Determination of total flavonoids content in buckwheat and inhibition of α-amylase activity

Diabetes is one of the most difficult chronic diseases to cure in the world,which seriously affects people’s health and quality of life.Flavonoids in buckwheat can regulate blood glucose levels by inhibitingα-amylase activity.Therefore,sweet buckwheat produced in Inner Mongolia was used as the research object,and buckwheat fl avonoids were extracted by ultrasonic-assisted extraction method.Total fl avonoids content was determined by ultraviolet-visible spectrophotometry.With acarbose as the positive control,the inhibition test ofα-amylase was carried out by DNS colorimetry to study the inhibition behavior of fl avonoids onα-amylase activity.The results showed that the extraction process of flavonoids was stable and reliable,and the established method for the determination of flavonoids was simple,accurate and reproducible.The total flavonoids content of buckwheat samples was 2.706 mg/g,buckwheat total fl avonoids extraction solution had an inhibitory eff ect onα-amylase,and its median inhibition concentration(IC_(50))was 38.53 mg/mL.The results of this experiment provide a technical reference for the development and utilization of fl avonoids in Inner Mongolia sweet buckwheat,and provide a theoretical reference for the development and application of flavonoid-rich hypoglycemic food.

MICROSTRUCTURE AND AMYLASE ACTIVITY OF CHINESE CABBAGE SEED DURING DRYING PROCESS

A seed is the carrier of life,and research on the heat and mass transfer of a seed has already stridden toward the level of microcosm,such as cell protoplasm,cell organism,and molecular membrane.By means of a transmission electron microscope,the authors of this paper observed the microstructure of cotyledon tissue slices of the Chinese cabbage seed with a moisture content of 13% (on dry basis) and that with a moisture content of 4.3% (on dry basis) for drying 2 h at 45 ℃.The compared result was that only wrinkles had been discovered on the cell walls of the seed dried for 2 h,without any significant change for other organelles.Study on the enzyme activity shows that after a germination for 48 h,the relative activity of α amylase of the Chinese cabbage seed dried for 2 h at 45 ℃,decreased by 5.8%,whereas that of the seed dried 2 h at a temperature of 67 ℃ decreased by 30.1%.This work shows that the drying factors have greatly influence on the seed microstructure,enzyme activity,which is directly positive to seed viability.Combined with the analysis of the critical safe drying temperature of the vegetable seed,it can be concluded that enzyme activity is also the function of the drying temperature,the moisture content and the drying time.

Effects of Mercury Stress on Wheat Growth,POD and Amylase Activity

[Objective] The aim was to study the effect of mercury stress on seed germination and seedlings growth.[Method]using Zhengzhou 9023 as the experimental material and cultured in water,to study the effect of the germinating rate,seedling height,root length,seedling＇s fresh weight,the activities of peroxidase（POD）and amylase in leaf,root and germinating embryo at different concentrations of Hg2＋（0.025,0.050,0.100,0.200,0.300,0.400,0.500 mmol/L）.[Result]Low concentrations of Hg2＋（≤ 0.10 mmol/L）have little effect on seed germination,seedling height,root length and fresh weight;high concentrations of Hg2＋（ 0.10 mmol/L）have significantly inhibited seed germination and seedling growth.Low concentration of Hg2＋（≥ 0.025 mmol/L）could increase POD activity and inhibit the amylase activity significantly,and the effects have increased with the increasing of Hg2＋ concentrations.[Conclusion]Hg2＋ stress could change the activities of POD and amylase in leaf,root and germinating embryo,influence the energy and substrate supply which was required for normal metabolism of lipid oxidation,and inhibit seedling growth ultimately.

Glutamatergic CYLD deletion leads to aberrant excitatory activity in the basolateral amygdala:association with enhanced cued fear expression

Neuronal activity,synaptic transmission,and molecular changes in the basolateral amygdala play critical roles in fear memory.Cylindromatosis(CYLD)is a deubiquitinase that negatively regulates the nuclear factor kappa-B pathway.CYLD is well studied in non-neuronal cells,yet underinvestigated in the brain,where it is highly expressed.Emerging studies have shown involvement of CYLD in the remodeling of glutamatergic synapses,neuroinflammation,fear memory,and anxiety-and autism-like behaviors.However,the precise role of CYLD in glutamatergic neurons is largely unknown.Here,we first proposed involvement of CYLD in cued fear expression.We next constructed transgenic model mice with specific deletion of Cyld from glutamatergic neurons.Our results show that glutamatergic CYLD deficiency exaggerated the expression of cued fear in only male mice.Further,loss of CYLD in glutamatergic neurons resulted in enhanced neuronal activation,impaired excitatory synaptic transmission,and altered levels of glutamate receptors accompanied by over-activation of microglia in the basolateral amygdala of male mice.Altogether,our study suggests a critical role of glutamatergic CYLD in maintaining normal neuronal,synaptic,and microglial activation.This may contribute,at least in part,to cued fear expression.

