Production of Bioactive Porcine Lactoferrin through a Novel Glucose-Inducible Expression System in Pichia pastoris: Unveiling Antimicrobial and Anticancer Functionalities

Lactoferrin (LF) stands as one of the extensively investigated iron-binding glycoproteins within milk, exhibiting diverse biological functionalities. The global demand for LF has experienced consistent growth. Biotechnological strategies aimed at enhancing LF productivity through microbial expression systems offer substantial cost-effective advantages and exhibit fewer constraints compared to traditional animal bioreactor technologies. This study devised a novel recombinant plasmid, wherein the AOX1 promoter was replaced with a glucose-inducible G1 promoter (PG1) to govern the expression of recombinant porcine LF (rpLF) in Pichia pastoris GS115. High-copy-number PG1-rpLF yeast clones were meticulously selected, and subsequent induction with 0.05 g/L glucose demonstrated robust secretion of rpLF. Scaling up production transpired in a 5 L fermenter, yielding an estimated rpLF productivity of approximately 2.8 g/L by the conclusion of glycerol-fed fermentation. A three-step purification process involving tangential-flow ultrafiltration yielded approximately 6.55 g of rpLF crude (approximately 85% purity). Notably, exceptional purity of rpLF was achieved through sequential heparin and size-exclusion column purification. Comparatively, the present glucose-inducible system outperformed our previous methanol-induced system, which yielded a level of 87 mg/L of extracellular rpLF secretion. Furthermore, yeast-produced rpLF demonstrated affinity for ferric ions (Fe3+) and exhibited growth inhibition against various pathogenic microbes (E. coli, S. aureus, and C. albicans) and human cancer cells (A549, MDA-MB-231, and Hep3B), similar to commercial bovine LF (bLF). Intriguingly, the hydrolysate of rpLF (rpLFH) manifested heightened antimicrobial and anticancer effects compared to its intact form. In conclusion, this study presents an efficient glucose-inducible yeast expression system for large-scale production and purification of active rpLF protein with the potential for veterinary or medical applications.

Effects of Recloning on the Telomere Lengths of Mouse Terc+/- Nuclear Transfer-Derived Embryonic Stem Cells

Haploinsufficiency of genes that participate in the telomere elongation and maintenance processes, such as Terc and Tert, often lead to premature aging related diseases such as dyskeratosis congenita and aplastic anemia. Previously we reported that when mouse Terc+/- tail tip fibroblasts (TTFs) were used as the donor cells for somatic cell nuclear transfer (SCNT, also known as "cloning"), the derivative embryonic stem cells (ntESCs) had elongated telomeres. In the present work, we are interested to know if an additional round of SCNT, or recloning, could bring further elongation of the telomeres. Terc+/- TTFs were used to derive the first generation (G1) ntESCs, followed by a second round SCNT using G1-Terc+/- ntESCs as donor cells to derive G2-Tert+/- ntESCs. Multiple lines of G1- and G2-Terc+/- ntESCs were efficiently established, and all expressed major pluripotent markers and supported efficient chondrocyte differentiation in vitro. Comparing to the donor TTFs, telomere lengths of G1-ntESCs were elongated to the level comparable to that in wildtype ntESCs. Interestingly, recloning did not further elongate telomere lengths of the Terc+/- ntESCs. Together, our work demonstrates that while a single round of SCNT is a viable means to reprogram Terc haploinsufficient cells to the ESC state, and to elongate these cells' telomere lengths, a second round of SCNT does not necessarily further elongate the telomeres.

