Auanema freiburgense is a nematode with males, females, and selfing hermaphrodites. When XO males mate with XX females, they typically produce a low proportion of XO offspring because they eliminate nullo-X spermatids. This process ensures that most sperm carry an X chromosome, increasing the likelihood of X chromosome transmission compared to random segregation. This occurs because of an unequal distribution of essential cellular organelles during sperm formation, likely dependent on the X chromosome. Some sperm components are selectively segregated into the X chromosome's daughter cell, while others are discarded with the nullo-X daughter cell. Intriguingly, the interbreeding of two A. freiburgense strains results in hybrid males capable of producing viable nullo-X sperm. Consequently, when these hybrid males mate with females, they yield a high percentage of male offspring. To uncover the genetic basis of nullo-spermatid elimination and X- chromosome drive, we generated a genome assembly for A. freiburgense, and genotyped the intercrossed lines. This analysis identified a Quantitative Trait Locus spanning several X chromosome genes linked to the non-Mendelian inheritance patterns observed in A. freiburgense. This finding provides valuable clues to the underlying factors involved in asymmetric organelle partitioning during male meiotic division and thus non-Mendelian transmission of the X chromosome and sex ratios.

中文翻译：

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X 染色体 QTL 对 A. freiburgense 中非孟德尔遗传和不平等染色体分离的贡献。

Auanema freiburgense 是一种具有雄性、雌性和自交雌雄同体的线虫。当 XO 雄性与 XX 雌性交配时，它们通常会产生较低比例的 XO 后代，因为它们消除了 nullo-X 精子细胞。这个过程确保大多数精子携带 X 染色体，与随机分离相比，增加了 X 染色体传递的可能性。发生这种情况的原因是精子形成过程中必需细胞器的分布不均，可能取决于 X 染色体。一些精子成分被选择性地分离到 X 染色体的子细胞中，而其他成分则与 nullo-X 子细胞一起被丢弃。有趣的是，两种弗赖堡放线菌菌株的杂交产生了能够产生可行的 nullo-X 精子的杂交雄性。因此，当这些杂交雄性与雌性交配时，它们会产生很高比例的雄性后代。为了揭示无精细胞消除和 X 染色体驱动的遗传基础，我们生成了弗赖堡放线菌的基因组组装，并对杂交品系进行了基因分型。该分析确定了跨越多个 X 染色体基因的数量性状基因座，该基因座与弗莱堡放线菌中观察到的非孟德尔遗传模式相关。这一发现为了解雄性减数分裂过程中细胞器不对称分配的潜在因素以及 X 染色体和性别比例的非孟德尔传递提供了有价值的线索。