The effect of ethylene, octanoic acid and a plant-derived smoke extract on the germination of light-sensitive lettuce seeds

The effects of an aqueous plant-derived smoke extract, octanoic acid and ethylene on germination of light-sensitive Grand Rapids lettuce seeds were investigated. The smoke extract brought about a concentration dependent increase in germination and a complete inhibition of germination at high concentrations. Octanoic acid could not induce germination. Ethylene at concentrations over 5 L L^–1 increased lettuce seed germination, but not to the same degree as smoke. Aqueous smoke in combination with ethylene showed a synergistic effect on germination at suboptimal smoke concentrations. At high smoke concentrations the effect of ethylene was almost completely inhibited. Octanoic acid in combination with ethylene brought about a higher level of germination than with ethylene alone, but only at the highest concentration of octanoic acid tested (1 mM). Standardized hexane and dichloromethane-partitioned smoke extracts and octanoic acid were subjected to TLC separation. The R _f -fractions in the smoke lanes showing activity in the lettuce seed bioassay did not correspond to the R _f -value of octanoic acid. As aqueous smoke can withstand autoclaving and can be separated by TLC and HPLC without loosing activity it is unlikely that the activity of aqueous smoke is linked to ethylene. It thus appears that the active compound in smoke is neither octanoic acid nor ethylene.Abbreviations TLC thin layer chromatography - HPLC High performance liquid chromatography     

Volatilome of Aleppo Pine litter over decomposition process

Biogenic Volatile Organic Compounds (BVOC) are largely accepted to contribute to both atmospheric chemistry and ecosystem functioning. While the forest canopy is recognized as a major source of BVOC, emissions from plant litter have scarcely been explored with just a couple of studies being focused on emission patterns over litter decomposition process. The aim of this study was to quantitatively and qualitatively characterize BVOC emissions (C₁–C₁₅) from Pinus halepensis litter, one of the major Mediterranean conifer species, over a 15‐month litter decomposition experiment. Senescent needles of P. halepensis were collected and placed in 42 litterbags where they underwent in situ decomposition. Litterbags were collected every 3 months and litter BVOC emissions were studied in vitro using both online (PTR‐ToF‐MS) and offline analyses (GC‐MS). Results showed a large diversity of BVOC (58 compounds detected), with a strong variation over time. Maximum total BVOC emissions were observed after 3 months of decomposition with 9.18 µg g_DM ⁻¹ hr⁻¹ mainly composed by terpene emissions (e.g., α‐pinene, terpinolene, β‐caryophyllene). At this stage, methanol, acetone, and acetic acid were the most important nonterpenic volatiles representing, respectively, up to 26%, 10%, and 26% of total emissions. This study gives an overview of the evolution of BVOC emissions from litter along with decomposition process and will thus contribute to better understand the dynamics and sources of BVOC emission in Mediterranean pine forests.     

Lipid Peroxidation and Total Cholesterol in HAART-Na?ve Patients Infected with Circulating Recombinant Forms of Human Immunodeficiency Virus Type-1 in Cameroon

Background

HIV infection has commonly been found to affect lipid profile and antioxidant defense.

Objectives

To determine the effects of Human Immunodeficiency Virus (HIV) infection and viral subtype on patient’s cholesterol and oxidative stress markers, and determine whether in the absence of Highly Active Antiretroviral Therapy (HAART), these biochemical parameters could be useful in patient’s management and monitoring disease progression in Cameroon. For this purpose, we measured total cholesterol (TC), LDL cholesterol (LDLC), HDL cholesterol (HDLC), total antioxidant ability (TAA), lipid peroxidation indices (LPI), and malondialdehyde (MDA) in HIV negative persons and HIV positive HAART-naïve patients infected with HIV-1 group M subtypes.

Methods

We measured serum TC, LDLC, HDLC, plasma MDA, and TAA concentrations, and calculated LPI indices in 151 HIV-positive HAART-naïve patients and 134 seronegative controls. We also performed gene sequence analysis on samples from 30 patients to determine the effect of viral genotypes on these biochemical parameters. We also determined the correlation between CD4 cell count and the above biochemical parameters.

