9 results on '"SCANNING electron microscopes"'
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2. Pit membranes and their evolution in the Oleinae of the Oleaceae.
- Author
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Nguyen, Chieuda, Andrews, Ashley, Baas, Pieter, Bond, Jason E., Auad, Maria, and Dute, Roland
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SCANNING electron microscopes , *FOSSIL dicotyledons , *NESTEGIS , *MICROSCOPE light sources ,ONTOGENY of plants - Abstract
Chionanthus retusus and most Osmanthus spp. possess torus-bearing intervascular pit membranes in their woods. Because the genera involved are thought to be closely related and are members of the subtribe Oleinae, we hypothesized that torus morphology should be similar across taxa. A study combining light, scanning electron, and atomic force microscopy indicates that tori in both genera comprise a bipartite thickening containing a central pustular region and an encircling corona. Removal of incrusting material from the torus exposes subtending sets of parallel microfibrils. We hypothesize that the torus structures of C. retusus and Osmanthus spp. (as represented by O. armatus) have the same morphology. Optimizing torus-bearing pits on published molecular phylogenies of the subtribe Oleinae indicates parallel evolution as an explanation for torus similarity between these two groups, although a robust and well-resolved phylogeny of the Oleaceae is still lacking. A brief study of the wood anatomy of Olea dioica was also undertaken. This species is a member of the subgenus Tetrapilus and thought to be closely related to torus-bearing genera of the Oleaceae. Despite the close relationship, no tori were observed in O. dioica. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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3. Description of Aphelenchoides stellatus n. sp. (Nematoda: Aphelenchoididae) found in packaging wood from Japan.
- Author
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Yiwu FANG, Jianfeng Gu, Xuan WANG, and Hongmei Li
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APHELENCHOIDIDAE , *SPERMATHECA , *SPERMATOZOA , *SCANNING electron microscopes , *CLADISTIC analysis , *RECOMBINANT DNA - Abstract
Aphelenchoides stellatus n. sp. is described and figured. The new species was isolated from packaging wood from Japan imported to Ningbo harbour, China. The new species has a body length of 485-533 μm (males) and 547-699 μm (females). The cuticle is weakly annulated and there are four lines in the lateral field. The stylet is 9-11 μm long and has small basal swellings. The excretory pore is located posterior to the nerve ring. Spicules smoothly curved, rose-thorn shaped. Apex and rostrum round, only slightly offset, dorsal limb 19-21 μm long. Male tail bearing six (2 + 2 + 2) caudal papillae. The female spermatheca is axial and oblong with round sperm present in multiple rows. Both male and female tail pegs have 3-4 processes, appearing star-like under SEM. The new species belongs to the Group 3 category of Aphelenchoides species. Phylogenetic analyses based on full length ITS and 28S D2/D3 region of rDNA confirmed its morphological status as a new species. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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4. Morphological and molecular characterisation of some Hemicriconemoides species (Nematoda: Criconematidae) together with a phylogeny of the genus.
- Author
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VAN DEN BERG, Esther, TIEDT, Louwrens R., INSERRA, Renato N., STANLEY, Jason D., VOVLAS, Nicola, PALOMARES RIUS, Juan E., CASTILLO, Pablo, and SUBBOTIN, Sergei A.
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CRICONEMATIDAE , *PHYLOGENY , *CROPS , *FRUIT trees , *ECTOPARASITES , *SCANNING electron microscopes , *POLYMERASE chain reaction - Abstract
Sheathoid nematodes of the genus Hemicriconemoides are migratory root-ectoparasites of many plants including various agricultural crops and fruit trees. They are generally found inhabiting warm areas of the world and presently consist of 52 valid species. In this study we provide morphological and molecular characterisation of 12 species of this genus viz. : H. alexis, H. brachyurus, H. californianus, H. chitwoodi, H. macrodorus, H. minutus, H. ortonwilliamsi, H. promissus, H. silvaticus, H. strictathecatus, H. wessoni and Hemicriconemoides sp. originating from China, Greece, Japan, Myanmar, Spain, South Africa and the USA. Morphological descriptions, measurements, light and scanning electron microscopic observations and drawings are given for several species. Phylogenetic relationships within Hemicriconemoides, as inferred from the analyses of the D2-D3 of 28S rRNA and ITS-rRNA gene sequences, resulted in trees with three major clades that corresponded with species groupings based on morphology of the lip pattern and vulval flap. PCR with species-specific primers were developed for H. calif ornianus, H. chitwoodi and H. strictathecatus. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
5. Morphological and molecular characterisation of several Paratylenchus Micoletzky, 1922 (Tylenchida: Paratylenchidae) species from South Africa and USA, together with some taxonomic notes.
