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LEAF School Posters by Minxiu (Spencer) Wang
The purpose of this rain garden project is to help Snohomish Conservation District and the Cities... more The purpose of this rain garden project is to help Snohomish Conservation District and the Cities of Edmonds and Lynnwood better understand Mandarin perspectives on rain gardens. Installing rain gardens in front yards will help filter the polluted stormwater before it runs into local water bodies. Rain gardens not only contribute to aesthetic, they also benefit the environment by slowing excess stormwater runoff into Puget Sound. This can improve water quality and the health of seafood coming from the Sound. The results we received from our online survey shows us clearly that majority of the people would like to install rain garden but with addition benefits either from financial help or future garden maintenance. All our participant are Mandarin Chinese, and Chinese people have the tendency to follow others/majority , so in this case getting other Chinese families involved in the same neighborhood around is also a key factor to success.
Papers by Minxiu (Spencer) Wang
Degenerative Retinal Diseases, 1997
Virology journal, 2015
Genome-wide RNAi screening has been widely used to identify host proteins involved in replication... more Genome-wide RNAi screening has been widely used to identify host proteins involved in replication and infection of different viruses, and numerous host factors are implicated in the replication cycles of these viruses, demonstrating the power of this approach. However, discrepancies on target identification of the same viruses by different groups suggest that high throughput RNAi screening strategies need to be carefully designed, developed and optimized prior to the large scale screening. Two genome-wide RNAi screens were performed in parallel against the entry of pseudotyped Marburg viruses and avian influenza virus H5N1 utilizing an HIV-1 based surrogate system, to identify host factors which are important for virus entry. A comparative analysis approach was employed in data analysis, which alleviated systematic positional effects and reduced the false positive number of virus-specific hits. The parallel nature of the strategy allows us to easily identify the host factors for a s...
Journal of Virology, 2015
ABSTRACTFiloviruses, including both Ebola virus (EBOV) and Marburg virus (MARV), can infect human... more ABSTRACTFiloviruses, including both Ebola virus (EBOV) and Marburg virus (MARV), can infect humans and other animals, causing hemorrhagic fever with a high mortality rate. Entry of these viruses into the host is mediated by a single filoviral glycoprotein (GP). GP is composed of two subunits: GP1, which is responsible for attachment and binding to receptor(s) on susceptible cells, and GP2, which mediates viral and cell membrane fusion. Although numerous host factors have been implicated in the entry process, the initial attachment receptor(s) has not been well defined. In this report, we demonstrate that exostosin 1 (EXT1), which is involved in biosynthesis of heparan sulfate (HS), plays a role in filovirus entry. Expression knockdown of EXT1 by small interfering RNAs (siRNAs) impairs GP-mediated pseudoviral entry and that of infectious EBOV and MARV in tissue cultured cells. Furthermore, HS, heparin, and other related glycosaminoglycans (GAGs), to different extents, can bind to and...
Zhonghua gan zang bing za zhi = Zhonghua ganzangbing zazhi = Chinese journal of hepatology, 2004
Lamivudine resistant HBV strains in Shenzhen were detected at multiple sites and in large amounts... more Lamivudine resistant HBV strains in Shenzhen were detected at multiple sites and in large amounts to understand further the distribution of lamivudine resistant mutants. 552 Hepatitis B patients's sera were examined using genechip method. Among them, 192 samples of lamivudine resistant mutant were further analyzed. In those 192 lamivudine resistant samples, 191 were YMDD mutants, 124 mutants of codon 528 and 9 mutants of codon 555. 88% YMDD mutants were multi-mutants of YVDD and codon 528; single mutants of YIDD; multi-mutants of YIDD and codon 528. 91% codon of YMDD mutants were GTG, ATT; the other 9% were ATA, ATC. These results suggest that mutants of codon 552 (YMDD) are core mutants. Mutants of codon 528 and 555 are incidental mutants, YVDD mutants always emerge with mutants of codon 528, but YIDD mutants appear differently. 9% YMDD mutants's codons are ATA or ATC. This may be the reason for the low positive rate shown by using the conventional PCR methods.
