Nucleotide sequence and characterization of a maize cytoplasmic ribosomal protein S11 cDNA

We isolated a Zea mays cDNA encoding the 40S subunit cytoplasmic ribosomal protein S11. The nucleotide sequence was determined and the derived amino acid sequence compared to the corresponding Arabidopsis thaliana protein showing an homology of 90%. This ribosomal protein is encoded by a small multigene family of at least two members. The mRNA steady-state level is about one order of magnitude higher in rapidly growing parts of the plant such as the roots and shoots of seedlings compared to fully expanded leaf tissue.     

Evidences for genetic differentiation within the highly endemic and endangered annual fish Austrolebias nigrofasciatus (Cyprinodontiformes: Rivulidae)

Samples of Austrolebias nigrofasciatus (n = 103), an endangered species of annual fish endemic to a small area of the Patos-Mirim lagoon system encompassing the São Gonçalo Channel lowlands, were collected from eight isolated temporary ponds, four located at the known distribution range of the species and four located along the Piratini River lowlands, where morphologically different individuals were found. In the laboratory, fragments of the mitochondrial cytochrome c oxidase I (coI), cytochrome b (cytb) and nuclear rhodopsin (rho) genes were amplified, purified and sequenced for 100, 99 and 58 of these individuals, respectively. Samples were further analysed using phylogenetic and phylogeographic methods to evaluate the patterns of genetic diversity and differentiation presented within and between populations, while assessing their evolutionary history, in order to guide the application of further conservation strategies. We found that the four new populations from the Piratini River lowlands encompass a different lineage of A. nigrofasciatus that diverged from that encountered in the São Gonçalo Channel at approximately 0.165 M years before present, during a population expansion and did not yet attain reciprocal monophyly. This divergence was associated with a glacial event that was preceded by an interglacial period putatively associated with the dispersal. Moreover, significant levels of genetic differentiation and a high number of exclusive haplotypes could be encountered even in micro-geographical scales, as in the comparisons between populations located within the same major lineage, indicating each of them may encompass independent management units. Conservation actions are certainly urgent, especially in the face of signs of a recent bottleneck.     

The role of duplication in the expression of a variable surface glycoprotein gene of Trypanosoma brucei

The variable surface glycoprotein (VSG) genes of Trypanosoma brucei have been classified into two groups depending upon whether or not duplication of the genes is observed when they are expressed. We report here the observation of duplication apparently linked to expression of the ILTaT 1.3 gene in the ETaR 1 trypanosome stock. In the ILTaR 1 stock, expression of the ILTaT 1.3 VSG did not involve a new duplication, but instead activation of a preexisting gene copy that had been apparently generated earlier by a duplication event analogous to that directly observed in the ETaR 1 trypanosomes. The results suggest that the well-characterised gene duplications found with other VSG genes are common to all VSG genes but are not directly responsible for controlling expression. All currently available data can be accommodated by a model that assumes that gene duplication and replacement occurs independently of antigenic switching.     

Purification and characterization of α-glucosidases produced by Saccharomyces in response to three distinct maltose genes

α-Glucosidases or maltases (EC 3.2.1.20) were purified to electrophoretic homogeneity from a respective strain of Sacchromyces cerevisiae which carries a single MAL gene, either MALα, MALβ or MALγ, using gluconate-Sepharose affinity chromography and isoelectrofocusing. Of these maltases, two types of maltase were obtained from the MALγ strain, the pI values of which were 5.6 and 5.9. From the MALα and MALβ strain was obtained only one type of maltase with the pI at 5.6 which was identical to one of the maltases from the MALγ strain. These four maltases possessed the same properties, except for pI. They were monomers with molecular weights of between 66 000 and 67 000. With regard to the substrate specificity, they hydrolyzed maltose and sucrose exclusively but not α-methulglucoside nor maltooligosaccharide. They did not differ in immunological properties.     

Domestication of the Emblematic White Cheese-Making Fungus Penicillium camemberti and Its Diversification into Two Varieties

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