Cell number and cellular composition in vermiform larvae of dicyemid mesozoans

Cell numbers and cellular composition were examined in vermiform larvae of 44 species of dicyemid mesozoans phylum Dicyemida belonging to six genera: Conocyema , Dicyema , Dicyemennea , Dicyemodeca , Microcyema and Pseudicyema . In addition, the literature on vermiform larvae of another 59 species was reviewed. Vermiform larvae typically have a constant number of peripheral cells that are species specific. Interspecific variations in the total number of peripheral cells range from 10 to 39. The most frequent number is either 22 or 23. Differences in the total number of peripheral cells are mostly due to differences in the number of trunk peripheral cells, such as parapolar cells, diapolar cells and uropolar cells. The body length of vermiform larvae is positively correlated with the number of trunk peripheral cells. Interspecific variations in the total number of trunk peripheral cells range from 2 to 31. The most frequent number is 14. In species with 14 trunk peripheral cells, individual variations of cell numbers were minimal. In species with more trunk peripheral cells, some individual variations appeared. Increase and decrease of trunk cell number might cause diversity of dicyemids, which is possibly related to speciation in these simple multicellular animals.     

Low dispersal ability and habitat specificity promote extinctions in rare but not in widespread species: the Orthoptera of Germany

Local extinctions are often non‐randomly associated with range size, dispersal ability and habitat specificity, as well as body size, sexual dimorphism and phylogeny. We used a large data set of the Orthoptera species (bush crickets, crickets, grasshoppers) occurring in Germany and compared the number of occupied grid cells before 1980 to those occupied after 1980, corrected for monitoring intensity. The number of grid cells in which a species went extinct was non‐linearly related to the number of occupied grid cells per species. Using generalized linear modelling we analysed extinction in relation to national distribution (the number of occupied grid cells before 1980), dispersal ability (derived from a large body of literature concerning wing development, colonization dynamics and within‐habitat mobility), habitat specificity (moisture specialists versus generalists), potential reproduction (the number of ovarioles), the degree of sexual size dimorphism and phylogeny (twelve clades). Species with a large global range size also had a large national range size. Species with a large range experienced more total extinction events than species with smaller ranges but relatively fewer compared to range size. The latter relationship was largely shaped by the dispersal ability of the species: the interactions of range size×dispersal ability and range size×habitat specificity explained almost one third of the variation in the number of extinction events. Species with high dispersal ability went extinct in a similar number of grid cells irrespective of their range size. By contrast, species with low dispersal ability went extinct in proportion to their range size. Therefore, comparing the speed of extinction across species in the conventional way of extinction rates (that is the percentage of range contraction) might be flawed because it only applies to species with low dispersal ability. Sexual size dimorphism was not a significant predictor of extinction. Extinction was not concentrated on particular clades.     

Dynamic Range of Vertebrate Retina Ganglion Cells: Importance of Active Dendrites and Coupling by Electrical Synapses

The vertebrate retina has a very high dynamic range. This is due to the concerted action of its diverse cell types. Ganglion cells, which are the output cells of the retina, have to preserve this high dynamic range to convey it to higher brain areas. Experimental evidence shows that the firing response of ganglion cells is strongly correlated with their total dendritic area and only weakly correlated with their dendritic branching complexity. On the other hand, theoretical studies with simple neuron models claim that active and large dendritic trees enhance the dynamic range of single neurons. Theoretical models also claim that electrical coupling between ganglion cells via gap junctions enhances their collective dynamic range. In this work we use morphologically reconstructed multi-compartmental ganglion cell models to perform two studies. In the first study we investigate the relationship between single ganglion cell dynamic range and number of dendritic branches/total dendritic area for both active and passive dendrites. Our results support the claim that large and active dendrites enhance the dynamic range of a single ganglion cell and show that total dendritic area has stronger correlation with dynamic range than with number of dendritic branches. In the second study we investigate the dynamic range of a square array of ganglion cells with passive or active dendritic trees coupled with each other via dendrodendritic gap junctions. Our results suggest that electrical coupling between active dendritic trees enhances the dynamic range of the ganglion cell array in comparison with both the uncoupled case and the coupled case with cells with passive dendrites. The results from our detailed computational modeling studies suggest that the key properties of the ganglion cells that endow them with a large dynamic range are large and active dendritic trees and electrical coupling via gap junctions.     

Evaluation of carriers used in the test methods of the Association of Official Analytical Chemists.

