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101.
Strain diversity and host specificity in a specialized gut symbiont of honeybees and bumblebees 下载免费PDF全文
Host‐restricted lineages of gut bacteria often include many closely related strains, but this fine‐scale diversity is rarely investigated. The specialized gut symbiont Snodgrassella alvi has codiversified with honeybees (Apis mellifera) and bumblebees (Bombus) for millions of years. Snodgrassella alvi strains are nearly identical for 16S rRNA gene sequences but have distinct gene repertoires potentially affecting host biology and community interactions. We examined S. alvi strain diversity within and between hosts using deep sequencing both of a single‐copy coding gene (minD) and of the V4 region of the 16S rRNA gene. We sampled workers from domestic and feral A. mellifera colonies and wild‐caught Bombus representing 14 species. Conventional analyses of community profiles, based on the V4 region of the 16S rRNA gene, failed to expose most strain variation. In contrast, the minD analysis revealed extensive strain variation within and between host species and individuals. Snodgrassella alvi strain diversity is significantly higher in A. mellifera than in Bombus, supporting the hypothesis that colony founding by swarms of workers enables retention of more diversity than colony founding by a single queen. Most Bombus individuals (72%) are dominated by a single S. alvi strain, whereas most A. mellifera (86%) possess multiple strains. No S. alvi strains are shared between A. mellifera and Bombus, indicating some host specificity. Among Bombus‐restricted strains, some are restricted to a single host species or subgenus, while others occur in multiple subgenera. Findings demonstrate that strains diversify both within and between host species and can be highly specific or relatively generalized in their host associations. 相似文献
102.
Hilaire Kpongbe Johnnie Van den Berg Fathiya Khamis Manuele Tam Elijah Jacob Talamas Baldwyn Torto 《Journal of Applied Entomology》2019,143(8):842-854
Clavigralla spp. (Hemiptera: Coreidae) are major pests of cowpea (Vigna unguiculata (L.) Walp, Fabacae), common bean (Phaseolus vulgaris L., Fabacae) and pigeon pea (Cajanus cajan L., Fabacae) in Africa. Clavigralla spp. egg parasitoids, Gryon spp. (Hymenoptera: Scelionidae), have previously been reported as potential biological control candidates. Little is known about the parasitism levels and their potential relationship with cuticular chemistry of Clavigralla spp. The aims of this study were to determine parasitism levels of Clavigralla tomentosicollis Stål (Hemiptera: Coreidae) and C. elongata Signoret (Hemiptera: Coreidae) eggs, and to explore the relationship between egg parasitism and egg cuticular chemistry. High parasitism levels were determined for C. tomentosicollis by collecting eggs from plants in mono‐cropping and multi‐cropping systems in farmers’ fields in Bénin and Kenya between April and June 2016. Three species of Clavigralla were recorded: C. tomentosicollis, C. shadabi and C. elongata. Clavigralla tomentosicollis was the most common in both countries, while C. shadabi and C. elongata were only collected in Bénin and Kenya, respectively. An egg parasitoid (Gryon sp.) was recovered from egg batches collected from both countries. In parasitism assays using Gryon sp., the incidence of parasitism was higher in C. tomentosicollis eggs than that of C. elongata. Chemical analysis by coupled gas chromatography/mass spectrometry (GC/MS) of cuticular extracts obtained from C. tomentosicollis and C. elongata eggs identified fifteen compounds including ten alkanes of which the amounts varied between the two species. We speculate that Clavigralla spp. cuticular chemistry may serve as potential host location cues for Gryon sp. 相似文献
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The cell of Pyrocystis spp. is covered by an outer layer of material resistant to strong acids and bases. Internal to this layer much of the cell wall is composed of cellulose fibrils. The presence of cellulose fibrils was established by staining raw and ultra-violet–peroxide-cleaned cell walls and by combining X-ray diffraction spectroscopy with electron microscope observation. Carbon replicas of freeze-etched preparations and thin sections of P. lunula walls show outer layers, inside them ca. 24 layers of crossed parallel cellulose fibrils (4–5 nm thick, ca. 12 nm wide), then a region of smaller (ca. 6–12 nm diameter) fibrils in a disperse texture, and then the plasma membrane. Cellulose fibrils in the parallel texture are constructed of 3–5 elementary fibrils ca. 3 nm in diameter. Walls of P. fusiformis and P. pseudonctiluca also have cellulose fibrils in a crossed parallel texture similar to those of P. lunula. The Gymnodinium-type swarmer from lunate P. lunula appears to have a cell wall ultrastructure typical of other “naked” dinoflagellates. 相似文献
105.
