Immunoglobulin isotype distribution of malaria-specific antibodies produced during infection with Plasmodium chabaudi adami and Plasmodium yoelii

The antibody response of mice to Plasmodium chabaudi adami and Plasmodium yoelii has been compared using a solid phase isotype-specific radioimmunoassay and sodium dodecyl sulfatepolyacrylamide gel electrophoresis. Serological cross-reactivity between these parasites was substantial. Studies using a radioimmunoassay detecting all classes of malaria-specific antibody demonstrated that during the early part of infection it was not possible to distinguish between homologous and heterologous reactions. Immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that 50% or more of the protein antigens detected were apparently shared by both parasites although the intensity of bands was always greater with homologous reactions. However, the distribution of isotypes in the antibody (Ab) response differed in the two infections. P. chabaudi infections were characterized by a predominant and persistent IgM response, moderate IgG₂ and IgG₃ and little significant IgG₁ response during a primary infection. By contrast, IgM antibodies were transient in P. yoelii infection, IgG₂ was the predominant isotype, and both IgG₁ and IgG₃ antibodies were present during a primary infection. These differences in isotypes were also detected when sera were tested on the heterologous antigen extracts suggesting that antigens shared by P. chabaudi and P. yoelii do not necessarily induce similar antibody responses in the two infections.     

迁地保育林麝体况及影响因素

通过建立基于外貌性状的量化性体况评分标准,于2012年7—10月间对四川马尔康麝场的586头圈养林麝(雌麝299头,雄麝287头)进行了体况评分,并分析了相关变量对林麝体况得分的效应,结果表明:马尔康麝场圈养林麝的体况评分均值为3.49(±0.02,n=586),大部分林麝(59.56%,n=349)的体况评分高于均值。雌麝体况评分均值(3.50±0.02,n=299)略高于雄麝(3.49±0.03,n=287)(P0.05),成体麝体况评分(3.59±0.02,n=291)极显著地高于老龄林麝(3.38±0.09,n=27)和亚成林麝(3.35±0.03,n=184)(P0.01)。林麝的体况得分与其年龄相关不显著(r=0.07,P0.05),但亚成体及成体麝的体况评分与其年龄间的相关极显著(亚成体r=0.19,P0.01;成体r=-0.16,P0.01),而老龄麝体况评分与其年龄略呈负相关(r=-0.23,P0.05)。S模型y=e1.2811-0.0885/a(R2=0.051,df=500,F=26.74,P0.01)可近似拟合林麝体况得分和年龄的关系。此外,马尔康麝场泥地基底的改装圈舍中的林麝体况(3.52±0.03,n=197)显著优于原装青砖圈舍林麝评分(3.47±0.02,n=389)(P0.05)。     

Quantitation of specific igg,iga, and igm antibodies directed against four species of basidiomycetes

Specific IgG, IgA, and IgM antibodies to aqueous extracts of Coprinus quadrifidus, Pleurotus ostreatus, Calvatia cyathiformis, and Psilocybe cubensis were assessed using an enzyme linked immunosorbent assay (ELISA) in basidiomycete radioallergosorbent test (RAST) positive atopics (Gr 1), RAST negative atopics (Gr 2), and RAST negative, non-atopics (Gr 3). ELISA values are presented as mean optical density ± sem. For C. quadrifidus, elevated specific IgA levels (0.33 ± 0.08, p=0.02) were shown in Gr 1, as compared with Gr 2 (0.129 ± 0.04) and Gr 3 (0.163 ± 0.02). For P. ostreatus, specific IgA levels (0.534 ± 0.15) were also elevated (p=0.003) in Gr 1, when compared with Gr 2 (0.389 ± 0.01) and Gr 3 (0.121 ± 0.03). For C. cyathiformis and P. cubensis, specific IgA levels in Gr 1 were higher than those in Gr 2 and Gr 3, however, these were not significantly elevated. For P. cubensis, specific IgM levels were elevated (p=0.03) in Gr 2 (0.666 ± 0.081) when compared with Gr 1 (0.505 ± 0.056) and Gr 3 (0.413 ± 0.045), respectively. No other differences were observed among the groups in any species tested. These data confirm that isotypes, other than IgE, are produced against Basidiomycetes, also, RAST positive, atopic subjects have a tendency to make higher levels of specific IgA, than RAST negative subjects.     

