Variation In Enzyme Activity Research Articles

Subtropical urban turfs: Carbon and nitrogen pools and the role of enzyme activity

Urban grasslands not only provide a recreational venue for urban residents, but also sequester organic carbon in vegetation and soils through photosynthesis, and release carbon dioxide through respiration, which largely contribute to carbon storage and fluxes at regional and global scales. We investigated organic carbon and nitrogen pools in subtropical turfs and found that dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) were regulated by several factors including microbial activity which is indicated by soil enzymatic activity. We observed a vertical variation and different temporal patterns in both soil DOC, DON and enzyme activities, which decreased significantly with increasing soil depths. We further found that concentration of soil DON was linked with turf age. There were correlations between grass biomass and soil properties, and soil enzyme activities. In particular, soil bulk density was significantly correlated with soil moisture and soil organic carbon (SOC). In addition, DOC correlated significantly with DON. Significant negative correlations were also observed between soil total dissolved nitrogen (TDN) and grass biomass of Axonopus compressus and Zoysia matrella. Specifically, grass biomass was significantly correlated with the soil activity of urease and β-glucosidase. Soil NO3-N concentration also showed negative correlations with the activity of both β-glucosidase and protease but there were no significant correlations between cellulase and soil properties or grass biomass. Our study demonstrated a relationship between soil C and N dynamics and soil enzymes that could be modulated to enhance SOC pools through management and maintenance practices.

Seasonal variations of soil enzyme activities in typical plant communities in the Ebinur Lake wetland, China

In this study, the soil catalase, phosphatase and urease activities of typical plant communities of reed (Phragmites australis) and tamarisk (Tamarix ramosissima) and their influencing factors were investigated in Ebinur Lake wetland. The results showed that three soil enzyme activities of reed and tamarisk had seasonal dynamic characteristics during different growth periods. For the reed community, the peak concentrations of soil catalase, phosphatase and urease appeared at vigorous stage with 3.26, 0.60 and 0.33 mg·g-1, respectively, and the minimum value occurred at budding stage and leaf-expansion stage. For the tamarisk community, the peak values of three soil enzyme activities appeared at withered stage with values of 6.33, 0.58 and 0.21 mg·g-1, respectively, and the valley values were observed at flowering and vigorous stages. Urease was stable during different growth periods, and it could be used as an indicator to identify the differences of soil enzyme activities in the wetlands. The enzyme activities of reed and tamarisk had significant positive correlation with soil organic matter and total P in all growth periods, while there was no significant relationship between enzyme activities and soil water content. The enzyme activities of reed had significant positive correlation with ammonium nitrogen in the rapid growth period. There were no significant relationships between enzyme activities and soil salinity in both communities. The soil enzyme activities of reed and tamarisk were controlled by many factors. Soil organic matter, soil water and soil temperature were the main factors influencing the enzyme activities in the Ebinur Lake wetland.

Age and gender-specific reference intervals for lysosomal enzymes in dried blood spot samples: A study in Indian population

ObjectivesThe study aimed to establish age and gender-specific reference values for the activities of lysosomal enzymes (acid α-galactosidase [GLA], acid β-glucocerebrosidase [GBA], acid α-glucosidase [GAA], acid sphingomyelinase [ASM] and galactocerebrosidase [GALC]) in dried blood spots (DBS) of Indian population. Design and methodsA total of 3797 healthy Indian subjects (1456 females and 2341 males) aged from 2days to 60years were selected for the study. Activities of 5 lysosomal enzymes were determined by tandem mass spectrometry, for newborns (<30days), infants (>1month–1year), children (>1–5years) and (>5–18years) and adults (>18years).Variations in enzyme activities based on age and gender were studied. The reference interval was defined as the central 95% range, and was determined based on age and gender. ResultsHighly significant differences in activities were observed for GAA (p=0.001), GLA (p<0.0001), GBA (p<0.0001), ASM (p<0.0001) and GALC (p<0.0001), between different age groups. Comparison of activities between genders showed significant difference for ASM in children aged 1–5years (p=0.03) with higher activity in females, and for GLA in children aged 5–18years (p=0.004) where the activity was higher in males. Reference intervals decreased with age for all enzymes, except GAA. The ranges of GLA and GALC were higher in females, whereas GBA was higher in males. ConclusionThe study establishes age and gender-specific reference values for the screening and identification of lysosomal storage disorders in Indian population. Our data may facilitate establishment of mass screening programs for these disorders in India.

