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L. Symeonidis 《Biometals》1990,3(3-4):204-207
Summary Plant yield of mycorrhizal and non-mycorrhizalFestuca rubra L. was linearly decreased with increasing zinc concentrations in nutrient solution. In all cases, non-mycorrhizal plant growth was significantly greater than that of mycorrhizal plants. Zinc and phosphorus concentrations of root and shoot of mycorrhizal plants were greater in all zinc treatments while mycorrhizal plants showed equal or lower tolerance indices to zinc than non-mycorrhizal plants. Yield depressions of mycorrhizal plants may be the result of enhanced zinc and phosphorus concentrations combined with the cost for growth and maintenance of the mycorrhizal fungi. 相似文献
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Henry A. F. Stephens Robert W. Vaughan Lazaros I. Sakkas Ken I. Welsh Gabriel S. Panayi 《Immunogenetics》1989,30(3):149-155
Despite extensive analysis of the incidence ofHLA-DR andHLA-DQ allele frequencies in defined autoimmune disease groups, there is very little information available onHLA-DP allele frequencies. This is largely becauseHLA-DP typing has until recently been restricted to primed lymphocyte typing (PLT). However, allelic polymorphism of theHLA-DP subregion can now be studied by Southern blot analysis or genotyping withDPA1 andDPB1 probes. By direct counting of allele-specific DNA fragments, we have analyzed the frequencies of five majorDP genotypes (DPw1, DPw2, DPw3/6, DPw4, andDPw5), in a large number of Caucasoid rheumatoid arthritis (RA) patients (n=74), and controls (n=91). The predicted frequency
ofDP alleles in both patient and control groups was comparable to PLT-determinedDP allele frequencies in normal Caucasoids. However, the gene frequency ofDPw4 was increased in the RA patients, with 51% of the patients studied scoring asDPw4, 4 homozygotes. With the exception of one possible combination (DPw5 andDRw6) in the controls, no significant linkage disequilibrium was detected betweenDP andDR alleles in either patient or control groups. Thus the prevalence ofDPw4 in the RA patients is independent of any disease association with theDR loci, and may represent a new class II association with RA. 相似文献
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People are increasingly trying to multitask while walking. Text messaging while walking is a significant area for concern. The number of text messages sent is expected to be more than 8 trillion in 2012. Texting is becoming so commonplace that people use this technology while engaged in other activities. The dangers of multitasking have hit the streets as people are becoming involved in more accidents while walking as they text on mobile phones. This simulation activity measures a student's ability to multitask by texting and walking. The activity simulates walking in the real world and is best suited for middle school students. Additional activities, after completing the simulation, will challenge middle school students to learn more about multitasking globally through scientific inquiry researched on the Internet. The students will use language arts skills to generate a report or presentation to share with classmates. Their findings will give the entire class a cultural perspective on accident statistical comparisons between different countries. 相似文献
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The activity described in this article engages students in learning about proper meat storage procedures by using the Internet. They apply their knowledge practically through creation of a pamphlet to be displayed in their kitchen at home and a follow-up report on their parents’ kitchen procedures; they may also participate in a classic food storage experiment. This activity is well suited for elementary school children in the second through fourth grades and promotes all basic STEM (science, technology, engineering, and math) concepts. Kitchen activities require all these concepts for successful and safe outcomes. The examination of food storage devices references engineering, and technology is used for the research and pamphlet creation. The section on bacteria introduces life sciences, and physical sciences come into play through the discussion of heat inducing change in the meats. Math skills are integral to the reference table containing temperatures and times. 相似文献
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Alexandros A. Karamanlidis Elena Drosopoulou Miguel de Gabriel Hernando Lazaros Georgiadis Lambros Krambokoukis Stavri Pllaha Andreas Zedrosser Zacharias Scouras 《European Journal of Wildlife Research》2010,56(5):693-702
One difficulty in the conservation of endangered wildlife is the lack of reliable information on its status. This lack of
knowledge can often be attributed to financial and logistic constraints as well as the lack of trained personnel to collect
data. We test a simple method to study bears in the southern Balkans by inspecting power poles, which are used by bears for
marking and rubbing purposes. We created a network of barbed-wire fitted poles for the collection of hair samples, evenly
distributed throughout six study areas. During 87 sampling sessions in the main study area, we collected 191 samples and identified
six microsatellite loci that were variable enough for individual bear identification. The most and best-quality hair samples
were collected during the mating period, and DNA was most successfully extracted from samples remaining <4 weeks in the field.
In the six study areas, we identified 47 bears. An advantage of using power poles for hair sampling is their availability
and accessibility; no bait is required, and the network can be easily set up. A drawback may be an unequal capture probability
of sex and age classes of bears. Despite this limitation, using power poles proved to be a simple and cheap method for the
noninvasive genetic study of bears that did not require any prior knowledge on habitat use and activity patterns. The method
is suitable for large-scale surveys to estimate distribution and relative densities of bears and could also be applied for
studying other species. 相似文献
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Sakkas LI Xu B Artlett CM Lu S Jimenez SA Platsoucas CD 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(7):3649-3659
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The solution of the shortest path problem in biochemical systems constitutes an important step for studies of their evolution. In this paper, a linear programming (LP) algorithm for calculating minimal pathway distances in metabolic networks is studied. Minimal pathway distances are identified as the smallest number of metabolic steps separating two enzymes in metabolic pathways. The algorithm deals effectively with circularity and reaction directionality. The applicability of the algorithm is illustrated by calculating the minimal pathway distances for Escherichia coli small molecule metabolism enzymes, and then considering their correlations with genome distance (distance separating two genes on a chromosome) and enzyme function (as characterised by enzyme commission number). The results illustrate the effectiveness of the LP model. In addition, the data confirm that propinquity of genes on the genome implies similarity in function (as determined by co-involvement in the same region of the metabolic network), but suggest that no correlation exists between pathway distance and enzyme function. These findings offer insight into the probable mechanism of pathway evolution. 相似文献
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