Forensic Bio

• 98% water
• 2% (Electrolytes, Mucus, Antibacterial compounds, Enzymes, Cells)

• Parotid gland (near the ears)
• Submandibular and sublingual glands (under the tongue)
• Also produced in two types of epithelial cells:
• mucous cells
• serous cells

0.75-1.5 liters

• ~stains are invisible to faint white
• ~stains faintly fluoresce at 450nm
• ~several million human cells per milliliter
• ~several hundred million bacterial cells per milliliter

• inorganic anions (thiocynate, nitrites)
• Enzymes (alkaline phosphatase, Amylase)
• antigens (HSA)

• -inorganic anion in saliva
• -detected by adding ferric chloride (forms a red/pink product)
• - 2.5 times higher in smokers
• - concentration decreaes with time
• - found in other body fluids in lower concentrations
• - may be present in undetectable amounts- negative result does not exclude saliva

• -inorganic anions found in saliva
• -NO2 is detected by the Griess test (used in GSR)
• -undetectable after a few weeks- so positive result meanse the stain is relatively recent
• -source= ingested nitrates in diet are broken down by bacteria
• -also form when nitrogen-containing substances decompose

• -most common method of detecting saliva
• -one of the oldest know enzymes (1831)
• -found in both plants and amylase
• -a and b amylase

• -found in plants; breaks starch into sugar in ripening fruit
• -yeast, mold and bacteria

• produced by humans and some animals that have a diet of complex carbohydrates
• -a-amylase is responsible for catalyzing the breakdown of starch, amylose and amylopectin into smaller less complex sugars
• -approx. 50 times higher in saliva than most other body fluids (values can vary within an individual and between individuals)
• -relatively stable
• -originally names ptyalin
• -type of amylase typically encountered in forensic science
• -saliva has one of the highest amylase values

• -loses activity upon drying (once dry, the rate at which activity loss
• occurs decreases)
• -will become inactive at high temperatures (100C),
• in the presence of strong acids or stong bases

True, usually. However occasionally the amylase activity in vaginal secretions can enter the range of saliva.

True

• -maintain oral health
• -lubricate the passage of food
• -breakdown of carbohydrates

other uses: breaks down starches in simple sugars in bread making; and added to detergents to dissolve starches from fabric

• AMY 1: Salivary amylase (HSA)- saliva, breast milk, perspiration, tears
• AMY 2: Pancreatic amylase (HPA)- pancreas, vaginal secretion, seminal plasma, fecal material

• -lectins used to preferentially inhibit one or the other
• -monoclonal antibodies used to react with one type or the other (ELISA)

• -isoenzymes (multiple molecular forms) will separate with polycrylamide or agar gel
• -electrophoresis:
• -AMY1 has 7 phenotypes
• -AMY2 has 3 phenotypes

• -bitemarks (objects or skin)
• -cigarette butts
• -drinking vessels
• -masks
• -condoms
• -vaginal/penile swabs
• -stamps/envelopes
• -expirated blood

• -Stiff area
• -whitish stain
• -use an ALS
• -look at obvious locations where saliva would be (i.e. the end of a cigarette)
• -mapping

• -Semen
• -saliva
• -urine
• -breast milk

• -UV light (200-400nm) can damaging to DNA
• -polilight, omnichrome, ultralight- 450nm
• -needs an orange filter
• -not damaging to DNA
• -Longwave UV (365-415nm)
• -UV A
• - good for body fluids such as semen and salive- exhibit a greenish flouresence
• -blood appears black
• -no barrier filter needed, but goggles used for eye protection

• -swabs: bitemarks (on skin, lightly rub with moistened swab); Cans, cups, bottles (swab inside and outside of rim)
• -Cuttings: masks, cigarette filter, vaginal swabs, envelopes

True. because of ease of collection

True. saliva samples were sometimes taken as reference materials for determining secretor status and stains were types using absorbtion-elution or absorption-inhibition

Starch gel, Phadebas

RSID, RNA-based

- also detection of high levels of salivary amylase and observation of glycogen free nucleated epithelial cells = saliva confirmation

• -agarose gel with starch added
• -iodine added, dyes starch dark blue
• -absence of blue color, indicates no starch because amylase digests starch
• -indicates hydrolysis reaction

• Advantages:
• -Cheap
• -Fairly easy
• -can run multiple samples on same gel
• -identifies amylase
• disadvantages:
• -difficult to use as locater
• -not specific to saliva

• -1974 began to be used forensically
• -Insoluble blue dye attached to starch polymer
• -Upon hydrolysis by amylase, blue dye released

- Active ingredient: starch polymer chains are interlinked to form spheres of uniform and pre-defined size- called bio-degradable starch microspheres (DSMS)

• -DSMS are insoluble in water- a water soluble
• blue dye is chemically attached and as long as the dye is bound to the DSM, it
• remains insoluble in water

• -In the presence of amylase, the DMSs are
• degraded by the enzyme, at a speed increasing with the solution’s amylase
• activity

• Tube test:
• -useful when amylase is suspected in mixed body fluid stains
• -test quantifies amylase activity in a positive stain
• -spectrophotometer can measure optical density of the sample
• Press test:
• -used for detection of hidden saliva stains (mapping)
• - paper can be tested for semen when amylase test is complete

• - Quantitative assays: free water soluble fraction of dye is measured with spectrophotometer (Concentration of dye is proportional to amylase)
• - Qualitative assays: (press test) diffusion of liberated blue dye molecules indicates the presence of amylase
• -Manufacture claims no other body fluid (except
• some fecal stains) will yield a positive result in 10 minutes

• The mechanism is unknown due to proprietary nature
• - Salivary amylase reacts with colorless tests to
• produce a yellow color change in 1-10 minutes

False

True (according to the manufacturer) however there is a low level cross reaction with human breast milk

• -immunochromatographic strip test that detects human salivary a-amylase
• - uses antibodies to detect presence of amylase rather than activity of amylase
• - only a fraction of extract is used, remainder is available for DNA analysis

Mouse

• -Ag-ab complex is formed
• - Ag-Ab migrates to the test area of the strip
• - Immobilized antibodies in test area “capture” the Ag-Ab complex forming an Ab-Ag-Ab sandwich
• -Colloidal gold accumulates at test area becomes visible as a pink band in the test region

No high dose hook effect when tested with 50ul saliva

• - Use PCR to detect the expression of genes exclusive to the oral cavity
• - Relatively new application
• - Specific but can degrade easily

False- amylase degrades over time and starting values may be low in some samples

True

Analysis of ___ gave chemical indications for the presence of amylase, a component of saliva.

Amylase, a constituent of saliva, was not detected on ___.