Inter- and intra-researcher variation in measurement of morphometrics on Steller sea lions (<Emphasis Type="Italic">Eumetopias jubatus</Emphasis>)

Substantial effort has been made to increase the accuracy of photogrammetric measurement techniques, especially on marine mammals. However, accuracy of the physical measurements is rarely considered when calculating the photogrammetric accuracy. We examined inter- and intra-researcher variation in the measurement of physical morphometrics of Steller sea lions (Eumetopias jubatus) to assess their potential effects on photogrammetric accuracy and body mass predictions based on photogrammetrically derived morphometrics. Significant differences were found inter-researcher in median standard length and axillary girth and intra-researcher when measuring axillary girth of the same animals. Photogrammetrically derived estimates of these parameters are comparable to physical measurements when taking into account the inherent inter- and intra-researcher variation.     

Reliability of reliability coefficients in the estimation of asymmetry

Although promising to provide insight into the interaction between genotype and environment, investigations into fluctuating asymmetry suffer from a lack of standardization in the reporting of measurement error. In the present paper we show, using both anthropometric and odonto-metric data, that the use of the reliability coefficient calculated for a bilateral measurement provides no indication of the reliability of the corresponding asymmetry estimate, because reliability of asymmetry depends on the relationship between measurement error and the difference between sides. Thus, we suggest that future investigations either provide reliability coefficients for asymmetry estimates specifically, or use methods that account for measurement error. © 1995 Wiley-Liss, Inc.     

Correlated changes in thermotolerance traits and body color phenotypes in montane populations of Drosophila melanogaster: analysis of within- and between-population variations

Thermotolerance traits vary across geographical gradients but there is a lack of clinal variation in some Drosophila species. Thus, it is not clear whether thermotolerance or other correlated traits are the target of natural selection. In order to test selection responses, we investigated body melanization and thermotolerance traits in six altitudinal populations of Drosophila melanogaster . Based on rearing different geographical populations under uniform growth conditions at 21 °C (common garden experiments), clinal variations for cold resistance are in the direction opposite to heat resistance along an altitudinal gradient, that is darker flies from highland populations evidenced higher levels of cold resistance while lowland populations showed higher heat resistance. Phenotypic plastic responses for body melanization at 17–28 °C showed significant correlations with thermotolerance traits. At 17 °C, regression coefficients as a function of altitude are highly significant and positive for cold resistance but negative for heat knockdown. However, for flies reared at 28 °C, there is no elevational change in melanization as well as thermotolerance traits. Thus, both genetic and plastic changes of body melanization and thermotolerance traits suggest a correlated selection response. Further, within-population analyses of body melanization (based on dark, intermediate and light color phenotypes) showed significant associations with thermotolerance traits. Correlated variations in body melanization and thermal tolerances are associated with climatic thermal variability ( T _cv) but not with T _min. or T _max. along an altitudinal gradient.     

A comprehensive assessment of geographic variation in heat tolerance and hardening capacity in populations of Drosophila melanogaster from eastern Australia

We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics, particularly for hardened flies, suggesting that tropical populations have a greater hardening response. A similar pattern was evident for ramping heat knockdown time at 0.06 °C min^?1 increase. There was no cline for ramping heat knockdown temperature (CT_max) at 0.1 °C min^?1 increase. Acute (static) heat knockdown temperature increased towards temperate latitudes, probably reflecting a greater capacity of temperate flies to withstand sudden temperature increases during summer in temperate Australia. Larval viability showed a quadratic association with latitude under heat stress. Thus, patterns of heat resistance depend on assay methods. Genetic correlations in thermotolerance across life stages and evolutionary potential for critical thermal limits should be the focus of future studies.     

