Himmel David, Maurin Leslie Candice, Gros Olivier, Mansot Jean-Louis
GTSI - Université des Antilles et de la Guyane, UFR des Sciences Exactes et Naturelles, Département de Physique. B.P. 592. 97159 Pointe-à-Pitre Cedex, Guadeloupe, France.
Biol Cell. 2009 Jan;101(1):43-54. doi: 10.1042/BC20080051.
Marine nematodes belonging to the Stilbonematidae (Desmodoridae) family are described as living in obligatory association with sulfur-oxidizing chemoautotrophic ectosymbionts. The symbiotic bacteria carrying out this chemosynthesis should contain elemental sulfur in periplasmic granules as sulfur granules of chemoautotrophic endosymbionts described in various marine invertebrates.
Based on TEM (transmission electron microscopy) analyses, extracellular bacteria surrounding Eubostrichus dianae possess these spherical periplasmic granules. Few investigative techniques can be used to identify elemental sulfur, S(8), such as EDXS (energy dispersive X-ray spectroscopy) and EELS (electron energy loss spectroscopy), which are associated with cryo-fixation of the sample to avoid sulfur loss. These techniques are time consuming, expensive and require technical skills. Raman microspectrometry applied to the analysis of E. dianae allowed us to detect elemental sulfur, S8, and confirmed the location of these sulfur clusters in the bacterial coat. In the same way, Raman spectrometry was positively applied to the endosymbiotic bivalve Codakia orbicularis, suggesting that this technique can be used to characterize sulfur in ecto- as well as in endo-symbiotic sulfur-oxidizing bacteria.
As Raman spectrometry can be used on living organisms (without preliminary fixation) without sample damage and preserving the molecular structure of the sulfur (denatured during chemical fixation), it represents a very well-adapted investigative tool for biologists. This technique therefore permits us to detect quickly and easily (in a few seconds and on entire living animals) the presence of sulfur compounds in the symbiotic nematode.
属于Stilbonematidae（Desmodoridae）科的海洋线虫被描述为与硫氧化化学自养外共生体形成 obligatory 关联生活。进行这种化学合成的共生细菌应在周质颗粒中含有元素硫，如同在各种海洋无脊椎动物中描述的化学自养内共生体的硫颗粒一样。
基于透射电子显微镜（TEM）分析，围绕戴安娜真刺线虫（Eubostrichus dianae）的细胞外细菌具有这些球形周质颗粒。很少有研究技术可用于鉴定元素硫S(8)，例如能量色散X射线光谱法（EDXS）和电子能量损失光谱法（EELS），这些方法与样品的冷冻固定相关联以避免硫损失。这些技术耗时、昂贵且需要技术技能。应用于戴安娜真刺线虫分析的拉曼显微光谱法使我们能够检测到元素硫S8，并确认了这些硫簇在细菌包膜中的位置。同样，拉曼光谱法成功应用于内共生双壳贝类圆蛤（Codakia orbicularis），表明该技术可用于表征外共生和内共生硫氧化细菌中的硫。
由于拉曼光谱法可用于活体生物（无需预先固定），不会对样品造成损害并保留硫的分子结构（在化学固定过程中会变性），它是一种非常适合生物学家的研究工具。因此，这项技术使我们能够快速轻松地（在几秒钟内对整个活体动物）检测共生线虫中硫化合物的存在。
