Drop weight variation in an automated collection procedure and its relationship to apparent surface tension.

A drop counter-regulated fraction collector yields samples containing equal numbers of drops. Such fractions vary slightly in weight depending on experimental conditions such as surface tension. Provided that variables such as flow rate and eluate density remain constant, apparent surface tension may be estimated directly from the weights of eluate fractions obtained from gel filtration experiments. The detergents sodium cholate and sodium lauryl sulphate significantly decreased drop weights in this system. Following gel filtration on Sepharose 4B, sodium cholate eluted in the fractions containing low molecular weight material. It eluted in the same position when pre-mixed with human plasma. Normal plasma was found to contain two surface tension-reducing components with apparent molecular weights of 3-10(6) and 1-10(5). The apparent surface tension of whole human plasma was found to be time dependent and decreased as the flow rate was reduced.     

Prediction of surface area in polydisperse gas-suspension systems with variable apparent surface tension,viscosity and density

Bubble size distribution was found to be represented by a modified log-normal distribution with 3 parameters. The parameters are simple functions of suspension properties,viz. surface tension, viscosity and density, and a function of superficial gas rate. Correlations are presented, enabling the prediction of the distribution constants (and thus of the bubble size distribution) from the system properties and gas rate. Model translucent systems can be used, having identical apparent system properties as real suspensions in experimental work. A computer algorithm is presented for (i) prediction of bubble size distribution, defining the region of formation of spherical bubbles, (ii) converting particle size distribution into volume distribution, (iii) determining the actual gas volume from a hold-up correlation, and (iv) giving the surface area of the system of a given predicted distribution.     

Phenylthiocarbamide taste sensitivity and its relationship to growth variation

The hypothesis that there is a relationship between the tasting polymorphism and growth variation was tested on a sample of 425 Negro elementary school children. Twenty-seven non-tasters were found by testing with impregnated papers; 13 were male, 14 female, indicating no sex differences in this group. Matchedpair comparisons indicated no differences in weight, a tendency for tasters to be taller, and a stronger tendency for tasters of both sexes to be skeletally more mature. It was felt that the tendency for tasters to be taller might reflect their more advanced maturation status. The relationship to skeletal maturation might be indicative of the decreased thryoid activity found in other studies of phenylthiocarbamide tasting.     

Genetic determinism for within-litter birth weight variation and its relationship with litter weight and litter size in the Ripollesa ewe breed

Birth weight plays a central role in lamb survival and growth, and the knowledge of its genetic determinism has become essential in worldwide selection programmes. Within this context, within-litter birth weight variation (BWV) has been suggested as an attractive trait to homogenise litters in prolific species, although it has not been analysed in sheep. The objective of this study was to ascertain whether maternal additive genetic variance exists for BWV in Ripollesa ewes, and to study its genetic, permanent environmental and residual relationships with litter weight (LW) and litter size (LS) at birth. Data were recorded in the Ripollesa experimental flock of the Universitat Autònoma of Barcelona, between 1986 and 2005, and included 1 662 litters from 380 ewes, with 712 records of BWV and 1 530 records of LW. Traits were analysed with a multivariate animal model solved through Bayesian methodologies, and with a threshold characterisation of LS. Additionally, the effect of BWV on lamb survival was studied. Additive genetic variance was observed for BWV (h² = 0.061), as well as for LW (h² = 0.200) and LS (h² = 0.141). Nevertheless, genetic correlations among those traits were not substantial (BWV and LW = 0.151; BWV and LS = − 0.219; LW and LS = − 0.320) and suffered from a high degree of uncertainly, with the null correlation included within the highest posterior interval at 95%. Within-litter birth weight variation and LS showed a negative and large permanent environmental correlation ( − 0.872), and LW and LS were negatively correlated due to residual ( − 0.762) and permanent environmental ( − 0.449) random sources of variation. Within-litter birth weight variation influenced lamb mortality during the first 7 days of life (P < 0.05), increasing and decreasing survivability in heavier and lighter littermates, respectively. Nevertheless, stillbirths and lambs died after the 1st week of life were not affected by BWV (P>0.05). The low heritability found indicates that slow genetic progress may be expected from selecting for BWV. Close to zero genetic correlations suggest that this selection will probably not affect LS and LW, although some significant permanent and residual correlations must be taken into account. Further studies are needed to understand better the genetic architecture among these three reproductive traits.     

