so with respect to high taxonomic levels based on morphological characters.

Phylogeography of African fruitbats (Megachiroptera).

Joint sequences from the mitochondrial cytochrome b and 16S rRNA genes of a wide representation of Megachiroptera were employed to evaluate the traditional taxonomic arrangement of African fruitbats and to examine their origins and evolutionary relationships. The resulting phylogenetic hypotheses are inconsistent with the previously established morphology-based subdivisions of Megachiroptera at the suprageneric level. Findings indicate the existence of an African clade, which appears to be formed by two endemic clades: the epomophorines and the myonycterines. According to our topologies, the genus Rousettus is monospecific in mainland Africa. Its traditional subgenera Stenonycteris and Lissonycteris appear closer to the myonycterines than to Rousettus. Topologies also indicate that the African genus Eidolon is not phylogenetically related to any other African fruitbat. It would seem that the arrival of fruitbats in Africa was a complex process involving at least three independent colonization events. One event took place probably in the Miocene via forested corridors that connected the African and Asian rain forest blocks, as for other groups of mammals. The resulting lineage diversified into most of the extant African fruitbats. Related to this clade, the Rousettus species group is thought to have arrived in Africa in more recent times, possibly by progressive displacement from the East through India. Finally, the present topologies suggest an independent colonization of Africa by ancestors of Eidolon.

Unproductive folding of the human G6PD-deficient variant A-.

Human glucose-6-phosphate dehydrogenase (G6PD) deficiency almost invariably results from the presence of missense mutations in the X-linked gene encoding G6PD. The common African deficient variant G6PD A- differs from the normal G6PD B by two amino acid substitutions. Only one of these mutations is found on its own, resulting in the nondeficient variant G6PD A. Deficiency is always associated with decreased G6PD activity in red cells, leading to a variety of clinical manifestations. A group of deficient variants, including A-, have near-normal affinity for the substrates G6P and NADP. In these cases, deficiency is caused by a decreased number of catalytically active molecules per cell due to intracellular instability of the mutated G6PD, although the mechanism for this in vivo instability is unknown. Here we report that in vitro folding of the A- variant mainly renders partially folded polypeptides that do not undergo the dimerization required for activity. Under the same conditions, the nondeficient variants B and A undergo folding to produce active dimers with normal mobilities in native gels and normal kinetic properties. The loss of intrinsic folding determinants in the A- variant may underlie the mechanism of its in vivo instability.

The complete nucleotide sequence of the mitochondrial DNA genome of the rainbow trout, Oncorhynchus mykiss.

The complete nucleotide sequence of the mitochondrial DNA of the rainbow trout, Onchorynchus mykiss, has been determined. The total length of the molecule is 16,660 bp. The rainbow trout mitochondrial DNA has the same organization described in eutherian mammals, the clawed frog (Xenopus laevis), and the two fish species, Oriental stream loach (Crossotoma lacustre) and carp (Cyprinus carpio). Alignment and comparison of the deduced amino acid sequences of the 13 proteins encoded by rainbow trout and other vertebrate mitochondrial genomes allowed us to estimate that COI is the most conserved mitochondrial subunit (amino acid identity ranging from 85.6% to 94.8%) whereas ATPase 8 is the most variable one (amino acid identity ranging from 30.8% to 70.4%). Putative secondary structures for the 22 tRNAs found in the molecule are given along with an extensive comparison of tRNA sequences among representative species of each major group of vertebrates. In this sense, an unusual cloverleaf structure for the tRNASer(AGY) is proposed. A stem-loop structure inferred for the origin of the L-strand replication (OL) and the presence of a large polycytidine tract in the OL loop is described. The existence of this stretch instead of the usual T-rich sequence reported so far in mammal mtDNAs is explained in terms of a less-strict template dependence of the RNA primase involved in the initiation of L-strand replication.

Revised dinoflagellate phylogeny inferred from molecular analysis of large-subunit ribosomal RNA gene sequences.

The nucleotide sequence analysis of the PCR products corresponding to the variable large-subunit rRNA domains D1, D2, D9, and D10 from ten representative dinoflagellate species is reported. Species were selected among the main laboratory-grown dinoflagellate groups: Prorocentrales, Gymnodiniales, and Peridiniales which comprise a variety of morphological and ecological characteristics. The sequence alignments comprising up to 1,000 nucleotides from all ten species were employed to analyze the phylogenetic relationships among these dinoflagellates. Maximum parsimony and neighbor-joining trees were inferred from the data generated and subsequently tested by bootstrapping. Both the D1/D2 and the D9/D10 regions led to coherent trees in which the main class of dinoflagellates. Dinophyceae, is divided in three groups: prorocentroid, gymnodinioid, and peridinioid. An interesting outcome from the molecular phylogeny obtained was the uncertain emergence of Prorocentrum lima. The molecular results reported agreed with morphological classifications within Peridiniales but not with those of Prorocentrales and Gymnodiniales. Additionally, the sequence comparison analysis provided strong evidence to suggest that Alexandrium minutum and Alexandrium lusitanicum were synonymous species given the identical sequence they shared. Moreover, clone Gg1V, which was determined Gymnodinium catenatum based on morphological criteria, would correspond to a new species of the genus Gymnodinium as its sequence clearly differed from that obtained in G. catenatum. The sequence of the amplified fragments was demonstrated to be a valuable tool for phylogenetic and taxonomical analysis among these highly diversified species.