Amplification, analysis and chromosome mapping of novel homeobox-containing and homeobox-flanking sequences in rice

Homeobox genes, widely distributed among animal and plant kingdoms, play an important role in developmental process. Several homeobox conserved fragments were amplified by PCR and the flanking regions were also obtained by an LM-PCR procedure. Sequencing and Southern analysis showed that they belong to a homeobox gene family of rice. Six homeobox-containing fragments were mapped on the molecular linkage map of rice. They were located on chromosomes 3, 4 and 7 respectively. It is noteworthy that there are 4 homeobox fragments located on rice chromosome 3 and the result is also consistent with the comparative genomics between rice and maize.

Human recombinant single-chain antibody fragments, specific for the hypervariable region 1 of hepatitis C virus, from immune phage-display libraries

The hypervariable region 1 (HVR1) of hepatitis C virus (HCV) may contain a potential neutralization site and the generation of human single-chain antibody fragments (scFv) to HVR1 may therefore provide a useful tool for the study of HCV. In this report, we have isolated and characterized three anti-HVR1 scFv clones from two patient-derived phage-displayed libraries and HCV HVR1 peptides. scFv S52/20 and S53/6 were selected with serologically cross-reactive HVR1 peptides. scFv p3f10 was obtained by screening the library from patient MH with an autologous HVR1 peptide. Nucleotide sequencing showed that the VH chains and Vkappa chains of all three scFv antibodies were derived from VH3 and Vkappa1 family germline V-genes, respectively. The specificity and affinity of the recombinant scFv antibodies were examined by enzyme-linked immunosorbent assay (ELISA) and an affinity biosensor, using HVR1 peptides. S52/20 scFv binding to S52 HVR1 peptide was blocked by preincubation with soluble peptide S52 and was partially competed by one of three HCV-infected patient sera. In addition, scFv S52/20 blocked the binding of HCV-susceptible Molt-4 cells to immobilized S52 peptide. This study demonstrates that recombinant human scFv antibodies to HCV HVR1 can be produced in vitro and directly confirms that HVR1 of HCV elicits highly specific antibodies. The very high specificity of these antibodies to HVR1 may limit their potential use in passive immunization therapy against HCV, and further engineering of the scFvs needs to be performed to generate broad-spectrum blocking scFvs.

Experimental study on pathogenicity of precore mutants in Hepadnaviridae

OBJECTIVE

To study the replicative competency and pathogenicity of precore gene mutants of duck hepatitis B virus (DHBV) in the duck model.

METHODS

Three site-directed point mutations in the precore region of cloned DHBV were constructed. Head-to-tail dimers were formed. The three plasmids were named: pEDM1-2 (initiation codon ATG mutated to TTG), pEDM2-2 (an "A" was inserted down stream of codon 12, leading to frame shift in the distal end of precore region), pEDM3-2 (codon 38 was changed from TAT to TAA, leading to a stop codon at the 3'-end). Mutants and wild-type cloned DNA dimers were first separately used to transfect LMH cells (a chicken hepatoma cell line) and viruses were collected from supernatant and used to infect 6 one-day-old ducklings per group. Serum duck hepatitis B surface antigen (DHBsAg) and DHBV DNA were assayed. Six weeks after infection, ducks were killed and liver tissues were studied for histopathological changes.

RESULTS

After transfection, pEDM1-2, pEDM2-2 and pEDM3-2 expressed similar level of DHBsAg. Replication of pEDM1-2 and pEDM3-2 was similar to that of the wild type clone, while pEDM2-2 replicated at a significantly decreased level. Infection study employing the supernatant of transfected cells was as follows: pEDM1-2 infected 5/6 ducklings, pEDM2-2 non infected, pEDM3-2 infected 2/6 ducklings, wild type virus infected 6/6 ducklings. Positive serum samples from both pEDM1-2 and pEDM3-2 were at a lower serum DHBV level compared to that of the wild type virus. Pathological changes were more significant in pEDM3-2 infected duck livers, with numerous inflammatory cells in portal tract and infiltration into parenchyma.

