Werren John H, Stouthamer Richard
Department of Biology, University of Rochester, Rochester, NY 14627, USA.
Genetica. 2003 Jan;117(1):85-101. doi: 10.1023/a:1022368700752.
PSR (paternal sex ratio) chromosomes are a type of supernumerary (or B) chromosomes that occur in haplodiploid arthropods. They are transmitted through sperm but then cause loss of the paternal chromosomes (except themselves) early in development. As a result, PSR chromosomes convert diploid fertilized eggs (which would normally develop into females) into haploid males that carry a PSR chromosome. Because they act by completely eliminating the haploid genome of their 'hosts', PSR chromosomes are the most extreme form of selfish or parasitic DNA known. PSR was originally described in the parasitic wasp Nasonia vitripennis (Pteromalidae). A second PSR chromosome has been found in Trichogrimmna kaykai, an egg parasitoid from a different family of Hymenoptera (Trichogrammatidae). We argue that PSR chromosomes are likely to be widespread in haplodiploid organisms, but have so far gone under reported due to a paucity of population genetic studies in haplodiploids. We describe the two known PSR systems and related phenomena, and models indicating the conditions conducive to increase of PSR like chromosomes in haplodiploids.
父本性别比（PSR）染色体是一类存在于单双倍体节肢动物中的超数染色体（即B染色体）。它们通过精子传递，但随后会在发育早期导致父本染色体（自身除外）丢失。结果，PSR染色体将二倍体受精卵（通常会发育成雌性）转化为携带PSR染色体的单倍体雄性。由于它们通过完全消除其“宿主”的单倍体基因组来发挥作用，PSR染色体是已知的自私或寄生DNA的最极端形式。PSR最初是在寄生蜂丽蝇蛹集金小蜂（金小蜂科）中被描述的。在凯氏三棒小蜂中发现了第二条PSR染色体，凯氏三棒小蜂是膜翅目另一个科（赤眼蜂科）的卵寄生蜂。我们认为PSR染色体可能在单双倍体生物中广泛存在，但由于单双倍体群体遗传学研究匮乏，迄今为止尚未得到充分报道。我们描述了两个已知的PSR系统及相关现象，以及表明有利于单双倍体中类似PSR染色体增加的条件的模型。
