Modular vector assembly enables rapid assessment of emerging CRISPR technologies

The diversity of CRISPR systems, coupled with scientific ingenuity, has led to an explosion of applications; however, to test newly described innovations in their model systems, researchers typically embark on cumbersome, one-off cloning projects to generate custom reagents that are optimized for their biological questions. Here, we leverage Golden Gate cloning to create the Fragmid toolkit, a modular set of CRISPR cassettes and delivery technologies, along with a web portal, resulting in a combinatorial platform that enables scalable vector assembly within days. We further demonstrate that multiple CRISPR technologies can be assessed in parallel in a pooled screening format using this resource, enabling the rapid optimization of both novel technologies and cellular models. These results establish Fragmid as a robust system for the rapid design of CRISPR vectors, and we anticipate that this assembly approach will be broadly useful for systematic development, comparison, and dissemination of CRISPR technologies.

Modular vector assembly enables rapid assessment of emerging CRISPR technologies

The diversity of CRISPR systems, coupled with scientific ingenuity, has led to an explosion of applications; however, to test newly-described innovations in their model systems, researchers typically embark on cumbersome, one-off cloning projects to generate custom reagents that are optimized for their biological questions. Here, we leverage Golden Gate cloning to create the Fragmid toolkit, a modular set of CRISPR cassettes and delivery technologies, along with a web portal, resulting in a combinatorial platform that enables scalable vector assembly within days. We further demonstrate that multiple CRISPR technologies can be assessed in parallel in a pooled screening format using this resource, enabling the rapid optimization of both novel technologies and cellular models. These results establish Fragmid as a robust system for the rapid design of CRISPR vectors, and we anticipate that this assembly approach will be broadly useful for systematic development, comparison, and dissemination of CRISPR technologies.

A Phase 0 Study Assessing the Intracranial Activity of a Metabolic Radiosensitizer in Patients with Glioblastoma

PURPOSE/OBJECTIVE(S)

Efforts to overcome treatment resistance in glioblastoma (GBM) have been unsuccessful due to tumor heterogeneity and poor intracranial drug penetration. Targeting altered metabolism is a promising approach to improve GBM therapy despite this heterogeneity. Mycophenolate mofetil (MMF) is an inhibitor of purine synthesis that sensitizes GBM to radiation and temozolomide (TMZ) in vitro and in vivo, but its ability to cross the blood brain barrier and inhibit GBM metabolism in patients is unknown. NCT04477200 is a phase 0/1 dose escalation study of MMF combined with radiation and temozolomide in GBM. Here we report the phase 0 results of this study assessing the intracranial activity of MMF.

MATERIALS/METHODS

Purine (GTP and IMP) and mycophenolic acid (MPA, the active metabolite of MMF) concentrations were determined using mass spectrometry in flash-frozen tumor (enhancing and non-enhancing) and normal cortex obtained from 8 patients with recurrent GBM who received MMF (500, 1000, 1500 and 2000 mg BID, N = 2 patients each dose level) for 1 week prior to re-resection and 5 control patients who did not receive MMF prior to re-resection. Plasma MPA concentration was similarly quantified to calculate the enhancing tumor, non-enhancing tumor and normal cortex to plasma MPA ratios.

RESULTS

Patients who received MMF had a mean MPA concentration of 2.2 ± 0.7 µM in the enhancing tumor samples, 1.2 ± 0.5 µM in the non-enhancing tumor samples and 1.3 ± 0.5 µM in normal cortex. MPA concentration was negligible in control patients. This corresponded to tissue/plasma MPA ratios of 0.31, 0.17 and 0.10 for enhancing tumor, non-enhancing tumor and normal cortex, respectively. The GTP/IMP ratio was decreased by 75% in enhancing tumor in MMF-treated patients compared to untreated controls (p = 0.009), indicating effective target engagement and inhibition of purine synthesis. The GTP/IMP ratio was also decreased in cortex and non-enhancing tumor, though a paucity of control samples prevented statistical analysis.

CONCLUSION

Twice daily MMF treatment yields intracranial drug concentrations above 1 µM and lowers the GTP/IMP ratio in GBMs, consistent with target engagement. As we have previously observed radiosensitization in vitro with MPA concentrations of 1 µM, these data suggest that MMF may achieve adequate CNS penetration for therapeutic benefit. The Phase 1 component of this study to determine the dose limiting toxicity and maximally tolerated dose of MMF when combined with reirradiation in recurrent GBM and radiation and TMZ in newly diagnosed GBM is ongoing.

