RESUMEN

Segregation distortion (SD) is defined as abnormal segregation ratio of hybrid offsprings at some genetic loci deviating from the Mendelian ratio. SD results from the incompatibility among genes from different parents, which could be due to loss-of-function or gain-of-function gene interactions. The mechanism for loss-of-function SD is relatively simple: defective gene combination leads to loss of the original function and eventual cell death. The gain-of-function hybrid SD system is a multi-gene genetic system, comprising two basic components: the killer and the protector. Additional modifiers, such as enhancers and repressors, are also involved. There is a general genetic model for gain-of-function hybrid SD: haplotypes with transmission advantage possess high-activity killer⁺ and protector⁺; those with transmission disadvantage possess low-activity killer- and protector-; neutral haplotypes (wide compatibility types) possess killer- and protector⁺. Depending upon close linkage between the killer and the protector and the accumulation of modifiers, the SD system survived through natural selection. Although the genetic mechanisms are highly similar, different gain-of-function hybrid SD systems have distinctive molecular mechanisms. In this review, we summarize the genetic and molecular mechanisms of hybrid SD, and the relationship between hybrid SD and hybrid sterility.

Asunto(s)

Segregación Cromosómica , Hibridación Genética , Animales , Drosophila/genética , Humanos , Ratones , Oryza/genética

RESUMEN

Objective:To study the pharmacokinetics,thissue distribution and secretion of nerve growth factor(NGF)in mice.Methods:The conecntration of NGF in various body fluids and tissue were determined by isotope tracer combined SDSPAGE method.Results:The plasma concenmtration-time curve was in accordance with the two-compartment pharmacokinetic model.The elimation half-life(t1/2β)was 3.1.The half-life of distribution(t1/2ka)was 5min.Tpeak was 25 min.AUC was 72.4 mg·kg-1·h-1.The concentrations of NGF were high in thyroid,blood,submaxillary glands,superior cervical ganglion,adrenasl and kidneys.Conclusion:NGF has a wide distribution,high tissue concentrationa nd excrtet mainly through the urine.

RESUMEN

Objective:To study the pharmacokinetics,thissue distribution and secretion of nerve growth factor(NGF)in mice.Methods:The conecntration of NGF in various body fluids and tissue were determined by isotope tracer combined SDSPAGE method.Results:The plasma concenmtration-time curve was in accordance with the two-compartment pharmacokinetic model.The elimation half-life(t1/2β)was 3.1.The half-life of distribution(t1/2ka)was 5min.Tpeak was 25 min.AUC was 72.4 mg·kg-1·h-1.The concentrations of NGF were high in thyroid,blood,submaxillary glands,superior cervical ganglion,adrenasl and kidneys.Conclusion:NGF has a wide distribution,high tissue concentrationa nd excrtet mainly through the urine.