Results

We obtained the following controls/patients values for TC (1.96±0.54/1. 12±0. 48 g/l), LDLC (0. 67±0. 46/0. 43±0. 36 g/l), HDLC (105. 51±28. 10/46. 54±23. 36 mg/dl) TAA (0. 63±0. 17/0. 16±0. 16 mM), MDA (0. 20±0. 07/0. 41±0. 10 µM) and LPI (0. 34±0. 14/26. 02±74. 40). In each case, the difference between the controls and patients was statistically significant (p<0.05). There was a positive and statistically significant Pearson correlation between CD4 cell count and HDLC (r = +0.272; p<0.01), TAA (r = +0.199; p<0.05) and a negative and statistically significant Pearson correlation between CD4 cell count and LPI (r = −0.166; p<0.05). Pearson correlation between CD4 cell count and TC, CD4cell count and LDLC was positive but not statistically significant while it was negative but not statistically significant with MDA. The different subtypes obtained after sequencing were CRF02_AG (43.3%), CRF01_AE (20%), A1 (23.3%), H (6.7%), and G (6.7%). None of the HIV-1 subtypes significantly influenced the levels of the biochemical parameters, but by grouping them as pure subtypes and circulating recombinant forms (CRFs), the CRF significantly influenced TC levels. TC was significantly lower in patients infected with CRF (0.87±0.27 g/l) compared to patients infected with pure HIV-1 subtypes (1.32±0.68 g/l) (p<0.017). MDA levels were also significantly higher in patients infected with HIV-1CRF01_AE (0.50±0.10 µM), compared to patients infected with CRF02_AG (0. 38±0. 08 µM) (p<0.018).

Conclusion

These results show that HIV infection in Cameroon is associated with significant decrease in TAA, LDLC, HDLC and TC, and increased MDA concentration and LPI indices which seem to be linked to the severity of HIV infection as assessed by CD4 cell count. The data suggests increased oxidative stress and lipid peroxidation in HIV-infected patients in Cameroon, and an influence of CRFs on TC and MDA levels.     

Effect of Root Temperature on Cytokinin Activity in Root Exudate of Vitis vinifera L

Root exudates of plants of Vitis vinifera L. cv. Thompson Seedless, grown in nutrient cultures with root temperatures maintained at either 20° or 30° and with shoots at a common air temperature, were assayed for cytokinin activity. After chromatography of freeze-dried sap on paper with n-butanol/acetic acid/water (4:1:1). activity was detected with a soybean callus assay. For both root temperatures, major activity appeared between R_F 0.6 and R_F 0.8, at about the same concentration in each case. The major difference between the 2 samples was the presence of activity at R_F 0.1 to 0.2 in the 20° sample and its absence in the 30° sample.

The higher root temperature resulted in increased shoot and root elongation, increased dry matter accumulation by both shoots and roots, and also altered the morphological appearance of the roots.

     

