European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.     

Changes in fatty acids contents and growth characteristics in transformed oilseed rape (Brassica napus)

Spring oilseed rapeBrassica napus L. ssp.oleifera cv. HM-81 was transformed with T_L-DNA of the Ri plasmid of the agropine strainAgrobacterium rhizogenes 15834. Selfed progenies (R₂ and R₃ generations) were studied for changes in values of growth characteristics and fatty acids contents. Transformants are ‘homozygous’ for T_L-DNA. Both generations of transformants differed significantly from the nontransformed control plants in reduced length, lower number of pods per plant, lower total mass of seeds and the higher number of branches. The contents of palmitic, linoleic and linolenic acids were significantly higher in transformants when compared with the control. On the contrary, the contents of both stearic and oleic acids were in most of transformants significantly lower. Only traces of erucic acid (less than 0.05 % ) were found, both in transformed and nontransformed plants.     

Diversity and ecology of algae from the Nahal Qishon river,northern Israel

In 59 samples of periphyton and phytoplankton collected in 2002 - 2003 from the Nahal Qishon (Qishon River), northern Israel, we found 178 species from seven divisions of algae and cyanoprocaryotes. Diatoms, clorophytes, and cyanoprocaryotes prevail. Nitzschia and Navicula (Bacillariophyta) are the most abundant. Most of the species are cosmopolitan or widespread, except Lagynion janei (Chrysophyta), which is endemic for the Mediterranean Realm. About 17% of species (26) are new for Israel and five of them represent the first recorded genera: Crinalium endophyticum Crow, Actinocyclus normanii (Gregory) Hustedt, Rhizoclonium hieroglyphicum (Agardh) Kütz (Chlorophyta), Lagynion janei Bourelly, and Stylococcus aureus Chodat. Most of them come from a rare riverine assemblage with red alga Audouinella pygmea, as well as from the estuarine assemblage. Alkaliphiles predominate among the indicators of acidity, with few acidophiles confined to the communities under the impact of industrial wastes. Among the indicators of salinity, most numerous are the oligohalobien-indifferents and species adapted to a moderate salinity level. The relative species richness of ecological groups and the indices of saprobity are correlated with changes in conductivity, pH, and N-nitrate concentration. Indicators of organic pollution fall in the range of betameso- to alfamesosaprobic self-purification grades. Our studies show ecological significance of the Nahal Qishon as a model for a strongly disturbed aquatic ecosystem in the coastal zone of eastern Mediterranean.     

Taphonomy and compositional fidelity of Quaternary fossil assemblages of terrestrial gastropods from carbonate-rich environments of the Canary Islands

Quaternary aeolian deposits of the Canary Islands contain well‐preserved terrestrial gastropods, providing a suitable setting for assessing the taphonomy and compositional fidelity of their fossil record over ~13 kyr. Nine beds (12, 513 shells) have been analysed in terms of multivariate taphonomic and palaeoecological variables, taxonomic composition, and the stratigraphic and palaeontological context. Shells are affected by carbonate coatings, colour loss and fragmentation. Shell preservation is size‐specific: juveniles are less fragmented and show colour preservation more commonly than adults. In palaeosols, the adult shell density correlates negatively with the proportion of fragmented adults, negatively with the proportion of juveniles, and positively with the proportion of adults with coatings. High bioturbation intensity in palaeosols is associated with low shell fragmentation and high proportion of shells with coatings. These relationships imply that high adult density in palaeosols was driven by an increase in shell production rate (related to a decrease in predation rates on adults and a decrease in juvenile mortality) and a decrease in shell destruction rate (related to an increase in durability enhanced by carbonate precipitation). In dunes, the relationships between taphonomic alteration, shell density and bioturbation are insignificant. However, dune assemblages are characterized by a lower frequency of shells with coatings and higher rates of colour loss, indicating lower shell durability in dunes than in palaeosols. Additionally, non‐random differences in the coating proportion among palaeosols imply substantial temporal variation in the rate of carbonate crust formation, reflecting long‐term changes in bioturbation intensity that covaries positively with shell preservation. Dunes and palaeosols do not differ in species abundances despite differences in the degree of shell alteration, suggesting that both weakly and strongly altered assemblages offer data with a high compositional fidelity. Carbonate‐rich terrestrial deposits originating in arid conditions can enhance the preservation of gastropods and result in fossil assemblages that are suitable for palaeoecological and palaeoenvironmental studies of terrestrial ecosystems.     

