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71.

Background  

The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum are distinguished by the presence of a tertiary plastid derived from a diatom endosymbiont. The diatom is fully integrated with the host cell cycle and is so altered in structure as to be difficult to recognize it as a diatom, and yet it retains a number of features normally lost in tertiary and secondary endosymbionts, most notably mitochondria. The dinoflagellate host is also reported to retain mitochondrion-like structures, making these cells unique in retaining two evolutionarily distinct mitochondria. This redundancy raises the question of whether the organelles share any functions in common or have distributed functions between them.  相似文献   
72.
Three saponins, named minutoside A (1), minutoside B (2), minutoside C (3), and two known sapogenins, alliogenin and neoagigenin, were isolated from the bulbs of Allium minutiflorum Regel. Elucidation of their structure was carried out by comprehensive spectroscopic analyses, including 2D NMR spectroscopy and mass spectrometry. The structures of the new compounds were identified as (25R)-furost-2alpha,3beta,6beta,22alpha,26-pentaol 3-O-[beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranosyl] 26-O-beta-D-glucopyranoside (1), (25S)-spirostan-2alpha,3beta,6beta-triol 3-O-beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranoside (2), and (25R)-furost-2alpha,3beta,5alpha,6beta,22alpha,26-esaol 3-O-[beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranosyl] 26-O-beta-D-glucopyranoside (3). The isolated compounds were evaluated for their antimicrobial activity. All the novel saponins showed a significant antifungal activity depending on their concentration and with the following rank: minutoside B>minutoside C>minutoside A. No appreciable antibacterial activity was recorded. The possible role of these saponins in plant-microbe interactions is discussed.  相似文献   
73.
The preparation, properties, and application in adriamycin delivery ofbiocompatible and biodegradable poly(lactide-co-glycolide)-polyethylene glycol (PLGA-PEG) nanoparticles are discussed. PLGA-PEG copolymers were synthesized by ring opening polymerization of the dl-lactide and glycolide in the presence of PEG1000. 1H-NMR and FT-IR spectrum were consistent with the structure of PLGA-PEG copolymers. The adriamycin-loaded nanoparticles could be prepared using a precipitation-solvent evaporation technique. The nanoparticles have been produced by a precipitation-solvent evaporation technique. The physical characteristics and drug loading efficiency of the PLGA-PEG nanoparticles were influenced by the composition of the PLGA-PEG copolymers used to prepare the nanoparticles. Particle sizes were between 65 and 100 nm for different compositions of PLGA-PEG copolymers. PLGA-PEG nanoparticles prepared from copolymers having relatively high PLGA/PEG ratios were smaller. Entrapment efficiency was 25%-33%. Adriamycin release from the nanoparticles at pH 7.4 showed an initial burst release and then sustained release phase. These results showed that PLGA-PEG nanoparticles could be an effective carrier for cancer therapy.  相似文献   
74.
Melanoma skin cancer is one of the main causes of male cancer-related deaths worldwide. It has been suggested that miR-330-5p can act as a tumor suppressor in various types of cancers. So, in this study, we replaced miR-330 in melanoma cancer cells by vector-based miR-330 to evaluate the effects of this microRNA on the growth and migration inhibition of melanoma cancer cells, and to determine the molecular mechanisms underlying its action. By using the MTT assay, the IC50 of Geneticin antibiotic was obtained as 460 µg/mL. The results of the qRT-PCR showed the increased expression level of miR-330 and decreased expression levels of MMP-9, CXCR4, Vimentin, melanoma cell adhesion molecule, AKT1, and E2F1 messenger RNA in A375 transfected cells. The cytotoxicity assay results demonstrated the inhibition of cancer cells proliferation. Furthermore, the wound healing test results showed a migration reduction of transfected cells with miR-330 compared with nontransfected ones. In addition, 4′,6-diamidino-2-phenylindoleLB: Luria-Bertani (DAPI) staining revealed the significant nucleus fragmentation in miR-330 replaced cells, which correspond to apoptosis induction in replaced cells. The results showed that increase in miR-330 expression level could significantly inhibit the tumor cell growth and the migration of melanoma cancer cells.  相似文献   
75.
