Changes in Cell Wall Polysaccharides During the Growth of Phaseolus vulgaris Leaves

The changes in pectic and hemicellulosic polysaccharides, and-cellulose during the expansion growth of the primary leavesof Phaseolus vulgaris L. var. Pinta have been studied. -Celluloseincreased continuously with age, while pectic and water-solublehemicellulose extracted with 4% KOH fractions slightly decreased.The water-soluble hemicelluloses extracted with 24% KOH showedthe most conspicuous changes, increasing until the 8th day,when the absolute growth rate was maximal, and thereafter decreasing.Furthermore, the study of the molecular mass distribution ofpectin, and water-soluble polysaccharides extracted with 4%and 24% KOH, showed an increase in the degree of polymerizationof polyuronic acid and xylan, and an important depolymerizationof galactan and xyloglucan. Accordingly, the mechanism of cellwall loosening in the leaf cell walls is similar to that describedfor plant axes. Key words: Cell wall, growth, leaf     

Ecomorphological study of large canids from the lower Pleistocene of southeastern Spain

An ecomorphological analysis of the skeletal remains of large canids, Canis (Xenocyon) falconeri and Canis etruscus (Mammalia, Carnivora, Canidae), preserved in an assemblage of large mammals from the lower Pleistocene site at Venta Micena (Guadix–Baza Basin, Orce, Granada, southeastern Spain) is reported. Mean body mass of adult individuals was estimated to be around 10 kg for C. etruscus and approximately 28 kg for C. falconeri using multiple regression. A comparative study of tooth measurements in modem canids, using principal components and discriminant function analysis, infers quite different ecomorphological adaptations and feeding behavior for both fossil species. The craniodental morphology of C. falconeri is similar to that shown by extant hypercarnivorous canids whose diet include more than 70% of vertebrate meat, whereas C. etruscus shows a cranial morphology similar to those of modem omnivorous species, thus indicating a dietary niche in which vertebrate meat represented less than 70% of its diet, with other feeding resources making up the balance. These results suggest that there was a marked ecological segregation between both sympatric species of large canids. The find of a complete skull of C. falconeri showing bilateral asymmetry and marked dental anomalies could suggest high levels of genetic homozygosis in the population which inhabited this region during early Pleistocene times, possibly as a consequence of isolation and the low number of individuals. This may have subsequently led to the extinction of C. falconeri in the Western fringe of Europe. The survival of this pathological individual to adulthood indicates that this species may have developed cooperative behavior similar to that of modem African wild dogs.     

EFFECT OF EXPOSURE TO THE AROMA OF A PRELOAD ON SUBSEQUENT INTAKE OF A FOOD WITH THE SAME AROMA

We tested the hypothesis that exposure to an aroma through a food or beverage in the first part of a meal (preload) would reduce the consumption of a food with the same aroma in the second portion of the meal, because of olfactory-specific satiety. In a first experiment, 35 young, normal-weight adults participated in 2 lunch sessions during which they consumed a fixed preload of either ranch-flavored or plain potato chips and sparkling water, followed by ad libitum consumption of a pasta salad with ranch dressing and sparkling water. In the second experiment, 33 subjects consumed a fixed preload of either lemon-flavored or plain sparkling water and pasta salad with ranch dressing, followed by ad libitum consumption of lemon-flavored yogurt and plain sparkling water. No difference was observed in the amount of food consumed (corrected for session order effects) as a function of prior exposure to ranch flavor in the chips or lemon flavor in the water. We conclude that exposure to a preload aroma may not have a significant effect on subsequent intake of a food with the same aroma.     

