Demographic history of Canary Islands male gene-pool: replacement of native lineages by European

Background  

The origin and prevalence of the prehispanic settlers of the Canary Islands has attracted great multidisciplinary interest. However, direct ancient DNA genetic studies on indigenous and historical 17^th–18^th century remains, using mitochondrial DNA as a female marker, have only recently been possible. In the present work, the analysis of Y-chromosome polymorphisms in the same samples, has shed light on the way the European colonization affected male and female Canary Island indigenous genetic pools, from the conquest to present-day times.     

ITS1 intra-individual variability of Ascaris isolates from Brazil

The zoonotic potential of Ascaris infecting pigs has stimulated studies of molecular epidemiology with internal transcribed spacer 1 (ITS1) as the target. The aim of this study was to determine the value of Ascaris ITS1 as a molecular marker through assessing the intra-individual genetic diversity of Ascaris isolates from two geographical areas of Brazil. DNA was extracted from single isolated eggs, ITS1 PCR was performed, and the PCR products were cloned and sequenced. Clone analysis showed high ITS1 intra-individual variability revealed by 2–4 ITS1 genotypes/haplotypes per sample (egg). Two genotypes, G1 and G6, and 13 new haplotypes were detected and characterized. The most prevalent in humans, G1 and/or the Brazilian G6, were detected in all samples. Except for genotype G1, no relationship was observed between Brazilian ITS1 genotypes/haplotypes and those previously described in China, Bangladesh, Japan, United Kingdom, Australia, and Denmark, with respect to geographic origin or host affiliation. However, an association between the two geographically separated Brazilian ITS1 isolates was observed. The ITS1 intra-individual variability revealed in this study indicated that the use of this genetic region to discriminate human and pig Ascaris genotypes should be reconsidered.     

Release of Juniperus thurifera woodlands from herbivore‐mediated arrested succession in Spain

Question: Do abiotic constraints maintain monospecific woodlands of Juniperus thurifera? What is the role of biotic (livestock) versus abiotic (climate) drivers in the recruitment and growth of the different tree species? Location: Cabrejas range, Soria, north‐central Spain, 1200 m altitude. Methods: Stand history was reconstructed using dendro‐ecology and spatial pattern analysis, combined with historical data of livestock abundances and climatic records. Results: J. thurifera establishment occurred in two distinct pulses, with a tree component establishing in the late 1800s to early 1900s. Quercus ilex and Pinus sylvestris establishment was evident only from the late 1970s onward. Recruitment events were related to reductions in livestock browsing. J. thurifera spatial structure was clumped and Q. ilex showed a short‐scale aggregation to J. thurifera trees and saplings. Radial growth trends of J. thurifera saplings, Q. ilex and P. sylvestris were negatively related to livestock density. Summer drought limited the radial growth of all the study species, and P. sylvestris and Q. ilex grew faster than J. thurifera even after considering an age effect. Conclusions: The differences in radial growth patterns and recruitment pulses between species indicate that livestock browsing and not abiotic factors is the main factor controlling plant succession and structural development. In this process, J. thurifera acts as a nurse plant, facilitating the establishment of other tree species. Under the current low pressure from herbivores, formerly pure J. thurifera woodlands will change towards dense stands of mixed species composition.     

Meiotic chromosomes and nucleolar behavior in testicular cells of the grassland spittlebugs Deois flavopicta, Mahanarva fimbriolata and Notozulia entreriana (Hemiptera, Auchenorrhyncha)

Spittlebugs annually infest pastures and cause severe damage, representing a serious problem for the tropical American beef cattle industry. Spittlebugs are an important biotic constraint to forage production and there is a lack of cytogenetic data for this group of insects. For these reasons, we conducted this work, in which the spermatogenesis and nucleolar behavior of Deois flavopicta, Mahanarva fimbriolata and Notozulia entreriana were studied. The males possessed testes in the shape of a "bunch of grapes"; a variable number of testicular lobes per individual and polyploid nuclei composed of several heteropycnotic bodies. A heteropycnotic area was located in the periphery of the nucleus (prophase I); the chiasmata were terminal or interstitial; metaphases I were circular or linear and anaphase showed late migration of the sex chromosome. The chromosome complement had 2n = 19, except for N. entreriana (2n = 15); the spermatids were round with heteropycnotic material in the center and elongated with conspicuos chromatin. The analysis of testes after silver nitrate staining showed polyploid nuclei with three large and three smaller nucleolar bodies. Early prophase cells had an intensely stained nucleolar body located close to the chromatin and another less evident body located away from the chromatin. The nucleolar bodies disintegrated during diplotene. Silver staining occurred in two autosomes, in terminal and subterminal locations, the latter probably corresponding to the nucleolus organizer regions (NORs). The spermatids were round with a round nucleolar body and silver staining was observed in the medial and posterior region of the elongated part of the spermatid head.     

Morphometry characterisation of European eel spermatozoa with computer-assisted spermatozoa analysis and scanning electron microscopy

The aim of the present study was to characterise European eel spermatozoa morphometrically, as a basis for future studies on the morphological effects of methods for sperm cryopreservation and sperm quality. This characterisation was carried out measuring several spermatozoa morphology parameters (head length, width, area and perimeter) by scanning electron microscopy (SEM), in comparison with measurements developed in European eel spermatozoa with computer-assisted morphology analysis (ASMA). Spermatozoa head morphology showed differences in width (1.15+/-0.01 microm versus 1.12+/-0.01 microm), perimeter (14.68+/-0.13 microm versus 13.72+/-0.19 microm) and area (5.36+/-0.06 microm2 versus 1.12+/-0.01 microm2) for ASMA and SEM, respectively. When head length was evaluated, significant differences were found, being higher for SEM methodology (5.09+/-0.04 microm versus 4.29+/-0.03 microm). The curved and elongated spermatozoa head in eels means a problem for the ASMA system (Sperm Class Analyser), Morfo Version 1.1, Imagesp, Barcelona, Spain), causing an error in the length measurements. However, similar results were obtained by both techniques when spermatozoa head length was considered as the greater length between two points within the object (4.29+/-0.03 microm versus 4.31+/-0.04 microm for ASMA and SEM, respectively). In conclusion, this is one of the first applications of ASMA in fish and the first in this species, and confirms this system as a useful tool with wide applications in future fish spermatozoa studies. Width, perimeter and area could be used as parameters for the spermatozoa morphology evaluation, whereas the length requires a new programming of the Imagesp software.     

Patterning the female side of Arabidopsis: the importance of hormones

The study of floral organ development has been a driving force in plant developmental biology research for the last two decades, and there is now an enormous wealth of information about the genetic networks underlying the specification of floral organ identity and the acquisition of its final morphology and function. These and parallel studies on leaf morphogenesis and development have made evident the common evolutionary origin of all plant lateral organs and the recurrent use of variations in the regulatory circuits involved in the shaping of leaves and flowers. This review summarizes the latest progress on the study of the development of the gynoecium, the female reproductive organ of the flower, stressing the connections with the developmental programme of leaf morphogenesis, and highlighting the common role of hormonal cues in these processes.     

Protein interactions within the Set1 complex and their roles in the regulation of histone 3 lysine 4 methylation

Set1 is the catalytic subunit and the central component of the evolutionarily conserved Set1 complex (Set1C) that methylates histone 3 lysine 4 (H3K4). Here we have determined protein/protein interactions within the complex and related the substructure to function. The loss of individual Set1C subunits differentially affects Set1 stability, complex integrity, global H3K4 methylation, and distribution of H3K4 methylation along active genes. The complex requires Set1, Swd1, and Swd3 for integrity, and Set1 amount is greatly reduced in the absence of the Swd1-Swd3 heterodimer. Bre2 and Sdc1 also form a heteromeric subunit, which requires the SET domain for interaction with the complex, and Sdc1 strongly interacts with itself. Inactivation of either Bre2 or Sdc1 has very similar effects. Neither is required for complex integrity, and their removal results in an increase of H3K4 mono- and dimethylation and a severe decrease of trimethylation at the 5' end of active coding regions but a decrease of H3K4 dimethylation at the 3' end of coding regions. Cells lacking Spp1 have a reduced amount of Set1 and retain a fraction of trimethylated H3K4, whereas cells lacking Shg1 show slightly elevated levels of both di- and trimethylation. Set1C associates with both serine 5- and serine 2-phosphorylated forms of polymerase II, indicating that the association persists to the 3' end of transcribed genes. Taken together, our results suggest that Set1C subunits stimulate Set1 catalytic activity all along active genes.     

Structural characterization of the 5' untranslated RNA of hepatitis C virus by vibrational spectroscopy

Raman and FTIR spectroscopy have been used to characterize the structure of 5'untranslated region (5'UTR, 342-mer RNA) of the HCV genome. The study of the 750-850 cm(-1) Raman spectral domain of the ribose-phosphate backbone reveals that the percentage of nucleobases involved in double helix-loop junctions is 19+/-1%, which is very close to that of a theoretical secondary structure model (18.7%) proposed on the basis of comparative sequence analysis and thermodynamic modelling. In addition, about 68+/-2% of the bases are helically ordered having C(3')-endo ribofuranose pucker. FTIR-monitored H/D exchange provides the following results: (a) base-paired guanine and cytosine nucleobases show the lowest rate of isotopic exchange, and some synchronous intensity changes of marker bands of A.U pair and single stranded adenine are consistent with the presence of A(*)A.U triplets; (b) the vibrational coupling between the ribose ether C-O stretching and 2'OH bending motions reveals that helical regions of 5'UTR RNA are characterized by hydrogen bonding between the 2'OH ribose groups and the ether oxygen atoms of neighbouring ribose residues.