Mitochondrial malic enzyme (ME2) in pancreatic islets of the human, rat and mouse and clonal insulinoma cells: Simple enzyme assay for mitochondrial malic enzyme 2

Despite interest in malic enzyme(ME)s in insulin cells, mitochondrial malic enzyme (ME2) has only been studied with estimates of mRNA or with mRNA knockdown. Because an mRNA’s level does not necessarily reflect the level of its cognate enzyme, we designed a simple spectrophotometric enzyme assay to measure ME2 activity of insulin cells by utilizing the distinct kinetic properties of ME2. Mitochondrial ME2 uses either NAD or NADP as a cofactor, has a high K_m for malate and is allosterically activated by fumarate and inhibited by ATP. Cytosolic ME (ME1) and the other mitochondrial ME (ME3) use only NADP as a cofactor and have lower K_ms for malate. The assay easily showed for the first time that substantial ME2 activity is present in pancreatic islets of humans, rats and mice and INS-1 832/13 cells. ME2’s presence was confirmed with immunoblotting. There was no evidence that ME3 is present in these tissues.     

Acquisition of thermotolerance in bay scallops, Argopecten irradians irradians, via differential induction of heat shock proteins

Many cells and organisms are rendered transiently resistant to lethal heat shock by short exposure to sublethal temperatures. This induced thermotolerance is thought to be related to increased amounts of heat shock proteins (HSPs) which, as molecular chaperones, protect cells from stress-induced damage. As part of a study on bivalve stress and thermotolerance, work was undertaken to examine the effects of sublethal heat shock on stress tolerance of juveniles of the northern bay scallop, Argopecten irradians irradians, in association with changes in the levels of cytoplasmic HSP70 and 40. Juvenile bay scallops heat-shocked at a sublethal temperature of 32 °C survived an otherwise lethal heat treatment at 35 °C for at least 7 days. As determined by ELISA, acquisition of induced thermotolerance closely paralleled HSP70 accumulation, whereas HSP40 accrual appeared less closely associated with thermotolerance. Quantification of scallop HSPs following lethal heat treatment, with or without conditioning, suggested a causal role for HSP70 in stress tolerance, with HSP40 contributing to a lesser, but significant extent. Overall, this study demonstrated that sublethal heat shock promotes survival of A. irradians irradians juveniles upon thermal stress and the results support the hypothesis that HSPs have a role in this induced thermotolerance. Exploitation of the induced thermotolerance response shows promise as a means to improve survival of bay scallops in commercial culture.     

Evolution of thermotolerance in seasonal environments: the effects of annual temperature variation and life-history timing in Wyeomyia smithii

In organisms with complex life cycles, the adaptive value of thermotolerance depends on life-history timing and seasonal temperature profiles. We illustrate this concept by examining variation in annual thermal environments and thermal acclimation among four geographic populations of the pitcher plant mosquito. Only diapausing larvae experience winter, whereas both postdiapause and nondiapause adults occur only during the growing season. Thus, adults experience transient cold stress primarily during the spring. We show that adult cold tolerance (chill coma recovery) is enhanced in spring-like conditions via thermal acclimation but is unaffected by diapause state. Moreover, adult mosquitoes from northern populations were more cold tolerant than those from southern populations largely because acclimation responses were steeper in the north. In contrast to cold tolerance, there was no significant acclimation of heat tolerance (heat knockdown), and no significant differences in heat tolerance between northern and southern populations. Field temperature data show that because of evolved differences in diapause timing, adult exposure to cold stress is remarkably consistent across geography. This suggests that geographic variation in cold tolerance may not be the result of direct selection on adults. Our results illustrate the importance of the interplay between phenological and thermal adaptation for understanding variation along climatic gradients.     

Heritability and Evolutionary Potential in Thermal Tolerance Traits in the Invasive Mediterranean Cryptic Species of Bemisia tabaci (Hemiptera: Aleyrodidae)

With advancing global climate change, the analysis of thermal tolerance and evolutionary potential is important in explaining the ecological adaptation and changes in the distribution of invasive species. To reveal the variation of heat resistance and evolutionary potential in the invasive Mediterranean cryptic species of Bemisia tabaci, we selected two Chinese populations—one from Harbin, N China, and one from Turpan, S China—that experience substantial heat and cold stress and conducted knockdown tests under static high- and low-temperature conditions. ANOVAs indicated significant effects of populations and sex on heat knockdown time and chill coma recovery time. The narrow-sense heritability (h ²) estimates of heat tolerance based on a parental half-sibling breeding design ranged from 0.47±0.03 to 0.51±0.06, and the estimates of cold tolerance varied from 0.33±0.07 to 0.36±0.06. Additive genetic variances were significantly different from zero for both heat and cold tolerance. These results suggest that invasive B. tabaci Mediterranean cryptic species possesses a strong ability to respond to thermal selection and develops rapid resistance to climate change.     