Clinical characteristics, genes identification and follow-up study of a patient with central venous thrombosis from a protein S deficiency pedigree

OBJECTIVE

To explore the clinical and prognostic features of CVT caused by PROS1 gene mutations and to provide clinical experience for new oral anticoagulants, such as rivaroxaban, in the treatment of CVT with a high risk of thrombosis.

PATIENTS AND METHODS

The CVT patient's clinical symptoms were described, and the brain imaging and blood coagulation tests were performed to confirm the diagnosis of CVT. The patient's family members were recruited to receive blood coagulation tests and ultrasonic examination of lower limb vessels. Genetic analysis on the pedigree was carried out to identify the responsible gene for PS deficiency. We followed-up with this patient for 24 months to evaluate the clinical outcomes, laboratory results and imaging performances of CVT.

RESULTS

The patient presented with typical CVT symptoms, including headache and epilepsy. Brain CT showed hemorrhage in the bilateral frontal lobe and left occipital lobe, while MRV demonstrated that thrombus had occurred. It was reviewed that the patient and his mother had a history of bilateral leg deep vein thrombosis. Gene tests revealed that the patient and two family members carried a heterozygous mutation of PROS1 (c.751_752delAT, p.M251Vfs*17). During 24 months of follow-up study, the patient was treated with rivaroxaban continuously and recovered well, supported by an mRS score that remained below 2. Blood coagulation tests were within normal limits, and MRV revealed partial recanalization of the cerebral venous sinus.

CONCLUSIONS

The frame shift mutation in the PROS1 gene (c.751_752delAT) may greatly affect the function of protein S and lead to a severe phenotype of CVT. Rivaroxaban showed a satisfying therapeutic effect in this CVT patient with hereditary thrombophilia.

Seed dormancy profiles for forest dynamics plot data: focusing on a tropical seasonal rainforest in Xishuangbanna, southwest China

Long-term forest dynamics monitoring plots provide information on number of individual species in the plot, allowing us for the first time to construct seed dormancy profiles at the species and individual levels for a specific site. Focusing on the Xishuangbanna tropical season rainforest plot (XTRDP), we used data from nine forest dynamics plots (two for tropical, four for subtropical and three for temperate) and information on kind of seed dormancy to generate seed dormancy profiles for communities across tropical to temperate latitudes at the species and individual levels. Seed dormancy information was collected from previous publications, and some data were provided by two germplasm banks that test seed germination of wild plants in China. In XTRDP, 35% of the species and 58% of individuals have non-dormant seeds; the dominant species have non-dormant seeds. In all plots, the most common kind of dormancy among species and individuals with dormant seeds was physiological dormancy. At the species level, the profile for tropical, subtropical and temperate plots was similar to profiles for each of these vegetation regions. In all plots, except one subtropical plot, the percentage of species versus individuals with dormant seeds differed. All temperate plots had a higher percentage of individuals than species with dormant seeds, but this pattern was not consistent for tropical or subtropical plots. We show that dormancy increases with latitude at both the species and individual levels. Dormancy profiles at the individual tree level provide new insight into seed dormancy relationships within plant communities.

Development of walnut oil and almond oil blends for improvements in nutritional and oxidative stability

For the increase in oxidative stability and phytonutrient contents of walnut oil (WO), 5, 10, 20 and 30% blends with almond oil (AO) were prepared. The fatty acid compositions and the micronutrients of the oil samples such as tocopherol, phytosterol and squalene were measured by GC-MS and HPLC. It was found that the proportions of PUFAs/SFAs in blended oils with high AO contents were lowered, and the blends contained higher levels of tocopherols, phytosterols and squalene than those of pure WO. The 60 °C oven accelerated oxidation test was used to determine the oxidative stability of the blended oil. The fatty acid composition, micronutrients and oxidation products were determined. The results showed that the oxidation stability of the blended oil increased with an increasing proportion of AO. In addition, a significant negative correlation between micronutrient and oxidation products was observed as the number of days of oxidation increased.

NGS-Integrator: An efficient tool for combining multiple NGS data tracks using minimum Bayes' factors

BACKGROUND

Next-generation sequencing (NGS) is widely used for genome-wide identification and quantification of DNA elements involved in the regulation of gene transcription. Studies that generate multiple high-throughput NGS datasets require data integration methods for two general tasks: 1) generation of genome-wide data tracks representing an aggregate of multiple replicates of the same experiment; and 2) combination of tracks from different experimental types that provide complementary information regarding the location of genomic features such as enhancers.

