RESUMEN
BACKGROUND: Ticks transmit pathogens of medical and veterinary importance and are an increasing threat to human and animal health. Assessing disease risk and developing new control strategies requires identifying members of the tick-borne microbiota as well as their temporal dynamics and interactions. METHODS: Using high-throughput sequencing, we studied the Ixodes ricinus microbiota and its temporal dynamics. 371 nymphs were monthly collected during three consecutive years in a peri-urban forest. After a Poisson lognormal model was adjusted to our data set, a principal component analysis, sparse network reconstruction, and differential analysis allowed us to assess seasonal and monthly variability of I. ricinus microbiota and interactions within this community. RESULTS: Around 75% of the detected sequences belonged to five genera known to be maternally inherited bacteria in arthropods and to potentially circulate in ticks: Candidatus Midichloria, Rickettsia, Spiroplasma, Arsenophonus and Wolbachia. The structure of the I. ricinus microbiota varied over time with interannual recurrence and seemed to be mainly driven by OTUs commonly found in the environment. Total network analysis revealed a majority of positive partial correlations. We identified strong relationships between OTUs belonging to Wolbachia and Arsenophonus, evidence for the presence of the parasitoid wasp Ixodiphagus hookeri in ticks. Other associations were observed between the tick symbiont Candidatus Midichloria and pathogens belonging to Rickettsia. Finally, more specific network analyses were performed on TBP-infected samples and suggested that the presence of pathogens belonging to the genera Borrelia, Anaplasma and Rickettsia may disrupt microbial interactions in I. ricinus. CONCLUSIONS: We identified the I. ricinus microbiota and documented marked shifts in tick microbiota dynamics over time. Statistically, we showed strong relationships between the presence of specific pathogens and the structure of the I. ricinus microbiota. We detected close links between some tick symbionts and the potential presence of either pathogenic Rickettsia or a parasitoid in ticks. These new findings pave the way for the development of new strategies for the control of ticks and tick-borne diseases. Video abstract.
Asunto(s)
Borrelia , Ixodes , Microbiota , Rickettsia , Animales , Humanos , Interacciones Microbianas , Microbiota/genética , Rickettsia/genéticaRESUMEN
High-throughput sequencing technologies now allow for rapid cost-effective surveys of multiple pathogens in many host species including rodents, but it is currently unclear if the organ chosen for screening influences the number and identity of bacteria detected. We used 16S rRNA amplicon sequencing to identify bacterial pathogens in the heart, liver, lungs, kidneys and spleen of 13 water voles (Arvicola terrestris) collected in Franche-Comté, France. We asked if bacterial pathogen assemblages within organs are similar and if all five organs are necessary to detect all of the bacteria present in an individual animal. We identified 24 bacteria representing 17 genera; average bacterial richness for each organ ranged from 1·5 ± 0·4 (mean ± standard error) to 2·5 ± 0·4 bacteria/organ and did not differ significantly between organs. The average bacterial richness when organ assemblages were pooled within animals was 4·7 ± 0·6 bacteria/animal; Operational Taxonomic Unit accumulation analysis indicates that all five organs are required to obtain this. Organ type influences bacterial assemblage composition in a systematic way (PERMANOVA, 999 permutations, pseudo-F 4,51 = 1·37, P = 0·001). Our results demonstrate that the number of organs sampled influences the ability to detect bacterial pathogens, which can inform sampling decisions in public health and wildlife ecology.
