NEWS CENTER

新闻中心

奥博资讯

媒体报道

体系论文

首页

Invisible Impurities in Extracts: Re-examining the Half-Century Controversy Over the Tong Fish Experiments

发布时间：

2026-07-26

Invisible Impurities in Extracts: Re-examining the Half-Century Controversy Over the Tong Fish Experiments

Sun Zuodong

This article follows the previous piece One Nuclear Envelope, Two Sets of Windmills: How Bioelectric Fields Determine the Direction of Cellular Development. We rely on the dual windmill model to explain the developmental patterns of nuclear-transfer fish. To untangle this academic dispute spanning half a century, we must first conduct a rigorous review of the series of experiments led by Professor Tong Dizhou and distinguish two long-confused lines of research.

I. Timeline Review: Two Distinct Lines of Research

In the 1950s, the mainstream view in international biology held that all heritable traits were entirely governed by the cell nucleus. Professor Tong Dizhou questioned this consensus and put forward the hypothesis that both the nucleus and cytoplasm jointly regulate embryonic development, which he set out to verify through hands-on experiments.

1958–1962: Technical Breakthrough Phase

Working with rudimentary equipment, the team independently built micromanipulation setups and mastered the core techniques for enucleation and nuclear transfer in fish oocytes. They completed preliminary intraspecies nuclear transfer experiments using goldfish and bitterling.

1963: Landmark Interspecies Nuclear Transfer Experiment

The team transplanted blastula cell nuclei from bitterling into enucleated goldfish oocytes. The resulting fry exhibited traits from both parent species. Based on this observation, Professor Tong concluded that the nucleus alone could not fully determine biological traits, and the cytoplasm exerted a profound influence on embryonic development. In the following years, reciprocal nuclear transfer experiments between common carp and crucian carp repeatedly validated this conclusion, laying the theoretical foundation for nuclear-cytoplasmic interaction. This entire body of research was completed solely by Tong Dizhou’s team, prior to his collaboration with Niu Man-chang.

Early 1970s: Collaborative Research with Niu Man-chang

Niu Man-chang returned to China for academic exchanges, launching a joint research partnership. The experimental focus shifted from transplanting intact cell nuclei to injecting cytoplasmic extracts—the collaborative trials later widely known as the "Tong Fish experiments".

It is critical to clearly separate the two distinct studies:

1.Nuclear-transfer fish (1963): An independent achievement of Tong Dizhou’s research group. The core procedure involved transplanting intact cell nuclei to reconstruct nuclear-cytoplasmic combinations.

2.Tong Fish injection experiments (1973): Joint work by Tong Dizhou and Niu Man-chang. The recipient oocyte retained its original nucleus; only cytoplasmic extracts were injected into the egg.

Unfortunately, popular science materials have long conflated these two distinct studies under the single label "Tong Fish experiments", leading to decades of misinterpretation of their underlying mechanisms.

II. Long-Standing Simplified Conclusions Contain Critical Flaws

The conventional academic interpretation holds that the Tong Fish experiments directly proved free cytoplasmic mRNA can induce stably heritable traits. However, when contextualized against the technical limitations of 1973, this one-dimensional causal attribution is untenable.

At that time, techniques for purifying biological macromolecules were immature. Breaking oocytes to prepare extracts frequently ruptured nuclear envelopes. Tetrameric ion channel complexes embedded within the nuclear membrane—the origami windmill structures described earlier—detached and mixed into the extraction solution. Given the technological constraints of the era, researchers could not fully separate these membrane protein complexes from nucleic acid components.

This means the injected sample was not a purified single mRNA solution, but a complex mixture containing both free nucleic acids and abundant fragments of membrane structures.

III. Could "Impurities" Be the Key Variable Disturbing Developmental Processes

Drawing on the dual windmill model, the author proposes a new interpretive hypothesis: The core substance triggering changes in caudal fin morphology may not be the widely accepted mRNA. Instead, exogenous detached tetramer fragments mixed within the extract act as a "Trojan horse" disrupting the cell’s developmental regulatory network.

Foreign tetramer complexes integrate into the oocyte’s native membrane channel system, destabilizing the homeostatic bioelectric field and thereby altering biological phenotypes. mRNA present in the extract functions only as a secondary signaling molecule, capable of inducing minor local trait modifications at most.

IV. The Hypothesis Explains the Reproducibility Crisis Plaguing the Experiments

This reasoning resolves a longstanding puzzle for the scientific community: laboratories worldwide have struggled to consistently replicate results from the Tong Fish trials.

Experimental outcomes are highly sensitive to the degree of cellular lysis. Harsher lysis ruptures more nuclear envelopes, releasing greater quantities of detached tetramers and producing more pronounced phenotypic variation. Conversely, gentle cell lysis, or purification protocols that remove most membrane components, drastically weaken or entirely eliminate trait induction effects. Without standardized control over this critical hidden variable, consistent experimental replication becomes impossible.

V. Unifying the Logical Framework of the Two Classic Experiments

A side-by-side comparison clarifies the hierarchical layers of genetic regulation:

1.1963 nuclear-transfer fish experiments: Intact nuclei with complete nuclear envelopes and full sets of tetramer channel systems were transplanted, establishing an entirely new bioelectric regulatory circuit that drove systemic cross-species trait remodeling across the whole organism.

2.1973 Tong Fish injection experiments: Only scattered detached tetramer fragments entered the cell, lacking a complete regulatory pathway—consequently, only localized trait changes such as modified caudal fins were observed.

The two experiments mutually corroborate one another: ion channel systems embedded in cell and nuclear membranes, together with bioelectric fields, serve as the top-tier regulators of cellular development. Soluble cytoplasmic components including free RNA and soluble proteins only mediate localized epigenetic modifications.

Conclusion: Theoretical Iteration, Not a Rejection of Pioneering Work

This paper does not question the empirical observations recorded by Tong Dizhou’s research team. The nuclear-transfer fish experiments pioneered the dismantling of the rigid academic dogma that "the nucleus holds sole genetic control", securing an irreplaceable place for Professor Tong in the history of Chinese developmental biology.

The divergence addressed in this article targets the oversimplified causal conclusion later drawn from the 1973 collaborative experiments. Limited by mid-20th-century laboratory instrumentation, researchers could only observe the superficial correlation: injecting cytoplasmic extracts leads to altered traits. They lacked the means to distinguish the distinct functional roles of individual components within the mixed extract.

Scientific advancement proceeds through iterative refinement, stripping away oversimplified assumptions to uncover hidden variables. Recognizing detached tetramers as the long-overlooked "invisible impurity" erases the logical divide separating the two landmark fish experiments.

The theoretical implications extend far beyond reinterpreting classic developmental biology trials. Translating to neuroscience, disrupted ion channel balance in neuronal membranes and resultant bioelectric field dysregulation are major contributors to numerous neurological disorders. Looking forward, precise exogenous bioelectric modulation may emerge as an innovative therapeutic strategy for neurological diseases and the regulation of aberrant cell proliferation.