Relationship between metabolic enzyme activities and bioaccumulation kinetics of PAHs in zebrafish (Danio rerio)

Many studies have investigated bioaccumulation and metabolism of polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms. However, lack of studies investigated both processes simultaneously, and the interaction between these two processes is less understood so far. This study investigated the bioaccumulation kinetics of PAHs and metabolic enzyme activities, including total cytochrome P450 (CYPs) and total superoxide dismutase (T-SOD), in zebrafish. Mature zebrafish were exposed to the mixture of phenanthrene and anthracene under constant concentration maintained by passive dosing systems for 16days. The results showed that PAH concentrations in zebrafish experienced a peak value after exposure for 1.5days, and then decreased gradually. The bioaccumulation equilibrium was achieved after exposure for 12days. Both of the uptake rate constants (ku) and the elimination rate constants (ke) decreased after the peak value. The variation of PAH concentrations and metabolic enzyme activities in zebrafish had an interactive relationship. The activities of CYPs and T-SOD increased initially with the increase of PAH concentrations, but decreased to the lowest state when PAH concentrations reached the peak value. When the bioaccumulation equilibrium of PAHs was achieved, CYPs and T-SOD activities also reached the steady state. In general, CYPs and T-SOD activities were activated after exposure to PAHs. The decrease of PAH concentrations in zebrafish after the peak value may be attributed to the great drop of ku and the variation of CYPs activities. This study suggests that an interactive relationship exists between bioaccumulation kinetics of PAHs and metabolic enzyme activities in aquatic organisms.

Antioxidant response to metal pollution in Phragmites australis from Anzali wetland

This research was conducted to examine variations of antioxidant enzyme activity in Phragmites australis as a biomarker for metals such as As, Pb, Cu, and Cd. Samples of sediment and plants were collected from 7 stations located in Anzali wetland. Biochemical parameters including Catalase, Peroxidase and Ascorbate Peroxidase activity were analyzed in the roots, stems and leaves of P. australis. The obtained results indicated that there were significant differences among activities of antioxidant enzymes in three organs (p<0.05). Antioxidant enzyme activities in the organs for all studied stations were as the following order: stem<leaf<root. Overall, significant positive correlations were observed among concentrations of metals in sediments and activities of antioxidant enzymes in P. australis. As a result, it can be concluded from this study that antioxidant enzymes are good biomarkers reflecting metal contamination in sediments of Anzali wetland.

Effects of gaps in the forest canopy on soil microbial communities and enzyme activity in a Chinese pine forest

Gaps in the forest canopy play an important role in forest ecology, affecting biological dynamics, nutrient cycling, and plant succession. The influence of gap size on soil microbial communities and soil enzyme activity is poorly understood. Chinese pine (Pinus tabulaeformis) is one of the main afforestation species in northern China, and the creation of artificial gaps in Chinese pine forests is a common silvicultural practice to reduce forest density. We compared the microbial communities and the activity levels of several key enzymes in a Chinese forest among sites with closed canopies and canopies with small gaps (40–50m2) and large gaps (100–120m2) in October 2015, one year after the gaps were created. Soil samples from a depth of 0–10cm were collected, and soil microbial community composition was evaluated using phospholipid fatty acid analysis. The activity levels of soil enzymes were also analyzed. Overall, the amounts of phospholipid fatty acids and the activity level of soil enzymes were highest in the sites with small gaps, followed by sites with closed canopies and sites with large gaps. Gram-positive bacteria were mainly responsible for the difference between microbial communities in sites with small gaps and sites with closed canopies. The activity levels of soil β-glucosidase and l-leucineaminopeptidase were also highest in sites with small gaps and lowest in those with large gaps. Soil acid phosphatase activity was similar in sites with small gaps and closed canopies and was lowest in sites with large gaps. Redundancy analysis indicated that dissolved organic carbon was the common driving factor affecting the variations in microbial communities and enzyme activity. Our results suggest that small gaps are beneficial for microbial communities. Further study of gap treatments is needed to determine the proper gap size for forest management.

