A comparison of the sensitivity of typing group-specific component (Gc) and the phosphoglucomutase (PGM1) locus in control and casework bloodstains by three isoelectric focusing methods

The performance of typing group-specific component (Gc) in bloodstains by two isoelectric focusing methods followed by its detection with silver staining has been compared with an established forensic system of typing phosphoglucomutase (PGM1) locus phenotypes by isoelectric focusing (IEF) in 1 mm gels. For Gc typing ultra-thin isoelectric focusing (UTIEF) gels and immobilized pH gradient (IPG) gels were used. Both laboratory prepared stains and casework stains were examined. The Gc UTIEF method is approximately eight times more sensitive than the existing PGM1 1 mm IEF method for control and casework stains. However, on average, a larger amount of stain was taken from casework stains than control stains for each typing system. A total of 53 casework stains were examined. Comparable success rates of 62% and 64% were obtained for typing Gc on UTIEF gels and PGM1 by 1 mm IEF, respectively. A success rate of 55% was obtained for typing Gc on IPGs. Bloodstains that were over 200 days old were successfully grouped by all three methods.     

Vitamin D binding protein (Gc) subtypes by isoelectric focusing and immunoblotting

The polymorphism of the human vitamin D binding protein (Gc system) was investigated in a total of 149 sera from unrelated healthy Egyptians residing in Tanta City, Gharbiya Governorate, Nile Delta of Egypt, using isoelectric focusing (IEF) in thin-layer polyacrylamide gel followed by immunoblotting. The estimated gene frequencies were Gc1s = 0.540, Gc1f = 0.242 and Gc2 = 0.218.     

A method for subtyping group-specific component in bloodstains

A method is described for subtyping group-specific component (Gc) derived from human bloodstains. Bloodstained cuttings were extracted in 6 M urea. The extracts were subjected to ultrathin-layer polyacrylamide gel isoelectric focusing in the pH 4.5-5.4 range. After isoelectric focusing, Gc was detected by immunofixation in cellulose acetate membranes. This method permitted the successful typing of Gc in at least four-month-old bloodstains maintained at room temperature. Bloodstains from 266 liquid blood samples of known origin were subjected to both this method and immunofixation conventional agarose gel electrophoresis with no phenotypic discrepancies observed. The Gc population data for Whites from Baltimore, Maryland, were homogeneous with white sample populations from other geographical locations within the U.S.A.; while Gc data from northern U.S.A. black sample populations appeared to be heterogeneous compared with a southern United States black sample population.     

Group-specific component: a review of the isoelectric focusing methods and auxiliary methods available for the separation of its phenotypes

This review compares the major isoelectric focusing methods that have been published for the separation of group-specific component (Gc) phenotypes since 1978. The various parameters of gel composition, size, electrical and running conditions and sample application points are listed. More current auxiliary methods are also listed. These relate to the extraction of Gc from bloodstains and its identification after isoelectric focusing. Protocols are then recommended for the forensic analysis of Gc phenotypes.     

Identification of species specific hemoglobin by isoelectric focusing

A method for the discrimination of human hemoglobin from animal sources is described. Hemoglobins from 34 species with and without treatment by p-chloromercuri-benzoate (PCMB) were examined by thin-layer isoelectric focusing (IEF) in polyacrylamide gel (PAG) plates containing an Ampholine gradient of pH 3.5 – 9.5. PCMB treatment was effective in distinguishing human and animal hemoglobins with their characteristic IEF patterns. Values for the isoelectric points of the major and minor hemoglobins of each species are also described.     

Studies on the use of isoelectric focusing as a method of phenotyping erythrocyte acid phosphatase

The technique of isoelectric focusing (IEF) in ultra-thin polyacrylamide gels as a method of phenotyping erythrocyte acid phosphatase (EAP) has been applied to a large number of red cell lysates and dried bloodstains. This paper presents the results of this study and discusses some features of the IEF patterns and problems with their interpretation. The IEF patterns of several rare EAP phenotypes are also described. These studies have confirmed that IEF is more sensitive than starch gel electrophoresis as a method of phenotyping EAP in dried bloodstains.     

