Chemical Education Today
Reports from Other Journals
Research Advances by Angela G. King
Human Urine As a Fertilizer for Food Crops Researchers in Finland are reporting successful use of an unlikely fertilizer for farm fields that is inexpensive, abundantly available, and undeniably organic—human urine. Despite the “yuk!” factor, urine from healthy individuals is virtually sterile, free of bacteria or viruses and has a fertilizer value of N/P/K/S of 15:1:3:1 when mixed with flush water. Naturally rich in nitrogen and other nutrients, urine has been used as fertilizer since ancient times, but urine fertilization is rare today. It has gained attention, however, in some areas as farmers embrace organic production methods and try to reduce use of synthetic fertilizers. In a recent study, Surendra K. Pradhan and colleagues at the University of Kuopio collected human urine from private homes and used it to fertilize cabbage crops. Cabbage was selected as the test plant because of its worldwide distribution and its high requirement for nitrogen. They compared urine-fertilized crops with those grown with conventional industrial fertilizer, both at doses of 180 kg N/ha and with no fertilizer. The analysis showed that growth and biomass were slightly higher with urine than with conventional fertilizer and substantially greater than for plants that received no fertilizer. Additionally, insect damage was lower for urine-fertilized plants than for commercially fertilized plots. There was no difference in nutritional value of the cabbage. The hygienic quality of sauerkraut produced by lactic acid fermentation of cabbage from each of the three treatments (urine fertilizer, industrial fertilizer, and no fertilizer) were all good, and fecal coliforms were not detected in any sample. Glucosinolates (GLSs), which possess a sugar moiety, sulfur, and nitrogen, were used as markers of chemical flavor compounds and quantified with HPLC. GSL levels were shown not to vary between the test plots. Human panelists could detect differences between the three sauerkraut samples but there was not a clear preference for any of the tastes. “Our results show that human urine could be used as a fertilizer for cabbage and does not pose any significant hygienic threats or leave any distinctive flavor in food products,” the report concludes. In the future, switching to urine fertilizer may mitigate the environmental damage done during production and transport of traditional fertilizer. More Information 1. Pradhan, Surendra K.; Nerg, Anne-Marja; Sjoeblom, Annalena; Holopainen, Jarmo K.; Heinonen-Tanski, Helvi. Use of Human Urine Fertilizer in Cultivation of Cabbage (Brassica oleracea)—Impacts on Chemical, Microbial, and Flavor Quality. J. Agric. Food Chem. 2007, 55, 8657–8663. 2. This Journal has published a tested Classroom Activity making sauerkraut from cabbage. It details the lactic acid fermentation referred to in this research paper. See J. Chem. Educ. 2000, 77, 1432A.
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3. This research is also described online at http://www. medicinenet.com/script/main/art.asp?articlekey=84401 (accessed May 2008).
Faster, More Sensitive Anthrax Detection Amid continuing concerns that anthrax might be used as a bioterrorism weapon, government researchers report development of a faster, more sensitive blood test for detecting the deadly toxins produced by the bacterium Bacillus anthracis (anthrax). Lethal factor (LF), the key toxin produced by the anthrax bug, is a zinc-dependent endoproteinase known to target members of the mitogen-activated protein kinase kinase (MAPKK) family. Systemic infection from the progression of an anthrax infection can cause secondary shock, organ failure, and death. In 2001, bioterrorism attacks involving inhaled anthrax in the U.S. had a 45% fatality rate despite treatment with antibiotics. Standard identification of anthrax infection relies on a combination of time-consuming steps, including cell culture and gene amplification, which can take several days to provide a diagnosis and have limitations for detecting early stages of infection. Early diagnosis is critical for effective treatment of pulmonary or inhalation anthrax, the most deadly form. The newly developed test produces results in only 4 hours and could save lives by allowing earlier detection of infection, researchers say. John R. Barr and colleagues in a multi-center team effort used a form of mass spectrometry to detect the presence of functional LF in the blood of monkeys