The trichome-specific acetolactate synthase NtALS1 gene, is involved in acylsugar biosynthesis in tobacco (Nicotiana tabacum L.)

MAIN CONCLUSION

NtALS1 is specifically expressed in glandular trichomes, and can improve the content of acylsugars in tobacco.

ABTRACT

The glandular trichomes of many species in the Solanaceae family play an important role in plant defense. These epidermal outgrowths exhibit specialized secondary metabolism, including the production of structurally diverse acylsugars that function in defense against insects and have substantial developmental potential for commercial uses. However, our current understanding of genes involved in acyl chain biosynthesis of acylsugars remains poor in tobacco. In this study, we identified three acetolactate synthase (ALS) genes in tobacco through homology-based gene prediction using Arabidopsis ALS. Quantitative real-time PCR (qRT-PCR) and tissue distribution analyses suggested that NtALS1 was highly expressed in the tips of glandular trichomes. Subcellular localization analysis showed that the NtALS1 localized to the chloroplast. Moreover, in the wild-type K326 variety background, we generated two ntals1 loss-of-function mutants using the CRISPR-Cas9 system. Acylsugars contents in the two ntals1 mutants were significantly lower than those in the wild type. Through phylogenetic tree analysis, we also identified NtALS1 orthologs that may be involved in acylsugar biosynthesis in other Solanaceae species. Taken together, these findings indicate a functional role for NtALS1 in acylsugar biosynthesis in tobacco.

Novel polymorphic microsatellite markers isolated from the pen shell Atrina pectinata (Mollusca: Bivalvia: Pinnidae)

In this study, we isolated 21 novel polymorphic microsatellite DNA loci from the pen shell Atrina pectinata using magnetic-bead hybridization enrichment. The characteristics of these loci were tested using a population of 30 individuals collected from the Penglai coast, Shandong Province. The number of alleles ranged from 2 to 13, and polymorphism information content (PIC) varied from 0.1730 to 0.8954. Values for observed heterozygosity (HO) and expected heterozygosity (HE) ranged from 0.0714 to 0.9231 and from 0.1948 to 0.9237, respectively. Four loci deviated significantly from Hardy-Weinberg equilibrium. The newly developed microsatellite markers will be beneficial in assessing the genetic diversity, population structure and genetic conservation of A. pectinata, and in other relevant research.

Complete mitochondrial genome of Ark shell Scapharca subcrenata

Complete mitochondrial genome of Scapharca subcrenata was determined in this report. It is 48,161 bp in length, being the largest mitochondrial genome among reported shellfish at present. The entire mitochondrial genome consists of 57 genes including 12 protein-coding genes, 2 ribosomal RNAs and 41 transfer RNAs.

[Proliferation characteristics of a PK-15 cell-adapted strain of porcine parvovirus]

To study the proliferation characteristics of PPV in differently infected way and the variance of concentrations in different cells. A strain of porcine parvovirus(PPV) was adapted to PK-15 cells, and a Real-time fluorescent quantitative PCR (FQ-PCR) assay was developed based on the specific region of the NS1 gene of PPV to quantify the PPV. The FQ-PCR was used to measure the viral concentration of virus-infected cells by simultaneous or step by step inoculation and plot one-step growth curves. The proliferation characteristics of PPV strain in different cells lines (HeLa, MDBK, PK-15 ,ST, F81, BHK-21 and Marc-145) was also compared. The results showed the PK-15 cell -adapted strain of PPV produced CPE after 12 passages, and maintained stable CPE at the following 10 messages. The one-step growth curve showed that the virus concentration of simultaneous inoculation was higher than that of the step-by-step inoculation, and the proliferation cycle of step-by-step inoculation was shorter. The proliferation ability of PPV strain in different cells showed that CPE appeared first inPK-15, followed by ST, HeLa and MDBK, and the virus concentration was highest in ST, followed byPK-15, MDBK and HeLa. NO proliferation was observed in F81, BHK-21 and Marc-145 cells. These findings lay a material foundation for the basic researches on PPV and the development of vaccine.

Development of an improved pig model of piggyback liver transplantation with temporary portacaval shunting

AIM: To improve the piggy-back orthotopic liver transplantation (PBOLT) technique in pigs and to enhance the survival rate of pigs after liver transplantation.