Antibodies reacting to mimotopes of Simian virus 40 large T antigen,the viral oncoprotein,in sera from children

Recent data indicate that the Simian virus 40 (SV40) infection appears to be transmitted in humans independently from early SV40-contaminated antipolio vaccines. Serum antibodies against SV40 large T antigen (Tag) were analyzed in children/adolescents and young adults. To investigate antibodies reacting to SV40 Tag antigens, serum samples ( n = 812) from children and young adults were analyzed by indirect ELISAs using specific SV40 Tag mimotopes. Mimotopes were synthetic peptides corresponding to SV40 Tag epitopes. In sera ( n = 412) from healthy children up to 17 years old, IgG antibodies against SV40 Tag mimotopes reached an overall prevalence of 15%. IgM antibodies against SV40 Tag were detected in sera of children 6–8 months old confirming and extending the knowledge that SV40 seroconversion occurs early in life. In children/adolescents affected by different diseases ( n = 180) SV40 Tag had a prevalence of 18%, being the difference no significant compared to healthy subjects ( n = 220; 16%) of the same age. Our immunological data indicate that SV40 circulates in children and young adults, both in healthy conditions and affected by distinct diseases. The IgM detection in sera from healthy children suggests that the SV40 infection/seroconversion occurs early in life (>6 months). Our immunological data support the hypothesis that SV40, or a closely related still unknown polyomavirus, infects humans. The SV40 seroprevalence is lower than common polyomaviruses, such as BKPyV and JCPyV, and other new human polyomaviruses. In addition, our immunological surveillance indicates a lack of association between different diseases, considered herein, and SV40.     

Evaluation of downward movements of Japanese eel Anguilla japonica inhabiting brackish water areas

This study evaluated the size and age distributions and otolith microchemistry of the Japanese eel Anguilla japonica in freshwater and brackish water areas in the Aki and Tsuchikawa rivers for 1 year, and in brackish water areas in the Asahi River for 3 years to understand the movements of Japanese eels between continental habitats of different salinity after recruitment (n = 759). For all three rivers, the total length (L_T) and age distributions were consistent; yellow eels captured in the upper brackish water (Aki River: 353.5 ± 77.4 mm and 3.0 ± 0.8 years; Tsuchikawa River: 287.7 ± 87.3 mm and 3.7 ± 1.3 years; Asahi River: 418.2 ± 112.1 mm and 4.2 ± 1.7 years) were smaller and younger than not only those in the fresh water of the two rivers but also those in the lowest brackish water sampling areas (Aki River: 436.0 ± 71.6 mm and 3.8 ± 1.1 years; Tsuchikawa River: 370.9 ± 121.7 mm and 4.9 ± 2.3 years; Asahi River: 558.5 ± 85.9 mm and 5.7 ± 1.7 years). In the Asahi River, these tendencies were found throughout the 3 years. Otolith analysis indicated that the majority of the eels captured in the lowest brackish water areas had moved down from upstream. These results suggest that Japanese eels inhabiting saline water generally move from the upper estuary as they grow. The upper estuary can be an important area for the management of this species because these eels spend their early continental growth life there.     

Hybrid immunoglobulin isotypes of identical specificity produced by genetic recombination in Escherichia coli and expression in lymphoid cells

We have produced a series of hybrid IgG₁-IgG_2a mouse immunoglobulins with identical light chains (L) and variable regions to facilitate the identification of structural features associated with functional differnces between immunoglobulin isotypes. Hybrid heavy chain (H) constant region gene segments were generated by genetic recombination in Escherichia coli between plasmids carrying mouse γ¹ and γ^2a gene segments. Crossovers occured through out these segments although the frequency was highest in regions of high nucleotide sequence homology. Eleven variant immunoglobulins produced by transfected hybridoma cell lines are assembled into H₂L₂ tetramers and properly glycosylated. In addition, all 11 immunoglbulins have identical antigen combining sites specific for the fluorescent hapten ε-dansyll-L-lysine. Protein A binding was used as probe of the structural integrity of the Fc portion of the variant antibodies. Differeneces in protein A binding between IgG₁ and IgG_2a appear to be due to amino acid differances at postions 252 (Thr→Met) and 254 (Thr→Ser) of the heavy chain (EU numbering).     