Translational Diffusion of Macromolecule-sized Solutes in Cytoplasm and Nucleus

Fluorescence recovery after photobleaching (FRAP) was used to quantify the translational diffusion of microinjected FITC-dextrans and Ficolls in the cytoplasm and nucleus of MDCK epithelial cells and Swiss 3T3 fibroblasts. Absolute diffusion coefficients (D) were measured using a microsecond-resolution FRAP apparatus and solution standards. In aqueous media (viscosity 1 cP), D for the FITC-dextrans decreased from 75 to 8.4 × 10⁻⁷ cm²/s with increasing dextran size (4–2,000 kD). D in cytoplasm relative to that in water (D/D_o) was 0.26 ± 0.01 (MDCK) and 0.27 ± 0.01 (fibroblasts), and independent of FITC-dextran and Ficoll size (gyration radii [R_G] 40–300 Å). The fraction of mobile FITC-dextran molecules (f_mob), determined by the extent of fluorescence recovery after spot photobleaching, was >0.75 for R_G < 200 Å, but decreased to <0.5 for R_G > 300 Å. The independence of D/D_o on FITC-dextran and Ficoll size does not support the concept of solute “sieving” (size-dependent diffusion) in cytoplasm. Photobleaching measurements using different spot diameters (1.5–4 μm) gave similar D/D_o, indicating that microcompartments, if present, are of submicron size. Measurements of D/D_o and f_mob in concentrated dextran solutions, as well as in swollen and shrunken cells, suggested that the low f_mob for very large macromolecules might be related to restrictions imposed by immobile obstacles (such as microcompartments) or to anomalous diffusion (such as percolation). In nucleus, D/D_o was 0.25 ± 0.02 (MDCK) and 0.27 ± 0.03 (fibroblasts), and independent of solute size (R_G 40–300 Å). Our results indicate relatively free and rapid diffusion of macromolecule-sized solutes up to approximately 500 kD in cytoplasm and nucleus.     

ATAD3B is a mitophagy receptor mediating clearance of oxidative stress‐induced damaged mitochondrial DNA

Mitochondrial DNA (mtDNA) encodes several key components of respiratory chain complexes that produce cellular energy through oxidative phosphorylation. mtDNA is vulnerable to damage under various physiological stresses, especially oxidative stress. mtDNA damage leads to mitochondrial dysfunction, and dysfunctional mitochondria can be removed by mitophagy, an essential process in cellular homeostasis. However, how damaged mtDNA is selectively cleared from the cell, and how damaged mtDNA triggers mitophagy, remain mostly unknown. Here, we identified a novel mitophagy receptor, ATAD3B, which is specifically expressed in primates. ATAD3B contains a LIR motif that binds to LC3 and promotes oxidative stress‐induced mitophagy in a PINK1‐independent manner, thus promoting the clearance of damaged mtDNA induced by oxidative stress. Under normal conditions, ATAD3B hetero‐oligomerizes with ATAD3A, thus promoting the targeting of the C‐terminal region of ATAD3B to the mitochondrial intermembrane space. Oxidative stress‐induced mtDNA damage or mtDNA depletion reduces ATAD3B‐ATAD3A hetero‐oligomerization and leads to exposure of the ATAD3B C‐terminus at the mitochondrial outer membrane and subsequent recruitment of LC3 for initiating mitophagy. Furthermore, ATAD3B is little expressed in m.3243A > G mutated cells and MELAS patient fibroblasts showing endogenous oxidative stress, and ATAD3B re‐expression promotes the clearance of m.3243A > G mutated mtDNA. Our findings uncover a new pathway to selectively remove damaged mtDNA and reveal that increasing ATAD3B activity is a potential therapeutic approach for mitochondrial diseases.     

Single-trait and antagonistic index selection for litter size and body weight in mice

Individual selection based on female performance only was conducted in four lines of mice: L⁺ for increased litter size, W⁺ for increased 6-week body weight, L^-W⁺ for a selection index aimed at decreasing litter size and increasing 6-week body weight and L⁺W^- for a selection index aimed at increasing litter size and decreasing 6-week body weight. A fifth line (K) served as an unselected control. All litters were standardized to eight mice at one day of age. Expected heritability was based on twice the regression of offspring on dam (h²_d), which contains additive genetic variance due to direct (σ²_Ao) and maternal (σ²_Am) effects and their covariance (σ_AoAm). Responses and correlated responses were measured either deviated (method 1) or not deviated (method 2) from the control line. Realized heritabilities (h²_R) for litter size were 0.19 ± 0.04 (1) and 0.16 ± 0.03 (2), which were similar to h ²_d of 0.17 ± 0.04. The h² _R for 6-week body weight of 0.55 ± 0.07 (1) and 0.44 ± 0.07 (2) agreed with h²_d of 0.42 ± 0.02. Realized genetic correlations (r*_GR) between litter size and 6-week body weight calculated from the double-selection experiment were 0.52 ± 0.10 (1) and 0.52 ± 0.13 (2), which were not significantly different from the base population estimate of r* _Gd = 0.63 ± 0.14. Divergence (L^-W ⁺ minus L⁺W^-) in the antagonistic index selection lines was 0.21 ± 0.01 index units (I = 0.305 P_W - 0.436 P_L, where P _W and P_L are the phenotypic values for 6-week body weight and litter size, respectively.). The h² _R of index units of 0.14 ± 0.02 calculated from divergence agreed with h²_d of 0.14 ± 0.04. Divergences in litter size (-0.19 ± 0.07) and 6-week body weight (0.46 ± 0.10) were in the expected direction. Antagonistic index selection yielded about one-half the expected divergence in litter size, while divergence in 6-week body weight was only slightly less than expected. Realized genetic correlations indicated that litter size, 6-week body weight and index units each showed positive pleiotropy with 3-week body weight, postweaning gain and weight at vaginal introitus and negative pleiotropy with age at vaginal introitus. Sex ratio and several components of fitness (days from joining to parturition, percent fertile matings and percent perinatal survival) did not change significantly in the selected lines.     

