The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform

Lawrence C Erway - One of the best experts on this subject based on the ideXlab platform.

  • genetics of age related hearing loss in mice iii susceptibility of inbred and F1 Hybrid strains to noise induced hearing loss
    Hearing Research, 1996
    Co-Authors: Lawrence C Erway, Yeawen Shiau, Rickie R Davis, Edward F Krieg
    Abstract:

    Some humans and mice are genetically predisposed to age-related hearing loss (AHL), and others are variously susceptible to noise-induced hearing loss (NIHL). The inbred C57BL/6J (B6) mice exhibit AHL at an early age, whereas the inbred CBA/CaJ (CB) mice do not. The B6 mice are much more susceptible to NIHL than are the CB mice (Shone et al., 1991; Li, 1992a). The B6 mice possess an Ahl gene which maps to chromosome 10 (Erway et al., 1995). This study was designed, using these two inbred strains plus two F1 Hybrid strains of mice, to begin to test the hypothesis that the Ahl genotypes may influence the susceptibility to NIHL. These strains of mice (with putative genotypes) are: inbred CB (+/+) and B6 (Ahl/Ahl); Hybrid CBB6F1 (+/Ahl) and B6D2F1 (Ahl/Ahl; D2 represents inbred DBA/2J). Twenty-four mice of each of these four strains were exposed to noise (110 dB for 0, 1 or 2 h) and tested for auditory-evoked brainstem response (ABR) thresholds. The CB and CBB6F1 strains of mice did not differ significantly from each other, exhibiting mostly temporary threshold shifts. The B6 and B6D2F1 strains of mice did not differ significantly from each other, but did exhibit permanent threshold shifts. These results support the hypothesis that genetic predisposition to AHL may be revealed at a younger age by NIHL. This suggests that it may be possible to use the NIHL to distinguish segregating genotypes (+/Ahl vs. Ahl/Ahl) backcross progeny and thereby to identify and map single genes for AHL.

  • genetics of age related hearing loss in mice i inbred and F1 Hybrid strains
    Hearing Research, 1993
    Co-Authors: Lawrence C Erway, James F Willott, Jonathan R Archer, David E Harrison
    Abstract:

    Abstract The auditory-evoked brainstem response (ABR) was used to assess hearing loss in five inbred strains of mice and all ten combinations of F1 Hybrids. The inbred strains are CBA/H-T6J (CH), DBA/2J (D2), C57BL/6J (B6), BALB/cByJ (BY) and WB/ReJ (WB). The F1 Hybrids are CHD2, CHB6, CHBY, CHWB, D2B6, D2BY, D2WB, B6BY, B6WB, and BYWB. At middle age (12, 16 months), mice were tested with click stimuli. At a relatively old age (23 months, near inbreds' median life span), they were tested with both click and tone-pip stimuli. The CH mice and their four F1 Hybrid strains exhibit lower thresholds than the other strains, with the F1 strains being most sensitive (i.e., Hybrid vigor). The D2 inbred and the three D2 F1 Hybrids (excluding CHD2) exhibit the earliest and most severe hearing losses. The B6, BY and WB inbred strains exhibit severe hearing losses between 16 and 23 months of age; however, the B6BY, B6WB and BYWB F1 Hybrids have significantly lower thresholds than their parental strains (genetic complementation). These data support a genetic model for recessive alleles at three different loci which contribute to age-related hearing loss. The CH mice have none of the recessive alleles, and the D2 mice are homozygous recessive for all three; the B6, BY and WB inbred strains are homozygous recessive respectively for one of the three loci.

Heung Yong Jeon - One of the best experts on this subject based on the ideXlab platform.

  • characteristics of F1 Hybrids and inbred lines in octoploid strawberry fragaria ananassa duchesne
    Plant Breeding, 2012
    Co-Authors: Ho Jeong Jeong, Heung Yong Jeon
    Abstract:

    With 4 figures and 3 tables Abstract The strawberry (Fragaria × ananassa Duchesne) plant is an octoploid vegetative propagated plant, and its cultivation is labour intensive in comparison with other plants propagated from seeds. The aims of this study were to develop an inbred line from octoploid strawberry and to generate an F1 Hybrid cultivar through the combination of inbred lines. All inbred lines were obtained through selfing using five cultivars. Inbred lines were produced by selecting the best individuals for further inbreeding from each of the previous generations. Plant vigour and yield in inbred lines were low compared with the original cultivar, but completely recovered in the F1 Hybrid. Breeding of inbred lines in octoploid strawberry can be achieved if individuals showing inbreeding depression are eliminated and vigorous individuals are selected, resulting in a strong heterosis of F1 Hybrids through crossing between inbred lines.