Revision of the official test method for the determination of the tuberculocidal activity of disinfectants is being undertaken. The current procedure lacks precision and accuracy and is not quantitative. Variability associated with carriers and the lack of temperature control were evaluated in this paper. The use of porcelain versus stainless steel carriers was also evaluated. When carriers of either type were contaminated with Mycobacterium bovis BCG, the number of organisms on the carriers varied by as much as 1.0 on the log10 scale. The average number of organisms attached to each porcelain carried was 1.10 x 10(5) CFU (range, 2.7 x 10(4) to 2.7 x 10(5) CFU), whereas the average number of organisms attached to each stainless steel carrier was 1.38 x 10(5) CFU (range, 2.9 x 10(4) to 4.0 x 10(5) CFU). The average number of cells attached to the carrier was directly proportional to the number of cells in the contaminating cell suspension. Variations in drying time did not alter the number of cells attached to the carrier. When porcelain carriers were placed in a test solution, the average number of organisms washed from the carriers was 55% of the total, with a range of 19 to 80%, whereas for stainless steel carriers, the average number was 82% of the total, with a range of 52 to 96%. Data for B. subtilis spores were similar to those for M. bovis BCG, suggesting that there may be similar problems with the Association of Official Analytical Chemists sporicidal test, which uses carriers. It was also found that the lack of an exacting temperature control could influence the outcome of the test. Changes in temperature as little as 1 degree C could influence the rate of killing of M. bovis BCG.     

Evaluation of carriers used in the test methods of the Association of Official Analytical Chemists

Revision of the official test method for the determination of the tuberculocidal activity of disinfectants is being undertaken. The current procedure lacks precision and accuracy and is not quantitative. Variability associated with carriers and the lack of temperature control were evaluated in this paper. The use of porcelain versus stainless steel carriers was also evaluated. When carriers of either type were contaminated with Mycobacterium bovis BCG, the number of organisms on the carriers varied by as much as 1.0 on the log10 scale. The average number of organisms attached to each porcelain carried was 1.10 x 10(5) CFU (range, 2.7 x 10(4) to 2.7 x 10(5) CFU), whereas the average number of organisms attached to each stainless steel carrier was 1.38 x 10(5) CFU (range, 2.9 x 10(4) to 4.0 x 10(5) CFU). The average number of cells attached to the carrier was directly proportional to the number of cells in the contaminating cell suspension. Variations in drying time did not alter the number of cells attached to the carrier. When porcelain carriers were placed in a test solution, the average number of organisms washed from the carriers was 55% of the total, with a range of 19 to 80%, whereas for stainless steel carriers, the average number was 82% of the total, with a range of 52 to 96%. Data for B. subtilis spores were similar to those for M. bovis BCG, suggesting that there may be similar problems with the Association of Official Analytical Chemists sporicidal test, which uses carriers. It was also found that the lack of an exacting temperature control could influence the outcome of the test. Changes in temperature as little as 1 degree C could influence the rate of killing of M. bovis BCG.     

PCR quantitation of fetal cells in maternal blood in normal and aneuploid pregnancies.

Fetal cells in maternal blood are a noninvasive source of fetal genetic material for prenatal diagnosis. We determined the number of fetal-cell DNA equivalents present in maternal whole-blood samples to deduce whether this number is affected by fetal karyotype. Peripheral blood samples were obtained from 199 women carrying chromosomally normal fetuses and from 31 women with male aneuploid fetuses. Male fetal-cell DNA-equivalent quantitation was determined by PCR amplification of a Y chromosome-specific sequence and was compared with PCR product amplified from known concentrations of male DNA run simultaneously. The mean number of male fetal-cell DNA equivalents detected in 16-ml blood samples from 90 women bearing a 46,XY fetus was 19 (range 0-91). The mean number of male fetal-cell DNA equivalents detected in 109 women bearing a 46,XX fetus was 2 (range 0-24). The mean number of male fetal-cell DNA equivalents detected when the fetus was male compared with when the fetus was female was highly significant (P = .0001). More fetal cells were detected in maternal blood when the fetus was aneuploid. The mean number of male fetal-cell DNA equivalents detected when the fetal karyotype was 47,XY,+21 was 110 (range 0.1-650), which was significantly higher than the number of male fetal-cell DNA equivalents detected in 46,XY fetuses (P = .0001). Feto-maternal transfusion of nucleated cells appears to be influenced by fetal karyotype. The sixfold elevation of fetal cells observed in maternal blood when the fetus had trisomy 21 indicates that noninvasive cytogenetic diagnosis of trisomy 21 should be feasible.     

