腺苷在低氧适应家兔脑血流调节中的作用

本研究观察了腺苷在低氧适应家兔脑血流(CBF)调节中的作用。结果表明:缺氧时适应组CBF改变不明显,对照组CBF明显增加;缺氧时适应组脑腺苷的含量明显低于对照组,而脑腺苷酸的含量明显高于对照组;适应组脑微血管对腺苷的反应与对照组相近。提示缺氧时低氧适应家兔CBF改变不明显,同低氧适应后脑腺苷含量较低、腺苷酸含量较高有关。     

Bone morphogenetic protein-4

Bone morphogenetic protein-4 (BMP-4) is one of nine structurally related BMPs belonging to the transforming growth factor-β (TGF-β) superfamily of secreted proteins. Mature BMP-4 is a dimer that binds to a multimeric transmembrane receptor with serine/threonine kinase activity. Although discovered because it stimulates bone formation in adult mammals, BMP-4 has important roles as a signalling molecule in embryonic tissues, including the developing central and peripheral nervous system, musculature and skeleton. It participates in an ancient signalling pathway also found in insects and worms. Nevertheless, the main practical application of BMPs is for stimulating repair of bone, and their use in humans is currently being assessed.     

MAGGY,a retrotransposon in the genome of the rice blast fungusMagnaporthe grisea

Full-length copies of a previously described repetitive DNA sequence (CH2-8) were isolated from the genome of theMagnaporthe grisea strain 2539. One copy of the complete element was sequenced and found to resemble agypsy-like LTR retrotransposon. We named this element MAGGY (MAGnaporthe GYpsy-like element). MAGGY contains two internal ORFs putatively encoding Gag, Pol and Env-like proteins which are similar to peptides encoded by retroelements identified in other filamentous fungi. MAGGY was found to be widely distributed amongM. grisea isolates from geographically dispersed locations and different hosts. It was present in high copy number in the genomes of all nine rice-pathogenic isolates examined. By contrast,M. grisea strains isolated from other Gramineae were found to possess varying copy numbers of MAGGY and in some cases the element was completely absent. The wide distribution of MAGGY suggests that this element invaded the genome ofM. grisea prior to the evolution of rice-specific form(s). It may since have been horizontally transmitted to other sub-specific groups. One copy of MAGGY, corresponding to the element we sequenced, was located at identical locations in the genomes of geographically dispersed strains, suggesting that this copy of the element is a relatively ancient insertion.     

利用强启动功能片段提高麦迪霉素4”，-羟基丙酰化酶基因的表达

利用PCR技术将本室克隆到的强启动功能片段取代麦迪霉素丙酰化酶基因(mpt)的启动子或与mpt基因自身启动子串连,获得含mPt重组质粒pCHFPE3和pCHFPE2。用含有这两个质粒的Streptomyces lividans TK24对螺旋霉素进行微生物转化,结果表明,与含有原启动子的mpt.S.lividans TK24(p.WFPE)相比,丙酰螺旋霉素的组分比例分别提高了89.02％和58.53％。含重组质粒pCHFPE2的螺旋霉素产生菌S.spiramyceticus发酵产物中丙酰螺旋霉素的组分也有较大辐度的提高。说明利用该强启动功能片段可以提高麦迪霉素丙酰化酶基因的表达。     

Detection of truncated virus particles in a persistent RNA virus infection in vivo.

Infectious hematopoietic necrosis virus (IHNV) is a rhabdovirus which causes devastating epizootics of trout and salmon fry in hatcheries around the world. In laboratory and field studies, epizootic survivors are negative for infectious virus by plaque assay at about 50 days postexposure. Survivors are considered virus free with no sequelae and, thus, are subsequently released into the wild. When adults return to spawn, infectious virus can again be isolated. Two hypotheses have been proposed to account for the source of virus in these adults. One hypothesis contends that virus in the epizootic survivors is cleared and that the adults are reinfected with IHNV from a secondary source during their migration upstream. The second hypothesis contends that IHNV persists in a subclinical or latent form and the virus is reactivated during the stress of spawning. Numerous studies have been carried out to test these hypotheses and, after 20 years, questions still remain regarding the maintenance of IHNV in salmonid fish populations. In the study reported here, IHNV-specific lesions in the hematopoietic tissues of rainbow trout survivors, reared in specific-pathogen-free water, were detected 1 year after the epizootic. The fish did not produce infectious virus. The presence of viral protein detected by immunohistochemistry, in viral RNA by PCR amplification, and in IHNV-truncated particles by immunogold electron microscopy confirmed the presence of IHNV in the survivors and provided the first evidence for subclinical persistence of virus in the tissues of IHNV survivors.     

Systematics of white-toothed shrews (Crocidura) (Mammalia: Insectivora: Soricidae) of Taiwan: Karyological and morphological Studies

We define the species boundaries of white-toothed shrews (genus Crocidura ) in Taiwan using karyological and morphological characteristics. Ninety-nine animals were obtained from all over Taiwan at capture rates usually less than 10%. Three species are recognized by distinct cytotypes: Crocidura attenuata tanakae 2n = 40, FN = 56; Crocidura suaveolens hosletti 2n = 40, FN = 50; Crocidura kurodai 2n = 40, FN = 54. A suite of six morphological characters diagnose the three species: shape of skull, position of incisive foramina, shape of fourth upper premolar, shape of pinna, tail vibrissae, and foot pads. A species key and notes on the life history of each species are provided. Finally, we discuss chromosomal evolution and biolgeography of Crocidura in East and South East Asia.     

Cloning of the rainbow trout (Oncorhynchus mykiss) Mx2 and Mx3 cDNAs and characterization of trout Mx protein expression in salmon cells.

