Analysis of Light Transport Features in Stone Fruits Using Monte Carlo Simulation

The propagation of light in stone fruit tissue was modeled using the Monte Carlo (MC) method. Peaches were used as the representative model of stone fruits. The effects of the fruit core and the skin on light transport features in the peaches were assessed. It is suggested that the skin, flesh and core should be separately considered with different parameters to accurately simulate light propagation in intact stone fruit. The detection efficiency was evaluated by the percentage of effective photons and the detection sensitivity of the flesh tissue. The fruit skin decreases the detection efficiency, especially in the region close to the incident point. The choices of the source-detector distance, detection angle and source intensity were discussed. Accurate MC simulations may result in better insight into light propagation in stone fruit and aid in achieving the optimal fruit quality inspection without extensive experimental measurements.     

Stomatal regulation of photosynthesis in apple leaves: evidence for different water-use strategies between two cultivars

BACKGROUND AND AIMS: Leaf responses to environmental conditions have been frequently described in fruit trees, but differences among cultivars have received little attention. This study shows that parameters of Farquhar's photosynthesis and Jarvis' stomatal conductance models differed between two apple cultivars, and examines the consequences of these differences for leaf water use efficiency. METHODS: Leaf stomatal conductance (g(sw)), net CO2 assimilation rate (A(n)), respiration (R(d)) and transpiration (E) were measured during summer in 8-year-old 'Braeburn' and 'Fuji' apple trees under well-watered field conditions. Parameters of Farquhar's and Jarvis' models were estimated, evaluated and then compared between cultivars. Leaf carbon isotope discrimination (delta(13)C) was measured at the end of the growing season. KEY RESULTS: A single positive relationship was established between V(Cmax) (maximum carboxylation rate) and N(a) (leaf nitrogen concentration per unit area), and between J(max) (maximum light-driven electron transport rate) and N(a). A higher leaf R(d) was observed in 'Fuji'. The g(sw) responded similarly to increasing irradiance and leaf temperature in both cultivars. g(sw) responded to lower vapour pressure deficit in 'Fuji' than in 'Braeburn'. Maximal conductance (g(swmax)) was significantly smaller and A(n) was more limited by g(sw) in 'Braeburn' than 'Fuji'. Lower g(sw), E and higher intrinsic water use efficiency were shown in 'Braeburn' and confirmed by smaller leaf delta(13)C compared with 'Fuji' leaves. CONCLUSIONS: The use of functional model parameters allowed comparison of the two cultivars and provided evidence of different water use 'strategies': 'Braeburn' was more conservative in water use than 'Fuji', due to stomatal limitation of A(n), higher intrinsic water use efficiency and lower delta(13)C. These physiological traits need to be considered in relation to climate adaptation, breeding of new cultivars and horticultural practice.     

QTL analysis and candidate gene mapping for skin and flesh color in sweet cherry fruit (<Emphasis Type="Italic">Prunus avium</Emphasis> L.)

Sweet cherry (Prunus avium L.) skin and fruit colors vary widely due to differences in red and yellow pigment profiles. The two major market classes of sweet cherry represent the two color extremes, i.e., yellow skin with red blush and yellow flesh and dark mahogany skin with mahogany flesh. Yet, within these extremes, there is a continuum of skin and flesh color types. The genetic control of skin and flesh color in sweet cherry was investigated using a quantitative trait locus (QTL) approach with progeny derived from a cross between cherry parents representing the two color extremes. Skin and flesh colors were measured using a qualitative color-card rating over three consecutive years and also evaluated quantitatively for darkness/lightness (L*), red/green (a*), and yellow/blue (b*). Segregations for the color measurements (card, L*, a*, and b*) did not fit normal distributions; instead, the distributions were skewed towards the color of the dark-fruited parent. A major QTL for skin and flesh color was identified on linkage group (LG) 3. Two QTLs for skin and flesh color were also identified on LG 6 and LG 8, respectively, indicating segregation for minor genes. The significance and magnitude of the QTL identified on LG 3 suggests the presence of a major regulatory gene within this QTL interval. A candidate gene PavMYB10, homologous to apple MdMYB10 and Arabidopsis AtPAP1, is within the interval of the major QTL on LG 3, suggesting that PavMYB10 could be the major determinant of fruit skin and flesh coloration in sweet cherry.     

