荨麻皮刺水提液对小鼠离体肠平滑肌运动的影响

【目的】研究荨麻促进消化道平滑肌运动的植株主要部位,分析其可能的受体机制。【方法】用生物信号处理系统监测麻叶荨麻皮刺与内茎(不含皮刺)水提液对小鼠离体小肠平滑肌的影响。【结果】2倍浓度递增(0.1%~3.2%)的皮刺剂量依赖性增加小肠收缩幅度、收缩张力和收缩峰值(P<0.05),但对收缩频率无影响(P>0.05);而内茎浓度达0.4%后使小肠收缩频率减慢(P<0.05)。0.8%皮刺一次性用药后小肠收缩幅度、收缩张力、收缩峰值均显著升高(P<0.05),而同剂量内茎对小肠收缩无影响(P>0.05)。M-受体阻断剂ATr与0.8%皮刺联合用药可使收缩幅度显著减弱(P<0.05)。【结论】荨麻植株的皮刺对消化道平滑肌具有促进作用,且可能部分作用是通过激活M-受体而实现。     

种植密度对玉米-大豆带状间作下大豆光合、产量及茎秆抗倒的影响

【目的】阐明玉米-大豆带状间作下大豆植株冠层在不同种植密度下的光环境变化规律,明确种植密度对间作大豆叶片光合特性、产量形成及茎秆抗倒的影响,为构建寡日照地区间作大豆合理群体密度提供理论参考。【方法】本研究以大豆（川豆-16）和玉米（正红-505）为试验材料。采用双因素随机区组设计,主因素为种植方式,设玉米-大豆带状间作和大豆带状单作2个水平,副因素为大豆的3个种植密度（PD1=17株/m²,PD2=20株/m²,PD3=25株/m²),研究种植密度对间作大豆冠层内部光环境变化、叶片光合特性、植株生长动态、田间倒伏率及产量构成等的影响。【结果】2年结果表明,在玉米-大豆带状间作系统中,大豆生长中后期受高位作物玉米遮荫和自荫性增加的影响,其植株群体冠层内部的光合有效辐射（PAR）、叶面积指数（LAI）、叶片光合能力、分枝数及产量显著降低,但受玉米影响的程度因大豆种植密度的不同而不同。在间作模式下,PD1和PD2处理的大豆植株群体冠层光合有效辐射比PD3处理分别增加了45.4%和24.8%,净光合速率分别增加了46.1%和12.3%,单株有效荚数分别增加了53.2%和27.2%,单株分枝数分别增加了270.4%和140.9%,田间倒伏率分别降低了50.3%和19.3%。相关性分析发现,间作大豆的田间倒伏率与冠层内部光合有效辐射、叶片净光合速率、茎秆抗折力、茎叶干物质比、单株分枝数及单株有效荚数呈显著负相关,与株高、叶面积指数和单株无效荚数呈显著正相关。【结论】在玉米-大豆带状间作模式下,20株/m²的大豆密度（PD2）有利于创造良好的群体冠层内部光环境,降低植株田间大豆倒伏率,增加光合产物积累,从而提高大豆产量。     

Expression profiling of transgenes (Cry1Ac and Cry2A) in cotton genotypes under different genetic backgrounds

Transgenic cotton carrying the Cry1Ac gene has revolutionized insect pest control since its adoption, although the development of resistance in insect pests has reduced its efficacy.  After 10 years of cultivating Bacillus thuringiensis (Bt) cotton with a single Cry1Ac gene, growers are on the verge of adopting Bt cotton that carries the double gene (Cry1Ac+Cry2A) due to its better effectiveness against insect pests.  Thus, the current study was designed to evaluate the role of each gene in the effectiveness of Bt cotton carrying the double gene.  The expression levels of the Cry1Ac and Cry2A genes were evaluated in the leaves of 10 genotypes (2 parents and 8 F₁ hybrids) at 30 days after sowing (DAS), while samples of leaves, bolls and flowers were taken from the upper and lower canopies at 70 and 110 DAS.  The F₁ hybrids were developed through reciprocal crosses between two Bt (CKC-1, CKC-2) and two non-Bt (MNH-786, FH-942) parents.  The differential expression of transgenes was evaluated through Enzyme Linked Immuno-Sorbent Assay (ELISA).  The results showed that the MNH786×CKC-1 hybrid had the highest concentrations of Cry1Ac gene at 30 DAS (3.08 µg g^–1) and 110 DAS (1.01 µg g^–1) in leaves.  In contrast, the CKC-2×MNH-786 hybrid showed the lowest concentrations of Cry1Ac gene at 30 DAS (2.30 µg g^–1) and 110 DAS (0.86 µg g^–1).  The F₁ hybrid FH-942×CKC-2 showed the highest concentrations of Cry2A gene at 30 DAS (8.39 µg g^–1) and 110 DAS (7.74 µg g^–1) in leaves, while the CKC-1×MNH-786 hybrid expressed the lowest concentrations of Cry2A gene at 30 DAS (7.10 µg g^–1) and 110 DAS (8.31 µg g^–1).  A comparison between the two stages of plant growth showed that leaves had the highest concentrations at 30 DAS, whereas the lowest concentrations were observed at 110 DAS for both genes in leaves.  When the expression pattern was compared between various plant parts in genotype CKC-2, it was found that leaves had higher concentrations of Cry1Ac (3.12 µg g^–1) and Cry2A (8.31 µg g^–1) at 70 DAS, followed by bolls (Cry1Ac (1.66 µg g^–1) and Cry2A (8.15 µg g^–1)) and flowers (Cry1Ac (1.07 µg g^–1) and Cry2A (7.99 µg g^–1)).  The genotype CKC-2 had higher concentrations of Cry1Ac (3.12 µg g^–1) and Cry2A (8.31 µg g^–1) in the upper canopy but less accumulation (2.66 µg g^–1 of Cry1Ac, 8.09 µg g^–1 of Cry2A) in the lower canopy at 70 DAS.  Similarly, at 110 DAS, the expression levels of Cry1Ac and Cry2A in upper and lower canopy leaves were 1.52 and 7.92 µg g^–1, and 0.99 and 7.54 µg g^–1, respectively.  Hence, the current study demonstrates that different genotypes showed variable expression for both of the Cry1Ac and Cry2A genes during plant growth due to different genetic backgrounds.  The Cry2A gene had three-fold higher expression than Cry1Ac with significant differences in expression in different plant parts.  The findings of this study will be helpful for breeding insect-resistant double-gene genotypes with better gene expression levels of Cry1Ac and Cry2A for sustainable cotton production worldwide.     

