EFFECTS OF ISOLATION DISTANCE ON CONTAMINATION IN SWEETCLOVER

1972 ◽  
Vol 52 (4) ◽  
pp. 517-524 ◽  
Author(s):  
B. P. GOPLEN ◽  
D. A. COOKE ◽  
P. PANKIW
Keyword(s):  
Honey Bees ◽  
Genetic Purity ◽  
Isolation Distance ◽  
Isolation Distances ◽  
Contamination Levels ◽  
High Level

The recessive low coumarin gene cu was used as a marker to study the effects of isolation distance on contamination levels in sweetclover pollinated by honey bees. A 46-m isolation distance was found inadequate to maintain a high level of genetic purity. Considerable contamination from crossing resulted with isolation distances from 46 to 804 m when there was little competitive bloom from other entomophilous crops. A highly attractive and competitive crop of rapeseed appeared to serve as a very effective isolation barrier to minimize contamination. A higher amount of contamination occurred in the borders of the low-coumarin isolation plots of one test. The results of this study are sufficient to question the existing isolation standards for sweetclover, but are not adequate to formulate new standards.

EFFECTIVENESS OF ISOLATION DISTANCE IN TURNIP RAPE

1978 ◽  
Vol 58 (2) ◽  
pp. 427-434 ◽  
Author(s):  
G. R. STRINGAM ◽  
R. K. DOWNEY
Keyword(s):  
Certified Seed ◽  
Brassica Campestris ◽  
Border Effects ◽  
Turnip Rape ◽  
Contaminant Source ◽  
Isolation Distance ◽  
Spatial Isolation ◽  
Isolation Requirements ◽  
Isolation Distances ◽  
Contamination Levels

Isolation distances for turnip rape (Brassica campestris L.) were studied using the recessive genetic marker yg-7. Average contamination levels from six tests over 2 yr were 8.5, 5.8, and 3.7% at isolation distances of 46, 137, and 366 m, respectively. The 46- and 137-m distances were judged to be inadequate, and even the 366-m distance showed greater contamination levels than desirable. No significant border effects were observed and there were no detectable differences in contamination attributable to directional orientation of the isolation blocks with the contaminant source. The data suggest that the 50- and 100-m isolation requirements in Canada for Certified seed production of turnip rape be re-examined and that border removal in lieu of spatial isolation be seriously questioned.

scholarly journals SNP- Based Assessment of Genetic Purity and Diversity in Maize Hybrid Breeding

2021 ◽  
Author(s):  
Chimwemwe Josia ◽  
Kingstone Mashingaidze ◽  
Assefa B. Amelework ◽  
Aleck Kondwakwenda ◽  
Cousin Musvosvi ◽  
...  
Keyword(s):  
Polymorphic Information Content ◽  
Inbred Lines ◽  
Genetic Distances ◽  
Snp Markers ◽  
Hybrid Breeding ◽  
Maize Breeding ◽  
Genetic Purity ◽  
Maize Hybrid ◽  
Dh Lines ◽  
High Level

AbstractAssessment of genetic purity of inbred lines and their resultant F1 hybrids is an essential quality control check in maize hybrid breeding, variety release and seed production. In this study, genetic purity, parent-offspring relationship and diversity among the inbred lines were assessed using 92 single-nucleotide polymorphism (SNP) markers. A total of 188 maize genotypes, comprising of 26 inbred lines, four doubled haploid (DH) lines and 158 single-cross maize hybrids were investigated in this study using Kompetitive Allele Specific Polymerase Chain Reaction (KASP) genotyping assays. The bi-allelic data was analyzed for genetic purity and diversity parameters using GenAlex software. The SNP markers were highly polymorphic and 90% had polymorphic information content (PIC) values of > 0.3. Pairwise genetic distances among the lines ranged from 0.05 to 0.56, indicating a high level of dissimilarity among the inbred lines. Maximum genetic distance of (0.56) was observed for CKDHL0089, CML443 and CB323, while the lowest (0.05) was between I-42 and I-40. The majority (67%) of the inbred lines studied were genetically pure with residual heterozygosity of <5%, while only 33% were had heterozygosity levels of >5%. Inbred lines, which were not pure, require purification through further inbreeding. Cluster analysis partitioned the lines into three distinct genetic clusters with the potential to contribute new beneficial alleles to the maize breeding program. Out of the 68 hybrids (43%) that passed the parent-offspring test, seven hybrids namely; SCHP29, SCHP95, SCHP94, SCHP134, SCHP44, SCHP114 and SCHP126, were selected as potential candidates for further evaluation and release due to their outstanding yield performance.