β-Carotene 9',10' Oxygenase Modulates the Anticancer Activity of Dietary Tomato or Lycopene on Prostate Carcinogenesis in the TRAMP Model.

The hypothesis that dietary tomato consumption or the intake of the carotenoid lycopene inhibits prostate cancer arose from epidemiologic studies and is supported by preclinical rodent experiments and in vitro mechanistic studies. We hypothesize that variation in activity of carotenoid cleavage enzymes, such as β-carotene 9',10'-oxygenase (BCO2), may alter the impact of dietary tomato and lycopene on prostate carcinogenesis and therefore examined this relationship in the TRAMP model. Starting at 3 weeks of age, TRAMP:Bco2+/+ and TRAMP:Bco2-/- mice were fed either AIN-93G control, or semipurified diets containing 10% tomato powder or 0.25% lycopene beadlets until 18 weeks of age. Both tomato- and lycopene-fed TRAMP:Bco2-/- mice had significantly greater serum concentrations of total, 5-cis, other cis, and all-trans lycopene than TRAMP:Bco2+/+ mice. Tomato- and lycopene-fed mice had a lower incidence of prostate cancer compared with the control-fed mice. Although Bco2 genotype alone did not significantly change prostate cancer outcome in the control AIN-93G-fed mice, the abilities of lycopene and tomato feeding to inhibit prostate carcinogenesis were significantly attenuated by the loss of Bco2 (Pinteraction = 0.0004 and 0.0383, respectively). Overall, dietary tomato and lycopene inhibited the progression of prostate cancer in TRAMP in a Bco2 genotype-specific manner, potentially implicating the anticancer activity of lycopene cleavage products. This study suggests that genetic variables impacting carotenoid metabolism and accumulation can impact anticancer activity and that future efforts devoted to understanding the interface between tomato carotenoid intake, host genetics, and metabolism will be necessary to clearly elucidate their interactive roles in human prostate carcinogenesis. Cancer Prev Res; 10(2); 161-9. ©2016 AACR.

Fertilization alters microbial community composition and functional patterns by changing the chemical nature of soil organic carbon: A field study in a Halosol

Insight into the effects of fertilization on soil organic carbon (C) content and composition, and on microbial community and functions related to C decomposition are being gained, although the linkage between them remains elusive. To address this knowledge gap, a field experiment was conducted under different fertilization regimes, no fertilization (CL), chemical fertilization for 11years (CF), organic fertilization for 6years (OF6) and organic fertilization for 11years (OF11) in an alkaline sandy loam soil. Changes in soil C chemistry using 13C nuclear magnetic resonance (NMR) spectroscopy, microbial community using phospholipid fatty acid (PLFA) analysis and microbial functions using six hydrolase and three oxidoreductase enzyme activities were assessed. Fertilization significantly increased soil carbon contents, microbial biomass, and the abundance of fungi and bacteria. Nevertheless, CF induced a higher fungal-to-bacterial ratio due to a lower response in bacterial than fungal growth. In contrast, OF11 increased bacterial abundance, hydrolase activity, and consequently depleted labile C, resulting in higher alkyl-C contents and alkyl C/O-alkyl C ratios compared to other fertilizer treatments. Changes in microbial community composition and enzyme activity were tightly linked to soil C forms. Alkyl-C, carbonyl-C and ketone-C explained most of the variation (>89%) in soil microbial community, while alkyl-C and ketone-C explained most of the variation (>91%) in enzyme activity. Our results indicate that C composition rather than C quantity shaped soil microbial community composition and enzyme activity, restricting soil C decomposition. The practice of long-term organic fertilizer use is suggested to increase the quantity and recalcitrance of soil organic C.