RESULTS

NGS-Integrator is a Java-based command line application, facilitating efficient integration of multiple genome-wide NGS datasets. NGS-Integrator first transforms all input data tracks using the complement of the minimum Bayes' factor so that all values are expressed in the range [0,1] representing the probability of a true signal given the background noise. Then, NGS-Integrator calculates the joint probability for every genomic position to create an integrated track. We provide examples using real NGS data generated in our laboratory and from the mouse ENCODE database.

CONCLUSIONS

Our results show that NGS-Integrator is both time- and memory-efficient. Our examples show that NGS-Integrator can integrate information to facilitate downstream analyses that identify functional regulatory domains along the genome.

[A study on the relationship between insufficient sleep and obesity among children and adolescents in China]

Objective: To analyze the relationship between insufficient sleep and obesity or central obesity in Chinese Han children and adolescents aged 9-18 years. Methods: A total of 172 710 students who participated in the 2014 Chinese National Survey on Students Constitution and Health with complete data of sleep duration and physical examination, were selected as study subjects. Insufficient sleep was defined, according to the amount of sleep for pediatric populations recommended by the American Academy of Sleep Medicine. Obesity and central obesity of children and adolescents were judged by experts from the Group of China Obesity Task Force and Health Industry Standards in China. Differences between groups were compared by using the t test or χ(2) test. Logistic regression method was applied to assess the relationship between insufficient sleep and obesity or central obesity. Results: In 2014, numbers of students with insufficient sleep, obesity and central obesity among Chinese Han children and adolescents aged 9-18 years appeared as 133 410 (77.2%), 11 145 (6.5%), and 12 603 (17.8%), respectively. Among the students with insufficient sleep, 8 358 (6.3%) were with obesity and 12 244 (17.9%) were with central obesity. The prevalence of obesity and central obesity among boys with insufficient sleep was higher than that in girls. Pupils with insufficient sleep showed the highest prevalence of obesity and central obesity. After controlling for potential confounders, the risk of obesity appeared an increase of 14.5% (OR=1.145, 95%CI: 1.092-1.200) and the risk of central obesity increased by 12.7% (OR=1.127, 95%CI: 1.078-1.178) in students with insufficient sleep, when compared with those with adequate sleep. Compared with those whose daily sleep duration was less than 6 hours, the ones who slept 7-10 hours per day showed significantly reduction on the risk of obesity and central obesity in students. Conclusions: Insufficient sleep significantly increase the risk of obesity and central obesity in children and adolescents while adequate sleep of 7-10 hours per day would reduce the risk of obesity and central obesity in students.

[Clinical analysis of 382 immediately breast reconstruction after mastectomy in Beijing City, Tianjin City and Hebei Province from 2012 to 2016]

Objective: To summarize the status of immediate breast reconstruction (IBR) after mastectomy in Beijing City, Tianjin City and Hebei Province. Methods: A retrospective analysis was made on the data of 382 cases with breast cancer who were treated and followed up successfully with immediate breast reconstruction after mastectomy from January 2012 to December 2016 in Beijing City, Tianjin City and Hebei Province. Clinic data of the followed-up 382 cases (all female, age (38.5±4.2) years (range: 24 to 70 years)), including general information, tumor information, sugery methods, and treatments after surgery were collected. The survival status, metastasis,complications and prognosis were followed up. Cosmetic effcet was evalated by Harris method, and life quality by Functional Assessment of Cancer Therapy-Breast scale (FACT-B). χ(2) test was used to compare the difference between year 2012 and year 2013 to 2016. Bonferroni method was used to correct the inspection level, which was 0.05/10=0.005. The trend of IBR rate (ratio of IBR to modified radical mastectomy) from 2013 to 2016 was analyzed by trend χ(2) test. Results: There was 46 cases in stage 0, 152 cases in stage Ⅰ, 165 cases in stage Ⅱ, 19 cases in stage Ⅲ. Twenty-five cases was treated by neoadjuvant chemotherapy, 231 by chemotherapy and 35 by radiotherapy. The proportion of implant reconstruction was 48.7% (186/382), more than expanded of 21.5% (82/382), with latissimus dorsi of 12.0% (46/382), TRAM of 8.9% (34/382), DIEP of 2.1% (8/382), and latissimus plus implant of 6.8% (26/382). According to the Harris standard, the excellent and good rate of the cosmetic effect of the reconstructed breast was 93.7%. The score of FACT-B was 108.20±16.9 (range: 67 to 144) 1 year postoperatively. Compared with 2012, the IBR rate was significant increased, till 2015, the IBR rate was 153/10 000 cases (χ(2)=47.028, P=0.000). Conclusions: There is a significant increase on IBR rate in Beijing City, Tianjin City and Hebei province by year. Most of cases received IBR is stage Ⅰ to Ⅱ. Implant reconstruction is the main reconstructive method. Postoperative cosmetic effects and quality of life are both meet patients' demon.

