细胞功能测定

DNA polymerases catalyze the synthesis of DNA molecules from monomeric deoxynucleotide triphosphate units. This definition encompasses those enzymes classed as DNA-dependent DNA polymerases (EC 2.7.7.7, which require both a DNA template strand and a DNA primer to which the monomer ...

DNA-dependent RNA polymerases (ribonucleoside triphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) catalyze the synthesis of RNA from ribonucleoside triphosphates in the presence of a DNA template and divalent cation (1).

The conversion of mRNA into cDNA is the essential first step in the study of eukaryotic cell products expressed from cloned genes. The key enzyme used first in this process, retroviral RNA-directed DNA polymerase (reverse transcriptase), catalyzes the synthesis of a DNA copy of an RNA template in ...

Terminal deoxyribonucleotidyl transferase (TdT) (EC 2.7.7.3 1) catalyzes the addition of deoxynucleoside triphosphates to the 3′ ends of oligo-and polynucleotide primers. Different from all the other known DNA polymerases, TdT-catalyzed DNA synthesis is not template-direct ...

Restriction enzymes are endonucleases that recognize specific double-stranded DNA sequences and cleave the DNA in both strands, e.g.: (1) They have been identified in many prokaryotic organisms and are considered to be part of a defense system directed against foreign DNA. Site-specific ...

DNA methyltransferases (Mtases) catalyze the transfer of the S-methyl group of S-adenosylmethionine (SAM) to deoxycytosine (dC) or deoxyadenine (dA) bases within defined DNA sequences (1). Individual enzymes are specific for one or the other base, and modify at the 6-NH2 of dA (EC 2.1.1.72) or at t ...

In elucidating a novel cell-cycle pathway or mode of regulation, it will first be necessary to establish that the cell is arrested in a particular stage of the cell cycle following arrest-inducing conditions. This is achieved by staining the DNA in a population of cells with propidium iodide and then ...

The discipline of developmental biology covers scientific investigations aimed at deciphering the underlying mechanisms responsible for diversity and order within tissues and organs. It is the goal of Developmental Biology Protocols to present to the readers a set of contempora ...

The ex vivo culture of intact fetal thymus lobes, fetal thymic organ culture (FTOC) has proven to be a useful technique for the elucidation of the molecular and cellular bases of T-cell development and T-cell receptor (TCR) repertoire selection (reviewed in ref. 1. Most dramatically, FTOC has been u ...

Chicken skin development is an excellent model to study the mechanisms of morphogenesis. It has a long experimental history and has been well characterized phenotypically. Chicken skin offers distinct patterns, large numbers of different cutaneous appendages, availability of in v ...

During embryonic development, pluripotent cells from the endoderm layer are directed toward specific cell lineages, leading to the formation of highly specialized organs, such as liver, lung, and pancreas. In case of liver, hepatocyte specification and maturation is the result of a tiss ...

Development involves a delicate orchestration of cell division, movement, differentiation, and death. Cell death in mammalian embryogenesis occurs as early as inner cell-mass differentiation, and it continues to be part of the developing embryo during the formation and functional ...

There are many times during Drosophila development or in the adult when cell death contributes to a phenotype of interest (e.g., refs. 1-5, and many others). The cell death may be primary to gene function or a secondary consequence of failure of proper differentiation or cell maintenance (e.g., ref. 6). To d ...

In many instances, the strength of Drosophila melanogaster genetics can be used to enhance our understanding of complex vertebrate signaling systems. The general success of this approach is underscored by the large number of vertebrate signaling components whose very names derive in p ...

Activin, a peptide growth factor, is a member of the transforming growth factor-β (TGF-β) superfamily. It was originally isolated from follicle fluid as a gonadal hormone that stimulates follicle-stimulating hormone (FSH) secretion and is identical to EDF, the erythroid differentia ...

One of the key issues in developmental biology is the question of specification. Specification is the commitment of a group of cells to proceed down a developmental pathway without further extraneous signals. In order identify the development period in which cells have acquired all the nece ...

Mammary gland development is marked by numerous cellular changes that begin in the embryo, continue postnatally, are modified at puberty, and come to full fruition during the adult cycles of pregnancy, lactation, and involution. These changes are initiated by hormones produced at distant ...

During early craniofacial development, cranial neural crest cells emigrate from seg-mentally distinct divisions of the hindbrain (rhombomeres) to populate the various branchial arches and subsequently differentiate into multiple neuronal and non-neu-ronal cell linea ...

All the bones of the craniofacial skeleton are united by the fibrous sutures, and those of the neurocranium are lined additionally by the dura mater. The sutures and dura mater are not only integral structural elements of the formed skeleton, but during morphogenesis they also are sites of apposi ...

The formation of a skeleton with its numerous bones of various shapes and sizes and the growth of these bones from embryonic to adult size is a complex process involving a multitude of genes. The complexity of the process is reflected by the large number of inherited diseases with skeletal phenotypes ...