CONCLUSIONS

Mutations in the initiating codon or generation of a stop codon at the 3'-end of the precore region resulted in decreased replication competency of DHBV, while frame-shift mutation of the precore region, covering the epsilon encapsidation signal abolished the replication of DHBV. When the mutants replicated in hosts, more severe pathological changes were observed in ducks infected with mutant harboring a stop codon at the 3'-end. Data suggest that replicative-competent DHBV precore mutant can be more pathogenic than wild-type DHBV.

[Expression of integrin alpha 5, beta 1 subunit and fibronectin mRNAs in human hepatocellular carcinoma]

OBJECTIVE

To study the biologic significance of the expression of integrin alpha 5, beta 1 subunit and fibronectin (FN) mRNAs in hepatocellular carcinoma (HCC).

METHODS

Integrin alpha 5, beta 1 subunit and FN mRNAs were detected by using Northern blot (alpha-32P-labeled cDNA probes) and in situ hybridization (Dig-labeled cDNA probes) in 15 cases of HCC, 5 cases of paracancerous cirrhotic liver and 3 cases of normal liver tissue.

RESULTS

In well-differentiated HCC, the level of integrin alpha 5, beta 1 or FN mRNA expression was similar to those in normal liver and paracancerous cirrhotic liver tissues, but was markedly decreased, even absent in the poorly- and moderately-differentiated HCC tissues (P < 0.01, respectively). The expression of integrin alpha 5 and FN mRNAs was mainly detected in the cytoplasm of HCC cells. In all the HCC cases tested, the expression of integrin alpha 5, beta 1 and FN mRNAs was lower in 8 cases of HCC with focal invasion and/or intrahepatic metastasis than that in the others without invasion or metastasis(P < 0.05). In addition, the heterogeneous expression of FN mRNA was found in 5 cases of HCC with intrahepatic metastasis.

CONCLUSIONS

Combined with the immunohistochemical observation before, it might be deduced that the changes of integrin alpha 5 beta 1 and FN protein expression in HCC tissues are because of changing of the mRNA levels related, which might deeply influence the cell differentiation, tumor invasion and metastasis of HCC. The appearance of the heterogeneous FN mRNA and its encoded FN protein might be associated with the development of HCC metastasis.

SV40 large T antigen binds to the TBP-TAF(I) complex SL1 and coactivates ribosomal RNA transcription

SV40 large T antigen is a multifunctional regulatory protein that plays a key role in the viral life cycle and can stimulate cell proliferation. To accomplish this, large T antigen has to control the expression of cellular genes involved in cell cycle progression and cell growth. rRNA synthesis by RNA polymerase I (Pol I) is tightly associated with cell growth and proliferation, and previous studies indicated that large T antigen up-regulates RNA Pol I transcription in SV40-infected cells. How this process occurs is currently unclear. To investigate the mechanisms of large T antigen stimulation of RNA Pol I transcription, we have established an in vitro transcription system that is responsive to large T antigen. Here, we show that recombinant large T antigen stimulates Pol I transcription reconstituted with purified RNA Pol I, UBF, and the TBP/TAF complex SL1. Immunoprecipitation experiments revealed that large T antigen directly binds to SL1, in vitro, as well as in SV40-infected cells. In addition, our data indicate that this interaction occurs by direct association with three SL1 subunits, namely TBP, TAF(I)48, and TAF(I)110. Transcription studies with large T antigen deletion mutants show that the 538-amino-acid amino-terminal domain is necessary for full stimulation of Pol I transcription. Importantly, mutants that no longer bind to SL1 are also unable to stimulate Pol I transcription. This indicates that recruitment of large T antigen to the rRNA promoter by SL1 constitutes a crucial step in the activation process. Taken together with recent studies on large T antigen activation of RNA Pol II transcription, these results suggest that viral modulation of genes involved in cell proliferation involves direct targeting of promoter-specific TBP/TAF complexes (i.e., SL1 or TFIID) by large T antigen.

