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1.
Many monophagous animals have coevolutionary relationships with bacteria that provide unavailable nutrients to the host. Frequently, these microbial partners are vertically inherited and reside in specialized structures or tissues. Here we report three new lineages of bacterial symbionts of blood-feeding leeches, one from the giant Amazonian leech, Haementeria ghilianii, and two others from Placobdelloides species. These hosts each possess a different mycetome or esophageal organ morphology where the bacterial cells are located. DNA sequencing of the bacterial 16S rRNA genes and fluorescent in situ hybridization placed these symbionts in two separate clades in the class Gammaproteobacteria. We also conducted a broad phylogenetic analysis of the herein-reported DNA sequences as well as others from bacterial symbionts reported elsewhere in the literature, including alphaproteobacterial symbionts from the leech genus Placobdella as well as Aeromonas veronii from the medicinal leech, Hirudo medicinalis, and a Rickettsia sp. detected in Hemiclepsis marginata. Combined, these results indicate that blood-feeding leeches have forged bacterial partnerships at least five times during their evolutionary history.  相似文献   

2.
Although several commensal alphaproteobacteria form close relationships with plant hosts where they aid in (e.g.,) nitrogen fixation and nodulation, only a few inhabit animal hosts. Among these, Reichenowia picta, R. ornata and R. parasitica, are currently the only known mutualistic, alphaproteobacterial endosymbionts to inhabit leeches. These bacteria are harbored in the epithelial cells of the mycetomal structures of their freshwater leech hosts, Placobdella spp., and these structures have no other obvious function than housing bacterial symbionts. However, the function of the bacterial symbionts has remained unclear. Here, we focused both on exploring the genomic makeup of R. parasitica and on performing a robust phylogenetic analysis, based on more data than previous hypotheses, to test its position among related bacteria. We sequenced a combined pool of host and symbiont DNA from 36 pairs of mycetomes and performed an in silico separation of the different DNA pools through subtractive scaffolding. The bacterial contigs were compared to 50 annotated bacterial genomes and the genome of the freshwater leech Helobdella robusta using a BLASTn protocol. Further, amino acid sequences inferred from the contigs were used as queries against the 50 bacterial genomes to establish orthology. A total of 358 orthologous genes were used for the phylogenetic analyses. In part, results suggest that R. parasitica possesses genes coding for proteins related to nitrogen fixation, iron/vitamin B translocation and plasmid survival. Our results also indicate that R. parasitica interacts with its host in part by transmembrane signaling and that several of its genes show orthology across Rhizobiaceae. The phylogenetic analyses support the nesting of R. parasitica within the Rhizobiaceae, as sister to a group containing Agrobacterium and Rhizobium species.  相似文献   

3.
We characterized the intracellular symbiotic bacteria of the hematophagous glossiphoniid leeches Placobdelloides siamensis and a Parabdella sp. These leeches have a specialized structure called an "esophageal organ," the cells of which harbor bacterial symbionts. From the esophageal organ of each species, a 1.5-kb eubacterial 16S rRNA gene segment was amplified by PCR, cloned, and sequenced. Diagnostic PCR detected the symbiont in the esophageal organ and intestine. Phylogenetic analysis of the 16S rRNA gene(s) demonstrated that the symbionts from the leeches formed a monophyletic group in a well-defined clade containing endosymbiotic bacteria of plant sap-feeding insects in the gamma-subdivision of the Proteobacteria.The nucleotide compositions of the 16S rRNA gene from the leech symbionts were highly AT biased (53.7%).  相似文献   