Life‐history traits of the long‐nosed skate Dipturus oxyrinchus

This work investigates life‐history traits of the long‐nosed skate Dipturus oxyrinchus, which is a common by‐catch in Sardinian waters. The reproductive variables were analysed from 979 specimens sampled during scientific and commercial hauls. Females (10·4–117·5 cm total length, L_T) attained larger sizes than males (14·5–99·5 cm L_T). To evaluate age and growth, a sub‐sample of 130 individuals (76 females and 54 males) were used. The age was estimated by annuli counts of sectioned vertebral centra. Four models were used for the length‐at‐age data: the von Bertalanffy, the exponential, the Gompertz and the logistic functions. According to the Akaike's information criterion, the Gompertz model seemed to provide the best fitting curve (L_∞ mean ± s.e. : 127·55 ± 4·90 cm, k: 0·14 ± 0·09, IP: 3·97 ± 0·90 years). The oldest female and male were aged 17 (115·5 cm L_T) and 15 years (96·0 cm L_T), respectively. Lengths at maturity were 103·5 cm for females and 91·0 cm for males, corresponding to 90% of the maximum observed length in both sexes. The monthly distribution of maturity stages highlighted an extended reproductive cycle, with spawning females and active males being present almost throughout the year, as confirmed by the gonado‐somatic index. Ovarian fecundity reached a maximum of 26 yolked follicles with a mean ± s.e. size of 19·7 ± 6·5 mm.     

北桑寄生产黄酮内生菌的分离鉴定及其抗氧化和抑菌活性评价

【背景】北桑寄生(Loranthus tanakae)植物中黄酮类化合物成分含量较高,生物活性较好。由于植物资源短缺,导致其生物活性成分的研究受限。【目的】从北桑寄生中分离、筛选和鉴定产黄酮类化合物的内生菌,并评估其体外抗氧化和抑菌活性。【方法】以北桑寄生枝条为研究对象分离内生菌,通过显色反应和薄层色谱法(thin-layer chromatography,TLC)筛选产黄酮类化合物的内生菌,并采用NaNO₂-Al (NO₃)₃比色法测定其总黄酮含量。利用清除自由基和抑菌的体外实验来初步评估产黄酮内生菌的生物活性。【结果】共筛选出4株产黄酮内生菌,其中3株为内生真菌,1株为内生细菌,通过形态学和分子生物学方法将其分别鉴定为Botryosphaeria sp.(ZC020)、Phoma sp.(ZZ105)、Nemania sp.(ZS042)和Pseudomonas sp.(ZC026)。4株菌中ZC020和ZS042的总黄酮含量较高,分别为(44.58±0.72) mg/L和(31.98±0.18) mg/L (P<0.05,n=3),并且ZS042可产生与北桑寄生植物相同类型的黄酮类化合物。ZC026和ZS042表现出优异的抗氧化活性,其1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)和2,2''-联氮-二(3-乙基苯并噻唑啉-6-磺酸)二铵盐[2,2''-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt,ABTS]自由基清除率分别为72.85%±0.66%(ZC026)、57.01%±0.89%(ZS042)和85.36%±0.75%(ZC026)、88.17%±0.15%(ZS042)(P<0.05,n=3)。ZZ105对革兰氏阳性菌和革兰氏阴性菌均有抑制作用。【结论】从北桑寄生枝条中分离出4株产黄酮类化合物的内生菌,其中有一株为内生细菌。这项工作为北桑寄生黄酮类化合物的生产提供了新的资源,也为其他珍稀药用植物和材料的开发和保护提供了参考。     

Life history of an unusual marine fish: survival, growth and movement patterns of Hippocampus guttulatus Cuvier 1829

