Laboratório de Fisiologia e Controle de Artrópodes Vetores, IOC, Fiocruz, Rio de Janeiro, RJ 21045-900, Brazil; Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ 20911-270, Brazil.
Laboratório de Fisiologia e Controle de Artrópodes Vetores, IOC, Fiocruz, Rio de Janeiro, RJ 21045-900, Brazil; Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ 20911-270, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ 21941-902, Brazil.
J Insect Physiol. 2014 Mar;62:54-60. doi: 10.1016/j.jinsphys.2014.02.001. Epub 2014 Feb 15.
Given their medical importance, mosquitoes have been studied as vectors of parasites since the late 1800's. However, there are still many gaps concerning some aspects of their biology, such as embryogenesis. The embryonic desiccation resistance (EDR), already described in Aedes and Anopheles gambiae mosquitoes, is a peculiar trait. Freshly laid eggs are susceptible to water loss, a condition that can impair their viability. EDR is acquired during embryogenesis through the formation of the serosal cuticle (SC), protecting eggs from desiccation. Nevertheless, conservation of both traits (SC presence and EDR acquisition) throughout mosquito evolution is unknown. Comparative physiological studies with mosquito embryos from different genera, exhibiting distinct evolutionary histories and habits is a feasible approach. In this sense, the process of EDR acquisition of Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus at 25°C was evaluated. Completion of embryogenesis occurs in Ae. aegypti, An. aquasalis and Cx. quinquefasciatus at, respectively 77.4, 51.3 and 34.3hours after egg laying, Cx. quinquefasciatus embryonic development taking less than half the time of Ae. aegypti. In all cases, EDR is acquired in correlation with SC formation. For both Ae. aegypti and An. aquasalis, EDR and SC appear at 21% of total embryonic development, corresponding to the morphological stage of complete germ band elongation/beginning of germ band retraction. Although phylogenetically closer to Ae. aegypti than to An. aquasalis, Cx. quinquefasciatus acquires both EDR and serosal cuticle later, with 35% of total development, when the embryo already progresses to the middle of germ band retraction. EDR confers distinct egg viability in these species. While Ae. aegypti eggs demonstrated high viability when left up to 72hours in a dry environment, those of An. aquasalis and Cx. quinquefasciatus supported these conditions for only 24 and 5hours, respectively. Our data suggest that serosa development is at least partially uncoupled from embryo development and that, depending upon the mosquito species, EDR bestows distinct levels of egg viability.
鉴于蚊子的医学重要性，自 19 世纪后期以来，它们一直被作为寄生虫的传播媒介进行研究。然而，关于它们的生物学，如胚胎发生等方面仍有许多空白。胚胎干燥耐受性（EDR）已在埃及伊蚊和冈比亚按蚊中描述，是一种特殊的特征。刚产下的卵易失水，这会损害它们的活力。EDR 在胚胎发生过程中通过形成浆膜角质层（SC）获得，从而保护卵免受干燥。然而，蚊子进化过程中这两种特征（SC 存在和 EDR 获得）的保存情况尚不清楚。对具有不同进化历史和习性的不同属蚊子胚胎进行比较生理研究是一种可行的方法。在这个意义上，评估了 25°C 下埃及伊蚊、安蚊 Aquasalis 和库蚊 quinquefasciatus 的 EDR 获得过程。在埃及伊蚊、安蚊 Aquasalis 和库蚊 quinquefasciatus 中，胚胎发生分别在产卵后 77.4、51.3 和 34.3 小时完成，库蚊 quinquefasciatus 的胚胎发育时间不到埃及伊蚊的一半。在所有情况下，EDR 的获得都与 SC 的形成相关。对于埃及伊蚊和安蚊 Aquasalis，EDR 和 SC 出现在胚胎发育的 21%，对应于完全 germ band 伸长/ germ band 收缩开始的形态阶段。尽管库蚊与埃及伊蚊的亲缘关系比安蚊更近，但它获得 EDR 和浆膜角质层的时间较晚，在总发育的 35%时，胚胎已经进入 germ band 收缩的中期。EDR 赋予这些物种不同的卵活力。当埃及伊蚊卵在干燥环境中放置长达 72 小时时，它们表现出高活力，而安蚊 Aquasalis 和库蚊 quinquefasciatus 的卵在干燥环境中只能存活 24 小时和 5 小时。我们的数据表明，浆膜的发育至少部分与胚胎发育分离，并且根据蚊子的种类，EDR 赋予不同水平的卵活力。