Elevated Bile Acids in Newborns with Biliary Atresia (BA)

Biliary Atresia (BA), a result from inflammatory destruction of the intrahepatic and extrahepatic bile ducts, is a severe hepatobiliary disorder unique to infancy. Early diagnosis and Kasai operation greatly improve the outcome of BA patients, which encourages the development of early screening methods. Using HPLC coupled tandem mass spectrometry, we detected primary bile acids content in dried blood spots obtained from 8 BA infants, 17 neonatal jaundice and 292 comparison infants at 3–4 days of life. Taurocholate (TC) was significantly elevated in biliary atresia infants (0.98±0.62 µmol/L) compared to neonatal jaundice (0.47±0.30 µmol/L) and comparison infants (0.43±0.40 µmol/L), with p = 0.0231 and p = 0.0016 respectively. The area under receiver operating characteristic (ROC) curve for TC to discriminate BA and comparison infants was 0.82 (95% confidence interval: 0.72–0.92). A cutoff of 0.63 µmol/L produced a sensitivity of 79.1% and specificity of 62.5%. The concentrations of total bile acids were also raised significantly in BA compared to comparison infants (6.62±3.89 µmol/L vs 3.81±3.06 µmol/L, p = 0.0162), with the area under ROC curve of 0.75 (95% confidence interval: 0.61–0.89). No significant difference was found between the bile acids of neonatal jaundice and that of comparison infants. The early increase of bile acids indicates the presentation of BA in the immediate newborn period and the possibility of TC as newborn screening marker.     

Water transport in invertebrate peripheral nerve fibers

Osmotic and diffusion permeabilities (P_f and P_d) of invertebrate nerve fibers to tritiated water were measured to determine what water flux studies could reveal about "the nerve membrane" and to directly test the possibility of active transport of water into or out of invertebrate nerve fibers. P_f/P_d ratios for lobster walking leg nerve fibers were found to be about 20 ± 7 at 14°C. P_d measurements were made for squid giant axons at 25°C. and found to yield a value of 4 x 10^–4 cm.^–1 sec.^–1. When combined with the data of D. K. Hill for P_f, a P_f/P_d ratio of 21 ± 5 is obtained. These P_f/P_d ratios correspond to "effective pore radii" of about 16 ± 4 angstrom units, according to theories developed by Koefoed-Johnsen and Ussing and independently by Pappenheimer and his colleagues. Variations of water flux ratios with temperatures were studied and apparent activation energies calculated for both diffusion experiments and osmotic filtration experiments using the Arrhenius equation, and found to be close to 3 to 5 cal. per mole of water transferred. Cyanide (5 x 10^–3 molar) and iodoacetate (1 x 10^–3 molar) poisoned lobster leg nerve fibers showed no appreciable change in diffusion or osmotic filtration water effluxes. Caution in interpreting these proposed channels as simple pores was emphasized, but the possibility that such channels exist and are related to ionic flow is not incompatible with electrophysiological data.     