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Arvicolinae , Bacterias/clasificación , Microbiota/fisiología , Enfermedades de los Roedores/epidemiología , Animales , Bacterias/genética , ADN Bacteriano/genética , Francia/epidemiología , Prevalencia , ARN Ribosómico 16S/genética , Enfermedades de los Roedores/microbiología , Análisis de Secuencia de ADN/veterinaria , Distribución TisularRESUMEN
The present study examined the lipid composition of plasma membranes in carp sperm with different post-thaw motility. The approach adapted for carp sperm cryopreservation, which involves the selection of the most effective protocol for individual males by comparing two cryoprotective media, was applied to the cryopreservation procedure. Sperm motility prior to freezing was greater than 80% but decreased to 40% in one group and to 10% in another group following cryopreservation. Lipid content of fresh sperm in all groups was analysed by thin layer chromatography and gas chromatography, with significant differences in phospholipid content, cholesterol and free fatty acids detected between groups, whereas the cholesterol/phospholipid ratio was extremely similar between groups (0.52 ± 0.038 and 0.52 ± 0.022). Increasing concentrations of saturated fatty acids, monounsaturated acids and decreasing concentrations of polyunsaturated n-6 fatty acids were negatively correlated (P < 0.05) with post-thaw motility of the carp sperm.
Asunto(s)
Crioprotectores/farmacología , Preservación de Semen/métodos , Motilidad Espermática/fisiología , Espermatozoides/química , Animales , Carpas , Membrana Celular/metabolismo , Colesterol/metabolismo , Cromatografía de Gases , Cromatografía en Capa Delgada , Criopreservación/métodos , Ácidos Grasos/metabolismo , Congelación , Masculino , Fosfolípidos/metabolismo , Motilidad Espermática/efectos de los fármacos , Espermatozoides/metabolismoRESUMEN
The paper reviews the significance of rats of the genus Rattus as hosts for zoogenous infections in a genus formation area (Southeast Asia) as compared to the invasion part of the genus area. The rats of the genus Rattus and their related disease agents are shown to be a uniqe model for the formation and development of a host-pathogen system. In the modern period of urbanization growth, the rats are among few species of warm-blooded vectors that can maintain the anthropurgic foci of feral nidal infections in the cities and towns and transmit their pathogens to the urban population. There are all prerequisites for the high activity of these foci in the native area of rats. By having settled, the rats have carried infectious agents outside this area along all continents in historical times. During invasions, the rats have become carriers of many other infections.
Asunto(s)
Infecciones Bacterianas/epidemiología , Reservorios de Enfermedades/veterinaria , Virosis/epidemiología , Zoonosis/epidemiología , Migración Animal/fisiología , Animales , Asia Sudoriental/epidemiología , Infecciones Bacterianas/microbiología , Ciudades , Reservorios de Enfermedades/microbiología , Reservorios de Enfermedades/virología , Interacciones Huésped-Patógeno , Humanos , Ratas , Federación de Rusia/epidemiología , Población Urbana , Virosis/virología , Zoonosis/microbiología , Zoonosis/virologíaRESUMEN
Leptospirosis incidence has increased markedly since 1995 in Thailand, with the eastern and northern parts being the most affected regions, particularly during flooding events. Here, we attempt to overview the evolution of human prevalence during the past decade and identify the environmental factors that correlate with the incidence of leptospirosis and the clinical incidence in humans. We used an extensive survey of Leptospira infection in rodents conducted in 2008 and 2009 and the human incidence of the disease from 2003 to 2012 in 168 villages of two districts of Nan province in Northern Thailand. Using an ad-hoc developed land-use cover implemented in a geographical information system we showed that humans and rodents were not infected in the same environment/habitat in the land-use cover. High village prevalence was observed in open habitat near rivers for the whole decade, or in 2008-2009 mostly in rice fields prone to flooding, whereas infected rodents (2008-2009) were observed in patchy habitat with high forest cover, mostly situated on sloping ground areas. We also investigated the potential effects of public health campaigns conducted after the dramatic flood event of 2006. We showed that, before 2006, human incidence in villages was explained by the population size of the village according to the environmental source of infection of this disease, while as a result of the campaigns, human incidence in villages after 2006 appeared independent of their population size. This study confirms the role of the environment and particularly land use, in the transmission of bacteria, emphasized by the effects of the provincial public health campaigns on the epidemiological pattern of incidence, and questions the role of rodents as reservoirs.
