Genetic sex determination in three closely related hydrothermal vent gastropods, including one species with intersex individuals

Molluscs have undergone many transitions between separate sexes and hermaphroditism, which is of interest for studying the evolution of sex determination and differentiation. Here we combined multi-locus genotypes obtained from RAD sequencing with anatomical observations of the gonads for three deep-sea hydrothermal vent gastropods of the genus Alviniconcha living in the southwest Pacific. We found that all three species (A. boucheti, A. strummeri, and A. kojimai) share the same male-heterogametic XY sex determination system, but that the gonads of XX A. kojimai individuals are invaded by a variable proportion of male reproductive tissue. The identification of Y-specific RAD loci (found only in A. boucheti) and the phylogenetic analysis of three sex-linked loci shared by all species suggested that X-Y recombination has evolved differently within each species. This situation of three species showing variation in gonadal development around a common sex determination system provides new insights into the reproductive mode of poorly known deep-sea species and opens up an opportunity to study the evolution of recombination suppression on sex chromosomes and its association with mixed or transitory sexual systems.

Cytomegalovirus DNAemia Requiring (Val)Ganciclovir Treatment for More Than 8 Weeks Is a Key Factor in the Development of Antiviral Drug Resistance

Background

Prolonged (val)ganciclovir [(V)GCV] exposure for ≥6 weeks is a known predisposing factor for cytomegalovirus (CMV) drug resistance. However, the selection of this threshold was based on limited data. In this study, we sought to reappraise the risk factors for the development of (V)GCV resistance through a specific focus on kidney transplant recipients (KTRs).

Methods

This single-center retrospective study included 313 consecutive KTRs treated for a first CMV episode. Adjusted Cox multivariate regression analysis was used for identifying independent risk factors.

Results

Antiviral drug resistance was identified in 20 (6%) KTRs. A cumulative (V)GCV exposure for more than 6 weeks (regardless of the viral load) was not associated with antiviral drug resistance (hazard ratio [HR] = 2.45, 95% confidence interval [CI] = 0.33-18.30, P = .38). In contrast, persistent CMV DNAemia requiring (V)GCV treatment for more than 8 weeks was the main independent risk factor for antiviral drug resistance (HR = 11.68, 95% CI = 2.62-52.01, P = .001). The (V)GCV treatment for more than 8 weeks was given to 9% and 18% of patients who had persistent or recurrent CMV DNAemia, respectively. These scenarios were associated with the occurrence of drug resistance in 39% and 12% of cases, respectively.

Conclusions

Cumulative (V)GCV exposure ≥6 weeks regardless of the viral load is not associated with antiviral drug resistance. In contrast, prolonged exposure to (V)GCV during CMV replication (with a cutoff ³8 weeks) seems to be a key factor.

Microbiological profile of orbital abscess

BACKGROUND

Knowledge of the culture and sensitivity pattern is necessary, for the institution of appropriate empirical antibiotic therapy in orbital abscess.

OBJECTIVE

The objective of this study is to describe culture and sensitivity patterns of specimens from the orbit and surrounding structures.

MATERIALS AND METHODS

Retrospectively the medical records of 56 cases of orbital abscess were reviewed.

RESULTS

Cultures were positive in 38/56 (68.8%) orbital specimens and the organisms included Staphylococcus aureus 18, Streptococci 7, Pseudomonas aeruginosa 3, 2 each of Enterobactersp, Escherichia coli, Proteus mirabilis, Acinetobacter sp. and 1 each of Actinomyces israelii, Diptheroids, Coagulase negative Staphylococcus, Citrobacter freundii, Methicillin-resistant S. aureus and Enterococcus faecalis. Four had polymicrobial infection. Culture of purulent nasal discharge, swabs taken from foci of infection on the face, and blood cultures were done in 26/56, and positive cultures were obtained in 16/26 (61.5%) specimens. In 12 patients, there was a concurrence in the organism cultured from the orbit and from cultures from other sites. Gram-negative organisms were associated with increased ocular morbidity.