Seasonal Variations of Soil Microbial PLFAs and Soil Enzyme Activity Under the Citrus Plantation in Mt. Jinyun, Chongqing

The soil microbial community and soil enzyme activity are important parts of soil ecosystem,and they are sensitive to the ecological environment.In this study,citrus plantation in Mt.Jinyun was chosen as the research object.The phospholipid fatty acid (PLFAs) combined with principal component analysis method was used to study the effect of season changes on soil microbial quantity,community structure characteristics and soil enzyme activity at 0-20 cm soil layer under citrus forest.The results obtained from this study were as follows:① The season changes had a significant impact on soil microbes (P<0.05).Moreover,16:0,i17:0,16:1 2OH,18:0,cy19:0ω8c,i17:1ω9c or 16:0 10-methyl were found to be common in all four seasons,and the proportion of each phospholipid fatty acid was 49.57%,41.63%,35.41% and 38.05%,respectively.In various microbial species,the PLFAs content of bacteria was the highest,followed by fungi,and that of actinomycetes was the lowest.Our results revealed that all kinds of micro-organisms showed obvious seasonal variation characteristics.The total PLFAs quantity of citrus forest ranged from 6.868 to 24.085 nmol·g-1,which had a content order of spring >autumn >winter >summer.The PLFAs content of bacteria,G-,G+ and actinomycetes also showed the same variation trend.However,the PLFAs content of fungi showed a different variation trend,i.e.,autumn was the highest,followed by winter and summer,and spring was the lowest.The results suggested that season change also had a significant impact on microbial community functional diversity index.The variation trend of richness index (R) followed the order of spring >winter >autumn >summer.Moreover,the variation trend of diversity index (H') was winter >autumn >spring >summer.Furthermore,the variation trend of evenness index (J) was summer >autumn >winter >spring.The dominance index (D) increased with the change of season.2 Urease showed a change with the seasons following summer >spring >autumn >winter;Soil invertase,soil catalase and acid phosphatase activity changed obviously in autumn,followed by spring,summer,and winter.3 The principal component analysis demonstrated that the PLFAs content of bacteria,G-,G+,actinomycetes and total PLFAs made the greatest contribution to soil fertility followed by that of invertase,catalase,acid phosphatase and fungi.Moreover,our studies showed that the PLFAs content of urease made a minimum contribution to the soil fertility.

Alkaline phosphatase and lactate dehydrogenase enzyme activity in gingival crevicular fluid during orthodontic tooth movements

Background: Bone remodeling is a biologic process involving an acute inflammatory response in periodontal tissues during orthodontic tooth movement. The early response of periodontal tissues to mechanical stress involves metabolic changes that allow tooth movement. Aim of the Study: The aim of the present study was to evaluate the changes in alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) enzyme activity in gingival crevicular fluid (GCF) when forces are applied during initial alignment (Phase 1 [P1]) and retraction (Phase 2 [P2]). Settings and Design: The study was performed in a hospital-based population with an experimental design. Materials and Methods: A total of 17 patients (11–21 years) were included in the study, all requiring first premolar extractions undergoing fixed orthodontic treatment. Maxillary canine and mandibular second molar were used as test tooth (TT) and control tooth (CT) in each patient, respectively. On the 14th day after the start of each phase, 2 μL of GCF was collected from mesial side of both TT and CT for ALP and LDH activity determination using spectrophotometer. Statistical Analysis: Statistical analysis was performed with SPSS (version 13, SPSS Inc., Chicago, USA) package. The significance of differences in both phases at test or, at control site for LDH and ALP enzyme activity, was evaluated by performing Student's paired t-test. The significance of differences in between test and control sites in each phase separately was evaluated by performing Student's unpaired t-test. Results: There was a variation in enzyme activity during orthodontic tooth movement. At TT, there was statistically significant increase in ALP and LDH activity in P2 as compared to P1 with P = 0.005 and P Conclusion: This study concluded that ALP and LDH activity could be successfully estimated in the GCF, and ALP and LDH activity in GCF reflects the biologic activity in the periodontium during orthodontic tooth movements.

