The impact of the aphids Tuberolachnus salignus and Pterocomma salicis on willow trees

The effect of two species of stem‐feeding aphid on the yield, phenology and water‐use of soil‐grown and hydroponic‐cultured willow were investigated. The effects of Pterocomma salicis were less marked than those of Tuberolachnus salignus. The latter reduced not only the above and below‐ground growth of trees made during and subsequent to infestation, but also altered the mass of previously developed woody tissue. The negative effects of T. salignus on the shoots and roots of established and establishing trees were drastic and were both quantitative and qualitative. They were also observed to reduce the survival of infested trees. P. salicis had negative effects on the growth of roots and shoots during infestation, but the influence of this species did not persist nor did it influence previous growth.     

The distribution of inorganic phosphate in amphibian muscle

The Na⁺, K⁺, and inorganic phosphate levels of the plasma and sartorius muscle of the toad Bufo marinus were determined. Soaking in normal Ringer brought about the usual cation shifts, but did not alter the level of inorganic phosphate in the cell. Increases in the external phosphate level brought about an increase in the internal phosphate, but the apparent phosphate space of muscle is somewhat smaller than the apparent Cl^- space. Phosphate spaces were compared with inulin spaces and were found to be significantly greater. Alteration of the H⁺ concentration of the high phosphate Ringer did not alter the partition of phosphate across the cell membrane. These results have been found to be consistent with the theory of a three compartment system for muscle, wherein the tissue is assumed to consist of an extracellular phase, and two intracellular phases. The inorganic phosphate of the cell is assumed to be adsorbed onto the "ordered phase," and increments in organic phosphate found on raising the external level are assumed to take place in the "free intracellular phase."     

Variations in the dorso-ventral organization of leaf structure and Kranz anatomy coordinate the control of photosynthesis and associated signalling at the whole leaf level in monocotyledonous species

Photosynthesis and associated signalling are influenced by the dorso-ventral properties of leaves. The degree of adaxial/abaxial symmetry in stomatal numbers, photosynthetic regulation with respect to light orientation and the total section areas of the bundle sheath (BS) cells and the surrounding mesophyll (M) cells on the adaxial and abaxial sides of the vascular bundles were compared in two C₄[ Zea mays (maize) and Paspalum dilatatum ] and one C₃[ Triticum turgidum (Durum wheat)] monocotyledonous species. The C₃ leaves had a higher degree of dorso-ventral symmetry than the C₄ leaves. Photosynthetic regulation was the same on each side of the wheat leaves, as were stomatal numbers and the section area of the BS relative to that of the M cells (BS/M section area ratio). In contrast, photosynthetic regulation in maize and P. dilatatum leaves showed a marked surface-specific response to light orientation. Compared to the adaxial sides of the C₄ monocotyledonous leaves, the abaxial surfaces had more stomata and the BS/M section area ratio was significantly higher. Differences in dorso-ventral structure, particularly in Kranz anatomy, serve not only to maximize photosynthetic capacity with respect light orientation in C₄ monocotyledonous leaves but also allow adaxial and abaxial-specific signalling from the respective M cells.     

THE FISH AND AMPHIBIAN SWIMMING TRACES UNDICHNA AND LUNICHNIUM, WITH EXAMPLES FROM THE LOWER PERMIAN OF NEW MEXICO, USA

Abstract: The ichnotaxonomy and stratigraphic, geographic and environmental distribution of fish (Undichna) and amphibian (Lunichnium) swimming traces are reviewed. The ichnospecies of Undichna consist of various combinations of sinusoidal waves of differing complexity. Some of the more complex ichnospecies are made up of elements of the simpler forms, and morphological subset relationships between them are presented. Such subset series represent potential taphoseries relationships (i.e. preservational variants that reflect, for example, undertrails), or series of minor behavioural variations. Such a system can be used to highlight that different ichnospecies occurring at a locality may be taphonomic or minor behavioural variants of each other. Caution should, therefore, be exercised before erecting new ichnospecies on the basis of limited material if its morphology is a subset of an existing ichnospecies. However, the naming of such simpler ichnospecies is valid if they represent a recurrent morphology, and it is valid to erect new ichnospecies whose morphology is not a subset of an existing ichnospecies. Specimens that demonstrate intergradation between ichnotaxa can be used to justify their synonomy. Ichnotaxonomic revisions reduce the number of ichnospecies in Undichna from 14 to nine. U. radnicensis, a highly variable ichnospecies, is synonymized with U. britannica on the basis of material from China that demonstrates they can intergrade. U. prava is a partial U. tricosta, which falls within the minimum diagnosis of U. simplicitas. U. gosiutensis is regarded as a subjective junior synonym of U. quina. U. westerbergensis, originally attributed to a ‘crossopterygian’ fish performing a tetrapod‐like gait, is reassigned as a distinct ichnospecies within Lunichnium because it demonstrates the same morphology, representing similar behaviour, albeit by a different producer. L. anceps and L. gracile are synonymized with L. rotterodium. New specimens of U. bina and L. rotterodium are also described from the Lower Permian Robledo Mountains Formation of southern New Mexico, USA.     

Drought stress differentially affects leaf-mining species

Abstract.  1. The impact of climate change on phytophages is difficult to predict, due in part to variation between species in their responses to factors such as drought stress. Here, the hypothesis that several species within the leaf-mining feeding guild will respond in a consistent way to changes in rainfall patterns is tested, using a manipulative field experiment.
2. Summer drought, enhanced summer rainfall, and control treatments were imposed on a calcareous grassland community, and the responses of five leaf-mining species were assessed.
3. One leaf-mining species was more abundant under enhanced rainfall, one was more abundant under drought, and the other three species showed no consistent response to the rainfall treatments. Higher parasitism levels under drought may partly explain the response of one species ( Stephensia brunnichella ) to the treatments.
4. These results show that generalisations relating to drought stress impacts cannot be drawn at the feeding guild level for leaf-mining insects.