Deciphering Water Oxidation Catalysts:The Dominant Role of Surface Chemistry over Reconstruction Degree in Activity Promotion

Water splitting hinges crucially on the availability of electrocatalysts for the oxygen evolution reaction.The surface reconstruction has been widely observed in perovskite catalysts,and the reconstruction degree has been often correlated with the activity enhancement.Here,a systematic study on the roles of Fe substitution in activation of perovskite LaNiO_(3)is reported.The substituting Fe content influences both current change tendency and surface reconstruction degree.LaNi_(0.9)Fe_(0.1)O_(3)is found exhibiting a volcano-peak intrinsic activity in both pristine and reconstructed among all substituted perovskites in the LaNi_(1-x)Fe_(x)O_(3)(x=0.00,0.10,0.25,0.50,0.75,1.00)series.The reconstructed LaNi_(0.9)Fe_(0.1)O_(3)shows a higher intrinsic activity than most reported NiFe-based catalysts.Besides,density functional theory calculations reveal that Fe substitution can lower the O 2p level,which thus stabilize lattice oxygen in LaNi0.9Fe0.1O3 and ensure its long-term stability.Furthermore,it is vital interesting that activity of the reconstructed catalysts relied more on the surface chemistry rather than the reconstruction degree.The effect of Fe on the degree of surface reconstruction of the perovskite is decoupled from that on its activity enhancement after surface reconstruction.This finding showcases the importance to customize the surface chemistry of reconstructed catalysts for water oxidation.

Acute Inflammatory Pain Induces Sex-different Brain Alpha Activity in Anesthetized Rats Through Optically Pumped Magnetometer Magnetoencephalography

Objective Magnetoencephalography(MEG),a non-invasive neuroimaging technique,meticulously captures the magnetic fields emanating from brain electrical activity.Compared with MEG based on superconducting quantum interference devices(SQUID),MEG based on optically pump magnetometer(OPM)has the advantages of higher sensitivity,better spatial resolution and lower cost.However,most of the current studies are clinical studies,and there is a lack of animal studies on MEG based on OPM technology.Pain,a multifaceted sensory and emotional phenomenon,induces intricate alterations in brain activity,exhibiting notable sex differences.Despite clinical revelations of pain-related neuronal activity through MEG,specific properties remain elusive,and comprehensive laboratory studies on pain-associated brain activity alterations are lacking.The aim of this study was to investigate the effects of inflammatory pain(induced by Complete Freund’s Adjuvant(CFA))on brain activity in a rat model using the MEG technique,to analysis changes in brain activity during pain perception,and to explore sex differences in pain-related MEG signaling.Methods This study utilized adult male and female Sprague-Dawley rats.Inflammatory pain was induced via intraplantar injection of CFA(100μl,50%in saline)in the left hind paw,with control groups receiving saline.Pain behavior was assessed using von Frey filaments at baseline and 1 h post-injection.For MEG recording,anesthetized rats had an OPM positioned on their head within a magnetic shield,undergoing two 15-minute sessions:a 5-minute baseline followed by a 10-minute mechanical stimulation phase.Data analysis included artifact removal and time-frequency analysis of spontaneous brain activity using accumulated spectrograms,generating spectrograms focused on the 4-30 Hz frequency range.Results MEG recordings in anesthetized rats during resting states and hind paw mechanical stimulation were compared,before and after saline/CFA injections.Mechanical stimulation elevated alpha activity in both male and female rats pre-and post-saline/CFA injections.Saline/CFA injections augmented average power in both sexes compared to pre-injection states.Remarkably,female rats exhibited higher average spectral power 1 h after CFA injection than after saline injection during resting states.Furthermore,despite comparable pain thresholds measured by classical pain behavioral tests post-CFA treatment,female rats displayed higher average power than males in the resting state after CFA injection.Conclusion These results imply an enhanced perception of inflammatory pain in female rats compared to their male counterparts.Our study exhibits sex differences in alpha activities following CFA injection,highlighting heightened brain alpha activity in female rats during acute inflammatory pain in the resting state.Our study provides a method for OPM-based MEG recordings to be used to study brain activity in anaesthetized animals.In addition,the findings of this study contribute to a deeper understanding of pain-related neural activity and pain sex differences.