METHODS: Pigs were divided into control group and experimental group. The inferior caval vein was separated from the liver of recipients by curettage and aspiration using Peng's multifunctional operative dissector in the control group. Temporary portacaval shunting was added in the experimental group to reduce congestion in the portal system during anhepatic phase.

RESULTS: The PBOLT procedures were performed in eight pairs of pigs in both the control group and experimental group, with a success rate of 87.5% and 100%, respectively. There were significant differences in cold ischemia time (142.8 min ± 7.4 min vs 155.6 min ± 8.3 min, P = 0.006), anhepatic phase duration (25.8 min ± 1.3 min vs 36.3 min ± 1.0 min, P = 0.000), and operation time (264.1 min ± 9.5 min vs 277.3 min ± 8.6 min, P = 0.012) between the two groups though no significant difference was noted in mean bleeding volume (892.5 mL ± 113.9 mL vs 888.8 mL ± 93.7 mL, P = 0.94). The 1-, 2-, 3- and 4-day survival rates were 87.5% and 100%, 25% and 100%, 12.5% and 87.5%, and 0% and 87.5% in the control group and experimental group, respectively. On day 10 after PBOLT, 87.5% of pigs of the experimental group were still alive (P = 0.000).

CONCLUSION: PBOLT with temporary portacaval shunting can maintain hemodynamic stability and relieve congestion of the portal system in pigs during liver transplantation. Control of gastrointestinal congestion is key to the success of liver transplantation and can raise the survival rate of pigs after liver transplantation.

Genetic susceptibility to haemorrhagic fever with renal syndrome caused by Hantaan virus in Chinese Han population

We report a significantly higher occurrence of HLA-DRB1*09 (51% vs. 23%, P = 0.002, OR = 3.57) and HLA-B*46-DRB1*09 (26% vs. 8%, P = 0.018, OR = 3.76) in patients with haemorrhagic fever with renal syndrome (HFRS) compared to the control group, suggesting Hantaan virus-induced HFRS is associated with a genetic predisposition in the Chinese Han population.

Othotopic liver transplantation in 500 rats using a reformed two-cuff method

AIM: To improve the method of rat othotopic liver transplantation using two cuffs and shorten anhepatic phase, and to raise the success rate of operation.

METHODS: The animals used in formal trial were divided five groups: (1) liver transplantation on normal rats was carried out after infusing apoptotic splenocytes of donors 1 wk before transplantation (including 4 subgroups); (2) liver transplantation on normal rats was carried out with simultaneous injection of apoptotic splenocytes from donors (including); (3) apoptotic splenocytes of donors were infused after liver transplantation on normal rats was carried out (including 4 subgroups); (4) liver transplantation on cirrhotic rats was carried out after infusing apoptotic splenocytes of donors 1 wk before transplantation (including 4 subgroups); (5) liver transplantation on normal rats was carried out after infusing apoptotic lymphocytes of donors 1 wk before transplantation (including 3 subgroups). Each subgroup contained 10 rats. Operating time, 2-day and 1-week survival rate of rats were observed.

RESULTS: The operating time on donor rats, the warm ischemia time of donor livers, the time for cuff preparation, the operating time on recipient rats, the anhepatic phase and the cold ischemia time of donor livers were 30 ± 5 min, 2 ± 0.5 min, 10 ± 2 min, 51 ± 10 min, 16 ± 4 min and 61 ± 5 min, respectively, in formal trials. The 2-day and 1-week survival rates were 96.8% (184/190) and 95.3% (181/190), respectively.

CONCLUSION: The reformed two-method can simplify the operating procedure, reduce complication and raise the survival rates.

Improved PCR-based subtractive hybridization strategy for cloning differentially expressed genes

An improved PCR-based subtractive hybridization strategy was used to clone apoptosis-related genes induced by all-trans retinoic acid (ATRA) from human promyelocytic leukemia cell line HL-60 cells. The protocol used the cap-finder method, long-distance PCR, streptavidin magnetic bead-mediated subtraction and spin column chromatography. Twenty-seven clones related to apoptosis were identified by reverse dot blot assay. Seventeen were known genes, of which seven have been reported to be apoptosis related. The remaining 10 were unknown genes, five of which were sequenced and named apr-1 to apr-5. apr-1, apr-2, apr-3 and TNF were reidentified by reverse dot blot, and it is suggested that they might be related to apoptosis. The results suggest that this strategy might be efficient for large-scale cloning of differentially expressed genes in target cells.

