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1.
Tight interactions between unrelated organisms such as is seen in plant-insect, host-parasite, or host-symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S-23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected. 相似文献
2.
Mealybugs (Hemiptera, Coccoidea, Pseudococcidae) are plant sap-sucking insects that have within their body cavities specialized cells containing prokaryotic primary endosymbionts (P-endosymbionts). The P-endosymbionts have the unusual property of containing within their cytoplasm prokaryotic secondary endosymbionts (S-endosymbionts) [C. D. von Dohlen, S. Kohler, S. T. Alsop, and W. R. McManus, Nature (London) 412:433-436, 2001]. Four-kilobase fragments containing 16S-23S ribosomal DNA (rDNA) were obtained from the P-endosymbionts of 22 mealybug species and the S-endosymbionts of 12 representative species. Phylogenetic analyses of the P-endosymbionts indicated that they have a monophyletic origin and are members of the beta-subdivision of the Proteobacteria; these organisms were subdivided into five different clusters. The S-endosymbionts were members of the gamma-subdivision of the Proteobacteria and were grouped into clusters similar to those observed with the P-endosymbionts. The S-endosymbiont clusters were distinct from each other and from other insect-associated bacteria. The similarity of the clusters formed by the P- and S-endosymbionts suggests that the P-endosymbionts of mealybugs were infected multiple times with different precursors of the S-endosymbionts and once the association was established, the P- and S-endosymbionts were transmitted together. The lineage consisting of the P-endosymbionts of mealybugs was given the designation "Candidatus Tremblaya" gen. nov., with a single species, "Candidatus Tremblaya princeps" sp. nov. The results of phylogenetic analyses of mitochondrial DNA fragments encoding cytochrome oxidase subunits I and II from four representative mealybug species were in agreement with the results of 16S-23S rDNA analyses, suggesting that relationships among strains of "Candidatus T. princeps" are useful in inferring the phylogeny of their mealybug hosts. 相似文献
3.
Marta A. Clark Dr. Linda Baumann Mark A. Munson Paul Baumann Bruce C. Campbell James E. Duffus Lance S. Osborne Nancy A. Moran 《Current microbiology》1992,25(2):119-123
Whiteflies (superfamily Aleyrodoidea) contain eubacterial endosymbionts localized within host cells known as mycetocytes. Sequence analysis of the genes for the 16S rRNA of the endosymbionts ofBemisia tabaci, Siphoninus phillyreae, andTrialeurodes vaporariorum indicates that these organisms are closely related and constitute a distinct lineage within the -subdivision of theProteobacteria. The endosymbionts of whiteflies are unrelated to the endosymbionts of aphids and mealybugs, which are in two separate lineages. 相似文献
4.
The development of molecular techniques for the study of uncultured bacteria allowed the extensive study of the widespread association between insects and intracellular symbiotic bacteria. Most of the bacterial endosymbionts involved in such associations are gamma-proteobacteria, closely related to Escherichia coli. In recent years, five genomes from insect endosymbionts have been sequenced, allowing the performance of extensive genome comparative analysis that, as a complement of phylogenetic studies, and analysis on individual genes, can help to understand the different traits of this particular association, including how the symbiotic process is established, the explanation of the special features of these microbial genomes, the bases of this intimate association and the possible future that awaits the endosymbionts with extremely reduced genomes. 相似文献
5.
