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排序方式: 共有297条查询结果,搜索用时 156 毫秒
121.
Michelle L. Castelletto Spencer S. Gang Ryo P. Okubo Anastassia A. Tselikova Thomas J. Nolan Edward G. Platzer James B. Lok Elissa A. Hallem 《PLoS pathogens》2014,10(8)
Skin-penetrating parasitic nematodes infect approximately one billion people worldwide and are responsible for some of the most common neglected tropical diseases. The infective larvae of skin-penetrating nematodes are thought to search for hosts using sensory cues, yet their host-seeking behavior is poorly understood. We conducted an in-depth analysis of host seeking in the skin-penetrating human parasite Strongyloides stercoralis, and compared its behavior to that of other parasitic nematodes. We found that Str. stercoralis is highly mobile relative to other parasitic nematodes and uses a cruising strategy for finding hosts. Str. stercoralis shows robust attraction to a diverse array of human skin and sweat odorants, most of which are known mosquito attractants. Olfactory preferences of Str. stercoralis vary across life stages, suggesting a mechanism by which host seeking is limited to infective larvae. A comparison of odor-driven behavior in Str. stercoralis and six other nematode species revealed that parasite olfactory preferences reflect host specificity rather than phylogeny, suggesting an important role for olfaction in host selection. Our results may enable the development of new strategies for combating harmful nematode infections. 相似文献
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123.
Few studies have examined how the number and identity of species in the neighbouring community influences the reproductive
success of particular focal species. Pollen delivery, an important component of fitness of sexual plants, is a function of
not just the floral traits of any particular individual, but of features of the population and community as it depends on
pollinator abundance and preferences. Many pollinators in flowering communities will prefer patches with high floral abundance
or diversity yet may exhibit lower floral constancy when more flowering species are present. Thus, pollination efficiency
could increase or decrease with increased species richness and this will alter the selection pressures placed upon the floral
traits (such as floral colour or reward) of any member of a particular community. Moreover, recent studies have indicated
that plant-pollinator networks are phylogenetically structured (pollinators visit related plant species more than expected
by chance) and this may be an important factor structuring flowering plant communities. Thus, the sheer number of species
within a patch may be less important than the number of closely-related species. We investigate whether species richness or
phylogenetic proximity of coflowering species influences the amount and proportion of conspecific pollen delivered to nodding
onion, Allium cernuum, in fragment patches of Garry Oak meadows in South Western British Columbia, Canada. We find that pollen delivery depended
upon the presence of close relatives far more than on species richness or population density, indicating a central role of
the community structure on pollination in flowering plant communities. Insofar as pollen delivery relates to the relative
number of seeds produced by members of the community, pollination may in turn determine the community structure of the next
generation. 相似文献
124.
125.
The misery and suffering caused worldwide by infection with the malaria parasite, especially Plasmodium falciparum, has been well documented. Although no licensed vaccine against malaria currently exists, progress has accelerated in recent years towards the goal of developing one. Although the complexity of the malaria parasite has made the malaria vaccine development process tenuous, advances in science and in the vaccine development process as well as increases in funding are encouraging. These advances, coupled with the results of the recent clinical trial of the vaccine candidate RTS,S, have added new vigor to the idea that a malaria vaccine is not only possible but probable. 相似文献
126.
Koff JL Shao MX Kim S Ueki IF Nadel JA 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(12):8693-8700
The surface of the airway epithelium represents a battleground in which the host intercepts signals from pathogens and activates epithelial defenses to combat infection. Wound repair is an essential function of the airway epithelium in response to injury in chronic airway diseases, and inhaled pathogens such as Pseudomonas bacteria are implicated in the pathobiology of several of these diseases. Because epidermal growth factor receptor (EGFR) activation stimulates wound repair and because LPS activates EGFR, we hypothesized that LPS accelerates wound repair via a surface signaling cascade that causes EGFR phosphorylation. In scrape wounds of NCI-H292 human airway epithelial cells, high concentrations of LPS were toxic and decreased wound repair. However, lower concentrations of LPS accelerated wound repair. This effect was inhibited by treatment with a selective inhibitor of EGFR phosphorylation (AG 1478) and by an EGFR neutralizing Ab. Metalloprotease inhibitors and TNF-alpha-converting enzyme (TACE) small interfering RNA inhibited wound repair, implicating TACE. Additional studies implicated TGF-alpha as the active EGFR ligand cleaved by TACE during wound repair. Reactive oxygen species scavengers, NADPH oxidase inhibitors, and importantly small interfering RNA of dual oxidase 1 inhibited LPS-induced wound repair. Inhibitors of protein kinase C isoforms alphabeta and a TLR-4 neutralizing Ab also inhibited LPS-induced wound repair. Normal human bronchial epithelial cells responded similarly. Thus, LPS accelerates wound repair in airway epithelial cells via a novel TLR-4-->protein kinase C alphabeta-->dual oxidase 1-->reactive oxygen species-->TACE-->TGF-alpha-->EGFR phosphorylation pathway. 相似文献
127.
