Azole resistance by loss of function of the sterol Δ⁵,⁶-desaturase gene (ERG3) in Candida albicans does not necessarily decrease virulence.

The inactivation of ERG3, a gene encoding sterol Δ⁵,⁶-desaturase (essential for ergosterol biosynthesis), is a known mechanism of in vitro resistance to azole antifungal drugs in the human pathogen Candida albicans. ERG3 inactivation typically results in loss of filamentation and attenuated virulence in animal models of disseminated candidiasis. In this work, we identified a C. albicans clinical isolate (VSY2) with high-level resistance to azole drugs in vitro and an absence of ergosterol but normal filamentation. Sequencing of ERG3 in VSY2 revealed a double base deletion leading to a premature stop codon and thus a nonfunctional enzyme. The reversion of the double base deletion in the mutant allele (erg3-1) restored ergosterol biosynthesis and full fluconazole susceptibility in VSY2, confirming that ERG3 inactivation was the mechanism of azole resistance. Additionally, the replacement of both ERG3 alleles by erg3-1 in the wild-type strain SC5314 led to the absence of ergosterol and to fluconazole resistance without affecting filamentation. In a mouse model of disseminated candidiasis, the clinical ERG3 mutant VSY2 produced kidney fungal burdens and mouse survival comparable to those obtained with the wild-type control. Interestingly, while VSY2 was resistant to fluconazole both in vitro and in vivo, the ERG3-derived mutant of SC5314 was resistant only in vitro and was less virulent than the wild type. This suggests that VSY2 compensated for the in vivo fitness defect of ERG3 inactivation by a still unknown mechanism(s). Taken together, our results provide evidence that contrary to previous reports inactivation of ERG3 does not necessarily affect filamentation and virulence.

Aortic root rupture: implications of catheter-guided aortic valve replacement.

PURPOSE OF REVIEW: The safety and efficiency of trans catheter aortic valve implantation (TAVI) has been clearly demonstrated. In high-risk patients, the number of procedures is constantly increasing and in western European countries this procedure is employed in more than 30% of isolated aortic valve replacements. The literature, however, focusing on perioperative aortic root (AoR) rupture is rather limited to just a few reports. The aim of this review is to analyze the pathophysiology of AoR rupture during TAVI, stressing the implications of the morphology of the AoR for this devastating complication. RECENT FINDINGS: Currently, perioperative AoR rupture ranges between 0.5 and 1.5% during TAVI, with almost 100% mortality. Recently, valve oversizing and balloon dilatation in a calcified and small AoR were considered as the most important predictive factors for this complication. SUMMARY: The most fragile unit of the AoR is its anchoring substrate to the ostium of the left ventricle. This membranous structure is not involved in the degenerative process leading to aortic valve stenosis. Due to the TAVI and/or balloon dilatation of the calcium stationed on the three leaflets and their attachment, a lesion may result on this structure. And, as a consequence, there is rupture of the AoR.

Molecular autopsy in sudden cardiac death and its implication for families: discussion of the practical, legal and ethical aspects of the multidisciplinary collaboration.

Sudden cardiac death (SCD) is a major cause of premature death in young adults and children in developed countries. Standard forensic autopsy procedures are often unsuccessful in determining the cause of SCD. Post-mortem genetic testing, also called molecular autopsy, has revealed that a non-negligible number of these deaths are a result of inherited cardiac diseases, including arrhythmic disorders such as congenital long QT syndrome and Brugada syndrome. Due to the heritability of these diseases, the potential implications for living relatives must be taken into consideration. Advanced diagnostic analyses, genetic counselling, and interdisciplinary collaboration should be integral parts of clinical and forensic practice. In this article we present a multidisciplinary collaboration established in Lausanne, with the goal of properly informing families of these pathologies and their implications for surviving family members. In Switzerland, as in many other countries, legal guidelines for genetic testing do not address the use of molecular tools for post-mortem genetic analyses in forensic practice. In this article we present the standard practice guidelines established by our multidisciplinary team.