There is an extraordinary diversity in genetic systems across species, but this variation remains poorly understood. In part, this is because the mechanisms responsible for transitions between systems are often unknown. A recent hypothesis has suggested that conflict between hosts and endosymbiotic microorganisms over transmission could drive the transition from diplodiploidy to systems with male haploidy (haplodiploidy, including arrhenotoky and paternal genome elimination [PGE]). Here, we present the first formal test of this idea with a comparative analysis across scale insects (Hemiptera: Coccoidea). Scale insects are renowned for their large variation in genetic systems, and multiple transitions between diplodiploidy and haplodiploidy have taken place within this group. Additionally, most species rely on endosymbiotic microorganisms to provide them with essential nutrients lacking in their diet. We show that species harboring endosymbionts are indeed more likely to have a genetic system with male haploidy, which supports the hypothesis that endosymbionts might have played a role in the transition to haplodiploidy. We also extend our analysis to consider the relationship between endosymbiont presence and transitions to parthenogenesis. Although in scale insects there is no such overall association, species harboring eukaryote endosymbionts were more likely to be parthenogenetic than those with bacterial symbionts. These results support the idea that intergenomic conflict can drive the evolution of novel genetic systems and affect host reproduction. 相似文献
6.
蚜虫作为典型的刺吸式昆虫,需要以取食植物韧皮部汁液来补充营养,几乎所有蚜虫均带有一种能为其提供植物韧皮部缺失营养物质的初生共生菌Buchnera aphidicola。此外,蚜虫还可携带一种或多种次生内共生菌。在众多共生菌—寄主系统中,蚜虫与其所带内共生菌间的互作研究最为透彻。虽然次生内共生菌对寄主的存活和生殖影响并不显著,但其在寄主对环境耐受力、天敌防御能力等方面作用明显。本文在查阅大量蚜虫次生内共生菌相关文献的基础上,着重对蚜虫次生内共生菌的种类及传播规律、次生内共生菌对蚜虫表型的影响、蚜虫次生内共生菌基因组学等方面的研究现状进行综述,以求为刺吸式昆虫次生内共生菌的研究提供参考。 相似文献
7.
Sui HS Liu Y Miao DQ Yuan JH Qiao TW Luo MJ Tan JH 《Molecular reproduction and development》2005,71(2):227-236
Configuration of germinal vesicle (GV) chromatin has been studied and found correlated with the developmental competence of oocytes in several mammalian species. A common feature in the configuration of GV chromatin in the species studied so far is that the diffuse chromatin (the so called "NSN" pattern) condenses into a perinucleolar ring (the so called "SN" configuration) with follicular growth. However, no study has been published on the configuration of GV chromatin in the goat. Nor is it known whether the perinucleolar ring of condensed chromatin (CC) in an oocyte represents a step toward final maturation or atresia. Changes in configurations of GV chromatin and RNA synthesis during goat oocyte growth, atresia and maturation in vivo and in vitro were investigated in this study. Based on both the size of nucleoli and the degree of chromatin condensation, the GV chromatin of goat oocytes was classified into GV1 characterized by large nucleoli and diffuse chromatin, GV2 with medium-sized nucleoli and condensed net-like (GV2n) or clumped (GV2c) chromatin, GV3 with small nucleoli and net-like (GV3n) or clumped (GV3c) chromatin, and GV4 with no nucleolus but clumped chromatin. The results showed that (i) the configurations of GV chromatin in the goat differ from those of other species in that the chromatin did not condense into a perinucleolar ring; (ii) most of the goat oocytes are synchronized at the GV3n configuration before GVBD; (iii) the GVn pattern might represent a healthy state, but the GVc an atretic state; (iv) in both goats and mice, the GC-specific (Chromomycin A3, CMA3) and the AT-specific (Hoechst 33342) fluorochromes followed the same pattern of distribution in GV chromatin; (v) the nucleolar size decreased significantly with oocyte growth and maturation in vivo and in vitro; and (vi) goat oocytes began GVBD at 8 hr and had completed it by 20 hr after onset of estrus. The peculiar configuration of GV chromatin of goat oocytes can be a useful model for studies of morphological and functional changes of different nuclear compartments during the cell cycle and cell differentiation, and the functional differentiation between GV3n and GV3c might be used for reference to the question whether the "SN" configuration in other species inclines toward ovulation or atresia. 相似文献
8.