Anti-HIV type 1 activity of wild-type and functional defective RANTES intrakine in primary human lymphocytes

We have developed a genetic "intrakine" strategy to inactivate the CC-chemokine receptor 5 (CCR-5), the principal coreceptor for macrophage (M)-tropic HIV-1 viruses (Yang et al, 1997). The inactivation of CCR5 was achieved by targeting a modified CC-chemokine (RANTES) to the lumen of the endoplasmic reticulum (ER) to block the transport of the newly synthesized CCR-5. The transduced lymphocytes with the phenotypic CCR5 knockout were shown to be resistant to M-tropic HIV-1 infection. This study illustrated the feasibility of the intrakine strategy to block HIV-1 infection. In our current study, the potential clinical application of the intrakine approach was further evaluated in human peripheral blood lymphocytes (PBLs). PBLs were transduced with the RANTES intrakine gene by using retroviral vectors with the truncated low-affinity human nerve growth factor receptor (deltaNGFR) marker, and then isolated by an anti-NGFR antibody/magnetic bead method. The surface expression of CCR-5 in the transduced lymphocytes was dramatically inhibited, as demonstrated by flow cytometric assays. The transduced PBLs were shown to resist various types of M-tropic HIV-1 virus infection. The cell viability, cell proliferation rates, and cell surface markers of the intrakine-transduced PBLs were shown to be comparable to those of control PBLs. The transduced PBLs were also found to respond to the stimulation of various CXC- and CC-chemokines, other than RANTES. The transduced PBLs responded to tetanus antigen stimulation by increasing IL-2 production and cell proliferation. In addition, a functionally defective mutant of RANTES that retains its binding activity to CCR-5, but loses its signaling ability, was used to generate a mutant RANTES intrakine. The primary lymphocytes transduced with the mutant RANTES intrakine were found to be resistant to M-tropic HIV-1 infection. From these results, we conclude that the primary human lymphocytes transduced with either the wild-type or functionally defective RANTES intrakine are resistant to M-tropic HIV-1 infection, and maintain their basic biological functions. This study, therefore, indicates the potential clinical application of the intrakine approach for HIV-1 gene therapy.

Genetic co-inactivation of macrophage- and T-tropic HIV-1 chemokine coreceptors CCR-5 and CXCR-4 by intrakines

CC-chemokine receptor (CCR)-5 is the principal coreceptor for the entry of macrophage (M)-tropic HIV-1 viruses into a cell, while CXC-chemokine receptor (CXCR)-4 is the principal coreceptor for T cell line (T)-tropic HIV-1. In this study, we utilized a novel intracellular chemokine (intrakine) strategy to co-inactivate genetically both CCR-5 and CXCR-4 in human lymphocytes. The principle of co-inactivation of CCR-5 and CXCR-4 was illustrated by targeting the CC-intrakine and CXC-intrakine to the lumen of the endoplasmic reticulum (ER) for intracellular blockade of the transport of newly synthesized chemokine coreceptors to the cell surface. The lymphocytes with the phenotypic knock-out of CCR-5 and CXCR-4 were found broadly to resist the infection of M-tropic, T-tropic and dual-tropic HIV-1 viruses. Moreover, the transduced lymphocytes retained normal cell features, including the responsiveness to mitogen and recall antigen stimulation. Thus, this study to our knowledge, is the first to demonstrate that genetic co-inactivation of the M- and T-tropic HIV-1 principal coreceptors in lymphocytes or other cells could be a viable strategy for the long-term control of HIV-1 infection.

Phenotypic knockout of HIV type 1 chemokine coreceptor CCR-5 by intrakines as potential therapeutic approach for HIV-1 infection

A genetic defect in a CC-chemokine receptor (CCR)-5, the principal coreceptor for the macrophage-tropic HIV type 1 (HIV-1), recently was found to naturally protect CCR-5-defective, but healthy, individuals from HIV-1 infection. In this study, we mimic the natural resistance of the CCR-5-defective individuals by designing a strategy to phenotypically knock out CCR-5. The inactivation of the CCR-5 coreceptor is accomplished by targeting a modified CC-chemokine to the endoplasmic reticulum to block the surface expression of newly synthesized CCR-5. The lymphocytes transduced to express the intracellular chemokine, termed "intrakine," were found to be viable and resistant to macrophage-tropic HIV-1 infection. Thus, this gene-based intrakine strategy targeted at the conserved cellular receptor for the prevention of HIV-1 entry should have significant advantages over currently described approaches for HIV-1 therapy.