The use of separator isoelectric focusing in micro-ultrathin polyacrylamide gels in the characterization of some polymorphic proteins of forensic science significance

The identification of phenotypes of erythrocyte acid phosphatase (EAP), esterase D (EsD), group specific component (Gc), and alpha-1-antitrypsin (PI) by separator isoelectric focusing in micro-ultrathin polyacrylamide gels (interelectrode distance: 45 mm) is described. The protein patterns obtained are compared favorably with the patterns seen by isoelectric focusing in conventional polyacrylamide gel dimensions (interelectrode distance: 110 to 120 mm). The technique described allows greater stability of pH gradients and is a fast and economic method.     

A silver staining method for the detection of polymorphic proteins in minute bloodstains after isoelectric focusing

A silver staining method has been developed to study polymorphic proteins in bloodstains after isoelectric focusing. This method is highly sensitive and permits the detection of polymorphic proteins (i.e. alpha 1-antitrypsin, Gc and Tf C subtypes) in bloodstains as small as 0.2 microliter or less. The method is simple and reproducible and can be used after immunofixation. Blood stains can be identified after longer storage periods than is possible by using conventional staining methods.     

A stability study on Gc subtyping in bloodstains: comparison by two different techniques

The limits of determination of Gc subtypes in bloodstains were compared between the immunofixation method and the sulfosalicylic acid precipitation method using isoelectric focusing on polyacrylamide gel. By the immunofixation method Gc subtyping in bloodstains was successfully made at 37 degrees C after 7 weeks, at room temperature after 17 weeks and at 4 degrees C even after 25 weeks storage. By the sulfosalicylic method Gc subtypes were no longer able to be determined a few weeks after stain formation. The superiority of the results obtained by the immunofixation method makes it the recommended method for the Gc subtyping from bloodstains in medicolegal practice.     

Group specific component subtyping in bloodstains by separator isoelectric focusing in micro-ultrathin polyacrylamide gels followed by immunoblotting

The identification of group specific component (Gc) subtypes derived from blood-stains by separator isoelectric focusing in micro-ultrathin polyacrylamide gels (interelectrode distance: 50 mm) containing 4.5 to 5.4 pharmalytes is described. The separation achieved between Gc 1F and Gc 1S bands is compared favorably with that obtained using separator isoelectric focusing in conventional polyacrylamide gels dimensions (interelectrode distance: 110 to 120 mm). The technique is rapid and economical, and the immunoblotting method described is more sensitive than immunofixation followed by silver staining.     

Subtyping phosphoglucomutase-1 in semen stains and bloodstains: a report on the method

A method is described for obtaining nondistorted, reproducible phosphoglucomutase-1 subtyping patterns from semen stains and bloodstains. Isoelectric focusing of phosphoglucomutase-1 was accomplished in 80 min in a 0.2-mm-thick polyacrylamide gel with an interelectrode wick distance of 8.0 cm. The gel contained 1.2% (w/v) N-(2-hydroxyethyl) piperazine-N-3-propanesulfonic acid (EPPS) and pH 5 to 7 ampholytes (4% w/v). When maintained at room temperature, laboratory-prepared bloodstains and semen stains could be typed for phosphoglucomutase-1 up to four months and three weeks, respectively. An evaluation of phosphoglucomutase-1 typing by isoelectric focusing and the Group I system was performed on casework samples submitted to the FBI Laboratory. In addition to the increased discriminating probability of phosphoglucomutase-1 when subtyped, isoelectric focusing yielded an increase in positive calls on questioned bloodstains (65.6 versus 36.2%) and dried seminal stains (16.4 versus 13.1%) compared with the Group I system.     

A method to increase the volume of sample applied to isoelectric focusing gels

Isoelectric focusing of extracts from diluted or aged bloodstains may be more successfully accomplished with larger sample volumes applied to the gel. A technique is described using teflon tubing to apply larger sample volumes (up to 100 μl) to isoelectric focusing (IEF) gels. This method is reproducible and easy to perform.     