Alkaline phosphatase and lactate dehydrogenase enzyme activity in gingival crevicular fluid during orthodontic tooth movement

Background: Bone remodeling is a biologic process involving an acute inflammatory response in periodontal tissues during orthodontic tooth movement. The early response of periodontal tissues to mechanical stress involves metabolic changes that allow tooth movement. Aim of the Study: The aim of the present study was to evaluate the changes in alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) enzyme activity in gingival crevicular fluid (GCF) when forces are applied during initial alignment (P1) and retraction (P2). Settings and Design: The study was performed in a hospital-based population with an experimental design. Materials and Methods: Seventeen participants (11–21 years) included in the study, all requiring first premolar extractions were undergoing fixed orthodontic treatment. Maxillary canine and mandibular second molar were used as test tooth (TT) and control tooth (CT) in each patient, respectively. On 14th day after the start of each phase, 2 μL of GCF was collected from mesial side of both TT and CT for ALP and LDH activity determination using a spectrophotometer. Statistical Analysis: The results were subjected for Student's t-test. Results: There was a variation in enzyme activity during orthodontic tooth movement. At TT, there was a statistically significant increase in ALP and LDH activity in P2 as compared to P1 with P = 0.005 and P ≤ 0.001, respectively. At CT, there was no statistically significant difference in ALP and LDH activity in P1 and P2 with P = 0.054 and P = 0.061, respectively. Conclusion: This study concluded that ALP and LDH activity could be successfully estimated in the GCF, and ALP and LDH activity in GCF reflects the biologic activity in the periodontium during orthodontic tooth movements.

Biochemical changes in the selected tissues of Channa punctatus exposed to Arsenic and its possible revival with turmeric.

Arsenic (As) is a pollutant widely distributed in nature and released into the environment through both geogenic process and anthropogenic disturbances. High concentration of arsenic has been found in many areas of Assam. Fishes are ideal organism for studying the toxicological effects and since they respond to toxicants in a similar way as higher vertebrates including human, hence Channa punctatus was taken as a laboratory animal model. In fishes, arsenic (As) is absorbed via the gills and through contaminated food which is capable of causing disturbance to the antioxidant system. Fish liver is the target organ of arsenic toxicity as it can uptake accumulate and excrete the arsenic. Enzymes are biochemical macromolecule which control metabolic processes of organisms. Since a slight variation in enzyme activities would affect the organism, hence by estimating the enzyme activities in an organism, metabolic disturbances in its body can be easily found. Significant alterations in the total protein and in the marker enzymes AST and ALT were observed in arsenic treated fishes. But when the arsenic treated fishes were exposed to phytochemical products of turmeric extract, a well marked revival from arsenicosis has been observed.

Changes in soil aggregate‐associated enzyme activities and nutrients under long‐term chemical fertilizer applications in a phosphorus‐limited paddy soil