Insects in the sap-sucking hemipteran suborder Sternorrhyncha typically harbor maternally transmitted bacteria housed in a specialized organ, the bacteriome. In three of the four superfamilies of Sternorrhyncha (Aphidoidea, Aleyrodoidea, Psylloidea), the bacteriome-associated (primary) bacterial lineage is from the class Gammaproteobacteria (phylum Proteobacteria). The fourth superfamily, Coccoidea (scale insects), has a diverse array of bacterial endosymbionts whose affinities are largely unexplored. We have amplified fragments of two bacterial ribosomal genes from each of 68 species of armored scale insects (Diaspididae). In spite of initially using primers designed for Gammaproteobacteria, we consistently amplified sequences from a different bacterial phylum: Bacteroidetes. We use these sequences (16S and 23S, 2105 total base pairs), along with previously published sequences from the armored scale hosts (elongation factor 1alpha and 28S rDNA) to investigate phylogenetic congruence between the two clades. The Bayesian tree for the bacteria is roughly congruent with that of the hosts, with 67% of nodes identical. Partition homogeneity tests found no significant difference between the host and bacterial data sets. Of thirteen Shimodaira-Hasegawa tests, comparing the original Bayesian bacterial tree to bacterial trees with incongruent clades forced to match the host tree, 12 found no significant difference. A significant difference in topology was found only when the entire host tree was compared with the entire bacterial tree. For the bacterial data set, the treelengths of the most parsimonious host trees are only 1.8-2.4% longer than that of the most parsimonious bacterial trees. The high level of congruence between the topologies indicates that these Bacteroidetes are the primary endosymbionts of armored scale insects. To investigate the phylogenetic affinities of these endosymbionts, we aligned some of their 16S rDNA sequences with other known Bacteroidetes endosymbionts and with other similar sequences identified by BLAST searches. Although the endosymbionts of armored scales are only distantly related to the endosymbionts of the other sternorrhynchan insects, they are closely related to bacteria associated with eriococcid and margarodid scale insects, to cockroach and auchenorrynchan endosymbionts (Blattabacterium and Sulcia), and to male-killing endosymbionts of ladybird beetles. We propose the name "Candidatus Uzinura diaspidicola" for the primary endosymbionts of armored scale insects. 相似文献
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Klempa B Witkowski PT Popugaeva E Auste B Koivogui L Fichet-Calvet E Strecker T Ter Meulen J Krüger DH 《Journal of virology》2012,86(7):3819-3827
We have discovered the first indigenous African hantavirus, Sangassou virus (SANGV). The virus was isolated from an African wood mouse (Hylomyscus simus), trapped in a forest habitat in Guinea, West Africa. Here, we report on the characterization of the genetic and functional properties of the virus. The complete genome of SANGV was determined and showed typical hantavirus organization. The small (S), medium (M), and large (L) genome segments containing genes encoding nucleocapsid protein, two envelope glycoproteins, and viral polymerase were found to be 1,746, 3,650, and 6,531 nucleotides long, respectively. The exact 5' and 3' termini for all three segments of the SANGV genome were determined and were predicted to form the panhandle structures typical of bunyaviruses. Phylogenetic analyses of all three segment sequences confirmed SANGV as a Murinae-associated hantavirus most closely related to the European Dobrava-Belgrade virus. We showed, however, that SANGV uses β(1) integrin rather than β(3) integrin and decay-accelerating factor (DAF)/CD55 as an entry receptor. In addition, we demonstrated a strong induction of type III lambda interferon (IFN-λ) expression in type I IFN-deficient Vero E6 cells by SANGV. These properties are unique within Murinae-associated hantaviruses and make the virus useful in comparative studies focusing on hantavirus pathogenesis. 相似文献
11.