Copper complexes of anthrahydrazone bearing pyridyl side chain:Synthesis,crystal structure,anticancer activity,and DNA binding

To expand the study on the structures and biological activities of the anthracyclines anticancer drugs and reduce their toxic side effects,the new anthraquinone derivatives,9‑pyridylanthrahydrazone(9‑PAH)and 9,10‑bispyridylanthrahydrazone(9,10‑PAH)were designed and synthesized.Utilizing 9‑PAH and 9,10‑PAH as promising anticancer ligands,their respective copper complexes,namely[Cu(L1)Cl_(2)]Cl(1)and{[Cu_(4)(μ_(2)‑Cl)_(3)Cl_(4)(9,10‑PAH)_(2)(DMSO)_(2)]Cl_(2)}_(n)(2),were subsequently synthesized,where the new ligand L1 is formed by coupling two 9‑PAH ligands in the coordination reaction.The chemical and crystal structures of 1 and 2 were elucidated by IR,MS,elemental analysis,and single‑crystal X‑ray diffraction.Complex 1 forms a mononuclear structure.L1 coordinates with Cu through its three N atoms,together with two Cl atoms,to form a five‑coordinated square pyramidal geometry.Complex 2 constitutes a polymeric structure,wherein each structural unit centrosymmetrically encompasses two five‑coordinated binuclear copper complexes(Cu1,Cu2)of 9,10‑PAH,with similar square pyramidal geometry.A chlorine atom(Cl_(2)),located at the symmetry center,bridges Cu1 and Cu1A to connect the two binuclear copper structures.Meanwhile,the two five‑coordinated Cu2 atoms symmetrically bridge the adjacent structural units via one coordinated Cl atom,respectively,thus forming a 1D chain‑like polymeric structure.In vitro anticancer activity assessments revealed that 1 and 2 showed significant cytotoxicity even higher than cisplatin.Specifically,the IC_(50)values of 2 against HeLa‑229 and SK‑OV‑3 cancer cell lines were determined to be(5.92±0.32)μmol·L^(-1)and(6.48±0.39)μmol·L^(-1),respectively.2 could also block the proliferation of HeLa‑229 cells in S phase and significantly induce cell apoptosis.In addition,fluorescence quenching competition experiments suggested that 2 might interact with DNA by an intercalative binding mode,offering insights into its underlying anticancer mechanism.CCDC:2388918,1;2388919,2.

Passive activity enhances residual control ability in patients with complete spinal cord injury

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

Prognostic value of combined detection of alpha-fetoprotein,plasma prothrombin activity,and serum prealbumin in acute-on-chronic liver failure

BACKGROUND Acute-on-chronic liver failure(ACLF)is a liver disease based on chronic liver disease,which is significantly influenced by clinical treatment regimen and disease status,and despite the existence of multiple prognostic assessment indicators for ACLF,the overall sensitivity and accuracy are relatively low.AIM To investigate the prognostic value of the combined detection of alpha-fetoprotein(AFP),plasma prothrombin activity(PTA),and serum prealbumin(PA)in ACLF.METHODS This retrospective study included 87 patients with ACLF admitted from February 2021 to February 2023 and categorized them into the survival(n=47)and death(n=40)groups according to their clinical outcomes 3 months posttreatment.All the participants underwent AFP,PTA,and PA level measurements upon admission.Baseline data,as well as AFP,PTA,and PA levels,were comparatively analyzed.Pearson correlation coefficients were utilized to analyze the correlations of AFP,PTA,and PA with different survival outcomes in patients with ACLF.Receiver operating characteristic(ROC)curves and areas under the curves were used to evaluate the predictive value of AFP,PTA,and PA for ACLF prognosis.RESULTS AFP,PTA,and PA levels were markedly decreased in the death group than in the survival group(P<0.05).Pearson analysis indicated a positive association of the AFP,PTA,and PA levels with the survival of patients with ACLF(P<0.05).ROC curve analysis determined the sensitivity and specificity of the combined diagnosis at 91.24%and 100.00%,respectively,both of which were notably increased compared to the single-index diagnosis.The ROC of their combined diagnosis was 0.989,significantly surpassing 0.907,0.849,and 0.853 of AFP,PTA,and PA,respectively.No statistically significant variance was determined in the sensitivity and specificity of the combined diagnosis vs the single detection(P>0.05).CONCLUSION The combined detection of AFP,PTA,and PA levels demonstrates favorable diagnostic value for the short-term prognosis of patients with ACLF,featuring high sensitivity and specificity.

