Bioaccumulation and retention of lead in the mussel Mytilus galloprovincialis following uptake from seawater

PURPOSE: We compared two groups of risk patients to try to identify different radiologic patterns in pulmonary tuberculosis. MATERIALS AND METHODS: 74 subjects, divided into two groups (HIV+:27; HIV-:47) were included since 1993. The patients were examined with chest X-ray (CXR) and CT. RESULTS: In the HIV+ group we observed 40 radiologic alterations, with 6 cases of bilateral lung involvement and 9 of atypical localizations; particularly: 11 consolidations, 8 cavitations, 5 miliary diseases, 9 hilar or mediastinal adenopathies, 3 extrapulmonary localizations and 4 negative CXRs. In the HIV- group we found 53 radiologic alterations, with 6 cases of bilateral lung involvement and 3 of atypical localizations; particularly: 12 consolidations, 25 cavitations, 5 nodular patterns, 1 miliary disease, 5 nodal disease, 4 pleural diseases and 1 negative CRX. DISCUSSION AND CONCLUSIONS: In HIV- patients lung consolidations and tysiogen patterns are significantly prevalent, while miliary diseases, mediastinal diseases and atypical localizations and negative CRXs are more frequent in HIV+ patients. We found miliary diseases, mediastinal diseases and extrapulmonary localizations also in HIV- patients with heavily impaired social, economic and sanitary conditions. This alterations indicate compromised host resistance, independent of the causes and modalities of immunodeficiency. The distinction between primary and secondary tuberculosis is currently not mandatory.     

Structure and differential target sensitivity of the stimulable cytotoxic complex from hemolymph of the Mediterranean mussel Mytilus galloprovincialis

Radiation therapy has been for years the treatment of choice of locally advanced non small cell lung cancer. Improvement due to the combination of radiation and chemotherapy has been shown recently through several randomized trials and a recent meta-analysis. These results may be explained by biological mechanisms, yet uncompletely explored, which are detailed in this review and applied to lung cancer. The optimal combination scheme is not yet defined, even though the concurrent approach is promising, at the expense of an increased toxicity which is the limiting factor of treatment escalation doses. Biological findings and future results of randomized trials will hopefully open new avenues in the therapeutic strategy of this poor prognosis disease.     

Species-specific segregation of gender-associated mitochondrial DNA types in an area where two mussel species (Mytilus edulis and M. trossulus) hybridize

In each of the mussel species Mytilus edulis and M. trossulus there exist two types of mtDNA, the F type transmitted through females and the M type transmitted through males. Because the two species produce fertile hybrids in nature, F and M types of one may introgress into the other. We present the results from a survey of a population in which extensive hybridization occurs between these two species. Among specimens classified as "pure" M. edulis or "pure" M. trossulus on the basis of allozyme analysis, we observed no animal that carried the F or the M mitotype of the other species. In most animals of mixed nuclear background, an individual's mtDNA came from the species that contributed the majority of the individual's nuclear genes. Most importantly, the two mtDNA types in post-F1 male hybrids were of the same species origin. We interpret this to mean that there are intrinsic barriers to the exchange of mtDNA between these two species. Because such barriers were not noted in other hybridizing species pairs (many being even less interfertile than M. edulis and M. trossulus), their presence in Mytilus could be another feature of the unusual mtDNA system in this genus.     

In vivo phosphorylation of phosphofructokinase from the bivalve mollusk Mytilus galloprovincialis

