Cloning and Molecular Analysis of the Plasma Membrane Ca2+ -ATPase Gene in Paramecium tetraurelia

ABSTRACT. We have determined the DNA sequence of the gene encoding the protein of the plasma membrane Ca²⁺-ATPase in Paramecium tetraurelia . The predicted amino acid sequence of the plasma membrane Ca²⁺-ATPase shows homology to conserved regions of known plasma membrane Ca²⁺-ATPases and contains the known binding sites for ATP (FITC), acylphosphate formation, and calmodulin, as well as the "hinge" region: all characteristics common to plasma membrane Ca²⁺-ATPases. The deduced molecular weight for this sequence is 131 kDa. The elucidation of this gene will assist in the studies of the mechanisms by which this excitable cell removes calcium entering through voltage gated calcium channels and the pump functions in chemosensory signal transduction.     

Female ornaments in the Pied Flycatcher Ficedula hypoleuca: associations with age, health and reproductive success

Female ornamentation has received little attention in studies of sexual selection. Traditionally, female ornaments have been explained as a genetically correlated response to selection in males. However, recent findings suggest that female ornaments may be adaptive. Southern populations of Pied Flycatchers Ficedula hypoleuca are suited for studies of female ornamentation because, in addition to the white wing patch, some females also express the white forehead patch characteristic of males. We thus addressed the associations of these two ornaments with female age and with some health and breeding parameters in a Spanish population of Pied Flycatchers. Female ornament expression was not associated with haemoparasite prevalences, clutch size or parental provisioning effort. However, females expressing the white forehead patch raised more fledglings, and females with larger wing patches bred earlier, had higher number of hatchlings and showed increased levels of total serum immunoglobulins. Thus, these two unrelated epigamic ornaments may indicate some aspects of female quality. Further experimental studies could test the possibility that these plumage traits might function as signals to the males or might be used during female–female aggressive encounters in competition for nest-sites and mates.     

Ultrastructural Characterisation and Molecular Taxonomic Identification of Nosema granulosis n. sp., a Transovarially Transmitted Feminising (TTF) Microsporidium

A novel microsporidian parasite is described, which infects the crustacean host Gammarus duebeni. The parasite was transovarially transmitted and feminised host offspring. The life cycle was monomorphic with three stages. Meronts were found in host embryos, juveniles, and in the gonadal tissue of adults. Sporoblasts and spores were restricted to the gonad. Sporogony was disporoblastic giving rise to paired sporoblasts, which then differentiated to form spores. Spores were not found in regular groupings and there was no interfacial envelope. Spores were approximately 3.78 x 1.22 microns and had a thin exospore wall, a short polar filament, and an unusual granular polaroplast. All life cycle stages were diplokaryotic. A region from the parasite small subunit ribosomal RNA gene was amplified and sequenced. Phylogenetic analysis based on these data places the parasite within the genus Nosema. We have named the species Nosema granulosis based on the structure of the polaroplast.     

Cuticular Proteins in Insects and Crustaceans

Comparisons between crustacean and insect cuticles are hamperedby the paucity of cuticular protein sequences for the former.Sufficient complete sequences are available for insect cuticularproteins to allow recognition of conserved motifs and relationshipsamong proteins that reflect the type of cuticle from which theyhave been extracted. All five sequences from an arachnid andtwo of 14 from crustaceans have a motif found in the largestgroup of insect cuticular proteins. Numerous insights have beengained from studying insect cuticular proteins and their genes.These insights have been summarized in hopes of encouraginginterest in building on the foundations laid by Dorothy Skinnerwith the exoskeleton of Gecarcinus.     

Life‐history consequences and disease resistance of western tent caterpillars in response to localised,herbivore‐induced changes in alder leaf quality

1. Plants can respond to herbivore damage with phenotypically plastic changes in quality that negatively affect herbivores and prevent subsequent attack – induced defences. 2. The present study tested whether trees respond to herbivory with localised induction, and whether life‐history traits and disease resistance of an insect herbivore are altered on induced branches of the trees. 3. The influences of localised, within‐branch, herbivore‐induced changes in red alder trees (Alnus rubra Bong.) on fitness characteristics of western tent caterpillars (Malacosoma californicum pluviale Dyar) were evaluated. In the field, randomly selected branches of trees were infested with tent caterpillar larvae and the adjacent branches were maintained as non‐infested controls. In the laboratory, larvae were fed leaves from either induced or non‐induced branches through to adult emergence. A second cohort of larvae was challenged with a viral pathogen to compare their disease susceptibility on induced versus non‐induced foliage. 4. Herbivore‐induced, localised responses of damaged branches reduced leaf quality for growth and the fecundity of female western tent caterpillars, but not that of males. Larvae fed induced leaves had a higher survival overall and a reduced mortality due to unidentified non‐viral pathogens than did their counterparts on non‐induced leaves. However, there was no influence of leaf quality on baculovirus‐induced mortality. 5. These findings suggest that localised induced changes in leaf quality could potentially influence populations of tent caterpillars in contradictory ways by reducing their growth rate and fecundity to a modest degree, while improving their survival and resistance to unidentified non‐viral pathogens to a larger extent.     

Chilling Sensitivity of Photosynthetic Oil-Seedlings: I COTTON SUNFLOWER

Despite the high probability that sensitive post-emergent seedlingswill be exposed to suboptimal temperatures which significantlyaffect subsequent development and yield, growers of long-season,indeterminate crops must rely upon empirically determined ‘earliestplanting dates’ Most ‘chilling-stress’ studieshave dealt, not with photosynthetic seedlings, but rather withthe effect of low, non-freezing temperatures (< 10 ?) upongerminating seeds and pre-emergent seedlings. A photosyntheticseedling growth system was used to monitor the effects of temperaturesfrom 10 to 35? upon the roots and aerial portions of chilling-sensitivecotton and relatively chilling-resistant sunflower oil-seedlings.Length measurements of cotton seedlings were too variable tobe reliable indicators of temperature treatment effects, butroot and shoot fresh weights could be used as non-destructivemeasurements of differences in root and shoot temperature responsesin both cotton and sunflower seedlings. The fresh weights wereindicative of the relative water status of seedling roots andshoots, including that of seedlings returned to 30? after exposureto other temperatures. Growth of both cotton and sunflower seedlingswas inhibited to some degree at non-optimal temperatures andthe capacities of the roots and shoots to return to normal waterstatus, as indicated by fresh weights and relative water contents,was correlated with sensitivity to suboptimal temperatures Key words: Cotton, sunflower, temperature, water status