Species composition and standing crop variation in an unfertilized meadow and its relationship to climatic variability during six years

Year-to-year variability of species composition and hay yield were investigated during a six-year period (1988–1993) in a traditionally mown meadow of great species richness at Negrentino in southern Switzerland Climatic parameters (temperature duration of sunshine, global radiation, precipitation, evaporation, relative moisture) measured at a nearby weather station were calculated for ten-day units and compared to quantitative vegetation data. Yields of the first and second harvest were positively correlated with the mean relative moisture during the first and second growth period. Distinct variation patterns were recognized among the 48 species and interpreted as direct or indirect responses of interacting species to climatic conditions during three periods of the year. The first variation pattern including abundant graminoids reflects a strong direct effect by weather conditions in the first growth period. Species of the other variation patterns responsed differently to extreme summer droughts with apparent time-lags. Some species reflect warm and humid conditions in early spring followed by dry conditions in a particular year; others combine features of different variation patterns. *** DIRECT SUPPORT *** A02DO006 00002     

Ring distraction technique for measuring surface tension of sputum: relationship to sputum clearability

Albers, G. M., R. P. Tomkiewicz, M. K. May, O. E. Ramirez,and B. K. Rubin. Ring distraction technique for measuring surfacetension of sputum: relationship to sputum clearability. J. Appl. Physiol. 81(6):2690-2695, 1996.Poor sputum clearance has been related to sputumadhesion tension. In this study, we describe a modified du Noüyring method for measuring the surface tension () of small samples ofsputum and for comparinge the calculated work of adhesion(W_ad) for sputum specimens withthe measured mucociliary transportability (MCTR) and coughtransportability (CTR). The , as measured by this method, correlateswith  measured by sputum contact angle on a low-surface-energy solid(R² = 0.368, P = 0.03). There is a smallbut significant difference in measurements made by these two methods(P = 0.03).W_ad calculated from the surfacetension ring method is inversely correlated with CTR(R² = 0.181, P = 0.004) but has nocorrelation with MCTR in this study. The miniaturized ring method givesaccurate and reproducible measurements of the surface tension of smallamounts of respiratory secretions. Because sputum behaves enough like aliquid that the assumptions made in using the Young equation tocalculate W_ad appear valid, wealso showed that the Neumann equation can be used to determine thesurface tension of sputum by its contact angle on tetrafluoroethylene(Teflon).

     

Assessing genetic diversity in a sugarcane germplasm collection using an automated AFLP analysis

An assessment of genetic diversity within and between Saccharum, Old World Erianthus sect. Ripidium, and North American E.giganteus (S.giganteum) was conducted using Amplified Fragment Length Polymorphism (AFLP^TM) markers. An automated gel scoring system (GelCompar^TM) was successfully used to analyse the complex AFLP patterns obtained in sugarcane and its relatives. Similarity coefficient calculations and clustering revealed a genetic structure for Saccharum and Erianthus sect. Ripidium that was identical to the one previously obtained using other molecular marker types, showing the appropriateness of AFLP markers and the associated automated analysis in assessing genetic diversity in sugarcane. A genetic structure that correlated with cytotype (2n=30, 60, 90) was revealed within the North American species, E. giganteus (S.giganteum). Complex relationships among Saccharum, Erianthus sect. Ripidium, and North American E.giganteus were revealed and are discussed in the light of a similar study which involved RAPD markers. This revised version was published online in July 2006 with corrections to the Cover Date.     

A fungal lectin and its apparent receptors on a nematode surface

Abstract A lectin was isolated from the nematode-trapping fungus Arthrobotrys oligospora . This carbohydrate-binding protein was developmentally regulated and was found only on trap-bearing mycelia. The lectin receptor on the surface of the nematode Panagrellus redivivus has, furthermore, been investigated using homogenates from whole nematodes or nematode cuticle. The ability of macromolecules from nematodes, fractionated according to M _r and lectin affinities, to inhibit the capture of nematodes by A. oligospora was tested using an inhibition assay, based on a simple dialysis membrane technique. One major lectin-binding glycoprotein, with apparent M _r of 65 000, was isolated from the nematode cuticle.     