PLoS ONE, 2012
In influenza, the envelope protein hemagglutinin (HA) plays a critical role in viral entry by fir... more In influenza, the envelope protein hemagglutinin (HA) plays a critical role in viral entry by first binding to sialic acid receptors on the cell surface and subsequently mediating fusion of the viral and target membranes. In this work, the receptor binding properties of influenza A HA from different subtypes (H1 A/California/04/09, H5 A/Vietnam/1205/04, H5 A/ bar-headed goose/Qinghai/1A/05, and H9 A/Hong Kong/1073/99) have been characterized by NMR spectroscopy. Using saturation transfer difference (STD) NMR, we find that all HAs bind to the receptor analogs 2,3-sialyllactose and 2,6sialyllactose, with subtle differences in the binding mode. Using competition STD NMR, we determine the receptor preferences for the HA subtypes. We find that H5-Qinghai and H9-Hong Kong HA bind to both receptor analogs with similar affinity. On the other hand, H1 exhibits a clear preference for 2,6-sialyllactose while H5-Vietnam exhibits a clear preference for 2,3-sialyllactose. Together, these results are interpreted within the context of differences in both the amino acid sequence and structures of HA from the different subtypes in determining receptor preference.
Molecular Cancer Therapeutics, 2011
Journal of Virology, 2012
Influenza A virus glycoprotein hemagglutinin (HA) binds to host cell surface sialic acid (SA)-ter... more Influenza A virus glycoprotein hemagglutinin (HA) binds to host cell surface sialic acid (SA)-terminated sugars in glycoproteins to initiate viral entry. It is thought that avian influenza viruses preferentially bind to N-acetylneuraminic acid ␣3 (NeuAc␣3) sugars, while human influenza viruses exhibit a preference for NeuAc␣6-containing sugars. Thus, species-specific SA(s) is one of the determinants in viral host tropism. The SA binding pocket of the HA1 subunit has been extensively studied, and a number of residues important for receptor binding have been identified. In this study, we examined the potential roles of seven highly conserved HA surface-located amino acid residues in receptor binding and viral entry using an H5 subtype. Among them, mutant Y161A showed cell-type-dependent viral entry without obvious defects in HA protein expression or viral incorporation. This mutant also displayed dramatically different ability in agglutinating different animal erythrocytes. Oligosaccharide binding analysis showed that substituting alanine at Y161 of HA changed the SA binding preference from NeuAc to N-glycolylneuraminic acid (NeuGc). Rescued mutant Y161A viruses demonstrated a 5-to 10-fold growth defect, but they were robust in viral replication and plaque forming ability. Our results demonstrate that Y161 is a critical residue involved in recognition of different SA species. This residue may play a role in determining influenza virus host tropism.