[Expression and detection of integrin alpha 5 beta 1, fibronectin and its fragment in patients with hepatocellular carcinoma]

OBJECTIVE

To study the relationship between the expression of integrin alpha 5 beta 1, fibronectin (FN) and its fragment (malignant disease-associated DNA-binding protein 2 MAD2) and the biologic behavior of human hepatocellular carcinoma HCC) as well as the significance of MAD2 detection in plasma.

METHODS

Integrin alpha 5 beta 1, FN and MAD2 were localized by immunohistochemical methods and quantified by image analysis in tumor and peripheral liver tissues from 40 HCC cases. The concentration of FN and MAD2 in the plasma samples from 30/40 cases were examined using the ELISA method.

RESULTS

The expression of integrin alpha 5 beta 1, FN and MAD2 in well differentiated HCC were not significantly different from that of normal tissues, while they were markedly decreased or undetectable in mode rately and poorly differentiated HCC. Decreased expression of integrin alpha 5 beta 1 and FN at sites where HCC invaded the connective tissue and enhanced expression on the HCC cells around cancerous emboli were also noted. The mean concentration of plasma MAD2 in patients with HCC were significantly increased when compared to those with chronic liver disease and normal subjects.

CONCLUSIONS

The changes in integrin alpha 5 beta 1 and FN expression may be associated with HCC differentiation, invasion and metastasis. The detection of plasma MAD2 in patients with HCC may have clinical significance.

[A study on type I, III and IV collagen production in CCl4 induced rat liver fibrosis]

OBJECTIVE

To study the dynamic changes of alpha 1 (I), alpha 1 (III) and alpha I (IV) procollagen mRNA and collagen-producing cells during CCl4 induced SD rat liver fibrogenesis (20 weeks).

METHODS

The investigations were performed using Northern blot analysis, in situ hybridization and immunohistochemical techniques.

RESULTS

The increased expression of alpha 1 (III) procollagen mRNA during fibrogenesis by Northern blot analysis was the most predominant among the three mRNAs studied. However, the increase of alpha 1 (IV) procollagen mRNA expression occurred earlier, while the expression of alpha 1 (I) mRNA did not increase until the middle stage of the experiment. Desmin positive and/or smooth muscle actin positive Ito cells and myofibroblasts (MFs) in and around the necrotic areas expressed alpha 1 (I), alpha 1 (III) and alpha 1 (IV) procollagen mRNA signals detected by in situ hybridization during the early stage of the experiment. All the three procollagen mRNAs were mostly localized in fibroblasts (Fbs) and MFs in the septa during the mid and late stages of fibrosis.

CONCLUSIONS

Fbs and MFs were considered as important Col I, Col III and Col IV producing cells in liver fibrosis. Sinusoid endothelia were involved in Col IV synthesis in the fibrotic liver.

Cloning, characterization and transient expression of the gene encoding a rice U3 small nuclear RNA

A rice U3 small nuclear RNA (snRNA)-encoding gene has been isolated. The coding region of this gene contains all five conserved sequence boxes common to plant U3 snRNAs. The upstream and downstream regions of the gene harbour characteristic sequence elements required for transcription with RNA polymerase III (pol III), as well as three monocot-specific promoter (MSP) elements [Connelly et al., Mol. Cell Biol.14 (1994) 5910-5919], two of them comprising a palindromic G+C-rich segment. The sequence (TTTAAAA) of the TATA-box in this gene does not fit the established consensus [Marshallsay et al., Plant Mol. Biol. 19(1992) 973-983], making this gene unique among reported snRNA-encoding genes of plants. An RNase protection assay showed that the gene is expressed properly in cucumber protoplasts. We thus suggest that, with other promoter elements present, the TATA-box for RNA pol III-specific snRNA-encoding genes may not be as well conserved as that for RNA pol II-specific genes.

