Characterisation of a track structure imaging detector

The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presented, which detects positive ions produced by radiation interacting with a gas-sensitive volume in order to obtain a high resolution image of the radiation track structure. The characterisation of the detector prototype was performed and different configurations of the device were tested by varying the detector cathode material and the working gas. Preliminary results show that the ionisation cluster size distribution can be obtained with this approach. Further work is planned to improve the detector efficiency in order to register the complete three-dimensional track structure of ionising radiation.

Towards a better understanding of Apis mellifera and Varroa destructor microbiomes: introducing 'phyloh' as a novel phylogenetic diversity analysis tool

The study of diversity in biological communities is an intriguing field. Huge amount of data are nowadays available (provided by the innovative DNA sequencing techniques), and management, analysis and display of results are not trivial. Here, we propose for the first time the use of phylogenetic entropy as a measure of bacterial diversity in studies of microbial community structure. We then compared our new method (i.e. the web tool phyloh) for partitioning phylogenetic diversity with the traditional approach in diversity analyses of bacteria communities. We tested phyloh to characterize microbiome in the honeybee (Apis mellifera, Insecta: Hymenoptera) and its parasitic mite varroa (Varroa destructor, Arachnida: Parasitiformes). The rationale is that the comparative analysis of honeybee and varroa microbiomes could open new perspectives concerning the role of the parasites on honeybee colonies health. Our results showed a dramatic change of the honeybee microbiome when varroa occurs, suggesting that this parasite is able to influence host microbiome. Among the different approaches used, only the entropy method, in conjunction with phylogenetic constraint as implemented in phyloh, was able to discriminate varroa microbiome from that of parasitized honeybees. In conclusion, we foresee that the use of phylogenetic entropy could become a new standard in the analyses of community structure, in particular to prove the contribution of each biological entity to the overall diversity.

A DNA barcoding approach to identify plant species in multiflower honey

The purpose of this study was to test the ability of DNA barcoding to identify the plant origins of processed honey. Four multifloral honeys produced at different sites in a floristically rich area in the northern Italian Alps were examined by using the rbcL and trnH-psbA plastid regions as barcode markers. An extensive reference database of barcode sequences was generated for the local flora to determine the taxonomic composition of honey. Thirty-nine plant species were identified in the four honey samples, each of which originated from a mix of common plants belonging to Castanea, Quercus, Fagus and several herbaceous taxa. Interestingly, at least one endemic plant was found in all four honey samples, providing a clear signature for the geographic identity of these products. DNA of the toxic plant Atropa belladonna was detected in one sample, illustrating the usefulness of DNA barcoding for evaluating the safety of honey.

Experimental verification of IMPT treatment plans in an anthropomorphic phantom in the presence of delivery uncertainties

Clinically relevant intensity modulated proton therapy (IMPT) treatment plans were measured in a newly developed anthropomorphic phantom (i) to assess plan accuracy in the presence of high heterogeneity and (ii) to measure plan robustness in the case of treatment uncertainties (range and spatial). The new phantom consists of five different tissue substitute materials simulating different tissue types and was cut into sagittal planes so as to facilitate the verification of co-planar proton fields. GafChromic films were positioned in the different planes of the phantom, and 3D-IMPT and distal edge tracking (DET) plans were delivered to a volume simulating a skull base chordoma. In addition, treatments planned on CTs of the phantom with HU units modified were delivered to simulate systematic range uncertainties (range-error treatments). Finally, plans were delivered with the phantom rotated to simulate spatial errors. Results show excellent agreement between the calculated and the measured dose distribution: >99% and 98% of points with a gamma value <1 (3%/3 mm) for the 3D-IMPT and the DET plan, respectively. For both range and spatial errors, the 3D-IMPT plan was more robust than the DET plan. Both plans were more robust to range than to the spatial uncertainties. Finally, for range error treatments, measured distributions were compared to a model for predicting delivery errors in the treatment planning system. Good agreement has been found between the model and the measurements for both types of IMPT plan.

Long-term outcomes of a pilot CT screening for lung cancer

BACKGROUND

Low-dose computed tomography (CT) screening can detect early stage lung cancer in high-risk populations. However, no data on repeated annual screening over more than 5 years are available, and the impact of screening on lung cancer mortality is controversial.