Journal of Virology, 2014
Influenza viruses are a major public health threat worldwide, and options for antiviral therapy a... more Influenza viruses are a major public health threat worldwide, and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The influenza virus glycoprotein hemagglutinin (HA) plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a potential target for the development of anti-influenza drugs. Using pseudotype virus-based high-throughput screens, we have identified several new small molecules capable of inhibiting influenza virus entry. We prioritized two novel inhibitors, MBX2329 and MBX2546, with aminoalkyl phenol ether and sulfonamide scaffolds, respectively, that specifically inhibit HA-mediated viral entry. The two compounds (i) are potent (50% inhibitory concentration [IC 50 ] of 0.3 to 5.9 M); (ii) are selective (50% cytotoxicity concentration [CC 50 ] of >100 M), with selectivity
Journal of Biomolecular Screening, 2013
Alternative splicing (AS) is an efficient mechanism that involves the generation of transcriptome... more Alternative splicing (AS) is an efficient mechanism that involves the generation of transcriptome and protein diversity from a single gene. Defects in pre-messenger RNA (mRNA) splicing are an important cause of numerous diseases, including cancer. AS of pre-mRNA as a target for cancer therapy has not been well studied. We have reported previously that a splicing factor, polypyrimidine tract-binding protein (PTB), is overexpressed in ovarian tumors compared with matched normal controls, and knockdown of PTB expression by short-hairpin RNA impairs ovarian tumor cell growth, colony formation, and invasiveness. Given the complexity of PTB's molecular functions, a chemical method for controlling PTB activity might provide a therapeutic and experimental tool. However, no commercially available PTB inhibitors have yet been described. To expand our ability to find novel inhibitors, we developed a robust, fluorometric, cell-based high-throughput screening assay in 96-well plates that reports on the splicing activity of PTB. In an attempt to use the cells for large-scale chemical screens to identify PTB modulators, we established cell lines stably expressing the reporter gene. Our results suggest that this high-throughput assay could be used to identify small-molecule modulators of PTB activity. Based on these findings and the role that upregulated PTB has on cell proliferation and malignant properties of tumors, targeting PTB for inhibition with small molecules offers a promising strategy for cancer therapy.
Information Sciences, 2014
Entity aliases commonly exist. Accurately detecting these aliases plays a vital role in various a... more Entity aliases commonly exist. Accurately detecting these aliases plays a vital role in various applications. In particular, it is critical to detect the aliases that are intentionally hidden from the real identities, such as those of terrorists and frauds. Most existing work does not pay close attention to the aliases that have low/no string similarity to the given entities. In this paper, we propose a classifier that is based on active learning for detecting this type of aliasing. To minimize the cost of pair-wise comparison, a subset-based method is designed to restrict the selection within entity subsets. An active learning classifier is then employed in each entity subset to find the probability of whether a candidate is the alias of a given entity within the subset. After all of the results from the classifier are integrated, a list of aliases is returned for each given entity. For evaluation, we implemented four stateof-the-art methods and compared them with our proposed approach on three datasets. The results clearly demonstrate that this new active learning classifier is superior to those existing methods.
Growth Factors, 2011
Reg family proteins such as Reg1 and islet neogenesis-associated protein (INGAP) have long been i... more Reg family proteins such as Reg1 and islet neogenesis-associated protein (INGAP) have long been implicated in the growth and/or neogenesis of pancreatic islet cells. Recent reports further suggest similar roles to be played by new members such as Reg2, Reg3α, and Reg3β. We have studied their age-, isoform-, and tissue-specific expressions. RNA and protein were isolated from C57BL/6 mice aged 7, 30, and 90 days. Using real-time polymerase chain reaction, the levels of Reg gene expression in the pancreas were 20-600-fold higher than that in other tissues (≫duodenum>stomach>liver); gene expression of Reg2, Reg3α, and Reg3β was age dependent as it was hardly detectable at day 7, increased drastically at day 30, and significantly decreased at day 90; the levels of pancreatic proteins displayed similar age-dependent variations. Using dual-labeled immunofluorescence, Reg2, Reg3α, and Reg3β were abundantly expressed in most acinar cells of the pancreas, in contrast to INGAP which exhibited stepwise increases from day 7 to day 90 and colocalized with the α-cells. These new Reg genes were mainly expressed in the pancreas, with clear age-dependent and isoform-specific patterns.
