Cinnamic acid (CA), which is a well-known major autotoxin secreted by the roots in cucumber continuous cropping, has been proven to exhibit inhibitory regulation of plant morphogenesis and ...development. Melatonin (MT) has been recently demonstrated to play important roles in alleviating plant abiotic stresses. To investigate whether MT supplementation could improve cucumber seedling growth under CA stress, we treated cucumber seeds and seedlings with/without MT under CA- or non-stress conditions, and then tested their effects on cucumber seedling growth, morphology, nutrient element content, and plant hormone. Overall, 10 μM MT best rescued cucumber seedling growth under 0.4 mM CA stress. MT was found to alleviate CA-stressed seedling growth by increasing the growth rates of cotyledons and leaves and by stimulating lateral root growth. Additionally, MT increased the allocation of newly gained dry weight in roots and improved the tolerance of cucumber seedlings to CA stress by altering the nutrient elements and hormone contents of the whole plant. These results strongly suggest that the application of MT can effectively improve cucumber seedling tolerance to CA stress through the perception and integration of morphology, nutrient element content and plant hormone signaling crosstalk.
Yield increases of cucumber following cover crops in a rotation system have been previously reported for intensive Chinese agricultural production. However, little information is available as to how ...this system affects soil microbial properties and nematodes. A 4-year field experiment on a greenhouse cucumber double-cropping system was conducted to investigate the effects of four different summer cover crops on cucumber yield, soil nutrients, microbial properties and nematodes. After 4 years, six cover crop and residue management rotational cropping systems that included sweet corn residue removed (SR), sweet corn residue incorporated (SI), and garland chrysanthemum and edible amaranth (GR) significantly (P < 0.05) increased cucumber fruit yields summed for the years 2005-2008 by 22%, 32% and 26%, compared to the control (CONTROL), while cropping systems that included common bean residue removed (CR) and common bean residue incorporated (CI) significantly (P < 0.05) decreased yields by 30% and 22%, respectively. Plant available N losses and P, K accumulation in soil were efficiently reduced by planting cover crops. Soil microbial biomass, population and diversity were higher under summer cover crop-related treatments than under the control. The dominant plant-parasitic nematodes found in our experiment field were Meloidogyne sp. and Helicotylenchus sp, which were all parasites of both common bean and cucumber. A strong relationship between cucumber yields and the non-plant-parasitic: plant-parasitic nematode ratio (NPR) (r = 0.703, p < 0.001) was found in the break-host systems (SR, SI and GR). These results suggested that on the nutrient rich soils of our study, cucumber yield increases for the SR, SI and GR treatments, compared with the control, could be explained by higher microbial biomass, population and diversity and NPR.
Root-knot nematodes (
) induce specific feeding sites in cucumber roots where they absorb carbon nutrients from the host, thereby turning the feeding sites into a strong sink for assimilates. ...Nematode infection may alter host sugar metabolism in the roots of sucrose-transporting species. However, much less is known about the species translocating raffinose family oligosaccharides (RFOs), such as cucumber. To address this knowledge gap, the dynamics of RFOs and sucrose metabolisms, two major sugar-metabolism processes, in cucumber roots during nematode infection at transcription and protein levels were analyzed. In the nematode-infected root, the expressions of RFO-synthesis genes,
(
) and
(
), were upregulated at early stage, but were significantly decreased, along with
(
), at the late stage during nematode infection. By contrast, α-galactosidase hydrolyzed RFOs into sucrose and galactose, whose encoding genes was suppressed (
) at early stage and then elevated (
,
, and
) at the late stage of nematode infection. Consistently, stachyose level was significantly increased by ∼2.5 times at the early stage but reduced at the late stage of infection in comparison with the uninfected roots, with a similar trend found for raffinose and galactinol. Moreover, the genes encoding sucrose synthase and cell wall invertase, which are responsible for sucrose degrading, were differentially expressed. In addition, sugar transporter,
, was enhanced significantly after nematode infection at early stage but was suppressed at the late stage. Based on the observation and in connection with the information from literature, the RFOs play a role in the protection of roots during the initial stage of infection but could be used by nematode as C nutrients at the late stage.