N-end rule specificity within the ubiquitin/proteasome pathway is not an affinity effect

The N-end rule relates the amino terminus to the rate of degradation through the ubiquitin/26 S proteasome pathway. Proteins bearing basic (type 1) or large hydrophobic (type 2) amino termini are assumed to be targeted through this pathway by their higher affinity for binding to the responsible E3 ligase compared with proteins bearing other residues (type 3). Paradoxically, a significant fraction of eukaryotic protein degradation occurs through the N-end rule pathway, although the majority of cellular proteins are type 3 substrates. We have exploited specific interactions between ubiquitin carrier proteins (E2/Ubc) and their cognate E3 ligases to purify for the first time the mammalian N-end rule ligase E3alpha/Ubr1 to near homogeneity. In vitro studies show that E3alpha forms lysine 48-linked polyubiquitin degradation signals on type 1-3 substrates and is absolutely dependent on Ubc2/Rad6 orthologs. Biochemically defined kinetic studies show that the basis of N-end rule specificity is a k(cat) rather than the K(m) effect originally proposed, since all three substrate classes show similar binding affinities (K(m) approximately 5 microm) but V(max) values that are 100- and 50-fold greater for type 1 and 2 versus type 3 model substrates, respectively. In addition, the N-end rule dipeptides lysylalanine and phenylalanylalanine are general noncompetitive inhibitors for E3alpha-catalyzed ubiquitination of type 1-3 substrates rather than type-specific competitive inhibitors as predicted. These observations are consistent with a model in which the N-end rule effect reflects substrate binding-induced transitions in E3alpha to a catalytically competent conformer, the equilibrium for which depends on the identity of the amino terminus or the presence of basic or hydrophobic surface features. The model reconciles conflicts between specific predictions and empirical observations relating N-end rule targeting in addition to explicating the efficacy of selected dipeptides as potent in vivo inhibitors of this pathway.     

Applications of nanoparticles in biology and medicine

Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. Their unique size-dependent properties make these materials superior and indispensable in many areas of human activity. This brief review tries to summarise the most recent developments in the field of applied nanomaterials, in particular their application in biology and medicine, and discusses their commercialisation prospects.     

Protein interactions within the N-end rule ubiquitin ligation pathway

Rate studies have been employed as a reporter function to probe protein-protein interactions within a biochemically defined reconstituted N-end rule ubiquitin ligation pathway. The concentration dependence for E1-catalyzed HsUbc2b/E2(14kb) transthiolation is hyperbolic and yields K(m) values of 102 +/- 13 nm and 123 +/- 19 nm for high affinity binding to rabbit and human E1/Uba1 orthologs. Competitive inhibition by the inactive substrate and product analogs HsUbc2bC88A (K(i) = 104 +/- 15 nm) and HsUbc2bC88S-ubiquitin oxyester (K(i) = 169 +/- 17 nm), respectively, indicates that the ubiquitin moiety contributes little to E1 binding. Under conditions of rate-limiting E3alpha-catalyzed conjugation to human alpha-lactalbumin, HsUbc2b-ubiquitin thiolester exhibits a K(i) of 54 +/- 18 nm and is competitively inhibited by the substrate analog HsUbc2bC88S-ubiquitin oxyester (K(i) = 66 +/- 29 nm). In contrast, the ligase product analog HsUbc2bC88A exhibits a K(i) of 440 +/- 55 nm with respect to the wild type HsUbc2b-ubiquitin thiolester, demonstrating that ubiquitin binding contributes to the ability of E3alpha to discriminate between substrate and product E2. A survey of E1 and E2 isoform distribution in selected cell lines demonstrates that Ubc2 isoforms are the predominant intracellular ubiquitin carrier protein. Intracellular levels of E1 and Ubc2 are micromolar and approximately equal based on in vitro quantitation by stoichiometric (125)I-ubiquitin thiolester formation. Comparison of intracellular E1 and Ubc2 pools with the corresponding ubiquitin pools reveals that most of the free ubiquitin in cells is present as thiolesters to the components of the conjugation pathways. The present data represent the first comprehensive analysis of protein interactions within a ubiquitin ligation pathway.