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991.
Alexandra Marinets Miklós Müller Patricia J. Johnson Jaroslav Kulda Otto Scheiner Gerhard Wiedermann Michael Duchêne 《Journal of molecular evolution》1996,43(6):563-571
Among the unicellular protists, several of which are parasitic, some of the most divergent eukaryotic species are found. The evolutionary distances between protists are so large that even slowly evolving proteins like histones are strongly divergent. In this study we isolated cDNA and genomic histone H3 and H4 clones fromTrichomonas vaginalis. Two histone H3 and three histone H4 genes were detected on three genomic clones with one complete H3 and two complete H4 sequences. H3 and H4 genes were divergently transcribed with very short intergenic regions of only 194 bp, which containedT. vaginalis-specific as well as histone-specific putative promoter elements. Southern blot analysis showed that there may be several more histone gene pairs. The two complete histone H4 genes were different on the nucleotide level but encoded the same amino acid sequence. Comparison of the amino acid sequences of theT. vaginalis H3 and H4 histones with sequences from animals, fungi, and plants as well as other protists revealed a significant divergence not only from the sequences in multicellular organisms but especially from the sequences in other protists likeEntamoeba histolytica, Trypanosoma cruzi, andLeishmania infantum. 相似文献
992.
Our cytological analysis revealed high proportions of XX males in some housefly populations of Turkey. In contrast to earlier findings in Europe, on the British Islands, and in Japan, the XX male frequency in Turkey was not correlated to the geographical latitude. In general, the frequency of XX males was lower in populations from the central and eastern Anatolian highlands than from coastal regions, demonstrating a correlation of the sex-determining mechanisms to geographical altitude and perhaps other geographical characteristics. 相似文献
993.
994.
This paper summarizes the processing of small enchytraeid species for cinematographic documentation and covers the main details of a film on their locomotion, food uptake, anatomy and reproductive biology. This includes copulation, shedding of the cocoon and hatching of the young, characteristic reproductive patterns for all clitellate worms. 相似文献
995.
Aphids of the genus Cinara, feeding on Norway spruce, excrete copious amounts of honeydew, a carbon-rich waste product, which accumulates locally on needles and twigs. We investigated the role of honeydew as a potential source of energy which might promote the growth of micro-organisms in the phyllosphere of conifer trees. To approach this question, we followed the population dynamics of Cinara spp. in a natural forest stand over two seasons. We also studied the amounts of honeydew produced by individual aphids and identified potential parameters which might influence honeydew production. Finally, we determined the growth of micro-organisms on infested and uninfested needles of Norway spruce during the growing season. Confined to Picea abies, the investigated Cinara species only became abundant in midsummer, when needles and shoots were expanding. The populations showed only a single peak in abundance, the timing and magnitude of which may vary from year to year due to weather conditions, changes in plant quality in a yearly cycle or the impact of natural enemies. The amount of honeydew produced by individual aphids was dependent on the developmental stage of the aphid, the nutritional supply of its host plant and on the developmental state of the Norway spruce (e.g. bud burst, end of shoot extension). The presence of honeydew significantly increased the growth of bacteria, yeast and filamentous fungi on the surface of needles and there was a pronounced seasonal trend, with the highest abundance in midsummer correlating with the period of peak aphid abundance. Taken together, these findings indicate that aphids have an influence on microbial ecology in the phyllosphere of trees. The implication of our study, from interactions at the population level to effects and potential consequences for C and N fluxes at the level of forest ecosystems, is discussed. 相似文献
996.
H. Schöne 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,179(4):587-592
Honeybees returning from foraging trips were video-filmed while they walked through a narrow transparent gangway to reach the hive entrance. On their way they were presented with black-and-white gratings viewed underneath as well as to both sides of the gangway. Bees could exit the gangway through one of two or three side exits installed at different distances from the gangway entrance. In one set of experiments, the substrate on which the bees walked was moved either in the bee's direction or against it. In another set of experiments, the substrate was stationary, but the pattern was moved in one or the other direction. The bee's walking speed (WS) was evaluated from the video tapes. When the substrate moved against, or the pattern in the bee's direction, in either case decreasing the speed of pattern flow (PFS), the bees increased WS, and, at the same time, they preferred the more distant exit. When the substrate moved in, or the pattern against the bee's direction, thus increasing PFS, WS decreased and the bees preferred the nearer exit. These results suggest that the speed of optic flow controls the speed of locomotion and might therefore also serve for assessing the distance travelled.Abbreviations
PFS
pattern-flow speed
-
WS
walking speed
Dedicated to Hans-Jochen Autrum, editor emeritus, for help in giving birth to this and many other papers over very many years, often with criticism but nevertheless with encouragement and sympathy. 相似文献
997.