Asunto(s)
Política de Salud , Leptospira/aislamiento & purificación , Leptospirosis/epidemiología , Murinae , Enfermedades de los Roedores/epidemiología , Animales , Inundaciones , Genes Bacterianos , Sistemas de Información Geográfica , Humanos , Incidencia , Leptospira/clasificación , Leptospira/genética , Leptospirosis/microbiología , Leptospirosis/veterinaria , Prevalencia , Factores de Riesgo , Enfermedades de los Roedores/microbiología , Análisis de Secuencia de ADN , Tailandia/epidemiologíaRESUMEN
Sturgeon spermatozoa maturation during their passage through the kidney is a prerequisite for initiation of motility. Samples of sterlet () testicular sperm (TS) were matured in vitro by incubation in seminal fluid (SF) or in SF supplemented with carbonyl cyanide -chlorophenyl hydrazone (CCCP; a respiration uncoupling agent). Sperm was diluted in activation medium (AM) containing 10 m Tris-HCl buffer (pH 8.5) and 0.25% Pluronic, and spermatozoon motility was assessed. Samples were taken and fixed in 3 perchloric acid at 3 points in the incubation process. Quantification of ATP, ADP, and creatine phosphate (CrP) was conducted using liquid chromatography/high-resolution mass spectrometry. We observed a significant decrease in CrP during artificial maturation of TS in SF. In contrast, ATP and ADP were not significantly affected. Addition of CCCP to SF halted maturation and led to significantly lower CrP whereas ADP significantly increased and ATP was unaffected. Dilution of matured and immature TS with AM led to a significant decrease of ATP and CrP and an increase of ADP compared with their levels before dilution, although immature TS were not motile. Energy dependency of TS maturation in sturgeon was confirmed, which suggests that mitochondrial oxidative phosphorylation is needed for maturation of sturgeon TS.
Asunto(s)
Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Peces/fisiología , Fosfocreatina/metabolismo , Maduración Sexual/fisiología , Espermatozoides/metabolismo , Animales , Carbonil Cianuro m-Clorofenil Hidrazona/farmacología , Masculino , Fosforilación Oxidativa , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Desacopladores/farmacologíaRESUMEN
We review the phylogeny, sperm competition, morphology, physiology, and fertilization environments of the sperm of externally fertilizing fish and amphibians. Increased sperm competition in both fish and anurans generally increases sperm numbers, sperm length, and energy reserves. The difference between the internal osmolarity and iconicity of sperm cells and those of the aquatic medium control the activation, longevity, and velocity of sperm motility. Hypo-osmolarity of the aquatic medium activates the motility of freshwater fish and amphibian sperm and hyperosmolarity activates the motility of marine fish sperm. The average longevity of the motility of marine fish sperm (~550 seconds) was significantly (P < 0.05) greater than that of freshwater fish sperm (~150 seconds), with the longevities of both marine and freshwater fish being significantly (P < 0.05) lower than that of anuran sperm (~4100 seconds). The average velocity of anuran sperm (25 µm/s) was significantly (P < 0.05) lower than that of marine fish (140 µm/s) or freshwater fish (135 µm/s) sperm. The longevity of the sperm of giant salamanders (Cryptobranchoidea) of approximately 600 seconds was greater than that of freshwater fish sperm but much lower than anuran sperm. Our research and information from the literature showed that higher osmolarities promote greater longevity in anuran sperm, and some freshwater fish sperm, and that anuran and cryptobranchid sperm maintained membrane integrity long after the cessation of motility, demonstrating a preferential sharing of energy reserves toward the maintenance of membrane integrity. The maintenance of the membrane integrity of anuran sperm in fresh water for up to 6 hours showed an extremely high osmotic tolerance relative to fish sperm. The very high longevity and osmotic tolerance of anuran sperm and high longevity of cryptobranchid sperm, relative to those of freshwater fish, may reflect the complex fertilization history of amphibian sperm in general and anurans reversion from internal to external fertilization. Our findings provide a greater understanding of the reproductive biology of externally fertilizing fish and amphibians, and a biological foundation for the further development of reproduction technologies for their sustainable management.
