High-level secretory expression, purification and characterization of Ailuropoda melanoleuca growth hormone in Pichia pastoris

Growth hormone is one of the most important hormones, which is involved in many reproductive processes of giant panda Ailuropoda melanoleuca. In this study, the mature peptide of A. melanoleuca growth hormone (AmGH) was successfully expressed and secreted in Pichia pastoris under the control of AOX1 promoter. The expression condition for AmGH in P. pastoris, such as the expression time, pH value and methanol concentration in the BMMY were optimized and the AmGH expression level is about 100 mg/L using GS115 recombinant under optimized condition (96 h of 1.5% methanol induction). The secreted nascent AmGH were purified using ammonium sulfate fractionation. The mature AmGH protein exhibited a molecular mass of approximately 22 kDa on SDS–PAGE. This study would provide a new opportunity for large-scale expression and purification of AmGH, which might facilitate studies on the biological activity of AmGH.     

Seasonal energy requirements and thermoregulation of growing pouched mice,Saccostomus campestris (Cricetidae)

Pouched mice (Saccostomus campestris) were born in captivity during January and March and subsequently maintained under long photoperiod (14 h light: 10 h dark) at 25°C. During their first winter (July) and the following summer (January) the pouched mice were exposed to natural photoperiod in an unheated laboratory for 3 weeks prior to measurement. The pouched mice continued to grow during the study, and were significantly heavier after summer exposure than after winter exposure 6 months earlier. Although this increase in body mass would result in a decline in their surface area to volume ratio there was no significant decline in minimal thermal conductance (C _m) and winter-exposed pouched mice had a relatively lowerC _m than expected. Meanwhile the smaller, winter-exposed animals displayed a significantly higher capacity for non-shivering thermogenesis, together with higher levels of basal metabolism than summer individuals. These differences were not solely attributable to the contrasting body mass of each group and it is therefore clear thatS. campestris can increase thermoregulatory heat production, and modify heat loss following exposure to short photoperiod and cold during their first winter. Despite the significant increase in metabolism, the overall energy requirements of small, winter-exposed animals were significantly lower than those for heavier pouched mice following exposure to summer conditions. These results suggest that growing pouched mice can effectively adapt to lower temperature conditions during their first winter, yet accrue considerable overall savings in total energy requirements as a result of their smaller body mass.     

Temperature dependence for development of the whitefly predator <Emphasis Type="Italic">Clitostethus arcuatus</Emphasis> (Rossi)

This work aimed to study the biology of Clitostethus arcuatus (Rossi) (Coleoptera: Coccinellidae) under different temperatures and evaluate the optimum temperature for its mass rearing. Studies were carried out in the laboratory at four constant temperatures (15°C, 20°C, 25°C and 30°C), 75 ± 5% relative humidity and a photoperiod of 16 h light:8 h dark, in which C. arcuatus was fed ad libitum with nymphs of all instar of Aleyrodes proletella L. (Homoptera: Aleyrodidae) on Brassicae oleracea L. (var. Costata). The following biological parameters were evaluated: development time and survival rates of pre-imaginal stages, adult longevity (female and male), length of the pre-oviposition and oviposition periods, fecundity, fertility and percentage of egg hatching. Population growth parameters, the lower development threshold and the sum of effective temperatures were estimated. Temperatures ranging from 20°C to 30°C were suitable for the development of C. arcuatus, suggesting that this species is well adapted to the temperatures usually found inside greenhouses or in open fields in temperate regions. Although the intrinsic rate of natural increase and doubling time were similar at 25°C and 30°C, the temperature of 25°C was shown to be the most suitable for mass rearing and development of populations under field conditions, since the percentage of egg hatching and the accumulated survival rates of the pre-imaginal stages were the highest. Considering the estimated lower threshold for pre-imaginal development (7.9°C) and the sum of effective temperatures [293.6 degree-days (°D)], it is predicted for Ponta Delgada (Azores, Portugal) that the first adults of C. arcuatus should emerge by the first fortnight of February and that up to 12 generations per year can occur.     