Cruciform DNA Structures Act as Legible Templates for Accelerating Homologous Recombination in Transgenic Animals

Inverted repeat (IR) DNA sequences compose cruciform structures. Some genetic disorders are the result of genome inversion or translocation by cruciform DNA structures. The present study examined whether exogenous DNA integration into the chromosomes of transgenic animals was related to cruciform DNA structures. Large imperfect cruciform structures were frequently predicted around predestinated transgene integration sites in host genomes of microinjection-based transgenic (Tg) animals (αLA-LPH Tg goat, Akr1A1eGFP/eGFP Tg mouse, and NFκB-Luc Tg mouse) or CRISPR/Cas9 gene-editing (GE) animals (αLA-AP1 GE mouse). Transgene cassettes were imperfectly matched with their predestinated sequences. According to the analyzed data, we proposed a putative model in which the flexible cruciform DNA structures acted as a legible template for DNA integration into linear DNAs or double-strand break (DSB) alleles. To demonstrate this model, artificial inverted repeat knock-in (KI) reporter plasmids were created to analyze the KI rate using the CRISPR/Cas9 system in NIH3T3 cells. Notably, the KI rate of the 5′ homologous arm inverted repeat donor plasmid (5′IR) with the ROSA gRNA group (31.5%) was significantly higher than the knock-in reporter donor plasmid (KIR) with the ROSA gRNA group (21.3%, p < 0.05). However, the KI rate of the 3′ inverted terminal repeat/inverted repeat donor plasmid (3′ITRIR) group was not different from the KIR group (23.0% vs. 22.0%). These results demonstrated that the legibility of the sequence with the cruciform DNA existing in the transgene promoted homologous recombination (HR) with a higher KI rate. Our findings suggest that flexible cruciform DNAs folded by IR sequences improve the legibility and accelerate DNA 3′-overhang integration into the host genome via homologous recombination machinery.

STAT3 Is an Upstream Regulator of Granzyme G in the Maternal-To-Zygotic Transition of Mouse Embryos

The maternal-to-zygotic transition (MZT), which controls maternal signaling to synthesize zygotic gene products, promotes the preimplantation development of mouse zygotes to the two-cell stage. Our previous study reported that mouse granzyme g (Gzmg), a serine-type protease, is required for the MZT. In this study, we further identified the maternal factors that regulate the Gzmg promoter activity in the zygote to the two-cell stage of mouse embryos. A full-length Gzmg promoter from mouse genomic DNA, FL-pGzmg (−1696~+28 nt), was cloned, and four deletion constructs of this Gzmg promoter, Δ1-pGzmg (−1369~+28 nt), Δ2-pGzmg (−939~+28 nt), Δ3-pGzmg (−711~+28 nt) and Δ4-pGzmg (−417~+28 nt), were subsequently generated. Different-sized Gzmg promoters were used to perform promoter assays of mouse zygotes and two-cell stage embryos. The results showed that Δ4-pGzmg promoted the highest expression level of the enhanced green fluorescent protein (EGFP) reporter in the zygotes and two-cell embryos. The data suggested that time-specific transcription factors upregulated Gzmg by binding cis-elements in the −417~+28-nt Gzmg promoter region. According to the results of the promoter assay, the transcription factor binding sites were predicted and analyzed with the JASPAR database, and two transcription factors, signal transducer and activator of transcription 3 (STAT3) and GA-binding protein alpha (GABPα), were identified. Furthermore, STAT3 and GABPα are expressed and located in zygote pronuclei and two-cell nuclei were confirmed by immunofluorescence staining; however, only STAT3 was recruited to the mouse zygote pronuclei and two-cell nuclei injected with the Δ4-pGzmg reporter construct. These data indicated that STAT3 is a maternal transcription factor and may upregulate Gzmg to promote the MZT. Furthermore, treatment with a STAT3 inhibitor, S3I-201, caused mouse embryonic arrest at the zygote and two-cell stages. These results suggest that STAT3, a maternal protein, is a critical transcription factor and regulates Gzmg transcription activity in preimplantation mouse embryos. It plays an important role in the maternal-to-zygotic transition during early embryonic development.