梨果各部分(皮、肉、核)钙运转动态的研究初报

以梨品种“黄花”为试材,研究了不同时期于果实的不同部位引入45Ca后各个部位放射性比活及钙分配比率变化。结果表明:(1)在幼果期,引入果肉的钙可快速向果皮与果核扩散,且向果皮扩散的速率较果核快;引入果核的钙也能向果肉中迅速运转。(2)在膨大期,引入果肉的钙可以向果皮、果核和种子扩散,但速率较幼果期慢;引入果核的钙基本上不向果皮和果肉运转。(3)在成熟期,引入果肉中的钙可以迅速向果皮与果核中积累,引入果核的钙向皮肉的运转微弱。     

Xylem, Phloem and Transpiration Flows in a Grape: Application of a Technique for Measuring the Volume of Attached Fruits to High Resolution Using Archimedes' Principle

The minute changes in volume of a grape berry which occur fromhour to hour were measured non-destructively in the field usingreadily available and cheap laboratory equipment and a modernelectronic balance. The method, applicable even to small (approximately10 g) fruits, is based on Archimedes' principle and gave a resolutionof about 1 part in 1 000 by measuring the buoyant upthrust experiencedby a berry when immersed in water. Volume data from control,pedicel-steamed, and detached berries were used to calculatethe magnitudes and directions of the fluid flows which tookplace through the stalk of the phloem and xylem streams andthrough the skin in the transpiration stream. In the latter stages of fruit development, after the onset ofripening, net volume growth more or less ceases in grapes althoughtheir rate of sugar import is at its strongest. Cessation ofvolume growth comes about because the strong inflow of sugarywater in the phloem is closely balanced in part by transpirationalwater loss through the skin and in part by the backflow of xylemwater to the parent vine. This xylem backflow appears to persistthroughout the diurnal cycle. The net backflow direction of the xylem stream, together withthe inability of the phloem stream to carry certain ions (notablycalcium), may explain how some mineral imbalance disorders arisein the later stages of fruit development. The intense manner in which fruiting sinks compete with vegetativesinks in Vitis finds its explanation in the breakdown of apoplast:symplast compartmentation in the berry which occurs around thetime of onset of ripening. The breakdown exposes the terminalsieve tubes of the berry to a highly negative water potentialenvironment, serving to increase both the speed and the concentrationof the translocation stream. Key words: Archimedes' principle, volume measurement, mineral nutrition, xylem, phloem, assimilate partitioning, fruit splitting     

Quantitation of dimethyl sulfoxide in solutions and tissues by high-performance liquid chromatography.

We have developed a rapid and simple method to determine the level of dimethyl sulfoxide (Me2SO) in both solutions and tissue samples. For analysis of Me2SO in a cryopreservation medium, the solution is simply diluted in 10% (vol/vol) methanol and centrifuged. Then an aliquot of the supernatant is assayed by high-performance liquid chromatography. For tissue samples, the wet weight is measured and the intact sample is extracted with 10% (vol/vol) methanol (e.g., 10 ml/g wet wt) in a sealed vial. The extract is then diluted and centrifuged, and an aliquot of the supernatant is assayed. The dry weight of the tissue is measured after the methanol-extracted sample is placed into either for 2 h and air-dried overnight. The water content of the tissue is calculated as the difference between the wet and the dry weights. The concentration of Me2SO in the aqueous compartment of the tissue can then be calculated by taking into account the concentration of Me2SO in the extract and the dilution factor, based on the tissue water volume and the volume of methanol used to extract the Me2SO. The calculated values for porcine myocardium samples correlated 1:1 with the actual Me2SO concentrations in the solutions in which the tissue samples were equilibrated. Finally, we present results documenting the usefulness of this assay by following the time course of Me2SO penetration into core versus peripheral regions of 1-cm3 samples of porcine myocardium.     