scholarly journals Isolation distance between municipal solid waste landfills and drinking water wells for bacteria attenuation and safe drinking

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rui Xiang ◽  
Ya Xu ◽  
Yu-Qiang Liu ◽  
Guo-Yuan Lei ◽  
Jing-Cai Liu ◽  
...  
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Transport Model ◽  
Environmental Safety ◽  
Aeration Zone ◽  
Water Wells ◽  
Isolation Distance ◽  
Municipal Solid Waste Landfills ◽  
Isolation Requirements ◽  
Isolation Distances

AbstractGroundwater pollution and human health risks caused by leachate leakage have become a worldwide environmental problem, and the harm and influence of bacteria in leachate have received increased attention. Setting the isolation distance between landfill sites and groundwater isolation targets is particularly important. Firstly, the intensity model of pollutant leakage source and solute transport model were established for the isolation of pathogenic Escherichia coli. Then, the migration, removal and reduction of bacteria in the aerated zone and ground were simulated. Finally, the isolation distance was calculated based on the acceptable water quality limits, and the influence of hydrogeological arameters was analyzed based on the parameter uncertainty. The results of this study suggest that the isolation distances vary widely ranging from 106 m–5.46 km in sand aquifers, 292 m–13.5 km in gravel aquifers and 2.4–58.7 km in coarse gravel aquifers. The gradient change of groundwater from 0.001 to 0.05 resulted in the isolation distance at the highest gradient position being 2–30 times greater than that at the lowest gradient position. There was a difference in the influence of the thickness of the vadose zone. For example, under the same conditions, with the increase of the thickness of the aeration zone, the isolation distance will be reduced by 1.5–5 times, or under the same thickness of the aeration zone, the isolation distance will be significantly shortened. Accordingly, this needs to be determined based on specific safety isolation requirements. In conclusion, this research has important guiding significance for the environmental safety assessment technology of municipal solid waste landfill.

scholarly journals Isolation of Aspergillus ochraceus and Production of Ochratoxin in Coffee Samples

2015 ◽  
Vol 15 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Pratikshya Pandit ◽  
Om Prakash Panta ◽  
Tika Bahadur Karki
Keyword(s):  
Animal Health ◽  
Good Condition ◽  
Fungal Growth ◽  
High Load ◽  
Aspergillus Ochraceus ◽  
Potential Hazard ◽  
High Production ◽  
Contamination Levels ◽  
High Level ◽  
Layer Chromatography

The occurrence of mycotoxins in foods and feeds has long been recognized as a potential hazard for human and animal health due to their severe toxic and carcinogenic properties. Among various mycotoxins, ochratoxin A (OTA) is the most hazardous one because of its serval contamination cases in the world. In this study contamination levels of Aspergillus ochraceus in coffee samples were assessed, where two strains of it were isolated from 65 coffee samples. They were confirmed by using Czapeck yeast extract agar (CYA). Fermentation was carried out for ochratoxin production at different moisture levels: 20%, 40% and 60% by using coffee as a substrate. The extract was assayed for the presence of ochratoxin by thin layer chromatography (TLC). Results showed that high production of this toxin (402 ppb) was obtained in coffee containing 60% of moisture after 19 days of incubation period with high load of fungal growth and the effect of roasting on coffee containing ochratoxin was observed where the level of it was decreased after roasting. It can be concluded that coffee substrate with high level of moisture favored good condition for the growth of A. ochraceus and ochratoxin formation.DOI: http://dx.doi.org/10.3126/njst.v15i1.12030 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 133-138 

scholarly journals Honey Bee (Hymenoptera: Apidea) Pollen Forage in a Highly Cultivated Agroecosystem: Limited Diet Diversity and Its Relationship to Virus Resistance