Asunto(s)
Anfibios/fisiología , Fertilización/fisiología , Peces/fisiología , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Animales , MasculinoRESUMEN
The protective influence of seminal plasma and the antioxidants catalase (CAT), superoxide dismutase (SOD), and glutathione (GTH) on quality parameters, oxidative stress indices, and antioxidant activity was studied in common carp (Cyprinus carpio) spermatozoa exposed to the xanthine-xanthine oxidase (X-XO) system. Fish spermatozoa were incubated for 5 and 20 min at 4 °C with X-XO concentrations of 1 mM X-0.1 U/mL, 0.6 mM X-0.05 U/mL, 0.3 mM X-0.025 U/mL, and 0.1 mM X-0.0125 U/mL. A dose-dependent reduction in spermatozoa motility and velocity was observed at concentrations of 0.1 mM X-0.0125 U/mL to 1 mM X-0.1 U/mL XO. Increase in spermatozoa motility parameters was recorded following treatment with antioxidants and seminal plasma. The level of the oxidative stress indices lipid peroxidation (LPO) and carbonyl derivatives of proteins (CP) was significantly reduced after addition of CAT, SOD, or GTH along with seminal plasma. Significant differences in SOD, glutathione reductase, and glutathione peroxidase activity were seen in spermatozoa incubated with, compared to that without, seminal plasma at all studied X-XO concentrations. The data demonstrated that CAT, SOD, or GTH in combination with SP can reduce reactive oxygen species stress in fish spermatozoa and improve spermatozoa quality.
Asunto(s)
Antioxidantes/metabolismo , Carpas/fisiología , Estrés Oxidativo/fisiología , Semen/fisiología , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Animales , Glutatión Reductasa , Masculino , Xantina/metabolismo , Xantina Oxidasa/metabolismoRESUMEN
The role of environmental ion composition and osmolality in calcium ion (Ca(2+) ) signalling of spermatozoa activation over the course of the spawning period of brook trout Salvelinus fontinalis was investigated. Motility at the end of spawning was low (mean ± s.d. of 5 ± 2% motile spermatozoa with curvilinear velocity of 25 ± 8 µm s(-1) ). Addition of 10 mM Ca(2+) to the activation medium resulted in values similar to those recorded during the middle of the spawning period (mean ± s.d. of 95 ± 6% motile spermatozoa with curvilinear velocity of 130 ± 15 µm s(-1) ).
Asunto(s)
Calcio/metabolismo , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Trucha/fisiología , Animales , Suplementos Dietéticos , Masculino , Estaciones del AñoRESUMEN
Sturgeon spermatozoa are immotile in the testis and acquire the potential for motility after contact with urine in Wolffian duct. The present study tested if in vitro incubation of testicular sperm in seminal fluid from Wolffian duct sperm leads to the acquisition of sperm fertilization ability. Sterlet sperm was taken from the testes, matured in vitro and cryopreserved. The fertility and motility of cryopreserved semen were tested. Matured testicular sperm showed freeze-thaw survival rates similar to Wolffian duct sperm, which is commonly used in sturgeon artificial propagation. Matured testicular sperm and Wolffian duct sperm post-thaw motility rate and curvilinear velocity were not significantly different, while duration of matured testicular sperm motility was significantly shorter than that of Wolffian duct sperm. Development rates of embryos obtained with post-thaw matured testicular sperm and Wolffian duct sperm were not significantly different. In vitro maturation of sterlet testicular sperm can potentially be useful in sperm cryobanking.