Long non‐coding RNAs (lncRNAs) comprise a vast repertoire of RNAs playing a wide variety of crucial roles in tissue physiology in a cell‐specific manner. Despite being engaged in myriads of regulatory mechanisms, many lncRNAs have still remained to be assigned any functions. A constellation of experimental techniques including single‐molecule RNA in situ hybridization (sm‐RNA FISH), cross‐linking and immunoprecipitation (CLIP), RNA interference (RNAi), Clustered regularly interspaced short palindromic repeats (CRISPR) and so forth has been employed to shed light on lncRNA cellular localization, structure, interaction networks and functions. Here, we review these and other experimental approaches in common use for identification and characterization of lncRNAs, particularly those involved in different types of cancer, with focus on merits and demerits of each technique.  相似文献   
76.
Salmonella organisms of an unknown serotype are inoculated in the center of a motility agar plate, and paper discs impregnated with antiflagellar antisera are placed in the periphery of the plate. The plate is incubated at room temperature overnight. During this time, the bacteria spread in a widening circle toward the discs, while the antiserum from each disc, in turn, diffuses centrifugally. When the motile organisms encounter an antiserum reacting with their flagella, they are immobilized. A semicircular line of immobilization is noted around the reactive antiserum disc. Eleven different Salmonella isolates were typed in duplicate by a standard method and by the immuno-immobilization method. Results obtained by the two methods were essentially identical. Simultaneously, single phases were isolated from the zone between the immobilization line and its antiserum disc. Isolates from this region were of the phase not immobilized by the antiserum disc. The dried discs, prepared in tris(hydroxymethyl)aminomethane buffer and stored at 4 C, were stable for at least 5 months. The method can be used for the study of relatedness of surface antigens of motile, growing bacteria, thus circumventing the need for solubilization of these antigens. The results obtained can be interpreted in a similar fashion to the “identity”-“nonidentity” lines of the Ochterlony double-diffusion technique for soluble antigens.  相似文献   
77.
Zinc deficiency is a critical nutritional problem in soils, restricting yield and nutritional quality of barley (Hordeum vulgare L.). Some genotypes (Zn-efficient) can produce greater yield and accumulate more Zn in seed under Zn deficiency than standard (Zn-inefficient) genotypes. However, there is little information regarding the genetics of Zn uptake/accumulation and location of genes conferring Zn efficiency in barley. Selection through molecular markers for seed Zn accumulation might be an efficient complementary breeding tool in barley. With the aim of developing molecular markers for increased accumulation of Zn in seed, a population of 150 DH lines derived from a cross between Clipper (low-Zn-accumulator) and Sahara 3771 (high-Zn-accumulator) was screened in the field and glasshouse for seed Zn concentration and content. One dominant DNA polymorphism was detected using the microsatellite-anchored fragment length polymorphism (MFLP) technique. The candidate MFLP marker was isolated from the MFLP gel, re-amplified by PCR, cloned, sequenced, and converted into simple sequence-specific and PCR-based marker. This marker, located on the short arm of chromosome 2H, might be useful for the improvement of barley nutritional quality and productivity programs in Zn-deficient environments. However, high seed Zn alone can not replace the need for Zn fertilization.  相似文献   
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80.
Marine oil spills are catastrophic events that cause massive damage to ecosystems at all trophic levels. While most of the research has focused on carbon-degrading microorganisms, the potential impacts of hydrocarbons on microbes responsible for nitrification have received far less attention. Nitrifiers are sensitive to hydrocarbon toxicity: ammonia-oxidizing bacteria and archaea being 100 and 1000 times more sensitive than typical heterotrophs respectively. Field studies have demonstrated the response of nitrifiers to hydrocarbons is highly variable and the loss of nitrification activity in coastal ecosystems can be restored within 1–2 years, which is much shorter than the typical recovery time of whole ecosystems (e.g., up to 20 years). Since the denitrification process is mainly driven by heterotrophs, which are more resistant to hydrocarbon toxicity than nitrifiers, the inhibition of nitrification may slow down the nitrogen turnover and increase ammonia availability, which supports the growth of oil-degrading heterotrophs and possibly various phototrophs. A better understanding of the ecological response of nitrification is paramount in predicting impacts of oil spills on the nitrogen cycle under oil spill conditions, and in improving current bioremediation practices.  相似文献   
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