In vitro α-amylase inhibitory activity and in vivo hypoglycemic effect of methanol extract of Citrus macroptera Montr.fruit

Objective:To investigate the therapeutic effects of methanol extract of Citrus macroptera Montr,fruit inα-amylase inhibitory activity(in vitro)and hypoglycemic activity in normal and glucose induced hyperglycemic rats(in vivo).Methods:Fruits of Citrus macroptera without rind was extracted with pure methanol following cold extraction and tested for presence of phytochemical constituents,α-amylase inhibitory activity,and hypoglycemic effect in normal rats and glucose induced hyperglycemic rats.Results:Presence of saponin,steroid and terpenoid were identified in the extract.The results showed that fruit extract had moderateα-amylase inhibitory activity[IC_(50)value=(3.638±0.190)mg/mL]as compared to acarbose.Moreover at 500 mg/kg and 1000 mg/kg doses fruit extract significantly(P<0.05 and P<0.01 respectively)reduced fasting blood glucose level in normal rats as compared to glibenclamide(5 mg/kg).In oral glucose tolerance test,500 mg/kg dose significantly reduced blood glucose level(P<0.05)at 2 h but 1000 mg/kg dose significantly reduced blood glucose level at 2 h and 3 h(P<0.05 and P<0.01 respectively)whereas glibenclamide(5 mg/kg)significantly reduced glucose level at every hour after administration.Overall time effect is also considered extremely significant with F value=23.83 and P value=0.0001 in oral glucose tolerance test.Conclusion:These findings suggest that the plant may be a potential source for the development of new oral hypoglycemic agent.

Effect of Cerium on Activity of α-Amylase from Porcine Pancreas

The activity of α amylase from porcine pancreas was enhanced under the treatment by Ce 3+ of low concentration (0.5～10 μmol·L -1 ), but was inhibited by Ce 3+ of high concentration (>10 μmol·L -1 ). Ce 3+ at high concentration displaced Ca 2+ from α amylase competitively. The equilibrium dialysis demonstrates that α amylase has five Ca 2+ binding sites with different affinities. The fluorescence titration shows that Ce 3+ can bind to Ca 2+ binding sites.

Relationship between malt qualities and β-amylase activity and protein content as affected by timing of nitrogen fertilizer application

The effects of different timing of N fertilizer application at the same rate on grain β-amylase activity, protein con- centration, weight and malt quality of barley were studied. Grain β-amylase activity and protein concentration were significantly higher in treatments where all top-dressed N fertilizer was applied at booting stage only or equally applied at two-leaf stage and booting stage than in the treatment where all top-dressed N fertilizer was applied at two-leaf age stage only. On the other hand, grain weight and malt extract decreased with increased N application at booting stage. There were obvious differences between barley varieties and experimental years in the grain and malt quality response to the timing of N fertilizer application. It was found that grain protein concentration was significantly and positively correlated with β-amylase activity, but significantly and nega- tively correlated with malt extract and Kolbach index. The effect of grain protein concentration on malt quality was predominant over the effect of grain β-amylase activity.

Effect of Static Magnetic Field on α-Amylase Activity and Enzymatic Reaction

The effect of magnetic field on a-amylase was studied. Under the experimental conditions, a-amylase solution was treated by 0.15 T, 0.30 T and 0.45 T static magnetic fields for a known period of time, then the activity, kinetic parameters, and the secondary conformation were investigated. The results showed that there was a considerable effect of the magnetic exposure on the α-amylase. The activity was increased by 27%, 34.1%, 37.8% compared with the control. It was also found that both kinetic parameters Km and Vm could be decreased due to the increasing magnetic field, Km decreased from 2.20×10^2 to 0.87×10^2, whereas Vm decreased from 2.0×10^3 g/min to 1.1 ×10^3 g/min. At the same time, there were some irregular changes in a-amylase secondary conformation.