Asunto(s)
Criopreservación/veterinaria , Peces/fisiología , Preservación de Semen/veterinaria , Espermatozoides/citología , Animales , Criopreservación/métodos , Femenino , Fertilización In Vitro , Masculino , Preservación de Semen/métodos , Motilidad Espermática , Testículo/citología , Conductos Mesonéfricos/citologíaRESUMEN
Heterogeneity in environmental conditions helps to maintain genetic and phenotypic diversity in ecosystems. As such, it may explain why the capacity of animals to mount immune responses is highly variable. The quality of habitat patches, in terms of resources, parasitism, predation and habitat fragmentation may, for example, trigger trade-offs ultimately affecting the investment of individuals in various immunological pathways. We described spatial immunoheterogeneity in bank vole populations with respect to landscape features and co-infection. We focused on the consequences of this heterogeneity for the risk of Puumala hantavirus (PUUV) infection. We assessed the expression of the Tnf-α and Mx2 genes and demonstrated a negative correlation between PUUV load and the expression of these immune genes in bank voles. Habitat heterogeneity was partly associated with differences in the expression of these genes. Levels of Mx2 were lower in large forests than in fragmented forests, possibly due to differences in parasite communities. We previously highlighted the positive association between infection with Heligmosomum mixtum and infection with PUUV. We found that Tnf-α was more strongly expressed in voles infected with PUUV than in uninfected voles or in voles co-infected with the nematode H. mixtum and PUUV. H. mixtum may limit the capacity of the vole to develop proinflammatory responses. This effect may increase the risk of PUUV infection and replication in host cells. Overall, our results suggest that close interactions between landscape features, co-infection and immune gene expression may shape PUUV epidemiology.
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Arvicolinae/inmunología , Arvicolinae/parasitología , Arvicolinae/virología , Virus Puumala/patogenicidad , Enfermedades de los Roedores/epidemiología , Animales , Arvicolinae/genética , Coinfección , Ecosistema , Femenino , Francia , Regulación de la Expresión Génica , Fiebre Hemorrágica con Síndrome Renal/epidemiología , Fiebre Hemorrágica con Síndrome Renal/veterinaria , Interacciones Huésped-Patógeno , Masculino , Proteínas de Resistencia a Mixovirus/genética , Infecciones por Nematodos/veterinaria , Enfermedades de los Roedores/parasitología , Enfermedades de los Roedores/virología , Árboles , Factor de Necrosis Tumoral alfa/genética , Carga Viral/genética , Replicación ViralRESUMEN
Here we report for the first time the possibility of sequential sperm motility activation in sturgeon (sterlet, Acipenser ruthenus), a fish with external fertilization, through changes either in osmolality (global solute concentration) or in the Ca(2+) concentration of the medium surrounding the spermatozoa. Sperm motility was initiated in any of three solutions containing buffer and sucrose at 80, or 40 or 10mM (called S80, S40, S10, respectively); S80 is hypertonic relative to sterlet seminal fluid, while S40 is isotonic and S10 is hypotonic. After cessation of sperm movement at the end of this first motility period, a second and then a third, subsequent motile phase were observed. The second motility period was induced at cessation of motility in S80 by imposing a two-fold decrease in osmolality. After arrest of motility in this half-diluted S80, a third motility period could be initiated by addition of CaCl2 to 1mM final concentration. At the end of a first motility period in either S40 or S10, subsequent motility re-activation episodes were achieved only by addition of 1mM CaCl2. Depending on conditions in which sperm samples were activated, significant differences in curvilinear velocity, percent motile spermatozoa, motility duration time, and specific external features of spermatozoa flagella were observed. Altogether, these observations on the ability of sturgeon spermatozoa to sustain sequential activation episodes by experimental adjustment of their environmental conditions represent a potent model for deeper investigations on the sperm motility activation mechanisms.
