Development of a pentaplex PCR assay for the simultaneous detection of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, L. helveticus, L. fermentum in whey starter for Grana Padano cheese

A pentaplex PCR assay for the rapid, selective and simultaneous detection of Lactobacillus helveticus, L. delbrueckii subsp. lactis, L. delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and L. fermentum, was developed. The target sequences were a group of genes coding for beta-galactosidase production (S. thermophilus and L. delbrueckii subsp. bulgaricus), for cell-enveloped associated proteinase synthesis (L. helveticus), for dipeptide transport system production (L. delbrueckii subsp. lactis) and for arginine-ornithine antiporter protein production (L. fermentum). The analytical specificity of the assay was evaluated with 5 reference strains and 140 lactic acid bacterial strains derived from raw milk cheeses and belonging to the Lactobacillus, Streptococcus, Lactococcus and Enterococcus genera. The identification limit for each target strain was 10³ CFU/ml. This new molecular assay was used to investigate the LAB population by direct extraction of DNA from the 12 whey cultures for Grana Padano. The pentaplex PCR assay revealed a good correspondence with microbiological analyses and allowed to identify even minor LAB community members which, can be out-competed in vitro by numerically more abundant microbial species.     

Properties of NiO sputtered thin films and modeling of their sensing mechanism under formaldehyde atmospheres

In this work the sensing mechanism of p-type semiconducting NiO thin films under the exposure to formaldehyde is explained. The influence of the sensing layer thickness and annealing treatment on the structural, optical and electrical properties of the samples is studied. The height of the potential barrier is estimated from temperature-stimulated conductance measurements. The potential barrier height is linked to oxygen ionosorption on the semiconductor surface. Furthermore, Fourier transform-IR analysis was carried out in order to determine the chemical reactions that govern the process of gas detection and the temperature range at which they occur. As a result of the study, it is possible to explain how the thickness and annealing treatment affect the sensing mechanism of the samples.     

Green Leaf Volatiles: A Plant’s Multifunctional Weapon against Herbivores and Pathogens

Plants cannot avoid being attacked by an almost infinite number of microorganisms and insects. Consequently, they arm themselves with molecular weapons against their attackers. Plant defense responses are the result of a complex signaling network, in which the hormones jasmonic acid (JA), salicylic acid (SA) and ethylene (ET) are the usual suspects under the magnifying glass when researchers investigate host-pest interactions. However, Green Leaf Volatiles (GLVs), C₆ molecules, which are very quickly produced and/or emitted upon herbivory or pathogen infection by almost every green plant, also play an important role in plant defenses. GLVs are semiochemicals used by insects to find their food or their conspecifics. They have also been reported to be fundamental in indirect defenses and to have a direct effect on pests, but these are not the only roles of GLVs. These volatiles, being probably one of the fastest weapons exploited, are also able to directly elicit or prime plant defense responses. Moreover, GLVs, via crosstalk with phytohormones, mostly JA, can influence the outcome of the plant’s defense response against pathogens. For all these reasons GLVs should be considered as co-protagonists in the play between plants and their attackers.     

Sequence determinants for hnRNP I protein nuclear localization

hnRNP I, also referred to as polypyrimidine tract binding protein, is one of the proteins associated with nascent pre-mRNA in the heterogeneous nuclear ribonucleoprotein (hnRNP) complexes. As for all karyophilic proteins, the nuclear import of hnRNP proteins requires specific sequence determinants that in many instances differ from the canonical import signal. In order to identify the sequences responsible for the nuclear localization, various hnRNP I portions were fused to a reporter protein (bacterial chloramphenicol acetyl transferase) and used in transient transfection assay. By this approach we identified a 60-amino-acid sequence located at the amino terminus of hnRNP I (designated NLD-I) that is both necessary and sufficient for nuclear localization. NLD-I represents a novel bipartite type of nuclear localization signal that bears no resemblance to other nuclear localization determinants so far identified in hnRNP proteins.     

Detection of human immunodeficiency virus type 1 (HIV-1) RNA in pools of sera negative for antibodies to HIV-1 and HIV-2

A total of 234 pools were prepared from 10,692 consecutive serum samples negative for antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 collected at five virological laboratories (average pool size, 45 serum samples). Pools were screened for the presence of HIV-1 RNA by a modified commercial assay (Amplicor HIV-1 Monitor test) which included an additional polyethylene glycol (PEG) precipitation step prior to purification of viral RNA (PEG Amplicor assay). The sensitivity of this assay for HIV-1 RNA detection in individual serum samples within pools matches that of standard commercial assays for individual serum samples, i.e., 500 HIV-1 RNA copies per ml. Five pools were identified as positive, and each one contained one antibody-negative, HIV-1 RNA-positive serum sample, corresponding to an average of 1 infected sample per 2,138 serum samples. Retrospective analysis revealed that the five HIV-1 RNA-positive specimens originated from individuals who had symptomatic primary HIV-1 infection at the time of sample collection and who were also positive for p24 antigenemia. We next assessed the possibility of performing the prepurification step by high-speed centrifugation (50,000 x g for 80 min) of 1.5-ml pools containing 25 microl of 60 individual serum samples, of which only 1 contained HIV-1 RNA (centrifugation Amplicor assay). The sensitivity of this assay also matches the sensitivities of standard commercial assays for HIV-1 RNA detection in individual serum samples. The results demonstrate that both assays with pooled sera can be applied to the screening of large numbers of serum samples in a time- and cost-efficient manner.     