Investigation of Rapid Thermal Analysis Procedures for Prediction of the Service Life of PCCP Carbonate Coarse Aggregate, HR-337, 1993

The major objective of this research project was to use thermal analysis techniques in conjunction with x-ray analysis methods to identify and explain chemical reactions that promote aggregate related deterioration in portland cement concrete. Twenty-two different carbonate aggregate samples were subjected to a chemical testing scheme that included: • bulk chemistry (major, minor and selected trace elements) • bulk mineralogy (minor phases concentrated by acid extraction) • solid-solution in the major carbonate phases • crystallite size determinations for the major carbonate phases • a salt treatment study to evaluate the impact of deicer salts Test results from these different studies were then compared to information that had been obtained using thermogravimetric analysis techniques. Since many of the limestones and dolomites that were used in the study had extensive field service records it was possible to correlate many of the variables with service life. The results of this study have indicated that thermogravimetric analysis can play an important role in categorizing carbonate aggregates. In fact, with modern automated thermal analysis systems it should be possible to utilize such methods on a quality control basis. Strong correlations were found between several of the variables that were monitored in this study. In fact, several of the variables exhibited significant correlations to concrete service life. When the full data set was utilized (n = 18), the significant correlations to service life can be summarized as follows ( a = 5% level): • Correlation coefficient, r, = -0.73 for premature TG loss versus service life. • Correlation coefficient, r, = 0.74 for relative crystallite size versus service life. • Correlation coefficient, r, = 0.53 for ASTM C666 durability factor versus service life. • Correlation coefficient, r, = -0.52 for acid-insoluble residue versus service life. Separation of the carbonate aggregates into their mineralogical categories (i.e., calcites and dolomites) tended to increase the correlation coefficients for some specific variables (r sometimes approached 0.90); however, the reliability of such correlations was questionable because of the small number of samples that were present in this study.

Characterization of the neuronal microtubule regulator SCG10 in transfected cells and " in vivo "

SUMMARY The ability of neuronal processes to find their way along complex paths and to establish appropriate connections depends on continual rearrangements of the cytoskeletal components. The regulation of microtubules plays an important role for morphological changes underlying nevrite outgrowth, axonal elongation, and growth cone steering. SCG10 (superior cervical ganglion clone 10) is a neuronal growthassociated protein developmentally regulated and highly enriched in the neuronal growth cones. SCG10 presents a microtubule destabilizing activity that could participate to the regulation of microtubule dynamics and thus explain microtubule behaviors in the growth cone during axonal elongation and turning. It is here suggested that a tight control of the opposite effects on microtubules of SCG10 and the stabilizing microtubule-associated protein MAP1B allows a fine tuning of cytoskeletal rearrangement and may provide the required microtubule dynamic instability to promote axonal growth. Moreover, antibodyblockade of SCG10 function, that leads to growth cone pauses similar as those triggered by the guidance molecule EphB, and the modulation of SCG10 activity by the Rho GTPase Rnd1 suggest a potential role for SCG10 in the signal transduction pathways of extracellular guidance cues. The identification of the active zone protein Bassoon as a potential interaction partner for the SCG10-related protein NPC2, using atomic force microscopy as well as COS-7 and neuronal cell cultures, also gives new insights for a role of this protein family into the processes of synapse genesis or plasticity. Finally, SCG10 mutant mice generated by gene targeting and expressing a soluble form of the protein have been characterized during early postnatal development and in the adulthood. Due to the deletion of its membrane binding domain, SCG10 specific subcellular targeting to growth cones is compromised and results in impairments of motor and coordination development. Further histological analysis in the sciatic nerve reveal that these symptoms are associated with neurodegenerative signs. RESUME Une navigation correcte des prolongements cellulaires neuronaux leur permettant de former des connections appropriées repose sur de continuels réarrangements des constituants de leur cytosquelette. La régulation des microtubules joue notamment un rôle important dans les changements morphologiques qui accompagnent la croissance axonale et les réorientations du cône de croissance. SCG10 (superior cervical ganglion clone 10) est une protéine étroitement associée à la croissance neuronale, hautement régulée durant le développement et abondante au niveau du cône de croissance. SCG10 présente une activité déstabilisatrice sur les microtubules qui pourrait permettre une régulation des paramètres dynamiques propres aux microtubules et ainsi expliquer leur comportement durant la navigation du cône de croissance. Il est ici proposé qu'un contrôle précis des effets opposés de SCG10 et d'une autre protéine stabilisante associée aux microtubules (MAP1 B) permette un réglage fin des réarrangements du cytosquelette et puisse ainsi produire l'instabilité dynamique nécessaire à la croissance anale. Par ailleurs, le blocage de la fonction de SCG10 par un anticorps spécifique, conduisant à des pauses du cônes de croissance similaires à celles provoquées par la molécule de guidage EphB, ainsi que la modulation de l'activité de SCG10 par la Rho GTPase Rnd1 suggèrent une potentielle implication de SCG10 dans les voies de transduction des signaux provenant de molécules de guidage extracellulaires. L'identification d'une interaction de la protéine synaptique Bassoon avec la protéine NPC2 apparentée à SCG10, au moyen de la microscopie à force atomique et dans des cultures de cellules neuronales et COS-7, ouvre des perspectives concernant ces protéines dans la formation et la plasticité synaptiques. Finalement, des souris mutantes pour SCG10 produites par ciblage de gène et exprimant une forme soluble de la protéine ont été caractérisées durant la phase précoce du développement et à l'âge adulte. La délétion du domaine permettant l'ancrage de SCG10 aux membranes compromet sa sub-localisation au niveau du cône de croissance et résulte en l'apparition de troubles moteurs et de la coordination. Des analyses histologiques complémentaires au niveau du nerf sciatique montrent que ces symptômes sont associés avec des signes neurodégénératifs.

