Elaboration of an electroporation protocol for large plasmids and wild-type strains of Bacillus thuringiensis

AIMS

To elaborate an effective electroporation protocol for large plasmids and wild type strains of Bacillus thuringiensis.

METHODS AND RESULTS

The effect of DNA desalting, wall-weakening agency, cell growth conditions, electroporation solutions, and electric fields on electroporation efficiency was evaluated to optimize electroporation conditions for B. thuringiensis. By using this improved method, the greatest efficiency was reached 2 x 10(10 )CFU microg(-1) with pHT304, which is 10(4) times higher than previously reported. Four large plasmids (29.1, 44.9, 58 and 60 kb) were successfully transferred into the acrystalliferous B. thuringiensis strain BMB171; these results have not been achieved with previous protocols. Three wild type B. thuringiensis strains which could not be transformed previously were also transferred successfully.

CONCLUSIONS

This improved method is more efficient for small plasmids; it is also appropriate for large plasmids and wild type B. thuringiensis strains which were not transformed by previous procedures.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study established an effective electroporation protocol for large plasmids and wild type strains of B. thuringiensis. This method is well suited for the cloning and expression of huge DNA fragments such as gene clusters in B. thuringiensis. It also can be used as a reference method for other Bacillus strains that are refractory to electroporate.

Identification of an antiapoptotic protein complex at death receptors

Stimulation of death receptors activates the extrinsic apoptotic signaling pathway that leads to cell death. Although many steps of this apoptotic signaling cascade are known, few mechanisms that counterbalance the death signal have been described. We identified an antiapoptotic protein complex associated with death receptors that contains glycogen synthase kinase-3 (GSK3), DDX3 and cellular inhibitor of apoptosis protein-1 (cIAP-1). GSK3, DDX3 and cIAP-1 are associated in cells with each other and with death receptors. Blocking the actions of GSK3 or DDX3 potentiated caspase-3 activation induced by stimulation of four different death receptors in several types of cells. GSK3 restrained apoptotic signaling by inhibiting formation of the death-inducing signaling complex and caspase-8 activation. Stimulated death receptors surmount the antiapoptotic complex by causing GSK3 inactivation and cleavage of DDX3 and cIAP-1 to enable progression of the apoptotic signaling cascade, but the antiapoptotic complex remains functional in cancer cells resistant to death receptor stimulation, a resistance that is overcome by GSK3 inhibitors. Thus, an antiapoptotic complex of GSK3, DDX3 and cIAP-1 caps death receptors, providing a checkpoint to counterbalance apoptotic signaling.

Assisted infant toilet training: is it time for a critical revision?

Toilet training is an essential issue in child education, and its completion represents a developmental milestone. Although for the last 40 years the Western medical community has recommended to start toilet training after 18 months of age, today a growing number of parents are accepting assistant infant toilet training that can begin relatively soon after birth. As currently practiced, assisted infant toilet training emphasizes infant-caregiver communication for the gradual acquisition of bowel and bladder control. Signals emitted by the infant lead the caregiver during elimination assistance. This review will help the reader to understand this new phenomenon.

Expression and localisation of breast cancer resistance protein (BCRP) in human fetal membranes and decidua and the influence of labour at term

Breast cancer resistance protein (BCRP) is a multidrug resistant ABC transport protein (ABCG-2). It extrudes a wide range of substrates, including many chemotherapy drugs, steroids and folate. It is present in many cancers, as well as normal tissues, in particular barrier tissues such as the blood-brain barrier, the intestine, blood vessels and the human placenta. Human fetal membranes (amnion and chorion laeve) provide the barrier between the maternal uterine environment and the fetus. In the present study, we defined the expression and localisation of BCRP mRNA and protein in human fetal membranes (amnion and chorion) and attached decidua obtained before and following labour at term. BCRP protein and mRNA was expressed in all tissues examined and the levels of expression were not altered by labour. BCRP was localised to the amnion epithelial cells, chorion trophoblast cells and decidua stromal cells, as well as the endothelial cells of maternal blood vessels in the decidua, but was absent from mesenchymal cells. In the amnion epithelium, BCRP protein was localised to the apical surface, cytoplasm and membrane between cells. In the chorion trophoblast and decidua stromal cells, BCRP protein was localised to the plasma membrane. However, in the chorion trophoblast, BCRP protein was also highly expressed in the nucleus. The level of BCRP protein in the membranes was comparable to that in the placenta. These high levels raise the possibility that this transporter plays an important role in the physiological function of the tissues.

