Lee Soo Rin, Lee Ji-Hyun, Kim Ah Ran, Kim Sanghee, Park Hyun, Baek Hea Ja, Kim Hyun-Woo
Interdisciplinary program of Biomedical Mechanical & Electrical Engineering, Pukyong National University, Busan, 608-737, South Korea.
Korea Polar Research Institute, Korea Ocean Research and Development Institute, Incheon 406-840, South Korea.
Comp Biochem Physiol B Biochem Mol Biol. 2016 Feb;192:38-48. doi: 10.1016/j.cbpb.2015.11.008. Epub 2015 Nov 25.
Three full-length cDNAs encoding lipoprotein homologs were identified in Tigriopus kingsejongensis, a newly identified copepod from Antarctica. Structural and transcriptional analyses revealed homology with two vitellogenin-like proteins, Tik-Vg1 and Tik-Vg2, which were 1855 and 1795 amino acids in length, respectively, along with a third protein, Tik-MEP, which produced a 1517-residue protein with similarity to a melanin engaging protein (MEP) in insects Phylogenetic analysis showed that Vgs in Maxillopods including two Tik-Vgs belong to the arthropod vitellogenin-like clade, which includes clottable proteins (CPs) in decapod crustaceans and vitellogenins in insects. Tik-MEP clustered together with insect MEPs, which appear to have evolved before the apoB-like and arthropod Vg-like clades. Interestingly, no genes orthologous to those found in the apoB clade were identified in Maxillopoda, suggesting that functions of large lipid transfer proteins (LLTPs) in reproduction and lipid metabolism may be different from those in insect and decapod crustaceans. As suggested by phylogenetic analyses, the two Tik-Vgs belonging to the arthropod Vg-like clade appear to play major roles in oocyte maturation, while Vgs belonging to the apoB clade function primarily in the reproduction of decapod crustaceans. Transcriptional analysis of Tik-Vg expression revealed a 24-fold increase in mature and ovigerous females compared with immature female, whereas expression of Tik-MEP remained low through all reproductive stages. Acute temperature changes did not affect the transcription of Tik-Vg genes, whereas Tik-MEP appeared to be affected by temperature change. Among the three hormones thought to be involved in molting and reproduction in arthropods, only farnesoic acid (FA) induced transcription of the two Tik-Vg genes. Regardless of developmental stage and hormone treatment, Tik-Vg1 and Tik-Vg2 exhibited a strong positive correlation in expression, suggesting that expression of these genes may be regulated by the same transcriptional machinery.
在新发现的来自南极洲的哲水蚤（Tigriopus kingsejongensis）中鉴定出了三个编码脂蛋白同源物的全长cDNA。结构和转录分析显示，其与两种卵黄原蛋白样蛋白Tik-Vg1和Tik-Vg2具有同源性，它们的长度分别为1855和1795个氨基酸，还有第三种蛋白Tik-MEP，它产生了一种1517个残基的蛋白，与昆虫中的黑色素结合蛋白（MEP）相似。系统发育分析表明，包括两个Tik-Vg在内的颚足纲中的Vg属于节肢动物卵黄原蛋白样进化枝，其中包括十足目甲壳类动物中的可凝结蛋白（CP）和昆虫中的卵黄原蛋白。Tik-MEP与昆虫MEP聚集在一起，它们似乎在载脂蛋白B样和节肢动物Vg样进化枝之前就已经进化。有趣的是，在颚足纲中未鉴定出与载脂蛋白B进化枝中发现的基因直系同源的基因，这表明大脂质转运蛋白（LLTP）在繁殖和脂质代谢中的功能可能与昆虫和十足目甲壳类动物不同。正如系统发育分析所表明的，属于节肢动物Vg样进化枝的两个Tik-Vg似乎在卵母细胞成熟中起主要作用，而属于载脂蛋白B进化枝的Vg主要在十足目甲壳类动物的繁殖中起作用。Tik-Vg表达的转录分析显示，成熟雌体和抱卵雌体与未成熟雌体相比增加了24倍，而Tik-MEP在所有生殖阶段的表达都保持较低水平。急性温度变化不影响Tik-Vg基因的转录，而Tik-MEP似乎受温度变化影响。在被认为参与节肢动物蜕皮和繁殖的三种激素中，只有法尼酸（FA）诱导了两个Tik-Vg基因的转录。无论发育阶段和激素处理如何，Tik-Vg1和Tik-Vg2的表达都呈现出强烈的正相关，这表明这些基因的表达可能受相同的转录机制调控。