Uncertainties in quantization-noise estimates for analog-to-digitalconverters

Estimates of quantization noise, obtained by stimulating an ideal analog-to-digital converter with a sine wave contained in the input range, are affected by an appreciable uncertainty, which may affect SNR and ENB specifications, especially in the case of low resolution devices. The uncertainty can be eliminated, when possible, by the use of an input sine wave bringing the converter into saturation. The different effects of additive noise on the noise estimates obtained by the various test procedures are also discussed, showing, in particular, that quantization noise may be overestimated by histogram testing with a nonsaturating input sine wave. Therefore, any noise specification should clearly make reference to the test signal parameters and to the instrumentation characteristics     

A Supramolecular Strategy to Leverage the Liquid‐Phase Exfoliation of Graphene in the Presence of Surfactants: Unraveling the Role of the Length of Fatty Acids

Achieving the full control over the production as well as processability of high‐quality graphene represents a major challenge with potential interest in the field of fabrication of multifunctional devices. The outstanding effort dedicated to tackle this challenge in the last decade revealed that certain organic molecules are capable of leveraging the exfoliation of graphite with different efficiencies. Here, a fundamental understanding on a straightforward supramolecular approach for producing homogenous dispersions of unfunctionalized and non‐oxidized graphene nanosheets in four different solvents is attained, namely N‐methyl‐2‐pyrrolidinone, N,N‐dimethylformamide, ortho‐dichlorobenzene, and 1,2,4‐trichlorobenzene. In particular, a comparative study on the liquid‐phase exfoliation of graphene in the presence of linear alkanes of different lengths terminated by a carboxylic‐acid head group is performed. These molecules act as graphene dispersion‐stabilizing agents during the exfoliation process. The efficiency of the exfoliation in terms of concentration of exfoliated graphene is found to be proportional to the length of the employed fatty acid. Importantly, a high percentage of single‐layer graphene flakes is revealed by high‐resolution transmission electron microscopy and Raman spectroscopy analyses. A simple yet effective thermodynamic model is developed to interpret the chain‐length dependence of the exfoliation yield. This approach relying on the synergistic effect of a ad‐hoc solvent and molecules to promote the exfoliation of graphene in liquid media represents a promising and modular strategy towards the rational design of improved dispersion‐stabilizing agents.     

TMABoost: an integrated system for comprehensive management of tissue microarray data.

In the last decade, high-throughput technologies such as DNA and tissue microarrays (TMAs) have become a means of large-scale investigation of gene expression, providing a plethora of new biomedical data in a relatively short time. Data collection and organization are critical aspects in this process to ensure the quality and reliability of future data interpretation. In this work, we propose a comprehensive approach to handle TMA data with the aim of supporting and promoting biomarker development. We describe a web-based system for the complete management of tissue microarray data in the field of pathology. The system has been in use since June, 2003. Our approach includes automatic localization and identification of tissue microarray samples, and quantitative image analysis that allows high-throughput screening of TMAs by ensuring nonsubjective measures and novel prognosis associations. In this paper, we present the architecture and the components of this system.     

Possible Role of –374T/A Polymorphism of RAGE Gene in Longevity

Demographic and social changes in the last decades have resulted in improvements in health and longevity. The survival of elderly people has improved significantly and thus centenarians are becoming the fastest growing population group. Environmental, genetic, and accidental factors have influenced the human life span. Researchers have gained substantial evidence that advanced glycation end products may play an important role in the processes of physiological aging. The aim of the present study was to investigate any differences in the frequencies of –374T/A polymorphism in subjects aged >90 years and in middle-aged individuals. We observed association between the A allele and genotype homozygous for this allele (AA) with a longer life expectancy in the male population. In particular, there was a prevalence of AA genotype and A allele in long-living subjects and a prevalence of the allele T in middle-aged subjects, indicating a possible protective role of the allele A to aging. In conclusion, our results support the hypothesis that longevity is the result of a good functioning of the immune system and a presumable hyper-expression of variants of anti-inflammatory genes of immunity. The differences in the genetic regulation of inflammatory processes may influence the presence of age-related disorders.