[The method of blood pressure evaluation among children and adolescents aged 7 to 17 years old in China]

The national health industry standard (WS/T 610-2018), 'the reference of screening for elevated blood pressure among children and adolescents aged 7-to 18-years-old', plays a significant role in the standardization of the blood pressure evaluation, the early detection of high blood pressure, and the early intervention of hypertension and other chronic non-communicable diseases among Chinese children and adolescents. This standard gives screening thresholds for blood pressure assessment of children and adolescents in different genders, ages, and heights. Given the complexity of applying this standard, it is error-prone and less efficient to evaluate blood pressure one by one or program this procedure. Therefore, this study provides a SPSS package based on the standard for researchers to download and use, combined with specific cases to guide the use of this package to evaluate the blood pressure of children and adolescents step by step, which could empower researchers to accurately and efficiently conduct blood pressure screening for children and adolescents in China.

[The change in mortality and major causes of death among Chinese adolescents from 1990 to 2016]

Objective: To analyze the change in mortality and major causes of death among Chinese adolescents aged 10-19 years from 1990 to 2016. Methods: Data of death for Chinese adolescents aged 10-19 years were extracted from the Global Burden of Disease Study 2016 (GBD 2016). The data was used to describe the change in mortality of Chinese adolescents from 1990 to 2016.Top 15 causes of death were compared between 1990 and 2016. Results: From 1990 to 2016, the all-cause mortality of Chinese adolescents aged 10-19 years old dropped from 102.5/100 000 to 41.2/100 000, reaching about a half of the global average (78.6/100 000) but still almost twice as high as the average of high-income countries (24.3/100 000) by 2016; the reduction in mortality was higher among females than that among males (decreased 68.7% vs. 54.7%), and among adolescents aged 10-14 years than that among those aged 15-19 years (decreased 62.1% vs. 57.1%). During the 26-year period, the cause-specific mortality of all top 15 causes saw sharp decreases. Among them, communicable, maternal, and nutritional diseases saw the most significant decrease (78.1%), and its proportion in all adolescent deaths fell from 11.1% to 6.1%. Meanwhile, non-communicable diseases and injuries saw relatively small decreases (58.2% and 57.3% respectively), and their proportions rose from 33.4% and 55.6% to 34.8% and 59.1%, respectively. The top 5 causes of death changed from drowning (17.39/100 000 in mortality, 17.0% in proportion), road injuries (14.77/100 000, 14.4%), self-harm (11.44/100 000, 11.2%), leukemia (5.48/100 000, 5.4%) and interpersonal violence (3.12/100 000, 3.0%) in1990 into road injuries (9.27/100 000, 22.5%), drowning (6.83/100 000, 16.6%), leukemia(2.73/100 000, 6.6%), self-harm (2.53/100 000, 6.2%) and congenital birth defects (1.76/100 000, 4.3%) in 2016, and tuberculosis, poisonings and rheumatic heart disease had dropped out of the top 15 in 2016. Conclusion: The mortality of Chinese adolescents aged 10-19 years has decreased significantly, but still higher than developed countries. Since 1990, injuries,especially for road injuries and drowning, have always been the leading causes of death among Chinese adolescents aged 10-19 years, followed by non-communicable diseases.