  • Characteristics of F1 Hybrids and Inbred lines in Octoploid Strawberry (Fragaria × ananassa Duchesne)
    Plant Breeding, 2012
    Co-Authors: Ho Jeong Jeong, Heung Yong Jeon
    Abstract:

    With 4 figures and 3 tables Abstract The strawberry (Fragaria × ananassa Duchesne) plant is an octoploid vegetative propagated plant, and its cultivation is labour intensive in comparison with other plants propagated from seeds. The aims of this study were to develop an inbred line from octoploid strawberry and to generate an F1 Hybrid cultivar through the combination of inbred lines. All inbred lines were obtained through selfing using five cultivars. Inbred lines were produced by selecting the best individuals for further inbreeding from each of the previous generations. Plant vigour and yield in inbred lines were low compared with the original cultivar, but completely recovered in the F1 Hybrid. Breeding of inbred lines in octoploid strawberry can be achieved if individuals showing inbreeding depression are eliminated and vigorous individuals are selected, resulting in a strong heterosis of F1 Hybrids through crossing between inbred lines.

Timothy John Blumfield - One of the best experts on this subject based on the ideXlab platform.

  • how weed control and fertilisation influence tree physiological processes and growth at early establishment in an exotic F1 Hybrid pine plantation of subtropical australia
    Journal of Soils and Sediments, 2014
    Co-Authors: Paula Therese Ibell, Zhihong Xu, Terence J Blake, Carole Wright, Timothy John Blumfield
    Abstract:

    Purpose This study investigated how nitrogen (N) nutrition and key physiological processes varied under changed water and nitrogen competition resulting from different weed control and fertilisation treatments in a 2-year-old F1 Hybrid (Pinus elliottii Engelm var. elliottii × P. caribaea var. hondurensis Barr. ex Golf.) plantation on a grey podzolic soil type, in Southeast Queensland. Materials and methods The study integrated a range of measures including growth variables (diameter at ground level (DGL), diameter at breast height (DBH) and height (H)), foliar variables (including foliar N concentration, foliar δ13C and δ15N) and physiological variables (including photosynthesis (An), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi) (A/gs) and xylem pressure potential (ΨXPP)) to better understand the mechanisms influencing growth under different weed control and fertilisation treatments. Five levels of weed control were applied: standard (routine), luxury, intermediate, mechanical and nil weed control, all with routine fertilisation plus an additional treatment, routine weed control and luxury fertilisation. Relative weed cover was assessed at 0.8, 1.1 and 1.6 years after plantation establishment to monitor the effectiveness of weed control treatments. Soil investigation included soil ammonium (NH4 +-N), nitrate (NO3 −-N), potentially mineralizable N (PMN), gravimetric soil moisture content (MC), hot water extractable organic carbon (HWETC), hot water extractable total N (HWETN), total C, total N, stable C isotope composition (δ13C), stable N isotope composition (δ15N), total P and extractable K. Results and discussion There were significant relationships between foliar N concentrations and relative weed cover and between tree growth and foliar N concentration or foliar δ15N, but initial site preparation practices also increased soil N transformations in the planting rows reducing the observable effects of weed control on foliar δ15N. A positive relationship between foliar N concentration and foliar δ13C or photosynthesis indicated that increased N availability to trees positively influenced non-stomatal limitations to photosynthesis. However, trees with increased foliar N concentrations and photosynthesis were negatively related to xylem pressure potential in the afternoons which enhanced stomatal limitations to photosynthesis and WUEi. Conclusions Luxury and intermediate weed control and luxury fertilisation positively influenced growth at early establishment by reducing the competition for water and N resources. This influenced fundamental key physiological processes such as the relationships between foliar N concentration, A n, E, gs and ΨXPP. Results also confirmed that time from cultivation is an important factor influencing the effectiveness of using foliar δ15N as an indicator of soil N transformations.