Stress tolerance and stress-induced injury in crop plants measured by chlorophyll fluorescence in vivo: chilling, freezing, ice cover, heat, and high light

The proposition is examined that measurements of chlorophyll fluorescence in vivo can be used to monitor cellular injury caused by environmental stresses rapidly and nondestructively and to determine the relative stress tolerances of different species. Stress responses of leaf tissue were measured by F_R, the maximal rate of the induced rise in chlorophyll fluorescence. The time taken for F_R to decrease by 50% in leaves at 0°C was used as a measure of chilling tolerance. This value was 4.3 hours for chilling-sensitive cucumber. In contrast, F_R decreased very slowly in cucumber leaves at 10°C or in chilling-tolerant cabbage leaves at 0°C. Long-term changes in F_R of barley, wheat, and rye leaves kept at 0°C were different in frost-hardened and unhardened material and in the latter appeared to be correlated to plant frost tolerance. To simulate damage caused by a thick ice cover, wheat leaves were placed at 0°C under N₂. Kharkov wheat, a variety tolerant of ice encapsulation, showed a slower decrease in F_R than Gatcher, a spring wheat. Relative heat tolerance was also indicated by the decrease in F_R in heated leaves while changes in vivo resulting from photoinhibition, ultraviolet radiation, and photobleaching can also be measured.     

Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production

Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 °C) and thermophilic (55 °C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 °C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 L_CH4/kg_VS (VS: volatile solids) and 121 L _CH4/kg_VS at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kg_{dry_biochar} was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only.     

Impact of Daily Thermocycles on Hatching Rhythms,Larval Performance and Sex Differentiation of Zebrafish

In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled “gating” mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation.     

Temperature-Dependent Fecundity and Life Table of the Fennel Aphid Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae)

Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae) is a cosmopolitan species and the main pest of fennel in northeastern Brazil. Understanding the relationship between temperature variations and the population growth rates of H. foeniculi is essential to predict the population dynamics of this aphid in the fennel crop. The aim of this study was to measure the effect of constant temperature on the adult prereproductive period and the life table fertility parameters (infinitesimal increase ratio (r_m), gross reproduction rate (GRR), net reproduction rate (R₀), finite increase ratio (λ), generation time (GT), the time required for the population to double in the number of individuals (DT), and the reproduction value (RV_x)) of the fennel pest H. foeniculi. The values of lx (survival of nymphs at age x) increased as the temperature rose from 15 to 28°C and fell at 30°C, whereas mx (number of nymphs produced by each nymph of age x) increased from 15 to 25°C and fell at 28 and 30°C. The net reproduction rates (R₀) of populations of H. foeniculi increased with temperature and ranged from 1.9 at 15°C to 12.23 at 28°C for each generation. The highest population increase occurred with the apterous aphids at 28°C. The rate of population increase per unit time (r_m) (day) ranged from 0.0033 (15°C) to 0.1995 (28°C). The highest values of r_m were recorded at temperatures of 28°C and 30°C. The r_m values were a good fit to the models tested, with R² > 0.91 and R² _adj > 0.88. The models tested (Davidson, Sharpe and DeMichele modified by Schoolfield et al., Logan et al., Lamb, and Briere et al.) were very good fits for the r_m values observed, with R² > 0.91 and R² _adj > 0.88. The only exception was the Davidson model. Of the parameters studied, the reproductive capacity was higher in the apterous aphids, with the unique exception of daily fecundity at 28°C, which was higher in the alate aphids of H. foeniculi. Parameters relating to the age-specific fertility table for H. foeniculi were heavily influenced by temperature, with the highest biotic potential and population growth capacity found at 34°C. Therefore, the results obtained in this study could be of practical significance for predicting outbreaks of fennel aphids and improving the management of this aphid in fennel crops.     