CONCLUSION

Gram-positive cocci, especially S. aureus are the most common organisms isolated from orbital abscesses. Infections by Gram-negative organisms were associated with more complications. Empirical intravenous antibiotic therapy should have a broad spectrum of activity effective against a wide range of Staphylococcal organisms and Gram-negative bacilli.

Prospective echocardiographic and tissue Doppler imaging screening of a population of Maine Coon cats tested for the A31P mutation in the myosin-binding protein C gene: a specific analysis of the heterozygous status

BACKGROUND

A mutation in the sarcomeric gene coding for the myosin-binding protein C gene has been identified in a colony of Maine Coon cats with hypertrophic cardiomyopathy (MyBPC3-A31P mutation). However, the close correlation between genotype and phenotype (left ventricular hypertrophy [LVH] and dysfunction) has never been assessed in a large population, particularly in heterozygous (Hetero) cats.

OBJECTIVES

To investigate LV morphology and function with echocardiography and tissue Doppler imaging (TDI) in a population of Maine Coon cats tested for the MyBPC3-A31P mutation with focus on Hetero animals.

ANIMALS

Ninety-six Maine Coon cats.

METHODS

Prospective observational study. Cats were screened for the MyBPC3-A31P mutation and examined with both echocardiography and 2-dimensional color TDI.

RESULTS

Fifty-two out of 96 cats did not have the mutation (wild-type genotype, Homo WT), 38/96 and 6/96 were Hetero- and homozygous-mutated (Homo M) cats, respectively. Only 11% of Hetero cats (4/38) had LVH and 29% (10/34) of Hetero cats without LVH were >4 years old (4.1-11.5 years). LVH was also detected in 2 Homo WT cats (4%). A significantly decreased (P < .05) longitudinal E/A (ratio between early and late diastolic myocardial velocities) in the basal segment of the interventricular septum was observed in Hetero cats without LVH (n = 34) compared with Homo WT cats without LVH (n = 50), thus confirming that the Hetero status is associated with regional diastolic dysfunction (P < .05).

CONCLUSIONS

The heterozygous status is not consistently associated with LVH and major myocardial dysfunction. Moreover, Homo WT cats can also develop LVH, suggesting that other genetic causes might be implicated.

Identification of proteins undergoing expression level modifications in WI-38 SV40 fibroblasts overexpressing methionine sulfoxide reductase A

Methionine sulfoxide reductase A overexpressing WI-38 SV40 human fibroblasts have been previously shown to exhibit higher resistance to oxidative stress by decreasing intracellular reactive oxygen species content and oxidative damage to proteins [C.R. Picot, I. Petropoulos, M. Perichon, M. Moreau, C. Nizard, B. Friguet, Overexpression of MsrA protects WI-38 SV40 human fibroblasts against H(2)O(2)-mediated oxidative stress, Free Radic Biol Med 39 (2005) 1332-1341]. In order to get further insight into the molecular mechanisms underlying this resistance to oxidative stress, proteins that are differentially expressed in methionine sulfoxide reductase A overexpressing cells were identified by 2D gel and Western blot quantitative analyses. Five proteins were shown to be differentially expressed and were identified by mass spectrometry, some of them were related to either cellular protection against oxidative stress, apoptosis or premature ageing.

A multicenter prospective randomized study testing non-inferiority of thalidomide 100 mg/day as compared with 400 mg/day in patients with refractory/relapsed multiple myeloma: Results of the final analysis of the IFM 01–02 study

