Hydraulic flow characteristics in the lignotuberous mallee Eucalyptus behriana F. Muell. in the field

Abstract The lignotuberous mallee Eucalyptus behriana F. Muell, had much lower predawn leaf water potentials (not higher than – 1.2MPa) than other eucalypts (as high as – 0.2MPa), even after extended rain. This led to the expectation that the lignotuber of E. behriana might have specific hydraulic characteristics. Keeping the soil around partially defoliated mallces for several days underwater did not raise the water status above the maximum leaf water potential observed under natural conditions. Digging a plant out and placing its roots in water after removal of the soil rapidly increased the water status to a level consistant with other eucalypts. This indicated that the major impedance to water uptake was a component of the soil rather than in the roots or in the lignotuber. Some of the individual mallces had only two major stems or branches. One stem or branch was kept covered throughout the experiments to prevent transpiration. The other stem was subjected to a variety of different conditions in order to modify water loss from it. The transpiring branch affected the water status of the non-transpiring plant parts. Hydraulic resistances in the shoot and root/lignotuber were determined from differences in the leaf water potential of covered and uncovered branches, at high water flow rates through the plant. Resistances in branches, including the liquid phase component of the leaf, were significantly larger than in root or lignotuber. The total plant hydraulic resistance of E. behriana was similar to that of other eucalypts, such as E. pauciflora Sieb. ex Spreng. or E. delegatensis R. T. Bak., even though its growth form was different and its natural leaf water potentials were much lower. An osmotic adjustment at the leaf level was observed in the mallee, keeping its bulk leaf turgor in the same range as compared to the other eucalypt species.     

A survey of intraspecific predation within the class Mammalia

The occurrence of cannibalism in mammals was studied during a general review of cannibalism (Polis, 1981). In total, there were 146 references documenting intraspecific predation in 75 species of mammals distributed between seven orders. Of these references, 138 refer to cannibalism whereas eight studies refer to intraspecific killing unaccompanied by cannibalism. Of the papers that specified the identity of both the predator and the prey, approximately 80% referred to infanticide (including cannibalism). It appears that infanticide often functions as part of a reproductive strategy. Juveniles and adults are occasional intraspecific prey for some species of Insectivora, Chiroptera, Primates, Lagomorpha, Rodentia, Carnivora, and Artio-dactyla. Cannibalism was best documented for the carnivores, rodents and primates. In general, cannibalism often occurs during normal predatory activities and is a function of low food availability, environmental stress, and a high density of conspecifics.     

Pheromones and Courtship Behavior in Butterflies

The courtship of butterflies begins with a general attractionof males to moving objects. If the object of the attractionis a receptive female, her response wil1 elicit further courtshipbehavior from the male. Male courtship pheromones are disseminatedduring the aerial phases of courtship and after the female haslanded. While female butterflies generally lack specific courtshippheromone glands, females of some groups do possess these. Courtship pheromones of males of four members of the subfamilyDanainae in the family Nymphalidae have now been identified.Three of these share the same active component, but each hasspecific additional components. Although the courtship pheromonesecretions of butterflies have odors which are very distinctiveto humans, the active compound of these pheromones is odorlessto humans and elicits responses from antennal receptors of allbutterflies tested. The pheromone receptors are short thin-walledpegs on the antennae of both male and female butterflies.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.