What Is Lost in the Weismann Barrier?

Abigail P Bline,Patrick Allard,Anne Le Goff

doi:10.3390/jdb8040035

Abigail P Bline, Patrick Allard + Show 1 more

Open Access

https://doi.org/10.3390/jdb8040035

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Abstract

The Weismann barrier has long been regarded as a basic tenet of biology. However, upon close examination of its historical origins and August Weismann’s own writings, questions arise as to whether such a status is warranted. As scientific research has advanced, the persistence of the concept of the barrier has left us with the same dichotomies Weismann contended with over 100 years ago: germ or soma, gene or environment, hard or soft inheritance. These dichotomies distract from the more important questions we need to address going forward. In this review, we will examine the theories that have shaped Weismann’s thinking, how the concept of the Weismann barrier emerged, and the limitations that it carries. We will contrast the principles underlying the barrier with recent and less recent findings in developmental biology and transgenerational epigenetic inheritance that have profoundly eroded the oppositional view of germline vs. soma. Discarding the barrier allows us to examine the interactive processes and their response to environmental context that generate germ cells in the first place, determine the entirety of what is inherited through them, and set the trajectory for the health status of the progeny they bear.

Highlights

The idea of the Weismann barrier provides a conceptual framework for the relationship between germ cells and somatic cells and the larger extraorganismal environment
The basic premise of the Weismann barrier, that is shared across its varied uses, is that germ cells are fundamentally separate from somatic cells
The authors shifted the argument for the separation of germ cells from the somatic cells: they reasoned that “undifferentiated” germ cells could not be derived from differentiated cells of the body but instead must come directly from the lineage of undifferentiated cells that remain such across generations [13]

Summary

Introduction

The idea of the Weismann barrier provides a conceptual framework for the relationship between germ cells and somatic cells and the larger extraorganismal environment. Weismann’s solution to this problem was described in his seminal 1893 work The Germ Plasm: A Theory of Heredity, in which he proposed a nuclear substance called the “germ plasm” as the essential unit of inheritance. Weismann’s model of the germ plasm was never widely accepted, the concept of a barrier named for him has been widely used as a default framework in which new scientific evidence and theories must be constructed. Modern-day scientific articles still refer to “crossing the Weismann barrier” [1,4] and evidence undermining the existence of such a barrier is described in this framework as an exception to the rule or a “leak” in the barrier. We seek to reevaluate the framework of the barrier itself and its limitations in light of contemporary scientific knowledge and to explore how scientific pursuits might advance differently without the framework of the Weismann barrier

Weismann’s Model of Inheritance

Origins of the Weismann Barrier

Emergent Germ Cell Fate and Function through Interaction with Somatic Cells

A Broader View of Heritable Information

Conclusions