METHODS

We analysed outcomes in high-risk asymptomatic volunteers (smokers and former smokers, >50 years) enrolled in a pilot study over 1 year from June 2000, who received annual low-dose CT for 7 years. Cumulative lung cancer incidence and survival were represented by Kaplan-Meier curves. Standardized incidence and mortality ratios were used to estimate risks relative to the general Italian and US population.

RESULTS

Compliance was 86% at the end of the seventh year in 1035 recruited volunteers (71% men, mean age 58 years). Lung cancer was diagnosed in 54 (5.3%); radical surgery was possible in 48/54 (87%); 39/54 (72%) had stage I disease. Five-year survival was 63% overall, 89% for stage I cases. During 6308 person-years of observation, 47 participants had died versus 75 expected in the Italian general population standardised for age and sex. Fourteen lung cancer deaths were registered versus 27 expected in a standardised US smoker population.

CONCLUSIONS

Seventy percent of screening-diagnosed patients had stage I disease, and the survival of screen-detected cancer patients was high. Lung cancer mortality was favourable compared to age- and sex-matched population of US smokers, suggesting that mortality can be lowered by screening, although larger trials with longer follow-up are necessary to confirm these findings.

Efficacy of HT 7 point acupressure stimulation in the treatment of insomnia in cancer patients and in patients suffering from disorders other than cancer

AIM

The induction of sleep would depend on interaction between gabaergic system and the pineal gland through its main hormone melatonin. Until few years ago benzodiazepines were the only drugs effective in the treatment of insomnia. Recently, however, both melatonin and acupressure have appear to be active in sleep disorders. The aim of study was to evaluate the efficacy of HT 7 point acupressure in insomnia.

METHODS

The study enrolled 25 patients affected by sleep disorders, 14 of whom had a neoplastic disease. They were treated by HT 7 stimulation for al least two consecutive weeks using a medical device named H7 Insomnia Control.

RESULTS

An improvement in the quality of sleep was achieved in 15/25 (60%) patients, with a more evident efficacy in cancer patients (11/14 [79%]).

CONCLUSION

This study confirms previous clinical data showing the efficacy of acupressure in the treatment of sleep disorders, particularly in cancer-related insomnia.

A progress study of 100 cancer patients treated by acupressure for chemotherapy-induced vomiting after failure with the pharmacological approach

AIM

The recent rediscovery of the natural traditional medical sciences has contributed to improve the treatment of the human diseases and, in particular, it has been shown that the pharmacological approach is not the only possible strategy in the treatment of nausea and vomiting, since bioenergetic approaches, such as acupressure and acupuncture, may also counteract the onset of vomiting due to different causes. Previous preliminary clinical studies had already suggested a possible efficacy of acupressure also in the treatment of chemotherapy-induced vomiting resistant to the classical antiemetic drugs. The aim of this study was to confirm these preliminary data.

METHODS

The study was performed in 100 consecutive metastatic solid tumour patients, who underwent chemotherapy for their advanced neoplastic disease, and who had no benefit from the standard antiemetic agents, including corticosteroids, antidopaminergics and 5-HT 3R-antagonists. Acupressure was made by a stimulation of PC6 acupoint.

RESULTS

The emetic symptomatology was reduced by acupressure in 68/100 (68%) patients, without significant differences in relation to tumour histotype. The lowest efficacy was observed in patients treated by anthracycline-containing regimens, without, however, statistically significant differences with respect to the other chemotherapeutic combinations.

CONCLUSION

This study confirms previous preliminary clinical results, which had already suggested the potential efficacy of acupressure in the treatment of vomiting due to cancer chemotherapy. Therefore, acupressure may be successfully included within the therapeutic strategies of cancer chemotherapy-induced vomiting.

A case-control study of Panicum Miliaceum in the treatment of cancer chemotherapy-induced alopecia

AIM

Alopecia still remains one of the most untreatable side-effects induced by cancer chemotherapy. According to the phytotherapeutic tradition, Panicum Miliaceum has been proven to be effective in the prevention of hair loss for different reasons. At present, however, there are no data about its possible efficacy in the treatment of cancer chemotherapy-induce alopecia. The aim of this study was to analyze the efficacy of Panicum Miliaceum in cancer patients treated with the most potent chemotherapeutic drugs in terms of hair loss, consisting of cisplatin (CDDP) and anthracyclines.