Fetal cells in maternal blood: recovery by charge flow separation 总被引:11,自引:0,他引:11
S. S. Wachtel David Sammons Michael Manley Gwendolyn Wachtel Garland Twitty Joseph Utermohlen Owen P. Phillips Lee P. Shulman Douglas J. Taron U. R. Müller Peter Koeppen Teresa M. Ruffalo Karen Addis Richard Porreco Joyce Murata-Collins Natalie B. Parker Loris McGavran 《Human genetics》1996,98(2):162-166
Fetal blood cells can be recovered from the maternal circulation by charge flow separation (CFS), a method that obviates the
risks associated with amniocentesis and chorionic villus sampling. By CFS, we processed blood samples from 13 women carrying
male fetuses, 2 carrying fetuses with trisomy 21, and 1 who had delivered a stillborn infant with trisomy 18. On average more
than 2000 fetal nucleated red blood cells were recovered per 20-ml sample of maternal blood. Recovery of fetal cells was confirmed
by fluorescence in situ hybridization with probes for chromosomes Y, 18 and 21. After culturing of CFS-processed cells, amplification
by the polymerase chain reaction revealed Y-chromosomal DNA in clones from four of six women bearing male fetuses, but not
in clones from three women bearing female fetuses.
Received: 8 January 1996 / Revised: 22 March 1996 相似文献
998.
James D. Pancook Jürgen C. Becker Stephen D. Gillies R. A. Reisfeld 《Cancer immunology, immunotherapy : CII》1996,42(2):88-92
A major problem in the treatment of solid tumors is the eradication of established, disseminated metastases. Here we describe
an effective treatment for established experimental hepatic metastases of human neuroblastoma in C. B.-17 scid/scid mice. This was accomplished with an antibody-cytokine fusion protein, combining the unique targeting ability of antibodies
with the multifunctional activity of cytokines. An anti-(ganglioside GD2) antibody (ch14.18) fusion protein with interleukin-2
(ch14.18-IL2), constructed by fusion of a synthetic sequence coding for human interleukin-2 (IL-2) to the carboxyl end of
the Cγ1 gene of ch14.18, was tested for its therapeutic efficacy against xenografted human neuroblastoma in vivo. The ch14.18-IL2
fusion protein markedly inhibited growth of established hepatic metastases in SCID (severe combined immunodeficiency) mice
previously reconstituted with human lymphokine-activated killer cells. Animals treated with ch14.18-IL2 showed an absence
of macroscopic liver metastasis. In contrast, treatment with combinations of ch14.18 and recombinant IL2 at dose levels equivalent
to the fusion protein only reduced the tumor load. Survival times of SCID mice treated with the fusion protein were more than
double that of control animals. These results demonstrate that an immunotherapeutic approach using a cytokine targeted by
an antibody to tumor sites is highly effective in eradicating the growth of established tumor metastases.
Received: 7 November 1995 / Accepted: 15 December 1995 相似文献
999.
Induction of accessory cell function of human alveolar macrophages by inhalation of human natural interleukin-2 总被引:1,自引:0,他引:1
Gernot Zissel Walter E. Aulitzky J. Lorenz Christoph Huber J. Müller-Quernheim 《Cancer immunology, immunotherapy : CII》1996,42(2):122-126
Accessory function allows antigen-presenting cells to produce sufficient secondary signals for optimum T cell proliferation
and interleukin-2 (IL-2) production. Alveolar macrophages are inferior accessory cells compared to monocytes (PBM). We report
here that the accessory index (AI) of alveolar macrophages and PBM of patients with lung metastases of solid tumors treated
with inhalations of human natural IL-2 (hnIL-2) increased following its administration (P<0.005). The accessory index was significantly elevated from baseline values after 2 weeks of inhalation of 300 000 IU hnIL-2/day
(8.2±10.2 compared to 1.1±1; P<0.001). The inhalation of 150 000 IU also induced increases in the index (AI = 2.3±1.9), however, without reaching statistical
significance. In addition at 300 000 IU IL-2/day a significant increase in the accessory index was observed for PBM (4±2.5;
P<0.05). The indices of PBM and alveolar macrophages prior to inhalation showed a significant negative correlation with the
age of the patients (r
s = – 0.5; r
s = – 0.8, respectively; P<0.03 for all comparisons). Our data demonstrate that the inhalational application of hnIL-2 enhances the accessory function
of alveolar macrophages and, to lesser extent, the accessory index of PBM, indicating the occurrence of pharmacological immunostimulation.
Received: 16 August 1995 / Accepted: 4 January 1996 相似文献
1000.