Chronology of chromosome reduplication in Chinese hamster cells incubated at low temperature

Experiments have been carried out on Chinese hamster fibroblasts. Cultures at the log-stage of growth were incubated at 15 or 25° C for 24 hrs. In two groups of experiments the cells were labeled with H³-TdR for 6 hrs at the respective temperature, washed and further incubated at 37° C. In each group of experiments cultures labeled with H³-TdR at 37° C for 20 min were used as a control. It was found: 1. the delay in the onset of cell passage through the mitotic cycle at 37° in cultures exposed to 15 or 25° C was about equal to 1,5-1 hr resp. and cells proceeded through the life cycle without blockages at any phase of the cycle; 2. the patterns of chromosome reproduction during the second half of the S-phase were the same after labeling at 15, 25 and 37° C. — In the third group the cells were labelled with HP-TdR for 10–60 min and 6 hrs resp. at 25° C. The patterns of reproduction of chromosome pairs 1–4 and small metacentrics were found to be the same in cells labeled briefly and those labeled for 6 hrs. After brief labeling asynchronous reduplication of different segments in many chromosomes became evident. It was masked because of heavy labeling after 6 hrs treatment.     

Dynamics of migration changes in tissue culture of delayed hypersensitive cells incubated with antigen

Клетки селезенки морских свинок, гиперсенситивных к туберкулину, в контакте с этим антигеном в течение первых часов обнаруживают повышенную способнстъ к миграции, и толъко в течение следующих часов опыта наблюдается торможение миграции. Подобные изменения не возникают при отсуствии специфичского антигена или в кулътурах клеток нормалънах животных. Эти резулътаты важны для объяснения некоторых разногласий в литературе и для понмания механизма аллергии туберкулинового типа.     

DNA synthesis in Hela cells at low temperature

It has been proved that ³H-thymidine is incorporated into DNA of HeLa cells cultured at 4 °C and its labelling distribution in DNA is homogeneous. This incorporation of ³H-thymidine increased with the duration of incubation and only 30% of the cell population was labelled after 12 h. When synchronous cell populations were used, the rate and extent of DNA synthesis at 4 °C was proportional to the relative number of cells in S phase at that temperature. Thus, cellular labelling at 4 °C does not result from a non-specific absorption phenomenon, but indicates a DNA synthesis process.     

太子参超低温脱毒及规模化组培育苗技术

以太子参茎尖为外植体,采用超低温去除病毒方法,通过组织培养研究了芽增殖诱导、丛生芽诱导、生根壮苗诱导的适合条件,以期形成太子参规模化育苗技术。结果表明：超低温处理1 h后,太子参脱毒率可达90%以上;规模化组培育苗最适宜配方为初代培养基为改良MS＋2.5 mg/L 6-BA＋0.5 mg/L IAA继代增殖培养基为改良MS＋1.2 mg/L KT＋0.5 mg/L NAA,壮苗生根培养基为改良MS＋0.2 mg/L KT＋1.5 mg/L DA-6＋10%蛋白粉。     

Cell-mediated mineralization in culture at low temperature associated with subtle thermogenic response

In both the growth plate and in marrow stromal cell cultures cell-mediated mineralization is preceded by characteristics of anaerobic and low efficiency energy metabolism. Reagents that increase mineralization like malonate and dexamethasone (DEX) also increase the mitochondrial membrane potential (MtMP) especially 1 week after DEX stimulation. Contrarily, levamisole, which decreases mineralization, also decreases MtMP. Modulation of MtMP and energy metabolism could be linked to regulation of mineralization by the uncoupling of oxidative phosphorylation. This uncoupling should be associated with thermogenesis in cells that induce mineralization. We examined whether cold temperature affects mineralization, and whether cellular thermogenesis takes place at cold temperature in parallel to changes in MtMP. Osteoprogenitor cells (OPC) induced, in DEX stimulated rat marrow stroma, higher mineralization at 33°C than at 37°C. Increased mineralization by cold temperature required long incubation since incubation in the cold during short intervals, 3–4 days, did not increase mineralization relative to (37°C) controls. Marrow stromal cells in the presence of valinomycin responded to incubation at 33°C by retaining all the vital dye after 4 h, unlike the cells at 37°C; however, after 24 h the level of dye retention at 33°C was the same as at 37°C. The delayed response of the temperature-dependent (> 37°C) K⁺ ionophor to incubation in the cold indicated that certain cells may respond to low temperature by local intracellular heating, and by heat conduction to the plasma membrane. DEX-stimulated stromal cells, unlike unstimulated cells, showed increased mitochondrial rhodamine 123 retention in the presence of valinomycin after 24 h in the cold, which corresponds to day 4 of OPC induction. This is consistent with the concept that valinomycin-induced cell damage is mediated by (cold-induced) local heating. The mechanism of this cell damage should selectively prefer non-thermogenic (rhodamine retaining) over thermogenic (rhodamine leaking) cells such as OPC. At cold temperature DEX-stimulated stromal cells showed the best anti-OPC selection under exposure to valinomycine between days 3–7, concurrent with the period of rhodamine leakage from the mitochondria. These results indicate that thermogenesis is enhanced during the period of low MtMP in mineralizing cells, and prolonged exposure to cold increases mineralization also due to induction of subtle thermogenesis. © 1996 Wiley-Liss, Inc.     

Induction of heat shock protein and thermal sensitivity of mammalian cells maintained at low culture temperature.