Isoelectric focusing of human hair keratins: correlation with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns and effect of cosmetic treatments.

A new isoelectric focusing (IEF) technique in polyacrylamide gels with 6M urea and 1.5% Nonidet P40 has been developed to characterize human hair samples. The phenotypes demonstrated with this procedure has been correlated with the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns described by other authors. The method described can be applied in the forensic science analysis of a single human hair. Using the same IEF technique we have studied the changes in electrophoretic patterns of cosmetically treated hair. The characteristics of the modifications observed and its utility in forensic science work are also discussed in this paper.     

The detection of group specific component (Gc) in the general population of West Virginia

An isoelectric focusing method is described for the detection of group specific component (Gc) in forensic casework. Gc can be subtyped in one day using this reliable and reproducible method. The gene frequency data collected indicate that the occurrence of Gc phenotypes in the population of West Virginia is consistent with established frequencies for the system.     

Evidence for a "new" allele at the esterase D (E.C. 3.1.1.1.) locus

An apparently new EsD gene product (EsD*Düsseldorf) was detected by use of horizontal agarose gel electrophoresis (AGE), starch gel electrophoresis (SGE), and isoelectric focusing (IEF). The observed phenotype EsD (1-Düsseldorf) can be distinguished from any known EsD type.     

Transferrin subtyping of human bloodstains

A method was described for subtyping transferrin derived from human bloodstains. Bloodstain cuttings were extracted in 0.5% ferrous ammonium sulfate. The extracts were subjected to ultrathin-layer polyacrylamide gel isoelectric focusing. After isoelectric focusing, transferrin was detected by silver staining. This method permitted the successful typing of Tf in 6-month-old blood stains maintained at -20 degrees C and room temperature and 3-month-old bloodstains maintained at 37 degrees C.     

Determination of phosphoglucomutase (PGM1), acid phosphatase (ACP), and esterase D (ESD) in human bloodstains by hybrid isoelectric focusing (HIEF)

PGM1, ESD, and ACP were determined in bloodstain extracts by isoelectric focusing (IEF) with carrier ampholytes (CA) and HIEF. HIEF yields superior results in PGM typing from bloodstain extracts, whereas for ESD and ACP typing isoelectric focusing with carrier ampholytes seems to be the method of choice.     

The use of ultrathin-layer agarose gels for phenotyping erythrocyte acid phosphatase by isoelectric focusing

A method is described for the use of ultrathin-layer agarose gels in phenotyping erythrocyte acid phosphatase (EAP) by isoelectric focusing (IEF). The results obtained using ultrathin-layer agarose gels are shown to be equally reliable and reproducible in comparison to established ultrathin-layer polyacrylamide gels. IEF of EAP on 0.168-mm agarose gels took place in 90 min using the LKB Multiphor system. The technique described allows for both time and cost efficient phenotyping of EAP.     

Genetic study of red cell esterase D polymorphism by ultrathin layer isoelectric focusing. Distribution in the Veneto population (Italy)

Human red cell Esterase D (EsD) was analyzed by isoelectric focusing (IEF) on ultrathin-layer polyacrylamide gel with a pH range of 5.0-6.0. Hemolysates were treated with Dithiothreitol to avoid loss of activity and change of the isozyme patterns by in vitro storage effects. In our sample of 951 unrelated persons from Veneto, seven different phenotypes were observed. The following allele frequencies were calculated: EsD1 = 0.8476, EsD2 = 0.1336, EsD5 = 0.0178, and EsDV = 0.0010.     

The use of hybrid isoelectric focusing for the detection of polymorphic proteins in blood stains

alpha1-Antitrypsin (Pi), transferrin (Tf) and orosomucoid (ORM) were determined in bloodstain extracts by isoelectric focusing (IEF) with carrier ampholytes (CA) and also with a mixture of immobilines (HIEF). HIEF yields superior results from proteins typing in bloodstain extracts, since phenotypes are better distinguished and the bands are straighter and sharper. Also the sensitivity of HIEF is similar to IEF with CA.