Electroporation, an alternative to biolistics for transfection of Bombyx mori embryos and larval tissues

There are few powerful techniques available to transfect insect tissues. We previously used biolistics to transfect Bombyx mori embryos, and larval and pupal tissues (Thomas J-L et al. 2001. Journal of Insect Science 1/9, Kravariti L et al. 2001. Insect Biochemistry and Molecular Biology 31: 473–479). As the main limitation was the irregularity in results we explored electroporation as an alternative technique by adapting techniques used for chicken embryos to B. mori embryos. By injecting the DNA solution into the hemocoel of late embryos that were finishing organogenesis, we expressed marker genes in numerous tissues following electroporation. With some adaptation of the method this was also achieved for early embryos lacking a hemocoel. Some larval tissues were also transfected. During these technical studies we found that optimizing parameters such as electrical voltage, number of pulses and their frequency, and conductivity of the buffer was important. These results confirmed that electroporation is a reliable technique for transfecting B. mori Abbreviation: / GFP: Green Fluorescent Protein CCD: Charged Coupled Devic

Trace elements in stream bed sediments from agricultural catchments (Gascogne region, S-W France): Where do they come from?

The Gascogne region (SW of France) is cultivated for more than 75% of the area. 83 samples of stream bed sediments were collected in three main Gascogne river basins (Gers, Save and Touch, left tributaries of the Garonne river) to evaluate the impact of agricultural practices on trace elements behavior. Eight potential harmful elements (PHE) (Cr, Co, Ni, Cu, Zn, As, Cd and Pb), four reference elements for normalization (Sc, Cs, Al and Fe) and four major elements (Mn, Ca, Mg and P) were considered. The average trace element concentrations in the fine fractions (b63 μm) are in the decreasing order: ZnNCrNNiNPbNCuNCoNAsNScNCsNCd. Geochemical investigations and an original approach combining regression analysis and chemical sequential extraction allowed to select the most adequate reference material (regional molasse)and reference element (Cs) for normalization procedure. The enrichment factor (EF) is generally lower than 2.5, particularly for Cr, Ni, Cu, As, Zn; however, 23% of the sampling stations are more contaminated (2.5bEFb4.5), particularly for Cd, Pb and Co. The PHE in the Gascogne river sediments are mainly originated from natural weathering processes; nevertheless, anthropogenic contribution could represent up to 34% of the total sediment content. For lead, geochemical and isotopic methods gave very similar anthropogenic contributions (24% and 22%, respectively). The enrichment of Cu, Pb, Zn, Co, As, Ni, Cr was mainly related to global and local atmospheric deposition of industrial emissions and gasoline combustion, and was associated to forested catchments. All PHE's are controlled by clay and oxi-hydroxides minerals. Cdwas the only PHE enriched downstreamcultivated catchments and this enrichmentwas linked to Ca and P. This indicates a major origin of Cd fromfertilizer inputs and a main control by carbonate mineral

Quantum Transitions Through Cosmological Singularities

In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.Comment: 32 pages, 27 figure

Distribution and origin of lead in stream sediments from small agricultural catchments draining Miocene molassic deposits (SW France)

Total Pb concentrations and isotopic composition were determined in stream-bed sediments and bedrock from 29 small agricultural or forested catchments in the Gascogne area (SW France). The contribution of Pb from various natural and anthropogenic sources was investigated in this rural area which is very weakly impacted by industrial or urban emissions. Environmental parameters in catchments (importance of forest cover, organic matter and oxide content in sediments) were considered. A combination of geochemical (enrichment calculation, sequential extraction) and isotopic investigations was performed to constrain the origin of Pb and the distribution of anthropogenic Pb in sediments. Most of the sediments have low total Pb content compared to other agricultural regions more impacted by industrial or urban emissions. The results indicated a moderate but significant Pb enrichment, particularly for catchments draining forested areas. This enrichment was positively related to organic C content in sediment and catchment forest cover, whereas in entirely cultivated catchments it was related to Fe-oxide content. An average anthropogenic end-member was determined using Pb isotopes, and was supposed to be representative of background atmospheric Pb pollution, with a weak influence of Pb from recent gasoline and local fertiliser spreading. The amount of anthropogenic Pb (Pbanthr) in sediments estimated using a geochemical approach (mean 63.7 ± 20.4%) was higher than that estimated using an isotopic approach (mean 36.6 ± 17.8%), but the same trend was observed among the samples, except for low anthropogenic contributions. The distribution of Pbanthr in sediments from weakly forested catchments indicated a strong affinity for carbonates and Fe-oxides. Amorphous Fe-oxides became preferential trapping compounds as soon as Pb enrichment increased and carbonate content decreased. Finally, in cultivated catchments, organic C was not a main trapping component for Pbanthr in sediments

Assessing the Impact of Sequence Length Learning on Classification Tasks for Transformer Encoder Models

Classification algorithms using Transformer architectures can be affected by the sequence length learning problem whenever observations from different classes have a different length distribution. This problem causes models to use sequence length as a predictive feature instead of relying on important textual information. Although most public datasets are not affected by this problem, privately owned corpora for fields such as medicine and insurance may carry this data bias. The exploitation of this sequence length feature poses challenges throughout the value chain as these machine learning models can be used in critical applications. In this paper, we empirically expose this problem and present approaches to minimize its impacts

Statistical Modeling of Epistasis and Linkage Decay using Logic Regression

Logic regression has been recognized as a tool that can identify and model non-additive genetic interactions using Boolean logic groups. Logic regression, TASSEL-GLM and SAS-GLM were compared for analytical precision using a previously characterized model system to identify the best genetic model explaining epistatic interaction of vernalization-sensitivity in barley. A genetic model containing two molecular markers identified in vernalization response in barley was selected using logic regression while both TASSEL-GLM and SAS-GLM included spurious associations in their models. The results also suggest the logic regression can be used to identify dominant/recessive relationships between epistatic alleles through its use of conjugate
operators