Application of biotechnology in snake reproductionpor

O crescente número de espécies de serpentes ameaçadas de extinção, estudos sobre suas toxinas, entre outros motivos, tornam a reprodução em cativeiro desses animais muito importante. Todavia, a ausência de cópulas ou problemas com a concepção são questões que dificultam a reprodução em cativeiro. A reprodução assistida em serpentes pode ser uma importante ferramenta para modificar essa realidade. Sêmen foi obtido pela primeira vez em serpentes pela compressão do terço final do corpo do animal, no entanto é comum a contaminação das amostras por fezes e urato. Em geral, os relatos da coleta de sêmen consistem na realização de massagens digitais ventrais no terço final do animal e posterior coleta utilizando-se uma seringa na região da cloaca. Poucas publicações contemplam a avaliação, o resfriamento ou a congelação de sêmen em serpentes. Meios de cultura de células como M199 e Ham’s F 10, diluidores como Test-gema, à base de leite ou água de coco, são alguns dos exemplos citados na literatura, porém seu uso ainda apresenta limitações e grande variabilidade nos resultados. Até o momento, não existe um protocolo eficiente para a congelação do sêmen em serpentes. A inseminação artificial utilizando sêmen fresco ou resfriado está descrita em poucas espécies de serpentes, com poucos resultados satisfatórios. Assim, a biotecnologia na reprodução de serpentes, apesar de ainda ser pouco utilizada, pode ser uma ferramenta muito importante para conservação dessas espécies em cativeiro.The increasing number of endangered snake species and the need of research to better combat their venom, among other reasons, emphasize how important is their reproduction in captivity. Unfortunately, mating or conception problems have restricted the reproduction of snakes in captivity and assisted reproduction could be an important tool to change this scenario. Snake’s semen was first collected stroking the final third of animal’s body at the cloaca region, but contamination with feces and urates were often reported. Semen is usually collected from the cloaca using a small syringe, after digital ventral massages along final third of snake’s body. Very few publications describe techniques for evaluation, cooling or freezing semen of snakes. Extenders for snake semen are cell culture media as M199 and Ham’s F 10 or extenders using Test-yolk, milk or coconut water, however their efficiency are restricted and inconsistent. So far, there is no protocol for cryopreservation of snake semen. The use of artificial insemination is reported for few species either with fresh or cooled semen, however, results are questionable. Although assisted reproduction biotechnologies in snakes are still limited, their use could be an important tool for the conservation of these species in captivity

Simultaneous expression of UV and violet SWS1 opsins expands the visual palette in a group of freshwater snakes

Snakes are known to express a rod visual opsin and two cone opsins, only (SWS1, LWS), a reduced palette resulting from their supposedly fossorial origins. Dipsadid snakes in the genus Helicops are highly visual predators that successfully invaded freshwater habitats from ancestral terrestrial-only habitats. Here we report the first case of multiple SWS1 visual pigments in a vertebrate, simultaneously expressed in different photoreceptors and conferring both UV and violet sensitivity to Helicops snakes. Molecular analysis and in vitro expression confirmed the presence of two functional SWS1 opsins, likely the result of recent gene duplication. Evolutionary analyses indicate that each sws1 variant has undergone different evolutionary paths, with strong purifying selection acting on the UV-sensitive copy and dN/dS ∼1 on the violet-sensitive copy. Site-directed mutagenesis points to the functional role of a single amino acid substitution, Phe86Val, in the large spectral shift between UV and violet opsins. In addition, higher densities of photoreceptors and SWS1 cones in the ventral retina suggest improved acuity in the upper visual field possibly correlated with visually-guided behaviors. The expanded visual opsin repertoire and specialized retinal architecture are likely to improve photon uptake in underwater and terrestrial environments, and provide the neural substrate for a gain in chromatic discrimination, potentially conferring unique color vision in the UV-violet range. Our findings highlight the innovative solutions undertaken by a highly specialized lineage to tackle the challenges imposed by the invasion of novel photic environments and the extraordinary diversity of evolutionary trajectories taken by visual opsin-based perception in vertebrates

