间隙基因（gap gene）成对基因（pair-rule gene）节段极性基因（segment polarity gen） 请解释一下

间隙基因（gap gene）成对基因（pair-rule gene）节段极性基因（segment polarity gen） 请解释一下

都是和昆虫体节发育有关的基因。
具体见下面：
A gap gene is a type of gene involved in the development of the segmented embryos of some arthropods. Gap genes are defined by the effect of a mutation in that gene, which causes the loss of contiguous body segments, resembling a gap in the normal body plan.

A pair-rule gene is a type of gene involved in the development of the segmented embryos of insects. Pair-rule genes are defined by the effect of a mutation in that gene, which causes the loss of the normal developmental pattern in alternating segments.

A segmentation gene is a generic term for a gene whose function is to specify tissue pattern in each repeated unit of a segmented organism. In the fruit fly Drosophila melanogaster, segment polarity genes help to define the anterior and posterior polarities within each embryonic parasegment by regulating the transmission of signals via the Wnt signaling pathway and Hedgehog signaling pathway.