罗汉果双受精过程的细胞学观察

罗汉果（Ｓｉｒａｉｔｉａｇｒｏｓｖｅｎｏｒｉ（Ｓｗｉｎｇｌｅ）Ｃ．Ｊｅｍｅｙ）双受精过程属有丝分裂前配子融合类型,授粉后２４～４８ｈ,花粉管进入胚囊,穿过一个助细胞,放出两个精子。雌雄核融合和雄核与次生核融合同时发生在授粉后６２～７２,雄核与次生核融合速度快于配子融合,７２ｈ后即可见到初生胚乳核分裂。合子中的雌雄核仁在授粉后第５～６ｄ融合,授粉后８～９ｄ合成分裂形成二细胞胚。在双受精过程中,多次观察到有多条花粉管进入胚囊和多精入极核现象。原胚期有附加花粉管从珠孔进入。     

Transformation and allelic replacement in Francisella spp.

We describe methods for transposon mutagenesis and allelic replacement in the facultative intracellular pathogen Francisella. Recombinant clones were constructed by insertion of partially cut F. tularensis or F. novicida DNA into pUC19 and then mutagenized with a mini-Tn10-Km transposon. F. novicida could be transformed with these plasmids either by a chemical transformation method or by electroporation, whereas F. tularensis could be transformed only by electroporation. Transformation of F. tularensis by electroporation was enhanced in the absence of the capsule. Southern blot analysis showed that the KmR marker was rescued either by integration of the plasmid into the Francisella chromosome or by allelic replacement. Allelic replacement was found to be the mechanism underlying a site-specific mutation affecting FopA, an outer-membrane protein of Francisella. F. novicida could also be transformed with chromosomal DNA carrying the KmR marker and the transformation frequency obtained using chromosomal DNA was generally greater than that obtained using plasmid DNA. F. novicida was also transformed by an IncQ plasmid containing an F. novicida DNA insert, which replicated autonomously in this host.     

Localization of a novel integrin of the beta 1 subfamily in human tissues.

We have previously described a novel integrin composed of a beta 1-chain non-covalently linked to an alpha-chain which is biochemically different from those known so far (i.e., alpha 1-alpha 7 and alpha v). This molecule has been identified with a monoclonal antibody (MAb) termed 10.1.2 raised against long-term cultured human thymic epithelial cells (TEC). In this study we analyzed the immunohistochemical distribution of this new integrin in a variety of human tissues. MAb 10.1.2 stains several types of endothelial and epithelial cells. Among the endothelia, a strong reaction was detected in the HEV of lymphoid organs including thymus, lymph node, tonsil, and mucosa-associated lymphoid tissue. Epithelial localizations of note were those in the basal layer of the epidermis and of other stratified squamous epithelia, where the lateral and apical but not the deep surfaces of most cells were stained. A variety of water-electrolyte transporting cells in sweat glands, salivary glands, and kidney were also stained at their deep surface. The latter findings suggest that this molecule may subserve other functions in addition to those related to cell adhesion.     

Triterpenoid saponins from Clinopodium polycephalum.

A new triterpenoid saponin, clinopodiside A, has been isolated from Clinopodium polycephalum. Its structure was established by spectroscopic methods and X-ray diffraction analysis as 3-O-beta-D-glucopyranosyl(1----6)-[ beta-D-glucopyranosyl (1----4)]-beta-D-glucopyranosyl-olean-11,13(18)-diene-3 beta,16 beta, 23,28-tetrol.     

Microcarrier culture of bowes melanoma cells in serum-free medium with Human plasma fraction IV-4+ V

Bowes melanoma cells were cultivated successfully in a serum-free medium which was constructed by the concept of maximum retention of proteins from fractionated human plasma having growth stimulatory activities. The cells could be cultivated in the serum-free medium without any adaptation period. The major serum-free component of the medium was the fraction IV-4 + V of the Cohn fractionation process of human plasma. Approximately six times increase of tissue-type plasminogen activator (t-PA) activity as compared with that in serum-free medium even though the cell growth was much slower. In addition, the growth stimulatory activities of thrombin and fibronectin were investigated during the cultivation of Bowes melanoma cells in this serum-free medium. These proteins contributed significantly to the enhanced growth of cells by reducing doubling time to 25 and 35 h as compared with 55 h in the serum-free medium without them. Especially, fibronectin supported cells to propagate near to the maximum cell density achieved in the medium with 10% FBS.     

