Grozeva Snejana, Nokkala Seppo, Simov Nikolay
Institute of Zoology, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel, 1000 Sofia, Bulgaria.
Folia Biol (Krakow). 2006;54(1-2):9-12. doi: 10.3409/173491606777919166.
The karyotype and male meiosis of Macrolophus costalis Fieber (Insecta, Heteroptera, Miridae) were studied using C-banding, AgNOR-banding and DNA sequence specific fluorochrome staining. The chromosome formula of the species is 2n = 28(24+X1X2X3Y). Male meiotic prophase is characterized by a prominent condensation stage. At this stage, two sex chromosomes, "X" and Y are positively heteropycnotic and always appeared together, while in autosomal bivalents homologous chromosomes were aligned side by side along their entire length, that is, meiosis is achiasmatic. At metaphase I, "X" and Y form a pseudobivalent and orient to the opposite poles. At early anaphase I, the "X" chromosome disintegrates into three separate small chromosomes, X1, X2, and X3. Hence both the autosomes and sex chromosomes segregate reductionally in the first anaphase, and separate equationally in the second anaphase. This is the first evidence of sex chromosome pre-reduction in the family Miridae. Data on C-heterochromatin distribution and its composition in the chromosomes of this species are discussed.
利用C带、AgNOR带和DNA序列特异性荧光染色技术，对烟盲蝽（昆虫纲，半翅目，盲蝽科）的核型和雄性减数分裂进行了研究。该物种的染色体公式为2n = 28(24 + X1X2X3Y)。雄性减数分裂前期的特点是有一个明显的浓缩期。在此阶段，两条性染色体“X”和“Y”呈正异固缩，且总是同时出现，而在常染色体二价体中，同源染色体沿其全长并排排列，即减数分裂是交叉消失的。在中期I，“X”和“Y”形成一个假二价体并向相反两极取向。在后期I早期，“X”染色体解体为三个单独的小染色体，X1、X2和X3。因此，常染色体和性染色体在第一次后期都进行减数分离，并在第二次后期进行均等分离。这是盲蝽科中性染色体提前减数的首个证据。讨论了该物种染色体中C-异染色质分布及其组成的数据。
