Alternative Transformation Methods Research Articles

A new method for identifying the role of marital preferences at shaping marriage patterns

AbstractWe develop a method which assumes that marital preferences are characterized either by the scalar-valued measure proposed by Liu and Lu, or by the matrix-valued generalized Liu–Lu measure. The new method transforms an observed contingency table into a counterfactual table while preserving its (generalized) Liu–Lu value. After exploring some analytical properties of the new method, we illustrate its application by decomposing changes in the prevalence of homogamy in the US between 1980 and 2010. We perform this decomposition with two alternative transformation methods as well where both methods capture preferences differently from Liu and Lu. Finally, we use survey evidence to support our claim that out of the three considered methods, the new transformation method is the most suitable for identifying the role of marital preferences at shaping marriage patterns. These data are also in favor of measuring assortativity in preferences à la Liu and Lu.

Electroporation-mediated genetic transformation of oil palm (Elaeis guineensis)

Abstract. Darmawan C, Wiendi NMA, Utomo C, Liwang T. 2020. Electroporation-mediated genetic transformation of oil palm (Elaeis guineensis). Biodiversitas 21: 3720-3726. Novel traits introduction to existing varieties may shorten the duration of oil palm genetic improvement. This approach heavily relies on efficient plant transformation and regeneration methods. Commonly used methods such as biolistic and Agrobacterium-mediated transformation still generated low efficiency for oil palm. Therefore, it is important to find alternative transformation methods that have the potency to give better results. Electroporation is usually used for delivering genes into bacteria or plant protoplast where cell wall does not exist, however, in this research, it was used to deliver plasmid into plant tissues. The aim of this research is to establish an optimum electroporation protocol for delivering genes into oil palm calli. Electric field strength of 250, 500, 750, 1,000, and 1,250 V/cm were applied for oil palm calli electroporation. Transient GUS assay was not applicable for initial detection presumably due to oil palm endogenous GUS-like protein activity after electroporation. Delivered gene could be detected in survived calli from all tested electric field strength treatments and the highest calli growth rates were observed from 250 V/cm electroporation treatment. Overall results showed that electroporation could be used to deliver specific genes into oil palm calli and might be developed further to increase its efficiency.

Comparing diel activity patterns of wildlife across latitudes and seasons: Time transformations using day length

Abstract Camera trapping allows scientists to study activity patterns of animals under natural conditions. However, comparisons of activity patterns across seasons or latitudes can be biased, because activity is often attuned to sunrise and sunset, the timing of which varies with latitude and season. Existing transformation methods to solve this problem have limitations. Here, we explore whether and how activity patterns can be transformed more accurately using two alternative ‘double anchoring’ transformations – equinoctial and average anchoring – that anchor activity time to two chosen anchor points during the study period. Using simulated noisy datasets mimicking species with either crepuscular, diurnal or cathemeral activity patterns, we compared the ability of different transformation methods to extract the latent pattern and activity levels under different study conditions. We found that average anchoring best retrieved the original diel activity pattern and yielded accurate estimates of activity level. Two alternative transformation methods – single anchoring and equinoctial anchoring – performed less well. Bias in estimates from using untransformed clock times was most marked (up to 2.5‐fold overestimation) for longer studies covering 4–5 months either side of an equinox at high latitude, and focusing on crepuscular species. We applied the average anchoring method to 9 months of data on Red deer Cervus elaphus, Wild boar Sus scrofa and Mouflon Ovis amon musimon activity as captured by camera traps in National Park Hoge Veluwe, the Netherlands. Average anchoring revealed more pronounced peaks of activity after sunset than was apparent from untransformed data in red deer and wild boar, but not for mouflon, a cathemeral species. Similarly, activity level was lower when calculated using average anchored time for red deer and wild boar, but no difference was observed for mouflon. We conclude that transformation of time might not be necessary at latitudes below 20°, or in studies with a duration of less than a month (below 40° latitude). For longer study periods and/or higher latitudes, average anchoring resolves the problem of variable day length. Code is provided. The transformation functions are incorporated in the r‐package ‘activity’.

Green fluorescent protein as a visual selection marker for oil palm transformation

The aim of the study was to regenerate transgenic oil palm expressing the gfp gene throughout the whole plant by transforming oil palm cultures with organelle-targeted and non-organelle targeted gfp genes. In this study, oil palm embryogenic calli and immature embryos were separately bombarded with different constructs carrying either organelle-targeted (mitochondria, plastid or endoplasmic reticulum) or non-organelle targeted gfp gene in combination with the herbicide Basta resistance (bar) gene for regenerating transgenic oil palm expressing gfp. Transformed embryogenic calli were successfully regenerated on media containing Basta but failed to express the gfp gene in the regenerated plants. On the other hand, the bombarded immature embryos were either directly germinated or regenerated into whole plantlets via callogenesis on medium containing Basta. The regenerated plantlets demonstrated gfp expression only as patches on some parts of the plants such as roots and leaves and not in the whole plant, contrary to what was expected. Even though the plantlets failed to show gfp gene expression in the whole plant, molecular analyses revealed the presence of bar and gfp transgenes in the transgenic plants. Based on results obtained from this study, it could be concluded that the failure was due to the inability of gfp gene to express in the regenerated transgenic plants. In order to overcome this failure, further interventions are proposed which include the use of stronger promoters, use of different gfp versions and finally to use alternative transformation methods.

Current conveyor based or unity gain cells based two integrator loop oscillators

Four alternative families of oscillators are considered in this paper, three of the families employ CCII or ICCII or combination of both and each family has sixteen oscillator circuit members. The fourth family uses unity gain cells and has four circuit members. Two alternative transformation methods are used in this paper for the generation of oscillators. The first one uses the adjoint circuit theorem to obtain a new family of current mode oscillators from a voltage mode oscillator circuit. The second transformation method uses the nodal admittance matrix (NAM) expansion to generate a grounded passive element oscillator family from an oscillator circuit, which employs a virtually grounded resistor. Although this paper has a tutorial nature it includes two new families of oscillators; one of them provides both current and voltage outputs and the other provides voltage outputs and is based on the use of voltage, current followers and inverters. Simulation results are included to support the analysis.

Efficient evaluation of Coulomb integrals: the nonlinearD- and -transformations

The two-electron multicentre Coulomb integrals constitute the rate-limiting step of ab initio and density functional theory (DFT) molecular structure calculations. Speed-up can be achieved by limiting the number of integrals to evaluate analytically but these analytical evaluations remain rate-limiting for large molecules. Here we apply the nonlinear D- and -transformations to evaluate Coulomb integrals over B-functions more rapidly than the alternative transformation methods to a given predetermined high accuracy.