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111.
112.
Background
Milkweeds (Asclepias L.) have been extensively investigated in diverse areas of evolutionary biology and ecology; however, there are few genetic resources available to facilitate and compliment these studies. This study explored how low coverage genome sequencing of the common milkweed (Asclepias syriaca L.) could be useful in characterizing the genome of a plant without prior genomic information and for development of genomic resources as a step toward further developing A. syriaca as a model in ecology and evolution.Results
A 0.5× genome of A. syriaca was produced using Illumina sequencing. A virtually complete chloroplast genome of 158,598 bp was assembled, revealing few repeats and loss of three genes: accD, clpP, and ycf1. A nearly complete rDNA cistron (18S-5.8S-26S; 7,541 bp) and 5S rDNA (120 bp) sequence were obtained. Assessment of polymorphism revealed that the rDNA cistron and 5S rDNA had 0.3% and 26.7% polymorphic sites, respectively. A partial mitochondrial genome sequence (130,764 bp), with identical gene content to tobacco, was also assembled. An initial characterization of repeat content indicated that Ty1/copia-like retroelements are the most common repeat type in the milkweed genome. At least one A. syriaca microread hit 88% of Catharanthus roseus (Apocynaceae) unigenes (median coverage of 0.29×) and 66% of single copy orthologs (COSII) in asterids (median coverage of 0.14×). From this partial characterization of the A. syriaca genome, markers for population genetics (microsatellites) and phylogenetics (low-copy nuclear genes) studies were developed.Conclusions
The results highlight the promise of next generation sequencing for development of genomic resources for any organism. Low coverage genome sequencing allows characterization of the high copy fraction of the genome and exploration of the low copy fraction of the genome, which facilitate the development of molecular tools for further study of a target species and its relatives. This study represents a first step in the development of a community resource for further study of plant-insect co-evolution, anti-herbivore defense, floral developmental genetics, reproductive biology, chemical evolution, population genetics, and comparative genomics using milkweeds, and A. syriaca in particular, as ecological and evolutionary models. 相似文献113.
Synovial tissue of patients with rheumatoid arthritis (RA) spontaneously produces several cytokines, of which a fundamental
role in joint inflammation and destruction has been established. However, the factors sustaining this phenomenon remain poorly
understood. In a recent report, blockade of Toll-like receptor 2 (TLR2) was found to inhibit the spontaneous release of inflammatory
cytokines by intact RA synovial explant cultures. Adding to the recent evidence implicating other TLRs (in particular, TLR4),
this observation highlights the potential of TLRs as therapeutic targets to suppress the local production of multiple cytokines
and to control the chronic inflammatory loop in RA. 相似文献
114.
115.
Marcin Czarnoleski Katarzyna Pawlik Pawe? Olejniczak Jan Koz?owski Marlena Lembicz 《Plant Ecology》2012,213(6):1049-1053
The interactions of endophytes with plants are believed to evolve over time from parasitic to mutualistic, and in the seed-transmitted fungal endophytes, these interactions are conventionally treated as mutualistic. The weeping alkaligrass Puccinellia distans has recently dispersed to new habitats in Europe, where it was colonised by the seed-transmitted fungus Epichlo? typhina. The E. typhina-infected weeping alkaligrass has a fertility advantage over -uninfected plants, but this advantage is held only over shorter time scales. We assess the antiherbivore value of E. typhina in mature weeping alkaligrass against common voles Microtus arvalis, a herbivore naturally co-occurring with weeping alkaligrass. In two consecutive food-choice tests conducted in a lab, we examined feeding by na?ve voles on E. typhina-infected (E+) and -uninfected grass (E?) originating from Central Europe. In the first test, all voles consumed comparable amounts of E+ biomass and E? biomass. In the subsequent test, the voles reduced their feeding rates by 57?%, but E+ food was avoided twice as frequently as E? food (75 vs. 33?% reduction). This result suggests that toxins produced by E. typhina repel herbivores soon after the first contact. We show that in addition to its direct fitness consequences, endophyte-mediated resistance to herbivory increases the fertility advantage of E. typhina-infected weeping alkaligrass. This effect can increase the ability of weeping alkaligrass to invade habitats with intense herbivory. 相似文献
116.
