Preface

Gene expression is a process by which genetic information is used in the synthesis of functional products including proteins and functional RNAs, such as transfer RNA (tRNA), small nuclear RNA (sn RNA), micro RNA (miRNA), small/short interfering RNA (siRNA), among others. This process is utilized by eukaryotes, prokaryotes, and viruses to generate macromolecules for constituting cellular components and exhibiting living functions. Several steps in the gene expression process could be regulated, such as transcription, post-transcriptional modification, translation, and post-translational modification. Regulation of gene expression is to modulate the production amount and timing of the functional products. Control of gene expression is critical to allow cells to produce their functional products when cells need them; in turn, this gives cells the flexibility to adapt to a variable environment, and respond to external signals, stimuli, and damages. Cellular structures and functions can also be controlled by gene expression regulation. Consequently, the regulation is crucial for cells to proliferate, differentiate, transport, metabolize, and repair. It is advantageous to the versatility, development, and adaptability of living organisms. A phenotypic trait, the expression of genes in an observable way, is an obvious and measurable trait. For example, hair color is a phenotypic trait and genotype composed of genes that determine hair color, but the hair color observed is the phenotype. The phenotype is variable depending on the genetic make-up of the organism, and influenced by the surroundings to which the organism is subjected across its morphogenesis, including various epigenetic processes. In this book, these findings and their implications are broadly discussed, and future genomic and phenotypic studies, analyses, and applications are highlighted. In this book, we explore the significance, mechanism, function, characteristic, determination and application of gene expression and phenotypic traits.

We are grateful for the participation of all authors and IntechOpen's enthusiasm in helping us to complete and publish this book.

**II**

**Chapter 8 141**

**Chapter 9 163**

Gene Evolution **177**

**Chapter 10 179**

Gene Expression Profile of HDF in SMG Partially Overlaps with That

Environmental Factors Affecting the Expression of Bilateral-Symmetrical

*by Sergey Baranov, Igor Vinokurov and Lubov Fedorova*

Sellafield, Seascale, and Scandinavia: A Legacy of Radioactive

Contamination with Future Implications for Gene Evolution in Affected

in the NASA Twins Study *by Jade Q. Clement*

Traits in Plants

**Section 4**

Ecosystems

*by Chanda Siddoo-Atwal*

**Yuan-Chuan Chen, PhD** Program in Comparative Biochemistry, University of California, Berkeley, CA, USA

> **Shiu-Jau Chen, MD, PhD** Department of Neurosurgery, Mackay Memorial Hospital, Taipei, Taiwan

**1**

Section 1

Background