  • effects of weed control and fertilization at early establishment on tree nitrogen and water use in an exotic F1 Hybrid pine of subtropical australia
    Journal of Soils and Sediments, 2013
    Co-Authors: Paula Therese Ibell, Zhihong Xu, Terence J Blake, Timothy John Blumfield
    Abstract:

    Purpose We investigated the effects of weed control and fertilization at early establishment on foliar stable carbon (δ13C) and nitrogen (N) isotope (δ15N) compositions, foliar N concentration, tree growth and biomass, relative weed cover and other physiological traits in a 2-year old F1 Hybrid (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Barr. ex Golf.)) plantation grown on a yellow earth in southeast Queensland of subtropical Australia. Materials and methods Treatments included routine weed control, luxury weed control, intermediate weed control, mechanical weed control, nil weed control, and routine and luxury fertilization in a randomised complete block design. Initial soil nutrition and soil fertility parameters included (hot water extractable organic carbon (C) and total nitrogen (N), total C and N, C/N ratio, labile N pools (nitrate (NO3 −) and ammonium (NH4 +)), extractable potassium (K+)), soil δ15N and δ13C. Relative weed cover, foliar N concentrations, tree growth rate and physiological parameters including photosynthesis, stomatal conductance, photosynthetic nitrogen use efficiency, foliar δ15N and foliar δ13C were also measured at early establishment. Results and discussion Foliar N concentration at 1.25 years was significantly different amongst the weed control treatments and was negatively correlated to the relative weed cover at 1.1 years. Foliar N concentration was also positively correlated to foliar δ15N and foliar δ13C, tree height, height growth rates and tree biomass. Foliar δ15N was negatively correlated to the relative weed cover at 0.8 and 1.1 years. The physiological measurements indicated that luxury fertilization and increasing weed competition on these soils decreased leaf xylem pressure potential (Ψxpp) when compared to the other treatments. Conclusions These results indicate how increasing N resources and weed competition have implications for tree N and water use at establishment in F1 Hybrid plantations of southeast Queensland, Australia. These results suggest the desirability of weed control, in the inter-planting row, in the first year to maximise site N and water resources available for seedling growth. It also showed the need to avoid over-fertilisation, which interfered with the balance between available N and water on these soils.

David E Harrison - One of the best experts on this subject based on the ideXlab platform.

  • genetics of age related hearing loss in mice i inbred and F1 Hybrid strains
    Hearing Research, 1993
    Co-Authors: Lawrence C Erway, James F Willott, Jonathan R Archer, David E Harrison
    Abstract:

    Abstract The auditory-evoked brainstem response (ABR) was used to assess hearing loss in five inbred strains of mice and all ten combinations of F1 Hybrids. The inbred strains are CBA/H-T6J (CH), DBA/2J (D2), C57BL/6J (B6), BALB/cByJ (BY) and WB/ReJ (WB). The F1 Hybrids are CHD2, CHB6, CHBY, CHWB, D2B6, D2BY, D2WB, B6BY, B6WB, and BYWB. At middle age (12, 16 months), mice were tested with click stimuli. At a relatively old age (23 months, near inbreds' median life span), they were tested with both click and tone-pip stimuli. The CH mice and their four F1 Hybrid strains exhibit lower thresholds than the other strains, with the F1 strains being most sensitive (i.e., Hybrid vigor). The D2 inbred and the three D2 F1 Hybrids (excluding CHD2) exhibit the earliest and most severe hearing losses. The B6, BY and WB inbred strains exhibit severe hearing losses between 16 and 23 months of age; however, the B6BY, B6WB and BYWB F1 Hybrids have significantly lower thresholds than their parental strains (genetic complementation). These data support a genetic model for recessive alleles at three different loci which contribute to age-related hearing loss. The CH mice have none of the recessive alleles, and the D2 mice are homozygous recessive for all three; the B6, BY and WB inbred strains are homozygous recessive respectively for one of the three loci.

Terence J Blake - One of the best experts on this subject based on the ideXlab platform.

