Direct sequencing and bidirectional allele specific polymerase chain reaction of the bovine beta-casein B variant.

We have used the polymerase chain reaction (PCR) to amplify exon VII of the bovine beta-casein gene. The mutations responsible for the B variant were identified by direct sequencing of the amplification products. A bidirectional allele-specific PCR method (BAS-PCR) has been developed using oligonucleotides overlapping the mutation site at their 3' ends. This new procedure allows a rapid and reliable discrimination between the B and non-B alleles of beta-casein.     

Retinol (Vitamin A) Increases α-Synuclein, β-Amyloid Peptide,Tau Phosphorylation and RAGE Content in Human SH-SY5Y Neuronal Cell Line

Retinoids (vitamin A and derivatives) are recognized as essential factors for central nervous system (CNS) development. Retinol (vitamin A) also was postulated to be a major antioxidant component of diet as it modulates reactive species (RS) production and oxidative stress in biological systems. Oxidative stress plays a major role either in pathogenesis or development of neurodegenerative diseases, or even in both. Here we investigate the role of retinol supplementation to human neuron-derived SH-SY5Y cells over RS production and biochemical markers associated to neurodegenerative diseases expressed at neuronal level in Parkinson’s disease and Alzheimer’s disease: α-synuclein, β-amyloid peptide, tau phosphorylation and RAGE. Retinol treatment (24 h) impaired cell viability and increased intracellular RS production at the highest concentrations (7 up to 20 µM). Antioxidant co-treatment (Trolox 100 µM) rescued cell viability and inhibited RS production. Furthermore, retinol (10 µM) increased the levels of α-synuclein, tau phosphorylation at Ser396, β-amyloid peptide and RAGE. Co-treatment with antioxidant Trolox inhibited the increased in RAGE, but not the effect of retinol on α-synuclein, tau phosphorylation and β-amyloid peptide accumulation. These data indicate that increased availability of retinol to neurons at levels above the cellular physiological concentrations may induce deleterious effects through diverse mechanisms, which include oxidative stress but also include RS-independent modulation of proteins associated to progression of neuronal cell death during the course of neurodegenerative diseases.     

Multilocus and morphological analysis of south-eastern Iberian Wall lizards (Squamata,Podarcis)

The phylogenetic relationships among the wall lizards of the Podarcis hispanicus complex that inhabit the south-east (SE) of the Iberian Peninsula and other lineages of the complex remain unclear. In this study, four mitochondrial and two nuclear markers were used to study genetic relationships within this complex. The phylogenetic analyses based on mtDNA gene trees constructed with ML and BI, and a species tree using *BEAST support three divergent clades in this region: the Valencia, Galera and Albacete/Murcia lineages. These three lineages were also corroborated in species delimitation analyses based on mtDNA using bPTP, mPTP, GMYC, ABGD and BAPS. Bayesian inference species delimitation method (BPP) based on both nuclear data and a combined data set (mtDNA + nuclear) showed high posterior probabilities for these three SE lineages (≥0.94) and another Bayesian analysis (STACEY) based on combined data set recovered the same three groups in this region. Divergence time dating of the species tree provided an estimated divergence of the Galera lineage from the other SE group (Podarcis vaucheri, (Albacete/Murcia, Valencia)) at 12.48 Ma. During this period, the Betic–Rifian arc was isolated, which could have caused the isolation of the Galera form distributed to the south of the Betic Corridor. Although lizards from the Albacete/Murcia and Galera lineage are morphologically similar, they clearly represent distinct genetic lineages. The noteworthy separation of the Galera lineage enables us to conclude that this lineage must be considered as a new full species.     

Cytogenetic divergence in two sympatric fish species of the genus Astyanax Baird and Girard, 1854 (Characiformes,Characidae) from northeastern Brazil

The fish genus Astyanax is widespread throughout the Neotropical region and is one of the most species-rich genera of the Characiformes. Cytogenetic studies of Astyanax have revealed marked intra- and interspecific diversity, with the identification of various species complexes. In this report, we describe the karyotypic structure of two sympatric species of Astyanax (Astyanax sp. and Astyanax aff. fasciatus) from the Middle Contas River basin in the northeastern Brazilian state of Bahia. Both species had 2n = 48 but differed in their karyotypic formulae. Small heterochromatic blocks and multiple nucleolar organizer regions (NORs) were identified in both species. Terminal CMA₃⁺/DAPI⁻ signals were observed in Astyanax sp. and A. aff. fasciatus, mostly coincident with NORs. These results show that chromosomal markers can be used to identify species in this fish complex. These markers can provide useful information for evolutionary studies and investigations on the mechanisms of chromosomal diversity in Astyanax.     

Structure and Evolution of the Mitochondrial DNA Complete Control Region in the Lizard Lacerta dugesii (Lacertidae, Sauria)

Abstract We sequenced the complete control region (CR) and adjacent tRNAs, partial 12S rRNA, and cytochrome b (over 3100 bp) from eight individuals of Madeiran wall lizards, Lacerta dugesii, from four distinct island populations. The tRNAs exhibit a high degree of intraspecific polymorphisms compared to other vertebrates. All CR sequences include a minisatellite that varies in length between populations but is apparently fixed within them. Variation in minisatellite length appears between populations separated by apparently very short evolutionary time spans. Many motifs identified in the CR of other vertebrates are not highly conserved, although conserved blocks are identifiable between the few published reptile CR sequences. Overall there are extensive differences in the internal organization of the reptile CR compared to the more widely studied mammals and birds. Variability in the CR is lower than in cytochrome b, but higher than in 12S rRNA. Phylogenetic analysis of these sequences produces a well-resolved estimate of relationships between populations.     

Role of atelomixis in replacement of phytoplankton assemblages in Dom Helvécio Lake, South-East Brazil

Scale and frequency of changes in a lake’s physical structure, light dynamics, and availability of nutrients are closely related to phytoplankton ecology. Since phytoplankton assemblages were first described, phytoplankton ecologists concluded that these assemblages provide insight into phytoplankton responses to environmental changes. Objectives of this study were to investigate ecology of phytoplankton during a complete hydrological cycle in the deepest natural lake in Brazil, Dom Helvécio, and to sort species into the list of assemblages, checking its accordance with environmental changes in a tropical system within the middle Rio Doce Lake district, South-East Brazil. Canonical Correspondence Analysis, t-test, Mann–Whitney U-test, and Kruskal–Wallis test were used to analyze climatological, environmental, and plankton data, which were obtained monthly in 2002. A new phytoplankton assemblage, N_A (atelomixis-dependent desmids), is suggested because atelomixis (robust movement of water occurring once a day) contributed to replacement of species in Dom Helvécio Lake. Stability of stratification, water chemistry, and composition of phytoplankton assemblages characterized two periods. The first period occurred in six rainy months (Jan–Mar and Oct–Dec) when the lake was stratified and phytoplankton was dominated by two assemblages: N_A and F. The second period occurred in six dry months (Apr–Sep) when the lake was nonstratified and phytoplankton was dominated by four assemblages: S2, X1, A, and L_O. Results suggest that phytoplankton in Dom Helvécio Lake was shaped by seasonal and daily changes of water temperature, even with its lower amplitude of variation within 2002 (El Niño year). These changes promoted water column stratification or mixing, reduced light, and increased nutrient availability. Temperature, therefore, is similarly important to phytoplankton ecology in tropical regions as it is in temperate ones. Sorting phytoplankton species into assemblages matched well with environmental changes and periods identified so it is also suggested that this can be further used as an appropriate tool to manage water quality when evaluating tropical lakes.