商业智能 职业发展新蓝海

读了贵刊上期《商业智能进入人才储备期》一文,感觉自己的职业发展又多了一条道路。     

Multiplex qualitative PCR assay for identification of genetically modified canola events and real-time event-specific PCR assay for quantification of the GT73 canola event

Genetically modified (GM) canola is the most widely grown oilseed crop in Canada. At this time, commercially produced GM canola cultivars in Canada have the events GT73/RT73 and Ms8xRf3. Commercial seed sale of canola cultivars containing the GM events such as OXY235 and T45 has been discontinued. Adventitious presence of GM seeds and grains in non-GM grains is a concern for international grain trade, and development of effective detection methods is important. A multiplex qualitative PCR procedure was established for the detection of the GM canola events OXY235, Ms8xRf3, T45 and GT73. The presence of the GM canola events was also successfully detected in ground spiked wheat and barley grain samples prepared at 0.1%, 0.5% and 1.0% levels (w/w). The GT73 real-time PCR assay was successfully used to quantify DNA extracted from spiked ground canola samples consisting of 5%, 1%, 0.5% and 0.1% GT73 (w/w).     

Development of a polymerase chain reaction assay for detection of three canola transgenes

Many countries are developing or implementing regulatory requirements to monitor for the presence of genetically modified (GM) materials in seeds, grain, and derived food products using DNA and protein-based methods. There is no published report on the detection of different GM transgenes in canola, and this study is aimed at developing qualitative PCR methods for the three major GM transgenes commercially available in canola. Primer sequences were generated from Gen-Bank and previously published information to develop a polymerase chain reaction (PCR) detection method for Roundup Ready (glyphosate tolerance, GT73 event), Liberty Link (glufosinate ammonium tolerance, HCN92 event), and BX (Bromoxynil tolerance, OXY235 event) canola varieties. On using PCR, two primer pairs for each of the GT73 and HCN92 and one primer pair for OXY235 amplified specific amplicons for the three GM transgenes. All three GM transgenes were detected simultaneously by multiplexing the five primer pairs in a single PCR reaction. Multiplexing of the five primer pairs for DNA prepared at 1% (one GM seed in 99 non-GM seeds) and 0.5% (one GM seed in 199 non-GM seeds) levels generated the expected DNA fragments for GT73, HCN92, and OXY235. This information will lay the groundwork for the development of a quantitative PCR assay for canola transgenic events.     

Wheat Starch Modification Through Biotechnology

Natural mutations that affect the amylose/amylopectin ratio in starch are unlikely to develop naturally in wheat due to its allohexaploid genome (2n=6x; AABBDD). One of the strategies to modify wheat starch structure involves identification of germplasms with null alleles for starch biosynthetic genes, followed by exchange of functional alleles with the identified null alleles through classical plant breeding. This technique has successfully been used to combine the three null alleles for granule-bound starch synthase I (GBSSI) to develop a wheat line that produces amylopectin-rich (>95%) starch (waxy starch). Another strategy to alter expression levels of starch biosynthetic genes employs recent advances in molecular biology and genetic engineering of wheat. For this approach, various monocot vectors have been developed that drive expression of wheat starch branching enzyme I (SBEI) cDNA sequences in the anti-sense orientation. Several of the wheat cell lines transformed with the anti-sense vectors express branching enzyme (BE) activity at a significantly lower level than non-transformed cells. One transgenic wheat plant expressing the anti-sense SBEI RNA produces a ten-fold lower level of BE activity in kernels than wild-type wheat. Analysis of starch produced from the transgenic plant shows that starch structure and properties have been altered.     

Linking farm diversification to household diet diversification: evidence from a sample of Kenyan ultra-poor farmers

Starting with a conceptual framework adapted from Herforth and Harris (2013), we analyzed the nexus between farm production diversification and household diet diversity using data collected in 2011 for evaluation of the welfare and economic impacts of Kenya’s Cash Transfer for Orphans and Vulnerable Children (CT-OVC). We used a sample of 1,353 households drawn from six districts of western Kenya to test the hypotheses that on-farm production diversification correlates with household diet diversification and some production activities have stronger association with diet diversification than others in the context of ultra-poor, labor constrained families living in rural Kenya. Approximately 67 % of the sample households received cash transfers through the CT-OVC programme. Production diversification was positively and significantly associated with household diet diversification, with livestock ownership more strongly correlated than crop production. Poultry production had the most compelling correlation, followed by pulses. In both cases, the association was most plausibly attributed to an income effect rather than production-for-own consumption. These findings suggest that supporting investments in diversified livelihood systems in general and in small livestock assets such as poultry, sheep and goats in particular are viable interventions for the improvement of household food security and nutrition for very poor, marginalized smallholders. Under semi-autarkic smallholder agriculture, a diversification strategy, which integrates crop and livestock production, not only adds value directly via increasing diet diversity and quality and indirectly via income effects but also serves as a risk management instrument, protecting against weather and market shocks, and contributing to biodiversity and sustainable land management.     

Simultaneous detection by PCR of Escherichia coli, Listeria monocytogenes and Salmonella typhimurium in artificially inoculated wheat grain

A multiplex PCR procedure was established to detect Escherichia coli, Listeria monocytogenes and Salmonella typhimurium in artificially inoculated wheat grain. The PCR protocol with an enrichment step successfully detected all three organisms inoculated together in non-autoclaved wheat grain. After a one day enrichment, E. coli, L. monocytogenes and S. typhimurium were detected at levels of 56, 1800 and <54 CFU/mL, respectively, in the initial sample. For L. monocytogenes, an improved detection limit of <62 CFU/mL was achieved using singleplex PCR. For autoclaved wheat grain inoculated with the three bacterial strains individually, a detection limit of 3 CFU/mL was achieved after an enrichment step. The ability to test for the three bacteria simultaneously will save time and increase the ability to assure grain quality.     

