Forensic botany: using plant evidence to aid in forensic death investigation. (17/95)

Forensic botany is still an under-utilized resource in forensic casework, although it has been used on occasion. It is an area of specialty science that could include traditional botanical classification of species, DNA, or materials evidence (trace and transfer evidence), crime mapping or geo-sourcing, all dependent on the specific case application under consideration. Critical to the evaluation of plant evidence is careful collection, documentation, and preservation for later scientific analysis. This article reviews proper procedures and recent cases where botanical evidence played a role in establishing either manner or time of death. Plant evidence can be useful for determining if a death was due to an accident, suicide, or homicide, or what time of year burial may have taken place. In addition, plant evidence can be used to determine if a crime scene is a primary or secondary scene and to locate missing bodies.  (+info)

Design and fabrication of adjustable red-green-blue LED light arrays for plant research. (18/95)

BACKGROUND: Although specific light attributes, such as color and fluence rate, influence plant growth and development, researchers generally cannot control the fine spectral conditions of artificial plant-growth environments. Plant growth chambers are typically outfitted with fluorescent and/or incandescent fixtures that provide a general spectrum that is accommodating to the human eye and not necessarily supportive to plant development. Many studies over the last several decades, primarily in Arabidopsis thaliana, have clearly shown that variation in light quantity, quality and photoperiod can be manipulated to affect growth and control developmental transitions. Light emitting diodes (LEDs) has been used for decades to test plant responses to narrow-bandwidth light. LEDs are particularly well suited for plant growth chambers, as they have an extraordinary life (about 100,000 hours), require little maintenance, and use negligible energy. These factors render LED-based light strategies particularly appropriate for space-biology as well as terrestrial applications. However, there is a need for a versatile and inexpensive LED array platform where individual wavebands can be specifically tuned to produce a series of light combinations consisting of various quantities and qualities of individual wavelengths. Two plans are presented in this report. RESULTS: In this technical report we describe the practical construction of tunable red-green-blue LED arrays to support research in plant growth and development. Two light fixture designs and corresponding circuitry are presented. The first is well suited for a laboratory environment for use in a finite area with small plants, such as Arabidopsis. The second is expandable and appropriate for growth chambers. The application of these arrays to early plant developmental studies has been validated with assays of hypocotyl growth inhibition/promotion and phototropic curvature in Arabidopsis seedlings. CONCLUSION: The presentation of these proven plans for LED array construction allows the teacher, researcher or electronics aficionado a means to inexpensively build efficient, adjustable lighting modules for plant research. These simple and effective designs permit the construction of useful tools by programs short on electronics expertise. These arrays represent a means to modulate precise quality and quantity in experimental settings to test the effect of specific light combinations in regulating plant growth, development and plant-product yield.  (+info)

A novel in vitro system for gamete fusion in maize. (19/95)

Various systems by using electric pulse, calcium, or polyethylene glycol have been developed in the past decade for the in vitro fusion of plant gametes. These in vitro systems provide a new way to study the fertilization mechanisms of plants. In this study, we developed a bovine serum albumin (BSA)-mediated fusion system for the in vitro fusion of maize gametes. The in vitro fusion of the isolated single egg cell and sperm cell of maize was observed microscopically in the BSA solution and the fertilized egg cell showed normal cell wall regeneration and nuclear division. The effects of the BSA concentration, pH value and calcium level on the efficiency of the maize gamete fusion were also assessed. BSA concentration and pH value did significantly affect the efficiency of the gamete fusion. Calcium was not necessary for the gamete fusion when BSA was present. The optimal solution for the gamete fusion contained 0.1% BSA, pH 6.0. The fusion frequency was as high as 96.7% in that optimal solution. This new in vitro fertilization system offers an alternative tool for the in vitro study of fertilization mechanisms with much simpler manipulating procedure than PEG system, and it will be especially useful for the in vitro study of the calcium dynamics during plant fertilization.  (+info)

Oxygen isotope enrichment (delta18O) as a measure of time-averaged transpiration rate. (20/95)