Blickwedehl J Olejniczak S Cummings R Sarvaiya N Mantilla A Chanan-Khan A Pandita TK Schmidt M Thompson CB Bangia N 《Molecular cancer research : MCR》2012,10(7):937-944
The cellular response to ionizing radiation (IR) involves a variety of mechanisms to repair damage and maintain cell survival. We previously reported that the proteasome activator PA200 promotes long-term cell survival after IR exposure. The molecular function of PA200 is to enhance proteasome-mediated cleavage after glutamate; however, it is not known how this molecular function promotes survival after IR exposure. Here, we report that upon IR exposure, cellular demand for exogenous glutamine is increased. Cells containing PA200 are capable of surviving this IR-induced glutamine demand, whereas PA200-deficient cells show impaired long-term survival. Additional glutamine supplementation reverses the radiosensitivity of PA200-knockdown cells suggesting impaired glutamine homeostasis in these cells. Indeed, PA200-knockdown cells are unable to maintain intracellular glutamine levels. Furthermore, when extracellular glutamine is limiting, cells that contain PA200 respond by slowing growth, but PA200-knockdown cells and cells in which post-glutamyl proteasome activity is inhibited are nonresponsive and continue rapid growth. This cellular unresponsiveness to nutrient depletion is also reflected at the level of the mTOR substrate ribosomal S6 kinase (S6K). Thus, inability to restrict growth causes PA200-deficient cells to continue growing and eventually die due to lack of available glutamine. Together, these data indicate an important role for PA200 and post-glutamyl proteasome activity in maintaining glutamine homeostasis, which appears to be especially important for long-term survival of tumor cells after radiation exposure. 相似文献
117.
118.
Agnieszka M. Bogdanowicz Paweł Olejniczak Marlena Lembicz Waldemar Żukowski 《Central European Journal of Biology》2011,6(5):870-877
We tested a hypothesis based on life history theory that examines reproductive costs incurred by individuals in consecutive
years of their life. A multi-year dataset of resource allocation to vegetative and reproductive structures was analysed in
Carex secalina — a perennial, monoecious sedge, reproducing only sexually. In a four-year garden experiment, we assessed above-ground biomass
at the end of each season and reproductive allocation expressed as the total length of male and female spikes. The study was
aimed at determining how size and age of a plant relates to its reproduction, and how the rate of reproduction affects the
year-toyear biomass change in Carex secalina. We observed that after each reproductive episode, individuals had significantly smaller sizes and produced a lower number
of generative tillers. The total production of reproductive structures decreased significantly with age in all populations.
Moreover, the decrease in plant biomass was greater when more reproductive structures were produced in a previous year, which
indicates that the plants incur costs of reproduction in terms of above-ground biomass production. 相似文献
119.
F C Rodrigues AJ JúniorHojaij I L Calvo C F de Carvalho 《Gegenbaurs morphologisches Jahrbuch》1987,133(4):665-672
50 dissections of the human inferior V. cava have been performed in order to measure its right renal vein - diaphragm, retrohepatic, and suprahepatic segments. We conclude that some individual parameters as skin type, age, height, weight did not influence the magnitude of the studied segments. The average measurements of the different parameters proposed for the inferior V. cava are: 1. The distances between the right renal vein and the diaphragm and between the right renal vein and the right atrium are 113.94 mm and 135.16 mm, respectively; 2. the length of the retrohepatic portion of the inferior V. cava and the suprahepatic one were 78.34 mm and 19.34 mm respectively; 3. the valve of the inferior V. cava is present in 46% of the observations; its length and width averages are 31 mm and 10.22 mm, respectively. 相似文献
120.
Smith TM Olejniczak AJ Reh S Reid DJ Hublin JJ 《American journal of physical anthropology》2008,136(2):237-241
In addition to evidence for bipedality in some fossil taxa, molar enamel thickness is among the few characters distinguishing (thick-enameled) hominins from the (thin-enameled) African apes. Despite the importance of enamel thickness in taxonomic discussions and a long history of scholarship, measurements of enamel thickness are performed almost exclusively on molars, with relatively few studies examining premolars and anterior teeth. This focus on molars has limited the scope of enamel thickness studies (i.e., there exist many fossil hominin incisors, canines, and premolars). Increasing the available sample of teeth from which to compare enamel thickness measurements from the fossil record could substantially increase our understanding of this aspect of dental biology, and perhaps facilitate greater taxonomic resolution of early hominin fossils. In this study, we report absolute and relative (size-scaled) enamel thickness measurements for the complete dentition of modern humans and chimpanzees. In accord with previous studies of molars, chimpanzees show lower relative enamel thickness at each tooth position, with little overlap between the two taxa. A significant trend of increasing enamel thickness from anterior to posterior teeth is apparent in both humans and chimpanzees, indicating that inter-taxon comparisons should be limited to the same tooth position in order to compare homologous structures. As nondestructive imaging techniques become commonplace (facilitating the examination of increasing numbers of fossil specimens), studies may maximize available samples by expanding beyond molars. 相似文献