In cancer [1,2] and animal research [3,4]. It was shown to be a powerful method for gene function analysis in the medical sciences [5]. Recently, use of a nanoparticle delivery system has helped A-ODN function more effectively [6]. It was proposed that designing 12225-nucleotide sequences complementary to the mRNA of a target gene would cause RNase H cleavage, inhibiting target gene mRNA transcription [7] or forming a complex to block translation [8] and would be more targetspecific, greatly reducing or eliminating off-target effects. RNA interference (RNAi) is a widely used method for gene silencing. It is particularly useful in species in which the genetic background is not yet well-understood, although it has also attracted criticism because of possible off-target effects [9211]. Compared to RNAi, A-ODN may provide more effective inhibition [12] and the effect of A-ODN is usually 194423-15-9 biological activity faster due to omission of plasmid INCB039110 supplier construction [13]. Furthermore, chemical modifications of A-ODN, such as PS modification (phosphorothioate modification), make its application more stable [14,15]. Thus, A-ODN inhibition is potentially a powerful technique for gene silencing. In addition, compared to mutation techniques, AODN is uniquely advantageous because it is able to transiently downregulate gene expression for the analysis of gene function in 
specific developmental phases or plant organs. In fact, examples of A-ODN application have been reported in various plants [12,16?19]. However, basic questions such as whether naked or nanoparticle-packed A-ODNs are more effective, or how ODN permeate the plant cell membrane, remains unclear. Recent evidence suggests that A-ODNs enter the cell via endocytosis or other vesicle trafficking [20,21], with evidence of receptormediated endocytosis [22]. However, more research is needed to elucidate the mechanism of A-ODN action within the cell to understand the details of how it functions. The Arf family of guanine-nucleotide-binding (G) proteins and ARF-guanine exchange factors (ARF-GEFs) play crucial roles in vesicle trafficking [23,24]. Large ARF-GEFs activate ARF-GTP by exchanging GDP for GTP and thus interact with some effectors, regulating diverse events in vesicle trafficking [25229]. We identified NtGNL1 in tobacco and, using the RNAi technique, confirmed its essential role in 10457188 pollen tube growth [30,31]. Cytological observations indicated that the down-regulation of NtGNL1 resulted in abnormal post-Golgi trafficking [31]. Based on this detailed background, NtGNL1 could be a useful target gene for evaluating the A-ODN technique in plant cells.Antisense ODN Inhibition in Pollen TubesFigure 1. Tracing the uptake of antisense ODN into pollen tubes. A: Tracing the uptake of FL-ODNs. FL-ODNs signal appeared as small dots in pollen tubes after 1 hour’s incubation (a). After 2 hours’ incubation, the signal concentrated at the tip of the pollen tube (b) and finally dispersed evenly throughout the entire pollen tube after 3 hour’s incubation (c). a Bar = 20 mm. B: Pulse-chasing labeling with fluorescence-labeled ODNs and FM4-64. (a) Bright field image of the pollen tube. (b) The image show the same pollen tube labeled with Alexa Fluor 488 fluorescence. (c) The image show the same pollen tube labeled with FM4-64 fluorescence. (d) Pulse-chase labeling with Alexa Fluor 488 for 3 h followed by FM4-64 for 10 min. 26001275 Squares (e ) indicate areas magnified in (d), respectively. Bar = 20 mm in (a ); bar = 10 mm in (e ). n = 15?0 for.In cancer [1,2] and animal research [3,4]. It was shown to be a powerful method for gene function analysis in the medical sciences [5]. Recently, use of a nanoparticle delivery system has helped A-ODN function more effectively [6]. It was proposed that designing 12225-nucleotide sequences complementary to the mRNA of a target gene would cause RNase H cleavage, inhibiting target gene mRNA transcription [7] or forming a complex to block translation [8] and would be more targetspecific, greatly reducing or eliminating off-target effects. RNA interference (RNAi) is a widely used method for gene silencing. It is particularly useful in species in which the genetic background is not yet well-understood, although it has also attracted criticism because of possible off-target effects [9211]. Compared to RNAi, A-ODN may provide more effective inhibition [12] and the effect of A-ODN is usually faster due to omission of plasmid construction [13]. Furthermore, chemical modifications of A-ODN, such as PS modification (phosphorothioate modification), make its application more stable [14,15]. Thus, A-ODN inhibition is potentially a powerful technique for gene silencing. In addition, compared to mutation techniques, AODN is uniquely advantageous because it is able to transiently downregulate gene expression for the analysis of gene function in specific developmental phases or plant organs. In fact, examples of A-ODN application have been reported in various plants [12,16?19]. However, basic questions such as whether naked or nanoparticle-packed A-ODNs are more effective, or how ODN permeate the plant cell membrane, remains unclear. Recent evidence suggests that A-ODNs enter the cell via endocytosis or other vesicle trafficking [20,21], with evidence of receptormediated endocytosis [22]. However, more research is needed to elucidate the mechanism of A-ODN action within the cell to understand the details of how it functions. The Arf family of guanine-nucleotide-binding (G) proteins and ARF-guanine exchange factors (ARF-GEFs) play crucial roles in vesicle trafficking [23,24]. Large 
ARF-GEFs activate ARF-GTP by exchanging GDP for GTP and thus interact with some effectors, regulating diverse events in vesicle trafficking [25229]. We identified NtGNL1 in tobacco and, using the RNAi technique, confirmed its essential role in 10457188 pollen tube growth [30,31]. Cytological observations indicated that the down-regulation of NtGNL1 resulted in abnormal post-Golgi trafficking [31]. Based on this detailed background, NtGNL1 could be a useful target gene for evaluating the A-ODN technique in plant cells.Antisense ODN Inhibition in Pollen TubesFigure 1. Tracing the uptake of antisense ODN into pollen tubes. A: Tracing the uptake of FL-ODNs. FL-ODNs signal appeared as small dots in pollen tubes after 1 hour’s incubation (a). After 2 hours’ incubation, the signal concentrated at the tip of the pollen tube (b) and finally dispersed evenly throughout the entire pollen tube after 3 hour’s incubation (c). a Bar = 20 mm. B: Pulse-chasing labeling with fluorescence-labeled ODNs and FM4-64. (a) Bright field image of the pollen tube. (b) The image show the same pollen tube labeled with Alexa Fluor 488 fluorescence. (c) The image show the same pollen tube labeled with FM4-64 fluorescence. (d) Pulse-chase labeling with Alexa Fluor 488 for 3 h followed by FM4-64 for 10 min. 26001275 Squares (e ) indicate areas magnified in (d), respectively. Bar = 20 mm in (a ); bar = 10 mm in (e ). n = 15?0 for.