Early detection of lung cancer: a statement from an expert panel of the Swiss university hospitals on lung cancer screening.

The discussion about setting up a program for lung cancer screening was launched with the publication of the results of the National Lung Screening Trial, which suggested reduced mortality in high-risk subjects undergoing CT screening. However, important questions about the benefit-harm balance and the details of a screening program and its cost-effectiveness remain unanswered. A panel of specialists in chest radiology, respiratory medicine, epidemiology, and thoracic surgery representing all Swiss university hospitals prepared this joint statement following several meetings. The panel argues that premature and uncontrolled introduction of a lung cancer screening program may cause substantial harm that may remain undetected without rigorous quality control. This position paper focuses on the requirements of running such a program with the objective of harmonizing efforts across the involved specialties and institutions and defining quality standards. The underlying statement includes information on current evidence for a reduction in mortality with lung cancer screening and the potential epidemiologic implications of such a program in Switzerland. Furthermore, requirements for lung cancer screening centers are defined, and recommendations for both the CT technique and the algorithm for lung nodule assessment are provided. In addition, related issues such as patient management, registry, and funding are addressed. Based on the current state of the knowledge, the panel concludes that lung cancer screening in Switzerland should be undertaken exclusively within a national observational study in order to provide answers to several critical questions before considering broad population-based screening for lung cancer.

Investigation of Rapid Thermal Analysis Procedures for Prediction of the Service Life of PCCP Carbonate Coarse Aggregate: Phase I, Progress Report, HR-337, 1992

The major objective of this research project is to utilize thermal analysis techniques in conjunction with x-ray analysis methods to identify and explain chemical reactions that promote aggregate related deterioration in Portland cement concrete. The first year of this project has been spent obtaining and analyzing limestone and dolomite samples that exhibit a wide range of field service performance. Most of the samples chosen for the study also had laboratory durability test information (ASTM C 666, method B) that was readily available. Preliminary test results indicate that a strong relationship exists between the average crystallite size of the limestone (calcite) specimens and their apparent decomposition temperatures as measured by thermogravimetric analysis. Also, premature weight loss in the thermogravimetric analysis tests appeared to be related to the apparent decomposition temperature of the various calcite test specimens.

Raeder's paratrigeminal syndrome due to spontaneous dissection of the cervical and petrous internal carotid artery.

The combination of pain, ipsilateral oculosympathetic defect (ptosis and miosis), and ipsilateral trigeminal dysfunction constitutes Raeder's syndrome. We describe a patient with an acute presentation of Raeder's syndrome due to spontaneous internal carotid artery dissection. True trigeminal dysfunction due to carotid dissection is rare, and the potential mechanisms for its involvement are reviewed in this paper. Finally, we remind clinicians to consider dissection in the differential diagnosis of Raeder's syndrome because of its potential for ischemic cerebral neurologic sequelae and suggest early cranial and neck imaging in the evaluation of such patients.

