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Zerknüllt
''Zerknüllt'' (zen, German for "crumpled") is a gene in the Antennapedia complex of ''Drosophila'' (fruit flies) and other insects, where it operates very differently from the canonical Hox genes in the same gene cluster. Comparison of Hox genes between species showed that the ''Zerknüllt'' gene evolved from one of the standard Hox genes (the 'paralogy group 3' Hox gene) in insects through accumulating many amino acid changes, changing expression pattern, losing ancestral function and gaining a new function. ''Zerknüllt'' codes for a homeoprotein regulates aspects of early embryogenesis in insects. Unlike the canonical Hox genes which are expressed in precise zones along the anteroposterior (head to tail) body axis, ''zerknüllt'' expression is restricted along the dorsoventral (back to belly) body axis. Expression of ''Zerknüllt'' is repressed in the ventral part of the embryo by a protein called Dorsal, and activated in the dorsal part of the embryo by the TGF beta signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German (language)
German ( ) is a West Germanic language mainly spoken in Central Europe. It is the most widely spoken and official or co-official language in Germany, Austria, Switzerland, Liechtenstein, and the Italian province of South Tyrol. It is also a co-official language of Luxembourg and Belgium, as well as a national language in Namibia. Outside Germany, it is also spoken by German communities in France (Bas-Rhin), Czech Republic (North Bohemia), Poland (Upper Silesia), Slovakia (Bratislava Region), and Hungary (Sopron). German is most similar to other languages within the West Germanic language branch, including Afrikaans, Dutch, English, the Frisian languages, Low German, Luxembourgish, Scots, and Yiddish. It also contains close similarities in vocabulary to some languages in the North Germanic group, such as Danish, Norwegian, and Swedish. German is the second most widely spoken Germanic language after English, which is also a West Germanic language. German is one of the maj ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Flour Beetle
The red flour beetle (''Tribolium castaneum'') is a species of beetle in the family Tenebrionidae, the darkling beetles. It is a worldwide pest of stored products, particularly food grains, and a model organism for ethological and food safety research. Description Adult beetles are small, around 3-4mm long (1/8 inches), of a uniform rust, brown or black color. Head and pronotum are sometimes darker than rest of body. Ecology The red flour beetle attacks stored grain and other food products including flour, cereals, pasta, biscuits, beans, and nuts, causing loss and damage. The United Nations, in a recent post-harvest compendium, estimated that ''Tribolium castaneum'' and ''Tribolium confusum'', the confused flour beetle, are "the two most common secondary pests of all plant commodities in store throughout the world." Distribution and habitat The red flour beetle is of Indo-Australian origin and less able to survive outdoors than the closely related species ''Tribolium confus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regional Specification
In the field of developmental biology, regional differentiation is the process by which different areas are identified in the development of the early embryo. The process by which the cells become specified differs between organisms. Cell fate determination In terms of developmental commitment, a cell can either be specified or it can be determined. Specification is the first stage in differentiation. A cell that is specified can have its commitment reversed while the determined state is irreversible. There are two main types of specification: autonomous and conditional. A cell specified autonomously will develop into a specific fate based upon cytoplasmic determinants with no regard to the environment the cell is in. A cell specified conditionally will develop into a specific fate based upon other surrounding cells or morphogen gradients. Another type of specification is syncytial specification, characteristic of most insect classes. Specification in sea urchins uses both auton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Embryogenesis
''Drosophila'' embryogenesis, the process by which ''Drosophila'' (fruit fly) embryos form, is a favorite model system for genetics and developmental biology. The study of its embryogenesis unlocked the century-long puzzle of how development was controlled, creating the field of evolutionary developmental biology. The small size, short generation time, and large brood size make it ideal for genetic studies. Transparent embryos facilitate developmental studies. ''Drosophila melanogaster'' was introduced into the field of genetic experiments by Thomas Hunt Morgan in 1909. Life cycle ''Drosophila'' display a holometabolous method of development, meaning that they have three distinct stages of their post-embryonic life cycle, each with a radically different body plan: larva, pupa and finally, adult. The machinery necessary for the function and smooth transition between these three phases develops during embryogenesis. During embryogenesis, the larval stage fly will develop and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bombyx Mori