Appropriate dose of Lactobacillus buchneri supplement improves intestinal microbiota and prevents diarrhoea in weaning Rex rabbits

This study examined the effects on intestinal microbiota and diarrhoea of Lactobacillus buchneri supplementation to the diet of weaning Rex rabbits. To this end, rabbits were treated with L. buchneri at two different doses (LC: 104 cfu/g diet and HC: 105 cfu/g diet) for 4 weeks. PCR-DGGE was used to determine the diversity of the intestinal microbiota, while real-time PCR permitted the detection of individual bacterial species. ELISA and real-time PCR allowed the identification of numerous cytokines in the intestinal tissues. Zonula occludens-1, polymeric immunoglobulin receptor and immunoglobulin A genes were examined to evaluate intestinal barriers. Results showed that the biodiversity of the intestinal microbiota of weaning Rex rabbits improved in the whole tract of the treated groups. The abundance of most detected bacterial species was highly increased in the duodenum, jejunum and ileum after L. buchneri administration. The species abundance in the HC group was more increased than in the LC group when compared to the control. Although the abundance of Enterobacteriaceae exhibited a different pattern, Escherichia coli was inhibited in all treatment groups. Toll-like receptor (TLR)2 and TLR4 genes were down-regulated in all intestinal tissues as the microbiota changed. In the LC group, the secretion of the inflammatory cytokine tumour necrosis factor-α was reduced, the gene expression of the anti-inflammatory cytokine interleukin (IL)-4 was up-regulated and the expression of intestinal-barrier-related genes was enhanced. Conversely, IL-4 expression was increased and the expression of other tested genes did not change in the HC group. The beneficial effects of LC were greater than those of HC or the control in terms of improving the daily weight gain and survival rate of weaning Rex rabbits and reducing their diarrhoea rate. Therefore, 104 cfu/g L. buchneri treatment improved the microbiota of weaning Rex rabbits and prevented diarrhoea in these animals.

[Effects of perforator flaps combined with muscle flaps for repairing grade Ⅳ pressure ulcers in ischial tuberosity of elderly patients]

Objective: To explore effects of perforator flaps combined with muscle flaps for repairing grade Ⅳ pressure ulcers in ischial tuberosity of elderly patients. Methods: Nine elderly patients with grade Ⅳ pressure ulcers in ischial tuberosity were hospitalized in our burn ward from April 2014 to April 2017. Size of wounds ranged from 5 cm×3 cm to 12 cm×7 cm, and depth of sinus ranged from 6 to 22 cm. After admission, emergency debridement or debridement in selective time was performed. After debridement, the wounds were treated with continuous vacuum assisted closure therapy. After the treatment for 1 to 2 weeks, tissue flaps repair operations were performed. Four patients were repaired with inferior gluteal artery perforator flaps combined with long head of biceps femoris muscle flaps. Three patients were repaired with inferior gluteal artery perforator flaps combined with semimembranous muscle flaps. One patient was repaired with inferior gluteal artery perforator flap combined with gracilis muscle flap. One patient was repaired with femoral profound artery perforator flap combined with gluteus maximus muscle flap, and the distal area of femoral profound artery perforator flap of the patient which showed intraoperative cyanosis of 6 cm×4 cm was thinned to medium thickness skin to cover the muscle flap. The other eight patients showed no abnormality during operation. Size of perforator flaps ranged from 7 cm×5 cm to 14 cm×12 cm, and size of muscle flaps ranged from 11 cm×4 cm to 24 cm×6 cm. The donor sites of flaps were all sutured directly. Results: The tissue flaps and skin graft of all patients survived well after operation. During follow-up of 8 to 35 weeks, operative area of all patients showed good shape and texture, with no local diabrosis or recurrence of pressure ulcers. Conclusions: The combination of perforator flaps and muscle flaps is effective in repairing and reducing recurrence of grade Ⅳ pressure ulcers in ischial tuberosity of elderly patients.

Maternal vitamin D beneficially programs metabolic, gut and bone health of mouse male offspring in an obesogenic environment

BACKGROUND/OBJECTIVES

Vitamin D is an anti-inflammatory nutrient and a determinant of bone health. Some prospective studies suggest that maternal vitamin D status is positively associated with offspring bone mass. We found that serum concentrations of lipopolysaccharide (LPS), an inflammatory molecule related to adiposity, insulin resistance and bone resorption, is lower in healthy mouse offspring exposed to high dietary vitamin D during pregnancy and lactation. LPS reaches the circulation via the gut. This study investigated whether maternal vitamin D programs metabolic, gut and bone health of male offspring in an obesogenic environment.

METHODS

C57BL/6J dams received an AIN-93G diet with high (H) or low (L) vitamin D during pregnancy and lactation. At weaning, offspring remained on their dam's vitamin D level (LL or HH) or were switched (LH or HL) and fed a high fat (44.2%) and sucrose (19.8%) diet. Glucose response, adiposity, systemic inflammation (LPS, cytokines), intestinal permeability and mass, strength and microarchitecture of trabecular and cortical bone were assessed in 7-month-old male offsprings.

