(n.) The number four; a collection of four things; a quaternion.
(n.) A tetravalent or quadrivalent atom or radical; as, carbon is a tetrad.
Example Sentences:
(1) A constellation of histologic lesions was identified in brain (diffuse meningoencephalitis with bilaterally symmetrical thalamic necrosis), liver (pericholangiohepatitis), lung (pneumonitis), and spleen (lymphoid hyperplasia); this tetrad is apparently unique to this model system.
(2) Optimal formation of complete tetrads occurred at a narrow range of pH values around 6.0.
(3) Tetrad dissection of sporulated diploids heterozygous for the wild-type and mutant allele resulted in a 2:2 segregation of mutant and wild-type phenotype indicating a single gene mutation.
(4) Increased nondisjunction is reflected by a marked increase in tetrads with two and zero viable spores.
(5) At each of these synaptic sites, L1 and L2 are invariable contributors to two of the four elements of a postsynaptic tetrad.
(6) Each glandular unit originates from an isogenic group of cells of which the four elements (tetrade) are disposed on two levels.
(7) A possibility to construct a genetic map of the yeast Pichia pinus MH4 is demonstrated on the basis of tetrad analysis.
(8) 74 of the patients showed acne conglobata, 12 acne tetrade, 11 acne fulminans, and 69 acne papulopustulosa.
(9) The mutations were assigned to specific chromosomes by chromosome loss procedures, and linkage relationships were determined subsequently by standard tetrad analysis.
(10) We used the telomeric repeat of Chlamydomonas reinhardtii, TTTTAGGG, which contains 3 guanines and has a long interguanine A + T tract, to determine whether these sequences can form intrastrand and interstrand guanine tetrads.
(11) The possibility that extragenic suppressors account for growth of clathrin-deficient cells was examined by deletion of CHC1 from haploid cell genomes by single-step gene transplacement and independently by introduction of a centromere plasmid carrying the complete CHC1 gene into diploid cells before eviction of a chromosomal CHC1 locus and subsequent tetrad analysis.
(12) The article generalizes the experience in surgical treatment of Fallot's tetrad in 20 infants.
(13) With respect to behavior, the resulting compounds appeared, presumably as a consequence of their singular generation, to contain an interstitial heterochromatic region that caused the distribution of exchanges between the elements of the compound to be abnormal (many zero and two-exchange tetrads with few, if any, single-exchange tetrads).
(14) Tetrad analysis showed the two suppressors were located about 10 map units apart, the missense suppressor being the more distal to the centromere.
(15) Defective proteinase B activity segregates 2:2 in meiotic tetrads.
(16) Fine genetic mapping was carried out by conventional tetrad analysis using the integrated LEU2 gene as a marker.
(17) Evidence for a centromeric effect on NRD was obtained, suggested by a negative correlation between the degree of NRD, c, and the distance between the region of exchange and the centromere as inferred from SET's (single exchange tetrads).
(18) Allelism tests and tetrad analysis clearly proved that the cat4 complementation group is a new class of mutant alleles affecting carbon source-dependent gene expression.
(19) In isosequential crosses, 90-95% of tetrads are 8:0.
(20) The distinguishing criteria are: lack of pigment in infected red blood cells; no circulating schizonts or gametocytes; "atypical" malarialike organisms; tetrad groups, rods, or exclamation-mark forms; and persisting parasitemia after treatment for malaria.