Comparison of coulter volumes with radiometrically determined intracellular water volumes for cultured cells

Summary During methotrexate-induced differentiation of cultured human choriocarcinoma (BeWo) cells, proliferation is inhibited, morphologic and biochemical changes occur, and giant, often multinucleated, cells form. We have used the increase in cell volume as a marker of the mature syncytiotrophoblastlike phenotype. Uninduced and differentiated BeWo cells are not spherical, and theoretical considerations suggested that deviations in shape could result in significant errors in Coulter volume. To determine if the values obtained by electrical pulse sizing reflected the actual mass of BeWo cells, we have evaluated the relationship between Coulter volumes and intracellular water volumes obtained using a shape-independent estimate for eight cell types. A close correlation (r ²=0.97) was found, indicating that cell volume changes in populations of irregularly shaped cells can be accurately measured using a Coulter instrument. Supported by an operating grant from the National Cancer Institute of Canada. N.S.B. was a recipient of a studentship award from the Alberta Heritage Foundation for Medical Research. C.E.C. is a Senior Research Scientist of the National Cancer Institute of Canada. The McEachern Laboratory is a research facility of the Faculty of Medicine, University of Alberta, and the Cross Cancer Institute, Edmonton, Alberta.     

Nitrogen concentration of cauliflower organs as determined by organ size,N supply,and radiation environment

Data from field experiments carried out in three consecutive years under contrasting N supply and radiation environment altered by artificial shading were used to identify (a) the relationship between N concentration and organ size under conditions of unrestricted N supply and (b) critical levels of soil nitrate (Nmin_crit), where nitrogen concentration of cauliflower organs begin to decline because of N limitations. The decline of N concentrations in cauliflower was analysed at different levels of morphological aggregation, i.e., the whole shoot level, the organ level (leaves, stem, and curd), and within different leaf groups within the canopy. Nmin_crit values (0–60 cm soil depth) for total nitrogen concentration of cauliflower organs leaves, stem and curd were estimated at 85, 93 and 28 kg N ha^–1, respectively. Within the canopy, Nmin_crit values for total N of leaves increased from the top to the bottom from 44 to 188 kg N ha^–1. Nmin_crit values for protein N in leaves from different layers of the canopy were much lower at around 30 kg N ha^–1, without a gradient within the canopy. It is discussed that these differences in Nmin_crit values are most likely a consequence of N redistribution associated with nitrogen deficiency. The decline of average shoot nitrogen concentrations, [Nm] (%N DM), with shoot dry matter, W _sh, (t ha^–1) under conditions of optimal N supply was [Nm]= 4.84 (±0.071) W _sh ^{–0.089(± 0.011)}, r ²=0.67 (±S.E.). The reduction of radiation intensity by artificial shading (60% of control) had no significant influence on total nitrogen concentrations of leaves and only a small influence on protein nitrogen concentrations in lower layers of the canopy. The leaf nitrate nitrogen fraction of nitrogen, f _nitr (–), within the canopy decreased linearly with increased average incident irradiance in different canopy layers (I _av, W PAR m^–2) (f _Nitr. = 0.2456(±0.0188) – 0.0023(±0.0004)I _av, r ² = 0.67.     

GF昆明小鼠主要重量系数及血液生理指标的测定

目的测定无菌KM小鼠体重、体长、尾长、脏器系数、血常规值。方法选取8只全雄无菌KM小鼠,8只SPF级测量体重、体长、尾长;检测红细胞总数(RBC),血红蛋白(HGB),红细胞压积(HCT),平均红细胞体积(MCV),血小板总数(PLT),白细胞总数(WBC),白细胞分类(DLC),平均血红蛋白含量(MCH),平均血红蛋白浓度(MCHC)等血液生理指标;解剖采集小鼠心脏、肝脏、脾脏、肺、肾、睾丸、盲肠,称重,计算脏器系数(脏器系数=脏器湿重/体重×100)。结果体长、尾长、心脏、脾脏、肺、肾脏、脑、睾丸、及血液生理指标等项目差异无统计学意义(P>0.05),体重、肝脏、盲肠项目差异有统计学意义(P<0.05)。结论所测数值为研究者提供基础数据,建立国内无菌KM小鼠背景资料。