The domestic silk moth (''Bombyx mori''), is an insect from the moth family Bombycidae. It is the closest relative of ''Bombyx mandarina'', the wild silk moth. The silkworm is the larva or caterpillar of a silk moth. It is an economically important insect, being a primary producer of silk. A silkworm's preferred food are white mulberry leaves, though they may eat other mulberry species and even the osage orange. Domestic silk moths are entirely dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silk moths (other species of ''Bombyx'') are not as commercially viable in the production of silk. Sericulture, the practice of breeding silkworms for the production of raw silk, has been under way for at least 5,000 years in China, whence it spread to India, Korea, Nepal, Japan, and the West. The domestic silk moth was domesticated from the wild silk moth ''Bombyx mandarina'', which has a range from northern India to northern China, Korea, Japan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic rank, superfamilies, 10 percent of the total described species of living organisms. It is one of the most widespread and widely recognizable insect orders in the world. The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought, and is among the four most wikt:speciose, speciose orders, along with the Hymenoptera, fly, Diptera, and beetle, Coleoptera. Lepidopteran species are characterized by more than three derived features. The most apparent is the presence of scale (anatomy), scales that cover the torso, bodies, wings, and a proboscis. The scales are modified, flattened "hairs", and give ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Duplication
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination, retrotransposition event, aneuploidy, polyploidy, and replication slippage. Mechanisms of duplication Ectopic recombination Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes. The products of this recombination are a duplication at the site of the exchange and a reciprocal deletion. Ectopic recombination is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicoid
Homeotic protein bicoid is encoded by the ''bcd'' maternal effect gene in ''Drosophilia''. Homeotic protein bicoid concentration gradient patterns the anterior-posterior (A-P) axis during ''Drosophila'' embryogenesis. Bicoid was the first protein demonstrated to act as a morphogen. Although bicoid is important for the development of ''Drosophila'' and other higher dipterans, it is absent from most other insects, where its role is accomplished by other genes. Role in axial patterning ''Bicoid'' mRNA is actively localized to the anterior of the fruit fly egg during oogenesis along microtubules by the motor protein dynein, and retained there through association with cortical actin. Translation of ''bicoid'' is regulated by its 3′ UTR and begins after egg deposition. Diffusion and convection within the syncytium produce an exponential gradient of Bicoid protein within roughly one hour, after which Bicoid nuclear concentrations remain approximately constant through cellulariza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Duplication
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination, retrotransposition event, aneuploidy, polyploidy, and replication slippage. Mechanisms of duplication Ectopic recombination Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes. The products of this recombination are a duplication at the site of the exchange and a reciprocal deletion. Ectopic recombination is ... [...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] |
TGF Beta Signaling Pathway
The transforming growth factor beta (TGFB) signaling pathway is involved in many cellular processes in both the adult organism and the developing embryo including cell growth, cell differentiation, cell migration, apoptosis, cellular homeostasis and other cellular functions. The TGFB signaling pathways are conserved. In spite of the wide range of cellular processes that the TGFβ signaling pathway regulates, the process is relatively simple. TGFβ superfamily ligands bind to a type II receptor, which recruits and phosphorylates a type I receptor. The type I receptor then phosphorylates receptor-regulated SMADs ( R-SMADs) which can now bind the coSMAD SMAD4. R-SMAD/coSMAD complexes accumulate in the nucleus where they act as transcription factors and participate in the regulation of target gene expression. Mechanism Ligand binding The TGF beta superfamily of ligands includes: Bone morphogenetic proteins (BMPs), Growth and differentiation factors (GDFs), Anti-müllerian hormo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Embryogenesis
''Drosophila'' embryogenesis, the process by which ''Drosophila'' (fruit fly) embryos form, is a favorite model system for genetics and developmental biology. The study of its embryogenesis unlocked the century-long puzzle of how development was controlled, creating the field of evolutionary developmental biology. The small size, short generation time, and large brood size make it ideal for genetic studies. Transparent embryos facilitate developmental studies. ''Drosophila melanogaster'' was introduced into the field of genetic experiments by Thomas Hunt Morgan in 1909. Life cycle ''Drosophila'' display a holometabolous method of development, meaning that they have three distinct stages of their post-embryonic life cycle, each with a radically different body plan: larva, pupa and finally, adult. The machinery necessary for the function and smooth transition between these three phases develops during embryogenesis. During embryogenesis, the larval stage fly will develop and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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