Diurnal changes in psychophysiological variables of school girls: comparison with regard to age and teacher's appreciation of learning.

Ninety-five nonresident girls of a private school volunteered for the study with the teachers' help as well as parental consent. Ages were approximately 8, 9, and 10 years. They were synchronized with diurnal activity from 0730 to 2100 h and nocturnal rest. Fatigue, drowsiness, and attention were self-rated using visual analogue scales; oral temperature was self-measured and a letter cancellation test was performed. Each of these variables was measured at school at 0900, 1100, 1400, and 1600 h on Mondays, Thursdays, Fridays, and Saturdays for two consecutive weeks in 1987 (March 30-April 11) and again in 1989 (March 13-25) when the youngest group had become 10 years old. According to conventional teacher evaluation of learning (learning performance) within each group, three subgroups were formed: top third, middle third, and bottom third. Time series (more than 50,000 data) were analyzed according to several statistical methods, but mainly chronograms with ANOVA. Similar diurnal changes in oral temperature were validated for each group and subgroups. The occurrence of a diurnal change in self-rated variables (fatigue and drowsiness) and score in letter cancellation was age related: no detection in the 8-year-old group (and subgroups) and validation (p less than 0.002) in 9- and 10-year-old groups (and respective subgroups). A good learning performance was associated with a reduced drowsiness in school girls of 9 and 10 years. Age-related, time-of-day differences in drowsiness (when detected) as well as learning performance effect were not associated with observed duration of sleep. Validated changes in self-rated fatigue were close to that of drowsiness. At 0900 h, girls of 9 and 10 years were more tired when belonging to the bottom third than top third subgroup. Whatever the time of day, self-rated attention was greater in the top than in the bottom third for these girls. Differences related to learning performance were validated in each grade. However, best scores were recorded for the bottom third in the 8-year-old group, while best scores were provided by top third subgroups in 10-year-old girls. It seems that in girls around 8 years of age, critical changes can be detected with regard to the (ontogenic?) occurrence of time-of-day differences in a set of psychophysiologic variables as well as influential effects of learning performance on the same variables. Reported finding are compatible with the hypothesis of circadian oscillators working at the level of the cortex of the human brain.     

Genetic Polymorphisms of Pneumocystis Jirovecii in HIV-Positive and HIV-Negative Patients in Northern China

Pneumocystis jirovecii is an opportunistic fungus that can cause severe and potentially fatal Pneumocystis pneumonia (PCP) in immunodeficient patients. In this study, we investigated the genetic polymorphisms of P. jirovecii at eight different loci, including six nuclear genes (ITS, 26S rRNA, sod, dhps, dhfr and β-Tub) and two mitochondrial genes (mtLSU-rRNA and cyb) in three PCP cases, including two patients with HIV infection and one without HIV infection in Shanxi Province, P.R. China. The gene targets were amplified by PCR followed by sequencing of plasmid clones. The HIV-negative patient showed a coinfection with two genotypes of P. jirovecii at six of the eight loci sequenced. Of the two HIV-positive patients, one showed a coinfection with two genotypes of P. jirovecii at the same two of the six loci as in the HIV-negative patient, while the other showed a single infection at all eight loci sequenced. None of the three drug target genes (dhfr, dhps and cyb) showed mutations known to be potentially associated with drug resistance. This is the first report of genetic polymorphisms of P. jirovecii in PCP patients in Shanxi Province, China. Our findings expand our understanding of the genetic diversity of P. jirovecii in China. Open in a separate window