Geochemistry of Persististrombus latus Gmelin from the Pleistocene Iberian Mediterranean realm

De Torres, T., Ortiz, J.E., Arribas, I., Delgado, A., Julià, R. & Martín‐Rubí, J.A. 2009: Geochemistry of Persististrombus latus Gmelin from the Pleistocene Iberian Mediterranean realm. Lethaia, Vol. 43, pp. 149–163. In this paper the organic and inorganic geochemistry of fossil and extant Persististrombus latus are compared, together with other strombid species (Lentigo lentiginosus, Lobatus gigas, Strombus alatus, Lobatus raninus, Laevistrombus canarium and Tricornis latissimus). Using a large sample of well‐preserved fossil P. latus shells from the Mediterranean realm, we examined the warming period of sea water in the Middle Pleistocene. A mineralogical study of the shells demonstrates the continuous presence of calcite and a complex organic matter distribution, which was well preserved in many cases, thereby making the U/Th dating of strombid shells unreliable. U/Th analysis of coral samples and amino acid racemization dating of pelecypod shells confirmed that P. latus entered the Mediterranean realm in MIS 7 and 5. The oscillations of the δ¹⁸O values reflect annual growth periods and provide a mixing of the first signal record (primary growth) and successive overgrowths. □Amino acid racemization, Mediterranean Sea, Persististrombus latus, shell mineralogy, U/Th, δ¹⁸O.     

Reduced salinities compromise the thermal tolerance of hypersaline specialist diving beetles

Inland saline waters are globally threatened habitats that harbour unique assemblages of specialist invertebrates. In many Mediterranean regions, irrigation associated with intensive agriculture is lowering the salinity of these habitats, resulting in the loss of their specialist biota, although the mechanisms by which reductions in salinity lead to species loss are poorly understood. In the present study, the effects of reduced salinity on the temperature tolerance and thermal acclimatory abilities of two related species of hypersaline water beetles, Nebrioporus baeticus (Schaum) and Nebrioporus ceresyi (Aubé), are explored. Both upper (UTL) and lower thermal limits (LTL) are assessed, and both salinity and temperature are found to influence the thermal biology of Nebrioporus. Mean UTLs are greater in individuals of both species acclimated at high salinities, with salinity appearing to be more important than acclimation temperature in determining UTL. In both taxa, the lowest mean LTLs are recorded in individuals acclimated at the highest salinities and lowest temperatures; temperature‐dependent acclimation is only reported after exposure to relatively high salinities. The data show that salinity influences the thermal tolerance and acclimatory ability of these hypersaline beetles, and that lowered salinity compromises the ability of adult Nebrioporus to cope with both heat and cold. Such an effect may partly explain why specialist species are lost from hypersaline habitats subject to salinity reductions, and suggests that ongoing reduction in salinity may compromise the ability of such specialist taxa to cope with rapid climate change.     

Lethal and sublethal behavioural responses of saline water beetles to acute heat and osmotic stress

1. As species' physiological breadth determines their potential to deal with environmental changes, and influences individuals' survival and the persistence of populations, information about lethal and sublethal responses could be fundamental for conservation purposes. 2. We used a standard experimental approach to explore mortality and behavioural avoidance responses (i.e. flight and emersion from the water) to a combination of acute heat and osmotic stress on six species of saline water beetles (belonging to Enochrus, Nebrioporus, and Ochthebius genera). 3. Heat stress affected survival and behavioural responses in all of the species, whereas osmotic stress and the interaction between both stressors only showed significant effects for the Ochthebius genus. Behavioural and survival patterns were highly interrelated across the stress gradients. The Enochrus and Nebrioporus studied species showed maximum avoidance activity at 35–40 °C, and a short (< 30 min) exposure to 45 °C was lethal. Ochthebius species were the most heat tolerant and displayed increasing behavioural responses with increasing temperature. In the Nebrioporus and Ochthebius genera, the species occupying lotic, more environmentally stable habitats, showed greater mortality, and avoidance responses were higher or initiated at lower stress thresholds than lentic species. In contrast, both Enochrus species displayed a similar mortality, and the lentic species E. bicolor emerged and flew more than the lotic E. falcarius, in concordance with its higher dispersal capacity. 4. Avoidance responses could provide interesting information about species' physiological amplitudes as a complement to lethal responses. The lotic species here studied showed narrower physiological amplitude (i.e. N. baeticus and O. glaber) or lower dispersal ability (i.e. E. falcarius) than their lentic relatives; both traits could result in a higher vulnerability of lotic species to thermal habitat changes.