Due to the increase in the human population, it is necessary to seek efficient methods of increasing crop productivity and, simultaneously, sustaining the soil. One way is to grow high demand crops ...continuously without rotating with other crops. This practice is often accompanied by increased rates of fertilizer application that can affect efficient nitrogen (N) cycling in the plant rhizosphere soil which, in turn, affects both plant growth and environmental pollution. In the present study, twelve various cucumber soils were selected from monoculture systems presenting different cropping years and divided into two groups including soils with relatively high mineral N (HMN) content (N > 100 mg kg−1 soil) and those with a lower mineral N (LMN) content (N < 100 mg kg−1 soil). All soils were amended with the addition of compost alone or in combination with bacterial inoculation to evaluate their effects on plant growth, microbial numbers, N mineralization, and N cycling genes. In general, the HMN soils increased (p < 0.05) net N mineralization (NNM) but did not statistically (p > 0.05) affect plant biomass compared to the LMN soils; however, compost addition increased both NNM and plant biomass in the HMN soils. In addition, the HMN soils had higher fungal pathogen numbers (FPNs) but lower total microbial biomass (TMB) and bacterial numbers (BNs) compared to the LMN soils; however, compost addition decreased FPNs but increased TMB and BNs in the HMN soils (all p < 0.05). Plant biomass was positively related to TMB, BN and NNM but was negatively related to FPN (all p < 0.05). In summary, compost addition reduced the high mineral N levels’ adverse effects on the rhizosphere soil and plant growth.
This study is the first report on production and characterization of the enzyme from an Ornithinibacillus species. A 4.2-fold increase in the extracellular protease (called L9 T ) production from ...Ornithinibacillus caprae L9 T was achieved through the one-factor-at-a-time approach and response surface methodological optimization. L9T protease exhibited a unique protein band with a mass of 25.9 kDa upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This novel protease was active over a range of pH (4-13), temperatures (30-80℃) and salt concentrations (0-220 g/l), with the maximal activity observed at pH 7, 70℃ and 20 g/l NaCl. Proteolytic activity was upgraded in the presence of Ag + , Ca 2+ and Sr 2+ , but was totally suppressed by 5 mM phenylmethylsulfonyl fluoride, which suggests that this enzyme belongs to the serine protease family. L9 T protease was resistant to certain common organic solvents and surfactants; particularly, 5 mM Tween 20 and Tween 80 improved the activity by 63 and 15%, respectively. More importantly, L9 T protease was found to be effective in dehairing of goatskins, cowhides and rabbit-skins without damaging the collagen fibers. These properties confirm the feasibility of L9 T protease in industrial applications, especially in leather processing.
This study is the first report on production and characterization of the enzyme from an
Ornithinibacillus
species. A 4.2-fold increase in the extracellular protease (called L9
T
) production from
...Ornithinibacillus caprae
L9
T
was achieved through the one-factor-at-a-time approach and response surface methodological optimization. L9
T
protease exhibited a unique protein band with a mass of 25.9 kDa upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This novel protease was active over a range of pH (4–13), temperatures (30–80°C) and salt concentrations (0–220 g/l), with the maximal activity observed at pH 7, 70°C and 20 g/l NaCl. Proteolytic activity was upgraded in the presence of Ag
+
, Ca
2+
and Sr
2+
, but was totally suppressed by 5 mM phenylmethylsulfonyl fluoride, which suggests that this enzyme belongs to the serine protease family. L9
T
protease was resistant to certain common organic solvents and surfactants; particularly, 5 mM Tween 20 and Tween 80 improved the activity by 63 and 15%, respectively. More importantly, L9
T
protease was found to be effective in dehairing of goatskins, cowhides and rabbit-skins without damaging the collagen fibers. These properties confirm the feasibility of L9
T
protease in industrial applications, especially in leather processing.