Frequent Absence of GBSS 1 B Isoprotein in Endosperm Starch of Canadian Wheat Cultivars

Granule bound starch synthase 1 (GBSS 1) is an enzyme involved in amylose synthesis, and it is encoded at the waxy loci in wheat. Mutations have been reported for three GBSS1 loci in wheat. Mutations at wheat GBSS 1 loci result in the absence of GBSS 1 isoproteins with concomitant reduction in the amylose concentrations of endosperm starch. A recent survey of Canadian wheat cultivars detected the frequent absence of GBSS1 B isoprotein in endosperm starch granules. This was likely a result of many Canadian spring wheat cultivars having common parents, which have a mutation at the GBSS1 B locus.     

Possibilities and limitations of artificial neural networks for subpixel mapping of land cover

Although developments in remote sensing have greatly improved land cover mapping, the mixed pixel problem has not yet been fully addressed. Soft classification techniques have been introduced to address the problem, but they do not show the spatial location of the class proportions in a pixel. Subpixel mapping has been introduced to address the drawbacks of soft classifications. In this work, the feedforward backpropagating neural network (FFBPNN) was used for subpixel mapping. A set of class proportion images, which are to be treated as soft classification results, were created from a high spatial resolution (25 m) land cover dataset. For this purpose, the land cover dataset was aggregated both thematically (into two, four or eight land cover classes) and spatially (into proportion images with pixel sizes of 75, 150 and 300 m). This resulted in nine different combinations that were considered here as study cases. Several FFBPNNs were trained using these proportion images and the original land cover dataset (which was used as a target). Subsequently, the best networks were used to reconstruct high spatial resolution land cover maps of two heterogeneous areas in the south of The Netherlands. The overall accuracies obtained revealed that the networks were influenced by the spatial frequency, shape and size of the different land cover types. Moreover, it was revealed that most of the errors were on the class boundaries where highly mixed pixels are to be expected. The accuracies spanned a wide range of values depending on the complexity of the cases. Although it was not possible to exhaustively explore all network architectures, the results demonstrate the potential of the FFBPNN for subpixel mapping.     

Phytoplankton composition and biomass in tropical soda Lake Shala: seasonal changes in response to environmental drivers

Although soda lakes are valuable, sensitive aquatic resources where phytoplankton play a decisive role for the entire ecological functions, they are among the least‐studied ecosystems. Seasonal variations in phytoplankton composition, abundance and biomass in relation to some environmental parameters of the little known, deep, large, volcanic and saline–alkaline Lake Shala were investigated over an annual cycle. The lake phytoplankton community consisted of relatively diverse taxa (23) belonging to Bacillariophyceae, Cryptophyta, Cyanoprokaryota and Dinophyta. Bacillariophyceae and Cryptophyta were the dominant groups throughout the annual cycle, accounting for about 57% and 22% of the total number of species, and 28% and 69% of the total abundance of the phytoplankton community, respectively. Cryptomonas spp. were most abundant throughout nearly all months, contributing about 59%–95% of total phytoplankton abundance, followed by Thalassiosira sp. (1%–35%). The chlorophyll‐a concentration, as a proxy for algal biomass, was generally low (mean 17 μg L^?1), exhibiting only small seasonal variation. The strong, inverse relation of chlorophyll‐a with water transparency (r = ?0.69; n = 11) and the persistent dominance of species adapted to low‐light conditions and mixing suggest the overriding importance of these factors in controlling the lake's phytoplankton. The results of the present study generally suggest the phytoplankton composition and biomass in Lake Shala exhibited muted seasonal changes, despite the environmental perturbations, probably because of the lake's high buffering capacity against allochthonous impacts because of its voluminous nature.     

Species-specific PCR-based assays for the detection of Fusarium species and a comparison with the whole seed agar plate method and trichothecene analysis

Species-specific PCR was used for the identification of nine Fusarium species in pure mycelial culture. A PCR-based method was compared with the whole seed agar plate method and trichothecene analysis for three toxin-producing Fusarium species using 85 grain samples of wheat, barley, oat, corn and rye. A simple SDS-based DNA extraction system followed by potassium acetate precipitation resulted in consistent PCR amplification of DNA fragments from cultures and grain samples. The species-specific PCR assays correctly identified pure cultures of Fusarium avenaceum ssp. avenaceum (9 isolates), Fusarium acuminatum ssp. acuminatum (12 isolates), Fusarium crookwellense (7 isolates), Fusarium culmorum (12 isolates), Fusarium equiseti (11 isolates), Fusarium graminearum (77 isolates), Fusarium poae (10 isolates), Fusarium pseudograminearum (23 isolates), and Fusarium sporotrichioides (10 isolates). Multiplex PCR was developed for the simultaneous detection of F. culmorum, F. graminearum and F. sporotrichioides, the three most important trichothecene producing species in Canada. In grain samples, results of PCR assays for these same three species related well with whole seed agar plate method results and determination of Fusarium trichothecenes. The PCR assay described in this study can be used for routine detection and identification of Fusarium spp. in Canada.