Kornblatt JA Kornblatt MJ Lange R Mombelli E Guillemette JG 《Biochimica et biophysica acta》1999,1431(1):238-248
The overall derivative spectrum of a protein is the sum of the individual derivative spectra just as the overall ultraviolet spectrum of a protein is the sum of its component parts. The RNase and DNA binding protein Sso7d has two tyrosines and one tryptophan. We used two mutant forms of the protein to show that the individual aromatics contribute derivative spectra that can be explained on the basis of their environments. We used mutant forms of iso-1-cytochrome c to estimate the contributions of the single tryptophan and three of the five tyrosines to the overall derivative spectrum. The tryptophan spectrum is not exceptional. The comparable tyrosine spectra are more complex. The derivative spectrum of individual tyrosines does not correspond to that expected on the basis of concentration. This is a reflection of two factors: (1) the extent to which mutations are sensed distally through the introduction and compression of packing defects; and (2) the extent to which electronic transitions of tyrosine are influenced by nearby atoms. This influence could take the form of tyrosine residing in an area where the dielectric coefficient is not uniform; it could also result from tyrosine bumping into neighboring atoms with lower frequency than it does in solution. 相似文献
12.
I. A. Gavrilov 《Entomological Review》2006,86(9):995-1001
The present paper is the third part of a revision of the fauna of the Volga Area. Five species new for the Volga Area, including four new for Russia are recorded. Nudicauda gen. n. is erected with type species Nudicauda nigra (Matesova, 1957) (comb. n.). The new genus differs from other genera of mealybugs in a complex of characters and mainly in the presence of very specific oral rim tubular ducts with a broad flat ring and in an unusual ovisac with the opening over posterior tergites of the female body. In addition to the type species, N. orientalis (Borchsenius, 1949) and N. salina (Matesova, 1981) (comb. n.) are also included in the new genus. N. nigra and N. orientalis are considered as separate species, contrary to Danzig (1980). All the three species of the new genus are redescribed and illustrated. The structure of the tubular ducts of the genus Humococcus Ferris, 1953 is briefly discussed and illustrated. 相似文献
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Calcium gradients in conifer pollen tubes; dynamic properties differ from those seen in angiosperms 总被引:8,自引:0,他引:8
Lazzaro MD Cardenas L Bhatt AP Justus CD Phillips MS Holdaway-Clarke TL Hepler PK 《Journal of experimental botany》2005,56(420):2619-2628
Pollen tubes are an established model system for examining polarized cell growth. The focus here is on pollen tubes of the conifer Norway spruce (Picea abies, Pinaceae); examining the relationship between cytosolic free Ca2+, tip elongation, and intracellular motility. Conifer pollen tubes show important differences from their angiosperm counterparts; they grow more slowly and their organelles move in an unusual fountain pattern, as opposed to reverse fountain, in the tip. Ratiometric ion imaging of growing pollen tubes, microinjected with fura-2-dextran, reveals a tip-focused [Ca2+]i gradient extending from 450 nM at the extreme apex to 225 nM at the base of the tip clear zone. Injection of 5,5' dibromo-BAPTA does not dissipate the apical gradient, but stops cell elongation and uniquely causes rapid, transient increases of apical free Ca2+. The [Ca2+]i gradient is, however, dissipated by reversible perfusion of extracellular caffeine. When the basal cytosolic free Ca2+ concentration falls below 150 nM, again a large increase in apical [Ca2+]i occurs. An external source of calcium is not required for germination but significantly enhances elongation. However, both germination and elongation are significantly inhibited by the inclusion of calcium channels blockers, including lanthanum, gadolinium, or verapamil. Modulation of intracellular calcium also affects organelle position and motility. Extracellular perfusion of lanthanides reversibly depletes the apical [Ca2+]i gradient, altering organelle positioning in the tip. Later, during recovery from lanthanide perfusion, organelle motility switches direction to a reverse fountain. When taken together these data show a unique interplay in Picea abies pollen tubes between intracellular calcium and the motile processes controlling cellular organization. 相似文献
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Isolated cell walls exhibit cation binding properties distinct from those of plant roots 总被引:1,自引:0,他引:1
Stéphanie Guigues Matthieu N. Bravin Cédric Garnier Armand Masion Emmanuel Doelsch 《Plant and Soil》2014,381(1-2):367-379
Aims
The principal contributor to the cation binding properties of roots is currently considered to be the cell wall or, alternatively, the plasma membrane. The aim of this study was to highlight their respective contributions in the binding properties.Methods
Cell walls of a dicotyledon (Solanum lycopersicum L.) and monocotyledon (Triticum aestivum L.) were isolated from roots and their binding properties were compared to those of their respective roots. Cell wall and root binding capacities were evaluated by potentiometric titrations and cation exchange capacity measurements, while their biochemical composition was analyzed by 13C-NMR spectroscopy.Results
The lower binding capacity of isolated cell walls compared to roots revealed that cell plasma membranes had a higher binding site density than cell walls. The significant decrease in some NMR signals, i.e. carbonyl C, N alkyl/methoxyl C and alkyl C regions, suggested that carboxyl, amine and phosphate binding sites, borne by proteins and phospholipid plasma membranes, contribute to the binding capacity.Conclusions
Cell walls and plasma membranes were found to be jointly involved in root binding properties and their respective contributions seemed vary between plants. 相似文献18.