Asunto(s)
Peces/fisiología , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Animales , Calcio/farmacología , Ácido Egtácico/farmacología , Masculino , Concentración Osmolar , Semen/química , Semen/metabolismo , Capacitación Espermática/efectos de los fármacos , Capacitación Espermática/fisiología , Motilidad Espermática/efectos de los fármacos , Espermatozoides/efectos de los fármacosRESUMEN
Spermatozoa tend to swim near surfaces. Such attraction toward surface vicinity was approximated by the force-dipole theoretical approach and hydrodynamic modeling, but the physical parameters of surfaces have not usually been included in these models and their effect on sperm mobility remains unknown. In spermatozoa, changes in wave parameters, together with rotation around their longitudinal axis and circling appear when movement takes place close to surfaces. Here we show, by analysis of microscopy images (including high-speed video), a strong influence of the liquid-solid interface on sterlet spermatozoa motility characteristics compared with motility near the liquid-gas interface. Sperm cells swam at 16% lower velocity near a liquid-solid interface, rotating at a stable frequency of 25 Hz, each 180° rotation corresponding to one beat cycle and circling clockwise (when observed from top). In case of spermatozoa close to a water-air interface, rotation and circling were sporadic and irregular. Sterlet spermatozoa movement near a surface affects their velocity and possibly causes rotation. These behaviors are highly dependent on the level of suppleness of the interface, as has been previously predicted by modeling. Our results enhance the understanding of how surfaces influence fish spermatozoa motility. These insights on the effects of surfaces on fish spermatozoa motility imply that widely used methods rating sperm motility, such as computer-assisted sperm analysis, might lead to erroneous results. Further study of sperm motility near surfaces is urgently needed to correct our rating methods and better understand sperm behavior in natural conditions. Improved evaluation of sperm motility behavior near surfaces could be used to determine physical properties of aquatic interfaces with various surfaces composed of different materials.
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Peces/fisiología , Motilidad Espermática/fisiología , Animales , Ambiente , Masculino , Modelos Biológicos , Movimiento/fisiología , Rotación , Análisis de Semen/veterinaria , Cola del Espermatozoide/fisiología , Espermatozoides/fisiología , Propiedades de Superficie , NataciónRESUMEN
Rodent control is an important issue in human health and agriculture. Oil palm plantations are rapidly expanding in Indonesia and this is having a major economic and ecological impact. Rodent control in oil palm plantations is based principally on the use of anti-vitamin K (AVK), the main anticoagulant used being coumatetralyl, a first-generation AVK. We conducted a comparative study in two well established oil palm plantations in Indonesia: (1) one without chemical control in Riau and (2) another with intensive coumatetralyl use on Bangka Island. Rat species were identified by the molecular barcoding method. Susceptibility to coumatetralyl was then assessed within the two populations and we screened for mutations in vkorc1, which encodes the molecular target of AVK. Different species were found in the two areas: Rattus tiomanicus in Riau, and a mix of R. tanezumi and a close relative one in Bangka. The rats in Riau were much more susceptible to coumatetralyl than those in Bangka. This study is the first to demonstrate physiological tolerance to AVK in these species. vkorc1 displayed low levels of polymorphism, and no SNP was associated with the high-tolerance phenotypes of R. tanezumi clade, even those exposed to very high concentrations (32 × the effective dose of 0.36 mg kg(-1)). The biochemical basis of this tolerance remains unknown, but may involve the vkorc1 promoter and/or cytochrome P450 metabolism. We discuss our results and the selective role of anticoagulant use in the occurrence of phenotypic tolerance.
