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Oscar Hertwig
Oscar Hertwig (21 April 1849 in Friedberg – 25 October 1922 in Berlin) was a German embryologist and zoologist known for his research in developmental biology and evolution. Hertwig is credited as the first man to observe sexual reproduction by looking at the cells of sea urchins under the microscope. Biography Hertwig was the elder brother of zoologist-professor Richard Hertwig (1850–1937). The Hertwig brothers were the most eminent scholars of Ernst Haeckel (and Carl Gegenbaur) from the University of Jena. They were independent of Haeckel's philosophical speculations but took his ideas in a positive way to widen their concepts in zoology. Initially, between 1879 and 1883, they performed embryological studies, especially on the theory of the coelom (1881), the fluid-filled body cavity. These problems were based on the phylogenetic theorems of Haeckel, i.e. the biogenic theory (German = biogenetisches Grundgesetz), and the " gastraea theory". Within 10 years, the two bro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicola Perscheid
Nicola Perscheid (3 December 1864 – 12 May 1930) was a German photographer. He is primarily known for his artistic portrait photography. He developed the "Perscheid lens", a soft focus lens for large format portrait photography. Life and career Perscheid was born as Nikolaus Perscheid in near Koblenz, German Confederation, where he also went to school. At the age of 15, he began an apprenticeship as a photographer. Subsequently, Perscheid earned his living as an itinerant photographer; he worked, amongst other places, in Saarbrücken, Trier, and Colmar, but also in Nice, Vienna, or Budapest. In Klagenfurt in Austria he finally found a permanent position and on 1 March 1887, he became a member of the Photographic Society of Vienna (''Wiener Photographische Gesellschaft''). In 1889, he moved to Dresden, where he initially worked in the studio of Wilhelm Höffert (1832–1901), a well-known studio in Germany at that time, before opening his own studio in Görlitz on 6 June 1891 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogenic Theory
The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (ontogeny), goes through stages resembling or representing successive adult stages in the evolution of the animal's remote ancestors (phylogeny). It was formulated in the 1820s by Étienne Serres based on the work of Johann Friedrich Meckel, after whom it is also known as Meckel–Serres law. Since embryos also evolve in different ways, the shortcomings of the theory had been recognized by the early 20th century, and it had been relegated to "biological mythology" by the mid-20th century. Analogies to recapitulation theory have been formulated in other fields, including cognitive development and music criticism.Medicus (1992) p.2 quotation: "..many biologists accept the rule with respect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University And State Library Düsseldorf
The University and State Library Düsseldorf (german: Universitäts- und Landesbibliothek Düsseldorf, abbreviated ULB Düsseldorf) is a central service institution of Heinrich Heine University. Along with Bonn and Münster, it is also one of the three State Libraries of North Rhine-Westphalia. Tradition and Modernity From 1965 to 1969, the University and Library Düsseldorf gradually developed out of the Medical Academy in Düsseldorf. There is no real founding year of the ULB, but the foundation stone for an integrated library system was laid when the former State and City Library of Düsseldorf was taken over by the university in 1970 and merged with the Central Library of the former Medical Academy. Structure and Holdings The ULB consists of one central library and four decentralized locations. Management and media processing are organized centrally. Catalogues, databases, e-books and e-journals are accessible throughout the whole university as well as at home via the lib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Swedish Academy Of Sciences
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting natural sciences and mathematics and strengthening their influence in society, whilst endeavouring to promote the exchange of ideas between various disciplines. The goals of the academy are: * to be a forum where researchers meet across subject boundaries, * to offer a unique environment for research, * to provide support to younger researchers, * to reward outstanding research efforts, * to communicate internationally among scientists, * to advance the case for science within society and to influence research policy priorities * to stimulate interest in mathematics and science in school, and * to disseminate and popularize scientific information in various forms. Every year, the academy awards the Nobel Priz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a common ancestor is now generally accepted and considered a fundamental concept in science. In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin has been described as one of the most influential figures in human history and was honoured by burial in Westminster Abbey. Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. His studies at the University of Cambridge's Christ's Col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avery–MacLeod–McCarty Experiment
