Honnen Ann-Christin, Johnston Paul R, Monaghan Michael T
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587, Berlin, Germany.
Freie Universität Berlin, Königin-Luise-Straße 1-3, 14195, Berlin, Germany.
BMC Genomics. 2016 Jan 5;17:22. doi: 10.1186/s12864-015-2336-0.
Artificial light at night (ALAN) is a typical feature of urban areas and most organisms living in urban or suburban habitats are exposed to low levels of ALAN. Light is one of the most important environmental cues that organisms use to regulate their activities. Studies have begun to quantify the influence of ALAN on the behavior and ecology of organisms, but research on the effects at the molecular level remains limited. Mosquitoes in the Culex pipiens complex (Diptera, Culicidae) are widespread and abundant in urban areas where they are potential disease vectors. It is thus of particular interest to understand how ALAN may influence biologically and ecologically relevant traits.
We used RNAseq to evaluate the transcriptome response in a Cx. pipiens f. molestus laboratory population that was exposed to near-natural light conditions (light:dark L16:D8 hours, "control") and ALAN conditions with 3 h of constant low-level light at night (L16 + Llow3:D5 hours, "low-light"). The resulting transcripts were mapped to the reference genome of the closely related Culex quinquefasciatus. Female expression patterns differed significantly between control and treatment conditions at five genes although none showed an absolute fold change greater than two (FC > 2). In contrast, male expression differed at 230 genes (74 with FC > 2). Of these, 216 genes (72 with FC > 2) showed reduced expression in the low-light treatment, most of which were related to gametogenesis, lipid metabolism, and immunity. Of the 14 genes (two with FC > 2) with increased expression, only five had any functional annotation. There was a pronounced sex-bias in gene expression regardless of treatment, with 11,660 genes (51 % of annotated genes; 8694 with FC > 2; 48 % of annotated genes) differentially expressed between males and females, including 14 genes of the circadian clock.
Our data suggest a stronger response to artificial light by males of Cx. pipiens f. molestus than by females, and that a wide range of physiological pathways may be affected by ALAN at the molecular level. The fact that differences in gene expression appear to be sex-specific may have a strong influence at the population level.
夜间人工光照（ALAN）是城市地区的一个典型特征，大多数生活在城市或郊区栖息地的生物都会接触到低水平的ALAN。光是生物体用来调节其活动的最重要的环境线索之一。研究已经开始量化ALAN对生物体行为和生态的影响，但在分子水平上的影响研究仍然有限。尖音库蚊复合组（双翅目，蚊科）中的蚊子在城市地区广泛分布且数量众多，它们是潜在的疾病传播媒介。因此，了解ALAN如何影响生物学和生态学相关特征特别重要。
我们使用RNA测序来评估尖音库蚊致倦亚种实验室种群在接近自然光照条件（光照：黑暗L16:D8小时，“对照”）和夜间有3小时持续低水平光照的ALAN条件（L16 + L低3:D5小时，“低光照”）下的转录组反应。所得转录本被映射到密切相关的致倦库蚊的参考基因组上。在五个基因上，对照和处理条件下雌性的表达模式有显著差异，尽管没有一个基因的绝对折叠变化大于两倍（FC > 2）。相比之下，雄性在230个基因上表达不同（74个基因FC > 2）。其中，216个基因（72个基因FC > 2）在低光照处理中表达降低，其中大多数与配子发生、脂质代谢和免疫有关。在表达增加的14个基因（两个基因FC > 2）中，只有五个有任何功能注释。无论处理如何，基因表达都存在明显的性别偏向，雄性和雌性之间有11,660个基因（占注释基因的51%；8694个基因FC > 2；占注释基因的48%）差异表达，包括14个生物钟基因。
我们的数据表明，尖音库蚊致倦亚种雄性对人工光照的反应比雌性更强，并且在分子水平上，广泛的生理途径可能受到ALAN的影响。基因表达差异似乎具有性别特异性这一事实可能在种群水平上有很大影响。