Two rainbow trout (Oncorhynchus mykiss) Mx cDNAs were cloned by using RACE (rapid amplification of cDNA ends) PCR and were designated RBTMx2 and RBTMx3. The deduced RBTMx2 and RBTMx3 proteins were 636 and 623 amino acids in length with molecular masses of 72 and 70.8 kDa, respectively. These proteins, along with the previously described RBTMx1 protein (G. D. Trobridge and J. A. Leong, J. Interferon Cytokine Res. 15:691-702, 1995), have between 88.7 and 96.6% identity at the amino acid level. All three proteins contain the tripartite GTP binding domain and leucine zipper motif common to Mx proteins. A monospecific polyclonal antiserum to an Escherichia coli-expressed fragment of RBTMx3 was generated, and that reagent was found to react with all three rainbow trout Mx proteins. Subsequently, endogenous Mx production in RTG-2 cells induced with poly(IC) double-stranded RNA was detected by immunoblot analysis. The cellular localization of the rainbow trout proteins was determined by transient expression of the RBTMx cDNAs in CHSE-214 (chinook salmon embryo) cells. A single-cell transient-transfection assay was used to examine the ability of each Mx cDNA clone to inhibit replication of the fish rhabdovirus infectious hematopoietic necrosis virus (IHNV). No significant inhibition in the accumulation of the IHNV nucleoprotein was observed in cells expressing either trout Mx1, Mx2, or Mx3 in transiently transfected cells.     

A portable DNA sequence carrying the cohesive site (cos) of bacteriophage lambda and the mob (mobilization) region of the broad-host-range plasmid RK2: a module for the construction of new cosmids

A polylinker DNA sequence carrying the cos site of bacteriophage lambda and the mob (oriT) region of the IncP group plasmid RK2 was constructed. This composite polylinker has EcoRI sites at both termini and also unique sites for ClaI, HindIII, PstI and XbaI. The cos-mob region is portable with the use of EcoRI or a combination of EcoRI with ClaI, HindIII or XbaI. Another cos-mob cassette was also constructed from which the cos-mob region can be lifted with HindIII, ClaI or either of these enzymes in combination with others. These cos-mob cassettes can be used in constructing new cosmids that can be mobilized into a variety of Gram-negative bacteria. Using one of these cassettes we have constructed a small IncW group cosmid (11.1 kb) that was mobilizable into Escherichia coli, Rhizobium spp. and Alcaligenes eutrophus at high frequency.     

Pathogenesis of experimental allergic orchitis. III. T lymphocyte requirement in local adoptive transfer by peritoneal exudate cells.

In experimental allergic orchitis (EAO), a lesion characterized by mononuclear invasion of seminiferous tubules can be adoptively transferred within 1 to 4 days by testicular injection of peritoneal exudate cells (PEC) from syngeneic strain 13 guinea pigs (GP) immunized with homologous testicular antigens in complete Freund's adjuvant (CFA). This study examined the role of T lymphocytes, macrophages, and polymorphonuclear neutrophils (PMN) in the adoptive transfer. Guinea pig PEC contained 7% T lymphocytes, rare B lymphocytes, and over 90% of macrophages and PMN. After T lymphocytes were depleted by rabbit erythrocyte (E) rosette and Hypaque-Ficoll gradient centrifugation, cell preparations that contained 73% of original macrophages and 15% original T lymphocytes were obtained, and these cells did not transfer EAO (0 of 18 testes). In contrast, cell preparations enriched in T lymphocytes by nylon wool column or E rosette contained 1.5% of the original macrophages and 59% of the original T lymphocytes transferred EAO to 70% of the testes, starting at 1.5 x 10(6) T lymphocytes per testis. The number of T lymphocytes correlated with the incidence of adoptive transfer; the correlation existed regardless of the number of macrophages or PMN present. Finally, EAO was adoptively transferred to recipients that had total-body irradiation. The results indicate that (a) T lymphocytes are capable of transferring lesions of EAO, (b) in the transfer, the T lymphocytes did not function as helper T cells, since the transfer need not involve participation of host lymphoid cells, and (c) by inference, testis antigen-reactive T lymphocytes exist.     

Evidence from studies with acifluorfen for participation of a flavin-cytochrome complex in blue light photoreception for phototropism of oat coleoptiles

The diphenyl ether acifluorfen enhances the blue light-induced absorbance change in Triton X100-solubilized crude membrane preparations from etiolated oat (Avena sativa L. cv. Lodi) coleoptiles. Enhancement of the spectral change is correlated with a change in rate of dark reoxidation of a b-type cytochrome. Similar, although smaller, enhancement was obtained with oxyfluorfen, nitrofen, and bifenox. Light-minus-dark difference spectra in the presence and absence of acifluorfen, and the dithionite-reduced-minus oxidized difference spectrum indicate that acifluorfen is acting specifically at a blue light-sensitive cytochrome-flavin complex. Sodium azide, a flavin inhibitor, decreases the light-induced absorbance change significantly, but does not affect the dark reoxidation of the cytochrome. Hence, it is acting on the light reaction, suggesting that the photoreceptor itself is a flavin. Acifluorfen sensitizes phototropism in dark-grown oat seedlings such that the first positive response occurs with blue light fluences as little as one-third of those required to elicit the same response in seedlings grown in the absence of the herbicide. Both this increase in sensitivity to light and the enhancement of the light-induced cytochrome reduction vary with the applied acifluorfen concentration in a similar manner. The herbicide is without effect either on elongation or on the geotropic response of dark-grown oat seedlings, indicating that acifluorfen is acting specifically close to, or at the photoreceptor end of, the stimulus-response chain. It seems likely that the flavin-cytochrome complex serves to transduce the light signal into curvature in phototropism in oats, with the flavin moiety itself serving as the photoreceptor.