Phosphate uptake by P-replete and P-depleted Pyrocystis noctiluca (Murray) Schütt grown at different ambient N:P ratios was multiphasic between 0.1 and 100 μM PO43-. Within each of the kinetic phases, the saturated uptake rate (Vmax), but not the half saturation constant (Km) was affected by the cellular-P status and light. Uptake rates in the dark were ca. 50% of that in the light and respiratory activity accounted for the observed basal uptake. The combination of multiphasic uptake, and the uncoupling of short term transient uptake from growth resulting in maximum specific uptake rates of 50 h?1 may help explain the abundance of P. noctiluca in oligotrophic regions. 相似文献
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Dana Praslickova Enrique C. Torchia Michael G. Sugiyama Elijah J. Magrane Brittnee L. Zwicker Lev Kolodzieyski Luis B. Agellon 《PloS one》2012,7(12)
The ileal lipid binding protein (ilbp) is a cytoplasmic protein that binds bile acids with high affinity. However evidence demonstrating the role of this protein in bile acid transport and homeostasis is missing. We created a mouse strain lacking ilbp (Fabp6−/− mice) and assessed the impact of ilbp deficiency on bile acid homeostasis and transport in vivo. Elimination of ilbp increased fecal bile acid excretion (54.2%, P<0.05) in female but not male Fabp6−/− mice. The activity of cholesterol 7α-hydroxylase (cyp7a1), the rate-controlling enzyme of the classical bile acid biosynthetic pathway, was significantly increased in female (63.5%, P<0.05) but not in male Fabp6−/− mice. The amount of [3H]taurocholic acid (TCA) excreted by 24 h after oral administration was 102% (P<0.025) higher for female Fabp6−/− mice whereas it was 57.3% (P<0.01) lower for male Fabp6−/− mice, compared to wild-type mice. The retained fraction of the [3H]TCA localized in the small and large intestines was increased by 22% (P<0.02) and decreased by 62.7% (P<0.01), respectively, in male Fabp6−/− mice relative wild-type mice, whereas no changes were seen in female Fabp6−/− mice. Mucosal to serosal bile acid transport using everted distal gut sacs was decreased by 74% (P<0.03) in both sexes of Fabp6−/− mice as compared to wild-type mice. The results demonstrate that ilbp is involved in the apical to basolateral transport of bile acids in ileal enterocytes, and is vital for the maintenance of bile acid homeostasis in the enterohepatic circulation (EHC) in mice. 相似文献
108.
Schistosomes are parasitic blood flukes that reside in human mesenteric veins or urinary bladder veins, depending on species of the parasite. The syncytial tegument of these parasites represents a dynamic interface that regulates nutritional and immunological interactions between the parasite and the host. It is known that the components for biogenesis and maintenance of the tegument are supplied via vesicles from the nucleated cell bodies beneath the syncytium and muscle layer. To investigate the common motor components of vesicular transport in the tegument of schistomes, we extracted Schistosoma mansoni tegumental microtubule associated proteins utilizing detergent/high-salt procedure and raised antiserum against these proteins. The antiserum was applied to screen Schistosoma haematobium λgt11 expression library and some of the isolated clones were sequenced. Blast search for the sequences against NCBI database identified clones that are dynein light chains and myosin genes. Further analysis of schistosome dynein genes in the databases identified three families of dynein light chains (Dlcs). The Tctex family protein sequences are significantly different from the mammalian homologs and, therefore, offer a potential vaccine/drug target against schistosomes. 相似文献
109.
A genual pattern of photophobic responses has been observedwhich differs for calanoid copepods from freshwater, estuarineand oceanic environments. Using a video-computer system formotion analysis, the photophobic responses of light and darkadapted calanoid copepods were compared. Dark-adapted copepodswere exposed to 600 ms flashes of dim blue light at 5 s intervalswhich simulated the flashes of biolumines-cent marine zooplankton.Light-adapted copepods were exposed to 600 ms intervals of darknessat 5 s intervals to simulate the shadows of organisms passingoverhead. Four species of coastal marine copepods (Acartia hudsonica,Centropages hamatus, Pseudocalanus minutus and Temora longicornis)all showed photophobic responses to both flashes and shadows.These responses may have adaptive value to the copepods sincethey live in an environment with predators that are bioluminescentat night and cast shadows on their prey during the day (e.g.ctenophores and cnidarian medusae). Two species of oceanic copepods(Euchaeta marina, Pleuromamma abdominalis) showed strong photophobicresponses to flashes but no response to shadows. This may correspondto the abundance of bioluminescent predators on copepods inthe oceanic environment (fish, ctenophores, siphonophores, etc.)and their lack of exposure to the shadows of predators, sinceboth these species are rarely found in the euphoric zone duringthe day. Two species of freshwater copepods (Diaptomus sanguineus,Epishwa massachusettsensis) showed no similar photophobic responseto flashes of light. This lack of startle response may relateto the lack of bioluminescence in the freshwater environment.Freshwater copepods showed a weak photophobic response to shadows.The adaptive value of this behavior is unclear, however, sincethe responses seem to be too weak to function for escape, andthe dominant predators large enough to cast shadows (fish) tendto approach their prey laterally.
1Present address: Marine Science Institute, University of Texasat Austin, Port Aransas, TX 783731267, USA 相似文献
110.
Melissa B. Manus Elijah Watson Sahana Kuthyar Delia Carba Nikola M. Belarmino Thomas W. McDade Christopher W. Kuzawa Katherine R. Amato 《American journal of physical anthropology》2023,181(1):45-58