The life history of the long‐snouted seahorse Hippocampus guttulatus was characterized using mark‐recapture data collected within a focal study site and catch data from 53 additional sites in the Ria Formosa coastal lagoon, southern Portugal. Population structure in benthic habitats was characterized by high local densities (0·3–1·5 m^?2), equal sex ratios and few juveniles <70 mm. Adult H. guttulatus maintained small (19·9 ± 12·4 m²), strongly overlapping home ranges during multiple reproductive seasons. Recruited (benthic) juveniles exhibited significantly lower site fidelity than adults. A Ford‐Walford plot of standard length (L_S) at time t against L_S measured during the previous year from tagged juveniles and adults led to estimates of the von Bertalanffy parameters K = 0·571 and L_∞ = 197·6 mm. The growth rate of planktonic juveniles (inferred from previous studies), was greater than predicted by the von Bertalanffy model, providing evidence of an ontogenetic shift in growth trajectory. The instantaneous rate of natural mortality, M, ranged from 1·13 to 1·22 year^?1(annual survival rate = 29·4–32·2%). Sexes did not differ in movement, growth or survival patterns. On average, H. guttulatus measured 12·2 ± 0·8 mm at birth. Planktonic juveniles recruited to vegetated habitat at 96·0 ± 8·0 mm (0·25 years), had mature brood pouches (males only) at 109·4 mm (0·49 years), began maintaining home ranges and reproducing at 125–129 mm (0·85–0·94 years), and lived for 4·3–5·5 years. Early age at maturity, rapid growth rates, and short generation times suggested that H. guttulatus may recover rapidly when direct (e.g. exploitation) and indirect (e.g. by‐catch and habitat damage) effects of disturbance cease, but may be vulnerable to extended periods of poor recruitment.     

The association of intestinal parasitosis and H. pylori infection in children and adults from a Mexican community with high prevalence of parasitosis

Background. ABSTExperimental evidences have suggested that a Th1 response is unable to eliminate H. pylori colonization; whereas a Th2 response, like the one induced by vaccination, reduces H. pylori infection in animal models. Some parasitic infections induce a polarized Th2 response, which theoretically would favor a reduced H. pylori prevalence. The aim of this work was to study the possible association between parasitic infections and H. pylori prevalence. Materials and Methods. The study population included 120 children and 188 adults from a low socioeconomic level village. H. pylori prevalence was determined in serum by ELISA; parasitic infections were identified in feces by microscopic examination; and total serum IgE levels, as an indirect indicator of some parasitic infections, were determined by ELISA. Results. In children, H. pylori prevalence was no different between those with and without intestinal parasitic infection. By contrast, adults with intestinal parasitic infection had a significantly lower H. pylori prevalence than adults without parasites (62.6% compared with 80.4%; p = 0.006, OR 2.45). Also in adults, but not in children, total IgE levels were significantly higher in those without H. pylori infection than in those with H. pylori infection (p < 0.001). Conclusions. Intestinal parasitic infections and serum IgE levels showed an age‐dependent association with H. pylori prevalence. In adults, but not in children, intestinal parasitic infections and increased IgE levels where associated with a reduced H. pylori prevalence.     

Age,growth, maturity and extinction risk of an exploited and endangered skate,Atlantoraja castelnaui,from off Uruguay and northern Argentina