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Background: Thalidomide (THAL) is effective in pts with relapsed or refractory multiple myeloma (RRMM). A study by Yakoub-Agha et al of 83 patients (Hematol J, 2002) supported this effectiveness but showed a high incidence of THAL toxicity ≥ grade II, related to either THAL cumulative dose or dose-intensity. Themean daily dose of THAL in the first 90-day treatment period, however, did not influence response, overall survival (OS), or event-free survival. Given the dose-related toxicities and an unknown minimally effective THAL dose, the IFM conducted a prospective randomized study to compare the efficacy of THAL 100 mg/d with 400 mg/d in pts with RRMM after ≥2 lines of prior therapy. Methods: The study design was approved by the ethics committee at Lille University Hospital, and all pts gave written informed consent. Given the improved response seen with THAL plus dexamethasone (DEX), this combination was specified per protocol in both study arms for treatment failure (TF) defined as progression at any time or stable disease after 3 months of THAL treatment. THAL dose reduction for toxicity was permitted, but no increase over the initial dose was allowed. All pts received pamidronate routinely. The primary end point was 1-year OS. Secondary endpoints were response rate, EFS, and safety. Results: All results are based on intent-to-treat analyses. In all, 400 pts were enrolled (400 mg, n = 195; 100 mg, n = 205). The 2 groups were comparable in terms of patient characteristics, disease features including Ch13 deletion and prior therapy. Pts in the THAL 100 mg arm received DEX more frequently for TF than those in the 400 mg group, but this difference did not influence 1-year OS: 73 ± 3% vs 69 ± 3% in the 400 mg and 100 mg groups, respectively. The hypothesis of inferiority of 100 mg was rejected. Also, THAL 100 mg was better tolerated than 400 mg with less high-grade somnolence, constipation, and peripheral neuropathy (p < .001, p = .01 et p = .05, respectively). There was no difference regarding deep vein thrombosis. Conclusion: THAL 100 mg/d is comparable in terms of survival with 400 mg/d (with DEX as salvage therapy in case of TF in both arms) in pts with RRMM and better tolerated.

[Table: see text]

Superiority of melphalan-prednisone (MP) + thalidomide (THAL) over MP and autologous stem cell transplantation in the treatment of newly diagnosed elderly patients with multiple myeloma

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Background: The standard MP regimen remains the reference treatment for elderly patients (pts) with multiple myeloma (MM). In May 2000, we initiated the IFM 99–06 trial, for pts aged 65–75 y, comparing MP (12 courses at 6 weeks intervals) to MP-THAL (MP plus THAL at the maximum tolerated dose, but ≤ 400 mg/day) and a MEL100-based treatment (VAD×2, CTX 3g/m2, and 2 courses of MEL100 mg/m2). Methods: IFM99–06 was planned to enroll 476 evaluable pts, whose treatment allocation followed a 3 (MP), 2 (MP-THAL), 2 (MEL100) randomization scheme. The primary end-point was overall survival (OS). Secondary end-points were response to treatment and progression-free survival (PFS). Two interim analyses were planned and reviewed by a Data Safety Monitoring Board (DSMB) independent of IFM. At the second interim analysis, the DSMB suggested that a third interim analysis be performed with a date of point on May 1, 2005. Results: At this time, 436 pts had been enrolled, 191, 124 and 121 in MP, MP-THAL and MEL100 groups, respectively. The median (se) follow-up time was 32.2 (1.8) months (mo.). Median (se) PFS times were 17.2 (1.5), 29.5 (3.6) and 19.0 (1.3) mo. in MP, MP-THAL and MEL100 groups, respectively. The PFS time was significantly longer in the MP-THAL group than in the MP group (RR=2.4, P<0.0001), but no significant difference was noted between MP and MEL100 groups (RR=1.2, P=0.12). There was a clear advantage in favor of MP-THAL vs MEL 100 (RR=2.0, P=0.0001). The PFS advantage in favor of MP-THAL translated to a significant benefit in terms of OS. Median (se) OS times were 30.3 (5.8) mo. (86 deaths), not reached at 56 mo.(34 deaths) and 38.6 (3.0) mo. (54 deaths) in MP, MP-THAL and MEL100 groups, respectively. The OS time was significantly longer in MP-THAL group than in MP group (RR=1.9, P=0.0008), but not significantly different between MP and MEL100 groups (RR=1.1, P=0.55). MP-THAL was also superior to MEL100 (RR=1.7, P=0.014). Conclusion: Since these results show the superiority of MP-THAL, enrollment was stopped. The final analysis will be presented at the meeting. MP-THAL should be, at the present time, the reference treatment for newly diagnosed MM pts ineligible for high-dose therapy.

