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41.
Ginette Séguin‐Swartz Jacqueline A. Nettleton Connie Sauder Suzanne I. Warwick Richard K. Gugel 《Plant Breeding》2013,132(4):390-396
The potential for gene flow between Camelina sativa, a promising edible and industrial oil crop in Canada, and its wild North American relatives C. alyssum, C. microcarpa and C. rumelica subsp. rumelica, was investigated. Sequence analysis of the nuclear ribosomal internal transcribed spacer region (ITS) was used to differentiate Camelina species and/or accession‐specific nucleotide markers and identify interspecific F1 hybrids. ITS analysis identified hybrids in progeny of C. alyssum × C. sativa, C. microcarpa accession 36010 × C. sativa and C. sativa × C. rumelica subsp. rumelica. Seed set on C. alyssum × C. sativa F1 and F2 progeny was similar to the parents; few seeds were produced on hybrid progeny of C. microcarpa accession 36010 × C. sativa and C. sativa × C. rumelica subsp. rumelica. The study provided evidence that should the species have sympatric distributions and overlapping flowering periods, gene flow between C. sativa and its wild North American relatives is possible and that it would most likely occur with C. alyssum given the high fertility of the F1 hybrids recovered. 相似文献
42.
Arsenic mobility and groundwater extraction in Bangladesh 总被引:13,自引:0,他引:13
Harvey CF Swartz CH Badruzzaman AB Keon-Blute N Yu W Ali MA Jay J Beckie R Niedan V Brabander D Oates PM Ashfaque KN Islam S Hemond HF Ahmed MF 《Science (New York, N.Y.)》2002,298(5598):1602-1606
High levels of arsenic in well water are causing widespread poisoning in Bangladesh. In a typical aquifer in southern Bangladesh, chemical data imply that arsenic mobilization is associated with recent inflow of carbon. High concentrations of radiocarbon-young methane indicate that young carbon has driven recent biogeochemical processes, and irrigation pumping is sufficient to have drawn water to the depth where dissolved arsenic is at a maximum. The results of field injection of molasses, nitrate, and low-arsenic water show that organic carbon or its degradation products may quickly mobilize arsenic, oxidants may lower arsenic concentrations, and sorption of arsenic is limited by saturation of aquifer materials. 相似文献
43.
Albert Chakona Gavin Gouws Wilbert T. Kadye Martine S. Jordaan Ernst R. Swartz 《水产资源保护:海洋与淡水生态系统》2020,30(1):144-158
- Understanding historical distribution patterns of freshwater fishes prior to human impacts is crucial for informing effective strategies for biodiversity conservation. However, incomplete information on species occurrence records, the existence of cryptic species and sensitivity to small sample sizes limit the application of historical records in natural history collections as well as conventional species distribution modelling algorithms to infer past distributions of species.
- This study used molecular data as an alternative and objective approach to reconstruct the historical distribution ranges of four stream fishes from the Breede River system in the Cape Fold Ecoregion, a global hotspot of imperilled endemic freshwater biodiversity in southern Africa.
- The study used 249 occurrence records and 208 mitochondrial cytochrome b sequences to reconstruct the potential historical ranges of four taxa: Galaxias sp. ‘zebratus nebula', Galaxias sp. ‘zebratus Riviersonderend', Pseudobarbus sp. ‘burchelli Breede' and Pseudobarbus skeltoni.
- All four taxa historically had broader distribution ranges across the Breede River system before human impacts, but they have suffered severe attrition as the main‐stem populations have been extirpated.
- The severe decline in the historical ranges of these four taxa is a result of multiple impacts, particularly hydrological modification, habitat degradation and the introduction of non‐native species, which are also global challenges for freshwater ecosystems.
- The approach presented in this study has great potential for reconstructing historical ranges of stream‐dwelling taxa from disparate regions where fragmentation has resulted from human‐mediated impacts. This information is crucial for identifying appropriate conservation strategies such as river rehabilitation and eradication of non‐native species, as well as guiding reintroductions and informing assisted gene flow where these are deemed necessary interventions.
44.
Swartz TE Tseng TS Frederickson MA Paris G Comerci DJ Rajashekara G Kim JG Mudgett MB Splitter GA Ugalde RA Goldbaum FA Briggs WR Bogomolni RA 《Science (New York, N.Y.)》2007,317(5841):1090-1093
Histidine kinases, used for environmental sensing by bacterial two-component systems, are involved in regulation of bacterial gene expression, chemotaxis, phototaxis, and virulence. Flavin-containing domains function as light-sensory modules in plant and algal phototropins and in fungal blue-light receptors. We have discovered that the prokaryotes Brucella melitensis, Brucella abortus, Erythrobacter litoralis, and Pseudomonas syringae contain light-activated histidine kinases that bind a flavin chromophore and undergo photochemistry indicative of cysteinyl-flavin adduct formation. Infection of macrophages by B. abortus was stimulated by light in the wild type but was limited in photochemically inactive and null mutants, indicating that the flavin-containing histidine kinase functions as a photoreceptor regulating B. abortus virulence. 相似文献