Genome, 2002
We report molecular genetic linkage maps for an interspecific hybrid population of Populus, a mod... more We report molecular genetic linkage maps for an interspecific hybrid population of Populus, a model system in forest-tree biology. The hybrids were produced by crosses between P. deltoides (mother) and P. euramericana (father), which is a natural hybrid of P. deltoides (grandmother) and P. nigra (grandfather). Linkage analysis from 93 of the 450 backcross progeny grown in the field for 15 years was performed using random amplified polymorphic DNAs (RAPDs), amplified fragment length polymorphisms (AFLPs), and inter-simple sequence repeats (ISSRs). Of a total of 839 polymorphic markers identified, 560 (67%) were testcross markers heterozygous in one parent but null in the other (segregating 1:1), 206 (25%) were intercross dominant markers heterozygous in both parents (segregating 3:1), and the remaining 73 (9%) were 19 non-parental RAPD markers (segregating 1:1) and 54 codominant AFLP markers (segregating 1:1:1:1). A mixed set of the testcross markers, non-parental RAPD markers, and codominant AFLP markers was used to construct two linkage maps, one based on the P. deltoides (D) genome and the other based on P. euramericana (E). The two maps showed nearly complete coverage of the genome, spanning 3801 and 3452 cM, respectively. The availability of non-parental RAPD and codominant AFLP markers as orthologous genes allowed for a direct comparison of the rate of meiotic recombination between the two different parental species. Generally, the rate of meiotic recombination was greater for males than females in our interspecific poplar hybrids. The confounded effect of sexes and species causes the mean recombination distance of orthologous markers to be 11% longer for the father (P. euramericana; interspecific hybrid) than for the mother (P. deltoides; pure species). The linkage maps constructed and the interspecific poplar hybrid population in which clonal replicates for individual genotypes are available present a comprehensive foundation for future genomic studies and quantitative trait locus (QTL) identification.
Genetical Research, 2003
Growth trajectories are a biological process important to plant and animal breeding, and to evolu... more Growth trajectories are a biological process important to plant and animal breeding, and to evolutionary genetic studies. In this article, we report the detection of quantitative trait loci (QTLs) responsible for growth trajectories in poplars that are used as a model system for the study of forest biology. These QTLs were localized on a genetic linkage map of polymorphic markers using a statistical mapping method incorporating growth-curve models. The effects of the QTLs on growth are described as a function of age, so that age-specific changes in QTL effects can be readily projected throughout the entire growth process. The QTLs identified display increased effects on growth when trees age, yet the timing of QTL activation is earlier for stem height than diameter, which is consistent with the ecological viewpoint of canopy competition. The implications of the results for breeding and silviculture are discussed.
The purpose of this rain garden project is to help Snohomish Conservation District and the Cities... more The purpose of this rain garden project is to help Snohomish Conservation District and the Cities of Edmonds and Lynnwood better understand Mandarin perspectives on rain gardens. Installing rain gardens in front yards will help filter the polluted stormwater before it runs into local water bodies. Rain gardens not only contribute to aesthetic, they also benefit the environment by slowing excess stormwater runoff into Puget Sound. This can improve water quality and the health of seafood coming from the Sound. The results we received from our online survey shows us clearly that majority of the people would like to install rain garden but with addition benefits either from financial help or future garden maintenance. All our participant are Mandarin Chinese, and Chinese people have the tendency to follow others/majority , so in this case getting other Chinese families involved in the same neighborhood around is also a key factor to success.
Degenerative Retinal Diseases, 1997
Virology journal, 2015
Genome-wide RNAi screening has been widely used to identify host proteins involved in replication... more Genome-wide RNAi screening has been widely used to identify host proteins involved in replication and infection of different viruses, and numerous host factors are implicated in the replication cycles of these viruses, demonstrating the power of this approach. However, discrepancies on target identification of the same viruses by different groups suggest that high throughput RNAi screening strategies need to be carefully designed, developed and optimized prior to the large scale screening. Two genome-wide RNAi screens were performed in parallel against the entry of pseudotyped Marburg viruses and avian influenza virus H5N1 utilizing an HIV-1 based surrogate system, to identify host factors which are important for virus entry. A comparative analysis approach was employed in data analysis, which alleviated systematic positional effects and reduced the false positive number of virus-specific hits. The parallel nature of the strategy allows us to easily identify the host factors for a s...
