A cytological observation on those factors affecting pollen abortion of <I>Taraxacum coreanum</I>

Abstract Background Photoperiod and/or thermo-sensitive male sterility is an effective pollination control system in crop two-line hybrid breeding. We previously discovered the spontaneous mutation of a partially male sterile plant and developed a thermo-sensitive genic male sterile (TGMS) line 373S in Brassica napus L. The present study characterized this TGMS line through cytological observation, photoperiod/ temperature treatments, and genetic investigation. Results Microscopic observation revealed that the condensed cytoplasm and irregular exine of microspores and the abnormal degradation of tapetum are related to pollen abortion. Different temperature and photoperiod treatments in field and growth cabinet conditions indicated that the fertility alteration of 373S was mainly caused by temperature changes. The effects of photoperiod and interaction between temperature and photoperiod were insignificant. The critical temperature leading to fertility alteration ranged from 10 °C (15 °C/5 °C) to 12 °C (17 °C/7 °C), and the temperature-responding stage was coincident with anther development from pollen mother cell formation to meiosis stages. Genetic analysis indicated that the TGMS trait in 373S was controlled by one pair of genes, with male sterility as the recessive. Multiplex PCR analysis revealed that the cytoplasm of 373S is pol type. Conclusions Our study suggested that the 373S line in B. napus has a novel thermo-sensitive gene Bnmst1 in Pol CMS cytoplasm background, and its fertility alteration is mainly caused by temperature changes. Our results will broaden the TGMS resources and lay the foundation for two-line hybrid breeding in B. napus.

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Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078614 ◽

1977 ◽

Vol 35 ◽

pp. 214-217

Author(s):

F. A. Heckman ◽

E. Redman ◽

J.E. Connolly

Keyword(s):

Image Analysis ◽

Image Quality ◽

Exposure Time ◽

Image Contrast ◽

Automated Image Analysis ◽

Practical Application ◽

Factors Affecting ◽

High Image Quality ◽

Qualitative Evidence ◽

Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

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Factors affecting microstructural scale in liquid crystalline polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174230 ◽

1990 ◽

Vol 48 (4) ◽

pp. 220-221

Author(s):

Christine M. Dannels ◽

Christopher Viney

Keyword(s):

Liquid Crystalline ◽

Liquid Crystalline Polymers ◽

Factors Affecting ◽

Crystalline Polymers ◽

Thermal Expansion Coefficients ◽

Low Thermal Expansion ◽

Lower Viscosity ◽

Fine Microstructure ◽

Planar Orientation ◽

Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

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Factors affecting dentist participation in a state Medicaid program

Journal of Dental Education ◽

10.1002/j.0022-0337.1990.54.11.tb02476.x ◽

1990 ◽

Vol 54 (11) ◽

pp. 638-643 ◽

Cited By ~ 20

Author(s):

PC Damiano ◽

ER Brown ◽

JD Johnson ◽

JP Scheetz

Keyword(s):

Medicaid Program ◽

Factors Affecting

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Factors affecting dental utilization of elders aged 75 years or older

Journal of Dental Education ◽

10.1002/j.0022-0337.1986.50.11.tb02060.x ◽

1986 ◽

Vol 50 (11) ◽

pp. 673-677 ◽

Cited By ~ 5

Author(s):

AA Wilson ◽

LG Branch

Keyword(s):

Factors Affecting ◽

Dental Utilization

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Speech Therapy Services in a Large School System: A Six-Year Overview

Language Speech and Hearing Services in Schools ◽

10.1044/0161-1461.0704.207 ◽

1976 ◽

Vol 7 (4) ◽

pp. 207-219 ◽

Cited By ~ 3

Author(s):

Constance P. DesRoches

Keyword(s):

School System ◽

Speech Therapy ◽

Factors Affecting ◽

Case Load ◽

Number Of Children ◽

School Population ◽

System A ◽

Therapy Services ◽

And Shifts ◽

Selection Factors

A statistical review provides analysis of four years of speech therapy services of a suburban school system which can be used for comparison with other school system programs. Included are data on the percentages of the school population enrolled in therapy, the categories of disabilities and the number of children in each category, the sex and grade-level distribution of those in therapy, and shifts in case-load selection. Factors affecting changes in case-load profiles are identified and discussed.

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Assessing the Link Between Perception and Production in Cantonese Tone Acquisition

Journal of Speech Language and Hearing Research ◽

10.1044/2018_jslhr-s-17-0430 ◽

2019 ◽

Vol 62 (5) ◽

pp. 1243-1257 ◽

Cited By ~ 2

Author(s):

Peggy Pik Ki Mok ◽

Holly Sze Ho Fung ◽

Vivian Guo Li

Keyword(s):

Language Acquisition ◽

General Principle ◽

Choice Task ◽

Factors Affecting ◽

Tone Pair ◽

Tone Production ◽

Monosyllabic Words ◽

Early Production ◽

Forced Choice Task ◽

Production Accuracy

Purpose Previous studies showed early production precedes late perception in Cantonese tone acquisition, contrary to the general principle that perception precedes production in child language. How tone production and perception are linked in 1st language acquisition remains largely unknown. Our study revisited the acquisition of tone in Cantonese-speaking children, exploring the possible link between production and perception in 1st language acquisition. Method One hundred eleven Cantonese-speaking children aged between 2;0 and 6;0 (years;months) and 10 adolescent reference speakers participated in tone production and perception experiments. Production materials with 30 monosyllabic words were transcribed in filtered and unfiltered conditions by 2 native judges. Perception accuracy was based on a 2-alternative forced-choice task with pictures covering all possible tone pair contrasts. Results Children's accuracy of production and perception of all the 6 Cantonese tones was still not adultlike by age 6;0. Both production and perception accuracies matured with age. A weak positive link was found between the 2 accuracies. Mother's native language contributed to children's production accuracy. Conclusions Our findings show that production and perception abilities are associated in tone acquisition. Further study is needed to explore factors affecting production accuracy in children. Supplemental Material https://doi.org/10.23641/asha.7960826

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