Optimization of the procedure for removing iron deposits on ceramic filter media

In this thesis, cleaning of ceramic filter media was studied. Mechanisms of fouling and dissolution of iron compounds, as well as methods for cleaning ceramic membranes fouled by iron deposits were studied in the literature part. Cleaning agents and different methods were closer examined in the experimental part of the thesis. Pyrite is found in the geologic strata. It is oxidized to form ferrous ions Fe(II) and ferric ions Fe(III). Fe(III) is further oxidized in the hydrolysis to form ferric hydroxide. Hematite and goethite, for instance, are naturally occurring iron oxidesand hydroxides. In contact with filter media, they can cause severe fouling, which common cleaning techniques competent enough to remove. Mechanisms for the dissolution of iron oxides include the ligand-promoted pathway and the proton-promoted pathway. The dissolution can also be reductive or non-reductive. The most efficient mechanism is the ligand-promoted reductive mechanism that comprises two stages: the induction period and the autocatalytic dissolution.Reducing agents(such as hydroquinone and hydroxylamine hydrochloride), chelating agents (such as EDTA) and organic acids are used for the removal of iron compounds. Oxalic acid is the most effective known cleaning agent for iron deposits. Since formulations are often more effective than organic acids, reducing agents or chelating agents alone, the citrate¿bicarbonate¿dithionite system among others is well studied in the literature. The cleaning is also enhanced with ultrasound and backpulsing.In the experimental part, oxalic acid and nitric acid were studied alone andin combinations. Also citric acid and ascorbic acid among other chemicals were tested. Soaking experiments, experiments with ultrasound and experiments for alternative methods to apply the cleaning solution on the filter samples were carried out. Permeability and ISO Brightness measurements were performed to examine the influence of the cleaning methods on the samples. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the solutions was carried out to determine the dissolved metals.

Spermiogenesis and spermatozoon of the liver fluke Mediogonimus jourdanei (Microphalloidea: Prosthogonimidae), a parasite of Myodes glareolus (Rodentia: Cricetidae)

Spermatological characters of the liver fluke Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 were studied by means of transmission and scanning electron microscopy. Spermiogenesis begins with the formation of the differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. These two centrioles originate two free flagella that undergo a 90 degrees rotation before fusing with the median cytoplasmic process. Both nuclear and mitochondrial migrations toward the median cytoplasmic process occur before the proximodistal fusion of flagella. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon. The mature sperm of M. jourdanei measures about 260 microm and presents two axonemes of different lengths with the typical pattern of the Trepaxonemata, two bundles of parallel cortical microtubules, one mitochondrion, a nucleus and granules of glycogen. An analysis of all the microphalloidean species studied to date emphasised some differences in certain characters found in Maritrema linguilla Jägerskiöld, 1908 and Ganeo tigrinum Mehra et Negi, 1928 in comparison to those in the remaining microphalloideans. The presence and variability of such ultrastructural characters according to family, superfamily or order have led several authors to propose their use in the analysis of trematode relationships and phylogeny. Therefore, apart from producing new data on the family Prosthogonimidae, the present study also compares the spermatological organization of M jourdanei with other available ultrastructural studies focusing on the Microphalloidea.