with inhalation anthrax. Their approach uses anti-LF monoclonal antibodies immobilized on magnetic protein G beads to capture LF from serum. Magnetic protein G beads are an affinity matrix for the smallscale isolation and purification of immunoglobulins. The captured LF cleaved a MAPKK peptide substrate into two pieces, which were analyzed by MALDI–TOF mass spectrometry and quantified by isotope dilution-MS. The method took only four hours to identify the toxin and detected LF at concentrations as low as 0.05 ng/mL, demonstrating its potential for early detection of infection, the researchers say. The new method also shows promise as a research tool for providing a better understanding of the anthrax infection cycle and for evaluating the effectiveness of different therapies and methods to fight infections. The combination of highly specific LF-antibody capture, LF-specific substrate cleavage, and MS peptide detection produces unambiguous results that have great potential for advancing both detection and understanding. More Information 1. Boyer, Anne E.; Quinn, Conrad P.; Woolfitt, Adrian R.; Pirkle, James L.; McWilliams, Lisa G; Stamey, Karen L.; Bagarozzi, Dennis A.; Hart, John C. Jr.; Barr, John R. Detection and Quantification of
Journal of Chemical Education • Vol. 85 No. 8 August 2008 • www.JCE.DivCHED.org • © Division of Chemical Education
Chemical Education Today
Anthrax Lethal Factor in Serum by Mass Spectrometry. Anal. Chem. 2007, 79, 8463–8470. 2. Research Advances has previously described breakthroughs in the structure/function understanding of anthrax toxins; see J. Chem. Educ. 2004, 81, 1086. 3. Related methodology uses mass spectrometry to detect Coxiella burnetii, which causes human disease Q fever and could potentially be used as a bioweapon. For more information, see http://www.gatech. edu/newsroom/release.html?id=628 (accessed May 2008). 4. The Center for Disease Control and Prevention hosts a Web site devoted to relevant information regarding anthrax infection and exposure. See http://www.bt.cdc.gov/agent/anthrax/ (accessed May 2008).
Seagulls Monitor Oil Spill Pollutants Like the proverbial coal miners’ canary-in-the-cage, seagulls may become living sentinels to monitor oil pollution levels in marine environments, according to scientists in Spain (Figure 1). In the study, Alberto Velando and colleagues note that researchers have known for years that large oil spills can increase levels of polycyclic aromatic hydrocarbons (PAHs) in marine environments. While oil spills quickly kill large numbers of seabirds and other animals, the Spanish researchers say that scientists do not fully understand the non-lethal biological effects of these spills. Earlier studies have linked these compounds to cancer in humans. Since blood cells have a lifespan of only a few weeks and are continually replaced, the presence of PAHs in blood cells probably indicates recent incorporation. This fact led investigators to consider the use of PAH levels in blood cells as a bioindicator of environmental contamination. The researchers measured levels of 15 PAHs in the blood of Yellow-legged gulls living in the vicinity of one of Europe’s largest oil spills, which was caused by the 2002 shipwreck of the Prestige. Researchers collected 1–2 mL blood samples from wild birds, and analyzed samples by HPLC to identify and quantitate PAHs. Spatial comparison of PAH levels was accomplished through a generalized mixed model (PROC MIXED). Gulls exposed to the oil spill due to location of their colony (oiled birds) showed twice the levels of PAHs in their blood as that of unexposed birds (unoiled), even though these levels were measured 17 months after the initial spill, the researchers say. These measurements also showed that naphthalene dominated the PAH profile, accounting for 22–38% of the total PAH content. In two years, the PAH levels in oiled birds dropped by almost a third over two breeding seasons. The research team also conducted a study to evaluate the relationship between oil ingestion and PAH levels in which 16 breeding pairs of gulls were fed oil, while 20 breeding pairs served as a control group. Oil-supplemented birds had higher PAH levels than the control groups. Five specific compounds (anthracene, fluoranthene, benzo(k)fluoranthene, benzo(a) pyrene, and dibenz(a,h)anthracene) had concentrations much
Figure 1. Seagull blood shows promise for monitoring pollutants from oil spills in marine environments. Photo courtesy of Alberto Velando, Universidade de Vigo, Spain.