4.
We characterized the intracellular symbiotic bacteria of the hematophagous glossiphoniid leeches Placobdelloides siamensis and a Parabdella sp. These leeches have a specialized structure called an “esophageal organ,” the cells of which harbor bacterial symbionts. From the esophageal organ of each species, a 1.5-kb eubacterial 16S rRNA gene segment was amplified by PCR, cloned, and sequenced. Diagnostic PCR detected the symbiont in the esophageal organ and intestine. Phylogenetic analysis of the 16S rRNA gene(s) demonstrated that the symbionts from the leeches formed a monophyletic group in a well-defined clade containing endosymbiotic bacteria of plant sap-feeding insects in the γ-subdivision of the Proteobacteria. The nucleotide compositions of the 16S rRNA gene from the leech symbionts were highly AT biased (53.7%).  相似文献   

5.
Intracellular rickettsia-like structures were found in the tissues of a glossiphoniid leech, Torix tagoi, by transmission electron microscopy. Diagnostic PCR analysis using specific primers suggested that of the nine glossiphoniid species examined, two species, T. tagoi and Hemicrepsis marginata, harbored bacteria of the genus Rickettsia. A 1.5-kb eubacterial 16S rRNA gene segment obtained from each of these species was amplified by PCR, cloned, and sequenced. Phylogenetic analysis of the 16S rRNA gene demonstrated that the Rickettsia species found in the leeches constituted a novel clade that is distinct from the clade of arthropod-associated Rickettsia species. In natural populations, 97.7% (43 of 44) of T. tagoi leeches and 100% (9 of 9) of H. marginata leeches carried Rickettsia, suggesting that infection with Rickettsia is prevalent in these leeches. This is the first report of Rickettsia found in annelids.  相似文献   

6.
Widespread mouth ulcerations were observed in largemouth bass collected from eight inland lakes in the Lower Peninsula of Michigan during the summer months of 2002 and 2003. These ulcerations were associated with, and most likely caused by, leech parasitism. Through the use of morphological dichotomous keys, it was determined that all leeches collected are of one species: Myzobdella lugubris. Among the eight lakes examined, Lake Orion and Devils Lake had the highest prevalence of leech parasitism (34% and 29%, respectively) and mouth ulcerations (53% and 68%, respectively). Statistical analyses demonstrated that leech and ulcer prevalence varied significantly from one lake to the other. Additionally, it was determined that the relationship between the prevalence of ulcers and the prevalence of leech attachment is significant, indicating that leech parasitism is most likely the cause of ulceration. The ulcers exhibited deep hemorrhagic centers and raised irregular edges. Affected areas lost their epithelial lining and submucosa, with masses of bacteria colonizing the damaged tissues. Since largemouth bass is a popular global sportfish and critical to the food web of inland lakes, there are concerns that the presence of leeches, damaged buccal mucosa, and general unsightliness may negatively affect this important sportfishery.  相似文献   

7.
Leeches and their microbiota: naturally simple symbiosis models   总被引:1,自引:0,他引:1  
Strictly blood-feeding leeches and their limited microbiota provide natural and powerful model systems to examine symbiosis. Blood is devoid of essential nutrients and it is thought that symbiotic bacteria synthesize these for the host. In this review, three distinct leech-microbe associations are described: (i) the mycetome, which is the large symbiont-containing organ associated with the esophagus; (ii) the nephridia and bladders that form the excretory system; and (iii) the digestive tract, where two bacterial species dominate the microbiota. The current knowledge and features of leech biology that promote the investigation of interspecific interactions (host-microbe and microbe-microbe) and their evolution are highlighted.  相似文献   

8.

Blood-feeding leeches of the genus Placobdella have acquired intracellular alphaproteobacterial endosymbionts of the genus Reichenowia that potentially aid in the production of B vitamins, thereby ameliorating the lack of these essential nutrients in the diet of the hosts. For Placobdella associates, little is still known about the diversity, genetic makeup, and the mode of transmission of bacteria between leeches. We aimed to (i) place the bacterial symbionts in a phylogenetic context, (ii) compare patterns of cladogenesis between the bacteria and hosts to search for evidence of co-speciation, and (iii) explore the mode of bacterial transmission between leech parent and offspring. DNA sequencing of the bacterial 16S rDNA and 23S rDNA loci suggests that, whereas Reichenowia forms a monophyletic group within the alphaproteobacterial family Rhizobiaceae, no evidence for co-speciation between hosts and bacteria can be traced. Attempts at DNA amplification for ovarial tissues were negative for a range of species, but two 16S rDNA sequences retrieved from the testisacs of P. rugosa showed very high similarity with Reichenowia. Although we cannot rule out that this may be a contamination, or a different, potentially free-living species of bacteria, our results may indicate that Reichenowia is transferred from leech parent to offspring via the testisacs.

