Saliva and saliva-stained materials were examined as potential sources of deoxyribonucleic acid (DNA) for DNA analysis and identity testing. In this paper, the authors demonstrate that DNA was isolated and DNA banding patterns suitable for DNA typing were obtained from fresh saliva and various saliva-stained materials, such as envelopes, buccal swabs, gags, and cigarettes. Furthermore, DNA and DNA banding patterns were obtained from actual forensic evidentiary samples containing mixed saliva/semen stains. The DNA banding patterns obtained from saliva or saliva-stained material were indistinguishable from the patterns obtained from blood or hair from the same individual. Intact DNA was readily isolated and DNA banding patterns were obtained from saliva stored at −20°C and dried saliva stains stored under varying conditions. We conclude that saliva and saliva-stained material can be good sources of DNA for analysis and for DNA typing in certain forensic settings.

Many aspects of photosynthetic gene expression are posttranscriptionally regulated in C4 plants. To determine if RbcS mRNA untranslated regions (UTRs) in themselves could confer any characteristic C4 expression patterns, 5′- and 3′-UTRs of AhRbcS1 mRNA from the C4 dicot amaranth were linked to a gusA reporter gene. These were constitutively transcribed from a cauliflower mosaic virus promoter and assayed for posttranscriptional expression patterns in transgenic lines of the C4 dicot Flaveria bidentis. Three characteristic C4 expression patterns were conferred by heterologous AhRbcS1 UTRs in transgenic F. bidentis. First, the AhRbcS1 UTRs conferred strong translational enhancement of gusA expression, relative to control constructs lacking these UTRs. Second, while the UTRs did not appear to confer tissue-specific expression when analyzed by β-glucuronidase activity assays, differences in gusA mRNA accumulation were observed in leaves, stems, and roots. Third, the AhRbcS1 UTRs conferred preferential gusA expression (enzyme activity and gusA mRNA accumulation) in leaf bundle sheath cells. AhRbcS1 UTR-mediated translational enhancement was also observed in transgenic C3 plants (tobacco [Nicotiana tabacum]) and in in vitro translation extracts. These mRNAs appear to be translated with different efficiencies in C4 versus C3 plants, indicating that processes determining overall translational efficiency may vary between these two categories of higher plants. Our findings suggest that the AhRbcS1 5′-UTR functions as a strong translational enhancer in leaves and other tissues, and may work synergistically with the 3′-UTR to modulate overall levels of Rubisco gene expression in different tissues and cell types of C4 plants.

Post-transcriptional regulation determines initial C4 gene expression patterns in developing leaves of Amaranthus hypochondriacus, an NAD-ME type C4 dicot. RuBPCase, PEPCase, and PPdK mRNAs are abundant in meristems and in leaf primordia, but are utilised only during specific developmental stages. While each enzyme shows independent patterns of initial mRNA and polypeptide accumulation, cell-specific localisation of the polypeptides occurs prior to cell-specific localisation of the mRNAs. In mature three-coloured leaves of A. tricolor, loss of photosynthetic activity correlates with reductions in the transcription rates of some plastid-encoded genes, reduction and loss of coordination in the translation of RuBPCase polypeptides, and loss of cell-specific accumulation of RuBPCase mRNAs (but not the polypeptides). The mitochondrial NAD-dependent malic enzyme (NAD-ME) provides an example of a basic metabolic enzyme that has acquired specialised gene expression patterns allowing it to function in the C4 pathway. NAD-ME occurs preferentially in photosynthetic tissues, and is specific to bundle sheath cells throughout development. NAD-ME synthesis is regulated by light and development at transcriptional and post-transcriptional levels. The findings summarised here indicate that C4 genes are independently regulated by multiple control mechanisms in response to developmental, environmental, and metabolic signals.