At the International AIDS Society Conference on Pathogenesis, Treatment and Prevention held in Sydney, Australia, in July 2007, the International AIDS Vaccine Initiative (IAVI) convened a satellite symposium entitled 'Accelerating the Development of Replicating Viral Vectors for AIDS Vaccines.' Its purpose was to highlight the rationale for accelerating the development of replicating viral vectors for use as vaccines against HIV-1, and to bring together vaccine scientists, regulatory officials, and public health specialists from industrialized and developing nations to discuss the major issues facing the development and testing of replicating viral vector-based vaccines. 相似文献
128.
Udita Datta Sarah E. Schoenrock Jason A. Bubier Molly A. Bogue James D. Jentsch Ryan W. Logan Lisa M. Tarantino Elissa J. Chesler 《Genes, Brain & Behavior》2020,19(3)
Despite substantial evidence for sex differences in addiction epidemiology, addiction‐relevant behaviors and associated neurobiological phenomena, the mechanisms and implications of these differences remain unknown. Genetic analysis in model organism is a potentially powerful and effective means of discovering the mechanisms that underlie sex differences in addiction. Human genetic studies are beginning to show precise risk variants that influence the mechanisms of addiction but typically lack sufficient power or neurobiological mechanistic access, particularly for the discovery of the mechanisms that underlie sex differences. Our thesis in this review is that genetic variation in model organisms are a promising approach that can complement these investigations to show the biological mechanisms that underlie sex differences in addiction. 相似文献
129.
Heather R Carstensen Reinard M Villalon Navonil Banerjee Elissa A Hallem Ray L Hong 《Genetics》2021,218(2)
Developmental and behavioral plasticity allow animals to prioritize alternative genetic programs during fluctuating environments. Behavioral remodeling may be acute in animals that interact with host organisms, since reproductive adults and the developmentally arrested larvae often have different ethological needs for chemical stimuli. To understand the genes that coordinate the development and host-seeking behavior, we used the entomophilic nematode Pristionchus pacificus to characterize dauer-constitutive mutants (Daf-c) that inappropriately enter developmental diapause to become dauer larvae. We found two Daf-c loci with dauer-constitutive and cuticle exsheathment phenotypes that can be rescued by the feeding of Δ7-dafachronic acid, and that are dependent on the conserved canonical steroid hormone receptor Ppa-DAF-12. Specifically at one locus, deletions in the sole hydroxysteroid dehydrogenase (HSD) in P. pacificus resulted in Daf-c phenotypes. Ppa-hsd-2 is expressed in the canal-associated neurons (CANs) and excretory cells whose homologous cells in Caenorhabditis elegans are not known to be involved in the dauer decision. While in wildtype only dauer larvae are attracted to host odors, hsd-2 mutant adults show enhanced attraction to the host beetle pheromone, along with ectopic activation of a marker for putative olfactory neurons, Ppa-odr-3. Surprisingly, this enhanced odor attraction acts independently of the Δ7-DA/DAF-12 module, suggesting that Ppa-HSD-2 may be responsible for several steroid hormone products involved in coordinating the dauer decision and host-seeking behavior in P. pacificus. 相似文献
130.
Ian W. Rodger Dorothy Dilar Janet Dwyer John Bienenstock Andu Coret Judith Coret-Simon Gary Foster Arlene Franchetto Slobodan Franic Charles H. Goldsmith David Koff Norman B. Konyer Mitchell Levine Ellen McDonald Michael D. Noseworthy John Paulseth Luciana Ribeiro Mary Jane Sayles Lehana Thabane 《PloS one》2013,8(8)