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101.
Across a large area of the midwestern United States Corn Belt, the western corn rootworm beetle (Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) exhibits behavioral resistance to annual crop rotation. Resistant females exhibit increased locomotor activity and frequently lay eggs in soybean (Glycine max L.) fields, although they also lay eggs in fields of corn (Zea mays L.) and other locations. The goals of this study were (1) to determine whether there were any differences in ovipositional behavior and response to plant cues between individual rotation-resistant and wild-type females in the laboratory and (2) to examine the roles of, and interaction between, host volatiles, diet, and locomotor behavior as they related to oviposition. Because rootworm females lay eggs in the soil, we also examined the influence of host plant roots on behavior. In the first year of the study, rotation-resistant beetles were significantly more likely to lay eggs in the presence of soybean foliage and to feed on soybean leaf discs than wild-type females, but this difference was not observed in the second year. Oviposition by rotation-resistant females was increased in the presence of soybean roots, but soybean herbivory did not affect ovipositional choice. Conversely, ovipositional choice of wild-type females was not affected by the presence or identity of host plant roots encountered, and wild-type females consuming soybean foliage were more likely to lay eggs. 相似文献
102.
ANA PAULA CUTRERA EILEEN A. LACEY MATÍAS S. MORA ENRIQUE P. LESSA 《Biological journal of the Linnean Society. Linnean Society of London》2010,99(2):260-277
To explore the impact of history on selection and genetic structure at functional loci, we compared patterns of major histocompatibility complex (MHC) variability in two sympatric species of ctenomyid rodents with different demographic backgrounds. Although Ctenomys talarum has experienced a stable demographic history, Ctenomys australis has undergone a recent demographic expansion. Accordingly, we predicted that MHC allele frequency distributions should be more skewed, differences between coding and noncoding regions should be less pronounced, and evidence of current selection on MHC loci should be reduced in C. australis relative to C. talarum. To test these predictions, we compared variation at the MHC class II DRB and DQA genes with that at multiple neutral markers, including DQA intron 2, the mitochondrial control region, and 8–12 microsatellite loci. These analyses supported the first two of our predictions but indicated that estimates of selection (based on ω‐values) were greater for C. australis. Further exploration of these data, however, revealed differences in the time frames over which selection appears to have acted on each species, with evidence of contemporary selection on MHC loci being limited to C. talarum. Collectively, these findings indicate that demographic history can substantially influence genetic structure at functional loci and that the effects of history on selection may be temporally complex and dynamic. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 260–277. 相似文献
103.
Genetic footprints of late Quaternary climate change in the diversity of Patagonian‐Fueguian rodents
Species are impacted by climate change at both ecological and evolutionary time scales. Studies in northern continents have provided abundant evidence of dramatic shifts in distributions of species subsequent to the last glacial maximum (LGM), particularly at high latitudes. However, little is known about the history of southern continents, especially at high latitudes. South America is the only continent, other than Antarctica, that extends beyond 40 °S. Genetic studies of a few Patagonian species have provided seemingly conflicting results, indicating either postglacial colonization from restricted glacial refugia or persistence through glacial cycles and in situ differentiation. Using mitochondrial DNA sequences of 14 species of sigmodontine rodents, a major faunal ensemble of Patagonia and Tierra del Fuego, we show that at least nine of these species bear genetic footprints of demographic expansion from single restricted sources. However, timing of demographic expansion precedes the LGM in most of these species. Four species are fragmented phylogeographically within the region. Our results indicate that (i) demographic instability in response to historical climate change has been widespread in the Patagonian‐Fueguian region, and is generally more pronounced at high latitudes in both southern and northern continents; (ii) colonization from lower latitudes is an important component of current Patagonian‐Fueguian diversity; but (iii) in situ differentiation has also contributed to species diversity. 相似文献
104.