- Author
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VAN DEN BERG, Esther, TIEDT, Louwrens R., and SUBBOTIN, Sergei A.
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MORPHOLOGY , *TYLENCHIDA , *NEMATODES , *RIBOSOMAL RNA , *SCANNING electron microscopes - Abstract
Pin nematodes of the genus Paratylenchus are widely distributed across the world and associated with many plant species. Morphological identification of Paratylenchus species is a difficult task because it relies on many characters with a wide range of intraspecific variation. In this study we provide morphological and molecular characterisation of several pin nematodes: Paratylenchus aquaticus, P. dianthus, P. hamatus, P. nanus and P. straeleni, collected in different states of the USA and South Africa. Paratylenchus aquaticus is reported from South Africa and Hawaii and P. nanus is found from South Africa for the first time. Morphological descriptions, morphometries, light and scanning electron microscopic photos and drawings are given for these species. Molecular characterisation of nematodes using the D2-D3 of 28S rRNA and ITS rRNA gene sequence revealed that samples morphologically identified as P. aquaticus, P. hamatus and P. nanus indeed represent species complexes containing several species. Sequences of the rRNA genes are also provided for several unidentified Paratylenchus. Phylogenetic relationships within the genus Paratylenchus are given as inferred from the analyses of the D2-D3 of 28S rRNA and ITS rRNA gene sequences. We present here the most complete phylogenetic analysis of the genus. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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6. Morphological variability in second-stage juveniles and males of Meloidogyne chitwoodi.
- Author
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HUMPHREYS-PEREIRA, Danny A. and ELLING, Axel A.
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MORPHOMETRICS , *ROOT-knot nematodes , *DISCRIMINANT analysis , *SCANNING electron microscopes , *PLANT morphology , *ANALYSIS of variance - Abstract
The morphology of Meloidogyne chitwoodi is relatively poorly characterised. In a recent study, morphological variation in adult females of M. chitwoodi was analysed. However, comparable data are lacking for adult males and second-stage juveniles (J2). Therefore, our studies of four M. chitwoodi isolates from the western USA, representing all currently known races and pathotypes, were designed to characterise intraspecific morphological variability in J2 and males and to compare it to variability found in adult females. Multivariate analysis of variance indicated statistically significant variation among isolates for both J2 and males. Moreover, for adult males, canonical discriminant analysis grouped races with their respective pathotypes. In addition, we analysed two morphological features that were previously uncharacterised for M. chitwoodi, i.e., stylet knob width and distance from secretory-excretory pore to anterior end. Both of these characters may be useful in distinguishing M. chitwoodi from closely related species. SEM clearly showed the presence of areolations along the bodies of J2, thereby separating M. chitwoodi from M. fallax and M. minor. In summary, this study indicates that M. chitwoodi J2 and adult males show substantially more intraspecific morphological variability than previously known. Consequences for diagnostics are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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7. Testudinema gilchristi n. gen., n. sp. (Nematoda: Monhysteridae) from the perianal folds of stinkpot turtles, Sternotherus odoratus (Testudines), USA.
- Author
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Abebe, Eyualem, Sharma, Jyotsna, Mundo-Ocampo, Manuel, and Platt, Thomas R.
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NEMATODE classification , *MONHYSTERIDAE , *TURTLES , *STERNOTHERUS odoratus , *SCANNING electron microscopes - Abstract
Examination of perianal folds of stinkpot turtles, Sternotherus odoratus, from Virginia, USA, revealed several monhysterid nematodes. The general morphological characteristics of this population, such as circular amphids, unstriated cuticle under light microscope, single outstretched ovary, single testis, caudal glands, terminal spinneret and the absence of an apophysis on the gubernaculum, with the exception of the position of the gonad in relation to the intestine, shows the affinity of this population to the Monhysteridae. Microscopic observations of the inner stoma show three (one dorsal and two ventro-sublateral) buccal wall extensions towards the lumen and numerous (ca 50) distinct denticles on its wall. Because this stoma structure is a morphological novelty within the Monhysterida and this is the first monhysterid group associated with perianal folds of turtles, we propose to establish Testudinema n. gen. within the Monhysteridae to accommodate this morphologically distinct population. We provide a detailed comparison with known monhysterid genera including those that possess a cup-shaped stoma, stoma with denticles or those genera reported to be commensals (Gammarinema, Monhystrium, Tripylium, Odontobius). Stinkpot turtles feed on benthic fauna and may acquire these commensals when the sediment is disturbed. The denticles and structure of the buccal cavity could be morphological adaptations for transition to ecto-parasitism. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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8. Revision and phylogeny of Tarvaia Allgén, 1934 (Nematoda: Tarvaiidae).
