Non-steroidal inhibitors of Drosophila melanogaster steroidogenic glutathione S-transferase Noppera-bo

Insect growth regulators (IGRs) can be developed by elucidating the molecular mechanisms of insect-specific biological events. Because insect molting, and metamorphosis are controlled by ecdysteroids, their biosynthetic pathways can serve as targets for IGR development. The glutathione S-transferase Noppera-bo (Nobo), which is conserved in dipteran and lepidopteran species, plays an essential role in ecdysteroid biosynthesis. Our previous study using 17β-estradiol as a molecular probe revealed that Asp113 of Drosophila melanogaster Nobo (DmNobo) is essential for its biological function. However, to develop IGRs with a greater Nobo inhibitory activity than 17β-estradiol, further structural information is warranted. Here, we report five novel non-steroidal DmNobo inhibitors. Analysis of crystal structures of complexes revealed that DmNobo binds these inhibitors in an Asp113-independent manner. Among amino acid residues at the substrate-recognition site, conformation of conserved Phe39 was dynamically altered upon inhibitor binding. Therefore, these inhibitors can serve as seed compounds for IGR development.     

Use of fluorescent proteins to visualize interactions between the Bakanae disease pathogen <Emphasis Type="Italic">Gibberella fujikuroi</Emphasis> and the biocontrol agent <Emphasis Type="Italic">Talaromyces</Emphasis> sp. KNB-422

Talaromyces sp. isolate KNB-422, isolated from a rice seedling, is a biofungicidal agent effective against several seedborne pathogens of rice including Gibberella fujikuroi, which causes Bakanae disease. Because the fungal mode of action (MOA) has not yet been clarified, we used the fluorescent protein markers GFP and RFP to visualize cell–cell interactions between the biocontrol agent and the pathogen G. fujikuroi. In slide culture, the hyphal cell wall of G. fujikuroi collapsed, and fluorescence of its cytoplasm disappeared 3 days after contact with hyphae of Talaromyces sp. On inoculated rice plants, both fungi occupied the same regions of coleoptiles and roots, where the biocontrol effect of Talaromyces sp. must be exerted. Our observations suggest that the MOA of Talaromyces sp. is mycoparasitic.     

The effect of the cytoplasms of Brassica napus and B. juncea on some characteristics of B. carinata, including flower morphology

This study was conducted to assess the cytoplasm effects of Brassica napus and B. juncea on the some characteristics of B. carinata, as well as the phylogenetic distances separating the three species. Alloplasmic lines of B. carinata were developed from B. napus × B. carinata and B. juncea × B. carinata hybrids by recurrent backcrossing to the BC₇ generation. Sixteen populations from three generations were compared for a number of characteristics. Plants with the cytoplasm of B. napus flowered later, had shorter filaments and longer pistils, lower pollen amount, lower seed set, lower petal length and width and different petal color; plants with the cytoplasm of B. juncea had shorter pistils and filaments, and lower petal length and width than their corresponding euplasmic sibs, respectively. The results suggest that the cytoplasm is involved in the development of flower organs. The natural species, B. carinata showed a balance between the nucleus and cytoplasm. The cytoplasm from B. napus showed a stronger disturbing effect than that of B. juncea, suggesting that B. carinata might be genetically closer to B. juncea than to B. napus. The significant difference in the alloplasmic effect of the cytoplasms of B. napus and B. juncea also suggests that in B. carinata the B genome may play a greater role than the C genome. An erratum to this article can be found at     

Growth performance and carcass characteristics of broiler chickens fed diets supplemented with graded levels of charcoal from maize cob or seed of <Emphasis Type="Italic">Canarium schweinfurthii</Emphasis> Engl

Growth performances and carcass characteristics of broiler chickens fed diets supplemented with graded levels of Canarium schweinfurthii Engl seed (charcoal A) or maize cob (charcoal B) were studied using a total of 110 3-week-old male chicks. 11 experimental diets including a control and other containing either 0.2, 0.4, 0.6, 0.8 or 1% charcoal from C. schweinfurthii Engl seed (A_0.2, A_0.4, A_0.6, A_0.8, and A_1%, respectively) or from maize cob (B_0.2, B_0.4, B_0.6, B_0.8, and B_1%, respectively) supplements were used. Each of the diets was fed to ten individually birds caged in a completely randomized design. Results indicated that birds fed 0.2, 0.4, and 0.6% of either charcoal A or B had significantly (P < 0.05) higher final body weights as compared to control birds, while, above 0.6% slightly depressed average final body weights and weight gain. The best growth performance was achieved with 0.2% inclusion of charcoals. There was no significant (P > 0.05) influence of charcoal B on the overall feed intake. Only the B_0.6 feed significantly (P < 0.05) improved feed conversion ratio as compared with the control. Dressing percentage, liver weight and abdominal fat were not significantly (P > 0.05) affected by charcoal. However, there was a significant (P < 0.05) reduction in gizzard weight with charcoal B. Charcoal had no significant (P > 0.05) influence on intestine length and weight. More than 0.6% of charcoal A significantly (P < 0.05) depressed intestine density. It was concluded that under the conditions of this study, charcoal from maize cob or Canarium seeds could be used to improve growth performances and some carcass traits in broiler chickens.     

