Dhammi Anirudh, Bissinger Brooke, Ponnusamy Loganathan, Sonenshine Daniel E, Roe R Michael
Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA.
Insects. 2025 Mar 25;16(4):343. doi: 10.3390/insects16040343.
The insect molting process is critical to growth and development and is regulated in part by the neuropeptides corazonin, eclosion hormone, and α and β bursicon. We found messages in a synganglion transcriptome from adult, female American dog ticks, (that do not molt), with a high similarity to the larval insect neuropeptides that control molting. The phylogenetic analysis of the tick putative neuropeptides compared to other arthropods is discussed in detail. The relative gene expression of these peptides was determined by quantitative PCR during the following adult developmental stages: (i) virgin, unfed 0-24 h after entering the adult stage (non-host-seeking), (ii) host-seeking, unfed, and not mated (3 d after emergence), (iii) part-fed (unmated, attached to host; 1st and 3rd day after emergence), (iv) mated (females are part-fed; allowed to mate for ≤1 day, 7th day after emergence), (v) mated repletes (completion of blood feeding but still attached to host), and (vi) post-drop-off (from host) with egg laying starting within 1 d of detachment. Eclosion hormone transcript levels peaked at mating and at drop-off. Bursicon α levels were highest just after molting into adults, with a second smaller peak in replete females. Bursicon β levels were highest (32-fold) post-drop-off. Corazonin message levels peaked in part-feds and were much higher (40-fold) in repletes compared to 0-24 h after emergence. RNAi suppression of the corazonin message by injection in newly molted ticks reduced oviposition and the number of vitellogenic eggs in the ovaries at drop-off but had no apparent effect on host-seeking, partial feeding, mating, feeding to repletion, and drop-off. The possible roles of these transcripts in adult, female tick development are discussed.
昆虫蜕皮过程对其生长和发育至关重要，部分受神经肽促心肽、羽化激素以及α和β羽化肽调控。我们在成年雌性美洲犬蜱（不蜕皮）的交感神经节转录组中发现了与控制昆虫蜕皮的幼虫神经肽高度相似的信息。详细讨论了蜱类假定神经肽与其他节肢动物的系统发育分析。通过定量PCR测定了这些肽在以下成年发育阶段的相对基因表达：（i）刚进入成年阶段（非寻找宿主）0 - 24小时的未进食处女蜱，（ii）寻找宿主、未进食且未交配的蜱（羽化后3天），（iii）部分进食的蜱（未交配，附着于宿主；羽化后第1天和第3天），（iv）交配后的蜱（雌性部分进食；允许交配≤1天，羽化后第7天），（v）饱血交配后的蜱（完成吸血但仍附着于宿主），以及（vi）脱落后（从宿主身上脱落）且在脱落1天内开始产卵的蜱。羽化激素转录水平在交配和脱落后达到峰值。羽化肽α水平在刚蜕皮成为成虫后最高，饱血雌性蜱中有第二个较小的峰值。羽化肽β水平在脱落后最高（高32倍）。促心肽信息水平在部分进食的蜱中达到峰值，与羽化后0 - 24小时相比，饱血蜱中的水平要高得多（高40倍）。通过向新蜕皮的蜱注射RNA干扰抑制促心肽信息，减少了脱落后的产卵量以及卵巢中卵黄生成卵的数量，但对寻找宿主、部分进食、交配、吸血至饱血以及脱落没有明显影响。讨论了这些转录本在成年雌性蜱发育中的可能作用。
