Analysis of distributions of mutants in clones of plant-cell aggregates

Summary The organization of plant cells (or any other genetic elements, such as organelles) into aggregates modifies the expected distribution of mutants in clones. The reason for the modification, and its effect on the use of the Luria-Delbrück fluctuation test, are discussed. The Luria-Delbriick test was used to show that the trait for chlorate resistance in cultured rose-cell aggregates appeared spontaneously and in the absence of chlorate ion.     

The dermatoglyphic characteristics of two isolated Bedouin groups from South Sinai

The dermatoglyphics of the Muzeina and Gebeliya Bedouin tribes, two small biologically isolated populations, leading a similar nomadic life under the specific conditions of the Sinai desert, were studied. The differences found between the studied samples concern particularly the frequencies of palmar and finger pattern types. These differences are in agreement with data on the origin of the tribes, a Negro and/or European admixture being evident in the Gebeliya dermatoglyphics. The coefficients of variation for some quantitative dermatoglyphic traits, presumably with a polygenic determination, are lower in the Muzeina than in the Gebeliya sample. Isolation and consanguinity may exert their influence on the dermatoglyphic traits influencing the frequencies of the corresponding genes.     

A simple cell disrupter designed for small cells with relatively large nuclei

A simple cell disrupter that is particularly suitable for breaking small cells with relatively large nuclei is described. Cells are disrupted by the shearing forces set up as they are pushed by a positive N2 pressure through a 0.8- to 1.5-micrometer stainless-steel filter. The total procedure takes only a few minutes, it is highly reproducible, and the yield is good. The cell homogenate obtained is a good starting source for the isolation of plasma membranes, intracellular organelles, and nuclei.     

Six-year field test results of micropropagated black cherry (Prunus serotina)

Summary A field test was established in 1987 to evaluate the growth of micropropagated black cherry plantlets and control seedlings. The study also evaluated effects of two container types on initial survival and growth and of pruning on stem form and growth. At the time of field establishment, plantlets had more extensive root systems than the control seedlings. Survival and height growth were not influenced by container size. Through the first three growing seasons, seedlings were larger than micropropagated plants, but growth differences diminished in the fourth through sixth seasons. Pruning increased the length of clear stem by nearly five-fold but adversely affected diameter growth. Although all clones were from ortet trees more than 50 yr old, none showed plagiotropic growth. Six-year results showed that in a well-prepared and maintained plantation, black cherry trees derived from tissue culture can have at least 80% survival, and growth rates in excess of 1 m per year.     

Interleukin-1-β and Tumor Necrosis Factor-α Increase Peripheral-Type Benzodiazepine Binding Sites in Cultured Polygonal Astrocytes

Peripheral-type benzodiazepine binding sites (PTBBS) are markedly increased in the injured CNS. Astrocytes appear to be the primary cell type which express increased PTBBS. Because certain cytokines within the injured CNS are potent mitogens for astrocytes, we examined the effects of two such cytokines, interleukin (IL)-1 beta and tumor necrosis factor (TNF), on PTBBS in cultured astrocytes using [3H]Ro 5-4864 as the specific ligand. Purified cultures of either polygonal or process-bearing astrocytes were prepared from neonatal rat cerebral hemispheres. At a concentration of 1.8 nM, specific binding of the radioactive ligand to polygonal astrocytes reached equilibrium within 60 min and was half-maximal by 5-10 min. By contrast, specific binding to process-bearing astrocytes barely exceeded background levels. IL-1 and TNF increased PTBBS within polygonal astrocytes in both dose- and time-dependent manners. At 10-50 ng/ml, IL-1 beta and TNF-alpha elevated [3H]Ro 5-4864 binding in polygonal astrocyte cultures 65 and 87%, respectively, above the level in control cultures. However, no changes in PTBBS were seen within polygonal astrocytes after IL-2 treatment. Scatchard analysis of saturation binding experiments suggested that the increase in PTBBS promoted by TNF was due to an increased number of binding sites present in polygonal astrocytes and not due to an increase in receptor affinity. Binding data suggested that PTBBS within cultures of process-bearing astrocytes were virtually absent irrespective of the treatment. These in vitro data suggest that certain cytokines found in the injured brain may be involved in up-regulating PTBBS within a particular subtype of astrocyte.     

Isolation,origin and properties of enucleate plant microplasts

Summary Auxin-induced highly vacuolated thin-walled callus cells of several plant species, when ruptured, released large numbers of subcellular units most of which were enucleate. These enucleate microplasts are surrounded by an inner membrane of the cell, most probably derived from the tonoplast. When microplasts isolated fromSaintpaulia callus were cultured in a medium supplemented with growth substances they formed a thin wall and underwent budding. Microplasts could be useful for various studies in plant cell biology and for genetic manipulations.     

Isolation and characterization of a serially cultivated,neoplastic, epithelial cell line from theN-nitrosomethylurea induced rat mammary adenocarcinoma

Summary A new in vitro model for human breast cancer is described. Derived from anN-nitrosomethylurea (NMU) induced rat mammary adenocarcinoma, this serially cultivated cell line has been demonstrated, by a variety of criteria, to be an authentic neoplastic, rat mammary epithelial cell line. The criteria used include morphological and growth characteristics; the presence of specific cell surface antigens; steroid hormone receptors; hormone responsiveness; casein production; karyotype and isoenzyme profile analysis; anchorage independent growth and oncogenicity. Inasmuch as the NMU cell line possesses high concentrations of glucocorticoid and androgen receptors, it may provide a useful model for study of the action of these hormones in human breast cancer. In addition, the NMU line may serve as a valuable in vitro model in which to assess the effects of a variety of endogenous and exogenous agents known to influence mammary tumor growth in vivo, including drugs, nutrients, and growth factors. This work was supported by Grants CA29602 and RR05775-05 from the National Cancer Institute, Bethesda, Maryland.     

Cryptic species in Diacyclops bicuspidatus (Copepoda:Cyclopoida): evidence from crossbreeding studies

The problem of cryptic species in Diacyclops bicuspidatus was examined using interpopulation crosses of four populations collected from a: (1) permanent flood lake in Kiev, Ukraine, (2) temporary pool in Kiev, (3) permanent pond in St. Petersburg, Russia (1200 km to north from Kiev) and (4) lake in Crimea (1100 km south of Kiev). The only interpopulation crosses to exhibit fertility were those between the St. Petersburg population and each of the two Kiev populations. The crosses between the Kiev and Crimea populations, between the St. Petersburg and Crimea populations, and between the two Kiev populations were sterile, as evidenced by either nonviable eggs, empty egg membranes or incomplete copulations. The F₁ hybrids resulting from the St. Petersburg permanent pond X Kiev flood lake cross were fertile and produced mature F₂ offspring. Some data on development times of parental and hybrid lines are presented. The St. Petersburg parental line showed development times almost twice as long as those of the Kiev flood lake population when reared at 10 °C and 20 °C in the laboratory. The F₁ offspring of the cross between St. Petersburg females and Kiev floodlake males showed similar development times to females of the St. Petersburg parental lines at both temperatures. The F₂ hybrids also showed development times that approximated those of the St. Petersburg parental line. These crossbreeding studies suggest the presence of cryptic species in the D. bicuspidatus inhabiting ecologically different populations in many parts of its large holarctic range.     

Selection and proliferation of rapid growing cell lines from embryo derived cell cultures of yew tree (Taxus cuspidata Sieb. et Zucc)

Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14 elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth.