Do Chimpanzees Use Weight to Select Hammer Tools?

The extent to which tool-using animals take into account relevant task parameters is poorly understood. Nut cracking is one of the most complex forms of tool use, the choice of an adequate hammer being a critical aspect in success. Several properties make a hammer suitable for nut cracking, with weight being a key factor in determining the impact of a strike; in general, the greater the weight the fewer strikes required. This study experimentally investigated whether chimpanzees are able to encode the relevance of weight as a property of hammers to crack open nuts. By presenting chimpanzees with three hammers that differed solely in weight, we assessed their ability to relate the weight of the different tools with their effectiveness and thus select the most effective one(s). Our results show that chimpanzees use weight alone in selecting tools to crack open nuts and that experience clearly affects the subjects' attentiveness to the tool properties that are relevant for the task at hand. Chimpanzees can encode the requirements that a nut-cracking tool should meet (in terms of weight) to be effective.     

Applying Microsatellite Multiplex PCR Analysis (MMPA) for Determining Allele Copy-Number Status and Percentage of Normal Cells within Tumors

The study of somatic genetic alterations in tumors contributes to the understanding and management of cancer. Genetic alterations, such us copy number or copy neutral changes, generate allelic imbalances (AIs) that can be determined using polymorphic markers. Here we report the development of a simple set of calculations for analyzing microsatellite multiplex PCR data from control-tumor pairs that allows us to obtain accurate information not only regarding the AI status of tumors, but also the percentage of tumor-infiltrating normal cells, the locus copy-number status and the mechanism involved in AI. We validated this new approach by re-analyzing a set of Neurofibromatosis type 1-associated dermal neurofibromas and comparing newly generated data with results obtained for the same tumors in a previous study using MLPA, Paralog Ratio Analysis and SNP-array techniques.Microsatellite multiplex PCR analysis (MMPA) should be particularly useful for analyzing specific regions of the genome containing tumor suppressor genes and also for determining the percentage of infiltrating normal cells within tumors allowing them to be sorted before they are analyzed by more expensive techniques.     

Physiological and antioxidant responses of <Emphasis Type="Italic">Erica multiflora</Emphasis> to drought and warming through different seasons

Climate change projections forecast a warming and an associated change in the distribution and intensity of rainfalls. In the case of the Mediterranean area, this will be reflected in more frequent and severe drought periods in the future. Within a long-term (9 years) manipulation experiment, we aimed to study the effect of the soil drought (15–20% decreased soil moisture) and warming conditions (+1°C warming) projected for the next decades onto photosynthetic rates and water relations, and onto the antioxidant and anti-stress defense capacity of Erica multiflora, a common species of the dry Mediterranean coastal scrublands, in two different seasons, spring and summer. Results indicated that none of the applied treatments was severe enough to induce a pronounced negative response of photosynthesis in this species well adapted to harsh Mediterranean conditions, but also highlighted important seasonal differences. Photosynthesis was limited by photoinhibition in spring and by stomatal closure in summer. Isoprenoid emission and the level of enzymatic and non-enzymatic antioxidants were lower in summer than in spring, whereas pigment and total phenolic contents were generally higher in summer. Volatile isoprenoid emissions were largely inhibited by drought and were not stimulated by warming. Drought and warming increased the oxidation state of ascorbate and reduced total glutathione levels in spring, but not in summer. It is concluded that E. multiflora plants can adapt to prolonged drought and warming, at least at the level simulated by our manipulative experiment, through changes in the seasonal physiological and antioxidant response of leaves.     

Precipitation manipulation experiments--challenges and recommendations for the future

Climatic changes, including altered precipitation regimes, will affect key ecosystem processes, such as plant productivity and biodiversity for many terrestrial ecosystems. Past and ongoing precipitation experiments have been conducted to quantify these potential changes. An analysis of these experiments indicates that they have provided important information on how water regulates ecosystem processes. However, they do not adequately represent global biomes nor forecasted precipitation scenarios and their potential contribution to advance our understanding of ecosystem responses to precipitation changes is therefore limited, as is their potential value for the development and testing of ecosystem models. This highlights the need for new precipitation experiments in biomes and ambient climatic conditions hitherto poorly studied applying relevant complex scenarios including changes in precipitation frequency and amplitude, seasonality, extremity and interactions with other global change drivers. A systematic and holistic approach to investigate how soil and plant community characteristics change with altered precipitation regimes and the consequent effects on ecosystem processes and functioning within these experiments will greatly increase their value to the climate change and ecosystem research communities. Experiments should specifically test how changes in precipitation leading to exceedance of biological thresholds affect ecosystem resilience and acclimation.     