Chemical composition and in vitro antifungal activity of Sambucus ebulus and Actinidia deliciosa on the fish pathogenic fungus,Saprolegnia parasitica

The aim of the present study was to determine the chemical composition of Sambucus ebulus and Actinidia deliciosa ethanolic extracts as well as their in vitro antifungal activity on the mycelial growth of the water mold, Saprolegnia parasitica. The preliminary minimum inhibition concentration (MIC) and minimum lethal concentration (MLC) were determined by the HeMP method and finally, concentrations of each extract ranging from 1 to 10% were prepared by an agar dilution method to assess the in vitro antifungal activity, quantitatively. Both herbal extracts inhibited growth of Saprolegnia hyphae in vitro. Complete in vitro growth inhibition was found at a concentration of ≥5% for S. ebulus, whereas it was not observed even at 10% concentration of A. deliciosa. Based on gas chromatography coupled with mass spectrometry (GC/MS) analysis, the main constituents of S. ebulus include monophthalate (66.17%), fatty acids (26.47%), phytol (4.25%), and acetic acid (2.11%). Using colorimetric assays, A. deliciosa contained phenolic contents at 162 mg gallic acid (GAE)/g DW and flavonoid contents at 2.31 mg quercetin (QE)/g DW. In conclusion, the results of this study indicated that S. ebulus and A. deliciosa showed some antifungal activities against S. parasitica with formerly exhibiting stronger activity (p < 0.05).

     

Dietary curcumin nanoparticles promoted the performance,antioxidant activity,and humoral immunity,and modulated the hepatic and intestinal histology of Nile tilapia fingerlings

Fish Physiology and Biochemistry - The current study investigated the effects of dietary curcumin nanoparticles (C-NPs) on the performance, hemato-biochemical profile, digestive enzymes activities,...     

Inhibition of protease activities in discus Symphysodon spp. by three plant meals

Based on biochemical assays and electrophoretical methods, the inhibitory effects of three plant meals (soybean meal, wheat meal, winged bean meal) on digestive alkaline proteases of discus were investigated. Casein assays revealed that increasing levels of soybean meal caused a linear inhibitory effect on activity of protease. SDS-PAGE images revealed that trypsin and chymotrypsin were the inhibited enzymes. Soybean showed the lowest inhibition rate followed by wheat meal and raw winged bean. There was a quadratic relationship between wheat meal levels and its inhibition of protease acitivity. The highest inhibitory effect was obtained with the winged bean meal with inhibition of caseinolytic activities ranging from 3.6–98.6%. Results from this study showed the potential of both soybean meal and wheat meal as ingredients for practical diet for discus, while demonstrating the need for further improvement in processing method for winged bean meal.     