Studies on the critical water mass and the rehydration potential of unfed adult Dermacentor marginatus and D. reticulatus ticks (Acari: Ixodidae)

In unfed adult Dermacentor marginatus and D. reticulatusticks survival and capability to restore water balance after loss of high percentages of exchangeable body water were investigated. Furthermore, it was examined how frequently dehydrated ticks of these species were able to rehydrate by uptake of atmospheric water vapour. The critical water mass, defined as the water mass remaining in a tick at the nonambulatory state, differed between light and heavy weight groups and averaged 62.4 and 55.8%, respectively, of the total body water of fully hydrated ticks in females, and 54.4 and 51.1% respectively, in males of D. marginatus. In D. reticulatus, the corresponding figures were 55.9 and 54.7% in females and 52.1 and 52.7% in males. All ticks survived dehydration to 50, 75 or 100% of the critical water mass, and 96.7% of the D. marginatus ticks and 95.8% of the D. reticulatus ticks compensated water losses during subsequent incubation at 95% relative humidity (r.h.) and 20°C. Unfed females and males of both Dermacentor spp. were capable to balance water loss very frequently over a period of several months. When ticks were repeatedly dehydrated at 0% r.h. for 7 days and rehydrated at 95% r.h. and 20°C, females and males of D. marginatus reached the 50% mortality after 22 and 29 cycles of de- and rehydration, respectively, during 211 and 285 days, respectively. In D. reticulatus, 50% of females and males survived 23 and 17 cycles, respectively, during 248 and 186 days, respectively. Rehydration weights were as high or even higher as those of ticks kept at permanent 95% r.h.     

Different biomass-allocation patterns among four tree species in heavily disturbed sites on a volcanic mountain in Hokkaido,northern Japan

We have compared biomass-allocation patterns and frequency of sprouting among saplings of four tree species (Larix kaempferi, Betula platyphylla var. japonica, Populus maximowiczii, and Populus sieboldii) growing on a volcanic mountain in Hokkaido, northern Japan. Growing conditions were very harsh on the mountainside. Leaf mass and fine root mass relative to root mass were larger in L. kaempferi, and L. kaempferi root mass was less than for the other species. Sprouting ratios were high for the broadleaved species. Different allometries and sprouting ratios among species suggest that survival strategies for L. kaempferi were different from those for the broadleaved species. L. kaempferi has greater ability to increase leaf mass under harsh growing conditions; this probably results in large photosynthetic production by L. kaempferi on the volcano. In contrast, the two Populus species and Betula platyphylla seem to maintain populations through their ability to produce sprouts from large root systems.     

外源亚精胺对淹涝胁迫下黄瓜根HSP70表达的影响

采用逆转录聚合酶链式反应(RT-PCR)及蛋白免疫印迹杂交(Western Blot)技术,研究0.5 mmol/L亚精胺浸种的黄瓜幼苗在淹水胁迫下,根热激蛋白70基因(HSP70)mRNA和蛋白质的表达量的变化。结果表明:淹水胁迫使黄瓜根HSP70的mRNA和蛋白的表达呈现先上升后下降的趋势,在淹水4 h时,HSP70的mRNA和蛋白表达量均极显著高于未淹水处理; 亚精胺浸种的黄瓜根HSP70的mRNA和蛋白的表达量在24 h内呈一直上升的趋势,在淹水24 h时,HSP70的mRNA和蛋白表达量均极显著高于未淹水处理。淹涝胁迫下,亚精胺浸种的黄瓜根HSP70的mRNA和蛋白表达量在淹水12 h和24 h时极显著高于蒸馏水浸种。外源亚精胺能诱导淹涝胁迫下黄瓜幼苗根HSP70 mRNA和蛋白质的表达量的增加,缓解淹涝胁迫对黄瓜造成的伤害。     

Functional Response ofColeomegilla maculata(Coleoptera: Coccinellidae) to Colorado Potato Beetle Eggs (Coleoptera: Chrysomelidae)