Triphalangeal thumb-polysyndactyly syndrome and syndactyly type IV are caused by genomic duplications involving the long range, limb-specific SHH enhancer

BACKGROUND

The Sonic hedgehog (SHH) protein produced in the zone of polarising activity (ZPA) is a major determinant of the identity and numbers of digits in early limb development. Preaxial polydactyly types II (PPD2) and III (PPD3) have been mapped to a critical region at 7q36, and subsequently shown to be caused by point mutations in the ZPA regulatory sequence (ZRS), a long range cis-regulator for the SHH gene. Triphalangeal thumb-polysyndactyly syndrome (TPTPS) and syndactyly type IV (SD4) were also mapped to the 7q36 region but pathogenic mutations in ZRS have not yet been affirmed.

METHODS AND RESULTS

We performed linkage and haplotype analysis in six Han Chinese families with TPTPS and/or SD4, and refined the disease locus to an interval of 646 kb containing ZRS. In all families, the affected individuals heterozygous at rs10254391 (a single nucleotide polymorphism within ZRS) revealed a remarkable allele imbalance on sequence chromatogram. Using real-time quantitative polymerase chain reaction (qPCR), we identified duplication of ZRS and found that this duplication segregated with the limb phenotypes in all families but was not detected in unaffected family members or in unrelated control individuals. The duplication was also confirmed by interphase fluorescence in situ hybridisation (FISH) in an affected individual. We designed 17 additional qPCR assays and defined the minimum duplications in all six families, ranging from 131kb to 398kb.

CONCLUSION

Both TPTPS and SD4 are due to duplications involving ZRS, the limb specific SHH enhancer. Point mutations in the ZRS and duplications encompassing the ZRS cause distinctive limb phenotypes.

Photo-patternable GeO2-contained organic-inorganic hybrid sol-gel films for photonic applications

Photo-patternable GeO(2)-contained organic-inorganic hybrid films, which can be used for the low cost and mass production of integrated photonic circuits, were synthesized by combining a low-temperature sol-gel process with a spin-coating technique. Optical waveguide properties and photochemical activities of the hybrid sol-gel films were characterized and monitored by a prism coupling technique and a Fourier transform infrared spectroscopy. Advantages for fabrication of ridge structures based on the hybrid films were demonstrated by one-step spin-coating process followed by direct ultraviolet light irradiation. The results indicate that the as-prepared photo-patternable hybrid materials have great applicability for the fabrication of photonic components, and the fabrication process has the advantages of cost-effect and very short processing time over inorganic materials patterning methods.

Toilet training started during the first year of life: a report on elimination signals, stool toileting refusal and completion age

AIM

The aim of this study was to examine an international population of children who started toilet training in the first year of life.

METHODS

Two hundred eighty-six participants completed an anonymous questionnaire. Main outcomes variables were: presence of elimination signals (ES), elimination pattern consistency (EPC), stool toileting refusal (STR), and toilet training completion age. The analysis included the differences in completion age regarding each of the following variables: start age range, presence of ES, EPC, STR and country of residency for those who completed either bowel or bladder training at the time of survey completion.

RESULTS

Over 90% of the respondents reported that their children showed ES. STR was nearly 12%. For those who completed toilet training at the time of survey completion mean completion ages for daytime dryness and bowel control were 17.4 and 15.0 months, respectively; those who initiated toilet training during the first 6 months completed training earlier than those who started later; those who showed STR at the beginning of training completed bowel training later than those who did not (P<0.001); those who exhibited ES for voiding or bowel movements completed day-dryness and bowel training earlier than those who did not (P<0.001). Among countries of residency, those children who resided in the USA and Canada completed bowel training the earliest (P<0.001).

CONCLUSION

This is the first report which provides data on the current infant toilet training method, which is based mainly on ES and patterns, and practiced by motivated caregivers. Notable side effects were not observed.

Comparative study on effect of different promoters on expression of cry1Ac in Bacillus thuringiensis chromosome

AIMS

The aim of this work was to investigate the effect of cry3A promoter on the expression of cry1Ac in Bacillus thuringiensis chromosome and stably enhance the production of different cry genes under the control of cry3A promoter.