Sediment denitrification in waterways in a rice-paddy-dominated watershed in eastern China

Purpose

Rice-paddy-dominated watersheds in eastern China are intensively cultivated, and lands with two crops receive as much as 550–600 kg?ha^–1?year^–1 of nitrogen (N), mainly through the addition of N-based fertilizers. However, stream N concentrations have been found to be relatively low. Waterways in the watersheds are assumed to be effective “sinks” for N, minimizing its downstream movement. We directly measured net sediment denitrification rates in three types of waterways (ponds, streams/rivers, and a reservoir) and determined the key factors that control net sediment denitrification. Such information is essential for evaluating the impact of the agricultural N cycle on the quality of surface water.

Materials and methods

The pond–stream–reservoir continuum was sampled every 2 months at nine sites in an agricultural watershed between November 2010 and December 2011. Net sediment N₂ fluxes/net sediment denitrification rates were determined by membrane inlet mass spectrometry and the N₂/Ar technique. A suite of parameters known to influence denitrification were also measured.

Results and discussion

Net denitrification rates ranged between 28.2?±?18.2 and 674.3?±?314.5 μmol N₂–N?m^–2?h^–1 for the streams, 23.7?±?23.9 and 121.2?±?38.7 μmol N₂–N?m^–2?h^–1 for the ponds, and 41.8?±?17.7 and 239.3?±?49.8 μmol N₂–N?m^–2?h^–1 for the reservoir. The mean net denitrification rate of the stream sites (173.2?±?248.4 μmol N₂–N?m^–2?h^–1) was significantly higher (p?<?0.001) than that of the pond sites (48.3?±?44.5 μmol N₂–N?m^–2?h^–1), and the three types of waterways all had significantly higher (p?<?0.01) mean net denitrification rates in summer than in other seasons. Linear regression and linear mixed effect model analysis showed that nitrate (NO₃ ^?–N) concentration in surface water was the primary controlling factor for net sediment denitrification, followed by water temperature. Using monitoring data on NO₃ ^?–N concentrations and temperature of the surface water of waterways and an established linear mixed effect model, total N removed through net sediment denitrification in the pond–stream–reservoir continuum was estimated at 46.8?±?24.0 t?year^–1 from July 2007 to June 2009, which was comparable with earlier estimates based on the mass balance method (34.3?±?12.7 t?year^–1), and accounted for 83.4 % of the total aquatic N. However, the total aquatic N was only 4.4 % of the total N input to the watershed, and thus most of the surplus N in the watershed was likely to be either denitrified or stored in soil.

Conclusions

High doses of N in a rice-paddy-dominated watershed did not lead to high stream N concentrations due to limited input of N into waterways and the high efficiency of waterways in removing N through denitrification.     

Variations in chlorosis and potential usefulness of alloplasmic Brassica rapa with the cytoplasm of male sterile Brassica juncea

To select superior seed parents for vegetable hybrid seed production, we conducted interspecific crosses between male sterile Brassica juncea (2n = 36, AABB) and eight inbred lines of Brassica rapa (2n = 20, AA). Alloplasmic lines of B. rapa with the cytoplasm of B. juncea were developed from B. juncea × B. rapa hybrids by repeated backcrossing using B. rapa as the recurrent male parent until the BC₃ generation. Seed fertility, male sterility and chlorophyll content were investigated in these plants cultivated under four different temperature conditions (5, 10, 12 and 20°C). At 10°C, the alloplasmic lines of B. rapa with the cytoplasm of B. juncea were male sterile with partly chlorotic leaves. The alloplasmic B. rapa had lower chlorophyll a, chlorophyll b and carotenoid contents than those of the original B. rapa. The leaves recovered from chlorosis when the plants were cultivated at 20°C. An alloplasmic line of B. rapa (A6) is available as a seed parent for vegetable hybrid seed production and contributes seed fertility, slight chlorosis and stable male sterility.     

Non-destructive evaluation of surface longitudinal growth strain on Sugi (Cryptomeria japonica) green logs using near-infrared spectroscopy

A use of near-infrared (NIR) spectroscopy for rapidly predicting the longitudinal growth strain (LGS), as a detector of growth stress, was described. NIR spectra and LGS were measured from peripheral locations of three Sugi (Cryptomeria japonica) green logs. Partial least squares regression model for predicting LGS was developed using the spectral range spanning 770–1200?nm. The predicted LGS was correlated with that measured by the strain gauge method. The coefficient of determination and the root mean square error of prediction were 0.61 and 0.013%, respectively. The predicted peripheral LGS distribution moderately fitted with the measured one. Our results indicate that NIR spectroscopy has a potential to evaluate the magnitude of longitudinal growth stresses on green logs.     

Surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica) cultivars dried by the conventional kiln drying

To investigate the factors affecting the surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica), surface checks formed by the conventional kiln drying were compared for two stem heights of five cultivars with different wood properties. The total length and average length of the surface checks were greater at the upper part of the stems for all the cultivars. This might be caused by more sapwood at the upper part of the stem, and large drying stresses between the outer sapwood and the inner heartwood. The cultivars, in which tangential shrinkage was large owing to small microfibril angle, formed longer surface checks and smaller bow. There was a positive relationship between surface-check length and tangential shrinkage. The heartwood percentage and tangential shrinkage were thought to be important factors affecting the surface-check variation in sugi boxed-heart square timber.