Monitoring salivary amylase activity is useful for providing timely analgesia under sedation

AIM:To detect the criteria and cause of elevated salivary amylase activity(sAMY)in patients undergoing endoscopic submucosal dissection(ESD)under sedation.METHODS:A total of 41 patients with early gastric cancer removed via ESD under deep sedation(DS)were enrolled.The perioperative sAMY,which was shown as sympathetic excitements(SE),was measured.The time at which a patient exhibited a relatively increased rate of sAMY compared with the preoperative baseline level(IR,%)≥100%(twice the actual value)was assumed as the moment when the patient received SE.Among the 41 patients,we focused on 14 patients who exhibited an IR≥100% at any time that was associated with sAMY elevation during ESD(H-group)and examined whether any particular endoscopic procedures can cause SE by simultaneously monitoring the sAMY level.If a patient demonstrated an elevated sAMY level above twice the baseline level,the endoscopic procedure was immediately stopped.In the impossible case of discontinuance,analgesic medicines were administered.This study was performed prospectively.RESULTS:A total of 26 episodes of sAMY eruption were considered moments of SE in the H-group.The baseline level of sAMY significantly increased in association with an IR of>100% at 5 min,with a significant difference(IR immediately before elevation/IR at elevation of sAMY=8.72±173/958±1391%,P<0.001).However,effective intervention decreased the elevated sAMY level immediately within only 5 min,with a significant difference(IR at sAMY elevation/immediately after intervention=958±1391/476±1031,P<0.001).The bispectral indices,systolic blood pressure and pulse rates,which were measured at the same time,remained stable throughout the ESD.Forceful endoscopic insertion or over insufflation was performed during 22 of the 26 episodes.Release of the gastric wall tension and/or the administration of analgesic medication resulted in the immediate recovery of the elevated sAMY level,independent of body movement.CONCLUSION:By detecting twice the actual sAMY based on the preoperative level,the release of the gastric wall tension or the administration of analgesic agents should be considered.

Salivary alpha-amylase activity—An indicator of relaxation response in perioperative patients

The psychological stress of most perioperative patients has been reduced by many interventions. In order to evaluate the effects of these interventions, biomarkers are being considered as objective assessment tools in addition to the subjective assessment tools. It has been thought that salivary α-amylase (sAA) activity is associated with sympathetic nervous system activity, which reflects psychological stress. We examined the relationship between sAA, self-reported data, and autonomic nervous system activity to assess the reliability of sAA as a marker for relaxing response in surgery-related stress. The sAA, the State anxiety, Visual Analogue Scale (VAS) of pain, and heart rate variability were used to assess prior to and after the relaxation on the day before surgery, and on postoperative days (POD) 1, 2, 3, and 7. A total of 75 patients participated and 301 relaxing response readings were obtained. We found that the sAA significantly decreased depending upon the pain and anxiety by relaxation, but they were unrelated to sympathetic nervous system activity. There was weak correlation between the change in sAA, and anxiety and VAS pain. Thus, sAA appears to be an easy-to-use, non-invasive and good marker for relaxing response within a short period in surgery-related stress patients.

The Effect of the Extracts of Endophytic Fungi on Pancreatic a-Amylase Activity

Inhibitors of pancreatic a-amylase offer an effective strategy to lower the levels of postprandial hyperglycemia by controlof starch breakdown. Among 86 fungal endophytes isolated from 15 medicinal plants Aspergillus terreus-AFl04S, Aspergillusegypticus-HT166S and Penicillium sp.-CC200 exhibited strong pancreatic amylase inhibitory potential were selected. Endophyteswere subjected to ethyl acetate extraction and tested for a-amylase inhibition, in order to assess and evaluate their inhibitory potentialon pancreatic a-amylase. Analysis showed concentration dependent enzyme inhibition up to 83% with half inhibition （IC50） valuesfor less 25 mg.mL1, which is lower than acarbose as control. It was observed 3-fold increasing of Vmax and maintenance Km atcontrol level in the presence of extracts A. terreus-AFl04S and Penicillium sp.-CC200, while in presence of extract A.egypticus-HT166S Km was doubled, and Vmax was maintained at the control level. Kinetic studies allow proposing the competitivemode of a-amylase inhibition by extracts A. egypticus-HT166S and uncompetitive inhibition by extracts A, terreus-AFl04S andPenicillium sp.-CC200.

Activities, Quantitative Changes and Subcellular Localization of α-Amylase During Development of Apple Fruit

Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuberous roots, and fleshy fruit development. α_Amylase is considered as one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was often shown extrachloroplastic in living cells. The present experiment showed that α_amylase activity was progressively increasing concomitantly with the decreasing starch concentrations during the development of apple ( Malus domestica Borkh cv. Starkrimson) fruit. The apparent amount of α_amylase assessed by Western blotting also increased during the fruit development, which is consistent with the seasonal changes in the enzyme activity. The enzyme subcellular_localization studies via immunogold electron_ microscopy technique showed that α_amylase visualized by gold particles was predominantly located in plastids, but the gold particles were scarcely found in other subcellular compartments. A high density of the enzyme was observed at the periphery of starch granules during the middle and late developmental stages. These data proved that the enzyme is compartmented in its functional sites in the living cells of the fruit. The predominantly plastid_distributed pattern of α_amylase in cells was shown unchanged throughout the fruit development. The density of gold particles (α_amylase) in plastids was increasing during the fruit development, which is consistent with the results of Western blotting. So it is considered that α_amylase is involved in starch hydrolysis in plastids of the fruit cells.