METHODS AND RESULTS

The cry1Ac gene, which is specific to Lepidopteran larvae, was integrated into the chromosome of a B. thuringiensis plasmid-free and acrystalliferous strain BMB171, under the control of cry3A promoter and cry1Ac promoter, respectively. The expression of cry1Ac genes in the chromosome of host strain was investigated. The results from sodium dodecyl sulfate-polyacrymide gel electrophoresis, crystal observation and bioassay showed that either integrated with cry3A promoter (cry3Apro-cry1Ac) or with its native promoter (cry1Acpro-cry1Ac), cry1Ac gene could efficiently and stably express in the chromosome. The production of cry3Apro-cry1Ac gene was higher than that of cry1Acpro-cry1Ac gene.

CONCLUSIONS

The cry3A promoter enhanced the expression of cry1Ac gene efficiently either on the chromosome or on the plasmid in B. thuringiensis strain.

SIGNIFICANCE AND IMPACT OF THE STUDY

So far, the comparative studies on cry3A promoter and other cry promoters were carried on B. thuringiensis plasmids. This system offers an additional method for potentially improving the efficacy of B. thuringiensis insecticidal proteins efficiently, stably and safely.

Endoscopic ultrasound-guided interstitial chemotherapy in the pancreas: results in a canine model

BACKGROUND AND STUDY AIM

Interstitial chemotherapy using surgically implanted, biodegradable polymers has been reported. Our aim in this study was to investigate the feasibility and safety of endoscopic ultrasound- (EUS-) guided interstitial chemotherapy of the pancreas in a canine model.

MATERIALS AND METHODS

A therapeutic 19-gauge needle with a large channel was inserted into the pancreas under EUS guidance. The polymers for sustained intratumoral release of 5-fluorouracil were implanted into the tissue by the needle. After 14 days of clinical observation, the animals were sacrificed and the tissue response to the local chemotherapy was examined.

RESULTS

All the polymers were implanted successfully and no implant migration occurred. Localized tissue fibrous necrosis was achieved in the pancreas, without significant complications. The apoptotic index of the tissue within 1 cm of the focus increased. Biochemical parameters were normal in all the dogs.

CONCLUSIONS

EUS-guided implantation of polymers is a safe, simple, and minimally invasive technique for interstitial chemotherapy in the pancreas.

Herbicide exposure modifies GSTP1 haplotype association to Parkinson onset age: the GenePD Study

BACKGROUND

Polymorphisms in the glutathione S-transferase pi gene (GSTP1), encoding GSTP1-1, a detoxification enzyme, may increase the risk of Parkinson disease (PD) with exposure to pesticides. Using the GenePD Study sample of familial PD cases, we explored whether GSTP1 polymorphisms were associated with the age at onset of PD symptoms and whether that relation was modified by exposure to herbicides.

METHODS

Seven single-nucleotide polymorphisms (SNPs) were genotyped and tested for association with PD onset age in men in three strata: no exposure to herbicides, residential exposure to herbicides, and occupational exposure to herbicides. Haplotypes were similarly evaluated in stratified analyses.

RESULTS

Three SNPs were associated with PD onset age in the group of men occupationally exposed to herbicides. Three additional SNPs had significant trends for the association of PD onset age across the herbicide exposure groups. Haplotype results also provided evidence that the relation between GSTP1 and onset age is modified by herbicide exposure. One haplotype was associated with an approximately 8-years-earlier onset in the occupationally exposed group and a 2.8-years-later onset in the nonexposed group.

CONCLUSIONS

Herbicide exposure may be an effect modifier of the relation between glutathione S-transferase pi gene polymorphisms and onset age in familial PD.

Inhibition of expression of rna polymerase with small interfering RNAs targeting a conserved motif in the respective viral genes in viruses of the family Flaviviridae

The RNA-dependent RNA polymerase (RdRp) in viruses of the family Flaviviridae plays an important role in the viral replication process and in the forming of a replicase complex. We used small interfering RNAs (siRNAs) corresponding to the highly conservative Motif V of RdRp gene of different viruses to examine their role in modulating the expression of RdRp. Evaluation of the expression of RdRps was performed by the fluorescence, flow cytometry, Western blotting, and real-time PCR. We found that Classical swine fever virus (CSFV) siRNA could completely block the transcription and expression of RdRp. Additionally, Hepatitis C virus (HCV) siRNA could cause effective inhibition of RdRp, whereas Japanese encephalitis virus siRNA did not show significant repression of corresponding RdRp. These results demonstrated that siRNAs inhibited the expression of tested RdRps at the transcription level or at the posttranscriptional processing to a different extent.