The objective of this study was to determine whether progesterone prevents the stimulatory effects of oestradiol on GnRH receptor gene expression. In Expt 1, ewes were treated during the luteal phase (days 10-12 of the oestrous cycle) with either one or five subcutaneous implants containing oestradiol (n = 6 per group). Control ewes received no treatment (n = 6). Anterior pituitary glands were collected 16 h after treatment with oestradiol. Steady-state amounts of GnRH receptor mRNA were similar among all three treatment groups despite increased circulating concentrations of oestradiol in implanted ewes at the time of pituitary collection (4.3 +/- 0.6 and 24.7 +/- 2.6 pg ml-1 in ewes treated with one or five implants, respectively, compared with 0.5 pg ml-1 in controls). Experiment 2 was designed to determine whether progesterone was the ovarian factor preventing the stimulatory effects of oestradiol on expression of the GnRH receptor gene in Expt 1. Twenty-five ewes were ovariectomized on day 6 or day 7 of the oestrous cycle and assigned to one of five treatment groups (n = 5 per group). Control ewes received no further treatment. Endogenous luteal phase concentrations of progesterone were replaced in three groups of ewes at the time of ovariectomy via intravaginal implants. Three days after ovariectomy, one group of progesterone-treated ewes received one oestradiol implant, while another group of progesterone-treated ewes received five oestradiol implants. An additional group was treated with five oestradiol implants only, and anterior pituitary glands were collected from all ewes 16 h later. Compared with untreated ovariectomized ewes, treatment with progesterone alone did not affect amounts of GnRH receptor mRNA. In ewes treated with progesterone and either one or five oestradiol implants, steady-state amounts of GnRH receptor mRNA were increased twofold (P < 0.01). Treatment with oestradiol in the absence of progesterone increased amounts of GnRH receptor mRNA threefold (P < 0.001). These results provide evidence that the stimulatory effects of oestradiol on the expression of the GnRH receptor gene are prevented during the natural luteal phase in ewes. However, progesterone does not appear to act independently to mediate this effect.     

Phylogenetic evidence for role-reversals of gender-associated mitochondrial DNA in Mytilus (Bivalvia: Mytilidae)

Distinct gender-associated mitochondrial DNA (mtDNA) lineages (i.e., lineages which are transmitted either through males or through females) have been demonstrated in two families of bivalves, the Mytilidae (marine mussels) and the Unionidae (freshwater mussels), which have been separated for more than 400 Myr. The mode of transmission of these M (for male-transmitted) and F (for female-transmitted) molecules has been referred to as doubly uniparental inheritance (DUI), in contrast to standard maternal inheritance (SMI), which is the norm in animals. A previous study suggested that at least three origins of DUI are required to explain the phylogenetic pattern of M and F lineages in freshwater and marine mussels. Here we present phylogenetic evidence based on partial sequences of the cytochrome c oxidase subunit I gene and the 16S RNA gene that indicates the DUI is a dynamic phenomenon. Specifically, we demonstrate that F lineages in three species of Mytilus mussels, M. edulis, M. trossulus, and M. californianus, have spawned separate lineages which are now associated only with males. This process is referred to as "masculinization" of F mtDNA. By extension, we propose that DUI may be a primitive bivalve character and that periodic masculinization events combined with extinction of previously existing M types effectively reset the time of divergence between conspecific gender-associated mtDNA lineages.     

Polymorphic sites in human mitochondrial DNA control region sequences: population data and maternal inheritance

Short-circuit current (Isc), transepithelial conductance (Gt), electrical capacitance (CT) and the fluctuation in Isc were analyzed in polarized epithelial cells from the distal nephron of Xenopus laevis (A6 cell line). Tissues were incubated with Na+- and Cl--free solutions on the apical surface. Basolateral perfusate was NaCl-Ringer. Agents that increase cellular cAMP evoked increases in Gt, CT, Isc and generated a Lorentzian Isc-noise. The responses could be related to active, electrogenic secretion of Cl-. Arginine-vasotocin and oxytocin caused a typical peak-plateau response pattern. Stimulation with a membrane-permeant nonhydrolyzable cAMP analogue or forskolin showed stable increases in Gt with only moderate peaking of Isc. Phosphodiesterase inhibitors also stimulated Cl- secretion with peaking responses in Gt and Isc. All stimulants elicited a spontaneous Lorentzian noise, originating from the activated apical Cl- channel, with almost identical corner frequency (40-50 Hz). Repetitive challenge with the hormones led to a refractory behavior of all parameters. Activation of the cAMP route could overcome this refractoriness. All agents caused CT, a measure of apical membrane area, to increase in a manner roughly synchronous with Gt. These results suggest that activation of the cAMP-messenger route may, at least partly, involve exocytosis of a vesicular Cl- channel pool. Apical flufenamate depressed Cl- current and conductance and apparently generated blocker-noise. However, blocking kinetics extracted from noise experiments could not be reconciled with those obtained from current inhibition, suggesting the drug does not act as simple open-channel inhibitor.     