Experimental evidence is presented to show that the 18O enrichment in the leaf biomass and the mean (time-averaged) transpiration rate are positively correlated in groundnut and rice genotypes. The relationship between oxygen isotope enrichment and stomatal conductance (g(s)) was determined by altering g(s) through ABA and subsequently using contrasting genotypes of cowpea and groundnut. The Peclet model for the 18O enrichment of leaf water relative to the source water is able to predict the mean observed values well, while it cannot reproduce the full range of measured isotopic values. Further, it fails to explain the observed positive correlation between transpiration rate and 18O enrichment in leaf biomass. Transpiration rate is influenced by the prevailing environmental conditions besides the intrinsic genetic variability. As all the genotypes of both species experienced similar environmental conditions, the differences in transpiration rate could mostly be dependent on intrinsic g(s). Therefore, it appears that the delta18O of leaf biomass can be used as an effective surrogate for mean transpiration rate. Further, at a given vapour pressure difference, delta18O can serve as a measure of stomatal conductance as well.  (+info)

A fully automatable enzymatic method for DNA extraction from plant tissues. (21/95)

BACKGROUND: DNA extraction from plant tissues, unlike DNA isolation from mammalian tissues, remains difficult due to the presence of a rigid cell wall around the plant cells. Currently used methods inevitably require a laborious mechanical grinding step, necessary to disrupt the cell wall for the release of DNA. RESULTS: Using a cocktail of different carbohydrases, a method was developed that enables a complete digestion of the plant cell walls and subsequent DNA release. Optimized conditions for the digestion reaction minimize DNA shearing and digestion, and maximize DNA release from the plant cell. The method gave good results in 125 of the 156 tested species. CONCLUSION: In combination with conventional DNA isolation techniques, the new enzymatic method allows to obtain high-yield, high-molecular weight DNA, which can be used for many applications, including genome characterization by AFLP, RAPD and SSR. Automation of the protocol (from leaf disks to DNA) is possible with existing workstations.  (+info)

The cucurbit images (1515-1518) of the Villa Farnesina, Rome. (22/95)

BACKGROUND: The gorgeous frescoes organized by the master Renaissance painter Raphael Sanzio (1483-1520) and illustrating the heavenly adventures of Cupid and Psyche were painted between 1515 and 1518 to decorate the Roman villa (now known as the Villa Farnesina) of the wealthy Sienese banker Agostino Chigi (1466-1520). Surrounding these paintings are festoons of fruits, vegetables and flowers painted by Giovanni Martini da Udine (1487-1564), which include over 170 species of plants. A deconstruction and collation of the cucurbit images in the festoons makes it possible to evaluate the genetic diversity of cucurbits in Renaissance Italy 500 years ago. FINDINGS: The festoons contain six species of Old World cucurbits, Citrullus lanatus (watermelon), Cucumis melo (melon), Cucumis sativus (cucumber), Ecballium elaterium (squirting cucumber), Lagenaria siceraria (bottle gourd) and Momordica balsamina (balsam apple), and two or three species of New World cucurbits, Cucurbita maxima, C. pepo and, perhaps, C. moschata (pumpkin, squash, gourd). The images of C. maxima are the first illustrations of this species in Europe.  (+info)

2005: signaling breakthroughs of the year. (23/95)

2005 was particularly notable for the range and scope of exciting advances in cell signaling research. Nominations from leading scientists ranged from plant signaling, neurobiology, and immunology to systems biology and structural biology. In plant biology, a new piece added to a long-standing puzzle in auxin signaling was discovered. The exploitation and regulation of RNA in cell signaling was also in the limelight. Intriguing new twists were highlighted in relation to functional and dysfunctional signaling in the brain, calcium-mediated signals, and the innate immune response. Finally, mathematical and statistical analysis of biochemical networks provided new insights into the circuitry of cell signaling pathways.  (+info)

Teaching resources. Model of the TIR1 pathway for auxin-mediated gene expression. (24/95)

Auxin mediates numerous plant responses, some of which have been shown to require transcriptional regulation. One auxin response pathway, which depends on the relief of transcriptional repression, is mediated by TIR1 (transport inhibitor response protein 1). TIR1 is an auxin receptor and also a subunit of an SCF-type ubiquitin ligase. In the presence of a low concentration of auxin in the nucleus, members of the Aux/IAA family of transcriptional repressors bind to ARF proteins and inhibit the transcription of specific auxin response genes. Increased nuclear concentrations of auxin promote auxin binding to TIR1, causing the Aux/IAA proteins to associate with TIR1 and leading to their degradation by a proteasome-mediated pathway. This decreases the concentration of Aux/IAA proteins in the nucleus and thereby enables the expression of certain auxin response genes.  (+info)