Histochemistry and ultrastructure of the mycetome and its ‘symbiotes’ in the pear psylla, Psylla pyricola Foerster (Homoptera)

Chang, Kwang-Poo; Musgrave, A.

doi:10.1016/s0040-8166(69)80034-0

Cited by 37 publications

(26 citation statements)

References 21 publications

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“…Transmission electron micrographs of P. venusta bacteriocytes and endosymbionts (Fig. 5) were in agreement with past observations (16,55). The P endosymbionts were pleomorphic bacteria that had the electron-dense structures previously observed (55).…”

Section: Vol 66 2000 Psyllids and Their Endosymbionts 2901supporting

confidence: 90%

“…5). They have a gram-negative type of cell wall and are found within membrane vesicles derived from host cells (16,55). Their 16S rRNA gene is directly upstream of the 23S rRNA gene.…”

Section: Discussionmentioning

confidence: 99%

“…Within psyllids is a bacteriome that has some structural variability (10). The most common bacteriome described consists of a large multinucleate syncytium within which are uninucleate bacteriocytes (10,16,25,55). The latter contain a morphologically similar bacterium, designated the P endosymbiont; the syncytium may also contain an S endosymbiont, with different psyllids having different morphological types.…”

mentioning

confidence: 99%

“…The latter contain a morphologically similar bacterium, designated the P endosymbiont; the syncytium may also contain an S endosymbiont, with different psyllids having different morphological types. Electron microscopic studies have indicated that, as in the case of B. aphidicola, both the P endosymbiont and the S endosymbiont of psyllids have a gramnegative cell wall and are enclosed in vesicles derived from the host cells (16,55). Recently, the endosymbiont 16S rDNAs from four psyllid species were cloned and sequenced.…”

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confidence: 99%

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Cospeciation of Psyllids and Their Primary Prokaryotic Endosymbionts

Thao

Moran

Abbot

et al. 2000

Appl Environ Microbiol

269

230

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Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. Four-kilobase DNA fragments containing 16S and 23S ribosomal DNA (rDNA) were amplified from the primary (P) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. In addition, 0.54-kb fragments of the psyllid nuclear gene wingless were also amplified from 26 species. Phylogenetic trees derived from 16S-23S rDNA and from the host wingless gene are very similar, and tests of compatibility of the data sets show no significant conflict between host and endosymbiont phylogenies. This result is consistent with a single infection of a shared psyllid ancestor and subsequent cospeciation of the host and the endosymbiont. In addition, the phylogenies based on DNA sequences generally agreed with psyllid taxonomy based on morphology. The 3 end of the 16S rDNA of the P endosymbionts differs from that of other members of the domain Bacteria in the lack of a sequence complementary to the mRNA ribosome binding site. The rate of sequence change in the 16S-23S rDNA of the psyllid P endosymbiont was considerably higher than that of other bacteria, including other fast-evolving insect endosymbionts. The lineage consisting of the P endosymbionts of psyllids was given the designation Candidatus Carsonella (gen. nov.) with a single species, Candidatus Carsonella ruddii (sp. nov.).Insects within the families Aphididae (aphids), Psyllidae (psyllids), Aleyrodidae (whiteflies), and Pseudococcidae (mealybugs) feed predominantly or exclusively on plant phloem sap. These insects have a number of common structural properties (8) and constitute separate lineages within the suborder Sternorrhyncha (15, 54). The utilization of plant sap necessitates the penetration of tissue by flexible mouth parts (stylets) and the ingestion of the fluid. This mode of feeding is conducive to the transmission of viruses and other infectious agents, and members of these families are vectors of pathogens of agriculturally important plants (7,28,51). In addition, these insects may reach enormous populations, causing plant nutrient deprivation, leaf curling, and gall formation (8). Plant phloem sap, the diet of these insects, is rich in carbohydrates but deficient in nitrogenous compounds (21,46). Due to this deficiency, a large amount of plant sap is consumed and is excreted as honeydew. This sticky material may cover the plant and serve as a substrate for fungal growth (8).A common feature of organisms that live on diets containing an excess of one class of compounds and a deficiency in essential nutrients is the presence of prokaryotic intracellular symbionts (endosymbionts) that may provide the missing essential nutrients (6, 21, 37). Early histological studies indicated that these endosymbionts are housed within specialized cells (bacteriocytes) that form an aggregate (bacteriome) found within the body cavity (5, 10, 37). Typically, insects of a particular family or superfamily were found to have a ...

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Section: Vol 66 2000 Psyllids and Their Endosymbionts 2901supporting

confidence: 90%

“…5). They have a gram-negative type of cell wall and are found within membrane vesicles derived from host cells (16,55). Their 16S rRNA gene is directly upstream of the 23S rRNA gene.…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Cospeciation of Psyllids and Their Primary Prokaryotic Endosymbionts

Thao

Moran

Abbot

et al. 2000

Appl Environ Microbiol

269

230

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“…The primary endosymbionts of psyllids, designated Carsonella ruddii, constitute a unique lineage within the ␥ 3 subdivision of the Proteobacteria (11,26,28). They are located within host cells called bacteriocytes, where they are enclosed by host-derived membrane vesicles; the multicellular structure containing the bacteriocytes is called a bacteriome (6,7,11,31). In a recent study of 32 psyllid species, the phylogenetic tree derived from the 16S-23S rDNA of C. ruddii agreed with the tree derived from a host gene, a result consistent with a single infection of a psyllid ancestor and subsequent vertical transmission (cospeciation) of endosymbionts and hosts (28).…”

mentioning

confidence: 99%

Degenerative Minimalism in the Genome of a Psyllid Endosymbiont

et al. 2001

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Psyllids, like aphids, feed on plant phloem sap and are obligately associated with prokaryotic endosymbionts acquired through vertical transmission from an ancestral infection. We have sequenced 37 kb of DNA of the genome of Carsonella ruddii, the endosymbiont of psyllids, and found that it has a number of unusual properties revealing a more extreme case of degeneration than was previously reported from studies of eubacterial genomes, including that of the aphid endosymbiont Buchnera aphidicola. Among the unusual properties are an exceptionally low guanine-plus-cytosine content (19.9%), almost complete absence of intergenic spaces, operon fusion, and lack of the usual promoter sequences upstream of 16S rDNA. These features suggest the synthesis of long mRNAs and translational coupling. The most extreme instances of base compositional bias occur in the genes encoding proteins that have less highly conserved amino acid sequences; the guanine-plus-cytosine content of some protein-coding sequences is as low as 10%. The shift in base composition has a large effect on proteins: in polypeptides of C. ruddii, half of the residues consist of five amino acids with codons low in guanine plus cytosine. Furthermore, the proteins of C. ruddii are reduced in size, with an average of about 9% fewer amino acids than in homologous proteins of related bacteria. These observations suggest that the C. ruddii genome is not subject to constraints that limit the evolution of other known eubacteria.

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