関: F1 hybrid

WordNet

preceding all others in time or space or degree; "the first house on the right"; "the first day of spring"; "his first political race"; "her first baby"; "the first time"; "the first meetings of the new party"; "the first phase of his training"
the first or highest in an ordering or series; "He wanted to be the first" (同)number_one
the first element in a countable series; "the first of the month" (同)number_one, number 1
an honours degree of the highest class (同)first-class honours degree
indicating the beginning unit in a series (同)1st
before anything else; "first we must consider the garter snake" (同)firstly, foremost, first of all, first off
the initial time; "when Felix first saw a garter snake" (同)for_the_first_time
ranking above all others; "was first in her class"; "the foremost figure among marine artists"; "the top graduate" (同)foremost, world-class
before another in time, space, or importance; "I was here first"; "lets do this job first"
highest in pitch or chief among parts or voices or instruments or orchestra sections; "first soprano"; "the first violin section"; "played first horn"
a stage of technological development or innovation; "the third generation of computers"
the normal time between successive generations; "they had to wait a generation for that prejudice to fade"
the act of producing offspring or multiplying by such production (同)multiplication, propagation
the production of heat or electricity; "dams were built for the generation of electricity"
group of genetically related organisms constituting a single step in the line of descent
relating to or characteristic of or befitting an offspring; "filial respect"
designating the generation or the sequence of generations following the parental generation
any of various evergreen trees of the genus Abies; chiefly of upland areas (同)fir_tree, true fir
nonresinous wood of a fir tree

PrepTutorEJDIC

(順序・時間的に)『第1の』,1番目の;最初の / (階級・等級・重要度などが)『1番の』,第一級の,首席の,最も重要な / 『最初に』,まっ先に;1番目に,第1位に;初めて / (…するくらいなら)むしろ,いっそ(…のほうがいい)(rather, sooner) / 《通例the~》『最初のもの』;(月の)第1日;(時代の)第1年 / 《通例the~》初め,始まり / 〈U〉ファーストギヤ,低速ギヤ / 〈C〉《英》(競技などの)第1位,1等(試験の)第一級 / 《複数形で》最高級品,一級品 / 〈U〉=first base
〈C〉《the ~》《集合的に》《単数扱い》『同時代の人人』,[同]世代 / 〈C〉〈U〉(家の)『一代』 / 〈C〉世代(ある代の出生から次の代の出生までの期間,約30年) / 〈U〉(電気などの)『発生』,生成《+『of』+『名』》
子としての,子にふさわしい
モミ,モミの木(クリスマスツリーに用いられる) / モミ材

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/11/15 18:07:04」(JST)

wiki en

F1 hybrid is a term used in genetics and selective breeding. F1 stands for Filial 1, the first filial generation seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types.^[1] The term is sometimes written with a subscript, as F₁ hybrid.^[2]^[3] The offspring of distinctly different parental types produce a new, uniform variety with specific characteristics from either or both parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics those parents usually are two inbred lines. Mules are F1 hybrids between horse and donkey. Today, certain domestic hybrid breeds, such as the Savannah cat, are classified by their filial generation number.

Gregor Mendel's groundbreaking work in the 19th century focused on patterns of inheritance and the genetic basis for variation. In his cross-pollination experiments involving two true-breeding, or homozygous, parents, Mendel found that the resulting F1 generation were heterozygous and consistent. The offspring showed a combination of those phenotypes from each of the parents that were genetically dominant. Mendel’s discoveries involving the F1 and F2 generation laid the foundation for modern genetics.

Production of F1 hybrids

In plants

Crossing two genetically different plants produces a hybrid seed (plant). This can happen naturally, and includes hybrids between two different species (for example, peppermint is a sterile F1 hybrid of watermint and spearmint). In agronomy, the term “F1 hybrid” is usually reserved for agricultural cultivars derived from two different parent cultivars. These F1 hybrids are usually created by means of controlled pollination, sometimes by hand-pollination. For annual plants such as tomato "hybrids" and "hybrid inbred maize, F1 hybrids must be produced each season.

For mass-production of F1 hybrids with uniform phenotype, the parent plants must have predictable genetic effects on the offspring. Inbreeding and selection for uniformity for a number of generations ensures that the parent lines are almost homozygous. The divergence between the parent lines promotes improved growth and yield characteristics in the F1 offspring through the phenomenon of heterosis ("hybrid vigour").

Two populations of breeding stock with desired characteristics are subject to inbreeding until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations. After this happens, both populations must be crossed while avoiding self-fertilization. Normally this happens in plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating.^[4]

In 1960, 99 percent of all corn planted in the United States, 95 percent of sugar beet, 80 percent of spinach, 80 percent of sunflowers, 62 percent of broccoli, and 60 percent of onions were hybrid. Such figures are probably higher today. Beans and peas are not commercially hybridized because they are automatic pollinators, and hand-pollination is prohibitively expensive.

F2 hybrid

While an F2 hybrid, the result of self or cross pollination of an F1, does not have the consistency of the F1 hybrid, it may retain some desirable traits and can be produced more cheaply as no intervention in the pollination is required. Some seed companies offer F2 seed, particularly in bedding plants where consistency is not as critical.^[5]

In animals

F1 crosses in animals can be between two inbred lines or between two closely related species or subspecies, where such crosses are possible. In some fish, such as cichlids, the term F1 cross is used for crosses between two different individuals known to have been collected from the wild, and therefore assumed to be from different genetic lines.^[6]

Advantages

Homogeneity and predictability - If the parents are homozygous pure lines, there is limited genetic variation between individual F1 plants or animals. This makes their phenotype extremely uniform and thus attractive for mechanical operations and makes it easier to fine-tune the management of the population. Once the characteristics of the cross are known, repeating this cross will yield exactly the same result.
Higher performance - As most alleles code for different versions of a protein or enzyme, having two different versions of this allele amounts to having two different versions of the enzyme. This will increase the likelihood of having an optimal version of the enzyme present and reduce the likelihood of a genetic defect. This effect is referred to in genetics as heterosis.
F1 hybrids can give higher yields than traditional varieties.