Antagonistic properties of centrally truncated analogs of [D-Trp(32)]NPY

We have previously shown that [D-Trp(32)]NPY can competitively antagonize NPY-induced feeding in rats (Balasubramaniam et al. J. Med. Chem. 1994, 37, 811-815). This peptide, however, did not bind to SK-N-MC cells with Y-1 receptors. Since centrally truncated NPY analogs have been shown to bind Y-1 receptors, we synthesized similar analogs of [D-Trp(32)]NPY and investigated their Y-1 (SK-N-MC) and Y-2 (SK-N-BE2) receptor affinities and their properties in human erythroleukemia (HEL) cells. None of the analogs with D-Trp(32) mobilized intracellular calcium, [Ca2]i, in HEL cells. Although Des-AA(6-24)[Aoc(6)]NPY and the corresponding D-Trp(32) analog exhibited no affinity to Y-1 receptors, Des-AA(7-24)[Aoc(6),D-Trp(32)] NPY(6) exhibited weak binding. Replacing Pro(5) in 6 with D-Ala to stabilize the central chain reversal, and hence the antiparallel alignment of the N- and C-terminal regions known to be important for Y-1 binding, resulted in an analog, Des-AA(7-24)[D-Ala(5),Aoc(6),D-Trp(32)]NPY (7), which exhibited moderate antagonist potency in attenuating NPY effects on cAMP and [Ca2+]i, in SK-N-MC and HEL cells, respectively. This analog also shifted the dose-response curve of NPY on blood pressure in anesthetized rats. Deletion of only the 7-17 and/or the incorporation of N-Me-Ala(5), superior beta-turn stabilizer, in 7 did not improve the Y-1 receptor affinity. Des-AA(7-24)[D-Ala(5), Gly(6),D-Trp(32)]NPY exhibited an affinity similar to that of 7, suggesting that a long spacer arm is not necessary for efficient Y-1 receptor interaction. Locking the antiparallel alignment via a 2/26 or 2/27 lactam bridge did not improve the binding. Finally, replacement of D-Ala(5) in 7 with D-Trp dramatically increased both the binding and the antagonistic potencies. Modeling based on the avian pancreatic polypeptide X-ray structure suggested that analogs which have the N- and C-terminal regions in close proximity might exhibit good binding, and that the D-Trp(32) substitution may induce a beta-turn that could be important for exhibiting antagonism. A systematic investigation has resulted in the development of relatively potent Y-1 receptor antagonists. Further structure-activity studies with these compounds and those previously reported by us and other investigators should result in the development of long-acting and receptor selective antagonists.

Synthesis, structure, and antagonistic properties of des-Asn29[D-Trp28,32]NPY(27-36)

We have previously reported that [D-Trp32]NPY and its centrally truncated analogues such as des-AA7-24[D-Trp5,32,Aoc6]NPY can competitively antagonize NPY effects on rat hypothalamus and Y1 (SK-N-MC AND HEL) cells, respectively. In continuation of this work, we performed structure-activity studies with C-terminal decapeptide sequence keeping D-Trp at position 32 to develop lower molecular weight Y1-selective antagonists. This study led to the development of des-Asn29[D-Trp28,32]NPY(27-36), which bound to both Y1 (SK-N-MC, Ki > or = 10 microM) and Y2 (SK-N-BE2, Ki = 1.01 +/- 0.03 microM) receptors. This peptide did not exhibit any agonist activity at Y1 receptors, and exhibited comparable potencies in antagonizing the effects of NPY on the synthesis of cAMP and mobilization of [Ca2+]i in HEL cells. However, in SK-N-MC cells, it was more potent in antagonizing the mobilization of [Ca2+]i than inhibition of cAMP synthesis. Substitution of Nva for Gln34 to increase the hydrophobicity without altering the carbon skeleton substantially increased Y1 affinity (Ki = 0.33 +/- 0.15 microM) and imparted Y1 selectivity (Ki for Y2 affinity = 3.16 +/- 0.50). Moreover, this peptide exhibited good antagonistic potency in HEL cells. 2D NMR studies of des-Asn29[D-Trp28,32]NPY(27-36) revealed the existence of a fairly stable loop-like structure between residues 27 and 32 and a less stable one between residues 32 and 36. The increased Y1 affinity of des-Asn29[D-Trp28,32,Nva34]NPY(27-36) may be due to the stabilization of the 32-36 loop by Nva34. It appears therefore that stabilization of the loop structures in these peptides should result in the development of more potent Y1 receptor antagonists. Our investigations also suggest that HEL cells express a homogeneous population of NPY Y1 receptors whereas SK-N-MC cells express high- and low-affinity Y1 receptors coupled to Ca2+ and cAMP, respectively.

