Anna Maria Bolzern

Epigenetic inheritance systems in bdelloid rotifers. I. Maternal‐age‐related biochemical effects

Abstract The present study focuses on the changes of protein patterns that occur with age and on their maintenance across orthoclonal generations (i.e., lines that belong to the same clone and that differ with the age of their ancestors). About 500 individuals of the bdelloid rotifer Macrotrachela quadricornifera were cultivated and processed, and their protein phenotypes compared by a similarity test. The number of protein bands decreased with the age of the individuals. Young rotifers had the young protein pheno‐type when born from young mothers, and the old protein pattern when born from aged ones. The age of their grandmother was irrelevant. On the basis of these results, bdelloid rotifers seemed to transmit to the offspring their biochemical phenotype modified by age and the modified phenotype could persist over the two generations considered. Thus, a truly evolutionarily ancient partheno‐genetic taxon, such as Bdelloidea, apparently produces variable offspring by transmitting phenotypic variations i...

Egg volume, chick growth and survival across a carrion/hooded crow hybrid zone

Abstract The carrion and the hooded crow (Corpus corone corone and Corvus c. comix) are usually considered as morphs of a single species. They have parapatric distributions with narrow belts of overlap where fertile hybrids are produced. This three‐year study analyzed the variation of egg volume, and of chick growth and survival among allopatric parental populations and phenotypically parental and hybrid sub‐populations in a hybrid zone. Hybrid females laid eggs significantly smaller than those of parental females, living both in areas of sympatry and allppatry. No differences in chick growth were observed between pairs of different composition in the hybrid zone. Nestlings in the hybrid zone were significantly lighter than those in allopatric areas at all ages, and grew to a lower asymptotic weight. Tarsus grew faster and to a higher asymptote in the carrion crow area than in the hooded crow and in the hybrid areas. Chick survival was significantly influenced by female but not by male phenotype. Chicks i...

Temporal analysis of clonal structure in a moss bdelloid population

Clonal structure of a population of Macrotrachela quadricornifera (Rotifera, Bdelloidea) from a terrestrial moss in Northern Italy, was investigated over a 16 month period. Every month, 40–60 specimens of M. quadricornifera were collected from about 0.1 m2 of moss. The individual animals were homogenized and their isozyme phenotypes analyzed by electrophoresis on vertical polyacrylamide gel. One enzyme, phosphoglucose isomerase (PGI), was used as a marker to distinguish the different clones present in the sample. A few clones were established from the rotifers sampled and patterns of esterases α and β, and malic enzyme were studied. Nine electrophoretic patterns for PGI were seen. One was dominant, a second was almost always present, but in lesser amounts. The remainder were present occasionally.

The adhesive organs of Anura: A histological and molecular study

Abstract The cement gland is a secreting organ located at the anterior end of the larva of anuran Amphibia. It is a highly conserved structure even if it has different shapes in the different species. The morphology and the histology of the cement glands of seven species are analysed: Xenopus laevis, Discoglossus sardus, Bufo bufo, Bufo viridis, Rana esculenta, Rana latastei and Hyla intermedia. XCG and XAG are genes specifically expressed in the cement gland of Xenopus laevis and can be used as markers to identify cement gland territory. By Northern analysis and whole mount ’in situ’ hybridization, the expressions of these genes are tested in the studied species, the presence of homolog transcripts is detected in all the species, except Discoglossus sardus. Histological and molecular analysis show a substantial uniformity among the different types of adhesive organs. On the basis of the preliminary results obtained, some phylogenetic relations are inferred according to a recent phylogenetic tree based on molecular characters. The results seem to agree with the hypothesis that Pipi‐dae, to which Xenopus laevis belongs, are nearer to Neobatrachia than to Archeobatrachia.

Induction of Somites by Myosin mRNA

The effects of the messenger for myosin heavy chain (26S mRNA) on postnodal explants of chick embryo blastoderm were studied. Somites do not differentiate in the postnodal explants of chick embryo cultivated by News method. They are induced when postnodal pieces are cultivated in the presence of a 26S mRNA extracted from chick leg muscles or in the presence of myosin. 26S mRNA plus actinomycin D induces small somites. 26S mRNA of duck, rabbit, or trout induce somite structures often built up of cells separated by large spaces and joined around a large myocele. Crayfish 26S mRNA or chick myosin light chain induce columnar cells connected around a cavity. Liver or kidney mRNA do not induce. The induction process can be summarized as follows: 26S mRNA codes for myosin (heavy chain) and the myosin (heavy chain) induces the somites. Induction of somites by mRNA can occur in the presence of actinomycin D but not when there is mRNA plus puromycin. It does occur when myosin acts in the presence of puromycin. Myosin and its heavy chain are present in chick blastoderm before the appearance of somites. Induced somites are able to induce neural plates. We conclude that in normal development somites are induced by myosin.

The differentiation of free‐living amoebae of the genus Mayorella: a biochemical approach

Abstract Four populations of free‐living amoebae of the Mayorella genus, collected from different biotopes, have been studied. Three populations belonging to Mayorella spumosa species were collected from different Italian environments. The fourth population was collected in Uganda. Previously, morphological differences and different seasonal cycles caused the Ugandan population to be described as a new species: Mayorella lyncaea. A biochemical approach has been used to study the intraspecies variability of the three Italian populations from the plains, middle mountains and high mountains. The similarity index was evaluated by comparing isoenzymatic patterns. The monthly total protein analysis showed that the three populations have a different seasonal cycle than in the original biotope and that there is a greater similarity between Mayorella from the plains and middle mountains than between them and the high mountain population.