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9.
The seasonal occurrence of medicinal leeches was studied at two lakes in the Black Sea coastland of north-western Turkey. The number of leeches attracted by a collector per hour was taken as an indicator for population density. Leeches were most abundant in May/June, and were almost absent during the cold season (November – March). Leeches with a weight of less than 1 g occurred principally between July and October with a peak in July. It is thought that these individuals represent newly hatched leeches. Although both study areas are close to each other, significant differences were found in respect to mean leech size and the seasonal frequency of leeches (both total number and certain age classes). It is suggested that leech biology is greatly dependent on factors such as microclimate and the availability of hosts, and no general conclusions on phenology can be drawn. There is therefore no scientific basis for restricting commercial leech collecting to certain months of the year.  相似文献   

10.
There are 60 species of blood-feeding land leeches, 50 species belonging to the family Haemadipsidae and 10 species belonging to the family Xerobdellidae. Despite recent papers on the land leeches, their taxonomic identification is not fully understood, especially at a species level. In Korea, there have been no historical records of the terrestrial leeches, but recently an unrecorded blood-feeding land leech was discovered at Gageo-do (Island), Korea. Molecular analysis was used to identify the species of 29 leeches collected from Mt. Dock-Sil in Gageo-do. Conventional PCR was conducted using nuclear 18S rRNA and mitochondrial cytochrome c oxidase subunit 1 (CO1) genetic marker. The 18S rRNA sequences revealed that the leeches share 99.9% identity with Haemadipsa rjukjuana (inhabiting Taiwan), and the CO1 sequences revealed that the leeches are very close to H. rjukjuana (inhabiting Taiwan). The CO1 sequences were separated into 2 categories, 1 with 94.6% and the other with 94.3% similarity to the H. rjukjuana L00115A (inhabiting Taiwan). This new finding of the land leech is the first record in Korea. In addition, the north range of the distribution of the blood-feeding leech (Hirudiniformes: Haemadipisidae) should be reconsidered including Korea.  相似文献   

11.
Intracellular rickettsia-like structures were found in the tissues of a glossiphoniid leech, Torix tagoi, by transmission electron microscopy. Diagnostic PCR analysis using specific primers suggested that of the nine glossiphoniid species examined, two species, T. tagoi and Hemicrepsis marginata, harbored bacteria of the genus Rickettsia. A 1.5-kb eubacterial 16S rRNA gene segment obtained from each of these species was amplified by PCR, cloned, and sequenced. Phylogenetic analysis of the 16S rRNA gene demonstrated that the Rickettsia species found in the leeches constituted a novel clade that is distinct from the clade of arthropod-associated Rickettsia species. In natural populations, 97.7% (43 of 44) of T. tagoi leeches and 100% (9 of 9) of H. marginata leeches carried Rickettsia, suggesting that infection with Rickettsia is prevalent in these leeches. This is the first report of Rickettsia found in annelids.