Functions of the human papillomavirus type 16 E4 protein

1. Abstract Cervical cancer is thought to be the consequence of infection by human papillomaviruses (HPV). In the majority of cases, DNA from HPV type 16 (HPV16) is found in malignant cervical lesions. The initial steps leading to transformation of an infected cell are not clearly understood but in most cases, disruption and integration of the episomal viral DNA must take place. As a consequence, the E2 and E4 genes are usually not expressed whereas the E6 and E7 oncogenes are highly expressed. However, in a normal infection in which the viral DNA is maintained as an episome, all viral genes are expressed. The pattern according to which the viral proteins are made, and therefore the life cycle of the virus, is tightly linked to the differentiation process of the host keratinocyte. The study of the viral oncogenes E6 and E7 has revealed crucial functions in the process of malignant transformation such as degradation of the p53 tumor suppressor protein, deregulation of the Retinoblastoma protein pathway and activation of the telomerase ribonucleoprotein. All these steps are necessary for cancerous lesions to develop. However, the loss of the E2 gene product seems to be necessary for sufficient expression of E6 and E7 in order to achieve such effects. In normal infections, the E4 protein is made abundantly in the later stages of the viral life cycle. Though extensive amounts of work have been carried out to define the function of E4, it still remains unclear. In this study, several approaches have been used to try and determine the functions of E4. First, a cell-penetrating fusion protein was designed and produced in order to circumvent the chronic difficulties of expressing E4 in mammalian cells. Unfortunately, this approach was not successful due to precipitation of the purified fusion protein. Second, the observation that E4 accumulates in cells having modified their adhesion properties led to the hypothesis that E4 might be involved in the differentiation process of keratinocytes. Preliminary results suggest that E4 triggers differentiation. Last, as E4 has been reported to collapse the cytokeratin network of keratinocytes, a direct approach using atomic force microscopy has allowed us to test the potential modification of mechanical properties of cells harboring reorganized cytokeratin networks. If so, a potential role for E4 in viral particle release could be hypothesized. 2. Résumé Il a été établi que le cancer du col de l'utérus se développe essentiellement à la suite d'une infection par le virus du papillome humain (HPV). Dans la majorité des cas analysés, de l'ADN du HPV de type 16 (HPV16) est détecté. Les étapes initiales de la transformation d'une cellule infectée sont mal connues mais il semble qu'une rupture du génome viral, normalement épisomal, suivi d'une intégration dans le génome de la cellule hôte soient des étapes nécessaires dans la plupart des cas. Or il semble qu'il y ait une sélection pour les cas où l'expression des oncogènes viraux E6 et E7 soit favorisée alors que l'expression des gènes E2 et E4 est en général impossible. Par contre, dans une infection dite normale où le génome viral n'est pas rompu, il n'y pas développement de cancer et tous les gènes viraux sont exprimés. L'ordre dans lequel les protéines virales sont produites, et donc le cycle de réplication du virus, est intimement lié au processus de différentiation de la cellule hôte. L'étude des protéines oncogènes E6 et E7 a révélé des fonctions clés dans le processus de transformation des cellules infectées telles que la dégradation du suppresseur de tumeur p53, la dérégulation de la voie de signalisation Rb ainsi que l'activation de la télomérase. Toutes ces activités sont nécessaires au développement de lésions cancéreuses. Toutefois, il semble que l'expression du gène E2 doit être empêchée afin que suffisamment des protéines E6 et E7 soient produites. Lorsque le gène E2 est exprimé, et donc lorsque le génome viral n'est pas rompu, les protéines E6 et E7 n'entraînent pas de telles conséquences. Le gène E4, qui se trouve dans la séquence codante de E2, a aussi besoin d'un génome viral intact pour être exprimé. Dans une infection normale, le gène E4 est exprimé abondamment dans les dernières étapes de la réplication du virus. Bien que de nombreuses études aient été menées afin de déterminer la fonction virale à E4, aucun résultat n'apparaît évident. Dans ce travail, plusieurs approches ont été utilisées afin d'adresser cette question. Premièrement, une protéine de fusion TAT-E4 a été produite et purifiée. Cette protéine, pouvant entrer dans les cellules vivantes par diffusion au travers de la membrane plasmique, aurait permis d'éviter ainsi les problèmes chroniques rencontrés lors de l'expression de E4 dans les cellules mammifères. Malheureusement, cette stratégie n'a pas pu être utilisée à cause de la précipitation de la protéine purifiée. Ensuite, l'observation que E4 s'accumule dans les cellules ayant modifié leurs propriétés d'adhésion a suggéré que E4 pourrait être impliqué dans le procédé de différentiation des kératinocytes. Des résultats préliminaires supportent cette possibilité. Enfin, il a été montré que E4 pouvait induire une réorganisation du réseau des cytokératines. Une approche directe utilisant le microscope à force atomique nous a ainsi permis de tester une potentielle modification des propriétés mécaniques de cellules ayant modifié leur réseau de cytokératines en présence de E4. Si tel est le cas, un rôle dans la libération de particules virales peut être proposé pour E4.

A Study on Fractionation and Ultrafiltration of Proteins with Characterized Modified and Unmodified Membranes

Membrane filtration has become increasingly attractive in the processing of both foodand biotechnological products. However, the poor selectivity of the membranes and fouling are the critical factors limiting the development of UF systems for the specific fractionation of protein mixtures. This thesis gives an overview on fractionation of proteins from model protein solutions or from biological solutions. An attempt was made to improve the selectivity of the available membranes by modifying the membranes and by exploiting the different electrostatic interactions between the proteins and the membrane pore surfaces. Fractionation and UF behavior of proteins in the model solutions and in the corresponding biological solutions were compared. Characterization of the membranes and protein adsorptionto the membrane were investigated with combined flux and streaming potential studies. It has been shown that fouling of the membranes can be reduced using "self-rejecting" membranes at pH values where electrostatic repulsion is achieved between the membrane and the proteins in solution. This effect is best shown in UF of dilute single protein solutions at low ionic strengths and low pressures. Fractionation of model proteins in single, binary, and ternary solutionshas been carried out. The results have been compared to the results obtained from fractination of biological solutions. It was generally observed that fractination of proteins from biological solutions are more difficult to carry out owingto the presence of non studied protein components with different properties. Itcan be generally concluded that it is easier to enrich the smaller protein in the permeate but it is also possible to enrich the larger protein in the permeateat pH values close to the isoelectric point of the protein. It should be possible to find an optimal flux and modification to effectively improve the fractination of proteins even with very similar molar masses.