A mini-pig model for evaluating the efficacy of autologous platelet patches on induced acute full thickness wound healing

Background

Autologous platelet concentrates are currently widely used across different areas of regenerative medicine in order to enhance the wound healing process. Although several protocols for platelet concentrates are available, their application remains difficult due to different protocols leading to distinct products with vary potential biological uses. In this study, we attempted to make a platelet patch (PP) using mixtures of platelet rich plasma (PRP) injection and platelet rich fibrin (PRF) to promote wound repair and regeneration.

Results

Experiments were performed using a full-thickness wound model in mini-pigs. Autologous PRP, PRF and PP were prepared immediately before creating four full-thickness skin wounds in pigs. We quantified concentrations of platelets, thrombin and various growth factors to ensure that the desired effect can be produced. After surgery, hydrocolloid dressing, PRP injection, PRF and PP was applied to experimentally induced wounds. Application efficacy was evaluated by measurement of wound sizes and histological examination. The results indicated that all wounds showed a significant size reduction. Wound repair efficacy in response to PP treatment exhibited enhanced re-epithelialization compared to PRP and PRF (P < 0.05) and higher wound contraction than did PRF application (P < 0.05). Another aspect, experiment using DsRed transgenic pigs as blood donors demonstrated that leucocytes in PP were incorporated into the wound bed at the end of the study, suggesting that leucocytes activity is stimulated in response to PP application. Safety of the experimental processes was also confirmed by examination of organ biopsies.

Conclusions

We used a mini-pig model to evaluate the efficacy of lab-made PP on induced full-thickness wound healing. Results demonstrated that application of one piece of PP was enough to obtain comparable efficacy versus general utilization of PRP or PRF for wound care. We also demonstrated that leucocytes in PP were incorporated into the wound bed and no safety concerns have been found in the whole experiment. This study provides a novel and feasible method for veterinary or clinical wound care.

Sunscreen formulations may serve as additional water barrier on skin surface: a clinical assessment

OBJECTIVES

Extended water exposure can cause stratum corneum swelling and a more porous skin barrier. People often wear water-resistant sunscreen formulations during extended period of water activities in the summer to protect skin from harmful UV rays. We wanted to evaluate whether sunscreen formulations can also serve as additional water barriers to help mitigate the disruption in stratum corneum caused by constant exposure to water.

METHODS

We conducted trans-epidermal water loss (TEWL) measurement in a controlled water patch (including salt and chlorine water) model and then applied this relevant model to study the effects of pre-treatments of sunscreen sprays and stick. We also conducted water sorption-desorption test in vivo with and without sunscreens. Finally, we studied the effect of constant water exposure combined with a known irritant, sodium lauryl sulphate (SLS), in a randomized clinical trial.

RESULTS

We found that application of sunscreen formulations help mitigate water-induced barrier disruption by repelling water at skin surface. Pre-treatment of sunscreen also statistically decreased the irritation in an acute patch test model.

CONCLUSIONS

Hydrophobic sunscreen formulations can help protect skin from extended water exposure by serving as additional water barriers.

Telomere elongation and naive pluripotent stem cells achieved from telomerase haplo-insufficient cells by somatic cell nuclear transfer

Haplo-insufficiency of telomerase genes in humans leads to telomere syndromes such as dyskeratosis congenital and idiopathic pulmonary fibrosis. Generation of pluripotent stem cells from telomerase haplo-insufficient donor cells would provide unique opportunities toward the realization of patient-specific stem cell therapies. Recently, pluripotent human embryonic stem cells (ntESCs) have been efficiently achieved by somatic cell nuclear transfer (SCNT). We tested the hypothesis that SCNT could effectively elongate shortening telomeres of telomerase haplo-insufficient cells in the ntESCs with relevant mouse models. Indeed, telomeres of telomerase haplo-insufficient (Terc(+/-)) mouse cells are elongated in ntESCs. Moreover, ntESCs derived from Terc(+/-) cells exhibit naive pluripotency as evidenced by generation of Terc(+/-) ntESC clone pups by tetraploid embryo complementation, the most stringent test of naive pluripotency. These data suggest that SCNT could offer a powerful tool to reprogram telomeres and to discover the factors for robust restoration of telomeres and pluripotency of telomerase haplo-insufficient somatic cells.