higher in oil-supplemented birds when compared to the control group. Relative abundances of individual hydrocarbons in blood did not correlate with their abundance in the oil supplement but correlated instead with their molecular mass. The findings “give support to the nondestructive use of seabirds as biomonitors of oil pollution in marine environments,” the report states. Monitoring programs based on PAH analysis of non-destructive blood samples are promising to complement existing environmental practices. More Information 1. Perez, Cristobal; Velando, Alberto; Munilla, Ignacio; LopezAlonso, Marta; Oro, Daniel. Monitoring Polycyclic Aromatic Hydrocarbon Pollution in the Marine Environment after the Prestige Oil Spill by Means of Seabird Blood Analysis. Environ. Sci. Technol. 2008, 42, 707–713. 2. Research Advances has previously described the use of snapping turtles as biomonitors; see J. Chem. Educ. 2008, 85, 174. 3. This Journal has published an experiment using magnetic particles for oil spill remediation. See J. Chem. Educ. 1997, 74, 1446. 4. PAHs were JCE Featured Molecules in a previous issue of JCE that also reported their quantitative analysis in cigarette smoke. See J. Chem. Educ. 2004, 81, 242, 245, and 912.
Gender through Feathers Scientists in Germany report the development of test that can answer one of the most frustrating questions in the animal kingdom: Is that bird a boy or a girl? In their study, Juergen Popp and colleagues point out that the boy–girl question can be difficult to answer in birds that lack distinctive, gender-related plumage (Figure 2). Since birds lack external genital organs, sexing a bird typically involves endoscopic examination of the animal’s gonads under general anesthesia or specific molecular biological methods. Since these methods are expensive, timeconsuming, and stressful for the bird, scientists long have sought a quick, minimally invasive sexing alternative.
© Division of Chemical Education • www.JCE.DivCHED.org • Vol. 85 No. 8 August 2008 • Journal of Chemical Education
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Reports from Other Journals shaft from tip to base, and the resulting liquid feather pulp was smeared on a fused-silica surface and allowed to dry. 18 male and 16 female samples were analyzed, with about 10 Raman fingerprint spectra recorded for each sample, and the resulting data analyzed with chemometrical methods for gender classification. Based on the chicken pilot, the test takes less than a minute, and identifies the birds’ sex with 95 percent accuracy, the scientists say. More Information Figure 2. In a finding that could be a boon to poultry farmers and bird breeders, scientists have developed a new test to ease the sometimes difficult task of determining the sex of birds. Photo courtesy of USDA Agricultural Research Service.
In the new study, researchers describe such a test, which involves analysis of tissue pulp from birds’ feathers using highly sensitive ultraviolet–resonance Raman spectroscopy (UVRR). Deep UV excitation wavelengths are used to study samples with high DNA and/or protein content. Researchers postulated that the known difference in genome size between male and female chickens, with males having ~2% more DNA, would result in detectable difference in UVRR signals for male and female chicken samples. This difference in DNA content is detectable by Raman spectroscopy when deep UV wavelengths are used for excitation since carbohydrates and lipids generate negligible signals under those conditions. In the pilot study, feathers were plucked from a flock of 6-week-old chickens of mixed sexes and stored at ‒20 °C. Cell material containing DNA was obtained by pressing the feather
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1. Harz, M.; Krause, M.; Bartels, T.; Cramer, K.; Roesch, P.; Popp, J. Minimal Invasive Gender Determination of Birds by Means of UV–Resonance Raman Spectroscopy. Anal. Chem. 2008, 80, 1080–1086. 2. Background on Raman spectroscopy is available in an online tutorial, found at http://www.kosi.com/raman/resources/tutorial/ (accessed May 2008). 3. A molecular test for the determination of bird gender is described online at http://www.mun.ca/biology/scarr/Bird_sexing.html (accessed May 2008).
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2008/Aug/abs1022.html Abstract and keywords Full text (PDF) with links to cited URLs and JCE articles
Angela G. King is Senior Lecturer in Chemistry at Wake Forest University, P.O. Box 7486, Winston-Salem, NC 27109;
[email protected].
Journal of Chemical Education • Vol. 85 No. 8 August 2008 • www.JCE.DivCHED.org • © Division of Chemical Education
