Sheree Hughes-Stamm

Ultrastructure of the Digestive Tract of Gyliauchen nahaensis (Platyhelminthes, Digenea), an Inhabitant of the Hindgut of Herbivorous Fishes

Digenean parasites of vertebrates usually amplify the surface area of their gut by increasing the size of the absorptive caeca. Some members of the family Gyliauchenidae, however, have relatively small caeca but have a greatly expanded foregut. The morphology of the elongate gut of the digenean Gyliauchen nahaensis, an inhabitant of herbivorous fish of the family Siganidae, was examined by light and transmission electron microscopy. The extensive foregut, consisting of a mouth, pharynx, and esophagus, is lined with a syncytial tegument‐like lining, which is connected to nucleated cell bodies sunken in the parenchyma. The apical cytoplasm in the mouth and anterior regions of the pharynx resembles that of the general body tegument, although some regional specialization is present. The lining of posterior regions of the pharynx is armed with large apical projections, which are thought to serve as filtration structures. The lining of the anterior and middle esophagus displays a peculiar form of surface amplification involving the formation of elongate flask‐shaped invaginations of the apical cytoplasm. The cell bodies associated with these regions are rich in secretory vesicles and it is proposed that these regions of the esophagus are expanded to promote extracellular digestion. The posterior region of the esophagus lacks the invaginations of other esophageal regions, but displays instead large surface projections. The caeca consists of columnar cells lined by extensive apical microlamellae. The peculiar gut morphology of G. nahaensis, coupled with alterations in the arrangement of suckers, is interpreted to be an adaptation to the predominantly herbivorous diets of the definitive hosts. J. Morphol. 246:198–211, 2000.

Characterisation of a family of Schistosoma japonicum proteins related to dynein light chains.

Dynein light chains (DLC) are components of dynein, an enzyme complex involved in various aspects of microtubule-based motility. We report here the molecular cloning and sequencing of cDNAs encoding a family of DLC-like polypeptides (SjcDLC1-5) from the human bloodfluke Schistosoma japonicum with open reading frames of 87-104 amino acids and deduced molecular masses ranging from 10.5 to 12.3 kDa. Two-dimensional Western blot analysis confirmed the presence of several S. japonicum DLC isoforms with differing pI values and molecular sizes. We also describe the molecular characterisation, genomic organisation and expression of clone SjcDLC1, and the immunological characterisation and localisation of its encoded protein. Northern blot analysis of adult worm RNA indicated SjcDLC1 is encoded by a single message of approximately 650 bp and Southern analysis suggested one SjcDLC1 gene exists in the S. japonicum genome. Immunolocalisation studies demonstrated that the SjcDLC1 protein is present in the tegument of the adult and cercarial stages of S. japonicum. SjcDLC1 and the other SjcDLC may function in the transport of specialised organelles, comprising membranous and discoid bodies, through the tegument to the schistosome-unique heptalaminate tegumental membrane at the external surface of the adult worm. As a consequence, they may provide novel targets for anti-schistosome vaccine and/or drug development.

Structure of the tegument and ectocommensal microorganisms of Gyliauchen nahaensis (Digenea: Gyliauchenidae), an inhabitant of herbivorous fish of the Great Barrier Reef, Australia.

The ultrastructure of the tegument and tegument-associated microorganisms of the gyliauchenid digenean Gyliauchen nahaensis is described by transmission and scanning electron microscopy. The tegument is devoid of surface spines and is characterized by a moderately folded apical membrane, abundant vesicles, basal mitochondria, a folded basal plasma membrane, and a thick basal matrix. Microorganisms form a dense biofilm on the tegument of the posterodorsal surface and the excretory papilla. At least 7 microbial morphotypes were identified, including eubacteria, spirochaetes, and nanobacteria.