Rosângela V Andrade Hugo C Paes André M Nicola Maria José A de Carvalho Ana Lúcia Fachin Renato S Cardoso Simoneide S Silva Larissa Fernandes Silvana P Silva Eduardo A Donadi Elza T Sakamoto-Hojo Geraldo AS Passos Célia MA Soares Marcelo M Brígido Maria Sueli S Felipe 《BMC genomics》2006,7(1):1-13
Background
Bread wheat (Triticum aestivum) is an important staple food. However, wheat gluten proteins cause celiac disease (CD) in 0.5 to 1% of the general population. Among these proteins, the α-gliadins contain several peptides that are associated to the disease.Results
We obtained 230 distinct α-gliadin gene sequences from severaldiploid wheat species representing the ancestral A, B, and D genomes of the hexaploid bread wheat. The large majority of these sequences (87%) contained an internal stop codon. All α-gliadin sequences could be distinguished according to the genome of origin on the basis of sequence similarity, of the average length of the polyglutamine repeats, and of the differences in the presence of four peptides that have been identified as T cell stimulatory epitopes in CD patients through binding to HLA-DQ2/8. By sequence similarity, α-gliadins from the public database of hexaploid T. aestivum could be assigned directly to chromosome 6A, 6B, or 6D. T. monococcum (A genome) sequences, as well as those from chromosome 6A of bread wheat, almost invariably contained epitope glia-α9 and glia-α20, but never the intact epitopes glia-α and glia-α2. A number of sequences from T. speltoides, as well as a number of sequences fromchromosome 6B of bread wheat, did not contain any of the four T cell epitopes screened for. The sequences from T. tauschii (D genome), as well as those from chromosome 6D of bread wheat, were found to contain all of these T cell epitopes in variable combinations per gene. The differences in epitope composition resulted mainly from point mutations. These substitutions appeared to be genome specific.Conclusion
Our analysis shows that α-gliadin sequences from the three genomes of bread wheat form distinct groups. The four known T cell stimulatory epitopes are distributed non-randomly across the sequences, indicating that the three genomes contribute differently to epitope content. A systematic analysis of all known epitopes in gliadins and glutenins will lead to better understanding of the differences in toxiCity among wheat varieties. On the basis of such insight, breeding strategies can be designed to generate less toxic varieties of wheat which may be tolerated by at least part of the CD patient population. 相似文献105.
I. TORRECILLA F. LEGANÉS I. BONILLA & F. FERNÁNDEZ-PIÑAS 《Plant, cell & environment》2004,27(7):810-819
Light‐to‐dark transitions represent one of the most crucial environmental stresses that photosynthetic organisms must cope with, since substantial metabolism adaptations are required in order to utilize alternative energy and carbon sources. Although signal transduction systems for changing light regimes are not sufficiently understood, calcium has been implicated in plants as a second messenger in light‐on and light‐off events. Much less is known about light signalling in cyanobacteria, but it has been shown that calcium probably performs similar signalling roles in these organisms and other prokaryotes. Herein it is reported that light‐to‐dark transitions trigger a calcium transient in aequorin expressing Anabaena sp. PCC7120. The magnitude of this transient depends on the fluence rate previously irradiated and can reach a peak height over 2 µm free calcium when the fluence rate of light is around 400 µmol photons s?1 m?2. The use of increasing calcium concentration, ethylene glycol‐bis (β‐aminoethylether) N,N,N′,N′‐tetraacetic acid (EGTA), verapamil and trifluoperazine indicated that these transients are originated by a calcium influx probably through verapamil‐sensitive Ca2+ channels and are probably modulated by calcium‐binding proteins. Experiments with different light spectral qualities and the photosynthetic inhibitors 3‐(3,4 dichlorophenyl)1,1,dimelthylurea (DCMU) and 3,5‐dibromo‐3‐methyl‐b‐isopropyl‐p‐benzoquinone (DBMIB) indicate that the calcium transient triggered by the light‐to‐dark transition is not coupled to a specific photoreceptor but rather to changes in the redox state of photosynthetic electron transport chain components other than the plastoquinone pool. 相似文献
106.
107.
108.
QUANTITATIVE STUDY OF MITOCHONDRIA IN RAT LIVER : Dry Mass, Wet Mass, Volume, and Concentration of Solids 总被引:3,自引:3,他引:0
The dry mass, wet mass, and volume of mitochondria of normal rat liver were determined, as well as nitrogen content and concentration. A scheme of multiple approaches to these quantities was devised, permitting comparison of values obtained by independent methods. The following basic values are considered highly accurate: Mean dry mass, 13.6 x 10-14 g; mean wet mass, 51.8 x 10-14 g; mean volume, 0.43 µ3; nitrogen content, 1.75 x 10-14 g The work emphasizes the fact that in mitochondria the quantities, mass, and volume occur in logarithmic-normal distributions. 相似文献
109.
110.
Fabian Schnitzler Matthias Friedrich Christiane Wolf Marianne Angelberger Julia Diegelmann Torsten Olszak Florian Beigel Cornelia Tillack Johannes Stallhofer Burkhard G?ke Jürgen Glas Peter Lohse Stephan Brand 《PloS one》2014,9(11)