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.     

Large-Scale Conformational Transitions and Dimerization Are Encoded in the Amino-Acid Sequences of Hsp70 Chaperones

Hsp70s are a class of ubiquitous and highly conserved molecular chaperones playing a central role in the regulation of proteostasis in the cell. Hsp70s assist a myriad of cellular processes by binding unfolded or misfolded substrates during a complex biochemical cycle involving large-scale structural rearrangements. Here we show that an analysis of coevolution at the residue level fully captures the characteristic large-scale conformational transitions of this protein family, and predicts an evolutionary conserved–and thus functional–homo-dimeric arrangement. Furthermore, we highlight that the features encoding the Hsp70 dimer are more conserved in bacterial than in eukaryotic sequences, suggesting that the known Hsp70/Hsp110 hetero-dimer is a eukaryotic specialization built on a pre-existing template.     

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.     

Molecules, Developmental Modules, and Phenotypes: A Combinatorial Approach to Homology

Most traditional views of homology rely on two unwarranted premises: the pervasively hierarchical nature of biology, inclusive of the levels of genes, development, and morphology and the linear mapping of genes onto developmental schedules and of developmental schedules onto phenotypes. These premises are only occasionally verified. Hierarchical behavior is negated by gene duplication and exon shuffling at the level of genes, by the coexistence of autonomous vs nonautonomous gene expression at the level of development, by ontogenetic repatterning at the level of morphology. The linearity of mapping of genes onto development is disturbed by genetic piracy, uncoupling of positional vs spatial control, and pleiotropy. The independence of developmental modules affects the mapping of development onto morphology and, finally, the peculiar topology of the epigenetic code affects the linearity of the gene to phenotype mapping. To cope with this complex behavior, a combinatorial approach to homology is recommended.