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DAZ1
Deleted in azoospermia 1, also known as DAZ1, is a protein which in humans is encoded by the ''DAZ1'' gene. Function This gene is a member of the DAZ gene family and is a candidate for the human Y-chromosomal azoospermia factor (AZF). Its expression is restricted to pre-meiotic germ cells, particularly in spermatogonia. It encodes an RNA-binding protein that is important for spermatogenesis. Four copies of this gene are found on chromosome Y within palindromic duplications; one pair of genes is part of the P2 palindrome and the second pair is part of the P1 palindrome. Each gene contains a 2.4 kb repeat including a 72-bp exon, called the DAZ repeat; the number of DAZ repeats is variable and there are several variations in the sequence of the DAZ repeat. Each copy of the gene also contains a 10.8 kb region that may be amplified; this region includes five exons that encode an RNA recognition motif (RRM) domain. This gene contains three copies of the 10.8 kb repeat. However, n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAZ Protein Family
The DAZ (Deleted in AZoospermia) protein family is a group of three highly conserved RNA-binding proteins that are important in gametogenesis and meiosis. Therefore, mutations in the genes that encode for the DAZ proteins can have detrimental consequences for fertility. The three members of the DAZ protein family include BOULE (BOLL), DAZL (DAZLA) and DAZ (DAZ1, DAZ2, DAZ3 and DAZ4). DAZ1 is located on the Y chromosome in higher primates and is important for spermatogenesis. BOULE and DAZL are important for both oogenesis and spermatogenesis. BOULE and DAZL are both located on autosomes as single copies. However DAZ is located with multiple copies in the Y chromosome only. BOULE is present from invertebrates, DAZL is from vertebrates and DAZ is present from primates. Discovery Each DAZ protein family member was discovered individually, over a period of time by different research groups. BOULE was first identified in ''Drosophila,'' with homologs being found in other organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y Chromosome
The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or absence of Y that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the gene SRY, which triggers male development. The DNA in the human Y chromosome is composed of about 59 million base pairs, making it similar in size to chromosome 19. The Y chromosome is passed only from father to son. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest-evolving parts of the human genome. The human Y chromosome carries an estimated 100–200 genes, with between 45 and 73 of these being protein-coding. All single-copy Y-linked genes are hemizygous (present on only one chromosome) except in cases of aneuploidy such as XYY syndrome or XXYY syndrome. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAZAP2
DAZ-associated protein 2 is a protein that in humans is encoded by the ''DAZAP2'' gene. Function In mammals, the Y chromosome directs the development of the testes and plays an important role in spermatogenesis. A high percentage of infertile men have deletions that map to regions of the Y chromosome. The DAZ (deleted in azoospermia) gene cluster maps to the AZFc region and is deleted in many azoospermic and severely oligospermic men. It is thought that the Y chromosomal DAZ gene cluster arose from the transposition, amplification, and pruning of the ancestral autosomal gene DAZL. This gene encodes a RNA-binding protein with two RNP motifs that was originally identified by its interaction with the infertility factors DAZ and DAZL. Interactions DAZAP2 has been shown to interact with DAZ1 Deleted in azoospermia 1, also known as DAZ1, is a protein which in humans is encoded by the ''DAZ1'' gene. Function This gene is a member of the DAZ gene family and is a candidate for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAZL
Deleted in azoospermia-like is a protein that in humans is encoded by the ''DAZL'' gene. Function The DAZ (Deleted in AZoospermia) gene family encodes potential RNA binding proteins that are expressed in prenatal and postnatal germ cells of males and females. The protein encoded by this gene is localized to the nucleus and cytoplasm of fetal germ cells and to the cytoplasm of developing oocytes. In the testis, this protein is localized to the nucleus of spermatogonia but relocates to the cytoplasm during meiosis where it persists in spermatids and spermatozoa. Transposition and amplification of this autosomal gene during primate evolution gave rise to the DAZ gene cluster on the Y chromosome. Mutations in this gene have been linked to severe spermatogenic failure and infertility in males. In mice and pigs deficient in ''DAZL'', PGCs migrate to the gonad but do not undertake germ cell determination, and may instead produce germ cell tumors. Interactions DAZL has been sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azoospermia
Azoospermia is the medical condition of a man whose semen contains no sperm. It is associated with male infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and may be seen in up to 20% of male infertility situations in Canada. In a non-pathological context, azoospermia is also the intended result of a successful vasectomy. Classification Azoospermia can be classified into three major types as listed. Many conditions listed may also cause various degrees of oligospermia rather than azoospermia. Pretesticular and testicular azoospermia are known as non-obstructive azoospermia, whereas post-testicular azoospermia is considered obstructive. Pretesticular Pretesticular azoospermia is characterized by inadequate stimulation of otherwise normal testicles and genital tract. Typically, follicle-stimulating hormone (FSH) levels are low (hypogonadotropic) commensurate with inadequate stimulation of the testes to prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with only one copy of each chromosome ( haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome. Later on, during fertilisation, the haploid cells produced by meiosis from a male and female will fuse to create a cell with two copies of each chromosome again, the zygote. Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells, each with half the number of chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germ Cell
Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embryonic development * Cereal germ, the reproductive part of a cereal grain * Tooth germ, an aggregation of cells that eventually forms a tooth * Germ theory of disease, which states that some diseases are caused by microorganisms * Germ (mathematics), an object in a topological space that captures local properties Art and media Music * Germs (band), an American punk rock band * Germ (musician), a stage name of Tim Wright * Germ (rapper), an American rapper affiliated with Suicideboys and Pouya * "Germs" (song), by "Weird Al" Yankovic * ''The Germ'' (album), by Victim's Family Others * "Germs" (''Invader Zim''), an episode of ''Invader Zim'' * ''The Germ'' (periodical), a British art magazine published in 1850 * The Germs (comics) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogonia
A spermatogonium (plural: ''spermatogonia'') is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testis. There are three subtypes of spermatogonia in humans: *Type A (dark) cells, with dark nuclei. These cells are reserve spermatogonial stem cells which do not usually undergo active mitosis. *Type A (pale) cells, with pale nuclei. These are the spermatogonial stem cells that undergo active mitosis. These cells divide to produce Type B cells. *Type B cells, which undergo growth and become primary spermatocytes. Anticancer drugs Anticancer drugs such as doxorubicin and vincristine can adversely affect male fertility by damaging the DNA of proliferative spermatogonial stem cells. Experimental exposure of rat undifferentiated spermatogonia to doxorubicin and vincristine indicated that these cells are able to respond to DNA damage by increasing their expression of DNA repair genes, and that this r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogenesis
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells. Spermatozoa are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palindrome
A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards, such as the words ''madam'' or ''racecar'', the date and time ''11/11/11 11:11,'' and the sentence: "A man, a plan, a canal – Panama". The 19-letter Finnish word ''saippuakivikauppias'' (a soapstone vendor), is the longest single-word palindrome in everyday use, while the 12-letter term ''tattarrattat'' (from James Joyce in ''Ulysses'') is the longest in English. The word ''palindrome'' was introduced by English poet and writer Henry Peacham in 1638.Henry Peacham, ''The Truth of our Times Revealed out of One Mans Experience'', 1638p. 123/ref> The concept of a palindrome can be dated to the 3rd-century BCE, although no examples survive; the first physical examples can be dated to the 1st-century CE with the Latin acrostic word square, the Sator Square (contains both word and sentence palindromes), and the 4th-century Greek Byzantine sentence palindrome ''nipson ano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
