The fate of spargana inoculated into the cat brain and sequential changes of anti-sparganum IgG antibody levels in the cerebrospinal fluid

To establish an animal model of intracranial sparganosis, the fate and behavior of the experimentally inoculated spargana were observed. A total of 102 scolices of spargana were injected into 22 cat brains, and the cats were sacrificed at 2 weeks, 1 month, 3 months and 6 months after the inoculation. Neurosparganosis was established in 77% of the cats. Of 43 recovered worms, 19 (44%) were located in the subdural or subarachnoid space, 16 (37%) in the brain parenchyme, and 2 (5%) in the lateral ventricle. One was detected at the diploic space of the skull and 5 were outside the cranial cavity. All but one were alive, and had grown tails. They were distributed in the brain parenchyme randomly. There was no place which they could not invade. No adult was found in the intestine. Cerebrospinal fluid (CSF) was collected before inoculation, 1 week, 2 weeks, 1 month, 3 months and 6 months after inoculation. The level of anti-sparganum IgG antibody in CSF measured by ELISA began to increase above the criteria of positivity 1 month after inoculation. Three months after inoculation, the values markedly increased. The present findings reveal that intracranial inoculation of spargana into the brains of cats would be a good animal model of experimental neurosparganosis.     

The changes of histopathology and serum anti-sparganum IgG in experimental sparganosis of mice

The present study is intended to observe the chronologic changes of experimental sparganosis by histopathological observation and detection of circulating anti-sparganum IgG antibody using ELISA. Each of 25 mice was infected with five spargana, and they were examined after 1, 2, 4, 10 weeks or 6 months from infection. The followings are summarized results. 1. The plerocercoids were detected in the subcutaneous tissue of the trunk, neck or axilla, but a few often extended into the skeletal muscle. The recovery rates were 72% at the first week, 80% at the second week, 95% at the fourth week, 92% at the tenth week and 100% at the sixth month. The larvae grew slowly in both length and weight until 6 months. 2. Histopathologically, most of the larvae were observed alive in the soft tissue or skeletal muscle. Numerous eosinophils, neutrophils, lymphocytes and plasma cells were infiltrated focally around the worms by the second week, but they surrounded the worms to form a layer of inflammatory reaction after 4 weeks of infection. Also histiocytes and fibroblasts began to appear around the inflammatory cells at 4 weeks. After 10 weeks, the worms encircled by a thin fibrous layer were found. After 6 months, the worms were surrounded by either fibrous tissue or active inflammatory cells. The inflammation looked more severe in the tracks left by the worms, rather than around the worms. 3. The level of anti-sparganum IgG antibody in the serum showed an increase by the fourth week, and a rapid and continuous increase was observed thereafter by the tenth week after infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of gamma irradiation on the survival and development of Clonorchis sinensis metacercariae

The effects of gamma irradiation on the survival and development of C. sinensis metacercariae were studied to evaluate the feasibility of irradiation as a control measure for clonorchiasis. Pseudorasbora parva were collected at an endemic river of clonorchiasis and were used for irradiation of the fluke in three schemes. The first (Scheme 1) was irradiation of the isolated metacercariae from the fish followed by infection to experimental rats. The second (Scheme 2) was irradiation of the fish, and then the metacercariae were isolated and infected to rats. The third (Scheme 3) was irradiation on the rat livers after infection with normal metacercariae. Irradiation doses varied from 5 to 100 Gy for Schemes 1 and 2, and 10 to 25 Gy for Scheme 3. The rats were sacrificed 2 to 6 weeks after infection. In Scheme 1, the metacercariae irradiated at 50 Gy failed to survive in the rats after 2 or 6 weeks. However, 1 to 44% of the metacercariae irradiated at 5-30 Gy survived. The estimated LD50 of Scheme 1 was 16.5 Gy. The flukes irradiated in Scheme 2 survived better than those in Scheme 1. The average worm recovery rate in 50 Gy was 28%(7-39% individually). Increasing the dose up to 100 Gy brought a remarkably low survival rate of an average 1%(0-3% individually). The LD50 of Scheme 2 was 47.5 Gy. Worm recovery rates in the 10 Gy group of Scheme 3 were 21-39%, and those in the 25 Gy group were 2% and 34%. Although the metacercariae were irradiated, all of the recovered worms were morphologically normal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distamycin-induced inhibition of formation of a nucleoprotein complex between the terminase small subunit G1P and the non-encapsidated end (pacL site) of Bacillus subtilis bacteriophage SPP1.

