A nitrate transporter encoded by ZmNPF7.9 is essential for maize seed development

Nitrogen is an essential macronutrient for plants and regulates many aspects of plant growth and development. Nitrate is one of the major forms of nitrogen in plants. However, the role of nitrate uptake and allocation in seed development is not fully understood. Here, we identified the maize (Zea mays) small-kernel mutant zmnpf7.9 and characterized the candidate gene, ZmNPF7.9, which was the same gene as nitrate transport 1.5 (NRT1.5) in maize. This gene is specifically expressed in the basal endosperm transfer layer cells of maize endosperm. Dysfunction of ZmNPF7.9 resulted in delayed endosperm development, abnormal starch deposition and decreased hundred-grain weight. Functional analysis of cRNA-injected Xenopus oocytes showed that ZmNPF7.9 is a low-affinity, pH-dependent bidirectional nitrate transporter. Moreover, the amount of nitrate in mature seeds of the zmnpf7.9 mutant was reduced. These suggest that ZmNPF7.9 is involved in delivering nitrate from maternal tissues to the developing endosperm. Moreover, most of the key genes associated with glycolysis/gluconeogenesis, carbon fixation, carbon metabolism and biosynthesis of amino acids pathways in the zmnpf7.9 mutant were significantly down-regulated. Thus, our results demonstrate that ZmNPF7.9 plays a specific role in seed development and grain weight by regulating nutrition transport and metabolism, which might provide useful information for maize genetic improvement.

Development of a fluorescent-intercalating-dye-based reverse transcription loop-mediated isothermal amplification assay for rapid detection of seasonal Japanese B encephalitis outbreaks in pigs

The standardization and validation of a one-step, single-tube, accelerated fluorescent-intercalating-dye-based reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay targeting the NS3 gene of Japanese B encephalitis virus (JEV) is described for rapid, simple, and high-throughput detection of JEV. The amplification can be completed in 35 min under isothermal conditions at 63°C by employing a set of six primers targeting the NS3 gene of JEV. The RT-LAMP assay described demonstrated high sensitivity for detecting JEV, with a detection limit in swine samples of 8.13 PFU/ml. The specificity of the selected primer sets was established by cross-reactivity studies with pathogens that exhibit similar clinical signs and testing of samples from healthy animals. The clinical applicability of the RT-LAMP assay was validated using either spiked samples or samples from seasonal outbreaks. The comparative evaluation of the RT-LAMP assay revealed 79.59 % concordance with conventional RT-PCR targeting the E gene of JEV. The RT-LAMP assay reported here is a valuable tool for rapid real-time and high-throughput seasonal infection surveillance and quarantine after outbreak through blood sampling by using ordinary real-time PCR thermocyclers without purchasing an expensive Loopamp real-time turbidimeter.

PTSD in a one year old girl after the Wenchuan earthquake in Sichuan, China

On May 12, 2008, at 2:28 PM, an earthquake measuring 8.0 on the Richter Scale struck Southwest China, with the epicenter in Wenchuan, a county about 92 km (about 58 miles) north-west of the Sichuan provincial capital of Chengdu. The earthquake destroyed about 6.5 million homes, leaving 4.8 million people homeless. Official figures stated that 69,196 are confirmed dead, including some 5,335 school children, while an additional 18,379 are listed as missing (Sina.com, 2009). An epidemiological survey conducted 2.5 months after the earthquake in two counties affected by the earthquake found the prevalence of post-traumatic disorder (PTSD) to be 45.5% in the heavily damaged county and 9.4% in the moderately damaged one (Kun et al., 2009).

Orally delivered foot-and-mouth disease virus capsid protomer vaccine displayed on T4 bacteriophage surface: 100% protection from potency challenge in mice

An orally delivered foot-and-mouth disease (FMD) vaccine has not previously been reported. By using a T4 bacteriophage nanoparticle surface gene-protein display system (T4-S-GPDS), we created a foot-and-mouth disease virus (FMDV) entire capsid protein vaccine candidate. On the T4 phage surface SOC site, a full length FMDV capsid precursor polyprotein (P1, 755 aa) and proteinase 3C (213 aa) derived from an infected pig of serotype O strain GD-10 (1999), were separately displayed on different T4 phage particle surfaces through inserting their coding region DNAs into the T4 phage genome, yielding phage strains T4-P1 and T4-3C. We also constructed a series of FMDV sub-full length capsid structural protein (subunit) containing T4 phage recombinant vaccines. Both sucking and young BALB/c mice were used as two kinds of FMDV vaccine potency evaluation models. Many groups of both model mice were vaccinated orally or by subcutaneous injection with varying FMDV-T4 phage recombinant vaccines, with and without addition of adjuvant, then challenged with a lethal dose of cattle source virulent FMDV. In the case of immunization with a mixture of phage T4-P1 and phage T4-3C particles without any adjuvant added, all mice were 100% protected following either oral or injection immunization, whereas 100% of the control, non-immunized mice and mice immunized with only T4 phage vector Z1/Zh(-) or wild-type T4(+)D phage died; in contrast, with FMDV subunit vaccine, less than 75% protection followed the same potency challenge in both mice model groups. In addition, two pigs immunized with a phage T4-P1 and phage T4-3C mix were protected upon housing together with infected pigs. This study represents a clear example of how FMD and other pathogenic disease vaccines can be prepared by a simple and efficient bacteriophage route.

