A new topology of the human Y chromosome haplogroup E1b1 (E-P2) revealed through the use of newly characterized binary polymorphisms

Haplogroup E1b1, defined by the marker P2, is the most represented human Y chromosome haplogroup in Africa. A phylogenetic tree showing the internal structure of this haplogroup was published in 2008. A high degree of internal diversity characterizes this haplogroup, as well as the presence of a set of chromosomes undefined on the basis of a derived character. Here we make an effort to update the phylogeny of this highly diverse haplogroup by including seven mutations which have been newly discovered by direct resequencing. We also try to incorporate five previously-described markers which were not, however, reported in the 2008 tree. Additionally, during the process of mapping, we found that two previously reported SNPs required a new position on the tree. There are three key changes compared to the 2008 phylogeny. Firstly, haplogroup E-M2 (former E1b1a) and haplogroup E-M329 (former E1b1c) are now united by the mutations V38 and V100, reducing the number of E1b1 basal branches to two. The new topology of the tree has important implications concerning the origin of haplogroup E1b1. Secondly, within E1b1b1 (E-M35), two haplogroups (E-V68 and E-V257) show similar phylogenetic and geographic structure, pointing to a genetic bridge between southern European and northern African Y chromosomes. Thirdly, most of the E1b1b1* (E-M35*) paragroup chromosomes are now marked by defining mutations, thus increasing the discriminative power of the haplogroup for use in human evolution and forensics.     

Molecular Dissection of the Basal Clades in the Human Y Chromosome Phylogenetic Tree

One hundred and forty-six previously detected mutations were more precisely positioned in the human Y chromosome phylogeny by the analysis of 51 representative Y chromosome haplogroups and the use of 59 mutations from literature. Twenty-two new mutations were also described and incorporated in the revised phylogeny. This analysis made it possible to identify new haplogroups and to resolve a deep trifurcation within haplogroup B2. Our data provide a highly resolved branching in the African-specific portion of the Y tree and support the hypothesis of an origin in the north-western quadrant of the African continent for the human MSY diversity.     

Karyology and distribution of Sesleria tenuifolia complex (Poaceae) in the Italian Peninsula

Karyological analyses of wild populations of Sesleria tenuifolia complex collected from throughout the Italian peninsula was performed to check the stability of the chromosome number along both geographical and ecological gradients. The chromosome counts showed that the Italian populations of the Sesleria tenuifolia complex consist of octoploid plants (2n=8x=56) and dodecaploid plants (2n=12x=84). The discovery of a dodecaploid chromosome number is the first for the genus Sesleria. The distribution of octoploid and dodecaploid populations follows strictly geographical boundaries and seems to be uninfluenced by synecological or physical factors. No overlapping between octoploid and dodecaploid populations was found; in fact, octoploid populations occupy northern, central and part of Peninsular Italy, whereas dodecaploid ones are restricted to the Pollino massif and the Orsomarso range, which together form the southernmost limit of the distribution area of the Sesleria tenuifolia complex.     

Chromosomal plasticity and evolutionary potential in the malaria vector <Emphasis Type="Italic">Anopheles gambiae</Emphasis> sensu stricto: insights from three decades of rare paracentric inversions

Background  

In the Anopheles gambiae complex, paracentric chromosomal inversions are non-randomly distributed along the complement: 18/31 (58%) of common polymorphic inversions are on chromosome arm 2R, which represents only ~30% of the complement. Moreover, in An. gambiae sensu stricto, 6/7 common polymorphic inversions occur on 2R. Most of these inversions are considered markers of ecological adaptation that increase the fitness of the carriers of alternative karyotypes in contrasting habitats. However, little is known about the evolutionary forces responsible for their origin and subsequent establishment in field populations.     

Structure and properties of the C-terminal domain of insulin-like growth factor-binding protein-1 isolated from human amniotic fluid

Insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) regulates the activity of the insulin-like growth factors in early pregnancy and is, thus, thought to play a key role at the fetal-maternal interface. The C-terminal domain of IGFBP-1 and three isoforms of the intact protein were isolated from human amniotic fluid, and sequencing of the four N-terminal polypeptide chains showed them to be highly pure. The addition of both intact IGFBP-1 and its C-terminal fragment to cultured fibroblasts has a similar stimulating effect on cell migration, and therefore, the domain has a biological activity on its own. The three-dimensional structure of the C-terminal domain was determined by x-ray crystallography to 1.8 Angstroms resolution. The fragment folds as a thyroglobulin type I domain and was found to bind the Fe(2+) ion in the crystals through the only histidine residue present in the polypeptide chain. Iron (II) decreases the binding of intact IGFBP-1 and the C-terminal domain to IGF-II, suggesting that the metal binding site is close to or part of the surface of interaction of the two molecules.     