Disadvantages

The main advantage of F1 hybrids in agriculture is also their drawback. When F1 cultivars are used for the breeding of a new generation, their offspring (F2 generation) will vary greatly from one another. Some of the F2 generation will be high in homozygous genes, as found in the weaker parental generation, and these will have a depression in yield and lack the hybrid vigour. From the point of view of a commercial seed producer which does not wish its customers to produce their own seed, this genetic assortment is a desired characteristic.
Both inbreeding and crossing the lines requires a lot of work, which translates into a much higher seed cost. In general, the higher yield offsets this disadvantage.
F1 hybrids mature at the same time when raised under the same environmental conditions. This is of interest for modern farmers, because all ripen at the same time and can be harvested by machine. Traditional varieties are often more useful to gardeners because they crop over a longer period of time, avoiding gluts and food shortages.

References

^ Marschall S. Runge and Cam Patterson (editors) (2006). Principles of Molecular Medicine. Humana Press. p. 58. ISBN 978-1-58829-202-5. http://books.google.com/books?id=j-_rAKRf3WwC&pg=PA58&dq=%22Filial+1%22+%22F1+hybrid%22.
^ Peter Abramoff and Robert G. Thomson (1994). Laboratory Outlines in Biology--VI. Macmillan. p. 497. ISBN 978-0-7167-2633-3. http://books.google.com/books?id=Is4whaGN1V8C&pg=PA497&dq=%22Filial+1%22+%22hybrid%22.
^ William Ernest Castle and Gregor Mendel (1922). Genetics and eugenics: a text-book for students of biology and a reference book for animal and plant breeders. Harvard University Press. p. 101. http://books.google.com/books?id=HtZpAAAAMAAJ&pg=PA101&dq=Filial+subscript#PPA101,M1.
^ http://tomclothier.hort.net/seedsav4.html
^ Lawrence D. Hills 1987. F2 and open pollinated varieties. Growing From Seed (The Seed Raising Journal from Thompson & Morgan) 1(2) [1]
^ "Guide to selecting and breeding high quality cichlids". bigskycichlids.com. http://www.bigskycichlids.com/newfish_articlex.htm.

Hand pollination
USDA, Seeds: The Yearbook of Agriculture, 1961.

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English Journal

Lactational exposure of phthalate causes long-term disruption in testicular architecture by altering tight junctional and apoptotic protein expression in Sertoli cells of first filial generation pubertal Wistar rats.

Sekaran S, Balaganapathy P, Parsanathan R, Elangovan S, Gunashekar J, Bhat F, Jagadeesan A.
Human & experimental toxicology.Hum Exp Toxicol.2014 Oct 28. pii: 0960327114555926. [Epub ahead of print]
Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental contaminant and a well-known endocrine disruptor (ED) that interferes with the reproductive function in both humans and animals. This study aimed to find out the impact of lactational exposure of DEHP in testes of first filial generatio
PMID 25352649

Inducible costimulator gene transduced bone marrow derived mesenchymal stem cells attenuate the severity of acute graft-versus-host disease in mouse models.

Yang D, Wang LP, Zhou H, Cheng H, Bao XC, Xu S, Zhang WP, Wang JM.
Cell transplantation.Cell Transplant.2014 Sep 8. [Epub ahead of print]
In allogeneic transplantation murine models, ICOS gene transduced bone marrow derived mesenchymal stem cells (MSC-ICOS-EGFP) were evaluated for their effects on GvHD severity and long-term survival. Lethally irradiated BALB/c or first filial generation of BALB/c and C57BL/6 (CB6F1) mice were transpl
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Growth performance of crossbred naked neck and normal feathered birds.

Adomako K1, Olympio OS, Hagan JF, Hamidu JA.
British poultry science.Br Poult Sci.2014 Sep 5. [Epub ahead of print]
Abstract 1. Two experiments were conducted to develop naked neck (Na/na) and normal feathered (na/na) crossbreds and compare their growth performance, linear body measurements and carcass characteristics in the first and second filial generations. 2. In the first experiment, 4 indigenous naked neck
PMID 25192492

Japanese Journal

トミヨ保護池におけるトミヨ属Pungitius淡水型と雄物型の交雑

河又邦彦,杉山秀樹,丸山涼子 [他],冨田多美,江戸三恵子,武田舞,新田宏宇
秋田大学教育文化学部研究紀要. 自然科学 68, 31-36, 2013-03-31
… In 2001, it was confirmed that there were first filial hybrid (F_1 hybrid) between Omono and Fresh-water types. … Although it was possible that third filial generation was exist at least, it was unclear about forth and later filial generation by the limit of isozime analysis. …
NAID 110009560986

トルコギキョウの野生種の特性と新品種の育成--F1系統の形質発現と優良F1系統の特性

渡邉英城
大分県農林水産研究センター研究報告農業編 (3), 75-84, 2009-03
1994年にアメリカ合衆国で収集したトルコギキョウの野生種と当研究所保有系統との交雑により得られた系統を用いて、F1品種の育種に取り組み、固定系統とF1系統の関係、優良なF1系統の栽培特性について検討した。1．F1系統での花色・覆輪・微細斑の発現について、以下のことが明らかになった。1）当研究所保有固定系統の白色系統に、可視光下で区別できない覆輪花系統が混在する可能性が高い。2）覆輪花において花色 …
NAID 40016784795