Journal of Virology, 2015
ABSTRACTFiloviruses, including both Ebola virus (EBOV) and Marburg virus (MARV), can infect human... more ABSTRACTFiloviruses, including both Ebola virus (EBOV) and Marburg virus (MARV), can infect humans and other animals, causing hemorrhagic fever with a high mortality rate. Entry of these viruses into the host is mediated by a single filoviral glycoprotein (GP). GP is composed of two subunits: GP1, which is responsible for attachment and binding to receptor(s) on susceptible cells, and GP2, which mediates viral and cell membrane fusion. Although numerous host factors have been implicated in the entry process, the initial attachment receptor(s) has not been well defined. In this report, we demonstrate that exostosin 1 (EXT1), which is involved in biosynthesis of heparan sulfate (HS), plays a role in filovirus entry. Expression knockdown of EXT1 by small interfering RNAs (siRNAs) impairs GP-mediated pseudoviral entry and that of infectious EBOV and MARV in tissue cultured cells. Furthermore, HS, heparin, and other related glycosaminoglycans (GAGs), to different extents, can bind to and...
Zhonghua gan zang bing za zhi = Zhonghua ganzangbing zazhi = Chinese journal of hepatology, 2004
Lamivudine resistant HBV strains in Shenzhen were detected at multiple sites and in large amounts... more Lamivudine resistant HBV strains in Shenzhen were detected at multiple sites and in large amounts to understand further the distribution of lamivudine resistant mutants. 552 Hepatitis B patients's sera were examined using genechip method. Among them, 192 samples of lamivudine resistant mutant were further analyzed. In those 192 lamivudine resistant samples, 191 were YMDD mutants, 124 mutants of codon 528 and 9 mutants of codon 555. 88% YMDD mutants were multi-mutants of YVDD and codon 528; single mutants of YIDD; multi-mutants of YIDD and codon 528. 91% codon of YMDD mutants were GTG, ATT; the other 9% were ATA, ATC. These results suggest that mutants of codon 552 (YMDD) are core mutants. Mutants of codon 528 and 555 are incidental mutants, YVDD mutants always emerge with mutants of codon 528, but YIDD mutants appear differently. 9% YMDD mutants's codons are ATA or ATC. This may be the reason for the low positive rate shown by using the conventional PCR methods.
PLoS ONE, 2012
In influenza, the envelope protein hemagglutinin (HA) plays a critical role in viral entry by fir... more In influenza, the envelope protein hemagglutinin (HA) plays a critical role in viral entry by first binding to sialic acid receptors on the cell surface and subsequently mediating fusion of the viral and target membranes. In this work, the receptor binding properties of influenza A HA from different subtypes (H1 A/California/04/09, H5 A/Vietnam/1205/04, H5 A/ bar-headed goose/Qinghai/1A/05, and H9 A/Hong Kong/1073/99) have been characterized by NMR spectroscopy. Using saturation transfer difference (STD) NMR, we find that all HAs bind to the receptor analogs 2,3-sialyllactose and 2,6sialyllactose, with subtle differences in the binding mode. Using competition STD NMR, we determine the receptor preferences for the HA subtypes. We find that H5-Qinghai and H9-Hong Kong HA bind to both receptor analogs with similar affinity. On the other hand, H1 exhibits a clear preference for 2,6-sialyllactose while H5-Vietnam exhibits a clear preference for 2,3-sialyllactose. Together, these results are interpreted within the context of differences in both the amino acid sequence and structures of HA from the different subtypes in determining receptor preference.