Recognition of a 31,000 molecular weight protein synthesized by the mussel Mytilus galloprovincialis Lmk. during Dinophysis spp. algal bloom in the Gulf of Trieste (upper Adriatic Sea)

OBJECTIVES: To demonstrate gastroesophageal reflux induced by proximal gastrectomy and to report preventive measures, such as total gastrectomy followed by Roux-en-Y esophagojejunostomy. METHODS: Thirteen patients underwent proximal gastrectomy (PG), and six patients underwent total gastrectomy (TG). Two of the 13 patients who received PG later underwent completion total gastrectomy. All patients were followed with endoscopy, radionuclide scintigraphy, and 24-h pH monitoring. RESULTS: Endoscopic examination revealed evidence of esophagitis in all PG group patients; however, none of the TG group had esophagitis. Prolonged esophageal transit was observed in 11 patients (10 in the PG group, one in the TG group). Increased residual fraction was found in 10 patients (nine in the PG group, one in the TG group). An increase in the retrograde index was found in 14 cases (11 in the PG group, three in the TG group). Positive enterogastroesophageal reflux was identified in 11 patients (eight in the PG group, three in the TG group). Twenty-four hour pH monitoring resulted in 10 positives (10 in the PG group, none in the TG group). CONCLUSIONS: Frequently, proximal gastrectomy will lead to significant gastroesophageal reflux and, subsequently, to varying degrees of esophagitis. The clinical symptoms are usually characteristic. However, the severity of esophagitis and the mechanism of reflux can be determined only by integrated interpretation of a reflux study. The study should include endoscopy, radionuclide scintigraphy, and 24-h pH monitoring. Although a total gastrectomy with Roux-en-Y diversion can reduce the incidence of acid reflux, neutral enteroesophageal reflux may be observed during a radioactive isotope study. Fortunately, neutral refluxes rarely cause esophagitis. A proximal gastrectomy should be avoided in adenocarcinoma of the gastric cardia, except in early cancer. Symptomatic palliation can be relieved by medication. However, completion total gastrectomy is the only effective method for eradicating unrelenting symptoms.     

Phosphofructokinase from mantle tissue of Mytilus galloprovincialis. Purification and effects of phosphorylation on the enzymatic activity

Phosphofructokinase purified from mantle tissue of the sea mussel Mytilus galloprovincialis, was phosphorylated "in vitro" by the catalytic subunit of cyclic AMP-dependent protein kinase. The incorporation of phosphate gave rise to an activation of the enzyme by increasing its affinity for fructose-6-phosphate, by decreasing its sensitivity to the inhibition by ATP and by enhancing the effect of allosteric activators (5'-AMP and fructose-2,6-bisphosphate). In addition, the effects of phosphorylation on the catalytic activity are pH-dependent.     

A mating type-linked gene cluster expressed in Chlamydomonas zygotes participates in the uniparental inheritance of the chloroplast genome

A characteristic feature of early zygote development in Chlamydomonas is the selective degradation of chloroplast DNA from the mating type minus parent. The zygote-specific gene cluster ezy-1 is linked to the mating type locus and is transcribed almost immediately upon zygote formation. We show here that the acidic Ezy-1 polypeptide is rapidly transported to both the plus and minus chloroplasts, where it interacts with each chloroplast nucleoid. Expression of ezy-1 is selectively inhibited when plus, but not minus, gametes are briefly ultraviolet irradiated just prior to mating, a treatment known to disrupt the uniparental inheritance of chloroplast traits. We propose that the Ezy-1 polypeptide participates in the destruction of the minus chloroplast DNA in zygotes and thus the uniparental inheritance of chloroplast traits. The ezy-1 gene represents a valuable molecular probe for dissecting mechanisms underlying organelle inheritance.     