METHODS

This case-control study included 28 cancer patients concomitantly treated with Panicum Miliaceum and 56 patients receiving the same combinations of chemotherapy alone as a control group. Panicum Miliaceum was given orally at 300 mg (daily dose) 3 times per day, every day until the end of chemotherapy. The grade of hair loss was assessed by World Health Organization (WHO) criteria.

RESULTS

The percentage of alopecia of third grade observed in patients concomitantly treated with Panicum Miliaceum in association with CDDP-containing regimens was significantly lower than that found in those who received the chemotherapy only. The percentage was also lower under anthracycline-containing schedules, without, however, statistically significant differences. Panicum Miliaceum therapy was substantially well tolerated in all patients.

RESULTS

This preliminary study would suggest that the concomitant treatment with Panicum Miliaceum may be effective in preventing hair loss induced by CDDP-containing chemotherapies, whereas the benefit was lower in patients treated with anthracyclines. Future randomized studies will be necessary to confirm these preliminary

Effect of acupressure on nausea and vomiting induced by chemotherapy in cancer patients

AIM

Corticosteroids, antidopaminergig agents and 5-HT3 antagonists are the most commonly used drugs in the treatment of chemotherapy-induced vomiting. Acupuncture and acupressure have also appeared to exert antiemetic effects. The aim of this study was to evaluate the efficacy of acupressure in the treatment of chemotherapy-induced vomiting resistant to the standard antiemetic therapies.

METHODS

The study included 40 consecutive advanced cancer patients with untreatable chemotherapy-induced vomiting. Colorectal cancer, lung cancer and breast cancer were the neoplasm most frequent in our patients. According to tumour histotype, patients received chemotherapeutic regimens containing the main emetic cytotoxic agents, including cisplatin and athracyclines. Acupressure was made by PC6 point stimulation for at least 6 h/day at the onset of chemotherapy.

RESULTS

The therapeutic approach was well accepted by the overall patients. An evident improvement in the emetic symptomatology was achieved in 28/40 (70%) patients, without significant differences in relation to neither tumor histotype, nor type of chemotherapeutic agent.

CONCLUSIONS

This preliminary study seems to suggest that a bioenergetic approach by acupressure on PC6 point may be effective in the treatment of chemotherapy-induced vomiting resistant to the conventional pharmacological strategies, as previously demonstrated for vomiting occurring during pregnancy.

Preoperative assessment in patients with postintubation tracheal stenosis : Rigid and flexible bronchoscopy versus spiral CT scan with multiplanar reconstructions

BACKGROUND

Postintubation stenosis remains the most frequent indication for tracheal surgery. Rigid bronchoscopy has traditionally been considered the technique of choice for the preoperative diagnostic assessment. However, this technique is not routinely available, and new techniques such as flexible videobronchoscopy and spiral computed tomography (CT) scan with multiplanar reconstructions have been proposed as alternatives to rigid bronchoscopy. The aim of this study was to compare these techniques in the diagnostic assessment of patients with tracheal stenosis submitted to surgical treatment.

METHODS

Twelve patients who underwent airway resection and reconstruction for postintubation tracheal and laryngotracheal stenosis were preoperatively evaluated with rigid and flexible bronchoscopy and with spiral CT scan with multiplanar reconstructions. The following parameters were examined: involvement of subglottic larynx, length of the stenosis, and associated lesions. The results were compared with the intraoperative findings.

RESULTS

The accuracy of rigid bronchoscopy, flexible bronchoscopy, and CT scan in the evaluation of the involvement of subglottic larynx was, respectively, 92%, 83%, and 83%. The evaluation of the length of the stenosis was correct in 83%, 92%, and 25% of the patients, respectively, with rigid bronchoscopy, flexible bronchoscopy, and CT scan. A significant correlation was observed between the length of the stenosis measured intraoperatively and preoperatively with rigid (p < 0.001) and flexible bronchoscopy (p < 0.05) but not with CT scan (p = 0.08). The three techniques correctly showed the presence of an associated tracheoesophageal fistula in two patients, but CT scan did not correctly show the exact location of the fistula in relation to the airway. Flexible bronchoscopy was the only effective technique in the assessment of laryngeal function.