The small subunit of the Bacillus subtilis bacteriophage SPP1 terminase (G1P) forms a sequence-specific nucleoprotein complex with the SPP1 non-encapsidated end (pacL site) during initiation of DNA encapsidation. Gel mobility shift assay was used to study the G1P-pacL interaction. Distamycin, a minor groove binder that induces local distortion of the DNA, inhibits G1P-pacL complex formation. The competition of G1P with distamycin for DNA binding at the pacL site is independent of the order of addition of the reactants. Other minor groove binders, such as spermine or Hoechst 33258, which do not distort DNA, failed to compete with G1P for pacL DNA binding. Cationic metals, which generate a repertoire of DNA structures different from that caused by the minor groove binders, can partially reverse the distamycin-induced inhibition of G1P binding to pacL DNA. The major groove binder methyl green, which does not distort sequence-directed bending of pacL DNA, competes with G1P for binding at the pacL site. Our data suggest that the natural sequence-directed bend that exists within the pacL site is the architectural element that facilitates assembly of a nucleoprotein complex and hence initiation of DNA encapsidation by bacteriophage SPP1.     

促葡萄糖转运蛋白基因家族的分子进化研究

葡萄糖转运蛋白是一个在结构上相似功能上不同的多基因家族（ＧＬＵＴ１－ＧＬＵＴ５）。由于这一组蛋白和体内的葡萄糖利用有关,因此被认为是糖尿病胰岛素抵抗（抗性）的一个候选基因。本文比较了不同种生物这一基因家族的氨基酸和核苷酸顺序;推测了亲水性和疏水性分布;计算了蛋白质和核苷酸的进化距离,并在此基础上构建了分子进化树。研究表明：这一基因家族具有高度的同源性、极为相似的亲水性和疏水性分布以及结构的对称性。提示这一基因家族起源于一个共同的祖先并可能通过基因的重复而形成。这一进化机制可能有利于氨基酸结构的稳定及抵抗突变的作用。由于邻元法构建的进化树其分支长度存在差异,提示在这一基因家族的进化过程中,各分支上的进化速率并不相同。蛋白质进化距离和核苷酸进化距离所构建进化树的差异提示了在基因组中可能存在隐匿替换。两种方法构建的进化树都提示了ＧＬＵＴ１、３、４在结构和功能上要更为保守。     

Epstein─Barr病毒膜抗原在中国仓鼠卵巢（CHO）细胞中的表达

将切去３’端穿膜序列的ＥＢ病毒膜抗原（ＭＡ）基因,插入ｐＳＶ２－ｄｈｆｒ质粒的ＳＶ４０早期启动子下游,构建了真核表达载体ｐＳＶ２－ｄｈｆｒＧＰＴＲ,使两个ＳＶ４０早期启动子分别调控ＭＡ和二氢叶酸还原酶（ｄｈｆｒ）基因。将该重组质粒转化ＣＨＯ－ｄｈｆｒ细胞,在选择培养基中筛选阳性克隆,用氨甲喋呤加压扩增,建立了表达ＥＢＶ－ＭＡ的克隆细胞系。ｗｅｓｔｅｒｎｂｌｏｔ分析证明,所表达的蛋白的分子量大约为３４０ｋｄ和２２０ｋｄ。经过细Ｓｅｐｈａｒｏｓｅ２Ｂ琼脂糖凝胶层析初步纯化的抗原与福氏佐剂混合免疫小鼠,２周后小鼠血清中出现明显的ｇｐ３４０／２２０特异性抗体,表明切去嵌膜区结构的ＥＢＶ－ＭＡ基因在ＣＨＯ细胞中的表达产物具有同天然膜抗原相似的分子量大小、糖基化程度、免疫特异性和免疫原性,可望成为ＥＢ病毒人用基因工程亚单位疫苗。     