Effect of electromagnetic microwave radiation on the growth of Ehrlich ascites carcinoma

Daily exposure of mouse recipients of Ehrlich ascites carcinoma to electromagnetic radiation of the microwave range leads to a change in the dynamics of tumor growth by decreasing the total number of cells. The number of tumor cells with blebbing morphological signs after microwave radiation increases gradually with tumor growth. The maximum content of tumor cells in the state of blebbing is observed during active proliferation in tumor-recipient mice of the control group (without irradiation).     

Instability of B-chromosomes in somatic and germline cells of Apodemus peninsulae

Instability of B-chromosomes was estimated in somatic and germline cells of samples Apodemus peninsulae from different localities of the species range. In 84 out of 188 animals (45%), in cells assessed for B-chromosome mosaicism, bone marrow cells with different B-chromosome number were observed. The numbers of B-chromosomes in spermatocytes at the pachytene stage were estimated in ten males. It was shown that the average number of B-chromosomes and the number of cell clones in germline cells was higher than the corresponding numbers in bone marrow cells. The higher number of B-chromosomes and their higher variability in germline cells than in somatic cells suggest the existence of a mechanism of premeiotic accumulation of B-chromosomes in spermatogenesis of A. peninsulae.     

制备精原干细胞滋养层细胞条件的优化

目的:优化精原干细胞培养滋养层细胞的制备条件。方法:首先根据文献资料报道和实践经验确定丝裂霉素C作用STO细胞的浓度范围和时间范围,利用双因素优选法缩短丝裂霉素C处理STO细胞的试验范围。然后采用MTT检测法确定丝裂霉素C处理STO细胞的最佳浓度和时间。结果:滋养层细胞处理后不经过冷冻保存的情况下,17.64μg/ml 2 h处理条件的STO细胞在培养14天内细胞数量基本保持稳定,其它处理条件的细胞数量均有所增加;经冷冻保存的情况下,14.72μg/ml 2 h处理条件的STO细胞在培养14天内细胞数量基本保持稳定,其它处理条件的细胞数目均有所降低。结论:滋养层细胞处理后不经过冷冻保存的情况下,17.64μg/ml 2 h的处理条件是丝裂霉素C处理STO细胞的最佳条件;经冷冻保存的情况下,14.72μg/ml 2 h的处理条件是丝裂霉素C处理STO细胞的最佳条件。     

银鹊树胚性愈伤组织继代培养过程中的细胞染色体数目变异

以银鹊树幼嫩的合子胚为外植体诱导胚性愈伤组织,胚性愈伤经增殖后转接到液体培养基中悬浮继代培养,对其多次继代培养的胚性愈伤细胞的染色体数目检测发现:多次继代培养后的胚性愈伤细胞染色体数正常的比例为48.28%(2n=30),部分细胞出现染色体数目2n=15~60的变异,其变异率高达51.72%,其中以亚二倍体变异为主(40.07%).结果表明,在体细胞胚胎诱导形成过程中,胚性愈伤组织细胞在染色体水平上发生部分变异,这可能是体胚形成过程中畸形胚产生的根本原因.     

Instability of B-chromosomes in somatic and germline cells of Apodemus peninsulae

Instability of B-chromosomes was estimated in somatic and germline cells of samples Apodemus peninsulae from different localities of the species range. In 84 out of 188 animals (45%), in cells assessed for B-chromosome mosaicism, bone marrow cells with different B-chromosome number were observed. The numbers of B-chromosomes in spermatocytes at the pachytene stage were estimated in ten males. It was shown that the average number of B-chromosomes and the number of cell clones in germline cells was higher than the corresponding numbers in bone marrow cells. The higher number of B-chromosomes and their higher variability in germline cells than in somatic cells suggest the existence of a mechanism of premeiotic accumulation of B-chromosomes in spermatogenesis of A. peninsulae     

Epileptogenesis following Kainic Acid-Induced Status Epilepticus in Cyclin D2 Knock-Out Mice with Diminished Adult Neurogenesis