CONCLUSIONS

Rigid bronchoscopy remains the procedure of choice in the evaluation of candidates for tracheal resection and reconstruction for postintubation stenosis, and it should be available in centers that perform surgery of the airway. Flexible bronchoscopy and CT scan have to be considered complementary techniques in the evaluation of laryngeal function and during follow-up.

Phylogeny of Wolbachia pipientis based on gltA, groEL and ftsZ gene sequences: clustering of arthropod and nematode symbionts in the F supergroup, and evidence for further diversity in the Wolbachia tree

Current phylogenies of the intracellular bacteria belonging to the genus Wolbachia identify six major clades (A–F), termed ‘supergroups’, but the branching order of these supergroups remains unresolved. Supergroups A, B and E include most of the wolbachiae found thus far in arthropods, while supergroups C and D include most of those found in filarial nematodes. Members of supergroup F have been found in arthropods (i.e. termites), and have previously been detected in the nematode Mansonella ozzardi, a causative agent of human filariasis. To resolve the phylogenetic positions of Wolbachia from Mansonella spp., and other novel strains from the flea Ctenocephalides felis and the filarial nematode Dipetalonema gracile, the authors generated new DNA sequences of the Wolbachia genes encoding citrate synthase (gltA), heat-shock protein 60 (groEL), and the cell division protein ftsZ. Phylogenetic analysis confirmed the designation of Wolbachia from Mansonella spp. as a member of the F supergroup. In addition, it was found that divergent lineages from Dip. gracile and Cte. felis lack any clear affiliation with known supergroups, indicating further genetic diversity within the Wolbachia genus. Finally, although the data generated did not permit clear resolution of the root of the global Wolbachia tree, the results suggest that the transfer of Wolbachia spp. from arthropods to nematodes (or vice versa) probably occurred more than once.

Neoadjuvant chemotherapy and pneumonectomy in a lung cancer patient on hemodialysis

Major pulmonary resections are rarely performed in non-small cell lung cancer patients on hemodialysis. To date only two cases of pneumonectomy performed in such patients are reported in the literature. Moreover, chemotherapy, as a treatment for advanced non-small cell lung cancer, is not routinely administered to patients with end-stage renal disease requiring hemodialysis. We present the case of a stage IIIB non-small cell lung cancer patient on hemodialysis who successfully underwent neoadjuvant chemotherapy followed by pneumonectomy. To our knowledge, this is the first case of non-small cell lung cancer patient on hemodialysis reported in the literature who successfully underwent this type of combined therapy.

Clinical, cytological and molecular evidence of Mesocestoides sp. infection in a dog from Italy

A 12-year-old, 13 kg, mixed-breed male dog was referred for anorexia and depression. The dog showed discomfort on abdominal palpation. Abdominal ultrasound examination revealed multiple, small, round anechoic cystic structures. Cystic fluid obtained with fine needle aspiration contained several 2-4 mm white motile flecks. Microscopic examination of the fluid revealed numerous irregularly shaped organisms measuring several hundred microns to 3 mm, the morphology of which was suggestive of intact and fragmented acephalic metacestodes of the genus Mesocestoides sp. Molecular analysis confirmed that the peritoneal infection was caused by Mesocestoides sp.

Molecular systematics and diagnosis

This collection of articles provides an account of six presentations delivered at the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology(WAAVP) (held in New Orleans, Louisiana, USA, from 10 to 14 August 2003) in a symposium session on Molecular Systematics and Diagnosis, organised and chaired by R.B. Gasser and D.S. Zarlenga. The focus was on recent advances in molecular tools for specific and genotypic identification,diagnosis, systematics and population genetics, with special emphasis on investigations of parasitic nematodes and protists.

Ultrastructural evidence of the degenerative events occurring during embryogenesis of the filarial nematode Brugia pahangi after tetracycline treatment

Intracellular bacteria belonging to the genus Wolbachia have been described in filarial nematodes and these microorganisms appear to have evolved an obligatory mutualistic association with their filarial hosts. In fact, antibiotic treatment leads to the clearance of bacteria from worms resulting in a block in embryogenesis and, eventually, death of adult filariae. Currently, the antifilarial action of antibiotic treatment is interpreted as a secondary consequence of the bacteriostatic activity against Wolbachia endosymbionts. Here, we demonstrate by transmission electron microscopy the degenerative events occurring during embryogenesis of Brugia pahangi after tetracycline treatment. After 56 days of treatment the cytoplasm of hypodermal cords was totally void of Wolbachia and numerous vacuoles, residual of cytolitic activity, were observed. In the ovary, the morphology of the oocytes was well conserved 33 days after treatment, but the texture of symbiotic bacteria appeared altered. After 56 days of treatment embryogenesis was dramatically affected and the terminal portion of the ovary appeared totally empty. The authors suggest that the symbiotic bacteria play a direct role in worm metabolism and a long-term bacteriostatic effect may block bacterial activity involved in the active control of cytolysis. As a consequence, the bacteriophorous vacuole is transformed into a digestive vacuole and the whole symbiotic population is disrupted.