2020 ◽  
Vol 113 (3) ◽  
pp. 1062-1072 ◽  
Author(s):  
Ge Zhang ◽  
Ashley L St. Clair ◽  
Adam Dolezal ◽  
Amy L Toth ◽  
Matthew O’Neal
Keyword(s):  
Viral Infection ◽  
Honey Bee ◽  
Honey Bees ◽  
Agricultural Landscapes ◽  
Diet Diversity ◽  
Immune Health ◽  
Pollen Traps ◽  
Abundance And Diversity ◽  
High Level ◽  
The Impact

Abstract Intensified agriculture reduces natural and seminatural habitats and plant diversity, reducing forage available to honey bees (Apis mellifera L. [Hymenoptera: Apidea]). In agricultural landscapes of Iowa, United States, we studied the impact of extrinsic agricultural intensification on the availability of pollen for honey bees by placing colonies next to soybean fields surrounded by either a low or high level of cultivation. The abundance and diversity of pollen returned to a colony were estimated by placing pollen traps on bee colonies during the summer and fall of 2015 and 2016. We observed no difference in abundance and diversity of pollen collected by colonies in either landscape, but abundance varied over time with significantly less collected in September. We explored if the most commonly collected pollen from these landscapes had the capacity to support honey bee immune health by testing if diets consisting of these pollens improved bee resistance to a viral infection. Compared to bees denied pollen, a mixture of pollen from the two most common plant taxa (Trifolium spp. L. [Fabales: Fabaceae] and Chimaechrista fasciculata (Michx.) Greene [Fabales: Fabaceae]) significantly reduced honey bee mortality induced by viral infection. These data suggest that a community of a few common plants was favored by honey bees, and when available, could be valuable for reducing mortality from a viral infection. Our data suggest a late season shortage of pollen may be ameliorated by additions of fall flowering plants, like goldenrod (Solidago spp. L. [Asterales: Asteraceae]) and sunflower (Helianthus, Heliopsis, and Silphium spp. [Asterales: Asteraceae]), as options for enhancing pollen availability and quality for honey bees in agricultural landscapes.

scholarly journals Effective isolation distance for prevention of cassava virus infections in Uganda

2020 ◽  
Vol 28 (s1) ◽  
pp. 1-13
Author(s):  
F. Kasule ◽  
P. Wasswa ◽  
S.B. Mukasa ◽  
A. Okiror ◽  
A.W. Mwang’ombe
Keyword(s):  
Tissue Culture ◽  
Agricultural Research ◽  
Block Design ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Viral Diseases ◽  
Virus Infections ◽  
Isolation Distance ◽  
Isolation Distances ◽  
Research Institute

Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) are the major viral diseases of cassava in Uganda. Although isolation distance of “50 m” has been recommended by MAAIF in Uganda for prevention of virus infections in crops, the minimum isolation distance has not been verified for effectiveness in cassava. This study assessed the effective isolation distance for management of viral diseases in cassava. Virus-clean cassava cultivars (NASE 03, NASE 14 and NAROCASS 1) from farmers’ fields were used as field sourced (FS) planting materials. Tissue culture (TC) material of the same cultivars were sourced from the National Crops Resources Research Institute and Makerere University Agricultural Research Institute tissue culture laboratories. Both FS and TC materials were tested at isolation distances of 50, 100, 150 and 250 m for virus prevention. The experiment was laid out in a randomised complete block design and was run for 12 months after planting (MAP). Mean CBSD/CMD prevalence significantly varied (P<0.05) among isolation distances in both FS and TC plants, and the 250 m isolation distance was the most effective in reducing disease prevalence. Across cultivars and planting material category at 12 MAP, the 50 m isolation distance had the highest foliar incidence for CBSD (29.2%) and CMD (16.1%); while severity for CBSD was 1.4 and 1.2 for CMD. At 250 m, all FS and TC plants had CBSD/CMD severity of 1.0 and 0% incidence. These results show that 250 m isolation distance can provide an option to disseminate popular, but CBSD/CMD susceptible cassava cultivars thereby manage CBSD/CMD.  

