Pagone Viviana, Pujal David, Maestro José Luis
Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona, Spain.
PLoS One. 2025 Aug 19;20(8):e0329852. doi: 10.1371/journal.pone.0329852. eCollection 2025.
The insulin-IGF-signalling (IIS) pathway plays crucial roles in animal physiology. In insects, this pathway uses multiple ligands, insulin-like peptides (ILPs), and a smaller number of insulin receptors (InRs). Consequently, much of the regulation of IIS pathway activity is driven by the expression of ILPs, its timing, tissue specific expression, and mode of action: endocrine, paracrine, or autocrine. In the adult male of the cockroach Blattella germanica, tissue expression and the regulation in relation to food restriction of the ILPs BgILP1-7 is similar to that observed in females. However, we identified the expression of BgILP8, an ILP absent in females, in the conglobate gland of males and only in this organ. BgILP8 expression in the conglobate gland is high during the initial days of adulthood and is reduced under starvation. The conglobate gland is a male sexual gland specific to cockroaches, involved in spermatophore formation. It consists of branches of coiled tubules that merge into a main collecting tubule, which opens into the ejaculatory duct. Each tubule is lined with a layer of secretory cells, each of them traversed by small ductules made of cuticle and actin fibers, through which the secretions are released. Decreasing BgILP8 levels through RNAi resulted in a reduction in the size of secretory cells, although the total protein extracted remained unaffected. A comparison of the transcriptomes of control and BgILP8-depleted glands revealed only small differences. Further, comparing genes expressed in the conglobate gland to those expressed in adult females provided a list of putative conglobate gland-specific genes. Our results suggest that BgILP8 plays a role in the development of the conglobate gland. However, a potential function in other male organs or its possible transfer to the female in the copulation cannot be ruled out.
胰岛素-IGF信号传导（IIS）通路在动物生理学中起着至关重要的作用。在昆虫中，该通路使用多种配体，即胰岛素样肽（ILP），以及数量较少的胰岛素受体（InR）。因此，IIS通路活性的大部分调节是由ILP的表达、其时间、组织特异性表达以及作用方式驱动的：内分泌、旁分泌或自分泌。在德国小蠊的成年雄性中，ILP BgILP1 - 7的组织表达以及与食物限制相关的调节与在雌性中观察到的相似。然而，我们在雄性的球腺中且仅在该器官中鉴定出了雌性中不存在的ILP BgILP8的表达。球腺中BgILP8的表达在成年初期较高，在饥饿状态下会降低。球腺是蟑螂特有的雄性性腺，参与精荚的形成。它由盘绕的小管分支组成，这些分支汇入一条主要的收集小管，该收集小管通向射精管。每个小管内衬有一层分泌细胞，每个分泌细胞都有由角质层和肌动蛋白纤维构成的小导管穿过，分泌物通过这些小导管释放。通过RNA干扰降低BgILP8水平导致分泌细胞大小减小，尽管提取的总蛋白不受影响。对照腺和BgILP8缺失腺的转录组比较仅显示出微小差异。此外，将球腺中表达的基因与成年雌性中表达的基因进行比较，得到了一份假定的球腺特异性基因列表。我们的结果表明BgILP8在球腺的发育中起作用。然而，不能排除其在其他雄性器官中的潜在功能或在交配过程中向雌性转移的可能性。
