Biological Anthropology and Ethics: From Repatriation to Genetic Identity

Biological Anthropology and Ethics: From Repatriation to Genetic Identity . Trudy R. Turner, ed. Albany: State University of New York Press, 2004. 327 pp.     

Decolonizing Knowledge: From Development to Dialogue

Decolonizing Knowledge: From Development to Dialogue. Frederique Apffel-Marglin and Stephen A. Marglin. eds. Oxford, England: Clarendon Press, 1996. 398 pp.     

生命之树与进化模式:导言

One and half centuries ago, Charles Darwin (1859) presented overwhelming evidence and argued that all life on the earth shared common descent, and "from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved". Ernst Haeckel (1886) and several of his contemporaries attempted to trace the pattern of descent among all extant and extinct forms in what Darwin referred to as "the great Tree of Life". Ever since then, systematists and evolutionary biologists have been exploring morphological, cytogenetic, chemical, developmental and molecular characters, and actively developing theories and methods to infer phylogenetic relationships among organisms from these characters. This endeavor has been especially stimulated by the rise of molecular biology and the emergence of computer science over the past 50 years. At the beginning of the 21st century, we are presented with an unprecedented opportunity to reconstruct the entire Tree of Life, and further, to study evolutionary processes and mechanisms in the context of a robust phylogenetic framework.     

Integrating Biomedical Knowledge to Model Pathways of Prostate Cancer Progression

Due to pathologic, histologic, and biologic variation within prostate cancers, profiling the genetic changes associated with disease progression has been difficult. Although initial integration of data from profiling studies had been limited by platform variation, bioinformatic tools and analytic techniques have enabled integrative analysis of profiling studies and the identification of more robust and valid profiles. The identification of key transition points in the progression of prostate cancer relies on profiling precursor lesions and “pure” cell populations. Utilizing laser-capture microdissection to isolate 101 cell populations, a more specific genetic profile of progression from benign epithelium to metastatic disease was obtained. This laser-capture profile was analyzed in the context of the Molecular Concepts Map (MCM), a compendium of over 15,000 molecular concepts including other expression profiles of prostate cancer, to obtain an integrative molecular model of progression. The conceptual connections associated with progression confirm that prostate cancer biology is largely driven by pathways related to androgen signaling and epithelial cell biology; however, further analysis of concepts associated with progression suggests stromal factors are highly associated with progression of prostate cancer. The effect of stromal signatures on the progression model suggests the impact of stromal signature downregulation may reflect both a change in the epithelia:stroma ratio within higher grade tumors and also a microenvironment influence on prostate epithelia. Analyzing complex gene expression signatures in the context of molecular concepts improves integrative models and may improve detection, prognostication, or targeted therapy.     

Conditional Genetic Transsynaptic Tracing in the Embryonic Mouse Brain

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits during embryonic maturation of the brain however is technically challenging because most transsynaptic tracing methods developed to date depend on stereotaxic tracer injection. To overcome this problem, we developed a binary genetic strategy for conditional genetic transsynaptic tracing in the mouse brain. Towards this end we generated two complementary knock-in mouse strains to selectively express the bidirectional transsynaptic tracer barley lectin (BL) and the retrograde transsynaptic tracer Tetanus Toxin fragment C from the ROSA26 locus after Cre-mediated recombination. Cell-specific tracer production in these mice is genetically encoded and does not depend on mechanical tracer injection. Therefore our experimental approach is suitable to study neural circuit formation in the embryonic murine brain. Furthermore, because tracer transfer across synapses depends on synaptic activity, these mouse strains can be used to analyze the communication between genetically defined neuronal populations during brain development at a single cell resolution. Here we provide a detailed protocol for transsynaptic tracing in mouse embryos using the novel recombinant ROSA26 alleles. We have utilized this experimental technique in order to delineate the neural circuitry underlying maturation of the reproductive axis in the developing female mouse brain.     

Controlling Life: From Jacques Loeb to Regenerative Medicine

In his 1987 book Controlling Life: Jacques Loeb and the Engineering Ideal in Biology, Philip Pauly presented his readers with the biologist Jacques Loeb and his role in developing an emphasis on control of life processes. Loeb’s work on artificial parthenogenesis, for example, provided an example of bioengineering at work. This paper revisits Pauly’s study of Loeb and explores the way current research in regenerative medicine reflects the same tradition. A history of regeneration research reveals patterns of thinking and research methods that both echo Loeb’s ideology and point the way to modern studies. Pauly’s work revealed far more than we readers realized at the time of its publication.     

Using Genealogical Mapping and Genetic Neighborhood Sizes to Quantify Dispersal Distances in the Neotropical Passerine,the Black-Capped Vireo

Dispersal is a key demographic process, ultimately responsible for genetic connectivity among populations. Despite its importance, quantifying dispersal within and between populations has proven difficult for many taxa. Even in passerines, which are among the most intensely studied, individual movement and its relation to gene flow remains poorly understood. In this study we used two parallel genetic approaches to quantify natal dispersal distances in a Neotropical migratory passerine, the black-capped vireo. First, we employed a strategy of sampling evenly across the landscape coupled with parentage assignment to map the genealogical relationships of individuals across the landscape, and estimate dispersal distances; next, we calculated Wright’s neighborhood size to estimate gene dispersal distances. We found that a high percentage of captured individuals were assigned at short distances within the natal population, and males were assigned to the natal population more often than females, confirming sex-biased dispersal. Parentage-based dispersal estimates averaged 2400m, whereas gene dispersal estimates indicated dispersal distances ranging from 1600–4200 m. Our study was successful in quantifying natal dispersal distances, linking individual movement to gene dispersal distances, while also providing a detailed look into the dispersal biology of Neotropical passerines. The high-resolution information was obtained with much reduced effort (sampling only 20% of breeding population) compared to mark-resight approaches, demonstrating the potential applicability of parentage-based approaches for quantifying dispersal in other vagile passerine species.     