AbstractPaddy soils in subtropical China are usually deficient in phosphorus (P) and require regular application of chemical fertilizers. This study evaluated the effects of chemical fertilizers on the distribution of soil organic carbon (SOC), total nitrogen (N) and available P, and on the activity of the associated enzymes in bulk soil and aggregates. Surface soils (0–20 cm) were collected from a 24‐yr‐old field experiment with five treatments: unfertilized control (CK), N only (N), N and potassium (NK), N and P (NP), and N, P and K (NPK). Undisturbed bulk soils were separated into &gt;2, 1–2, 0.25–1, 0.053–0.25 and &lt;0.053 mm aggregate classes using wet sieving. Results showed that both NP‐ and NPK‐treated soils significantly increased mean weight diameter of aggregates, SOC, available P in bulk soil and aggregates, as compared to CK. Most SOC and total N adhered to macro‐aggregates (&gt;0.25 mm), which accounted for 64–81% of SOC and 54–82% of total N in bulk soil. The activities of invertase and acid phosphatase in the 1–2 mm fraction were the highest under NPK treatment. The highest activity of urease was observed in the &lt;0.053 mm fraction under NP treatment. Soil organic carbon and available P were major contributors to variation of enzyme activities at the aggregate scale. In conclusion, application of NP or NPK fertilizers promoted the formation of soil aggregates, nutrient contents and activities of associated enzymes in P‐limited paddy soils, and thus enhanced soil quality.

The effect of growth hormone replacement on the thyroid axis in patients with hypopituitarism: in vivo and ex vivo studies.

Alterations in the hypothalamic-pituitary-thyroid axis have been reported following growth hormone (GH) replacement. The aim was to examine the relationship between changes in serum concentration of thyroid hormones and deiodinase activity in subcutaneous adipose tissue, before and after GH replacement. A prospective, observational study of patients receiving GH replacement as part of routine clinical care. Twenty adult hypopituitary men. Serum TSH, thyroid hormones - free and total thyroxine (T4) and triiodothyronine (T3) and reverse T3, thyroglobulin and thyroid-binding globulin (TBG) levels were measured before and after GH substitution. Changes in serum hormone levels were compared to the activity of deiodinase isoenzymes (DIO1, DIO2 and DIO3) in subcutaneous adipose tissue. The mean daily dose of growth hormone (GH) was 0·34 ± 0·11 mg (range 0·15-0·5 mg). Following GH replacement, mean free T4 levels declined (-1·09 ± 1·99 pmol/l, P = 0·02). Reverse T3 levels also fell (-3·44 ± 1·42 ng/dl, P = 0·03) and free T3 levels increased significantly (+0·34 ± 0·15 pmol/l, P = 0·03). In subcutaneous fat, DIO2 enzyme activity declined; DIO1 and DIO3 activities remained unchanged following GH substitution. Serum TSH, thyroglobulin and TBG levels were unaltered by GH therapy. In vitro analysis of subcutaneous adipose tissue from hypopituitary human subjects demonstrates that GH replacement is associated with significant changes in deiodinase isoenzyme activity. However, the observed variation in enzyme activity does not explain the changes in the circulating concentration of thyroid hormones induced by GH replacement. It is possible that deiodinase isoenzymes are differentially regulated by GH in other tissues including liver and muscle.

Relationships between soil–litter interface enzyme activities and decomposition in Pinus massoniana plantations in China

Enzyme activities in decomposing litter are directly related to the rate of litter mass loss and have been widely accepted as indicators of changes in belowground processes. Studies of variation in enzyme activities of soil–litter interface and its effects on decomposition are lacking. Evaluating enzyme activities in this layer is important to better understand energy flow and nutrient cycling in forest ecosystems. Litter decomposition and the seasonal dynamics of soil–litter enzyme activities were investigated in situ in 20- (younger) and 46-year-old (older) Pinus massoniana stands for 540 days from August 2010 to March 2012 by litterbag method. We measured potential activities of invertase, cellulase, urease, polyphenol oxidase, and peroxidase in litter and the upper mineral soils, and evaluated their relationships with the main environment factors. Remaining litter mass was 57.6 % of the initial weights in the younger stands and 61.3 % in the older stands after 540-day decomposition. Levels of enzyme activity were higher in the litter layer than in the soil layer. Soil temperature, litter moisture, and litter nitrogen (N) concentration were the most important factors affecting the enzyme activities. The enzyme activity showed significantly seasonal dynamics in association with the seasonal variations in temperature, water, and decomposition stages. Remaining litter dry mass was found to be significantly linearly correlated with enzyme activities (except for litter peroxidase), which indicates an important role of enzyme activity in the litter decomposition process. Our results indicated the important effects of biotic (litter N) and abiotic factors (soil temperature and litter moisture) on soil–litter interface enzyme activities. Overall significant linear relationship between remaining dry mass and enzyme activities highlighted the important role of enzyme activity in affecting litter decomposition processes, which will further influence nutrient cycling in forest ecosystems. Our results contributed to the better understanding of the mechanistic link between upper soil–litter extracellular enzyme production and litter decomposition in forest ecosystems.

