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981.
982.
983.
M J DE MAINE 《The Annals of applied biology》1994,125(2):361-366
Data on the production of offspring of 4×× 2× crosses in potato are presented. The ploidy composition of seedlings varied from year to year and parent to parent. Products of dihaploid induction crosses were chiefly 2× or 3× whereas crosses between S. tuberosum cultivars and unreduced gamete-producing S. phureja clones were mainly 3× or 4×. Substantial percentages of 3× seedlings were produced by some crosses in some years. It was concluded that the so-called ‘triploid block’ in potatoes is a variable phenomenon and that factors which increase seed production may suppress the proportion of triploids produced. 相似文献
984.
S. P. Dash 《Biometrical journal. Biometrische Zeitschrift》1980,22(5):407-417
In this paper the first two moments of the test criterion (Treat. S.S.)/(Treat.S.S. + Error S.S.) have been derived assuming that one observation corresponding to the first plot of the first block which is under treatment ‘m’ (say), is missing in a randomized block design with ‘V’ treatments and ‘r’ blocks. To keep the analysis simple the case of one missing observation has been considered. It is concluded that in general the design is not unbiased in YATES (1951) sense and the usual F-test is satisfactory iff /(vr - r - 1)=(S - S1)/(v - 1) (r-1), the block errors are homogeneous and (vr - r - 1) is large. The analysis of three unifornity trial data indicates that the first condition is the most important for the F-test to be satisfactory. However, if one observation is missing at random from some plot of some block, the F-test is unbiased. If the block errors are homogeneous and (vr - r - 1) GT96, the F-test also provides a good approximation to the corresponding randomization test in this case. 相似文献
985.
Lynnette R. Ferguson Pamela M. Turner Trudi A. Gourdie Kisione K. Valu William A. Denny 《Mutation research》1989,215(2):213-222
Although the biological properties (cytotoxicity, mutagenicity and carcinogenicity) of alkylating agents result from their bonding interactions with DNA, such compounds generally do not show any special binding affinity for DNA. A series of acridine-linked aniline mustards of widely-varying alkylator reactivity have been designed as DNA-directed alkylating agents. We have considered whether such DNA targeting has an effect on mutagenic properties by evaluating this series of drugs in comparison with their untargeted counterparts for toxic, recombinogenic and mutagenic properties in Saccharomyces cerevisae strain D5. The simple untargeted aniline mustards are effective inducers of mitotic crossing-over in this strain, but resemble other reported alkylators in being rather inefficient inducers of the “petite” or mitochondrial mutation in yeast. However, the majority of the DNA-targeted mustards were very efficient petite, mutagens, while showing little evidence of mitotic crossing-over or other nuclear events. The 100% conversion of cells into petites and the lack of a differential between growing and non-growing cells are similar to the effects of the well characterised mitochondrial mutagen ethidium bromide. These data suggest very different modes of action between the DNA-targeted alkylators and their non-targeted counterparts. 相似文献
986.
Embryogenic cultures of soybean [Glycine max (L.) Merr. cv. Jack and Asgrow A2872] were established in liquid Finer and Nagasawa medium, maintained by transfer to fresh
medium at biweekly intervals, and subjected to microprojectile bombardment over time. Cultures were not amenable to transformation
until they were at least 6 months old. Over time, different cell lines of the same genotype acquired very different culture
phenotypes. Histological analysis of cell lines differing in transformation ability showed that the most transformable cultures
had cytoplasmic-rich cells in the outermost layers of the tissue. In contrast, the outer layers of less transformable cultures
contained cells with prominent vacuoles. Although fresh weight accumulation of the cultures was curvilinear during the 2-week
subculture period, a burst of mitotic activity was evident shortly after transfer to fresh medium. This activity usually lasted
from the 2nd to the 6th day following subculture, and peaked on the 4th day. Tissues at or near this stage always produced
more transient expression of a reporter gene than did bombardments at other times. In addition, the cell lines most amenable
to transformation also exhibited the highest mitotic index. Thus any treatment to increase the mitotic index, especially when
the cell lines are less than 6 months old, may facilitate the transformation of cell lines from which efficient recovery of
transgenic plants is still possible.
Received: 16 September 1997 / Revision received: 29 January 1998 / Accepted: 21 February 1998 相似文献
987.
J. Subramani 《Biometrical journal. Biometrische Zeitschrift》1992,34(7):843-854
The present paper deals with an alternative and simple procedure to analyse the non-orthogonal data. The procedure is general in nature but has some advantages for the non-orthogonal data due to some missing observations. The procedure is applied to (i) two way classification with unequal number of observations per cell; (ii) randomized block designs with some missing observations and (iii) balanced incomplete block designs and also illustrated with the help of numerical examples. 相似文献
988.
989.