The sorting of mitochondrial DNA and mitochondrial proteins in zygotes: preferential transmission of mitochondrial DNA to the medial bud

Green fluorescent protein (GFP) was used to tag proteins of the mitochondrial matrix, inner, and outer membranes to examine their sorting patterns relative to mtDNA in zygotes of synchronously mated yeast cells in rho+ x rho0 crosses. When transiently expressed in one of the haploid parents, each of the marker proteins distributes throughout the fused mitochondrial reticulum of the zygote before equilibration of mtDNA, although the membrane markers equilibrate slower than the matrix marker. A GFP-tagged form of Abf2p, a mtDNA binding protein required for faithful transmission of rho+ mtDNA in vegetatively growing cells, colocalizes with mtDNA in situ. In zygotes of a rho+ x rho+ cross, in which there is little mixing of parental mtDNAs, Abf2p-GFP prelabeled in one parent rapidly equilibrates to most or all of the mtDNA, showing that the mtDNA compartment is accessible to exchange of proteins. In rho+ x rho0 crosses, mtDNA is preferentially transmitted to the medial diploid bud, whereas mitochondrial GFP marker proteins distribute throughout the zygote and the bud. In zygotes lacking Abf2p, mtDNA sorting is delayed and preferential sorting is reduced. These findings argue for the existence of a segregation apparatus that directs mtDNA to the emerging bud.     

Mutational analysis of Mdm1p function in nuclear and mitochondrial inheritance

Nuclear and mitochondrial transmission to daughter buds of Saccharomyces cerevisiae depends on Mdm1p, an intermediate filament-like protein localized to numerous punctate structures distributed throughout the yeast cell cytoplasm. These structures disappear and organelle inheritance is disrupted when mdm1 mutant cells are incubated at the restrictive temperature. To characterize further the function of Mdm1p, new mutant mdm1 alleles that confer temperature-sensitive growth and defects in organelle inheritance but produce stable Mdm1p structures were isolated. Microscopic analysis of the new mdm1 mutants revealed three phenotypic classes: Class I mutants showed defects in both mitochondrial and nuclear transmission; Class II alleles displayed defective mitochondrial inheritance but had no effect on nuclear movement; and Class III mutants showed aberrant nuclear inheritance but normal mitochondrial distribution. Class I and II mutants also exhibited altered mitochondrial morphology, possessing primarily small, round mitochondria instead of the extended tubular structures found in wild-type cells. Mutant mdm1 alleles affecting nuclear transmission were of two types: Class Ia and IIIa mutants were deficient for nuclear movement into daughter buds, while Class Ib and IIIb mutants displayed a complete transfer of all nuclear DNA into buds. The mutations defining all three allelic classes mapped to two distinct domains within the Mdm1p protein. Genetic crosses of yeast strains containing different mdm1 alleles revealed complex genetic interactions including intragenic suppression, synthetic phenotypes, and intragenic complementation. These results support a model of Mdm1p function in which a network comprised of multimeric assemblies of the protein mediates two distinct cellular processes.     

