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91.
It is known that low root zone temperatures (RZT) have moreeffect on infection and early nodule development than on nitrogenfixation by soybean [Glycine max (L.) Merr.]. However, therehave been no studies regarding how the low RZT inhibit the infectionstages of soybean. Two controlled environment experiments wereconducted to examine the effect of low RZT on bacterial attachmentto, and infection thread penetration of, soybean root hairs.The experimental designs were (1) plants maintained at 25, 17.5or 15C RZT, or transferred from 25 or 17.5 to 15C RZT at either0.5, 1, 2, or 7d after inoculation (DAI), (2) early symbioticestablishment between soybean and Bradyrhizobium japonicum wasexamined microscopically under three RZT (15, 17.5 and 25C).These results indicated that (1) keeping plants at 25C only0.5 DAI prior to transfer to a 15C RZT accelerates the onsetof N2 fixation at 15C RZT by 6 d, (2) at RZT between 25 and17.5C the infection processes were progressively delayed astemperature declined, (3) RZT less than 17C strongly inhibitedinfection steps, such that when RZT dropped 8.5C from 25 to17.5C infection initiation was delayed 1 d, while when RZTdropped only 2.5C from 17.5 to 15C, infection initiation wasdelayed another 2 d. Key words: Bradyrhizobium japonicum, low temperature, nodulation, soybean 相似文献
92.
Insect resistance of transgenic plants that express modified Bacillus thuringiensis cryIA(b) and cryIC genes: a resistance management strategy 总被引:7,自引:0,他引:7
93.
Expression of mouse metallothionein-I gene confers cadmium resistance in transgenic tobacco plants 总被引:8,自引:0,他引:8
Aihua Pan Meizhu Yang Feng Tie Lingyua Li Zhangliang Chen Biggen Ru 《Plant molecular biology》1994,24(2):341-351
Transgenic tobacco plants containing a mouse metallothionein-I (MT-I) gene fused to the cauliflower mosaic virus 35S (CaMV 35S) promoter and nopaline synthase (nos) polyadenylation site were obtained by transforming tobacco leaf discs with an Agrobacterium tumefaciens strain carrying the chimaeric gene. Transformants were directly selected and rooted on medium containing cadmium and kanamycin. A total of 49 individual transgenic tobacco plants were regenerated. Among them 20% showed a very high expression level and their growth was unaffected by up to 200 M cadmium, whereas the growth of control plants was severely affected leaf chlorosis occurred on medium containing only 10 M cadmium. The concentration of MT-I in leaves of control and transgenic tobacco was determined with Cd/haemoglobin saturation assay, a polarographic method and western blotting. In addition, seeds from self-fertilized transgenic plants were germinated on medium containing toxic levels of cadmium and scored for tolerance/susceptibility to this heavy metal. The ratio of tolerant to susceptible plants was 3:1 indicating that the metallothionein gene is inherited as a single locus. 相似文献
94.
Jin Feng Kunitoshi Yamanaka Hironori Niki Teru Ogura Sota Hiraga 《Molecular & general genetics : MGG》1994,243(2):136-147
The nucleotide sequence was determined of the region upstream of the mukB gene of Escherichia coli. Two new genes were found, designated kicA and kicB (killing of cell); the gene order is kicB-kicA-mukB. Promoter activities were detected in the regions immediately upstream of kicB and kicA, but not in front of mukB. Gene disruption experiments revealed that the kicA disruptant was nonviable, but the kicB-disrupted mutant and the mutant lacking both the kicB and kicA genes were able to grow. When kicA disruptant cells bearing a temperature-sensitive replication plasmid carrying the kicA
+ gene were grown at 30° C and then transferred to 42° C, the mutant cells gradually lost colony-forming ability, even in the presence of a mukB
+ plasmid. Rates of protein synthesis, but not of RNA or DNA synthesis, fell dramatically during incubation at 42° C. These results suggested that the kicB gene encodes a killing factor and the kicA gene codes for a protein that suppresses the killing function of the kicB gene product. It was also demonstrated that KicA and KicB can function as a post-segregational killing system, when the genes are transferred from the E. coli chromosome onto a plasmid. 相似文献
95.
96.
Largepterosaurwithamaximumwingspanofmorethan5metres.Theskullislowerandlonger,withoutmiddlecrestorsupraoccipita1crest.ThenasaIandpre-orbita1fenestraareconfluentcompletely,andoccupyaboutha1foftheskulI1ength.Thetoothlessbeakisslenderandpointed.The1ongneckiscomposedbyse-venslendercervicalvertebrae.Thenotariumconsistsofsixco-ossifiedanteriordorsalvertebrae-ThetaiIisextremlyshort.lthassixpairsof"A"shapegastralia.Theanteriorlimbsarestrong;thehumerusarethickandshort;thewing-metacarpalbonearelongert… 相似文献
97.
98.
广东封开县罗沙岩洞穴遗址第一期发掘简报 总被引:8,自引:1,他引:7
封开罗沙岩第一期发掘,出土了一些打制石器,它们有明确的地层,并有绝对年代测定数据,有助于解决广东是否有旧石器文化的争论。 相似文献
99.
A. S. Feng W. -Y. Lin L. Sun 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,175(5):531-546
Physiological studies were carried out in the frog (Rana pipiens pipiens) eighth nerve to determine: (i) whether the modulation rate or the silent gap was the salient feature that set the upper limit of time-locking to pulsed amplitude-modulated (PAM) stimuli, (ii) the gap detection capacity of individual eighth nerve fibers. Time-locked responses of 79 eighth nerve fibers to PAM stimuli (at the fiber's characteristic frequency) showed that the synchronization coefficient was a low-pass function of the modulation rate. In response to PAM stimuli having different pulse durations, a fiber gave rise to non-overlapping modulation transfer functions. The upper cut-off frequency of time locking was higher when tonepulses in PAM stimuli had shorter duration. The fact that the cut-off frequency was different for the different PAM series suggested that the AM rate was neither the sole, nor the main, determinant for the decay in time-locking at high AM rates. Gap detection capacity was determined for 69 eighth nerve fibers by assessing fiber's spiking activities to paired tone-pulses during an OFF-window and an ON-window. It was found that the minimum detectable gap of eighth nerve fibers ranged from 0.5 to 10 ms with an average of 1.23–2.16 ms depending on the duration of paired tone pulses. For each fiber, the minimum detectable gap was longer when the duration of tone pulses comprising the twin-pulse stimuli was more than four times longer. When the synchronization coefficient was plotted against the silent gap between tones pulses in the PAM stimuli, the gap response functions of a fiber as derived from multiple PAM series were equivalent to gap response functions deriving from twin-pulse series suggesting that it was the silent gap which primarily determined the upper limit of time-locking to PAM stimuli.Abbreviations
MTF
modulation transfer function
-
PAM
pulse amplitude modulated
-
SAM
sinusoidally amplitude modulated
-
SC
synchronization coefficient
-
TW
time window 相似文献
100.
斑须蝽三代卵块的空间分布和田间抽样技术研究 总被引:3,自引:0,他引:3
通过田间调查和计算,明确了斑须蝽三代卵块呈聚集分布,且以负二项分布为主。理论抽样数当t=1.00,D=0.3时,n=13.091/+63.878,如果防治指标定为百株虫卵块12块时,则最大抽样数为173株,序贯抽样的累积虫卵块数量界限为:T0(N)=0.12N±0.4735。田间随机取样以平行线和Z字形为最佳。 相似文献