Asunto(s)
4-Hidroxicumarinas/farmacología , Agricultura , Arecaceae , Resistencia a Medicamentos , Aceites de Plantas , Control de Roedores/métodos , Rodenticidas/farmacología , Árboles , Animales , Arecaceae/química , Código de Barras del ADN Taxonómico , Análisis Mutacional de ADN , Resistencia a Medicamentos/genética , Genotipo , Indonesia , Oxigenasas de Función Mixta/genética , Mutación , Aceite de Palma , Fenotipo , Aceites de Plantas/aislamiento & purificación , Polimorfismo Genético , Ratas , Árboles/química , Vitamina K Epóxido ReductasasRESUMEN
Osteoradionecrosis of the jaws is a complication of radiotherapy and controversy remains about the management of teeth in the field of radiotherapy. Platelet rich plasma has been advocated in multiple surgical sites, both bone and soft tissue, to promote healing and reduce complications. A randomized double blinded controlled trial was performed on patients receiving bilateral radiotherapy that affected the mandible who required pre treatment dental extractions. One side received platelet rich plasma and the other acted as a control. Twenty-two patients were recruited over 12 months and over a 5-year period following treatment three developed osteoradionecrosis (14%). Platelet rich plasma failed to show any benefit in the prevention of osteoradionecrosis. Nor was there any benefit in pain scores or mucosal healing on sides that were treated with platelet rich plasma. Platelet rich plasma fails to show a benefit in the prevention of osteoradionecrosis. The rate of osteoradionecrosis is high compared to other published series and the prophylactic removal of molar teeth should be questioned as a preventative measure.
Asunto(s)
Enfermedades Mandibulares/prevención & control , Osteorradionecrosis/prevención & control , Plasma Rico en Plaquetas/fisiología , Adulto , Anciano , Alveoloplastia/métodos , Estudios Cruzados , Método Doble Ciego , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Laríngeas/radioterapia , Masculino , Mandíbula/patología , Mandíbula/efectos de la radiación , Persona de Mediana Edad , Dimensión del Dolor , Dolor Postoperatorio/etiología , Neoplasias Faríngeas/radioterapia , Dosificación Radioterapéutica , Extracción Dental , Alveolo Dental/patología , Alveolo Dental/efectos de la radiaciónRESUMEN
Motility of Pinctada margaritifera (Linnaeus, 1758); var: cumingii (Jameson, 1901) (P. margaritifera) spermatozoa collected from gonads are not immediately activated at spawning in seawater (SW) but motility occurs when spermatozoa are transferred into alkaline seawater (pH ranging from 9.0 to 11.4). This motility-activating effect of alkaline pH is reversed when pH is shifted back to more acidic values. In both cases, activity of sperm (% motile cells) increases gradually after alkaline pH activation then lasts for several minutes. The characteristics of these fully motile spermatozoa are described in details at the level of flagella: the wave amplitude and wave-length range 5 to 6 µm and 15 µm respectively, while the flagellar beat frequency is approximately 49 Hz. The velocity of sperm displacement is from 220 to 230 µm/sec. The general swimming pattern is almost circular: the head trajectories describe portions of circles intercalated with small linear segments. Spermatozoa saved in natural seawater at 4°C retain potent motility for several days and can be subsequently activated by alkaline seawater. Respiration and ATP concentration were measured in 3 conditions: regular seawater (pH 7.8), artificial diluent (pH 8.2), and alkaline Tris-buffered seawater (pH 10.5). Results show that sperm respiration rates are higher whereas ATP levels are lower in the latter two media.
Asunto(s)
Pinctada/fisiología , Motilidad Espermática , Espermatozoides/fisiología , Adenosina Trifosfato/metabolismo , Animales , Concentración de Iones de Hidrógeno , Masculino , Agua de Mar/química , Espermatozoides/metabolismoRESUMEN
Rodent host dynamics and dispersal are thought to be critical for hantavirus epidemiology as they determine pathogen persistence and transmission within and between host populations. We used landscape genetics to investigate how the population dynamics of the bank vole Myodes glareolus, the host of Puumala hantavirus (PUUV), vary with forest fragmentation and influence PUUV epidemiology. We sampled vole populations within the Ardennes, a French PUUV endemic area. We inferred demographic features such as population size, isolation and migration with regard to landscape configuration. We next analysed the influence of M. glareolus population dynamics on PUUV spatial distribution. Our results revealed that the global metapopulation dynamics of bank voles were strongly shaped by landscape features, including suitable patch size and connectivity. Large effective size in forest might therefore contribute to the higher observed levels of PUUV prevalence. By contrast, populations from hedge networks highly suffered from genetic drift and appeared strongly isolated from all other populations. This might result in high probabilities of local extinction for both M. glareolus and PUUV. Besides, we detected signatures of asymmetric bank vole migration from forests to hedges. These movements were likely to sustain PUUV in fragmented landscapes. In conclusion, our study provided arguments in favour of source-sink dynamics shaping PUUV persistence and spread in heterogeneous, Western European temperate landscapes. It illustrated the potential contribution of landscape genetics to the understanding of the epidemiological processes occurring at this local scale.
