Ayayee Paul, Rosa Cristina, Ferry James Gregory, Felton Gary, Saunders Mike, Hoover Kelli
Department of Evolution, Ecology and Organismal Biology, the Ohio State University, Columbus, OH 43210, USA.
Environ Entomol. 2014 Aug;43(4):903-12. doi: 10.1603/EN14045. Epub 2014 Jun 16.
Xylophagous insects often thrive on nutritionally suboptimal diets through symbiotic associations with microbes that supplement their nutritional requirements, particularly nitrogen. The wood-feeding cerambycid Anoplophora glabripennis (Motschulsky) feeds on living, healthy host trees and harbors a diverse gut microbial community. We investigated gut microbial contributions to larval nitrogen requirements through nitrogen fixing and recycling (urea hydrolysis) processes, using a combination of molecular, biochemical, and stable isotope approaches. Genes and transcripts of conserved regions of the urease operon (ureC) and nitrogen fixing (nif) regulon (nifH) were detected in A. glabripennis eggs and larvae from naturally infested logs and from larvae reared on artificial diet. Significant nitrogen fixation and recycling were documented in larvae using (15)N2 gas and (15)N-urea, respectively. Subsequent (15)N-routing of incorporated recycled nitrogen into larval essential and nonessential amino acids was shown for (15)N-urea diet-fed larvae. Results from this study show significant gut microbial contributions to this insect's metabolic nitrogen utilization through nitrogenous waste product recycling and nitrogen fixation.
食木昆虫通常通过与微生物的共生关系在营养欠佳的食物上茁壮成长，这些微生物能补充它们的营养需求，尤其是氮。以木材为食的天牛科昆虫光肩星天牛（Anoplophora glabripennis (Motschulsky)）以健康的活寄主树为食，并拥有多样的肠道微生物群落。我们结合分子、生化和稳定同位素方法，通过固氮和氮循环（尿素水解）过程，研究了肠道微生物对幼虫氮需求的贡献。在取自自然感染原木的光肩星天牛卵和幼虫以及在人工饲料上饲养的幼虫中，检测到了脲酶操纵子（ureC）保守区域和固氮（nif）调节子（nifH）的基因和转录本。分别使用(^{15}N_2)气体和(^{15}N) - 尿素记录了幼虫显著的固氮和氮循环情况。对于用(^{15}N) - 尿素饲料喂养的幼虫，显示了随后将掺入的循环氮(^{15}N)分配到幼虫必需和非必需氨基酸中的情况。这项研究的结果表明，肠道微生物通过含氮废物的循环利用和固氮作用，对这种昆虫的代谢氮利用有显著贡献。