STRESS, GENES, AND GENERALIZABILITY ACROSS GENDER: EFFECTS OF MAOA AND STRESS SENSITIVITY ON CRIME AND DELINQUENCY*

In the current study, we extend the gene-by-environment interaction (cGxE) literature by examining how a widely studied polymorphism, the MAOA upstream variable number tandem repeat (MAOA-uVNTR) interacts with distal and proximal stressors to explain variation in crime and delinquency. Prior research findings have revealed that MAOA-uVNTR interacts with single indicators of environmental adversity to explain criminal behavior in general-population and incarcerated samples. Nevertheless, the genetically moderated stress sensitivity hypothesis suggests that increased risk for criminal behavior associated with variation in the MAOA-uVNTR can be best understood in the context of both distal stress during childhood and proximal stress in adulthood. Therefore, we employed Tobit regression analyses to examine a gene–distal–proximal environment (CGxExE) interaction across gender in a sample of university students (n = 267) and with data from the National Longitudinal Study of Adolescent to Adult Health (Add Health; n = 1,294). The results across both sets of analyses demonstrate that variation in the MAOA-uVNTR interacts with distal and proximal stress to lead to increased risk for criminal behavior in males. Although proximal life stress is associated with an increase in crime and delinquency, this effect is more pronounced among MAOA-L allele carriers that have experienced distal stress.

Development and evaluation of a rapid PCR method for the PowerPlex®S5 system for forensic DNA profiling

Forensic DNA profiling is a multi-step process taking approximately 10h to complete. A reduction in the amount of time required for the amplification step would allow for faster human identification and increase laboratory throughput. The goal of this work was to optimize and evaluate a rapid PCR method for the PowerPlex®S5 system for forensic DNA profiling. By pairing fast chemistries with a fast thermal cycler, we were able to reduce the amplification time by 70% (1 h). Sensitivity and heterozygous peak height ratios were comparable between the fast and standard protocols. However, there was a notable decrease (5%) in peak height ratio at the D18S51 locus with the fast cycling method. An increase in average mean stutter for combined loci of 2.6% was observed in profiles amplified using the fast protocol compared to the standard system. Our results suggest that with further optimization and validation the fast protocol can be used to replace the standard amplification conditions.

Developmental and internal validation of a novel 13 loci STR multiplex method for Cannabis sativa DNA profiling

Marijuana (Cannabis sativa L.) is a plant cultivated and trafficked worldwide as a source of fiber (hemp), medicine, and intoxicant. The development of a validated method using molecular techniques such as short tandem repeats (STRs) could serve as an intelligence tool to link multiple cases by means of genetic individualization or association of cannabis samples. For this purpose, a 13 loci STR multiplex method was developed, optimized, and validated according to relevant ISFG and SWGDAM guidelines. The STR multiplex consists of 13 previously described C. sativa STR loci: ANUCS501, 9269, 4910, 5159, ANUCS305, 9043, B05, 1528, 3735, CS1, D02, C11, and H06. A sequenced allelic ladder consisting of 56 alleles was designed to accurately genotype 101 C. sativa samples from three seizures provided by a U.S. Customs and Border Protection crime lab. Using an optimal range of DNA (0.5-1.0ng), validation studies revealed well-balanced electropherograms (inter-locus balance range: 0.500-1.296), relatively balanced heterozygous peaks (mean peak height ratio of 0.83 across all loci) with minimal artifacts and stutter ratio (mean stutter of 0.021 across all loci). This multi-locus system is relatively sensitive (0.13ng of template DNA) with a combined power of discrimination of 1 in 55 million. The 13 STR panel was found to be species specific for C. sativa; however, non-specific peaks were produced with Humulus lupulus. The results of this research demonstrate the robustness and applicability of this 13 loci STR system for forensic DNA profiling of marijuana samples.

A capillary electrophoresis method for identifying forensically relevant body fluids using miRNAs

Body fluid identification (BFID) can provide crucial information during the course of an investigation. In recent years, microRNAs (miRNAs) have shown considerable body fluid specificity, are able to be co-extracted with DNA, and their small size (18-25 nucleotides) make them ideal for analyzing highly degraded forensic samples. In this study, we designed a preliminary 8-marker system for BFID including an endogenous reference gene (let-7g) to differentiate between venous blood (miR-451a and miR-142-3p), menstrual blood (miR-141-3p and miR-412-3p), semen (miR-891a and miR-10b), and saliva (miR-205) using a capillary electrophoresis approach. This panel uses a linear primer system in order to incorporate additional miRNA markers by forming a multiplex system. The miRNA system was able to distinguish between venous blood, menstrual blood, semen, and saliva using a rudimentary data interpretation strategy. All STR amplifications from co-extracted DNA yielded complete profiles from human identification purposes.