Localising the gamma-ray emission in Flat Spectrum Radio Quasars and an extragalactic population study for the Cherenkov Telescope Array

This thesis is concerned with localising the gamma-ray emission region in Flat Spectrum Radio Quasars (FSRQs) and assessing the extragalactic source populations that will be detectable with the Cherenkov Telescope Array (CTA). An analysis of the gamma-ray flux from the nine brightest FSRQs detected with the Fermi-Large Area Telescope (LAT) during its first 8 years of operation is undertaken. Three different methods are employed to constrain the location of the emission region during identified flare periods, namely, measuring the shortest variability timescales, searching for evidence of a cut-off in the spectra and investigating the energy dependence in cooling timescales. Monte Carlo simulations are then implemented to constrain the very high energy (VHE) photon emission from the sample during the entire observation period. The combined findings of all the approaches suggest that the gamma-ray emission in the brightest FSRQs originates in multiple compact emission regions throughout the jet, within both the broad-line region and the molecular torus. The remainder of this thesis describes a detailed investigation of the extragalactic AGN sources that will be detectable with the CTA when in operation. The spectra from a sample of 1551 Fermi-LAT detected AGN having a known redshift measurement are extrapolated to the energy range 30 GeV - 200 TeV and the detection significance for each source is obtained using the anticipated instrument response of the CTA. The results reveal that the CTA will detect over 300 sources in 20 hours of observation and a list of promising candidates from each AGN class is presented. The improved statistics will allow a range of scientific topics to be explored including obtaining a reliable estimate of the luminosity function in the VHE regime for the first time. A preliminary evaluation of the evolutionary parameters using the expected CTA blazar source count distributions is discussed in this thesis

Coupling functions:universal insights into dynamical interaction mechanisms

The dynamical systems found in Nature are rarely isolated. Instead they interact and influence each other. The coupling functions that connect them contain detailed information about the functional mechanisms underlying the interactions and prescribe the physical rule specifying how an interaction occurs. Here, we aim to present a coherent and comprehensive review encompassing the rapid progress made recently in the analysis, understanding and applications of coupling functions. The basic concepts and characteristics of coupling functions are presented through demonstrative examples of different domains, revealing the mechanisms and emphasizing their multivariate nature. The theory of coupling functions is discussed through gradually increasing complexity from strong and weak interactions to globally-coupled systems and networks. A variety of methods that have been developed for the detection and reconstruction of coupling functions from measured data is described. These methods are based on different statistical techniques for dynamical inference. Stemming from physics, such methods are being applied in diverse areas of science and technology, including chemistry, biology, physiology, neuroscience, social sciences, mechanics and secure communications. This breadth of application illustrates the universality of coupling functions for studying the interaction mechanisms of coupled dynamical systems

Sustainability in Geotechnics: The Use of Environmentally Friendly Materials

Implementing environmentally friendly and cost-effective solutions is a pressing need to fulfill the United Nations Sustainable Development Goals (SDGs) set to be achieved by 2030. Thus, the requirement to execute the design, construction and maintenance of civil engineering structures and infrastructures as sustainably as possible are big challenges currently faced by civil and geotechnical engineers. This book, compiling the papers published during the 2020–2021 biennium in the Topical Collection, “Sustainability in Geotechnics: The Use of Environmentally Friendly Materials”, is intended help tackle those challenges. Several topics are covered by the 23 papers published herein, including: sustainable ground improvement techniques; replacement of raw materials such as soils and aggregates by recycled materials; soil reinforcement with alternative materials; sustainable solutions using geosynthetics; low-carbon solutions for stabilization of contaminated soils; and bioengineering techniques to prevent soil erosion. The Guest Editor expects that this book can be very useful towards the achievement of more environmentally friendly solutions, in particular in the field of geotechnical engineering