Amplification, contraction and genomic spread of a satellite DNA family (E180) in Medicago (Fabaceae) and allied genera

Background and Aims

Satellite DNA is a genomic component present in virtually all eukaryotic organisms. The turnover of highly repetitive satellite DNA is an important element in genome organization and evolution in plants. Here we assess the presence and physical distribution of the repetitive DNA E180 family in Medicago and allied genera. Our goals were to gain insight into the karyotype evolution of Medicago using satellite DNA markers, and to evaluate the taxonomic and phylogenetic signal of a satellite DNA family in a genus hypothesized to have a complex evolutionary history.

Methods

Seventy accessions from Medicago, Trigonella, Melilotus and Trifolium were analysed by PCR to assess the presence of the repetitive E180 family, and fluorescence in situ hybridization (FISH) was used for physical mapping in somatic chromosomes.

Key Results

The E180 repeat unit was PCR-amplified in 37 of 40 taxa in Medicago, eight of 12 species of Trigonella, six of seven species of Melilotus and in two of 11 Trifolium species. Examination of the mitotic chromosomes revealed that only 13 Medicago and two Trigonella species showed FISH signals using the E180 probe. Stronger hybridization signals were observed in subtelomeric and interstitial loci than in the pericentromeric loci, suggesting this satellite family has a preferential genomic location. Not all 13 Medicago species that showed FISH localization of the E180 repeat were phylogenetically related. However, nine of these species belong to the phylogenetically derived clade including the M. sativa and M. arborea complexes.

Conclusions

The use of the E180 family as a phylogenetic marker in Medicago should be viewed with caution. Its amplification appears to have been produced through recurrent and independent evolutionary episodes in both annual and perennial Medicago species as well as in basal and derived clades.     

Fine mapping of 14q24.1 breast cancer susceptibility locus

In the National Cancer Institute Cancer Genetic Markers of Susceptibility (CGEMS) genome-wide association study of breast cancer, a single nucleotide polymorphism (SNP) marker, rs999737, in the 14q24.1 interval, was associated with breast cancer risk. In order to fine map this region, we imputed a 3.93?MB region flanking rs999737 for Stages 1 and 2 of the CGEMS study (5,692 cases, 5,576 controls) using the combined reference panels of the HapMap 3 and the 1000 Genomes Project. Single-marker association testing and variable-sized sliding-window haplotype analysis were performed, and for both analyses the initial tagging SNP rs999737 retained the strongest association with breast cancer risk. Investigation of contiguous regions did not reveal evidence for an additional independent signal. Therefore, we conclude that rs999737 is an optimal tag SNP for common variants in the 14q24.1 region and thus narrow the candidate variants that should be investigated in follow-up laboratory evaluation.     

GM2 gangliosidoses in Spain: Analysis of the HEXA and HEXB genes in 34 Tay-Sachs and 14 Sandhoff patients

Acid α-glucosidase (GAA) is a lysosomal enzyme that hydrolyzes glycogen to glucose. Deficiency of GAA causes Pompe disease. Mammalian GAA is synthesized as a precursor of ~ 110,000 Da that is N-glycosylated and targeted to the lysosome via the M6P receptors. In the lysosome, human GAA is sequentially processed by proteases to polypeptides of 76-, 19.4-, and 3.9-kDa that remain associated. Further cleavage between R²⁰⁰ and A²⁰⁴ inefficiently converts the 76-kDa polypeptide to the mature 70-kDa form with an additional 10.4-kDa polypeptide. GAA maturation increases its affinity for glycogen by 7-10 fold. In contrast to human GAA, processing of bovine and hamster GAA to the 70-kDa form is more rapid. A comparison of sequences surrounding the cleavage site revealed human GAA contains histidine at 201 while other species contain hydrophobic amino acids at position 201 in the otherwise conserved sequence. Recombinant human GAA (rhGAA) containing the H201L substitution was expressed in 293 T cells by transfection. Pulse chase experiments in 293 T cells expressing rhGAA with or without the H201L substitution revealed rapid processing of rhGAA^H201L but not rhGAA^WT to the 70-kDa form. Similarly, when GAA precursor was endocytosed by human Pompe fibroblasts rhGAA^H201L but not rhGAA^WT was rapidly converted to the 70-kDa mature GAA. These studies indicate that the amino acid at position 201 influences the rate of conversion of 76-kDa GAA to 70-kDa GAA. The GAA sequence rather than the lysosomal protease environment explains the predominance of the 76-kDa form in human tissues.