saliva Flashcards
the digestive system
oral cavity
lined with stratified squamous epithelium
cells are nucleated
oral swabs used as DNA references
layers consistently renewed
saliva can contain exfoliated cells
comprised of many surfaces, each coat with a plethora or bacteria
saliva as evidence
may be necessary to identify saliva to establish an act
fellatio - persistance on penis
cunnilingus - persistence on external vaginal samples
licking or sucking breasts
assault against an officer (spit)
can persist on skin even after reported bathing
saliva
mostly water containing small amounts of electrolytes, buffers glycoproteins, antibodies, and enzymes
humans produce 1.0 - 1.5 L of saliva daily
product of three glands
submandibular salivary glands ( 70%)
parotids (25%)
sublingual salivary glands (5%)
visualization of stains may be more problematic than other bodily fluids
other fluids fluoresce under ALS (Semen, urine)
ALS 430 - 470 nm with yellow filter glasses
common in asexual assault evidence
amylases
enzymes cleave polysaccharides such as starches that are composed of D-glucose units connected by α 1-4 linkages
starches contain 2 types of glucose polymers
amylose
long unbranched chains of glucose residues connected by α 1-4 linkages
amylopectin
highly branched consisting of glucose residue chains by α 1-4 linkages and branch points by α 1-6 linkages
2 types of amylases
β- amylases
found in plant and bacterial sources
cleave only at the terminal reducing end of a polysaccharide chain
α-amylases
found in plants and animals so we make more specific by saying human
cleave at α 1-4 linkages randomly along polysaccharide chain
β bacteria
α animals
2 different human α amylases
two DNA loci on chromosome 1 encode for amylase
AMY1 (above the waist)
saliva, breast milk, prespiration
AMY2 (below the waist)
pancreas, semen, vag secretions
they are the 2 major isoenzymes (multiple forms that differ in their amino acid sequence)
this can cause interpretive problems when using radial diffusion assay of Phadebas assay
measure amylase activiy
doesn’t differentiate between amylases
human α amylases
salivary α amylase (HSA)
AMY1loci
saliva breast milk perspiration amniotic fluid, cervical mucous, tears
pancreatic α amylase (HPA)
AMY2 locu
pancreatic secretions, semen, vag secretions (with some AMY1) and feces
types of screening tests for saliva
largely based on the presence of amylase
enzymatic activity (Phadebas/SALIgAE - colorimetric, ELISA, radial diffusion starch iodine test for amylase)
detection of HSA proteins (Serateα-amylase, RSID- Saliva - immunochromatographic assays)
RNA based assays
radial diffusion starch-iodine assay for amylase
performed on an agarose gel
amylase breaks down starch
iodine stains starch blue
clear zones indicate amylase activity
measures the total amylase activity
cannot distinguish between AMY1 and AMY2
run standards at diff dilutions (1:100, 1:10) and negative and measure the diameter of clearing
negative is water
1:10 saliva
1:100 dilute saliva or another bodily fluid
RDA interpretation
range of amylase levels in saliva, vaginal secretions, and semen overlap
therefore interpretation based on the size of the clearing is not definite
RDA only measures amount of amylase activity
PHADEBAS
colorimetric assay
uses dye-labeled amylase substrates
these substrates are not soluble in water
in the presence of amylase, the dye-labeled substrates are cleaved and then soluble in water to produce a blue color, opposite in RDA
not HSA specific, not specific to humans, just amylase
press test and tube test
amylase interpretation overall
amylase is found in animals, microorganisms, and plants
intra- and inter- individual variation
hunger levels in a single person
range of amylase levels in saliva, vag secretions, and semen overlap
stability
salivary amylase loses much of its activity on drying and rehydration, variable
reported hald-life in dried stains 1-2 weeks up to 45 days
salivary amylase was detected on a 16 year old stamp
highly variable in stability
mapping (press-test) vs tube test
mapping
also called press test
use Whitman #1 grade filter paper sheet
moisten sheet with di h2o apply to substrate, apply weight
saliva transfers to paper because water soluble
reagents are then sprayed
tube test
sample is cut and placed in tube
incubated
reagents added directly to tube
ELISA for saliva
uses anti-HSA antibody, specific for human
specific
highly sensitive
but time consuming and costly
not used much