Out-crossing rates for 10 Canadian spring wheat cultivars

1996 ◽  
Vol 76 (3) ◽  
pp. 423-427 ◽  
Author(s):  
P. Hucl
Keyword(s):  
Spring Wheat ◽  
Triticum Aestivum L ◽  
Wheat Cultivars ◽  
Wheat Seed ◽  
Genetic Purity ◽  
Cross Pollination ◽  
Wheat Market ◽  
Single Spike ◽  
Isolation Distance ◽  
Market Class

The genetic purity of pedigreed wheat seed can be compromised by inter-cultivar cross-pollination. Common wheat (Triticum aestivum L.) is assumed to be highly self-pollinated, an assumption that has not been verified for more recent western Canadian spring wheat cultivars. This field study was designed to estimate the outcrossing (OC) rate in three market classes of spring wheat in each of 2 yr and to determine whether OC rates were associated with specific spike characteristics. Highest OC rates were detected for the cultivar Oslo (6.05%) followed by Rongotea (2.30%), Roblin (1.43%), Wildcat (1.35%), Biggar (1.05%) and Glenlea (0.95%). In contrast Katepwa and CDC Makwa had OC rates of 0.38 and 0.30%, respectively. The cultivars Oslo, Columbus, Roblin and Glenlea tended to have lower iodine pollen viabilities. Of those four cultivars, three had higher-than-average OC rates. No single spike characteristic was correlated with OC rate. However, the cultivars Oslo, Wildcat and Glenlea had high OC rates, low pollen staining and spikes which tapered at the extremeties. Furthermore, cultivars with higher OC rates tended to have a greater degree of spikelet opening at anthesis. The high levels of OC observed in this study could result in obvious off-types if morphologically diverse cultivars were grown in adjacent pedigreed seed fields. The current 3 to 10 m isolation distance for pedigreed wheat seed production may not be enough to ensure that OC is minimized. Key words: Cross-pollination, spring wheat, market class

scholarly journals SNP-based assessment of genetic purity and diversity in maize hybrid breeding

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0249505
Author(s):  
Chimwemwe Josia ◽  
Kingstone Mashingaidze ◽  
Assefa B. Amelework ◽  
Aleck Kondwakwenda ◽  
Cousin Musvosvi ◽  
...  
Keyword(s):  
Polymorphic Information Content ◽  
Inbred Lines ◽  
Genetic Distances ◽  
Snp Markers ◽  
Hybrid Breeding ◽  
Maize Breeding ◽  
Genetic Purity ◽  
Maize Hybrid ◽  
Dh Lines ◽  
High Level

Assessment of genetic purity of parental inbred lines and their resultant F1 hybrids is an essential quality control check in maize hybrid breeding, variety release and seed production. In this study, genetic purity, parent-offspring relationship and diversity among the inbred lines were assessed using 92 single-nucleotide polymorphism (SNP) markers. A total of 188 maize genotypes, comprising of 26 inbred lines, four doubled haploid (DH) lines and 158 single-cross maize hybrids were investigated in this study using Kompetitive Allele Specific Polymerase Chain Reaction (KASP) genotyping assays. The bi-allelic data was analyzed for genetic purity and diversity parameters using GenAlex software. The SNP markers were highly polymorphic and 90% had polymorphic information content (PIC) values of > 0.3. Pairwise genetic distances among the lines ranged from 0.05 to 0.56, indicating a high level of dissimilarity among the inbred lines. A maximum genetic distance of (0.56) was observed between inbred lines CKDHL0089 and CML443 while the lowest (0.05) was between I-42 and I-40. The majority (67%) of the inbred lines studied were genetically pure with residual heterozygosity of <5%, while only 33% had heterozygosity levels of >5%. Inbred lines, which were not pure, require purification through further inbreeding. Cluster analysis partitioned the lines into three distinct genetic clusters with the potential to contribute new beneficial alleles to the maize breeding program. Out of the 68 hybrids (43%) that passed the parent-offspring test, seven hybrids namely; SCHP29, SCHP95, SCHP94, SCHP134, SCHP44, SCHP114 and SCHP126, were selected as potential candidates for further evaluation and release due to their outstanding yield performance.