Errors in measuring water potentials of small samples resulting from water adsorption by thermocouple psychrometer chambers

The adsorption of water by thermocouple psychrometer assemblies is known to cause errors in the determination of water potential. Experiments were conducted to evaluate the effect of sample size and psychrometer chamber volume on measured water potentials of leaf discs, leaf segments, and sodium chloride solutions. Reasonable agreement was found between soybean (Glycine max L. Merr.) leaf water potentials measured on 5-millimeter radius leaf discs and large leaf segments. Results indicated that while errors due to adsorption may be significant when using small volumes of tissue, if sufficient tissue is used the errors are negligible. Because of the relationship between water potential and volume in plant tissue, the errors due to adsorption were larger with turgid tissue. Large psychrometers which were sealed into the sample chamber with latex tubing appeared to adsorb more water than those sealed with flexible plastic tubing. Estimates are provided of the amounts of water adsorbed by two different psychrometer assemblies and the amount of tissue sufficient for accurate measurements of leaf water potential with these assemblies. It is also demonstrated that water adsorption problems may have generated low water potential values which in prior studies have been attributed to large cut surface area to volume ratios.     

Roles of gibberellins in increasing sink demand in Japanese pear fruit during rapid fruit growth

Our previous work demonstrated that exogenous gibberellins (GAs) applications during rapid fruit growth significantly increases sink demand and results in a larger fruit in Japanese pear. In an attempt to unravel the mechanism of increased sink demand by applied GAs, the histology, cell wall components of the flesh, and carbon accumulation in the fruit were assessed for Japanese pear (Pyrus pyrifolia, cultivar ‘Kousui’), as were the activities of sucrose- and sorbitol-cleaving enzymes. Our results show that most vascular tissues occurred in core tissue with very little vascular tissue in the flesh. Application of a mixture of GA₃ + GA₄ in lanolin paste significantly increased the amount of ethanol-insoluble solids, e.g., total pectins, hemicellulose, and cellulose in the cell walls. There was a significantly increased sink demand (assessed by ¹³C accumulation in the fruit) by the applied GAs, and this increased sink strength was closely related to increased activities of cell wall-bound invertase in the core, neutral invertase and NAD-dependent sorbitol dehydrogenase in the flesh during rapid fruit growth. As well, concentrations of sorbitol and sucrose in the flesh were decreased by GA application, while glucose concentration increased. Most importantly, the fact that sink activity can be increased by GA application implies that endogenous GAs are likely to be important modulators for sugar metabolism. Hence, selecting for genotypes with elevated GA production in the growing fruit and increased activities of key enzymes for sugar metabolism could result in increased fruit size.     

Decrease in heart rates by artificial CO2 hot spring bathing is inhibited by beta1-adrenoceptor blockade in anesthetized rats.

To investigate the effects of carbon dioxide (CO2) hot spring baths on physiological functions, head-out immersion of urethane-anesthetized, fursheared male Wistar rats was performed. Animals were immersed in water (30 or 35 degrees C) with high-CO2 content ( approximately 1,000 parts/million; CO2-water). CO2-water for bathing was made by using an artificial spa maker with normal tap water and high-pressure CO2 from a gas cylinder. When a human foot was immersed for 10 min in the CO2-water at 35 degrees C, the immersed skin reddened, whereas skin color did not change in normal tap water at the same temperature. Arterial blood pressure, heart rate (HR), underwater skin tissue blood flow, and temperatures of the colon and immersed skin were continuously measured while animals were immersed in a bathtub of water for approximately 30 min at room temperature (26 degrees C). Immersed skin vascular resistance, computed from blood pressure and tissue blood flow, was significantly lower in the CO2-water bath than in tap water at 30 degrees C, but no differences were apparent at 35 degrees C. HR of rats in CO2-water was significantly slower than in tap water at 35 degrees C. Decreased HR in CO2-water was inhibited by infusion of atenolol (beta1-adrenoceptor blocker), but it was unaffected by atropine (muscarinic cholinoceptor blocker). Theses results suggest that bradycardia in CO2 hot spring bathing is caused by inhibition of the cardiac sympathetic innervation. This CO2-water maker should prove a useful device for acquiring physiological evidence of balneotherapy.     