RESULTS

Higher maternal dietary vitamin D resulted in lower intestinal permeability (fecal albumin, P=0.010) and benefited trabecular but not cortical bone structure at the distal femur (higher trabecular number, P=0.022; less trabecular separation, P=0.015) and lumbar vertebra 2 (bone volume/total volume%, P=0.049). Higher maternal and offspring vitamin D resulted in lower fasting glucose (HH versus LL, P=0.039) and serum LPS concentrations (dam diet, P=0.011; pup diet, P=0.002). Higher offspring vitamin D resulted in lower epididymal fat pad relative weight (P=0.006). The serum concentrations of IL-6 and TNF-α did not differ among groups.

CONCLUSIONS

Maternal dietary vitamin D beneficially programs intestinal permeability and systemic LPS concentration, which is accompanied by stronger trabecular bone in an obesogenic environment. Thus, the gut may mediate vitamin D effects. Moreover, optimizing vitamin D in early life may be critical for later health.

Multimodal-Imaging-Guided Cancer Phototherapy by Versatile Biomimetic Theranostics with UV and γ-Irradiation Protection

A versatile biomimetic theranostic agent based on magnetic melanin nanoparticles is developed for positron-emission tomography/magnetic resonance/photoacoustic/photothermal multimodal-imaging-guided cancer photothermal therapy and UV and γ-irradiation protection.

Temporal-spatially transformed synthesis and formation mechanism of gold bellflowers

Anisotropic gold nanostructures with unique plasmonic properties, specifically the strong absorption of light in the near-infrared region (650-900 nm) due to the excitation of plasmon oscillations, have been widely employed as photothermal conversion agents (PTCAs) for cancer photothermal therapy (PTT). However, the reported PTCAs show suboptimal photothermal conversion efficiency (η), even gold nanocages (η = 63%), which limits their biomedical applications. Herein, we fabricated gold bellflowers (GBFs) with an ultrahigh photothermal conversion efficiency (η = 74%) via a novel liquid/liquid/gas triphasic interface system, using chloroauric acid as a gold source, and o-phenetidine as a reducing agent. The well-defined GBFs with multiple-branched petals show adjustable localized surface plasmon resonance (LSPR) from 760 to 1100 nm by tuning the petal length and circular bottom diameter. Originating from the monophasic and biphasic systems used in the creation of gold nanourchins (GNUs) and gold microspheres (GMPs) respectively, the triphasic interface system successfully produced GBFs. The possible formation mechanisms of GNUs, GMPs, and GBFs in the different systems were also investigated and discussed. We found that the formation mechanism of GNUs and GBFs followed classical crystallization, while the formation of GMPs followed non-classical crystallization.

Microphthalmia-associated transcription factor/T-box factor-2 axis acts through Cyclin D1 to regulate melanocyte proliferation

OBJECTIVES

Control of cell proliferation is critical for accurate cell differentiation and tissue formation, during development and regeneration. Here, we have analysed the role of microphthalmia-associated transcription factor MITF and its direct target, T-box factor TBX2, in regulating proliferation of mammalian neural crest-derived melanocytes.

MATERIALS AND METHODS

Immunohistochemistry was used to examine spatial and temporal expression of TBX2 in melanocytes in vivo. RNAi and cell proliferation analysis were used to investigate functional roles of TBX2. Furthermore, quantitative RT-PCR, western blot analysis and flow cytometry were used to further scrutinize molecular mechanisms underlying TBX2-dependent cell proliferation.

RESULTS

TBX2 was found to be co-expressed with MITF in melanocytes of mouse hair follicles. Specific Tbx2 knockdown in primary neural crest cells led to inhibition MITF-positive melanoblast proliferation. Tbx2 knockdown in melan-a cells led to reduction in Cyclin D1 expression and G1-phase cell cycle arrest. TBX2 directly activated Ccnd1 transcription by binding to a specific sequence in the Ccnd1 promoter, and the defect in cell proliferation could be rescued partially by overexpression of Cyclin D1 in Tbx2 knockdown melanocytes.

CONCLUSIONS

Results suggest that the Mitf-Tbx2-Cyclin D1 pathway played an important role in regulation of melanocyte proliferation, and provided novel insights into the complex physiology of melanocytes.

