Identification of Salivary stain Nie Shengjie Assoc Prof

Identification of Salivary stain Nie Shengjie, Assoc. Prof Section of Forensic Biology 2010. 09. 20

Outline • Feature of saliva and salivary stain • Objective & requirement • Confirmatory test • Individual identification

Feature of saliva and salivary stain Salivary glands

Saliva secretion 唾液的分泌

Saliva composition 唾液成分

Objective & requirement 检验目的与要求 • Is it salivary stain? • Is it human salivary stain or animal salivary stain? • Individualize of salivary stain

Detection of amylase 淀粉酶检测 • High levels of amylase in the saliva. • Can be found in other body fluids saliva: 263 000 -376 000 U/L Urine: 263 -940 U/L Blood: 110 U/L Semen: 35 U/L Nasal secretion: undetectable levels Sweat: undetectable levels

Detection of amylase 淀粉酶检测 l Amylase enzyme can break down starch (淀粉) l Two kinds of test: Starch-iodine assay 淀粉碘实验 Phadebas Reagent Phadebas 试剂

Starch-Iodine Test 淀粉碘实验 • Gel diffuse 凝胶法: – Gel containing starch is stained blue with iodine – Sample is added to well in gel. If amylase (saliva) is present, the blue color begins to vanish 淀 粉 酶 检 测 含碘淀粉凝胶 有淀粉酶 无淀粉酶 OR before negative positive

Phadebas Reagent 菲德倍斯试剂法 淀 粉 酶 检 测 n Starch linked to a colored dye n Presence of amylase releases the dye 淀粉包裹染料制成微球，淀粉酶能将淀粉分 解，染料释放使溶液呈蓝色反应。 Two methods for using Phadebas Reagent: ¨ Press Test 按压法 ¨ Tube Test 试管法

The Phadebas® Forensic Press test Step 1: Place item to be Step 2: Cover testing area tested on a flat and clean with Phadebas® paper, surface. Dampen the item reagent side down. Dampen with water Phadebas® paper with water

Step 3: Trace an outline of the testing area on the Phadebas paper Step 4: Cover the Phadebas® paper with a clean glass board. Weigh down the Arrangement Step 5: Start a timer and observe the test frequently during 40 minutes. Record the time of positive reaction (distinct area of diffuse blue color).

The Phadebas® Forensic Tube Test • Small piece containing stain is placed in tube • Water and Phadebas reagent added, incubated in 37℃ • Centrifuged • Amount of color in top liquid is measured by a spectrophotometer.

Individualize of salivary stain 唾液斑个人识别 ABO血型 蛋白多态性 酶型 DNA分析

DNA Analysis n With some biological stains, DNA testing is more important than identifying the stain. n If a test destroys cells, it may not be done before DNA testing

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