|
|
×îºóÁ½¶Î
¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ¡ï ... xu_0501(½ð±Ò+300,VIP+0):thank you very much
The results suggest that in two species of Lepidoptera, cadherin receptor
protein in the larval midgut mediates the toxicity of Cry1A toxins by
facilitating removal of helix a-1, which promotes toxin oligomerization.
½á¹û±íÃ÷£¬ÔÚ2ÖÖÁÛ³áÄ¿À¥³æÖУ¬¸ÆÕ³µ°°×ÊÜÌåµ°°×Ôڽ鵼Ó׳æÖг¦Cry1A¶¾Ëص;ÐÔ£¬´Ù½øÏû³ý¦Á-1ÂÝÐý£¬´Ó¶ø´Ù½ø¶¾ËعѾۻ¯¡£
The modified toxins Cry1AbMod and Cry1AcMod lacking helix ¦Á-1 formed oligomers in vitro without cadherin, whereas native Cry1Ab and Cry1Ac did not.
Ð޸ĺóµÄ¶¾ËØCry1AbModºÍCry1AcModȱ·¦¦Á - 1 ÂÝÐý£¬ÔÚÌåÍâÐγɵ;ÛÎïÎÞ¸ÆÕ³µ°°×£¬¶øÌìÈ»Cry1AbºÍCry1AcÔÚÌåÍâÐγɵ;ÛÎïÓиÆÕ³µ°°×¡£
The modified toxins killed insects with greatly reduced susceptibility to
native Cry1A toxins caused by RNAi silencing of the cadherin gene or by mutations in the cadherin gene.
Ð޸ĺóµÄ¶¾ËØÉ±ËÀÀ¥³æµÄͬʱ´ó´ó½µµÍÌìÈ»Cry1A¶¾ËظÐÐÔ£¬ÕâÖÖ½µµÍÊÇÓÉÀ¥³æÊÊÓ¦ÐÔµÄRNAi³ÁĬ»ò»ùÒòÍ»±ä¸ÆÕ³µ°°×µÄ»ùÒò¡£
These results support the pore-formation model (15) and not the signaling
model, which does not include removal of helix a-1 or toxin oligomerization
.
ÕâЩ½á¹ûÖ§³Ö¿×϶ÐγÉÄ£ÐÍ£¬¶ø²»ÊÇÐźÅÄ£ÐÍ£¬ÆäÖв»°üÀ¨Ïû³ýÂÝÐý¼¶»ò¶¾Ëص;ۻ¯¡£
If the results seen here with the pink bollworm extend to other lepidopterans,Cry1AbMod and Cry1AcMod could be broadly useful for countering or delaying pest resistance to Cry1A toxins.
Èç¹ûÔÚÕâÀï¿´µ½µÄ½á¹û£¬ÄÜ´ÓºìÁ峿À©Õ¹µ½ÆäËûÁÛ³áÀàÀ¥³æ £¬Cry1AbModºÍCry1AcMod´óÖ¿ÉÓÃÓÚ½â¾ö»òÍÆ³Ùº¦³æ¶ÔCry1A¶¾ËØ¿¹Ò©ÐÔ¡£
However, we do not know whether Cry1AMod toxins kill insects with mechanisms of resistance unrelated to cadherin, such as the disruption of other receptors or decreased protease activation.
È»¶ø£¬ÎÒÃDz»ÖªµÀCry1AMod¶¾ËØÉ±ËÀº¦³æµÄ¿¹ÐÔ»úÖÆÊÇ·ñºÍ¸ÆÕ³µ°°×Î޹أ¬ÈçÆäËûÊÜÌåµ°°×ø¼¤»îµÄÖжϻò¼õÉÙ¡£
Many Bt toxins have structural topology similar to Cry1A, form oligomers, and
induce pores, suggesting that they share a similar mode of action.
Bt¶¾ËغÍCry1AÓÐÐí¶àÏàËÆÈçÍØÆË½á¹¹ £¬ÔÚÐγɵ;ÛÎï¼°ÓÕµ¼¿Õ϶µÄ¹ý³Ì£¬Õâ±íÃ÷ËüÃǾßÓÐÀàËÆµÄ×÷Ó÷½Ê½¡£
It remains to be determined whether, parallel to results with Cry1A toxins,
other Cry toxins lacking helix a-1 can kill resistant insects that have altered
receptors.
Cry1A¶¾ËØÓëÆäËûȱ·¦¦Á-1ÂÝÐýµÄÄܹ»É±ËÀ¸Ä±äÊÜÌåÇÒ¾ßÓп¹ÐÔµÄÀ¥³æµÄCry¶¾Ëؽá¹ûÊÇ·ñƽÐл¹ÓдýÈ·¶¨¡£
In addition, insects can probably evolve resistance to modified Bt toxins
lacking helix a-1.
´ËÍ⣬À¥³æ¿ÉÄÜÑݱä³öµÖ¿¹Ð޸ĵÄȱ·¦¦Á-1ÂÝÐýµÄBt¶¾ËØÆ·Ïµ¡£
Nonetheless, along with native Bt toxins such as Cry2 and Vip3 that have not been used as extensively as Cry1A toxins, the modified toxins broaden the options for pest control.
È»¶ø£¬Ëæ×ÅÒ°ÉúÐÍBt¶¾ËØ£¬ÈçCry2ºÍVip3»¹Ã»Óб»ÓÃÀ´×÷Ϊ¹ã·ºµÄCry1A¶¾ËØ£¬À©´óÁ˶¾ËصÄÐÞ¸ÄÑ¡Ôñ·¶Î§À´¿ØÖƳ溦¡£
[ Last edited by caitikuan on 2009-1-15 at 15:35 ] |
|