Season, but not experimental warming, affects the activity and temperature sensitivity of extracellular enzymes

Climate change may affect the microbial production and temperature sensitivity of extracellular enzymes that release carbon (C) and nutrients from soil organic matter. We measured the response of six hydrolytic enzymes involved in C, nitrogen (N), and phosphorus (P) degradation to experimental warming in a mixed-deciduous forest persisting on highly-weathered Ultisols (Whitehall Forest, Georgia, US). We found that warming produced no consistent enzyme response. However, we observed significant seasonal variation in enzyme activities, temperature sensitivities and elemental enzyme ratios (C:N and C:P). Seasonal differences in enzyme activity and temperature sensitivity were best explained by soil moisture and temperature. Our results suggest that seasonal dynamics in soil microclimate, organic matter supply, and microbial demand exert more control on enzyme dynamics than does a uniform increase in soil temperature.

Predictors of Variation in CYP2A6 mRNA, Protein, and Enzyme Activity in a Human Liver Bank: Influence of Genetic and Nongenetic Factors.

Cytochrome P450 2A6 CYP2A6: metabolizes several clinically relevant substrates, including nicotine, the primary psychoactive component in cigarette smoke. Smokers vary widely in their rate of inactivation and clearance of nicotine, altering numerous smoking phenotypes. We aimed to characterize independent and shared impact of genetic and nongenetic sources of variation in CYP2A6 mRNA, protein, and enzyme activity in a human liver bank (n = 360). For the assessment of genetic factors, we quantified levels of CYP2A6, cytochrome P450 oxidoreductase (POR), and aldo-keto reductase 1D1 (AKR1D1) mRNA, and CYP2A6 and POR proteins. CYP2A6 enzyme activity was determined through measurement of cotinine formation from nicotine and 7-hydroxycoumarin formation from coumarin. Donor DNA was genotyped for CYP2A6, POR, and AKR1D1 genetic variants. Nongenetic factors assessed included gender, age, and liver disease. CYP2A6 phenotype measures were positively correlated to each other (r values ranging from 0.47-0.88, P < 0.001). Female donors exhibited higher CYP2A6 mRNA expression relative to males (P < 0.05). Donor age was weakly positively correlated with CYP2A6 protein (r = 0.12, P < 0.05) and activity (r = 0.20, P < 0.001). CYP2A6 reduced-function genotypes, but not POR or AKR1D1 genotypes, were associated with lower CYP2A6 protein (P < 0.001) and activity (P < 0.01). AKR1D1 mRNA was correlated with CYP2A6 mRNA (r = 0.57, P < 0.001), protein (r = 0.30, P < 0.001), and activity (r = 0.34, P < 0.001). POR protein was correlated with CYP2A6 activity (r = 0.45, P < 0.001). Through regression analyses, we accounted for 17% (P < 0.001), 37% (P < 0.001), and 77% (P < 0.001) of the variation in CYP2A6 mRNA, protein, and activity, respectively. Overall, several independent and shared sources of variation in CYP2A6 activity in vitro have been identified, which could translate to variable hepatic clearance of nicotine.

