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501.
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503.
Mitochondrial DNA sequence variation in the spruce budworm species complex (Choristoneura: Lepidoptera) 总被引:5,自引:0,他引:5
A combination of polymerase-chain-reaction amplification and automated DNA
sequencing was used to survey variation in a species complex of pest
insects, the spruce budworms (Choristoneura fumiferana species group), and
an outgroup species, C. rosaceana. We sequenced an mtDNA region of 1,573 bp
that extends from the middle of cytochrome oxidase subunit I (COI) through
tRNA leucine (UUR) to the end of cytochrome oxidase subunit II. In
addition, we examined levels of intraspecific variation within a 470-bp
region of the COI gene. Choristoneura fumiferana clearly represented the
oldest lineage within its species group, with 2.7%-2.9% sequence divergence
from the other species. In contrast, the four remaining species (C. pinus,
C. biennis, C. occidentalis, and C. orae) had closely related or identical
mtDNA, with < 1% divergence among most of their haplotypes. Despite its
older lineage and widespread geographic distribution, C. fumiferana showed
significantly lower intraspecific genetic diversity than did C.
occidentalis. Choristoneura orae shared haplotypes with C. occidentalis and
C. biennis, and species-level separation of these three species was not
supported. Two divergent, uncommon haplotypes were also found in C.
occidentalis and C. biennis. The divergent haplotype in C. biennis had an
unusually high number of inferred amino acid replacements, suggesting
selective differences between mitochondrial DNA haplotypes.
Transition:transversion ratios in Choristoneura paralleled those found in
Drosophila; transition:transversion ratios were highest in closely related
sequences but decreased with increasing sequence divergence. Nucleotide
composition showed an A+T bias that was near the high end of the range
known for insects. This work illustrates the potential utility of direct
DNA sequencing in assessing population structures, species limits, and
phylogenetic relationships among organisms that have not previously been
subjected to DNA analysis.
相似文献
504.
505.
O. V. LEDESMA AÍDA P. DE RUIZ HOLGADO G. OLIVER GRACIELA S. DE GIORI P. RAIBAUD J. V. GALPIN 《Journal of applied microbiology》1977,42(1):123-133
The composition of a synthetic medium supporting the growth of lactobacilli is given (Table 1). The medium, containing glucose, amino acids, vitamins, mineral salts, purines and pyrimidines, allows the study of nutritional requirements of different strains of lactobacilli under identical environmental conditions. It was found that all the strains tested needed L-glutamic acid, L-valine and L-leucine, and a group of them also required L-arginine, L-tyrosine and L-tryptophan. Some strains required vitamins, e.g. L. bulgaricus (pantothenic acid), L. fermenti (pantothenic acid and niacin). These results are compared with those found by others employing different media. 相似文献
506.
Dream recall and the physiology of sleep 总被引:1,自引:0,他引:1
507.
508.
Monocaryotization of Cultures of Lenzites trabea (Pers.) Fr. and other Wood-destroying Basidiomycetes 总被引:1,自引:0,他引:1
Cultures of Lenzites trabea and some other basidiomycetes grownon nutrient agar containing high concentrations of sodium arsenateconsistently reverted from the dicaryotic to the monocaryoticcondition. This effect could also be induced by a wide varietyof other toxicants, including copper sulphate, zinc sulphate,sodium dichromate, sodium pentachlorophenate, creosote, crystalviolet, boric acid, and sodium taurocholate, but sodium arsenatewas the most reliable monocaryotizing agent, being effectivewith eight of the fourteen basidio-mycete species tested withit. The neohaplonts formed by sodium arsenate and other toxicantsmate normally with each other and with compatible monosporeisolates. The value of chemical monocaryotization as a techniquein fungal genetics and experimental taxonomy is discussed. Byusing the mating factor alleles as genetic markers, it was demonstratedthat when L. trabea is monocaryo-tized by sodium arsenate orcopper sulphate, only one of the two nuclei in the dicaryoncan be recovered in the neohaplonts, the direction of this completenuclear selection depending on the toxicant and the dicaryonconcerned. It was shown to occur in treated wood blocks duringroutine soil-block decay tests of inorganic wood preservativesand it is probably a frequent, though hitherto unrecognized,occurrence in the laboratory testing of wood preservatives andother fungicides against basidiomycetes. 相似文献
509.
Certain legume crops, including white lupin (Lupinus albus L.), mobilise soil-bound phosphorus (P) through root exudates. The changes in the rhizosphere enhance P availability to these crops, and possibly to subsequent crops growing in the same soil. We conducted a pot experiment to compare phosphorus acquisition of three legume species with that of wheat, and to determine whether the legume crops influence growth and P uptake of a subsequent wheat crop. Field pea (Pisum sativum L.), faba bean (Vicia faba L.), white lupin (Lupinus albus L.) and wheat (Triticum aestivum L.) were grown in three different soils to which we added no or 20 mg P kg–1 soil (P0, P20). Growth, P content and rhizosphere carboxylates varied significantly amongst crops, soils and P levels. Total P content of the plants was increased with applied phosphorus. Phosphorus content of faba bean was 3.9 and 8.8 mg/pot, at P0 and P20, respectively, which was about double that of all other species at the respective P levels. Field pea and white lupin had large amounts of rhizosphere carboxylates, whereas wheat and faba bean had negligible amounts in all three soils at both P levels. Wheat grew better after legumes than after wheat in all three soils. The effect of the previous plant species was greater when these previous species had received P fertiliser. All the legumes increased plant biomass of subsequent wheat significantly over the unplanted pots in all the soils. Faba bean was unparalleled in promoting subsequent wheat growth on all fertilised soils. This experiment clearly demonstrated a residual benefit of the legume crops on the growth of the subsequent wheat crop due to enhanced P uptake. Faba bean appeared to be a suitable P-mobilising legume crop plant for use in rotations with wheat. 相似文献
510.
Morphological and functional aspects of volatile-producing glands in bees (Hymenoptera: Apidae) 总被引:1,自引:0,他引:1
CARMINDA DA CRUZ-LANDIM FÁBIO CAMARGO ABDALLA LUCIANA FIORETTI GRACIOLI-VITTI 《Insect Science》2005,12(6):467-480
Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text. 相似文献