Cloning of linear DNAs in vivo by overexpressed T4 DNA ligase: construction of a T4 phage hoc gene display vector

A method was developed to clone linear DNAs by overexpressing T4 phage DNA ligase in vivo, based upon recombination deficient E. coli derivatives that carry a plasmid containing an inducible T4 DNA ligase gene. Integration of this ligase-plasmid into the chromosome of such E. coli allows standard plasmid isolation following linear DNA transformation of the strains containing high levels of T4 DNA ligase. Intramolecular ligation allows high efficiency recircularization of cohesive and blunt-end terminated linear plasmid DNAs following transformation. Recombinant plasmids could be constructed in vivo by co-transformation with linearized vector plus insert DNAs, followed by intermolecular ligation in the T4 ligase strains to yield clones without deletions or rearrangements. Thus, in vitro packaged lox-site terminated plasmid DNAs injected from phage T4 were recircularized by T4 ligase in vivo with an efficiency comparable to CRE recombinase. Clones that expressed a capsid-binding 14-aa N-terminal peptide extension derivative of the HOC (highly antigenic outer capsid) protein for T4 phage hoc gene display were constructed by co-transformation with a linearized vector and a PCR-synthesized hoc gene. Therefore, the T4 DNA ligase strains are useful for cloning linear DNAs in vivo by transformation or transduction of DNAs with nonsequence-specific but compatible DNA ends.

Phage display of intact domains at high copy number: a system based on SOC, the small outer capsid protein of bacteriophage T4

Peptides fused to the coat proteins of filamentous phages have found widespread applications in antigen display, the construction of antibody libraries, and biopanning. However, such systems are limited in terms of the size and number of the peptides that may be incorporated without compromising the fusion proteins' capacity to self-assemble. We describe here a system in which the molecules to be displayed are bound to pre-assembled polymers. The polymers are T4 capsids and polyheads (tubular capsid variants) and the display molecules are derivatives of the dispensable capsid protein SOC. In one implementation, SOC and its fusion derivatives are expressed at high levels in Escherichia coli, purified in high yield, and then bound in vitro to separately isolated polyheads. In the other, a positive selection vector forces integration of the modified soc gene into a soc-deleted T4 genome, leading to in vivo binding of the display protein to progeny virions. The system is demonstrated as applied to C-terminal fusions to SOC of (1) a tetrapeptide; (2) the 43-residue V3 loop domain of gp120, the human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein; and (3) poliovirus VP1 capsid protein (312 residues). SOC-V3 displaying phage were highly antigenic in mice and produced antibodies reactive with native gp120. That the fusion protein binds correctly to the surface lattice was attested in averaged electron micrographs of polyheads. The SOC display system is capable of presenting up to approximately 10(3) copies per capsid and > 10(4) copies per polyhead of V3-sized domains. Phage displaying SOC-VP1 were isolated from a 1:10(6) mixture by two cycles of a simple biopanning procedure, indicating that proteins of at least 35 kDa may be accommodated.

Electroacupuncture reversed the inhibition of intestinal peristalsis induced by intrathecal injection of morphine in rabbits

Morphine elicits a series of adverse effects including the inhibition of intestinal motility in addition to the therapeutic benefit of alleviating postoperative pain. To ascertain the role of electroacupuncture (EA) in diminishing those detrimental effects on recovery, we imitated the clinical procedures in rabbits. Morphine was given via a preimplanted cannula within spinal subarachnoid space, while the duodenal motility, respiration rate and arterial pressure were simultaneously recorded. It was found that morphine (6 mg/rabbit, IT) markedly suppressed duodenal peristalsis, decreased respiration rate throughout 90 min observation. When EA was administered together with morphine, peristalsis of the duodenum was much less inhibited (P < 0.05, vs morphine alone group), but no significant improvement of respiratory depression was noticed (P > 0.05), nor obvious change of arterial pressure in both groups. The results strongly recommend extensive application of EA in postoperative care, so as to decrease both the required dosage of morphine and the subsequent occurrence of postoperative ileus, while attaining sufficient analgesia.

In vivo sequence variation of the human immunodeficiency virus type 1 env gene: evidence for recombination among variants found in a single individual

To assess in vivo sequence heterogeneity of the human immunodeficiency virus type 1 (HIV-1) env gene, we used the polymerase chain reaction to amplify proviral sequences present in peripheral blood mononuclear cell DNA of a patient with acquired immunodeficiency syndrome (AIDS). The amplified env gene fragment (575 bp) contains the first hypervariable region and part of the first conserved region. Eleven and twelve clones were sequenced, respectively, from specimens collected two months apart. Notable heterogeneity was observed among sequences recovered from both specimens. Also, the proviral population recovered from the first specimen varied significantly from that found in the second specimen. Both specimens contained forms with and without an 18 bp duplication. The presence or absence of this duplication, in addition to several point mutations, appear to define two molecular groups evolving in parallel within this patient. Several genotypes which had sequences characteristic of both groups occurred primarily in the second specimen; these can best be explained by multiple recombinational events between representatives of the two groups during reverse transcription. This study demonstrates that recombination may contribute significantly to the generation of diversity among HIV variants within a single individual.