An automated procedure to measure DNA synthesis in preimplantation mouse embryos

This paper describes a sensitive, reproducible, and automated procedure to measure DNA synthesis in preimplantation mouse embryos. Conditions for the DNA synthesis assay have been optimized as follows: (1) 4 μCi/ml³H-thymidine (sp. act. 20 Ci/immole); (2) a labeling period from 2 to 7 hours; (3) a 3-hour preincubation period for blastocysts and from 0 to 7 hours preincubation for 8-cell embryos; and (4) from 1 to 64 embryos per assay. The amount of DNA synthesis per embryo was found to be directly proportional to the number of cells (nuclei) per embryo. The described assay should be useful for future studies on the effect of synthetic and natural compounds on the development of preimplantation mouse embryos, as measured by perturbations in embryonic DNA synthetic activity.     

Fine-scale spatial variation in plant species richness and its relationship to environmental conditions in coastal marshlands

Previous studies have shown that variations in environmental conditions play a major role in explaining variations in plant species richness at community and landscape scales. In this study, we considered the degree to which fine-scale spatial variations in richness could be related to fine-scale variations in abiotic and biotic factors. To examine spatial variation in richness, grids of 1 m² plots were laid out at five sites within a coastal riverine wetland landscape. At each site, a 5 × 7 array of plots was established adjacent to the river’s edge with plots one meter apart. In addition to the estimation of species richness, environmental measurements included sediment salinity, plot microelevation, percent of plot recently disturbed, and estimated community biomass. Our analysis strategy was to combine the use of structural equation modeling (path modeling) with an assessment of spatial association. Mantel’s tests revealed significant spatial autocorrelation in species richness at four of the five sites sampled, indicating that richness in a plot correlated with the richness of nearby plots. We subsequently considered the degree to which spatial autocorrelations in richness could be explained by spatial autocorrelations in environmental conditions. Once data were corrected for environmental correlations, spatial autocorrelation in residual species richness could not be detected at any site. Based on these results, we conclude that in this coastal wetland, there appears to be a fine-scale mapping of diversity to microgradients in environmental conditions.     

Quantitative determination of aliphatic diamines and polyamines by an automated liquid chromatography procedure

The naturally occurring aliphatic polyamines and diamines can be separated with an improved automated procedure on a sulfonated-type ion-exchange column. Quantitative determinations can be carried out on 2–20 nmoles of each amine.In addition to the simple diamines, spermidine, and spermine, this procedure separates a number of naturally occurring derivatives, such as monoacetyl-1,4-diaminobutane, monoacetylspermidine, carbamyl-1,4-diaminobutane, 1,4-diamino-2-hydroxybutane, and glutathionylspermidine.The method can be used for a variety of biological materials, including urine, animal tissues, and bacterial extracts.     

Two-point fluorescence detection and automated fraction collection applied to constant denaturant capillary electrophoresis

Constant denaturant capillary electrophoresis (CDCE) has been shown to be a sensitive method to detect point mutations in DNA sequences of 100-bp lengths. Here, we report a significant modifications for the instrumental setup that allows a highly accurate prediction of the elution time of DNA fragments from the capillary and an efficient collection of separated fractions. Fluorescently labeled DNA fragments of TP53 exon 8 wild-type and two mutants (base pair number 14480 and 14525) are detected at two separate points of the same capillary. This permits the precise calculation of the fragment velocity after separation in the heated zone because, at room temperature, all DNA fragments of the same length have the same velocity. Such precision permits the selective collection of separated fragments using an automated fraction collector for additional CDCE analysis or sequencing. Also, the two-point detection allows one to rapidly distinguish between double-stranded and single-stranded DNA fragments of the same length, a process that cannot be achieved with a one-point detection system alone. Both modifications greatly improve the procedure to detect novel mutations by means of CDCE.     