  • how weed control and fertilisation influence tree physiological processes and growth at early establishment in an exotic F1 Hybrid pine plantation of subtropical australia
    Journal of Soils and Sediments, 2014
    Co-Authors: Paula Therese Ibell, Zhihong Xu, Terence J Blake, Carole Wright, Timothy John Blumfield
    Abstract:

    Purpose This study investigated how nitrogen (N) nutrition and key physiological processes varied under changed water and nitrogen competition resulting from different weed control and fertilisation treatments in a 2-year-old F1 Hybrid (Pinus elliottii Engelm var. elliottii × P. caribaea var. hondurensis Barr. ex Golf.) plantation on a grey podzolic soil type, in Southeast Queensland. Materials and methods The study integrated a range of measures including growth variables (diameter at ground level (DGL), diameter at breast height (DBH) and height (H)), foliar variables (including foliar N concentration, foliar δ13C and δ15N) and physiological variables (including photosynthesis (An), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi) (A/gs) and xylem pressure potential (ΨXPP)) to better understand the mechanisms influencing growth under different weed control and fertilisation treatments. Five levels of weed control were applied: standard (routine), luxury, intermediate, mechanical and nil weed control, all with routine fertilisation plus an additional treatment, routine weed control and luxury fertilisation. Relative weed cover was assessed at 0.8, 1.1 and 1.6 years after plantation establishment to monitor the effectiveness of weed control treatments. Soil investigation included soil ammonium (NH4 +-N), nitrate (NO3 −-N), potentially mineralizable N (PMN), gravimetric soil moisture content (MC), hot water extractable organic carbon (HWETC), hot water extractable total N (HWETN), total C, total N, stable C isotope composition (δ13C), stable N isotope composition (δ15N), total P and extractable K. Results and discussion There were significant relationships between foliar N concentrations and relative weed cover and between tree growth and foliar N concentration or foliar δ15N, but initial site preparation practices also increased soil N transformations in the planting rows reducing the observable effects of weed control on foliar δ15N. A positive relationship between foliar N concentration and foliar δ13C or photosynthesis indicated that increased N availability to trees positively influenced non-stomatal limitations to photosynthesis. However, trees with increased foliar N concentrations and photosynthesis were negatively related to xylem pressure potential in the afternoons which enhanced stomatal limitations to photosynthesis and WUEi. Conclusions Luxury and intermediate weed control and luxury fertilisation positively influenced growth at early establishment by reducing the competition for water and N resources. This influenced fundamental key physiological processes such as the relationships between foliar N concentration, A n, E, gs and ΨXPP. Results also confirmed that time from cultivation is an important factor influencing the effectiveness of using foliar δ15N as an indicator of soil N transformations.

  • effects of weed control and fertilization at early establishment on tree nitrogen and water use in an exotic F1 Hybrid pine of subtropical australia
    Journal of Soils and Sediments, 2013
    Co-Authors: Paula Therese Ibell, Zhihong Xu, Terence J Blake, Timothy John Blumfield
    Abstract:

    Purpose We investigated the effects of weed control and fertilization at early establishment on foliar stable carbon (δ13C) and nitrogen (N) isotope (δ15N) compositions, foliar N concentration, tree growth and biomass, relative weed cover and other physiological traits in a 2-year old F1 Hybrid (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Barr. ex Golf.)) plantation grown on a yellow earth in southeast Queensland of subtropical Australia. Materials and methods Treatments included routine weed control, luxury weed control, intermediate weed control, mechanical weed control, nil weed control, and routine and luxury fertilization in a randomised complete block design. Initial soil nutrition and soil fertility parameters included (hot water extractable organic carbon (C) and total nitrogen (N), total C and N, C/N ratio, labile N pools (nitrate (NO3 −) and ammonium (NH4 +)), extractable potassium (K+)), soil δ15N and δ13C. Relative weed cover, foliar N concentrations, tree growth rate and physiological parameters including photosynthesis, stomatal conductance, photosynthetic nitrogen use efficiency, foliar δ15N and foliar δ13C were also measured at early establishment. Results and discussion Foliar N concentration at 1.25 years was significantly different amongst the weed control treatments and was negatively correlated to the relative weed cover at 1.1 years. Foliar N concentration was also positively correlated to foliar δ15N and foliar δ13C, tree height, height growth rates and tree biomass. Foliar δ15N was negatively correlated to the relative weed cover at 0.8 and 1.1 years. The physiological measurements indicated that luxury fertilization and increasing weed competition on these soils decreased leaf xylem pressure potential (Ψxpp) when compared to the other treatments. Conclusions These results indicate how increasing N resources and weed competition have implications for tree N and water use at establishment in F1 Hybrid plantations of southeast Queensland, Australia. These results suggest the desirability of weed control, in the inter-planting row, in the first year to maximise site N and water resources available for seedling growth. It also showed the need to avoid over-fertilisation, which interfered with the balance between available N and water on these soils.