Litter decomposes slowly on shaded steep slope and sunny gentle slope in a typical steppe ecoregion

Plant litter decomposition is mainly affected by litter properties and environmental factors, but the influence of terrain on litter decomposition is not well understood. We studied the effects of terrain on litter decomposition over a period of 12 months at six locations in a typical steppe ecoregion and measured the concomitant release of carbon (C), nitrogen (N), and phosphorus (P). The study site has two aspects, shaded and sunny, each aspect having three slopes: 15°, 30°, and 45°. The same mixed litter was used at each location to exclude the influence of litter quality variation. Results showed that soil temperature and moisture, solar radiation, and plant species diversity varied by terrain, which in turn, affected the k‐value (standardized total effects, 0.78, 0.12, 0.92, 0.23, respectively) and the release of C (0.72, –0.25, 0.83, 0.24, respectively), N (0.89, –0.45, 0.76, 0.40, respectively) and P (0.88, 0.77, 0.58, 0.57, respectively). K‐value and C release decreased with increasing slope on shaded aspect, while increased with increasing slope on sunny aspect. The release of N and P decreased with increasing slope on the shaded aspect. K‐value and C, N, and P release were significantly higher on shaded than that on sunny aspect at 15° and 30°, while at 45°, it was higher on sunny than on shaded aspect. The litter mass loss was slower on shaded 45° and sunny 15°. So moderate grazing or mowing could be used to reduce litter accumulation and accelerate litter decomposition on these terrains. Structural equation modeling indicated that soil temperature and solar radiation had the greatest influence on k‐value and C, N, and P release, and these two factors were directly related to soil moisture and plant species diversity. Overall, our results emphasize the need to consider terrain for litter decomposition in typical steppe ecoregions.     

Leaf Cytosolic Fructose-1,6-bisphosphatase : A Potential Target Site in Low Temperature Stress

Leaf cytosolic fructose-1,6-bisphosphatase (FBPase), partially purified from both spinach (Spinacia oleracea, var Hipack) and peas (Pisum sativum, var Progress No. 9), is reversibly inactivated by exposure to low temperature. Thus, even though assays were conducted at 22°C, samples incubated at 0 to 12°C had greatly reduced activity relative to controls maintained at 22°C. Following incubation at 22°C prior to assay, the inactivated samples regained their initial activity. Chloroplast FBPase, by contrast, was unaffected by low temperature treatment. This feature as well as lack of a response of cytosolic FBPase to thioredoxins f or c_f and to chloroplast FBPase antibody indicate that the FBPase isozymes of leaves are different proteins.     

Evaluation of the Shape Symmetry of Bilateral Normal Corneas in a Chinese Population

Purpose

To investigate the bilateral symmetry of the global corneal topography in normal corneas with a wide range of curvature, astigmatism and thickness values

Design

Cross-Sectional Study

Methods

Topography images were recorded for the anterior and posterior surfaces of 342 participants using a Pentacam. Elevation data were fitted to a general quadratic model that considered both translational and rotational displacements. Comparisons between fellow corneas of estimates of corneal shape parameters (elevation, radius in two main directions, R_x and R_y, and corresponding shape factors, Q_x and Q_y) and corneal position parameters (translational displacements: x₀, y₀ and z₀, and rotational displacements: α, β and γ) were statistically analyzed.

Results

The general quadratic model provided average RMS of fit errors with the topography data of 1.7±0.6 µm and 5.7±1.3 µm in anterior and posterior corneal surfaces. The comparisons showed highly significant bilateral correlations with the differences between fellow corneas in R_x, R_y, Q_x and Q_y of anterior and posterior surfaces remaining insignificantly different from zero. Bilateral differences in elevation measurements at randomly-selected points in both corneal central and peripheral areas indicated strong mirror symmetry between fellow corneas. The mean geometric center (x₀, y₀, z₀) of both right and left corneas was located on the temporal side and inferior-temporal side of the apex in anterior and posterior topography map, respectively. Rotational displacement angle α along X axis had similar distributions in bilateral corneas, while rotation angle β along Y axis showed both eyes tilting towards the nasal side. Further, rotation angle γ along Z axis, which is related to corneal astigmatism, showed clear mirror symmetry.