Control of purple spot of loquat fruit (Eriobotrya japonica) by means of mineral compounds

Treatments to control purple spot of loquat fruit (Eriobotrya japonica) were tested based on the hypothesis that the disorder appears as a consequence of water unbalance between flesh and epidermal tissues caused by their different ability for sugar accumulation. Calcium nitrate, calcium chloride, Ca‐EDTA, ammonium nitrate and potassium nitrate at a concentration of 150 mm applied 2 weeks before fruit colour break reduced significantly the proportion of purple‐spotted fruit, giving rise to a reduction of water potential of the epidermal tissue that allows it to retain water. The most favourable date of treatment was during the 2 weeks prior to fruit colour break.     

Skin contraction with pulsed CO2 and erbium:YAG laser

The purpose of this study was to assess the physical response of skin to laser resurfacing in a real-time, quantitative fashion. The study was designed to assess skin contraction from two opposite standpoints. First, change in tension was measured during laser application while samples were held at constant length. Second, change in length of a sample under no tension was measured during laser treatment. These two disparate analyses represent the two possible extremes of the clinical situation in which skin exists under some tension with some laxity to allow for decrease in length. A custom apparatus with digital interface for skin tension measurements was used to produce single sample tracings of change in skin tension with laser treatment. Length change was measured for individual samples by continuous sonomicrometer readings. Individual sample data were then plotted in a time versus tension/length graph. Skin contracts immediately to a peak level and then relaxes to a sustained plateau level for both CO2 and erbium:YAG lasers. Increased contraction was noted when the beam penetrated into the dermis. Greater peak and plateau contraction is observed after the beam has penetrated into the dermis. Skin contraction varies directly with energy for CO2 and erbium:YAG laser. Findings were similar when skin tension was measured with the sample held at constant length and when length change was measured with the sample under no tension. Char left on the skin after a pass with CO2 laser substantially decreases skin contraction. High-density settings with CO2 laser yield pulse stacking, which effectively irradiates the same portion of tissue with char on it. Skin contraction varies inversely with computer pattern density settings for CO2 laser due to this pulse stacking effect. Density has little effect on skin contraction for the erbium:YAG laser because little char is generated. Histologic analysis identified a zone of coagulated dermis that correlates linearly with skin contraction.     

Fruit ripening in Vitis vinifera: spatiotemporal relationships among turgor, sugar accumulation, and anthocyanin biosynthesis

This study reports the first observations indicating the spatiotemporal relationships among genetic and physiological aspects of ripening in the berry of Vitis vinifera. At the onset of ripening in the red flesh variety Alicante Bouschet, colour development began in the flesh at the stylar end of the fruit and progressed toward the pedicel end flesh and into the skin. Tissue solute potential and cell turgor also decreased first in the flesh. The decrease in flesh solute potential was due to accumulation of sugars, glucose and fructose, an accumulation that is integral to ripening. Expression of the anthocyanin biosynthesis-related genes VvMybA and VvUFGT was linearly related to the decrease in solute potential. Expression of VvMybA, and to a lesser extent VvUFGT, was correspondingly low in green tissue, higher in the red, stylar end flesh of berries beginning to ripen, and greatest in red berries. In contrast, expression of the abscisic acid biosynthesis-related genes VvNCED1 and VvNCED2 was not correlated with the other spatiotemporal aspects of the onset of ripening. These results, together with earlier work showing that sugar accumulation and acid loss also begin in the stylar flesh in other varieties, indicate that ripening in the grape berry originates in the stylar end flesh.     

Analysis of Growth and Water Relations of Tomato Fruits in Relation to Air Vapor Pressure Deficit and Plant Fruit Load

The influence of air vapor pressure deficit (VPD) and plant fruit load on the expansion and water relations of young tomato fruits grown in a glasshouse were evaluated under summer Mediterranean conditions. The contributions of phloem, xylem and transpiration fluxes to the fruit volume increase were estimated at an hourly scale from the growth curves of intact, heat-girdled and detached fruits, measured using displacement transducers. High VPD conditions reduced the xylem influx and increased the fruit transpiration, but hardly affected the phloem influx. Net water accumulation and growth rate were reduced, and a xylem efflux even occurred during the warmest and driest hours of the day. Changes in xylem flux could be explained by variations in the gradient of water potential between stem and fruit, due to changes in stem water potential. Misting reduced air VPD and alleviated the reduction in fruit volume increase through an increase in xylem influx and a decrease in fruit transpiration. Under low fruit load, the competition for assimilates being likely reduced, the phloem flux to fruits increased, similarly to the xylem and transpiration fluxes, without any changes in the fruit water potential. However, different diurnal dynamics among treatments assume variable contributions of turgor and osmotic pressure in F3 and F6 fruits, and hypothetical short-term variations in the water potential gradient between stem and fruit, preventing xylem efflux in F3 fruits.     