Influenza della temperatura sullo sviluppo della “Dicranophora fulva„ Schröter

Abstract

Karyotype features and microsporogenesis of Tripogandra diuretica (Mart.) Handlos and Tripogandra glandulosa (Seub.) Rohw. from 15 NE Argentina accessions are analysed via classical cytogenetics, CMA/DA/DAPI and Ag-NOR. The karyotype of T. glandulosa (2n = 2x = 16; 2m + 6sm + 8st) is bimodal (A ₂ = 0.37; R = 2.65) and asymmetrical (A ₁ = 0.63; i = 26.06; r > 2 = 0.88) (3B-Stebbins) with a genome size of 33.28 μm; two pairs are satellited, CMA+ and NOR-actives. Another four CMA+ loci and DAPI+ universal centromeric heterochromatin occur. Microsporogenesis is normal (pollen viability short stamens = 97.8%; large = 96.7%), meiotic behaviour is regular and chromosomes pair as 8II. The karyotype of T. diuretica (2n = 8x = 64; 8m + 24sm + 32st) is bimodal (A ₂ = 0.27; R = 2.54) and asymmetrical (A ₁ = 0.60; i = 27.32; r > 2 = 0.88) (3B-Stebbins); additionally, two pairs are satellited. Microsporogenesis is normal (short stamens = 77.8%; large = 68.5%), except for micronuclei and low pollen viability in some accessions. Meiotic behaviour is regular with 32II, acting as a cytological diploid, however the arrangement of the haploid karyotype suggests that T. diuretica, which also exhibits a reduction of the genome size (18.58 μm), constitutes an auto-octoploid taxa. Additionally, both species share cytological features common to karyotype orthoselection.     

N2O fluxes of a bio‐energy poplar plantation during a two years rotation period

Nitrous oxide emissions are of critical importance for the assumed climate neutrality of bio‐energy. In this study we report on the N₂O fluxes from a bio‐energy poplar plantation measured with eddy covariance for 2 years, after conversion of agricultural fields to few months after harvesting of the plantation. A pulse peak of N₂O was detected after the land use change and in the wake of the first heavy rainfall. The N₂O‐N emission during just a single week was 2.7 kg N₂O‐N ha^?1 which represented approximately 42% of the total N₂O‐N emitted during the 2 years of measurements. After this peak emission, N₂O fluxes were constantly rather low, not increasing after rainfall events any longer. Lowest emissions (and even N₂O sink) occurred mostly during the end of the second growing season with maximum canopy development, and water table deeper than 80 cm. Gross primary production (GPP) explained 68% of the monthly averaged variability in N₂O emission from August to December 2011. Probably N uptake by vegetation during the peak of the second growing season limited N₂O emission, which in fact increased again after the plantation was coppiced. For the majority of the measuring period, N₂O fluxes did not present a well‐defined diurnal pattern, with the exception of two periods: (1) from 19–22 August 2010 and (2) from September–November 2011. In both cases wind speed played a major role in controlling the diurnal pattern in these fluxes (explaining up to 80% of the diurnal variability in N₂O fluxes on 19–22 August 2010), whereas at the end of the second growing season (September–November 2011), GPP explained 73% of the diurnal pattern in N₂O fluxes.     

A quantitative threshold for nest-mate recognition in a paper social wasp

Nest-mate recognition is fundamental for protecting social insect colonies from intrusion threats such as predators or social parasites. The aggression of resident females towards intruders is mediated by their cuticular semiochemicals. A positive relation between the amount of cues and responses has been widely assumed and often taken for granted, even though direct tests have not been carried out. This hypothesis has important consequences, since it is the basis for the chemical insignificance strategy, the most common explanation for the reduction in the amount of semiochemicals occurring in many social parasites. Here we used the social wasp Polistes dominulus, a model species in animal communication studies and host of three social parasites, to test this hypothesis. We discovered that different amounts of cuticular hydrocarbons (CHC) of a foreign female evoke quantitatively different behavioural reactions in the resident foundress. The relation between CHC quantity and the elicited response supports the idea that a threshold exists in the chemical recognition system of this species. The chemical insignificance hypothesis thus holds in a host–parasite system of Polistes wasps, even though other explanations should not be discarded.