Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein. 相似文献
The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1. 相似文献
The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a widely distributed and destructive agricultural pest on various host plants. The
biology of two biotypes of B. tabaci: the invasive B and a new defined Cv biotype, on a range of host plants (hibiscus, laurel, poinsettia, collard, cucumber
and tomato) were studied in the laboratory. Results revealed that the developmental periods of the B biotype immatures were
not significantly different on the tested host plants except those between laurel and collard. The Cv biotype immatures developed
significantly slower on cucumber and tomato than on the other plants. B. tabaci B biotype had the highest survivorship on collard (68.55%), and the lowest on laurel (33.24%), while the Cv biotype had the
highest and lowest survivorships on laurel (61.63%) and tomato (36.74%). Host plants did not significantly affect the pre-ovipostion
period regardless of biotype. The longest averaged longevity and highest fecundity of B biotype were both recorded on collard:
25.15 days and 143.0 eggs. The highest fecundity of Cv biotype was 196.49 eggs on laurel and its longest longevity was on
hibiscus (19.62 days). The intrinsic rate of natural increase (rm) of B biotype on the three vegetables were all higher than those on the three ornamentals whereas the rm of Cv biotype on the three ornamentals were all higher that those on the three vegetables. Our research indicates that B. tabaci B and Cv biotypes have different host plant suitabilities. The three tested vegetables were more suitable for B biotype while
the three tested ornamental plants were more suitable for Cv biotype. The potential mechanism for the different suitability
of B and Cv biotypes on various host plants is also discussed. 相似文献
The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important insect pest of canola, Brassica napus L., in Ardabil, Iran. Host plant resistance is an essential component of integrated management of P. xylostella. We investigated the preferences and performance of P. xylostella on nine commercial cultivars of canola, namely Zarfam, RGS003, Adder, Okapi, Opera, Hyola401, Ebonite Option500 and Elite
under greenhouse conditions at 23 ± 1°C, 50 ± 5% RH and 14L:10D. In free-choice situation, oviposition was lowest on Opera
(23.5) and highest on Zarfam (44.7). In the life table study, fecundity of new generation female moths was lowest on Opera
(95.4) and highest on Adder (145.7). Survival from egg to adult was significantly lower on Opera, Option500 and Hyola401 than
on other tested cultivars. The intrinsic rate of natural increase (rm) and population growth rate (λ) were lowest on Opera and highest on Zarfam. The generation time (T) was shortest on Zarfam (17.2 days) and longest on Hyola401 (19.9 days) whereas doubling time (DT) was longest on Opera (3.9 days)
and shortest on Zarfam (3.0 days). Our results clearly suggest that Opera was the most resistant host among the tested cultivars
and has the potential to be used in the integrated management of P. xylostella. 相似文献
Fifty wheat varieties along with Jupateco-73 and Morocco were studied for the expression of leaf tip necrosis (LTN), a trait
linked with the durable rust resistance gene pair Lr34/Yr18. LTN was frequent (i.e., ≥6) in nine replications of a field experiment over 3 years in 17 genotypes, and the varieties were
considered positive for LTN. In molecular analyses of these varieties, having relative severity values up to 78 for yellow
rust and 45 for leaf rust, the 150-bp Lr34/Yr18-linked allele was consistently amplified. Expression of LTN in six of nine replications is an appropriate threshold for predicting
the presence of Lr34/Yr18 gene pair, and genotypes can be selected using this trait. 相似文献
On-line measurement of soil compaction is needed for site specific tillage management. The soil bulk density (ρ) indicating soil compaction was measured on-line by means of a developed compaction sensor system that comprised several sensors for on-line measurement of the draught (D) of a soil cutting tool (subsoiler), the soil cutting depth (d) and the soil moisture content (w). The subsoiler D was measured with a single shear beam load cell, whereas d was measured with a wheel gauge that consisted of a swinging arm metal wheel and a linear variable differential transducer (LVDT). The soil w was measured with a near infrared fibre-type spectrophotometer sensor. These on-line three measured parameters were used to calculate ρ, by utilising a hybrid numerical–statistical mathematical model developed in a previous study. Punctual kriging was performed using the variogram estimation and spatial prediction with error (VESPER) 1.6 software to develop the field maps of ρ, soil w, subsoiler d and D, based on 10 m × 10 m grid. To verify the on-line measured ρ map, this map was compared with the map measured by the conventional core sampling method.
The spherical semivariogram models, providing the best fit for all properties was used for kriging of different maps. Maps developed showed that no clear correlation could be detected between different parameters measured and subsoiler D. However, the D value was smaller at shallow penetration d, whereas large D coincided with large ρ values at few positions in the field. Maps of ρ measured with the core sampling and on-line methods were similar, with correlation coefficient (r) and the standard error values of 0.75 and 0.054 Mg m−3, respectively. On-line measured ρ exhibited larger errors at very dry zones. The normal distribution of the ρ error between the two different measurement methods showed that about 72% of the errors were less than 0.05 Mg m−3 in absolute values. However, the overall mean error of on-line measured ρ was of a small value of 2.3%, which ensures the method accuracy for on-line measurement of ρ. Measurement under very dry conditions should be minimised, because it can lead to a relatively large error, and hence, compacted zones at dry zones cannot be detected correctly. 相似文献
Maize straw and pea straw were added to five Pakistani soils from a gradient in salinity to test the following hypotheses: Increasing salinity at high pH decreases proportionally (1) the decomposition of added straw and (2) the resulting net increase in microbial biomass. In the non-amended control soils, salinity had depressive effects on microbial biomass C, biomass N, but not on biomass P and ergosterol. The ratios microbial biomass C-to-N and biomass C-to-P decreased consistently with increasing salinity. In contrast, the ergosterol-to-microbial biomass C ratio was constant in the four soils at pH>8.9, but nearly doubled in the most saline, but least alkaline, soil (pH 8.2). The addition of the maize and pea straw always increased the contents of microbial biomass C, biomass N, biomass P and ergosterol, but without clear effects of salinity. Highest mean contents of microbial biomass C and biomass N were measured at day 0, immediately after the straw was added. Straw amendments increased the CO2 evolution rates of all five soils without any effect of salinity. The same was true for total C and total N in the two fractions of particulate organic matter (POM) 63–400 μm and >400 μm. Lowest percentage of straw-derived CO2-C and highest recoveries of POM-C and POM-N were observed in the maize straw treatment and the reverse in the pea straw treatment. Yield coefficients were calculated for maize and pea straw based on the assumption that the balance gap between CO2 and the amount of POM can be fully assigned to microbial products. 相似文献