We isolated a moderately halophilic lipase-producing bacterium from the saline soil. Based on the morphological, physiological, chemotaxonomic and phylogenetic analysis, the isolate PT-11 was ...postulated to be a novel species identified as Oceanobacillus rekensis PT-11. The lipase was purified 2.50-fold by Q-Sepharose FF and SP-Sepharose FF chromatography and its molecular mass was estimated to be 23.5 kDa by SDS-PAGE. It was highly active over the broad temperature ranging from 10 to 35°C and showed up to 80% of the maximum activity at 10°C indicating the lipase to be a typical cold-adapted enzyme. The enzyme activity was slightly enhanced by Na+, Li+ and K+. Incubation with detergents, such as Tween-20 and Tween-80, slightly inhibited the enzyme activity; while Triton X-100decreased the enzyme activity. The enzyme was fairly stable in the presence of long-chain alcohols but was highly denatured in hydrophilic solvents such as acetone or short-chain alcohols (C1-C3).
Microbial degradation of dyes is vital to understanding the fate of dyes in the environment. In this study, a fungal strain A-3 and a bacterial strain L-6, which were identified as Aspergillus ...fumigatus and Pseudomonas fluorescens, respectively, had been proven to efficiently degrade crystal violet (CV) dye. The decolorization of CV dye by fungal and bacterial cocultivation was investigated. The results showed that the decolorization rate of cocultures was better than monoculture (P. fluorescens in L-6 (PF), and that of A. fumigatus A-3 (AF)). Furthermore, enzymatic analysis further revealed that Lac, MnP, Lip, and NADH–DCIP reductases were involved in the biodegradation of CV dyes. UV–visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and gas chromatography–mass spectrometry (GC–MS) were used to examine the degradation products. GC–MS analysis showed the presence of 4-(dimethylamino) benzophenone, 3-dimethylaminophenol, benzyl alcohol, and benzaldehyde, indicating that CV was degraded into simpler compounds. The phytotoxicity tests revealed that CV degradation products were less toxic than the parent compounds, indicating that the cocultures detoxified CV dyes. As a result, the cocultures are likely to have a wide range of applications in the bioremediation of CV dyes.
In this review, we report investigating photothermal hydrogels, innovative biomedical materials designed for infection control and tissue regeneration. These hydrogels exhibit responsiveness to ...near-infrared (NIR) stimulation, altering their structure and properties, which is pivotal for medical applications. Photothermal hydrogels have emerged as a significant advancement in medical materials, harnessing photothermal agents (PTAs) to respond to NIR light. This responsiveness is crucial for controlling infections and promoting tissue healing. We discuss three construction methods for preparing photothermal hydrogels, emphasizing their design and synthesis, which incorporate PTAs to achieve the desired photothermal effects. The application of these hydrogels demonstrates enhanced infection control and tissue regeneration, supported by their unique photothermal properties. Although research progress in photothermal hydrogels is promising, challenges remain. We address these issues and explore future directions to enhance their therapeutic potential.
The deep-sea environment has the characteristics of high pressure and low temperature. In addition to the extremely high requirements on the structural reliability, the ultra-high ambient pressure ...also has a great impact on the working characteristics of the hydraulic source. In this paper, the efficiency characteristics of a deep-sea hydraulic source are studied in the full-ocean-depth pressure range. According to the power transfer process, the efficiency of the deep-sea motor, gear pump and hydraulic circuit is analyzed. In so doing, the oil friction loss of the motor rotor, the internal leakage of the gear pump, the viscous friction loss of the hydraulic system, etc., are calculated. Then, simulating the deep-sea high-pressure environment by the pressure cylinder, the output characteristics and corresponding input power of the prototype are measured. By analyzing the experimental data, the efficiency characteristic curve of the hydraulic source prototype, changing with the ambient pressure, is obtained. The experimental and calculation results show that, with the increase of ambient pressure, the system efficiency of the hydraulic source prototype increases first and then decreases.
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