Look at the first cell on earth in a new perspective

A team at Harvard University recently created a model of a primitive cell, or protozoan, in a laboratory capable of growing, copying and containing DNA.

Since there is no record of the first cell shape on Earth, as well as its growth and division, the team's pre-cell project provides a useful method. aiming to understand the interaction between the first cells and the living environment about 3.5 billion years ago.

The pre-cell fatty acid membrane allows chemical compounds, including DNA building blocks, to go inside without the support of tubes and protein pumps like today's high-grade cell membranes. . Unlike modern cells, pre-cells do not use enzymes to catalyze DNA replication.

The research team, published by Jack W. Szostak of Harvard Medical School, published their first research results online on June 4, 2008 in Nature. Luis Echegoyen - NSF chemistry director - said: 'Szostak's team has applied an innovative method in research, while contributing significantly to our understanding of the process of transporting click molecules. small size through cell membrane '.

In the image is a 3-dimensional image of a pre-cell sample with a diameter of about 100 nanometers.The fatty acid membrane of the pre-cell allows nutrients and DNA building blocks to pass through, participating in DNA replication without the need for a catalytic enzyme.Newly formed DNA circuits are maintained in primitive cells.(Photo by Janet Iwasa, Szostak lab, Harvard Medical University and Massachusetts General Hospital)

Some scientists suggest that ancient hydrothermal vents may be where the prebiotic molecule (the molecule created before life forms) such as fatty acids or amino acids is formed.

When fatty acid molecules exist in the water environment, they spontaneously align so that water-loving 'heads' interact with the surrounding water molecules to shield the hydrophobic 'tail' , thereby forming the sphere. Small size fatty acids are called mixtures.

However, depending on the chemical concentration and pH of the environment, micelles can be converted into multi-layer films or closed bags (vesicle). Researchers often use closed bags to model cell membranes of precursor cells.

When the team began to study, they were not sure whether the building blocks needed for the replication of the cell's genetic material could pass through the membrane. Szostak said: 'By proving that it is completely possible and is actually very effective, we have come a little closer to the goal of making pre-cells in a suitable environment that can be born. Head and self-division '.

Dr Jack Szostak of the MGH Department of Molecular Biology and the Center for Integrated Biology and Computing and the lead author of the research report said: 'We found that the cell membrane made up of fatty acids together Related molecules have very different properties with modern cell membrane components. Modern cell membranes have specialized piping and pumping systems or holes that control all substances. Primitive cells can absorb nutrients from the environment and not produce the necessary material inside the cell. This is evidence to prove one of the two opposite hypotheses about the basic properties of pre-cells'.

Szostak's team conducted a thorough analysis of the vesicle made up of various fatty acid molecules with specific characteristics that make the cell membrane permeable to essential nutrient molecules. While large molecules of DNA such as DNA or RNA circuits cannot pass through fatty acid membranes, single sugar molecules as well as individual nucleotides can combine to create large nucleic acid molecules that easily penetrate cell membranes.

In order to further explore the function of cell fatty acid membranes, the researchers used activated nucleotides for research purposes to copy the sample DNA circuit without the polimerase catalyst enzyme that often appears in the duplication process. ADN. After placing the sample molecule into the fatty acid vesicle and then activating the activated nucleotide into the external environment, add a DNA circuit formed inside the vesicle. This confirms that the nucleotide molecule has penetrated the fatty acid membrane.

The co-authors of the Nature paper include Sheref S. Mansy, Jason P. Schrum, Mathangi Krishnamurthy, Sylvia Tobe and Douglas A. Treco (Szostak Laboratory). The research was funded by the National Science Foundation (Department of Chemistry, No. 0434507). Jack W. Szostak also received support from the National Abroad and Aeronautical Biology Program EXB02-0031-0018. Sheref S. Mansy was supported by the National Institutes of Health for fear of F32 GM07450601.