Evaluation of four commercial quantitative real-time PCR kits with inhibited and degraded samples

DNA quantification is a vital step in forensic DNA analysis to determine the optimal input amount for DNA typing. A quantitative real-time polymerase chain reaction (qPCR) assay that can predict DNA degradation or inhibitors present in the sample prior to DNA amplification could aid forensic laboratories in creating a more streamlined and efficient workflow. This study compares the results from four commercial qPCR kits: (1) Investigator® Quantiplex® Pro Kit, (2) Quantifiler® Trio DNA Quantification Kit, (3) PowerQuant® System, and (4) InnoQuant® HY with high molecular weight DNA, low template samples, degraded samples, and DNA spiked with various inhibitors.The results of this study indicate that all kits were comparable in accurately predicting quantities of high quality DNA down to the sub-picogram level. However, the InnoQuant(R) HY kit showed the highest precision across the DNA concentration range tested in this study. In addition, all kits performed similarly with low concentrations of forensically relevant PCR inhibitors. However, in general, the Investigator® Quantiplex® Pro Kit was the most tolerant kit to inhibitors and provided the most accurate quantification results with higher concentrations of inhibitors (except with salt). PowerQuant® and InnoQuant® HY were the most sensitive to inhibitors, but they did indicate significant levels of PCR inhibition. When quantifying degraded samples, each kit provided different degradation indices (DI), with Investigator® Quantiplex® Pro indicating the largest DI and Quantifiler® Trio indicating the smallest DI. When the qPCR kits were paired with their respective STR kit to genotype highly degraded samples, the Investigator® 24plex QS and GlobalFiler® kits generated more complete profiles when the small target concentrations were used for calculating input amount.

Comparison of DNA yield and STR success rates from different tissues in embalmed bodies

Formalin fixation is commonly used to preserve tissue sections for pathological testing and embalming cadavers for medical dissection or burial. DNA extracted from formalin-fixed tissues may also provide an alternative source of genetic material for medical diagnosis and forensic casework, such as identifying unknown embalmed human remains. Formaldehyde causes DNA damage, chemical modifications, and degradation, thereby reducing the quantity and quality of DNA available for downstream genetic analyses. By comparing the DNA yield, level of DNA degradation, and short tandem repeat (STR) success of various tissue types, this study is the first of its kind to provide some guidance on which samples from embalmed bodies are likely to generate more complete STR profiles. Tissue samples were dissected from three male embalmed cadavers and included bone, cartilage, hair, muscle, internal organs, skin, teeth, and nail clippings. DNA was purified from all samples using the QIAamp® FFPE Tissue Kit (Qiagen), quantified using the QuantiFiler® Trio DNA Quantification kit (Life Technologies), and genotyped using the GlobalFiler® PCR Amplification Kit (Life Technologies). Results of this study showed variation in DNA quantity and STR success between different types of tissues and some variation between cadavers. Overall, bone marrow samples resulted in the highest DNA yields, the least DNA degradation, and greatest STR success. However, several muscle, hair, and nail samples generated higher STR success rates than traditionally harvested bone and tooth samples. A key advantage to preferentially using these tissue samples over bone (and marrow) and teeth is their comparative ease and speed of collection from the cadaver and processing during DNA extraction. Results also indicate that soft tissues affected by lividity (blood pooling) may experience greater exposure to formalin, resulting in more DNA damage and reduced downstream STR success than tissues under compression. Overall, we recommend harvesting from selected muscles (gastrocnemius, rectus femoris, flexor digitorum brevis, masseter, brachioradialis) or fingernails for human identification purposes.

An alternate method for extracting DNA from environmentally challenged teeth for improved DNA analysis

A grinding-free method to extract DNA from teeth via a direct minimal-invasive retrograde approach to the pulp cavity and dentine was compared to a standard grinding/pulverisation method. This alternate method uses endodontic dental files to access the root canals and pulp cavity for tissue and dentine harvest via the apical end of the roots and avoids mechanical damage to the crown and root morphology. In contrast, other methods require pulverisation of the whole root or tooth, transection or destruction of the occlusal surface to gain access to the DNA in the root canals and pulp chamber. This study compared two methods for preparing dentine powder from the roots of environmentally challenged teeth for forensic DNA analysis. We found that although the filing method was more laborious, and produced less dentine powder, the amount of amplifiable DNA per milligram of powder was substantially higher with the filing method compared to grinding the entire root. In addition, the number of short tandem repeat (STR) alleles detected and the peak height ratios of the STR profiles were notably higher. Although several other methods of extracting DNA-rich tissue from the pulp chamber of teeth have previously been reported, the method presented in this study is minimally invasive, thereby allowing the preservation of tooth and crown morphology.