- Author
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Holovachov, Oleksandr, Fadeeva, Natalia, De Ley, Irma Tandingan, Mundo-Ocampo, Manuel, Gingold, Ruth, and De Ley, Paul
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NEMATODE phylogeny , *ANIMAL species , *DESMOSCOLECIDA , *RECOMBINANT DNA , *SCANNING electron microscopes - Abstract
Descriptions of eight new and three known species of Tarvaia are given. Tarvaia pacifica sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina with pars refringens vaginae, slightly asymmetrical spicules, gubernaculum with two dorsal apophyses, precloacal ridge present; T. algicola sp. n. has cephalic capsule with unevenly thickened walls reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina, apophyses absent, precloacal ridge present; T. carolinensis sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield with ornamentation, sigmoid vagina, gubernaculum with a dorsal apophysis; T. longispiculata sp. n. has elongated cephalic capsule reaching posterior part of elongate amphids, amphidial shield without ornamentation, sigmoid vagina, unusually long spicules, gubernaculum with dorsal apophysis, precloacal ridge present; T. inaequalis sp. n. has short cephalic capsule reaching anterior third of elongate amphids, amphidial shield with ornamentation, straight vagina, strongly anisometric spicules, gubernaculum with caudal apophysis, precloacal ridge present; T. sakhalinensis sp. n. has short cephalic capsule reaching middle of short amphids, amphidial shield with distinct pores, symmetrical spicules, apophyses absent; T. tchesunovi sp. n. has cephalic capsule with unevenly thickened walls reaching posterior part of short amphids, amphidial shield without ornamentation, symmetrical spicules, apophyses absent; and T. ricordensis sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina, symmetrical spicules, gubernaculum with dorsal apophyses. Updated descriptions of T. donsi, T. cladara and T. gerlachi are provided. Phylogenese analysis based on 18S rDNA suggests a close relationship between Tarvaia and Desmoscolecida. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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9. Diversity of Meloidogyne arenaria using morphological, cytological and molecular approaches.
- Author
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Carneiro, Regina M.D.G., dos Santos, Marcilene F.A., Almeida, Maria Ritta A., Mota, Fabiane Castro, Gomes, Ana Cristina M.M., and Tigano, Myrian S.
- Subjects
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RAPD technique , *ROOT-knot nematodes , *SCANNING electron microscopes , *TAXONOMY , *PEANUT root-knot nematode , *POLYMORPHISM (Zoology) - Abstract
Thirteen Meloidogyne arenaria isolates representing two cytological types (3n = 51-56, 2n = 42-48) and four enzymatic phenotypes (esterase and malate dehydrogenase: A3N1, A2N1, A1N1, A2N3) were studied using different approaches. The analysis of molecular markers showed a high level of polymorphism among the isolates. The trees obtained with RAPD or ISSR polymorphisms showed concordant results and agree with morphological studies. By considering morphometrical and morphological features, it was possible to conclude that the isolate with enzymatic phenotype A2N3 race 1 was the M. arenaria described in 1949 by Chitwood and appearing clearly separated in the trees, as well as in the outgroups. The seven isolates with phenotype A2N1 from different localities and isolate A1N1 can be considered morphometrically typical of M. arenaria race 2 and they were apparently clustered by geographical origin. Morphologically, they differed from isolate A2N3 race 1. The two isolates with phenotype A3N1 appeared to be closely related to the isolate of M. morocciensis and, considering all of the features described for this species, were identified as such. The two isolates A2N3 race 2 were identified either as an atypical M. arenaria or an unidentified species (females and males having atypical stylets), and clustered together and separated from other M. arenaria isolates with high bootstrap support. The same M. arenaria isolates were tested with the species-specific molecular marker, type SCAR. A fragment of 420 bp was obtained for ten isolates of M. arenaria, including the atypical A2N3 race 2 and M. morocciensis. This fragment was not amplified for three typical A2N1 isolates of M. arenaria. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
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