The Avery–MacLeod–McCarty experiment was an experimental demonstration, reported in 1944 by Oswald Avery, Colin MacLeod, and Maclyn McCarty, that DNA is the substance that causes bacterial transformation, in an era when it had been widely believed that it was proteins that served the function of carrying genetic information (with the very word ''protein'' itself coined to indicate a belief that its function was ''primary''). It was the culmination of research in the 1930s and early 20th century at the Rockefeller Institute for Medical Research to purify and characterize the "transforming principle" responsible for the transformation phenomenon first described in Griffith's experiment of 1928: killed ''Streptococcus pneumoniae'' of the virulent strain type III-S, when injected along with living but non-virulent type II-R pneumococci, resulted in a deadly infection of type III-S pneumococci. In their paper "''Studies on the Chemical Nature of the Substance Inducing Transform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleic Acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). If the sugar is ribose, the polymer is RNA; if the sugar is the ribose derivative deoxyribose, the polymer is DNA. Nucleic acids are naturally occurring chemical compounds that serve as the primary information-carrying molecules in cells and make up the genetic material. Nucleic acids are found in abundance in all living things, where they create, encode, and then store information of every living cell of every life-form on Earth. In turn, they function to transmit and express that information inside and outside the cell nucleus to the interior operations of the cell and ultimately to the next generation of each living organism. The encoded information is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertwig Rule
Hertwig's rule, or the long axis rule states that a cell divides along its long axis. Introduced by the German zoologist Oscar Hertwig in 1884, the rule emphasizes the cell shape as a default mechanism of spindle apparatus orientation. Hertwig's rule predicts cell division orientation, which is important for tissue architecture, cell fate and morphogenesis. Discovery Hertwig's experiments studied the orientation of frog egg divisions. The frog egg has a round shape and the first division occurs in a random orientation. Hertwig compressed the egg between two parallel plates. The compression forced the egg to change its shape from round to elongated. Hertwig noticed that elongated egg divides not randomly, but orthogonally to its long axis. The new daughter cells were formed along the longest axis of the cell. This observation thus became known as 'Hertwig's rule' or 'long axis rule'. Confirmation and mechanism Recent studies in animal and plant systems support the 'long axis rule' ... [...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] |
Nature Reviews Molecular Cell Biology
''Nature Reviews Molecular Cell Biology'' is a monthly peer-reviewed review journal published by Nature Portfolio. It was established in October 2000 and covers all aspects of molecular and cell biology. The editor-in-chief is Kim Baumann. According to the ''Journal Citation Reports'', the journal has a 2021 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as i ... of 113.915, ranking it 1st out of 194 journals in the category "Cell Biology". References External links * Nature Research academic journals Publications established in 2000 Molecular and cellular biology journals Monthly journals English-language journals Review journals {{Molec-cell-biology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Urchin
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of sea urchins are round and spiny, ranging in diameter from . Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals. Sea urchins are also used as food especially in Japan. Adult sea urchins have fivefold symmetry, but their pluteus larvae feature bilateral (mirror) symmetry, indicating that the sea urchin belongs to the Bilateria group of animal phyla, which also comprises the chordates and the arthropods, the annelids and the molluscs, and are found in every ocean and in every climate, from the tropics to the pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Maximilian University
The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Universität München) is a public research university in Munich, Germany. It is Germany's sixth-oldest university in continuous operation. Originally established in Ingolstadt in 1472 by Duke Ludwig IX of Bavaria-Landshut, the university was moved in 1800 to Landshut by King Maximilian I of Bavaria when the city was threatened by the French, before being relocated to its present-day location in Munich in 1826 by King Ludwig I of Bavaria. In 1802, the university was officially named Ludwig-Maximilians-Universität by King Maximilian I of Bavaria in honor of himself and Ludwig IX. LMU is currently the second-largest university in Germany in terms of student population; in the 2018/19 winter semester, the university had a total of 51,606 matriculated students. Of these, 9,424 were freshmen while international students totalled 8,875 or approximately 17% of the student popu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