Genetic purity and testing technologies for seed quality: a company perspective

1998 ◽  
Vol 8 (2) ◽  
pp. 285-294 ◽  
Author(s):  
J. S. C. Smith ◽  
J. C. Register III
Keyword(s):  
Single Molecule ◽  
Seed Quality ◽  
Genetic Purity ◽  
Biochemical Methods ◽  
Crop Varieties ◽  
Select Group ◽  
Purity Testing ◽  
Length Polymorphisms ◽  
Micro Array ◽  
High Level

AbstractA high level of genetic purity in crop varieties must be achieved and maintained for agronomic performance as well as to encourage investment and innovation in plant breeding and to ensure that the improvements in productivity and quality imparted by breeders are delivered to the farmer and, ultimately, to the consumer. Traditionally, morphological comparisons have formed the basis for genetic purity evaluations. However, replicated field observations are time-consuming, expensive and unreliable. Morphology cannot provide information on the purity of specific genetic attributes that relate to grain quality or to pest or herbicide resistance bred into varieties. Biochemical assays, including isozymes, can distinguish varieties within several species. Isozymes have been routinely used in checking seed-lot purity in maize (Zea mays L.) for the past 20 years. Newer DNA-based technologies such as restriction fragment length polymorphisms and more recently developed methods that use the polymerase chain reaction can allow even more discriminative and faster identification of varieties. However, none of the DNA methods have replaced biochemical methods for seed purity assays, other than in a relatively select group of crops with very high seed value, due to their high datapoint cost. It will require further miniaturization, automation and enhanced capabilities to process numerous samples simultaneously before newly developed methods supplant biochemical methods for routine usage in purity testing. New varieties that have major genes for herbicide or insect resistance incorporated within them require purity assays during product development and following seed production of the commercial variety. Immunological or DNA sequence assays can be developed and automated systems are required to process hundreds of thousands of individuals. Ultra-high, micro-array technologies and single-molecule detection systems are now under development. These technologies offer the promise that adequate distinction and high sample throughput will be combined. New methods may eclipse the capabilities of biochemical methodologies, thereby potentially raising genetic purity standards and enabling farmers and consumers better to utilize and benefit from increasingly productive varieties that are bred from a more diverse base of genetic resources.

The Use of Rapid Indicators for the Detection of Organic Residues on Clinically Used Gastrointestinal Endoscopes with and without Visually Apparent Debris

2014 ◽  
Vol 35 (8) ◽  
pp. 987-994 ◽  
Author(s):  
Kavel H. Visrodia ◽  
Cori L. Ofstead ◽  
Hannah L. Yellin ◽  
Harry P. Wetzler ◽  
Pritish K. Tosh ◽  
...  
Keyword(s):  
Visual Inspection ◽  
Tertiary Care ◽  
Multidrug Resistant ◽  
Organic Residues ◽  
Multiple Components ◽  
Multidrug Resistant Organisms ◽  
Before And After ◽  
Contamination Levels ◽  
High Level ◽  
Monitoring Protocols

BackgroundOutbreaks of multidrug-resistant organisms have been linked to endoscope reprocessing lapses. Meticulous manual cleaning before high-level disinfection (HLD) is essential in reducing residual contamination that can interfere with HLD. Current reprocessing guidelines state that visual inspection is sufficient to confirm adequate cleaning.ObjectiveOur aim was to evaluate contamination of clinically used endoscopes, using visual inspection and rapid indicator tests before and after manual cleaning. A second objective was to determine which rapid indicator instruments and methods could be used for quality improvement initiatives in endoscope reprocessing.DesignClinical use study of endoscope reprocessing effectiveness.SettingTertiary care teaching hospital with an inpatient endoscopy center.MethodsResearchers sampled endoscopes used for gastrointestinal procedures before and after manual cleaning. The external surfaces and 1 channel of each endoscope were visually inspected and tested with rapid indicators to measure protein, blood, and adenosine triphosphate (ATP) contamination levels.ResultsMultiple components were sampled during 37 encounters with 12 unique endoscopes. All bedside-cleaned endoscopes had high levels of ATP and detectable blood or protein, whether or not any residue was visible. Although there was no visible residue on any endoscopes after manual cleaning, 82% had at least 1 positive rapid indicator test.ConclusionsRelying solely on visual inspection of endoscopes prior to HLD is insufficient to ensure reprocessing effectiveness. For quality assurance initiatives, tests of different endoscope components using more than 1 indicator may be necessary. Additional research is needed to validate specific monitoring protocols.

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