Modulation of the Activity of Enzymes Involved in Carbohydrate Metabolism during Flower Development of Grapevine ( Vitis Vinifera L. )

Abstract In order to further understand the relationships between flower development and sugar metabolism in grapevine, the fluctuations of both starch and sucrose contents were compared with the activity of their related enzymes, in the inflorescences, from the appearance of flower buds until the fruit set. The measurements were carried out on GW and PN cvs., differing in their sensitivity to the flower abscission. The meiosis stage, which is a crucial step for the achievement of sexual reproduction, was particularly screened. Results indicate that the main differences in carbohydrate metabolism occur during meiosis. In the inflorescences of both cvs., variations of enzyme activities can be correlated with their differences in sugar contents. Starch fluctuations were mediated by the activity of amylases (alpha- and beta-) rather than by starch synthase. Changes of sucrose were correlated with the activity of Starch Synthase degradation, both cytoplasmic and wall-bounded invertases but not with the Sucrose Phosphate Synthase activity. Finally, the significant increase of sucrose degrading enzyme activities, such as Starch Synthase degradation, cytoplasmic invertase, and wall-bound invertase, observed after the flower separating stage was interpreted as the first sign of the strong physiological modifications occurred in the ovaries between fertilization and the fruit formation

Endosperm Carotenoid Concentrations in Wheat are Better Correlated with PSY1 Transcript Levels than Enzyme Activities

Phytoene synthase (PSY) catalyzes a key reaction in the biosynthesis of carotenoids, which are major contributors of grain yellow pigment content (GYPC) in wheat (Triticum spp.). Although quantitative trait loci (QTL) for GYPC have been linked to PSY1 homoeologs in tetraploid and hexaploid wheat, the underlying molecular and biochemical mechanisms for such associations are not well understood. Functional characterization of wheat PSY1 homoeologs indicated that variations in PSY1 homoeolog enzyme activities did not correspond to different levels of GYPC in the wild‐type tetraploid and hexaploid wheat genotypes analyzed. However, a correlation between PSY1 homoeolog expression and carotenoid accumulation in grain endosperm was evident, suggesting that GYPC is at least partially modulated by transcriptional regulation of PSY1 homoeologs in wheat grains. Further promoter analysis of PSY‐A1 homoeologs with diverse expression profiles in three wheat genotypes revealed not only potential motifs for light and hormonal responses but also new candidate cis‐regulatory elements. Overall, the knowledge on the association of PSY1 homoeolog expression and GYPC can be directly applied to breeding tetraploid and hexaploid wheat varieties with desirable carotenoid levels.

Variations of soil microbial community composition and enzyme activities with different salinities on Yuyao coast, Zhejiang, China

In October 2015, soil samples with different salinity were collected in a coast area in Yuyao, Zhejiang, and soil microbial community composition, soil catalase, urease activities, as well as soil physical and chemical properties were studied. The results showed that Nitrospira took absolute advantage in the bacterial community, and showed good correlations to total potassium. Cladosporium and Fusarium were predominant in the fungal community. Meanwhile, Cladosporium was related to soil urease and total nitrogen, and same correlation was found between Fusarium and soil urease. Catalase activity ranged from 3.52 to 4.56 mL·g-1, 3.08 to 4.61 mL·g-1 and 5.81 to 6.91 mL·g-1 for soils with heavy, medium and weak salinity, respectively. Catalase activity increased with the soil layer deepening, which was directly related to soil total potassium, and indirectly related to pH, organic matter, total nitrogen and total phosphorus through total potassium. Soil urease activity ranged among 0.04 to 0.52 mg·g-1, 0.08 to 1.07 mg·g-1 and 0.27 to 8.21 mg·g-1 for each saline soil, respectively. Urease activity decreased with soil layer deepening which was directly related to soil total nitrogen, and was indirectly related to pH, organic matter and total potassium through total nitrogen. The total phosphorus was the largest effect factor on the bacterial community CCA ordination, and the urease was on fungal community.