The spotback skate Atlantoraja castelnaui (Arhynchobatidae) is a large and threatened skate species subjected to fishing pressure, endemic to the Southwest Atlantic that occurs from Rio de Janeiro, Brazil, to San Jorge Gulf, Argentina. The age, growth, age at maturity and the maximum intrinsic rate of population increase r_max of A. castelnaui were studied using 152 specimens collected from off Uruguay and north Argentina (35°–42° S), between June 2013 and February 2020. Vertebrae from 143 individuals were used for ageing (females: n = 83, size range 404–1300 mm total length, TL; males: n = 60, size range 400–1270 mm TL). Maximum ages determined for females and males were 30 and 28 years, respectively. To fit growth models, non-linear and Bayesian estimation approaches were considered. For the first approach, a set of four candidate growth (size-at-age) models were fitted: three-parameter von Bertalanffy, two-parameter von Bertalanffy with fixed L₀, Gompertz and Logistic. In the second approach, von Bertalanffy, Gompertz and Logistic were fitted. For non-linear estimation, model selection indicated that the entire set of candidate growth models were supported by the data. The von Bertalanffy was selected as the best model for Bayesian estimation. There were no differences in growth between sexes. For the sexes combined, the von Bertalanffy growth model by Bayesian method was considered the most adequate to describe the growth of A. castelnaui (growth mean parameters ± S.D. : L_∞ = 1210.29 ± 40.68 mm; k = 0.12 ± 0.01 years⁻¹; L₀ = 179.20 ± 11.62 mm). The age at maturity was estimated at 16.21 and 14.04 years for females and males, respectively. The maximum intrinsic rate of population increase r_max was estimated as 0.252 years⁻¹. Life-history traits and r_max provided in the present study suggest that this species has a relatively low productivity and may be vulnerable to an intense fishing pressure.     

Energy Intake and Meal Portions: Associations with BMI Percentile in U.S. Children

Objective: We examined relationships of eating patterns and reported energy intake (rEI) with BMI percentile in U.S. children. Research Methods and Procedures: Two 24‐hour dietary recalls from the Continuing Surveys of Food Intakes by Individuals 1994 to 1996 and 1998 (1005 boys, 990 girls) were averaged, and children were categorized into three age groups: 3 to 5 years (n = 1077), 6 to 11 years (n = 537), and 12 to 19 years (n = 381). Physiologically implausible reports due to reporting bias or abnormal intake (rEI outside ±18% to 23% of predicted energy requirements; pER) were identified. Results: rEI averaged 109 ± 34% and 100 ± 10% of pER in the total and plausible samples, respectively. EI was overreported more in younger children and underreported more in overweight older children. Children with plausible rEI (45.3% of sample) averaged 4.7 eating occasions/d, 589 kcal/meal, 223 kcal/snack, and 2038 kcal/d. rEI was not associated with BMI percentile in the total sample. In the plausible sample, rEI, meal portion size, and meal energy were positively associated with BMI percentile in boys 6 to 11 years and in children 12 to 19 years. No relationships were found in children 3 to 5 years and girls 6 to 11 years. Relationships were more consistent and stronger in the plausible compared with the total sample. Discussion: Excluding implausible dietary reports may be necessary for discerning dietary associations with BMI percentile. EI and meal, but not snack, patterns may play a quantitatively greater role in weight regulation as children age.     

A modified hybridoma technique for production of monoclonal antibodies having desired isotypes

In the present study, we describe a modified hybridoma technique for production of monoclonal antibodies (mAbs) having a desired isotype. Mice were immunized with the antigen of interest. After having reached a high antibody titer, cells expressing IgM or IgG molecules were isolated from spleen cells of the immunized mice using a Magnetic Cell Sorting System. The isolated cells were fused with myeloma cells using the conventional fusion protocol. With the isolated IgM⁺ spleen cells, more than 75% (85 ± 7%; means ± SD) were IgM producing cells and a large number of IgM mAbs specific to the protein of interest were obtained. With the isolated IgG⁺ spleen cells, 41 ± 40% of the generated hybridomas produced IgG antibody and no IgM producing hybridoma was generated. A large number of IgG mAbs specific to the protein of interest could be produced. The results indicate that the generated hybridomas produce corresponding antibody isotypes as expressed on the surface of their starting cells. The technique that we have developed will be very useful for production of desired mAbs having a specific isotype.     

Life history of the river goby Glossogobius callidus (Teleostei: Gobiidae)

The river goby Glossogobius callidus is native to freshwater and estuarine habitats in South Africa. Individuals [21.1–144.4 mm total length (L_T)] were sampled from impoundments in the Sundays River Valley, Eastern Cape, from February 2014 to March 2015. The largest female was 137.2 mm L_T, and the largest male was 144.4 mm L_T. Length-at-50% maturity was 75.2 ± 2.1 mm L_T for males and 76.2 ± 2.0 mm L_T for females. Absolute fecundity was 1028.2 ± 131.7 oocytes per fish, and relative fecundity was 50.1 ± 18.1 oocytes per gram. The spawning season extended from October to December. Fish were aged using sectioned sagittal otoliths. The growth zone periodicity was validated using edge analysis. Longevity was more than 7 years for females and more than 6 years for males. Length-at-age was similar for the two sexes and was best described using the von Bertalanffy growth model as L_t = 74.7(1 − e^{–1.0(t + 0.1)}) mm L_T for the entire population. Using the population age structure, the mortality rate was estimated at 1.3 per year.     