Inactivation of HIV-1 chemokine co-receptor CXCR-4 by a novel intrakine strategy

CXC-chemokine receptor (CXCR)-4/fusin, a newly discovered co-receptor for T-cell line (T)-tropic HIV-1 virus, plays a critical role in T-tropic virus fusion and entry into permissive cells. The occurrence of T-tropic HIV viruses is associated with CD4-positive cell decline and progression to AIDS, suggesting that the T-tropic HIV-1 contributes to AIDS pathogenesis. In this study, we used a novel strategy to inactivate CXCR-4 by targeting a modified CXC-chemokine to the endoplasmic reticulum (ER) to block the surface expression of newly synthesized CXCR-4. The genetically modified lymphocytes expressing this intracellular chemokine, termed "intrakine", are immune to T-tropic virus infection and appear to retain normal biological features. Thus, this genetic intrakine strategy is uniquely targeted at the conserved cellular receptor for the prevention of HIV-1 entry and may be developed into an effective treatment for HIV-1 infection and AIDS.

Potent antitumour activity of a new class of tumour-specific killer cells

Two approaches to the antibody-directed targeting of toxic or cytolytic activity and augmentation of cellular immune responses have been explored for tumour immunotherapy, but so far success has been limited. Obstacles facing immunotherapy are the limited accessibility of antibodies or antibody conjugates to solid tumours and the difficulty in obtaining tumour-specific cytotoxic lymphocytes. Here we generate a new class of tumour-specific killer cells by genetically modifying lymphocytes to produce and secrete a targeted toxin against an oncoprotein overexpressed on breast and other tumour cells. The transduced lymphocytes were shown to have potent and selective cytotoxicity to tumours in culture and nude mouse models. The potent in vivo antitumour activity is probably a result of the migration of the lymphocytes to tumours as a targeted toxin carrier, and production and accumulation of the targeted toxins inside tumours as a producer. Our approach, which has features of both antibody-directed and cell-mediated immunotherapy, may have application in a gene therapy context.

A new class of antigen-specific killer cells

A new class of antigen-specific killer cells that combines the features of antibody-mediated and cell-mediated immunity was designed. The principle and feasibility of this strategy are illustrated by creating an antigen-specific killer cell to produce and secrete targeted antibody-toxin molecules that recognize and kill human immunodeficiency virus (HIV)-1-infected cells. The transduced lymphocytes, which were able to produce and secrete the targeted toxin proteins, remained viable due to the lack of the target antigen on the cell surface. These transduced cells were found to have selective and potent cytotoxicity to the HIV-infected cells. This approach combines the specificity of antibodies, extreme potency of toxins, and effector-cell properties of T-cells to generate a new class of potent antigen-specific killer cells, which may have broad applications for the treatment of viral infection and other diseases. This study demonstrates the principle that mammalian cells can be genetically modified to produce targeted toxins, indicating that in vivo production of targeted toxins can be achieved to locally or systematically destroy targeted cells.

Intra- and extracellular immunization against HIV-1 infection with lymphocytes transduced with an AAV vector expressing a human anti-gp120 antibody

Recently, we developed a novel anti-HIV-1 approach by transducing an anti-gp120 antibody gene into lymphocytes, resulting in the resistance to HIV-1 infection by the combined intra- and extracellular binding activities of the neutralizing antibody. To extend this study, we improved the co-expression of the heavy and light chains of the Fab105 fragment of the anti-gp120 antibody F105 by using an internal ribosome entry site (IRES) sequence. The Fab105 expression cassette was then cloned into an adeno-associated virus (AAV) shuttle vector, and encapsidated recombinant AAV-Fab105 vectors were produced. The Fab105 antibody gene was shown to be transduced into human lymphocytes by using the recombinant AAV viruses. The transduced lymphocytes were able to produce and secrete the Fab105 fragments, while maintaining their normal morphology, growth rates, and responsiveness to mitogen stimulation. The infection of several primary HIV-1 patient isolates was effectively blocked in the transduced lymphocytes. This study indicates that the combined intra- and extracellular immunization approach may be useful for the treatment of HIV-1-infected patients.