The goal of this study was to determine whether a substantial decrease in adult neurogenesis influences epileptogenesis evoked by the intra-amygdala injection of kainic acid (KA). Cyclin D2 knockout (cD2 KO) mice, which lack adult neurogenesis almost entirely, were used as a model. First, we examined whether status epilepticus (SE) evoked by an intra-amygdala injection of KA induces cell proliferation in cD2 KO mice. On the day after SE, we injected BrdU into mice for 5 days and evaluated the number of DCX- and DCX/BrdU-immunopositive cells 3 days later. In cD2 KO control animals, only a small number of DCX+ cells was observed. The number of DCX+ and DCX/BrdU+ cells/mm of subgranular layer in cD2 KO mice increased significantly following SE (p<0.05). However, the number of newly born cells was very low and was significantly lower than in KA-treated wild type (wt) mice. To evaluate the impact of diminished neurogenesis on epileptogenesis and early epilepsy, we performed video-EEG monitoring of wt and cD2 KO mice for 16 days following SE. The number of animals with seizures did not differ between wt (11 out of 15) and cD2 KO (9 out of 12) mice. The median latency to the first spontaneous seizure was 4 days (range 2 – 10 days) in wt mice and 8 days (range 2 – 16 days) in cD2 KO mice and did not differ significantly between groups. Similarly, no differences were observed in median seizure frequency (wt: 1.23, range 0.1 – 3.4; cD2 KO: 0.57, range 0.1 – 2.0 seizures/day) or median seizure duration (wt: 51 s, range 23 – 103; cD2 KO: 51 s, range 23 – 103). Our results indicate that SE-induced epileptogenesis is not disrupted in mice with markedly reduced adult neurogenesis. However, we cannot exclude the contribution of reduced neurogenesis to the chronic epileptic state.     

The other mediator for adherence of Haemophilus influenzae organisms without involvement of fimbriae.

The number of the nontypeable Haemophilus influenzae (HiN) organisms that adhered to the primary mouse fetal lung cells was significantly more than type b Haemophilus influenzae (Hib) organisms. The average number of HiN organisms adherent to host cells was 2,291/100 host cells (range, 1,654-3,182), but that of Hib was markedly reduced to 147/100 host cells (range, 102-238). In this case, P value was less than 0.05 by using a paired Student t-test. The sonicated extract from HiN TMS11 organisms inhibited adherence of H. influenzae TMS11 organisms to monolayer at 76.3% and it inhibited adherence of Hib TMS24 organisms at 92.3%. This result indicates that a mediator existing on the surface of HiN organisms may be the same as that on type b organisms. The number of detected organisms in broncho and lung tissues 3 days after intranasal infection with HiN strains was significantly greater than that in infection with Hib strains. Therefore, in vitro adhesive capacity of H. influenzae organisms was correlative to infectivity by intranasal injection.     

The enumeration of Leptospira interrogans serovar pomona by a bioluminescence ATP assay

A rapid method for enumerating viable Leptospira interrogans serovar pomona cells was investigated using a bacterial adenosine triphosphate (ATP) assay. The ATP was assayed by the luciferin-luciferase bioluminescence reaction. Samples of serovar pomona grown in liquid polysorbate 80-bovine albumin (P80-BA) medium for 1-3 days were analysed for ATP content, culture density (nephelometry), direct cell count and most probable number of viable cells (MPNVC) as determined by the dilution tube technique. A linear relationship was found between ATP content and the number of viable cells over the range of 4 X 10(8) to 8 X 10(9) leptospires/ml. Over this range the correlation coefficient for ATP content versus viable cells (0.96) was similar to the coefficient for culture density versus the number of viable cells. The coefficient for direct counts versus the number of viable cells was smaller. The bioluminescence assay of bacterial ATP is a promising method for enumerating viable leptospires in pure culture.     

Artificial induction of chromosome aneuploidy in CHO cells alters their function as host cells

Chinese hamster ovary (CHO) cells are major host cells for biopharmaceuticals. During culture, the chromosome number of CHO cells alters spontaneously. Here, we investigated the effects of artificial changes in the chromosome number on productivity. When cell fusion between antibody-producing CHO-K1-derived cells was induced, we observed a wide range of aneuploidy that was not detected in controls. In particular, antibody productivities were high in clone-derived cell populations that retained a diverse chromosome number distribution. We also induced aneuploid cells using 3-aminobenzamide that causes chromosome non-disjunction. After induction of aneuploidy by 3-aminobenzamide, cells with an increased chromosome number were isolated, but cells with a decreased chromosome number could not be isolated. When antibody expression vectors were introduced into these isolated clones, productivity tended to increase in cells with an increased chromosome number. Further analysis was carried out by focusing on clone 5E8 with an average chromosome number of 37. When 5E8 cells were used as host, the productivity of multiple antibodies, including difficult-to-express antibodies, was improved compared with CHO-K1 cells. The copies of exogenous genes integrated into the genome were significantly increased in 5E8 cells. These findings expand the possibilities for host cell selection and contribute to the efficient construction of cell lines for recombinant protein production.     