A comparative study of the functional response ofColeomegilla maculataDeGeer (Coleoptera: Coccinellidae) fourth instars was conducted under laboratory, greenhouse, and field conditions. In the laboratory, individual larvae were placed in 9-cm petri dishes for 24 h, with 1, 3, 5, or 7 Colorado potato beetle (Leptinotarsa decemlineata[Say]) (Coleoptera: Chrysomelidae) egg masses. Each egg mass was standardized at 15 eggs. In the greenhouse and field,C. maculatalarvae were provided with an equivalent of 0.5 to 35L. decemlineataegg masses/m²of potato leaf. Fourth instars ofC. maculataexhibited a type II functional response toL. decemlineataeggs under laboratory, greenhouse, and field conditions. Predator search efficiency was inversely related with prey density. The maximum mean attack rate (8.7 eggs) byC. maculatalarvae in the field was about half the mean attack rate in the laboratory (17.6 eggs) and greenhouse (20.1 eggs). The difference in prey density between the laboratory and field seems to have been a major contributing factor in determining the rate of predation, whereas differences in environmental conditions (e.g., temperature and possible alternate food) may explain the differences observed in the predation rate in the greenhouse and field.     

High throughput culture and gametogenesis induction of <Emphasis Type="Italic">Laminaria japonica</Emphasis> gametophyte clones

In anticipation of the application of a new sporeling-raising method using gametophyte clones to Laminaria commercial cultivation in China, techniques of mass culture and gametogenesis induction of L. japonica gametophyte clones were developed, as a mass of fertile gametophytes is a prerequisite for sporeling-raising with the new method. Gametophyte clones which were subjected to fed-batch culture exhibited a classical logistic growth curve. Growth rates decreased gradually after 2 months of culture, and were negatively correlated to cell density. UNOVA also showed that only cell density has a significant effect on the growth of gametophyte clones under the experimental conditions. Based on the dynamics models revealed, a culture strategy only directed at the control of cell density was adopted. By this strategy, a total of 36 kg wet weight from an initial weight of 0.75 kg was achieved after 3 months culture in 100 20-L bottles. The final average density reached 24 g L⁻¹. For the subsequent gametogenesis induction, amplificatory male and female gametophyte clones were cut, mixed and cultured in bottles under the same conditions used in amplification except for a change of photoperiod from continuous irradiance to 10 h light: 14 h dark cycle. Egg discharge occurred 10 days after the mixed culture and increased gradually with the culture duration. Most gametophytes gave rise to sporophytes 20 days after induction. Large-scale culture of gametophyte clones and gametogenesis induction for commercial cultivation in 2003–2005 have been conducted successfully.     

Characterization of thermostable native alkaline phosphatase from an aerobic hyperthermophilic archaeon, <Emphasis Type="Italic">Aeropyrum pernix</Emphasis> K1

This paper reports the characterization of an alkaline phosphatase (AP) from an aerobic hyperthermophilic Archaeon Aeropyrum pernix K1. The native AP was purified into homogeneity. The enzyme is predicted as a homodimeric structure with a native molecular mass of about 75 kDa and monomer of about 40 kDa. Apparent optimum pH and temperature were estimated at 10.0 and above 95°C, respectively. Magnesium ion increased both the stability and the activity of the enzyme. A. pernix AP has been demonstrated as a very thermostable AP, retaining about 76% of its activity after being incubated at 90°C for 5.5 h and 67% of its activity after being incubated at 100°C for 2.5 h, respectively, under the presence of Mg(II). Enzyme activity was increased in addition of exogenous Mg(II), Ca(II), Zn(II), and Co(II).     

Dynamics and attenuation characteristics of periphyton upon artificial substratum under various light conditions and some additional observations on periphyton upon Potamogeton pectinatus L.

The seasonal variation in periphyton dynamics has been studied upon artificial substratum (microscopic glass slides) under various light conditions during the periods May–October 1986 and May–September 1987, in Lake Veluwe. Some additional observations on the periphyton development upon leaves of Potamogeton pectinatus L. have been made simultaneously. Four different light conditions were created in an experimental setup by manipulating the photon flux density through artificial shading.Periphyton upon artificial substratum exhibited a relatively high abundance with a distinct seasonal pattern. Periphyton accrual rates were highest at the beginning of June and in August and September upon slides which were incubated for two weeks. Periphyton mass increased during May and June, decreased or remained about the same during July and subsequently increased until an upper plateau was reached upon slides which were incubated from the beginning of May onwards.Generally, periphyton mass was lower upon slides than upon P. pectinatus. The seasonal variation in periphyton mass was more pronounced upon P. pectinatus leaves than upon the slides.Attenuation by periphyton upon slides ranged from 5 to 65% after two weeks of incubation. Periphyton upon slides which had been incubated for more than two weeks demonstrated an attenuation of more than 85%.Water quality parameters other than photon flux density were probably more important in determining the periphyton dynamics, since only minor differences were observed in periphyton mass between the various light conditions. Chlorophyll-a content was higher with increased shading on various sampling dates.Periphyton, especially older periphyton consisted largely of settled silt and clay particles and to a lesser extent of detrital matter on both substrata. Living epiphytes were only a relatively small fraction.It is concluded that a reduction of resuspension of sediment particles, giving less suspended matter in the water column, will result in lower periphytic mass. Consequently, the quantity of photosynthetically active radiation reaching the submerged macrophytes is expected to increase considerably.     

