THE RATIO OF CALCAREOUS AND ORGANIC SHELL COMPONENTS OF FRESHWATER SPHAERIID CLAMS IN RELATION TO WATER HARDNESS AND TROPHIC CONDITIONS

Shells from 14 populations of sphaeriid clams including Sphaeriumstriatinum, S. simile, Pisidium walkeri, Musculim partumeiumand M. iransversum were analyzed for organic carbon (µgCmg^–1 shell), nitrogen (µg,N mg^–1 shell) andCaCO_s (%CaCO₃ of total clam dry weight). Habitat waters wereassessed for total hardness (expressed as ppm CaCo₃), ppm Ca,ppm Mg, conductivity (µmho) and suspended organic Carbon(µgCl^–1). For all populations, shell organic C andN are positively correlated and there is an inverse relationshipbetween the amounts of shell CaCO₃ and shell organic carbon.Trophic considerations give the best correlation with shelltype at the generic level of consideration since species ofMusculium are found at the opposite end of the trophic scale(eutrophic) from all other populations studied. For S. striatinum,the most extensively studied species, the amount of shell CaCO₃is inversely related to water hardness. The selection of shellsin the Sphaeriidae is discussed in relation to structural-functionalneeds and habitat conditions ¹ Present Address: Department of Biology, Syracuse University,Syracuse, New York 13210, U.S.A. ² Present Address: Department of Zoology, Miami University,Oxford, Ohio 45056, U.S.A. (Received 5 December 1978;     

Cutting xylem under tension or supersaturated with gas can generate PLC and the appearance of rapid recovery from embolism

We investigated the common assumption that severing stems and petioles under water preserves the hydraulic continuity in the xylem conduits opened by the cut when the xylem is under tension. In red maple and white ash, higher percent loss of conductivity (PLC) in the afternoon occurred when the measurement segment was excised under water at native xylem tensions, but not when xylem tensions were relaxed prior to sample excision. Bench drying vulnerability curves in which measurement samples were excised at native versus relaxed tensions showed a dramatic effect of cutting under tension in red maple, a moderate effect in sugar maple, and no effect in paper birch. We also found that air injection of cut branches (red and sugar maple) at pressures of 0.1 and 1.0 MPa resulted in PLC greater than predicted from vulnerability curves for samples cut 2 min after depressurization, with PLC returning to expected levels for samples cut after 75 min. These results suggest that sampling methods can generate PLC patterns indicative of repair under tension by inducing a degree of embolism that is itself a function of xylem tensions or supersaturation of dissolved gases (air injection) at the moment of sample excision. Implications for assessing vulnerability to cavitation and levels of embolism under field conditions are discussed.     

Are atypical depression,borderline personality disorder and bipolar II disorder overlapping manifestations of a common cyclothymic diathesis?

The constructs of atypical depression, bipolar II disorder and borderline personality disorder (BPD) overlap. We explored the relationships between these constructs and their temperamental underpinnings. We examined 107 consecutive patients who met DSM-IV criteria for major depressive episode with atypical features. Those who also met the DSM-IV criteria for BPD (BPD+), compared with those who did not (BPD-), had a significantly higher lifetime comorbidity for body dysmorphic disorder, bulimia nervosa, narcissistic, dependent and avoidant personality disorders, and cyclothymia. BPD+ also scored higher on the Atypical Depression Diagnostic Scale items of mood reactivity, interpersonal sensitivity, functional impairment, avoidance of relationships, other rejection avoidance, and on the Hopkins Symptoms Check List obsessive-compulsive, interpersonal sensitivity, anxiety, anger-hostility, paranoid ideation and psychoticism factors. Logistic regression revealed that cyclothymic temperament accounted for much of the relationship between atypical depression and BPD, predicting 6 of 9 of the defining DSM-IV attributes of the latter. Trait mood lability (among BPD patients) and interpersonal sensitivity (among atypical depressive patients) appear to be related as part of an underlying cyclothymic temperamental matrix.     