Immunohistochemical/immunogold detection and distribution of the endosymbiont Wolbachia of Dirofilaria immitis and Brugia pahangi using a polyclonal antiserum raised against WSP (Wolbachia surface protein)

Intracellular bacteria in filarial nematodes were described as early as the 1970s, yet it was only with the work on Dirofilaria immitis, the agent of canine and feline heartworm disease, that these microorganisms were identified as belonging to Wolbachia, a genus known for encompassing bacteria infecting insects and other arthropods. The implications for the presence of intracellular bacteria in filarial nematodes is now the subject of intense research, particularly regarding their role in the immunology and pathogenesis of disease in infected humans and animals and as a possible target for therapy. Here, the authors report results on the immunohistochemical and immunogold staining of Wolbachia in D. immitis and Brugia pahangi using polyclonal antibodies raised against the recombinant Wolbachia surface protein (WSP). The bacteria were present in the lateral hypodermal chords of both male and female worms and in the reproductive tract of adult females (oocytes, morulae, microfilariae). In D. immitis and B. pahangi from animals treated with tetracycline, positive staining was observed in the lateral chords of adult males and females, but was absent from the oocytes and morulae. These results indicate that Wolbachia endosymbionts can be identified immunohistochemically with anti-WSP polyclonal antibodies, that their distribution matches that already described for Wolbachia of other filarial worms, and that antibiotic treatment may impede the vertical transmission of these bacteria. Unequivocal detection of Wolbachia is essential for the study of this symbiont, in particular to monitor the effects of antibiotic treatment on worms. The use of a specific marker for bacteria in their nematode hosts represents an extremely useful tool in evaluating the pathogenic role and the effect of antibiotic treatment on these potential targets in the control of filarial disease.

dnaA gene sequences from Wolbachia pipientis support subdivision into supergroups and provide no evidence for recombination in the lineages infecting nematodes

Wolbachia pipientis is an intracellular bacterial endosymbiont of arthropods and filarial nematodes. Six main supergroups of W. pipientis have been described: supergroups A, B, E, and F encompass arthropod wolbachiae; supergroups C and D encompass nematode wolbachiae. The description of these six supergroups has been based on the analysis of only two genes (ftsZ and 16S rDNA) and before decisions are taken on the taxonomic status of the six supergroups, analysis of further genes is required. In addition, the branching order of the six supergroups is still unresolved. Sequence information from other genes is also needed to allow phylogenesis to be addressed through the analysis of a higher number of characters. Here we report sequences from a portion of the gene coding for the DNAA protein of W pipientis, generated from the endosymbionts of 22 host species. Phylogenies based on dnaA gene sequences are congruent with the existence of at least six supergroups of W pipientis. In addition, subtrees generated for nematode wolbachiae in supergroups C and D were compared to the trees based on the already available gene sequences (ftsZ, 16S rDNA and wsp). The congruence observed among the trees based on the different genes agrees with the hypothesis that recombination does not occur in nematode wolbachiae.

Different rates of nucleotide substitutions in Wolbachia endosymbionts of arthropods and nematodes: arms race or host shifts?

The genus Wolbachia encompasses intracellular bacteria found in arthropods and in filarial nematodes. In arthropods, Wolbachia is primarily a reproductive parasite and shows relatively frequent horizontal transfer between host species, while in nematodes it appears to be a mutualist and is strictly vertically transmitted. We can expect that different selective pressures are acting on their genomes. Here we present an analysis of three Wolbachia genes, wsp, ftsZ and dnaA. In wsp of arthropod Wolbachia, an excess of non-synonymous substitutions was observed, providing evidence for positive selection. In nematode Wolbachia, no evidence for positive selection was found. Pressure for amino acid variation in wsp of arthropod Wolbachia could derive either from an arms race with the host or from the occurrence of more frequent hosts shifts due to horizontal transmission. In nematode Wolbachia, the lack of positively selected sites could result from the absence of an arms race, or from the homogeneity of the biochemical environment they exist in (ensured by strict vertical transmission). In ftsZ minor differences in substitution patterns were observed between arthropod and nematode Wolbachia, only in the 3'-portion of the gene. dnaA showed comparable patterns of variation in both lineages, with evidence for strong conservation.