Heterologous production of Aspergillus fumigatus keratinase in Pichia pastoris

Aspergillus fumigatus Fresenius was previously shown to grow in mineral medium containing chicken feather flour as carbon and nitrogen source. Substantial proteolytic keratin-degrading activity was present in the culture supernatant after 24–72 h of growth at 42 °C. The keratinase was successfully purified by a single ion exchange chromatographic procedure and had a molecular mass of 31 kDa as determined by SDS–PAGE. The keratinase cDNA was expressed in Pichia pastoris cells and the recombinant clones were shown to be able to produce substantial caseinolytic, azo-keratinolytic and keratinolytic activities. SDS–PAGE and Western-blotting analysis using antibody against keratinase of A. fumigatus showed the presence of a single protein in the culture supernatants of several recombinant P. pastoris cells. This protein had a molecular mass corresponding to that of the A. fumigatus keratinase. The enzyme production profile showed that theP. pastoris recombinant cells produced an increasing amount of proteolytic and azo-keratinolytic activities over a 72 h growth period. Dry weight determination analysis indicated that 10% of the keratin flour was hydrolysed over a 24 h incubation period with 510 U (caseinolytic activity) of the recombinant keratinase.     

Functional response of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) to Aphis gossypii Glover (Homoptera: Aphididae) in the Laboratory

Stage specific functional response of Harmonia axyridis (Pallas) to varying densities of Aphis gossypii Glover was examined in a simplified cucumber leaf arena under laboratory conditions. All stages of H. axyridis were isolated individually for 24 h with different prey densities at 25 °C and a photoperiod of 16:8 (L:D) h. The number of prey consumed by the predator was checked at 3, 6, 12, and 24 h. All stages of H. axyridis showed a Type II functional response. Based on the random predator equation, estimated attack rates of H. axyridis at 24 h were 0.0037, 0.0442, 0.3590, 0.3228, and 0.1456, and estimated handling times were 4.1001, 2.4575, 0.7500, 0.2132, and 0.1708 h for the first, second, third, and fourth instars, and female adult, respectively.     

The production of polyhydroxybutyrate by Methylobacterium rhodesianum and Ralstonia eutropha in media containing glycerol and casein hydrolysates

Methylobacterium rhodesianum and Ralstonia eutropha were cultivated to produce polyhydroxybutyrate (PHB) using media which contained glycerol and casein hydrolysates as C/N-substrates. In these media the pH had not to be regulated during the fermentations. The first strain accumulated an average of 39% PHB during 92 h of cultivation in flasks and 50% PHB during 45 h of cultivation in fermenters. The second one yielded an average of 47% PHB during 67 h of cultivation using casein peptone and 65% PHB during 45 h of cultivation using Casamino acids in the medium. Calculated N-balances showed that about 65% of the supplied nitrogen was used for growth of non-PHB cell dry mass. The conversion of glycerol to PHB was 17% (w/w).     

Protein Patterns, Characterized by Computer Image Analysis, of Lentil Embryo Axes Germinating Under Salt Stress

Following 16, 40 and 64 h exposure to 0.33 M NaCl given after 8 h water imbibition, lentil seeds showed a gradual decrease of germination upon their transfer to water. These salt related changes were accompanied by modifications in the protein patterns of embryo axes as revealed by two-dimensional electrophoresis separation and by the computer image analysis of protein spots. In comparison with 8 h water imbibed seeds, prominent proteins comprised between the 5.1 – 7.6 pH isoelectric point in the first dimension and 75 – 50 kDa molecular mass in the second dimension showed a significant increase in their abundance as salt exposure increased. On transfer to water to complete germination, the content of many of these proteins decreased at 24h in 2 – 3 cm length embryo axes in comparison with the corresponding embryo axes of seeds continuously imbibed in water for 24 h. Some groups of proteins ranging between 15.5 – 17.3 kDa, already present after 8 h water imbibition, were not detectable after 24 h but were expressed in seeds exposed to NaCl and transferred to water for 24 h. Up- and down-regulated proteins in lentil embryo axes, imbibed under non-lethal salt stress conditions, have been tentatively identified by comparison with the protein map of germinating seeds of the model plant Arabidopsis. This revised version was published online in July 2006 with corrections to the Cover Date.     