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12.
Martin  A. J.  Seaby  R. M. H.  Young  J. O. 《Hydrobiologia》1994,273(2):67-75
The effect of predator and prey body size on the feeding success of the British lake-dwelling leeches Glossiphonia complanata and Helobdella stagnalis was examined in the laboratory, and any involvement of size difference between the leeches in allowing coexistence in the field assessed. G. complanata breeds in advance of H. stagnalis and maintains a body size advantage throughout their annual life-cycle. In experiments, conducted at 14 °C and a photoperiod of 16 hrs L: 8 hrs D, three size classes of leeches of each species were each exposed to each of three size classes of each of five prey species, viz. Tubifex sp., Chironomus sp., Asellus aquaticus, Lymnaea peregra and Potamopyrgus jenkinsi. For each prey species, three different types of experiments were performed: one leech exposed to four prey individuals; four leeches of the same species with sixteen prey; and two leeches of each species with sixteen prey. In the first experiment, all sizes of G. complanata were capable of feeding on all sizes of the prey types offered; the same was true for H. stagnalis with exceptions of feeding on large A. aquaticus and large L. peregra. For both species, but especially for G. complanata, there was a trend within each size class of leech for decreasing proportions of fed leeches with increasing prey size, and within each size class of prey for an increasing proportion of fed leeches with increasing leech size; however there were several exceptions to these trends. Both leeches fed extensively on Tubifex sp. but there were significant differences in the proportions feeding on other prey types; G. complanata fed more on A. aquaticus and the two snail species, and less on Chironomus, than H. stagnalis. The effect of increasing the number of leech individuals from one to four individuals, of the same or mixed species, had little effect on the proportion of leeches which had fed. It is concluded that large G. complanata will have access to large individuals of certain prey taxa denied H. stagnalis, which may lessen the intensity of interspecific competition.  相似文献   

13.
Most animals harbour symbiotic microorganisms inside their body, where intimate interactions occur between the partners. The medicinal leech, Hirudo verbana, possesses 17 pairs of excretory bladders that harbour a large number of intracellular and extracellular symbiotic bacteria. In this study, we characterized the bladder symbionts using molecular phylogenetic analyses, transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH). Restriction fragment length polymorphism (RFLP) and sequence analyses of 16S rRNA gene clone libraries suggested that six bacterial species co‐colonize the leech bladders. Phylogenetic analyses revealed that these species belong to the α‐Proteobacteria (Ochrobactrum symbiont), β‐Proteobacteria (Beta‐1 and Beta‐2 symbionts), δ‐Proteobacteria (Bdellovibrio symbiont) and Bacteroidetes (Niabella and Sphingobacterium symbionts). Species‐specific PCR detection and FISH confirmed the localization of the symbiotic bacteria in the bladders. The Ochrobactrum, Beta‐1, Bdellovibrio and Sphingobacterium symbionts were consistently detected in 13 leeches from two populations, while infection rate of the other symbionts ranged between 20% and 100% in the two leech populations. Transmission electron microscopy observations of the bladders revealed epithelial cells harbouring a number of intracellular bacilli and an additional type of extracellular, rod‐shaped bacteria in the luminal region. Fluorescence in situ hybridization with group‐specific oligonucleotide probes revealed the spatial organization of the bacterial species in the bladder: the Ochrobactrum symbiont was located intracellularly inside epithelial cells; the Bacteroidetes were localized close to the epithelium in the lumen of the bladder; and the Bacteroidetes layer was covered with dense β‐proteobacterial cells. These results clearly demonstrate that a simple but organized microbial community exists in the bladder of the medicinal leech.  相似文献   

14.
The protein and peptide composition of medicinal leech salivary gland secretion (SGS) was analyzed in preparations obtained in July from three species--Hirudo verbana, H. medicinalis, and H. orientalis. Two-dimensional electrophoresis (molecular mass 10-150 kD and pI 3-10) revealed no distinctions in the distribution of over 100 silver-stained proteins. Differences were noted only in intensity of 10 protein spots at 30-90 kD and pI 4.7-7.5. Mass spectrometric profiling of SGS of the three leech species using the Zip-Tip/golden chip scheme and cation-exchanging chips CM-10 revealed over 50 components in SGS of each of the three leech species. It was noted that 30-40% of the individual masses of the SGS of each leech species fall within the masses present in SGS of at least one of the two other species. This rather small part of the total mass may be indicative of a high polymorphism of amino acid sequences or a high frequency of posttranslational modifications of the SGS proteins and peptides. Calculation of Jacquard's coefficient showed that H. medicinalis and H. orientalis are closest to each other in SGS composition, which is consistent with data in the literature on the phylogenetic relationship between these two species of medicinal leech. Comparison of detected molecular masses with those of six known biologically active compounds produced by medicinal leeches revealed their uneven distribution in SGS of each of the three medicinal leech species. This opens prospects for using certain species of medicinal leech for targeted therapy of various pathologies.  相似文献   