Subcutaneous Bacteria in Turkey Carcasses

Two methods were employed to quantitate the subcutaneous bacteria in fresh, refrigerated, and frozen turkey carcasses. Relatively few bacteria were detected in the skin-flesh interface and in the flesh as compared with the number of bacteria on the skin surface and in the skin layer. No subcutaneous bacteria were detected in 49% of the skin-flesh interface and flesh samples. The number of bacteria detected in skin samples from carcasses chemically disinfected to kill skin surface bacteria was smaller than that in nondisinfected skin samples. These results indicate that the skin blending method used to quantify microorganisms on poultry carcass skin measures the skin layer flora and that the number of subcutaneous membrane or flesh bacteria measured is not normally large enough to have a significant influence on the results.     

梨贮藏过程中乙烯和钙调素动态及其与贮藏性的关系

对两个梨品种不同成熟期果实贮藏过程中,整个果实以及果皮、果肉、果心的乙烯释放变化及果肉、种子的钙调素(CaM)含量进行测定。结果表明:(1)黄花品种完整果实及不同部位乙烯释放量都高于耐贮藏的湘南品种,且启动乙烯生成和形成乙烯峰值的时间也早于湘南品种;(2)果实不同部位形成峰值的顺序均依次为果心、果肉、果皮;(3)果实呼吸跃变过程中,CaM含量伴随乙烯释放量的上升而升高,乙烯峰值过后,CaM含量下降,果实衰老。     

基于2b-RAD简化基因组测序的甜瓜遗传多样性分析

该研究利用2b-RAD(type IIB endonucleases restriction-site associated DNA)测序对28份厚皮甜瓜亲本材料的单核苷酸多态性(single nucleotide polymorphism,SNP)位点进行基因分型,分析其遗传多样性与亲缘关系,为甜瓜分子标记辅助育种提供科学依据。结果表明:(1)28份甜瓜种质SNPs数量有10318个,其发生转换与发生颠换的比值为2.15,两两种质间的遗传分化系数和遗传距离的平均值分别为0.88和2.22,说明这28份种质之间存在高度的遗传分化。(2)依据甜瓜的果皮颜色、果面网纹和果肉颜色3种性状,分别将以上28份种质分为4个群体(白皮群体、黄皮群体、青皮群体和绿皮群体)、3个群体(光皮群体、稀网群体和密网群体)以及3个群体(白肉群体、桔肉群体和绿肉群体)。(3)表型性状遗传分析结果显示,依据果皮颜色分类的各群体之间的遗传分化程度最高,其遗传分化系数在0.05~0.19之间,即均存在中度及以上程度的分化;光皮群体与密网群体之间存在中度遗传分化,但光皮群体与稀网群体之间以及稀网群体与密网群体之间均无显著分化;白肉群体与桔肉群体之间存在中度遗传分化,但白肉群体与绿肉群体之间以及桔肉群体与绿肉群体之间无明显分化。(4)分子系统进化树分析将28份甜瓜种质划分为三类,其中,第一类包含11份种质(主要为自主选育的纯合种质),第二类包含9份种质(大部分为从新疆引进或从新疆品种中选育出来的纯合种质),第三类包含8份种质(大部分为从日本引进或从日本品种中选育出来的纯合种质)。研究表明,依据甜瓜分子水平的聚类结果与地理来源具有一定关系,但其与育种者依据甜瓜的果皮颜色、果面网纹和果肉颜色对育种材料的分类结果不完全一致。     

Optimizing methods to estimate zooplankton concentration based on generalized patterns of patchiness inside ballast tanks and ballast water discharges