A trypsin inhibitor from <Emphasis Type="Italic">Cassia obtusifolia</Emphasis> seeds: isolation,characterization and activity against <Emphasis Type="Italic">Pieris rapae</Emphasis>

A trypsin inhibitor was isolated from Cassia obtusifolia by ammonium sulfate precipitation, Sepharose 4B-trypsin affinity and Sephadex G-75 chromatography. The inhibitor consisted of a single polypeptide chain with a molecular mass of 19, 812.55 Da. It was stable from pH 2 to 12 for 24 h, whereas it was unstable either above 70°C for 10 min or under reduced conditions. The inhibitor, which inhibited trypsin activity with an apparent Ki of 0.3 μM, had one reactive site involving a lysine residue. The native inhibitor was resistant to pepsin digestion, whereas the heated inhibitor produced 40% degree of susceptibility. The disulfide linkage and lysine residue were important in maintaining its conformation. Partial amino acid sequence of the purified protein showed a high degree of homology with various members of the Kunitz inhibitor family. Moreover, the inhibitor showed significant inhibitory activity against trypsin-like proteases present in the larval midgut on Pieris rapae and could suppress the growth of larvae.     

Regulation of nitrogen-fixation by different nitrogen sources in the marine non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067

The effect of various nitrogen sources on the synthesis and activity of nitrogenase was studied in the marine, non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067 grown under defined culture conditions. Cells grown with N₂ as the sole inorganic nitrogen source showed light-dependent nitrogenase activity (acetylene reduction). Nitrogenase activity in cells grown on N₂ was not suppressed after 7 h incubation with 2 mM NaNO₃ or 0.02 mM NH₄Cl. However, after 3 h of exposure to 0.5 mM of urea, nitrogenase was inactivated. Cells grown in medium containing 2 mM NaNO₃, 0.5 mM urea or 0.02 mM NH₄Cl completely lacked the ability to reduce acetylene. Western immunoblots tested with polyclonal antisera against the Fe-protein and the Mo–Fe protein, revealed the following: (1) both the Fe-protein and the Mo–Fe protein were synthesized in cells grown with N₂ as well as in cells grown with NaNO₃ or low concentration of NH₄Cl; (2) two bands (apparent molecular mass of 38 000 and 40 000) which cross-reacted with the antiserum to the Fe-protein, were found in nitrogen-fixing cells; (3) only one protein band, corresponding to the high molecular mass form of the Fe-protein, was found in cells grown with NaNO₃ or low concentration of NH₄Cl; (4) neither the Fe-protein nor the Mo–Fe protein was found in cells grown with urea; (5) the apparent molecular mass of the Fe-protein of Trichodesmium sp. NIBB1067 was about 5000 dalton higher than that of the heterocystous cyanobacterium, Anabaena cylindrica IAM-M1.     

Use ofAzospirillum brasilense as biofertilizer in intensive wheat cropping

Summary Three field experiments were conducted on ten cultivars of winterwheat and four cultivars of springwheat to estimate the growth promoting effect ofAzospirillum brasilense under varying nitrogen doses. Independent of cultivar selection or nitrogen dose a highly significant yield increase could be observed in winterwheat: strains S631 and SpBr14 increased the average grain yield with 9.14% and 14.82% respectively. When the yield components were studied a coinciding increase in ear density could be demonstrated of resp. 10.57% and 13.55%. Less significant results were obtained with springwheat although in one experiment strain SpBr14 significantly increased grain yield. As with winterwheat tillering of the plant was markedly affected by inoculation with both strains. In a companion greenhouse experiment it was found that inoculation with Azospirillum can cause a decrease in the root mass of wheatplants except when strain SpBr14 is used. Therefore it is suggested that the presence of a higher tillering together with an undisturbed nutrient uptake capacity can result in yield increases after inoculation withAzospirillum brasilense.     

