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首页> 外文期刊>Comparative biochemistry and physiology, Part B. Biochemistry & molecular biology >Methyl-branched hydrocarbons,major components of the waxy material coating the embryos of the viviparous cockroach Diploptera punctata
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Methyl-branched hydrocarbons,major components of the waxy material coating the embryos of the viviparous cockroach Diploptera punctata

机译：甲基支链烃，蜡质材料的主要成分，覆盖着胎生蟑螂双翅目（Dipoptera punctata）的胚

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The viviparous cockroach Diploptera punctata carries a wax-coated batch of embryos in a brood sac.When the embryos are expelled into saline,flakes of wax from the surface of the embryos float to the surface.In contrast,embryos of the ovoviviparous species such as Rhyparobia maderae are not nourished by the mother during embryogenesis and do not have a copious waxy coating.As a first step in determining the function of this copious wax layer on the batch of embryos of D.punctata,its composition was compared to that of the waxy material on the outer cuticular surface of the mother (female cuticle) by thin-layer chromatography (TLC) and gas chromatography-mass spectrometry.The major lipid class on the embryos was hydrocarbons with lesser amounts of wax esters and long-chain alcohols.Hydrocarbons from both sources had similar elution times and chemical composition,but were markedly different in the amounts of the major methyl-branched hydrocarbon components.A mixture of 3,X-dimethyl alkanes was 44% of the hydrocarbons on the embryos and was only 29% on the female cuticle.However,trimethylalkanes were only 22% of the hydrocarbons on the embryos and were 34% of the hydrocarbons on the female cuticle.The major hydrocarbons from both sources were mixtures of methyl-branched alkanes with backbones of 33 and 35 carbon atoms.Methyl-branched tritriacontanes were 59% of embryo and 35% of female cuticular hydrocarbons;methyl-branched pentatriacontanes were 19% of embryo and 42% of female hydrocarbons.The difference in proportions of the similar hydrocarbons on the outer cuticular surface of the female and those covering the embryos may suggest that the evolution of copious nutrient secretion for the embryos was accompanied by selection for a mixture of hydrocarbons that prevents water loss by the embryos and protects them against invasion by microorganisms without preventing the movement of nutrient fluid into the embryos.
机译：胎生蟑螂Diploptera punctata在雏囊中载有一批蜡涂的胚。当将胚排入生理盐水中时，蜡从胚表面浮到表面。相反，卵生卵的种如母亲在胚发生过程中不会养育马来杜鹃，并且没有丰富的蜡质涂层。作为确​​定该蜡质层在斑D种子胚胎上的功能的第一步，将其成分与通过薄层色谱法（TLC）和气相色谱质谱法测定母体（女性表皮）外表皮上的蜡质物质。胚胎上的主要脂质类别是碳氢化合物，其中蜡酯和长链醇的含量较少。两种来源的烃具有相似的洗脱时间和化学组成，但主要的甲基支链烃组分的量却明显不同。3，X-二甲基烷烃的混合物s占胚芽碳氢化合物的44％，而女性角质层仅占29％。然而，三甲基链烷烃仅占胚芽碳氢化合物的22％，占女性角质层碳氢化合物的34％。来源是主链分别具有33和35个碳原子的甲基支链烷烃的混合物，甲基支链的Tritriatantanes占胚的59％和雌性表皮碳氢化合物的35％;甲基支链的五碳con烷占胚的19％和母体碳氢化合物的42％。在雌性外表皮表面和覆盖胚胎的表皮表面类似的碳氢化合物比例的差异可能表明，伴随着胚胎丰富养分分泌的演变，伴随着对碳氢化合物混合物的选择，这些混合物可防止胚芽和水分流失。保护它们免受微生物入侵，而又不阻止营养液进入胚胎。

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