PCR analysis of half-seeds of cereal crops and its application in marker-assisted selection and breeding

A simple and rapid PCR method was adapted to DNA analysis of cereal seeds. Half-seeds of rice, wheat, and maize were treated with an extraction buffer and the resulting supernatants were used in PCR and RAPD reactions. PCR products amplified from the half-seed DNA extracts were identical with that from leaf tissue DNA extracts when the same specific primers were used in PCR reactions. The remaining half-seeds with embryos could still germinate normally. The half-seed PCR analysis was applied to the identification of resistant genotypes of rice bacterial blight, and it was proved effective in plant breeding and genetic studies.

[Study on cells associated with human liver fibrosis]

The cells which related to deposition of extracellular matrix (ECM) in human liver fibrogenesis were investigated with immunohistochemistry (IHC) and nucleic acid hybridization. Results showed that ECMs were high in chronic liver disease (CLD) tissues, particularly collagen III and its mRNA in active-CLD. In this group, cells positive for pre-collagen III pro-peptide (PIIIP) and collagen III mRNA were markedly increased and mostly located in the area connecting interstitium and parenchyma. These collagen producing cells were mainly the interstitial cells identified by IHC and electron microscopy as fat storing cells and associated myofibroblasts and fibroblasts. Their degree of hyperplasia was closely related to the infiltration of inflammatory cells.

The nutritional status of pre-school children in poor rural areas of China

Described are the main findings of the first large-scale nutrition monitoring project carried out over a 4-year period in China. The nutritional status of nearly 10 000 preschool children in 18 comparatively poor rural areas in seven provinces was followed each year over the period 198S89 in order to identify their major nutritional problems and improve their growth and development. Physical measurements were made and dietary surveys and biochemical tests were performed on a subsample of the children. The proportion of stunted and underweight children was far higher than the national average. Based on the possibilities offered by local circumstances, the prevalences of stunting and underweight were lowered and anemia greatly reduced. Along with the progress in nutrition monitoring, major efforts were made to train health workers, as well as to encourage increased production of green vegetables, poultry, and small livestock. The wealth of information collected and the experience gained may serve as a baseline record, the project currently being expanded to cover 100 counties throughout China.

Chromium-induced early changes in renal function among ferrochromium-producing workers

Urinary biochemical indicators of renal injury were examined in 84 male and 38 female ferrochromium-producing workers exposed to water-soluble chromium compounds [Cr(VI)]. The indicators examined included urinary chromium (U-Cr), alkaline phosphatase (ALP), gamma-glutamyl transferase (gamma-GT), glutamic-oxalacetic and glutamic-pyruvic transaminases (GOT & GPT), lactate dehydrogenase (LDH), N-acetyl-beta-D-glucosaminidase (NAG), total protein (TPr) and beta 2-microglobulin (beta 2-MG). The U-Cr levels in the exposed group were approximately 1.8 times that of the control group. Compared to controls, the activities of gamma-GT, NAG, ALP, GOT and LDH in the urine of workers were significantly increased whenever U-Cr concentration exceeded 45 microgram/g creatinine. The activities of gamma-GT, GOT and NAG were elevated in workers employed for longer than ten years. However, no clear dose-response relationships nor time-effect relationships were found. The present results suggest that long-term exposure to water-soluble chromium [Cr(VI)] produces chronic renal injury. The site of the injury appears to mainly involve the proximal tubule. U-Cr concentrations of > 15 microgram/g creatinine can be proposed as a threshold dosage for nephrotoxicity, and gamma-GT, NAG and ALP are early sensitive indicators of the most valuable for evaluating the renal injury.