The capacity of Drosophila to heat harden associates with low rates of heat-shocked protein synthesis

The thermotolerance of a species or of an ecotype is important for determining its habitat range and vigour, and considerable research has focused on identifying underlying physiological, biochemical and genetic bases of thermotolerance traits. Rates of protein synthesis in tissues when organisms experience a sudden heat stress as occurs on rare hot days may be important to avoid heat-induced paralysis and to survive. While natural variation in Drosophila melanogaster thermotolerance has been associated with heat-shock gene expression, little attention has been given to examining the thermo-protective role of protein synthesis generally. Using two independently derived sets of single-pair mating lines, we characterised variation in rates of protein synthesis in dissected ovarian tissues, both before and after a heat shock applied at different severities in the two sets. In both sets of lines heat-shocked protein synthesis rates were negatively associated with the increase in heat knockdown tolerance after hardening. These associations occurred in a different sex in each set. Variation in rates of Hsp70 synthesis failed to associate with levels of heat tolerance or general protein synthesis. Our results suggest heritable variation in the rate of protein synthesis following heat stress, independently of Hsp70 variation, contributes to heat tolerance variation in this species.     

QTL for the thermotolerance effect of heat hardening, knockdown resistance to heat and chill-coma recovery in an intercontinental set of recombinant inbred lines of Drosophila melanogaster

The thermotolerance effect of heat hardening (also called short-term acclimation), knockdown resistance to high temperature (KRHT) with and without heat hardening and chill-coma recovery (CCR) are important phenotypes of thermal adaptation in insects and other organisms. Drosophila melanogaster from Denmark and Australia were previously selected for low and high KRHT, respectively. These flies were crossed to construct recombinant inbred lines (RIL). KRHT was higher in heat-hardened than in nonhardened RIL. We quantify the heat-hardening effect (HHE) as the ratio in KRHT between heat-hardened and nonhardened RIL. Composite interval mapping revealed a more complex genetic architecture for KRHT without heat-hardening than for KRHT in heat-hardened insects. Five quantitative trait loci (QTL) were found for KRHT, but only two of them were significant after heat hardening. KRHT and CCR showed trade-off associations for QTL both in the middle of chromosome 2 and the right arm of chromosome 3, which should be the result of either pleiotropy or linkage. The major QTL on chromosome 2 explained 18% and 27-33% of the phenotypic variance in CCR and KRHT in nonhardened flies, respectively, but its KRHT effects decreased by heat hardening. We discuss candidate loci for each QTL. One HHE-QTL was found in the region of small heat-shock protein genes. However, HHE-QTL explained only a small fraction of the phenotypic variance. Most heat-resistance QTL did not colocalize with CCR-QTL. Large-effect QTL for CCR and KRHT without hardening (basal thermotolerance) were consistent across continents, with apparent transgressive segregation for CCR. HHE (inducible thermotolerance) was not regulated by large-effect QTL.     

Improvement of the heat pulse method for determining sap flow in trees

Abstract. The heat pulse method for determining sap flux in large woody sterns was modified for easier field operation. It uses the measurement of the time elapsed between heat pulse release by a line heater radially inserted in the stem, and the occurrence of maximum temperature 15 mm downstream of the heater. This spacing between heater and thermometer is critical to the reliability of the measurement. Calculations using uncorrected theory provide estimates of the sap flux density in stems with both uniform and non-uniform cross-sectional distribution of conducting tissues which are about 55% of the actual sap flux density. This factor results from insufficient thermal homogeneity between tissues where sap flow occurs and tissues where sap flow has been interrupted.
Sap flow in trunks of citrus trees was inferred from measurements of the cross-sectional distribution of sap flux density. Variability of sap flux density is specific to each trunk and is time-dependent and imposes multiple radial and angular measurements. The method was checked in a citrus trunk ramified into three branches. Instantaneous determinations of the flow in the trunk and in the branches differed by less than 5.7%. The daily values agreed within 2.8%.     