Reisch Christoph Lehmair Theresa A. Pagel Ellen Poschlod Peter 《Biodiversity and Conservation》2021,30(12):3549-3561
Biodiversity and Conservation - The conservation of genetic diversity requires a deeper understanding of the processes shaping intraspecific variation. In recent decades, numerous studies... 相似文献
19.
Deeley JM Mitchell TW Wei X Korth J Nealon JR Blanksby SJ Truscott RJ 《Biochimica et biophysica acta》2008,1781(6-7):288-298
Electrospray ionisation tandem mass spectrometry has allowed the unambiguous identification and quantification of individual lens phospholipids in human and six animal models. Using this approach ca. 100 unique phospholipids have been characterised. Parallel analysis of the same lens extracts by a novel direct-insertion electron-ionization technique found the cholesterol content of human lenses to be significantly higher (ca. 6 times) than lenses from the other animals. The most abundant phospholipids in all the lenses examined were choline-containing phospholipids. In rat, mouse, sheep, cow, pig and chicken, these were present largely as phosphatidylcholines, in contrast 66% of the total phospholipid in Homo sapiens was sphingomyelin, with the most abundant being dihydrosphingomyelins, in particular SM(d18:0/16:0) and SM(d18:0/24:1). The abundant glycerophospholipids within human lenses were found to be predominantly phosphatidylethanolamines and phosphatidylserines with surprisingly high concentrations of ether-linked alkyl chains identified in both classes. This study is the first to identify the phospholipid class (head-group) and assign the constituent fatty acid(s) for each lipid molecule and to quantify individual lens phospholipids using internal standards. These data clearly indicate marked differences in the membrane lipid composition of the human lens compared to commonly used animal models and thus predict a significant variation in the membrane properties of human lens fibre cells compared to those of other animals. 相似文献
20.
Phylogenetic relationships of the endosymbionts of mealybugs (Homoptera: Pseudococcidae) based on 16S rDNA sequences. 总被引:7,自引:0,他引:7
A portion of the gene coding for the 16S ribosomal RNA from the endosymbionts of three species of mealybugs [Pseudococcus longispinus (Targioni-Tozzetti), Pseudococcus maritimus (Ehrhorn), and Dysmicoccus neobrevipes (Beardsley)] was cloned, sequenced, and compared to a homologous fragment from bacteria representative of aphid endosymbionts as well as major subdivisions of the Proteobacteria. Parsimony analysis of the sequences indicated that the mealybug endosymbionts are related and belong to the beta-subdivision; in contrast, previous studies showed that aphid endosymbionts are part of the gamma-subdivision. These findings suggest that the endosymbiosis of mealybugs is a consequence of a single bacterial infection and indicate that this ancestor was different from the ancestor involved in aphid endosymbiosis. 相似文献