Organ printing: fiction or science

Aggregates of living cells (i.e. model tissue fragments) under appropriate conditions fuse like liquid drops. According to Steinberg's differential adhesion hypothesis (DAH), this may be understood by assuming that cells are motile and tissues made of such cells possess an effective surface tension. Here we show that based on these properties three-dimensional cellular structures of prescribed shape can be constructed by a novel method: cell aggregate printing. Spherical aggregates of similar size made of cells with known adhesive properties were prepared. Aggregates were embedded into biocompatible gels. When the cellular and gel properties, as well as the symmetry of the initial configuration were appropriately adjusted the contiguous aggregates fused into ring-like organ structures. To elucidate the driving force and optimal conditions for this pattern formation, Monte Carlo simulations based on a DAH motivated model were performed. The simulations reproduced the experimentally observed cellular arrangements and revealed that the control parameter of pattern evolution is the gel-tissue interfacial tension, an experimentally accessible parameter.     

Off with your heads: isolated organs in early Soviet science and fiction

In the summer of 1925, a debutant writer, Aleksandr Beliaev, published a ‘scientific-fantastic story’, which depicted the travails of a severed human head living in a laboratory, supported by special machinery. Just a few months later, a young medical researcher, Sergei Briukhonenko, succeeded in reviving the severed head of a dog, using a special apparatus he had devised to keep the head alive. This paper examines the relationship between the literary and the scientific experiments with severed heads in post-revolutionary Russia, which reflected the anxieties about death, revival, and survival in the aftermath of the 1914–1923 ‘reign of death’ in that country. It contrasts the anguished ethical questions raised by the story with the public fascination for ‘science that conquers death’.     

A unique role for citizen science in ecological restoration: a case study in streams

Citizen science has the potential to generate valuable biologic data for use in restoration monitoring, while also providing a unique opportunity for public participation in local restoration projects. In this article, we describe and evaluate a citizen science program designed to monitor the effect of stream restoration construction disturbance on the macroinvertebrate community. We present the results of a 7‐year stream restoration study conducted by citizen scientists utilizing a Before‐After‐Control‐Impact (BACI) design. Trait‐based macroinvertebrate data showed a strong response to restoration construction disturbance and return to pre‐restoration conditions within 2 years. The findings of this study suggest that citizen science can generate meaningful BACI‐oriented data about ecological restoration; however, until more research is conducted, citizen data should only be used to augment professional data intended to demonstrate restoration success.     

On the role of hypotheses in science

Scientific research progresses by the dialectic dialogue between hypothesis building and the experimental testing of these hypotheses. Microbiologists as biologists in general can rely on an increasing set of sophisticated experimental methods for hypothesis testing such that many scientists maintain that progress in biology essentially comes with new experimental tools. While this is certainly true, the importance of hypothesis building in science should not be neglected. Some scientists rely on intuition for hypothesis building. However, there is also a large body of philosophical thinking on hypothesis building whose knowledge may be of use to young scientists. The present essay presents a primer into philosophical thoughts on hypothesis building and illustrates it with two hypotheses that played a major role in the history of science (the parallel axiom and the fifth element hypothesis). It continues with philosophical concepts on hypotheses as a calculus that fits observations (Copernicus), the need for plausibility (Descartes and Gilbert) and for explicatory power imposing a strong selection on theories (Darwin, James and Dewey). Galilei introduced and James and Poincaré later justified the reductionist principle in hypothesis building. Waddington stressed the feed-forward aspect of fruitful hypothesis building, while Poincaré called for a dialogue between experiment and hypothesis and distinguished false, true, fruitful and dangerous hypotheses. Theoretical biology plays a much lesser role than theoretical physics because physical thinking strives for unification principle across the universe while biology is confronted with a breathtaking diversity of life forms and its historical development on a single planet. Knowledge of the philosophical foundations on hypothesis building in science might stimulate more hypothesis-driven experimentation that simple observation-oriented “fishing expeditions” in biological research.     

中华民族永生细胞库在生命科学研究中的支撑作用

人类样品是生物医学研究必需的物质基础。B淋巴母细胞系(LCL)是利用Epstein-Barr(EB)病毒转化人的B细胞获得,制备简便,可以无限繁殖,是非常便捷的保存人类样品的形式。中华民族永生细胞库保藏有中国各个民族群体的LCL。目前,已经有详实的LCL的性质研究以及关于LCL的全基因组数据,因而, LCL已经广泛应用于遗传学、免疫学、药学基因组学、再生医学、癌症发生与免疫治疗、筛选制备全人单克隆中和抗体及EB病毒致病机理等研究领域。本文对LCL的特性以及LCL在上述研究领域中的应用进行了综述,最后对中华民族永生细胞库的保藏内容做了简单介绍,以促进广大科研人员进一步了解该细胞库的科研价值,充分发挥该库保藏资源在基础科学、生物医学研究中的科技支撑作用。     

Microbial traces and their role in forensic science

Forensic microbiology, also known as the microbiology of death, is an emerging branch of science that is still underused in criminal investigations. Some of the cases might be difficult to solve with commonly used forensic methods, and then they become an operational field for microbiological and mycological analyses. The aim of our review is to present significant achievements of selected studies on the thanatomicrobiome (micro-organisms found in the body, organs and fluids after death) and epinecrotic community (micro-organisms found on decaying corpses) that can be used in forensic sciences. Research carried out as a part of the forensic microbiology deals with the thanatomicrobiome and the necrobiome—communities of micro-organisms that live inside and outside of a putrefying corpse. Change of species composition observed in each community is a valuable feature that gives a lot of information related to the crime. It is mainly used in the estimation of post-mortem interval (PMI). In some criminal investigations, such noticeable changes in the microbiome and mycobiome can determine the cause or the actual place of death. The microbial traces found at the crime scene can also provide clear evidence of guilt. Nowadays, identification of micro-organisms isolated from the body or environment is based on metagenome analysis and 16S rRNA gene amplicon-based sequencing for bacteria and ITS rRNA gene amplicon-based sequencing for fungi. Cultivation methods are still in use and seem to be more accurate; however, they require much more time to achieve a final result, which is an unwanted feature in any criminal investigation.     

The role of expert systems in vegetation science

An area of artificial intelligence known as experts systems (or knowledge-based systems) is being applied in many areas of science, technology and commerce. It is likely that the techniques will have an impact on vegetation science and ecology in general. This paper discusses some of those impacts and concludes that the main effects will be in areas of applied ecology especially where ecological expertise is needed either quickly (e.g. disaster management) or across a wide range of ecological disciplines (e.g. land management decisions). Expert systems will provide ecologists with valuable tools for managing data and interacting with other fields of expertise. The impact of expert systems on ecological theory will depend on the degree to which deep knowledge (i.e. knowledge based on first principles rather than on more empirical rules) is used in formulating knowledge bases.