The relationship between obesity and seasonal variation in body weight among elementary school children in Tokyo

Typical patterns of seasonal variation in body weight among Japanese children involve increases during the fall and/or winter and decreases during the summer. However, atypical variations, namely, increases in weight during the summer, have been reported for obese children. The present study examines whether weight gain during the summer (i.e., July through September) is a possible cause of obesity. We examined seasonal changes in weight for 446 elementary school children in Tokyo in six waves between 1972 and 2004. Weight was measured monthly for 6 years in each child and was evaluated by means of time-series analysis. Overall, significant seasonal variations in weight were found in 86% of the children, most of which were typical (i.e., decreases during the summer and increases during the fall, winter, and/or early spring). On the other hand, weight gain in the summer was observed exclusively among obese children. Children whose weight increased during the summer holiday spent most of their time comfortably indoors because of air conditioners, which became popular in 1970s. A possible explanation of the observed weight gain during the summer seems to be changes in life style associated with the use of air conditioning, concomitant with insufficient physical exercise and excessive consumption of food and drink, which could disturb the rhythms of seasonal weight changes and lead to obesity.     

Seasonal variation in testes size in Polish Merino rams and its relationship to reproductive performance in spring

Observations relating testes size to body weight in growing and adult Polish Merino rams were performed during 3 consecutive years in a flock of 1700 pedigree ewes. October-born ram lambs were measured for testis diameter (TD), scrotal circumference (SC), and body weight (BW) at 100 (January), 150 (March), 180 (April), 240 (June), 365 (October), and 480 d (February) of age. In adult rams (n = 63 to 73 per year) BW and SC were measured in March, May (prior to breeding), August and October. Semen quality was evaluated before each breeding season, and the results of controlled reproductive performance (2 natural services to designated rams) were analyzed. Indices were applied to relate testis size to body weight: TD BW , SC BW and TW BW . Heritability estimates of testes indices in ram lambs at 100 to 240 d and at 480 d of age ranged from 0.21 to 0.36 (SE = 0.067 to 0.090). In adult rams SC measurements within months in consecutive years were repeatable (r = 0.55 to 0.68; P相似文献   

Proportion with low birth weight infants in an Indian population and its relationship with maternal age and parity.

The overall proportion of low birth weight infants is found to be relatively higher in the Indian population. Data collected from two hospitals in Calcutta, India indicate that although the proportion of infants weighing less than 2,001 g is approximately 10%, the dependence of this proportion on maternal age and parity is similar to the studies conducted elsewhere, suggesting a definite biological significance of the phenomenon. The proportion of low birth weight infants is found to be the greatest for the first and late pregnancies, the minimum being at the third birth rank. Young mothers showed a tendency to have an increasing proportion of low birth weight infants with increasing birth order; whereas for older mothers a general U-shaped dependence of the proportion on parity is suggest from the analysis.     

Intraspecific variation in seed dispersal of a Neotropical tree and its relationship to fruit and tree traits

The distribution of wind‐dispersed seeds around a parent tree depends on diaspore and tree traits, as well as wind conditions and surrounding vegetation. This study of a neotropical canopy tree, Platypodium elegans, explored the extent to which parental variation in diaspore and tree traits explained (1) rate of diaspore descent in still air, (2) distributions of diaspores dispersed from a 40‐m tower in the forest, and (3) natural diaspore distributions around the parent tree. The geometric mean rate of descent in still air among 20 parents was highly correlated with geometric mean wing loading^1/2 (r = 0.84). However, diaspore traits and rate of descent predicted less variation in dispersal distance from the tower, although descent rate⁻¹ consistently correlated with dispersal distance. Measured seed shadows, particularly their distribution edges, differed significantly among six parents (DBH range 62–181 cm) and were best fit by six separate anisotropic dispersal kernels and surveyed fecundities. Measured rate of descent and tree traits, combined in a mechanistic seed dispersal model, did not significantly explain variation among parents in natural seed dispersal distances, perhaps due to the limited power to detect effects with only six trees. Seedling and sapling distributions were at a greater mean distance from the parents than seed distributions; saplings were heavily concentrated at far distances. Variation among parents in the distribution tails so critical for recruitment could not be explained by measured diaspore or tree traits with this sample size, and may be determined more by wind patterns and the timing of abscission in relation to wind conditions. Studies of wind dispersal need to devote greater field efforts at recording the “rare” dispersal events that contribute to far dispersal distances, following their consequences, and in understanding the mechanisms that generate them.