The initial peopling of the Americas: a growing number of founding mitochondrial genomes from Beringia.

Pan-American mitochondrial DNA (mtDNA) haplogroup C1 has been recently subdivided into three branches, two of which (C1b and C1c) are characterized by ages and geographical distributions that are indicative of an early arrival from Beringia with Paleo-Indians. In contrast, the estimated ages of C1d--the third subset of C1--looked too young to fit the above scenario. To define the origin of this enigmatic C1 branch, we completely sequenced 63 C1d mitochondrial genomes from a wide range of geographically diverse, mixed, and indigenous American populations. The revised phylogeny not only brings the age of C1d within the range of that of its two sister clades, but reveals that there were two C1d founder genomes for Paleo-Indians. Thus, the recognized maternal founding lineages of Native Americans are at least 15, indicating that the overall number of Beringian or Asian founder mitochondrial genomes will probably increase extensively when all Native American haplogroups reach the same level of phylogenetic and genomic resolution as obtained here for C1d.

Mitochondrial haplogroup U5b3: a distant echo of the epipaleolithic in Italy and the legacy of the early Sardinians.

There are extensive data indicating that some glacial refuge zones of southern Europe (Franco-Cantabria, Balkans, and Ukraine) were major genetic sources for the human recolonization of the continent at the beginning of the Holocene. Intriguingly, there is no genetic evidence that the refuge area located in the Italian Peninsula contributed to this process. Here we show, through phylogeographic analyses of mitochondrial DNA (mtDNA) variation performed at the highest level of molecular resolution (52 entire mitochondrial genomes), that the most likely homeland for U5b3-a haplogroup present at a very low frequency across Europe-was the Italian Peninsula. In contrast to mtDNA haplogroups that expanded from other refugia, the Holocene expansion of haplogroup U5b3 toward the North was restricted by the Alps and occurred only along the Mediterranean coasts, mainly toward nearby Provence (southern France). From there, approximately 7,000-9,000 years ago, a subclade of this haplogroup moved to Sardinia, possibly as a result of the obsidian trade that linked the two regions, leaving a distinctive signature in the modern people of the island. This scenario strikingly matches the age, distribution, and postulated geographic source of a Sardinian Y chromosome haplogroup (I2a2-M26), a paradigmatic case in the European context of a founder event marking both female and male lineages.

In planta expression of a mature Der p 1 allergen isolated from an Italian strain of Dermatophagoides pteronyssinus.

European (Dermatophagoides pteronyssinus) and American (Dermatophagoides farinae) house dust mite species are considered the most common causes of asthma and allergic symptoms worldwide. Der p 1 protein, one of the main allergens of D. pteronyssinus, is found in high concentration in mites faecal pellets, which can became easily airborne and, when inhaled, can cause perennial rhinitis and bronchial asthma. Here we report the isolation of the Der p 1 gene from an Italian strain of D. pteronyssinus and the PVX-mediated expression of its mature form (I-rDer p 1) in Nicotiana benthamiana plants. Human sera from characterized allergic patients were used for IgE binding inhibition assays to test the immunological reactivity of I-rDer p 1 produced in N. benthamiana plants. The binding properties of in planta produced I-rDer p 1 versus the IgE of patients sera were comparable to those obtained on Der p 1 preparation immobilized on a microarray. In this paper we provide a proof of concept for the production of an immunologically active form of Der p 1 using a plant viral vector. These results pave the way for the development of diagnostic allergy tests based on in planta produced allergens.

Low molecular weight phosphotyrosine protein phosphatase from PC12 cells. Purification, some properties and expression during neurogenesis in vitro and in vivo.

The purification and partial characterization of low molecular weight phosphotyrosine phosphatase (LMW-PTP) was reported for the first time in PC12 cells. In addition, the expression levels during neuronal phenotype induction by nerve growth factor (NGF) and during neurogenesis in chick embryos were investigated. LMW-PTP was purified to homogeneity and showed a single band of about 18 kDa with sodium dodecyl sulfate polyacrylamide gel electrophoresis. A native molecular mass of 20.1 kDa was determined by gel filtration on Sephadex G-75 column. The LMW-PTP from PC12 cells displays structural and biochemical characteristics similar to the enzyme isolated for normal tissues. It was specifically immunoprecipitated by an affinity purified antibody directed against the bovine liver enzyme. The enzyme is present in the cytosolic and cytoskeletal cell compartment where is tyrosine phosphorylated. Time course expression of LMW-PTP in PC12 cells was investigated after NGF treatment and showed an increase of about 30% in the basal level of LMW-PTP from 0 to 72 h. These changes were related to the appearance in PC12 cells of neuronal processes and to a decrease in cell proliferation. An increase of the LMW-PTP expression was also observed in vivo during chick embryo neurogenesis from 8-day-old embryos to adult chicks. The protein level, assayed by immunoblotting, increases from 14-day-old embryos to the hatched chicks reaching the adult levels within the first week after birth. These data indicate that the neurogenesis process is accompanied by a physiological increment of LMW-PTP expression in vitro and in vivo.

Molecular and phenotypic evidence of a new species of genus Esox (Esocidae, Esociformes, Actinopterygii): the southern pike, Esox flaviae.

We address the taxonomic position of the southern European individuals of pike, performing a series of tests and comparisons from morphology, DNA taxonomy and population genetics parameters, in order to support the hypothesis that two species of pike, and not only one, exist in Europe. A strong relationship emerged between a northern genotype supported by COI, Cytb, AFLP and specific fragments, and a phenotype with round spot skin colour pattern and a large number of scales in the lateral line, clearly separated from a southern genotype with other skin colour pattern and a low number of scales in the lateral line. DNA taxonomy, based on a coalescent approach (GMYC) from phylogenetic reconstructions on COI and Cytb together with AFLP admixture analysis, supported the existence of two independently evolving entities. Such differences are not simply due to geographic distances, as northern European samples are more similar to Canadian and Chinese samples than the southern Europe ones. Thus, given that the differences between the two groups of European pike are significant at the phenotypic, genotypic and geographical levels, we propose the identification of two pike species: the already known northern pike (Esox lucius) and the southern pike (E. flaviae n.sp.). The correct identification of these two lineages as independent species should give rise to a ban on the introduction of northern pikes in southern Europe for recreational fishing, due to potential problems of hybridisation.

Muscle actin isoforms are differentially expressed in human satellite cells isolated from donors of different ages.

Myogenesis is mainly sustained by a subpopulation of myogenic cells known as satellite cells (SC). In this paper we studied alpha-smooth muscle (alphaSMA) and alpha-sarcomeric muscle (alphaSRA) actin isoform expression in cultures of human satellite cells (HSC) isolated from skeletal muscle biopsies from a 5-day-old newborn, a 34-year-old young adult and a 71-year-old donor. Myogenicity of cultures was assessed using immunocytochemical detection of desmin and myosin heavy chain. Time-course expression of alphaSRA and alphaSMA were studied with both immunocytochemistry and western blotting procedures. Although alphaSMA was never detected in whole skeletal muscle, both alphaSMA and alphaSRA were detected in proliferating and differentiating HSC derived from donors of all examined ages. The expression level experiments showed that alphaSRA was gradually up-regulated during HSC differentiation, but no significant differences were observed between newborn, young, and elderly HSC cultures. Our data demonstrated that HSC, isolated from subjects of different ages, re-expressed alphaSMA, but its levels and expression pattern varied considerably in the newborn with respect to the young adult and elderly donors. These results are discussed in relation to the myogenic differentiation capability of HSC during human muscle senescence.