Molecular Cancer Therapeutics, 2011
Journal of Virology, 2012
Influenza A virus glycoprotein hemagglutinin (HA) binds to host cell surface sialic acid (SA)-ter... more Influenza A virus glycoprotein hemagglutinin (HA) binds to host cell surface sialic acid (SA)-terminated sugars in glycoproteins to initiate viral entry. It is thought that avian influenza viruses preferentially bind to N-acetylneuraminic acid ␣3 (NeuAc␣3) sugars, while human influenza viruses exhibit a preference for NeuAc␣6-containing sugars. Thus, species-specific SA(s) is one of the determinants in viral host tropism. The SA binding pocket of the HA1 subunit has been extensively studied, and a number of residues important for receptor binding have been identified. In this study, we examined the potential roles of seven highly conserved HA surface-located amino acid residues in receptor binding and viral entry using an H5 subtype. Among them, mutant Y161A showed cell-type-dependent viral entry without obvious defects in HA protein expression or viral incorporation. This mutant also displayed dramatically different ability in agglutinating different animal erythrocytes. Oligosaccharide binding analysis showed that substituting alanine at Y161 of HA changed the SA binding preference from NeuAc to N-glycolylneuraminic acid (NeuGc). Rescued mutant Y161A viruses demonstrated a 5-to 10-fold growth defect, but they were robust in viral replication and plaque forming ability. Our results demonstrate that Y161 is a critical residue involved in recognition of different SA species. This residue may play a role in determining influenza virus host tropism.
Journal of Virology, 2014
Influenza viruses are a major public health threat worldwide, and options for antiviral therapy a... more Influenza viruses are a major public health threat worldwide, and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The influenza virus glycoprotein hemagglutinin (HA) plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a potential target for the development of anti-influenza drugs. Using pseudotype virus-based high-throughput screens, we have identified several new small molecules capable of inhibiting influenza virus entry. We prioritized two novel inhibitors, MBX2329 and MBX2546, with aminoalkyl phenol ether and sulfonamide scaffolds, respectively, that specifically inhibit HA-mediated viral entry. The two compounds (i) are potent (50% inhibitory concentration [IC 50 ] of 0.3 to 5.9 M); (ii) are selective (50% cytotoxicity concentration [CC 50 ] of >100 M), with selectivity
Journal of Biomolecular Screening, 2013
Alternative splicing (AS) is an efficient mechanism that involves the generation of transcriptome... more Alternative splicing (AS) is an efficient mechanism that involves the generation of transcriptome and protein diversity from a single gene. Defects in pre-messenger RNA (mRNA) splicing are an important cause of numerous diseases, including cancer. AS of pre-mRNA as a target for cancer therapy has not been well studied. We have reported previously that a splicing factor, polypyrimidine tract-binding protein (PTB), is overexpressed in ovarian tumors compared with matched normal controls, and knockdown of PTB expression by short-hairpin RNA impairs ovarian tumor cell growth, colony formation, and invasiveness. Given the complexity of PTB's molecular functions, a chemical method for controlling PTB activity might provide a therapeutic and experimental tool. However, no commercially available PTB inhibitors have yet been described. To expand our ability to find novel inhibitors, we developed a robust, fluorometric, cell-based high-throughput screening assay in 96-well plates that reports on the splicing activity of PTB. In an attempt to use the cells for large-scale chemical screens to identify PTB modulators, we established cell lines stably expressing the reporter gene. Our results suggest that this high-throughput assay could be used to identify small-molecule modulators of PTB activity. Based on these findings and the role that upregulated PTB has on cell proliferation and malignant properties of tumors, targeting PTB for inhibition with small molecules offers a promising strategy for cancer therapy.
Information Sciences, 2014
Entity aliases commonly exist. Accurately detecting these aliases plays a vital role in various a... more Entity aliases commonly exist. Accurately detecting these aliases plays a vital role in various applications. In particular, it is critical to detect the aliases that are intentionally hidden from the real identities, such as those of terrorists and frauds. Most existing work does not pay close attention to the aliases that have low/no string similarity to the given entities. In this paper, we propose a classifier that is based on active learning for detecting this type of aliasing. To minimize the cost of pair-wise comparison, a subset-based method is designed to restrict the selection within entity subsets. An active learning classifier is then employed in each entity subset to find the probability of whether a candidate is the alias of a given entity within the subset. After all of the results from the classifier are integrated, a list of aliases is returned for each given entity. For evaluation, we implemented four stateof-the-art methods and compared them with our proposed approach on three datasets. The results clearly demonstrate that this new active learning classifier is superior to those existing methods.