Anti-allergic effects of His-Ala-Gln tripeptide in vitro and in vivo

We examined the inhibitory effects of HAQ (His-Ala-Gln) peptide on type-1 allergy in vitro and in vivo. HAQ peptide inhibited β-hexosaminidase release and intracellular Ca²⁺ levels of rat basophilic leukemia RBL-2H3 cells. Oral administration of a HAQ peptide-added diet (1 mg/mouse/administration) to C3H/HeJ mice for 14 days led to significant suppression of allergic symptoms, but did not reduce allergen-specific IgE or IgG₁.     

Late circadian phase in adults and children is correlated with use of high color temperature light at home at night

Light is the strongest synchronizer of human circadian rhythms, and exposure to residential light at night reportedly causes a delay of circadian rhythms. The present study was conducted to investigate the association between color temperature of light at home and circadian phase of salivary melatonin in adults and children. Twenty healthy children (mean age: 9.7 year) and 17 of their parents (mean age: 41.9 years) participated in the experiment. Circadian phase assessments were made with dim light melatonin onset (DLMO). There were large individual variations in DLMO both in adults and children. The average DLMO in adults and in children were 21:50 ± 1:12 and 20:55 ± 0:44, respectively. The average illuminance and color temperature of light at eye level were 139.6 ± 82.7 lx and 3862.0 ± 965.6 K, respectively. There were significant correlations between color temperature of light and DLMO in adults (r = 0.735, p < 0.01) and children (r = 0.479, p < 0.05), although no significant correlations were found between illuminance level and DLMO. The results suggest that high color temperature light at home might be a cause of the delay of circadian phase in adults and children.     

Interactions of tropospheric CO2 and O3 enrichments and moisture variations on microbial biomass and respiration in soil

Soil microbial biomass C (C_mic) is a sensitive indicator of trends in organic matter dynamics in terrestrial ecosystems. This study was conducted to determine the effects of tropospheric CO₂ or O₃ enrichments and moisture variations on total soil organic C (C_org), mineralizable C fraction (C_Min), C_mic, maintenance respiratory (qCO₂) or C_mic death (qD) quotients, and their relationship with basal respiration (BR) rates and field respiration (FR) fluxes in wheat‐soybean agroecosystems. Wheat (Triticum aestivum L.) and soybean (Glycine max. L. Merr) plants were grown to maturity in 3‐m dia open‐top field chambers and exposed to charcoal‐filtered (CF) air at 350 μL CO₂ L^?1; CF air + 150 μL CO₂ L^?1; nonfiltered (NF) air + 35 nL O₃ L^?1; and NF air + 35 nL O₃ L^?1 + 150 μL CO₂ L^?1 at optimum (? 0.05 MPa) and restricted soil moisture (? 1.0 ± 0.05 MPa) regimes. The + 150 μL CO₂ L^?1 additions were 18 h d^?1 and the + 35 nL O₃ L^?1 treatments were 7 h d^?1 from April until late October. While C_org did not vary consistently, C_Min, C_mic and C_mic fractions increased in soils under tropospheric CO₂ enrichment (500 μL CO₂ L^?1) and decreased under high O₃ exposures (55 ± 6 nL O₃ L^?1 for wheat; 60 ± 5 nL O₃ L^?1 for soybean) compared to the CF treatments (25 ± 5 nL O₃ L^?1). The qCO₂ or qD quotients of C_mic were also significantly decreased in soils under high CO₂ but increased under high O₃ exposures compared to the CF control. The BR rates did not vary consistently but they were higher in well‐watered soils. The FR fluxes were lower under high O₃ exposures compared to soils under the CF control. An increase in C_mic or C_mic fractions and decrease in qCO₂ or qD observed under high CO₂ treatment suggest that these soils were acting as C sinks whereas, reductions in C_mic or C_mic fractions and increase in qCO₂ or qD in soils under elevated tropospheric O₃ exposures suggest the soils were serving as a source of CO₂.     