Effects of feeding rates on growth and production of Nile tilapia, common carp and silver carp polycultured in fertilized ponds

Abstract In an attempt to identify appropriate feeding rates for multispecies of fish raised in fertilized earthen ponds, the present work was conducted over a 19‐week experimental period to establish the growth performance, production and body composition of Nile tilapia, common carp and silver carp fed 0.0%, 0.5%, 1.0%, 3.0%, 5.0% biomass and to apparent satiation (treatments). Twelve ponds were stocked with a similar number and weight of each fish species. Two ponds were assigned to each of the treatments, and a 25% protein pelleted fish feed was used to feed fish at the specified rate of feeding. At the end of the experiment, growth, weight gain, survival, yield and body composition of fish groups were affected by the treatments. The economic effectiveness also varied among treatments. The most conspicuous attribute of the feeding rates was its lack of influence on growth (g day^?1), weight gain (g per fish), yield (kg ha^?1) or body composition of silver carp. The results of whole‐body proximate analysis indicated that various feeding rates had either an irregular pattern or no effects on the protein and ash gain per 100 g of fish body weight (bw) gain. The most notable exceptions were significant (P < 0.05) increases in body fat and gross energy gains in Nile tilapia, common carp and silver carp accompanied by decreases in percentages of moisture (but not in silver carp) as feeding rate increased. Among the six different feeding levels, feeding to apparent satiation (feed amount was equivalent to 2.67% of fish bw day^?1) appeared to be optimal, as it significantly (P < 0.05) supported the highest fish production, income and net profit compared with all other treatments except for the 3% feeding level, for which the differences in those measurements were comparable.     

Molecular typing of Iranian field isolates Mycoplasma synoviae and their differentiation from the live commercial vaccine strain MS-H using vlhA gene

1. The single-copy domain of the N-terminal region of the vlhA gene of Mycoplasma synoviae was sequenced, analysed and verified and used to type Iranian field isolates of M. synoviae and the MS-H live vaccine strain. In addition, a restriction fragment length polymorphism (RFLP) method was developed to differentiate between field isolates of Iranian and MS-H vaccine strains.

2. All sequences were analysed and aligned; the percentage similarity of the DNA was calculated and dendrograms were constructed. Based on single nucleotide polymorphism (SNP) that existed in all field isolates in Iran, the PCR-RFLP method allowed the differentiation of all M. synoviae field isolates from the vaccine strain.

3. Using phylogenetic analysis, the isolates were assigned to 8 unique genotypes and, within each group, DNA had a high level of similarity.

4. DNA sequence analysis and PCR-RFLP of the amplicon based on percent similarity and evolutionary relationship appeared to be useful tools for strain differentiation whether M. synoviae clinical isolates from infected chickens were derived from the vaccine strain or wild-type strains.

5. This study confirms the potential value of strain typing for epidemiological purposes and suggests that phylogenetic studies are essential to understand the true relationships between strains.     

Influence of S. babylonica extract on feed intake, growth performance and diet in vitro gas production profile in young lambs

An experiment was completed to determine the effect of Salix babylonica (SB) extract supplementation to the diet of growing lambs. Eighteen Katahdin × Pelibuey male lambs (14?±?2 kg live body weight) were divided randomly in individual cages into three groups and fed three diets varying in SB: a control group was fed on total mixed ration (TMR) without SB (SB0), an SB25 group was fed on TMR plus SB extract at 25 mL/lamb/day, and an SB50 group was fed on TMR plus SB extract at 50 mL/lamb/day on dry matter intake (DMI), average daily gain (ADG), feed efficiency, and in vitro gas production (GP) in lambs fed on TMR. In vitro GP of the TMR fed to lambs was recorded at 2, 4, 6, 8, 10, 12, 24, 48, and 72 h of incubation with 0, 0.6, 1.2, and 1.8 mL extract per gram of DM. Addition of SB extract at low and high doses improved the DMI of lambs by 59.9 and 33.2 %, respectively. Relative to the control, low and high extract doses achieved greater lamb ADG during the experimental period. The asymptotic GP increased (P?<?0.05) with increasing dose of SB extract without affecting the rate of GP or the initial delay before GP begins. Linear increases for in vitro GP with advancing time with different SB extract doses were observed. It is suggested that the use of S. babylonica extract with the rate of 25 mL/lamb/day is beneficial to young lamb’s performance growth and thus can be safely used as a feed additive in diets without any negative effects on animal health.     

Fecal carriage of multi-drug resistant and extended spectrum β-lactamases producing E. coli in household pigeons,Bangladesh

Antibiotic resistance and ESBL constitute a risk to human and animal health. Birds residing close to humans could mirror the spectrum of human associated antibiotic resistance. Household pigeons were screened in Bangladesh to shed light on human associated, as well as, environmental antibiotic resistance. Escherichia coli from pigeons (n = 150) were tested against 11 antibiotics. 89% E. coli isolates were resistant to one or more critically important human antibiotics like ampicillin, cefadroxil, mecillinam, ciprofloxacin, gentamicin and tigecycline. No carbapenamase-producers were detected and the lower ESBL prevalence (5%) in pigeons. ESBL-producing E. coli isolates had bla_CTX-M-15 genes. Pigeons shared some bacterial clones and had bird associated sequence types like E. coli ST1408. Fecal carriage of bacteria resistance of critically important human antibiotics, together with examples of shared genotypes among pigeons, indicate the human-birds and bird to bird transmissions are important in the epidemiology of antibiotic resistance.