Growth Factors, 2011
Reg family proteins such as Reg1 and islet neogenesis-associated protein (INGAP) have long been i... more Reg family proteins such as Reg1 and islet neogenesis-associated protein (INGAP) have long been implicated in the growth and/or neogenesis of pancreatic islet cells. Recent reports further suggest similar roles to be played by new members such as Reg2, Reg3α, and Reg3β. We have studied their age-, isoform-, and tissue-specific expressions. RNA and protein were isolated from C57BL/6 mice aged 7, 30, and 90 days. Using real-time polymerase chain reaction, the levels of Reg gene expression in the pancreas were 20-600-fold higher than that in other tissues (≫duodenum>stomach>liver); gene expression of Reg2, Reg3α, and Reg3β was age dependent as it was hardly detectable at day 7, increased drastically at day 30, and significantly decreased at day 90; the levels of pancreatic proteins displayed similar age-dependent variations. Using dual-labeled immunofluorescence, Reg2, Reg3α, and Reg3β were abundantly expressed in most acinar cells of the pancreas, in contrast to INGAP which exhibited stepwise increases from day 7 to day 90 and colocalized with the α-cells. These new Reg genes were mainly expressed in the pancreas, with clear age-dependent and isoform-specific patterns.
Genome, 2002
We report molecular genetic linkage maps for an interspecific hybrid population of Populus, a mod... more We report molecular genetic linkage maps for an interspecific hybrid population of Populus, a model system in forest-tree biology. The hybrids were produced by crosses between P. deltoides (mother) and P. euramericana (father), which is a natural hybrid of P. deltoides (grandmother) and P. nigra (grandfather). Linkage analysis from 93 of the 450 backcross progeny grown in the field for 15 years was performed using random amplified polymorphic DNAs (RAPDs), amplified fragment length polymorphisms (AFLPs), and inter-simple sequence repeats (ISSRs). Of a total of 839 polymorphic markers identified, 560 (67%) were testcross markers heterozygous in one parent but null in the other (segregating 1:1), 206 (25%) were intercross dominant markers heterozygous in both parents (segregating 3:1), and the remaining 73 (9%) were 19 non-parental RAPD markers (segregating 1:1) and 54 codominant AFLP markers (segregating 1:1:1:1). A mixed set of the testcross markers, non-parental RAPD markers, and codominant AFLP markers was used to construct two linkage maps, one based on the P. deltoides (D) genome and the other based on P. euramericana (E). The two maps showed nearly complete coverage of the genome, spanning 3801 and 3452 cM, respectively. The availability of non-parental RAPD and codominant AFLP markers as orthologous genes allowed for a direct comparison of the rate of meiotic recombination between the two different parental species. Generally, the rate of meiotic recombination was greater for males than females in our interspecific poplar hybrids. The confounded effect of sexes and species causes the mean recombination distance of orthologous markers to be 11% longer for the father (P. euramericana; interspecific hybrid) than for the mother (P. deltoides; pure species). The linkage maps constructed and the interspecific poplar hybrid population in which clonal replicates for individual genotypes are available present a comprehensive foundation for future genomic studies and quantitative trait locus (QTL) identification.
Genetical Research, 2003
Growth trajectories are a biological process important to plant and animal breeding, and to evolu... more Growth trajectories are a biological process important to plant and animal breeding, and to evolutionary genetic studies. In this article, we report the detection of quantitative trait loci (QTLs) responsible for growth trajectories in poplars that are used as a model system for the study of forest biology. These QTLs were localized on a genetic linkage map of polymorphic markers using a statistical mapping method incorporating growth-curve models. The effects of the QTLs on growth are described as a function of age, so that age-specific changes in QTL effects can be readily projected throughout the entire growth process. The QTLs identified display increased effects on growth when trees age, yet the timing of QTL activation is earlier for stem height than diameter, which is consistent with the ecological viewpoint of canopy competition. The implications of the results for breeding and silviculture are discussed.