Extracellular matrix (mesoglea) of Hydra vulgaris. II. Influence of collagen and proteoglycan components on head regeneration.

Hydra are characterized by having their body wall organized as an epithelial bilayer with an intervening acellular layer termed the mesoglea. As an extension of the previous study which indicated that mesoglea is a primitive basement membrane which has retained some characteristics of interstitial extracellular matrix, the present study was undertaken to analyze the role of mesoglea components during head regeneration in Hydra vulgaris. Studies were conducted that utilized drugs that affect collagen processing or secondary collagen structure (beta-aminoproprionitrile; 2,2'-dipydridyl; and cis-4-hydroxy-L-proline) and a drug that inhibits addition of glycosaminoglycan chains to proteoglycan core proteins (p-nitrophenyl-beta-D-xylopyranoside). These studies indicated that alterations in the structure of collagens or proteoglycans caused blockage of head regeneration in Hydra as monitored over a 48-hr period. Blockage of head regeneration was reversible once the drugs were removed, indicating that the drugs were not having a general toxic effect on the organism. Radiotracer studies also indicated that blockage of head regeneration was not simply due to a general depression of protein synthesis by the drugs. Various controls indicated that each drug was affecting mesoglea components under the conditions utilized in these studies. These observations indicate that preservation of normal mesoglea structure is required for Hydra head regeneration to proceed.     

Trigonal crystals of porin from Escherichia coli

Trigonal crystals of the integral membrane protein porin from Escherichia coli have been grown and characterized. They belong to space group P321 with unit cell constants a = b = LL8.4, c = 52.7 A, alpha = beta = 90 degrees, gamma = 120 degrees. The crystals grow as well-defined hexagonal prisms to a size of 0.25 mm in all dimensions, and diffract to 2.7 A. The molecular symmetry coincides with 3-fold crystallographic symmetry, giving two trimers per unit cell (1 monomer/asymmetric unit). This corresponds to VM = 2.9 A3/Da. Native X-ray data to 3.0 A resolution have been collected on a FAST area detector and a search for heavy atom derivatives is underway.     

与胎儿珠蛋白基因持续表达有关的(A_γδβ)°—地贫纯合子及杂合子的分子鉴别

我们分子鉴别了一个缺失型中国(A_γδβ)°-地贫家系。先证者为这一缺失的纯合子,具有中度贫血症状。家系的另五个成员均为这一缺失的杂合子,其胎儿血红蛋白(HbF)为16—21％,接近或达到HPFH杂合子的HbF水平,并且几乎不表现贫血症状。限制性内切酶图谱分析证明了β-珠蛋白基因簇内的DNA顺序缺失,缺失的5′端点位于Aγ基因IVSⅡ内,3′端点在β-珠蛋白基因下游区远端,距HPFH-2的3′缺失端点上游区约11kb。缺失的总长度约为80kb。本文讨论了这一缺失导致胎儿血红蛋白在成人中持续活跃表达的可能机制。     

基因定点诱变删除及天然α型心钠素的分泌型表达

用基因定点诱变技术,删除了pO_1α ANF表达质粒中的33对碱基,使人α型心钠素结构基因直接与大肠杆菌分泌型表达质粒pIN-Ⅲ-OmPA中的信号肽酶切位点编码区相连,构成天然人α型心钠素的表达质粒pANF,在IPTG诱导下表达28肽的天然人α型心钠素。纯化后的表达产物具有天然心钠素的放免活性和很强的舒张血管的生物活性。     

板栗干腐病的防治研究之五

研究证明,花期防治以及及时采收、低温贮藏和快速运输等保水措施是控制板栗干腐病的较为有效的措施。     

Investigation of reduced serum and serum-free media for the cultivation of insect cells (Bm5) and the production of baculovirus (BmNPV)

An experimental study has been carried out to investigate the effectivenes of several reduced serum and serum-free media for the cultivation of an ovarian cell line, Bm5, of the lepidopteran insect Bombyx mori. Bm5 cell were successfully adapted to grow in a medium containing 5% serum and a serum-free medium (EX-CELL 400). On the other hand, this cell line could not be adapted to grow in several other media suggested in the literature, including IPL-41 + 2% fetal bovine serum (FBS), SF-900, and a serum-free medium (ISFM). Furthermore, a comparative study was conducted to determine the production levels of B. mori nuclear polyhedrosis virus (BmNPV) in Bm5 cells cultured in three different medium formulations. The production levels of BmNPV in adapted Bm5 cells grown in a 5% serum-supplemented medium and a serum-free medium (EX-CELL 400) were comparable to those obtained in Bm5 cells grown 10% serum-supplemented medium. (c) 1992 John Wiley & Sons, Inc.     

Improvement of Longevity and Viability of Sperm Cells Isolated from Pollen of Zea mays L

Our previous studies showed that the common maize (Zea mays L.) sperm isolation medium (Brewbaker and Kwack salts in 0.44 m sucrose without buffering) caused cell lysis in vitro. In an attempt to remedy this situation, 6 sugars, 10 buffers, 5 pH values, and 3 membrane protective agents were screened to improve longevity and viability of isolated Zea mays sperm cells as estimated by hemacytometry and flow cytometry. Use of 0.55 m galactose in the isolation solution increased sperm yield by 2.5-fold compared with sucrose, and suspension of isolated sperm cells in the galactose solution gave the best longevity among the six sugars. Buffering the galactose solution with 2 mm 2-(N-morpholino)ethanesulfonic acid significantly improved longevity, whereas other buffers had no effect or decreased the longevity and/or viability. Among the five pH values tested (5.0, 6.0, 6.7, 7.0, and 8.0), pH 6.7 appeared to be optimal for maintenance of both longevity and viability. Screening of membrane protectants showed that cysteine caused a rapid decrease in cell viability and increased lysis, whereas dithiothreitol increased the cell numbers but lowered their viability. Addition of 0.1% bovine serum albumin increased cell numbers and viability, and about 70% of the cells remained viable after 72 h of suspension. Cell longevity and viability were also improved in 0.44 m sucrose when the solution was conditioned with 2-(N-morpholino)ethanesulfonic acid and bovine serum albumin. Use of 2-(N-morpholino)ethanesulfonic acid and bovine serum albumin inthe isolation and suspension medium significantly improved the viability and longevity of sperm cells isolated from Zea mays pollen.     

Distribution and behaviour of Acetes sibogae Hansen (Decapoda, Crustacea) in an estuary in relation to tidal and diel environmental changes

Quantitative samples of Acetes sibogae were collected at 2 hintervals for 48 h at three sites across the axis of a tidalestuary to examine their distribution within the water bodyover tidal and diel cycles, and to assess the role of behaviourin maintaining population distribution in estuarine/coastalwaters in relation to selected environmental factors. Watertemperature, salinity, tidal height and light intensity wereconcurrently measured. Distribution of the shrimp across theestuary was uniform and consistent between daylight or darkperiods, and among flood or ebb tides. Changes of A.sibogaeabundance were related to light and tidal cycles at each sitewith higher catches in dark periods and during flood tides.Acetes sibogae also exhibited both nocturnal and tidal verticalmovements in the water body, with greater numbers being onlyfound near-surface rather than near-bottom during flood tidesand at night. No significant differences in the distributionof size groups were found between any sampled levels of anysite. Acetes sibogae was highly aggregated in the water body.It is suggested that aggregating behaviour and tidal and nocturnalvertical movements act to facilitate population maintenancein estuarine/coastal waters.