Rapid and simple determination of oxolinic acid and oxytetracycline in the shell of the blue mussel (Mytilus edulis) by high-performance liquid chromatography

A simple procedure for the determination of oxolinic acid (OA) and oxytetracycline (OTC), two antibacterial agents, in the shell of the blue mussel (Mytilus edulis), using reversed-phase high-performance liquid chromatography is described. Liquid chromatography was performed on a 5-microm LiChroSpher 100 RP-18E column using acetonitrile and a 0.02 M orthophosphoric acid solution as the mobile phase, with ultraviolet detection. After roughly grinding the shell, drugs were extracted using a methanolic oxalic acid solution. Linearity and precision were checked over the concentration range 0.04-0.32 microg/g. Limits of detection of OA and OTC were 0.012 and 0.008 microg/g, respectively. Mean extraction recoveries of OA and OTC from mussel shell were 72.9 and 65.4%, respectively. To demonstrate the usefulness of the analytical procedure, an experimental study was performed in blue mussels exposed to the drugs for eight days.     

Cardiomyopathies and mitochondrial DNA mutations

Our former studies concerning mitochondrial DNA mutations were reviewed in this article. A 7.4 kb deletion between the D-loop and ATPase 6 genes was detected in myocardial tissue obtained at autopsy from patients with myocardial infarction, diabetes mellitus and also patients treated with adriamycin. A case with diabetes mellitus and hypertrophic cardiomyopathy is demonstrated which revealed a point mutation from adenine to guanine at position 3243 within tRNA Leu(UUR).     

The one ancestor per generation rule and three other rules of mitochondrial inheritance

In mammals, at least, a species-specific mechanism exists that eliminates sperm-derived mitochondrial DNA from a fertilized egg. The result is the "one female ancestor per generation" rule and three other rules of mitochondrial inheritance. The second, third, and fourth rules are as follows. (ii) Sublineages of a given mitochondrial line can be generated only during the parallel descents from ancestral sisters. (iii) In a static population in which the production of one female progeny per mated pair per generation has been a rule, several ancient mitochondrial lineages harking back to the female founders of the speciation may persist side by side. (iv) Two or more individuals not related to each other in the recent past may share the identical or nearly identical mitochondrial genome derived from the common female ancestor or ancestral sisters of many generations ago.     

Multiple deletions of the mitochondrial DNA in polymyalgia rheumatica

We analyzed the mitochondrial DNA of patients with polymyalgia rheumatica, a disease frequently associated with mitochondrial myopathy. In an attempt to study the deletions, we have developed a qualitative PCR method using a highly thermostable polymerase in order to amplify multiple mitochondrial DNA large fragments (up to 12 kb). PCR serves to observe both deleted and normal fractions of the mitochondrial DNA. We found multiple deletions of the mitochondrial DNA in all of the patient muscles. Although these muscles harbored many ragged red fibers, we found no point mutations of the tRNA(Leu)(UUR)) and the mutation at nucleotide position 8344 was not present.     

Deleterious mutations in animal mitochondrial DNA

A simple neutral model predicts that the ratio of non-synonymous to synonymous fixed differences between species will be the same as the ratio of non-synonymous to synonymous polymorphisms within species. This prediction is tested with existing mitochondrial datasets from 25 animal species. In slightly over half of the studies, the ratio of replacement to silent polymorphisms within species is significantly greater than the ratio of replacement to silent fixed differences between species. These observations are best explained by a substantial number of mildly deleterious amino acid mutations that contribute to heterozygosity but rarely become fixed.     

The distribution of ND genes in yeast mitochondrial genomes and the mitochondrial DNA structure of Pichia membranaefacens

For long time, it has been believed that the yeast mitochondrial (mt) genome lacks NADH dehydrogenase subunit genes which are designated ND genes. However, our complete mtDNA sequencing of yeast Hansenula wingei led us to the first finding of seven mitochondrial ND genes. We investigated the distribution of ND genes in mtDNAs of other yeasts including Pichia membranaefaciens, Yarrowia lypolitica, Candida maltosa, Saccharomyces kluyveri and Saccharomyces exiguus. By Southern hybridization with probes of H. wingei's ND1, 2 and 5 genes, we detected positive signals on mtDNAs in P. membranaefaciens, Y. lypolitica, and C. maltosa. To confirm this, we cloned and sequenced DNA fragment of ND5 gene in P. membranaefaciens. We have discussed the sequence homology and genome structure.