Isolation and characterization of a cysteine protease from the latex of Araujia hortorum fruits

A new protease (araujiain h l) was purified to mass spectroscopy homogeneity from the latex of Araujia hortorum Fourn. (Asclepiadaceae) fruits by ultracentrifugation and ion exchange chromatography. The enzyme has a molecular mass of 24,031 (mass spectrometry) and an isoelectric point higher than 9.3. The optimum pH range for casein hydrolysis was 8.0–9.5. The enzyme showed remarkable caseinolytic activity at high temperatures, although its thermal stability decayed rapidly. The proteinase was activated by thiol compounds and inhibited by common thiol-blocking reagents, particularly E-64 and HgCl₂, suggesting the enzyme belongs to the cysteine protease family. The concentration of active sites as determined by titration with E-64 was 3.3 M. When assayed on N--CBZ-amino acid-p-nitrophenyl esters, the enzyme showed higher preference for the glutamine derivative, followed by those of alanine, asparagine, glycine, and leucine, in decreasing order. Partial homology (36–48%) with other plant cysteine proteinases was observed in an internal fragment obtained by Protease V8 treatment.     

Partial characterization and dynamics of synthesis of high molecular mass exopolysaccharides from Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus

Exopolysaccharide (EPS) preparations from Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) strains LBB.B26 and LBB.B332 and Streptococcus thermophilus strains LBB.T54 and LBB.T6V were characterized using ion-exchange chromatography and gel filtration. All four preparations contained a neutral EPS with molecular mass in the range of 1.3−1.6 × 10⁶ Da (HMM-EPS). The EPS preparations from the two L. bulgaricus strains also contained an acidic low molecular mass EPS fraction (LMM-EPS) comprising from 10% to 34% of the total EPS yield. HMM-EPS preparations were subjected to High Pressure Liquid Chromatography (HPLC) analysis of monomer sugars after complete hydrolysis. Glucose, galactose and/or rhamnose in different ratios proved to be the principal sugars building the HMM-EPS from all four strains. The chemical composition of HMM-EPS was strictly strain-specific. The LMM-EPS contained galactose. The viscosifying properties of the four different HMM-EPS varied greatly with intrinsic viscosity in the range from 0.26 (strain B26) to 2.38 (strain T6V). For 24 h the two L. bulgaricus strains accumulated more HMM-EPS in milk (>70 mg l⁻¹) than S. thermophilus strains T54 and T6V (<30 mg l⁻¹), but maximal yields were reached earlier with cocci (8 h) than with rods (16–24 h). The contribution of HMM-EPS production to increased viscosity of fermented milk was demonstrated for all of the tested strains grown as monocultures or as mixed yogurt starters compared to non-EPS producing S. thermophilus LBB.A and poor EPS-producer L. bulgaricus LBB.B5. The extent of increased viscosity was strongly dependent on the nature of the produced HMM-EPS, rather than simply on polymer yield.     

Root aerobic respiration and growth characteristics of three Typha species in response to hypoxia

The responses of root aerobic respiration to hypoxia in three common Typha species were examined. Typha latifolia L., T. orientalis Presl, and T. angustifolia L. were hydroponically cultivated under both aerobic and hypoxic growth conditions to measure root oxygen consumption rates. Hypoxia significantly enhanced the root aerobic respiration capacity of the two deep-water species, T. orientalis and T. angustifolia, while it did not affect that of the shallow-water species, T. latifolia. T. angustifolia increased its root porosity and root mass ratio, while T. latifolia increased its root diameter under the hypoxic growth conditions. The relative growth rates in biomass of T. orientalis and T. angustifolia were 59 and 39% higher, respectively, under the hypoxic growth conditions than under the aerobic growth conditions. In contrast, that of T. latifolia did not differ between the two conditions. In T. orientalis and T. angustifolia, enhanced root aerobic respiration rates under the hypoxic growth conditions would have increased the nutrient uptake, and thus higher relative growth rates were obtained. For the deep-water species, T. orientalis and T. angustifolia, the root aerobic respiration capacity was enhanced, probably in order to maintain the generation of respiratory energy under hypoxia.