Tetracycline treatment and sex-ratio distortion: a role for Wolbachia in the moulting of filarial nematodes?

Filarial nematodes harbour intracellular bacteria of the genus Wolbachia. These bacteria are thought to be beneficial to the host nematode. Indeed, tetracycline treatments reduce the population of Wolbachia in filarial worms and have detrimental effects on the nematode. Even though various antibiotic-curing experiments have been performed on filariae, the actual role of Wolbachia in the biology of these nematodes is not yet clear. To address this issue, we designed a first experiment on a model filaria (Brugia pahangi), maintained in the gerbil (Meriones unguiculatus). In this experiment, timing of tetracycline treatment was set on the basis of the larval stage of the nematode. This first experiment showed that 2 weeks of treatment started after the L(4)-L(5) moult of males, but before the moult of females, led to significant sex-ratio distortion of the nematodes. We thus hypothesised that tetracycline interferes with the moult in B. pahangi. To test this hypothesis, we designed a second experiment in which antibiotic treatments were started (1). before the moult of both sexes, (2). after the moult of males but before the moult of females, or (3). after the moult of both sexes. Treatment 1 determined a reduction of worm recovery with no sex bias. Treatment 2 led to a male-biased sex-ratio. Treatment 3 had no effect on either worm recovery or sex-ratio. These results thus support the hypothesis that tetracycline treatment interferes with the L(4)-L(5) moult of B. pahangi. The nematodes recovered from the treated and control animals were examined for the presence of Wolbachia using both immunohistochemistry and real-time PCR. In general, nematodes from treated animals showed a dramatic reduction in Wolbachia content. In one group, Wolbachia depletion, as observed at the end of the treatment, was followed by a rebound to 'normal' values 160 days later. Prospects for antifilarial therapy using Wolbachia-targeted tetracycline treatments should thus take into account the possibility of Wolbachia rebound.

Does fertilization in the filarial nematode Dirofilaria immitis occur through endocytosis of spermatozoa?

Information on the ultrastructural details of fertilization in filarial nematodes are still unavailable. Here we report new data on this process in Dirofilaria immits, the heartworm of dogs and cats. Electron microscopy allowed us to observe oocytes engulfing spermatozoa through an endocytosis-like process. We also observed spermatozoa inside the oocytes which still possessed their plasma membrane and which were clearly enveloped by a further membrane, likely derived from the endocytosis process. At this stage, at the interface between the sperm membrane and the endocytotic membrane (vacuolar space), we observed flocculent material in the proximity of the membranous organelles (MOs) of the sperm. In the proximity of the MOs, we also observed the enlargement of the vacuolar space. Other images showed the dissolution of the sperm membrane, and the release of nuclear masses and organelles in the egg cytoplasm. We did not observe the fusion of lysosomes to the endocytotic vacuoles. In addition, the lysis of the sperm organelles has never been observed inside the vacuoles containing the whole sperm. Thus we suggest that the degradation of the endocytotic and sperm plasma membranes is determined by material released by the MOs. Since we did not observe the entry of sperm into the oocytes by other mechanisms, we also suggest that endocytosis is the normal process used by the spermatozoon to get into the egg cytoplasm in D. immitis. Finally, during our observations of the seminal receptacle we did not observe any structure in the spermatozoa which could be interpreted as an intracellular bacterium. This is consistent with previous results indicating that the bacterium Wolbachia in filarial nematodes is not transmitted through the sperm.

