The objective was to visualize a variety of marine bacteriophage and identify unique structural features that set them apart from terrestrial phages. Phages were plaque isolated and characterized using atomic force mi...The objective was to visualize a variety of marine bacteriophage and identify unique structural features that set them apart from terrestrial phages. Phages were plaque isolated and characterized using atomic force microscopy. Bacteriophage infecting cyanobacteria synechococcus that exhibits a novel structural feature not previously reported for any other phages were observed. These cyanophages have up to four, 450 nm long, multi-stranded, complex helical fibers that emanate from either the base plate and/or the collar of the phage particle, origins of shorter fibers on well-studied phages such as T4. The flexible fibers terminate at their distal ends in multiple bulbs of diameter 30 nm composed of 20 to 30 closely associated proteins. Bulbs form one of two distinctive patterns, or tassels. Most commonly, the arrangement is a 3 + 1 pattern of three consecutive bulbs at the very end with a forth lying upstream, separated from the terminal three by a gap of 135 nm. In other populations the fibers terminate in 5 consecutive bulbs. It is proposed that the novel appendages may be involved in host cell searching and recognition in a marine environment.展开更多
【目的】跟踪调查甘蔗花穗经不同温度水浴杀雄后的生物学特征变化,评价温汤杀雄效果,为进一步提高甘蔗杂交结实提供理论依据。【方法】以花粉较多的甘蔗品种ROC22和科5为试验材料,设48、50和52℃温水各处理3 min 3个处理,以不进行温度...【目的】跟踪调查甘蔗花穗经不同温度水浴杀雄后的生物学特征变化,评价温汤杀雄效果,为进一步提高甘蔗杂交结实提供理论依据。【方法】以花粉较多的甘蔗品种ROC22和科5为试验材料,设48、50和52℃温水各处理3 min 3个处理,以不进行温度处理为对照,对各处理2个甘蔗品种花穗的开花动态、雌蕊外部形态变化、单穗散粉量、花粉成熟度、花粉活力变化及授予外源花粉4 h后柱头原位萌发情况和结实性进行对比分析。【结果】与对照相比,不同温度处理下2个甘蔗品种的花穗均延迟开花,温度越高,延迟时间越长;单穗散粉量和花粉活力显著(P<0.05)或极显著(P<0.01,下同)降低;随着处理温度的升高,单穗自交出苗数和异交出苗数极显著降低,假杂种比例呈先降低后升高的变化趋势,其中以50℃处理的假杂种比例最低(0.09~0.11),处理效果最佳。3种温度处理对雌蕊外观、柱头可授性及成熟花粉影响较小。【结论】结合甘蔗杂交育种对实生苗后代选择需要,以50℃温水处理3 min的去雄效果较理想,可减少后代区分假杂种的人工投入,提高育种效率。展开更多
文摘The objective was to visualize a variety of marine bacteriophage and identify unique structural features that set them apart from terrestrial phages. Phages were plaque isolated and characterized using atomic force microscopy. Bacteriophage infecting cyanobacteria synechococcus that exhibits a novel structural feature not previously reported for any other phages were observed. These cyanophages have up to four, 450 nm long, multi-stranded, complex helical fibers that emanate from either the base plate and/or the collar of the phage particle, origins of shorter fibers on well-studied phages such as T4. The flexible fibers terminate at their distal ends in multiple bulbs of diameter 30 nm composed of 20 to 30 closely associated proteins. Bulbs form one of two distinctive patterns, or tassels. Most commonly, the arrangement is a 3 + 1 pattern of three consecutive bulbs at the very end with a forth lying upstream, separated from the terminal three by a gap of 135 nm. In other populations the fibers terminate in 5 consecutive bulbs. It is proposed that the novel appendages may be involved in host cell searching and recognition in a marine environment.
文摘【目的】跟踪调查甘蔗花穗经不同温度水浴杀雄后的生物学特征变化,评价温汤杀雄效果,为进一步提高甘蔗杂交结实提供理论依据。【方法】以花粉较多的甘蔗品种ROC22和科5为试验材料,设48、50和52℃温水各处理3 min 3个处理,以不进行温度处理为对照,对各处理2个甘蔗品种花穗的开花动态、雌蕊外部形态变化、单穗散粉量、花粉成熟度、花粉活力变化及授予外源花粉4 h后柱头原位萌发情况和结实性进行对比分析。【结果】与对照相比,不同温度处理下2个甘蔗品种的花穗均延迟开花,温度越高,延迟时间越长;单穗散粉量和花粉活力显著(P<0.05)或极显著(P<0.01,下同)降低;随着处理温度的升高,单穗自交出苗数和异交出苗数极显著降低,假杂种比例呈先降低后升高的变化趋势,其中以50℃处理的假杂种比例最低(0.09~0.11),处理效果最佳。3种温度处理对雌蕊外观、柱头可授性及成熟花粉影响较小。【结论】结合甘蔗杂交育种对实生苗后代选择需要,以50℃温水处理3 min的去雄效果较理想,可减少后代区分假杂种的人工投入,提高育种效率。
