我国某些常见化石硅藻的环境分析

本文详细研究了中国海表层沉积物中的常见化石硅藻,结果表明,这些种的分布范围及数量变化随环境的不同而变化。因此,根据柱状样品中这些种类数量的变化,能够推断古气候变化,恢复古地理环境,再现海平面波动历程,进而划分、对比第四系地层。     

Pregnancy diagnosis in zoo animals by estrogen determination in feces

Estrogen concentration in feces was investigated in five different herbivorous species of zoo animals. Using a nonspecific estrogen radioimmunoassay, in four species (red buffalo, yak, Grevy's zebra, and Nubian ibex) pregnancy was revealed by measuring estrogen concentration in feces. In hippopotamus, the levels of fecal estrogens were not different between pregnant and nonpregnant animals.     

Isolation of full-length putative rat lysophospholipase cDNA using improved methods for mRNA isolation and cDNA cloning

We have cloned a full-length putative rat pancreatic lysophospholipase cDNA by an improved mRNA isolation method and cDNA cloning strategy. These new methods allow the construction of a cDNA library from the adult rat pancreas in which the majority of recombinant clones contained complete sequences for the corresponding mRNAs. A previously recognized but unidentified long and relatively rare cDNA clone containing the entire sequence from the cap site at the 5' end to the poly(A) tail at the 3' end of the mRNA was isolated by single-step screening of the library. The size, amino acid composition, and the activity of the protein expressed in heterologous cells strongly suggest this mRNA codes for lysophospholipase [Van den Bosch, H., Aarsman, A. J., DeJong, G. N., & Van Deenen, L. M. (1973) Biochim. Biophys. Acta 296, 94-104].     

Ionizing-radiation-induced damage in the DNA of cultured human cells. Identification of 8,5-cyclo-2-deoxyguanosine.

Epstein-Barr-virus-transformed peripheral-blood B-lymphocytes were gamma-irradiated at 0 degree C at doses from 10 to 100 Gy. The cells were immediately lysed and the DNA was isolated. Subsequently, the DNA was hydrolysed to 2'-deoxyribonucleosides with a mixture of DNAase I, venom and spleen exonucleases and alkaline phosphatase. The hydrolysate was dried, trimethylsilylated and analysed by capillary gas chromatography-mass spectrometry with selected-ion monitoring. The (5'R)- and (5'S)-diastereomers of 8,5'-cyclo-2'-deoxyguanosine were observed in a ratio of 1:3, and their formation was dose-dependent. It was possible to detect and characterize one such lesion in approx. 4 X 10(4) guanine nucleotide subunits of DNA.     

Expression of rat transforming growth factor alpha mRNA during development occurs predominantly in the maternal decidua.

Previous studies have shown that transforming growth factor alpha is expressed during rodent development. To establish the site(s) of transforming growth factor alpha mRNA expression during rat embryogensis, we performed in situ hybridization and Northern blot analyses on samples of embryonic and maternal tissues at various gestational ages. Our results indicate that the high levels of transforming growth factor alpha mRNA that are observed during early development are the result of expression in the maternal decidua and not in the embryo. Decidual expression appears to be induced after implantation, peaks at day 8, and then slowly declines through day 15 at which time the decidua is being resorbed. Expression of transforming growth factor alpha mRNA is highest in that region of the decidua adjacent to the embryo and is low or nondetectable in the uterus, placenta, and other maternal tissues. The developmentally regulated expression of transforming growth factor alpha mRNA in the decidua, together with the presence of epidermal growth factor receptors in this tissue, suggests that transforming growth factor alpha stimulates proliferation locally through an autocrine mechanism. Since epidermal growth factor receptors are present in the embryo and placenta, transforming growth factor alpha produced in the decidua may also act on these tissues through paracrine or endocrine mechanisms.     

长滩果引种驯化研究

长滩果系罗汉果最佳品种。原产区分布于永福和临桂县交界400—600米山区,但不适应于低丘陵和平原地区,因而不能在低丘陵和平原地区推广。为了解决这个问题。采用了(1)选择湿润和半阴的生长环境;(2)采用适应性强的砧木;(3)促成栽培;(4)加强秋旱期的科学管理等措施并取得成功,试验结果表明长滩果产量和品质达到或略超过原产区水平。     

Mitotic reversion in prophase of PTK1 cells induced by argon laser microirradiation

In this paper, we report the effects of laser microirradiation of prophase nucleoli and mitotic chromosomes in cells of female rat kangaroo kidney epithelial cell line PTK1. When the laser power delivered to sample surface was 90-190 mW, irradiation of one of the two nucleoli in the prophase cell did not inhibit the mitotic progress, but resulted in the loss of the irradiated nucleolus in daughter cells. When the laser power was increased to 360-420 mW, either irradiation of the nucleolus or chromosome in midprophase caused a blockage of mitosis at terminal midprophase. The irradiated cells returned morphologically to early prophase. No mitotic reversion occurred in the case of irradiation of chromosomes at late prophase, prometaphase, metaphase, and anaphase. Irradiation of the cytoplasm in prophase cells caused a 50-70 min mitotic delay at prophase. However, the irradiated cells underwent successive mitotic divisions. The mechanism of laser-induced mitotic prophase reversion is discussed.     