Impact of strain engineering on nanoscale strained III-V PMOSFETs

Stress distributions in the strained InGaAs PMOSFET with source/drain (S/D) stressors for various lengths and widths were studied with 3D stress simulations. The resulting mobility improvement was analyzed. Compressive stress along the transport direction was found to dominate the hole mobility improvement for the wide width devices. Stress along the vertical direction perpendicular to the gate oxide was found to affect the mobility the least, while stress along the width direction enhanced in the middle wide width region. The impact of channel width and length on performance improvements such as the mobility gain was analyzed using the Kubo-Greenwood formalism accounting for nonpolar hole-phonon scattering (acoustic and optical), surface roughness scattering, polar phonon scattering, alloy scattering and remote phonon scattering. The novelty of this paper is studying the impact of channel width and length on the performance of InGaAs PMOSFET such as mobility and exploring physical insight for scaling the future III-V CMOS devices.

Rapid, accurate genotyping of the common -alpha(4.2) thalassaemia deletion based on the use of denaturing HPLC

AIMS

To develop an alternative assay for specific genotyping of the -alpha(4.2) thalassaemia deletion based on the DNA sequence features surrounding the breakpoint.

METHODS

The 5' and 3' ends of the breakpoint regions of the -alpha(4.2) allele and the normal homologous segments were sequenced in Chinese individuals. A sequence haplotype composed of four single nucleotide variations within the X2/X1 box of the -alpha(4.2) breakpoint region was found in all of the 10 Chinese -alpha(4.2) thalassaemia alleles studied. Based on these findings, a novel polymerase chain reaction (PCR)/denaturing high performance liquid chromatography (DHPLC) assay was developed for rapid genotyping of the -alpha(4.2) allele instead of traditional Southern blotting or Gap-PCR. This method involves amplification of the alpha globin target sequence encompassing these four polymorphic sites, followed by a partially denaturing HPLC analysis using the transgenomic WAVE DNA fragment analysis system.

RESULTS

The three major genotypes (-alpha4.2/alphaalpha, -alpha(4.2)/--SEA, and alphaalpha/alphaalpha) could be distinguished through the characteristic chromatograms generated by the WAVE system. The accuracy of this technique was evaluated blindly, and the results were 100% (40 of 40) concordant with the genotypes previously characterised by Southern blotting or Gap-PCR.

CONCLUSIONS

This study validates the PCR/DHPLC approach as a simple, rapid, highly accurate, and cost effective method, potentially adaptable for use in epidemiological surveys, genetic screening, and diagnosis of silent alpha+ thalassaemia and Hb H disease.

Diurnal and seasonal variations of the UV cut-off wavelength and most erythemally effective wavelength of solar spectra

BACKGROUND

Biologically effective solar ultraviolet radiation is defined as the product of the intensity of the solar spectrum and the erythema action spectrum at each wavelength. In this way we may arrive at the weighted effectiveness of each wavelength of solar radiation to produce a sunburn reaction. There have been many measurements of the variation of the solar spectrum with the time of the day and the time of the year, but questions remain as to the variation of the quality of the spectrum and the contribution of the shortest wavelengths of solar terrestrial radiation. The purpose of the present study was to determine the variation of the biologically effective solar spectrum with the time of the day and the time of the year and to determine the variation of the shortest wavelength that contributes to the sunburn reaction with the time of the day and the time of the year.

METHODS

Spectroradiometric measurements were made at ground level over the period of one year (1988-1989) and at different times of the day at latitude 29.5 degrees north. The measured spectral irradiance was multiplied wavelength by wavelength by the erythema action spectra.

RESULTS

We determined that the biologically effective solar spectrum remains essentially the same over the times of the day that sunburn may be experienced. The maximally effective wavelength of biologically effective solar radiation was determined to be 308 nm. The cut-off wavelength for biologically effective solar radiation (defined as the wavelength at which the biologically effective solar radiation is at 1% of its maximum) varied from 291 to 295 nm over the time of the year and from 292 to 296 nm over the day.