Conclusions

Analysis of corneal topography demonstrated strong and statistically-significant mirror symmetry between bilateral corneas. This characteristic could help in detection of pathological abnormalities, disease diagnosis, measurement validation and surgery planning.     

Cyclic variations in nitrogen uptake rate in soybean plants

Uptake of NO₃⁻ by nonnodulated soybean plants (Glycine max L. Merr. cv Ransom) growing in flowing hydroponic culture at 22 and 14°C root temperatures was measured daily during a 31-day growth period. Ion chromatography was used to determine removal of NO₃⁻ from solution during each 24-hour period. At both root-zone temperatures, rate of NO₃⁻ uptake per plant oscillated with a periodicity of 3 to 5 days. The rate of NO₃⁻ uptake per plant was consistently lower at 14°C than 22°C. The lower rate of NO₃⁻ uptake at 14°C during the initial 5 to 10 days was caused by reduced uptake rates per gram root dry weight, but with time uptake rates per gram root became equal at 14 and 22°C. Thereafter, the continued reduction in rate of NO₃⁻ uptake per plant at 14°C was attributable to slower root growth.     

Characterization of an endo-Acting Amylopullulanase from Thermoanaerobacter Strain B6A

A thermoanaerobe (Thermoanaerobacter sp.) grown in TYE-starch (0.5%) medium at 60°C produced both extra- and intracellular pullulanase (1.90 U/ml) and amylase (1.19 U/ml) activities. Both activities were produced at high levels on a variety of carbon sources. The temperature and pH optima for both pullulanase and amylase activities were 75°C and pH 5.0, respectively. Both the enzyme activities were stable up to 70°C (without substrate) and at pH 4.5 to 5.0. The half-lives of both enzyme activities were 5 h at 70°C and 45 min at 75°C. The enzyme activities did not show any metal ion activity, and both activities were inhibited by β- and γ-cyclodextrins but not by α-cyclodextrin. A single amylolytic pullulanase responsible for both activities was purified to homogeneity by DEAE-Sepharose CL-6B column chromatography, gel filtration using high-pressure liquid chromatography, and pullulan-Sepharose affinity chromatography. It was a 450,000-molecular-weight glycoprotein composed of two equivalent subunits. The pullulanase cleaved pullulan in α1,6 linkages and produced multiple saccharides from cleavage of α-1,4 linkages in starch. The K_ms for pullulan and soluble starch were 0.43 and 0.37 mg/ml, respectively.     

Physical and Perceptual Cooling with Beverages to Increase Cycle Performance in a Tropical Climate

Purpose

This study compares the effects of neutral temperature, cold and ice-slush beverages, with and without 0.5% menthol on cycling performance, core temperature (T_co) and stress responses in a tropical climate (hot and humid conditions).

Methods

Twelve trained male cyclists/triathletes completed six 20-km exercise trials against the clock in 30.7°C±0.8°C and 78%±0.03% relative humidity. Before and after warm-up, and before exercise and every 5 km during exercise, athletes drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L)) or a non-aromatized beverage (neutral temperature: 23°C±0.1°C, cold: 3°C±0.1°C, or ice-slush: −1°C±0.7°C). During the trials, heart rate (HR) was continuously monitored, whereas core temperature (T_co), thermal comfort (TC), thermal sensation (TS) and rate of perceived exertion (RPE) were measured before and after warm-up, every 5 km of exercise, and at the end of exercise and after recovery.

Results

Both the beverage aroma (P<0.02) and beverage temperature (P<0.02) had significant and positive effects on performance, which was considerably better with ice-slush than with a neutral temperature beverage, whatever the aroma (P<0.002), and with menthol vs non-menthol (P<0.02). The best performances were obtained with ice-slush/menthol and cold/menthol, as opposed to neutral/menthol. No differences were noted in HR and T_co between trials.

Conclusion

Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate. Further studies are needed to explore its effects in field competition.