Real-time PCR for quantification of the bacterial endosymbionts (Wolbachia) of filarial nematodes

Filarial nematodes harbour intracellular symbiotic bacteria belonging to the genus Wolbachia. Wolbachia is thought to play an important role in the biology of the nematode. Moreover, Wolbachia appears to be involved in the immunopathogenesis of filariasis and in the onset of the side-effects of antifilarial therapy. Investigations in these research areas require reliable methods to quantify Wolbachia both in nematodes and in vertebrate tissues. To this purpose, we designed a quantitative real-time PCR targeted on the ftsZ gene of the Wolbachia of Brugia pahangi, a model filarial species maintained in gerbils. The method was applied to quantify Wolbachia in Brugia pahangi, from animals with or without tetracycline treatment. Our results show that tetracycline treatment leads to dramatic reduction or clearance of Wolbachia from the nematode. Results obtained from different replicates were reproducible and the method appeared very sensitive compared to other PCR protocols for Wolbachia detection. Real-time PCR is thus an appropriate method for investigations on the biological role of Wolbachia and on the implication of these bacteria in the pathogenesis of filariasis. With slight modifications of the primers and probe, the protocol we have developed could be applied in studies of the human pathogen Brugia malayi and on the model filarial species Litomosoides sigmodontis.

Molecular identification of Wolbachia from the filarial nematode Mansonella ozzardi

Mansonella ozzardi, a filarial parasite of humans in Latin America, has been shown to harbour intracellular bacteria not yet identified. Here we show that these bacteria, like those of other filarial nematodes, belong to the genus Wolbachia (alpha 2 Proteobacteria; Rickettsiales). Their unambiguous placement in the Wolbachia group was shown by 16S rDNA sequence analysis. However, the exact position of the Wolbachia from M. ozzardi relative to the other wolbachiae is not clear. Indeed, 16S rDNA sequence analysis places this bacterium at a deep branch in Wolbachia evolution. It is interesting that analysis of the 5S rDNA gene spacer of the nematode host also suggests that the genus Mansonella, together with the genus Loa, could represent a deep-branching lineage in filarial evolution.

A phylogenetic analysis of filarial nematodes: comparison with the phylogeny of Wolbachia endosymbionts

Infection with the endosymbiotic bacteria Wolbachia is widespread in filarial nematodes. Previous studies have suggested concordance between the phylogeny of Wolbachia with that of their nematode hosts. However, there is only one published molecular phylogenetic study of filarial species, based on the 5S rRNA gene spacer. The phylogeny proposed by this study is partially incongruent with previous classifications of filarial nematodes, based on morphological characters. Furthermore, both traditional classifications and molecular phylogenies are, in part, inconsistent with the phylogeny of Wolbachia. Here we report mitochondrial cytochrome oxidase I (COI) gene sequences for 11 species of filaria and for another spirurid nematode which was included as an outgroup. In addition, 16S rRNA, wsp and ftsZ gene sequences were generated for the Wolbachia of several filarial species, in order to complete the available data sets and further resolve the phylogeny of Wolbachia in nematodes. We used these data to evaluate whether nematode and Wolbachia phylogenies are concordant. Some of the possible phylogenetic reconstructions based on COI gene were congruent with the phylogeny of Wolbachia and supported the grouping of the rodent filaria Litomosoides sigmodontis with the lymphatic filariae (i.e. Brugia spp. and Wuchereria spp.) and the sister group relationship of Dirofilaria spp. and Onchocerca spp. However, the placement of the Wolbachia-free filaria Acanthocheilonema viteae is ambiguous and dependent on the phylogenetic methods used.

Insurance-based advantage to helpers in a tropical hover wasp

The origin and maintenance of eusociality is a central problem in evolutionary biology. Eusocial groups contain individuals that forfeit their own reproduction in order to help others reproduce. In facultatively eusocial taxa, offspring can choose whether to found new nests or become helpers in their natal groups. In many facultatively eusocial insects, offspring need continuous care during development, but adult carers have life expectancies shorter than the developmental period. When a lone foundress dies, her partly reared brood are usually doomed. Here, we show that helpers in a tropical hover wasp (Liostenogaster flavolineata) have an insurance-based advantage over lone foundresses because after a helper dies, most of the brood that she has partly reared will be brought to maturity by surviving nest-mates. After some of the helpers are experimentally removed from a multi-female nest, the reduced group is left with more brood than it would normally rear. We found that larger, more valuable extra brood were reared through to maturity, but not smaller, less valuable brood. Smaller brood may be sacrificed to feed larger brood, and reduced groups probably benefited from increased short-term helper recruitment. Rearing extra brood did not increase adult mortality or brood development time.