15.
Leeches within the Piscicolidae are of great numerical and taxonomic importance, yet little is known about bacteria that associate with this diverse group of blood-feeding marine parasites of fish and elasmobranchs. We focused primarily on the bacteria from a deep-sea leech species of unknown identity, collected at ~?600?m depth in Monterey Canyon, CA, along with two shallow-living leech genera, Austrobdella and Branchellion, from Los Angeles Harbor, CA. Molecular analysis of all five leech species revealed a dominance of gammaproteobacteria, which were distinct from each other and from previously reported freshwater leech symbionts. Bacteria related to members of the genus Psychromonas (99% similarity in 16S rRNA) were dominant in the deep-sea leech species (80-94% of recovered ribotypes) collected over 19 months from two different locations. Psychromonas was not detected in cocoons or 2-16 week-old juveniles, suggesting that acquisition is via the environment at a later stage. Transmission electron microscopy did, however, reveal abundant bacteria-like cells near areas of thinning of the juvenile epithelial surface, as well as Psychromonas sparsely distributed internally. Electron and fluorescence in situ microscopy of adults also showed Psychromonas-like bacteria concentrated within the crop. Despite the apparent non-transient nature of the association between Psychromonas and the deep-sea leech, their functional role, if any, is not known. The prevalence, however, of an abundant bacterial genus in one piscicolid leech species, as well as the presence of a dominant bacterial species in singular observations of four additional marine species, suggests that members of the Piscicolidae, possibly basal within the class Hirudinea, form specific alliances with microbes.  相似文献   

16.
17.
The hellbender (Cryptobranchus alleganiensis) is among the most intriguing and imperiled amphibians in North America. Since the 1970s and 80s, western populations of the Ozark and eastern subspecies in Missouri have declined by nearly 80%. As a result of population declines, the Ozark hellbender was recently federally protected as an endangered species, and the eastern subspecies was granted protection under CITES. Although habitat degradation is probably the biggest threat to hellbender populations, recent evidence suggests that pathogens including chytrid fungus and “flesh-eating” bacteria may also contribute to declines in Ozark hellbenders. Leeches, which are very common on Ozark hellbenders, have recently been implicated as possible vectors of disease among Ozark hellbenders but have not been described in eastern hellbenders or outside of Missouri and Arkansas. We discovered a population of leeches on eastern hellbenders in southwest Virginia and confirmed that the species of leech is within the genus Placobdella, but is morphologically and genetically distinct from all previously described leech species. We named the new species Placobdella appalachiensis sp. n. Moser and Hopkins, based on the mountainous region in which it was discovered. Our surveys over a three consecutive year period suggested that this leech species may be patchily distributed and/or have a narrow geographic range. We consistently detected leeches at one site (mean prevalence in 80 hellbenders = 27.5%; median intensity = 3.0 leeches per parasitized hellbender [range 1 – >250 leeches]) during three years of surveys, but we never found leeches in any of our other seven study sites in two streams (mean prevalence in 139 hellbenders = 0%). We found a significant positive relationship between hellbender body size and the intensity of parasitism, and we suggest the possibility that the behavioral ecology of adults leading up to reproduction may increase their encounter rates with parasites. We discuss the potential conservation implications of discovery of leeches in this stream, and make recommendations for future mitigation and monitoring efforts.  相似文献   