The statistical analysis of fluctuating asymmetry: REML estimation of a mixed regression model

The unbiased estimation of fluctuating asymmetry (FA) requires independent repeated measurements on both sides. The statistical analysis of such data is currently performed by a two-way mixed ANOVA analysis. Although this approach produces unbiased estimates of FA, many studies do not utilize this method. This may be attributed in part to the fact that the complete analysis of FA is very cumbersome and cannot be performed automatically with standard statistical software. Therefore, further elaboration of the statistical tools to analyse FA should focus on the usefulness of the method, in order for the correct statistical approaches to be applied more regularly. In this paper we propose a mixed regression model with restricted maximum likelihood (REML) parameter estimation to model FA. This routine yields exactly the same estimates of FA as the two-way mixed ANOVA . Yet the advantages of this approach are that it allows (a) testing the statistical significance of FA, (b) modelling and testing heterogeneity in both FA and measurement error (ME) among samples, (c) testing for nonzero directional asymmetry and (d) obtaining unbiased estimates of individual FA levels. The switch from a mixed two-way ANOVA to a mixed regression model was made to avoid overparametrization. Two simulation studies are presented. The first shows that a previously proposed method to test the significance of FA is incorrect, contrary to our mixed regression approach. In the second simulation study we show that a traditionally applied measure of individual FA [abs(left – right)] is biased by ME. The proposed mixed regression method, however, produces unbiased estimates of individual FA after modelling heterogeneity in ME. The applicability of this method is illustrated with two analyses.     

Effect of thermotolerance on thermal radiosensitization in hepatoma cells

The interaction between hyperthermia and X irradiation was determined in cultured Reuber H35 hepatoma cells with different states of thermosensitivity. Incubation at 41 degrees C followed by 4-Gy X rays resulted after 2 hr in a stabilization of cell survival for heat or plus X rays, with a maximum synergism factor of 1.6. Thermotolerance did not develop during incubation at 41.7 or 42.5 degrees C. When heat treatment of cells was followed by irradiation, the synergism factor for thermal radiosensitization increased with both the amount of thermal cell killing and the amount of X-ray cell killing; the influence of thermal exposure on the synergism factor was greater than that of the X-ray dose. Cells were made thermotolerant either by incubation at 42.5 degrees C for 30 or 60 min followed by an interval at 37 degrees C, or by continuous incubation at 41 degrees C. In both cases thermotolerance was measured by incubation at 42.5 degrees C. No difference was observed between the maximum thermotolerance achieved with both methods. When cells were irradiated in addition to the second heat treatment, thermal radiosensitization was strongly reduced concomitant with the decreased sensitivity to killing by heat.     

Multistage evaluation of measurement error in a reliability study

We introduce sequential testing procedures for the planning and analysis of reliability studies to assess an exposure's measurement error. The designs allow repeated evaluation of reliability of the measurements and stop testing if early evidence shows the measurement error is within the level of tolerance. Methods are developed and critical values tabulated for a number of two-stage designs. The methods are exemplified using an example evaluating the reliability of biomarkers associated with oxidative stress.     

Seasonal thermal tolerance in marine Crustacea

Seasonal values of the critical thermal maximum (CTMax) of eight species of adult marine Crustacea from temperate latitudes were measured and found to range between 20 and 34 °C. The extent to which CTMax was dependent on acclimatization varied with species but for most of the species studied, summer-captured animals had significantly higher CTMax values than winter-captured animals. Heat shock resulted in an increase in thermotolerance in most species in winter-captured animals, but a different pattern was found for summer-captured animals. Then, only Cancer pagurus and Pagurus bernhardus showed a positive increment of CTMax on heat shock. Test for Serial Independence analysis indicated no significant phylogenetic autocorrelation between CTMax values in winter or summer-captured animals. Temperature measurements taken by remote data loggers in the intertidal zone of the North-East coast of England are reported. These suggest that several species, whose distribution extends into the intertidal zone, may experience temperatures close to their CTMax in summer.     