Effects of low culture temperature on the induction of heat shock proteins in FM3A cells by a heat shock and on the thermal sensitivity of the cells were examined. FM3A cells maintained at 33 degrees C could not induce hsp70 during continuous heating or after a short heat shock at either 39, 42, or 45 degrees C, although FM3A cells maintained at a normal culture temperature of 37 degrees C can induce the synthesis of hsp70. Furthermore, the cells maintained at 33 degrees C were more sensitive to the subsequent heat shock than the cells maintained at 37 degrees C. Thus, the culture temperature of the mammalian cells may be an important factor for the induction of hsp70, and hsp70 may play an important role to protect or repair the thermal damage of cells.     

Epithelial cells in tissue culture

In this review the characteristics of established renal and intestinal epithelial cell lines are described by summarizing the accumulated literature about specific properties retained by the cells in tissue culture. Furthermore, brief examples are given for the use of cultured epithelia as model systems to study epithelial transport and metabolic functions, epithelial cell polarity, and aspects of the differentiation and maturation of epithelia by physiological, biochemical and genetic, or cell and molecular biological approaches.     

Differential protein expression following low temperature culture of suspension CHO-K1 cells

Background  

To ensure maximal productivity of recombinant proteins (rP) during production culture it is typical to encourage an initial phase of rapid cell proliferation to achieve high biomass followed by a stationary phase where cellular energies are directed towards production of rP. During many such biphasic cultures, the initial phase of rapid cell growth at 37°C is followed by a growth arrest phase induced through reduction of the culture temperature. Low temperature induced growth arrest is associated with many positive phenotypes including increased productivity, sustained viability and an extended production phase, although the mechanisms regulating these phenotypes during mild hypothermia are poorly understood.     

Ependymal cells in tissue culture

Summary Ciliated ependymal cells from various locations of the ventricular system of mammals showed outgrowth either in the form of epithelial sheets or in the form of pools and elongated double rows, dependant on the site from which the ependyma was taken and on the original orientation of the cells in respect to the cover slip.The ependymal cilia in such cultures were shown to be moving at a rate of 51/2 to 6 times per second. The movement of the cilia of adjacent cells was apparently well coordinated causing the surrounding fluid to flow in a particular direction.The effect of physiological saline, morphine sulfate, ethyl and methyl alcohol on the ciliary motility has been studied in living cells with phase contrast cinematography.Grateful acknowledgement is made to Messers G. Lefeber, E. Pitsinger and J. Carnes for indispensible aid with photographic work. Mrs. J. Finerty and Mrs. W. Hild contributed generously in the management of the tissue cultures and in executing staining procedures.This investigation was supported by a research grant [PHS B-364 (C3)] from the National Institute of Neurological Diseases and Blindness, of the National Institutes of Health, Public Health Service, administered by C. M. Pomerat.     

A tissue culture method for propagation and low temperature storage of Trifolium repens genotypes

Proliferating shoot cultures of Trifolium repens L . cv. Grasslands Huia have been established on Murashige and Skoog's medium containing 3% sucrose and 0.2 mg l⁻¹ benzylamino purine. The shoots could be readily rooted on media without cytokinin and transferred to potting mix with 100% survival. The cultured shoots have been stored for 10 months, at 5°C in darkness without adversely affecting their potentiality for rapid multiplication. The significance of this approach for genotype storage is discussed.     

Irradiation of cells in tissue culture

Summary Strain cultures of the cervical carcinoma HeLa (Puck-clone), human fetal intestinal epithelium (Henle) and adult human skin (NCTC clonal 2414) were used in Rose chambers for gamma irradiation at 2000 r and 4000 r from a Cobalt⁶⁰ source.Phase contrast, time-lapse cinematographic records generally made from one to 5 days following irradiation yielded a total of more than 6000 feet of 16 mm film records for analysis.Cell enlargement was regularly observed. Telo-reduplication, including a second division is reported. Multinucleation arising from cells with single and multiple nuclei producing one or two daughter cells with numerous micronuclei was found for all three strains.It is believed that these mitotic anomalies represented a quantitative rather than a qualitative difference between irradiated and control cultures.The method permits an accurate assessment of the divisional potentialities of living cells during long periods of life in vitro under experimental conditions.This research was supported by the USAF under Contract No. AF 18(600)-1263, monitored by the School of Aviation Medicine, USAF, Randolph Air Force Base, Texas.Captain, USAF (MSC).     

Irradiation of cells in tissue culture

Summary Cultures of human amnion were employed to check the hypothesis that cell strains with heteroploid chromosome counts regularly produce giant cells within 12 days following treatment with 2000 r and 4000 r of gamma irradiation from a cobalt source, while this response has not been obtained from primary cultures whose cells were presumed to be diploid.The giant cell reaction not only was obtained from two transfer passage lines of a well-established amnion strain developed at Berkeley (No A 185-21C-26 and No A 185-21C-45) but was also found for a 20-day second passage culture of amnion. Since this line has continued to reproduce at a rapid rate, it is presumed to have assumed the features of a typical strain within the period of observation. This impression was reinforced by the finding that the chromosome number for 32 cells fixed on the 35th day had a modal value of 67.In contrast, both untrypsinized and trypsinized spindle cells in primary cultures as well as unaltered epithelial elements which had not been subcultured gave no evidence of giant cell formation 12 days after exposure to 2000 r and 4000 r from a Cobalt⁶⁰ source.These data lend evidence that giant cell formation is related to the chromosomal constitution of the irradiated elements.This research was supported by funds provided under Contract AF 18(600)-1263 with the School of Aviation Medicine, USAF, Randolph Air Force Base, Texas.Fellow of the Instituto de Alta Cultura and the Fundacão Calouste Gulbenkian of Lisbon, Portugal.Tobacco Industry Research Committee Fellow.