No significant financial relationships to disclose.

Biological detection of low radiation doses by combining results of two microarray analysis methods

The accurate determination of the biological effects of low doses of pollutants is a major public health challenge. DNA microarrays are a powerful tool for investigating small intracellular changes. However, the inherent low reliability of this technique, the small number of replicates and the lack of suitable statistical methods for the analysis of such a large number of attributes (genes) impair accurate data interpretation. To overcome this problem, we combined results of two independent analysis methods (ANOVA and RELIEF). We applied this analysis protocol to compare gene expression patterns in Saccharomyces cerevisiae growing in the absence and continuous presence of varying low doses of radiation. Global distribution analysis highlights the importance of mitochondrial membrane functions in the response. We demonstrate that microarrays detect cellular changes induced by irradiation at doses that are 1000-fold lower than the minimal dose associated with mutagenic effects.

Rat peptide methionine sulphoxide reductase: cloning of the cDNA, and down-regulation of gene expression and enzyme activity during aging

Peptide methionine sulphoxide reductase (PMSR, EC 1.8.4.6), the msrA or pmsR gene product, is a ubiquitous enzyme catalysing the reduction of methionine sulphoxide to methionine in proteins. Decreased expression and/or activity of the PMSR with age could explain, at least in part, the accumulation of oxidized protein observed upon aging. To test this hypothesis, the rat pmsR cDNA was cloned and sequenced. The recombinant protein was expressed, its catalytic activity checked with a synthetic substrate and polyclonal antibodies were raised against recombinant PMSR. The expression of the pmsR gene and protein as well as its catalytic activity were then analysed as a function of age in the rat brain and in two organs that express the most PMSR, liver and kidney. It appears that pmsR gene expression decreases with age in liver and kidney as early as 18 months, whereas protein level and protein activity are reduced in the three organs at the very end of the life of the rat (26 months). These results suggest that the down-regulation of PMSR can contribute to the accumulation of oxidized protein that has been associated with the aging process.

Isolation and characterization of a protein with high affinity for DNA: the glutamine synthetase of Thermus thermophilus 111

In a search of proteins from the thermophilic bacterium Thermus thermophilus 111 with a high affinity for DNA, the selected protein from this screening appears to be the glutamine synthetase (GS). The purified product gives one band in SDS-polyacrylamide gel electrophoresis (53,700 Da). The N-terminal 32 residues have been identified and present an homology of 80% with the glutamine synthetase of Bacillus subtilis and 76% with that of Thermotoga maritima. The protein displays the characteristic dodecameric structure of the eubacteria glutamine synthetase. From a detailed study of the interaction of this protein with DNA by dark-field electron microscopy and agarose gel electrophoresis, it is concluded that double-stranded DNA wraps the protein by a full turn of 150 bp length. An even number of GS molecules bound to a closed relaxed plasmid DNA does not alter its null topology. By using an inverted dimer DNA fragment, which contains twice a curved kinetoplast DNA insert in its central part, it is shown that DNA curvature rules the order in which GS binds to the DNA. DNA ends are also sites of high affinity for the GS. Supercoiling does not favor the binding of GS to the DNA with the exception of the apices that are by essence bent regions. By saturating a DNA molecule with GS one obtains a novel characteristic scalloped configuration in which the DNA undulates from one GS to the next. The DNA is condensed at least three times in these structures. By increasing the ratio of GS to DNA in solution the resulting material migrates as discrete bands relative to the free DNA in an agarose gel. By gel retardation and EM statistical distribution analysis of GS within the complexes, an average affinity constant of 10(7) M-1 was obtained. The potential implications of this novel interaction of the glutamine synthetase with DNA for the regulation of its own gene are briefly discussed.

Posttranslational modifications of axonemal tubulin

Axonemal tubulin exhibits a high degree of heterogeneity mostly due to several posttranslational modifications (PTM). The aim of this work was to chemically characterize the different PTM occurring in the C-terminal tail of axonemal tubulin purified from sea urchin, Paracentrotus lividus, spermatozoa. After its purification, tubulin was enzymatically cleaved. The C-terminal peptides were chromatographically isolated, first by anion exchange and then by reverse-phase HPLC. Peptides were characterized by their sequence, determined by Edman degradation, and by their mass, determined by MALDI-TOF/MS. The two major conclusions are that the majority of the isolated C-terminal peptides were unmodified and that polyglycylation and polyglutamylation can occur simultaneously on one molecule of alpha-tubulin.

Structure of the C-terminal tail of alpha-tubulin: increase of heterogeneity from newborn to adult

A combination of posttranslational modifications contributes to the high heterogeneity of brain tubulin in mammals. In this report, the structures of the detyrosinated carboxy-terminal peptides of alpha-tubulin from newborn and adult mouse brain were compared. The heterogeneity of these carboxy-terminal peptides was observed to increase from newborn to adult brain tubulin. The major part of this increased heterogeneity is due to the post-translational excision of Glu450, which makes alpha-tubulin nontyrosinatable (delta-2 tubulin). The structures of the polyglutamyl side chain of the bi- and triglutamylated peptides were analyzed in this work. In polyglutamylation of alpha-tubulin, the first glutamyl residue can only be amide-linked to the gamma-carboxyl group of Glu445, but the additional residues may be linked either to the gamma- or to the alpha-carboxyl groups of the preceding one. By optimized reverse-phase separations and comparison with synthetic peptides corresponding to all possible linkages for the biglutamylated (gamma 1 alpha 2, gamma 1 gamma 2) and triglutamylated (gamma 1 alpha 2 alpha 3, gamma 1 gamma 2 gamma 3, gamma 1 alpha 2 gamma 3, gamma 1 gamma 2 alpha 3, gamma 1 gamma 2 alpha 2) tubulin peptides, it was possible to conclude that the mode of linkage connecting the second and third additional glutamyl residues corresponds mostly to alpha-bond structures, for both newborn and adult mice.

Posttranslational modifications in the C-terminal tail of axonemal tubulin from sea urchin sperm

After proteolytic digestion of sperm tubulin from sea urchin Paracentrotus lividus, C-terminal peptides were isolated by chromatographic separations. The peptides were analyzed by Edman degradation and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. About 70% of the isolated C-terminal peptides were unmodified. The remaining modified peptides have undergone a combination of numerous posttranslational modifications generating significant heterogeneity of sperm tubulin. alpha-Tubulin is modified by detyrosylation, release of the penultimate glutamate, polyglutamylation, and polyglycylation. Glycylation and glutamylation can coexist within one alpha-tubulin isoform. beta-Tubulin undergoes polyglycylation but was not observed to be polyglutamylated. The number of units posttranslationally added reaches 11 and 12 glycyl units on beta- and alpha-tubulin, respectively. This is different from the polyglycylation of axonemal tubulin in Paramecium cilia where up to 40 added glycyl units were observed both on alpha- and beta-tubulin.

Class I and IVa beta-tubulin isotypes expressed in adult mouse brain are glutamylated

Several types of post-translational modifications contribute to the high level of tubulin heterogeneity in the brain. An important modification is glutamylation of the major brain-specific isotypes, such as class Ia/b of alpha-tubulin and classes II and III of beta-tubulin. Here we describe experiments to determine if additional, minor tubulin isotypes, expressed in adult mouse brain, could also be glutamylated. Purified tubulin from adult mouse brain was cleaved with thermolysin. Proteolytically released carboxy-terminal peptides of both alpha- and beta-tubulin were isolated by sequential anion exchange and reverse-phase column-chromatography. Anionic peptides were then characterized by amino acid sequencing and mass spectrometry. We show that brain-specific class IVa and constitutive class I beta-tubulin isotypes can be glutamylated, at Glu434 and Glu441, respectively.