毛白杨细胞质抗坏血酸过氧化物酶基因的克隆及表达分析

利用同源克隆技术得到1个毛白杨细胞质抗坏血酸过氧化物酶基因,命名为PcAPX。该基因编码249个氨基酸残基,预测分子量为33.01kD。采用原核表达技术在大肠杆菌中表达并纯化该蛋白并进行酶活性分析,结果表明:重组PcAPX蛋白对抗坏血酸(AsA)和过氧化氢(H2O2)有很高的活性,其对抗坏血酸的米氏常数(Km)和最大反应速度(Vmax)分别为(0.71±0.03)mmol·L-1和(0.41±0.02)mmol·L-1·min-1·mg-1;对过氧化氢的Km和Vmax分别为(0.60±0.21)mmol·L-1和(0.35±0.12)mmol·L-1·min-1·mg-1,表明PcAPX对AsA和H2O2拥有较高的催化底物的能力和催化效率。利用实时定量RT-PCR分析毛白杨PcAPX基因的表达模式,结果表明其在老叶中表达量高于新叶、韧皮部、形成层和根部。该研究结果将进一步促进毛白杨APX基因家族成员参与植物生长调控的研究。     

Maximum sustainable speed, energetics and swimming kinematics of a tropical carangid fish, the green jack Caranx caballus

Maximum sustained swimming speeds, swimming energetics and swimming kinematics were measured in the green jack Caranx caballus (Teleostei: Carangidae) using a 41 l temperature‐controlled, Brett‐type swimming‐tunnel respirometer. In individual C. caballus [mean ±s.d. of 22·1 ± 2·2 cm fork length (L_F), 190 ± 61 g, n = 11] at 27·2 ± 0·7° C, mean critical speed (U_crit) was 102·5 ± 13·7 cm s^?1 or 4·6 ± 0·9 L_F s^?1. The maximum speed that was maintained for a 30 min period while swimming steadily using the slow, oxidative locomotor muscle (U_max,c) was 99·4 ± 14·4 cm s^?1 or 4·5 ± 0·9 L_F s^?1. Oxygen consumption rate (M in mg O₂ min^?1) increased with swimming speed and with fish mass, but mass‐specific M (mg O₂ kg^?1 h^?1) as a function of relative speed (L_F s^?1) did not vary significantly with fish size. Mean standard metabolic rate (R_S) was 170 ± 38 mg O₂ kg^?1 h^?1, and the mean ratio of M at U_max,c to R_S, an estimate of factorial aerobic scope, was 3·6 ± 1·0. The optimal speed (U_opt), at which the gross cost of transport was a minimum of 2·14 J kg^?1 m^?1, was 3·8 L_F s^?1. In a subset of the fish studied (19·7–22·7 cm L_F, 106–164 g, n = 5), the swimming kinematic variables of tailbeat frequency, yaw and stride length all increased significantly with swimming speed but not fish size, whereas tailbeat amplitude varied significantly with speed, fish mass and L_F. The mean propulsive wavelength was 86·7 ± 5·6 %L_F or 73·7 ± 5·2 %L_T. Mean ±s.d . yaw and tailbeat amplitude values, calculated from lateral displacement of each intervertebral joint during a complete tailbeat cycle in three C. caballus (19·7, 21·6 and 22·7 cm L_F; 23·4, 25·3 and 26·4 cm L_T), were 4·6 ± 0·1 and 17·1 ± 2·2 %L_T, respectively. Overall, the sustained swimming performance, energetics, kinematics, lateral displacement and intervertebral bending angles measured in C. caballus were similar to those of other active ectothermic fishes that have been studied, and C. caballus was more similar to the chub mackerel Scomber japonicus than to the kawakawa tuna Euthynnus affinis.