CONCLUSION

For all practical purposes the biologically effective spectrum of solar ultraviolet radiation may be considered to remain constant over the period when sunburn may occur and the minimal wavelength of sunlight that contributes to sunburn is in the range of 291-296 nm.

Infrared microscopic imaging of bone: spatial distribution of CO3(2-)

This article describes a novel technology for quantitative determination of the spatial distribution of CO3(2-) substitution in bone mineral using infrared (IR) imaging at approximately 6 microm spatial resolution. This novel technology consists of an IR array detector of 64 x 64 elements mapped to a 400 microm x 400 microm spot at the focal plane of an IR microscope. During each scan, a complete IR spectrum is acquired from each element in the array. The variation of any IR parameter across the array may be mapped. In the current study, a linear relationship was observed between the band area or the peak height ratio of the CO3(2-) v3 contour at 1415 cm(-1) to the PO4(3-) v1,v3 contour in a series of synthetic carbonated apatites. The correlation coefficient between the spectroscopically and analytically determined ratios (R2 = 0.989) attests to the practical utility of this IR area ratio for determination of bone CO3(2-) levels. The relationship forms the basis for the determination of CO3(2-) in tissue sections using IR imaging. In four images of trabecular bone the average CO3(2-) levels were 5.95 wt% (2298 data points), 6.67% (2040 data points), 6.66% (1176 data points), and 6.73% (2256 data points) with an overall average of 6.38+/-0.14% (7770 data points). The highest levels of CO3(2-) were found at the edge of the trabeculae and immediately adjacent to the Haversian canal. Examination of parameters derived from the phosphate v1,v3 contour of the synthetic apatites revealed that the crystallinity/perfection of the hydroxyapatite (HA) crystals was diminished as CO3(2-) levels increased. The methodology described will permit evaluation of the spatial distribution of CO3(2-) levels in diseased and normal mineralized tissues.

Two-dimensional vibrational correlation spectroscopy of in vitro hydroxyapatite maturation

Two-dimensional (2-D) Raman and 2-D IR correlation spectroscopy are applied to analyze changes in the nu(4) region of the IR spectrum and in the nu(1) region of the Raman spectrum during the maturation of hydroxyapatite (HA) following the solution-mediated conversion of amorphous calcium phosphate (ACP) to HA. The nu(1) region of the Raman spectrum exhibits a frequency shift and sharpening during the maturation. Comparison of the experimental and simulated 2-D plots for this process suggests that the shift of a single peak, rather than a change in the relative intensity of two overlapped bands, is responsible for the observed spectral changes. The nu(4) mode of the PO(3-)(4) ion (T(2) symmetry in the free species) splits into a triplet with components near 563, 575, and 603 cm(-1) in HA. In addition, broad features appear at 540 and 617 cm(-1). During the latest stages of the maturation, an OH(-) librational mode develops at approximately 632 cm(-1). Changes in the relative intensities of three components of the nu(4) mode are not all correlated with each other. The synchronous 2-D plots reveal that the 563 and 603 cm(-1) pair are positively correlated while the feature at 575 cm(-1) is absent. A 587 cm(-1) mode arising from ACP is negatively correlated with the 563 and 603 cm(-1) pair and is both synchronously (positively) and asynchronously correlated with the 540 cm(-1) feature during the early stages of the maturation but is absent from 2-D plots of the later stages of the maturation. Cross correlations between the nu(4) mode and the nu(1),nu(3) contour generally confirm and extend previous assignments for the latter spectral region. Finally, the suitability of the 2-D approach for analysis of IR spectral images is examined through studies of HA crystallinity in a human iliac crest biopsy sample. Trabecular bone contains a fraction of HA that is more crystalline and mature than could be achieved in vitro during the room temperature ACP --> HA interconversion.