Spermiogenesis and spermatozoon of the liver fluke Mediogonimus jourdanei (Microphalloidea: Prosthogonimidae), a parasite of Myodes glareolus (Rodentia: Cricetidae)

Spermatological characters of the liver fluke Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 were studied by means of transmission and scanning electron microscopy. Spermiogenesis begins with the formation of the differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. These two centrioles originate two free flagella that undergo a 90 degrees rotation before fusing with the median cytoplasmic process. Both nuclear and mitochondrial migrations toward the median cytoplasmic process occur before the proximodistal fusion of flagella. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon. The mature sperm of M. jourdanei measures about 260 microm and presents two axonemes of different lengths with the typical pattern of the Trepaxonemata, two bundles of parallel cortical microtubules, one mitochondrion, a nucleus and granules of glycogen. An analysis of all the microphalloidean species studied to date emphasised some differences in certain characters found in Maritrema linguilla Jägerskiöld, 1908 and Ganeo tigrinum Mehra et Negi, 1928 in comparison to those in the remaining microphalloideans. The presence and variability of such ultrastructural characters according to family, superfamily or order have led several authors to propose their use in the analysis of trematode relationships and phylogeny. Therefore, apart from producing new data on the family Prosthogonimidae, the present study also compares the spermatological organization of M jourdanei with other available ultrastructural studies focusing on the Microphalloidea.

Ultrastructural study of spermiogenesis and the spermatozoon of the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009, a parasite of the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes, Clariidae)

Spermiogenesis in the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009 shows typical characteristics of the type I spermiogenesis. These include the formation of distal cytoplasmic protrusions forming the differentiation zones, lined by cortical microtubules and containing two centrioles. An electron-dense material is present in the apical region of the differentiation zone during the early stages of spermiogenesis. Each centriole is associated to a striated rootlet, being separated by an intercentriolar body. Two free and unequal flagella originate from the centrioles and develop on the lateral sides of the differentiation zone. A median cytoplasmic process is formed between the flagella. Later these flagella rotate, become parallel to the median cytoplasmic process and finally fuse proximodistally with the latter. It is interesting to note that both flagellar growth and rotation are asynchronous. Later, the nucleus enlarges and penetrates into the spermatid body. Finally, the ring of arching membranes is strangled and the young spermatozoon is detached from the residual cytoplasm. The mature spermatozoon presents two axonemes of the 9 +"1" trepaxonematan pattern, crested body, parallel nucleus and cortical microtubules, and glycogen granules. Thus, it corresponds to the type II spermatozoon, described in almost all Proteocephalidea. The anterior extremity of the gamete is characterized by the presence of an apical cone surrounded by the lateral projections of the crested body. An arc formed by some thick and parallel cortical microtubules appears at the level of the centriole. They surround the centriole and later the first axoneme. This arc of electron-dense microtubules disorganizes when the second axoneme appears, and then two parallel rows of thin cortical microtubules are observed. The posterior extremity of the male gamete exhibits some cortical microtubules. This type of posterior extremity has never been described in proteocephalidean cestodes. The ultrastructural features of the spermatozoon/spermiogenesis of the Proteocephalidea species are analyzed and compared.

Spermiogenesis and ultrastructure of the spermatozoon of Wardula capitellata (Digenea, Mesometridae), an intestinal parasite of the sparid teleost Sarpa salpa in Senegal

The spermiogenesis process in Wardula capitellata begins with the formation of a differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. Each centriole develops into a free flagellum orthogonal to a median cytoplasmic process. Later these flagella rotate and become parallel to the median cytoplasmic process, which already exhibits two electron-dense areas and spinelike bodies before its proximodistal fusion with the flagella. The final stage of the spermiogenesis is characterized by the constriction of the ring of arched membranes, giving rise to the young spermatozoon, which detaches from the residual cytoplasm. The mature spermatozoon of W. capitellata presents most of the classical characters reported in digenean spermatozoa such as two axonemes of different lengths of the 9 + '1' trepaxonematan pattern, nucleus, mitochondrion, two bundles of parallel cortical microtubules and granules of glycogen. However, some peculiarities such as two lateral expansions accompanied by external ornamentation of the plasma membrane and spinelike bodies characterize the mature sperm. Moreover, a new spermatological character is described for the first time, the so-called cytoplasmic ornamented buttons.