bivalent


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

bivalent

 [bi-va´lent]
the structure formed by a pair of homologous chromosomes joined by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase. After each homologous chromosome splits into two sister chromatids during the pachytene stage, this structure is called a tetrad.

bi·va·lent

(bī-vā'lent, biv'ă-lent),
1. Having a combining power (valence) of 2.
See also: tetrad. Synonym(s): divalent
2. In cytology, a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.
See also: tetrad.

bivalent

/bi·va·lent/ (bi-va´lent)
2. the structure formed by a pair of homologous chromosomes by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase.

bivalent

(bī-vā′lənt)
adj.
1. Genetics Relating to or being a pair of homologous, side-by-side chromosomes, especially during meiosis; double.
2. Chemistry & Immunology Divalent.

bi·va′lence, bi·va′len·cy n.

bivalent

[bīvā′lənt]
Etymology: L, bis + valere, to be powerful
1 See divalent. (in genetics) a pair of synapsed homologous chromosomes that are attached to each other by chiasmata during the early first meiotic prophase of gametogenesis. The structure serves as the basis for the tetrads from which gametes are produced during the two meiotic divisions.
2 See valence, def. 1. bivalence, n.

bivalent

Chemistry
adjective Referring to an atom with 2 valent states.
 
Genetics
adjective Referring to either of 2 homologous chromosomes in synapsis during meiosis.

bi·va·lent

(bī-vā'lĕnt)
1. Having a combining power (valence) of two.
Synonym(s): divalent.
2. cytology a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.

bivalent

(of a pair of homologous CHROMOSOMES) being paired during prophase I of MEIOSIS. Compare MULTIVALENT.

bivalent

1. having a valence of two.
2. denoting homologous chromosomes associated in pairs during the first meiotic prophase.
References in periodicals archive ?
Lonky: Why would a clinician choose a bivalent vaccine when the quadrivalent vaccine protects not only against carcinogenic types 16 and 18, but also against HPV-associated genital warts?
Among the species used for this purpose, a special interest in the cytogenetics of the genus Stethophyma (previously named Mecostethus) arose from three main fascinating characteristics: i) the tendency for chiasmata to occur close to the centomeric regions in most bivalents (Darlington 1932; White 1936; Shaw 1970, 1971a; Jones 1971, 1973); ii) occurrence of ditactic bivalents (McClung 1928; White 1951, 1973; Shaw 1970, 1971a); iii) extended polymorphisms with respect to supernumerary heterochromatic segments, in addition to a marked interpopulation variation for standard heterochromatin in a number of autosomes (McClung 1928; Carothers 1931; Shaw 1970, 1971a; Jones 1971; Santos unpub.
Frank DeStefano of the CDC's immunization safety office said that post-marketing safety surveillance studies would be conducted on the bivalent HPV vaccine using the Vaccine Adverse Event Reporting System (VAERS), including a study to look at pregnancy outcomes after vaccination with the bivalent vaccine.
After pachytene, bivalents have no chiasma; homologous chromosomes lie parallel to each other, and condense gradually during prophase I and metaphase I.
Usually, when m chromosomes are present, the X and Y form part of the ring of the autosomal bivalents at first metaphase, and the m pseudobivalent lies in its centre.
Extended follow-up data for the bivalent HPV vaccine (HPV 16/18) also provide information on long-term effectiveness, safety, and immunogenicity.
Children vaccinated outside the United States with bivalent vaccine, including immigrants and refugees, will need to be revaccinated.
An innovative approach to develop a simple and practical method to release bivalent ions in a controlled way, without adding any additional compound, was presented [10].
Vaccination with the bivalent vaccine against HPV 16 and 18 (Cervarix, GlaxoSmithKline (GSK)) may prevent cervical, vulval and some anal cancers; vaccination with the quadrivalent vaccine (Gardasil, Merck) may prevent those conditions plus warts.
Among the cancers attributable to HPV between 2008 and 2012, about 80 percent were linked to HPV strains that can be prevented by bivalent, quadrivalent or ninevalent HPV vaccines.
Summary: Reduction of nitro compounds to the corresponding amines has been carried out efficiently with NaBH4 in the presence of bis-thiourea complexes of bivalent cobalt, nickel, copper and zinc chlorides, [MII(tu)2Cl2].
Groups vaccinated with inactivated Newcastle Disease vaccine and bivalent vaccine (containing Newcastle Disease Virus and Avian Influenza Virus) provided 90 to 100% protection following challenge with vvNDV.