Low-temperature storage and cryopreservation of grapefruit (Citrus paradisi Macfad.) seeds

BACKGROUND

Grapefruit is an economically important fruit worldwide, but our knowledge of its seed biology is rather poor.

OBJECTIVE

The present study aimed to develop techniques for banking and cryopreservation of grapefruit seeds.

MATERIALS AND METHODS

Grapefruit seeds with the exotesta removed were used. Seeds were desiccated to three moisture levels between 5-9 % and stored at 15 degree C, 4 degree C and -20 degree C for up to 24, months to investigate seed lifespan in conventional seed bank. Meanwhile seeds desiccated by silica gel or saturated salt solution and embryonic axes by flash drying were employed to develop cryopreservation protocols.

RESULTS

It was confirmed that grapefruit seeds have some intermediate properties, being able to withstand removal of type II water up to 7 % MC, but sensitive to -20 degree C storage. For cryopreservation, the excised embryonic axes had a wider moisture window between 5 % and 15%, with a maximum past-thaw emergence of 95 %, while seeds survived only with a maximum past-thaw emergence of 50 % or 70 % from a much narrow moisture window.

CONCLUSION

In contrast to previous reports on another type II seed, coffee, we found that citrus seeds desiccated by silica gel had better post-thaw viability than those subjected to equilibrium desiccation with saturated salt solutions. Further investigation is required to elucidate the mechanisms that contribute to variable cryopreservation tolerance.

Reduced graphene oxides: the thinnest and most lightweight materials with highly efficient microwave attenuation performances of the carbon world

In this work, reduced graphene oxide (r-GO) and graphite nanosheet (GN) were obtained via the chemical approach. Furthermore, r-GO composites and GN composites were prepared with a paraffin wax host. r-GO composites show high dielectric properties and electromagnetic interference shielding efficiency (EMI SE). Compared with the GN composites, the loss tangent and EMI SE of the r-GO composites with the same mass ratio are enhanced ∼5 to 10 times and ∼3 to 10 times, respectively. The enhanced attenuation capacity arises from higher specific surface area, clustered defects and residual bonds of the r-GOs, which increase the polarization loss, scattering and conductivity of the composite. Moreover, the higher conductivity of r-GO composites leads to higher EMI SE compared with that of GN composites. These results suggest that r-GOs are highly promising fillers for microwave attenuation in the carbon family and that r-GO composites are high-performance EMI shielding materials with application anticipated to many fields.

Effect of silencing the two major tomato fruit pectin methylesterase isoforms on cell wall pectin metabolism

Post-harvest storage is largely limited by fruit softening, a result of cell wall degradation. Pectin methylesterase (PE) (EC 3.1.1.11) is a major hydrolase responsible for pectin de-esterification in the cell wall, a response to fruit ripening. Two major PE isoforms, PE1 and PE2, have been isolated from tomato (Solanum lycopersicon) pericarp tissue and both have previously been down-regulated using antisense suppression. In this paper, PE1 and PE2 double antisense tomato plants were successfully generated through crossing the two single antisense lines. In the double antisense fruit, approximately 10% of normal PE activity remained and ripening associated pectin de-esterification was almost completely blocked. However, double antisense fruit softened normally during ripening. In tomato fruit, the PE1 isoform was found to contribute little to total PE activity and have little effect on the degree of esterification of pectin. In contrast, the other dominant fruit isoform, PE2, has a major impact on de-esterification of total pectin. PE2 appears to act on non-CDTA-soluble pectin during ripening and on CDTA-soluble pectin before the start of ripening in a potentially block-wise fashion.

Critical behavior of a strongly interacting 2D electron system

With decreasing density n(s) the thermopower S of a low-disorder two-dimensional electron system in silicon is found to exhibit a sharp increase by more than an order of magnitude tending to a divergence at a finite disorder-independent density n(t) consistent with the critical form (-T/S) is proportional to (n(s)-n(t))(x) with x=1.0±0.1 (T is the temperature). Our results provide clear evidence for an interaction-induced transition to a new phase at low density in a strongly interacting 2D electron system.