Asunto(s)
Arvicolinae/genética , Arvicolinae/virología , Fiebre Hemorrágica con Síndrome Renal/epidemiología , Virus Puumala/patogenicidad , Animales , Teorema de Bayes , Análisis por Conglomerados , ADN/aislamiento & purificación , Ecosistema , Francia/epidemiología , Flujo Genético , Fiebre Hemorrágica con Síndrome Renal/transmisión , Fiebre Hemorrágica con Síndrome Renal/veterinaria , Densidad de Población , Dinámica Poblacional , Prevalencia , ÁrbolesRESUMEN
In most species, fish spermatozoa activate their motility on contact with the external medium (sea or fresh water depending of their reproductive habitat). Their flagella immediately develop waves propagated at high beat frequency (up to 70 beats s(-1)), which propel these sperm cells at high velocity (6-10 mm min(-1)), but for a quite short period of time, usually limited to minutes. Their specific inability to restore their energy content (mostly adenosine triphosphate) fast enough relatively to their high rate of energy consumption by flagellar contributes mainly to the activity arrest of motility, as the spermatozoa need to rely on early accumulated energy prior to activation. This review of the published data explains the present understanding of physico-chemical mechanisms by which flagellar motility is activated (mostly through osmotic and ionic regulation) and then propels sperm cells at speed. It aims also to describe the gradual arrest of their motility much of which occurs within a few minutes.
Asunto(s)
Peces/fisiología , Flagelos/fisiología , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Animales , Iones/farmacología , Masculino , Concentración Osmolar , Motilidad Espermática/efectos de los fármacosRESUMEN
Dispersal is a fundamental process in ecology because it influences the dynamics, genetic structure and persistence of populations. Furthermore, understanding the evolutionary causes of dispersal pattern, particularly when they differ between genders, is still a major question in evolutionary ecology. Using a panel of 10 microsatellite loci, we investigated at different spatial scales the genetic structure and the sex-specific dispersal patterns in the common vole Microtus arvalis, a small colonial mammal. This study was conducted in an intensive agricultural area of western France. Hierarchical F(ST) analyses, relatedness and assignment tests suggested (i) that females are strongly kin-clustered within colonies; (ii) that dispersal is strongly male-biased at a local scale; and (iii) long-distance dispersal is not rare and more balanced between genders. We conclude that males migrate continuously from colony to colony to reproduce, whereas females may disperse just once and would be mainly involved in new colony foundation.
Asunto(s)
Arvicolinae/fisiología , Demografía , Caracteres Sexuales , Envejecimiento , Animales , Arvicolinae/genética , Femenino , Francia , Masculino , Conducta SocialRESUMEN
Trichuris arvicolae and T. muris are gastro-intestinal nematodes of respectively arvicoline and murine rodents. We aim to investigate the ecology of these Trichuris species using population genetics. We sampled nematodes from rodents trapped in the East of France. After confirming the species identification of the nematodes using ITS1-5.8S-ITS2 ribosomal DNA sequences, we isolated and characterized twelve dinucleotide microsatellite loci in T. arvicolae. A multiplex panel was developed. Application to a set of 30 individuals allowed clear and easy characterization of allele sizes. The number of alleles ranged from 2 to 6 per locus with observed heterozygosities ranging from 0 to 0.93. A test on eleven T. muris revealed that eight loci among twelve amplified, and five were polymorphic. These sets of microsatellite loci provide high throughput capacity for population genetic studies.