COMPARING TRANS-FAT AND TRANS-FAT-FREE DOUGHNUT SHORTENINGS BASED ON SENSORY EVALUATION AND OIL DEGRADATION

This is an initiative study on the use of trans -fat-free products in the bakery industry. A standardized doughnut product was cooked in three doughnut shortenings, one containing trans fat and two that were trans fat-free. Six hundred forty-one panelists, students, faculty and staff of a large northeastern university rated each of the three doughnuts on a variety of categories, including texture, moisture content and overall liking. Results showed that there were no significant differences between doughnuts cooked in the three shortenings – this was true for all attributes tested.
The results from this study have many significant implications for the foodservice industry, as they work to cut down or eliminate the use of trans fats in their establishments because of the significant health risks they have been proven to cause.

PRACTICAL APPLICATIONS

This study demonstrates the variances on texture, taste, appearance and overall liking characteristics of doughnuts fried in different doughnut shortenings. The nutritional breakdown of the doughnuts and the shortenings are also addressed. In the case of shortenings, the ideal type of fat is a mixture of canola, soybean and hydrogenated cottonseed. This shortening mixture, which is trans fat-free, produced the most preferred doughnut.     

Modelled hydraulic redistribution by sunflower (Helianthus annuus L.) matches observed data only after including night‐time transpiration

The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical and ecological consequences of HR depend on the amount of redistributed water, whereas the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two ecotypes of sunflower (Helianthus annuus L.) in split‐pot experiments, we examined how well the widely used HR modelling formulation developed by Ryel et al. matched experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive night‐time transpiration, and although over the last decade it has become more widely recognized that night‐time transpiration occurs in multiple species and many ecosystems, the original Ryel et al. formulation does not include the effect of night‐time transpiration on HR. We developed and added a representation of night‐time transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and night‐time stomatal behaviour changed, both influencing HR.     

Morphological and ecological differences in two electrophoretically detected species of Cliona (Porifera, Demospongiae)

The taxonomie status of different morphotypes generally ascribed to the species of boring sponge Cliona viridis is examined. Morphometric, ecological and genetic differences between two morphotypes living sympatrically on rocky shores of the Ligurian Sea are considered. Morphotype 1 is characterized by small, well separated papillae (α stage), exclusively boring into the crust of coralline algae on the exposed rocky bottoms of the upper sublittoral zone. Morphotype 2 shows bigger papillae, often connected by portions of encrusting tissue ( β stage), and is predominantly found boring into organogenic concretions in slightly lighted habitats. Measurements of tylostyles indicate that morphotype 1 has spicules significantly smaller than morphotype 2. Electrophoretic analysis shows that the two morphotypes are fixed for different alleles at all four loci scored, indicating absence of gene flow between the two populations, i.e. they appear to be distinct biological species.     

The spatial pattern of air seeding thresholds in mature sugar maple trees

Air seeding threshold (P_a) of xylem vessels from current year growth rings were measured along the vertical axis of mature sugar maple trees (Acer saccharum Marsh.), with sampling points in primary leaf veins, petioles, 1-, 3-, and 7-year-old branches, large branches, the trunk and roots. The air seeding threshold was taken as the pressure required to force nitrogen gas through intervessel pit membranes. Although all measurements were made on wood produced in the same year, P_a varied between different regions of A. saccharum, with distal organs such as leaves and petioles having lower P_a than basal regions. Mean (SE) P_a ranged from 1.0 (± 0.1) MPa in primary leaf veins to 4.8 (± 0.1) MPa in the main trunk. Roots exhibited a P_a of 2.8 (± 0.2) MPa, lower than all other regions of the tree except leaf veins and petioles. Mean xylem vessel diameter increased basipetally, with the widest vessels occurring in the trunk and roots. Within the shoot, wider vessels had greater air seeding thresholds, contrasting with trends previously reported. However, further experimentation revealed that differences in P_a between regions of the stem were driven by the presence of primary xylem conduits, rather than differences in vessel diameter. In 1-year-old branches, P_a was significantly lower in primary xylem vessels than in adjacent secondary xylem vessels. This explained the lower values of P_a measured in petioles and leaf veins, which possessed a greater ratio of primary xylem to secondary xylem than other regions. The difference in P_a between primary and secondary xylem was attributed to the greater area of primary cell wall (pit membrane) exposed in primary xylem conduits with helical or annular thickening.