Qualitative and quantitative comparison of brain proteins in Alzheimer's disease

In human brain extracts, most proteins of pathological interest in Alzheimer's disease are insoluble and their analysis is often performed on denatured and reduced samples by immunoblotting after electrophoresis on polyacrylamide gel in presence of sodium dodecyl sulfate. Because we needed to accurately compare the concentration of several proteins in brain extracts to investigate the etiology of the disease, the quantitative aspect of immunoblotting was assessed and the results compared for a soluble component with those obtained by electroimmunoassay. Glial fibrillary acidic protein (GFAP) and Tau proteins were analysed by immunoblotting in brain homogenates treated with the Laemmli sample buffer from 10 control and 25 Alzheimer's disease brains. The linearity of densitometric measures of dilutions for one given sample was demonstrated. A 8 to 16-fold GFAP increase in Alzheimer brain was established. With regard to Tau proteins it was possible to show the presence of two pathological Tau variants (Tau 64 and 69) in all the Alzheimer brain homogenates, furthermore, the amount of Tau 64 and 69 was proportional to the presence of neurofibrillary degeneration. As far as alpha 1-antichymotrypsin is concerned, we showed, in a second set of brain samples (14 control and 12 Alzheimer brains), discrepancies between the results obtained by immunoblotting and by electroimmunoassay while for a given sample linearity of immunoblotting measures of dilutions of this sample was demonstrated. Quantitation by immunoblotting of such components which can be quantified using other procedures is uncertain whereas the interest of immunoblotting is undoubted for the insoluble proteins in the brain extracts.     

Studies on the structure of NADH: ubiquinone oxidoreductase complex: topography of the subunits of the iron-sulfur protein component

Resolution of the mitochondrial NADH:ubiquinone oxidoreductase complex (Complex I) by chaotropic agents result in the separation of three building blocks of the enzyme, designated FP (flavoprotein), IP (iron-sulfur protein), and HP (hydrophobic protein). FP contains three subunits of Mr 51, 24, and 9 kDa; one FMN; and two iron-sulfur clusters. Immunochemical studies with monospecific antibodies to the FP subunits have indicated that all three subunits of FP protrude from the inner mitochondrial membrane on the matrix side, whereas no reactive epitopes from these subunits were found exposed on the cytosolic side [A.-L. Han, T. Yagi, and Y. Hatefi (1988) Arch. Biochem. Biophys. 267, 490-496]. IP contains six subunits of Mr 75, 49, 30, 18, 15, and 13 kDa and four iron-sulfur clusters. In the present study, immunochemical experiments (enzyme-linked immunosorbent assays and 125I-protein A labeling) were carried out with monospecific antibodies to the above IP subunits and with bovine Complex I, submitochondrial particles, mitoplasts, and intact mitochondria as sources of antigens. Results have indicated that all six IP subunits protrude from the inner mitochondrial membrane into the matrix, and that the 75-kDa subunit, and possibly the 15-kDa subunit, protrude in mitoplasts from the cytosolic side as well. No epitopes reactive toward the monospecific antibodies to the 49-, 30-, 18-, and 13-kDa subunits were detected in mitoplasts.     

Differential susceptibility of type III erythrocytes of paroxysmal nocturnal hemoglobinuria to lysis mediated by complement and perforin

Previous reports have suggested that a 65 kDa membrane protein, termed homologous restriction factor (HRF), in addition to protecting erythrocytes (E) against lysis by homologous complement (C), may also be involved in protecting cytolytic lymphocytes against lysis mediated by a pore-forming protein (PFP/perforin), one of their own lytic mediators. Here, we used HRF-deficient type III E of patients with paroxysmal nocturnal hemoglobinuria (PNH) to study their susceptibility to lysis mediated by homologous C and perforin, and compared it with lysis of HRF-bearing control or PNH type I E. We show that type III E of PNH patients are indeed more susceptible to lysis mediated by homologous C than control or type I E, but they are as susceptible to perforin-mediated lysis as type I E. In addition, all human E (type I or III) tested here are equally susceptible to lysis mediated by either human (homologous) or murine (heterologous) perforin. By immunoblot analysis, we confirm that type III E, in contrast to type I E, were deficient in the 65 kDa HRF. These results support the notion that homologous species restriction is seen in the C- but not in the lymphocyte perforin-system and argue against an active participation of HRF in protecting cells from perforin-mediated lysis.