Genetic Characterization of Human Populations: From ABO to a Genetic Map of the British People

From 1900, when Landsteiner first described the ABO blood groups, to the present, the methods used to characterize the genetics of human populations have undergone a remarkable development. Concomitantly, our understanding of the history and spread of human populations across the earth has become much more detailed. As has often been said, a better understanding of the genetic relationships among the peoples of the world is one of the best antidotes to racial prejudices. Such an understanding provides us with a fascinating, improved insight into our origins as well as with valuable information about population differences that are of medical relevance. The study of genetic polymorphisms has been essential to the analysis of the relationships between human populations. The evolution of methods used to study human polymorphisms and the resulting contributions to our understanding of human health and history is the subject of this Perspectives.THE A, B, and O blood types of the ABO blood group system were first described by Landsteiner in 1900, the year of the rediscovery of Mendel’s work. Landsteiner had set out to see whether the sorts of differences between species that had been detected by serological methods might also occur within species (see Owen, 2008). The experiment was very simple: mix the red blood cells of one person with the serum of another and do this pairwise for a number of people. To his surprise, he found that certain combinations of serum and red cells led to clumping or agglutination of the red cells. Based on the resulting patterns of agglutination of the red cells, three types of serum and red cells were identified: A (which agglutinates only B cells), B (which agglutinates only A cells), and O (which agglutinates both A and B cells). [Landsteiner did not at first observe AB serum (which agglutinates neither A or B cells) because of the small size of his sample.] These types seemed to be intrinsic to the individual and did not change with time or, for example, the presence of infections. They were, as we now know, the inherited characteristics of an individual’s red blood cells. Landsteiner’s work, together with many subsequent developments, meant that blood transfusions became possible and eventually much safer. In addition, this simple but fundamental analysis was the initial stimulus for all subsequent studies of the frequency of genetic variation in different human populations and the use of genetic variants for characterizing genetic differences among humans.     

Genetic Structure and Gene Flows within Horses: A Genealogical Study at the French Population Scale

Since horse breeds constitute populations submitted to variable and multiple outcrossing events, we analyzed the genetic structure and gene flows considering horses raised in France. We used genealogical data, with a reference population of 547,620 horses born in France between 2002 and 2011, grouped according to 55 breed origins. On average, individuals had 6.3 equivalent generations known. Considering different population levels, fixation index decreased from an overall species F_IT of 1.37%, to an average of −0.07% when considering the 55 origins, showing that most horse breeds constitute populations without genetic structure. We illustrate the complexity of gene flows existing among horse breeds, a few populations being closed to foreign influence, most, however, being submitted to various levels of introgression. In particular, Thoroughbred and Arab breeds are largely used as introgression sources, since those two populations explain together 26% of founder origins within the overall horse population. When compared with molecular data, breeds with a small level of coancestry also showed low genetic distance; the gene pool of the breeds was probably impacted by their reproducer exchanges.     

Genetic regulation of aflatoxin biosynthesis: From gene to genome

Aflatoxins are notorious toxic secondary metabolites known for their impacts on human and animal health, and their effects on the marketability of key grain and nut crops. Understanding aflatoxin biosynthesis is the focus of a large and diverse research community. Concerted efforts by this community have led not only to a well-characterized biosynthetic pathway, but also to the discovery of novel regulatory mechanisms. Common to secondary metabolism is the clustering of biosynthetic genes and their regulation by pathway specific as well as global regulators. Recent data show that arrangement of secondary metabolite genes in clusters may allow for an important global regulation of secondary metabolism based on physical location along the chromosome. Available genomic and proteomic tools are now allowing us to examine aflatoxin biosynthesis more broadly and to put its regulation in context with fungal development and fungal ecology. This review covers our current understanding of the biosynthesis and regulation of aflatoxin and highlights new and emerging information garnered from structural and functional genomics. The focus of this review will be on studies in Aspergillus flavus and Aspergillus parasiticus, the two agronomically important species that produce aflatoxin. Also covered will be the important contributions gained by studies on production of the aflatoxin precursor sterigmatocystin in Aspergillus nidulans.     

The Ethics of Discharging Asylum Seekers to Harm: A Case From Australia

In February 2016 a twelve-month-old asylum seeker, who came to be know as Baby Asha, was transferred from Nauru and hospitalized in Brisbane. This case came to public attention after Doctors refused to discharge Asha as she would have been returned to detention on Nauru. What in other circumstances would have been considered routine clinical care, quickly turned into an act of civil disobedience. This paper will discuss the ethical aspects of this case, along with its implications for clinicians and the broader healthcare community.