屎克螂适宜的繁殖条件初步研究

１９９１—１９９４年对屎克螂适宜的繁殖条件研究结果：１．土层４０ｃｍ和６０ｃｍ的平均温度分别为１５．９２±６．３４℃和１５．８９±６．０８℃;平均土壤含水量分别为２６．７０±３．７４％和２３．７２±１．８８％,使各虫态处于一个几乎恒温恒湿的条件,有利于生长发育与越冬,２．土壤含水量１７％、２０％、２２％、２６％和２９％,其产卵最多的深度分别在６５─７０ｃｍ,７５─８０ｃｍ,６５─８０ｃｍ,６５—８０ｃｍ和３５—５０ｃｍ,分别占产卵总数的３４．１６％、４２．４２％、６８．４２％、５５．４０％和９０．５６％。３．不同土壤的产卵深度,沙壤土以土下４５—５０ｃｍ处最多,占产卵总数的３４．７８％;沙土以６５—８５ｃｍ最多,占产卵总数的８６．６７％;粘土以４５—６０ｃｍ最多,占产卵总数的５１．１１％。     

红旗泡水生植物群落结构与功能的研究

红旗泡是松嫩平原上的水草型湖泊,１９７２年由引嫩干渠补入嫩江水,使其成为大庆市主要水源地和渔业基地。该湖水生植被分布面积大,覆盖近１／２的水面。本文分析了芦苇,狭叶香蒲和稗等单优群落的结构与分布,并统计了混合群落的数量特征。随着油田开发,大庆地区的水体均受到不同程度的污染;因红旗泡水生植物资源丰富且其具清除油污、吸附重金属和沉降悬浮物等净化功能,故使其成为大庆地区水质最好和鱼产量最高的湖泊。     

Reduction in omega-3 fatty acids by UV-B irradiation in microalgae

UV-B irradiation reduced the levels of omega-3 fatty acid, eicosapentaenoic acid (EPA, 20:53) and docosahexaenoic acid (DHA, 22:63), in microalgae; the degree of reduction varied with species.Chaetoceros calcitrans andSkeletonema costatum were high UV-B tolerant species, followed byPhaeodactylum tricornutum, Chroomonas salina, Pavlova lutheri, andThalassiosira pseudonana.Isochrysis galbana (T.ISO) andProrocentrum micans were UV- B sensitive. Cells in logarithmic phase were most sensitive to UV- B irradiation. Nitrate-, phosphate-, or sulphate-starved cells were more UV-B sensitive than non-starved cells grown in a complete basal medium. A relatively short exposure to high UV-B was more damaging than a longer exposure to lower irradiance. Visible light intensity levels had a profound impact on the sensitivity of microalgal cultures to UV-B, with high levels decreasing UV-B dependent damage. Addition of polyamines (putrescine, spermidine or spermine) or an amino acid (cysteine) to the culture medium minimized the reduction of omega-3 fatty acid content in microalgae caused by UV-B irradiation.Author for correspondence     

Characterization of the effectors required for stable inheritance of Streptococcus pyogenes pSM19035-derived plasmids in Bacillus subtilis

The low-copy-number and broad-host-range pSM19035-derived plasmid pBT233 is stably inherited in Bacillus subtilis cells. Two distinct regions, segA and segB, enhance the segregational stability of the plasmid. Both regions function in a replicon-independent manner. The maximization of random plasmid segregation is accomplished by the recombination proficiency of the host or the presence of the pBT233 segA region. The segA region contains two open reading frames (or) [ and ]. Inactivation or deletion of or results in SegA^– plasmids. Better than random segregation requires an active segB region. The segB region contains two ors (or and or). Inactivation of either of the orfs does not lead to an increase in cell death, but or^– plasmids are randomly segregated. These results suggest that pBT233 stabilization relies on a complex system involving resolution of plasmid oligomers (segA) and on the function(s) encoded by the segB region.