Salivary Alpha-Amylase Reactivity under Psycho-Physiological Stress. A Nonverbal Communication Measurement Tool?

Previous studies have shown that changes in salivary alpha-amylase (sAA) levels are dependent on psychosocial stress stimulation and reflect the activity of the sympathetic nervous system. sAA measurement can be performed easily and quickly;therefore, it may be useful for evaluating psychosocial or physical stress. The aim of this preliminary study was to examine the use of sAA measurements as objective indicators of psychological and physiological stress levels by examining sAA changes in volunteers subjected to conditions similar to those suffered by children with severe motor and intellectual disabilities and cerebral paralysis. Twelve healthy volunteers were required to not move or speak, as is found in patients suffering from total paralysis, for 30 min. Saliva samples were taken at three points, and sAA activity was measured using a hand-held monitor before the test, immediately after the test, and 10 min after the test. In the present study, a marked increase in sAA activity due to physiological stress and a rapid return to the baseline level were observed. Many subjects felt bodily pain and psychotic discomfort. This measurement method is useful for evaluating stress in children with severe motor and intellectual disabilities, who can not fully express their emotions or communicate with their caregivers.

Effects of Exogenous Amylases and Metal Ions on the Amylase Specific Activities and Starch Degradation of the Upper Leaves of ‘KRK_(26)' during Flue-curing

Objective] The aim of this study was to investigate the effects of exoge-nous amylases and Ca2＋, Mn2＋ and K＋ on the amylase specific activities and starch degradation of the upper leaves of ＇KRK26＇ planted in Yunnan Province during flue-curing. [Method] The amylase specific activities and starch degradation of the leaves were determined by using spectrophotometry. [Result] The 8 U/g exogenous α-amy-lase could improve the specific activity of the leaf α-amylase at yel owing and color-fixing stages, but could not at stem-drying stage, and similarly, the 80 U/g exoge-nous β-amylase could improved the specific activity of the leaf β-amylase at the yel owing stage and the early period of color-fixing stage. The leaf starch could be enhanced to degrade by the exogenous α- or β-amylases and the enhancing effect of the former was stronger than that of the later. 1.50 mg/ml Ca2＋ improved the specific activity of the leaf （α＋β）-amylase mainly due to its enhancing effect on the leaf α-amylase, and increased the starch degradation. 4 mmol/L Mn2＋ inhibited the leaf α-amylase from yel owing to the early period of color-fixing and the β- and （α＋β）-amylases from the yel owing to the later period of color-fixing, but enhanced the leafα-amylase from the later period of color-fixing to the later period of stem-drying and the β- and （α＋β）-amylases at the later period of stem-drying. Meanwhile, Mn2＋ ham-pered the starch degradation during yel owing, but promoted it from the early period of color-fixing to stem-drying. 1 mg/ml K＋ enhanced the leaf α-, β- and （α＋β）-amy-lases during the yel owing stage, but lowered them from the early period of color-fix-ing to the later period of stem-drying, and always inhibited the leaf starch degrada-tion. [Conclusion] The exogenous α-, β- amylases and Ca2＋ of suitable concentra-tions could be used to treat the tobacco leaves before flue-curing to improve the leaf starch degradation during the curing.

Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice (Oryza sativa)

Two rice varieties, Xiushui 110 with high cadmium (Cd) tolerance and Xiushui 11 with low Cd tolerance were used to study the effects of Cd stress on seed germination, seedling growth and amylase activities. The low cadmium concentration had little effect on seed germination rate. However, cadmium stress could significantly inhibit plumule and radicle growth, especially for radicle growth. Germination index, vigour index, radicle length and amylase activities of Xiushui 11 decreased more significantly with the increasing cadmium level compared with Xiushui 110. The cadmium content in seedlings of Xiushui 11 was higher than that in Xiushui 110 when the cadmium concentration exceeded 5 μmol/L, which caused lower mitotic index in root tips and amylase activities, and more serious cadmium toxicity in Xiushui 11.