Cytogenetic changes in the Namalwa cell line of human malignant lymphoma induced by inhibitors of DNA replication and synthesis

Namalwa cells originating from the malignant human lymphoma have been analyzed cytogenetically upon short-time exposure to subtoxic doses of inhibitors of DNA replication and synthesis, either etoposide or fludarabine. The intact cells were characterized by the modal class of the chromosomes within the diploid range with the proportion of the aberrant cells amounting to 16.0 +/- 0.5%. Upon exposure to etoposide the percentage of the aberrant cells increased amounting to 26.1 +/- 2.9 through 39.8 +/- 1.7% depending on the duration of the exposure and the dose of the drug. At the same time the number of the polyploid cells increased but the modal class retained within the diploid range. Upon exposure to fludarabine the percentage of the cells with the aberrant chromosomes increased to 57.1 +/- 2.9%. Two modal classes appeared--the first approaching the diploid number and the second being polyploid. The exposure to either etoposide or fludarabine resulted in increasing number of the chromatide aberrations with more frequent involvement of #1, #2, #5, #6, #7, #11, #13, #14, #16 and #17 chromosomes. The data obtained have shown the susceptibility of Namalwa cells to the subtoxic concentrations of the inhibitors of DNA synthesis and replication used in the study resulting in the survival of the novel clones resistant to the drugs.     

Microcalorimetric measurements of tissue cells in vitro

A culture flask was designed for the microcalorimetric measurements of tissue cells by an MS 80 standard calvet microcalorimeter. Tissue cells cultured in this flask behaved in the same manner as in the common culture flask used in cytobiological studies. The thermograms of human adenocarcinoma gastric cells (SGc 7901) and HeLa cells were obtained. The heat output power of SGc 7901 cells continuously increased for 70 h with an initial cell number of 3.0 X 10(5). The thermogram was reproducible under strictly controlled conditions. The relationship between the heat output power and the number of SGc 7901 cells within 48 h was obtained. The heat output power was 40 pW/cell to 49 pW/cell when the cell number was in the range 4.5 X 10(5) to 10.4 X 10(5). It was 62.3 +/- 2.9 pW/cell for HeLa cells when the cell number was 6 X 10(5).     

Effect of mycoplasma contamination of a human cervical carcinoma cell line M HeLa clone 11 on karyotypic variability

The karyotypic variability has been investigated for an immortalized human epithelioid cervix carcinoma cell line M HeLa clone 11, cultivated for 15-60 days after contamination with Acholeplasma laidlawii A, strain PG-8, and for 30 days after contamination with Mycoplasma arginini R-16. The character of cell distribution for chromosome number changes in contaminated cells significantly, as compared to the control. So, the frequency of cells with the modal number of chromosomes being equal to 50 decreases significantly, and the range of variability in the number of chromosomes increases. With the prolongation of the term of cultivation in control variants up to 60 days the character of cell distribution for chromosomal number changes, as compared to the preceding terms (15 and 30 days), which is expressed in the extended range of variability in the chromosomal number at the expense of decreased frequency of cells with submodal number of chromosomes equal to 49. But the degree of these changes is significantly smaller than in contaminated variants. The frequency of polyploid cells did not differ in all investigated variants. The number of chromosomal aberrations in cultures contaminated with A. laidlawii (for 15-60 days) and M. arginini (for 30 days) does not differ from that in the corresponding controls. The absence of dicentrics (telomeric association) at a long-term contamination of the human epithelioid cervix carcinoma cell line M HeLa clone 11 having marker chromosomes in karyotype and a comparison of these results with the earlier obtained data on other "marker" and "markerless" cell lines seems to confirm the point of view that dicentrics appear a characteristic feature of karyotypic variability of "markerless" cell lines, mainly with a long-term contamination in different conditions.     

The efficiency and direction of thymus changes after whole-body exposure of mice to the weak electromagnetic field are determined by the initial status of the thymus

The work presents results of the experimental study on thymus changes developing after whole-body exposure of mice to ultralow power pulse-modulated electromagnetic field (carrying frequency 2.39 GHz, modulating pulses with frequency 4 Hz, duration of impulses 0.025 sec, average power density 60 mW/cm2, absorbed dose 0.086 J/g or 0.172 J/g). It was shown that a percent of the microwave induced increase or decrease of thymus mass and the number of cells in the organ (y) are determined by the initial mass or number of cells in thymus accordingly to equation of linear regression: (yx = 215-2.25x, where x is the thymus mass of control animals (in a range 31-63 mg) and (yx = 178.6-41x, where x is the initial number of cells in thymus (in a range 0.6 x 10(8)-2.6 x 10(8)) reduced by a factor of 10(8).