Epigenetic memory in induced pluripotent stem cells

Somatic cell nuclear transfer and transcription-factor-based reprogramming revert adult cells to an embryonic state, and yield pluripotent stem cells that can generate all tissues. Through different mechanisms and kinetics, these two reprogramming methods reset genomic methylation, an epigenetic modification of DNA that influences gene expression, leading us to hypothesize that the resulting pluripotent stem cells might have different properties. Here we observe that low-passage induced pluripotent stem cells (iPSCs) derived by factor-based reprogramming of adult murine tissues harbour residual DNA methylation signatures characteristic of their somatic tissue of origin, which favours their differentiation along lineages related to the donor cell, while restricting alternative cell fates. Such an 'epigenetic memory' of the donor tissue could be reset by differentiation and serial reprogramming, or by treatment of iPSCs with chromatin-modifying drugs. In contrast, the differentiation and methylation of nuclear-transfer-derived pluripotent stem cells were more similar to classical embryonic stem cells than were iPSCs. Our data indicate that nuclear transfer is more effective at establishing the ground state of pluripotency than factor-based reprogramming, which can leave an epigenetic memory of the tissue of origin that may influence efforts at directed differentiation for applications in disease modelling or treatment.

The structure of the NO(X (2)Pi)-N(2) complex: A joint experimental-theoretical study

We report the first measurement of the spectrum of the NO-N(2) complex in the region of the first vibrational NO overtone transition. The origin band of the complex is blueshifted by 0.30 cm(-1) from the corresponding NO monomer frequency. The observed spectrum consists of three bands assigned to the origin band, the excitation of one quantum of z-axis rotation and one associated hot band. The spacing of the bands and the rotational structure indicate a T-shaped vibrationally averaged structure with the NO molecule forming the top of the T. These findings are confirmed by high level ab initio calculations of the potential energy surfaces in planar symmetry. The deepest minimum is found for a T-shaped geometry on the A(")-surface. As a result the sum potential also has the global minimum for this structure. The different potential surfaces show several additional local minima at slightly higher energies indicating that the complex most likely will perform large amplitude motion even in its ground vibrational state. Nevertheless, as suggested by the measured spectra, the complex must, on average, spend a substantial amount of time near the T-shaped configuration.

Critical moisture content windows differ for the cryopreservation of pomelo (Citrus grandis) seeds and embryonic axes

Cryopreservation was attempted using a partial dehydration and freezing protocol on pomelo (Citrus grandis) seeds of ten cultivars and embryonic axes of one cultivar collected from Xishuangbanna. Although seeds of all ten cultivars could be dehydrated safely to 10 percent moisture content, further dehydration impaired seed viability with critical moisture contents ranging from 9 percent to 7 percent. Complete seedling regenerated from seeds frozen in a moisture window between 5-9 percent, and maximum seedling recovery varied between 22-86 percent. Cryopreservation of Jiajieyou cv. embryonic axes had a moisture window between 3-20 percent , much wider compared to whole seed cryopreservation, and maximum post-thaw emergence of 93 percent was achieved at 13 percent moisture content. Emergence differed only slightly from survival when whole seeds were cryopreserved, but for the embryonic axis cryopreservation at low moisture contents resulted in much lower emergence than survival. Possible causes of intraspecific variation in cryotolerance in pomelo seeds is discussed.

The near IR spectrum of the NO(X(2)Pi)-CH4 complex

We report the first measurement of the near IR spectrum of the NO-CH(4) complex in the region of the first vibrational NO overtone transition in an IR-resonance enhanced multiphoton ionization double resonance experiment. The origin band is located at 3723.26 cm(-1), i.e., redshifted by 0.59 cm(-1) from the corresponding NO monomer frequency. The observed spectrum consists of two bands assigned to the origin band and the excitation of hindered rotation of the NO monomer in the complex similar to z-axis rotation. The spacing and the relative intensity of the bands are consistent with a structure in which NO resides preferentially in a position perpendicular to the intermolecular axis. The deviation from the linear configuration with C(3v) symmetry can be regarded as a Jahn-Teller (JT) distortion. Each band is dominated by two broad peaks with a few resolved rotational structures. The large spacing between the two peaks is indicative of significant angular momentum quenching, possibly another manifestation of the JT effect. The delay dependence between the IR and UV laser pulses reveals a lifetime of about 10 ns for the vibrationally excited complex due to vibrational predissociation. On the other hand, the linewidth of the narrowest spectral features indicates a much shorter excited state lifetime of about 100 ps, most likely due to intramolecular vibrational redistribution.

A Frequent Partial AZFc Deletion does not Render an Increased Risk of Spermatogenic Impairment in East Asians

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.