Zooplankton populations are spatially heterogeneous in nature and inside ship ballast tanks. Sampling methods should take heterogeneity into account, particularly when estimating quantitative variables such as abundance or concentration. It is particularly important to generate unbiased estimates of zooplankton concentration in ballast water when assessing compliance with new international ballast water discharge standards. We measured spatial heterogeneity of zooplankton within ballast water using three sampling methodologies. In‐tank pump samples were collected at fixed depths within the vertical part of the ballast tank (side tank). Vertical net‐haul samples were collected from the upper portion of the tank as a depth‐integrated and historically relevant method. In‐line, time‐integrated samples were collected during ballast discharge by an isokinetic sample probe, likely representing the double bottom part of the ballast tank. The bias and precision associated with each sampling method were evaluated in reference to the estimated average abundance of the entire ballast tank, which was modeled from the data collected by all methods. In‐tank pump samples provided robust evidence for vertical stratification of zooplankton concentration in the side tank. A consistent trend was also observed for in‐line discharge samples, with zooplankton concentration decreasing through time as the ballast tank is being discharged. Sample representativeness, as compared to the tank average, varied depending on the depth or tank volume discharged. In‐line discharge samples provided the least biased and most precise estimate of average tank abundance (having lowest mean squared error) when collected during the time frame of 20%–60% of the tank volume being discharged. Results were consistent across five trips despite differences in ballast water source, season, and age.     

The effect of a post-harvest heat-treatment on the storage behaviour of Cox's Orange Pippin apple fruits

Samples from a wide range of commercially grown Cox's Orange Pippin apple fruits were immersed in water at 45° C. for 10 min. to control rotting due to Gloeosporium spp. In two seasons the incidence of rotting following storage for 19 weeks at 3·3° C. (38° F.) was reduced to about 40% of the level in the untreated samples. However, there was a marked increase in the incidence of breakdown and core flush in the treated fruit, particularly when stored in a controlled atmosphere of 5% CO₂, 3 % O₂. A similar but less severe increase in the incidence of breakdown was also recorded in the second season in treated fruit stored in 2% O₂ (with continuous removal of CO₂). The treated fruit tended to develop a more yellow ground colour and softened more rapidly during storage in 5% CO₂, 3% O₂. It is concluded that the treatment advances fruit senescence and that the increased incidence of physiological disorders is likely to limit the use of this method for the control of Gloeosporium rotting in English-grown Cox apples.     

The effect of dynamic exercise on resting cold thermoregulatory responses measured during water immersion

The purpose of this study was to evaluate the effect of exercise on the subsequent post-exercise thresholds for vasoconstriction and shivering measured during water immersion. On 2 separate days, seven subjects (six males and one female) were immersed in water (37.5 degrees C) that was subsequently cooled at a constant rate of approximately 6.5 degrees C x h(-1) until the thresholds for vasoconstriction and shivering were clearly established. Water temperature was then increased to 37.5 degrees C. Subjects remained immersed for approximately 20 min, after which they exited the water, were towel-dried and sat in room air (22 degrees C) until both esophageal temperature and mean skin temperature (Tsk) returned to near-baseline values. Subjects then either performed 15 min of cycle ergometry (at 65% maximal oxygen consumption) followed by 30 min of recovery (Exercise), or remained seated with no exercise for 45 min (Control). Subjects were then cooled again. The core temperature thresholds for both vasoconstriction and shivering increased significantly by 0.2 degrees C Post-Exercise (P < 0.05). Because the Tsk at the onset of vasoconstriction and shivering was different during Pre- and Post-Exercise Cooling, we compensated mathematically for changes in skin temperatures using the established linear cutaneous contribution of skin to the control of vasoconstriction and shivering (20%). The calculated core temperature threshold (at a designated skin temperature of 32.0 degrees C) for vasoconstriction increased significantly from 37.1 (0.3) degrees C to 37.5 ( 0.3) degrees C post-exercise (P < 0.05). Likewise, the shivering threshold increased from 36.2 (0.3) degrees C to 36.5 (0.3) degrees C post-exercise (P < 0.05). In contrast to the post-exercise increase in cold thermal response thresholds, sequential measurements demonstrated a time-dependent similarity in the Pre- and Post-Control thresholds for vasoconstriction and shivering. These data indicate that exercise has a prolonged effect on the post-exercise thresholds for both cold thermoregulatory responses.