Cold activity of Beauveria and Metarhizium, and thermotolerance of Beauveria

Heat and cold are environmental abiotic factors that restrict the use of entomopathogenic fungi as agents for biological control of insects. The thermotolerance and cold activity of 60 entomopathogenic fungal isolates, including five species of Beauveria and one isolate of Engyodontium albus (=Beauveria alba) were examined as to tolerance of temperatures that might be encountered during field use. In addition, cold activity of eight Metarhizium spp. isolates was evaluated. The isolates were from various geographic regions, arthropod hosts or substrates. High variability in conidial thermotolerance was found among the Beauveria spp. isolates after exposure to 45 °C for 2 h, as evidenced by low (0-20%), medium (20-60%), or high germination (60-80%). The thermal death point (0% germination) for three rather thermotolerant B. bassiana isolates (CG 138, GHA and ARSEF 252) was 46 °C for 6 h. At low temperatures (5 °C), with few exceptions (e.g. CG 66, UFPE 479, CG 227, CG 02), most of the B. bassiana isolates germinated well (ca. 100%). On the other hand, only one isolate of Metarhizium sp. was cold-active (i.e. ARSEF 4343 from Macquarie Island, 54.4°S, Australia). This probably is a M. frigidum isolate. The E. albus isolate (UFPE 3138) was the most susceptible isolate to both heat and cold stress. Isolates ARSEF 252 and GHA of B. bassiana, on the other hand, presented exceptionally high thermotolerance and cold activity. Some isolates with high cold activity, however, were thermosensitive (e.g. ARSEF 1682) and others with high thermotolerance had low cold activity (e.g. CG 227). An attempt to correlate the latitude of origin with thermotolerance or cold activity indicated that B. bassiana isolates from higher latitudes were more cold-active than isolates from nearer the equator, but there was not a similar correlation for heat.     

运用CT三维重建测量重度先天性脊柱侧凸Cobb角的临床应用

目的:评价在CT三维重建上测量重度先天性脊柱侧凸Cobb角度的可重复性和可靠性。方法:收集在我院诊治的重度先天性脊柱侧凸病人的CT三维重建和脊柱全长X线片,共计67例。由五名不同测量者对CT三维重建脊柱畸形冠状面主弯Cobb角测量两次,两次间隔在三周以上,并测量脊柱全长X线片脊柱畸形冠状面主弯Cobb角一次,运用组内相关系数分析测量结果之间的可重复性和可靠性。结果:同一测量者两次测量结果之间的差值平均为4.5°。同一测量者两次测量结果之间的组内相关系数为0.969,不同测量者之间测量结果的组内相关系数为0.913。取五名测量者在CT三维重建上第一次测量的Cobb角度,其平均值为(110.5±23.5)°,五名测量者在X线片上测量结果的平均值为(103.1±22.0)°,对两组数据进行Mann-Whitney非参数检验差异有统计学意义(Z=-2.86,P=0.004)。结论:在CT三维重建上测量重度先天性脊柱侧凸的Cobb角,可以减小测量的误差,提高测量的可重复性和可靠性,是一种相对准确的测量方法。     

“Edge-on” MOSkin detector for stereotactic beam measurement and verification

Dosimetry in small radiation field is challenging and complicated because of dose volume averaging and beam perturbations in a detector. We evaluated the suitability of the “Edge-on” MOSkin (MOSFET) detector in small radiation field measurement. We also tested the feasibility for dosimetric verification in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). “Edge-on” MOSkin detector was calibrated and the reproducibility and linearity were determined. Lateral dose profiles and output factors were measured using the “Edge-on” MOSkin detector, ionization chamber, SRS diode and EBT2 film. Dosimetric verification was carried out on two SRS and five SRT plans. In dose profile measurements, the “Edge-on” MOSkin measurements concurred with EBT2 film measurements. It showed full width at half maximum of the dose profile with average difference of 0.11 mm and penumbral width with difference of ±0.2 mm for all SRS cones as compared to EBT2 film measurement. For output factor measurements, a 1.1% difference was observed between the “Edge-on” MOSkin detector and EBT2 film for 4 mm SRS cone. The “Edge-on” MOSkin detector provided reproducible measurements for dose verification in real-time. The measured doses concurred with the calculated dose for SRS (within 1%) and SRT (within 3%). A set of output correction factors for the “Edge-on” MOSkin detector for small radiation fields were derived from EBT2 film measurement and presented. This study showed that the “Edge-on” MOSkin detector is a suitable tool for dose verification in small radiation field.