18.
Leeches have long been considered potential vectors for the aquatic lineage of trypanosomes, while bloodsucking insects are generally considered as the vectors for the terrestrial lineage of trypanosomes. The freshwater leech, Hirudinaria manillensis, is a widely distributed species in southern China and could potentially act as the vector for trypanosomes. Prior to this study, no trypanosomes had been reported from this leech. However, in this study, leeches were collected from three different places in Guangdong province, China, and a large number of flagellates were isolated and successfully cultured in vitro. Based on morphology, these flagellates looked like a typical trypanosome species. Analysis was carried out on the molecular sequences of the 18S rRNA gene and the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. To our surprise, these flagellates were identified as likely to be a mammalian trypanosome belonging to the clade containing Trypanosoma (Megatrypanum) theileri but they are significantly different from the typical TthI and TthII stocks. Analyses of blood composition indicated that the source of the blood meal in these leeches was from the water buffalo (Bubalus bubalis). To further test if this flagellate from the freshwater leech was indeed a mammalian trypanosome, we transferred the trypanosomes cultured at 27–37 °C and they were able to successfully adapt to this mammalian body temperature, providing further supporting evidence. Due to the significant genetic differences from other related trypanosomes in the subgenus Megatrypanum, we propose that this flagellate, isolated from H. manillensis, is a new species and have named it Trypanosoma bubalisi. Our results indicate that freshwater leeches may be a potential vector of this new mammalian trypanosome.  相似文献   

19.
A novel GGNG-related neuropeptide from the polychaete Perinereis vancaurica   总被引:2,自引:0,他引:2  
The GGNG peptides are myoactive peptides so far identified from earthworms and leeches, which are the earthworm excitatory peptides (EEP) and the leech excitatory peptide (LEP), respectively. A novel GGNG peptide was isolated and structurally determined from a marine polychaete, Perinereis vancaurica, using a combination of immunological assay and high performance liquid chromatography (HPLC). The peptide was a pentadecapeptide whose amino acid sequence was similar to that of EEP and LEP, and showed myoactivity on isolated esophagus of P. vancaurica with a threshold concentration of 10(-10)M. The peptide was designated as polychaete excitatory peptide (PEP). Amidation of the alpha-carboxyl group of C-terminal residue occurred in PEP. This is the case for LEP, but not for EEP. The cDNA cloning revealed that the structure of the PEP precursor is more similar to the EEP precursor than to the LEP precursor. Immunohistochemical staining showed the presence of PEP in several neurons of central nervous system (CNS) as somata and neuropile structure, epithelial cells of the pharynx and epidermal cells throughout the body wall. Altogether these results support the physiological significance of PEP in regulation of the CNS neural activity and the peripheral myoactivity.  相似文献   

20.
During October 2004 to April 2005, when water temperature ranged between 18 and 22 degrees C, over than 500 specimens of leeches namely Alboglossiphonia polypompholyx, Batracobdelloides tricarinata, Helobdella conifera (Rhynchobdellida), Barbronia assiuti, and Salifa delicata (Arhynchobdellida) were collected from Al-Sont canal near Assiut city. About 80% of these specimens were infected with the peritrich ciliate Epistylis sp. The infection occurred in the field, both rhynchobdellid and arhynchobdellid leeches were infected, but Epistylis can infect rhynchobdellids more than arhynchobdellids. Both light and scanning electron microscopy showed the morphology of this parasite which attached to the surface of the leech body by a stalk. Histopathological studies revealed the damage of cuticle, epidermis, and dermis of the leech body wall at the area of attachment and the leech body seemed to be sloughy. Presence of this parasite in high numbers covering large areas of the body can impede gas exchange leading to leech suffocation and finally its death. Like the other sessile single-celled ciliates Epistylis spp. feed on bacteria and suspended organic debris, which are prevalent in nutrient-rich water, hence, Epistylis is a good indicator of poor water quality (pollution). The present study represents the first report of the effect of Epistylis on leeches collected from Egypt.  相似文献   

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