Changes in methylation of tissue cultured soybean cells detected by digestion with the restriction enzymes HpaII and MspI

Each of the tandemly arranged 5S RNA genes of soybean contain two CCGG sites which, if unmethylated, can be digested by both MspI and HpaII. Methylation of the internal cytosine (CmeCGG) prevents digestion by HpaII but allows digestions by MspI.Suspension cultures were prepared from soybean plants and the DNA from these cultures was examined for the susceptibility of 5S RNA genes to digestion by MspI and HpaII. 5S genes from DNA extracted from intact plants can be partially digested with MspI but not at all by HpaII. In contrast, shortly after cells were cultured the 5S RNA could be hydrolyzed by both HpaII and MspI. After prolonged cell culture, the 5S genes from some cell lines were found to have become partially or even completely resistant to HpaII digestion. The results suggest that lack of methylation can occur when cells are cultured and that such methylation may play a role in the heritable changes observed in cell culture.

Benefits of rehabilitation for traumatic spinal cord injury. Multivariate analysis in 711 patients

The functional outcomes of 711 patients with traumatic spinal cord injuries who were admitted to a rehabilitation hospital during an eight-year period were studied. The modified Barthel index, a 100-point scale, was used to assess ability to perform self-care and mobility skills at rehabilitation admission and discharge. There were statistically significant improvements in self-care and mobility subscores of the modified Barthel index. Mean total modified Barthel index scores increased from 13.8 at admission to 46.1 at discharge for patients with quadriplegia, and from 37.7 to 74.4 for patients with paraplegia. Functional gains made by patients with incomplete spinal lesions were greater than those made by patients with complete lesions. This study documents improvement in ability to perform self-care and mobility skills among patients with spinal cord injuries who participate in comprehensive rehabilitation.

Selection, Isolation, and Characterization of Cadmium-Resistant Datura innoxia Suspension Cultures

Datura innoxia cells from suspension cultures were selected for their ability to grow and divide rapidly in normally lethal concentrations of cadmium. Cells resistant to 12.5, 25, 50, 100, 160, 200, and 250 micromolar cadmium chloride were isolated and utilized to initiate cell suspension cultures resistant to this toxic metal ion. Variant cell lines retained their ability to grow in cadmium after being grown in its absence for more than 400 generations. Resistance to cadmium was correlated with the synthesis of low molecular weight, cysteine-rich, cadium-binding proteins. Synthesis of these proteins was induced rapidly in cadmium-resistant cells in response to a challenge of cadmium. Induction was detectable within one hour after exposure of the cells to the metal ion. Accumulation of protein bound cadmium reached a maximum eight to twelve hours following exposure. Metal-binding proteins were not detectable in the cadmium sensitive D. innoxia cells from which resistant cells were derived.

Isopropyl-N(3-chlorophenyl) carbamate (CIPC) induced chromosomal loss in soybean: a new tool for plant somatic cell genetics

The properties and uses of tissue culture partial haploid soybean cell lines are explored. Partial haploid lines were prepared by CIPC treatment of a genetic heterozygote, and compared to this heterozygote and to homozygous cell lines corresponding to the parental genotypes from which the heterozygote was derived. Cell lines which lack chromosomes were characterized physiologically and with respect to a variety of isozyme markers. Often the loss of chromosomes revealed a phenotype corresponding to a recessive parental genotype. In some cases, however, new phenotypes were observed indicating a complex genotype and suggests the interaction of several genes. The implications of this for plant breeding are discussed.CIPC also was used as a tool to dissect a complex phenotype which arose as the result of mutagenesis. A mutant cell line which required asparagine for growth but also had acquired the ability to grow on allantoin as a sole source of nitrogen was treated with CIPC to remove chromosomes. The requirement for asparagine could be separated from the ability to use allantoin, demonstrating that these phenotypes were the result of separate mutations.

Use of isopropyl-N(3-chlorophenyl) carbamate (CIPC) to produce partial haploid cells from suspension cultures of soybean (Glycine max)

Suspension cultures of a heterozygous line of soybean (Glycine max) were treated with CIPC. Surviving clones had lost 10-15 chromosomes. A recessive phenotype (non-fluorescence) not expressed in the heterozygote, was expressed with high frequency (15-20%) in these clones. Nucleoside auxotrophs were isolated from the segregant clones consistent with partial haploidy. A selective screen for nucleoside auxotrophs is described.

Isolation of an auxotrophic cell line of soybean (Glycine max) which requires asparagine or glutamine for growth

A suspension culture of haploid soybean cells was treated with ultra-violet light. From the mutagenized culture an auxotrophic cell line was isolated which grows on 1-B5 media supplemented with asparagine or glutamine. In the absence of these additives the cells cease to grow and die. Asparagine is unable to serve as a sole source of nitrogen, i.e., cannot substitute for nitrate and ammonia.

Isolation of sodium dependent variants from haploid soybean cell culture

Following ultraviolet mutagenesis, we have isolated two Na(+) dependent variants from haploid suspension cultures of soybean cells. No selection was used in the isolation procedure. These cells cannot grow in 1 mM Na(+) but can grow in 17 mM Na(+). The strains also grow in 33 or 65 mM Na(+), concentrations in which the parent cell line dies. [(22)Na] was used to measure the accumulation of Na(+) by parent and variant cell lines. Two- to three-fold less Na(+) is retained by the variant cell lines.